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e48354ce NB |
1 | /******************************************************************************* |
2 | * This file houses the main functions for the iSCSI CHAP support | |
3 | * | |
4 | * \u00a9 Copyright 2007-2011 RisingTide Systems LLC. | |
5 | * | |
6 | * Licensed to the Linux Foundation under the General Public License (GPL) version 2. | |
7 | * | |
8 | * Author: Nicholas A. Bellinger <nab@linux-iscsi.org> | |
9 | * | |
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. | |
14 | * | |
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 | ******************************************************************************/ | |
20 | ||
f2b56afd | 21 | #include <linux/kernel.h> |
e48354ce NB |
22 | #include <linux/string.h> |
23 | #include <linux/crypto.h> | |
24 | #include <linux/err.h> | |
25 | #include <linux/scatterlist.h> | |
26 | ||
27 | #include "iscsi_target_core.h" | |
28 | #include "iscsi_target_nego.h" | |
29 | #include "iscsi_target_auth.h" | |
30 | ||
e48354ce NB |
31 | static int chap_string_to_hex(unsigned char *dst, unsigned char *src, int len) |
32 | { | |
ddca8f3e | 33 | int j = DIV_ROUND_UP(len, 2), rc; |
e48354ce | 34 | |
ddca8f3e NB |
35 | rc = hex2bin(dst, src, j); |
36 | if (rc < 0) | |
37 | pr_debug("CHAP string contains non hex digit symbols\n"); | |
e48354ce NB |
38 | |
39 | dst[j] = '\0'; | |
40 | return j; | |
41 | } | |
42 | ||
43 | static void chap_binaryhex_to_asciihex(char *dst, char *src, int src_len) | |
44 | { | |
45 | int i; | |
46 | ||
47 | for (i = 0; i < src_len; i++) { | |
48 | sprintf(&dst[i*2], "%02x", (int) src[i] & 0xff); | |
49 | } | |
50 | } | |
51 | ||
52 | static void chap_set_random(char *data, int length) | |
53 | { | |
54 | long r; | |
55 | unsigned n; | |
56 | ||
57 | while (length > 0) { | |
58 | get_random_bytes(&r, sizeof(long)); | |
59 | r = r ^ (r >> 8); | |
60 | r = r ^ (r >> 4); | |
61 | n = r & 0x7; | |
62 | ||
63 | get_random_bytes(&r, sizeof(long)); | |
64 | r = r ^ (r >> 8); | |
65 | r = r ^ (r >> 5); | |
66 | n = (n << 3) | (r & 0x7); | |
67 | ||
68 | get_random_bytes(&r, sizeof(long)); | |
69 | r = r ^ (r >> 8); | |
70 | r = r ^ (r >> 5); | |
71 | n = (n << 2) | (r & 0x3); | |
72 | ||
73 | *data++ = n; | |
74 | length--; | |
75 | } | |
76 | } | |
77 | ||
78 | static void chap_gen_challenge( | |
79 | struct iscsi_conn *conn, | |
80 | int caller, | |
81 | char *c_str, | |
82 | unsigned int *c_len) | |
83 | { | |
84 | unsigned char challenge_asciihex[CHAP_CHALLENGE_LENGTH * 2 + 1]; | |
8359cf43 | 85 | struct iscsi_chap *chap = conn->auth_protocol; |
e48354ce NB |
86 | |
87 | memset(challenge_asciihex, 0, CHAP_CHALLENGE_LENGTH * 2 + 1); | |
88 | ||
89 | chap_set_random(chap->challenge, CHAP_CHALLENGE_LENGTH); | |
90 | chap_binaryhex_to_asciihex(challenge_asciihex, chap->challenge, | |
91 | CHAP_CHALLENGE_LENGTH); | |
92 | /* | |
93 | * Set CHAP_C, and copy the generated challenge into c_str. | |
94 | */ | |
95 | *c_len += sprintf(c_str + *c_len, "CHAP_C=0x%s", challenge_asciihex); | |
96 | *c_len += 1; | |
97 | ||
98 | pr_debug("[%s] Sending CHAP_C=0x%s\n\n", (caller) ? "server" : "client", | |
99 | challenge_asciihex); | |
100 | } | |
101 | ||
102 | ||
103 | static struct iscsi_chap *chap_server_open( | |
104 | struct iscsi_conn *conn, | |
105 | struct iscsi_node_auth *auth, | |
106 | const char *a_str, | |
107 | char *aic_str, | |
108 | unsigned int *aic_len) | |
109 | { | |
110 | struct iscsi_chap *chap; | |
111 | ||
112 | if (!(auth->naf_flags & NAF_USERID_SET) || | |
113 | !(auth->naf_flags & NAF_PASSWORD_SET)) { | |
114 | pr_err("CHAP user or password not set for" | |
115 | " Initiator ACL\n"); | |
116 | return NULL; | |
117 | } | |
118 | ||
119 | conn->auth_protocol = kzalloc(sizeof(struct iscsi_chap), GFP_KERNEL); | |
120 | if (!conn->auth_protocol) | |
121 | return NULL; | |
122 | ||
8359cf43 | 123 | chap = conn->auth_protocol; |
e48354ce NB |
124 | /* |
125 | * We only support MD5 MDA presently. | |
126 | */ | |
127 | if (strncmp(a_str, "CHAP_A=5", 8)) { | |
128 | pr_err("CHAP_A is not MD5.\n"); | |
129 | return NULL; | |
130 | } | |
131 | pr_debug("[server] Got CHAP_A=5\n"); | |
132 | /* | |
133 | * Send back CHAP_A set to MD5. | |
134 | */ | |
135 | *aic_len = sprintf(aic_str, "CHAP_A=5"); | |
136 | *aic_len += 1; | |
137 | chap->digest_type = CHAP_DIGEST_MD5; | |
138 | pr_debug("[server] Sending CHAP_A=%d\n", chap->digest_type); | |
139 | /* | |
140 | * Set Identifier. | |
141 | */ | |
142 | chap->id = ISCSI_TPG_C(conn)->tpg_chap_id++; | |
143 | *aic_len += sprintf(aic_str + *aic_len, "CHAP_I=%d", chap->id); | |
144 | *aic_len += 1; | |
145 | pr_debug("[server] Sending CHAP_I=%d\n", chap->id); | |
146 | /* | |
147 | * Generate Challenge. | |
148 | */ | |
149 | chap_gen_challenge(conn, 1, aic_str, aic_len); | |
150 | ||
151 | return chap; | |
152 | } | |
153 | ||
154 | static void chap_close(struct iscsi_conn *conn) | |
155 | { | |
156 | kfree(conn->auth_protocol); | |
157 | conn->auth_protocol = NULL; | |
158 | } | |
159 | ||
160 | static int chap_server_compute_md5( | |
161 | struct iscsi_conn *conn, | |
162 | struct iscsi_node_auth *auth, | |
163 | char *nr_in_ptr, | |
164 | char *nr_out_ptr, | |
165 | unsigned int *nr_out_len) | |
166 | { | |
167 | char *endptr; | |
bc704fb5 NB |
168 | unsigned long id; |
169 | unsigned char digest[MD5_SIGNATURE_SIZE]; | |
e48354ce NB |
170 | unsigned char type, response[MD5_SIGNATURE_SIZE * 2 + 2]; |
171 | unsigned char identifier[10], *challenge = NULL; | |
172 | unsigned char *challenge_binhex = NULL; | |
173 | unsigned char client_digest[MD5_SIGNATURE_SIZE]; | |
174 | unsigned char server_digest[MD5_SIGNATURE_SIZE]; | |
175 | unsigned char chap_n[MAX_CHAP_N_SIZE], chap_r[MAX_RESPONSE_LENGTH]; | |
8359cf43 | 176 | struct iscsi_chap *chap = conn->auth_protocol; |
e48354ce NB |
177 | struct crypto_hash *tfm; |
178 | struct hash_desc desc; | |
179 | struct scatterlist sg; | |
180 | int auth_ret = -1, ret, challenge_len; | |
181 | ||
182 | memset(identifier, 0, 10); | |
183 | memset(chap_n, 0, MAX_CHAP_N_SIZE); | |
184 | memset(chap_r, 0, MAX_RESPONSE_LENGTH); | |
185 | memset(digest, 0, MD5_SIGNATURE_SIZE); | |
186 | memset(response, 0, MD5_SIGNATURE_SIZE * 2 + 2); | |
187 | memset(client_digest, 0, MD5_SIGNATURE_SIZE); | |
188 | memset(server_digest, 0, MD5_SIGNATURE_SIZE); | |
189 | ||
190 | challenge = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL); | |
191 | if (!challenge) { | |
192 | pr_err("Unable to allocate challenge buffer\n"); | |
193 | goto out; | |
194 | } | |
195 | ||
196 | challenge_binhex = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL); | |
197 | if (!challenge_binhex) { | |
198 | pr_err("Unable to allocate challenge_binhex buffer\n"); | |
199 | goto out; | |
200 | } | |
201 | /* | |
202 | * Extract CHAP_N. | |
203 | */ | |
204 | if (extract_param(nr_in_ptr, "CHAP_N", MAX_CHAP_N_SIZE, chap_n, | |
205 | &type) < 0) { | |
206 | pr_err("Could not find CHAP_N.\n"); | |
207 | goto out; | |
208 | } | |
209 | if (type == HEX) { | |
210 | pr_err("Could not find CHAP_N.\n"); | |
211 | goto out; | |
212 | } | |
213 | ||
214 | if (memcmp(chap_n, auth->userid, strlen(auth->userid)) != 0) { | |
215 | pr_err("CHAP_N values do not match!\n"); | |
216 | goto out; | |
217 | } | |
218 | pr_debug("[server] Got CHAP_N=%s\n", chap_n); | |
219 | /* | |
220 | * Extract CHAP_R. | |
221 | */ | |
222 | if (extract_param(nr_in_ptr, "CHAP_R", MAX_RESPONSE_LENGTH, chap_r, | |
223 | &type) < 0) { | |
224 | pr_err("Could not find CHAP_R.\n"); | |
225 | goto out; | |
226 | } | |
227 | if (type != HEX) { | |
228 | pr_err("Could not find CHAP_R.\n"); | |
229 | goto out; | |
230 | } | |
231 | ||
232 | pr_debug("[server] Got CHAP_R=%s\n", chap_r); | |
233 | chap_string_to_hex(client_digest, chap_r, strlen(chap_r)); | |
234 | ||
235 | tfm = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC); | |
236 | if (IS_ERR(tfm)) { | |
237 | pr_err("Unable to allocate struct crypto_hash\n"); | |
238 | goto out; | |
239 | } | |
240 | desc.tfm = tfm; | |
241 | desc.flags = 0; | |
242 | ||
243 | ret = crypto_hash_init(&desc); | |
244 | if (ret < 0) { | |
245 | pr_err("crypto_hash_init() failed\n"); | |
246 | crypto_free_hash(tfm); | |
247 | goto out; | |
248 | } | |
249 | ||
8359cf43 | 250 | sg_init_one(&sg, &chap->id, 1); |
e48354ce NB |
251 | ret = crypto_hash_update(&desc, &sg, 1); |
252 | if (ret < 0) { | |
253 | pr_err("crypto_hash_update() failed for id\n"); | |
254 | crypto_free_hash(tfm); | |
255 | goto out; | |
256 | } | |
257 | ||
8359cf43 | 258 | sg_init_one(&sg, &auth->password, strlen(auth->password)); |
e48354ce NB |
259 | ret = crypto_hash_update(&desc, &sg, strlen(auth->password)); |
260 | if (ret < 0) { | |
261 | pr_err("crypto_hash_update() failed for password\n"); | |
262 | crypto_free_hash(tfm); | |
263 | goto out; | |
264 | } | |
265 | ||
8359cf43 | 266 | sg_init_one(&sg, chap->challenge, CHAP_CHALLENGE_LENGTH); |
e48354ce NB |
267 | ret = crypto_hash_update(&desc, &sg, CHAP_CHALLENGE_LENGTH); |
268 | if (ret < 0) { | |
269 | pr_err("crypto_hash_update() failed for challenge\n"); | |
270 | crypto_free_hash(tfm); | |
271 | goto out; | |
272 | } | |
273 | ||
274 | ret = crypto_hash_final(&desc, server_digest); | |
275 | if (ret < 0) { | |
276 | pr_err("crypto_hash_final() failed for server digest\n"); | |
277 | crypto_free_hash(tfm); | |
278 | goto out; | |
279 | } | |
280 | crypto_free_hash(tfm); | |
281 | ||
282 | chap_binaryhex_to_asciihex(response, server_digest, MD5_SIGNATURE_SIZE); | |
283 | pr_debug("[server] MD5 Server Digest: %s\n", response); | |
284 | ||
285 | if (memcmp(server_digest, client_digest, MD5_SIGNATURE_SIZE) != 0) { | |
286 | pr_debug("[server] MD5 Digests do not match!\n\n"); | |
287 | goto out; | |
288 | } else | |
289 | pr_debug("[server] MD5 Digests match, CHAP connetication" | |
290 | " successful.\n\n"); | |
291 | /* | |
292 | * One way authentication has succeeded, return now if mutual | |
293 | * authentication is not enabled. | |
294 | */ | |
295 | if (!auth->authenticate_target) { | |
296 | kfree(challenge); | |
297 | kfree(challenge_binhex); | |
298 | return 0; | |
299 | } | |
300 | /* | |
301 | * Get CHAP_I. | |
302 | */ | |
303 | if (extract_param(nr_in_ptr, "CHAP_I", 10, identifier, &type) < 0) { | |
304 | pr_err("Could not find CHAP_I.\n"); | |
305 | goto out; | |
306 | } | |
307 | ||
308 | if (type == HEX) | |
8359cf43 | 309 | id = simple_strtoul(&identifier[2], &endptr, 0); |
e48354ce | 310 | else |
8359cf43 | 311 | id = simple_strtoul(identifier, &endptr, 0); |
bc704fb5 NB |
312 | if (id > 255) { |
313 | pr_err("chap identifier: %lu greater than 255\n", id); | |
314 | goto out; | |
315 | } | |
e48354ce NB |
316 | /* |
317 | * RFC 1994 says Identifier is no more than octet (8 bits). | |
318 | */ | |
bc704fb5 | 319 | pr_debug("[server] Got CHAP_I=%lu\n", id); |
e48354ce NB |
320 | /* |
321 | * Get CHAP_C. | |
322 | */ | |
323 | if (extract_param(nr_in_ptr, "CHAP_C", CHAP_CHALLENGE_STR_LEN, | |
324 | challenge, &type) < 0) { | |
325 | pr_err("Could not find CHAP_C.\n"); | |
326 | goto out; | |
327 | } | |
328 | ||
329 | if (type != HEX) { | |
330 | pr_err("Could not find CHAP_C.\n"); | |
331 | goto out; | |
332 | } | |
333 | pr_debug("[server] Got CHAP_C=%s\n", challenge); | |
334 | challenge_len = chap_string_to_hex(challenge_binhex, challenge, | |
335 | strlen(challenge)); | |
336 | if (!challenge_len) { | |
337 | pr_err("Unable to convert incoming challenge\n"); | |
338 | goto out; | |
339 | } | |
340 | /* | |
341 | * Generate CHAP_N and CHAP_R for mutual authentication. | |
342 | */ | |
343 | tfm = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC); | |
344 | if (IS_ERR(tfm)) { | |
345 | pr_err("Unable to allocate struct crypto_hash\n"); | |
346 | goto out; | |
347 | } | |
348 | desc.tfm = tfm; | |
349 | desc.flags = 0; | |
350 | ||
351 | ret = crypto_hash_init(&desc); | |
352 | if (ret < 0) { | |
353 | pr_err("crypto_hash_init() failed\n"); | |
354 | crypto_free_hash(tfm); | |
355 | goto out; | |
356 | } | |
357 | ||
8359cf43 | 358 | sg_init_one(&sg, &id, 1); |
e48354ce NB |
359 | ret = crypto_hash_update(&desc, &sg, 1); |
360 | if (ret < 0) { | |
361 | pr_err("crypto_hash_update() failed for id\n"); | |
362 | crypto_free_hash(tfm); | |
363 | goto out; | |
364 | } | |
365 | ||
8359cf43 | 366 | sg_init_one(&sg, auth->password_mutual, |
e48354ce NB |
367 | strlen(auth->password_mutual)); |
368 | ret = crypto_hash_update(&desc, &sg, strlen(auth->password_mutual)); | |
369 | if (ret < 0) { | |
370 | pr_err("crypto_hash_update() failed for" | |
371 | " password_mutual\n"); | |
372 | crypto_free_hash(tfm); | |
373 | goto out; | |
374 | } | |
375 | /* | |
376 | * Convert received challenge to binary hex. | |
377 | */ | |
8359cf43 | 378 | sg_init_one(&sg, challenge_binhex, challenge_len); |
e48354ce NB |
379 | ret = crypto_hash_update(&desc, &sg, challenge_len); |
380 | if (ret < 0) { | |
381 | pr_err("crypto_hash_update() failed for ma challenge\n"); | |
382 | crypto_free_hash(tfm); | |
383 | goto out; | |
384 | } | |
385 | ||
386 | ret = crypto_hash_final(&desc, digest); | |
387 | if (ret < 0) { | |
388 | pr_err("crypto_hash_final() failed for ma digest\n"); | |
389 | crypto_free_hash(tfm); | |
390 | goto out; | |
391 | } | |
392 | crypto_free_hash(tfm); | |
393 | /* | |
394 | * Generate CHAP_N and CHAP_R. | |
395 | */ | |
396 | *nr_out_len = sprintf(nr_out_ptr, "CHAP_N=%s", auth->userid_mutual); | |
397 | *nr_out_len += 1; | |
398 | pr_debug("[server] Sending CHAP_N=%s\n", auth->userid_mutual); | |
399 | /* | |
400 | * Convert response from binary hex to ascii hext. | |
401 | */ | |
402 | chap_binaryhex_to_asciihex(response, digest, MD5_SIGNATURE_SIZE); | |
403 | *nr_out_len += sprintf(nr_out_ptr + *nr_out_len, "CHAP_R=0x%s", | |
404 | response); | |
405 | *nr_out_len += 1; | |
406 | pr_debug("[server] Sending CHAP_R=0x%s\n", response); | |
407 | auth_ret = 0; | |
408 | out: | |
409 | kfree(challenge); | |
410 | kfree(challenge_binhex); | |
411 | return auth_ret; | |
412 | } | |
413 | ||
414 | static int chap_got_response( | |
415 | struct iscsi_conn *conn, | |
416 | struct iscsi_node_auth *auth, | |
417 | char *nr_in_ptr, | |
418 | char *nr_out_ptr, | |
419 | unsigned int *nr_out_len) | |
420 | { | |
8359cf43 | 421 | struct iscsi_chap *chap = conn->auth_protocol; |
e48354ce NB |
422 | |
423 | switch (chap->digest_type) { | |
424 | case CHAP_DIGEST_MD5: | |
425 | if (chap_server_compute_md5(conn, auth, nr_in_ptr, | |
426 | nr_out_ptr, nr_out_len) < 0) | |
427 | return -1; | |
428 | return 0; | |
429 | default: | |
430 | pr_err("Unknown CHAP digest type %d!\n", | |
431 | chap->digest_type); | |
432 | return -1; | |
433 | } | |
434 | } | |
435 | ||
436 | u32 chap_main_loop( | |
437 | struct iscsi_conn *conn, | |
438 | struct iscsi_node_auth *auth, | |
439 | char *in_text, | |
440 | char *out_text, | |
441 | int *in_len, | |
442 | int *out_len) | |
443 | { | |
8359cf43 | 444 | struct iscsi_chap *chap = conn->auth_protocol; |
e48354ce NB |
445 | |
446 | if (!chap) { | |
447 | chap = chap_server_open(conn, auth, in_text, out_text, out_len); | |
448 | if (!chap) | |
449 | return 2; | |
450 | chap->chap_state = CHAP_STAGE_SERVER_AIC; | |
451 | return 0; | |
452 | } else if (chap->chap_state == CHAP_STAGE_SERVER_AIC) { | |
453 | convert_null_to_semi(in_text, *in_len); | |
454 | if (chap_got_response(conn, auth, in_text, out_text, | |
455 | out_len) < 0) { | |
456 | chap_close(conn); | |
457 | return 2; | |
458 | } | |
459 | if (auth->authenticate_target) | |
460 | chap->chap_state = CHAP_STAGE_SERVER_NR; | |
461 | else | |
462 | *out_len = 0; | |
463 | chap_close(conn); | |
464 | return 1; | |
465 | } | |
466 | ||
467 | return 2; | |
468 | } |