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