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