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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 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_shash *tfm = NULL;
189 struct shash_desc *desc = NULL;
190 int auth_ret = -1, ret, challenge_len;
191
192 memset(identifier, 0, 10);
193 memset(chap_n, 0, MAX_CHAP_N_SIZE);
194 memset(chap_r, 0, MAX_RESPONSE_LENGTH);
195 memset(digest, 0, MD5_SIGNATURE_SIZE);
196 memset(response, 0, MD5_SIGNATURE_SIZE * 2 + 2);
197 memset(client_digest, 0, MD5_SIGNATURE_SIZE);
198 memset(server_digest, 0, MD5_SIGNATURE_SIZE);
199
200 challenge = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL);
201 if (!challenge) {
202 pr_err("Unable to allocate challenge buffer\n");
203 goto out;
204 }
205
206 challenge_binhex = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL);
207 if (!challenge_binhex) {
208 pr_err("Unable to allocate challenge_binhex buffer\n");
209 goto out;
210 }
211
212
213
214 if (extract_param(nr_in_ptr, "CHAP_N", MAX_CHAP_N_SIZE, chap_n,
215 &type) < 0) {
216 pr_err("Could not find CHAP_N.\n");
217 goto out;
218 }
219 if (type == HEX) {
220 pr_err("Could not find CHAP_N.\n");
221 goto out;
222 }
223
224
225 compare_len = strlen(auth->userid) + 1;
226 if (strncmp(chap_n, auth->userid, compare_len) != 0) {
227 pr_err("CHAP_N values do not match!\n");
228 goto out;
229 }
230 pr_debug("[server] Got CHAP_N=%s\n", chap_n);
231
232
233
234 if (extract_param(nr_in_ptr, "CHAP_R", MAX_RESPONSE_LENGTH, chap_r,
235 &type) < 0) {
236 pr_err("Could not find CHAP_R.\n");
237 goto out;
238 }
239 if (type != HEX) {
240 pr_err("Could not find CHAP_R.\n");
241 goto out;
242 }
243
244 pr_debug("[server] Got CHAP_R=%s\n", chap_r);
245 chap_string_to_hex(client_digest, chap_r, strlen(chap_r));
246
247 tfm = crypto_alloc_shash("md5", 0, 0);
248 if (IS_ERR(tfm)) {
249 tfm = NULL;
250 pr_err("Unable to allocate struct crypto_shash\n");
251 goto out;
252 }
253
254 desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(tfm), GFP_KERNEL);
255 if (!desc) {
256 pr_err("Unable to allocate struct shash_desc\n");
257 goto out;
258 }
259
260 desc->tfm = tfm;
261 desc->flags = 0;
262
263 ret = crypto_shash_init(desc);
264 if (ret < 0) {
265 pr_err("crypto_shash_init() failed\n");
266 goto out;
267 }
268
269 ret = crypto_shash_update(desc, &chap->id, 1);
270 if (ret < 0) {
271 pr_err("crypto_shash_update() failed for id\n");
272 goto out;
273 }
274
275 ret = crypto_shash_update(desc, (char *)&auth->password,
276 strlen(auth->password));
277 if (ret < 0) {
278 pr_err("crypto_shash_update() failed for password\n");
279 goto out;
280 }
281
282 ret = crypto_shash_finup(desc, chap->challenge,
283 CHAP_CHALLENGE_LENGTH, server_digest);
284 if (ret < 0) {
285 pr_err("crypto_shash_finup() failed for challenge\n");
286 goto out;
287 }
288
289 chap_binaryhex_to_asciihex(response, server_digest, MD5_SIGNATURE_SIZE);
290 pr_debug("[server] MD5 Server Digest: %s\n", response);
291
292 if (memcmp(server_digest, client_digest, MD5_SIGNATURE_SIZE) != 0) {
293 pr_debug("[server] MD5 Digests do not match!\n\n");
294 goto out;
295 } else
296 pr_debug("[server] MD5 Digests match, CHAP connection"
297 " successful.\n\n");
298
299
300
301
302 if (!auth->authenticate_target) {
303 auth_ret = 0;
304 goto out;
305 }
306
307
308
309 if (extract_param(nr_in_ptr, "CHAP_I", 10, identifier, &type) < 0) {
310 pr_err("Could not find CHAP_I.\n");
311 goto out;
312 }
313
314 if (type == HEX)
315 ret = kstrtoul(&identifier[2], 0, &id);
316 else
317 ret = kstrtoul(identifier, 0, &id);
318
319 if (ret < 0) {
320 pr_err("kstrtoul() failed for CHAP identifier: %d\n", ret);
321 goto out;
322 }
323 if (id > 255) {
324 pr_err("chap identifier: %lu greater than 255\n", id);
325 goto out;
326 }
327
328
329
330 pr_debug("[server] Got CHAP_I=%lu\n", id);
331
332
333
334 if (extract_param(nr_in_ptr, "CHAP_C", CHAP_CHALLENGE_STR_LEN,
335 challenge, &type) < 0) {
336 pr_err("Could not find CHAP_C.\n");
337 goto out;
338 }
339
340 if (type != HEX) {
341 pr_err("Could not find CHAP_C.\n");
342 goto out;
343 }
344 pr_debug("[server] Got CHAP_C=%s\n", challenge);
345 challenge_len = chap_string_to_hex(challenge_binhex, challenge,
346 strlen(challenge));
347 if (!challenge_len) {
348 pr_err("Unable to convert incoming challenge\n");
349 goto out;
350 }
351 if (challenge_len > 1024) {
352 pr_err("CHAP_C exceeds maximum binary size of 1024 bytes\n");
353 goto out;
354 }
355
356
357
358
359
360 if (!memcmp(challenge_binhex, chap->challenge, CHAP_CHALLENGE_LENGTH)) {
361 pr_err("initiator CHAP_C matches target CHAP_C, failing"
362 " login attempt\n");
363 goto out;
364 }
365
366
367
368 ret = crypto_shash_init(desc);
369 if (ret < 0) {
370 pr_err("crypto_shash_init() failed\n");
371 goto out;
372 }
373
374
375 id_as_uchar = id;
376 ret = crypto_shash_update(desc, &id_as_uchar, 1);
377 if (ret < 0) {
378 pr_err("crypto_shash_update() failed for id\n");
379 goto out;
380 }
381
382 ret = crypto_shash_update(desc, auth->password_mutual,
383 strlen(auth->password_mutual));
384 if (ret < 0) {
385 pr_err("crypto_shash_update() failed for"
386 " password_mutual\n");
387 goto out;
388 }
389
390
391
392 ret = crypto_shash_finup(desc, challenge_binhex, challenge_len,
393 digest);
394 if (ret < 0) {
395 pr_err("crypto_shash_finup() failed for ma challenge\n");
396 goto out;
397 }
398
399
400
401
402 *nr_out_len = sprintf(nr_out_ptr, "CHAP_N=%s", auth->userid_mutual);
403 *nr_out_len += 1;
404 pr_debug("[server] Sending CHAP_N=%s\n", auth->userid_mutual);
405
406
407
408 chap_binaryhex_to_asciihex(response, digest, MD5_SIGNATURE_SIZE);
409 *nr_out_len += sprintf(nr_out_ptr + *nr_out_len, "CHAP_R=0x%s",
410 response);
411 *nr_out_len += 1;
412 pr_debug("[server] Sending CHAP_R=0x%s\n", response);
413 auth_ret = 0;
414out:
415 kzfree(desc);
416 crypto_free_shash(tfm);
417 kfree(challenge);
418 kfree(challenge_binhex);
419 return auth_ret;
420}
421
422static int chap_got_response(
423 struct iscsi_conn *conn,
424 struct iscsi_node_auth *auth,
425 char *nr_in_ptr,
426 char *nr_out_ptr,
427 unsigned int *nr_out_len)
428{
429 struct iscsi_chap *chap = conn->auth_protocol;
430
431 switch (chap->digest_type) {
432 case CHAP_DIGEST_MD5:
433 if (chap_server_compute_md5(conn, auth, nr_in_ptr,
434 nr_out_ptr, nr_out_len) < 0)
435 return -1;
436 return 0;
437 default:
438 pr_err("Unknown CHAP digest type %d!\n",
439 chap->digest_type);
440 return -1;
441 }
442}
443
444u32 chap_main_loop(
445 struct iscsi_conn *conn,
446 struct iscsi_node_auth *auth,
447 char *in_text,
448 char *out_text,
449 int *in_len,
450 int *out_len)
451{
452 struct iscsi_chap *chap = conn->auth_protocol;
453
454 if (!chap) {
455 chap = chap_server_open(conn, auth, in_text, out_text, out_len);
456 if (!chap)
457 return 2;
458 chap->chap_state = CHAP_STAGE_SERVER_AIC;
459 return 0;
460 } else if (chap->chap_state == CHAP_STAGE_SERVER_AIC) {
461 convert_null_to_semi(in_text, *in_len);
462 if (chap_got_response(conn, auth, in_text, out_text,
463 out_len) < 0) {
464 chap_close(conn);
465 return 2;
466 }
467 if (auth->authenticate_target)
468 chap->chap_state = CHAP_STAGE_SERVER_NR;
469 else
470 *out_len = 0;
471 chap_close(conn);
472 return 1;
473 }
474
475 return 2;
476}
477
