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Nicholas Bellingere48354c2011-07-23 06:43:04 +00001/*******************************************************************************
2 * This file houses the main functions for the iSCSI CHAP support
3 *
Nicholas Bellinger4c762512013-09-05 15:29:12 -07004 * (c) Copyright 2007-2013 Datera, Inc.
Nicholas Bellingere48354c2011-07-23 06:43:04 +00005 *
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
Herbert Xu69110e32016-01-24 21:19:52 +080019#include <crypto/hash.h>
Andy Shevchenkof2b56af2011-09-30 14:39:54 +030020#include <linux/kernel.h>
Nicholas Bellingere48354c2011-07-23 06:43:04 +000021#include <linux/string.h>
Nicholas Bellingere48354c2011-07-23 06:43:04 +000022#include <linux/err.h>
Bart Van Assche8dcf07b2016-11-14 15:47:14 -080023#include <linux/random.h>
Nicholas Bellingere48354c2011-07-23 06:43:04 +000024#include <linux/scatterlist.h>
Sagi Grimberg67f091f2015-01-07 14:57:31 +020025#include <target/iscsi/iscsi_target_core.h>
Nicholas Bellingere48354c2011-07-23 06:43:04 +000026#include "iscsi_target_nego.h"
27#include "iscsi_target_auth.h"
28
Nicholas Bellingere48354c2011-07-23 06:43:04 +000029static int chap_string_to_hex(unsigned char *dst, unsigned char *src, int len)
30{
Nicholas Bellingerddca8f32011-12-06 05:24:19 +000031 int j = DIV_ROUND_UP(len, 2), rc;
Nicholas Bellingere48354c2011-07-23 06:43:04 +000032
Nicholas Bellingerddca8f32011-12-06 05:24:19 +000033 rc = hex2bin(dst, src, j);
34 if (rc < 0)
35 pr_debug("CHAP string contains non hex digit symbols\n");
Nicholas Bellingere48354c2011-07-23 06:43:04 +000036
37 dst[j] = '\0';
38 return j;
39}
40
41static 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
Jason A. Donenfeld6787ab82017-06-07 22:34:26 -040050static int chap_gen_challenge(
Nicholas Bellingere48354c2011-07-23 06:43:04 +000051 struct iscsi_conn *conn,
52 int caller,
53 char *c_str,
54 unsigned int *c_len)
55{
Jason A. Donenfeld6787ab82017-06-07 22:34:26 -040056 int ret;
Nicholas Bellingere48354c2011-07-23 06:43:04 +000057 unsigned char challenge_asciihex[CHAP_CHALLENGE_LENGTH * 2 + 1];
Jörn Engel8359cf42011-11-24 02:05:51 +010058 struct iscsi_chap *chap = conn->auth_protocol;
Nicholas Bellingere48354c2011-07-23 06:43:04 +000059
60 memset(challenge_asciihex, 0, CHAP_CHALLENGE_LENGTH * 2 + 1);
61
Jason A. Donenfeld6787ab82017-06-07 22:34:26 -040062 ret = get_random_bytes_wait(chap->challenge, CHAP_CHALLENGE_LENGTH);
63 if (unlikely(ret))
64 return ret;
Nicholas Bellingere48354c2011-07-23 06:43:04 +000065 chap_binaryhex_to_asciihex(challenge_asciihex, chap->challenge,
66 CHAP_CHALLENGE_LENGTH);
67 /*
68 * Set CHAP_C, and copy the generated challenge into c_str.
69 */
70 *c_len += sprintf(c_str + *c_len, "CHAP_C=0x%s", challenge_asciihex);
71 *c_len += 1;
72
73 pr_debug("[%s] Sending CHAP_C=0x%s\n\n", (caller) ? "server" : "client",
74 challenge_asciihex);
Jason A. Donenfeld6787ab82017-06-07 22:34:26 -040075 return 0;
Nicholas Bellingere48354c2011-07-23 06:43:04 +000076}
77
Tejas Vaykole31607232014-05-30 11:13:47 +053078static int chap_check_algorithm(const char *a_str)
79{
80 char *tmp, *orig, *token;
81
82 tmp = kstrdup(a_str, GFP_KERNEL);
83 if (!tmp) {
84 pr_err("Memory allocation failed for CHAP_A temporary buffer\n");
85 return CHAP_DIGEST_UNKNOWN;
86 }
87 orig = tmp;
88
89 token = strsep(&tmp, "=");
90 if (!token)
91 goto out;
92
93 if (strcmp(token, "CHAP_A")) {
94 pr_err("Unable to locate CHAP_A key\n");
95 goto out;
96 }
97 while (token) {
98 token = strsep(&tmp, ",");
99 if (!token)
100 goto out;
101
102 if (!strncmp(token, "5", 1)) {
103 pr_debug("Selected MD5 Algorithm\n");
104 kfree(orig);
105 return CHAP_DIGEST_MD5;
106 }
107 }
108out:
109 kfree(orig);
110 return CHAP_DIGEST_UNKNOWN;
111}
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000112
113static struct iscsi_chap *chap_server_open(
114 struct iscsi_conn *conn,
115 struct iscsi_node_auth *auth,
116 const char *a_str,
117 char *aic_str,
118 unsigned int *aic_len)
119{
Tejas Vaykole31607232014-05-30 11:13:47 +0530120 int ret;
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000121 struct iscsi_chap *chap;
122
123 if (!(auth->naf_flags & NAF_USERID_SET) ||
124 !(auth->naf_flags & NAF_PASSWORD_SET)) {
125 pr_err("CHAP user or password not set for"
126 " Initiator ACL\n");
127 return NULL;
128 }
129
130 conn->auth_protocol = kzalloc(sizeof(struct iscsi_chap), GFP_KERNEL);
131 if (!conn->auth_protocol)
132 return NULL;
133
Jörn Engel8359cf42011-11-24 02:05:51 +0100134 chap = conn->auth_protocol;
Tejas Vaykole31607232014-05-30 11:13:47 +0530135 ret = chap_check_algorithm(a_str);
136 switch (ret) {
137 case CHAP_DIGEST_MD5:
138 pr_debug("[server] Got CHAP_A=5\n");
139 /*
140 * Send back CHAP_A set to MD5.
141 */
142 *aic_len = sprintf(aic_str, "CHAP_A=5");
143 *aic_len += 1;
144 chap->digest_type = CHAP_DIGEST_MD5;
145 pr_debug("[server] Sending CHAP_A=%d\n", chap->digest_type);
146 break;
147 case CHAP_DIGEST_UNKNOWN:
148 default:
149 pr_err("Unsupported CHAP_A value\n");
Jason A. Donenfeld6787ab82017-06-07 22:34:26 -0400150 kfree(conn->auth_protocol);
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000151 return NULL;
152 }
Tejas Vaykole31607232014-05-30 11:13:47 +0530153
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000154 /*
155 * Set Identifier.
156 */
Andy Grover60bfcf82013-10-09 11:05:58 -0700157 chap->id = conn->tpg->tpg_chap_id++;
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000158 *aic_len += sprintf(aic_str + *aic_len, "CHAP_I=%d", chap->id);
159 *aic_len += 1;
160 pr_debug("[server] Sending CHAP_I=%d\n", chap->id);
161 /*
162 * Generate Challenge.
163 */
Jason A. Donenfeld6787ab82017-06-07 22:34:26 -0400164 if (chap_gen_challenge(conn, 1, aic_str, aic_len) < 0) {
165 kfree(conn->auth_protocol);
166 return NULL;
167 }
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000168
169 return chap;
170}
171
172static void chap_close(struct iscsi_conn *conn)
173{
174 kfree(conn->auth_protocol);
175 conn->auth_protocol = NULL;
176}
177
178static int chap_server_compute_md5(
179 struct iscsi_conn *conn,
180 struct iscsi_node_auth *auth,
181 char *nr_in_ptr,
182 char *nr_out_ptr,
183 unsigned int *nr_out_len)
184{
Nicholas Bellingerbc704fb2011-11-28 01:02:07 -0800185 unsigned long id;
Andy Grover7ac9ad12013-03-04 13:52:09 -0800186 unsigned char id_as_uchar;
Nicholas Bellingerbc704fb2011-11-28 01:02:07 -0800187 unsigned char digest[MD5_SIGNATURE_SIZE];
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000188 unsigned char type, response[MD5_SIGNATURE_SIZE * 2 + 2];
189 unsigned char identifier[10], *challenge = NULL;
190 unsigned char *challenge_binhex = NULL;
191 unsigned char client_digest[MD5_SIGNATURE_SIZE];
192 unsigned char server_digest[MD5_SIGNATURE_SIZE];
193 unsigned char chap_n[MAX_CHAP_N_SIZE], chap_r[MAX_RESPONSE_LENGTH];
Eric Seppanen86784c62013-11-20 14:19:52 -0800194 size_t compare_len;
Jörn Engel8359cf42011-11-24 02:05:51 +0100195 struct iscsi_chap *chap = conn->auth_protocol;
Herbert Xu69110e32016-01-24 21:19:52 +0800196 struct crypto_shash *tfm = NULL;
197 struct shash_desc *desc = NULL;
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000198 int auth_ret = -1, ret, challenge_len;
199
200 memset(identifier, 0, 10);
201 memset(chap_n, 0, MAX_CHAP_N_SIZE);
202 memset(chap_r, 0, MAX_RESPONSE_LENGTH);
203 memset(digest, 0, MD5_SIGNATURE_SIZE);
204 memset(response, 0, MD5_SIGNATURE_SIZE * 2 + 2);
205 memset(client_digest, 0, MD5_SIGNATURE_SIZE);
206 memset(server_digest, 0, MD5_SIGNATURE_SIZE);
207
208 challenge = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL);
209 if (!challenge) {
210 pr_err("Unable to allocate challenge buffer\n");
211 goto out;
212 }
213
214 challenge_binhex = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL);
215 if (!challenge_binhex) {
216 pr_err("Unable to allocate challenge_binhex buffer\n");
217 goto out;
218 }
219 /*
220 * Extract CHAP_N.
221 */
222 if (extract_param(nr_in_ptr, "CHAP_N", MAX_CHAP_N_SIZE, chap_n,
223 &type) < 0) {
224 pr_err("Could not find CHAP_N.\n");
225 goto out;
226 }
227 if (type == HEX) {
228 pr_err("Could not find CHAP_N.\n");
229 goto out;
230 }
231
Eric Seppanen86784c62013-11-20 14:19:52 -0800232 /* Include the terminating NULL in the compare */
233 compare_len = strlen(auth->userid) + 1;
234 if (strncmp(chap_n, auth->userid, compare_len) != 0) {
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000235 pr_err("CHAP_N values do not match!\n");
236 goto out;
237 }
238 pr_debug("[server] Got CHAP_N=%s\n", chap_n);
239 /*
240 * Extract CHAP_R.
241 */
242 if (extract_param(nr_in_ptr, "CHAP_R", MAX_RESPONSE_LENGTH, chap_r,
243 &type) < 0) {
244 pr_err("Could not find CHAP_R.\n");
245 goto out;
246 }
247 if (type != HEX) {
248 pr_err("Could not find CHAP_R.\n");
249 goto out;
250 }
251
252 pr_debug("[server] Got CHAP_R=%s\n", chap_r);
253 chap_string_to_hex(client_digest, chap_r, strlen(chap_r));
254
Herbert Xu69110e32016-01-24 21:19:52 +0800255 tfm = crypto_alloc_shash("md5", 0, 0);
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000256 if (IS_ERR(tfm)) {
Herbert Xu69110e32016-01-24 21:19:52 +0800257 tfm = NULL;
258 pr_err("Unable to allocate struct crypto_shash\n");
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000259 goto out;
260 }
261
Herbert Xu69110e32016-01-24 21:19:52 +0800262 desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(tfm), GFP_KERNEL);
263 if (!desc) {
264 pr_err("Unable to allocate struct shash_desc\n");
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000265 goto out;
266 }
267
Herbert Xu69110e32016-01-24 21:19:52 +0800268 desc->tfm = tfm;
269 desc->flags = 0;
270
271 ret = crypto_shash_init(desc);
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000272 if (ret < 0) {
Herbert Xu69110e32016-01-24 21:19:52 +0800273 pr_err("crypto_shash_init() failed\n");
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000274 goto out;
275 }
276
Herbert Xu69110e32016-01-24 21:19:52 +0800277 ret = crypto_shash_update(desc, &chap->id, 1);
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000278 if (ret < 0) {
Herbert Xu69110e32016-01-24 21:19:52 +0800279 pr_err("crypto_shash_update() failed for id\n");
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000280 goto out;
281 }
282
Herbert Xu69110e32016-01-24 21:19:52 +0800283 ret = crypto_shash_update(desc, (char *)&auth->password,
284 strlen(auth->password));
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000285 if (ret < 0) {
Herbert Xu69110e32016-01-24 21:19:52 +0800286 pr_err("crypto_shash_update() failed for password\n");
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000287 goto out;
288 }
Herbert Xu69110e32016-01-24 21:19:52 +0800289
290 ret = crypto_shash_finup(desc, chap->challenge,
291 CHAP_CHALLENGE_LENGTH, server_digest);
292 if (ret < 0) {
293 pr_err("crypto_shash_finup() failed for challenge\n");
294 goto out;
295 }
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000296
297 chap_binaryhex_to_asciihex(response, server_digest, MD5_SIGNATURE_SIZE);
298 pr_debug("[server] MD5 Server Digest: %s\n", response);
299
300 if (memcmp(server_digest, client_digest, MD5_SIGNATURE_SIZE) != 0) {
301 pr_debug("[server] MD5 Digests do not match!\n\n");
302 goto out;
303 } else
Masanari Iidac01e0152016-04-20 00:27:33 +0900304 pr_debug("[server] MD5 Digests match, CHAP connection"
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000305 " successful.\n\n");
306 /*
307 * One way authentication has succeeded, return now if mutual
308 * authentication is not enabled.
309 */
310 if (!auth->authenticate_target) {
Herbert Xu69110e32016-01-24 21:19:52 +0800311 auth_ret = 0;
312 goto out;
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000313 }
314 /*
315 * Get CHAP_I.
316 */
317 if (extract_param(nr_in_ptr, "CHAP_I", 10, identifier, &type) < 0) {
318 pr_err("Could not find CHAP_I.\n");
319 goto out;
320 }
321
322 if (type == HEX)
Nicholas Bellingerb06eef62014-06-13 04:05:16 +0000323 ret = kstrtoul(&identifier[2], 0, &id);
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000324 else
Nicholas Bellingerb06eef62014-06-13 04:05:16 +0000325 ret = kstrtoul(identifier, 0, &id);
326
327 if (ret < 0) {
328 pr_err("kstrtoul() failed for CHAP identifier: %d\n", ret);
329 goto out;
330 }
Nicholas Bellingerbc704fb2011-11-28 01:02:07 -0800331 if (id > 255) {
332 pr_err("chap identifier: %lu greater than 255\n", id);
333 goto out;
334 }
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000335 /*
336 * RFC 1994 says Identifier is no more than octet (8 bits).
337 */
Nicholas Bellingerbc704fb2011-11-28 01:02:07 -0800338 pr_debug("[server] Got CHAP_I=%lu\n", id);
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000339 /*
340 * Get CHAP_C.
341 */
342 if (extract_param(nr_in_ptr, "CHAP_C", CHAP_CHALLENGE_STR_LEN,
343 challenge, &type) < 0) {
344 pr_err("Could not find CHAP_C.\n");
345 goto out;
346 }
347
348 if (type != HEX) {
349 pr_err("Could not find CHAP_C.\n");
350 goto out;
351 }
352 pr_debug("[server] Got CHAP_C=%s\n", challenge);
353 challenge_len = chap_string_to_hex(challenge_binhex, challenge,
354 strlen(challenge));
355 if (!challenge_len) {
356 pr_err("Unable to convert incoming challenge\n");
357 goto out;
358 }
Nicholas Bellingere4fae232014-06-13 04:28:31 +0000359 if (challenge_len > 1024) {
360 pr_err("CHAP_C exceeds maximum binary size of 1024 bytes\n");
361 goto out;
362 }
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000363 /*
Nicholas Bellinger1d2b60a2014-06-05 18:08:57 -0700364 * During mutual authentication, the CHAP_C generated by the
365 * initiator must not match the original CHAP_C generated by
366 * the target.
367 */
368 if (!memcmp(challenge_binhex, chap->challenge, CHAP_CHALLENGE_LENGTH)) {
369 pr_err("initiator CHAP_C matches target CHAP_C, failing"
370 " login attempt\n");
371 goto out;
372 }
373 /*
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000374 * Generate CHAP_N and CHAP_R for mutual authentication.
375 */
Herbert Xu69110e32016-01-24 21:19:52 +0800376 ret = crypto_shash_init(desc);
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000377 if (ret < 0) {
Herbert Xu69110e32016-01-24 21:19:52 +0800378 pr_err("crypto_shash_init() failed\n");
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000379 goto out;
380 }
381
Andy Grover7ac9ad12013-03-04 13:52:09 -0800382 /* To handle both endiannesses */
383 id_as_uchar = id;
Herbert Xu69110e32016-01-24 21:19:52 +0800384 ret = crypto_shash_update(desc, &id_as_uchar, 1);
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000385 if (ret < 0) {
Herbert Xu69110e32016-01-24 21:19:52 +0800386 pr_err("crypto_shash_update() failed for id\n");
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000387 goto out;
388 }
389
Herbert Xu69110e32016-01-24 21:19:52 +0800390 ret = crypto_shash_update(desc, auth->password_mutual,
391 strlen(auth->password_mutual));
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000392 if (ret < 0) {
Herbert Xu69110e32016-01-24 21:19:52 +0800393 pr_err("crypto_shash_update() failed for"
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000394 " password_mutual\n");
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000395 goto out;
396 }
397 /*
398 * Convert received challenge to binary hex.
399 */
Herbert Xu69110e32016-01-24 21:19:52 +0800400 ret = crypto_shash_finup(desc, challenge_binhex, challenge_len,
401 digest);
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000402 if (ret < 0) {
Herbert Xu69110e32016-01-24 21:19:52 +0800403 pr_err("crypto_shash_finup() failed for ma challenge\n");
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000404 goto out;
405 }
406
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000407 /*
408 * Generate CHAP_N and CHAP_R.
409 */
410 *nr_out_len = sprintf(nr_out_ptr, "CHAP_N=%s", auth->userid_mutual);
411 *nr_out_len += 1;
412 pr_debug("[server] Sending CHAP_N=%s\n", auth->userid_mutual);
413 /*
414 * Convert response from binary hex to ascii hext.
415 */
416 chap_binaryhex_to_asciihex(response, digest, MD5_SIGNATURE_SIZE);
417 *nr_out_len += sprintf(nr_out_ptr + *nr_out_len, "CHAP_R=0x%s",
418 response);
419 *nr_out_len += 1;
420 pr_debug("[server] Sending CHAP_R=0x%s\n", response);
421 auth_ret = 0;
422out:
Herbert Xu69110e32016-01-24 21:19:52 +0800423 kzfree(desc);
424 crypto_free_shash(tfm);
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000425 kfree(challenge);
426 kfree(challenge_binhex);
427 return auth_ret;
428}
429
430static int chap_got_response(
431 struct iscsi_conn *conn,
432 struct iscsi_node_auth *auth,
433 char *nr_in_ptr,
434 char *nr_out_ptr,
435 unsigned int *nr_out_len)
436{
Jörn Engel8359cf42011-11-24 02:05:51 +0100437 struct iscsi_chap *chap = conn->auth_protocol;
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000438
439 switch (chap->digest_type) {
440 case CHAP_DIGEST_MD5:
441 if (chap_server_compute_md5(conn, auth, nr_in_ptr,
442 nr_out_ptr, nr_out_len) < 0)
443 return -1;
444 return 0;
445 default:
446 pr_err("Unknown CHAP digest type %d!\n",
447 chap->digest_type);
448 return -1;
449 }
450}
451
452u32 chap_main_loop(
453 struct iscsi_conn *conn,
454 struct iscsi_node_auth *auth,
455 char *in_text,
456 char *out_text,
457 int *in_len,
458 int *out_len)
459{
Jörn Engel8359cf42011-11-24 02:05:51 +0100460 struct iscsi_chap *chap = conn->auth_protocol;
Nicholas Bellingere48354c2011-07-23 06:43:04 +0000461
462 if (!chap) {
463 chap = chap_server_open(conn, auth, in_text, out_text, out_len);
464 if (!chap)
465 return 2;
466 chap->chap_state = CHAP_STAGE_SERVER_AIC;
467 return 0;
468 } else if (chap->chap_state == CHAP_STAGE_SERVER_AIC) {
469 convert_null_to_semi(in_text, *in_len);
470 if (chap_got_response(conn, auth, in_text, out_text,
471 out_len) < 0) {
472 chap_close(conn);
473 return 2;
474 }
475 if (auth->authenticate_target)
476 chap->chap_state = CHAP_STAGE_SERVER_NR;
477 else
478 *out_len = 0;
479 chap_close(conn);
480 return 1;
481 }
482
483 return 2;
484}