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 <crypto/algapi.h>
61 #include <linux/types.h>
62 #include <linux/jiffies.h>
63 #include <linux/sunrpc/gss_krb5.h>
64 #include <linux/crypto.h>
65
66 #include "gss_krb5_internal.h"
67
68 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
69 # define RPCDBG_FACILITY RPCDBG_AUTH
70 #endif
71
72
73 #if defined(CONFIG_RPCSEC_GSS_KRB5_SIMPLIFIED)
74 /* read_token is a mic token, and message_buffer is the data that the mic was
75 * supposedly taken over. */
76 u32
gss_krb5_verify_mic_v1(struct krb5_ctx * ctx,struct xdr_buf * message_buffer,struct xdr_netobj * read_token)77 gss_krb5_verify_mic_v1(struct krb5_ctx *ctx, struct xdr_buf *message_buffer,
78 struct xdr_netobj *read_token)
79 {
80 int signalg;
81 int sealalg;
82 char cksumdata[GSS_KRB5_MAX_CKSUM_LEN];
83 struct xdr_netobj md5cksum = {.len = sizeof(cksumdata),
84 .data = cksumdata};
85 s32 now;
86 int direction;
87 u32 seqnum;
88 unsigned char *ptr = (unsigned char *)read_token->data;
89 int bodysize;
90 u8 *cksumkey;
91
92 dprintk("RPC: krb5_read_token\n");
93
94 if (g_verify_token_header(&ctx->mech_used, &bodysize, &ptr,
95 read_token->len))
96 return GSS_S_DEFECTIVE_TOKEN;
97
98 if ((ptr[0] != ((KG_TOK_MIC_MSG >> 8) & 0xff)) ||
99 (ptr[1] != (KG_TOK_MIC_MSG & 0xff)))
100 return GSS_S_DEFECTIVE_TOKEN;
101
102 /* XXX sanity-check bodysize?? */
103
104 signalg = ptr[2] + (ptr[3] << 8);
105 if (signalg != ctx->gk5e->signalg)
106 return GSS_S_DEFECTIVE_TOKEN;
107
108 sealalg = ptr[4] + (ptr[5] << 8);
109 if (sealalg != SEAL_ALG_NONE)
110 return GSS_S_DEFECTIVE_TOKEN;
111
112 if ((ptr[6] != 0xff) || (ptr[7] != 0xff))
113 return GSS_S_DEFECTIVE_TOKEN;
114
115 if (ctx->gk5e->keyed_cksum)
116 cksumkey = ctx->cksum;
117 else
118 cksumkey = NULL;
119
120 if (make_checksum(ctx, ptr, 8, message_buffer, 0,
121 cksumkey, KG_USAGE_SIGN, &md5cksum))
122 return GSS_S_FAILURE;
123
124 if (memcmp(md5cksum.data, ptr + GSS_KRB5_TOK_HDR_LEN,
125 ctx->gk5e->cksumlength))
126 return GSS_S_BAD_SIG;
127
128 /* it got through unscathed. Make sure the context is unexpired */
129
130 now = ktime_get_real_seconds();
131
132 if (now > ctx->endtime)
133 return GSS_S_CONTEXT_EXPIRED;
134
135 /* do sequencing checks */
136
137 if (krb5_get_seq_num(ctx, ptr + GSS_KRB5_TOK_HDR_LEN, ptr + 8,
138 &direction, &seqnum))
139 return GSS_S_FAILURE;
140
141 if ((ctx->initiate && direction != 0xff) ||
142 (!ctx->initiate && direction != 0))
143 return GSS_S_BAD_SIG;
144
145 return GSS_S_COMPLETE;
146 }
147 #endif
148
149 u32
gss_krb5_verify_mic_v2(struct krb5_ctx * ctx,struct xdr_buf * message_buffer,struct xdr_netobj * read_token)150 gss_krb5_verify_mic_v2(struct krb5_ctx *ctx, struct xdr_buf *message_buffer,
151 struct xdr_netobj *read_token)
152 {
153 struct crypto_ahash *tfm = ctx->initiate ?
154 ctx->acceptor_sign : ctx->initiator_sign;
155 char cksumdata[GSS_KRB5_MAX_CKSUM_LEN];
156 struct xdr_netobj cksumobj = {
157 .len = ctx->gk5e->cksumlength,
158 .data = cksumdata,
159 };
160 u8 *ptr = read_token->data;
161 __be16 be16_ptr;
162 time64_t now;
163 u8 flags;
164 int i;
165
166 dprintk("RPC: %s\n", __func__);
167
168 memcpy(&be16_ptr, (char *) ptr, 2);
169 if (be16_to_cpu(be16_ptr) != KG2_TOK_MIC)
170 return GSS_S_DEFECTIVE_TOKEN;
171
172 flags = ptr[2];
173 if ((!ctx->initiate && (flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR)) ||
174 (ctx->initiate && !(flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR)))
175 return GSS_S_BAD_SIG;
176
177 if (flags & KG2_TOKEN_FLAG_SEALED) {
178 dprintk("%s: token has unexpected sealed flag\n", __func__);
179 return GSS_S_FAILURE;
180 }
181
182 for (i = 3; i < 8; i++)
183 if (ptr[i] != 0xff)
184 return GSS_S_DEFECTIVE_TOKEN;
185
186 if (gss_krb5_checksum(tfm, ptr, GSS_KRB5_TOK_HDR_LEN,
187 message_buffer, 0, &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 = ktime_get_real_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