1 /*
2 * Copyright (c) 1997 - 2003 Kungliga Tekniska Högskolan
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
36 static krb5_error_code
verify_checksum(krb5_context context,krb5_auth_context auth_context,KRB_SAFE * safe)37 verify_checksum(krb5_context context,
38 krb5_auth_context auth_context,
39 KRB_SAFE *safe)
40 {
41 krb5_error_code ret;
42 u_char *buf;
43 size_t buf_size;
44 size_t len = 0;
45 Checksum c;
46 krb5_crypto crypto;
47 krb5_keyblock *key;
48
49 c = safe->cksum;
50 safe->cksum.cksumtype = 0;
51 safe->cksum.checksum.data = NULL;
52 safe->cksum.checksum.length = 0;
53
54 ASN1_MALLOC_ENCODE(KRB_SAFE, buf, buf_size, safe, &len, ret);
55 if(ret)
56 return ret;
57 if(buf_size != len)
58 krb5_abortx(context, "internal error in ASN.1 encoder");
59
60 if (auth_context->remote_subkey)
61 key = auth_context->remote_subkey;
62 else if (auth_context->local_subkey)
63 key = auth_context->local_subkey;
64 else
65 key = auth_context->keyblock;
66
67 ret = krb5_crypto_init(context, key, 0, &crypto);
68 if (ret)
69 goto out;
70 ret = krb5_verify_checksum (context,
71 crypto,
72 KRB5_KU_KRB_SAFE_CKSUM,
73 buf + buf_size - len,
74 len,
75 &c);
76 krb5_crypto_destroy(context, crypto);
77 out:
78 safe->cksum = c;
79 free (buf);
80 return ret;
81 }
82
83 KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
krb5_rd_safe(krb5_context context,krb5_auth_context auth_context,const krb5_data * inbuf,krb5_data * outbuf,krb5_replay_data * outdata)84 krb5_rd_safe(krb5_context context,
85 krb5_auth_context auth_context,
86 const krb5_data *inbuf,
87 krb5_data *outbuf,
88 krb5_replay_data *outdata)
89 {
90 krb5_error_code ret;
91 KRB_SAFE safe;
92 size_t len;
93
94 krb5_data_zero(outbuf);
95
96 if ((auth_context->flags &
97 (KRB5_AUTH_CONTEXT_RET_TIME | KRB5_AUTH_CONTEXT_RET_SEQUENCE)))
98 {
99 if (outdata == NULL) {
100 krb5_set_error_message(context, KRB5_RC_REQUIRED,
101 N_("rd_safe: need outdata "
102 "to return data", ""));
103 return KRB5_RC_REQUIRED; /* XXX better error, MIT returns this */
104 }
105 /* if these fields are not present in the safe-part, silently
106 return zero */
107 memset(outdata, 0, sizeof(*outdata));
108 }
109
110 ret = decode_KRB_SAFE (inbuf->data, inbuf->length, &safe, &len);
111 if (ret)
112 return ret;
113 if (safe.pvno != 5) {
114 ret = KRB5KRB_AP_ERR_BADVERSION;
115 krb5_clear_error_message (context);
116 goto failure;
117 }
118 if (safe.msg_type != krb_safe) {
119 ret = KRB5KRB_AP_ERR_MSG_TYPE;
120 krb5_clear_error_message (context);
121 goto failure;
122 }
123 if (!krb5_checksum_is_keyed(context, safe.cksum.cksumtype)
124 || !krb5_checksum_is_collision_proof(context, safe.cksum.cksumtype)) {
125 ret = KRB5KRB_AP_ERR_INAPP_CKSUM;
126 krb5_clear_error_message (context);
127 goto failure;
128 }
129
130 /* check sender address */
131
132 if (safe.safe_body.s_address
133 && auth_context->remote_address
134 && !krb5_address_compare (context,
135 auth_context->remote_address,
136 safe.safe_body.s_address)) {
137 ret = KRB5KRB_AP_ERR_BADADDR;
138 krb5_clear_error_message (context);
139 goto failure;
140 }
141
142 /* check receiver address */
143
144 if (safe.safe_body.r_address
145 && auth_context->local_address
146 && !krb5_address_compare (context,
147 auth_context->local_address,
148 safe.safe_body.r_address)) {
149 ret = KRB5KRB_AP_ERR_BADADDR;
150 krb5_clear_error_message (context);
151 goto failure;
152 }
153
154 /* check timestamp */
155 if (auth_context->flags & KRB5_AUTH_CONTEXT_DO_TIME) {
156 krb5_timestamp sec;
157
158 krb5_timeofday (context, &sec);
159
160 if (safe.safe_body.timestamp == NULL ||
161 safe.safe_body.usec == NULL ||
162 abs(*safe.safe_body.timestamp - sec) > context->max_skew) {
163 ret = KRB5KRB_AP_ERR_SKEW;
164 krb5_clear_error_message (context);
165 goto failure;
166 }
167 }
168 /* XXX - check replay cache */
169
170 /* check sequence number. since MIT krb5 cannot generate a sequence
171 number of zero but instead generates no sequence number, we accept that
172 */
173
174 if (auth_context->flags & KRB5_AUTH_CONTEXT_DO_SEQUENCE) {
175 if ((safe.safe_body.seq_number == NULL
176 && auth_context->remote_seqnumber != 0)
177 || (safe.safe_body.seq_number != NULL
178 && *safe.safe_body.seq_number !=
179 auth_context->remote_seqnumber)) {
180 ret = KRB5KRB_AP_ERR_BADORDER;
181 krb5_clear_error_message (context);
182 goto failure;
183 }
184 auth_context->remote_seqnumber++;
185 }
186
187 ret = verify_checksum (context, auth_context, &safe);
188 if (ret)
189 goto failure;
190
191 outbuf->length = safe.safe_body.user_data.length;
192 outbuf->data = malloc(outbuf->length);
193 if (outbuf->data == NULL && outbuf->length != 0) {
194 ret = ENOMEM;
195 krb5_set_error_message(context, ret, N_("malloc: out of memory", ""));
196 krb5_data_zero(outbuf);
197 goto failure;
198 }
199 memcpy (outbuf->data, safe.safe_body.user_data.data, outbuf->length);
200
201 if ((auth_context->flags &
202 (KRB5_AUTH_CONTEXT_RET_TIME | KRB5_AUTH_CONTEXT_RET_SEQUENCE))) {
203
204 if(safe.safe_body.timestamp)
205 outdata->timestamp = *safe.safe_body.timestamp;
206 if(safe.safe_body.usec)
207 outdata->usec = *safe.safe_body.usec;
208 if(safe.safe_body.seq_number)
209 outdata->seq = *safe.safe_body.seq_number;
210 }
211
212 failure:
213 free_KRB_SAFE (&safe);
214 return ret;
215 }
216