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 #if IS_ENABLED(CONFIG_SUNRPC_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
73 static u32
74 gss_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
145 static u32
146 gss_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 __be16 be16_ptr;
159
160 dprintk("RPC: %s\n", __func__);
161
162 memcpy(&be16_ptr, (char *) ptr, 2);
163 if (be16_to_cpu(be16_ptr) != KG2_TOK_MIC)
164 return GSS_S_DEFECTIVE_TOKEN;
165
166 flags = ptr[2];
167 if ((!ctx->initiate && (flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR)) ||
168 (ctx->initiate && !(flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR)))
169 return GSS_S_BAD_SIG;
170
171 if (flags & KG2_TOKEN_FLAG_SEALED) {
172 dprintk("%s: token has unexpected sealed flag\n", __func__);
173 return GSS_S_FAILURE;
174 }
175
176 for (i = 3; i < 8; i++)
177 if (ptr[i] != 0xff)
178 return GSS_S_DEFECTIVE_TOKEN;
179
180 if (ctx->initiate) {
181 cksumkey = ctx->acceptor_sign;
182 cksum_usage = KG_USAGE_ACCEPTOR_SIGN;
183 } else {
184 cksumkey = ctx->initiator_sign;
185 cksum_usage = KG_USAGE_INITIATOR_SIGN;
186 }
187
188 if (make_checksum_v2(ctx, ptr, GSS_KRB5_TOK_HDR_LEN, message_buffer, 0,
189 cksumkey, cksum_usage, &cksumobj))
190 return GSS_S_FAILURE;
191
192 if (memcmp(cksumobj.data, ptr + GSS_KRB5_TOK_HDR_LEN,
193 ctx->gk5e->cksumlength))
194 return GSS_S_BAD_SIG;
195
196 /* it got through unscathed. Make sure the context is unexpired */
197 now = get_seconds();
198 if (now > ctx->endtime)
199 return GSS_S_CONTEXT_EXPIRED;
200
201 /*
202 * NOTE: the sequence number at ptr + 8 is skipped, rpcsec_gss
203 * doesn't want it checked; see page 6 of rfc 2203.
204 */
205
206 return GSS_S_COMPLETE;
207 }
208
209 u32
210 gss_verify_mic_kerberos(struct gss_ctx *gss_ctx,
211 struct xdr_buf *message_buffer,
212 struct xdr_netobj *read_token)
213 {
214 struct krb5_ctx *ctx = gss_ctx->internal_ctx_id;
215
216 switch (ctx->enctype) {
217 default:
218 BUG();
219 case ENCTYPE_DES_CBC_RAW:
220 case ENCTYPE_DES3_CBC_RAW:
221 case ENCTYPE_ARCFOUR_HMAC:
222 return gss_verify_mic_v1(ctx, message_buffer, read_token);
223 case ENCTYPE_AES128_CTS_HMAC_SHA1_96:
224 case ENCTYPE_AES256_CTS_HMAC_SHA1_96:
225 return gss_verify_mic_v2(ctx, message_buffer, read_token);
226 }
227 }