1223 строки
29 KiB
C
1223 строки
29 KiB
C
/*
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* NET3: Implementation of the ICMP protocol layer.
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*
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* Alan Cox, <alan@lxorguk.ukuu.org.uk>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* Some of the function names and the icmp unreach table for this
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* module were derived from [icmp.c 1.0.11 06/02/93] by
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* Ross Biro, Fred N. van Kempen, Mark Evans, Alan Cox, Gerhard Koerting.
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* Other than that this module is a complete rewrite.
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*
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* Fixes:
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* Clemens Fruhwirth : introduce global icmp rate limiting
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* with icmp type masking ability instead
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* of broken per type icmp timeouts.
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* Mike Shaver : RFC1122 checks.
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* Alan Cox : Multicast ping reply as self.
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* Alan Cox : Fix atomicity lockup in ip_build_xmit
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* call.
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* Alan Cox : Added 216,128 byte paths to the MTU
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* code.
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* Martin Mares : RFC1812 checks.
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* Martin Mares : Can be configured to follow redirects
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* if acting as a router _without_ a
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* routing protocol (RFC 1812).
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* Martin Mares : Echo requests may be configured to
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* be ignored (RFC 1812).
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* Martin Mares : Limitation of ICMP error message
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* transmit rate (RFC 1812).
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* Martin Mares : TOS and Precedence set correctly
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* (RFC 1812).
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* Martin Mares : Now copying as much data from the
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* original packet as we can without
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* exceeding 576 bytes (RFC 1812).
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* Willy Konynenberg : Transparent proxying support.
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* Keith Owens : RFC1191 correction for 4.2BSD based
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* path MTU bug.
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* Thomas Quinot : ICMP Dest Unreach codes up to 15 are
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* valid (RFC 1812).
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* Andi Kleen : Check all packet lengths properly
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* and moved all kfree_skb() up to
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* icmp_rcv.
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* Andi Kleen : Move the rate limit bookkeeping
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* into the dest entry and use a token
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* bucket filter (thanks to ANK). Make
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* the rates sysctl configurable.
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* Yu Tianli : Fixed two ugly bugs in icmp_send
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* - IP option length was accounted wrongly
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* - ICMP header length was not accounted
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* at all.
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* Tristan Greaves : Added sysctl option to ignore bogus
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* broadcast responses from broken routers.
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*
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* To Fix:
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*
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* - Should use skb_pull() instead of all the manual checking.
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* This would also greatly simply some upper layer error handlers. --AK
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*
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*/
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/jiffies.h>
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#include <linux/kernel.h>
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#include <linux/fcntl.h>
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#include <linux/socket.h>
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#include <linux/in.h>
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#include <linux/inet.h>
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#include <linux/inetdevice.h>
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#include <linux/netdevice.h>
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#include <linux/string.h>
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#include <linux/netfilter_ipv4.h>
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#include <linux/slab.h>
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#include <net/snmp.h>
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#include <net/ip.h>
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#include <net/route.h>
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#include <net/protocol.h>
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#include <net/icmp.h>
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#include <net/tcp.h>
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#include <net/udp.h>
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#include <net/raw.h>
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#include <linux/skbuff.h>
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#include <net/sock.h>
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#include <linux/errno.h>
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#include <linux/timer.h>
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#include <linux/init.h>
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#include <asm/system.h>
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#include <asm/uaccess.h>
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#include <net/checksum.h>
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#include <net/xfrm.h>
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#include <net/inet_common.h>
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/*
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* Build xmit assembly blocks
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*/
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struct icmp_bxm {
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struct sk_buff *skb;
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int offset;
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int data_len;
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struct {
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struct icmphdr icmph;
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__be32 times[3];
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} data;
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int head_len;
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struct ip_options replyopts;
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unsigned char optbuf[40];
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};
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/* An array of errno for error messages from dest unreach. */
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/* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */
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const struct icmp_err icmp_err_convert[] = {
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{
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.errno = ENETUNREACH, /* ICMP_NET_UNREACH */
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.fatal = 0,
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},
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{
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.errno = EHOSTUNREACH, /* ICMP_HOST_UNREACH */
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.fatal = 0,
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},
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{
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.errno = ENOPROTOOPT /* ICMP_PROT_UNREACH */,
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.fatal = 1,
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},
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{
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.errno = ECONNREFUSED, /* ICMP_PORT_UNREACH */
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.fatal = 1,
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},
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{
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.errno = EMSGSIZE, /* ICMP_FRAG_NEEDED */
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.fatal = 0,
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},
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{
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.errno = EOPNOTSUPP, /* ICMP_SR_FAILED */
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.fatal = 0,
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},
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{
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.errno = ENETUNREACH, /* ICMP_NET_UNKNOWN */
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.fatal = 1,
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},
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{
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.errno = EHOSTDOWN, /* ICMP_HOST_UNKNOWN */
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.fatal = 1,
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},
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{
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.errno = ENONET, /* ICMP_HOST_ISOLATED */
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.fatal = 1,
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},
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{
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.errno = ENETUNREACH, /* ICMP_NET_ANO */
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.fatal = 1,
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},
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{
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.errno = EHOSTUNREACH, /* ICMP_HOST_ANO */
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.fatal = 1,
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},
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{
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.errno = ENETUNREACH, /* ICMP_NET_UNR_TOS */
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.fatal = 0,
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},
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{
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.errno = EHOSTUNREACH, /* ICMP_HOST_UNR_TOS */
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.fatal = 0,
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},
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{
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.errno = EHOSTUNREACH, /* ICMP_PKT_FILTERED */
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.fatal = 1,
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},
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{
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.errno = EHOSTUNREACH, /* ICMP_PREC_VIOLATION */
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.fatal = 1,
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},
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{
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.errno = EHOSTUNREACH, /* ICMP_PREC_CUTOFF */
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.fatal = 1,
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},
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};
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/*
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* ICMP control array. This specifies what to do with each ICMP.
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*/
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struct icmp_control {
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void (*handler)(struct sk_buff *skb);
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short error; /* This ICMP is classed as an error message */
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};
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static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1];
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/*
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* The ICMP socket(s). This is the most convenient way to flow control
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* our ICMP output as well as maintain a clean interface throughout
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* all layers. All Socketless IP sends will soon be gone.
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*
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* On SMP we have one ICMP socket per-cpu.
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*/
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static struct sock *icmp_sk(struct net *net)
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{
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return net->ipv4.icmp_sk[smp_processor_id()];
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}
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static inline struct sock *icmp_xmit_lock(struct net *net)
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{
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struct sock *sk;
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local_bh_disable();
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sk = icmp_sk(net);
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if (unlikely(!spin_trylock(&sk->sk_lock.slock))) {
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/* This can happen if the output path signals a
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* dst_link_failure() for an outgoing ICMP packet.
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*/
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local_bh_enable();
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return NULL;
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}
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return sk;
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}
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static inline void icmp_xmit_unlock(struct sock *sk)
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{
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spin_unlock_bh(&sk->sk_lock.slock);
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}
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/*
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* Send an ICMP frame.
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*/
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/*
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* Check transmit rate limitation for given message.
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* The rate information is held in the destination cache now.
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* This function is generic and could be used for other purposes
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* too. It uses a Token bucket filter as suggested by Alexey Kuznetsov.
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*
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* Note that the same dst_entry fields are modified by functions in
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* route.c too, but these work for packet destinations while xrlim_allow
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* works for icmp destinations. This means the rate limiting information
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* for one "ip object" is shared - and these ICMPs are twice limited:
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* by source and by destination.
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*
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* RFC 1812: 4.3.2.8 SHOULD be able to limit error message rate
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* SHOULD allow setting of rate limits
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*
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* Shared between ICMPv4 and ICMPv6.
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*/
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#define XRLIM_BURST_FACTOR 6
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int xrlim_allow(struct dst_entry *dst, int timeout)
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{
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unsigned long now, token = dst->rate_tokens;
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int rc = 0;
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now = jiffies;
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token += now - dst->rate_last;
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dst->rate_last = now;
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if (token > XRLIM_BURST_FACTOR * timeout)
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token = XRLIM_BURST_FACTOR * timeout;
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if (token >= timeout) {
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token -= timeout;
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rc = 1;
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}
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dst->rate_tokens = token;
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return rc;
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}
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static inline int icmpv4_xrlim_allow(struct net *net, struct rtable *rt,
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int type, int code)
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{
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struct dst_entry *dst = &rt->u.dst;
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int rc = 1;
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if (type > NR_ICMP_TYPES)
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goto out;
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/* Don't limit PMTU discovery. */
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if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
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goto out;
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/* No rate limit on loopback */
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if (dst->dev && (dst->dev->flags&IFF_LOOPBACK))
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goto out;
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/* Limit if icmp type is enabled in ratemask. */
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if ((1 << type) & net->ipv4.sysctl_icmp_ratemask)
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rc = xrlim_allow(dst, net->ipv4.sysctl_icmp_ratelimit);
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out:
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return rc;
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}
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/*
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* Maintain the counters used in the SNMP statistics for outgoing ICMP
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*/
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void icmp_out_count(struct net *net, unsigned char type)
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{
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ICMPMSGOUT_INC_STATS(net, type);
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ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS);
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}
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/*
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* Checksum each fragment, and on the first include the headers and final
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* checksum.
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*/
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static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
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struct sk_buff *skb)
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{
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struct icmp_bxm *icmp_param = (struct icmp_bxm *)from;
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__wsum csum;
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csum = skb_copy_and_csum_bits(icmp_param->skb,
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icmp_param->offset + offset,
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to, len, 0);
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skb->csum = csum_block_add(skb->csum, csum, odd);
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if (icmp_pointers[icmp_param->data.icmph.type].error)
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nf_ct_attach(skb, icmp_param->skb);
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return 0;
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}
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static void icmp_push_reply(struct icmp_bxm *icmp_param,
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struct ipcm_cookie *ipc, struct rtable **rt)
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{
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struct sock *sk;
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struct sk_buff *skb;
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sk = icmp_sk(dev_net((*rt)->u.dst.dev));
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if (ip_append_data(sk, icmp_glue_bits, icmp_param,
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icmp_param->data_len+icmp_param->head_len,
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icmp_param->head_len,
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ipc, rt, MSG_DONTWAIT) < 0) {
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ICMP_INC_STATS_BH(sock_net(sk), ICMP_MIB_OUTERRORS);
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ip_flush_pending_frames(sk);
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} else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
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struct icmphdr *icmph = icmp_hdr(skb);
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__wsum csum = 0;
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struct sk_buff *skb1;
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skb_queue_walk(&sk->sk_write_queue, skb1) {
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csum = csum_add(csum, skb1->csum);
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}
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csum = csum_partial_copy_nocheck((void *)&icmp_param->data,
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(char *)icmph,
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icmp_param->head_len, csum);
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icmph->checksum = csum_fold(csum);
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skb->ip_summed = CHECKSUM_NONE;
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ip_push_pending_frames(sk);
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}
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}
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/*
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* Driving logic for building and sending ICMP messages.
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*/
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static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
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{
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struct ipcm_cookie ipc;
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struct rtable *rt = skb_rtable(skb);
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struct net *net = dev_net(rt->u.dst.dev);
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struct sock *sk;
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struct inet_sock *inet;
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__be32 daddr;
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if (ip_options_echo(&icmp_param->replyopts, skb))
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return;
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sk = icmp_xmit_lock(net);
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if (sk == NULL)
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return;
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inet = inet_sk(sk);
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icmp_param->data.icmph.checksum = 0;
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inet->tos = ip_hdr(skb)->tos;
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daddr = ipc.addr = rt->rt_src;
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ipc.opt = NULL;
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ipc.shtx.flags = 0;
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if (icmp_param->replyopts.optlen) {
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ipc.opt = &icmp_param->replyopts;
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if (ipc.opt->srr)
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daddr = icmp_param->replyopts.faddr;
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}
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{
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struct flowi fl = { .nl_u = { .ip4_u =
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{ .daddr = daddr,
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.saddr = rt->rt_spec_dst,
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.tos = RT_TOS(ip_hdr(skb)->tos) } },
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.proto = IPPROTO_ICMP };
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security_skb_classify_flow(skb, &fl);
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if (ip_route_output_key(net, &rt, &fl))
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goto out_unlock;
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}
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if (icmpv4_xrlim_allow(net, rt, icmp_param->data.icmph.type,
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icmp_param->data.icmph.code))
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icmp_push_reply(icmp_param, &ipc, &rt);
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ip_rt_put(rt);
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out_unlock:
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icmp_xmit_unlock(sk);
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}
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/*
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* Send an ICMP message in response to a situation
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*
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* RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header.
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* MAY send more (we do).
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* MUST NOT change this header information.
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* MUST NOT reply to a multicast/broadcast IP address.
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* MUST NOT reply to a multicast/broadcast MAC address.
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* MUST reply to only the first fragment.
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*/
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void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
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{
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struct iphdr *iph;
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int room;
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struct icmp_bxm icmp_param;
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struct rtable *rt = skb_rtable(skb_in);
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struct ipcm_cookie ipc;
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__be32 saddr;
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u8 tos;
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struct net *net;
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struct sock *sk;
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if (!rt)
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goto out;
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net = dev_net(rt->u.dst.dev);
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|
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/*
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* Find the original header. It is expected to be valid, of course.
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* Check this, icmp_send is called from the most obscure devices
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* sometimes.
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*/
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iph = ip_hdr(skb_in);
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if ((u8 *)iph < skb_in->head ||
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(skb_in->network_header + sizeof(*iph)) > skb_in->tail)
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goto out;
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/*
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* No replies to physical multicast/broadcast
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*/
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if (skb_in->pkt_type != PACKET_HOST)
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goto out;
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/*
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* Now check at the protocol level
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*/
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if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
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goto out;
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/*
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* Only reply to fragment 0. We byte re-order the constant
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* mask for efficiency.
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*/
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if (iph->frag_off & htons(IP_OFFSET))
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goto out;
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/*
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* If we send an ICMP error to an ICMP error a mess would result..
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*/
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if (icmp_pointers[type].error) {
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/*
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* We are an error, check if we are replying to an
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* ICMP error
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*/
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if (iph->protocol == IPPROTO_ICMP) {
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u8 _inner_type, *itp;
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itp = skb_header_pointer(skb_in,
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skb_network_header(skb_in) +
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(iph->ihl << 2) +
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offsetof(struct icmphdr,
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type) -
|
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skb_in->data,
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sizeof(_inner_type),
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&_inner_type);
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if (itp == NULL)
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goto out;
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|
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/*
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* Assume any unknown ICMP type is an error. This
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* isn't specified by the RFC, but think about it..
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*/
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if (*itp > NR_ICMP_TYPES ||
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icmp_pointers[*itp].error)
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goto out;
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}
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}
|
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|
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sk = icmp_xmit_lock(net);
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if (sk == NULL)
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return;
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|
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/*
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* Construct source address and options.
|
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*/
|
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|
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saddr = iph->daddr;
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if (!(rt->rt_flags & RTCF_LOCAL)) {
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struct net_device *dev = NULL;
|
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|
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rcu_read_lock();
|
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if (rt->fl.iif &&
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net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)
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dev = dev_get_by_index_rcu(net, rt->fl.iif);
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|
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if (dev)
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saddr = inet_select_addr(dev, 0, RT_SCOPE_LINK);
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else
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saddr = 0;
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rcu_read_unlock();
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}
|
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|
|
tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) |
|
|
IPTOS_PREC_INTERNETCONTROL) :
|
|
iph->tos;
|
|
|
|
if (ip_options_echo(&icmp_param.replyopts, skb_in))
|
|
goto out_unlock;
|
|
|
|
|
|
/*
|
|
* Prepare data for ICMP header.
|
|
*/
|
|
|
|
icmp_param.data.icmph.type = type;
|
|
icmp_param.data.icmph.code = code;
|
|
icmp_param.data.icmph.un.gateway = info;
|
|
icmp_param.data.icmph.checksum = 0;
|
|
icmp_param.skb = skb_in;
|
|
icmp_param.offset = skb_network_offset(skb_in);
|
|
inet_sk(sk)->tos = tos;
|
|
ipc.addr = iph->saddr;
|
|
ipc.opt = &icmp_param.replyopts;
|
|
ipc.shtx.flags = 0;
|
|
|
|
{
|
|
struct flowi fl = {
|
|
.nl_u = {
|
|
.ip4_u = {
|
|
.daddr = icmp_param.replyopts.srr ?
|
|
icmp_param.replyopts.faddr :
|
|
iph->saddr,
|
|
.saddr = saddr,
|
|
.tos = RT_TOS(tos)
|
|
}
|
|
},
|
|
.proto = IPPROTO_ICMP,
|
|
.uli_u = {
|
|
.icmpt = {
|
|
.type = type,
|
|
.code = code
|
|
}
|
|
}
|
|
};
|
|
int err;
|
|
struct rtable *rt2;
|
|
|
|
security_skb_classify_flow(skb_in, &fl);
|
|
if (__ip_route_output_key(net, &rt, &fl))
|
|
goto out_unlock;
|
|
|
|
/* No need to clone since we're just using its address. */
|
|
rt2 = rt;
|
|
|
|
err = xfrm_lookup(net, (struct dst_entry **)&rt, &fl, NULL, 0);
|
|
switch (err) {
|
|
case 0:
|
|
if (rt != rt2)
|
|
goto route_done;
|
|
break;
|
|
case -EPERM:
|
|
rt = NULL;
|
|
break;
|
|
default:
|
|
goto out_unlock;
|
|
}
|
|
|
|
if (xfrm_decode_session_reverse(skb_in, &fl, AF_INET))
|
|
goto relookup_failed;
|
|
|
|
if (inet_addr_type(net, fl.fl4_src) == RTN_LOCAL)
|
|
err = __ip_route_output_key(net, &rt2, &fl);
|
|
else {
|
|
struct flowi fl2 = {};
|
|
unsigned long orefdst;
|
|
|
|
fl2.fl4_dst = fl.fl4_src;
|
|
if (ip_route_output_key(net, &rt2, &fl2))
|
|
goto relookup_failed;
|
|
|
|
/* Ugh! */
|
|
orefdst = skb_in->_skb_refdst; /* save old refdst */
|
|
err = ip_route_input(skb_in, fl.fl4_dst, fl.fl4_src,
|
|
RT_TOS(tos), rt2->u.dst.dev);
|
|
|
|
dst_release(&rt2->u.dst);
|
|
rt2 = skb_rtable(skb_in);
|
|
skb_in->_skb_refdst = orefdst; /* restore old refdst */
|
|
}
|
|
|
|
if (err)
|
|
goto relookup_failed;
|
|
|
|
err = xfrm_lookup(net, (struct dst_entry **)&rt2, &fl, NULL,
|
|
XFRM_LOOKUP_ICMP);
|
|
switch (err) {
|
|
case 0:
|
|
dst_release(&rt->u.dst);
|
|
rt = rt2;
|
|
break;
|
|
case -EPERM:
|
|
goto ende;
|
|
default:
|
|
relookup_failed:
|
|
if (!rt)
|
|
goto out_unlock;
|
|
break;
|
|
}
|
|
}
|
|
|
|
route_done:
|
|
if (!icmpv4_xrlim_allow(net, rt, type, code))
|
|
goto ende;
|
|
|
|
/* RFC says return as much as we can without exceeding 576 bytes. */
|
|
|
|
room = dst_mtu(&rt->u.dst);
|
|
if (room > 576)
|
|
room = 576;
|
|
room -= sizeof(struct iphdr) + icmp_param.replyopts.optlen;
|
|
room -= sizeof(struct icmphdr);
|
|
|
|
icmp_param.data_len = skb_in->len - icmp_param.offset;
|
|
if (icmp_param.data_len > room)
|
|
icmp_param.data_len = room;
|
|
icmp_param.head_len = sizeof(struct icmphdr);
|
|
|
|
icmp_push_reply(&icmp_param, &ipc, &rt);
|
|
ende:
|
|
ip_rt_put(rt);
|
|
out_unlock:
|
|
icmp_xmit_unlock(sk);
|
|
out:;
|
|
}
|
|
|
|
|
|
/*
|
|
* Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEED, and ICMP_QUENCH.
|
|
*/
|
|
|
|
static void icmp_unreach(struct sk_buff *skb)
|
|
{
|
|
struct iphdr *iph;
|
|
struct icmphdr *icmph;
|
|
int hash, protocol;
|
|
const struct net_protocol *ipprot;
|
|
u32 info = 0;
|
|
struct net *net;
|
|
|
|
net = dev_net(skb_dst(skb)->dev);
|
|
|
|
/*
|
|
* Incomplete header ?
|
|
* Only checks for the IP header, there should be an
|
|
* additional check for longer headers in upper levels.
|
|
*/
|
|
|
|
if (!pskb_may_pull(skb, sizeof(struct iphdr)))
|
|
goto out_err;
|
|
|
|
icmph = icmp_hdr(skb);
|
|
iph = (struct iphdr *)skb->data;
|
|
|
|
if (iph->ihl < 5) /* Mangled header, drop. */
|
|
goto out_err;
|
|
|
|
if (icmph->type == ICMP_DEST_UNREACH) {
|
|
switch (icmph->code & 15) {
|
|
case ICMP_NET_UNREACH:
|
|
case ICMP_HOST_UNREACH:
|
|
case ICMP_PROT_UNREACH:
|
|
case ICMP_PORT_UNREACH:
|
|
break;
|
|
case ICMP_FRAG_NEEDED:
|
|
if (ipv4_config.no_pmtu_disc) {
|
|
LIMIT_NETDEBUG(KERN_INFO "ICMP: %pI4: fragmentation needed and DF set.\n",
|
|
&iph->daddr);
|
|
} else {
|
|
info = ip_rt_frag_needed(net, iph,
|
|
ntohs(icmph->un.frag.mtu),
|
|
skb->dev);
|
|
if (!info)
|
|
goto out;
|
|
}
|
|
break;
|
|
case ICMP_SR_FAILED:
|
|
LIMIT_NETDEBUG(KERN_INFO "ICMP: %pI4: Source Route Failed.\n",
|
|
&iph->daddr);
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
if (icmph->code > NR_ICMP_UNREACH)
|
|
goto out;
|
|
} else if (icmph->type == ICMP_PARAMETERPROB)
|
|
info = ntohl(icmph->un.gateway) >> 24;
|
|
|
|
/*
|
|
* Throw it at our lower layers
|
|
*
|
|
* RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
|
|
* header.
|
|
* RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
|
|
* transport layer.
|
|
* RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
|
|
* transport layer.
|
|
*/
|
|
|
|
/*
|
|
* Check the other end isnt violating RFC 1122. Some routers send
|
|
* bogus responses to broadcast frames. If you see this message
|
|
* first check your netmask matches at both ends, if it does then
|
|
* get the other vendor to fix their kit.
|
|
*/
|
|
|
|
if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses &&
|
|
inet_addr_type(net, iph->daddr) == RTN_BROADCAST) {
|
|
if (net_ratelimit())
|
|
printk(KERN_WARNING "%pI4 sent an invalid ICMP "
|
|
"type %u, code %u "
|
|
"error to a broadcast: %pI4 on %s\n",
|
|
&ip_hdr(skb)->saddr,
|
|
icmph->type, icmph->code,
|
|
&iph->daddr,
|
|
skb->dev->name);
|
|
goto out;
|
|
}
|
|
|
|
/* Checkin full IP header plus 8 bytes of protocol to
|
|
* avoid additional coding at protocol handlers.
|
|
*/
|
|
if (!pskb_may_pull(skb, iph->ihl * 4 + 8))
|
|
goto out;
|
|
|
|
iph = (struct iphdr *)skb->data;
|
|
protocol = iph->protocol;
|
|
|
|
/*
|
|
* Deliver ICMP message to raw sockets. Pretty useless feature?
|
|
*/
|
|
raw_icmp_error(skb, protocol, info);
|
|
|
|
hash = protocol & (MAX_INET_PROTOS - 1);
|
|
rcu_read_lock();
|
|
ipprot = rcu_dereference(inet_protos[hash]);
|
|
if (ipprot && ipprot->err_handler)
|
|
ipprot->err_handler(skb, info);
|
|
rcu_read_unlock();
|
|
|
|
out:
|
|
return;
|
|
out_err:
|
|
ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
|
|
goto out;
|
|
}
|
|
|
|
|
|
/*
|
|
* Handle ICMP_REDIRECT.
|
|
*/
|
|
|
|
static void icmp_redirect(struct sk_buff *skb)
|
|
{
|
|
struct iphdr *iph;
|
|
|
|
if (skb->len < sizeof(struct iphdr))
|
|
goto out_err;
|
|
|
|
/*
|
|
* Get the copied header of the packet that caused the redirect
|
|
*/
|
|
if (!pskb_may_pull(skb, sizeof(struct iphdr)))
|
|
goto out;
|
|
|
|
iph = (struct iphdr *)skb->data;
|
|
|
|
switch (icmp_hdr(skb)->code & 7) {
|
|
case ICMP_REDIR_NET:
|
|
case ICMP_REDIR_NETTOS:
|
|
/*
|
|
* As per RFC recommendations now handle it as a host redirect.
|
|
*/
|
|
case ICMP_REDIR_HOST:
|
|
case ICMP_REDIR_HOSTTOS:
|
|
ip_rt_redirect(ip_hdr(skb)->saddr, iph->daddr,
|
|
icmp_hdr(skb)->un.gateway,
|
|
iph->saddr, skb->dev);
|
|
break;
|
|
}
|
|
out:
|
|
return;
|
|
out_err:
|
|
ICMP_INC_STATS_BH(dev_net(skb->dev), ICMP_MIB_INERRORS);
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* Handle ICMP_ECHO ("ping") requests.
|
|
*
|
|
* RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
|
|
* requests.
|
|
* RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
|
|
* included in the reply.
|
|
* RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
|
|
* echo requests, MUST have default=NOT.
|
|
* See also WRT handling of options once they are done and working.
|
|
*/
|
|
|
|
static void icmp_echo(struct sk_buff *skb)
|
|
{
|
|
struct net *net;
|
|
|
|
net = dev_net(skb_dst(skb)->dev);
|
|
if (!net->ipv4.sysctl_icmp_echo_ignore_all) {
|
|
struct icmp_bxm icmp_param;
|
|
|
|
icmp_param.data.icmph = *icmp_hdr(skb);
|
|
icmp_param.data.icmph.type = ICMP_ECHOREPLY;
|
|
icmp_param.skb = skb;
|
|
icmp_param.offset = 0;
|
|
icmp_param.data_len = skb->len;
|
|
icmp_param.head_len = sizeof(struct icmphdr);
|
|
icmp_reply(&icmp_param, skb);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Handle ICMP Timestamp requests.
|
|
* RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
|
|
* SHOULD be in the kernel for minimum random latency.
|
|
* MUST be accurate to a few minutes.
|
|
* MUST be updated at least at 15Hz.
|
|
*/
|
|
static void icmp_timestamp(struct sk_buff *skb)
|
|
{
|
|
struct timespec tv;
|
|
struct icmp_bxm icmp_param;
|
|
/*
|
|
* Too short.
|
|
*/
|
|
if (skb->len < 4)
|
|
goto out_err;
|
|
|
|
/*
|
|
* Fill in the current time as ms since midnight UT:
|
|
*/
|
|
getnstimeofday(&tv);
|
|
icmp_param.data.times[1] = htonl((tv.tv_sec % 86400) * MSEC_PER_SEC +
|
|
tv.tv_nsec / NSEC_PER_MSEC);
|
|
icmp_param.data.times[2] = icmp_param.data.times[1];
|
|
if (skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4))
|
|
BUG();
|
|
icmp_param.data.icmph = *icmp_hdr(skb);
|
|
icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
|
|
icmp_param.data.icmph.code = 0;
|
|
icmp_param.skb = skb;
|
|
icmp_param.offset = 0;
|
|
icmp_param.data_len = 0;
|
|
icmp_param.head_len = sizeof(struct icmphdr) + 12;
|
|
icmp_reply(&icmp_param, skb);
|
|
out:
|
|
return;
|
|
out_err:
|
|
ICMP_INC_STATS_BH(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
|
|
goto out;
|
|
}
|
|
|
|
|
|
/*
|
|
* Handle ICMP_ADDRESS_MASK requests. (RFC950)
|
|
*
|
|
* RFC1122 (3.2.2.9). A host MUST only send replies to
|
|
* ADDRESS_MASK requests if it's been configured as an address mask
|
|
* agent. Receiving a request doesn't constitute implicit permission to
|
|
* act as one. Of course, implementing this correctly requires (SHOULD)
|
|
* a way to turn the functionality on and off. Another one for sysctl(),
|
|
* I guess. -- MS
|
|
*
|
|
* RFC1812 (4.3.3.9). A router MUST implement it.
|
|
* A router SHOULD have switch turning it on/off.
|
|
* This switch MUST be ON by default.
|
|
*
|
|
* Gratuitous replies, zero-source replies are not implemented,
|
|
* that complies with RFC. DO NOT implement them!!! All the idea
|
|
* of broadcast addrmask replies as specified in RFC950 is broken.
|
|
* The problem is that it is not uncommon to have several prefixes
|
|
* on one physical interface. Moreover, addrmask agent can even be
|
|
* not aware of existing another prefixes.
|
|
* If source is zero, addrmask agent cannot choose correct prefix.
|
|
* Gratuitous mask announcements suffer from the same problem.
|
|
* RFC1812 explains it, but still allows to use ADDRMASK,
|
|
* that is pretty silly. --ANK
|
|
*
|
|
* All these rules are so bizarre, that I removed kernel addrmask
|
|
* support at all. It is wrong, it is obsolete, nobody uses it in
|
|
* any case. --ANK
|
|
*
|
|
* Furthermore you can do it with a usermode address agent program
|
|
* anyway...
|
|
*/
|
|
|
|
static void icmp_address(struct sk_buff *skb)
|
|
{
|
|
#if 0
|
|
if (net_ratelimit())
|
|
printk(KERN_DEBUG "a guy asks for address mask. Who is it?\n");
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* RFC1812 (4.3.3.9). A router SHOULD listen all replies, and complain
|
|
* loudly if an inconsistency is found.
|
|
*/
|
|
|
|
static void icmp_address_reply(struct sk_buff *skb)
|
|
{
|
|
struct rtable *rt = skb_rtable(skb);
|
|
struct net_device *dev = skb->dev;
|
|
struct in_device *in_dev;
|
|
struct in_ifaddr *ifa;
|
|
|
|
if (skb->len < 4 || !(rt->rt_flags&RTCF_DIRECTSRC))
|
|
goto out;
|
|
|
|
in_dev = in_dev_get(dev);
|
|
if (!in_dev)
|
|
goto out;
|
|
rcu_read_lock();
|
|
if (in_dev->ifa_list &&
|
|
IN_DEV_LOG_MARTIANS(in_dev) &&
|
|
IN_DEV_FORWARD(in_dev)) {
|
|
__be32 _mask, *mp;
|
|
|
|
mp = skb_header_pointer(skb, 0, sizeof(_mask), &_mask);
|
|
BUG_ON(mp == NULL);
|
|
for (ifa = in_dev->ifa_list; ifa; ifa = ifa->ifa_next) {
|
|
if (*mp == ifa->ifa_mask &&
|
|
inet_ifa_match(rt->rt_src, ifa))
|
|
break;
|
|
}
|
|
if (!ifa && net_ratelimit()) {
|
|
printk(KERN_INFO "Wrong address mask %pI4 from %s/%pI4\n",
|
|
mp, dev->name, &rt->rt_src);
|
|
}
|
|
}
|
|
rcu_read_unlock();
|
|
in_dev_put(in_dev);
|
|
out:;
|
|
}
|
|
|
|
static void icmp_discard(struct sk_buff *skb)
|
|
{
|
|
}
|
|
|
|
/*
|
|
* Deal with incoming ICMP packets.
|
|
*/
|
|
int icmp_rcv(struct sk_buff *skb)
|
|
{
|
|
struct icmphdr *icmph;
|
|
struct rtable *rt = skb_rtable(skb);
|
|
struct net *net = dev_net(rt->u.dst.dev);
|
|
|
|
if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
|
|
struct sec_path *sp = skb_sec_path(skb);
|
|
int nh;
|
|
|
|
if (!(sp && sp->xvec[sp->len - 1]->props.flags &
|
|
XFRM_STATE_ICMP))
|
|
goto drop;
|
|
|
|
if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr)))
|
|
goto drop;
|
|
|
|
nh = skb_network_offset(skb);
|
|
skb_set_network_header(skb, sizeof(*icmph));
|
|
|
|
if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb))
|
|
goto drop;
|
|
|
|
skb_set_network_header(skb, nh);
|
|
}
|
|
|
|
ICMP_INC_STATS_BH(net, ICMP_MIB_INMSGS);
|
|
|
|
switch (skb->ip_summed) {
|
|
case CHECKSUM_COMPLETE:
|
|
if (!csum_fold(skb->csum))
|
|
break;
|
|
/* fall through */
|
|
case CHECKSUM_NONE:
|
|
skb->csum = 0;
|
|
if (__skb_checksum_complete(skb))
|
|
goto error;
|
|
}
|
|
|
|
if (!pskb_pull(skb, sizeof(*icmph)))
|
|
goto error;
|
|
|
|
icmph = icmp_hdr(skb);
|
|
|
|
ICMPMSGIN_INC_STATS_BH(net, icmph->type);
|
|
/*
|
|
* 18 is the highest 'known' ICMP type. Anything else is a mystery
|
|
*
|
|
* RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
|
|
* discarded.
|
|
*/
|
|
if (icmph->type > NR_ICMP_TYPES)
|
|
goto error;
|
|
|
|
|
|
/*
|
|
* Parse the ICMP message
|
|
*/
|
|
|
|
if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
|
|
/*
|
|
* RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
|
|
* silently ignored (we let user decide with a sysctl).
|
|
* RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
|
|
* discarded if to broadcast/multicast.
|
|
*/
|
|
if ((icmph->type == ICMP_ECHO ||
|
|
icmph->type == ICMP_TIMESTAMP) &&
|
|
net->ipv4.sysctl_icmp_echo_ignore_broadcasts) {
|
|
goto error;
|
|
}
|
|
if (icmph->type != ICMP_ECHO &&
|
|
icmph->type != ICMP_TIMESTAMP &&
|
|
icmph->type != ICMP_ADDRESS &&
|
|
icmph->type != ICMP_ADDRESSREPLY) {
|
|
goto error;
|
|
}
|
|
}
|
|
|
|
icmp_pointers[icmph->type].handler(skb);
|
|
|
|
drop:
|
|
kfree_skb(skb);
|
|
return 0;
|
|
error:
|
|
ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
|
|
goto drop;
|
|
}
|
|
|
|
/*
|
|
* This table is the definition of how we handle ICMP.
|
|
*/
|
|
static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
|
|
[ICMP_ECHOREPLY] = {
|
|
.handler = icmp_discard,
|
|
},
|
|
[1] = {
|
|
.handler = icmp_discard,
|
|
.error = 1,
|
|
},
|
|
[2] = {
|
|
.handler = icmp_discard,
|
|
.error = 1,
|
|
},
|
|
[ICMP_DEST_UNREACH] = {
|
|
.handler = icmp_unreach,
|
|
.error = 1,
|
|
},
|
|
[ICMP_SOURCE_QUENCH] = {
|
|
.handler = icmp_unreach,
|
|
.error = 1,
|
|
},
|
|
[ICMP_REDIRECT] = {
|
|
.handler = icmp_redirect,
|
|
.error = 1,
|
|
},
|
|
[6] = {
|
|
.handler = icmp_discard,
|
|
.error = 1,
|
|
},
|
|
[7] = {
|
|
.handler = icmp_discard,
|
|
.error = 1,
|
|
},
|
|
[ICMP_ECHO] = {
|
|
.handler = icmp_echo,
|
|
},
|
|
[9] = {
|
|
.handler = icmp_discard,
|
|
.error = 1,
|
|
},
|
|
[10] = {
|
|
.handler = icmp_discard,
|
|
.error = 1,
|
|
},
|
|
[ICMP_TIME_EXCEEDED] = {
|
|
.handler = icmp_unreach,
|
|
.error = 1,
|
|
},
|
|
[ICMP_PARAMETERPROB] = {
|
|
.handler = icmp_unreach,
|
|
.error = 1,
|
|
},
|
|
[ICMP_TIMESTAMP] = {
|
|
.handler = icmp_timestamp,
|
|
},
|
|
[ICMP_TIMESTAMPREPLY] = {
|
|
.handler = icmp_discard,
|
|
},
|
|
[ICMP_INFO_REQUEST] = {
|
|
.handler = icmp_discard,
|
|
},
|
|
[ICMP_INFO_REPLY] = {
|
|
.handler = icmp_discard,
|
|
},
|
|
[ICMP_ADDRESS] = {
|
|
.handler = icmp_address,
|
|
},
|
|
[ICMP_ADDRESSREPLY] = {
|
|
.handler = icmp_address_reply,
|
|
},
|
|
};
|
|
|
|
static void __net_exit icmp_sk_exit(struct net *net)
|
|
{
|
|
int i;
|
|
|
|
for_each_possible_cpu(i)
|
|
inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]);
|
|
kfree(net->ipv4.icmp_sk);
|
|
net->ipv4.icmp_sk = NULL;
|
|
}
|
|
|
|
static int __net_init icmp_sk_init(struct net *net)
|
|
{
|
|
int i, err;
|
|
|
|
net->ipv4.icmp_sk =
|
|
kzalloc(nr_cpu_ids * sizeof(struct sock *), GFP_KERNEL);
|
|
if (net->ipv4.icmp_sk == NULL)
|
|
return -ENOMEM;
|
|
|
|
for_each_possible_cpu(i) {
|
|
struct sock *sk;
|
|
|
|
err = inet_ctl_sock_create(&sk, PF_INET,
|
|
SOCK_RAW, IPPROTO_ICMP, net);
|
|
if (err < 0)
|
|
goto fail;
|
|
|
|
net->ipv4.icmp_sk[i] = sk;
|
|
|
|
/* Enough space for 2 64K ICMP packets, including
|
|
* sk_buff struct overhead.
|
|
*/
|
|
sk->sk_sndbuf =
|
|
(2 * ((64 * 1024) + sizeof(struct sk_buff)));
|
|
|
|
/*
|
|
* Speedup sock_wfree()
|
|
*/
|
|
sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
|
|
inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT;
|
|
}
|
|
|
|
/* Control parameters for ECHO replies. */
|
|
net->ipv4.sysctl_icmp_echo_ignore_all = 0;
|
|
net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1;
|
|
|
|
/* Control parameter - ignore bogus broadcast responses? */
|
|
net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1;
|
|
|
|
/*
|
|
* Configurable global rate limit.
|
|
*
|
|
* ratelimit defines tokens/packet consumed for dst->rate_token
|
|
* bucket ratemask defines which icmp types are ratelimited by
|
|
* setting it's bit position.
|
|
*
|
|
* default:
|
|
* dest unreachable (3), source quench (4),
|
|
* time exceeded (11), parameter problem (12)
|
|
*/
|
|
|
|
net->ipv4.sysctl_icmp_ratelimit = 1 * HZ;
|
|
net->ipv4.sysctl_icmp_ratemask = 0x1818;
|
|
net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0;
|
|
|
|
return 0;
|
|
|
|
fail:
|
|
for_each_possible_cpu(i)
|
|
inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]);
|
|
kfree(net->ipv4.icmp_sk);
|
|
return err;
|
|
}
|
|
|
|
static struct pernet_operations __net_initdata icmp_sk_ops = {
|
|
.init = icmp_sk_init,
|
|
.exit = icmp_sk_exit,
|
|
};
|
|
|
|
int __init icmp_init(void)
|
|
{
|
|
return register_pernet_subsys(&icmp_sk_ops);
|
|
}
|
|
|
|
EXPORT_SYMBOL(icmp_err_convert);
|
|
EXPORT_SYMBOL(icmp_send);
|
|
EXPORT_SYMBOL(xrlim_allow);
|