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_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         size_t compare_len;
 178         struct iscsi_chap *chap = conn->auth_protocol;
 179         struct crypto_hash *tfm;
 180         struct hash_desc desc;
 181         struct scatterlist sg;
 182         int auth_ret = -1, ret, challenge_len;
 183
 184         memset(identifier, 0, 10);
 185         memset(chap_n, 0, MAX_CHAP_N_SIZE);
 186         memset(chap_r, 0, MAX_RESPONSE_LENGTH);
 187         memset(digest, 0, MD5_SIGNATURE_SIZE);
 188         memset(response, 0, MD5_SIGNATURE_SIZE * 2 + 2);
 189         memset(client_digest, 0, MD5_SIGNATURE_SIZE);
 190         memset(server_digest, 0, MD5_SIGNATURE_SIZE);
 191
 192         challenge = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL);
 193         if (!challenge) {
 194                 pr_err("Unable to allocate challenge buffer\n");
 195                 goto out;
 196         }
 197
 198         challenge_binhex = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL);
 199         if (!challenge_binhex) {
 200                 pr_err("Unable to allocate challenge_binhex buffer\n");
 201                 goto out;
 202         }
 203         /*
 204          * Extract CHAP_N.
 205          */
 206         if (extract_param(nr_in_ptr, "CHAP_N", MAX_CHAP_N_SIZE, chap_n,
 207                                 &type) < 0) {
 208                 pr_err("Could not find CHAP_N.\n");
 209                 goto out;
 210         }
 211         if (type == HEX) {
 212                 pr_err("Could not find CHAP_N.\n");
 213                 goto out;
 214         }
 215
 216         /* Include the terminating NULL in the compare */
 217         compare_len = strlen(auth->userid) + 1;
 218         if (strncmp(chap_n, auth->userid, compare_len) != 0) {
 219                 pr_err("CHAP_N values do not match!\n");
 220                 goto out;
 221         }
 222         pr_debug("[server] Got CHAP_N=%s\n", chap_n);
 223         /*
 224          * Extract CHAP_R.
 225          */
 226         if (extract_param(nr_in_ptr, "CHAP_R", MAX_RESPONSE_LENGTH, chap_r,
 227                                 &type) < 0) {
 228                 pr_err("Could not find CHAP_R.\n");
 229                 goto out;
 230         }
 231         if (type != HEX) {
 232                 pr_err("Could not find CHAP_R.\n");
 233                 goto out;
 234         }
 235
 236         pr_debug("[server] Got CHAP_R=%s\n", chap_r);
 237         chap_string_to_hex(client_digest, chap_r, strlen(chap_r));
 238
 239         tfm = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC);
 240         if (IS_ERR(tfm)) {
 241                 pr_err("Unable to allocate struct crypto_hash\n");
 242                 goto out;
 243         }
 244         desc.tfm = tfm;
 245         desc.flags = 0;
 246
 247         ret = crypto_hash_init(&desc);
 248         if (ret < 0) {
 249                 pr_err("crypto_hash_init() failed\n");
 250                 crypto_free_hash(tfm);
 251                 goto out;
 252         }
 253
 254         sg_init_one(&sg, &chap->id, 1);
 255         ret = crypto_hash_update(&desc, &sg, 1);
 256         if (ret < 0) {
 257                 pr_err("crypto_hash_update() failed for id\n");
 258                 crypto_free_hash(tfm);
 259                 goto out;
 260         }
 261
 262         sg_init_one(&sg, &auth->password, strlen(auth->password));
 263         ret = crypto_hash_update(&desc, &sg, strlen(auth->password));
 264         if (ret < 0) {
 265                 pr_err("crypto_hash_update() failed for password\n");
 266                 crypto_free_hash(tfm);
 267                 goto out;
 268         }
 269
 270         sg_init_one(&sg, chap->challenge, CHAP_CHALLENGE_LENGTH);
 271         ret = crypto_hash_update(&desc, &sg, CHAP_CHALLENGE_LENGTH);
 272         if (ret < 0) {
 273                 pr_err("crypto_hash_update() failed for challenge\n");
 274                 crypto_free_hash(tfm);
 275                 goto out;
 276         }
 277
 278         ret = crypto_hash_final(&desc, server_digest);
 279         if (ret < 0) {
 280                 pr_err("crypto_hash_final() failed for server digest\n");
 281                 crypto_free_hash(tfm);
 282                 goto out;
 283         }
 284         crypto_free_hash(tfm);
 285
 286         chap_binaryhex_to_asciihex(response, server_digest, MD5_SIGNATURE_SIZE);
 287         pr_debug("[server] MD5 Server Digest: %s\n", response);
 288
 289         if (memcmp(server_digest, client_digest, MD5_SIGNATURE_SIZE) != 0) {
 290                 pr_debug("[server] MD5 Digests do not match!\n\n");
 291                 goto out;
 292         } else
 293                 pr_debug("[server] MD5 Digests match, CHAP connetication"
 294                                 " successful.\n\n");
 295         /*
 296          * One way authentication has succeeded, return now if mutual
 297          * authentication is not enabled.
 298          */
 299         if (!auth->authenticate_target) {
 300                 kfree(challenge);
 301                 kfree(challenge_binhex);
 302                 return 0;
 303         }
 304         /*
 305          * Get CHAP_I.
 306          */
 307         if (extract_param(nr_in_ptr, "CHAP_I", 10, identifier, &type) < 0) {
 308                 pr_err("Could not find CHAP_I.\n");
 309                 goto out;
 310         }
 311
 312         if (type == HEX)
 313                 id = simple_strtoul(&identifier[2], &endptr, 0);
 314         else
 315                 id = simple_strtoul(identifier, &endptr, 0);
 316         if (id > 255) {
 317                 pr_err("chap identifier: %lu greater than 255\n", id);
 318                 goto out;
 319         }
 320         /*
 321          * RFC 1994 says Identifier is no more than octet (8 bits).
 322          */
 323         pr_debug("[server] Got CHAP_I=%lu\n", id);
 324         /*
 325          * Get CHAP_C.
 326          */
 327         if (extract_param(nr_in_ptr, "CHAP_C", CHAP_CHALLENGE_STR_LEN,
 328                         challenge, &type) < 0) {
 329                 pr_err("Could not find CHAP_C.\n");
 330                 goto out;
 331         }
 332
 333         if (type != HEX) {
 334                 pr_err("Could not find CHAP_C.\n");
 335                 goto out;
 336         }
 337         pr_debug("[server] Got CHAP_C=%s\n", challenge);
 338         challenge_len = chap_string_to_hex(challenge_binhex, challenge,
 339                                 strlen(challenge));
 340         if (!challenge_len) {
 341                 pr_err("Unable to convert incoming challenge\n");
 342                 goto out;
 343         }
 344         /*
 345          * During mutual authentication, the CHAP_C generated by the
 346          * initiator must not match the original CHAP_C generated by
 347          * the target.
 348          */
 349         if (!memcmp(challenge_binhex, chap->challenge, CHAP_CHALLENGE_LENGTH)) {
 350                 pr_err("initiator CHAP_C matches target CHAP_C, failing"
 351                        " login attempt\n");
 352                 goto out;
 353         }
 354         /*
 355          * Generate CHAP_N and CHAP_R for mutual authentication.
 356          */
 357         tfm = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC);
 358         if (IS_ERR(tfm)) {
 359                 pr_err("Unable to allocate struct crypto_hash\n");
 360                 goto out;
 361         }
 362         desc.tfm = tfm;
 363         desc.flags = 0;
 364
 365         ret = crypto_hash_init(&desc);
 366         if (ret < 0) {
 367                 pr_err("crypto_hash_init() failed\n");
 368                 crypto_free_hash(tfm);
 369                 goto out;
 370         }
 371
 372         /* To handle both endiannesses */
 373         id_as_uchar = id;
 374         sg_init_one(&sg, &id_as_uchar, 1);
 375         ret = crypto_hash_update(&desc, &sg, 1);
 376         if (ret < 0) {
 377                 pr_err("crypto_hash_update() failed for id\n");
 378                 crypto_free_hash(tfm);
 379                 goto out;
 380         }
 381
 382         sg_init_one(&sg, auth->password_mutual,
 383                                 strlen(auth->password_mutual));
 384         ret = crypto_hash_update(&desc, &sg, strlen(auth->password_mutual));
 385         if (ret < 0) {
 386                 pr_err("crypto_hash_update() failed for"
 387                                 " password_mutual\n");
 388                 crypto_free_hash(tfm);
 389                 goto out;
 390         }
 391         /*
 392          * Convert received challenge to binary hex.
 393          */
 394         sg_init_one(&sg, challenge_binhex, challenge_len);
 395         ret = crypto_hash_update(&desc, &sg, challenge_len);
 396         if (ret < 0) {
 397                 pr_err("crypto_hash_update() failed for ma challenge\n");
 398                 crypto_free_hash(tfm);
 399                 goto out;
 400         }
 401
 402         ret = crypto_hash_final(&desc, digest);
 403         if (ret < 0) {
 404                 pr_err("crypto_hash_final() failed for ma digest\n");
 405                 crypto_free_hash(tfm);
 406                 goto out;
 407         }
 408         crypto_free_hash(tfm);
 409         /*
 410          * Generate CHAP_N and CHAP_R.
 411          */
 412         *nr_out_len = sprintf(nr_out_ptr, "CHAP_N=%s", auth->userid_mutual);
 413         *nr_out_len += 1;
 414         pr_debug("[server] Sending CHAP_N=%s\n", auth->userid_mutual);
 415         /*
 416          * Convert response from binary hex to ascii hext.
 417          */
 418         chap_binaryhex_to_asciihex(response, digest, MD5_SIGNATURE_SIZE);
 419         *nr_out_len += sprintf(nr_out_ptr + *nr_out_len, "CHAP_R=0x%s",
 420                         response);
 421         *nr_out_len += 1;
 422         pr_debug("[server] Sending CHAP_R=0x%s\n", response);
 423         auth_ret = 0;
 424 out:
 425         kfree(challenge);
 426         kfree(challenge_binhex);
 427         return auth_ret;
 428 }
 429
 430 static int chap_got_response(
 431         struct iscsi_conn *conn,
 432         struct iscsi_node_auth *auth,
 433         char *nr_in_ptr,
 434         char *nr_out_ptr,
 435         unsigned int *nr_out_len)
 436 {
 437         struct iscsi_chap *chap = conn->auth_protocol;
 438
 439         switch (chap->digest_type) {
 440         case CHAP_DIGEST_MD5:
 441                 if (chap_server_compute_md5(conn, auth, nr_in_ptr,
 442                                 nr_out_ptr, nr_out_len) < 0)
 443                         return -1;
 444                 return 0;
 445         default:
 446                 pr_err("Unknown CHAP digest type %d!\n",
 447                                 chap->digest_type);
 448                 return -1;
 449         }
 450 }
 451
 452 u32 chap_main_loop(
 453         struct iscsi_conn *conn,
 454         struct iscsi_node_auth *auth,
 455         char *in_text,
 456         char *out_text,
 457         int *in_len,
 458         int *out_len)
 459 {
 460         struct iscsi_chap *chap = conn->auth_protocol;
 461
 462         if (!chap) {
 463                 chap = chap_server_open(conn, auth, in_text, out_text, out_len);
 464                 if (!chap)
 465                         return 2;
 466                 chap->chap_state = CHAP_STAGE_SERVER_AIC;
 467                 return 0;
 468         } else if (chap->chap_state == CHAP_STAGE_SERVER_AIC) {
 469                 convert_null_to_semi(in_text, *in_len);
 470                 if (chap_got_response(conn, auth, in_text, out_text,
 471                                 out_len) < 0) {
 472                         chap_close(conn);
 473                         return 2;
 474                 }
 475                 if (auth->authenticate_target)
 476                         chap->chap_state = CHAP_STAGE_SERVER_NR;
 477                 else
 478                         *out_len = 0;
 479                 chap_close(conn);
 480                 return 1;
 481         }
 482
 483         return 2;
 484 }