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/kernel.h> 22 #include <linux/string.h> 23 #include <linux/crypto.h> 24 #include <linux/err.h> 25 #include <linux/scatterlist.h> 26 27 #include "iscsi_target_core.h" 28 #include "iscsi_target_nego.h" 29 #include "iscsi_target_auth.h" 30 31 static int chap_string_to_hex(unsigned char *dst, unsigned char *src, int len) 32 { 33 int j = DIV_ROUND_UP(len, 2), rc; 34 35 rc = hex2bin(dst, src, j); 36 if (rc < 0) 37 pr_debug("CHAP string contains non hex digit symbols\n"); 38 39 dst[j] = '\0'; 40 return j; 41 } 42 43 static void chap_binaryhex_to_asciihex(char *dst, char *src, int src_len) 44 { 45 int i; 46 47 for (i = 0; i < src_len; i++) { 48 sprintf(&dst[i*2], "%02x", (int) src[i] & 0xff); 49 } 50 } 51 52 static void chap_set_random(char *data, int length) 53 { 54 long r; 55 unsigned n; 56 57 while (length > 0) { 58 get_random_bytes(&r, sizeof(long)); 59 r = r ^ (r >> 8); 60 r = r ^ (r >> 4); 61 n = r & 0x7; 62 63 get_random_bytes(&r, sizeof(long)); 64 r = r ^ (r >> 8); 65 r = r ^ (r >> 5); 66 n = (n << 3) | (r & 0x7); 67 68 get_random_bytes(&r, sizeof(long)); 69 r = r ^ (r >> 8); 70 r = r ^ (r >> 5); 71 n = (n << 2) | (r & 0x3); 72 73 *data++ = n; 74 length--; 75 } 76 } 77 78 static void chap_gen_challenge( 79 struct iscsi_conn *conn, 80 int caller, 81 char *c_str, 82 unsigned int *c_len) 83 { 84 unsigned char challenge_asciihex[CHAP_CHALLENGE_LENGTH * 2 + 1]; 85 struct iscsi_chap *chap = conn->auth_protocol; 86 87 memset(challenge_asciihex, 0, CHAP_CHALLENGE_LENGTH * 2 + 1); 88 89 chap_set_random(chap->challenge, CHAP_CHALLENGE_LENGTH); 90 chap_binaryhex_to_asciihex(challenge_asciihex, chap->challenge, 91 CHAP_CHALLENGE_LENGTH); 92 /* 93 * Set CHAP_C, and copy the generated challenge into c_str. 94 */ 95 *c_len += sprintf(c_str + *c_len, "CHAP_C=0x%s", challenge_asciihex); 96 *c_len += 1; 97 98 pr_debug("[%s] Sending CHAP_C=0x%s\n\n", (caller) ? "server" : "client", 99 challenge_asciihex); 100 } 101 102 103 static struct iscsi_chap *chap_server_open( 104 struct iscsi_conn *conn, 105 struct iscsi_node_auth *auth, 106 const char *a_str, 107 char *aic_str, 108 unsigned int *aic_len) 109 { 110 struct iscsi_chap *chap; 111 112 if (!(auth->naf_flags & NAF_USERID_SET) || 113 !(auth->naf_flags & NAF_PASSWORD_SET)) { 114 pr_err("CHAP user or password not set for" 115 " Initiator ACL\n"); 116 return NULL; 117 } 118 119 conn->auth_protocol = kzalloc(sizeof(struct iscsi_chap), GFP_KERNEL); 120 if (!conn->auth_protocol) 121 return NULL; 122 123 chap = conn->auth_protocol; 124 /* 125 * We only support MD5 MDA presently. 126 */ 127 if (strncmp(a_str, "CHAP_A=5", 8)) { 128 pr_err("CHAP_A is not MD5.\n"); 129 return NULL; 130 } 131 pr_debug("[server] Got CHAP_A=5\n"); 132 /* 133 * Send back CHAP_A set to MD5. 134 */ 135 *aic_len = sprintf(aic_str, "CHAP_A=5"); 136 *aic_len += 1; 137 chap->digest_type = CHAP_DIGEST_MD5; 138 pr_debug("[server] Sending CHAP_A=%d\n", chap->digest_type); 139 /* 140 * Set Identifier. 141 */ 142 chap->id = ISCSI_TPG_C(conn)->tpg_chap_id++; 143 *aic_len += sprintf(aic_str + *aic_len, "CHAP_I=%d", chap->id); 144 *aic_len += 1; 145 pr_debug("[server] Sending CHAP_I=%d\n", chap->id); 146 /* 147 * Generate Challenge. 148 */ 149 chap_gen_challenge(conn, 1, aic_str, aic_len); 150 151 return chap; 152 } 153 154 static void chap_close(struct iscsi_conn *conn) 155 { 156 kfree(conn->auth_protocol); 157 conn->auth_protocol = NULL; 158 } 159 160 static int chap_server_compute_md5( 161 struct iscsi_conn *conn, 162 struct iscsi_node_auth *auth, 163 char *nr_in_ptr, 164 char *nr_out_ptr, 165 unsigned int *nr_out_len) 166 { 167 char *endptr; 168 unsigned long id; 169 unsigned char digest[MD5_SIGNATURE_SIZE]; 170 unsigned char type, response[MD5_SIGNATURE_SIZE * 2 + 2]; 171 unsigned char identifier[10], *challenge = NULL; 172 unsigned char *challenge_binhex = NULL; 173 unsigned char client_digest[MD5_SIGNATURE_SIZE]; 174 unsigned char server_digest[MD5_SIGNATURE_SIZE]; 175 unsigned char chap_n[MAX_CHAP_N_SIZE], chap_r[MAX_RESPONSE_LENGTH]; 176 struct iscsi_chap *chap = conn->auth_protocol; 177 struct crypto_hash *tfm; 178 struct hash_desc desc; 179 struct scatterlist sg; 180 int auth_ret = -1, ret, challenge_len; 181 182 memset(identifier, 0, 10); 183 memset(chap_n, 0, MAX_CHAP_N_SIZE); 184 memset(chap_r, 0, MAX_RESPONSE_LENGTH); 185 memset(digest, 0, MD5_SIGNATURE_SIZE); 186 memset(response, 0, MD5_SIGNATURE_SIZE * 2 + 2); 187 memset(client_digest, 0, MD5_SIGNATURE_SIZE); 188 memset(server_digest, 0, MD5_SIGNATURE_SIZE); 189 190 challenge = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL); 191 if (!challenge) { 192 pr_err("Unable to allocate challenge buffer\n"); 193 goto out; 194 } 195 196 challenge_binhex = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL); 197 if (!challenge_binhex) { 198 pr_err("Unable to allocate challenge_binhex buffer\n"); 199 goto out; 200 } 201 /* 202 * Extract CHAP_N. 203 */ 204 if (extract_param(nr_in_ptr, "CHAP_N", MAX_CHAP_N_SIZE, chap_n, 205 &type) < 0) { 206 pr_err("Could not find CHAP_N.\n"); 207 goto out; 208 } 209 if (type == HEX) { 210 pr_err("Could not find CHAP_N.\n"); 211 goto out; 212 } 213 214 if (memcmp(chap_n, auth->userid, strlen(auth->userid)) != 0) { 215 pr_err("CHAP_N values do not match!\n"); 216 goto out; 217 } 218 pr_debug("[server] Got CHAP_N=%s\n", chap_n); 219 /* 220 * Extract CHAP_R. 221 */ 222 if (extract_param(nr_in_ptr, "CHAP_R", MAX_RESPONSE_LENGTH, chap_r, 223 &type) < 0) { 224 pr_err("Could not find CHAP_R.\n"); 225 goto out; 226 } 227 if (type != HEX) { 228 pr_err("Could not find CHAP_R.\n"); 229 goto out; 230 } 231 232 pr_debug("[server] Got CHAP_R=%s\n", chap_r); 233 chap_string_to_hex(client_digest, chap_r, strlen(chap_r)); 234 235 tfm = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC); 236 if (IS_ERR(tfm)) { 237 pr_err("Unable to allocate struct crypto_hash\n"); 238 goto out; 239 } 240 desc.tfm = tfm; 241 desc.flags = 0; 242 243 ret = crypto_hash_init(&desc); 244 if (ret < 0) { 245 pr_err("crypto_hash_init() failed\n"); 246 crypto_free_hash(tfm); 247 goto out; 248 } 249 250 sg_init_one(&sg, &chap->id, 1); 251 ret = crypto_hash_update(&desc, &sg, 1); 252 if (ret < 0) { 253 pr_err("crypto_hash_update() failed for id\n"); 254 crypto_free_hash(tfm); 255 goto out; 256 } 257 258 sg_init_one(&sg, &auth->password, strlen(auth->password)); 259 ret = crypto_hash_update(&desc, &sg, strlen(auth->password)); 260 if (ret < 0) { 261 pr_err("crypto_hash_update() failed for password\n"); 262 crypto_free_hash(tfm); 263 goto out; 264 } 265 266 sg_init_one(&sg, chap->challenge, CHAP_CHALLENGE_LENGTH); 267 ret = crypto_hash_update(&desc, &sg, CHAP_CHALLENGE_LENGTH); 268 if (ret < 0) { 269 pr_err("crypto_hash_update() failed for challenge\n"); 270 crypto_free_hash(tfm); 271 goto out; 272 } 273 274 ret = crypto_hash_final(&desc, server_digest); 275 if (ret < 0) { 276 pr_err("crypto_hash_final() failed for server digest\n"); 277 crypto_free_hash(tfm); 278 goto out; 279 } 280 crypto_free_hash(tfm); 281 282 chap_binaryhex_to_asciihex(response, server_digest, MD5_SIGNATURE_SIZE); 283 pr_debug("[server] MD5 Server Digest: %s\n", response); 284 285 if (memcmp(server_digest, client_digest, MD5_SIGNATURE_SIZE) != 0) { 286 pr_debug("[server] MD5 Digests do not match!\n\n"); 287 goto out; 288 } else 289 pr_debug("[server] MD5 Digests match, CHAP connetication" 290 " successful.\n\n"); 291 /* 292 * One way authentication has succeeded, return now if mutual 293 * authentication is not enabled. 294 */ 295 if (!auth->authenticate_target) { 296 kfree(challenge); 297 kfree(challenge_binhex); 298 return 0; 299 } 300 /* 301 * Get CHAP_I. 302 */ 303 if (extract_param(nr_in_ptr, "CHAP_I", 10, identifier, &type) < 0) { 304 pr_err("Could not find CHAP_I.\n"); 305 goto out; 306 } 307 308 if (type == HEX) 309 id = simple_strtoul(&identifier[2], &endptr, 0); 310 else 311 id = simple_strtoul(identifier, &endptr, 0); 312 if (id > 255) { 313 pr_err("chap identifier: %lu greater than 255\n", id); 314 goto out; 315 } 316 /* 317 * RFC 1994 says Identifier is no more than octet (8 bits). 318 */ 319 pr_debug("[server] Got CHAP_I=%lu\n", id); 320 /* 321 * Get CHAP_C. 322 */ 323 if (extract_param(nr_in_ptr, "CHAP_C", CHAP_CHALLENGE_STR_LEN, 324 challenge, &type) < 0) { 325 pr_err("Could not find CHAP_C.\n"); 326 goto out; 327 } 328 329 if (type != HEX) { 330 pr_err("Could not find CHAP_C.\n"); 331 goto out; 332 } 333 pr_debug("[server] Got CHAP_C=%s\n", challenge); 334 challenge_len = chap_string_to_hex(challenge_binhex, challenge, 335 strlen(challenge)); 336 if (!challenge_len) { 337 pr_err("Unable to convert incoming challenge\n"); 338 goto out; 339 } 340 /* 341 * Generate CHAP_N and CHAP_R for mutual authentication. 342 */ 343 tfm = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC); 344 if (IS_ERR(tfm)) { 345 pr_err("Unable to allocate struct crypto_hash\n"); 346 goto out; 347 } 348 desc.tfm = tfm; 349 desc.flags = 0; 350 351 ret = crypto_hash_init(&desc); 352 if (ret < 0) { 353 pr_err("crypto_hash_init() failed\n"); 354 crypto_free_hash(tfm); 355 goto out; 356 } 357 358 sg_init_one(&sg, &id, 1); 359 ret = crypto_hash_update(&desc, &sg, 1); 360 if (ret < 0) { 361 pr_err("crypto_hash_update() failed for id\n"); 362 crypto_free_hash(tfm); 363 goto out; 364 } 365 366 sg_init_one(&sg, auth->password_mutual, 367 strlen(auth->password_mutual)); 368 ret = crypto_hash_update(&desc, &sg, strlen(auth->password_mutual)); 369 if (ret < 0) { 370 pr_err("crypto_hash_update() failed for" 371 " password_mutual\n"); 372 crypto_free_hash(tfm); 373 goto out; 374 } 375 /* 376 * Convert received challenge to binary hex. 377 */ 378 sg_init_one(&sg, challenge_binhex, challenge_len); 379 ret = crypto_hash_update(&desc, &sg, challenge_len); 380 if (ret < 0) { 381 pr_err("crypto_hash_update() failed for ma challenge\n"); 382 crypto_free_hash(tfm); 383 goto out; 384 } 385 386 ret = crypto_hash_final(&desc, digest); 387 if (ret < 0) { 388 pr_err("crypto_hash_final() failed for ma digest\n"); 389 crypto_free_hash(tfm); 390 goto out; 391 } 392 crypto_free_hash(tfm); 393 /* 394 * Generate CHAP_N and CHAP_R. 395 */ 396 *nr_out_len = sprintf(nr_out_ptr, "CHAP_N=%s", auth->userid_mutual); 397 *nr_out_len += 1; 398 pr_debug("[server] Sending CHAP_N=%s\n", auth->userid_mutual); 399 /* 400 * Convert response from binary hex to ascii hext. 401 */ 402 chap_binaryhex_to_asciihex(response, digest, MD5_SIGNATURE_SIZE); 403 *nr_out_len += sprintf(nr_out_ptr + *nr_out_len, "CHAP_R=0x%s", 404 response); 405 *nr_out_len += 1; 406 pr_debug("[server] Sending CHAP_R=0x%s\n", response); 407 auth_ret = 0; 408 out: 409 kfree(challenge); 410 kfree(challenge_binhex); 411 return auth_ret; 412 } 413 414 static int chap_got_response( 415 struct iscsi_conn *conn, 416 struct iscsi_node_auth *auth, 417 char *nr_in_ptr, 418 char *nr_out_ptr, 419 unsigned int *nr_out_len) 420 { 421 struct iscsi_chap *chap = conn->auth_protocol; 422 423 switch (chap->digest_type) { 424 case CHAP_DIGEST_MD5: 425 if (chap_server_compute_md5(conn, auth, nr_in_ptr, 426 nr_out_ptr, nr_out_len) < 0) 427 return -1; 428 return 0; 429 default: 430 pr_err("Unknown CHAP digest type %d!\n", 431 chap->digest_type); 432 return -1; 433 } 434 } 435 436 u32 chap_main_loop( 437 struct iscsi_conn *conn, 438 struct iscsi_node_auth *auth, 439 char *in_text, 440 char *out_text, 441 int *in_len, 442 int *out_len) 443 { 444 struct iscsi_chap *chap = conn->auth_protocol; 445 446 if (!chap) { 447 chap = chap_server_open(conn, auth, in_text, out_text, out_len); 448 if (!chap) 449 return 2; 450 chap->chap_state = CHAP_STAGE_SERVER_AIC; 451 return 0; 452 } else if (chap->chap_state == CHAP_STAGE_SERVER_AIC) { 453 convert_null_to_semi(in_text, *in_len); 454 if (chap_got_response(conn, auth, in_text, out_text, 455 out_len) < 0) { 456 chap_close(conn); 457 return 2; 458 } 459 if (auth->authenticate_target) 460 chap->chap_state = CHAP_STAGE_SERVER_NR; 461 else 462 *out_len = 0; 463 chap_close(conn); 464 return 1; 465 } 466 467 return 2; 468 } 469