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19#include <crypto/hash.h>
20#include <linux/kernel.h>
21#include <linux/string.h>
22#include <linux/err.h>
23#include <linux/random.h>
24#include <linux/scatterlist.h>
25#include <target/iscsi/iscsi_target_core.h>
26#include "iscsi_target_nego.h"
27#include "iscsi_target_auth.h"
28
29static int chap_string_to_hex(unsigned char *dst, unsigned char *src, int len)
30{
31 int j = DIV_ROUND_UP(len, 2), rc;
32
33 rc = hex2bin(dst, src, j);
34 if (rc < 0)
35 pr_debug("CHAP string contains non hex digit symbols\n");
36
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
50static int chap_gen_challenge(
51 struct iscsi_conn *conn,
52 int caller,
53 char *c_str,
54 unsigned int *c_len)
55{
56 int ret;
57 unsigned char challenge_asciihex[CHAP_CHALLENGE_LENGTH * 2 + 1];
58 struct iscsi_chap *chap = conn->auth_protocol;
59
60 memset(challenge_asciihex, 0, CHAP_CHALLENGE_LENGTH * 2 + 1);
61
62 ret = get_random_bytes_wait(chap->challenge, CHAP_CHALLENGE_LENGTH);
63 if (unlikely(ret))
64 return ret;
65 chap_binaryhex_to_asciihex(challenge_asciihex, chap->challenge,
66 CHAP_CHALLENGE_LENGTH);
67
68
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);
75 return 0;
76}
77
78static 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}
112
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{
120 int ret;
121 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
134 chap = conn->auth_protocol;
135 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
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");
150 kfree(conn->auth_protocol);
151 return NULL;
152 }
153
154
155
156
157 chap->id = conn->tpg->tpg_chap_id++;
158 *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
163
164 if (chap_gen_challenge(conn, 1, aic_str, aic_len) < 0) {
165 kfree(conn->auth_protocol);
166 return NULL;
167 }
168
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{
185 unsigned long id;
186 unsigned char id_as_uchar;
187 unsigned char digest[MD5_SIGNATURE_SIZE];
188 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];
194 size_t compare_len;
195 struct iscsi_chap *chap = conn->auth_protocol;
196 struct crypto_shash *tfm = NULL;
197 struct shash_desc *desc = NULL;
198 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
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
232
233 compare_len = strlen(auth->userid) + 1;
234 if (strncmp(chap_n, auth->userid, compare_len) != 0) {
235 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
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
255 tfm = crypto_alloc_shash("md5", 0, 0);
256 if (IS_ERR(tfm)) {
257 tfm = NULL;
258 pr_err("Unable to allocate struct crypto_shash\n");
259 goto out;
260 }
261
262 desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(tfm), GFP_KERNEL);
263 if (!desc) {
264 pr_err("Unable to allocate struct shash_desc\n");
265 goto out;
266 }
267
268 desc->tfm = tfm;
269 desc->flags = 0;
270
271 ret = crypto_shash_init(desc);
272 if (ret < 0) {
273 pr_err("crypto_shash_init() failed\n");
274 goto out;
275 }
276
277 ret = crypto_shash_update(desc, &chap->id, 1);
278 if (ret < 0) {
279 pr_err("crypto_shash_update() failed for id\n");
280 goto out;
281 }
282
283 ret = crypto_shash_update(desc, (char *)&auth->password,
284 strlen(auth->password));
285 if (ret < 0) {
286 pr_err("crypto_shash_update() failed for password\n");
287 goto out;
288 }
289
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 }
296
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
304 pr_debug("[server] MD5 Digests match, CHAP connection"
305 " successful.\n\n");
306
307
308
309
310 if (!auth->authenticate_target) {
311 auth_ret = 0;
312 goto out;
313 }
314
315
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)
323 ret = kstrtoul(&identifier[2], 0, &id);
324 else
325 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 }
331 if (id > 255) {
332 pr_err("chap identifier: %lu greater than 255\n", id);
333 goto out;
334 }
335
336
337
338 pr_debug("[server] Got CHAP_I=%lu\n", id);
339
340
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 }
359 if (challenge_len > 1024) {
360 pr_err("CHAP_C exceeds maximum binary size of 1024 bytes\n");
361 goto out;
362 }
363
364
365
366
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
374
375
376 ret = crypto_shash_init(desc);
377 if (ret < 0) {
378 pr_err("crypto_shash_init() failed\n");
379 goto out;
380 }
381
382
383 id_as_uchar = id;
384 ret = crypto_shash_update(desc, &id_as_uchar, 1);
385 if (ret < 0) {
386 pr_err("crypto_shash_update() failed for id\n");
387 goto out;
388 }
389
390 ret = crypto_shash_update(desc, auth->password_mutual,
391 strlen(auth->password_mutual));
392 if (ret < 0) {
393 pr_err("crypto_shash_update() failed for"
394 " password_mutual\n");
395 goto out;
396 }
397
398
399
400 ret = crypto_shash_finup(desc, challenge_binhex, challenge_len,
401 digest);
402 if (ret < 0) {
403 pr_err("crypto_shash_finup() failed for ma challenge\n");
404 goto out;
405 }
406
407
408
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
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:
423 kzfree(desc);
424 if (tfm)
425 crypto_free_shash(tfm);
426 kfree(challenge);
427 kfree(challenge_binhex);
428 return auth_ret;
429}
430
431static int chap_got_response(
432 struct iscsi_conn *conn,
433 struct iscsi_node_auth *auth,
434 char *nr_in_ptr,
435 char *nr_out_ptr,
436 unsigned int *nr_out_len)
437{
438 struct iscsi_chap *chap = conn->auth_protocol;
439
440 switch (chap->digest_type) {
441 case CHAP_DIGEST_MD5:
442 if (chap_server_compute_md5(conn, auth, nr_in_ptr,
443 nr_out_ptr, nr_out_len) < 0)
444 return -1;
445 return 0;
446 default:
447 pr_err("Unknown CHAP digest type %d!\n",
448 chap->digest_type);
449 return -1;
450 }
451}
452
453u32 chap_main_loop(
454 struct iscsi_conn *conn,
455 struct iscsi_node_auth *auth,
456 char *in_text,
457 char *out_text,
458 int *in_len,
459 int *out_len)
460{
461 struct iscsi_chap *chap = conn->auth_protocol;
462
463 if (!chap) {
464 chap = chap_server_open(conn, auth, in_text, out_text, out_len);
465 if (!chap)
466 return 2;
467 chap->chap_state = CHAP_STAGE_SERVER_AIC;
468 return 0;
469 } else if (chap->chap_state == CHAP_STAGE_SERVER_AIC) {
470 convert_null_to_semi(in_text, *in_len);
471 if (chap_got_response(conn, auth, in_text, out_text,
472 out_len) < 0) {
473 chap_close(conn);
474 return 2;
475 }
476 if (auth->authenticate_target)
477 chap->chap_state = CHAP_STAGE_SERVER_NR;
478 else
479 *out_len = 0;
480 chap_close(conn);
481 return 1;
482 }
483
484 return 2;
485}
486
