1 /*
2 * linux/net/sunrpc/gss_spkm3_unseal.c
3 *
4 * Copyright (c) 2003 The Regents of the University of Michigan.
5 * All rights reserved.
6 *
7 * Andy Adamson <andros@umich.edu>
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 *
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its
19 * contributors may be used to endorse or promote products derived
20 * from this software without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
23 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
24 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
25 * DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
27 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
28 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
29 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
30 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
31 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
32 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
33 *
34 */
35
36 #include <linux/types.h>
37 #include <linux/slab.h>
38 #include <linux/jiffies.h>
39 #include <linux/sunrpc/gss_spkm3.h>
40 #include <linux/crypto.h>
41
42 #ifdef RPC_DEBUG
43 # define RPCDBG_FACILITY RPCDBG_AUTH
44 #endif
45
46 /*
47 * spkm3_read_token()
48 *
49 * only SPKM_MIC_TOK with md5 intg-alg is supported
50 */
51 u32
spkm3_read_token(struct spkm3_ctx * ctx,struct xdr_netobj * read_token,struct xdr_buf * message_buffer,int toktype)52 spkm3_read_token(struct spkm3_ctx *ctx,
53 struct xdr_netobj *read_token, /* checksum */
54 struct xdr_buf *message_buffer, /* signbuf */
55 int toktype)
56 {
57 s32 checksum_type;
58 s32 code;
59 struct xdr_netobj wire_cksum = {.len =0, .data = NULL};
60 char cksumdata[16];
61 struct xdr_netobj md5cksum = {.len = 0, .data = cksumdata};
62 unsigned char *ptr = (unsigned char *)read_token->data;
63 unsigned char *cksum;
64 int bodysize, md5elen;
65 int mic_hdrlen;
66 u32 ret = GSS_S_DEFECTIVE_TOKEN;
67
68 if (g_verify_token_header((struct xdr_netobj *) &ctx->mech_used,
69 &bodysize, &ptr, read_token->len))
70 goto out;
71
72 /* decode the token */
73
74 if (toktype != SPKM_MIC_TOK) {
75 dprintk("RPC: BAD SPKM3 token type: %d\n", toktype);
76 goto out;
77 }
78
79 if ((ret = spkm3_verify_mic_token(&ptr, &mic_hdrlen, &cksum)))
80 goto out;
81
82 if (*cksum++ != 0x03) {
83 dprintk("RPC: spkm3_read_token BAD checksum type\n");
84 goto out;
85 }
86 md5elen = *cksum++;
87 cksum++; /* move past the zbit */
88
89 if (!decode_asn1_bitstring(&wire_cksum, cksum, md5elen - 1, 16))
90 goto out;
91
92 /* HARD CODED FOR MD5 */
93
94 /* compute the checksum of the message.
95 * ptr + 2 = start of header piece of checksum
96 * mic_hdrlen + 2 = length of header piece of checksum
97 */
98 ret = GSS_S_DEFECTIVE_TOKEN;
99 if (!g_OID_equal(&ctx->intg_alg, &hmac_md5_oid)) {
100 dprintk("RPC: gss_spkm3_seal: unsupported I-ALG "
101 "algorithm\n");
102 goto out;
103 }
104
105 checksum_type = CKSUMTYPE_HMAC_MD5;
106
107 code = make_spkm3_checksum(checksum_type,
108 &ctx->derived_integ_key, ptr + 2, mic_hdrlen + 2,
109 message_buffer, 0, &md5cksum);
110
111 if (code)
112 goto out;
113
114 ret = GSS_S_BAD_SIG;
115 code = memcmp(md5cksum.data, wire_cksum.data, wire_cksum.len);
116 if (code) {
117 dprintk("RPC: bad MIC checksum\n");
118 goto out;
119 }
120
121
122 /* XXX: need to add expiration and sequencing */
123 ret = GSS_S_COMPLETE;
124 out:
125 kfree(wire_cksum.data);
126 return ret;
127 }
128