gss_krb5: import functionality to derive keys into the kernel
Import the code to derive Kerberos keys from a base key into the kernel. This will allow us to change the format of the context information sent down from gssd to include only a single key. Signed-off-by: Kevin Coffman <kwc@citi.umich.edu> Signed-off-by: Steve Dickson <steved@redhat.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This commit is contained in:
Kevin Coffman
Trond Myklebust
Родитель
e1f6c07b11
Коммит
4891f2d008
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@ -41,6 +41,9 @@
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#include <linux/sunrpc/gss_err.h>
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#include <linux/sunrpc/gss_asn1.h>
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/* Length of constant used in key derivation */
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#define GSS_KRB5_K5CLENGTH (5)
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/* Maximum key length (in bytes) for the supported crypto algorithms*/
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#define GSS_KRB5_MAX_KEYLEN (32)
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@ -69,6 +72,9 @@ struct gss_krb5_enctype {
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u32 (*decrypt) (struct crypto_blkcipher *tfm,
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void *iv, void *in, void *out,
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int length); /* decryption function */
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u32 (*mk_key) (struct gss_krb5_enctype *gk5e,
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struct xdr_netobj *in,
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struct xdr_netobj *out); /* complete key generation */
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};
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struct krb5_ctx {
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@ -147,6 +153,25 @@ enum seal_alg {
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#define ENCTYPE_DES3_CBC_SHA1 0x0010
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#define ENCTYPE_UNKNOWN 0x01ff
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/*
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* Constants used for key derivation
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*/
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/* for 3DES */
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#define KG_USAGE_SEAL (22)
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#define KG_USAGE_SIGN (23)
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#define KG_USAGE_SEQ (24)
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/* from rfc3961 */
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#define KEY_USAGE_SEED_CHECKSUM (0x99)
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#define KEY_USAGE_SEED_ENCRYPTION (0xAA)
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#define KEY_USAGE_SEED_INTEGRITY (0x55)
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/* from rfc4121 */
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#define KG_USAGE_ACCEPTOR_SEAL (22)
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#define KG_USAGE_ACCEPTOR_SIGN (23)
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#define KG_USAGE_INITIATOR_SEAL (24)
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#define KG_USAGE_INITIATOR_SIGN (25)
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/*
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* This compile-time check verifies that we will not exceed the
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* slack space allotted by the client and server auth_gss code
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@ -211,3 +236,9 @@ krb5_get_seq_num(struct crypto_blkcipher *key,
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int
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xdr_extend_head(struct xdr_buf *buf, unsigned int base, unsigned int shiftlen);
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u32
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krb5_derive_key(struct gss_krb5_enctype *gk5e,
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const struct xdr_netobj *inkey,
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struct xdr_netobj *outkey,
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const struct xdr_netobj *in_constant);
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@ -10,7 +10,7 @@ auth_rpcgss-objs := auth_gss.o gss_generic_token.o \
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obj-$(CONFIG_RPCSEC_GSS_KRB5) += rpcsec_gss_krb5.o
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rpcsec_gss_krb5-objs := gss_krb5_mech.o gss_krb5_seal.o gss_krb5_unseal.o \
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gss_krb5_seqnum.o gss_krb5_wrap.o gss_krb5_crypto.o
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gss_krb5_seqnum.o gss_krb5_wrap.o gss_krb5_crypto.o gss_krb5_keys.o
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obj-$(CONFIG_RPCSEC_GSS_SPKM3) += rpcsec_gss_spkm3.o
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@ -0,0 +1,252 @@
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/*
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* COPYRIGHT (c) 2008
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* The Regents of the University of Michigan
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* ALL RIGHTS RESERVED
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*
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* Permission is granted to use, copy, create derivative works
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* and redistribute this software and such derivative works
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* for any purpose, so long as the name of The University of
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* Michigan is not used in any advertising or publicity
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* pertaining to the use of distribution of this software
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* without specific, written prior authorization. If the
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* above copyright notice or any other identification of the
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* University of Michigan is included in any copy of any
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* portion of this software, then the disclaimer below must
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* also be included.
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*
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* THIS SOFTWARE IS PROVIDED AS IS, WITHOUT REPRESENTATION
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* FROM THE UNIVERSITY OF MICHIGAN AS TO ITS FITNESS FOR ANY
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* PURPOSE, AND WITHOUT WARRANTY BY THE UNIVERSITY OF
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* MICHIGAN OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING
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* WITHOUT LIMITATION THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE
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* REGENTS OF THE UNIVERSITY OF MICHIGAN SHALL NOT BE LIABLE
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* FOR ANY DAMAGES, INCLUDING SPECIAL, INDIRECT, INCIDENTAL, OR
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* CONSEQUENTIAL DAMAGES, WITH RESPECT TO ANY CLAIM ARISING
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* OUT OF OR IN CONNECTION WITH THE USE OF THE SOFTWARE, EVEN
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* IF IT HAS BEEN OR IS HEREAFTER ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGES.
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*/
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/*
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* Copyright (C) 1998 by the FundsXpress, INC.
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*
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* All rights reserved.
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*
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* Export of this software from the United States of America may require
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* a specific license from the United States Government. It is the
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* responsibility of any person or organization contemplating export to
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* obtain such a license before exporting.
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*
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* WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
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* distribute this software and its documentation for any purpose and
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* without fee is hereby granted, provided that the above copyright
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* notice appear in all copies and that both that copyright notice and
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* this permission notice appear in supporting documentation, and that
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* the name of FundsXpress. not be used in advertising or publicity pertaining
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* to distribution of the software without specific, written prior
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* permission. FundsXpress makes no representations about the suitability of
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* this software for any purpose. It is provided "as is" without express
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* or implied warranty.
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*
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
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* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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*/
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#include <linux/err.h>
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#include <linux/types.h>
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#include <linux/crypto.h>
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#include <linux/sunrpc/gss_krb5.h>
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#include <linux/sunrpc/xdr.h>
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#ifdef RPC_DEBUG
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# define RPCDBG_FACILITY RPCDBG_AUTH
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#endif
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/*
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* This is the n-fold function as described in rfc3961, sec 5.1
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* Taken from MIT Kerberos and modified.
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*/
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static void krb5_nfold(u32 inbits, const u8 *in,
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u32 outbits, u8 *out)
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{
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int a, b, c, lcm;
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int byte, i, msbit;
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/* the code below is more readable if I make these bytes
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instead of bits */
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inbits >>= 3;
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outbits >>= 3;
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/* first compute lcm(n,k) */
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a = outbits;
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b = inbits;
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while (b != 0) {
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c = b;
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b = a%b;
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a = c;
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}
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lcm = outbits*inbits/a;
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/* now do the real work */
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memset(out, 0, outbits);
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byte = 0;
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/* this will end up cycling through k lcm(k,n)/k times, which
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is correct */
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for (i = lcm-1; i >= 0; i--) {
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/* compute the msbit in k which gets added into this byte */
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msbit = (
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/* first, start with the msbit in the first,
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* unrotated byte */
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((inbits << 3) - 1)
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/* then, for each byte, shift to the right
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* for each repetition */
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+ (((inbits << 3) + 13) * (i/inbits))
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/* last, pick out the correct byte within
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* that shifted repetition */
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+ ((inbits - (i % inbits)) << 3)
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) % (inbits << 3);
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/* pull out the byte value itself */
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byte += (((in[((inbits - 1) - (msbit >> 3)) % inbits] << 8)|
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(in[((inbits) - (msbit >> 3)) % inbits]))
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>> ((msbit & 7) + 1)) & 0xff;
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/* do the addition */
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byte += out[i % outbits];
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out[i % outbits] = byte & 0xff;
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/* keep around the carry bit, if any */
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byte >>= 8;
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}
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/* if there's a carry bit left over, add it back in */
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if (byte) {
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for (i = outbits - 1; i >= 0; i--) {
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/* do the addition */
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byte += out[i];
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out[i] = byte & 0xff;
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/* keep around the carry bit, if any */
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byte >>= 8;
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}
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}
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}
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/*
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* This is the DK (derive_key) function as described in rfc3961, sec 5.1
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* Taken from MIT Kerberos and modified.
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*/
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u32 krb5_derive_key(struct gss_krb5_enctype *gk5e,
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const struct xdr_netobj *inkey,
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struct xdr_netobj *outkey,
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const struct xdr_netobj *in_constant)
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{
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size_t blocksize, keybytes, keylength, n;
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unsigned char *inblockdata, *outblockdata, *rawkey;
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struct xdr_netobj inblock, outblock;
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struct crypto_blkcipher *cipher;
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u32 ret = EINVAL;
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blocksize = gk5e->blocksize;
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keybytes = gk5e->keybytes;
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keylength = gk5e->keylength;
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if ((inkey->len != keylength) || (outkey->len != keylength))
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goto err_return;
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cipher = crypto_alloc_blkcipher(gk5e->encrypt_name, 0,
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CRYPTO_ALG_ASYNC);
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if (IS_ERR(cipher))
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goto err_return;
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if (crypto_blkcipher_setkey(cipher, inkey->data, inkey->len))
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goto err_return;
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/* allocate and set up buffers */
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ret = ENOMEM;
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inblockdata = kmalloc(blocksize, GFP_KERNEL);
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if (inblockdata == NULL)
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goto err_free_cipher;
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outblockdata = kmalloc(blocksize, GFP_KERNEL);
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if (outblockdata == NULL)
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goto err_free_in;
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rawkey = kmalloc(keybytes, GFP_KERNEL);
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if (rawkey == NULL)
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goto err_free_out;
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inblock.data = (char *) inblockdata;
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inblock.len = blocksize;
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outblock.data = (char *) outblockdata;
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outblock.len = blocksize;
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/* initialize the input block */
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if (in_constant->len == inblock.len) {
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memcpy(inblock.data, in_constant->data, inblock.len);
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} else {
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krb5_nfold(in_constant->len * 8, in_constant->data,
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inblock.len * 8, inblock.data);
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}
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/* loop encrypting the blocks until enough key bytes are generated */
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n = 0;
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while (n < keybytes) {
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(*(gk5e->encrypt))(cipher, NULL, inblock.data,
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outblock.data, inblock.len);
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if ((keybytes - n) <= outblock.len) {
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memcpy(rawkey + n, outblock.data, (keybytes - n));
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break;
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}
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memcpy(rawkey + n, outblock.data, outblock.len);
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memcpy(inblock.data, outblock.data, outblock.len);
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n += outblock.len;
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}
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/* postprocess the key */
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inblock.data = (char *) rawkey;
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inblock.len = keybytes;
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BUG_ON(gk5e->mk_key == NULL);
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ret = (*(gk5e->mk_key))(gk5e, &inblock, outkey);
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if (ret) {
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dprintk("%s: got %d from mk_key function for '%s'\n",
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__func__, ret, gk5e->encrypt_name);
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goto err_free_raw;
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}
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/* clean memory, free resources and exit */
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ret = 0;
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err_free_raw:
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memset(rawkey, 0, keybytes);
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kfree(rawkey);
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err_free_out:
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memset(outblockdata, 0, blocksize);
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kfree(outblockdata);
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err_free_in:
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memset(inblockdata, 0, blocksize);
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kfree(inblockdata);
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err_free_cipher:
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crypto_free_blkcipher(cipher);
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err_return:
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return ret;
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}
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@ -60,6 +60,7 @@ static const struct gss_krb5_enctype supported_gss_krb5_enctypes[] = {
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.cksum_name = "md5",
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.encrypt = krb5_encrypt,
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.decrypt = krb5_decrypt,
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.mk_key = NULL,
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.signalg = SGN_ALG_DES_MAC_MD5,
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.sealalg = SEAL_ALG_DES,
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.keybytes = 7,
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