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 = ISCSI_TPG_C(conn)->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 struct iscsi_chap *chap = conn->auth_protocol; 150 struct crypto_hash *tfm; 151 struct hash_desc desc; 152 struct scatterlist sg; 153 int auth_ret = -1, ret, challenge_len; 154 155 memset(identifier, 0, 10); 156 memset(chap_n, 0, MAX_CHAP_N_SIZE); 157 memset(chap_r, 0, MAX_RESPONSE_LENGTH); 158 memset(digest, 0, MD5_SIGNATURE_SIZE); 159 memset(response, 0, MD5_SIGNATURE_SIZE * 2 + 2); 160 memset(client_digest, 0, MD5_SIGNATURE_SIZE); 161 memset(server_digest, 0, MD5_SIGNATURE_SIZE); 162 163 challenge = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL); 164 if (!challenge) { 165 pr_err("Unable to allocate challenge buffer\n"); 166 goto out; 167 } 168 169 challenge_binhex = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL); 170 if (!challenge_binhex) { 171 pr_err("Unable to allocate challenge_binhex buffer\n"); 172 goto out; 173 } 174 /* 175 * Extract CHAP_N. 176 */ 177 if (extract_param(nr_in_ptr, "CHAP_N", MAX_CHAP_N_SIZE, chap_n, 178 &type) < 0) { 179 pr_err("Could not find CHAP_N.\n"); 180 goto out; 181 } 182 if (type == HEX) { 183 pr_err("Could not find CHAP_N.\n"); 184 goto out; 185 } 186 187 if (memcmp(chap_n, auth->userid, strlen(auth->userid)) != 0) { 188 pr_err("CHAP_N values do not match!\n"); 189 goto out; 190 } 191 pr_debug("[server] Got CHAP_N=%s\n", chap_n); 192 /* 193 * Extract CHAP_R. 194 */ 195 if (extract_param(nr_in_ptr, "CHAP_R", MAX_RESPONSE_LENGTH, chap_r, 196 &type) < 0) { 197 pr_err("Could not find CHAP_R.\n"); 198 goto out; 199 } 200 if (type != HEX) { 201 pr_err("Could not find CHAP_R.\n"); 202 goto out; 203 } 204 205 pr_debug("[server] Got CHAP_R=%s\n", chap_r); 206 chap_string_to_hex(client_digest, chap_r, strlen(chap_r)); 207 208 tfm = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC); 209 if (IS_ERR(tfm)) { 210 pr_err("Unable to allocate struct crypto_hash\n"); 211 goto out; 212 } 213 desc.tfm = tfm; 214 desc.flags = 0; 215 216 ret = crypto_hash_init(&desc); 217 if (ret < 0) { 218 pr_err("crypto_hash_init() failed\n"); 219 crypto_free_hash(tfm); 220 goto out; 221 } 222 223 sg_init_one(&sg, &chap->id, 1); 224 ret = crypto_hash_update(&desc, &sg, 1); 225 if (ret < 0) { 226 pr_err("crypto_hash_update() failed for id\n"); 227 crypto_free_hash(tfm); 228 goto out; 229 } 230 231 sg_init_one(&sg, &auth->password, strlen(auth->password)); 232 ret = crypto_hash_update(&desc, &sg, strlen(auth->password)); 233 if (ret < 0) { 234 pr_err("crypto_hash_update() failed for password\n"); 235 crypto_free_hash(tfm); 236 goto out; 237 } 238 239 sg_init_one(&sg, chap->challenge, CHAP_CHALLENGE_LENGTH); 240 ret = crypto_hash_update(&desc, &sg, CHAP_CHALLENGE_LENGTH); 241 if (ret < 0) { 242 pr_err("crypto_hash_update() failed for challenge\n"); 243 crypto_free_hash(tfm); 244 goto out; 245 } 246 247 ret = crypto_hash_final(&desc, server_digest); 248 if (ret < 0) { 249 pr_err("crypto_hash_final() failed for server digest\n"); 250 crypto_free_hash(tfm); 251 goto out; 252 } 253 crypto_free_hash(tfm); 254 255 chap_binaryhex_to_asciihex(response, server_digest, MD5_SIGNATURE_SIZE); 256 pr_debug("[server] MD5 Server Digest: %s\n", response); 257 258 if (memcmp(server_digest, client_digest, MD5_SIGNATURE_SIZE) != 0) { 259 pr_debug("[server] MD5 Digests do not match!\n\n"); 260 goto out; 261 } else 262 pr_debug("[server] MD5 Digests match, CHAP connetication" 263 " successful.\n\n"); 264 /* 265 * One way authentication has succeeded, return now if mutual 266 * authentication is not enabled. 267 */ 268 if (!auth->authenticate_target) { 269 kfree(challenge); 270 kfree(challenge_binhex); 271 return 0; 272 } 273 /* 274 * Get CHAP_I. 275 */ 276 if (extract_param(nr_in_ptr, "CHAP_I", 10, identifier, &type) < 0) { 277 pr_err("Could not find CHAP_I.\n"); 278 goto out; 279 } 280 281 if (type == HEX) 282 id = simple_strtoul(&identifier[2], &endptr, 0); 283 else 284 id = simple_strtoul(identifier, &endptr, 0); 285 if (id > 255) { 286 pr_err("chap identifier: %lu greater than 255\n", id); 287 goto out; 288 } 289 /* 290 * RFC 1994 says Identifier is no more than octet (8 bits). 291 */ 292 pr_debug("[server] Got CHAP_I=%lu\n", id); 293 /* 294 * Get CHAP_C. 295 */ 296 if (extract_param(nr_in_ptr, "CHAP_C", CHAP_CHALLENGE_STR_LEN, 297 challenge, &type) < 0) { 298 pr_err("Could not find CHAP_C.\n"); 299 goto out; 300 } 301 302 if (type != HEX) { 303 pr_err("Could not find CHAP_C.\n"); 304 goto out; 305 } 306 pr_debug("[server] Got CHAP_C=%s\n", challenge); 307 challenge_len = chap_string_to_hex(challenge_binhex, challenge, 308 strlen(challenge)); 309 if (!challenge_len) { 310 pr_err("Unable to convert incoming challenge\n"); 311 goto out; 312 } 313 /* 314 * Generate CHAP_N and CHAP_R for mutual authentication. 315 */ 316 tfm = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC); 317 if (IS_ERR(tfm)) { 318 pr_err("Unable to allocate struct crypto_hash\n"); 319 goto out; 320 } 321 desc.tfm = tfm; 322 desc.flags = 0; 323 324 ret = crypto_hash_init(&desc); 325 if (ret < 0) { 326 pr_err("crypto_hash_init() failed\n"); 327 crypto_free_hash(tfm); 328 goto out; 329 } 330 331 /* To handle both endiannesses */ 332 id_as_uchar = id; 333 sg_init_one(&sg, &id_as_uchar, 1); 334 ret = crypto_hash_update(&desc, &sg, 1); 335 if (ret < 0) { 336 pr_err("crypto_hash_update() failed for id\n"); 337 crypto_free_hash(tfm); 338 goto out; 339 } 340 341 sg_init_one(&sg, auth->password_mutual, 342 strlen(auth->password_mutual)); 343 ret = crypto_hash_update(&desc, &sg, strlen(auth->password_mutual)); 344 if (ret < 0) { 345 pr_err("crypto_hash_update() failed for" 346 " password_mutual\n"); 347 crypto_free_hash(tfm); 348 goto out; 349 } 350 /* 351 * Convert received challenge to binary hex. 352 */ 353 sg_init_one(&sg, challenge_binhex, challenge_len); 354 ret = crypto_hash_update(&desc, &sg, challenge_len); 355 if (ret < 0) { 356 pr_err("crypto_hash_update() failed for ma challenge\n"); 357 crypto_free_hash(tfm); 358 goto out; 359 } 360 361 ret = crypto_hash_final(&desc, digest); 362 if (ret < 0) { 363 pr_err("crypto_hash_final() failed for ma digest\n"); 364 crypto_free_hash(tfm); 365 goto out; 366 } 367 crypto_free_hash(tfm); 368 /* 369 * Generate CHAP_N and CHAP_R. 370 */ 371 *nr_out_len = sprintf(nr_out_ptr, "CHAP_N=%s", auth->userid_mutual); 372 *nr_out_len += 1; 373 pr_debug("[server] Sending CHAP_N=%s\n", auth->userid_mutual); 374 /* 375 * Convert response from binary hex to ascii hext. 376 */ 377 chap_binaryhex_to_asciihex(response, digest, MD5_SIGNATURE_SIZE); 378 *nr_out_len += sprintf(nr_out_ptr + *nr_out_len, "CHAP_R=0x%s", 379 response); 380 *nr_out_len += 1; 381 pr_debug("[server] Sending CHAP_R=0x%s\n", response); 382 auth_ret = 0; 383 out: 384 kfree(challenge); 385 kfree(challenge_binhex); 386 return auth_ret; 387 } 388 389 static int chap_got_response( 390 struct iscsi_conn *conn, 391 struct iscsi_node_auth *auth, 392 char *nr_in_ptr, 393 char *nr_out_ptr, 394 unsigned int *nr_out_len) 395 { 396 struct iscsi_chap *chap = conn->auth_protocol; 397 398 switch (chap->digest_type) { 399 case CHAP_DIGEST_MD5: 400 if (chap_server_compute_md5(conn, auth, nr_in_ptr, 401 nr_out_ptr, nr_out_len) < 0) 402 return -1; 403 return 0; 404 default: 405 pr_err("Unknown CHAP digest type %d!\n", 406 chap->digest_type); 407 return -1; 408 } 409 } 410 411 u32 chap_main_loop( 412 struct iscsi_conn *conn, 413 struct iscsi_node_auth *auth, 414 char *in_text, 415 char *out_text, 416 int *in_len, 417 int *out_len) 418 { 419 struct iscsi_chap *chap = conn->auth_protocol; 420 421 if (!chap) { 422 chap = chap_server_open(conn, auth, in_text, out_text, out_len); 423 if (!chap) 424 return 2; 425 chap->chap_state = CHAP_STAGE_SERVER_AIC; 426 return 0; 427 } else if (chap->chap_state == CHAP_STAGE_SERVER_AIC) { 428 convert_null_to_semi(in_text, *in_len); 429 if (chap_got_response(conn, auth, in_text, out_text, 430 out_len) < 0) { 431 chap_close(conn); 432 return 2; 433 } 434 if (auth->authenticate_target) 435 chap->chap_state = CHAP_STAGE_SERVER_NR; 436 else 437 *out_len = 0; 438 chap_close(conn); 439 return 1; 440 } 441 442 return 2; 443 } 444