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putty/ssh.c

6214 строки
181 KiB
C
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#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <assert.h>
#include "putty.h"
#include "tree234.h"
#include "ssh.h"
#ifndef FALSE
#define FALSE 0
#endif
#ifndef TRUE
#define TRUE 1
#endif
#define SSH1_MSG_DISCONNECT 1 /* 0x1 */
#define SSH1_SMSG_PUBLIC_KEY 2 /* 0x2 */
#define SSH1_CMSG_SESSION_KEY 3 /* 0x3 */
#define SSH1_CMSG_USER 4 /* 0x4 */
#define SSH1_CMSG_AUTH_RSA 6 /* 0x6 */
#define SSH1_SMSG_AUTH_RSA_CHALLENGE 7 /* 0x7 */
#define SSH1_CMSG_AUTH_RSA_RESPONSE 8 /* 0x8 */
#define SSH1_CMSG_AUTH_PASSWORD 9 /* 0x9 */
#define SSH1_CMSG_REQUEST_PTY 10 /* 0xa */
#define SSH1_CMSG_WINDOW_SIZE 11 /* 0xb */
#define SSH1_CMSG_EXEC_SHELL 12 /* 0xc */
#define SSH1_CMSG_EXEC_CMD 13 /* 0xd */
#define SSH1_SMSG_SUCCESS 14 /* 0xe */
#define SSH1_SMSG_FAILURE 15 /* 0xf */
#define SSH1_CMSG_STDIN_DATA 16 /* 0x10 */
#define SSH1_SMSG_STDOUT_DATA 17 /* 0x11 */
#define SSH1_SMSG_STDERR_DATA 18 /* 0x12 */
#define SSH1_CMSG_EOF 19 /* 0x13 */
#define SSH1_SMSG_EXIT_STATUS 20 /* 0x14 */
#define SSH1_MSG_CHANNEL_OPEN_CONFIRMATION 21 /* 0x15 */
#define SSH1_MSG_CHANNEL_OPEN_FAILURE 22 /* 0x16 */
#define SSH1_MSG_CHANNEL_DATA 23 /* 0x17 */
#define SSH1_MSG_CHANNEL_CLOSE 24 /* 0x18 */
#define SSH1_MSG_CHANNEL_CLOSE_CONFIRMATION 25 /* 0x19 */
#define SSH1_SMSG_X11_OPEN 27 /* 0x1b */
#define SSH1_CMSG_PORT_FORWARD_REQUEST 28 /* 0x1c */
#define SSH1_MSG_PORT_OPEN 29 /* 0x1d */
#define SSH1_CMSG_AGENT_REQUEST_FORWARDING 30 /* 0x1e */
#define SSH1_SMSG_AGENT_OPEN 31 /* 0x1f */
#define SSH1_MSG_IGNORE 32 /* 0x20 */
#define SSH1_CMSG_EXIT_CONFIRMATION 33 /* 0x21 */
#define SSH1_CMSG_X11_REQUEST_FORWARDING 34 /* 0x22 */
#define SSH1_CMSG_AUTH_RHOSTS_RSA 35 /* 0x23 */
#define SSH1_MSG_DEBUG 36 /* 0x24 */
#define SSH1_CMSG_REQUEST_COMPRESSION 37 /* 0x25 */
#define SSH1_CMSG_AUTH_TIS 39 /* 0x27 */
#define SSH1_SMSG_AUTH_TIS_CHALLENGE 40 /* 0x28 */
#define SSH1_CMSG_AUTH_TIS_RESPONSE 41 /* 0x29 */
#define SSH1_CMSG_AUTH_CCARD 70 /* 0x46 */
#define SSH1_SMSG_AUTH_CCARD_CHALLENGE 71 /* 0x47 */
#define SSH1_CMSG_AUTH_CCARD_RESPONSE 72 /* 0x48 */
#define SSH1_AUTH_TIS 5 /* 0x5 */
#define SSH1_AUTH_CCARD 16 /* 0x10 */
#define SSH1_PROTOFLAG_SCREEN_NUMBER 1 /* 0x1 */
/* Mask for protoflags we will echo back to server if seen */
#define SSH1_PROTOFLAGS_SUPPORTED 0 /* 0x1 */
#define SSH2_MSG_DISCONNECT 1 /* 0x1 */
#define SSH2_MSG_IGNORE 2 /* 0x2 */
#define SSH2_MSG_UNIMPLEMENTED 3 /* 0x3 */
#define SSH2_MSG_DEBUG 4 /* 0x4 */
#define SSH2_MSG_SERVICE_REQUEST 5 /* 0x5 */
#define SSH2_MSG_SERVICE_ACCEPT 6 /* 0x6 */
#define SSH2_MSG_KEXINIT 20 /* 0x14 */
#define SSH2_MSG_NEWKEYS 21 /* 0x15 */
#define SSH2_MSG_KEXDH_INIT 30 /* 0x1e */
#define SSH2_MSG_KEXDH_REPLY 31 /* 0x1f */
#define SSH2_MSG_KEX_DH_GEX_REQUEST 30 /* 0x1e */
#define SSH2_MSG_KEX_DH_GEX_GROUP 31 /* 0x1f */
#define SSH2_MSG_KEX_DH_GEX_INIT 32 /* 0x20 */
#define SSH2_MSG_KEX_DH_GEX_REPLY 33 /* 0x21 */
#define SSH2_MSG_USERAUTH_REQUEST 50 /* 0x32 */
#define SSH2_MSG_USERAUTH_FAILURE 51 /* 0x33 */
#define SSH2_MSG_USERAUTH_SUCCESS 52 /* 0x34 */
#define SSH2_MSG_USERAUTH_BANNER 53 /* 0x35 */
#define SSH2_MSG_USERAUTH_PK_OK 60 /* 0x3c */
#define SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ 60 /* 0x3c */
#define SSH2_MSG_USERAUTH_INFO_REQUEST 60 /* 0x3c */
#define SSH2_MSG_USERAUTH_INFO_RESPONSE 61 /* 0x3d */
#define SSH2_MSG_GLOBAL_REQUEST 80 /* 0x50 */
#define SSH2_MSG_REQUEST_SUCCESS 81 /* 0x51 */
#define SSH2_MSG_REQUEST_FAILURE 82 /* 0x52 */
#define SSH2_MSG_CHANNEL_OPEN 90 /* 0x5a */
#define SSH2_MSG_CHANNEL_OPEN_CONFIRMATION 91 /* 0x5b */
#define SSH2_MSG_CHANNEL_OPEN_FAILURE 92 /* 0x5c */
#define SSH2_MSG_CHANNEL_WINDOW_ADJUST 93 /* 0x5d */
#define SSH2_MSG_CHANNEL_DATA 94 /* 0x5e */
#define SSH2_MSG_CHANNEL_EXTENDED_DATA 95 /* 0x5f */
#define SSH2_MSG_CHANNEL_EOF 96 /* 0x60 */
#define SSH2_MSG_CHANNEL_CLOSE 97 /* 0x61 */
#define SSH2_MSG_CHANNEL_REQUEST 98 /* 0x62 */
#define SSH2_MSG_CHANNEL_SUCCESS 99 /* 0x63 */
#define SSH2_MSG_CHANNEL_FAILURE 100 /* 0x64 */
/*
* Packet type contexts, so that ssh2_pkt_type can correctly decode
* the ambiguous type numbers back into the correct type strings.
*/
#define SSH2_PKTCTX_DHGROUP1 0x0001
#define SSH2_PKTCTX_DHGEX 0x0002
#define SSH2_PKTCTX_PUBLICKEY 0x0010
#define SSH2_PKTCTX_PASSWORD 0x0020
#define SSH2_PKTCTX_KBDINTER 0x0040
#define SSH2_PKTCTX_AUTH_MASK 0x00F0
#define SSH2_DISCONNECT_HOST_NOT_ALLOWED_TO_CONNECT 1 /* 0x1 */
#define SSH2_DISCONNECT_PROTOCOL_ERROR 2 /* 0x2 */
#define SSH2_DISCONNECT_KEY_EXCHANGE_FAILED 3 /* 0x3 */
#define SSH2_DISCONNECT_HOST_AUTHENTICATION_FAILED 4 /* 0x4 */
#define SSH2_DISCONNECT_MAC_ERROR 5 /* 0x5 */
#define SSH2_DISCONNECT_COMPRESSION_ERROR 6 /* 0x6 */
#define SSH2_DISCONNECT_SERVICE_NOT_AVAILABLE 7 /* 0x7 */
#define SSH2_DISCONNECT_PROTOCOL_VERSION_NOT_SUPPORTED 8 /* 0x8 */
#define SSH2_DISCONNECT_HOST_KEY_NOT_VERIFIABLE 9 /* 0x9 */
#define SSH2_DISCONNECT_CONNECTION_LOST 10 /* 0xa */
#define SSH2_DISCONNECT_BY_APPLICATION 11 /* 0xb */
#define SSH2_DISCONNECT_TOO_MANY_CONNECTIONS 12 /* 0xc */
#define SSH2_DISCONNECT_AUTH_CANCELLED_BY_USER 13 /* 0xd */
#define SSH2_DISCONNECT_NO_MORE_AUTH_METHODS_AVAILABLE 14 /* 0xe */
#define SSH2_DISCONNECT_ILLEGAL_USER_NAME 15 /* 0xf */
static const char *const ssh2_disconnect_reasons[] = {
NULL,
"SSH_DISCONNECT_HOST_NOT_ALLOWED_TO_CONNECT",
"SSH_DISCONNECT_PROTOCOL_ERROR",
"SSH_DISCONNECT_KEY_EXCHANGE_FAILED",
"SSH_DISCONNECT_HOST_AUTHENTICATION_FAILED",
"SSH_DISCONNECT_MAC_ERROR",
"SSH_DISCONNECT_COMPRESSION_ERROR",
"SSH_DISCONNECT_SERVICE_NOT_AVAILABLE",
"SSH_DISCONNECT_PROTOCOL_VERSION_NOT_SUPPORTED",
"SSH_DISCONNECT_HOST_KEY_NOT_VERIFIABLE",
"SSH_DISCONNECT_CONNECTION_LOST",
"SSH_DISCONNECT_BY_APPLICATION",
"SSH_DISCONNECT_TOO_MANY_CONNECTIONS",
"SSH_DISCONNECT_AUTH_CANCELLED_BY_USER",
"SSH_DISCONNECT_NO_MORE_AUTH_METHODS_AVAILABLE",
"SSH_DISCONNECT_ILLEGAL_USER_NAME",
};
#define SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED 1 /* 0x1 */
#define SSH2_OPEN_CONNECT_FAILED 2 /* 0x2 */
#define SSH2_OPEN_UNKNOWN_CHANNEL_TYPE 3 /* 0x3 */
#define SSH2_OPEN_RESOURCE_SHORTAGE 4 /* 0x4 */
#define SSH2_EXTENDED_DATA_STDERR 1 /* 0x1 */
/*
* Various remote-bug flags.
*/
#define BUG_CHOKES_ON_SSH1_IGNORE 1
#define BUG_SSH2_HMAC 2
#define BUG_NEEDS_SSH1_PLAIN_PASSWORD 4
#define BUG_CHOKES_ON_RSA 8
#define BUG_SSH2_RSA_PADDING 16
#define BUG_SSH2_DERIVEKEY 32
#define BUG_SSH2_DH_GEX 64
#define translate(x) if (type == x) return #x
#define translatec(x,ctx) if (type == x && (pkt_ctx & ctx)) return #x
static char *ssh1_pkt_type(int type)
{
translate(SSH1_MSG_DISCONNECT);
translate(SSH1_SMSG_PUBLIC_KEY);
translate(SSH1_CMSG_SESSION_KEY);
translate(SSH1_CMSG_USER);
translate(SSH1_CMSG_AUTH_RSA);
translate(SSH1_SMSG_AUTH_RSA_CHALLENGE);
translate(SSH1_CMSG_AUTH_RSA_RESPONSE);
translate(SSH1_CMSG_AUTH_PASSWORD);
translate(SSH1_CMSG_REQUEST_PTY);
translate(SSH1_CMSG_WINDOW_SIZE);
translate(SSH1_CMSG_EXEC_SHELL);
translate(SSH1_CMSG_EXEC_CMD);
translate(SSH1_SMSG_SUCCESS);
translate(SSH1_SMSG_FAILURE);
translate(SSH1_CMSG_STDIN_DATA);
translate(SSH1_SMSG_STDOUT_DATA);
translate(SSH1_SMSG_STDERR_DATA);
translate(SSH1_CMSG_EOF);
translate(SSH1_SMSG_EXIT_STATUS);
translate(SSH1_MSG_CHANNEL_OPEN_CONFIRMATION);
translate(SSH1_MSG_CHANNEL_OPEN_FAILURE);
translate(SSH1_MSG_CHANNEL_DATA);
translate(SSH1_MSG_CHANNEL_CLOSE);
translate(SSH1_MSG_CHANNEL_CLOSE_CONFIRMATION);
translate(SSH1_SMSG_X11_OPEN);
translate(SSH1_CMSG_PORT_FORWARD_REQUEST);
translate(SSH1_MSG_PORT_OPEN);
translate(SSH1_CMSG_AGENT_REQUEST_FORWARDING);
translate(SSH1_SMSG_AGENT_OPEN);
translate(SSH1_MSG_IGNORE);
translate(SSH1_CMSG_EXIT_CONFIRMATION);
translate(SSH1_CMSG_X11_REQUEST_FORWARDING);
translate(SSH1_CMSG_AUTH_RHOSTS_RSA);
translate(SSH1_MSG_DEBUG);
translate(SSH1_CMSG_REQUEST_COMPRESSION);
translate(SSH1_CMSG_AUTH_TIS);
translate(SSH1_SMSG_AUTH_TIS_CHALLENGE);
translate(SSH1_CMSG_AUTH_TIS_RESPONSE);
translate(SSH1_CMSG_AUTH_CCARD);
translate(SSH1_SMSG_AUTH_CCARD_CHALLENGE);
translate(SSH1_CMSG_AUTH_CCARD_RESPONSE);
return "unknown";
}
static char *ssh2_pkt_type(int pkt_ctx, int type)
{
translate(SSH2_MSG_DISCONNECT);
translate(SSH2_MSG_IGNORE);
translate(SSH2_MSG_UNIMPLEMENTED);
translate(SSH2_MSG_DEBUG);
translate(SSH2_MSG_SERVICE_REQUEST);
translate(SSH2_MSG_SERVICE_ACCEPT);
translate(SSH2_MSG_KEXINIT);
translate(SSH2_MSG_NEWKEYS);
translatec(SSH2_MSG_KEXDH_INIT, SSH2_PKTCTX_DHGROUP1);
translatec(SSH2_MSG_KEXDH_REPLY, SSH2_PKTCTX_DHGROUP1);
translatec(SSH2_MSG_KEX_DH_GEX_REQUEST, SSH2_PKTCTX_DHGEX);
translatec(SSH2_MSG_KEX_DH_GEX_GROUP, SSH2_PKTCTX_DHGEX);
translatec(SSH2_MSG_KEX_DH_GEX_INIT, SSH2_PKTCTX_DHGEX);
translatec(SSH2_MSG_KEX_DH_GEX_REPLY, SSH2_PKTCTX_DHGEX);
translate(SSH2_MSG_USERAUTH_REQUEST);
translate(SSH2_MSG_USERAUTH_FAILURE);
translate(SSH2_MSG_USERAUTH_SUCCESS);
translate(SSH2_MSG_USERAUTH_BANNER);
translatec(SSH2_MSG_USERAUTH_PK_OK, SSH2_PKTCTX_PUBLICKEY);
translatec(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, SSH2_PKTCTX_PASSWORD);
translatec(SSH2_MSG_USERAUTH_INFO_REQUEST, SSH2_PKTCTX_KBDINTER);
translatec(SSH2_MSG_USERAUTH_INFO_RESPONSE, SSH2_PKTCTX_KBDINTER);
translate(SSH2_MSG_GLOBAL_REQUEST);
translate(SSH2_MSG_REQUEST_SUCCESS);
translate(SSH2_MSG_REQUEST_FAILURE);
translate(SSH2_MSG_CHANNEL_OPEN);
translate(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
translate(SSH2_MSG_CHANNEL_OPEN_FAILURE);
translate(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
translate(SSH2_MSG_CHANNEL_DATA);
translate(SSH2_MSG_CHANNEL_EXTENDED_DATA);
translate(SSH2_MSG_CHANNEL_EOF);
translate(SSH2_MSG_CHANNEL_CLOSE);
translate(SSH2_MSG_CHANNEL_REQUEST);
translate(SSH2_MSG_CHANNEL_SUCCESS);
translate(SSH2_MSG_CHANNEL_FAILURE);
return "unknown";
}
#undef translate
#undef translatec
#define GET_32BIT(cp) \
(((unsigned long)(unsigned char)(cp)[0] << 24) | \
((unsigned long)(unsigned char)(cp)[1] << 16) | \
((unsigned long)(unsigned char)(cp)[2] << 8) | \
((unsigned long)(unsigned char)(cp)[3]))
#define PUT_32BIT(cp, value) { \
(cp)[0] = (unsigned char)((value) >> 24); \
(cp)[1] = (unsigned char)((value) >> 16); \
(cp)[2] = (unsigned char)((value) >> 8); \
(cp)[3] = (unsigned char)(value); }
enum { PKT_END, PKT_INT, PKT_CHAR, PKT_DATA, PKT_STR, PKT_BIGNUM };
/* Coroutine mechanics for the sillier bits of the code */
#define crBegin(v) { int *crLine = &v; switch(v) { case 0:;
#define crState(t) \
struct t *s; \
if (!ssh->t) ssh->t = smalloc(sizeof(struct t)); \
s = ssh->t;
#define crFinish(z) } *crLine = 0; return (z); }
#define crFinishV } *crLine = 0; return; }
#define crReturn(z) \
do {\
*crLine =__LINE__; return (z); case __LINE__:;\
} while (0)
#define crReturnV \
do {\
*crLine=__LINE__; return; case __LINE__:;\
} while (0)
#define crStop(z) do{ *crLine = 0; return (z); }while(0)
#define crStopV do{ *crLine = 0; return; }while(0)
#define crWaitUntil(c) do { crReturn(0); } while (!(c))
#define crWaitUntilV(c) do { crReturnV; } while (!(c))
typedef struct ssh_tag *Ssh;
static void ssh2_pkt_init(Ssh, int pkt_type);
static void ssh2_pkt_addbool(Ssh, unsigned char value);
static void ssh2_pkt_adduint32(Ssh, unsigned long value);
static void ssh2_pkt_addstring_start(Ssh);
static void ssh2_pkt_addstring_str(Ssh, char *data);
static void ssh2_pkt_addstring_data(Ssh, char *data, int len);
static void ssh2_pkt_addstring(Ssh, char *data);
static unsigned char *ssh2_mpint_fmt(Bignum b, int *len);
static void ssh2_pkt_addmp(Ssh, Bignum b);
static int ssh2_pkt_construct(Ssh);
static void ssh2_pkt_send(Ssh);
/*
* Buffer management constants. There are several of these for
* various different purposes:
*
* - SSH1_BUFFER_LIMIT is the amount of backlog that must build up
* on a local data stream before we throttle the whole SSH
* connection (in SSH1 only). Throttling the whole connection is
* pretty drastic so we set this high in the hope it won't
* happen very often.
*
* - SSH_MAX_BACKLOG is the amount of backlog that must build up
* on the SSH connection itself before we defensively throttle
* _all_ local data streams. This is pretty drastic too (though
* thankfully unlikely in SSH2 since the window mechanism should
* ensure that the server never has any need to throttle its end
* of the connection), so we set this high as well.
*
* - OUR_V2_WINSIZE is the maximum window size we present on SSH2
* channels.
*/
#define SSH1_BUFFER_LIMIT 32768
#define SSH_MAX_BACKLOG 32768
#define OUR_V2_WINSIZE 16384
const static struct ssh_kex *kex_algs[] = {
&ssh_diffiehellman_gex,
&ssh_diffiehellman
};
const static struct ssh_signkey *hostkey_algs[] = { &ssh_rsa, &ssh_dss };
static void *nullmac_make_context(void)
{
return NULL;
}
static void nullmac_free_context(void *handle)
{
}
static void nullmac_key(void *handle, unsigned char *key)
{
}
static void nullmac_generate(void *handle, unsigned char *blk, int len,
unsigned long seq)
{
}
static int nullmac_verify(void *handle, unsigned char *blk, int len,
unsigned long seq)
{
return 1;
}
const static struct ssh_mac ssh_mac_none = {
nullmac_make_context, nullmac_free_context, nullmac_key,
nullmac_generate, nullmac_verify, "none", 0
};
const static struct ssh_mac *macs[] = {
&ssh_sha1, &ssh_md5, &ssh_mac_none
};
const static struct ssh_mac *buggymacs[] = {
&ssh_sha1_buggy, &ssh_md5, &ssh_mac_none
};
static void *ssh_comp_none_init(void)
{
return NULL;
}
static void ssh_comp_none_cleanup(void *handle)
{
}
static int ssh_comp_none_block(void *handle, unsigned char *block, int len,
unsigned char **outblock, int *outlen)
{
return 0;
}
static int ssh_comp_none_disable(void *handle)
{
return 0;
}
const static struct ssh_compress ssh_comp_none = {
"none",
ssh_comp_none_init, ssh_comp_none_cleanup, ssh_comp_none_block,
ssh_comp_none_init, ssh_comp_none_cleanup, ssh_comp_none_block,
ssh_comp_none_disable, NULL
};
extern const struct ssh_compress ssh_zlib;
const static struct ssh_compress *compressions[] = {
&ssh_zlib, &ssh_comp_none
};
enum { /* channel types */
CHAN_MAINSESSION,
CHAN_X11,
CHAN_AGENT,
CHAN_SOCKDATA,
CHAN_SOCKDATA_DORMANT /* one the remote hasn't confirmed */
};
/*
* 2-3-4 tree storing channels.
*/
struct ssh_channel {
Ssh ssh; /* pointer back to main context */
unsigned remoteid, localid;
int type;
/*
* In SSH1, this value contains four bits:
*
* 1 We have sent SSH1_MSG_CHANNEL_CLOSE.
* 2 We have sent SSH1_MSG_CHANNEL_CLOSE_CONFIRMATION.
* 4 We have received SSH1_MSG_CHANNEL_CLOSE.
* 8 We have received SSH1_MSG_CHANNEL_CLOSE_CONFIRMATION.
*
* A channel is completely finished with when all four bits are set.
*/
int closes;
union {
struct ssh1_data_channel {
int throttling;
} v1;
struct ssh2_data_channel {
bufchain outbuffer;
unsigned remwindow, remmaxpkt;
unsigned locwindow;
} v2;
} v;
union {
struct ssh_agent_channel {
unsigned char *message;
unsigned char msglen[4];
int lensofar, totallen;
} a;
struct ssh_x11_channel {
Socket s;
} x11;
struct ssh_pfd_channel {
Socket s;
} pfd;
} u;
};
/*
* 2-3-4 tree storing remote->local port forwardings. SSH 1 and SSH
* 2 use this structure in different ways, reflecting SSH 2's
* altogether saner approach to port forwarding.
*
* In SSH 1, you arrange a remote forwarding by sending the server
* the remote port number, and the local destination host:port.
* When a connection comes in, the server sends you back that
* host:port pair, and you connect to it. This is a ready-made
* security hole if you're not on the ball: a malicious server
* could send you back _any_ host:port pair, so if you trustingly
* connect to the address it gives you then you've just opened the
* entire inside of your corporate network just by connecting
* through it to a dodgy SSH server. Hence, we must store a list of
* host:port pairs we _are_ trying to forward to, and reject a
* connection request from the server if it's not in the list.
*
* In SSH 2, each side of the connection minds its own business and
* doesn't send unnecessary information to the other. You arrange a
* remote forwarding by sending the server just the remote port
* number. When a connection comes in, the server tells you which
* of its ports was connected to; and _you_ have to remember what
* local host:port pair went with that port number.
*
* Hence: in SSH 1 this structure stores host:port pairs we intend
* to allow connections to, and is indexed by those host:port
* pairs. In SSH 2 it stores a mapping from source port to
* destination host:port pair, and is indexed by source port.
*/
struct ssh_rportfwd {
unsigned sport, dport;
char dhost[256];
};
struct Packet {
long length;
int type;
unsigned char *data;
unsigned char *body;
long savedpos;
long maxlen;
};
static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt);
static void ssh2_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt);
static void ssh_size(void *handle, int width, int height);
static void ssh_special(void *handle, Telnet_Special);
static int ssh2_try_send(struct ssh_channel *c);
static void ssh2_add_channel_data(struct ssh_channel *c, char *buf, int len);
static void ssh_throttle_all(Ssh ssh, int enable, int bufsize);
static void ssh2_set_window(struct ssh_channel *c, unsigned newwin);
static int ssh_sendbuffer(void *handle);
struct rdpkt1_state_tag {
long len, pad, biglen, to_read;
unsigned long realcrc, gotcrc;
unsigned char *p;
int i;
int chunk;
};
struct rdpkt2_state_tag {
long len, pad, payload, packetlen, maclen;
int i;
int cipherblk;
unsigned long incoming_sequence;
};
struct ssh_tag {
const struct plug_function_table *fn;
/* the above field _must_ be first in the structure */
SHA_State exhash, exhashbase;
Socket s;
void *ldisc;
void *logctx;
unsigned char session_key[32];
int v1_compressing;
int v1_remote_protoflags;
int v1_local_protoflags;
int agentfwd_enabled;
int X11_fwd_enabled;
int remote_bugs;
const struct ssh_cipher *cipher;
void *v1_cipher_ctx;
void *crcda_ctx;
const struct ssh2_cipher *cscipher, *sccipher;
void *cs_cipher_ctx, *sc_cipher_ctx;
const struct ssh_mac *csmac, *scmac;
void *cs_mac_ctx, *sc_mac_ctx;
const struct ssh_compress *cscomp, *sccomp;
void *cs_comp_ctx, *sc_comp_ctx;
const struct ssh_kex *kex;
const struct ssh_signkey *hostkey;
unsigned char v2_session_id[20];
void *kex_ctx;
char *savedhost;
int savedport;
int send_ok;
int echoing, editing;
void *frontend;
int term_width, term_height;
tree234 *channels; /* indexed by local id */
struct ssh_channel *mainchan; /* primary session channel */
int exitcode;
tree234 *rportfwds;
enum {
SSH_STATE_PREPACKET,
SSH_STATE_BEFORE_SIZE,
SSH_STATE_INTERMED,
SSH_STATE_SESSION,
SSH_STATE_CLOSED
} state;
int size_needed, eof_needed;
struct Packet pktin;
struct Packet pktout;
unsigned char *deferred_send_data;
int deferred_len, deferred_size;
/*
* Gross hack: pscp will try to start SFTP but fall back to
* scp1 if that fails. This variable is the means by which
* scp.c can reach into the SSH code and find out which one it
* got.
*/
int fallback_cmd;
/*
* Used for username and password input.
*/
char *userpass_input_buffer;
int userpass_input_buflen;
int userpass_input_bufpos;
int userpass_input_echo;
char *portfwd_strptr;
int pkt_ctx;
void *x11auth;
int version;
int v1_throttle_count;
int overall_bufsize;
int throttled_all;
int v1_stdout_throttling;
int v2_outgoing_sequence;
int ssh1_rdpkt_crstate;
int ssh2_rdpkt_crstate;
int do_ssh_init_crstate;
int ssh_gotdata_crstate;
int ssh1_protocol_crstate;
int do_ssh1_login_crstate;
int do_ssh2_transport_crstate;
int do_ssh2_authconn_crstate;
void *do_ssh_init_state;
void *do_ssh1_login_state;
void *do_ssh2_transport_state;
void *do_ssh2_authconn_state;
struct rdpkt1_state_tag rdpkt1_state;
struct rdpkt2_state_tag rdpkt2_state;
void (*protocol) (Ssh ssh, unsigned char *in, int inlen, int ispkt);
int (*s_rdpkt) (Ssh ssh, unsigned char **data, int *datalen);
};
#define logevent(s) logevent(ssh->frontend, s)
/* logevent, only printf-formatted. */
static void logeventf(Ssh ssh, char *fmt, ...)
{
va_list ap;
char *buf;
va_start(ap, fmt);
buf = dupvprintf(fmt, ap);
va_end(ap);
logevent(buf);
sfree(buf);
}
#define bombout(msg) ( ssh->state = SSH_STATE_CLOSED, \
(ssh->s ? sk_close(ssh->s), ssh->s = NULL : 0), \
logeventf msg, connection_fatal msg )
static int ssh_channelcmp(void *av, void *bv)
{
struct ssh_channel *a = (struct ssh_channel *) av;
struct ssh_channel *b = (struct ssh_channel *) bv;
if (a->localid < b->localid)
return -1;
if (a->localid > b->localid)
return +1;
return 0;
}
static int ssh_channelfind(void *av, void *bv)
{
unsigned *a = (unsigned *) av;
struct ssh_channel *b = (struct ssh_channel *) bv;
if (*a < b->localid)
return -1;
if (*a > b->localid)
return +1;
return 0;
}
static int ssh_rportcmp_ssh1(void *av, void *bv)
{
struct ssh_rportfwd *a = (struct ssh_rportfwd *) av;
struct ssh_rportfwd *b = (struct ssh_rportfwd *) bv;
int i;
if ( (i = strcmp(a->dhost, b->dhost)) != 0)
return i < 0 ? -1 : +1;
if (a->dport > b->dport)
return +1;
if (a->dport < b->dport)
return -1;
return 0;
}
static int ssh_rportcmp_ssh2(void *av, void *bv)
{
struct ssh_rportfwd *a = (struct ssh_rportfwd *) av;
struct ssh_rportfwd *b = (struct ssh_rportfwd *) bv;
if (a->sport > b->sport)
return +1;
if (a->sport < b->sport)
return -1;
return 0;
}
static int alloc_channel_id(Ssh ssh)
{
const unsigned CHANNEL_NUMBER_OFFSET = 256;
unsigned low, high, mid;
int tsize;
struct ssh_channel *c;
/*
* First-fit allocation of channel numbers: always pick the
* lowest unused one. To do this, binary-search using the
* counted B-tree to find the largest channel ID which is in a
* contiguous sequence from the beginning. (Precisely
* everything in that sequence must have ID equal to its tree
* index plus CHANNEL_NUMBER_OFFSET.)
*/
tsize = count234(ssh->channels);
low = -1;
high = tsize;
while (high - low > 1) {
mid = (high + low) / 2;
c = index234(ssh->channels, mid);
if (c->localid == mid + CHANNEL_NUMBER_OFFSET)
low = mid; /* this one is fine */
else
high = mid; /* this one is past it */
}
/*
* Now low points to either -1, or the tree index of the
* largest ID in the initial sequence.
*/
{
unsigned i = low + 1 + CHANNEL_NUMBER_OFFSET;
assert(NULL == find234(ssh->channels, &i, ssh_channelfind));
}
return low + 1 + CHANNEL_NUMBER_OFFSET;
}
static void c_write(Ssh ssh, char *buf, int len)
{
if ((flags & FLAG_STDERR)) {
int i;
for (i = 0; i < len; i++)
if (buf[i] != '\r')
fputc(buf[i], stderr);
return;
}
from_backend(ssh->frontend, 1, buf, len);
}
static void c_write_untrusted(Ssh ssh, char *buf, int len)
{
int i;
for (i = 0; i < len; i++) {
if (buf[i] == '\n')
c_write(ssh, "\r\n", 2);
else if ((buf[i] & 0x60) || (buf[i] == '\r'))
c_write(ssh, buf + i, 1);
}
}
static void c_write_str(Ssh ssh, char *buf)
{
c_write(ssh, buf, strlen(buf));
}
/*
* Collect incoming data in the incoming packet buffer.
* Decipher and verify the packet when it is completely read.
* Drop SSH1_MSG_DEBUG and SSH1_MSG_IGNORE packets.
* Update the *data and *datalen variables.
* Return the additional nr of bytes needed, or 0 when
* a complete packet is available.
*/
static int ssh1_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
{
struct rdpkt1_state_tag *st = &ssh->rdpkt1_state;
crBegin(ssh->ssh1_rdpkt_crstate);
next_packet:
ssh->pktin.type = 0;
ssh->pktin.length = 0;
for (st->i = st->len = 0; st->i < 4; st->i++) {
while ((*datalen) == 0)
crReturn(4 - st->i);
st->len = (st->len << 8) + **data;
(*data)++, (*datalen)--;
}
st->pad = 8 - (st->len % 8);
st->biglen = st->len + st->pad;
ssh->pktin.length = st->len - 5;
if (ssh->pktin.maxlen < st->biglen) {
ssh->pktin.maxlen = st->biglen;
ssh->pktin.data = srealloc(ssh->pktin.data, st->biglen + APIEXTRA);
}
st->to_read = st->biglen;
st->p = ssh->pktin.data;
while (st->to_read > 0) {
st->chunk = st->to_read;
while ((*datalen) == 0)
crReturn(st->to_read);
if (st->chunk > (*datalen))
st->chunk = (*datalen);
memcpy(st->p, *data, st->chunk);
*data += st->chunk;
*datalen -= st->chunk;
st->p += st->chunk;
st->to_read -= st->chunk;
}
if (ssh->cipher && detect_attack(ssh->crcda_ctx, ssh->pktin.data,
st->biglen, NULL)) {
bombout((ssh,"Network attack (CRC compensation) detected!"));
crReturn(0);
}
if (ssh->cipher)
ssh->cipher->decrypt(ssh->v1_cipher_ctx, ssh->pktin.data, st->biglen);
st->realcrc = crc32(ssh->pktin.data, st->biglen - 4);
st->gotcrc = GET_32BIT(ssh->pktin.data + st->biglen - 4);
if (st->gotcrc != st->realcrc) {
bombout((ssh,"Incorrect CRC received on packet"));
crReturn(0);
}
ssh->pktin.body = ssh->pktin.data + st->pad + 1;
if (ssh->v1_compressing) {
unsigned char *decompblk;
int decomplen;
zlib_decompress_block(ssh->sc_comp_ctx,
ssh->pktin.body - 1, ssh->pktin.length + 1,
&decompblk, &decomplen);
if (ssh->pktin.maxlen < st->pad + decomplen) {
ssh->pktin.maxlen = st->pad + decomplen;
ssh->pktin.data = srealloc(ssh->pktin.data,
ssh->pktin.maxlen + APIEXTRA);
ssh->pktin.body = ssh->pktin.data + st->pad + 1;
}
memcpy(ssh->pktin.body - 1, decompblk, decomplen);
sfree(decompblk);
ssh->pktin.length = decomplen - 1;
}
ssh->pktin.type = ssh->pktin.body[-1];
if (ssh->logctx)
log_packet(ssh->logctx,
PKT_INCOMING, ssh->pktin.type,
ssh1_pkt_type(ssh->pktin.type),
ssh->pktin.body, ssh->pktin.length);
if (ssh->pktin.type == SSH1_SMSG_STDOUT_DATA ||
ssh->pktin.type == SSH1_SMSG_STDERR_DATA ||
ssh->pktin.type == SSH1_MSG_DEBUG ||
ssh->pktin.type == SSH1_SMSG_AUTH_TIS_CHALLENGE ||
ssh->pktin.type == SSH1_SMSG_AUTH_CCARD_CHALLENGE) {
long stringlen = GET_32BIT(ssh->pktin.body);
if (stringlen + 4 != ssh->pktin.length) {
bombout((ssh,"Received data packet with bogus string length"));
crReturn(0);
}
}
if (ssh->pktin.type == SSH1_MSG_DEBUG) {
/* log debug message */
char buf[512];
int stringlen = GET_32BIT(ssh->pktin.body);
strcpy(buf, "Remote debug message: ");
if (stringlen > 480)
stringlen = 480;
memcpy(buf + 8, ssh->pktin.body + 4, stringlen);
buf[8 + stringlen] = '\0';
logevent(buf);
goto next_packet;
} else if (ssh->pktin.type == SSH1_MSG_IGNORE) {
/* do nothing */
goto next_packet;
}
if (ssh->pktin.type == SSH1_MSG_DISCONNECT) {
/* log reason code in disconnect message */
char buf[256];
unsigned msglen = GET_32BIT(ssh->pktin.body);
unsigned nowlen;
strcpy(buf, "Remote sent disconnect: ");
nowlen = strlen(buf);
if (msglen > sizeof(buf) - nowlen - 1)
msglen = sizeof(buf) - nowlen - 1;
memcpy(buf + nowlen, ssh->pktin.body + 4, msglen);
buf[nowlen + msglen] = '\0';
/* logevent(buf); (this is now done within the bombout macro) */
bombout((ssh,"Server sent disconnect message:\n\"%s\"", buf+nowlen));
crReturn(0);
}
crFinish(0);
}
static int ssh2_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
{
struct rdpkt2_state_tag *st = &ssh->rdpkt2_state;
crBegin(ssh->ssh2_rdpkt_crstate);
next_packet:
ssh->pktin.type = 0;
ssh->pktin.length = 0;
if (ssh->sccipher)
st->cipherblk = ssh->sccipher->blksize;
else
st->cipherblk = 8;
if (st->cipherblk < 8)
st->cipherblk = 8;
if (ssh->pktin.maxlen < st->cipherblk) {
ssh->pktin.maxlen = st->cipherblk;
ssh->pktin.data = srealloc(ssh->pktin.data, st->cipherblk + APIEXTRA);
}
/*
* Acquire and decrypt the first block of the packet. This will
* contain the length and padding details.
*/
for (st->i = st->len = 0; st->i < st->cipherblk; st->i++) {
while ((*datalen) == 0)
crReturn(st->cipherblk - st->i);
ssh->pktin.data[st->i] = *(*data)++;
(*datalen)--;
}
if (ssh->sccipher)
ssh->sccipher->decrypt(ssh->sc_cipher_ctx,
ssh->pktin.data, st->cipherblk);
/*
* Now get the length and padding figures.
*/
st->len = GET_32BIT(ssh->pktin.data);
st->pad = ssh->pktin.data[4];
/*
* _Completely_ silly lengths should be stomped on before they
* do us any more damage.
*/
if (st->len < 0 || st->pad < 0 || st->len + st->pad < 0) {
bombout((ssh,"Incoming packet was garbled on decryption"));
crReturn(0);
}
/*
* This enables us to deduce the payload length.
*/
st->payload = st->len - st->pad - 1;
ssh->pktin.length = st->payload + 5;
/*
* So now we can work out the total packet length.
*/
st->packetlen = st->len + 4;
st->maclen = ssh->scmac ? ssh->scmac->len : 0;
/*
* Adjust memory allocation if packet is too big.
*/
if (ssh->pktin.maxlen < st->packetlen + st->maclen) {
ssh->pktin.maxlen = st->packetlen + st->maclen;
ssh->pktin.data = srealloc(ssh->pktin.data,
ssh->pktin.maxlen + APIEXTRA);
}
/*
* Read and decrypt the remainder of the packet.
*/
for (st->i = st->cipherblk; st->i < st->packetlen + st->maclen;
st->i++) {
while ((*datalen) == 0)
crReturn(st->packetlen + st->maclen - st->i);
ssh->pktin.data[st->i] = *(*data)++;
(*datalen)--;
}
/* Decrypt everything _except_ the MAC. */
if (ssh->sccipher)
ssh->sccipher->decrypt(ssh->sc_cipher_ctx,
ssh->pktin.data + st->cipherblk,
st->packetlen - st->cipherblk);
/*
* Check the MAC.
*/
if (ssh->scmac
&& !ssh->scmac->verify(ssh->sc_mac_ctx, ssh->pktin.data, st->len + 4,
st->incoming_sequence)) {
bombout((ssh,"Incorrect MAC received on packet"));
crReturn(0);
}
st->incoming_sequence++; /* whether or not we MACed */
/*
* Decompress packet payload.
*/
{
unsigned char *newpayload;
int newlen;
if (ssh->sccomp &&
ssh->sccomp->decompress(ssh->sc_comp_ctx,
ssh->pktin.data + 5, ssh->pktin.length - 5,
&newpayload, &newlen)) {
if (ssh->pktin.maxlen < newlen + 5) {
ssh->pktin.maxlen = newlen + 5;
ssh->pktin.data = srealloc(ssh->pktin.data,
ssh->pktin.maxlen + APIEXTRA);
}
ssh->pktin.length = 5 + newlen;
memcpy(ssh->pktin.data + 5, newpayload, newlen);
sfree(newpayload);
}
}
ssh->pktin.savedpos = 6;
ssh->pktin.type = ssh->pktin.data[5];
if (ssh->logctx)
log_packet(ssh->logctx, PKT_INCOMING, ssh->pktin.type,
ssh2_pkt_type(ssh->pkt_ctx, ssh->pktin.type),
ssh->pktin.data+6, ssh->pktin.length-6);
switch (ssh->pktin.type) {
/*
* These packets we must handle instantly.
*/
case SSH2_MSG_DISCONNECT:
{
/* log reason code in disconnect message */
char *buf;
int nowlen;
int reason = GET_32BIT(ssh->pktin.data + 6);
unsigned msglen = GET_32BIT(ssh->pktin.data + 10);
if (reason > 0 && reason < lenof(ssh2_disconnect_reasons)) {
buf = dupprintf("Received disconnect message (%s)",
ssh2_disconnect_reasons[reason]);
} else {
buf = dupprintf("Received disconnect message (unknown"
" type %d)", reason);
}
logevent(buf);
sfree(buf);
buf = dupprintf("Disconnection message text: %n%.*s",
&nowlen, msglen, ssh->pktin.data + 14);
logevent(buf);
bombout((ssh,"Server sent disconnect message\ntype %d (%s):\n\"%s\"",
reason,
(reason > 0 && reason < lenof(ssh2_disconnect_reasons)) ?
ssh2_disconnect_reasons[reason] : "unknown",
buf+nowlen));
sfree(buf);
crReturn(0);
}
break;
case SSH2_MSG_IGNORE:
goto next_packet;
case SSH2_MSG_DEBUG:
{
/* log the debug message */
char buf[512];
/* int display = ssh->pktin.body[6]; */
int stringlen = GET_32BIT(ssh->pktin.data+7);
int prefix;
strcpy(buf, "Remote debug message: ");
prefix = strlen(buf);
if (stringlen > (int)(sizeof(buf)-prefix-1))
stringlen = sizeof(buf)-prefix-1;
memcpy(buf + prefix, ssh->pktin.data + 11, stringlen);
buf[prefix + stringlen] = '\0';
logevent(buf);
}
goto next_packet; /* FIXME: print the debug message */
/*
* These packets we need do nothing about here.
*/
case SSH2_MSG_UNIMPLEMENTED:
case SSH2_MSG_SERVICE_REQUEST:
case SSH2_MSG_SERVICE_ACCEPT:
case SSH2_MSG_KEXINIT:
case SSH2_MSG_NEWKEYS:
case SSH2_MSG_KEXDH_INIT:
case SSH2_MSG_KEXDH_REPLY:
/* case SSH2_MSG_KEX_DH_GEX_REQUEST: duplicate case value */
/* case SSH2_MSG_KEX_DH_GEX_GROUP: duplicate case value */
case SSH2_MSG_KEX_DH_GEX_INIT:
case SSH2_MSG_KEX_DH_GEX_REPLY:
case SSH2_MSG_USERAUTH_REQUEST:
case SSH2_MSG_USERAUTH_FAILURE:
case SSH2_MSG_USERAUTH_SUCCESS:
case SSH2_MSG_USERAUTH_BANNER:
case SSH2_MSG_USERAUTH_PK_OK:
/* case SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ: duplicate case value */
/* case SSH2_MSG_USERAUTH_INFO_REQUEST: duplicate case value */
case SSH2_MSG_USERAUTH_INFO_RESPONSE:
case SSH2_MSG_GLOBAL_REQUEST:
case SSH2_MSG_REQUEST_SUCCESS:
case SSH2_MSG_REQUEST_FAILURE:
case SSH2_MSG_CHANNEL_OPEN:
case SSH2_MSG_CHANNEL_OPEN_CONFIRMATION:
case SSH2_MSG_CHANNEL_OPEN_FAILURE:
case SSH2_MSG_CHANNEL_WINDOW_ADJUST:
case SSH2_MSG_CHANNEL_DATA:
case SSH2_MSG_CHANNEL_EXTENDED_DATA:
case SSH2_MSG_CHANNEL_EOF:
case SSH2_MSG_CHANNEL_CLOSE:
case SSH2_MSG_CHANNEL_REQUEST:
case SSH2_MSG_CHANNEL_SUCCESS:
case SSH2_MSG_CHANNEL_FAILURE:
break;
/*
* For anything else we send SSH2_MSG_UNIMPLEMENTED.
*/
default:
ssh2_pkt_init(ssh, SSH2_MSG_UNIMPLEMENTED);
ssh2_pkt_adduint32(ssh, st->incoming_sequence - 1);
ssh2_pkt_send(ssh);
break;
}
crFinish(0);
}
static void ssh1_pktout_size(Ssh ssh, int len)
{
int pad, biglen;
len += 5; /* type and CRC */
pad = 8 - (len % 8);
biglen = len + pad;
ssh->pktout.length = len - 5;
if (ssh->pktout.maxlen < biglen) {
ssh->pktout.maxlen = biglen;
#ifdef MSCRYPTOAPI
/* Allocate enough buffer space for extra block
* for MS CryptEncrypt() */
ssh->pktout.data = srealloc(ssh->pktout.data, biglen + 12);
#else
ssh->pktout.data = srealloc(ssh->pktout.data, biglen + 4);
#endif
}
ssh->pktout.body = ssh->pktout.data + 4 + pad + 1;
}
static void s_wrpkt_start(Ssh ssh, int type, int len)
{
ssh1_pktout_size(ssh, len);
ssh->pktout.type = type;
}
static int s_wrpkt_prepare(Ssh ssh)
{
int pad, len, biglen, i;
unsigned long crc;
ssh->pktout.body[-1] = ssh->pktout.type;
if (ssh->logctx)
log_packet(ssh->logctx, PKT_OUTGOING, ssh->pktout.type,
ssh1_pkt_type(ssh->pktout.type),
ssh->pktout.body, ssh->pktout.length);
if (ssh->v1_compressing) {
unsigned char *compblk;
int complen;
zlib_compress_block(ssh->cs_comp_ctx,
ssh->pktout.body - 1, ssh->pktout.length + 1,
&compblk, &complen);
ssh1_pktout_size(ssh, complen - 1);
memcpy(ssh->pktout.body - 1, compblk, complen);
sfree(compblk);
}
len = ssh->pktout.length + 5; /* type and CRC */
pad = 8 - (len % 8);
biglen = len + pad;
for (i = 0; i < pad; i++)
ssh->pktout.data[i + 4] = random_byte();
crc = crc32(ssh->pktout.data + 4, biglen - 4);
PUT_32BIT(ssh->pktout.data + biglen, crc);
PUT_32BIT(ssh->pktout.data, len);
if (ssh->cipher)
ssh->cipher->encrypt(ssh->v1_cipher_ctx, ssh->pktout.data + 4, biglen);
return biglen + 4;
}
static void s_wrpkt(Ssh ssh)
{
int len, backlog;
len = s_wrpkt_prepare(ssh);
backlog = sk_write(ssh->s, (char *)ssh->pktout.data, len);
if (backlog > SSH_MAX_BACKLOG)
ssh_throttle_all(ssh, 1, backlog);
}
static void s_wrpkt_defer(Ssh ssh)
{
int len;
len = s_wrpkt_prepare(ssh);
if (ssh->deferred_len + len > ssh->deferred_size) {
ssh->deferred_size = ssh->deferred_len + len + 128;
ssh->deferred_send_data = srealloc(ssh->deferred_send_data,
ssh->deferred_size);
}
memcpy(ssh->deferred_send_data + ssh->deferred_len, ssh->pktout.data, len);
ssh->deferred_len += len;
}
/*
* Construct a packet with the specified contents.
*/
static void construct_packet(Ssh ssh, int pkttype, va_list ap1, va_list ap2)
{
unsigned char *p, *argp, argchar;
unsigned long argint;
int pktlen, argtype, arglen;
Bignum bn;
pktlen = 0;
while ((argtype = va_arg(ap1, int)) != PKT_END) {
switch (argtype) {
case PKT_INT:
(void) va_arg(ap1, int);
pktlen += 4;
break;
case PKT_CHAR:
(void) va_arg(ap1, int);
pktlen++;
break;
case PKT_DATA:
(void) va_arg(ap1, unsigned char *);
arglen = va_arg(ap1, int);
pktlen += arglen;
break;
case PKT_STR:
argp = va_arg(ap1, unsigned char *);
arglen = strlen((char *)argp);
pktlen += 4 + arglen;
break;
case PKT_BIGNUM:
bn = va_arg(ap1, Bignum);
pktlen += ssh1_bignum_length(bn);
break;
default:
assert(0);
}
}
s_wrpkt_start(ssh, pkttype, pktlen);
p = ssh->pktout.body;
while ((argtype = va_arg(ap2, int)) != PKT_END) {
switch (argtype) {
case PKT_INT:
argint = va_arg(ap2, int);
PUT_32BIT(p, argint);
p += 4;
break;
case PKT_CHAR:
argchar = (unsigned char) va_arg(ap2, int);
*p = argchar;
p++;
break;
case PKT_DATA:
argp = va_arg(ap2, unsigned char *);
arglen = va_arg(ap2, int);
memcpy(p, argp, arglen);
p += arglen;
break;
case PKT_STR:
argp = va_arg(ap2, unsigned char *);
arglen = strlen((char *)argp);
PUT_32BIT(p, arglen);
memcpy(p + 4, argp, arglen);
p += 4 + arglen;
break;
case PKT_BIGNUM:
bn = va_arg(ap2, Bignum);
p += ssh1_write_bignum(p, bn);
break;
}
}
}
static void send_packet(Ssh ssh, int pkttype, ...)
{
va_list ap1, ap2;
va_start(ap1, pkttype);
va_start(ap2, pkttype);
construct_packet(ssh, pkttype, ap1, ap2);
s_wrpkt(ssh);
}
static void defer_packet(Ssh ssh, int pkttype, ...)
{
va_list ap1, ap2;
va_start(ap1, pkttype);
va_start(ap2, pkttype);
construct_packet(ssh, pkttype, ap1, ap2);
s_wrpkt_defer(ssh);
}
static int ssh_versioncmp(char *a, char *b)
{
char *ae, *be;
unsigned long av, bv;
av = strtoul(a, &ae, 10);
bv = strtoul(b, &be, 10);
if (av != bv)
return (av < bv ? -1 : +1);
if (*ae == '.')
ae++;
if (*be == '.')
be++;
av = strtoul(ae, &ae, 10);
bv = strtoul(be, &be, 10);
if (av != bv)
return (av < bv ? -1 : +1);
return 0;
}
/*
* Utility routines for putting an SSH-protocol `string' and
* `uint32' into a SHA state.
*/
#include <stdio.h>
static void sha_string(SHA_State * s, void *str, int len)
{
unsigned char lenblk[4];
PUT_32BIT(lenblk, len);
SHA_Bytes(s, lenblk, 4);
SHA_Bytes(s, str, len);
}
static void sha_uint32(SHA_State * s, unsigned i)
{
unsigned char intblk[4];
PUT_32BIT(intblk, i);
SHA_Bytes(s, intblk, 4);
}
/*
* SSH2 packet construction functions.
*/
static void ssh2_pkt_ensure(Ssh ssh, int length)
{
if (ssh->pktout.maxlen < length) {
ssh->pktout.maxlen = length + 256;
ssh->pktout.data = srealloc(ssh->pktout.data,
ssh->pktout.maxlen + APIEXTRA);
if (!ssh->pktout.data)
fatalbox("Out of memory");
}
}
static void ssh2_pkt_adddata(Ssh ssh, void *data, int len)
{
ssh->pktout.length += len;
ssh2_pkt_ensure(ssh, ssh->pktout.length);
memcpy(ssh->pktout.data + ssh->pktout.length - len, data, len);
}
static void ssh2_pkt_addbyte(Ssh ssh, unsigned char byte)
{
ssh2_pkt_adddata(ssh, &byte, 1);
}
static void ssh2_pkt_init(Ssh ssh, int pkt_type)
{
ssh->pktout.length = 5;
ssh2_pkt_addbyte(ssh, (unsigned char) pkt_type);
}
static void ssh2_pkt_addbool(Ssh ssh, unsigned char value)
{
ssh2_pkt_adddata(ssh, &value, 1);
}
static void ssh2_pkt_adduint32(Ssh ssh, unsigned long value)
{
unsigned char x[4];
PUT_32BIT(x, value);
ssh2_pkt_adddata(ssh, x, 4);
}
static void ssh2_pkt_addstring_start(Ssh ssh)
{
ssh2_pkt_adduint32(ssh, 0);
ssh->pktout.savedpos = ssh->pktout.length;
}
static void ssh2_pkt_addstring_str(Ssh ssh, char *data)
{
ssh2_pkt_adddata(ssh, data, strlen(data));
PUT_32BIT(ssh->pktout.data + ssh->pktout.savedpos - 4,
ssh->pktout.length - ssh->pktout.savedpos);
}
static void ssh2_pkt_addstring_data(Ssh ssh, char *data, int len)
{
ssh2_pkt_adddata(ssh, data, len);
PUT_32BIT(ssh->pktout.data + ssh->pktout.savedpos - 4,
ssh->pktout.length - ssh->pktout.savedpos);
}
static void ssh2_pkt_addstring(Ssh ssh, char *data)
{
ssh2_pkt_addstring_start(ssh);
ssh2_pkt_addstring_str(ssh, data);
}
static unsigned char *ssh2_mpint_fmt(Bignum b, int *len)
{
unsigned char *p;
int i, n = (bignum_bitcount(b) + 7) / 8;
p = smalloc(n + 1);
if (!p)
fatalbox("out of memory");
p[0] = 0;
for (i = 1; i <= n; i++)
p[i] = bignum_byte(b, n - i);
i = 0;
while (i <= n && p[i] == 0 && (p[i + 1] & 0x80) == 0)
i++;
memmove(p, p + i, n + 1 - i);
*len = n + 1 - i;
return p;
}
static void ssh2_pkt_addmp(Ssh ssh, Bignum b)
{
unsigned char *p;
int len;
p = ssh2_mpint_fmt(b, &len);
ssh2_pkt_addstring_start(ssh);
ssh2_pkt_addstring_data(ssh, (char *)p, len);
sfree(p);
}
/*
* Construct an SSH2 final-form packet: compress it, encrypt it,
* put the MAC on it. Final packet, ready to be sent, is stored in
* ssh->pktout.data. Total length is returned.
*/
static int ssh2_pkt_construct(Ssh ssh)
{
int cipherblk, maclen, padding, i;
if (ssh->logctx)
log_packet(ssh->logctx, PKT_OUTGOING, ssh->pktout.data[5],
ssh2_pkt_type(ssh->pkt_ctx, ssh->pktout.data[5]),
ssh->pktout.data + 6, ssh->pktout.length - 6);
/*
* Compress packet payload.
*/
{
unsigned char *newpayload;
int newlen;
if (ssh->cscomp &&
ssh->cscomp->compress(ssh->cs_comp_ctx, ssh->pktout.data + 5,
ssh->pktout.length - 5,
&newpayload, &newlen)) {
ssh->pktout.length = 5;
ssh2_pkt_adddata(ssh, newpayload, newlen);
sfree(newpayload);
}
}
/*
* Add padding. At least four bytes, and must also bring total
* length (minus MAC) up to a multiple of the block size.
*/
cipherblk = ssh->cscipher ? ssh->cscipher->blksize : 8; /* block size */
cipherblk = cipherblk < 8 ? 8 : cipherblk; /* or 8 if blksize < 8 */
padding = 4;
padding +=
(cipherblk - (ssh->pktout.length + padding) % cipherblk) % cipherblk;
maclen = ssh->csmac ? ssh->csmac->len : 0;
ssh2_pkt_ensure(ssh, ssh->pktout.length + padding + maclen);
ssh->pktout.data[4] = padding;
for (i = 0; i < padding; i++)
ssh->pktout.data[ssh->pktout.length + i] = random_byte();
PUT_32BIT(ssh->pktout.data, ssh->pktout.length + padding - 4);
if (ssh->csmac)
ssh->csmac->generate(ssh->cs_mac_ctx, ssh->pktout.data,
ssh->pktout.length + padding,
ssh->v2_outgoing_sequence);
ssh->v2_outgoing_sequence++; /* whether or not we MACed */
if (ssh->cscipher)
ssh->cscipher->encrypt(ssh->cs_cipher_ctx,
ssh->pktout.data, ssh->pktout.length + padding);
/* Ready-to-send packet starts at ssh->pktout.data. We return length. */
return ssh->pktout.length + padding + maclen;
}
/*
* Construct and send an SSH2 packet immediately.
*/
static void ssh2_pkt_send(Ssh ssh)
{
int len;
int backlog;
len = ssh2_pkt_construct(ssh);
backlog = sk_write(ssh->s, (char *)ssh->pktout.data, len);
if (backlog > SSH_MAX_BACKLOG)
ssh_throttle_all(ssh, 1, backlog);
}
/*
* Construct an SSH2 packet and add it to a deferred data block.
* Useful for sending multiple packets in a single sk_write() call,
* to prevent a traffic-analysing listener from being able to work
* out the length of any particular packet (such as the password
* packet).
*
* Note that because SSH2 sequence-numbers its packets, this can
* NOT be used as an m4-style `defer' allowing packets to be
* constructed in one order and sent in another.
*/
static void ssh2_pkt_defer(Ssh ssh)
{
int len = ssh2_pkt_construct(ssh);
if (ssh->deferred_len + len > ssh->deferred_size) {
ssh->deferred_size = ssh->deferred_len + len + 128;
ssh->deferred_send_data = srealloc(ssh->deferred_send_data,
ssh->deferred_size);
}
memcpy(ssh->deferred_send_data + ssh->deferred_len, ssh->pktout.data, len);
ssh->deferred_len += len;
}
/*
* Send the whole deferred data block constructed by
* ssh2_pkt_defer() or SSH1's defer_packet().
*/
static void ssh_pkt_defersend(Ssh ssh)
{
int backlog;
backlog = sk_write(ssh->s, (char *)ssh->deferred_send_data,
ssh->deferred_len);
ssh->deferred_len = ssh->deferred_size = 0;
sfree(ssh->deferred_send_data);
ssh->deferred_send_data = NULL;
if (backlog > SSH_MAX_BACKLOG)
ssh_throttle_all(ssh, 1, backlog);
}
#if 0
void bndebug(char *string, Bignum b)
{
unsigned char *p;
int i, len;
p = ssh2_mpint_fmt(b, &len);
debug(("%s", string));
for (i = 0; i < len; i++)
debug((" %02x", p[i]));
debug(("\n"));
sfree(p);
}
#endif
static void sha_mpint(SHA_State * s, Bignum b)
{
unsigned char *p;
int len;
p = ssh2_mpint_fmt(b, &len);
sha_string(s, p, len);
sfree(p);
}
/*
* SSH2 packet decode functions.
*/
static unsigned long ssh2_pkt_getuint32(Ssh ssh)
{
unsigned long value;
if (ssh->pktin.length - ssh->pktin.savedpos < 4)
return 0; /* arrgh, no way to decline (FIXME?) */
value = GET_32BIT(ssh->pktin.data + ssh->pktin.savedpos);
ssh->pktin.savedpos += 4;
return value;
}
static int ssh2_pkt_getbool(Ssh ssh)
{
unsigned long value;
if (ssh->pktin.length - ssh->pktin.savedpos < 1)
return 0; /* arrgh, no way to decline (FIXME?) */
value = ssh->pktin.data[ssh->pktin.savedpos] != 0;
ssh->pktin.savedpos++;
return value;
}
static void ssh2_pkt_getstring(Ssh ssh, char **p, int *length)
{
int len;
*p = NULL;
*length = 0;
if (ssh->pktin.length - ssh->pktin.savedpos < 4)
return;
len = GET_32BIT(ssh->pktin.data + ssh->pktin.savedpos);
if (len < 0)
return;
*length = len;
ssh->pktin.savedpos += 4;
if (ssh->pktin.length - ssh->pktin.savedpos < *length)
return;
*p = (char *)(ssh->pktin.data + ssh->pktin.savedpos);
ssh->pktin.savedpos += *length;
}
static Bignum ssh2_pkt_getmp(Ssh ssh)
{
char *p;
int length;
Bignum b;
ssh2_pkt_getstring(ssh, &p, &length);
if (!p)
return NULL;
if (p[0] & 0x80) {
bombout((ssh,"internal error: Can't handle negative mpints"));
return NULL;
}
b = bignum_from_bytes((unsigned char *)p, length);
return b;
}
/*
* Helper function to add an SSH2 signature blob to a packet.
* Expects to be shown the public key blob as well as the signature
* blob. Normally works just like ssh2_pkt_addstring, but will
* fiddle with the signature packet if necessary for
* BUG_SSH2_RSA_PADDING.
*/
static void ssh2_add_sigblob(Ssh ssh, void *pkblob_v, int pkblob_len,
void *sigblob_v, int sigblob_len)
{
unsigned char *pkblob = (unsigned char *)pkblob_v;
unsigned char *sigblob = (unsigned char *)sigblob_v;
/* dmemdump(pkblob, pkblob_len); */
/* dmemdump(sigblob, sigblob_len); */
/*
* See if this is in fact an ssh-rsa signature and a buggy
* server; otherwise we can just do this the easy way.
*/
if ((ssh->remote_bugs & BUG_SSH2_RSA_PADDING) &&
(GET_32BIT(pkblob) == 7 && !memcmp(pkblob+4, "ssh-rsa", 7))) {
int pos, len, siglen;
/*
* Find the byte length of the modulus.
*/
pos = 4+7; /* skip over "ssh-rsa" */
pos += 4 + GET_32BIT(pkblob+pos); /* skip over exponent */
len = GET_32BIT(pkblob+pos); /* find length of modulus */
pos += 4; /* find modulus itself */
while (len > 0 && pkblob[pos] == 0)
len--, pos++;
/* debug(("modulus length is %d\n", len)); */
/*
* Now find the signature integer.
*/
pos = 4+7; /* skip over "ssh-rsa" */
siglen = GET_32BIT(sigblob+pos);
/* debug(("signature length is %d\n", siglen)); */
if (len != siglen) {
unsigned char newlen[4];
ssh2_pkt_addstring_start(ssh);
ssh2_pkt_addstring_data(ssh, (char *)sigblob, pos);
/* dmemdump(sigblob, pos); */
pos += 4; /* point to start of actual sig */
PUT_32BIT(newlen, len);
ssh2_pkt_addstring_data(ssh, (char *)newlen, 4);
/* dmemdump(newlen, 4); */
newlen[0] = 0;
while (len-- > siglen) {
ssh2_pkt_addstring_data(ssh, (char *)newlen, 1);
/* dmemdump(newlen, 1); */
}
ssh2_pkt_addstring_data(ssh, (char *)(sigblob+pos), siglen);
/* dmemdump(sigblob+pos, siglen); */
return;
}
/* Otherwise fall through and do it the easy way. */
}
ssh2_pkt_addstring_start(ssh);
ssh2_pkt_addstring_data(ssh, (char *)sigblob, sigblob_len);
}
/*
* Examine the remote side's version string and compare it against
* a list of known buggy implementations.
*/
static void ssh_detect_bugs(Ssh ssh, char *vstring)
{
char *imp; /* pointer to implementation part */
imp = vstring;
imp += strcspn(imp, "-");
if (*imp) imp++;
imp += strcspn(imp, "-");
if (*imp) imp++;
ssh->remote_bugs = 0;
if (cfg.sshbug_ignore1 == BUG_ON ||
(cfg.sshbug_ignore1 == BUG_AUTO &&
(!strcmp(imp, "1.2.18") || !strcmp(imp, "1.2.19") ||
!strcmp(imp, "1.2.20") || !strcmp(imp, "1.2.21") ||
!strcmp(imp, "1.2.22") || !strcmp(imp, "Cisco-1.25")))) {
/*
* These versions don't support SSH1_MSG_IGNORE, so we have
* to use a different defence against password length
* sniffing.
*/
ssh->remote_bugs |= BUG_CHOKES_ON_SSH1_IGNORE;
logevent("We believe remote version has SSH1 ignore bug");
}
if (cfg.sshbug_plainpw1 == BUG_ON ||
(cfg.sshbug_plainpw1 == BUG_AUTO &&
(!strcmp(imp, "Cisco-1.25")))) {
/*
* These versions need a plain password sent; they can't
* handle having a null and a random length of data after
* the password.
*/
ssh->remote_bugs |= BUG_NEEDS_SSH1_PLAIN_PASSWORD;
logevent("We believe remote version needs a plain SSH1 password");
}
if (cfg.sshbug_rsa1 == BUG_ON ||
(cfg.sshbug_rsa1 == BUG_AUTO &&
(!strcmp(imp, "Cisco-1.25")))) {
/*
* These versions apparently have no clue whatever about
* RSA authentication and will panic and die if they see
* an AUTH_RSA message.
*/
ssh->remote_bugs |= BUG_CHOKES_ON_RSA;
logevent("We believe remote version can't handle RSA authentication");
}
if (cfg.sshbug_hmac2 == BUG_ON ||
(cfg.sshbug_hmac2 == BUG_AUTO &&
(wc_match("2.1.0*", imp) || wc_match("2.0.*", imp) ||
wc_match("2.2.0*", imp) || wc_match("2.3.0*", imp) ||
wc_match("2.1 *", imp)))) {
/*
* These versions have the HMAC bug.
*/
ssh->remote_bugs |= BUG_SSH2_HMAC;
logevent("We believe remote version has SSH2 HMAC bug");
}
if (cfg.sshbug_derivekey2 == BUG_ON ||
(cfg.sshbug_derivekey2 == BUG_AUTO &&
(wc_match("2.0.0*", imp) || wc_match("2.0.1[01]*", imp) ))) {
/*
* These versions have the key-derivation bug (failing to
* include the literal shared secret in the hashes that
* generate the keys).
*/
ssh->remote_bugs |= BUG_SSH2_DERIVEKEY;
logevent("We believe remote version has SSH2 key-derivation bug");
}
if (cfg.sshbug_rsapad2 == BUG_ON ||
(cfg.sshbug_rsapad2 == BUG_AUTO &&
(wc_match("OpenSSH_2.[5-9]*", imp) ||
wc_match("OpenSSH_3.[0-2]*", imp)))) {
/*
* These versions have the SSH2 RSA padding bug.
*/
ssh->remote_bugs |= BUG_SSH2_RSA_PADDING;
logevent("We believe remote version has SSH2 RSA padding bug");
}
if (cfg.sshbug_dhgex2 == BUG_ON) {
/*
* User specified the SSH2 DH GEX bug.
*/
ssh->remote_bugs |= BUG_SSH2_DH_GEX;
logevent("We believe remote version has SSH2 DH group exchange bug");
}
}
static int do_ssh_init(Ssh ssh, unsigned char c)
{
struct do_ssh_init_state {
int vslen;
char version[10];
char *vstring;
int vstrsize;
int i;
int proto1, proto2;
};
crState(do_ssh_init_state);
crBegin(ssh->do_ssh_init_crstate);
/* Search for the string "SSH-" in the input. */
s->i = 0;
while (1) {
static const int transS[] = { 1, 2, 2, 1 };
static const int transH[] = { 0, 0, 3, 0 };
static const int transminus[] = { 0, 0, 0, -1 };
if (c == 'S')
s->i = transS[s->i];
else if (c == 'H')
s->i = transH[s->i];
else if (c == '-')
s->i = transminus[s->i];
else
s->i = 0;
if (s->i < 0)
break;
crReturn(1); /* get another character */
}
s->vstrsize = 16;
s->vstring = smalloc(s->vstrsize);
strcpy(s->vstring, "SSH-");
s->vslen = 4;
s->i = 0;
while (1) {
crReturn(1); /* get another char */
if (s->vslen >= s->vstrsize - 1) {
s->vstrsize += 16;
s->vstring = srealloc(s->vstring, s->vstrsize);
}
s->vstring[s->vslen++] = c;
if (s->i >= 0) {
if (c == '-') {
s->version[s->i] = '\0';
s->i = -1;
} else if (s->i < sizeof(s->version) - 1)
s->version[s->i++] = c;
} else if (c == '\012')
break;
}
ssh->agentfwd_enabled = FALSE;
ssh->rdpkt2_state.incoming_sequence = 0;
s->vstring[s->vslen] = 0;
s->vstring[strcspn(s->vstring, "\r\n")] = '\0';/* remove EOL chars */
{
char *vlog;
vlog = smalloc(20 + s->vslen);
sprintf(vlog, "Server version: %s", s->vstring);
logevent(vlog);
sfree(vlog);
}
ssh_detect_bugs(ssh, s->vstring);
/*
* Decide which SSH protocol version to support.
*/
/* Anything strictly below "2.0" means protocol 1 is supported. */
s->proto1 = ssh_versioncmp(s->version, "2.0") < 0;
/* Anything greater or equal to "1.99" means protocol 2 is supported. */
s->proto2 = ssh_versioncmp(s->version, "1.99") >= 0;
if (cfg.sshprot == 0 && !s->proto1) {
bombout((ssh,"SSH protocol version 1 required by user but not provided by server"));
crReturn(0);
}
if (cfg.sshprot == 3 && !s->proto2) {
bombout((ssh,"SSH protocol version 2 required by user but not provided by server"));
crReturn(0);
}
if (s->proto2 && (cfg.sshprot >= 2 || !s->proto1)) {
/*
* Use v2 protocol.
*/
char verstring[80], vlog[100];
sprintf(verstring, "SSH-2.0-%s", sshver);
SHA_Init(&ssh->exhashbase);
/*
* Hash our version string and their version string.
*/
sha_string(&ssh->exhashbase, verstring, strlen(verstring));
sha_string(&ssh->exhashbase, s->vstring, strcspn(s->vstring, "\r\n"));
sprintf(vlog, "We claim version: %s", verstring);
logevent(vlog);
strcat(verstring, "\012");
logevent("Using SSH protocol version 2");
sk_write(ssh->s, verstring, strlen(verstring));
ssh->protocol = ssh2_protocol;
ssh->version = 2;
ssh->s_rdpkt = ssh2_rdpkt;
} else {
/*
* Use v1 protocol.
*/
char verstring[80], vlog[100];
sprintf(verstring, "SSH-%s-%s",
(ssh_versioncmp(s->version, "1.5") <= 0 ? s->version : "1.5"),
sshver);
sprintf(vlog, "We claim version: %s", verstring);
logevent(vlog);
strcat(verstring, "\012");
logevent("Using SSH protocol version 1");
sk_write(ssh->s, verstring, strlen(verstring));
ssh->protocol = ssh1_protocol;
ssh->version = 1;
ssh->s_rdpkt = ssh1_rdpkt;
}
ssh->state = SSH_STATE_BEFORE_SIZE;
sfree(s->vstring);
crFinish(0);
}
static void ssh_gotdata(Ssh ssh, unsigned char *data, int datalen)
{
crBegin(ssh->ssh_gotdata_crstate);
/*
* To begin with, feed the characters one by one to the
* protocol initialisation / selection function do_ssh_init().
* When that returns 0, we're done with the initial greeting
* exchange and can move on to packet discipline.
*/
while (1) {
int ret; /* need not be kept across crReturn */
if (datalen == 0)
crReturnV; /* more data please */
ret = do_ssh_init(ssh, *data);
data++;
datalen--;
if (ret == 0)
break;
}
/*
* We emerge from that loop when the initial negotiation is
* over and we have selected an s_rdpkt function. Now pass
* everything to s_rdpkt, and then pass the resulting packets
* to the proper protocol handler.
*/
if (datalen == 0)
crReturnV;
while (1) {
while (datalen > 0) {
if (ssh->s_rdpkt(ssh, &data, &datalen) == 0) {
if (ssh->state == SSH_STATE_CLOSED) {
return;
}
ssh->protocol(ssh, NULL, 0, 1);
if (ssh->state == SSH_STATE_CLOSED) {
return;
}
}
}
crReturnV;
}
crFinishV;
}
static int ssh_closing(Plug plug, char *error_msg, int error_code,
int calling_back)
{
Ssh ssh = (Ssh) plug;
ssh->state = SSH_STATE_CLOSED;
if (ssh->s) {
sk_close(ssh->s);
ssh->s = NULL;
}
if (error_msg) {
/* A socket error has occurred. */
logevent(error_msg);
connection_fatal(ssh->frontend, error_msg);
} else {
/* Otherwise, the remote side closed the connection normally. */
}
return 0;
}
static int ssh_receive(Plug plug, int urgent, char *data, int len)
{
Ssh ssh = (Ssh) plug;
ssh_gotdata(ssh, (unsigned char *)data, len);
if (ssh->state == SSH_STATE_CLOSED) {
if (ssh->s) {
sk_close(ssh->s);
ssh->s = NULL;
}
return 0;
}
return 1;
}
static void ssh_sent(Plug plug, int bufsize)
{
Ssh ssh = (Ssh) plug;
/*
* If the send backlog on the SSH socket itself clears, we
* should unthrottle the whole world if it was throttled.
*/
if (bufsize < SSH_MAX_BACKLOG)
ssh_throttle_all(ssh, 0, bufsize);
}
/*
* Connect to specified host and port.
* Returns an error message, or NULL on success.
* Also places the canonical host name into `realhost'. It must be
* freed by the caller.
*/
static char *connect_to_host(Ssh ssh, char *host, int port,
char **realhost, int nodelay)
{
static const struct plug_function_table fn_table = {
ssh_closing,
ssh_receive,
ssh_sent,
NULL
};
SockAddr addr;
char *err;
ssh->savedhost = smalloc(1 + strlen(host));
if (!ssh->savedhost)
fatalbox("Out of memory");
strcpy(ssh->savedhost, host);
if (port < 0)
port = 22; /* default ssh port */
ssh->savedport = port;
/*
* Try to find host.
*/
logeventf(ssh, "Looking up host \"%s\"", host);
addr = name_lookup(host, port, realhost);
if ((err = sk_addr_error(addr)) != NULL)
return err;
/*
* Open socket.
*/
{
char addrbuf[100];
sk_getaddr(addr, addrbuf, 100);
logeventf(ssh, "Connecting to %s port %d", addrbuf, port);
}
ssh->fn = &fn_table;
ssh->s = new_connection(addr, *realhost, port, 0, 1, nodelay, (Plug) ssh);
if ((err = sk_socket_error(ssh->s)) != NULL) {
ssh->s = NULL;
return err;
}
return NULL;
}
/*
* Throttle or unthrottle the SSH connection.
*/
static void ssh1_throttle(Ssh ssh, int adjust)
{
int old_count = ssh->v1_throttle_count;
ssh->v1_throttle_count += adjust;
assert(ssh->v1_throttle_count >= 0);
if (ssh->v1_throttle_count && !old_count) {
sk_set_frozen(ssh->s, 1);
} else if (!ssh->v1_throttle_count && old_count) {
sk_set_frozen(ssh->s, 0);
}
}
/*
* Throttle or unthrottle _all_ local data streams (for when sends
* on the SSH connection itself back up).
*/
static void ssh_throttle_all(Ssh ssh, int enable, int bufsize)
{
int i;
struct ssh_channel *c;
if (enable == ssh->throttled_all)
return;
ssh->throttled_all = enable;
ssh->overall_bufsize = bufsize;
if (!ssh->channels)
return;
for (i = 0; NULL != (c = index234(ssh->channels, i)); i++) {
switch (c->type) {
case CHAN_MAINSESSION:
/*
* This is treated separately, outside the switch.
*/
break;
case CHAN_X11:
x11_override_throttle(c->u.x11.s, enable);
break;
case CHAN_AGENT:
/* Agent channels require no buffer management. */
break;
case CHAN_SOCKDATA:
pfd_override_throttle(c->u.x11.s, enable);
break;
}
}
}
/*
* Username and password input, abstracted off into routines
* reusable in several places - even between SSH1 and SSH2.
*/
/* Set up a username or password input loop on a given buffer. */
static void setup_userpass_input(Ssh ssh, char *buffer, int buflen, int echo)
{
ssh->userpass_input_buffer = buffer;
ssh->userpass_input_buflen = buflen;
ssh->userpass_input_bufpos = 0;
ssh->userpass_input_echo = echo;
}
/*
* Process some terminal data in the course of username/password
* input. Returns >0 for success (line of input returned in
* buffer), <0 for failure (user hit ^C/^D, bomb out and exit), 0
* for inconclusive (keep waiting for more input please).
*/
static int process_userpass_input(Ssh ssh, unsigned char *in, int inlen)
{
char c;
while (inlen--) {
switch (c = *in++) {
case 10:
case 13:
ssh->userpass_input_buffer[ssh->userpass_input_bufpos] = 0;
ssh->userpass_input_buffer[ssh->userpass_input_buflen-1] = 0;
return +1;
break;
case 8:
case 127:
if (ssh->userpass_input_bufpos > 0) {
if (ssh->userpass_input_echo)
c_write_str(ssh, "\b \b");
ssh->userpass_input_bufpos--;
}
break;
case 21:
case 27:
while (ssh->userpass_input_bufpos > 0) {
if (ssh->userpass_input_echo)
c_write_str(ssh, "\b \b");
ssh->userpass_input_bufpos--;
}
break;
case 3:
case 4:
return -1;
break;
default:
if (((c >= ' ' && c <= '~') ||
((unsigned char) c >= 160))
&& ssh->userpass_input_bufpos < ssh->userpass_input_buflen-1) {
ssh->userpass_input_buffer[ssh->userpass_input_bufpos++] = c;
if (ssh->userpass_input_echo)
c_write(ssh, &c, 1);
}
break;
}
}
return 0;
}
/*
* Handle the key exchange and user authentication phases.
*/
static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
{
int i, j;
unsigned char cookie[8];
struct RSAKey servkey, hostkey;
struct MD5Context md5c;
struct do_ssh1_login_state {
int len;
unsigned char *rsabuf, *keystr1, *keystr2;
unsigned long supported_ciphers_mask, supported_auths_mask;
int tried_publickey, tried_agent;
int tis_auth_refused, ccard_auth_refused;
unsigned char session_id[16];
int cipher_type;
char username[100];
void *publickey_blob;
int publickey_bloblen;
char password[100];
char prompt[200];
int pos;
char c;
int pwpkt_type;
unsigned char request[5], *response, *p;
int responselen;
int keyi, nkeys;
int authed;
struct RSAKey key;
Bignum challenge;
char *commentp;
int commentlen;
};
crState(do_ssh1_login_state);
crBegin(ssh->do_ssh1_login_crstate);
if (!ispkt)
crWaitUntil(ispkt);
if (ssh->pktin.type != SSH1_SMSG_PUBLIC_KEY) {
bombout((ssh,"Public key packet not received"));
crReturn(0);
}
logevent("Received public keys");
memcpy(cookie, ssh->pktin.body, 8);
i = makekey(ssh->pktin.body + 8, &servkey, &s->keystr1, 0);
j = makekey(ssh->pktin.body + 8 + i, &hostkey, &s->keystr2, 0);
/*
* Log the host key fingerprint.
*/
{
char logmsg[80];
logevent("Host key fingerprint is:");
strcpy(logmsg, " ");
hostkey.comment = NULL;
rsa_fingerprint(logmsg + strlen(logmsg),
sizeof(logmsg) - strlen(logmsg), &hostkey);
logevent(logmsg);
}
ssh->v1_remote_protoflags = GET_32BIT(ssh->pktin.body + 8 + i + j);
s->supported_ciphers_mask = GET_32BIT(ssh->pktin.body + 12 + i + j);
s->supported_auths_mask = GET_32BIT(ssh->pktin.body + 16 + i + j);
ssh->v1_local_protoflags =
ssh->v1_remote_protoflags & SSH1_PROTOFLAGS_SUPPORTED;
ssh->v1_local_protoflags |= SSH1_PROTOFLAG_SCREEN_NUMBER;
MD5Init(&md5c);
MD5Update(&md5c, s->keystr2, hostkey.bytes);
MD5Update(&md5c, s->keystr1, servkey.bytes);
MD5Update(&md5c, ssh->pktin.body, 8);
MD5Final(s->session_id, &md5c);
for (i = 0; i < 32; i++)
ssh->session_key[i] = random_byte();
s->len = (hostkey.bytes > servkey.bytes ? hostkey.bytes : servkey.bytes);
s->rsabuf = smalloc(s->len);
if (!s->rsabuf)
fatalbox("Out of memory");
/*
* Verify the host key.
*/
{
/*
* First format the key into a string.
*/
int len = rsastr_len(&hostkey);
char fingerprint[100];
char *keystr = smalloc(len);
if (!keystr)
fatalbox("Out of memory");
rsastr_fmt(keystr, &hostkey);
rsa_fingerprint(fingerprint, sizeof(fingerprint), &hostkey);
verify_ssh_host_key(ssh->frontend,
ssh->savedhost, ssh->savedport, "rsa", keystr,
fingerprint);
sfree(keystr);
}
for (i = 0; i < 32; i++) {
s->rsabuf[i] = ssh->session_key[i];
if (i < 16)
s->rsabuf[i] ^= s->session_id[i];
}
if (hostkey.bytes > servkey.bytes) {
rsaencrypt(s->rsabuf, 32, &servkey);
rsaencrypt(s->rsabuf, servkey.bytes, &hostkey);
} else {
rsaencrypt(s->rsabuf, 32, &hostkey);
rsaencrypt(s->rsabuf, hostkey.bytes, &servkey);
}
logevent("Encrypted session key");
{
int cipher_chosen = 0, warn = 0;
char *cipher_string = NULL;
int i;
for (i = 0; !cipher_chosen && i < CIPHER_MAX; i++) {
int next_cipher = cfg.ssh_cipherlist[i];
if (next_cipher == CIPHER_WARN) {
/* If/when we choose a cipher, warn about it */
warn = 1;
} else if (next_cipher == CIPHER_AES) {
/* XXX Probably don't need to mention this. */
logevent("AES not supported in SSH1, skipping");
} else {
switch (next_cipher) {
case CIPHER_3DES: s->cipher_type = SSH_CIPHER_3DES;
cipher_string = "3DES"; break;
case CIPHER_BLOWFISH: s->cipher_type = SSH_CIPHER_BLOWFISH;
cipher_string = "Blowfish"; break;
case CIPHER_DES: s->cipher_type = SSH_CIPHER_DES;
cipher_string = "single-DES"; break;
}
if (s->supported_ciphers_mask & (1 << s->cipher_type))
cipher_chosen = 1;
}
}
if (!cipher_chosen) {
if ((s->supported_ciphers_mask & (1 << SSH_CIPHER_3DES)) == 0)
bombout((ssh,"Server violates SSH 1 protocol by not "
"supporting 3DES encryption"));
else
/* shouldn't happen */
bombout((ssh,"No supported ciphers found"));
crReturn(0);
}
/* Warn about chosen cipher if necessary. */
if (warn)
askcipher(ssh->frontend, cipher_string, 0);
}
switch (s->cipher_type) {
case SSH_CIPHER_3DES:
logevent("Using 3DES encryption");
break;
case SSH_CIPHER_DES:
logevent("Using single-DES encryption");
break;
case SSH_CIPHER_BLOWFISH:
logevent("Using Blowfish encryption");
break;
}
send_packet(ssh, SSH1_CMSG_SESSION_KEY,
PKT_CHAR, s->cipher_type,
PKT_DATA, cookie, 8,
PKT_CHAR, (s->len * 8) >> 8, PKT_CHAR, (s->len * 8) & 0xFF,
PKT_DATA, s->rsabuf, s->len,
PKT_INT, ssh->v1_local_protoflags, PKT_END);
logevent("Trying to enable encryption...");
sfree(s->rsabuf);
ssh->cipher = (s->cipher_type == SSH_CIPHER_BLOWFISH ? &ssh_blowfish_ssh1 :
s->cipher_type == SSH_CIPHER_DES ? &ssh_des :
&ssh_3des);
ssh->v1_cipher_ctx = ssh->cipher->make_context();
ssh->cipher->sesskey(ssh->v1_cipher_ctx, ssh->session_key);
logeventf(ssh, "Initialised %s encryption", ssh->cipher->text_name);
ssh->crcda_ctx = crcda_make_context();
logevent("Installing CRC compensation attack detector");
crWaitUntil(ispkt);
if (ssh->pktin.type != SSH1_SMSG_SUCCESS) {
bombout((ssh,"Encryption not successfully enabled"));
crReturn(0);
}
logevent("Successfully started encryption");
fflush(stdout);
{
if ((flags & FLAG_INTERACTIVE) && !*cfg.username) {
if (ssh_get_line && !ssh_getline_pw_only) {
if (!ssh_get_line("login as: ",
s->username, sizeof(s->username), FALSE)) {
/*
* get_line failed to get a username.
* Terminate.
*/
logevent("No username provided. Abandoning session.");
ssh->state = SSH_STATE_CLOSED;
crReturn(1);
}
} else {
int ret; /* need not be kept over crReturn */
c_write_str(ssh, "login as: ");
ssh->send_ok = 1;
setup_userpass_input(ssh, s->username, sizeof(s->username), 1);
do {
crWaitUntil(!ispkt);
ret = process_userpass_input(ssh, in, inlen);
} while (ret == 0);
if (ret < 0)
cleanup_exit(0);
c_write_str(ssh, "\r\n");
}
} else {
strncpy(s->username, cfg.username, sizeof(s->username));
s->username[sizeof(s->username)-1] = '\0';
}
send_packet(ssh, SSH1_CMSG_USER, PKT_STR, s->username, PKT_END);
{
char userlog[22 + sizeof(s->username)];
sprintf(userlog, "Sent username \"%s\"", s->username);
logevent(userlog);
if (flags & FLAG_INTERACTIVE &&
(!((flags & FLAG_STDERR) && (flags & FLAG_VERBOSE)))) {
strcat(userlog, "\r\n");
c_write_str(ssh, userlog);
}
}
}
crWaitUntil(ispkt);
if ((ssh->remote_bugs & BUG_CHOKES_ON_RSA)) {
/* We must not attempt PK auth. Pretend we've already tried it. */
s->tried_publickey = s->tried_agent = 1;
} else {
s->tried_publickey = s->tried_agent = 0;
}
s->tis_auth_refused = s->ccard_auth_refused = 0;
/* Load the public half of cfg.keyfile so we notice if it's in Pageant */
if (*cfg.keyfile) {
if (!rsakey_pubblob(cfg.keyfile,
&s->publickey_blob, &s->publickey_bloblen))
s->publickey_blob = NULL;
} else
s->publickey_blob = NULL;
while (ssh->pktin.type == SSH1_SMSG_FAILURE) {
s->pwpkt_type = SSH1_CMSG_AUTH_PASSWORD;
if (agent_exists() && !s->tried_agent) {
/*
* Attempt RSA authentication using Pageant.
*/
void *r;
s->authed = FALSE;
s->tried_agent = 1;
logevent("Pageant is running. Requesting keys.");
/* Request the keys held by the agent. */
PUT_32BIT(s->request, 1);
s->request[4] = SSH1_AGENTC_REQUEST_RSA_IDENTITIES;
agent_query(s->request, 5, &r, &s->responselen);
s->response = (unsigned char *) r;
if (s->response && s->responselen >= 5 &&
s->response[4] == SSH1_AGENT_RSA_IDENTITIES_ANSWER) {
s->p = s->response + 5;
s->nkeys = GET_32BIT(s->p);
s->p += 4;
{
char buf[64];
sprintf(buf, "Pageant has %d SSH1 keys", s->nkeys);
logevent(buf);
}
for (s->keyi = 0; s->keyi < s->nkeys; s->keyi++) {
{
char buf[64];
sprintf(buf, "Trying Pageant key #%d", s->keyi);
logevent(buf);
}
if (s->publickey_blob &&
!memcmp(s->p, s->publickey_blob,
s->publickey_bloblen)) {
logevent("This key matches configured key file");
s->tried_publickey = 1;
}
s->p += 4;
s->p += ssh1_read_bignum(s->p, &s->key.exponent);
s->p += ssh1_read_bignum(s->p, &s->key.modulus);
s->commentlen = GET_32BIT(s->p);
s->p += 4;
s->commentp = (char *)s->p;
s->p += s->commentlen;
send_packet(ssh, SSH1_CMSG_AUTH_RSA,
PKT_BIGNUM, s->key.modulus, PKT_END);
crWaitUntil(ispkt);
if (ssh->pktin.type != SSH1_SMSG_AUTH_RSA_CHALLENGE) {
logevent("Key refused");
continue;
}
logevent("Received RSA challenge");
ssh1_read_bignum(ssh->pktin.body, &s->challenge);
{
char *agentreq, *q, *ret;
void *vret;
int len, retlen;
len = 1 + 4; /* message type, bit count */
len += ssh1_bignum_length(s->key.exponent);
len += ssh1_bignum_length(s->key.modulus);
len += ssh1_bignum_length(s->challenge);
len += 16; /* session id */
len += 4; /* response format */
agentreq = smalloc(4 + len);
PUT_32BIT(agentreq, len);
q = agentreq + 4;
*q++ = SSH1_AGENTC_RSA_CHALLENGE;
PUT_32BIT(q, bignum_bitcount(s->key.modulus));
q += 4;
q += ssh1_write_bignum(q, s->key.exponent);
q += ssh1_write_bignum(q, s->key.modulus);
q += ssh1_write_bignum(q, s->challenge);
memcpy(q, s->session_id, 16);
q += 16;
PUT_32BIT(q, 1); /* response format */
agent_query(agentreq, len + 4, &vret, &retlen);
ret = vret;
sfree(agentreq);
if (ret) {
if (ret[4] == SSH1_AGENT_RSA_RESPONSE) {
logevent("Sending Pageant's response");
send_packet(ssh, SSH1_CMSG_AUTH_RSA_RESPONSE,
PKT_DATA, ret + 5, 16,
PKT_END);
sfree(ret);
crWaitUntil(ispkt);
if (ssh->pktin.type == SSH1_SMSG_SUCCESS) {
logevent
("Pageant's response accepted");
if (flags & FLAG_VERBOSE) {
c_write_str(ssh, "Authenticated using"
" RSA key \"");
c_write(ssh, s->commentp,
s->commentlen);
c_write_str(ssh, "\" from agent\r\n");
}
s->authed = TRUE;
} else
logevent
("Pageant's response not accepted");
} else {
logevent
("Pageant failed to answer challenge");
sfree(ret);
}
} else {
logevent("No reply received from Pageant");
}
}
freebn(s->key.exponent);
freebn(s->key.modulus);
freebn(s->challenge);
if (s->authed)
break;
}
}
if (s->authed)
break;
}
if (*cfg.keyfile && !s->tried_publickey)
s->pwpkt_type = SSH1_CMSG_AUTH_RSA;
if (cfg.try_tis_auth &&
(s->supported_auths_mask & (1 << SSH1_AUTH_TIS)) &&
!s->tis_auth_refused) {
s->pwpkt_type = SSH1_CMSG_AUTH_TIS_RESPONSE;
logevent("Requested TIS authentication");
send_packet(ssh, SSH1_CMSG_AUTH_TIS, PKT_END);
crWaitUntil(ispkt);
if (ssh->pktin.type != SSH1_SMSG_AUTH_TIS_CHALLENGE) {
logevent("TIS authentication declined");
if (flags & FLAG_INTERACTIVE)
c_write_str(ssh, "TIS authentication refused.\r\n");
s->tis_auth_refused = 1;
continue;
} else {
int challengelen = GET_32BIT(ssh->pktin.body);
logevent("Received TIS challenge");
if (challengelen > sizeof(s->prompt) - 1)
challengelen = sizeof(s->prompt) - 1;/* prevent overrun */
memcpy(s->prompt, ssh->pktin.body + 4, challengelen);
/* Prompt heuristic comes from OpenSSH */
strncpy(s->prompt + challengelen,
memchr(s->prompt, '\n', challengelen) ?
"": "\r\nResponse: ",
(sizeof s->prompt) - challengelen);
s->prompt[(sizeof s->prompt) - 1] = '\0';
}
}
if (cfg.try_tis_auth &&
(s->supported_auths_mask & (1 << SSH1_AUTH_CCARD)) &&
!s->ccard_auth_refused) {
s->pwpkt_type = SSH1_CMSG_AUTH_CCARD_RESPONSE;
logevent("Requested CryptoCard authentication");
send_packet(ssh, SSH1_CMSG_AUTH_CCARD, PKT_END);
crWaitUntil(ispkt);
if (ssh->pktin.type != SSH1_SMSG_AUTH_CCARD_CHALLENGE) {
logevent("CryptoCard authentication declined");
c_write_str(ssh, "CryptoCard authentication refused.\r\n");
s->ccard_auth_refused = 1;
continue;
} else {
int challengelen = GET_32BIT(ssh->pktin.body);
logevent("Received CryptoCard challenge");
if (challengelen > sizeof(s->prompt) - 1)
challengelen = sizeof(s->prompt) - 1;/* prevent overrun */
memcpy(s->prompt, ssh->pktin.body + 4, challengelen);
strncpy(s->prompt + challengelen,
memchr(s->prompt, '\n', challengelen) ?
"" : "\r\nResponse: ",
sizeof(s->prompt) - challengelen);
s->prompt[sizeof(s->prompt) - 1] = '\0';
}
}
if (s->pwpkt_type == SSH1_CMSG_AUTH_PASSWORD) {
sprintf(s->prompt, "%.90s@%.90s's password: ",
s->username, ssh->savedhost);
}
if (s->pwpkt_type == SSH1_CMSG_AUTH_RSA) {
char *comment = NULL;
int type;
char msgbuf[256];
if (flags & FLAG_VERBOSE)
c_write_str(ssh, "Trying public key authentication.\r\n");
logeventf(ssh, "Trying public key \"%s\"", cfg.keyfile);
type = key_type(cfg.keyfile);
if (type != SSH_KEYTYPE_SSH1) {
sprintf(msgbuf, "Key is of wrong type (%s)",
key_type_to_str(type));
logevent(msgbuf);
c_write_str(ssh, msgbuf);
c_write_str(ssh, "\r\n");
s->tried_publickey = 1;
continue;
}
if (!rsakey_encrypted(cfg.keyfile, &comment)) {
if (flags & FLAG_VERBOSE)
c_write_str(ssh, "No passphrase required.\r\n");
goto tryauth;
}
sprintf(s->prompt, "Passphrase for key \"%.100s\": ", comment);
sfree(comment);
}
/*
* Show password prompt, having first obtained it via a TIS
* or CryptoCard exchange if we're doing TIS or CryptoCard
* authentication.
*/
if (ssh_get_line) {
if (!ssh_get_line(s->prompt, s->password,
sizeof(s->password), TRUE)) {
/*
* get_line failed to get a password (for example
* because one was supplied on the command line
* which has already failed to work). Terminate.
*/
send_packet(ssh, SSH1_MSG_DISCONNECT,
PKT_STR, "No more passwords available to try",
PKT_END);
logevent("Unable to authenticate");
connection_fatal(ssh->frontend, "Unable to authenticate");
ssh->state = SSH_STATE_CLOSED;
crReturn(1);
}
} else {
/* Prompt may have come from server. We've munged it a bit, so
* we know it to be zero-terminated at least once. */
int ret; /* need not be saved over crReturn */
c_write_untrusted(ssh, s->prompt, strlen(s->prompt));
s->pos = 0;
setup_userpass_input(ssh, s->password, sizeof(s->password), 0);
do {
crWaitUntil(!ispkt);
ret = process_userpass_input(ssh, in, inlen);
} while (ret == 0);
if (ret < 0)
cleanup_exit(0);
c_write_str(ssh, "\r\n");
}
tryauth:
if (s->pwpkt_type == SSH1_CMSG_AUTH_RSA) {
/*
* Try public key authentication with the specified
* key file.
*/
s->tried_publickey = 1;
{
int ret = loadrsakey(cfg.keyfile, &s->key, s->password);
if (ret == 0) {
c_write_str(ssh, "Couldn't load private key from ");
c_write_str(ssh, cfg.keyfile);
c_write_str(ssh, ".\r\n");
continue; /* go and try password */
}
if (ret == -1) {
c_write_str(ssh, "Wrong passphrase.\r\n");
s->tried_publickey = 0;
continue; /* try again */
}
}
/*
* Send a public key attempt.
*/
send_packet(ssh, SSH1_CMSG_AUTH_RSA,
PKT_BIGNUM, s->key.modulus, PKT_END);
crWaitUntil(ispkt);
if (ssh->pktin.type == SSH1_SMSG_FAILURE) {
c_write_str(ssh, "Server refused our public key.\r\n");
continue; /* go and try password */
}
if (ssh->pktin.type != SSH1_SMSG_AUTH_RSA_CHALLENGE) {
bombout((ssh,"Bizarre response to offer of public key"));
crReturn(0);
}
{
int i;
unsigned char buffer[32];
Bignum challenge, response;
ssh1_read_bignum(ssh->pktin.body, &challenge);
response = rsadecrypt(challenge, &s->key);
freebn(s->key.private_exponent);/* burn the evidence */
for (i = 0; i < 32; i++) {
buffer[i] = bignum_byte(response, 31 - i);
}
MD5Init(&md5c);
MD5Update(&md5c, buffer, 32);
MD5Update(&md5c, s->session_id, 16);
MD5Final(buffer, &md5c);
send_packet(ssh, SSH1_CMSG_AUTH_RSA_RESPONSE,
PKT_DATA, buffer, 16, PKT_END);
freebn(challenge);
freebn(response);
}
crWaitUntil(ispkt);
if (ssh->pktin.type == SSH1_SMSG_FAILURE) {
if (flags & FLAG_VERBOSE)
c_write_str(ssh, "Failed to authenticate with"
" our public key.\r\n");
continue; /* go and try password */
} else if (ssh->pktin.type != SSH1_SMSG_SUCCESS) {
bombout((ssh,"Bizarre response to RSA authentication response"));
crReturn(0);
}
break; /* we're through! */
} else {
if (s->pwpkt_type == SSH1_CMSG_AUTH_PASSWORD) {
/*
* Defence against traffic analysis: we send a
* whole bunch of packets containing strings of
* different lengths. One of these strings is the
* password, in a SSH1_CMSG_AUTH_PASSWORD packet.
* The others are all random data in
* SSH1_MSG_IGNORE packets. This way a passive
* listener can't tell which is the password, and
* hence can't deduce the password length.
*
* Anybody with a password length greater than 16
* bytes is going to have enough entropy in their
* password that a listener won't find it _that_
* much help to know how long it is. So what we'll
* do is:
*
* - if password length < 16, we send 15 packets
* containing string lengths 1 through 15
*
* - otherwise, we let N be the nearest multiple
* of 8 below the password length, and send 8
* packets containing string lengths N through
* N+7. This won't obscure the order of
* magnitude of the password length, but it will
* introduce a bit of extra uncertainty.
*
* A few servers (the old 1.2.18 through 1.2.22)
* can't deal with SSH1_MSG_IGNORE. For these
* servers, we need an alternative defence. We make
* use of the fact that the password is interpreted
* as a C string: so we can append a NUL, then some
* random data.
*
* One server (a Cisco one) can deal with neither
* SSH1_MSG_IGNORE _nor_ a padded password string.
* For this server we are left with no defences
* against password length sniffing.
*/
if (!(ssh->remote_bugs & BUG_CHOKES_ON_SSH1_IGNORE)) {
/*
* The server can deal with SSH1_MSG_IGNORE, so
* we can use the primary defence.
*/
int bottom, top, pwlen, i;
char *randomstr;
pwlen = strlen(s->password);
if (pwlen < 16) {
bottom = 0; /* zero length passwords are OK! :-) */
top = 15;
} else {
bottom = pwlen & ~7;
top = bottom + 7;
}
assert(pwlen >= bottom && pwlen <= top);
randomstr = smalloc(top + 1);
for (i = bottom; i <= top; i++) {
if (i == pwlen)
defer_packet(ssh, s->pwpkt_type,
PKT_STR, s->password, PKT_END);
else {
for (j = 0; j < i; j++) {
do {
randomstr[j] = random_byte();
} while (randomstr[j] == '\0');
}
randomstr[i] = '\0';
defer_packet(ssh, SSH1_MSG_IGNORE,
PKT_STR, randomstr, PKT_END);
}
}
logevent("Sending password with camouflage packets");
ssh_pkt_defersend(ssh);
}
else if (!(ssh->remote_bugs & BUG_NEEDS_SSH1_PLAIN_PASSWORD)) {
/*
* The server can't deal with SSH1_MSG_IGNORE
* but can deal with padded passwords, so we
* can use the secondary defence.
*/
char string[64];
char *ss;
int len;
len = strlen(s->password);
if (len < sizeof(string)) {
ss = string;
strcpy(string, s->password);
len++; /* cover the zero byte */
while (len < sizeof(string)) {
string[len++] = (char) random_byte();
}
} else {
ss = s->password;
}
logevent("Sending length-padded password");
send_packet(ssh, s->pwpkt_type, PKT_INT, len,
PKT_DATA, ss, len, PKT_END);
} else {
/*
* The server has _both_
* BUG_CHOKES_ON_SSH1_IGNORE and
* BUG_NEEDS_SSH1_PLAIN_PASSWORD. There is
* therefore nothing we can do.
*/
int len;
len = strlen(s->password);
logevent("Sending unpadded password");
send_packet(ssh, s->pwpkt_type, PKT_INT, len,
PKT_DATA, s->password, len, PKT_END);
}
} else {
send_packet(ssh, s->pwpkt_type, PKT_STR, s->password, PKT_END);
}
}
logevent("Sent password");
memset(s->password, 0, strlen(s->password));
crWaitUntil(ispkt);
if (ssh->pktin.type == SSH1_SMSG_FAILURE) {
if (flags & FLAG_VERBOSE)
c_write_str(ssh, "Access denied\r\n");
logevent("Authentication refused");
} else if (ssh->pktin.type != SSH1_SMSG_SUCCESS) {
bombout((ssh,"Strange packet received, type %d", ssh->pktin.type));
crReturn(0);
}
}
logevent("Authentication successful");
crFinish(1);
}
void sshfwd_close(struct ssh_channel *c)
{
Ssh ssh = c->ssh;
if (c && !c->closes) {
/*
* If the channel's remoteid is -1, we have sent
* CHANNEL_OPEN for this channel, but it hasn't even been
* acknowledged by the server. So we must set a close flag
* on it now, and then when the server acks the channel
* open, we can close it then.
*/
if (((int)c->remoteid) != -1) {
if (ssh->version == 1) {
send_packet(ssh, SSH1_MSG_CHANNEL_CLOSE, PKT_INT, c->remoteid,
PKT_END);
} else {
ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_CLOSE);
ssh2_pkt_adduint32(ssh, c->remoteid);
ssh2_pkt_send(ssh);
}
}
c->closes = 1; /* sent MSG_CLOSE */
if (c->type == CHAN_X11) {
c->u.x11.s = NULL;
logevent("Forwarded X11 connection terminated");
} else if (c->type == CHAN_SOCKDATA ||
c->type == CHAN_SOCKDATA_DORMANT) {
c->u.pfd.s = NULL;
logevent("Forwarded port closed");
}
}
}
int sshfwd_write(struct ssh_channel *c, char *buf, int len)
{
Ssh ssh = c->ssh;
if (ssh->version == 1) {
send_packet(ssh, SSH1_MSG_CHANNEL_DATA,
PKT_INT, c->remoteid,
PKT_INT, len, PKT_DATA, buf, len, PKT_END);
/*
* In SSH1 we can return 0 here - implying that forwarded
* connections are never individually throttled - because
* the only circumstance that can cause throttling will be
* the whole SSH connection backing up, in which case
* _everything_ will be throttled as a whole.
*/
return 0;
} else {
ssh2_add_channel_data(c, buf, len);
return ssh2_try_send(c);
}
}
void sshfwd_unthrottle(struct ssh_channel *c, int bufsize)
{
Ssh ssh = c->ssh;
if (ssh->version == 1) {
if (c->v.v1.throttling && bufsize < SSH1_BUFFER_LIMIT) {
c->v.v1.throttling = 0;
ssh1_throttle(ssh, -1);
}
} else {
ssh2_set_window(c, OUR_V2_WINSIZE - bufsize);
}
}
static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
{
crBegin(ssh->ssh1_protocol_crstate);
random_init();
while (!do_ssh1_login(ssh, in, inlen, ispkt)) {
crReturnV;
}
if (ssh->state == SSH_STATE_CLOSED)
crReturnV;
if (cfg.agentfwd && agent_exists()) {
logevent("Requesting agent forwarding");
send_packet(ssh, SSH1_CMSG_AGENT_REQUEST_FORWARDING, PKT_END);
do {
crReturnV;
} while (!ispkt);
if (ssh->pktin.type != SSH1_SMSG_SUCCESS
&& ssh->pktin.type != SSH1_SMSG_FAILURE) {
bombout((ssh,"Protocol confusion"));
crReturnV;
} else if (ssh->pktin.type == SSH1_SMSG_FAILURE) {
logevent("Agent forwarding refused");
} else {
logevent("Agent forwarding enabled");
ssh->agentfwd_enabled = TRUE;
}
}
if (cfg.x11_forward) {
char proto[20], data[64];
logevent("Requesting X11 forwarding");
ssh->x11auth = x11_invent_auth(proto, sizeof(proto),
data, sizeof(data));
x11_get_real_auth(ssh->x11auth, cfg.x11_display);
if (ssh->v1_local_protoflags & SSH1_PROTOFLAG_SCREEN_NUMBER) {
send_packet(ssh, SSH1_CMSG_X11_REQUEST_FORWARDING,
PKT_STR, proto, PKT_STR, data,
PKT_INT, x11_get_screen_number(cfg.x11_display),
PKT_END);
} else {
send_packet(ssh, SSH1_CMSG_X11_REQUEST_FORWARDING,
PKT_STR, proto, PKT_STR, data, PKT_END);
}
do {
crReturnV;
} while (!ispkt);
if (ssh->pktin.type != SSH1_SMSG_SUCCESS
&& ssh->pktin.type != SSH1_SMSG_FAILURE) {
bombout((ssh,"Protocol confusion"));
crReturnV;
} else if (ssh->pktin.type == SSH1_SMSG_FAILURE) {
logevent("X11 forwarding refused");
} else {
logevent("X11 forwarding enabled");
ssh->X11_fwd_enabled = TRUE;
}
}
{
char type;
int n;
int sport,dport,sserv,dserv;
char sports[256], dports[256], saddr[256], host[256];
ssh->rportfwds = newtree234(ssh_rportcmp_ssh1);
/* Add port forwardings. */
ssh->portfwd_strptr = cfg.portfwd;
while (*ssh->portfwd_strptr) {
type = *ssh->portfwd_strptr++;
saddr[0] = '\0';
n = 0;
while (*ssh->portfwd_strptr && *ssh->portfwd_strptr != '\t') {
if (*ssh->portfwd_strptr == ':') {
/*
* We've seen a colon in the middle of the
* source port number. This means that
* everything we've seen until now is the
* source _address_, so we'll move it into
* saddr and start sports from the beginning
* again.
*/
ssh->portfwd_strptr++;
sports[n] = '\0';
strcpy(saddr, sports);
n = 0;
}
if (n < 255) sports[n++] = *ssh->portfwd_strptr++;
}
sports[n] = 0;
if (*ssh->portfwd_strptr == '\t')
ssh->portfwd_strptr++;
n = 0;
while (*ssh->portfwd_strptr && *ssh->portfwd_strptr != ':') {
if (n < 255) host[n++] = *ssh->portfwd_strptr++;
}
host[n] = 0;
if (*ssh->portfwd_strptr == ':')
ssh->portfwd_strptr++;
n = 0;
while (*ssh->portfwd_strptr) {
if (n < 255) dports[n++] = *ssh->portfwd_strptr++;
}
dports[n] = 0;
ssh->portfwd_strptr++;
dport = atoi(dports);
dserv = 0;
if (dport == 0) {
dserv = 1;
dport = net_service_lookup(dports);
if (!dport) {
logeventf(ssh, "Service lookup failed for"
" destination port \"%s\"", dports);
}
}
sport = atoi(sports);
sserv = 0;
if (sport == 0) {
sserv = 1;
sport = net_service_lookup(sports);
if (!sport) {
logeventf(ssh, "Service lookup failed for source"
" port \"%s\"", sports);
}
}
if (sport && dport) {
if (type == 'L') {
pfd_addforward(host, dport, *saddr ? saddr : NULL,
sport, ssh);
logeventf(ssh, "Local port %.*s%.*s%.*s%.*s%d%.*s"
" forwarding to %s:%.*s%.*s%d%.*s",
(int)(*saddr?strlen(saddr):0), *saddr?saddr:NULL,
(int)(*saddr?1:0), ":",
(int)(sserv ? strlen(sports) : 0), sports,
sserv, "(", sport, sserv, ")",
host,
(int)(dserv ? strlen(dports) : 0), dports,
dserv, "(", dport, dserv, ")");
} else {
struct ssh_rportfwd *pf;
pf = smalloc(sizeof(*pf));
strcpy(pf->dhost, host);
pf->dport = dport;
if (saddr) {
logeventf(ssh,
"SSH1 cannot handle source address spec \"%s:%d\"; ignoring",
saddr, sport);
}
if (add234(ssh->rportfwds, pf) != pf) {
logeventf(ssh,
"Duplicate remote port forwarding to %s:%d",
host, dport);
sfree(pf);
} else {
logeventf(ssh, "Requesting remote port %.*s%.*s%d%.*s"
" forward to %s:%.*s%.*s%d%.*s",
(int)(sserv ? strlen(sports) : 0), sports,
sserv, "(", sport, sserv, ")",
host,
(int)(dserv ? strlen(dports) : 0), dports,
dserv, "(", dport, dserv, ")");
send_packet(ssh, SSH1_CMSG_PORT_FORWARD_REQUEST,
PKT_INT, sport,
PKT_STR, host,
PKT_INT, dport,
PKT_END);
do {
crReturnV;
} while (!ispkt);
if (ssh->pktin.type != SSH1_SMSG_SUCCESS
&& ssh->pktin.type != SSH1_SMSG_FAILURE) {
bombout((ssh,"Protocol confusion"));
crReturnV;
} else if (ssh->pktin.type == SSH1_SMSG_FAILURE) {
c_write_str(ssh, "Server refused port"
" forwarding\r\n");
}
logevent("Remote port forwarding enabled");
}
}
}
}
}
if (!cfg.nopty) {
send_packet(ssh, SSH1_CMSG_REQUEST_PTY,
PKT_STR, cfg.termtype,
PKT_INT, ssh->term_height,
PKT_INT, ssh->term_width,
PKT_INT, 0, PKT_INT, 0, PKT_CHAR, 0, PKT_END);
ssh->state = SSH_STATE_INTERMED;
do {
crReturnV;
} while (!ispkt);
if (ssh->pktin.type != SSH1_SMSG_SUCCESS
&& ssh->pktin.type != SSH1_SMSG_FAILURE) {
bombout((ssh,"Protocol confusion"));
crReturnV;
} else if (ssh->pktin.type == SSH1_SMSG_FAILURE) {
c_write_str(ssh, "Server refused to allocate pty\r\n");
ssh->editing = ssh->echoing = 1;
}
logevent("Allocated pty");
} else {
ssh->editing = ssh->echoing = 1;
}
if (cfg.compression) {
send_packet(ssh, SSH1_CMSG_REQUEST_COMPRESSION, PKT_INT, 6, PKT_END);
do {
crReturnV;
} while (!ispkt);
if (ssh->pktin.type != SSH1_SMSG_SUCCESS
&& ssh->pktin.type != SSH1_SMSG_FAILURE) {
bombout((ssh,"Protocol confusion"));
crReturnV;
} else if (ssh->pktin.type == SSH1_SMSG_FAILURE) {
c_write_str(ssh, "Server refused to compress\r\n");
}
logevent("Started compression");
ssh->v1_compressing = TRUE;
ssh->cs_comp_ctx = zlib_compress_init();
logevent("Initialised zlib (RFC1950) compression");
ssh->sc_comp_ctx = zlib_decompress_init();
logevent("Initialised zlib (RFC1950) decompression");
}
/*
* Start the shell or command.
*
* Special case: if the first-choice command is an SSH2
* subsystem (hence not usable here) and the second choice
* exists, we fall straight back to that.
*/
{
char *cmd = cfg.remote_cmd_ptr;
if (cfg.ssh_subsys && cfg.remote_cmd_ptr2) {
cmd = cfg.remote_cmd_ptr2;
ssh->fallback_cmd = TRUE;
}
if (*cmd)
send_packet(ssh, SSH1_CMSG_EXEC_CMD, PKT_STR, cmd, PKT_END);
else
send_packet(ssh, SSH1_CMSG_EXEC_SHELL, PKT_END);
logevent("Started session");
}
ssh->state = SSH_STATE_SESSION;
if (ssh->size_needed)
ssh_size(ssh, ssh->term_width, ssh->term_height);
if (ssh->eof_needed)
ssh_special(ssh, TS_EOF);
if (ssh->ldisc)
ldisc_send(ssh->ldisc, NULL, 0, 0);/* cause ldisc to notice changes */
ssh->send_ok = 1;
ssh->channels = newtree234(ssh_channelcmp);
while (1) {
crReturnV;
if (ispkt) {
if (ssh->pktin.type == SSH1_SMSG_STDOUT_DATA ||
ssh->pktin.type == SSH1_SMSG_STDERR_DATA) {
long len = GET_32BIT(ssh->pktin.body);
int bufsize =
from_backend(ssh->frontend,
ssh->pktin.type == SSH1_SMSG_STDERR_DATA,
(char *)(ssh->pktin.body) + 4, len);
if (!ssh->v1_stdout_throttling && bufsize > SSH1_BUFFER_LIMIT) {
ssh->v1_stdout_throttling = 1;
ssh1_throttle(ssh, +1);
}
} else if (ssh->pktin.type == SSH1_MSG_DISCONNECT) {
ssh->state = SSH_STATE_CLOSED;
logevent("Received disconnect request");
crReturnV;
} else if (ssh->pktin.type == SSH1_SMSG_X11_OPEN) {
/* Remote side is trying to open a channel to talk to our
* X-Server. Give them back a local channel number. */
struct ssh_channel *c;
logevent("Received X11 connect request");
/* Refuse if X11 forwarding is disabled. */
if (!ssh->X11_fwd_enabled) {
send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_FAILURE,
PKT_INT, GET_32BIT(ssh->pktin.body), PKT_END);
logevent("Rejected X11 connect request");
} else {
c = smalloc(sizeof(struct ssh_channel));
c->ssh = ssh;
if (x11_init(&c->u.x11.s, cfg.x11_display, c,
ssh->x11auth) != NULL) {
logevent("opening X11 forward connection failed");
sfree(c);
send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_FAILURE,
PKT_INT, GET_32BIT(ssh->pktin.body),
PKT_END);
} else {
logevent
("opening X11 forward connection succeeded");
c->remoteid = GET_32BIT(ssh->pktin.body);
c->localid = alloc_channel_id(ssh);
c->closes = 0;
c->v.v1.throttling = 0;
c->type = CHAN_X11; /* identify channel type */
add234(ssh->channels, c);
send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_CONFIRMATION,
PKT_INT, c->remoteid, PKT_INT,
c->localid, PKT_END);
logevent("Opened X11 forward channel");
}
}
} else if (ssh->pktin.type == SSH1_SMSG_AGENT_OPEN) {
/* Remote side is trying to open a channel to talk to our
* agent. Give them back a local channel number. */
struct ssh_channel *c;
/* Refuse if agent forwarding is disabled. */
if (!ssh->agentfwd_enabled) {
send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_FAILURE,
PKT_INT, GET_32BIT(ssh->pktin.body), PKT_END);
} else {
c = smalloc(sizeof(struct ssh_channel));
c->ssh = ssh;
c->remoteid = GET_32BIT(ssh->pktin.body);
c->localid = alloc_channel_id(ssh);
c->closes = 0;
c->v.v1.throttling = 0;
c->type = CHAN_AGENT; /* identify channel type */
c->u.a.lensofar = 0;
add234(ssh->channels, c);
send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_CONFIRMATION,
PKT_INT, c->remoteid, PKT_INT, c->localid,
PKT_END);
}
} else if (ssh->pktin.type == SSH1_MSG_PORT_OPEN) {
/* Remote side is trying to open a channel to talk to a
* forwarded port. Give them back a local channel number. */
struct ssh_channel *c;
struct ssh_rportfwd pf;
int hostsize, port;
char host[256], buf[1024];
char *p, *h, *e;
c = smalloc(sizeof(struct ssh_channel));
c->ssh = ssh;
hostsize = GET_32BIT(ssh->pktin.body+4);
for (h = host, p = (char *)(ssh->pktin.body+8);
hostsize != 0; hostsize--) {
if (h+1 < host+sizeof(host))
*h++ = *p;
p++;
}
*h = 0;
port = GET_32BIT(p);
strcpy(pf.dhost, host);
pf.dport = port;
if (find234(ssh->rportfwds, &pf, NULL) == NULL) {
sprintf(buf, "Rejected remote port open request for %s:%d",
host, port);
logevent(buf);
send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_FAILURE,
PKT_INT, GET_32BIT(ssh->pktin.body), PKT_END);
} else {
sprintf(buf, "Received remote port open request for %s:%d",
host, port);
logevent(buf);
e = pfd_newconnect(&c->u.pfd.s, host, port, c);
if (e != NULL) {
char buf[256];
sprintf(buf, "Port open failed: %s", e);
logevent(buf);
sfree(c);
send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_FAILURE,
PKT_INT, GET_32BIT(ssh->pktin.body),
PKT_END);
} else {
c->remoteid = GET_32BIT(ssh->pktin.body);
c->localid = alloc_channel_id(ssh);
c->closes = 0;
c->v.v1.throttling = 0;
c->type = CHAN_SOCKDATA; /* identify channel type */
add234(ssh->channels, c);
send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_CONFIRMATION,
PKT_INT, c->remoteid, PKT_INT,
c->localid, PKT_END);
logevent("Forwarded port opened successfully");
}
}
} else if (ssh->pktin.type == SSH1_MSG_CHANNEL_OPEN_CONFIRMATION) {
unsigned int remoteid = GET_32BIT(ssh->pktin.body);
unsigned int localid = GET_32BIT(ssh->pktin.body+4);
struct ssh_channel *c;
c = find234(ssh->channels, &remoteid, ssh_channelfind);
if (c && c->type == CHAN_SOCKDATA_DORMANT) {
c->remoteid = localid;
c->type = CHAN_SOCKDATA;
c->v.v1.throttling = 0;
pfd_confirm(c->u.pfd.s);
}
if (c && c->closes) {
/*
* We have a pending close on this channel,
* which we decided on before the server acked
* the channel open. So now we know the
* remoteid, we can close it again.
*/
send_packet(ssh, SSH1_MSG_CHANNEL_CLOSE,
PKT_INT, c->remoteid, PKT_END);
}
} else if (ssh->pktin.type == SSH1_MSG_CHANNEL_OPEN_FAILURE) {
unsigned int remoteid = GET_32BIT(ssh->pktin.body);
struct ssh_channel *c;
c = find234(ssh->channels, &remoteid, ssh_channelfind);
if (c && c->type == CHAN_SOCKDATA_DORMANT) {
logevent("Forwarded connection refused by server");
pfd_close(c->u.pfd.s);
del234(ssh->channels, c);
sfree(c);
}
} else if (ssh->pktin.type == SSH1_MSG_CHANNEL_CLOSE ||
ssh->pktin.type == SSH1_MSG_CHANNEL_CLOSE_CONFIRMATION) {
/* Remote side closes a channel. */
unsigned i = GET_32BIT(ssh->pktin.body);
struct ssh_channel *c;
c = find234(ssh->channels, &i, ssh_channelfind);
if (c && ((int)c->remoteid) != -1) {
int closetype;
closetype =
(ssh->pktin.type == SSH1_MSG_CHANNEL_CLOSE ? 1 : 2);
if ((c->closes == 0) && (c->type == CHAN_X11)) {
logevent("Forwarded X11 connection terminated");
assert(c->u.x11.s != NULL);
x11_close(c->u.x11.s);
c->u.x11.s = NULL;
}
if ((c->closes == 0) && (c->type == CHAN_SOCKDATA)) {
logevent("Forwarded port closed");
assert(c->u.pfd.s != NULL);
pfd_close(c->u.pfd.s);
c->u.pfd.s = NULL;
}
c->closes |= (closetype << 2); /* seen this message */
if (!(c->closes & closetype)) {
send_packet(ssh, ssh->pktin.type, PKT_INT, c->remoteid,
PKT_END);
c->closes |= closetype; /* sent it too */
}
if (c->closes == 15) {
del234(ssh->channels, c);
sfree(c);
}
} else {
bombout((ssh,"Received CHANNEL_CLOSE%s for %s channel %d\n",
ssh->pktin.type == SSH1_MSG_CHANNEL_CLOSE ? "" :
"_CONFIRMATION", c ? "half-open" : "nonexistent",
i));
}
} else if (ssh->pktin.type == SSH1_MSG_CHANNEL_DATA) {
/* Data sent down one of our channels. */
int i = GET_32BIT(ssh->pktin.body);
int len = GET_32BIT(ssh->pktin.body + 4);
unsigned char *p = ssh->pktin.body + 8;
struct ssh_channel *c;
c = find234(ssh->channels, &i, ssh_channelfind);
if (c) {
int bufsize;
switch (c->type) {
case CHAN_X11:
bufsize = x11_send(c->u.x11.s, (char *)p, len);
break;
case CHAN_SOCKDATA:
bufsize = pfd_send(c->u.pfd.s, (char *)p, len);
break;
case CHAN_AGENT:
/* Data for an agent message. Buffer it. */
while (len > 0) {
if (c->u.a.lensofar < 4) {
int l = min(4 - c->u.a.lensofar, len);
memcpy(c->u.a.msglen + c->u.a.lensofar, p,
l);
p += l;
len -= l;
c->u.a.lensofar += l;
}
if (c->u.a.lensofar == 4) {
c->u.a.totallen =
4 + GET_32BIT(c->u.a.msglen);
c->u.a.message = smalloc(c->u.a.totallen);
memcpy(c->u.a.message, c->u.a.msglen, 4);
}
if (c->u.a.lensofar >= 4 && len > 0) {
int l =
min(c->u.a.totallen - c->u.a.lensofar,
len);
memcpy(c->u.a.message + c->u.a.lensofar, p,
l);
p += l;
len -= l;
c->u.a.lensofar += l;
}
if (c->u.a.lensofar == c->u.a.totallen) {
void *reply, *sentreply;
int replylen;
agent_query(c->u.a.message,
c->u.a.totallen, &reply,
&replylen);
if (reply)
sentreply = reply;
else {
/* Fake SSH_AGENT_FAILURE. */
sentreply = "\0\0\0\1\5";
replylen = 5;
}
send_packet(ssh, SSH1_MSG_CHANNEL_DATA,
PKT_INT, c->remoteid,
PKT_INT, replylen,
PKT_DATA, sentreply, replylen,
PKT_END);
if (reply)
sfree(reply);
sfree(c->u.a.message);
c->u.a.lensofar = 0;
}
}
bufsize = 0; /* agent channels never back up */
break;
}
if (!c->v.v1.throttling && bufsize > SSH1_BUFFER_LIMIT) {
c->v.v1.throttling = 1;
ssh1_throttle(ssh, +1);
}
}
} else if (ssh->pktin.type == SSH1_SMSG_SUCCESS) {
/* may be from EXEC_SHELL on some servers */
} else if (ssh->pktin.type == SSH1_SMSG_FAILURE) {
/* may be from EXEC_SHELL on some servers
* if no pty is available or in other odd cases. Ignore */
} else if (ssh->pktin.type == SSH1_SMSG_EXIT_STATUS) {
char buf[100];
ssh->exitcode = GET_32BIT(ssh->pktin.body);
sprintf(buf, "Server sent command exit status %d",
ssh->exitcode);
logevent(buf);
send_packet(ssh, SSH1_CMSG_EXIT_CONFIRMATION, PKT_END);
/*
* In case `helpful' firewalls or proxies tack
* extra human-readable text on the end of the
* session which we might mistake for another
* encrypted packet, we close the session once
* we've sent EXIT_CONFIRMATION.
*/
ssh->state = SSH_STATE_CLOSED;
crReturnV;
} else {
bombout((ssh,"Strange packet received: type %d", ssh->pktin.type));
crReturnV;
}
} else {
while (inlen > 0) {
int len = min(inlen, 512);
send_packet(ssh, SSH1_CMSG_STDIN_DATA,
PKT_INT, len, PKT_DATA, in, len, PKT_END);
in += len;
inlen -= len;
}
}
}
crFinishV;
}
/*
* Utility routine for decoding comma-separated strings in KEXINIT.
*/
static int in_commasep_string(char *needle, char *haystack, int haylen)
{
int needlen;
if (!needle || !haystack) /* protect against null pointers */
return 0;
needlen = strlen(needle);
while (1) {
/*
* Is it at the start of the string?
*/
if (haylen >= needlen && /* haystack is long enough */
!memcmp(needle, haystack, needlen) && /* initial match */
(haylen == needlen || haystack[needlen] == ',')
/* either , or EOS follows */
)
return 1;
/*
* If not, search for the next comma and resume after that.
* If no comma found, terminate.
*/
while (haylen > 0 && *haystack != ',')
haylen--, haystack++;
if (haylen == 0)
return 0;
haylen--, haystack++; /* skip over comma itself */
}
}
/*
* SSH2 key creation method.
*/
static void ssh2_mkkey(Ssh ssh, Bignum K, unsigned char *H,
unsigned char *sessid, char chr,
unsigned char *keyspace)
{
SHA_State s;
/* First 20 bytes. */
SHA_Init(&s);
if (!(ssh->remote_bugs & BUG_SSH2_DERIVEKEY))
sha_mpint(&s, K);
SHA_Bytes(&s, H, 20);
SHA_Bytes(&s, &chr, 1);
SHA_Bytes(&s, sessid, 20);
SHA_Final(&s, keyspace);
/* Next 20 bytes. */
SHA_Init(&s);
if (!(ssh->remote_bugs & BUG_SSH2_DERIVEKEY))
sha_mpint(&s, K);
SHA_Bytes(&s, H, 20);
SHA_Bytes(&s, keyspace, 20);
SHA_Final(&s, keyspace + 20);
}
/*
* Handle the SSH2 transport layer.
*/
static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
{
struct do_ssh2_transport_state {
int nbits, pbits, warn;
Bignum p, g, e, f, K;
int kex_init_value, kex_reply_value;
const struct ssh_mac **maclist;
int nmacs;
const struct ssh2_cipher *cscipher_tobe;
const struct ssh2_cipher *sccipher_tobe;
const struct ssh_mac *csmac_tobe;
const struct ssh_mac *scmac_tobe;
const struct ssh_compress *cscomp_tobe;
const struct ssh_compress *sccomp_tobe;
char *hostkeydata, *sigdata, *keystr, *fingerprint;
int hostkeylen, siglen;
void *hkey; /* actual host key */
unsigned char exchange_hash[20];
int n_preferred_ciphers;
const struct ssh2_ciphers *preferred_ciphers[CIPHER_MAX];
const struct ssh_compress *preferred_comp;
int first_kex;
};
crState(do_ssh2_transport_state);
crBegin(ssh->do_ssh2_transport_crstate);
s->cscipher_tobe = s->sccipher_tobe = NULL;
s->csmac_tobe = s->scmac_tobe = NULL;
s->cscomp_tobe = s->sccomp_tobe = NULL;
random_init();
s->first_kex = 1;
{
int i;
/*
* Set up the preferred ciphers. (NULL => warn below here)
*/
s->n_preferred_ciphers = 0;
for (i = 0; i < CIPHER_MAX; i++) {
switch (cfg.ssh_cipherlist[i]) {
case CIPHER_BLOWFISH:
s->preferred_ciphers[s->n_preferred_ciphers++] = &ssh2_blowfish;
break;
case CIPHER_DES:
if (cfg.ssh2_des_cbc) {
s->preferred_ciphers[s->n_preferred_ciphers++] = &ssh2_des;
}
break;
case CIPHER_3DES:
s->preferred_ciphers[s->n_preferred_ciphers++] = &ssh2_3des;
break;
case CIPHER_AES:
s->preferred_ciphers[s->n_preferred_ciphers++] = &ssh2_aes;
break;
case CIPHER_WARN:
/* Flag for later. Don't bother if it's the last in
* the list. */
if (i < CIPHER_MAX - 1) {
s->preferred_ciphers[s->n_preferred_ciphers++] = NULL;
}
break;
}
}
}
/*
* Set up preferred compression.
*/
if (cfg.compression)
s->preferred_comp = &ssh_zlib;
else
s->preferred_comp = &ssh_comp_none;
/*
* Be prepared to work around the buggy MAC problem.
*/
if (ssh->remote_bugs & BUG_SSH2_HMAC)
s->maclist = buggymacs, s->nmacs = lenof(buggymacs);
else
s->maclist = macs, s->nmacs = lenof(macs);
begin_key_exchange:
{
int i, j, cipherstr_started;
/*
* Construct and send our key exchange packet.
*/
ssh2_pkt_init(ssh, SSH2_MSG_KEXINIT);
for (i = 0; i < 16; i++)
ssh2_pkt_addbyte(ssh, (unsigned char) random_byte());
/* List key exchange algorithms. */
ssh2_pkt_addstring_start(ssh);
for (i = 0; i < lenof(kex_algs); i++) {
if (kex_algs[i] == &ssh_diffiehellman_gex &&
(ssh->remote_bugs & BUG_SSH2_DH_GEX))
continue;
ssh2_pkt_addstring_str(ssh, kex_algs[i]->name);
if (i < lenof(kex_algs) - 1)
ssh2_pkt_addstring_str(ssh, ",");
}
/* List server host key algorithms. */
ssh2_pkt_addstring_start(ssh);
for (i = 0; i < lenof(hostkey_algs); i++) {
ssh2_pkt_addstring_str(ssh, hostkey_algs[i]->name);
if (i < lenof(hostkey_algs) - 1)
ssh2_pkt_addstring_str(ssh, ",");
}
/* List client->server encryption algorithms. */
ssh2_pkt_addstring_start(ssh);
cipherstr_started = 0;
for (i = 0; i < s->n_preferred_ciphers; i++) {
const struct ssh2_ciphers *c = s->preferred_ciphers[i];
if (!c) continue; /* warning flag */
for (j = 0; j < c->nciphers; j++) {
if (cipherstr_started)
ssh2_pkt_addstring_str(ssh, ",");
ssh2_pkt_addstring_str(ssh, c->list[j]->name);
cipherstr_started = 1;
}
}
/* List server->client encryption algorithms. */
ssh2_pkt_addstring_start(ssh);
cipherstr_started = 0;
for (i = 0; i < s->n_preferred_ciphers; i++) {
const struct ssh2_ciphers *c = s->preferred_ciphers[i];
if (!c) continue; /* warning flag */
for (j = 0; j < c->nciphers; j++) {
if (cipherstr_started)
ssh2_pkt_addstring_str(ssh, ",");
ssh2_pkt_addstring_str(ssh, c->list[j]->name);
cipherstr_started = 1;
}
}
/* List client->server MAC algorithms. */
ssh2_pkt_addstring_start(ssh);
for (i = 0; i < s->nmacs; i++) {
ssh2_pkt_addstring_str(ssh, s->maclist[i]->name);
if (i < s->nmacs - 1)
ssh2_pkt_addstring_str(ssh, ",");
}
/* List server->client MAC algorithms. */
ssh2_pkt_addstring_start(ssh);
for (i = 0; i < s->nmacs; i++) {
ssh2_pkt_addstring_str(ssh, s->maclist[i]->name);
if (i < s->nmacs - 1)
ssh2_pkt_addstring_str(ssh, ",");
}
/* List client->server compression algorithms. */
ssh2_pkt_addstring_start(ssh);
for (i = 0; i < lenof(compressions) + 1; i++) {
const struct ssh_compress *c =
i == 0 ? s->preferred_comp : compressions[i - 1];
ssh2_pkt_addstring_str(ssh, c->name);
if (i < lenof(compressions))
ssh2_pkt_addstring_str(ssh, ",");
}
/* List server->client compression algorithms. */
ssh2_pkt_addstring_start(ssh);
for (i = 0; i < lenof(compressions) + 1; i++) {
const struct ssh_compress *c =
i == 0 ? s->preferred_comp : compressions[i - 1];
ssh2_pkt_addstring_str(ssh, c->name);
if (i < lenof(compressions))
ssh2_pkt_addstring_str(ssh, ",");
}
/* List client->server languages. Empty list. */
ssh2_pkt_addstring_start(ssh);
/* List server->client languages. Empty list. */
ssh2_pkt_addstring_start(ssh);
/* First KEX packet does _not_ follow, because we're not that brave. */
ssh2_pkt_addbool(ssh, FALSE);
/* Reserved. */
ssh2_pkt_adduint32(ssh, 0);
}
ssh->exhash = ssh->exhashbase;
sha_string(&ssh->exhash, ssh->pktout.data + 5, ssh->pktout.length - 5);
ssh2_pkt_send(ssh);
if (!ispkt)
crWaitUntil(ispkt);
if (ssh->pktin.length > 5)
sha_string(&ssh->exhash, ssh->pktin.data + 5, ssh->pktin.length - 5);
/*
* Now examine the other side's KEXINIT to see what we're up
* to.
*/
{
char *str;
int i, j, len;
if (ssh->pktin.type != SSH2_MSG_KEXINIT) {
bombout((ssh,"expected key exchange packet from server"));
crReturn(0);
}
ssh->kex = NULL;
ssh->hostkey = NULL;
s->cscipher_tobe = NULL;
s->sccipher_tobe = NULL;
s->csmac_tobe = NULL;
s->scmac_tobe = NULL;
s->cscomp_tobe = NULL;
s->sccomp_tobe = NULL;
ssh->pktin.savedpos += 16; /* skip garbage cookie */
ssh2_pkt_getstring(ssh, &str, &len); /* key exchange algorithms */
for (i = 0; i < lenof(kex_algs); i++) {
if (kex_algs[i] == &ssh_diffiehellman_gex &&
(ssh->remote_bugs & BUG_SSH2_DH_GEX))
continue;
if (in_commasep_string(kex_algs[i]->name, str, len)) {
ssh->kex = kex_algs[i];
break;
}
}
ssh2_pkt_getstring(ssh, &str, &len); /* host key algorithms */
for (i = 0; i < lenof(hostkey_algs); i++) {
if (in_commasep_string(hostkey_algs[i]->name, str, len)) {
ssh->hostkey = hostkey_algs[i];
break;
}
}
ssh2_pkt_getstring(ssh, &str, &len); /* client->server cipher */
s->warn = 0;
for (i = 0; i < s->n_preferred_ciphers; i++) {
const struct ssh2_ciphers *c = s->preferred_ciphers[i];
if (!c) {
s->warn = 1;
} else {
for (j = 0; j < c->nciphers; j++) {
if (in_commasep_string(c->list[j]->name, str, len)) {
s->cscipher_tobe = c->list[j];
break;
}
}
}
if (s->cscipher_tobe) {
if (s->warn)
askcipher(ssh->frontend, s->cscipher_tobe->name, 1);
break;
}
}
if (!s->cscipher_tobe) {
bombout((ssh,"Couldn't agree a client-to-server cipher (available: %s)",
str ? str : "(null)"));
crReturn(0);
}
ssh2_pkt_getstring(ssh, &str, &len); /* server->client cipher */
s->warn = 0;
for (i = 0; i < s->n_preferred_ciphers; i++) {
const struct ssh2_ciphers *c = s->preferred_ciphers[i];
if (!c) {
s->warn = 1;
} else {
for (j = 0; j < c->nciphers; j++) {
if (in_commasep_string(c->list[j]->name, str, len)) {
s->sccipher_tobe = c->list[j];
break;
}
}
}
if (s->sccipher_tobe) {
if (s->warn)
askcipher(ssh->frontend, s->sccipher_tobe->name, 2);
break;
}
}
if (!s->sccipher_tobe) {
bombout((ssh,"Couldn't agree a server-to-client cipher (available: %s)",
str ? str : "(null)"));
crReturn(0);
}
ssh2_pkt_getstring(ssh, &str, &len); /* client->server mac */
for (i = 0; i < s->nmacs; i++) {
if (in_commasep_string(s->maclist[i]->name, str, len)) {
s->csmac_tobe = s->maclist[i];
break;
}
}
ssh2_pkt_getstring(ssh, &str, &len); /* server->client mac */
for (i = 0; i < s->nmacs; i++) {
if (in_commasep_string(s->maclist[i]->name, str, len)) {
s->scmac_tobe = s->maclist[i];
break;
}
}
ssh2_pkt_getstring(ssh, &str, &len); /* client->server compression */
for (i = 0; i < lenof(compressions) + 1; i++) {
const struct ssh_compress *c =
i == 0 ? s->preferred_comp : compressions[i - 1];
if (in_commasep_string(c->name, str, len)) {
s->cscomp_tobe = c;
break;
}
}
ssh2_pkt_getstring(ssh, &str, &len); /* server->client compression */
for (i = 0; i < lenof(compressions) + 1; i++) {
const struct ssh_compress *c =
i == 0 ? s->preferred_comp : compressions[i - 1];
if (in_commasep_string(c->name, str, len)) {
s->sccomp_tobe = c;
break;
}
}
}
/*
* Work out the number of bits of key we will need from the key
* exchange. We start with the maximum key length of either
* cipher...
*/
{
int csbits, scbits;
csbits = s->cscipher_tobe->keylen;
scbits = s->sccipher_tobe->keylen;
s->nbits = (csbits > scbits ? csbits : scbits);
}
/* The keys only have 160-bit entropy, since they're based on
* a SHA-1 hash. So cap the key size at 160 bits. */
if (s->nbits > 160)
s->nbits = 160;
/*
* If we're doing Diffie-Hellman group exchange, start by
* requesting a group.
*/
if (ssh->kex == &ssh_diffiehellman_gex) {
logevent("Doing Diffie-Hellman group exchange");
ssh->pkt_ctx |= SSH2_PKTCTX_DHGEX;
/*
* Work out how big a DH group we will need to allow that
* much data.
*/
s->pbits = 512 << ((s->nbits - 1) / 64);
ssh2_pkt_init(ssh, SSH2_MSG_KEX_DH_GEX_REQUEST);
ssh2_pkt_adduint32(ssh, s->pbits);
ssh2_pkt_send(ssh);
crWaitUntil(ispkt);
if (ssh->pktin.type != SSH2_MSG_KEX_DH_GEX_GROUP) {
bombout((ssh,"expected key exchange group packet from server"));
crReturn(0);
}
s->p = ssh2_pkt_getmp(ssh);
s->g = ssh2_pkt_getmp(ssh);
ssh->kex_ctx = dh_setup_group(s->p, s->g);
s->kex_init_value = SSH2_MSG_KEX_DH_GEX_INIT;
s->kex_reply_value = SSH2_MSG_KEX_DH_GEX_REPLY;
} else {
ssh->pkt_ctx |= SSH2_PKTCTX_DHGROUP1;
ssh->kex_ctx = dh_setup_group1();
s->kex_init_value = SSH2_MSG_KEXDH_INIT;
s->kex_reply_value = SSH2_MSG_KEXDH_REPLY;
}
logevent("Doing Diffie-Hellman key exchange");
/*
* Now generate and send e for Diffie-Hellman.
*/
s->e = dh_create_e(ssh->kex_ctx, s->nbits * 2);
ssh2_pkt_init(ssh, s->kex_init_value);
ssh2_pkt_addmp(ssh, s->e);
ssh2_pkt_send(ssh);
crWaitUntil(ispkt);
if (ssh->pktin.type != s->kex_reply_value) {
bombout((ssh,"expected key exchange reply packet from server"));
crReturn(0);
}
ssh2_pkt_getstring(ssh, &s->hostkeydata, &s->hostkeylen);
s->f = ssh2_pkt_getmp(ssh);
ssh2_pkt_getstring(ssh, &s->sigdata, &s->siglen);
s->K = dh_find_K(ssh->kex_ctx, s->f);
sha_string(&ssh->exhash, s->hostkeydata, s->hostkeylen);
if (ssh->kex == &ssh_diffiehellman_gex) {
sha_uint32(&ssh->exhash, s->pbits);
sha_mpint(&ssh->exhash, s->p);
sha_mpint(&ssh->exhash, s->g);
}
sha_mpint(&ssh->exhash, s->e);
sha_mpint(&ssh->exhash, s->f);
sha_mpint(&ssh->exhash, s->K);
SHA_Final(&ssh->exhash, s->exchange_hash);
dh_cleanup(ssh->kex_ctx);
#if 0
debug(("Exchange hash is:\n"));
dmemdump(s->exchange_hash, 20);
#endif
s->hkey = ssh->hostkey->newkey(s->hostkeydata, s->hostkeylen);
if (!s->hkey ||
!ssh->hostkey->verifysig(s->hkey, s->sigdata, s->siglen,
(char *)s->exchange_hash, 20)) {
bombout((ssh,"Server's host key did not match the signature supplied"));
crReturn(0);
}
/*
* Authenticate remote host: verify host key. (We've already
* checked the signature of the exchange hash.)
*/
s->keystr = ssh->hostkey->fmtkey(s->hkey);
s->fingerprint = ssh->hostkey->fingerprint(s->hkey);
verify_ssh_host_key(ssh->frontend,
ssh->savedhost, ssh->savedport, ssh->hostkey->keytype,
s->keystr, s->fingerprint);
if (s->first_kex) { /* don't bother logging this in rekeys */
logevent("Host key fingerprint is:");
logevent(s->fingerprint);
}
sfree(s->fingerprint);
sfree(s->keystr);
ssh->hostkey->freekey(s->hkey);
/*
* Send SSH2_MSG_NEWKEYS.
*/
ssh2_pkt_init(ssh, SSH2_MSG_NEWKEYS);
ssh2_pkt_send(ssh);
/*
* Expect SSH2_MSG_NEWKEYS from server.
*/
crWaitUntil(ispkt);
if (ssh->pktin.type != SSH2_MSG_NEWKEYS) {
bombout((ssh,"expected new-keys packet from server"));
crReturn(0);
}
/*
* Create and initialise session keys.
*/
if (ssh->cs_cipher_ctx)
ssh->cscipher->free_context(ssh->cs_cipher_ctx);
ssh->cscipher = s->cscipher_tobe;
ssh->cs_cipher_ctx = ssh->cscipher->make_context();
if (ssh->sc_cipher_ctx)
ssh->sccipher->free_context(ssh->sc_cipher_ctx);
ssh->sccipher = s->sccipher_tobe;
ssh->sc_cipher_ctx = ssh->sccipher->make_context();
if (ssh->cs_mac_ctx)
ssh->csmac->free_context(ssh->cs_mac_ctx);
ssh->csmac = s->csmac_tobe;
ssh->cs_mac_ctx = ssh->csmac->make_context();
if (ssh->sc_mac_ctx)
ssh->scmac->free_context(ssh->sc_mac_ctx);
ssh->scmac = s->scmac_tobe;
ssh->sc_mac_ctx = ssh->scmac->make_context();
if (ssh->cs_comp_ctx)
ssh->cscomp->compress_cleanup(ssh->cs_comp_ctx);
ssh->cscomp = s->cscomp_tobe;
ssh->cs_comp_ctx = ssh->cscomp->compress_init();
if (ssh->sc_comp_ctx)
ssh->sccomp->decompress_cleanup(ssh->sc_comp_ctx);
ssh->sccomp = s->sccomp_tobe;
ssh->sc_comp_ctx = ssh->sccomp->decompress_init();
/*
* Set IVs after keys. Here we use the exchange hash from the
* _first_ key exchange.
*/
{
unsigned char keyspace[40];
if (s->first_kex)
memcpy(ssh->v2_session_id, s->exchange_hash,
sizeof(s->exchange_hash));
ssh2_mkkey(ssh,s->K,s->exchange_hash,ssh->v2_session_id,'C',keyspace);
ssh->cscipher->setkey(ssh->cs_cipher_ctx, keyspace);
ssh2_mkkey(ssh,s->K,s->exchange_hash,ssh->v2_session_id,'D',keyspace);
ssh->sccipher->setkey(ssh->sc_cipher_ctx, keyspace);
ssh2_mkkey(ssh,s->K,s->exchange_hash,ssh->v2_session_id,'A',keyspace);
ssh->cscipher->setiv(ssh->cs_cipher_ctx, keyspace);
ssh2_mkkey(ssh,s->K,s->exchange_hash,ssh->v2_session_id,'B',keyspace);
ssh->sccipher->setiv(ssh->sc_cipher_ctx, keyspace);
ssh2_mkkey(ssh,s->K,s->exchange_hash,ssh->v2_session_id,'E',keyspace);
ssh->csmac->setkey(ssh->cs_mac_ctx, keyspace);
ssh2_mkkey(ssh,s->K,s->exchange_hash,ssh->v2_session_id,'F',keyspace);
ssh->scmac->setkey(ssh->sc_mac_ctx, keyspace);
}
logeventf(ssh, "Initialised %.200s client->server encryption",
ssh->cscipher->text_name);
logeventf(ssh, "Initialised %.200s server->client encryption",
ssh->sccipher->text_name);
if (ssh->cscomp->text_name)
logeventf(ssh, "Initialised %s compression",
ssh->cscomp->text_name);
if (ssh->sccomp->text_name)
logeventf(ssh, "Initialised %s decompression",
ssh->sccomp->text_name);
/*
* If this is the first key exchange phase, we must pass the
* SSH2_MSG_NEWKEYS packet to the next layer, not because it
* wants to see it but because it will need time to initialise
* itself before it sees an actual packet. In subsequent key
* exchange phases, we don't pass SSH2_MSG_NEWKEYS on, because
* it would only confuse the layer above.
*/
if (!s->first_kex) {
crReturn(0);
}
s->first_kex = 0;
/*
* Now we're encrypting. Begin returning 1 to the protocol main
* function so that other things can run on top of the
* transport. If we ever see a KEXINIT, we must go back to the
* start.
*/
while (!(ispkt && ssh->pktin.type == SSH2_MSG_KEXINIT)) {
crReturn(1);
}
logevent("Server initiated key re-exchange");
goto begin_key_exchange;
crFinish(1);
}
/*
* Add data to an SSH2 channel output buffer.
*/
static void ssh2_add_channel_data(struct ssh_channel *c, char *buf,
int len)
{
bufchain_add(&c->v.v2.outbuffer, buf, len);
}
/*
* Attempt to send data on an SSH2 channel.
*/
static int ssh2_try_send(struct ssh_channel *c)
{
Ssh ssh = c->ssh;
while (c->v.v2.remwindow > 0 && bufchain_size(&c->v.v2.outbuffer) > 0) {
int len;
void *data;
bufchain_prefix(&c->v.v2.outbuffer, &data, &len);
if ((unsigned)len > c->v.v2.remwindow)
len = c->v.v2.remwindow;
if ((unsigned)len > c->v.v2.remmaxpkt)
len = c->v.v2.remmaxpkt;
ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_DATA);
ssh2_pkt_adduint32(ssh, c->remoteid);
ssh2_pkt_addstring_start(ssh);
ssh2_pkt_addstring_data(ssh, data, len);
ssh2_pkt_send(ssh);
bufchain_consume(&c->v.v2.outbuffer, len);
c->v.v2.remwindow -= len;
}
/*
* After having sent as much data as we can, return the amount
* still buffered.
*/
return bufchain_size(&c->v.v2.outbuffer);
}
/*
* Potentially enlarge the window on an SSH2 channel.
*/
static void ssh2_set_window(struct ssh_channel *c, unsigned newwin)
{
Ssh ssh = c->ssh;
/*
* Never send WINDOW_ADJUST for a channel that the remote side
* already thinks it's closed; there's no point, since it won't
* be sending any more data anyway.
*/
if (c->closes != 0)
return;
if (newwin > c->v.v2.locwindow) {
ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_WINDOW_ADJUST);
ssh2_pkt_adduint32(ssh, c->remoteid);
ssh2_pkt_adduint32(ssh, newwin - c->v.v2.locwindow);
ssh2_pkt_send(ssh);
c->v.v2.locwindow = newwin;
}
}
/*
* Handle the SSH2 userauth and connection layers.
*/
static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
{
struct do_ssh2_authconn_state {
enum {
AUTH_INVALID, AUTH_PUBLICKEY_AGENT, AUTH_PUBLICKEY_FILE,
AUTH_PASSWORD,
AUTH_KEYBOARD_INTERACTIVE
} method;
enum {
AUTH_TYPE_NONE,
AUTH_TYPE_PUBLICKEY,
AUTH_TYPE_PUBLICKEY_OFFER_LOUD,
AUTH_TYPE_PUBLICKEY_OFFER_QUIET,
AUTH_TYPE_PASSWORD,
AUTH_TYPE_KEYBOARD_INTERACTIVE,
AUTH_TYPE_KEYBOARD_INTERACTIVE_QUIET
} type;
int gotit, need_pw, can_pubkey, can_passwd, can_keyb_inter;
int tried_pubkey_config, tried_agent, tried_keyb_inter;
int kbd_inter_running;
int we_are_in;
int num_prompts, curr_prompt, echo;
char username[100];
int got_username;
char pwprompt[200];
char password[100];
void *publickey_blob;
int publickey_bloblen;
unsigned char request[5], *response, *p;
int responselen;
int keyi, nkeys;
int authed;
char *pkblob, *alg, *commentp;
int pklen, alglen, commentlen;
int siglen, retlen, len;
char *q, *agentreq, *ret;
int try_send;
};
crState(do_ssh2_authconn_state);
crBegin(ssh->do_ssh2_authconn_crstate);
/*
* Request userauth protocol, and await a response to it.
*/
ssh2_pkt_init(ssh, SSH2_MSG_SERVICE_REQUEST);
ssh2_pkt_addstring(ssh, "ssh-userauth");
ssh2_pkt_send(ssh);
crWaitUntilV(ispkt);
if (ssh->pktin.type != SSH2_MSG_SERVICE_ACCEPT) {
bombout((ssh,"Server refused user authentication protocol"));
crReturnV;
}
/*
* We repeat this whole loop, including the username prompt,
* until we manage a successful authentication. If the user
* types the wrong _password_, they can be sent back to the
* beginning to try another username, if this is configured on.
* (If they specify a username in the config, they are never
* asked, even if they do give a wrong password.)
*
* I think this best serves the needs of
*
* - the people who have no configuration, no keys, and just
* want to try repeated (username,password) pairs until they
* type both correctly
*
* - people who have keys and configuration but occasionally
* need to fall back to passwords
*
* - people with a key held in Pageant, who might not have
* logged in to a particular machine before; so they want to
* type a username, and then _either_ their key will be
* accepted, _or_ they will type a password. If they mistype
* the username they will want to be able to get back and
* retype it!
*/
s->username[0] = '\0';
s->got_username = FALSE;
do {
/*
* Get a username.
*/
if (s->got_username && !cfg.change_username) {
/*
* We got a username last time round this loop, and
* with change_username turned off we don't try to get
* it again.
*/
} else if ((flags & FLAG_INTERACTIVE) && !*cfg.username) {
if (ssh_get_line && !ssh_getline_pw_only) {
if (!ssh_get_line("login as: ",
s->username, sizeof(s->username), FALSE)) {
/*
* get_line failed to get a username.
* Terminate.
*/
logevent("No username provided. Abandoning session.");
ssh->state = SSH_STATE_CLOSED;
crReturnV;
}
} else {
int ret; /* need not be saved across crReturn */
c_write_str(ssh, "login as: ");
ssh->send_ok = 1;
setup_userpass_input(ssh, s->username, sizeof(s->username), 1);
do {
crWaitUntilV(!ispkt);
ret = process_userpass_input(ssh, in, inlen);
} while (ret == 0);
if (ret < 0)
cleanup_exit(0);
c_write_str(ssh, "\r\n");
}
s->username[strcspn(s->username, "\n\r")] = '\0';
} else {
char *stuff;
strncpy(s->username, cfg.username, sizeof(s->username));
s->username[sizeof(s->username)-1] = '\0';
if ((flags & FLAG_VERBOSE) || (flags & FLAG_INTERACTIVE)) {
stuff = dupprintf("Using username \"%s\".\r\n", s->username);
c_write_str(ssh, stuff);
sfree(stuff);
}
}
s->got_username = TRUE;
/*
* Send an authentication request using method "none": (a)
* just in case it succeeds, and (b) so that we know what
* authentication methods we can usefully try next.
*/
ssh->pkt_ctx &= ~SSH2_PKTCTX_AUTH_MASK;
ssh2_pkt_init(ssh, SSH2_MSG_USERAUTH_REQUEST);
ssh2_pkt_addstring(ssh, s->username);
ssh2_pkt_addstring(ssh, "ssh-connection");/* service requested */
ssh2_pkt_addstring(ssh, "none"); /* method */
ssh2_pkt_send(ssh);
s->type = AUTH_TYPE_NONE;
s->gotit = FALSE;
s->we_are_in = FALSE;
s->tried_pubkey_config = FALSE;
s->tried_agent = FALSE;
s->tried_keyb_inter = FALSE;
s->kbd_inter_running = FALSE;
/* Load the pub half of cfg.keyfile so we notice if it's in Pageant */
if (*cfg.keyfile) {
int keytype;
logeventf(ssh, "Reading private key file \"%.150s\"", cfg.keyfile);
keytype = key_type(cfg.keyfile);
if (keytype == SSH_KEYTYPE_SSH2) {
s->publickey_blob =
ssh2_userkey_loadpub(cfg.keyfile, NULL,
&s->publickey_bloblen);
} else {
char *msgbuf;
logeventf(ssh, "Unable to use this key file (%s)",
key_type_to_str(keytype));
msgbuf = dupprintf("Unable to use key file \"%.150s\""
" (%s)\r\n", cfg.keyfile,
key_type_to_str(keytype));
c_write_str(ssh, msgbuf);
sfree(msgbuf);
s->publickey_blob = NULL;
}
} else
s->publickey_blob = NULL;
while (1) {
/*
* Wait for the result of the last authentication request.
*/
if (!s->gotit)
crWaitUntilV(ispkt);
while (ssh->pktin.type == SSH2_MSG_USERAUTH_BANNER) {
char *banner;
int size;
/*
* Don't show the banner if we're operating in
* non-verbose non-interactive mode. (It's probably
* a script, which means nobody will read the
* banner _anyway_, and moreover the printing of
* the banner will screw up processing on the
* output of (say) plink.)
*/
if (flags & (FLAG_VERBOSE | FLAG_INTERACTIVE)) {
ssh2_pkt_getstring(ssh, &banner, &size);
if (banner)
c_write_untrusted(ssh, banner, size);
}
crWaitUntilV(ispkt);
}
if (ssh->pktin.type == SSH2_MSG_USERAUTH_SUCCESS) {
logevent("Access granted");
s->we_are_in = TRUE;
break;
}
if (s->kbd_inter_running &&
ssh->pktin.type == SSH2_MSG_USERAUTH_INFO_REQUEST) {
/*
* This is either a further set-of-prompts packet
* in keyboard-interactive authentication, or it's
* the same one and we came back here with `gotit'
* set. In the former case, we must reset the
* curr_prompt variable.
*/
if (!s->gotit)
s->curr_prompt = 0;
} else if (ssh->pktin.type != SSH2_MSG_USERAUTH_FAILURE) {
bombout((ssh,"Strange packet received during authentication: type %d",
ssh->pktin.type));
crReturnV;
}
s->gotit = FALSE;
/*
* OK, we're now sitting on a USERAUTH_FAILURE message, so
* we can look at the string in it and know what we can
* helpfully try next.
*/
if (ssh->pktin.type == SSH2_MSG_USERAUTH_FAILURE) {
char *methods;
int methlen;
ssh2_pkt_getstring(ssh, &methods, &methlen);
s->kbd_inter_running = FALSE;
if (!ssh2_pkt_getbool(ssh)) {
/*
* We have received an unequivocal Access
* Denied. This can translate to a variety of
* messages:
*
* - if we'd just tried "none" authentication,
* it's not worth printing anything at all
*
* - if we'd just tried a public key _offer_,
* the message should be "Server refused our
* key" (or no message at all if the key
* came from Pageant)
*
* - if we'd just tried anything else, the
* message really should be "Access denied".
*
* Additionally, if we'd just tried password
* authentication, we should break out of this
* whole loop so as to go back to the username
* prompt.
*/
if (s->type == AUTH_TYPE_NONE) {
/* do nothing */
} else if (s->type == AUTH_TYPE_PUBLICKEY_OFFER_LOUD ||
s->type == AUTH_TYPE_PUBLICKEY_OFFER_QUIET) {
if (s->type == AUTH_TYPE_PUBLICKEY_OFFER_LOUD)
c_write_str(ssh, "Server refused our key\r\n");
logevent("Server refused public key");
} else if (s->type==AUTH_TYPE_KEYBOARD_INTERACTIVE_QUIET) {
/* server declined keyboard-interactive; ignore */
} else {
c_write_str(ssh, "Access denied\r\n");
logevent("Access denied");
if (s->type == AUTH_TYPE_PASSWORD) {
s->we_are_in = FALSE;
break;
}
}
} else {
c_write_str(ssh, "Further authentication required\r\n");
logevent("Further authentication required");
}
s->can_pubkey =
in_commasep_string("publickey", methods, methlen);
s->can_passwd =
in_commasep_string("password", methods, methlen);
s->can_keyb_inter = cfg.try_ki_auth &&
in_commasep_string("keyboard-interactive", methods, methlen);
}
s->method = 0;
ssh->pkt_ctx &= ~SSH2_PKTCTX_AUTH_MASK;
/*
* Most password/passphrase prompts will be
* non-echoing, so we set this to 0 by default.
* Exception is that some keyboard-interactive prompts
* can be echoing, in which case we'll set this to 1.
*/
s->echo = 0;
if (!s->method && s->can_pubkey &&
agent_exists() && !s->tried_agent) {
/*
* Attempt public-key authentication using Pageant.
*/
void *r;
s->authed = FALSE;
ssh->pkt_ctx &= ~SSH2_PKTCTX_AUTH_MASK;
ssh->pkt_ctx |= SSH2_PKTCTX_PUBLICKEY;
s->tried_agent = TRUE;
logevent("Pageant is running. Requesting keys.");
/* Request the keys held by the agent. */
PUT_32BIT(s->request, 1);
s->request[4] = SSH2_AGENTC_REQUEST_IDENTITIES;
agent_query(s->request, 5, &r, &s->responselen);
s->response = (unsigned char *) r;
if (s->response && s->responselen >= 5 &&
s->response[4] == SSH2_AGENT_IDENTITIES_ANSWER) {
s->p = s->response + 5;
s->nkeys = GET_32BIT(s->p);
s->p += 4;
{
char buf[64];
sprintf(buf, "Pageant has %d SSH2 keys", s->nkeys);
logevent(buf);
}
for (s->keyi = 0; s->keyi < s->nkeys; s->keyi++) {
void *vret;
{
char buf[64];
sprintf(buf, "Trying Pageant key #%d", s->keyi);
logevent(buf);
}
s->pklen = GET_32BIT(s->p);
s->p += 4;
if (s->publickey_blob &&
s->pklen == s->publickey_bloblen &&
!memcmp(s->p, s->publickey_blob,
s->publickey_bloblen)) {
logevent("This key matches configured key file");
s->tried_pubkey_config = 1;
}
s->pkblob = (char *)s->p;
s->p += s->pklen;
s->alglen = GET_32BIT(s->pkblob);
s->alg = s->pkblob + 4;
s->commentlen = GET_32BIT(s->p);
s->p += 4;
s->commentp = (char *)s->p;
s->p += s->commentlen;
ssh2_pkt_init(ssh, SSH2_MSG_USERAUTH_REQUEST);
ssh2_pkt_addstring(ssh, s->username);
ssh2_pkt_addstring(ssh, "ssh-connection"); /* service requested */
ssh2_pkt_addstring(ssh, "publickey"); /* method */
ssh2_pkt_addbool(ssh, FALSE); /* no signature included */
ssh2_pkt_addstring_start(ssh);
ssh2_pkt_addstring_data(ssh, s->alg, s->alglen);
ssh2_pkt_addstring_start(ssh);
ssh2_pkt_addstring_data(ssh, s->pkblob, s->pklen);
ssh2_pkt_send(ssh);
crWaitUntilV(ispkt);
if (ssh->pktin.type != SSH2_MSG_USERAUTH_PK_OK) {
logevent("Key refused");
continue;
}
if (flags & FLAG_VERBOSE) {
c_write_str(ssh, "Authenticating with "
"public key \"");
c_write(ssh, s->commentp, s->commentlen);
c_write_str(ssh, "\" from agent\r\n");
}
/*
* Server is willing to accept the key.
* Construct a SIGN_REQUEST.
*/
ssh2_pkt_init(ssh, SSH2_MSG_USERAUTH_REQUEST);
ssh2_pkt_addstring(ssh, s->username);
ssh2_pkt_addstring(ssh, "ssh-connection"); /* service requested */
ssh2_pkt_addstring(ssh, "publickey"); /* method */
ssh2_pkt_addbool(ssh, TRUE);
ssh2_pkt_addstring_start(ssh);
ssh2_pkt_addstring_data(ssh, s->alg, s->alglen);
ssh2_pkt_addstring_start(ssh);
ssh2_pkt_addstring_data(ssh, s->pkblob, s->pklen);
s->siglen = ssh->pktout.length - 5 + 4 + 20;
s->len = 1; /* message type */
s->len += 4 + s->pklen; /* key blob */
s->len += 4 + s->siglen; /* data to sign */
s->len += 4; /* flags */
s->agentreq = smalloc(4 + s->len);
PUT_32BIT(s->agentreq, s->len);
s->q = s->agentreq + 4;
*s->q++ = SSH2_AGENTC_SIGN_REQUEST;
PUT_32BIT(s->q, s->pklen);
s->q += 4;
memcpy(s->q, s->pkblob, s->pklen);
s->q += s->pklen;
PUT_32BIT(s->q, s->siglen);
s->q += 4;
/* Now the data to be signed... */
PUT_32BIT(s->q, 20);
s->q += 4;
memcpy(s->q, ssh->v2_session_id, 20);
s->q += 20;
memcpy(s->q, ssh->pktout.data + 5,
ssh->pktout.length - 5);
s->q += ssh->pktout.length - 5;
/* And finally the (zero) flags word. */
PUT_32BIT(s->q, 0);
agent_query(s->agentreq, s->len + 4, &vret, &s->retlen);
s->ret = vret;
sfree(s->agentreq);
if (s->ret) {
if (s->ret[4] == SSH2_AGENT_SIGN_RESPONSE) {
logevent("Sending Pageant's response");
ssh2_add_sigblob(ssh, s->pkblob, s->pklen,
s->ret + 9,
GET_32BIT(s->ret + 5));
ssh2_pkt_send(ssh);
s->authed = TRUE;
break;
} else {
logevent
("Pageant failed to answer challenge");
sfree(s->ret);
}
}
}
if (s->authed)
continue;
}
}
if (!s->method && s->can_pubkey && s->publickey_blob
&& !s->tried_pubkey_config) {
unsigned char *pub_blob;
char *algorithm, *comment;
int pub_blob_len;
s->tried_pubkey_config = TRUE;
ssh->pkt_ctx &= ~SSH2_PKTCTX_AUTH_MASK;
ssh->pkt_ctx |= SSH2_PKTCTX_PUBLICKEY;
/*
* Try the public key supplied in the configuration.
*
* First, offer the public blob to see if the server is
* willing to accept it.
*/
pub_blob =
(unsigned char *)ssh2_userkey_loadpub(cfg.keyfile,
&algorithm,
&pub_blob_len);
if (pub_blob) {
ssh2_pkt_init(ssh, SSH2_MSG_USERAUTH_REQUEST);
ssh2_pkt_addstring(ssh, s->username);
ssh2_pkt_addstring(ssh, "ssh-connection"); /* service requested */
ssh2_pkt_addstring(ssh, "publickey"); /* method */
ssh2_pkt_addbool(ssh, FALSE); /* no signature included */
ssh2_pkt_addstring(ssh, algorithm);
ssh2_pkt_addstring_start(ssh);
ssh2_pkt_addstring_data(ssh, (char *)pub_blob,
pub_blob_len);
ssh2_pkt_send(ssh);
logevent("Offered public key"); /* FIXME */
crWaitUntilV(ispkt);
if (ssh->pktin.type != SSH2_MSG_USERAUTH_PK_OK) {
s->gotit = TRUE;
s->type = AUTH_TYPE_PUBLICKEY_OFFER_LOUD;
continue; /* key refused; give up on it */
}
logevent("Offer of public key accepted");
/*
* Actually attempt a serious authentication using
* the key.
*/
if (ssh2_userkey_encrypted(cfg.keyfile, &comment)) {
sprintf(s->pwprompt,
"Passphrase for key \"%.100s\": ",
comment);
s->need_pw = TRUE;
} else {
s->need_pw = FALSE;
}
c_write_str(ssh, "Authenticating with public key \"");
c_write_str(ssh, comment);
c_write_str(ssh, "\"\r\n");
s->method = AUTH_PUBLICKEY_FILE;
}
}
if (!s->method && s->can_keyb_inter && !s->tried_keyb_inter) {
s->method = AUTH_KEYBOARD_INTERACTIVE;
s->type = AUTH_TYPE_KEYBOARD_INTERACTIVE;
s->tried_keyb_inter = TRUE;
ssh->pkt_ctx &= ~SSH2_PKTCTX_AUTH_MASK;
ssh->pkt_ctx |= SSH2_PKTCTX_KBDINTER;
ssh2_pkt_init(ssh, SSH2_MSG_USERAUTH_REQUEST);
ssh2_pkt_addstring(ssh, s->username);
ssh2_pkt_addstring(ssh, "ssh-connection"); /* service requested */
ssh2_pkt_addstring(ssh, "keyboard-interactive"); /* method */
ssh2_pkt_addstring(ssh, ""); /* lang */
ssh2_pkt_addstring(ssh, "");
ssh2_pkt_send(ssh);
crWaitUntilV(ispkt);
if (ssh->pktin.type != SSH2_MSG_USERAUTH_INFO_REQUEST) {
if (ssh->pktin.type == SSH2_MSG_USERAUTH_FAILURE)
s->gotit = TRUE;
logevent("Keyboard-interactive authentication refused");
s->type = AUTH_TYPE_KEYBOARD_INTERACTIVE_QUIET;
continue;
}
s->kbd_inter_running = TRUE;
s->curr_prompt = 0;
}
if (s->kbd_inter_running) {
s->method = AUTH_KEYBOARD_INTERACTIVE;
s->type = AUTH_TYPE_KEYBOARD_INTERACTIVE;
s->tried_keyb_inter = TRUE;
ssh->pkt_ctx &= ~SSH2_PKTCTX_AUTH_MASK;
ssh->pkt_ctx |= SSH2_PKTCTX_KBDINTER;
if (s->curr_prompt == 0) {
/*
* We've got a fresh USERAUTH_INFO_REQUEST.
* Display header data, and start going through
* the prompts.
*/
char *name, *inst, *lang;
int name_len, inst_len, lang_len;
ssh2_pkt_getstring(ssh, &name, &name_len);
ssh2_pkt_getstring(ssh, &inst, &inst_len);
ssh2_pkt_getstring(ssh, &lang, &lang_len);
if (name_len > 0) {
c_write_untrusted(ssh, name, name_len);
c_write_str(ssh, "\r\n");
}
if (inst_len > 0) {
c_write_untrusted(ssh, inst, inst_len);
c_write_str(ssh, "\r\n");
}
s->num_prompts = ssh2_pkt_getuint32(ssh);
}
/*
* If there are prompts remaining in the packet,
* display one and get a response.
*/
if (s->curr_prompt < s->num_prompts) {
char *prompt;
int prompt_len;
ssh2_pkt_getstring(ssh, &prompt, &prompt_len);
if (prompt_len > 0) {
strncpy(s->pwprompt, prompt, sizeof(s->pwprompt));
s->pwprompt[prompt_len < sizeof(s->pwprompt) ?
prompt_len : sizeof(s->pwprompt)-1] = '\0';
} else {
strcpy(s->pwprompt,
"<server failed to send prompt>: ");
}
s->echo = ssh2_pkt_getbool(ssh);
s->need_pw = TRUE;
} else
s->need_pw = FALSE;
}
if (!s->method && s->can_passwd) {
s->method = AUTH_PASSWORD;
ssh->pkt_ctx &= ~SSH2_PKTCTX_AUTH_MASK;
ssh->pkt_ctx |= SSH2_PKTCTX_PASSWORD;
sprintf(s->pwprompt, "%.90s@%.90s's password: ", s->username,
ssh->savedhost);
s->need_pw = TRUE;
}
if (s->need_pw) {
if (ssh_get_line) {
if (!ssh_get_line(s->pwprompt, s->password,
sizeof(s->password), TRUE)) {
/*
* get_line failed to get a password (for
* example because one was supplied on the
* command line which has already failed to
* work). Terminate.
*/
ssh2_pkt_init(ssh, SSH2_MSG_DISCONNECT);
ssh2_pkt_adduint32(ssh,SSH2_DISCONNECT_BY_APPLICATION);
ssh2_pkt_addstring(ssh, "No more passwords available"
" to try");
ssh2_pkt_addstring(ssh, "en"); /* language tag */
ssh2_pkt_send(ssh);
logevent("Unable to authenticate");
connection_fatal(ssh->frontend,
"Unable to authenticate");
ssh->state = SSH_STATE_CLOSED;
crReturnV;
}
} else {
int ret; /* need not be saved across crReturn */
c_write_untrusted(ssh, s->pwprompt, strlen(s->pwprompt));
ssh->send_ok = 1;
setup_userpass_input(ssh, s->password,
sizeof(s->password), s->echo);
do {
crWaitUntilV(!ispkt);
ret = process_userpass_input(ssh, in, inlen);
} while (ret == 0);
if (ret < 0)
cleanup_exit(0);
c_write_str(ssh, "\r\n");
}
}
if (s->method == AUTH_PUBLICKEY_FILE) {
/*
* We have our passphrase. Now try the actual authentication.
*/
struct ssh2_userkey *key;
key = ssh2_load_userkey(cfg.keyfile, s->password);
if (key == SSH2_WRONG_PASSPHRASE || key == NULL) {
if (key == SSH2_WRONG_PASSPHRASE) {
c_write_str(ssh, "Wrong passphrase\r\n");
s->tried_pubkey_config = FALSE;
} else {
c_write_str(ssh, "Unable to load private key\r\n");
s->tried_pubkey_config = TRUE;
}
/* Send a spurious AUTH_NONE to return to the top. */
ssh2_pkt_init(ssh, SSH2_MSG_USERAUTH_REQUEST);
ssh2_pkt_addstring(ssh, s->username);
ssh2_pkt_addstring(ssh, "ssh-connection"); /* service requested */
ssh2_pkt_addstring(ssh, "none"); /* method */
ssh2_pkt_send(ssh);
s->type = AUTH_TYPE_NONE;
} else {
unsigned char *pkblob, *sigblob, *sigdata;
int pkblob_len, sigblob_len, sigdata_len;
/*
* We have loaded the private key and the server
* has announced that it's willing to accept it.
* Hallelujah. Generate a signature and send it.
*/
ssh2_pkt_init(ssh, SSH2_MSG_USERAUTH_REQUEST);
ssh2_pkt_addstring(ssh, s->username);
ssh2_pkt_addstring(ssh, "ssh-connection"); /* service requested */
ssh2_pkt_addstring(ssh, "publickey"); /* method */
ssh2_pkt_addbool(ssh, TRUE);
ssh2_pkt_addstring(ssh, key->alg->name);
pkblob = key->alg->public_blob(key->data, &pkblob_len);
ssh2_pkt_addstring_start(ssh);
ssh2_pkt_addstring_data(ssh, (char *)pkblob, pkblob_len);
/*
* The data to be signed is:
*
* string session-id
*
* followed by everything so far placed in the
* outgoing packet.
*/
sigdata_len = ssh->pktout.length - 5 + 4 + 20;
sigdata = smalloc(sigdata_len);
PUT_32BIT(sigdata, 20);
memcpy(sigdata + 4, ssh->v2_session_id, 20);
memcpy(sigdata + 24, ssh->pktout.data + 5,
ssh->pktout.length - 5);
sigblob = key->alg->sign(key->data, (char *)sigdata,
sigdata_len, &sigblob_len);
ssh2_add_sigblob(ssh, pkblob, pkblob_len,
sigblob, sigblob_len);
sfree(pkblob);
sfree(sigblob);
sfree(sigdata);
ssh2_pkt_send(ssh);
s->type = AUTH_TYPE_PUBLICKEY;
}
} else if (s->method == AUTH_PASSWORD) {
/*
* We send the password packet lumped tightly together with
* an SSH_MSG_IGNORE packet. The IGNORE packet contains a
* string long enough to make the total length of the two
* packets constant. This should ensure that a passive
* listener doing traffic analyis can't work out the length
* of the password.
*
* For this to work, we need an assumption about the
* maximum length of the password packet. I think 256 is
* pretty conservative. Anyone using a password longer than
* that probably doesn't have much to worry about from
* people who find out how long their password is!
*/
ssh2_pkt_init(ssh, SSH2_MSG_USERAUTH_REQUEST);
ssh2_pkt_addstring(ssh, s->username);
ssh2_pkt_addstring(ssh, "ssh-connection"); /* service requested */
ssh2_pkt_addstring(ssh, "password");
ssh2_pkt_addbool(ssh, FALSE);
ssh2_pkt_addstring(ssh, s->password);
memset(s->password, 0, sizeof(s->password));
ssh2_pkt_defer(ssh);
/*
* We'll include a string that's an exact multiple of the
* cipher block size. If the cipher is NULL for some
* reason, we don't do this trick at all because we gain
* nothing by it.
*/
if (ssh->cscipher) {
int stringlen, i;
stringlen = (256 - ssh->deferred_len);
stringlen += ssh->cscipher->blksize - 1;
stringlen -= (stringlen % ssh->cscipher->blksize);
if (ssh->cscomp) {
/*
* Temporarily disable actual compression,
* so we can guarantee to get this string
* exactly the length we want it. The
* compression-disabling routine should
* return an integer indicating how many
* bytes we should adjust our string length
* by.
*/
stringlen -=
ssh->cscomp->disable_compression(ssh->cs_comp_ctx);
}
ssh2_pkt_init(ssh, SSH2_MSG_IGNORE);
ssh2_pkt_addstring_start(ssh);
for (i = 0; i < stringlen; i++) {
char c = (char) random_byte();
ssh2_pkt_addstring_data(ssh, &c, 1);
}
ssh2_pkt_defer(ssh);
}
ssh_pkt_defersend(ssh);
logevent("Sent password");
s->type = AUTH_TYPE_PASSWORD;
} else if (s->method == AUTH_KEYBOARD_INTERACTIVE) {
if (s->curr_prompt == 0) {
ssh2_pkt_init(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE);
ssh2_pkt_adduint32(ssh, s->num_prompts);
}
if (s->need_pw) { /* only add pw if we just got one! */
ssh2_pkt_addstring(ssh, s->password);
memset(s->password, 0, sizeof(s->password));
s->curr_prompt++;
}
if (s->curr_prompt >= s->num_prompts) {
ssh2_pkt_send(ssh);
} else {
/*
* If there are prompts remaining, we set
* `gotit' so that we won't attempt to get
* another packet. Then we go back round the
* loop and will end up retrieving another
* prompt out of the existing packet. Funky or
* what?
*/
s->gotit = TRUE;
}
s->type = AUTH_TYPE_KEYBOARD_INTERACTIVE;
} else {
c_write_str(ssh, "No supported authentication methods"
" left to try!\r\n");
logevent("No supported authentications offered."
" Disconnecting");
ssh2_pkt_init(ssh, SSH2_MSG_DISCONNECT);
ssh2_pkt_adduint32(ssh, SSH2_DISCONNECT_BY_APPLICATION);
ssh2_pkt_addstring(ssh, "No supported authentication"
" methods available");
ssh2_pkt_addstring(ssh, "en"); /* language tag */
ssh2_pkt_send(ssh);
ssh->state = SSH_STATE_CLOSED;
crReturnV;
}
}
} while (!s->we_are_in);
/*
* Now we're authenticated for the connection protocol. The
* connection protocol will automatically have started at this
* point; there's no need to send SERVICE_REQUEST.
*/
/*
* So now create a channel with a session in it.
*/
ssh->channels = newtree234(ssh_channelcmp);
ssh->mainchan = smalloc(sizeof(struct ssh_channel));
ssh->mainchan->ssh = ssh;
ssh->mainchan->localid = alloc_channel_id(ssh);
ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_OPEN);
ssh2_pkt_addstring(ssh, "session");
ssh2_pkt_adduint32(ssh, ssh->mainchan->localid);
ssh->mainchan->v.v2.locwindow = OUR_V2_WINSIZE;
ssh2_pkt_adduint32(ssh, ssh->mainchan->v.v2.locwindow);/* our window size */
ssh2_pkt_adduint32(ssh, 0x4000UL); /* our max pkt size */
ssh2_pkt_send(ssh);
crWaitUntilV(ispkt);
if (ssh->pktin.type != SSH2_MSG_CHANNEL_OPEN_CONFIRMATION) {
bombout((ssh,"Server refused to open a session"));
crReturnV;
/* FIXME: error data comes back in FAILURE packet */
}
if (ssh2_pkt_getuint32(ssh) != ssh->mainchan->localid) {
bombout((ssh,"Server's channel confirmation cited wrong channel"));
crReturnV;
}
ssh->mainchan->remoteid = ssh2_pkt_getuint32(ssh);
ssh->mainchan->type = CHAN_MAINSESSION;
ssh->mainchan->closes = 0;
ssh->mainchan->v.v2.remwindow = ssh2_pkt_getuint32(ssh);
ssh->mainchan->v.v2.remmaxpkt = ssh2_pkt_getuint32(ssh);
bufchain_init(&ssh->mainchan->v.v2.outbuffer);
add234(ssh->channels, ssh->mainchan);
logevent("Opened channel for session");
/*
* Potentially enable X11 forwarding.
*/
if (cfg.x11_forward) {
char proto[20], data[64];
logevent("Requesting X11 forwarding");
ssh->x11auth = x11_invent_auth(proto, sizeof(proto),
data, sizeof(data));
x11_get_real_auth(ssh->x11auth, cfg.x11_display);
ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_REQUEST);
ssh2_pkt_adduint32(ssh, ssh->mainchan->remoteid);
ssh2_pkt_addstring(ssh, "x11-req");
ssh2_pkt_addbool(ssh, 1); /* want reply */
ssh2_pkt_addbool(ssh, 0); /* many connections */
ssh2_pkt_addstring(ssh, proto);
ssh2_pkt_addstring(ssh, data);
ssh2_pkt_adduint32(ssh, x11_get_screen_number(cfg.x11_display));
ssh2_pkt_send(ssh);
do {
crWaitUntilV(ispkt);
if (ssh->pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST) {
unsigned i = ssh2_pkt_getuint32(ssh);
struct ssh_channel *c;
c = find234(ssh->channels, &i, ssh_channelfind);
if (!c)
continue; /* nonexistent channel */
c->v.v2.remwindow += ssh2_pkt_getuint32(ssh);
}
} while (ssh->pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST);
if (ssh->pktin.type != SSH2_MSG_CHANNEL_SUCCESS) {
if (ssh->pktin.type != SSH2_MSG_CHANNEL_FAILURE) {
bombout((ssh,"Unexpected response to X11 forwarding request:"
" packet type %d", ssh->pktin.type));
crReturnV;
}
logevent("X11 forwarding refused");
} else {
logevent("X11 forwarding enabled");
ssh->X11_fwd_enabled = TRUE;
}
}
/*
* Enable port forwardings.
*/
{
char type;
int n;
int sport,dport,sserv,dserv;
char sports[256], dports[256], saddr[256], host[256];
ssh->rportfwds = newtree234(ssh_rportcmp_ssh2);
/* Add port forwardings. */
ssh->portfwd_strptr = cfg.portfwd;
while (*ssh->portfwd_strptr) {
type = *ssh->portfwd_strptr++;
saddr[0] = '\0';
n = 0;
while (*ssh->portfwd_strptr && *ssh->portfwd_strptr != '\t') {
if (*ssh->portfwd_strptr == ':') {
/*
* We've seen a colon in the middle of the
* source port number. This means that
* everything we've seen until now is the
* source _address_, so we'll move it into
* saddr and start sports from the beginning
* again.
*/
ssh->portfwd_strptr++;
sports[n] = '\0';
strcpy(saddr, sports);
n = 0;
}
if (n < 255) sports[n++] = *ssh->portfwd_strptr++;
}
sports[n] = 0;
if (*ssh->portfwd_strptr == '\t')
ssh->portfwd_strptr++;
n = 0;
while (*ssh->portfwd_strptr && *ssh->portfwd_strptr != ':') {
if (n < 255) host[n++] = *ssh->portfwd_strptr++;
}
host[n] = 0;
if (*ssh->portfwd_strptr == ':')
ssh->portfwd_strptr++;
n = 0;
while (*ssh->portfwd_strptr) {
if (n < 255) dports[n++] = *ssh->portfwd_strptr++;
}
dports[n] = 0;
ssh->portfwd_strptr++;
dport = atoi(dports);
dserv = 0;
if (dport == 0) {
dserv = 1;
dport = net_service_lookup(dports);
if (!dport) {
logeventf(ssh, "Service lookup failed for destination"
" port \"%s\"", dports);
}
}
sport = atoi(sports);
sserv = 0;
if (sport == 0) {
sserv = 1;
sport = net_service_lookup(sports);
if (!sport) {
logeventf(ssh, "Service lookup failed for source"
" port \"%s\"", sports);
}
}
if (sport && dport) {
if (type == 'L') {
pfd_addforward(host, dport, *saddr ? saddr : NULL,
sport, ssh);
logeventf(ssh, "Local port %.*s%.*s%.*s%.*s%d%.*s"
" forwarding to %s:%.*s%.*s%d%.*s",
(int)(*saddr?strlen(saddr):0), *saddr?saddr:NULL,
(int)(*saddr?1:0), ":",
(int)(sserv ? strlen(sports) : 0), sports,
sserv, "(", sport, sserv, ")",
host,
(int)(dserv ? strlen(dports) : 0), dports,
dserv, "(", dport, dserv, ")");
} else {
struct ssh_rportfwd *pf;
pf = smalloc(sizeof(*pf));
strcpy(pf->dhost, host);
pf->dport = dport;
pf->sport = sport;
if (add234(ssh->rportfwds, pf) != pf) {
logeventf(ssh, "Duplicate remote port forwarding"
" to %s:%d", host, dport);
sfree(pf);
} else {
logeventf(ssh, "Requesting remote port "
"%.*s%.*s%.*s%.*s%d%.*s"
" forward to %s:%.*s%.*s%d%.*s",
(int)(*saddr?strlen(saddr):0),
*saddr?saddr:NULL,
(int)(*saddr?1:0), ":",
(int)(sserv ? strlen(sports) : 0), sports,
sserv, "(", sport, sserv, ")",
host,
(int)(dserv ? strlen(dports) : 0), dports,
dserv, "(", dport, dserv, ")");
ssh2_pkt_init(ssh, SSH2_MSG_GLOBAL_REQUEST);
ssh2_pkt_addstring(ssh, "tcpip-forward");
ssh2_pkt_addbool(ssh, 1);/* want reply */
if (*saddr)
ssh2_pkt_addstring(ssh, saddr);
if (cfg.rport_acceptall)
ssh2_pkt_addstring(ssh, "0.0.0.0");
else
ssh2_pkt_addstring(ssh, "127.0.0.1");
ssh2_pkt_adduint32(ssh, sport);
ssh2_pkt_send(ssh);
do {
crWaitUntilV(ispkt);
if (ssh->pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST) {
unsigned i = ssh2_pkt_getuint32(ssh);
struct ssh_channel *c;
c = find234(ssh->channels, &i, ssh_channelfind);
if (!c)
continue;/* nonexistent channel */
c->v.v2.remwindow += ssh2_pkt_getuint32(ssh);
}
} while (ssh->pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST);
if (ssh->pktin.type != SSH2_MSG_REQUEST_SUCCESS) {
if (ssh->pktin.type != SSH2_MSG_REQUEST_FAILURE) {
bombout((ssh,"Unexpected response to port "
"forwarding request: packet type %d",
ssh->pktin.type));
crReturnV;
}
logevent("Server refused this port forwarding");
} else {
logevent("Remote port forwarding enabled");
}
}
}
}
}
}
/*
* Potentially enable agent forwarding.
*/
if (cfg.agentfwd && agent_exists()) {
logevent("Requesting OpenSSH-style agent forwarding");
ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_REQUEST);
ssh2_pkt_adduint32(ssh, ssh->mainchan->remoteid);
ssh2_pkt_addstring(ssh, "auth-agent-req@openssh.com");
ssh2_pkt_addbool(ssh, 1); /* want reply */
ssh2_pkt_send(ssh);
do {
crWaitUntilV(ispkt);
if (ssh->pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST) {
unsigned i = ssh2_pkt_getuint32(ssh);
struct ssh_channel *c;
c = find234(ssh->channels, &i, ssh_channelfind);
if (!c)
continue; /* nonexistent channel */
c->v.v2.remwindow += ssh2_pkt_getuint32(ssh);
}
} while (ssh->pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST);
if (ssh->pktin.type != SSH2_MSG_CHANNEL_SUCCESS) {
if (ssh->pktin.type != SSH2_MSG_CHANNEL_FAILURE) {
bombout((ssh,"Unexpected response to agent forwarding request:"
" packet type %d", ssh->pktin.type));
crReturnV;
}
logevent("Agent forwarding refused");
} else {
logevent("Agent forwarding enabled");
ssh->agentfwd_enabled = TRUE;
}
}
/*
* Now allocate a pty for the session.
*/
if (!cfg.nopty) {
ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_REQUEST);
ssh2_pkt_adduint32(ssh, ssh->mainchan->remoteid); /* recipient channel */
ssh2_pkt_addstring(ssh, "pty-req");
ssh2_pkt_addbool(ssh, 1); /* want reply */
ssh2_pkt_addstring(ssh, cfg.termtype);
ssh2_pkt_adduint32(ssh, ssh->term_width);
ssh2_pkt_adduint32(ssh, ssh->term_height);
ssh2_pkt_adduint32(ssh, 0); /* pixel width */
ssh2_pkt_adduint32(ssh, 0); /* pixel height */
ssh2_pkt_addstring_start(ssh);
ssh2_pkt_addstring_data(ssh, "\0", 1); /* TTY_OP_END, no special options */
ssh2_pkt_send(ssh);
ssh->state = SSH_STATE_INTERMED;
do {
crWaitUntilV(ispkt);
if (ssh->pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST) {
unsigned i = ssh2_pkt_getuint32(ssh);
struct ssh_channel *c;
c = find234(ssh->channels, &i, ssh_channelfind);
if (!c)
continue; /* nonexistent channel */
c->v.v2.remwindow += ssh2_pkt_getuint32(ssh);
}
} while (ssh->pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST);
if (ssh->pktin.type != SSH2_MSG_CHANNEL_SUCCESS) {
if (ssh->pktin.type != SSH2_MSG_CHANNEL_FAILURE) {
bombout((ssh,"Unexpected response to pty request:"
" packet type %d", ssh->pktin.type));
crReturnV;
}
c_write_str(ssh, "Server refused to allocate pty\r\n");
ssh->editing = ssh->echoing = 1;
} else {
logevent("Allocated pty");
}
} else {
ssh->editing = ssh->echoing = 1;
}
/*
* Start a shell or a remote command. We may have to attempt
* this twice if the config data has provided a second choice
* of command.
*/
while (1) {
int subsys;
char *cmd;
if (ssh->fallback_cmd) {
subsys = cfg.ssh_subsys2;
cmd = cfg.remote_cmd_ptr2;
} else {
subsys = cfg.ssh_subsys;
cmd = cfg.remote_cmd_ptr;
}
ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_REQUEST);
ssh2_pkt_adduint32(ssh, ssh->mainchan->remoteid); /* recipient channel */
if (subsys) {
ssh2_pkt_addstring(ssh, "subsystem");
ssh2_pkt_addbool(ssh, 1); /* want reply */
ssh2_pkt_addstring(ssh, cmd);
} else if (*cmd) {
ssh2_pkt_addstring(ssh, "exec");
ssh2_pkt_addbool(ssh, 1); /* want reply */
ssh2_pkt_addstring(ssh, cmd);
} else {
ssh2_pkt_addstring(ssh, "shell");
ssh2_pkt_addbool(ssh, 1); /* want reply */
}
ssh2_pkt_send(ssh);
do {
crWaitUntilV(ispkt);
if (ssh->pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST) {
unsigned i = ssh2_pkt_getuint32(ssh);
struct ssh_channel *c;
c = find234(ssh->channels, &i, ssh_channelfind);
if (!c)
continue; /* nonexistent channel */
c->v.v2.remwindow += ssh2_pkt_getuint32(ssh);
}
} while (ssh->pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST);
if (ssh->pktin.type != SSH2_MSG_CHANNEL_SUCCESS) {
if (ssh->pktin.type != SSH2_MSG_CHANNEL_FAILURE) {
bombout((ssh,"Unexpected response to shell/command request:"
" packet type %d", ssh->pktin.type));
crReturnV;
}
/*
* We failed to start the command. If this is the
* fallback command, we really are finished; if it's
* not, and if the fallback command exists, try falling
* back to it before complaining.
*/
if (!ssh->fallback_cmd && cfg.remote_cmd_ptr2 != NULL) {
logevent("Primary command failed; attempting fallback");
ssh->fallback_cmd = TRUE;
continue;
}
bombout((ssh,"Server refused to start a shell/command"));
crReturnV;
} else {
logevent("Started a shell/command");
}
break;
}
ssh->state = SSH_STATE_SESSION;
if (ssh->size_needed)
ssh_size(ssh, ssh->term_width, ssh->term_height);
if (ssh->eof_needed)
ssh_special(ssh, TS_EOF);
/*
* Transfer data!
*/
if (ssh->ldisc)
ldisc_send(ssh->ldisc, NULL, 0, 0);/* cause ldisc to notice changes */
ssh->send_ok = 1;
while (1) {
crReturnV;
s->try_send = FALSE;
if (ispkt) {
if (ssh->pktin.type == SSH2_MSG_CHANNEL_DATA ||
ssh->pktin.type == SSH2_MSG_CHANNEL_EXTENDED_DATA) {
char *data;
int length;
unsigned i = ssh2_pkt_getuint32(ssh);
struct ssh_channel *c;
c = find234(ssh->channels, &i, ssh_channelfind);
if (!c)
continue; /* nonexistent channel */
if (ssh->pktin.type == SSH2_MSG_CHANNEL_EXTENDED_DATA &&
ssh2_pkt_getuint32(ssh) != SSH2_EXTENDED_DATA_STDERR)
continue; /* extended but not stderr */
ssh2_pkt_getstring(ssh, &data, &length);
if (data) {
int bufsize;
c->v.v2.locwindow -= length;
switch (c->type) {
case CHAN_MAINSESSION:
bufsize =
from_backend(ssh->frontend, ssh->pktin.type ==
SSH2_MSG_CHANNEL_EXTENDED_DATA,
data, length);
break;
case CHAN_X11:
bufsize = x11_send(c->u.x11.s, data, length);
break;
case CHAN_SOCKDATA:
bufsize = pfd_send(c->u.pfd.s, data, length);
break;
case CHAN_AGENT:
while (length > 0) {
if (c->u.a.lensofar < 4) {
int l = min(4 - c->u.a.lensofar, length);
memcpy(c->u.a.msglen + c->u.a.lensofar,
data, l);
data += l;
length -= l;
c->u.a.lensofar += l;
}
if (c->u.a.lensofar == 4) {
c->u.a.totallen =
4 + GET_32BIT(c->u.a.msglen);
c->u.a.message = smalloc(c->u.a.totallen);
memcpy(c->u.a.message, c->u.a.msglen, 4);
}
if (c->u.a.lensofar >= 4 && length > 0) {
int l =
min(c->u.a.totallen - c->u.a.lensofar,
length);
memcpy(c->u.a.message + c->u.a.lensofar,
data, l);
data += l;
length -= l;
c->u.a.lensofar += l;
}
if (c->u.a.lensofar == c->u.a.totallen) {
void *reply, *sentreply;
int replylen;
agent_query(c->u.a.message,
c->u.a.totallen, &reply,
&replylen);
if (reply)
sentreply = reply;
else {
/* Fake SSH_AGENT_FAILURE. */
sentreply = "\0\0\0\1\5";
replylen = 5;
}
ssh2_add_channel_data(c, sentreply, replylen);
s->try_send = TRUE;
if (reply)
sfree(reply);
sfree(c->u.a.message);
c->u.a.lensofar = 0;
}
}
bufsize = 0;
break;
}
/*
* If we are not buffering too much data,
* enlarge the window again at the remote side.
*/
if (bufsize < OUR_V2_WINSIZE)
ssh2_set_window(c, OUR_V2_WINSIZE - bufsize);
}
} else if (ssh->pktin.type == SSH2_MSG_CHANNEL_EOF) {
unsigned i = ssh2_pkt_getuint32(ssh);
struct ssh_channel *c;
c = find234(ssh->channels, &i, ssh_channelfind);
if (!c)
continue; /* nonexistent channel */
if (c->type == CHAN_X11) {
/*
* Remote EOF on an X11 channel means we should
* wrap up and close the channel ourselves.
*/
x11_close(c->u.x11.s);
sshfwd_close(c);
} else if (c->type == CHAN_AGENT) {
sshfwd_close(c);
} else if (c->type == CHAN_SOCKDATA) {
pfd_close(c->u.pfd.s);
sshfwd_close(c);
}
} else if (ssh->pktin.type == SSH2_MSG_CHANNEL_CLOSE) {
unsigned i = ssh2_pkt_getuint32(ssh);
struct ssh_channel *c;
c = find234(ssh->channels, &i, ssh_channelfind);
if (!c || ((int)c->remoteid) == -1) {
bombout((ssh,"Received CHANNEL_CLOSE for %s channel %d\n",
c ? "half-open" : "nonexistent", i));
}
/* Do pre-close processing on the channel. */
switch (c->type) {
case CHAN_MAINSESSION:
break; /* nothing to see here, move along */
case CHAN_X11:
if (c->u.x11.s != NULL)
x11_close(c->u.x11.s);
sshfwd_close(c);
break;
case CHAN_AGENT:
sshfwd_close(c);
break;
case CHAN_SOCKDATA:
if (c->u.pfd.s != NULL)
pfd_close(c->u.pfd.s);
sshfwd_close(c);
break;
}
if (c->closes == 0) {
ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_CLOSE);
ssh2_pkt_adduint32(ssh, c->remoteid);
ssh2_pkt_send(ssh);
}
del234(ssh->channels, c);
bufchain_clear(&c->v.v2.outbuffer);
sfree(c);
/*
* See if that was the last channel left open.
*/
if (count234(ssh->channels) == 0) {
#if 0
/*
* We used to send SSH_MSG_DISCONNECT here,
* because I'd believed that _every_ conforming
* SSH2 connection had to end with a disconnect
* being sent by at least one side; apparently
* I was wrong and it's perfectly OK to
* unceremoniously slam the connection shut
* when you're done, and indeed OpenSSH feels
* this is more polite than sending a
* DISCONNECT. So now we don't.
*/
logevent("All channels closed. Disconnecting");
ssh2_pkt_init(ssh, SSH2_MSG_DISCONNECT);
ssh2_pkt_adduint32(ssh, SSH2_DISCONNECT_BY_APPLICATION);
ssh2_pkt_addstring(ssh, "All open channels closed");
ssh2_pkt_addstring(ssh, "en"); /* language tag */
ssh2_pkt_send(ssh);
#endif
ssh->state = SSH_STATE_CLOSED;
crReturnV;
}
continue; /* remote sends close; ignore (FIXME) */
} else if (ssh->pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST) {
unsigned i = ssh2_pkt_getuint32(ssh);
struct ssh_channel *c;
c = find234(ssh->channels, &i, ssh_channelfind);
if (!c || c->closes)
continue; /* nonexistent or closing channel */
c->v.v2.remwindow += ssh2_pkt_getuint32(ssh);
s->try_send = TRUE;
} else if (ssh->pktin.type == SSH2_MSG_CHANNEL_OPEN_CONFIRMATION) {
unsigned i = ssh2_pkt_getuint32(ssh);
struct ssh_channel *c;
c = find234(ssh->channels, &i, ssh_channelfind);
if (!c)
continue; /* nonexistent channel */
if (c->type != CHAN_SOCKDATA_DORMANT)
continue; /* dunno why they're confirming this */
c->remoteid = ssh2_pkt_getuint32(ssh);
c->type = CHAN_SOCKDATA;
c->v.v2.remwindow = ssh2_pkt_getuint32(ssh);
c->v.v2.remmaxpkt = ssh2_pkt_getuint32(ssh);
if (c->u.pfd.s)
pfd_confirm(c->u.pfd.s);
if (c->closes) {
/*
* We have a pending close on this channel,
* which we decided on before the server acked
* the channel open. So now we know the
* remoteid, we can close it again.
*/
ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_CLOSE);
ssh2_pkt_adduint32(ssh, c->remoteid);
ssh2_pkt_send(ssh);
}
} else if (ssh->pktin.type == SSH2_MSG_CHANNEL_OPEN_FAILURE) {
unsigned i = ssh2_pkt_getuint32(ssh);
struct ssh_channel *c;
c = find234(ssh->channels, &i, ssh_channelfind);
if (!c)
continue; /* nonexistent channel */
if (c->type != CHAN_SOCKDATA_DORMANT)
continue; /* dunno why they're failing this */
logevent("Forwarded connection refused by server");
pfd_close(c->u.pfd.s);
del234(ssh->channels, c);
sfree(c);
} else if (ssh->pktin.type == SSH2_MSG_CHANNEL_REQUEST) {
unsigned localid;
char *type;
int typelen, want_reply;
struct ssh_channel *c;
localid = ssh2_pkt_getuint32(ssh);
ssh2_pkt_getstring(ssh, &type, &typelen);
want_reply = ssh2_pkt_getbool(ssh);
/*
* First, check that the channel exists. Otherwise,
* we can instantly disconnect with a rude message.
*/
c = find234(ssh->channels, &localid, ssh_channelfind);
if (!c) {
char buf[80];
sprintf(buf, "Received channel request for nonexistent"
" channel %d", localid);
logevent(buf);
ssh2_pkt_init(ssh, SSH2_MSG_DISCONNECT);
ssh2_pkt_adduint32(ssh, SSH2_DISCONNECT_BY_APPLICATION);
ssh2_pkt_addstring(ssh, buf);
ssh2_pkt_addstring(ssh, "en"); /* language tag */
ssh2_pkt_send(ssh);
connection_fatal("%s", buf);
ssh->state = SSH_STATE_CLOSED;
crReturnV;
}
/*
* Having got the channel number, we now look at
* the request type string to see if it's something
* we recognise.
*/
if (typelen == 11 && !memcmp(type, "exit-status", 11) &&
c == ssh->mainchan) {
/* We recognise "exit-status" on the primary channel. */
char buf[100];
ssh->exitcode = ssh2_pkt_getuint32(ssh);
sprintf(buf, "Server sent command exit status %d",
ssh->exitcode);
logevent(buf);
if (want_reply) {
ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_SUCCESS);
ssh2_pkt_adduint32(ssh, c->remoteid);
ssh2_pkt_send(ssh);
}
} else {
/*
* This is a channel request we don't know
* about, so we now either ignore the request
* or respond with CHANNEL_FAILURE, depending
* on want_reply.
*/
if (want_reply) {
ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_FAILURE);
ssh2_pkt_adduint32(ssh, c->remoteid);
ssh2_pkt_send(ssh);
}
}
} else if (ssh->pktin.type == SSH2_MSG_GLOBAL_REQUEST) {
char *type;
int typelen, want_reply;
ssh2_pkt_getstring(ssh, &type, &typelen);
want_reply = ssh2_pkt_getbool(ssh);
/*
* We currently don't support any global requests
* at all, so we either ignore the request or
* respond with REQUEST_FAILURE, depending on
* want_reply.
*/
if (want_reply) {
ssh2_pkt_init(ssh, SSH2_MSG_REQUEST_FAILURE);
ssh2_pkt_send(ssh);
}
} else if (ssh->pktin.type == SSH2_MSG_CHANNEL_OPEN) {
char *type;
int typelen;
char *error = NULL;
struct ssh_channel *c;
unsigned remid, winsize, pktsize;
ssh2_pkt_getstring(ssh, &type, &typelen);
c = smalloc(sizeof(struct ssh_channel));
c->ssh = ssh;
remid = ssh2_pkt_getuint32(ssh);
winsize = ssh2_pkt_getuint32(ssh);
pktsize = ssh2_pkt_getuint32(ssh);
if (typelen == 3 && !memcmp(type, "x11", 3)) {
if (!ssh->X11_fwd_enabled)
error = "X11 forwarding is not enabled";
else if (x11_init(&c->u.x11.s, cfg.x11_display, c,
ssh->x11auth) != NULL) {
error = "Unable to open an X11 connection";
} else {
c->type = CHAN_X11;
}
} else if (typelen == 15 &&
!memcmp(type, "forwarded-tcpip", 15)) {
struct ssh_rportfwd pf, *realpf;
char *dummy;
int dummylen;
ssh2_pkt_getstring(ssh, &dummy, &dummylen);/* skip address */
pf.sport = ssh2_pkt_getuint32(ssh);
realpf = find234(ssh->rportfwds, &pf, NULL);
if (realpf == NULL) {
error = "Remote port is not recognised";
} else {
char *e = pfd_newconnect(&c->u.pfd.s, realpf->dhost,
realpf->dport, c);
logeventf(ssh, "Received remote port open request"
" for %s:%d", realpf->dhost, realpf->dport);
if (e != NULL) {
logeventf(ssh, "Port open failed: %s", e);
error = "Port open failed";
} else {
logevent("Forwarded port opened successfully");
c->type = CHAN_SOCKDATA;
}
}
} else if (typelen == 22 &&
!memcmp(type, "auth-agent@openssh.com", 3)) {
if (!ssh->agentfwd_enabled)
error = "Agent forwarding is not enabled";
else {
c->type = CHAN_AGENT; /* identify channel type */
c->u.a.lensofar = 0;
}
} else {
error = "Unsupported channel type requested";
}
c->remoteid = remid;
if (error) {
ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE);
ssh2_pkt_adduint32(ssh, c->remoteid);
ssh2_pkt_adduint32(ssh, SSH2_OPEN_CONNECT_FAILED);
ssh2_pkt_addstring(ssh, error);
ssh2_pkt_addstring(ssh, "en"); /* language tag */
ssh2_pkt_send(ssh);
sfree(c);
} else {
c->localid = alloc_channel_id(ssh);
c->closes = 0;
c->v.v2.locwindow = OUR_V2_WINSIZE;
c->v.v2.remwindow = winsize;
c->v.v2.remmaxpkt = pktsize;
bufchain_init(&c->v.v2.outbuffer);
add234(ssh->channels, c);
ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
ssh2_pkt_adduint32(ssh, c->remoteid);
ssh2_pkt_adduint32(ssh, c->localid);
ssh2_pkt_adduint32(ssh, c->v.v2.locwindow);
ssh2_pkt_adduint32(ssh, 0x4000UL); /* our max pkt size */
ssh2_pkt_send(ssh);
}
} else {
bombout((ssh,"Strange packet received: type %d", ssh->pktin.type));
crReturnV;
}
} else {
/*
* We have spare data. Add it to the channel buffer.
*/
ssh2_add_channel_data(ssh->mainchan, (char *)in, inlen);
s->try_send = TRUE;
}
if (s->try_send) {
int i;
struct ssh_channel *c;
/*
* Try to send data on all channels if we can.
*/
for (i = 0; NULL != (c = index234(ssh->channels, i)); i++) {
int bufsize;
if (c->closes)
continue; /* don't send on closing channels */
bufsize = ssh2_try_send(c);
if (bufsize == 0) {
switch (c->type) {
case CHAN_MAINSESSION:
/* stdin need not receive an unthrottle
* notification since it will be polled */
break;
case CHAN_X11:
x11_unthrottle(c->u.x11.s);
break;
case CHAN_AGENT:
/* agent sockets are request/response and need no
* buffer management */
break;
case CHAN_SOCKDATA:
pfd_unthrottle(c->u.pfd.s);
break;
}
}
}
}
}
crFinishV;
}
/*
* Handle the top-level SSH2 protocol.
*/
static void ssh2_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
{
if (do_ssh2_transport(ssh, in, inlen, ispkt) == 0)
return;
do_ssh2_authconn(ssh, in, inlen, ispkt);
}
/*
* Called to set up the connection.
*
* Returns an error message, or NULL on success.
*/
static char *ssh_init(void *frontend_handle, void **backend_handle,
char *host, int port, char **realhost, int nodelay)
{
char *p;
Ssh ssh;
ssh = smalloc(sizeof(*ssh));
ssh->s = NULL;
ssh->cipher = NULL;
ssh->v1_cipher_ctx = NULL;
ssh->crcda_ctx = NULL;
ssh->cscipher = NULL;
ssh->cs_cipher_ctx = NULL;
ssh->sccipher = NULL;
ssh->sc_cipher_ctx = NULL;
ssh->csmac = NULL;
ssh->cs_mac_ctx = NULL;
ssh->scmac = NULL;
ssh->sc_mac_ctx = NULL;
ssh->cscomp = NULL;
ssh->cs_comp_ctx = NULL;
ssh->sccomp = NULL;
ssh->sc_comp_ctx = NULL;
ssh->kex = NULL;
ssh->hostkey = NULL;
ssh->exitcode = -1;
ssh->state = SSH_STATE_PREPACKET;
ssh->size_needed = FALSE;
ssh->eof_needed = FALSE;
ssh->ldisc = NULL;
ssh->logctx = NULL;
{
static const struct Packet empty = { 0, 0, NULL, NULL, 0 };
ssh->pktin = ssh->pktout = empty;
}
ssh->deferred_send_data = NULL;
ssh->deferred_len = 0;
ssh->deferred_size = 0;
ssh->fallback_cmd = 0;
ssh->pkt_ctx = 0;
ssh->x11auth = NULL;
ssh->v1_compressing = FALSE;
ssh->v2_outgoing_sequence = 0;
ssh->ssh1_rdpkt_crstate = 0;
ssh->ssh2_rdpkt_crstate = 0;
ssh->do_ssh_init_crstate = 0;
ssh->ssh_gotdata_crstate = 0;
ssh->ssh1_protocol_crstate = 0;
ssh->do_ssh1_login_crstate = 0;
ssh->do_ssh2_transport_crstate = 0;
ssh->do_ssh2_authconn_crstate = 0;
ssh->do_ssh_init_state = NULL;
ssh->do_ssh1_login_state = NULL;
ssh->do_ssh2_transport_state = NULL;
ssh->do_ssh2_authconn_state = NULL;
ssh->mainchan = NULL;
ssh->throttled_all = 0;
ssh->v1_stdout_throttling = 0;
*backend_handle = ssh;
#ifdef MSCRYPTOAPI
if (crypto_startup() == 0)
return "Microsoft high encryption pack not installed!";
#endif
ssh->frontend = frontend_handle;
ssh->term_width = cfg.width;
ssh->term_height = cfg.height;
ssh->send_ok = 0;
ssh->editing = 0;
ssh->echoing = 0;
ssh->v1_throttle_count = 0;
ssh->overall_bufsize = 0;
ssh->fallback_cmd = 0;
ssh->protocol = NULL;
p = connect_to_host(ssh, host, port, realhost, nodelay);
if (p != NULL)
return p;
return NULL;
}
/*
* Called to send data down the Telnet connection.
*/
static int ssh_send(void *handle, char *buf, int len)
{
Ssh ssh = (Ssh) handle;
if (ssh == NULL || ssh->s == NULL || ssh->protocol == NULL)
return 0;
ssh->protocol(ssh, (unsigned char *)buf, len, 0);
return ssh_sendbuffer(ssh);
}
/*
* Called to query the current amount of buffered stdin data.
*/
static int ssh_sendbuffer(void *handle)
{
Ssh ssh = (Ssh) handle;
int override_value;
if (ssh == NULL || ssh->s == NULL || ssh->protocol == NULL)
return 0;
/*
* If the SSH socket itself has backed up, add the total backup
* size on that to any individual buffer on the stdin channel.
*/
override_value = 0;
if (ssh->throttled_all)
override_value = ssh->overall_bufsize;
if (ssh->version == 1) {
return override_value;
} else if (ssh->version == 2) {
if (!ssh->mainchan || ssh->mainchan->closes > 0)
return override_value;
else
return (override_value +
bufchain_size(&ssh->mainchan->v.v2.outbuffer));
}
return 0;
}
/*
* Called to set the size of the window from SSH's POV.
*/
static void ssh_size(void *handle, int width, int height)
{
Ssh ssh = (Ssh) handle;
ssh->term_width = width;
ssh->term_height = height;
switch (ssh->state) {
case SSH_STATE_BEFORE_SIZE:
case SSH_STATE_PREPACKET:
case SSH_STATE_CLOSED:
break; /* do nothing */
case SSH_STATE_INTERMED:
ssh->size_needed = TRUE; /* buffer for later */
break;
case SSH_STATE_SESSION:
if (!cfg.nopty) {
if (ssh->version == 1) {
send_packet(ssh, SSH1_CMSG_WINDOW_SIZE,
PKT_INT, ssh->term_height,
PKT_INT, ssh->term_width,
PKT_INT, 0, PKT_INT, 0, PKT_END);
} else {
ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_REQUEST);
ssh2_pkt_adduint32(ssh, ssh->mainchan->remoteid);
ssh2_pkt_addstring(ssh, "window-change");
ssh2_pkt_addbool(ssh, 0);
ssh2_pkt_adduint32(ssh, ssh->term_width);
ssh2_pkt_adduint32(ssh, ssh->term_height);
ssh2_pkt_adduint32(ssh, 0);
ssh2_pkt_adduint32(ssh, 0);
ssh2_pkt_send(ssh);
}
}
break;
}
}
/*
* Send Telnet special codes. TS_EOF is useful for `plink', so you
* can send an EOF and collect resulting output (e.g. `plink
* hostname sort').
*/
static void ssh_special(void *handle, Telnet_Special code)
{
Ssh ssh = (Ssh) handle;
if (code == TS_EOF) {
if (ssh->state != SSH_STATE_SESSION) {
/*
* Buffer the EOF in case we are pre-SESSION, so we can
* send it as soon as we reach SESSION.
*/
if (code == TS_EOF)
ssh->eof_needed = TRUE;
return;
}
if (ssh->version == 1) {
send_packet(ssh, SSH1_CMSG_EOF, PKT_END);
} else {
ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_EOF);
ssh2_pkt_adduint32(ssh, ssh->mainchan->remoteid);
ssh2_pkt_send(ssh);
}
logevent("Sent EOF message");
} else if (code == TS_PING) {
if (ssh->state == SSH_STATE_CLOSED
|| ssh->state == SSH_STATE_PREPACKET) return;
if (ssh->version == 1) {
if (!(ssh->remote_bugs & BUG_CHOKES_ON_SSH1_IGNORE))
send_packet(ssh, SSH1_MSG_IGNORE, PKT_STR, "", PKT_END);
} else {
ssh2_pkt_init(ssh, SSH2_MSG_IGNORE);
ssh2_pkt_addstring_start(ssh);
ssh2_pkt_send(ssh);
}
} else {
/* do nothing */
}
}
void *new_sock_channel(void *handle, Socket s)
{
Ssh ssh = (Ssh) handle;
struct ssh_channel *c;
c = smalloc(sizeof(struct ssh_channel));
c->ssh = ssh;
if (c) {
c->remoteid = -1; /* to be set when open confirmed */
c->localid = alloc_channel_id(ssh);
c->closes = 0;
c->type = CHAN_SOCKDATA_DORMANT;/* identify channel type */
c->u.pfd.s = s;
bufchain_init(&c->v.v2.outbuffer);
add234(ssh->channels, c);
}
return c;
}
/*
* This is called when stdout/stderr (the entity to which
* from_backend sends data) manages to clear some backlog.
*/
static void ssh_unthrottle(void *handle, int bufsize)
{
Ssh ssh = (Ssh) handle;
if (ssh->version == 1) {
if (ssh->v1_stdout_throttling && bufsize < SSH1_BUFFER_LIMIT) {
ssh->v1_stdout_throttling = 0;
ssh1_throttle(ssh, -1);
}
} else {
if (ssh->mainchan && ssh->mainchan->closes == 0)
ssh2_set_window(ssh->mainchan, OUR_V2_WINSIZE - bufsize);
}
}
void ssh_send_port_open(void *channel, char *hostname, int port, char *org)
{
struct ssh_channel *c = (struct ssh_channel *)channel;
Ssh ssh = c->ssh;
logeventf(ssh, "Opening forwarded connection to %s:%d", hostname, port);
if (ssh->version == 1) {
send_packet(ssh, SSH1_MSG_PORT_OPEN,
PKT_INT, c->localid,
PKT_STR, hostname,
PKT_INT, port,
//PKT_STR, <org:orgport>,
PKT_END);
} else {
ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_OPEN);
ssh2_pkt_addstring(ssh, "direct-tcpip");
ssh2_pkt_adduint32(ssh, c->localid);
c->v.v2.locwindow = OUR_V2_WINSIZE;
ssh2_pkt_adduint32(ssh, c->v.v2.locwindow);/* our window size */
ssh2_pkt_adduint32(ssh, 0x4000UL); /* our max pkt size */
ssh2_pkt_addstring(ssh, hostname);
ssh2_pkt_adduint32(ssh, port);
/*
* We make up values for the originator data; partly it's
* too much hassle to keep track, and partly I'm not
* convinced the server should be told details like that
* about my local network configuration.
*/
ssh2_pkt_addstring(ssh, "client-side-connection");
ssh2_pkt_adduint32(ssh, 0);
ssh2_pkt_send(ssh);
}
}
static Socket ssh_socket(void *handle)
{
Ssh ssh = (Ssh) handle;
return ssh->s;
}
static int ssh_sendok(void *handle)
{
Ssh ssh = (Ssh) handle;
return ssh->send_ok;
}
static int ssh_ldisc(void *handle, int option)
{
Ssh ssh = (Ssh) handle;
if (option == LD_ECHO)
return ssh->echoing;
if (option == LD_EDIT)
return ssh->editing;
return FALSE;
}
static void ssh_provide_ldisc(void *handle, void *ldisc)
{
Ssh ssh = (Ssh) handle;
ssh->ldisc = ldisc;
}
static void ssh_provide_logctx(void *handle, void *logctx)
{
Ssh ssh = (Ssh) handle;
ssh->logctx = logctx;
}
static int ssh_return_exitcode(void *handle)
{
Ssh ssh = (Ssh) handle;
return ssh->exitcode;
}
/*
* Gross hack: pscp will try to start SFTP but fall back to scp1 if
* that fails. This variable is the means by which scp.c can reach
* into the SSH code and find out which one it got.
*/
extern int ssh_fallback_cmd(void *handle)
{
Ssh ssh = (Ssh) handle;
return ssh->fallback_cmd;
}
Backend ssh_backend = {
ssh_init,
ssh_send,
ssh_sendbuffer,
ssh_size,
ssh_special,
ssh_socket,
ssh_return_exitcode,
ssh_sendok,
ssh_ldisc,
ssh_provide_ldisc,
ssh_provide_logctx,
ssh_unthrottle,
22
};
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