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19#include <linux/kernel.h>
20#include <linux/string.h>
21#include <linux/crypto.h>
22#include <linux/err.h>
23#include <linux/scatterlist.h>
24
25#include "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 void chap_gen_challenge(
51 struct iscsi_conn *conn,
52 int caller,
53 char *c_str,
54 unsigned int *c_len)
55{
56 unsigned char challenge_asciihex[CHAP_CHALLENGE_LENGTH * 2 + 1];
57 struct iscsi_chap *chap = conn->auth_protocol;
58
59 memset(challenge_asciihex, 0, CHAP_CHALLENGE_LENGTH * 2 + 1);
60
61 get_random_bytes(chap->challenge, CHAP_CHALLENGE_LENGTH);
62 chap_binaryhex_to_asciihex(challenge_asciihex, chap->challenge,
63 CHAP_CHALLENGE_LENGTH);
64
65
66
67 *c_len += sprintf(c_str + *c_len, "CHAP_C=0x%s", challenge_asciihex);
68 *c_len += 1;
69
70 pr_debug("[%s] Sending CHAP_C=0x%s\n\n", (caller) ? "server" : "client",
71 challenge_asciihex);
72}
73
74static int chap_check_algorithm(const char *a_str)
75{
76 char *tmp, *orig, *token;
77
78 tmp = kstrdup(a_str, GFP_KERNEL);
79 if (!tmp) {
80 pr_err("Memory allocation failed for CHAP_A temporary buffer\n");
81 return CHAP_DIGEST_UNKNOWN;
82 }
83 orig = tmp;
84
85 token = strsep(&tmp, "=");
86 if (!token)
87 goto out;
88
89 if (strcmp(token, "CHAP_A")) {
90 pr_err("Unable to locate CHAP_A key\n");
91 goto out;
92 }
93 while (token) {
94 token = strsep(&tmp, ",");
95 if (!token)
96 goto out;
97
98 if (!strncmp(token, "5", 1)) {
99 pr_debug("Selected MD5 Algorithm\n");
100 kfree(orig);
101 return CHAP_DIGEST_MD5;
102 }
103 }
104out:
105 kfree(orig);
106 return CHAP_DIGEST_UNKNOWN;
107}
108
109static struct iscsi_chap *chap_server_open(
110 struct iscsi_conn *conn,
111 struct iscsi_node_auth *auth,
112 const char *a_str,
113 char *aic_str,
114 unsigned int *aic_len)
115{
116 int ret;
117 struct iscsi_chap *chap;
118
119 if (!(auth->naf_flags & NAF_USERID_SET) ||
120 !(auth->naf_flags & NAF_PASSWORD_SET)) {
121 pr_err("CHAP user or password not set for"
122 " Initiator ACL\n");
123 return NULL;
124 }
125
126 conn->auth_protocol = kzalloc(sizeof(struct iscsi_chap), GFP_KERNEL);
127 if (!conn->auth_protocol)
128 return NULL;
129
130 chap = conn->auth_protocol;
131 ret = chap_check_algorithm(a_str);
132 switch (ret) {
133 case CHAP_DIGEST_MD5:
134 pr_debug("[server] Got CHAP_A=5\n");
135
136
137
138 *aic_len = sprintf(aic_str, "CHAP_A=5");
139 *aic_len += 1;
140 chap->digest_type = CHAP_DIGEST_MD5;
141 pr_debug("[server] Sending CHAP_A=%d\n", chap->digest_type);
142 break;
143 case CHAP_DIGEST_UNKNOWN:
144 default:
145 pr_err("Unsupported CHAP_A value\n");
146 return NULL;
147 }
148
149
150
151
152 chap->id = conn->tpg->tpg_chap_id++;
153 *aic_len += sprintf(aic_str + *aic_len, "CHAP_I=%d", chap->id);
154 *aic_len += 1;
155 pr_debug("[server] Sending CHAP_I=%d\n", chap->id);
156
157
158
159 chap_gen_challenge(conn, 1, aic_str, aic_len);
160
161 return chap;
162}
163
164static void chap_close(struct iscsi_conn *conn)
165{
166 kfree(conn->auth_protocol);
167 conn->auth_protocol = NULL;
168}
169
170static int chap_server_compute_md5(
171 struct iscsi_conn *conn,
172 struct iscsi_node_auth *auth,
173 char *nr_in_ptr,
174 char *nr_out_ptr,
175 unsigned int *nr_out_len)
176{
177 unsigned long id;
178 unsigned char id_as_uchar;
179 unsigned char digest[MD5_SIGNATURE_SIZE];
180 unsigned char type, response[MD5_SIGNATURE_SIZE * 2 + 2];
181 unsigned char identifier[10], *challenge = NULL;
182 unsigned char *challenge_binhex = NULL;
183 unsigned char client_digest[MD5_SIGNATURE_SIZE];
184 unsigned char server_digest[MD5_SIGNATURE_SIZE];
185 unsigned char chap_n[MAX_CHAP_N_SIZE], chap_r[MAX_RESPONSE_LENGTH];
186 size_t compare_len;
187 struct iscsi_chap *chap = conn->auth_protocol;
188 struct crypto_hash *tfm;
189 struct hash_desc desc;
190 struct scatterlist sg;
191 int auth_ret = -1, ret, challenge_len;
192
193 memset(identifier, 0, 10);
194 memset(chap_n, 0, MAX_CHAP_N_SIZE);
195 memset(chap_r, 0, MAX_RESPONSE_LENGTH);
196 memset(digest, 0, MD5_SIGNATURE_SIZE);
197 memset(response, 0, MD5_SIGNATURE_SIZE * 2 + 2);
198 memset(client_digest, 0, MD5_SIGNATURE_SIZE);
199 memset(server_digest, 0, MD5_SIGNATURE_SIZE);
200
201 challenge = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL);
202 if (!challenge) {
203 pr_err("Unable to allocate challenge buffer\n");
204 goto out;
205 }
206
207 challenge_binhex = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL);
208 if (!challenge_binhex) {
209 pr_err("Unable to allocate challenge_binhex buffer\n");
210 goto out;
211 }
212
213
214
215 if (extract_param(nr_in_ptr, "CHAP_N", MAX_CHAP_N_SIZE, chap_n,
216 &type) < 0) {
217 pr_err("Could not find CHAP_N.\n");
218 goto out;
219 }
220 if (type == HEX) {
221 pr_err("Could not find CHAP_N.\n");
222 goto out;
223 }
224
225
226 compare_len = strlen(auth->userid) + 1;
227 if (strncmp(chap_n, auth->userid, compare_len) != 0) {
228 pr_err("CHAP_N values do not match!\n");
229 goto out;
230 }
231 pr_debug("[server] Got CHAP_N=%s\n", chap_n);
232
233
234
235 if (extract_param(nr_in_ptr, "CHAP_R", MAX_RESPONSE_LENGTH, chap_r,
236 &type) < 0) {
237 pr_err("Could not find CHAP_R.\n");
238 goto out;
239 }
240 if (type != HEX) {
241 pr_err("Could not find CHAP_R.\n");
242 goto out;
243 }
244
245 pr_debug("[server] Got CHAP_R=%s\n", chap_r);
246 chap_string_to_hex(client_digest, chap_r, strlen(chap_r));
247
248 tfm = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC);
249 if (IS_ERR(tfm)) {
250 pr_err("Unable to allocate struct crypto_hash\n");
251 goto out;
252 }
253 desc.tfm = tfm;
254 desc.flags = 0;
255
256 ret = crypto_hash_init(&desc);
257 if (ret < 0) {
258 pr_err("crypto_hash_init() failed\n");
259 crypto_free_hash(tfm);
260 goto out;
261 }
262
263 sg_init_one(&sg, &chap->id, 1);
264 ret = crypto_hash_update(&desc, &sg, 1);
265 if (ret < 0) {
266 pr_err("crypto_hash_update() failed for id\n");
267 crypto_free_hash(tfm);
268 goto out;
269 }
270
271 sg_init_one(&sg, &auth->password, strlen(auth->password));
272 ret = crypto_hash_update(&desc, &sg, strlen(auth->password));
273 if (ret < 0) {
274 pr_err("crypto_hash_update() failed for password\n");
275 crypto_free_hash(tfm);
276 goto out;
277 }
278
279 sg_init_one(&sg, chap->challenge, CHAP_CHALLENGE_LENGTH);
280 ret = crypto_hash_update(&desc, &sg, CHAP_CHALLENGE_LENGTH);
281 if (ret < 0) {
282 pr_err("crypto_hash_update() failed for challenge\n");
283 crypto_free_hash(tfm);
284 goto out;
285 }
286
287 ret = crypto_hash_final(&desc, server_digest);
288 if (ret < 0) {
289 pr_err("crypto_hash_final() failed for server digest\n");
290 crypto_free_hash(tfm);
291 goto out;
292 }
293 crypto_free_hash(tfm);
294
295 chap_binaryhex_to_asciihex(response, server_digest, MD5_SIGNATURE_SIZE);
296 pr_debug("[server] MD5 Server Digest: %s\n", response);
297
298 if (memcmp(server_digest, client_digest, MD5_SIGNATURE_SIZE) != 0) {
299 pr_debug("[server] MD5 Digests do not match!\n\n");
300 goto out;
301 } else
302 pr_debug("[server] MD5 Digests match, CHAP connetication"
303 " successful.\n\n");
304
305
306
307
308 if (!auth->authenticate_target) {
309 kfree(challenge);
310 kfree(challenge_binhex);
311 return 0;
312 }
313
314
315
316 if (extract_param(nr_in_ptr, "CHAP_I", 10, identifier, &type) < 0) {
317 pr_err("Could not find CHAP_I.\n");
318 goto out;
319 }
320
321 if (type == HEX)
322 ret = kstrtoul(&identifier[2], 0, &id);
323 else
324 ret = kstrtoul(identifier, 0, &id);
325
326 if (ret < 0) {
327 pr_err("kstrtoul() failed for CHAP identifier: %d\n", ret);
328 goto out;
329 }
330 if (id > 255) {
331 pr_err("chap identifier: %lu greater than 255\n", id);
332 goto out;
333 }
334
335
336
337 pr_debug("[server] Got CHAP_I=%lu\n", id);
338
339
340
341 if (extract_param(nr_in_ptr, "CHAP_C", CHAP_CHALLENGE_STR_LEN,
342 challenge, &type) < 0) {
343 pr_err("Could not find CHAP_C.\n");
344 goto out;
345 }
346
347 if (type != HEX) {
348 pr_err("Could not find CHAP_C.\n");
349 goto out;
350 }
351 pr_debug("[server] Got CHAP_C=%s\n", challenge);
352 challenge_len = chap_string_to_hex(challenge_binhex, challenge,
353 strlen(challenge));
354 if (!challenge_len) {
355 pr_err("Unable to convert incoming challenge\n");
356 goto out;
357 }
358 if (challenge_len > 1024) {
359 pr_err("CHAP_C exceeds maximum binary size of 1024 bytes\n");
360 goto out;
361 }
362
363
364
365
366
367 if (!memcmp(challenge_binhex, chap->challenge, CHAP_CHALLENGE_LENGTH)) {
368 pr_err("initiator CHAP_C matches target CHAP_C, failing"
369 " login attempt\n");
370 goto out;
371 }
372
373
374
375 tfm = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC);
376 if (IS_ERR(tfm)) {
377 pr_err("Unable to allocate struct crypto_hash\n");
378 goto out;
379 }
380 desc.tfm = tfm;
381 desc.flags = 0;
382
383 ret = crypto_hash_init(&desc);
384 if (ret < 0) {
385 pr_err("crypto_hash_init() failed\n");
386 crypto_free_hash(tfm);
387 goto out;
388 }
389
390
391 id_as_uchar = id;
392 sg_init_one(&sg, &id_as_uchar, 1);
393 ret = crypto_hash_update(&desc, &sg, 1);
394 if (ret < 0) {
395 pr_err("crypto_hash_update() failed for id\n");
396 crypto_free_hash(tfm);
397 goto out;
398 }
399
400 sg_init_one(&sg, auth->password_mutual,
401 strlen(auth->password_mutual));
402 ret = crypto_hash_update(&desc, &sg, strlen(auth->password_mutual));
403 if (ret < 0) {
404 pr_err("crypto_hash_update() failed for"
405 " password_mutual\n");
406 crypto_free_hash(tfm);
407 goto out;
408 }
409
410
411
412 sg_init_one(&sg, challenge_binhex, challenge_len);
413 ret = crypto_hash_update(&desc, &sg, challenge_len);
414 if (ret < 0) {
415 pr_err("crypto_hash_update() failed for ma challenge\n");
416 crypto_free_hash(tfm);
417 goto out;
418 }
419
420 ret = crypto_hash_final(&desc, digest);
421 if (ret < 0) {
422 pr_err("crypto_hash_final() failed for ma digest\n");
423 crypto_free_hash(tfm);
424 goto out;
425 }
426 crypto_free_hash(tfm);
427
428
429
430 *nr_out_len = sprintf(nr_out_ptr, "CHAP_N=%s", auth->userid_mutual);
431 *nr_out_len += 1;
432 pr_debug("[server] Sending CHAP_N=%s\n", auth->userid_mutual);
433
434
435
436 chap_binaryhex_to_asciihex(response, digest, MD5_SIGNATURE_SIZE);
437 *nr_out_len += sprintf(nr_out_ptr + *nr_out_len, "CHAP_R=0x%s",
438 response);
439 *nr_out_len += 1;
440 pr_debug("[server] Sending CHAP_R=0x%s\n", response);
441 auth_ret = 0;
442out:
443 kfree(challenge);
444 kfree(challenge_binhex);
445 return auth_ret;
446}
447
448static int chap_got_response(
449 struct iscsi_conn *conn,
450 struct iscsi_node_auth *auth,
451 char *nr_in_ptr,
452 char *nr_out_ptr,
453 unsigned int *nr_out_len)
454{
455 struct iscsi_chap *chap = conn->auth_protocol;
456
457 switch (chap->digest_type) {
458 case CHAP_DIGEST_MD5:
459 if (chap_server_compute_md5(conn, auth, nr_in_ptr,
460 nr_out_ptr, nr_out_len) < 0)
461 return -1;
462 return 0;
463 default:
464 pr_err("Unknown CHAP digest type %d!\n",
465 chap->digest_type);
466 return -1;
467 }
468}
469
470u32 chap_main_loop(
471 struct iscsi_conn *conn,
472 struct iscsi_node_auth *auth,
473 char *in_text,
474 char *out_text,
475 int *in_len,
476 int *out_len)
477{
478 struct iscsi_chap *chap = conn->auth_protocol;
479
480 if (!chap) {
481 chap = chap_server_open(conn, auth, in_text, out_text, out_len);
482 if (!chap)
483 return 2;
484 chap->chap_state = CHAP_STAGE_SERVER_AIC;
485 return 0;
486 } else if (chap->chap_state == CHAP_STAGE_SERVER_AIC) {
487 convert_null_to_semi(in_text, *in_len);
488 if (chap_got_response(conn, auth, in_text, out_text,
489 out_len) < 0) {
490 chap_close(conn);
491 return 2;
492 }
493 if (auth->authenticate_target)
494 chap->chap_state = CHAP_STAGE_SERVER_NR;
495 else
496 *out_len = 0;
497 chap_close(conn);
498 return 1;
499 }
500
501 return 2;
502}
503
