drivers/target/iscsi/iscsi_target_auth.c

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