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