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
64 #include "gss_krb5_internal.h"
65
66 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
67 # define RPCDBG_FACILITY RPCDBG_AUTH
68 #endif
69
70 u32
71 gss_krb5_verify_mic_v2(struct krb5_ctx *ctx, struct xdr_buf *message_buffer,
72 struct xdr_netobj *read_token)
73 {
74 struct crypto_ahash *tfm = ctx->initiate ?
75 ctx->acceptor_sign : ctx->initiator_sign;
76 char cksumdata[GSS_KRB5_MAX_CKSUM_LEN];
77 struct xdr_netobj cksumobj = {
78 .len = ctx->gk5e->cksumlength,
79 .data = cksumdata,
80 };
81 u8 *ptr = read_token->data;
82 __be16 be16_ptr;
83 time64_t now;
84 u8 flags;
85 int i;
86
87 dprintk("RPC: %s\n", __func__);
88
89 memcpy(&be16_ptr, (char *) ptr, 2);
90 if (be16_to_cpu(be16_ptr) != KG2_TOK_MIC)
91 return GSS_S_DEFECTIVE_TOKEN;
92
93 flags = ptr[2];
94 if ((!ctx->initiate && (flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR)) ||
95 (ctx->initiate && !(flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR)))
96 return GSS_S_BAD_SIG;
97
98 if (flags & KG2_TOKEN_FLAG_SEALED) {
99 dprintk("%s: token has unexpected sealed flag\n", __func__);
100 return GSS_S_FAILURE;
101 }
102
103 for (i = 3; i < 8; i++)
104 if (ptr[i] != 0xff)
105 return GSS_S_DEFECTIVE_TOKEN;
106
107 if (gss_krb5_checksum(tfm, ptr, GSS_KRB5_TOK_HDR_LEN,
108 message_buffer, 0, &cksumobj))
109 return GSS_S_FAILURE;
110
111 if (memcmp(cksumobj.data, ptr + GSS_KRB5_TOK_HDR_LEN,
112 ctx->gk5e->cksumlength))
113 return GSS_S_BAD_SIG;
114
115 /* it got through unscathed. Make sure the context is unexpired */
116 now = ktime_get_real_seconds();
117 if (now > ctx->endtime)
118 return GSS_S_CONTEXT_EXPIRED;
119
120 /*
121 * NOTE: the sequence number at ptr + 8 is skipped, rpcsec_gss
122 * doesn't want it checked; see page 6 of rfc 2203.
123 */
124
125 return GSS_S_COMPLETE;
126 }
127
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