summaryrefslogtreecommitdiff
path: root/net/sunrpc/auth_gss/gss_krb5_unseal.c
blob: db055fd7d7789c22ef62e4e8faab7ebac7cafebd (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
/*
 *  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;
	struct xdr_netobj	md5cksum = {.len = 0, .data = NULL};
	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:
	kfree(md5cksum.data);
	return ret;
}