1 /*******************************************************************************
2 * This file houses the main functions for the iSCSI CHAP support
4 * (c) Copyright 2007-2013 Datera, Inc.
6 * Author: Nicholas A. Bellinger <nab@linux-iscsi.org>
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.
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 ******************************************************************************/
19 #include <crypto/hash.h>
20 #include <linux/kernel.h>
21 #include <linux/string.h>
22 #include <linux/err.h>
23 #include <linux/random.h>
24 #include <linux/scatterlist.h>
25 #include <target/iscsi/iscsi_target_core.h>
26 #include "iscsi_target_nego.h"
27 #include "iscsi_target_auth.h"
29 static int chap_gen_challenge(
30 struct iscsi_conn *conn,
36 unsigned char challenge_asciihex[CHAP_CHALLENGE_LENGTH * 2 + 1];
37 struct iscsi_chap *chap = conn->auth_protocol;
39 memset(challenge_asciihex, 0, CHAP_CHALLENGE_LENGTH * 2 + 1);
41 ret = get_random_bytes_wait(chap->challenge, CHAP_CHALLENGE_LENGTH);
44 bin2hex(challenge_asciihex, chap->challenge,
45 CHAP_CHALLENGE_LENGTH);
47 * Set CHAP_C, and copy the generated challenge into c_str.
49 *c_len += sprintf(c_str + *c_len, "CHAP_C=0x%s", challenge_asciihex);
52 pr_debug("[%s] Sending CHAP_C=0x%s\n\n", (caller) ? "server" : "client",
57 static int chap_check_algorithm(const char *a_str)
59 char *tmp, *orig, *token;
61 tmp = kstrdup(a_str, GFP_KERNEL);
63 pr_err("Memory allocation failed for CHAP_A temporary buffer\n");
64 return CHAP_DIGEST_UNKNOWN;
68 token = strsep(&tmp, "=");
72 if (strcmp(token, "CHAP_A")) {
73 pr_err("Unable to locate CHAP_A key\n");
77 token = strsep(&tmp, ",");
81 if (!strcmp(token, "5")) {
82 pr_debug("Selected MD5 Algorithm\n");
84 return CHAP_DIGEST_MD5;
89 return CHAP_DIGEST_UNKNOWN;
92 static void chap_close(struct iscsi_conn *conn)
94 kfree(conn->auth_protocol);
95 conn->auth_protocol = NULL;
98 static struct iscsi_chap *chap_server_open(
99 struct iscsi_conn *conn,
100 struct iscsi_node_auth *auth,
103 unsigned int *aic_len)
106 struct iscsi_chap *chap;
108 if (!(auth->naf_flags & NAF_USERID_SET) ||
109 !(auth->naf_flags & NAF_PASSWORD_SET)) {
110 pr_err("CHAP user or password not set for"
115 conn->auth_protocol = kzalloc(sizeof(struct iscsi_chap), GFP_KERNEL);
116 if (!conn->auth_protocol)
119 chap = conn->auth_protocol;
120 ret = chap_check_algorithm(a_str);
122 case CHAP_DIGEST_MD5:
123 pr_debug("[server] Got CHAP_A=5\n");
125 * Send back CHAP_A set to MD5.
127 *aic_len = sprintf(aic_str, "CHAP_A=5");
129 chap->digest_type = CHAP_DIGEST_MD5;
130 pr_debug("[server] Sending CHAP_A=%d\n", chap->digest_type);
132 case CHAP_DIGEST_UNKNOWN:
134 pr_err("Unsupported CHAP_A value\n");
142 chap->id = conn->tpg->tpg_chap_id++;
143 *aic_len += sprintf(aic_str + *aic_len, "CHAP_I=%d", chap->id);
145 pr_debug("[server] Sending CHAP_I=%d\n", chap->id);
147 * Generate Challenge.
149 if (chap_gen_challenge(conn, 1, aic_str, aic_len) < 0) {
157 static int chap_server_compute_md5(
158 struct iscsi_conn *conn,
159 struct iscsi_node_auth *auth,
162 unsigned int *nr_out_len)
165 unsigned char id_as_uchar;
166 unsigned char 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];
174 struct iscsi_chap *chap = conn->auth_protocol;
175 struct crypto_shash *tfm = NULL;
176 struct shash_desc *desc = NULL;
177 int auth_ret = -1, ret, challenge_len;
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);
187 challenge = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL);
189 pr_err("Unable to allocate challenge buffer\n");
193 challenge_binhex = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL);
194 if (!challenge_binhex) {
195 pr_err("Unable to allocate challenge_binhex buffer\n");
201 if (extract_param(nr_in_ptr, "CHAP_N", MAX_CHAP_N_SIZE, chap_n,
203 pr_err("Could not find CHAP_N.\n");
207 pr_err("Could not find CHAP_N.\n");
211 /* Include the terminating NULL in the compare */
212 compare_len = strlen(auth->userid) + 1;
213 if (strncmp(chap_n, auth->userid, compare_len) != 0) {
214 pr_err("CHAP_N values do not match!\n");
217 pr_debug("[server] Got CHAP_N=%s\n", chap_n);
221 if (extract_param(nr_in_ptr, "CHAP_R", MAX_RESPONSE_LENGTH, chap_r,
223 pr_err("Could not find CHAP_R.\n");
227 pr_err("Could not find CHAP_R.\n");
230 if (strlen(chap_r) != MD5_SIGNATURE_SIZE * 2) {
231 pr_err("Malformed CHAP_R\n");
234 if (hex2bin(client_digest, chap_r, MD5_SIGNATURE_SIZE) < 0) {
235 pr_err("Malformed CHAP_R\n");
239 pr_debug("[server] Got CHAP_R=%s\n", chap_r);
241 tfm = crypto_alloc_shash("md5", 0, 0);
244 pr_err("Unable to allocate struct crypto_shash\n");
248 desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(tfm), GFP_KERNEL);
250 pr_err("Unable to allocate struct shash_desc\n");
257 ret = crypto_shash_init(desc);
259 pr_err("crypto_shash_init() failed\n");
263 ret = crypto_shash_update(desc, &chap->id, 1);
265 pr_err("crypto_shash_update() failed for id\n");
269 ret = crypto_shash_update(desc, (char *)&auth->password,
270 strlen(auth->password));
272 pr_err("crypto_shash_update() failed for password\n");
276 ret = crypto_shash_finup(desc, chap->challenge,
277 CHAP_CHALLENGE_LENGTH, server_digest);
279 pr_err("crypto_shash_finup() failed for challenge\n");
283 bin2hex(response, server_digest, MD5_SIGNATURE_SIZE);
284 pr_debug("[server] MD5 Server Digest: %s\n", response);
286 if (memcmp(server_digest, client_digest, MD5_SIGNATURE_SIZE) != 0) {
287 pr_debug("[server] MD5 Digests do not match!\n\n");
290 pr_debug("[server] MD5 Digests match, CHAP connection"
293 * One way authentication has succeeded, return now if mutual
294 * authentication is not enabled.
296 if (!auth->authenticate_target) {
303 if (extract_param(nr_in_ptr, "CHAP_I", 10, identifier, &type) < 0) {
304 pr_err("Could not find CHAP_I.\n");
309 ret = kstrtoul(&identifier[2], 0, &id);
311 ret = kstrtoul(identifier, 0, &id);
314 pr_err("kstrtoul() failed for CHAP identifier: %d\n", ret);
318 pr_err("chap identifier: %lu greater than 255\n", id);
322 * RFC 1994 says Identifier is no more than octet (8 bits).
324 pr_debug("[server] Got CHAP_I=%lu\n", id);
328 if (extract_param(nr_in_ptr, "CHAP_C", CHAP_CHALLENGE_STR_LEN,
329 challenge, &type) < 0) {
330 pr_err("Could not find CHAP_C.\n");
335 pr_err("Could not find CHAP_C.\n");
338 challenge_len = DIV_ROUND_UP(strlen(challenge), 2);
339 if (!challenge_len) {
340 pr_err("Unable to convert incoming challenge\n");
343 if (challenge_len > 1024) {
344 pr_err("CHAP_C exceeds maximum binary size of 1024 bytes\n");
347 if (hex2bin(challenge_binhex, challenge, challenge_len) < 0) {
348 pr_err("Malformed CHAP_C\n");
351 pr_debug("[server] Got CHAP_C=%s\n", challenge);
353 * During mutual authentication, the CHAP_C generated by the
354 * initiator must not match the original CHAP_C generated by
357 if (!memcmp(challenge_binhex, chap->challenge, CHAP_CHALLENGE_LENGTH)) {
358 pr_err("initiator CHAP_C matches target CHAP_C, failing"
363 * Generate CHAP_N and CHAP_R for mutual authentication.
365 ret = crypto_shash_init(desc);
367 pr_err("crypto_shash_init() failed\n");
371 /* To handle both endiannesses */
373 ret = crypto_shash_update(desc, &id_as_uchar, 1);
375 pr_err("crypto_shash_update() failed for id\n");
379 ret = crypto_shash_update(desc, auth->password_mutual,
380 strlen(auth->password_mutual));
382 pr_err("crypto_shash_update() failed for"
383 " password_mutual\n");
387 * Convert received challenge to binary hex.
389 ret = crypto_shash_finup(desc, challenge_binhex, challenge_len,
392 pr_err("crypto_shash_finup() failed for ma challenge\n");
397 * Generate CHAP_N and CHAP_R.
399 *nr_out_len = sprintf(nr_out_ptr, "CHAP_N=%s", auth->userid_mutual);
401 pr_debug("[server] Sending CHAP_N=%s\n", auth->userid_mutual);
403 * Convert response from binary hex to ascii hext.
405 bin2hex(response, digest, MD5_SIGNATURE_SIZE);
406 *nr_out_len += sprintf(nr_out_ptr + *nr_out_len, "CHAP_R=0x%s",
409 pr_debug("[server] Sending CHAP_R=0x%s\n", response);
414 crypto_free_shash(tfm);
416 kfree(challenge_binhex);
420 static int chap_got_response(
421 struct iscsi_conn *conn,
422 struct iscsi_node_auth *auth,
425 unsigned int *nr_out_len)
427 struct iscsi_chap *chap = conn->auth_protocol;
429 switch (chap->digest_type) {
430 case CHAP_DIGEST_MD5:
431 if (chap_server_compute_md5(conn, auth, nr_in_ptr,
432 nr_out_ptr, nr_out_len) < 0)
436 pr_err("Unknown CHAP digest type %d!\n",
443 struct iscsi_conn *conn,
444 struct iscsi_node_auth *auth,
450 struct iscsi_chap *chap = conn->auth_protocol;
453 chap = chap_server_open(conn, auth, in_text, out_text, out_len);
456 chap->chap_state = CHAP_STAGE_SERVER_AIC;
458 } else if (chap->chap_state == CHAP_STAGE_SERVER_AIC) {
459 convert_null_to_semi(in_text, *in_len);
460 if (chap_got_response(conn, auth, in_text, out_text,
465 if (auth->authenticate_target)
466 chap->chap_state = CHAP_STAGE_SERVER_NR;