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 <linux/kernel.h>
20 #include <linux/string.h>
21 #include <linux/crypto.h>
22 #include <linux/err.h>
23 #include <linux/scatterlist.h>
25 #include "iscsi_target_core.h"
26 #include "iscsi_target_nego.h"
27 #include "iscsi_target_auth.h"
29 static int chap_string_to_hex(unsigned char *dst, unsigned char *src, int len)
31 int j = DIV_ROUND_UP(len, 2), rc;
33 rc = hex2bin(dst, src, j);
35 pr_debug("CHAP string contains non hex digit symbols\n");
41 static void chap_binaryhex_to_asciihex(char *dst, char *src, int src_len)
45 for (i = 0; i < src_len; i++) {
46 sprintf(&dst[i*2], "%02x", (int) src[i] & 0xff);
50 static void chap_gen_challenge(
51 struct iscsi_conn *conn,
56 unsigned char challenge_asciihex[CHAP_CHALLENGE_LENGTH * 2 + 1];
57 struct iscsi_chap *chap = conn->auth_protocol;
59 memset(challenge_asciihex, 0, CHAP_CHALLENGE_LENGTH * 2 + 1);
61 get_random_bytes(chap->challenge, CHAP_CHALLENGE_LENGTH);
62 chap_binaryhex_to_asciihex(challenge_asciihex, chap->challenge,
63 CHAP_CHALLENGE_LENGTH);
65 * Set CHAP_C, and copy the generated challenge into c_str.
67 *c_len += sprintf(c_str + *c_len, "CHAP_C=0x%s", challenge_asciihex);
70 pr_debug("[%s] Sending CHAP_C=0x%s\n\n", (caller) ? "server" : "client",
75 static struct iscsi_chap *chap_server_open(
76 struct iscsi_conn *conn,
77 struct iscsi_node_auth *auth,
80 unsigned int *aic_len)
82 struct iscsi_chap *chap;
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"
91 conn->auth_protocol = kzalloc(sizeof(struct iscsi_chap), GFP_KERNEL);
92 if (!conn->auth_protocol)
95 chap = conn->auth_protocol;
97 * We only support MD5 MDA presently.
99 if (strncmp(a_str, "CHAP_A=5", 8)) {
100 pr_err("CHAP_A is not MD5.\n");
103 pr_debug("[server] Got CHAP_A=5\n");
105 * Send back CHAP_A set to MD5.
107 *aic_len = sprintf(aic_str, "CHAP_A=5");
109 chap->digest_type = CHAP_DIGEST_MD5;
110 pr_debug("[server] Sending CHAP_A=%d\n", chap->digest_type);
114 chap->id = ISCSI_TPG_C(conn)->tpg_chap_id++;
115 *aic_len += sprintf(aic_str + *aic_len, "CHAP_I=%d", chap->id);
117 pr_debug("[server] Sending CHAP_I=%d\n", chap->id);
119 * Generate Challenge.
121 chap_gen_challenge(conn, 1, aic_str, aic_len);
126 static void chap_close(struct iscsi_conn *conn)
128 kfree(conn->auth_protocol);
129 conn->auth_protocol = NULL;
132 static int chap_server_compute_md5(
133 struct iscsi_conn *conn,
134 struct iscsi_node_auth *auth,
137 unsigned int *nr_out_len)
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;
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);
163 challenge = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL);
165 pr_err("Unable to allocate challenge buffer\n");
169 challenge_binhex = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL);
170 if (!challenge_binhex) {
171 pr_err("Unable to allocate challenge_binhex buffer\n");
177 if (extract_param(nr_in_ptr, "CHAP_N", MAX_CHAP_N_SIZE, chap_n,
179 pr_err("Could not find CHAP_N.\n");
183 pr_err("Could not find CHAP_N.\n");
187 if (memcmp(chap_n, auth->userid, strlen(auth->userid)) != 0) {
188 pr_err("CHAP_N values do not match!\n");
191 pr_debug("[server] Got CHAP_N=%s\n", chap_n);
195 if (extract_param(nr_in_ptr, "CHAP_R", MAX_RESPONSE_LENGTH, chap_r,
197 pr_err("Could not find CHAP_R.\n");
201 pr_err("Could not find CHAP_R.\n");
205 pr_debug("[server] Got CHAP_R=%s\n", chap_r);
206 chap_string_to_hex(client_digest, chap_r, strlen(chap_r));
208 tfm = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC);
210 pr_err("Unable to allocate struct crypto_hash\n");
216 ret = crypto_hash_init(&desc);
218 pr_err("crypto_hash_init() failed\n");
219 crypto_free_hash(tfm);
223 sg_init_one(&sg, &chap->id, 1);
224 ret = crypto_hash_update(&desc, &sg, 1);
226 pr_err("crypto_hash_update() failed for id\n");
227 crypto_free_hash(tfm);
231 sg_init_one(&sg, &auth->password, strlen(auth->password));
232 ret = crypto_hash_update(&desc, &sg, strlen(auth->password));
234 pr_err("crypto_hash_update() failed for password\n");
235 crypto_free_hash(tfm);
239 sg_init_one(&sg, chap->challenge, CHAP_CHALLENGE_LENGTH);
240 ret = crypto_hash_update(&desc, &sg, CHAP_CHALLENGE_LENGTH);
242 pr_err("crypto_hash_update() failed for challenge\n");
243 crypto_free_hash(tfm);
247 ret = crypto_hash_final(&desc, server_digest);
249 pr_err("crypto_hash_final() failed for server digest\n");
250 crypto_free_hash(tfm);
253 crypto_free_hash(tfm);
255 chap_binaryhex_to_asciihex(response, server_digest, MD5_SIGNATURE_SIZE);
256 pr_debug("[server] MD5 Server Digest: %s\n", response);
258 if (memcmp(server_digest, client_digest, MD5_SIGNATURE_SIZE) != 0) {
259 pr_debug("[server] MD5 Digests do not match!\n\n");
262 pr_debug("[server] MD5 Digests match, CHAP connetication"
265 * One way authentication has succeeded, return now if mutual
266 * authentication is not enabled.
268 if (!auth->authenticate_target) {
270 kfree(challenge_binhex);
276 if (extract_param(nr_in_ptr, "CHAP_I", 10, identifier, &type) < 0) {
277 pr_err("Could not find CHAP_I.\n");
282 id = simple_strtoul(&identifier[2], &endptr, 0);
284 id = simple_strtoul(identifier, &endptr, 0);
286 pr_err("chap identifier: %lu greater than 255\n", id);
290 * RFC 1994 says Identifier is no more than octet (8 bits).
292 pr_debug("[server] Got CHAP_I=%lu\n", id);
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");
303 pr_err("Could not find CHAP_C.\n");
306 pr_debug("[server] Got CHAP_C=%s\n", challenge);
307 challenge_len = chap_string_to_hex(challenge_binhex, challenge,
309 if (!challenge_len) {
310 pr_err("Unable to convert incoming challenge\n");
314 * Generate CHAP_N and CHAP_R for mutual authentication.
316 tfm = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC);
318 pr_err("Unable to allocate struct crypto_hash\n");
324 ret = crypto_hash_init(&desc);
326 pr_err("crypto_hash_init() failed\n");
327 crypto_free_hash(tfm);
331 /* To handle both endiannesses */
333 sg_init_one(&sg, &id_as_uchar, 1);
334 ret = crypto_hash_update(&desc, &sg, 1);
336 pr_err("crypto_hash_update() failed for id\n");
337 crypto_free_hash(tfm);
341 sg_init_one(&sg, auth->password_mutual,
342 strlen(auth->password_mutual));
343 ret = crypto_hash_update(&desc, &sg, strlen(auth->password_mutual));
345 pr_err("crypto_hash_update() failed for"
346 " password_mutual\n");
347 crypto_free_hash(tfm);
351 * Convert received challenge to binary hex.
353 sg_init_one(&sg, challenge_binhex, challenge_len);
354 ret = crypto_hash_update(&desc, &sg, challenge_len);
356 pr_err("crypto_hash_update() failed for ma challenge\n");
357 crypto_free_hash(tfm);
361 ret = crypto_hash_final(&desc, digest);
363 pr_err("crypto_hash_final() failed for ma digest\n");
364 crypto_free_hash(tfm);
367 crypto_free_hash(tfm);
369 * Generate CHAP_N and CHAP_R.
371 *nr_out_len = sprintf(nr_out_ptr, "CHAP_N=%s", auth->userid_mutual);
373 pr_debug("[server] Sending CHAP_N=%s\n", auth->userid_mutual);
375 * Convert response from binary hex to ascii hext.
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",
381 pr_debug("[server] Sending CHAP_R=0x%s\n", response);
385 kfree(challenge_binhex);
389 static int chap_got_response(
390 struct iscsi_conn *conn,
391 struct iscsi_node_auth *auth,
394 unsigned int *nr_out_len)
396 struct iscsi_chap *chap = conn->auth_protocol;
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)
405 pr_err("Unknown CHAP digest type %d!\n",
412 struct iscsi_conn *conn,
413 struct iscsi_node_auth *auth,
419 struct iscsi_chap *chap = conn->auth_protocol;
422 chap = chap_server_open(conn, auth, in_text, out_text, out_len);
425 chap->chap_state = CHAP_STAGE_SERVER_AIC;
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,
434 if (auth->authenticate_target)
435 chap->chap_state = CHAP_STAGE_SERVER_NR;