1 /*******************************************************************************
2 * This file houses the main functions for the iSCSI CHAP support
4 * \u00a9 Copyright 2007-2011 RisingTide Systems LLC.
6 * Licensed to the Linux Foundation under the General Public License (GPL) version 2.
8 * Author: Nicholas A. Bellinger <nab@linux-iscsi.org>
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.
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 ******************************************************************************/
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>
27 #include "iscsi_target_core.h"
28 #include "iscsi_target_nego.h"
29 #include "iscsi_target_auth.h"
31 static int chap_string_to_hex(unsigned char *dst, unsigned char *src, int len)
33 int j = DIV_ROUND_UP(len, 2), rc;
35 rc = hex2bin(dst, src, j);
37 pr_debug("CHAP string contains non hex digit symbols\n");
43 static void chap_binaryhex_to_asciihex(char *dst, char *src, int src_len)
47 for (i = 0; i < src_len; i++) {
48 sprintf(&dst[i*2], "%02x", (int) src[i] & 0xff);
52 static void chap_gen_challenge(
53 struct iscsi_conn *conn,
58 unsigned char challenge_asciihex[CHAP_CHALLENGE_LENGTH * 2 + 1];
59 struct iscsi_chap *chap = conn->auth_protocol;
61 memset(challenge_asciihex, 0, CHAP_CHALLENGE_LENGTH * 2 + 1);
63 get_random_bytes(chap->challenge, CHAP_CHALLENGE_LENGTH);
64 chap_binaryhex_to_asciihex(challenge_asciihex, chap->challenge,
65 CHAP_CHALLENGE_LENGTH);
67 * Set CHAP_C, and copy the generated challenge into c_str.
69 *c_len += sprintf(c_str + *c_len, "CHAP_C=0x%s", challenge_asciihex);
72 pr_debug("[%s] Sending CHAP_C=0x%s\n\n", (caller) ? "server" : "client",
77 static struct iscsi_chap *chap_server_open(
78 struct iscsi_conn *conn,
79 struct iscsi_node_auth *auth,
82 unsigned int *aic_len)
84 struct iscsi_chap *chap;
86 if (!(auth->naf_flags & NAF_USERID_SET) ||
87 !(auth->naf_flags & NAF_PASSWORD_SET)) {
88 pr_err("CHAP user or password not set for"
93 conn->auth_protocol = kzalloc(sizeof(struct iscsi_chap), GFP_KERNEL);
94 if (!conn->auth_protocol)
97 chap = conn->auth_protocol;
99 * We only support MD5 MDA presently.
101 if (strncmp(a_str, "CHAP_A=5", 8)) {
102 pr_err("CHAP_A is not MD5.\n");
105 pr_debug("[server] Got CHAP_A=5\n");
107 * Send back CHAP_A set to MD5.
109 *aic_len = sprintf(aic_str, "CHAP_A=5");
111 chap->digest_type = CHAP_DIGEST_MD5;
112 pr_debug("[server] Sending CHAP_A=%d\n", chap->digest_type);
116 chap->id = ISCSI_TPG_C(conn)->tpg_chap_id++;
117 *aic_len += sprintf(aic_str + *aic_len, "CHAP_I=%d", chap->id);
119 pr_debug("[server] Sending CHAP_I=%d\n", chap->id);
121 * Generate Challenge.
123 chap_gen_challenge(conn, 1, aic_str, aic_len);
128 static void chap_close(struct iscsi_conn *conn)
130 kfree(conn->auth_protocol);
131 conn->auth_protocol = NULL;
134 static int chap_server_compute_md5(
135 struct iscsi_conn *conn,
136 struct iscsi_node_auth *auth,
139 unsigned int *nr_out_len)
143 unsigned char id_as_uchar;
144 unsigned char digest[MD5_SIGNATURE_SIZE];
145 unsigned char type, response[MD5_SIGNATURE_SIZE * 2 + 2];
146 unsigned char identifier[10], *challenge = NULL;
147 unsigned char *challenge_binhex = NULL;
148 unsigned char client_digest[MD5_SIGNATURE_SIZE];
149 unsigned char server_digest[MD5_SIGNATURE_SIZE];
150 unsigned char chap_n[MAX_CHAP_N_SIZE], chap_r[MAX_RESPONSE_LENGTH];
152 struct iscsi_chap *chap = conn->auth_protocol;
153 struct crypto_hash *tfm;
154 struct hash_desc desc;
155 struct scatterlist sg;
156 int auth_ret = -1, ret, challenge_len;
158 memset(identifier, 0, 10);
159 memset(chap_n, 0, MAX_CHAP_N_SIZE);
160 memset(chap_r, 0, MAX_RESPONSE_LENGTH);
161 memset(digest, 0, MD5_SIGNATURE_SIZE);
162 memset(response, 0, MD5_SIGNATURE_SIZE * 2 + 2);
163 memset(client_digest, 0, MD5_SIGNATURE_SIZE);
164 memset(server_digest, 0, MD5_SIGNATURE_SIZE);
166 challenge = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL);
168 pr_err("Unable to allocate challenge buffer\n");
172 challenge_binhex = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL);
173 if (!challenge_binhex) {
174 pr_err("Unable to allocate challenge_binhex buffer\n");
180 if (extract_param(nr_in_ptr, "CHAP_N", MAX_CHAP_N_SIZE, chap_n,
182 pr_err("Could not find CHAP_N.\n");
186 pr_err("Could not find CHAP_N.\n");
190 /* Include the terminating NULL in the compare */
191 compare_len = strlen(auth->userid) + 1;
192 if (strncmp(chap_n, auth->userid, compare_len) != 0) {
193 pr_err("CHAP_N values do not match!\n");
196 pr_debug("[server] Got CHAP_N=%s\n", chap_n);
200 if (extract_param(nr_in_ptr, "CHAP_R", MAX_RESPONSE_LENGTH, chap_r,
202 pr_err("Could not find CHAP_R.\n");
206 pr_err("Could not find CHAP_R.\n");
210 pr_debug("[server] Got CHAP_R=%s\n", chap_r);
211 chap_string_to_hex(client_digest, chap_r, strlen(chap_r));
213 tfm = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC);
215 pr_err("Unable to allocate struct crypto_hash\n");
221 ret = crypto_hash_init(&desc);
223 pr_err("crypto_hash_init() failed\n");
224 crypto_free_hash(tfm);
228 sg_init_one(&sg, &chap->id, 1);
229 ret = crypto_hash_update(&desc, &sg, 1);
231 pr_err("crypto_hash_update() failed for id\n");
232 crypto_free_hash(tfm);
236 sg_init_one(&sg, &auth->password, strlen(auth->password));
237 ret = crypto_hash_update(&desc, &sg, strlen(auth->password));
239 pr_err("crypto_hash_update() failed for password\n");
240 crypto_free_hash(tfm);
244 sg_init_one(&sg, chap->challenge, CHAP_CHALLENGE_LENGTH);
245 ret = crypto_hash_update(&desc, &sg, CHAP_CHALLENGE_LENGTH);
247 pr_err("crypto_hash_update() failed for challenge\n");
248 crypto_free_hash(tfm);
252 ret = crypto_hash_final(&desc, server_digest);
254 pr_err("crypto_hash_final() failed for server digest\n");
255 crypto_free_hash(tfm);
258 crypto_free_hash(tfm);
260 chap_binaryhex_to_asciihex(response, server_digest, MD5_SIGNATURE_SIZE);
261 pr_debug("[server] MD5 Server Digest: %s\n", response);
263 if (memcmp(server_digest, client_digest, MD5_SIGNATURE_SIZE) != 0) {
264 pr_debug("[server] MD5 Digests do not match!\n\n");
267 pr_debug("[server] MD5 Digests match, CHAP connetication"
270 * One way authentication has succeeded, return now if mutual
271 * authentication is not enabled.
273 if (!auth->authenticate_target) {
275 kfree(challenge_binhex);
281 if (extract_param(nr_in_ptr, "CHAP_I", 10, identifier, &type) < 0) {
282 pr_err("Could not find CHAP_I.\n");
287 id = simple_strtoul(&identifier[2], &endptr, 0);
289 id = simple_strtoul(identifier, &endptr, 0);
291 pr_err("chap identifier: %lu greater than 255\n", id);
295 * RFC 1994 says Identifier is no more than octet (8 bits).
297 pr_debug("[server] Got CHAP_I=%lu\n", id);
301 if (extract_param(nr_in_ptr, "CHAP_C", CHAP_CHALLENGE_STR_LEN,
302 challenge, &type) < 0) {
303 pr_err("Could not find CHAP_C.\n");
308 pr_err("Could not find CHAP_C.\n");
311 pr_debug("[server] Got CHAP_C=%s\n", challenge);
312 challenge_len = chap_string_to_hex(challenge_binhex, challenge,
314 if (!challenge_len) {
315 pr_err("Unable to convert incoming challenge\n");
319 * During mutual authentication, the CHAP_C generated by the
320 * initiator must not match the original CHAP_C generated by
323 if (!memcmp(challenge_binhex, chap->challenge, CHAP_CHALLENGE_LENGTH)) {
324 pr_err("initiator CHAP_C matches target CHAP_C, failing"
329 * Generate CHAP_N and CHAP_R for mutual authentication.
331 tfm = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC);
333 pr_err("Unable to allocate struct crypto_hash\n");
339 ret = crypto_hash_init(&desc);
341 pr_err("crypto_hash_init() failed\n");
342 crypto_free_hash(tfm);
346 /* To handle both endiannesses */
348 sg_init_one(&sg, &id_as_uchar, 1);
349 ret = crypto_hash_update(&desc, &sg, 1);
351 pr_err("crypto_hash_update() failed for id\n");
352 crypto_free_hash(tfm);
356 sg_init_one(&sg, auth->password_mutual,
357 strlen(auth->password_mutual));
358 ret = crypto_hash_update(&desc, &sg, strlen(auth->password_mutual));
360 pr_err("crypto_hash_update() failed for"
361 " password_mutual\n");
362 crypto_free_hash(tfm);
366 * Convert received challenge to binary hex.
368 sg_init_one(&sg, challenge_binhex, challenge_len);
369 ret = crypto_hash_update(&desc, &sg, challenge_len);
371 pr_err("crypto_hash_update() failed for ma challenge\n");
372 crypto_free_hash(tfm);
376 ret = crypto_hash_final(&desc, digest);
378 pr_err("crypto_hash_final() failed for ma digest\n");
379 crypto_free_hash(tfm);
382 crypto_free_hash(tfm);
384 * Generate CHAP_N and CHAP_R.
386 *nr_out_len = sprintf(nr_out_ptr, "CHAP_N=%s", auth->userid_mutual);
388 pr_debug("[server] Sending CHAP_N=%s\n", auth->userid_mutual);
390 * Convert response from binary hex to ascii hext.
392 chap_binaryhex_to_asciihex(response, digest, MD5_SIGNATURE_SIZE);
393 *nr_out_len += sprintf(nr_out_ptr + *nr_out_len, "CHAP_R=0x%s",
396 pr_debug("[server] Sending CHAP_R=0x%s\n", response);
400 kfree(challenge_binhex);
404 static int chap_got_response(
405 struct iscsi_conn *conn,
406 struct iscsi_node_auth *auth,
409 unsigned int *nr_out_len)
411 struct iscsi_chap *chap = conn->auth_protocol;
413 switch (chap->digest_type) {
414 case CHAP_DIGEST_MD5:
415 if (chap_server_compute_md5(conn, auth, nr_in_ptr,
416 nr_out_ptr, nr_out_len) < 0)
420 pr_err("Unknown CHAP digest type %d!\n",
427 struct iscsi_conn *conn,
428 struct iscsi_node_auth *auth,
434 struct iscsi_chap *chap = conn->auth_protocol;
437 chap = chap_server_open(conn, auth, in_text, out_text, out_len);
440 chap->chap_state = CHAP_STAGE_SERVER_AIC;
442 } else if (chap->chap_state == CHAP_STAGE_SERVER_AIC) {
443 convert_null_to_semi(in_text, *in_len);
444 if (chap_got_response(conn, auth, in_text, out_text,
449 if (auth->authenticate_target)
450 chap->chap_state = CHAP_STAGE_SERVER_NR;