drivers/target/iscsi/iscsi_target_auth.c

   1 /*******************************************************************************
   2  * This file houses the main functions for the iSCSI CHAP support
   3  *
   4  * (c) Copyright 2007-2013 Datera, Inc.
   5  *
   6  * Author: Nicholas A. Bellinger <nab@linux-iscsi.org>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  ******************************************************************************/
  18
  19 #include <linux/kernel.h>
  20 #include <linux/string.h>
  21 #include <linux/crypto.h>
  22 #include <linux/err.h>
  23 #include <linux/scatterlist.h>
  24
  25 #include "iscsi_target_core.h"
  26 #include "iscsi_target_nego.h"
  27 #include "iscsi_target_auth.h"
  28
  29 static int chap_string_to_hex(unsigned char *dst, unsigned char *src, int len)
  30 {
  31         int j = DIV_ROUND_UP(len, 2), rc;
  32
  33         rc = hex2bin(dst, src, j);
  34         if (rc < 0)
  35                 pr_debug("CHAP string contains non hex digit symbols\n");
  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_gen_challenge(
  51         struct iscsi_conn *conn,
  52         int caller,
  53         char *c_str,
  54         unsigned int *c_len)
  55 {
  56         unsigned char challenge_asciihex[CHAP_CHALLENGE_LENGTH * 2 + 1];
  57         struct iscsi_chap *chap = conn->auth_protocol;
  58
  59         memset(challenge_asciihex, 0, CHAP_CHALLENGE_LENGTH * 2 + 1);
  60
  61         get_random_bytes(chap->challenge, CHAP_CHALLENGE_LENGTH);
  62         chap_binaryhex_to_asciihex(challenge_asciihex, chap->challenge,
  63                                 CHAP_CHALLENGE_LENGTH);
  64         /*
  65          * Set CHAP_C, and copy the generated challenge into c_str.
  66          */
  67         *c_len += sprintf(c_str + *c_len, "CHAP_C=0x%s", challenge_asciihex);
  68         *c_len += 1;
  69
  70         pr_debug("[%s] Sending CHAP_C=0x%s\n\n", (caller) ? "server" : "client",
  71                         challenge_asciihex);
  72 }
  73
  74
  75 static struct iscsi_chap *chap_server_open(
  76         struct iscsi_conn *conn,
  77         struct iscsi_node_auth *auth,
  78         const char *a_str,
  79         char *aic_str,
  80         unsigned int *aic_len)
  81 {
  82         struct iscsi_chap *chap;
  83
  84         if (!(auth->naf_flags & NAF_USERID_SET) ||
  85             !(auth->naf_flags & NAF_PASSWORD_SET)) {
  86                 pr_err("CHAP user or password not set for"
  87                                 " Initiator ACL\n");
  88                 return NULL;
  89         }
  90
  91         conn->auth_protocol = kzalloc(sizeof(struct iscsi_chap), GFP_KERNEL);
  92         if (!conn->auth_protocol)
  93                 return NULL;
  94
  95         chap = conn->auth_protocol;
  96         /*
  97          * We only support MD5 MDA presently.
  98          */
  99         if (strncmp(a_str, "CHAP_A=5", 8)) {
 100                 pr_err("CHAP_A is not MD5.\n");
 101                 return NULL;
 102         }
 103         pr_debug("[server] Got CHAP_A=5\n");
 104         /*
 105          * Send back CHAP_A set to MD5.
 106          */
 107         *aic_len = sprintf(aic_str, "CHAP_A=5");
 108         *aic_len += 1;
 109         chap->digest_type = CHAP_DIGEST_MD5;
 110         pr_debug("[server] Sending CHAP_A=%d\n", chap->digest_type);
 111         /*
 112          * Set Identifier.
 113          */
 114         chap->id = conn->tpg->tpg_chap_id++;
 115         *aic_len += sprintf(aic_str + *aic_len, "CHAP_I=%d", chap->id);
 116         *aic_len += 1;
 117         pr_debug("[server] Sending CHAP_I=%d\n", chap->id);
 118         /*
 119          * Generate Challenge.
 120          */
 121         chap_gen_challenge(conn, 1, aic_str, aic_len);
 122
 123         return chap;
 124 }
 125
 126 static void chap_close(struct iscsi_conn *conn)
 127 {
 128         kfree(conn->auth_protocol);
 129         conn->auth_protocol = NULL;
 130 }
 131
 132 static int chap_server_compute_md5(
 133         struct iscsi_conn *conn,
 134         struct iscsi_node_auth *auth,
 135         char *nr_in_ptr,
 136         char *nr_out_ptr,
 137         unsigned int *nr_out_len)
 138 {
 139         char *endptr;
 140         unsigned long id;
 141         unsigned char id_as_uchar;
 142         unsigned char digest[MD5_SIGNATURE_SIZE];
 143         unsigned char type, response[MD5_SIGNATURE_SIZE * 2 + 2];
 144         unsigned char identifier[10], *challenge = NULL;
 145         unsigned char *challenge_binhex = NULL;
 146         unsigned char client_digest[MD5_SIGNATURE_SIZE];
 147         unsigned char server_digest[MD5_SIGNATURE_SIZE];
 148         unsigned char chap_n[MAX_CHAP_N_SIZE], chap_r[MAX_RESPONSE_LENGTH];
 149         struct iscsi_chap *chap = conn->auth_protocol;
 150         struct crypto_hash *tfm;
 151         struct hash_desc desc;
 152         struct scatterlist sg;
 153         int auth_ret = -1, ret, challenge_len;
 154
 155         memset(identifier, 0, 10);
 156         memset(chap_n, 0, MAX_CHAP_N_SIZE);
 157         memset(chap_r, 0, MAX_RESPONSE_LENGTH);
 158         memset(digest, 0, MD5_SIGNATURE_SIZE);
 159         memset(response, 0, MD5_SIGNATURE_SIZE * 2 + 2);
 160         memset(client_digest, 0, MD5_SIGNATURE_SIZE);
 161         memset(server_digest, 0, MD5_SIGNATURE_SIZE);
 162
 163         challenge = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL);
 164         if (!challenge) {
 165                 pr_err("Unable to allocate challenge buffer\n");
 166                 goto out;
 167         }
 168
 169         challenge_binhex = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL);
 170         if (!challenge_binhex) {
 171                 pr_err("Unable to allocate challenge_binhex buffer\n");
 172                 goto out;
 173         }
 174         /*
 175          * Extract CHAP_N.
 176          */
 177         if (extract_param(nr_in_ptr, "CHAP_N", MAX_CHAP_N_SIZE, chap_n,
 178                                 &type) < 0) {
 179                 pr_err("Could not find CHAP_N.\n");
 180                 goto out;
 181         }
 182         if (type == HEX) {
 183                 pr_err("Could not find CHAP_N.\n");
 184                 goto out;
 185         }
 186
 187         if (memcmp(chap_n, auth->userid, strlen(auth->userid)) != 0) {
 188                 pr_err("CHAP_N values do not match!\n");
 189                 goto out;
 190         }
 191         pr_debug("[server] Got CHAP_N=%s\n", chap_n);
 192         /*
 193          * Extract CHAP_R.
 194          */
 195         if (extract_param(nr_in_ptr, "CHAP_R", MAX_RESPONSE_LENGTH, chap_r,
 196                                 &type) < 0) {
 197                 pr_err("Could not find CHAP_R.\n");
 198                 goto out;
 199         }
 200         if (type != HEX) {
 201                 pr_err("Could not find CHAP_R.\n");
 202                 goto out;
 203         }
 204
 205         pr_debug("[server] Got CHAP_R=%s\n", chap_r);
 206         chap_string_to_hex(client_digest, chap_r, strlen(chap_r));
 207
 208         tfm = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC);
 209         if (IS_ERR(tfm)) {
 210                 pr_err("Unable to allocate struct crypto_hash\n");
 211                 goto out;
 212         }
 213         desc.tfm = tfm;
 214         desc.flags = 0;
 215
 216         ret = crypto_hash_init(&desc);
 217         if (ret < 0) {
 218                 pr_err("crypto_hash_init() failed\n");
 219                 crypto_free_hash(tfm);
 220                 goto out;
 221         }
 222
 223         sg_init_one(&sg, &chap->id, 1);
 224         ret = crypto_hash_update(&desc, &sg, 1);
 225         if (ret < 0) {
 226                 pr_err("crypto_hash_update() failed for id\n");
 227                 crypto_free_hash(tfm);
 228                 goto out;
 229         }
 230
 231         sg_init_one(&sg, &auth->password, strlen(auth->password));
 232         ret = crypto_hash_update(&desc, &sg, strlen(auth->password));
 233         if (ret < 0) {
 234                 pr_err("crypto_hash_update() failed for password\n");
 235                 crypto_free_hash(tfm);
 236                 goto out;
 237         }
 238
 239         sg_init_one(&sg, chap->challenge, CHAP_CHALLENGE_LENGTH);
 240         ret = crypto_hash_update(&desc, &sg, CHAP_CHALLENGE_LENGTH);
 241         if (ret < 0) {
 242                 pr_err("crypto_hash_update() failed for challenge\n");
 243                 crypto_free_hash(tfm);
 244                 goto out;
 245         }
 246
 247         ret = crypto_hash_final(&desc, server_digest);
 248         if (ret < 0) {
 249                 pr_err("crypto_hash_final() failed for server digest\n");
 250                 crypto_free_hash(tfm);
 251                 goto out;
 252         }
 253         crypto_free_hash(tfm);
 254
 255         chap_binaryhex_to_asciihex(response, server_digest, MD5_SIGNATURE_SIZE);
 256         pr_debug("[server] MD5 Server Digest: %s\n", response);
 257
 258         if (memcmp(server_digest, client_digest, MD5_SIGNATURE_SIZE) != 0) {
 259                 pr_debug("[server] MD5 Digests do not match!\n\n");
 260                 goto out;
 261         } else
 262                 pr_debug("[server] MD5 Digests match, CHAP connetication"
 263                                 " successful.\n\n");
 264         /*
 265          * One way authentication has succeeded, return now if mutual
 266          * authentication is not enabled.
 267          */
 268         if (!auth->authenticate_target) {
 269                 kfree(challenge);
 270                 kfree(challenge_binhex);
 271                 return 0;
 272         }
 273         /*
 274          * Get CHAP_I.
 275          */
 276         if (extract_param(nr_in_ptr, "CHAP_I", 10, identifier, &type) < 0) {
 277                 pr_err("Could not find CHAP_I.\n");
 278                 goto out;
 279         }
 280
 281         if (type == HEX)
 282                 id = simple_strtoul(&identifier[2], &endptr, 0);
 283         else
 284                 id = simple_strtoul(identifier, &endptr, 0);
 285         if (id > 255) {
 286                 pr_err("chap identifier: %lu greater than 255\n", id);
 287                 goto out;
 288         }
 289         /*
 290          * RFC 1994 says Identifier is no more than octet (8 bits).
 291          */
 292         pr_debug("[server] Got CHAP_I=%lu\n", id);
 293         /*
 294          * Get CHAP_C.
 295          */
 296         if (extract_param(nr_in_ptr, "CHAP_C", CHAP_CHALLENGE_STR_LEN,
 297                         challenge, &type) < 0) {
 298                 pr_err("Could not find CHAP_C.\n");
 299                 goto out;
 300         }
 301
 302         if (type != HEX) {
 303                 pr_err("Could not find CHAP_C.\n");
 304                 goto out;
 305         }
 306         pr_debug("[server] Got CHAP_C=%s\n", challenge);
 307         challenge_len = chap_string_to_hex(challenge_binhex, challenge,
 308                                 strlen(challenge));
 309         if (!challenge_len) {
 310                 pr_err("Unable to convert incoming challenge\n");
 311                 goto out;
 312         }
 313         /*
 314          * Generate CHAP_N and CHAP_R for mutual authentication.
 315          */
 316         tfm = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC);
 317         if (IS_ERR(tfm)) {
 318                 pr_err("Unable to allocate struct crypto_hash\n");
 319                 goto out;
 320         }
 321         desc.tfm = tfm;
 322         desc.flags = 0;
 323
 324         ret = crypto_hash_init(&desc);
 325         if (ret < 0) {
 326                 pr_err("crypto_hash_init() failed\n");
 327                 crypto_free_hash(tfm);
 328                 goto out;
 329         }
 330
 331         /* To handle both endiannesses */
 332         id_as_uchar = id;
 333         sg_init_one(&sg, &id_as_uchar, 1);
 334         ret = crypto_hash_update(&desc, &sg, 1);
 335         if (ret < 0) {
 336                 pr_err("crypto_hash_update() failed for id\n");
 337                 crypto_free_hash(tfm);
 338                 goto out;
 339         }
 340
 341         sg_init_one(&sg, auth->password_mutual,
 342                                 strlen(auth->password_mutual));
 343         ret = crypto_hash_update(&desc, &sg, strlen(auth->password_mutual));
 344         if (ret < 0) {
 345                 pr_err("crypto_hash_update() failed for"
 346                                 " password_mutual\n");
 347                 crypto_free_hash(tfm);
 348                 goto out;
 349         }
 350         /*
 351          * Convert received challenge to binary hex.
 352          */
 353         sg_init_one(&sg, challenge_binhex, challenge_len);
 354         ret = crypto_hash_update(&desc, &sg, challenge_len);
 355         if (ret < 0) {
 356                 pr_err("crypto_hash_update() failed for ma challenge\n");
 357                 crypto_free_hash(tfm);
 358                 goto out;
 359         }
 360
 361         ret = crypto_hash_final(&desc, digest);
 362         if (ret < 0) {
 363                 pr_err("crypto_hash_final() failed for ma digest\n");
 364                 crypto_free_hash(tfm);
 365                 goto out;
 366         }
 367         crypto_free_hash(tfm);
 368         /*
 369          * Generate CHAP_N and CHAP_R.
 370          */
 371         *nr_out_len = sprintf(nr_out_ptr, "CHAP_N=%s", auth->userid_mutual);
 372         *nr_out_len += 1;
 373         pr_debug("[server] Sending CHAP_N=%s\n", auth->userid_mutual);
 374         /*
 375          * Convert response from binary hex to ascii hext.
 376          */
 377         chap_binaryhex_to_asciihex(response, digest, MD5_SIGNATURE_SIZE);
 378         *nr_out_len += sprintf(nr_out_ptr + *nr_out_len, "CHAP_R=0x%s",
 379                         response);
 380         *nr_out_len += 1;
 381         pr_debug("[server] Sending CHAP_R=0x%s\n", response);
 382         auth_ret = 0;
 383 out:
 384         kfree(challenge);
 385         kfree(challenge_binhex);
 386         return auth_ret;
 387 }
 388
 389 static int chap_got_response(
 390         struct iscsi_conn *conn,
 391         struct iscsi_node_auth *auth,
 392         char *nr_in_ptr,
 393         char *nr_out_ptr,
 394         unsigned int *nr_out_len)
 395 {
 396         struct iscsi_chap *chap = conn->auth_protocol;
 397
 398         switch (chap->digest_type) {
 399         case CHAP_DIGEST_MD5:
 400                 if (chap_server_compute_md5(conn, auth, nr_in_ptr,
 401                                 nr_out_ptr, nr_out_len) < 0)
 402                         return -1;
 403                 return 0;
 404         default:
 405                 pr_err("Unknown CHAP digest type %d!\n",
 406                                 chap->digest_type);
 407                 return -1;
 408         }
 409 }
 410
 411 u32 chap_main_loop(
 412         struct iscsi_conn *conn,
 413         struct iscsi_node_auth *auth,
 414         char *in_text,
 415         char *out_text,
 416         int *in_len,
 417         int *out_len)
 418 {
 419         struct iscsi_chap *chap = conn->auth_protocol;
 420
 421         if (!chap) {
 422                 chap = chap_server_open(conn, auth, in_text, out_text, out_len);
 423                 if (!chap)
 424                         return 2;
 425                 chap->chap_state = CHAP_STAGE_SERVER_AIC;
 426                 return 0;
 427         } else if (chap->chap_state == CHAP_STAGE_SERVER_AIC) {
 428                 convert_null_to_semi(in_text, *in_len);
 429                 if (chap_got_response(conn, auth, in_text, out_text,
 430                                 out_len) < 0) {
 431                         chap_close(conn);
 432                         return 2;
 433                 }
 434                 if (auth->authenticate_target)
 435                         chap->chap_state = CHAP_STAGE_SERVER_NR;
 436                 else
 437                         *out_len = 0;
 438                 chap_close(conn);
 439                 return 1;
 440         }
 441
 442         return 2;
 443 }