rd_safe.c revision 55682 
1/*
2 * Copyright (c) 1997 Kungliga Tekniska H�gskolan
3 * (Royal Institute of Technology, Stockholm, Sweden).
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 *
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 *
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 *
17 * 3. Neither the name of the Institute nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#include <krb5_locl.h>
35
36RCSID("$Id: rd_safe.c,v 1.18 1999/12/02 17:05:12 joda Exp $");
37
38static krb5_error_code
39verify_checksum(krb5_context context,
40		krb5_auth_context auth_context,
41		KRB_SAFE *safe)
42{
43    krb5_error_code ret;
44    u_char *buf;
45    size_t buf_size;
46    size_t len;
47    Checksum c;
48    krb5_crypto crypto;
49
50    c = safe->cksum;
51    safe->cksum.cksumtype       = 0;
52    safe->cksum.checksum.data   = NULL;
53    safe->cksum.checksum.length = 0;
54
55
56    buf_size = length_KRB_SAFE(safe);
57    buf = malloc(buf_size);
58
59    if (buf == NULL) {
60	ret = ENOMEM;
61	goto out;
62    }
63
64    ret = encode_KRB_SAFE (buf + buf_size - 1,
65			   buf_size,
66			   safe,
67			   &len);
68    krb5_crypto_init(context, auth_context->keyblock, 0, &crypto);
69    ret = krb5_verify_checksum (context,
70				crypto,
71				KRB5_KU_KRB_SAFE_CKSUM,
72				buf + buf_size - len,
73				len,
74				&c);
75    krb5_crypto_destroy(context, crypto);
76out:
77    safe->cksum = c;
78    free (buf);
79    return ret;
80}
81
82krb5_error_code
83krb5_rd_safe(krb5_context context,
84	     krb5_auth_context auth_context,
85	     const krb5_data *inbuf,
86	     krb5_data *outbuf,
87	     /*krb5_replay_data*/ void *outdata)
88{
89  krb5_error_code ret;
90  KRB_SAFE safe;
91  size_t len;
92
93  ret = decode_KRB_SAFE (inbuf->data, inbuf->length, &safe, &len);
94  if (ret)
95      return ret;
96  if (safe.pvno != 5) {
97      ret = KRB5KRB_AP_ERR_BADVERSION;
98      goto failure;
99  }
100  if (safe.msg_type != krb_safe) {
101      ret = KRB5KRB_AP_ERR_MSG_TYPE;
102      goto failure;
103  }
104  if (!krb5_checksum_is_keyed(context, safe.cksum.cksumtype)
105      || !krb5_checksum_is_collision_proof(context, safe.cksum.cksumtype)) {
106      ret = KRB5KRB_AP_ERR_INAPP_CKSUM;
107      goto failure;
108  }
109
110  /* check sender address */
111
112  if (safe.safe_body.s_address
113      && auth_context->remote_address
114      && !krb5_address_compare (context,
115				auth_context->remote_address,
116				safe.safe_body.s_address)) {
117      ret = KRB5KRB_AP_ERR_BADADDR;
118      goto failure;
119  }
120
121  /* check receiver address */
122
123  if (safe.safe_body.r_address
124      && auth_context->local_address
125      && !krb5_address_compare (context,
126				auth_context->local_address,
127				safe.safe_body.r_address)) {
128      ret = KRB5KRB_AP_ERR_BADADDR;
129      goto failure;
130  }
131
132  /* check timestamp */
133  if (auth_context->flags & KRB5_AUTH_CONTEXT_DO_TIME) {
134      int32_t sec;
135
136      krb5_timeofday (context, &sec);
137
138      if (safe.safe_body.timestamp == NULL ||
139	  safe.safe_body.usec      == NULL ||
140	  abs(*safe.safe_body.timestamp - sec) > context->max_skew) {
141	  ret = KRB5KRB_AP_ERR_SKEW;
142	  goto failure;
143      }
144  }
145  /* XXX - check replay cache */
146
147  /* check sequence number */
148  if (auth_context->flags & KRB5_AUTH_CONTEXT_DO_SEQUENCE) {
149      if (safe.safe_body.seq_number == NULL ||
150	  *safe.safe_body.seq_number != ++auth_context->remote_seqnumber) {
151	  ret = KRB5KRB_AP_ERR_BADORDER;
152	  goto failure;
153      }
154  }
155
156  ret = verify_checksum (context, auth_context, &safe);
157  if (ret)
158      goto failure;
159
160  outbuf->length = safe.safe_body.user_data.length;
161  outbuf->data   = malloc(outbuf->length);
162  if (outbuf->data == NULL) {
163      ret = ENOMEM;
164      goto failure;
165  }
166  memcpy (outbuf->data, safe.safe_body.user_data.data, outbuf->length);
167  free_KRB_SAFE (&safe);
168  return 0;
169failure:
170  free_KRB_SAFE (&safe);
171  return ret;
172}
173