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 u32
gss_krb5_verify_mic_v2(struct krb5_ctx * ctx,struct xdr_buf * message_buffer,struct xdr_netobj * read_token)73 gss_krb5_verify_mic_v2(struct krb5_ctx *ctx, struct xdr_buf *message_buffer,
74 struct xdr_netobj *read_token)
75 {
76 struct crypto_ahash *tfm = ctx->initiate ?
77 ctx->acceptor_sign : ctx->initiator_sign;
78 char cksumdata[GSS_KRB5_MAX_CKSUM_LEN];
79 struct xdr_netobj cksumobj = {
80 .len = ctx->gk5e->cksumlength,
81 .data = cksumdata,
82 };
83 u8 *ptr = read_token->data;
84 __be16 be16_ptr;
85 time64_t now;
86 u8 flags;
87 int i;
88
89 dprintk("RPC: %s\n", __func__);
90
91 memcpy(&be16_ptr, (char *) ptr, 2);
92 if (be16_to_cpu(be16_ptr) != KG2_TOK_MIC)
93 return GSS_S_DEFECTIVE_TOKEN;
94
95 flags = ptr[2];
96 if ((!ctx->initiate && (flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR)) ||
97 (ctx->initiate && !(flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR)))
98 return GSS_S_BAD_SIG;
99
100 if (flags & KG2_TOKEN_FLAG_SEALED) {
101 dprintk("%s: token has unexpected sealed flag\n", __func__);
102 return GSS_S_FAILURE;
103 }
104
105 for (i = 3; i < 8; i++)
106 if (ptr[i] != 0xff)
107 return GSS_S_DEFECTIVE_TOKEN;
108
109 if (gss_krb5_checksum(tfm, ptr, GSS_KRB5_TOK_HDR_LEN,
110 message_buffer, 0, &cksumobj))
111 return GSS_S_FAILURE;
112
113 if (memcmp(cksumobj.data, ptr + GSS_KRB5_TOK_HDR_LEN,
114 ctx->gk5e->cksumlength))
115 return GSS_S_BAD_SIG;
116
117 /* it got through unscathed. Make sure the context is unexpired */
118 now = ktime_get_real_seconds();
119 if (now > ctx->endtime)
120 return GSS_S_CONTEXT_EXPIRED;
121
122 /*
123 * NOTE: the sequence number at ptr + 8 is skipped, rpcsec_gss
124 * doesn't want it checked; see page 6 of rfc 2203.
125 */
126
127 return GSS_S_COMPLETE;
128 }
129