1 /******************************************************************************* 2 * This file houses the main functions for the iSCSI CHAP support 3 * 4 * (c) Copyright 2007-2013 Datera, Inc. 5 * 6 * Author: Nicholas A. Bellinger <nab@linux-iscsi.org> 7 * 8 * This program is free software; you can redistribute it and/or modify 9 * it under the terms of the GNU General Public License as published by 10 * the Free Software Foundation; either version 2 of the License, or 11 * (at your option) any later version. 12 * 13 * This program is distributed in the hope that it will be useful, 14 * but WITHOUT ANY WARRANTY; without even the implied warranty of 15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 * GNU General Public License for more details. 17 ******************************************************************************/ 18 19 #include <linux/kernel.h> 20 #include <linux/string.h> 21 #include <linux/crypto.h> 22 #include <linux/err.h> 23 #include <linux/scatterlist.h> 24 25 #include "iscsi_target_core.h" 26 #include "iscsi_target_nego.h" 27 #include "iscsi_target_auth.h" 28 29 static int chap_string_to_hex(unsigned char *dst, unsigned char *src, int len) 30 { 31 int j = DIV_ROUND_UP(len, 2), rc; 32 33 rc = hex2bin(dst, src, j); 34 if (rc < 0) 35 pr_debug("CHAP string contains non hex digit symbols\n"); 36 37 dst[j] = '\0'; 38 return j; 39 } 40 41 static void chap_binaryhex_to_asciihex(char *dst, char *src, int src_len) 42 { 43 int i; 44 45 for (i = 0; i < src_len; i++) { 46 sprintf(&dst[i*2], "%02x", (int) src[i] & 0xff); 47 } 48 } 49 50 static void chap_gen_challenge( 51 struct iscsi_conn *conn, 52 int caller, 53 char *c_str, 54 unsigned int *c_len) 55 { 56 unsigned char challenge_asciihex[CHAP_CHALLENGE_LENGTH * 2 + 1]; 57 struct iscsi_chap *chap = conn->auth_protocol; 58 59 memset(challenge_asciihex, 0, CHAP_CHALLENGE_LENGTH * 2 + 1); 60 61 get_random_bytes(chap->challenge, CHAP_CHALLENGE_LENGTH); 62 chap_binaryhex_to_asciihex(challenge_asciihex, chap->challenge, 63 CHAP_CHALLENGE_LENGTH); 64 /* 65 * Set CHAP_C, and copy the generated challenge into c_str. 66 */ 67 *c_len += sprintf(c_str + *c_len, "CHAP_C=0x%s", challenge_asciihex); 68 *c_len += 1; 69 70 pr_debug("[%s] Sending CHAP_C=0x%s\n\n", (caller) ? "server" : "client", 71 challenge_asciihex); 72 } 73 74 75 static struct iscsi_chap *chap_server_open( 76 struct iscsi_conn *conn, 77 struct iscsi_node_auth *auth, 78 const char *a_str, 79 char *aic_str, 80 unsigned int *aic_len) 81 { 82 struct iscsi_chap *chap; 83 84 if (!(auth->naf_flags & NAF_USERID_SET) || 85 !(auth->naf_flags & NAF_PASSWORD_SET)) { 86 pr_err("CHAP user or password not set for" 87 " Initiator ACL\n"); 88 return NULL; 89 } 90 91 conn->auth_protocol = kzalloc(sizeof(struct iscsi_chap), GFP_KERNEL); 92 if (!conn->auth_protocol) 93 return NULL; 94 95 chap = conn->auth_protocol; 96 /* 97 * We only support MD5 MDA presently. 98 */ 99 if (strncmp(a_str, "CHAP_A=5", 8)) { 100 pr_err("CHAP_A is not MD5.\n"); 101 return NULL; 102 } 103 pr_debug("[server] Got CHAP_A=5\n"); 104 /* 105 * Send back CHAP_A set to MD5. 106 */ 107 *aic_len = sprintf(aic_str, "CHAP_A=5"); 108 *aic_len += 1; 109 chap->digest_type = CHAP_DIGEST_MD5; 110 pr_debug("[server] Sending CHAP_A=%d\n", chap->digest_type); 111 /* 112 * Set Identifier. 113 */ 114 chap->id = conn->tpg->tpg_chap_id++; 115 *aic_len += sprintf(aic_str + *aic_len, "CHAP_I=%d", chap->id); 116 *aic_len += 1; 117 pr_debug("[server] Sending CHAP_I=%d\n", chap->id); 118 /* 119 * Generate Challenge. 120 */ 121 chap_gen_challenge(conn, 1, aic_str, aic_len); 122 123 return chap; 124 } 125 126 static void chap_close(struct iscsi_conn *conn) 127 { 128 kfree(conn->auth_protocol); 129 conn->auth_protocol = NULL; 130 } 131 132 static int chap_server_compute_md5( 133 struct iscsi_conn *conn, 134 struct iscsi_node_auth *auth, 135 char *nr_in_ptr, 136 char *nr_out_ptr, 137 unsigned int *nr_out_len) 138 { 139 char *endptr; 140 unsigned long id; 141 unsigned char id_as_uchar; 142 unsigned char digest[MD5_SIGNATURE_SIZE]; 143 unsigned char type, response[MD5_SIGNATURE_SIZE * 2 + 2]; 144 unsigned char identifier[10], *challenge = NULL; 145 unsigned char *challenge_binhex = NULL; 146 unsigned char client_digest[MD5_SIGNATURE_SIZE]; 147 unsigned char server_digest[MD5_SIGNATURE_SIZE]; 148 unsigned char chap_n[MAX_CHAP_N_SIZE], chap_r[MAX_RESPONSE_LENGTH]; 149 size_t compare_len; 150 struct iscsi_chap *chap = conn->auth_protocol; 151 struct crypto_hash *tfm; 152 struct hash_desc desc; 153 struct scatterlist sg; 154 int auth_ret = -1, ret, challenge_len; 155 156 memset(identifier, 0, 10); 157 memset(chap_n, 0, MAX_CHAP_N_SIZE); 158 memset(chap_r, 0, MAX_RESPONSE_LENGTH); 159 memset(digest, 0, MD5_SIGNATURE_SIZE); 160 memset(response, 0, MD5_SIGNATURE_SIZE * 2 + 2); 161 memset(client_digest, 0, MD5_SIGNATURE_SIZE); 162 memset(server_digest, 0, MD5_SIGNATURE_SIZE); 163 164 challenge = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL); 165 if (!challenge) { 166 pr_err("Unable to allocate challenge buffer\n"); 167 goto out; 168 } 169 170 challenge_binhex = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL); 171 if (!challenge_binhex) { 172 pr_err("Unable to allocate challenge_binhex buffer\n"); 173 goto out; 174 } 175 /* 176 * Extract CHAP_N. 177 */ 178 if (extract_param(nr_in_ptr, "CHAP_N", MAX_CHAP_N_SIZE, chap_n, 179 &type) < 0) { 180 pr_err("Could not find CHAP_N.\n"); 181 goto out; 182 } 183 if (type == HEX) { 184 pr_err("Could not find CHAP_N.\n"); 185 goto out; 186 } 187 188 /* Include the terminating NULL in the compare */ 189 compare_len = strlen(auth->userid) + 1; 190 if (strncmp(chap_n, auth->userid, compare_len) != 0) { 191 pr_err("CHAP_N values do not match!\n"); 192 goto out; 193 } 194 pr_debug("[server] Got CHAP_N=%s\n", chap_n); 195 /* 196 * Extract CHAP_R. 197 */ 198 if (extract_param(nr_in_ptr, "CHAP_R", MAX_RESPONSE_LENGTH, chap_r, 199 &type) < 0) { 200 pr_err("Could not find CHAP_R.\n"); 201 goto out; 202 } 203 if (type != HEX) { 204 pr_err("Could not find CHAP_R.\n"); 205 goto out; 206 } 207 208 pr_debug("[server] Got CHAP_R=%s\n", chap_r); 209 chap_string_to_hex(client_digest, chap_r, strlen(chap_r)); 210 211 tfm = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC); 212 if (IS_ERR(tfm)) { 213 pr_err("Unable to allocate struct crypto_hash\n"); 214 goto out; 215 } 216 desc.tfm = tfm; 217 desc.flags = 0; 218 219 ret = crypto_hash_init(&desc); 220 if (ret < 0) { 221 pr_err("crypto_hash_init() failed\n"); 222 crypto_free_hash(tfm); 223 goto out; 224 } 225 226 sg_init_one(&sg, &chap->id, 1); 227 ret = crypto_hash_update(&desc, &sg, 1); 228 if (ret < 0) { 229 pr_err("crypto_hash_update() failed for id\n"); 230 crypto_free_hash(tfm); 231 goto out; 232 } 233 234 sg_init_one(&sg, &auth->password, strlen(auth->password)); 235 ret = crypto_hash_update(&desc, &sg, strlen(auth->password)); 236 if (ret < 0) { 237 pr_err("crypto_hash_update() failed for password\n"); 238 crypto_free_hash(tfm); 239 goto out; 240 } 241 242 sg_init_one(&sg, chap->challenge, CHAP_CHALLENGE_LENGTH); 243 ret = crypto_hash_update(&desc, &sg, CHAP_CHALLENGE_LENGTH); 244 if (ret < 0) { 245 pr_err("crypto_hash_update() failed for challenge\n"); 246 crypto_free_hash(tfm); 247 goto out; 248 } 249 250 ret = crypto_hash_final(&desc, server_digest); 251 if (ret < 0) { 252 pr_err("crypto_hash_final() failed for server digest\n"); 253 crypto_free_hash(tfm); 254 goto out; 255 } 256 crypto_free_hash(tfm); 257 258 chap_binaryhex_to_asciihex(response, server_digest, MD5_SIGNATURE_SIZE); 259 pr_debug("[server] MD5 Server Digest: %s\n", response); 260 261 if (memcmp(server_digest, client_digest, MD5_SIGNATURE_SIZE) != 0) { 262 pr_debug("[server] MD5 Digests do not match!\n\n"); 263 goto out; 264 } else 265 pr_debug("[server] MD5 Digests match, CHAP connetication" 266 " successful.\n\n"); 267 /* 268 * One way authentication has succeeded, return now if mutual 269 * authentication is not enabled. 270 */ 271 if (!auth->authenticate_target) { 272 kfree(challenge); 273 kfree(challenge_binhex); 274 return 0; 275 } 276 /* 277 * Get CHAP_I. 278 */ 279 if (extract_param(nr_in_ptr, "CHAP_I", 10, identifier, &type) < 0) { 280 pr_err("Could not find CHAP_I.\n"); 281 goto out; 282 } 283 284 if (type == HEX) 285 id = simple_strtoul(&identifier[2], &endptr, 0); 286 else 287 id = simple_strtoul(identifier, &endptr, 0); 288 if (id > 255) { 289 pr_err("chap identifier: %lu greater than 255\n", id); 290 goto out; 291 } 292 /* 293 * RFC 1994 says Identifier is no more than octet (8 bits). 294 */ 295 pr_debug("[server] Got CHAP_I=%lu\n", id); 296 /* 297 * Get CHAP_C. 298 */ 299 if (extract_param(nr_in_ptr, "CHAP_C", CHAP_CHALLENGE_STR_LEN, 300 challenge, &type) < 0) { 301 pr_err("Could not find CHAP_C.\n"); 302 goto out; 303 } 304 305 if (type != HEX) { 306 pr_err("Could not find CHAP_C.\n"); 307 goto out; 308 } 309 pr_debug("[server] Got CHAP_C=%s\n", challenge); 310 challenge_len = chap_string_to_hex(challenge_binhex, challenge, 311 strlen(challenge)); 312 if (!challenge_len) { 313 pr_err("Unable to convert incoming challenge\n"); 314 goto out; 315 } 316 /* 317 * Generate CHAP_N and CHAP_R for mutual authentication. 318 */ 319 tfm = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC); 320 if (IS_ERR(tfm)) { 321 pr_err("Unable to allocate struct crypto_hash\n"); 322 goto out; 323 } 324 desc.tfm = tfm; 325 desc.flags = 0; 326 327 ret = crypto_hash_init(&desc); 328 if (ret < 0) { 329 pr_err("crypto_hash_init() failed\n"); 330 crypto_free_hash(tfm); 331 goto out; 332 } 333 334 /* To handle both endiannesses */ 335 id_as_uchar = id; 336 sg_init_one(&sg, &id_as_uchar, 1); 337 ret = crypto_hash_update(&desc, &sg, 1); 338 if (ret < 0) { 339 pr_err("crypto_hash_update() failed for id\n"); 340 crypto_free_hash(tfm); 341 goto out; 342 } 343 344 sg_init_one(&sg, auth->password_mutual, 345 strlen(auth->password_mutual)); 346 ret = crypto_hash_update(&desc, &sg, strlen(auth->password_mutual)); 347 if (ret < 0) { 348 pr_err("crypto_hash_update() failed for" 349 " password_mutual\n"); 350 crypto_free_hash(tfm); 351 goto out; 352 } 353 /* 354 * Convert received challenge to binary hex. 355 */ 356 sg_init_one(&sg, challenge_binhex, challenge_len); 357 ret = crypto_hash_update(&desc, &sg, challenge_len); 358 if (ret < 0) { 359 pr_err("crypto_hash_update() failed for ma challenge\n"); 360 crypto_free_hash(tfm); 361 goto out; 362 } 363 364 ret = crypto_hash_final(&desc, digest); 365 if (ret < 0) { 366 pr_err("crypto_hash_final() failed for ma digest\n"); 367 crypto_free_hash(tfm); 368 goto out; 369 } 370 crypto_free_hash(tfm); 371 /* 372 * Generate CHAP_N and CHAP_R. 373 */ 374 *nr_out_len = sprintf(nr_out_ptr, "CHAP_N=%s", auth->userid_mutual); 375 *nr_out_len += 1; 376 pr_debug("[server] Sending CHAP_N=%s\n", auth->userid_mutual); 377 /* 378 * Convert response from binary hex to ascii hext. 379 */ 380 chap_binaryhex_to_asciihex(response, digest, MD5_SIGNATURE_SIZE); 381 *nr_out_len += sprintf(nr_out_ptr + *nr_out_len, "CHAP_R=0x%s", 382 response); 383 *nr_out_len += 1; 384 pr_debug("[server] Sending CHAP_R=0x%s\n", response); 385 auth_ret = 0; 386 out: 387 kfree(challenge); 388 kfree(challenge_binhex); 389 return auth_ret; 390 } 391 392 static int chap_got_response( 393 struct iscsi_conn *conn, 394 struct iscsi_node_auth *auth, 395 char *nr_in_ptr, 396 char *nr_out_ptr, 397 unsigned int *nr_out_len) 398 { 399 struct iscsi_chap *chap = conn->auth_protocol; 400 401 switch (chap->digest_type) { 402 case CHAP_DIGEST_MD5: 403 if (chap_server_compute_md5(conn, auth, nr_in_ptr, 404 nr_out_ptr, nr_out_len) < 0) 405 return -1; 406 return 0; 407 default: 408 pr_err("Unknown CHAP digest type %d!\n", 409 chap->digest_type); 410 return -1; 411 } 412 } 413 414 u32 chap_main_loop( 415 struct iscsi_conn *conn, 416 struct iscsi_node_auth *auth, 417 char *in_text, 418 char *out_text, 419 int *in_len, 420 int *out_len) 421 { 422 struct iscsi_chap *chap = conn->auth_protocol; 423 424 if (!chap) { 425 chap = chap_server_open(conn, auth, in_text, out_text, out_len); 426 if (!chap) 427 return 2; 428 chap->chap_state = CHAP_STAGE_SERVER_AIC; 429 return 0; 430 } else if (chap->chap_state == CHAP_STAGE_SERVER_AIC) { 431 convert_null_to_semi(in_text, *in_len); 432 if (chap_got_response(conn, auth, in_text, out_text, 433 out_len) < 0) { 434 chap_close(conn); 435 return 2; 436 } 437 if (auth->authenticate_target) 438 chap->chap_state = CHAP_STAGE_SERVER_NR; 439 else 440 *out_len = 0; 441 chap_close(conn); 442 return 1; 443 } 444 445 return 2; 446 } 447