1/*
2 *  linux/net/sunrpc/gss_krb5_unseal.c
3 *
4 *  Adapted from MIT Kerberos 5-1.2.1 lib/gssapi/krb5/k5unseal.c
5 *
6 *  Copyright (c) 2000-2008 The Regents of the University of Michigan.
7 *  All rights reserved.
8 *
9 *  Andy Adamson   <andros@umich.edu>
10 */
11
12/*
13 * Copyright 1993 by OpenVision Technologies, Inc.
14 *
15 * Permission to use, copy, modify, distribute, and sell this software
16 * and its documentation for any purpose is hereby granted without fee,
17 * provided that the above copyright notice appears in all copies and
18 * that both that copyright notice and this permission notice appear in
19 * supporting documentation, and that the name of OpenVision not be used
20 * in advertising or publicity pertaining to distribution of the software
21 * without specific, written prior permission. OpenVision makes no
22 * representations about the suitability of this software for any
23 * purpose.  It is provided "as is" without express or implied warranty.
24 *
25 * OPENVISION DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
26 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
27 * EVENT SHALL OPENVISION BE LIABLE FOR ANY SPECIAL, INDIRECT OR
28 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
29 * USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
30 * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
31 * PERFORMANCE OF THIS SOFTWARE.
32 */
33
34/*
35 * Copyright (C) 1998 by the FundsXpress, INC.
36 *
37 * All rights reserved.
38 *
39 * Export of this software from the United States of America may require
40 * a specific license from the United States Government.  It is the
41 * responsibility of any person or organization contemplating export to
42 * obtain such a license before exporting.
43 *
44 * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
45 * distribute this software and its documentation for any purpose and
46 * without fee is hereby granted, provided that the above copyright
47 * notice appear in all copies and that both that copyright notice and
48 * this permission notice appear in supporting documentation, and that
49 * the name of FundsXpress. not be used in advertising or publicity pertaining
50 * to distribution of the software without specific, written prior
51 * permission.  FundsXpress makes no representations about the suitability of
52 * this software for any purpose.  It is provided "as is" without express
53 * or implied warranty.
54 *
55 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
56 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
57 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
58 */
59
60#include <linux/types.h>
61#include <linux/jiffies.h>
62#include <linux/sunrpc/gss_krb5.h>
63#include <linux/crypto.h>
64
65#ifdef RPC_DEBUG
66# define RPCDBG_FACILITY        RPCDBG_AUTH
67#endif
68
69
70/* read_token is a mic token, and message_buffer is the data that the mic was
71 * supposedly taken over. */
72
73static u32
74gss_verify_mic_v1(struct krb5_ctx *ctx,
75		struct xdr_buf *message_buffer, struct xdr_netobj *read_token)
76{
77	int			signalg;
78	int			sealalg;
79	char			cksumdata[GSS_KRB5_MAX_CKSUM_LEN];
80	struct xdr_netobj	md5cksum = {.len = sizeof(cksumdata),
81					    .data = cksumdata};
82	s32			now;
83	int			direction;
84	u32			seqnum;
85	unsigned char		*ptr = (unsigned char *)read_token->data;
86	int			bodysize;
87	u8			*cksumkey;
88
89	dprintk("RPC:       krb5_read_token\n");
90
91	if (g_verify_token_header(&ctx->mech_used, &bodysize, &ptr,
92					read_token->len))
93		return GSS_S_DEFECTIVE_TOKEN;
94
95	if ((ptr[0] != ((KG_TOK_MIC_MSG >> 8) & 0xff)) ||
96	    (ptr[1] !=  (KG_TOK_MIC_MSG & 0xff)))
97		return GSS_S_DEFECTIVE_TOKEN;
98
99	/* XXX sanity-check bodysize?? */
100
101	signalg = ptr[2] + (ptr[3] << 8);
102	if (signalg != ctx->gk5e->signalg)
103		return GSS_S_DEFECTIVE_TOKEN;
104
105	sealalg = ptr[4] + (ptr[5] << 8);
106	if (sealalg != SEAL_ALG_NONE)
107		return GSS_S_DEFECTIVE_TOKEN;
108
109	if ((ptr[6] != 0xff) || (ptr[7] != 0xff))
110		return GSS_S_DEFECTIVE_TOKEN;
111
112	if (ctx->gk5e->keyed_cksum)
113		cksumkey = ctx->cksum;
114	else
115		cksumkey = NULL;
116
117	if (make_checksum(ctx, ptr, 8, message_buffer, 0,
118			  cksumkey, KG_USAGE_SIGN, &md5cksum))
119		return GSS_S_FAILURE;
120
121	if (memcmp(md5cksum.data, ptr + GSS_KRB5_TOK_HDR_LEN,
122					ctx->gk5e->cksumlength))
123		return GSS_S_BAD_SIG;
124
125	/* it got through unscathed.  Make sure the context is unexpired */
126
127	now = get_seconds();
128
129	if (now > ctx->endtime)
130		return GSS_S_CONTEXT_EXPIRED;
131
132	/* do sequencing checks */
133
134	if (krb5_get_seq_num(ctx, ptr + GSS_KRB5_TOK_HDR_LEN, ptr + 8,
135			     &direction, &seqnum))
136		return GSS_S_FAILURE;
137
138	if ((ctx->initiate && direction != 0xff) ||
139	    (!ctx->initiate && direction != 0))
140		return GSS_S_BAD_SIG;
141
142	return GSS_S_COMPLETE;
143}
144
145static u32
146gss_verify_mic_v2(struct krb5_ctx *ctx,
147		struct xdr_buf *message_buffer, struct xdr_netobj *read_token)
148{
149	char cksumdata[GSS_KRB5_MAX_CKSUM_LEN];
150	struct xdr_netobj cksumobj = {.len = sizeof(cksumdata),
151				      .data = cksumdata};
152	s32 now;
153	u8 *ptr = read_token->data;
154	u8 *cksumkey;
155	u8 flags;
156	int i;
157	unsigned int cksum_usage;
158
159	dprintk("RPC:       %s\n", __func__);
160
161	if (be16_to_cpu(*((__be16 *)ptr)) != KG2_TOK_MIC)
162		return GSS_S_DEFECTIVE_TOKEN;
163
164	flags = ptr[2];
165	if ((!ctx->initiate && (flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR)) ||
166	    (ctx->initiate && !(flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR)))
167		return GSS_S_BAD_SIG;
168
169	if (flags & KG2_TOKEN_FLAG_SEALED) {
170		dprintk("%s: token has unexpected sealed flag\n", __func__);
171		return GSS_S_FAILURE;
172	}
173
174	for (i = 3; i < 8; i++)
175		if (ptr[i] != 0xff)
176			return GSS_S_DEFECTIVE_TOKEN;
177
178	if (ctx->initiate) {
179		cksumkey = ctx->acceptor_sign;
180		cksum_usage = KG_USAGE_ACCEPTOR_SIGN;
181	} else {
182		cksumkey = ctx->initiator_sign;
183		cksum_usage = KG_USAGE_INITIATOR_SIGN;
184	}
185
186	if (make_checksum_v2(ctx, ptr, GSS_KRB5_TOK_HDR_LEN, message_buffer, 0,
187			     cksumkey, cksum_usage, &cksumobj))
188		return GSS_S_FAILURE;
189
190	if (memcmp(cksumobj.data, ptr + GSS_KRB5_TOK_HDR_LEN,
191				ctx->gk5e->cksumlength))
192		return GSS_S_BAD_SIG;
193
194	/* it got through unscathed.  Make sure the context is unexpired */
195	now = get_seconds();
196	if (now > ctx->endtime)
197		return GSS_S_CONTEXT_EXPIRED;
198
199	/*
200	 * NOTE: the sequence number at ptr + 8 is skipped, rpcsec_gss
201	 * doesn't want it checked; see page 6 of rfc 2203.
202	 */
203
204	return GSS_S_COMPLETE;
205}
206
207u32
208gss_verify_mic_kerberos(struct gss_ctx *gss_ctx,
209			struct xdr_buf *message_buffer,
210			struct xdr_netobj *read_token)
211{
212	struct krb5_ctx *ctx = gss_ctx->internal_ctx_id;
213
214	switch (ctx->enctype) {
215	default:
216		BUG();
217	case ENCTYPE_DES_CBC_RAW:
218	case ENCTYPE_DES3_CBC_RAW:
219	case ENCTYPE_ARCFOUR_HMAC:
220		return gss_verify_mic_v1(ctx, message_buffer, read_token);
221	case ENCTYPE_AES128_CTS_HMAC_SHA1_96:
222	case ENCTYPE_AES256_CTS_HMAC_SHA1_96:
223		return gss_verify_mic_v2(ctx, message_buffer, read_token);
224	}
225}
226
227