drivers/target/iscsi/iscsi_target_auth.c

   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         kzfree(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 }