/*
* linux/net/sunrpc/gss_krb5_unseal.c
*
* Adapted from MIT Kerberos 5-1.2.1 lib/gssapi/krb5/k5unseal.c
*
* Copyright (c) 2000 The Regents of the University of Michigan.
* All rights reserved.
*
* Andy Adamson <andros@umich.edu>
*/
/*
* Copyright 1993 by OpenVision Technologies, Inc.
*
* Permission to use, copy, modify, distribute, and sell this software
* and its documentation for any purpose is hereby granted without fee,
* provided that the above copyright notice appears in all copies and
* that both that copyright notice and this permission notice appear in
* supporting documentation, and that the name of OpenVision not be used
* in advertising or publicity pertaining to distribution of the software
* without specific, written prior permission. OpenVision makes no
* representations about the suitability of this software for any
* purpose. It is provided "as is" without express or implied warranty.
*
* OPENVISION DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
* EVENT SHALL OPENVISION BE LIABLE FOR ANY SPECIAL, INDIRECT OR
* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
* USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
* OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
* PERFORMANCE OF THIS SOFTWARE.
*/
/*
* Copyright (C) 1998 by the FundsXpress, INC.
*
* All rights reserved.
*
* Export of this software from the United States of America may require
* a specific license from the United States Government. It is the
* responsibility of any person or organization contemplating export to
* obtain such a license before exporting.
*
* WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
* distribute this software and its documentation for any purpose and
* without fee is hereby granted, provided that the above copyright
* notice appear in all copies and that both that copyright notice and
* this permission notice appear in supporting documentation, and that
* the name of FundsXpress. not be used in advertising or publicity pertaining
* to distribution of the software without specific, written prior
* permission. FundsXpress makes no representations about the suitability of
* this software for any purpose. It is provided "as is" without express
* or implied warranty.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/jiffies.h>
#include <linux/sunrpc/gss_krb5.h>
#include <linux/crypto.h>
#ifdef RPC_DEBUG
# define RPCDBG_FACILITY RPCDBG_AUTH
#endif
/* read_token is a mic token, and message_buffer is the data that the mic was
* supposedly taken over. */
u32
gss_verify_mic_kerberos(struct gss_ctx *gss_ctx,
struct xdr_buf *message_buffer, struct xdr_netobj *read_token)
{
struct krb5_ctx *ctx = gss_ctx->internal_ctx_id;
int signalg;
int sealalg;
s32 checksum_type;
char cksumdata[16];
struct xdr_netobj md5cksum = {.len = 0, .data = cksumdata};
s32 now;
int direction;
s32 seqnum;
unsigned char *ptr = (unsigned char *)read_token->data;
int bodysize;
u32 ret = GSS_S_DEFECTIVE_TOKEN;
dprintk("RPC: krb5_read_token\n");
if (g_verify_token_header(&ctx->mech_used, &bodysize, &ptr,
read_token->len))
goto out;
if ((*ptr++ != ((KG_TOK_MIC_MSG>>8)&0xff)) ||
(*ptr++ != ( KG_TOK_MIC_MSG &0xff)) )
goto out;
/* XXX sanity-check bodysize?? */
/* get the sign and seal algorithms */
signalg = ptr[0] + (ptr[1] << 8);
sealalg = ptr[2] + (ptr[3] << 8);
/* Sanity checks */
if ((ptr[4] != 0xff) || (ptr[5] != 0xff))
goto out;
if (sealalg != 0xffff)
goto out;
/* there are several mappings of seal algorithms to sign algorithms,
but few enough that we can try them all. */
if ((ctx->sealalg == SEAL_ALG_NONE && signalg > 1) ||
(ctx->sealalg == SEAL_ALG_1 && signalg != SGN_ALG_3) ||
(ctx->sealalg == SEAL_ALG_DES3KD &&
signalg != SGN_ALG_HMAC_SHA1_DES3_KD))
goto out;
/* compute the checksum of the message */
/* initialize the the cksum */
switch (signalg) {
case SGN_ALG_DES_MAC_MD5:
checksum_type = CKSUMTYPE_RSA_MD5;
break;
default:
ret = GSS_S_DEFECTIVE_TOKEN;
goto out;
}
switch (signalg) {
case SGN_ALG_DES_MAC_MD5:
ret = make_checksum(checksum_type, ptr - 2, 8,
message_buffer, 0, &md5cksum);
if (ret)
goto out;
ret = krb5_encrypt(ctx->seq, NULL, md5cksum.data,
md5cksum.data, 16);
if (ret)
goto out;
if (memcmp(md5cksum.data + 8, ptr + 14, 8)) {
ret = GSS_S_BAD_SIG;
goto out;
}
break;
default:
ret = GSS_S_DEFECTIVE_TOKEN;
goto out;
}
/* it got through unscathed. Make sure the context is unexpired */
now = get_seconds();
ret = GSS_S_CONTEXT_EXPIRED;
if (now > ctx->endtime)
goto out;
/* do sequencing checks */
ret = GSS_S_BAD_SIG;
if ((ret = krb5_get_seq_num(ctx->seq, ptr + 14, ptr + 6, &direction,
&seqnum)))
goto out;
if ((ctx->initiate && direction != 0xff) ||
(!ctx->initiate && direction != 0))
goto out;
ret = GSS_S_COMPLETE;
out:
return ret;
}
