1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /******************************************************************************* 3 * This file houses the main functions for the iSCSI CHAP support 4 * 5 * (c) Copyright 2007-2013 Datera, Inc. 6 * 7 * Author: Nicholas A. Bellinger <nab@linux-iscsi.org> 8 * 9 ******************************************************************************/ 10 11 #include <crypto/hash.h> 12 #include <linux/kernel.h> 13 #include <linux/string.h> 14 #include <linux/err.h> 15 #include <linux/random.h> 16 #include <linux/scatterlist.h> 17 #include <target/iscsi/iscsi_target_core.h> 18 #include "iscsi_target_nego.h" 19 #include "iscsi_target_auth.h" 20 21 static char *chap_get_digest_name(const int digest_type) 22 { 23 switch (digest_type) { 24 case CHAP_DIGEST_MD5: 25 return "md5"; 26 case CHAP_DIGEST_SHA1: 27 return "sha1"; 28 case CHAP_DIGEST_SHA256: 29 return "sha256"; 30 case CHAP_DIGEST_SHA3_256: 31 return "sha3-256"; 32 default: 33 return NULL; 34 } 35 } 36 37 static int chap_gen_challenge( 38 struct iscsi_conn *conn, 39 int caller, 40 char *c_str, 41 unsigned int *c_len) 42 { 43 int ret; 44 unsigned char *challenge_asciihex; 45 struct iscsi_chap *chap = conn->auth_protocol; 46 47 challenge_asciihex = kzalloc(chap->challenge_len * 2 + 1, GFP_KERNEL); 48 if (!challenge_asciihex) 49 return -ENOMEM; 50 51 memset(chap->challenge, 0, MAX_CHAP_CHALLENGE_LEN); 52 53 ret = get_random_bytes_wait(chap->challenge, chap->challenge_len); 54 if (unlikely(ret)) 55 goto out; 56 57 bin2hex(challenge_asciihex, chap->challenge, 58 chap->challenge_len); 59 /* 60 * Set CHAP_C, and copy the generated challenge into c_str. 61 */ 62 *c_len += sprintf(c_str + *c_len, "CHAP_C=0x%s", challenge_asciihex); 63 *c_len += 1; 64 65 pr_debug("[%s] Sending CHAP_C=0x%s\n\n", (caller) ? "server" : "client", 66 challenge_asciihex); 67 68 out: 69 kfree(challenge_asciihex); 70 return ret; 71 } 72 73 static int chap_test_algorithm(const char *name) 74 { 75 struct crypto_shash *tfm; 76 77 tfm = crypto_alloc_shash(name, 0, 0); 78 if (IS_ERR(tfm)) 79 return -1; 80 81 crypto_free_shash(tfm); 82 return 0; 83 } 84 85 static int chap_check_algorithm(const char *a_str) 86 { 87 char *tmp, *orig, *token, *digest_name; 88 long digest_type; 89 int r = CHAP_DIGEST_UNKNOWN; 90 91 tmp = kstrdup(a_str, GFP_KERNEL); 92 if (!tmp) { 93 pr_err("Memory allocation failed for CHAP_A temporary buffer\n"); 94 return CHAP_DIGEST_UNKNOWN; 95 } 96 orig = tmp; 97 98 token = strsep(&tmp, "="); 99 if (!token) 100 goto out; 101 102 if (strcmp(token, "CHAP_A")) { 103 pr_err("Unable to locate CHAP_A key\n"); 104 goto out; 105 } 106 while (token) { 107 token = strsep(&tmp, ","); 108 if (!token) 109 goto out; 110 111 if (kstrtol(token, 10, &digest_type)) 112 continue; 113 114 digest_name = chap_get_digest_name(digest_type); 115 if (!digest_name) 116 continue; 117 118 pr_debug("Selected %s Algorithm\n", digest_name); 119 if (chap_test_algorithm(digest_name) < 0) { 120 pr_err("failed to allocate %s algo\n", digest_name); 121 } else { 122 r = digest_type; 123 goto out; 124 } 125 } 126 out: 127 kfree(orig); 128 return r; 129 } 130 131 static void chap_close(struct iscsi_conn *conn) 132 { 133 kfree(conn->auth_protocol); 134 conn->auth_protocol = NULL; 135 } 136 137 static struct iscsi_chap *chap_server_open( 138 struct iscsi_conn *conn, 139 struct iscsi_node_auth *auth, 140 const char *a_str, 141 char *aic_str, 142 unsigned int *aic_len) 143 { 144 int digest_type; 145 struct iscsi_chap *chap; 146 147 if (!(auth->naf_flags & NAF_USERID_SET) || 148 !(auth->naf_flags & NAF_PASSWORD_SET)) { 149 pr_err("CHAP user or password not set for" 150 " Initiator ACL\n"); 151 return NULL; 152 } 153 154 conn->auth_protocol = kzalloc(sizeof(struct iscsi_chap), GFP_KERNEL); 155 if (!conn->auth_protocol) 156 return NULL; 157 158 chap = conn->auth_protocol; 159 digest_type = chap_check_algorithm(a_str); 160 switch (digest_type) { 161 case CHAP_DIGEST_MD5: 162 chap->digest_size = MD5_SIGNATURE_SIZE; 163 break; 164 case CHAP_DIGEST_SHA1: 165 chap->digest_size = SHA1_SIGNATURE_SIZE; 166 break; 167 case CHAP_DIGEST_SHA256: 168 chap->digest_size = SHA256_SIGNATURE_SIZE; 169 break; 170 case CHAP_DIGEST_SHA3_256: 171 chap->digest_size = SHA3_256_SIGNATURE_SIZE; 172 break; 173 case CHAP_DIGEST_UNKNOWN: 174 default: 175 pr_err("Unsupported CHAP_A value\n"); 176 chap_close(conn); 177 return NULL; 178 } 179 180 chap->digest_name = chap_get_digest_name(digest_type); 181 182 /* Tie the challenge length to the digest size */ 183 chap->challenge_len = chap->digest_size; 184 185 pr_debug("[server] Got CHAP_A=%d\n", digest_type); 186 *aic_len = sprintf(aic_str, "CHAP_A=%d", digest_type); 187 *aic_len += 1; 188 pr_debug("[server] Sending CHAP_A=%d\n", digest_type); 189 190 /* 191 * Set Identifier. 192 */ 193 chap->id = conn->tpg->tpg_chap_id++; 194 *aic_len += sprintf(aic_str + *aic_len, "CHAP_I=%d", chap->id); 195 *aic_len += 1; 196 pr_debug("[server] Sending CHAP_I=%d\n", chap->id); 197 /* 198 * Generate Challenge. 199 */ 200 if (chap_gen_challenge(conn, 1, aic_str, aic_len) < 0) { 201 chap_close(conn); 202 return NULL; 203 } 204 205 return chap; 206 } 207 208 static int chap_server_compute_hash( 209 struct iscsi_conn *conn, 210 struct iscsi_node_auth *auth, 211 char *nr_in_ptr, 212 char *nr_out_ptr, 213 unsigned int *nr_out_len) 214 { 215 unsigned long id; 216 unsigned char id_as_uchar; 217 unsigned char type; 218 unsigned char identifier[10], *initiatorchg = NULL; 219 unsigned char *initiatorchg_binhex = NULL; 220 unsigned char *digest = NULL; 221 unsigned char *response = NULL; 222 unsigned char *client_digest = NULL; 223 unsigned char *server_digest = NULL; 224 unsigned char chap_n[MAX_CHAP_N_SIZE], chap_r[MAX_RESPONSE_LENGTH]; 225 size_t compare_len; 226 struct iscsi_chap *chap = conn->auth_protocol; 227 struct crypto_shash *tfm = NULL; 228 struct shash_desc *desc = NULL; 229 int auth_ret = -1, ret, initiatorchg_len; 230 231 digest = kzalloc(chap->digest_size, GFP_KERNEL); 232 if (!digest) { 233 pr_err("Unable to allocate the digest buffer\n"); 234 goto out; 235 } 236 237 response = kzalloc(chap->digest_size * 2 + 2, GFP_KERNEL); 238 if (!response) { 239 pr_err("Unable to allocate the response buffer\n"); 240 goto out; 241 } 242 243 client_digest = kzalloc(chap->digest_size, GFP_KERNEL); 244 if (!client_digest) { 245 pr_err("Unable to allocate the client_digest buffer\n"); 246 goto out; 247 } 248 249 server_digest = kzalloc(chap->digest_size, GFP_KERNEL); 250 if (!server_digest) { 251 pr_err("Unable to allocate the server_digest buffer\n"); 252 goto out; 253 } 254 255 memset(identifier, 0, 10); 256 memset(chap_n, 0, MAX_CHAP_N_SIZE); 257 memset(chap_r, 0, MAX_RESPONSE_LENGTH); 258 259 initiatorchg = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL); 260 if (!initiatorchg) { 261 pr_err("Unable to allocate challenge buffer\n"); 262 goto out; 263 } 264 265 initiatorchg_binhex = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL); 266 if (!initiatorchg_binhex) { 267 pr_err("Unable to allocate initiatorchg_binhex buffer\n"); 268 goto out; 269 } 270 /* 271 * Extract CHAP_N. 272 */ 273 if (extract_param(nr_in_ptr, "CHAP_N", MAX_CHAP_N_SIZE, chap_n, 274 &type) < 0) { 275 pr_err("Could not find CHAP_N.\n"); 276 goto out; 277 } 278 if (type == HEX) { 279 pr_err("Could not find CHAP_N.\n"); 280 goto out; 281 } 282 283 /* Include the terminating NULL in the compare */ 284 compare_len = strlen(auth->userid) + 1; 285 if (strncmp(chap_n, auth->userid, compare_len) != 0) { 286 pr_err("CHAP_N values do not match!\n"); 287 goto out; 288 } 289 pr_debug("[server] Got CHAP_N=%s\n", chap_n); 290 /* 291 * Extract CHAP_R. 292 */ 293 if (extract_param(nr_in_ptr, "CHAP_R", MAX_RESPONSE_LENGTH, chap_r, 294 &type) < 0) { 295 pr_err("Could not find CHAP_R.\n"); 296 goto out; 297 } 298 if (type != HEX) { 299 pr_err("Could not find CHAP_R.\n"); 300 goto out; 301 } 302 if (strlen(chap_r) != chap->digest_size * 2) { 303 pr_err("Malformed CHAP_R\n"); 304 goto out; 305 } 306 if (hex2bin(client_digest, chap_r, chap->digest_size) < 0) { 307 pr_err("Malformed CHAP_R\n"); 308 goto out; 309 } 310 311 pr_debug("[server] Got CHAP_R=%s\n", chap_r); 312 313 tfm = crypto_alloc_shash(chap->digest_name, 0, 0); 314 if (IS_ERR(tfm)) { 315 tfm = NULL; 316 pr_err("Unable to allocate struct crypto_shash\n"); 317 goto out; 318 } 319 320 desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(tfm), GFP_KERNEL); 321 if (!desc) { 322 pr_err("Unable to allocate struct shash_desc\n"); 323 goto out; 324 } 325 326 desc->tfm = tfm; 327 328 ret = crypto_shash_init(desc); 329 if (ret < 0) { 330 pr_err("crypto_shash_init() failed\n"); 331 goto out; 332 } 333 334 ret = crypto_shash_update(desc, &chap->id, 1); 335 if (ret < 0) { 336 pr_err("crypto_shash_update() failed for id\n"); 337 goto out; 338 } 339 340 ret = crypto_shash_update(desc, (char *)&auth->password, 341 strlen(auth->password)); 342 if (ret < 0) { 343 pr_err("crypto_shash_update() failed for password\n"); 344 goto out; 345 } 346 347 ret = crypto_shash_finup(desc, chap->challenge, 348 chap->challenge_len, server_digest); 349 if (ret < 0) { 350 pr_err("crypto_shash_finup() failed for challenge\n"); 351 goto out; 352 } 353 354 bin2hex(response, server_digest, chap->digest_size); 355 pr_debug("[server] %s Server Digest: %s\n", 356 chap->digest_name, response); 357 358 if (memcmp(server_digest, client_digest, chap->digest_size) != 0) { 359 pr_debug("[server] %s Digests do not match!\n\n", 360 chap->digest_name); 361 goto out; 362 } else 363 pr_debug("[server] %s Digests match, CHAP connection" 364 " successful.\n\n", chap->digest_name); 365 /* 366 * One way authentication has succeeded, return now if mutual 367 * authentication is not enabled. 368 */ 369 if (!auth->authenticate_target) { 370 auth_ret = 0; 371 goto out; 372 } 373 /* 374 * Get CHAP_I. 375 */ 376 if (extract_param(nr_in_ptr, "CHAP_I", 10, identifier, &type) < 0) { 377 pr_err("Could not find CHAP_I.\n"); 378 goto out; 379 } 380 381 if (type == HEX) 382 ret = kstrtoul(&identifier[2], 0, &id); 383 else 384 ret = kstrtoul(identifier, 0, &id); 385 386 if (ret < 0) { 387 pr_err("kstrtoul() failed for CHAP identifier: %d\n", ret); 388 goto out; 389 } 390 if (id > 255) { 391 pr_err("chap identifier: %lu greater than 255\n", id); 392 goto out; 393 } 394 /* 395 * RFC 1994 says Identifier is no more than octet (8 bits). 396 */ 397 pr_debug("[server] Got CHAP_I=%lu\n", id); 398 /* 399 * Get CHAP_C. 400 */ 401 if (extract_param(nr_in_ptr, "CHAP_C", CHAP_CHALLENGE_STR_LEN, 402 initiatorchg, &type) < 0) { 403 pr_err("Could not find CHAP_C.\n"); 404 goto out; 405 } 406 407 if (type != HEX) { 408 pr_err("Could not find CHAP_C.\n"); 409 goto out; 410 } 411 initiatorchg_len = DIV_ROUND_UP(strlen(initiatorchg), 2); 412 if (!initiatorchg_len) { 413 pr_err("Unable to convert incoming challenge\n"); 414 goto out; 415 } 416 if (initiatorchg_len > 1024) { 417 pr_err("CHAP_C exceeds maximum binary size of 1024 bytes\n"); 418 goto out; 419 } 420 if (hex2bin(initiatorchg_binhex, initiatorchg, initiatorchg_len) < 0) { 421 pr_err("Malformed CHAP_C\n"); 422 goto out; 423 } 424 pr_debug("[server] Got CHAP_C=%s\n", initiatorchg); 425 /* 426 * During mutual authentication, the CHAP_C generated by the 427 * initiator must not match the original CHAP_C generated by 428 * the target. 429 */ 430 if (initiatorchg_len == chap->challenge_len && 431 !memcmp(initiatorchg_binhex, chap->challenge, 432 initiatorchg_len)) { 433 pr_err("initiator CHAP_C matches target CHAP_C, failing" 434 " login attempt\n"); 435 goto out; 436 } 437 /* 438 * Generate CHAP_N and CHAP_R for mutual authentication. 439 */ 440 ret = crypto_shash_init(desc); 441 if (ret < 0) { 442 pr_err("crypto_shash_init() failed\n"); 443 goto out; 444 } 445 446 /* To handle both endiannesses */ 447 id_as_uchar = id; 448 ret = crypto_shash_update(desc, &id_as_uchar, 1); 449 if (ret < 0) { 450 pr_err("crypto_shash_update() failed for id\n"); 451 goto out; 452 } 453 454 ret = crypto_shash_update(desc, auth->password_mutual, 455 strlen(auth->password_mutual)); 456 if (ret < 0) { 457 pr_err("crypto_shash_update() failed for" 458 " password_mutual\n"); 459 goto out; 460 } 461 /* 462 * Convert received challenge to binary hex. 463 */ 464 ret = crypto_shash_finup(desc, initiatorchg_binhex, initiatorchg_len, 465 digest); 466 if (ret < 0) { 467 pr_err("crypto_shash_finup() failed for ma challenge\n"); 468 goto out; 469 } 470 471 /* 472 * Generate CHAP_N and CHAP_R. 473 */ 474 *nr_out_len = sprintf(nr_out_ptr, "CHAP_N=%s", auth->userid_mutual); 475 *nr_out_len += 1; 476 pr_debug("[server] Sending CHAP_N=%s\n", auth->userid_mutual); 477 /* 478 * Convert response from binary hex to ascii hext. 479 */ 480 bin2hex(response, digest, chap->digest_size); 481 *nr_out_len += sprintf(nr_out_ptr + *nr_out_len, "CHAP_R=0x%s", 482 response); 483 *nr_out_len += 1; 484 pr_debug("[server] Sending CHAP_R=0x%s\n", response); 485 auth_ret = 0; 486 out: 487 kfree_sensitive(desc); 488 if (tfm) 489 crypto_free_shash(tfm); 490 kfree(initiatorchg); 491 kfree(initiatorchg_binhex); 492 kfree(digest); 493 kfree(response); 494 kfree(server_digest); 495 kfree(client_digest); 496 return auth_ret; 497 } 498 499 u32 chap_main_loop( 500 struct iscsi_conn *conn, 501 struct iscsi_node_auth *auth, 502 char *in_text, 503 char *out_text, 504 int *in_len, 505 int *out_len) 506 { 507 struct iscsi_chap *chap = conn->auth_protocol; 508 509 if (!chap) { 510 chap = chap_server_open(conn, auth, in_text, out_text, out_len); 511 if (!chap) 512 return 2; 513 chap->chap_state = CHAP_STAGE_SERVER_AIC; 514 return 0; 515 } else if (chap->chap_state == CHAP_STAGE_SERVER_AIC) { 516 convert_null_to_semi(in_text, *in_len); 517 if (chap_server_compute_hash(conn, auth, in_text, out_text, 518 out_len) < 0) { 519 chap_close(conn); 520 return 2; 521 } 522 if (auth->authenticate_target) 523 chap->chap_state = CHAP_STAGE_SERVER_NR; 524 else 525 *out_len = 0; 526 chap_close(conn); 527 return 1; 528 } 529 530 return 2; 531 } 532