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 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 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