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 id_as_uchar; 170 unsigned char digest[MD5_SIGNATURE_SIZE]; 171 unsigned char type, response[MD5_SIGNATURE_SIZE * 2 + 2]; 172 unsigned char identifier[10], *challenge = NULL; 173 unsigned char *challenge_binhex = NULL; 174 unsigned char client_digest[MD5_SIGNATURE_SIZE]; 175 unsigned char server_digest[MD5_SIGNATURE_SIZE]; 176 unsigned char chap_n[MAX_CHAP_N_SIZE], chap_r[MAX_RESPONSE_LENGTH]; 177 struct iscsi_chap *chap = conn->auth_protocol; 178 struct crypto_hash *tfm; 179 struct hash_desc desc; 180 struct scatterlist sg; 181 int auth_ret = -1, ret, challenge_len; 182 183 memset(identifier, 0, 10); 184 memset(chap_n, 0, MAX_CHAP_N_SIZE); 185 memset(chap_r, 0, MAX_RESPONSE_LENGTH); 186 memset(digest, 0, MD5_SIGNATURE_SIZE); 187 memset(response, 0, MD5_SIGNATURE_SIZE * 2 + 2); 188 memset(client_digest, 0, MD5_SIGNATURE_SIZE); 189 memset(server_digest, 0, MD5_SIGNATURE_SIZE); 190 191 challenge = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL); 192 if (!challenge) { 193 pr_err("Unable to allocate challenge buffer\n"); 194 goto out; 195 } 196 197 challenge_binhex = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL); 198 if (!challenge_binhex) { 199 pr_err("Unable to allocate challenge_binhex buffer\n"); 200 goto out; 201 } 202 /* 203 * Extract CHAP_N. 204 */ 205 if (extract_param(nr_in_ptr, "CHAP_N", MAX_CHAP_N_SIZE, chap_n, 206 &type) < 0) { 207 pr_err("Could not find CHAP_N.\n"); 208 goto out; 209 } 210 if (type == HEX) { 211 pr_err("Could not find CHAP_N.\n"); 212 goto out; 213 } 214 215 if (memcmp(chap_n, auth->userid, strlen(auth->userid)) != 0) { 216 pr_err("CHAP_N values do not match!\n"); 217 goto out; 218 } 219 pr_debug("[server] Got CHAP_N=%s\n", chap_n); 220 /* 221 * Extract CHAP_R. 222 */ 223 if (extract_param(nr_in_ptr, "CHAP_R", MAX_RESPONSE_LENGTH, chap_r, 224 &type) < 0) { 225 pr_err("Could not find CHAP_R.\n"); 226 goto out; 227 } 228 if (type != HEX) { 229 pr_err("Could not find CHAP_R.\n"); 230 goto out; 231 } 232 233 pr_debug("[server] Got CHAP_R=%s\n", chap_r); 234 chap_string_to_hex(client_digest, chap_r, strlen(chap_r)); 235 236 tfm = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC); 237 if (IS_ERR(tfm)) { 238 pr_err("Unable to allocate struct crypto_hash\n"); 239 goto out; 240 } 241 desc.tfm = tfm; 242 desc.flags = 0; 243 244 ret = crypto_hash_init(&desc); 245 if (ret < 0) { 246 pr_err("crypto_hash_init() failed\n"); 247 crypto_free_hash(tfm); 248 goto out; 249 } 250 251 sg_init_one(&sg, &chap->id, 1); 252 ret = crypto_hash_update(&desc, &sg, 1); 253 if (ret < 0) { 254 pr_err("crypto_hash_update() failed for id\n"); 255 crypto_free_hash(tfm); 256 goto out; 257 } 258 259 sg_init_one(&sg, &auth->password, strlen(auth->password)); 260 ret = crypto_hash_update(&desc, &sg, strlen(auth->password)); 261 if (ret < 0) { 262 pr_err("crypto_hash_update() failed for password\n"); 263 crypto_free_hash(tfm); 264 goto out; 265 } 266 267 sg_init_one(&sg, chap->challenge, CHAP_CHALLENGE_LENGTH); 268 ret = crypto_hash_update(&desc, &sg, CHAP_CHALLENGE_LENGTH); 269 if (ret < 0) { 270 pr_err("crypto_hash_update() failed for challenge\n"); 271 crypto_free_hash(tfm); 272 goto out; 273 } 274 275 ret = crypto_hash_final(&desc, server_digest); 276 if (ret < 0) { 277 pr_err("crypto_hash_final() failed for server digest\n"); 278 crypto_free_hash(tfm); 279 goto out; 280 } 281 crypto_free_hash(tfm); 282 283 chap_binaryhex_to_asciihex(response, server_digest, MD5_SIGNATURE_SIZE); 284 pr_debug("[server] MD5 Server Digest: %s\n", response); 285 286 if (memcmp(server_digest, client_digest, MD5_SIGNATURE_SIZE) != 0) { 287 pr_debug("[server] MD5 Digests do not match!\n\n"); 288 goto out; 289 } else 290 pr_debug("[server] MD5 Digests match, CHAP connetication" 291 " successful.\n\n"); 292 /* 293 * One way authentication has succeeded, return now if mutual 294 * authentication is not enabled. 295 */ 296 if (!auth->authenticate_target) { 297 kfree(challenge); 298 kfree(challenge_binhex); 299 return 0; 300 } 301 /* 302 * Get CHAP_I. 303 */ 304 if (extract_param(nr_in_ptr, "CHAP_I", 10, identifier, &type) < 0) { 305 pr_err("Could not find CHAP_I.\n"); 306 goto out; 307 } 308 309 if (type == HEX) 310 id = simple_strtoul(&identifier[2], &endptr, 0); 311 else 312 id = simple_strtoul(identifier, &endptr, 0); 313 if (id > 255) { 314 pr_err("chap identifier: %lu greater than 255\n", id); 315 goto out; 316 } 317 /* 318 * RFC 1994 says Identifier is no more than octet (8 bits). 319 */ 320 pr_debug("[server] Got CHAP_I=%lu\n", id); 321 /* 322 * Get CHAP_C. 323 */ 324 if (extract_param(nr_in_ptr, "CHAP_C", CHAP_CHALLENGE_STR_LEN, 325 challenge, &type) < 0) { 326 pr_err("Could not find CHAP_C.\n"); 327 goto out; 328 } 329 330 if (type != HEX) { 331 pr_err("Could not find CHAP_C.\n"); 332 goto out; 333 } 334 pr_debug("[server] Got CHAP_C=%s\n", challenge); 335 challenge_len = chap_string_to_hex(challenge_binhex, challenge, 336 strlen(challenge)); 337 if (!challenge_len) { 338 pr_err("Unable to convert incoming challenge\n"); 339 goto out; 340 } 341 /* 342 * Generate CHAP_N and CHAP_R for mutual authentication. 343 */ 344 tfm = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC); 345 if (IS_ERR(tfm)) { 346 pr_err("Unable to allocate struct crypto_hash\n"); 347 goto out; 348 } 349 desc.tfm = tfm; 350 desc.flags = 0; 351 352 ret = crypto_hash_init(&desc); 353 if (ret < 0) { 354 pr_err("crypto_hash_init() failed\n"); 355 crypto_free_hash(tfm); 356 goto out; 357 } 358 359 /* To handle both endiannesses */ 360 id_as_uchar = id; 361 sg_init_one(&sg, &id_as_uchar, 1); 362 ret = crypto_hash_update(&desc, &sg, 1); 363 if (ret < 0) { 364 pr_err("crypto_hash_update() failed for id\n"); 365 crypto_free_hash(tfm); 366 goto out; 367 } 368 369 sg_init_one(&sg, auth->password_mutual, 370 strlen(auth->password_mutual)); 371 ret = crypto_hash_update(&desc, &sg, strlen(auth->password_mutual)); 372 if (ret < 0) { 373 pr_err("crypto_hash_update() failed for" 374 " password_mutual\n"); 375 crypto_free_hash(tfm); 376 goto out; 377 } 378 /* 379 * Convert received challenge to binary hex. 380 */ 381 sg_init_one(&sg, challenge_binhex, challenge_len); 382 ret = crypto_hash_update(&desc, &sg, challenge_len); 383 if (ret < 0) { 384 pr_err("crypto_hash_update() failed for ma challenge\n"); 385 crypto_free_hash(tfm); 386 goto out; 387 } 388 389 ret = crypto_hash_final(&desc, digest); 390 if (ret < 0) { 391 pr_err("crypto_hash_final() failed for ma digest\n"); 392 crypto_free_hash(tfm); 393 goto out; 394 } 395 crypto_free_hash(tfm); 396 /* 397 * Generate CHAP_N and CHAP_R. 398 */ 399 *nr_out_len = sprintf(nr_out_ptr, "CHAP_N=%s", auth->userid_mutual); 400 *nr_out_len += 1; 401 pr_debug("[server] Sending CHAP_N=%s\n", auth->userid_mutual); 402 /* 403 * Convert response from binary hex to ascii hext. 404 */ 405 chap_binaryhex_to_asciihex(response, digest, MD5_SIGNATURE_SIZE); 406 *nr_out_len += sprintf(nr_out_ptr + *nr_out_len, "CHAP_R=0x%s", 407 response); 408 *nr_out_len += 1; 409 pr_debug("[server] Sending CHAP_R=0x%s\n", response); 410 auth_ret = 0; 411 out: 412 kfree(challenge); 413 kfree(challenge_binhex); 414 return auth_ret; 415 } 416 417 static int chap_got_response( 418 struct iscsi_conn *conn, 419 struct iscsi_node_auth *auth, 420 char *nr_in_ptr, 421 char *nr_out_ptr, 422 unsigned int *nr_out_len) 423 { 424 struct iscsi_chap *chap = conn->auth_protocol; 425 426 switch (chap->digest_type) { 427 case CHAP_DIGEST_MD5: 428 if (chap_server_compute_md5(conn, auth, nr_in_ptr, 429 nr_out_ptr, nr_out_len) < 0) 430 return -1; 431 return 0; 432 default: 433 pr_err("Unknown CHAP digest type %d!\n", 434 chap->digest_type); 435 return -1; 436 } 437 } 438 439 u32 chap_main_loop( 440 struct iscsi_conn *conn, 441 struct iscsi_node_auth *auth, 442 char *in_text, 443 char *out_text, 444 int *in_len, 445 int *out_len) 446 { 447 struct iscsi_chap *chap = conn->auth_protocol; 448 449 if (!chap) { 450 chap = chap_server_open(conn, auth, in_text, out_text, out_len); 451 if (!chap) 452 return 2; 453 chap->chap_state = CHAP_STAGE_SERVER_AIC; 454 return 0; 455 } else if (chap->chap_state == CHAP_STAGE_SERVER_AIC) { 456 convert_null_to_semi(in_text, *in_len); 457 if (chap_got_response(conn, auth, in_text, out_text, 458 out_len) < 0) { 459 chap_close(conn); 460 return 2; 461 } 462 if (auth->authenticate_target) 463 chap->chap_state = CHAP_STAGE_SERVER_NR; 464 else 465 *out_len = 0; 466 chap_close(conn); 467 return 1; 468 } 469 470 return 2; 471 } 472