1 /******************************************************************************* 2 * This file houses the main functions for the iSCSI CHAP support 3 * 4 * \u00a9 Copyright 2007-2011 RisingTide Systems LLC. 5 * 6 * Licensed to the Linux Foundation under the General Public License (GPL) version 2. 7 * 8 * Author: Nicholas A. Bellinger <nab@linux-iscsi.org> 9 * 10 * This program is free software; you can redistribute it and/or modify 11 * it under the terms of the GNU General Public License as published by 12 * the Free Software Foundation; either version 2 of the License, or 13 * (at your option) any later version. 14 * 15 * This program is distributed in the hope that it will be useful, 16 * but WITHOUT ANY WARRANTY; without even the implied warranty of 17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 18 * GNU General Public License for more details. 19 ******************************************************************************/ 20 21 #include <linux/string.h> 22 #include <linux/crypto.h> 23 #include <linux/err.h> 24 #include <linux/scatterlist.h> 25 26 #include "iscsi_target_core.h" 27 #include "iscsi_target_nego.h" 28 #include "iscsi_target_auth.h" 29 30 static unsigned char chap_asciihex_to_binaryhex(unsigned char val[2]) 31 { 32 unsigned char result = 0; 33 /* 34 * MSB 35 */ 36 if ((val[0] >= 'a') && (val[0] <= 'f')) 37 result = ((val[0] - 'a' + 10) & 0xf) << 4; 38 else 39 if ((val[0] >= 'A') && (val[0] <= 'F')) 40 result = ((val[0] - 'A' + 10) & 0xf) << 4; 41 else /* digit */ 42 result = ((val[0] - '0') & 0xf) << 4; 43 /* 44 * LSB 45 */ 46 if ((val[1] >= 'a') && (val[1] <= 'f')) 47 result |= ((val[1] - 'a' + 10) & 0xf); 48 else 49 if ((val[1] >= 'A') && (val[1] <= 'F')) 50 result |= ((val[1] - 'A' + 10) & 0xf); 51 else /* digit */ 52 result |= ((val[1] - '0') & 0xf); 53 54 return result; 55 } 56 57 static int chap_string_to_hex(unsigned char *dst, unsigned char *src, int len) 58 { 59 int i, j = 0; 60 61 for (i = 0; i < len; i += 2) { 62 dst[j++] = (unsigned char) chap_asciihex_to_binaryhex(&src[i]); 63 } 64 65 dst[j] = '\0'; 66 return j; 67 } 68 69 static void chap_binaryhex_to_asciihex(char *dst, char *src, int src_len) 70 { 71 int i; 72 73 for (i = 0; i < src_len; i++) { 74 sprintf(&dst[i*2], "%02x", (int) src[i] & 0xff); 75 } 76 } 77 78 static void chap_set_random(char *data, int length) 79 { 80 long r; 81 unsigned n; 82 83 while (length > 0) { 84 get_random_bytes(&r, sizeof(long)); 85 r = r ^ (r >> 8); 86 r = r ^ (r >> 4); 87 n = r & 0x7; 88 89 get_random_bytes(&r, sizeof(long)); 90 r = r ^ (r >> 8); 91 r = r ^ (r >> 5); 92 n = (n << 3) | (r & 0x7); 93 94 get_random_bytes(&r, sizeof(long)); 95 r = r ^ (r >> 8); 96 r = r ^ (r >> 5); 97 n = (n << 2) | (r & 0x3); 98 99 *data++ = n; 100 length--; 101 } 102 } 103 104 static void chap_gen_challenge( 105 struct iscsi_conn *conn, 106 int caller, 107 char *c_str, 108 unsigned int *c_len) 109 { 110 unsigned char challenge_asciihex[CHAP_CHALLENGE_LENGTH * 2 + 1]; 111 struct iscsi_chap *chap = (struct iscsi_chap *) conn->auth_protocol; 112 113 memset(challenge_asciihex, 0, CHAP_CHALLENGE_LENGTH * 2 + 1); 114 115 chap_set_random(chap->challenge, CHAP_CHALLENGE_LENGTH); 116 chap_binaryhex_to_asciihex(challenge_asciihex, chap->challenge, 117 CHAP_CHALLENGE_LENGTH); 118 /* 119 * Set CHAP_C, and copy the generated challenge into c_str. 120 */ 121 *c_len += sprintf(c_str + *c_len, "CHAP_C=0x%s", challenge_asciihex); 122 *c_len += 1; 123 124 pr_debug("[%s] Sending CHAP_C=0x%s\n\n", (caller) ? "server" : "client", 125 challenge_asciihex); 126 } 127 128 129 static struct iscsi_chap *chap_server_open( 130 struct iscsi_conn *conn, 131 struct iscsi_node_auth *auth, 132 const char *a_str, 133 char *aic_str, 134 unsigned int *aic_len) 135 { 136 struct iscsi_chap *chap; 137 138 if (!(auth->naf_flags & NAF_USERID_SET) || 139 !(auth->naf_flags & NAF_PASSWORD_SET)) { 140 pr_err("CHAP user or password not set for" 141 " Initiator ACL\n"); 142 return NULL; 143 } 144 145 conn->auth_protocol = kzalloc(sizeof(struct iscsi_chap), GFP_KERNEL); 146 if (!conn->auth_protocol) 147 return NULL; 148 149 chap = (struct iscsi_chap *) conn->auth_protocol; 150 /* 151 * We only support MD5 MDA presently. 152 */ 153 if (strncmp(a_str, "CHAP_A=5", 8)) { 154 pr_err("CHAP_A is not MD5.\n"); 155 return NULL; 156 } 157 pr_debug("[server] Got CHAP_A=5\n"); 158 /* 159 * Send back CHAP_A set to MD5. 160 */ 161 *aic_len = sprintf(aic_str, "CHAP_A=5"); 162 *aic_len += 1; 163 chap->digest_type = CHAP_DIGEST_MD5; 164 pr_debug("[server] Sending CHAP_A=%d\n", chap->digest_type); 165 /* 166 * Set Identifier. 167 */ 168 chap->id = ISCSI_TPG_C(conn)->tpg_chap_id++; 169 *aic_len += sprintf(aic_str + *aic_len, "CHAP_I=%d", chap->id); 170 *aic_len += 1; 171 pr_debug("[server] Sending CHAP_I=%d\n", chap->id); 172 /* 173 * Generate Challenge. 174 */ 175 chap_gen_challenge(conn, 1, aic_str, aic_len); 176 177 return chap; 178 } 179 180 static void chap_close(struct iscsi_conn *conn) 181 { 182 kfree(conn->auth_protocol); 183 conn->auth_protocol = NULL; 184 } 185 186 static int chap_server_compute_md5( 187 struct iscsi_conn *conn, 188 struct iscsi_node_auth *auth, 189 char *nr_in_ptr, 190 char *nr_out_ptr, 191 unsigned int *nr_out_len) 192 { 193 char *endptr; 194 unsigned char id, digest[MD5_SIGNATURE_SIZE]; 195 unsigned char type, response[MD5_SIGNATURE_SIZE * 2 + 2]; 196 unsigned char identifier[10], *challenge = NULL; 197 unsigned char *challenge_binhex = NULL; 198 unsigned char client_digest[MD5_SIGNATURE_SIZE]; 199 unsigned char server_digest[MD5_SIGNATURE_SIZE]; 200 unsigned char chap_n[MAX_CHAP_N_SIZE], chap_r[MAX_RESPONSE_LENGTH]; 201 struct iscsi_chap *chap = (struct iscsi_chap *) conn->auth_protocol; 202 struct crypto_hash *tfm; 203 struct hash_desc desc; 204 struct scatterlist sg; 205 int auth_ret = -1, ret, challenge_len; 206 207 memset(identifier, 0, 10); 208 memset(chap_n, 0, MAX_CHAP_N_SIZE); 209 memset(chap_r, 0, MAX_RESPONSE_LENGTH); 210 memset(digest, 0, MD5_SIGNATURE_SIZE); 211 memset(response, 0, MD5_SIGNATURE_SIZE * 2 + 2); 212 memset(client_digest, 0, MD5_SIGNATURE_SIZE); 213 memset(server_digest, 0, MD5_SIGNATURE_SIZE); 214 215 challenge = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL); 216 if (!challenge) { 217 pr_err("Unable to allocate challenge buffer\n"); 218 goto out; 219 } 220 221 challenge_binhex = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL); 222 if (!challenge_binhex) { 223 pr_err("Unable to allocate challenge_binhex buffer\n"); 224 goto out; 225 } 226 /* 227 * Extract CHAP_N. 228 */ 229 if (extract_param(nr_in_ptr, "CHAP_N", MAX_CHAP_N_SIZE, chap_n, 230 &type) < 0) { 231 pr_err("Could not find CHAP_N.\n"); 232 goto out; 233 } 234 if (type == HEX) { 235 pr_err("Could not find CHAP_N.\n"); 236 goto out; 237 } 238 239 if (memcmp(chap_n, auth->userid, strlen(auth->userid)) != 0) { 240 pr_err("CHAP_N values do not match!\n"); 241 goto out; 242 } 243 pr_debug("[server] Got CHAP_N=%s\n", chap_n); 244 /* 245 * Extract CHAP_R. 246 */ 247 if (extract_param(nr_in_ptr, "CHAP_R", MAX_RESPONSE_LENGTH, chap_r, 248 &type) < 0) { 249 pr_err("Could not find CHAP_R.\n"); 250 goto out; 251 } 252 if (type != HEX) { 253 pr_err("Could not find CHAP_R.\n"); 254 goto out; 255 } 256 257 pr_debug("[server] Got CHAP_R=%s\n", chap_r); 258 chap_string_to_hex(client_digest, chap_r, strlen(chap_r)); 259 260 tfm = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC); 261 if (IS_ERR(tfm)) { 262 pr_err("Unable to allocate struct crypto_hash\n"); 263 goto out; 264 } 265 desc.tfm = tfm; 266 desc.flags = 0; 267 268 ret = crypto_hash_init(&desc); 269 if (ret < 0) { 270 pr_err("crypto_hash_init() failed\n"); 271 crypto_free_hash(tfm); 272 goto out; 273 } 274 275 sg_init_one(&sg, (void *)&chap->id, 1); 276 ret = crypto_hash_update(&desc, &sg, 1); 277 if (ret < 0) { 278 pr_err("crypto_hash_update() failed for id\n"); 279 crypto_free_hash(tfm); 280 goto out; 281 } 282 283 sg_init_one(&sg, (void *)&auth->password, strlen(auth->password)); 284 ret = crypto_hash_update(&desc, &sg, strlen(auth->password)); 285 if (ret < 0) { 286 pr_err("crypto_hash_update() failed for password\n"); 287 crypto_free_hash(tfm); 288 goto out; 289 } 290 291 sg_init_one(&sg, (void *)chap->challenge, CHAP_CHALLENGE_LENGTH); 292 ret = crypto_hash_update(&desc, &sg, CHAP_CHALLENGE_LENGTH); 293 if (ret < 0) { 294 pr_err("crypto_hash_update() failed for challenge\n"); 295 crypto_free_hash(tfm); 296 goto out; 297 } 298 299 ret = crypto_hash_final(&desc, server_digest); 300 if (ret < 0) { 301 pr_err("crypto_hash_final() failed for server digest\n"); 302 crypto_free_hash(tfm); 303 goto out; 304 } 305 crypto_free_hash(tfm); 306 307 chap_binaryhex_to_asciihex(response, server_digest, MD5_SIGNATURE_SIZE); 308 pr_debug("[server] MD5 Server Digest: %s\n", response); 309 310 if (memcmp(server_digest, client_digest, MD5_SIGNATURE_SIZE) != 0) { 311 pr_debug("[server] MD5 Digests do not match!\n\n"); 312 goto out; 313 } else 314 pr_debug("[server] MD5 Digests match, CHAP connetication" 315 " successful.\n\n"); 316 /* 317 * One way authentication has succeeded, return now if mutual 318 * authentication is not enabled. 319 */ 320 if (!auth->authenticate_target) { 321 kfree(challenge); 322 kfree(challenge_binhex); 323 return 0; 324 } 325 /* 326 * Get CHAP_I. 327 */ 328 if (extract_param(nr_in_ptr, "CHAP_I", 10, identifier, &type) < 0) { 329 pr_err("Could not find CHAP_I.\n"); 330 goto out; 331 } 332 333 if (type == HEX) 334 id = (unsigned char)simple_strtoul((char *)&identifier[2], 335 &endptr, 0); 336 else 337 id = (unsigned char)simple_strtoul(identifier, &endptr, 0); 338 /* 339 * RFC 1994 says Identifier is no more than octet (8 bits). 340 */ 341 pr_debug("[server] Got CHAP_I=%d\n", id); 342 /* 343 * Get CHAP_C. 344 */ 345 if (extract_param(nr_in_ptr, "CHAP_C", CHAP_CHALLENGE_STR_LEN, 346 challenge, &type) < 0) { 347 pr_err("Could not find CHAP_C.\n"); 348 goto out; 349 } 350 351 if (type != HEX) { 352 pr_err("Could not find CHAP_C.\n"); 353 goto out; 354 } 355 pr_debug("[server] Got CHAP_C=%s\n", challenge); 356 challenge_len = chap_string_to_hex(challenge_binhex, challenge, 357 strlen(challenge)); 358 if (!challenge_len) { 359 pr_err("Unable to convert incoming challenge\n"); 360 goto out; 361 } 362 /* 363 * Generate CHAP_N and CHAP_R for mutual authentication. 364 */ 365 tfm = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC); 366 if (IS_ERR(tfm)) { 367 pr_err("Unable to allocate struct crypto_hash\n"); 368 goto out; 369 } 370 desc.tfm = tfm; 371 desc.flags = 0; 372 373 ret = crypto_hash_init(&desc); 374 if (ret < 0) { 375 pr_err("crypto_hash_init() failed\n"); 376 crypto_free_hash(tfm); 377 goto out; 378 } 379 380 sg_init_one(&sg, (void *)&id, 1); 381 ret = crypto_hash_update(&desc, &sg, 1); 382 if (ret < 0) { 383 pr_err("crypto_hash_update() failed for id\n"); 384 crypto_free_hash(tfm); 385 goto out; 386 } 387 388 sg_init_one(&sg, (void *)auth->password_mutual, 389 strlen(auth->password_mutual)); 390 ret = crypto_hash_update(&desc, &sg, strlen(auth->password_mutual)); 391 if (ret < 0) { 392 pr_err("crypto_hash_update() failed for" 393 " password_mutual\n"); 394 crypto_free_hash(tfm); 395 goto out; 396 } 397 /* 398 * Convert received challenge to binary hex. 399 */ 400 sg_init_one(&sg, (void *)challenge_binhex, challenge_len); 401 ret = crypto_hash_update(&desc, &sg, challenge_len); 402 if (ret < 0) { 403 pr_err("crypto_hash_update() failed for ma challenge\n"); 404 crypto_free_hash(tfm); 405 goto out; 406 } 407 408 ret = crypto_hash_final(&desc, digest); 409 if (ret < 0) { 410 pr_err("crypto_hash_final() failed for ma digest\n"); 411 crypto_free_hash(tfm); 412 goto out; 413 } 414 crypto_free_hash(tfm); 415 /* 416 * Generate CHAP_N and CHAP_R. 417 */ 418 *nr_out_len = sprintf(nr_out_ptr, "CHAP_N=%s", auth->userid_mutual); 419 *nr_out_len += 1; 420 pr_debug("[server] Sending CHAP_N=%s\n", auth->userid_mutual); 421 /* 422 * Convert response from binary hex to ascii hext. 423 */ 424 chap_binaryhex_to_asciihex(response, digest, MD5_SIGNATURE_SIZE); 425 *nr_out_len += sprintf(nr_out_ptr + *nr_out_len, "CHAP_R=0x%s", 426 response); 427 *nr_out_len += 1; 428 pr_debug("[server] Sending CHAP_R=0x%s\n", response); 429 auth_ret = 0; 430 out: 431 kfree(challenge); 432 kfree(challenge_binhex); 433 return auth_ret; 434 } 435 436 static int chap_got_response( 437 struct iscsi_conn *conn, 438 struct iscsi_node_auth *auth, 439 char *nr_in_ptr, 440 char *nr_out_ptr, 441 unsigned int *nr_out_len) 442 { 443 struct iscsi_chap *chap = (struct iscsi_chap *) conn->auth_protocol; 444 445 switch (chap->digest_type) { 446 case CHAP_DIGEST_MD5: 447 if (chap_server_compute_md5(conn, auth, nr_in_ptr, 448 nr_out_ptr, nr_out_len) < 0) 449 return -1; 450 return 0; 451 default: 452 pr_err("Unknown CHAP digest type %d!\n", 453 chap->digest_type); 454 return -1; 455 } 456 } 457 458 u32 chap_main_loop( 459 struct iscsi_conn *conn, 460 struct iscsi_node_auth *auth, 461 char *in_text, 462 char *out_text, 463 int *in_len, 464 int *out_len) 465 { 466 struct iscsi_chap *chap = (struct iscsi_chap *) conn->auth_protocol; 467 468 if (!chap) { 469 chap = chap_server_open(conn, auth, in_text, out_text, out_len); 470 if (!chap) 471 return 2; 472 chap->chap_state = CHAP_STAGE_SERVER_AIC; 473 return 0; 474 } else if (chap->chap_state == CHAP_STAGE_SERVER_AIC) { 475 convert_null_to_semi(in_text, *in_len); 476 if (chap_got_response(conn, auth, in_text, out_text, 477 out_len) < 0) { 478 chap_close(conn); 479 return 2; 480 } 481 if (auth->authenticate_target) 482 chap->chap_state = CHAP_STAGE_SERVER_NR; 483 else 484 *out_len = 0; 485 chap_close(conn); 486 return 1; 487 } 488 489 return 2; 490 } 491