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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_gen_challenge(
30 struct iscsi_conn *conn,
31 int caller,
32 char *c_str,
33 unsigned int *c_len)
34{
35 int ret;
36 unsigned char challenge_asciihex[CHAP_CHALLENGE_LENGTH * 2 + 1];
37 struct iscsi_chap *chap = conn->auth_protocol;
38
39 memset(challenge_asciihex, 0, CHAP_CHALLENGE_LENGTH * 2 + 1);
40
41 ret = get_random_bytes_wait(chap->challenge, CHAP_CHALLENGE_LENGTH);
42 if (unlikely(ret))
43 return ret;
44 bin2hex(challenge_asciihex, chap->challenge,
45 CHAP_CHALLENGE_LENGTH);
46
47
48
49 *c_len += sprintf(c_str + *c_len, "CHAP_C=0x%s", challenge_asciihex);
50 *c_len += 1;
51
52 pr_debug("[%s] Sending CHAP_C=0x%s\n\n", (caller) ? "server" : "client",
53 challenge_asciihex);
54 return 0;
55}
56
57static int chap_check_algorithm(const char *a_str)
58{
59 char *tmp, *orig, *token;
60
61 tmp = kstrdup(a_str, GFP_KERNEL);
62 if (!tmp) {
63 pr_err("Memory allocation failed for CHAP_A temporary buffer\n");
64 return CHAP_DIGEST_UNKNOWN;
65 }
66 orig = tmp;
67
68 token = strsep(&tmp, "=");
69 if (!token)
70 goto out;
71
72 if (strcmp(token, "CHAP_A")) {
73 pr_err("Unable to locate CHAP_A key\n");
74 goto out;
75 }
76 while (token) {
77 token = strsep(&tmp, ",");
78 if (!token)
79 goto out;
80
81 if (!strncmp(token, "5", 1)) {
82 pr_debug("Selected MD5 Algorithm\n");
83 kfree(orig);
84 return CHAP_DIGEST_MD5;
85 }
86 }
87out:
88 kfree(orig);
89 return CHAP_DIGEST_UNKNOWN;
90}
91
92static struct iscsi_chap *chap_server_open(
93 struct iscsi_conn *conn,
94 struct iscsi_node_auth *auth,
95 const char *a_str,
96 char *aic_str,
97 unsigned int *aic_len)
98{
99 int ret;
100 struct iscsi_chap *chap;
101
102 if (!(auth->naf_flags & NAF_USERID_SET) ||
103 !(auth->naf_flags & NAF_PASSWORD_SET)) {
104 pr_err("CHAP user or password not set for"
105 " Initiator ACL\n");
106 return NULL;
107 }
108
109 conn->auth_protocol = kzalloc(sizeof(struct iscsi_chap), GFP_KERNEL);
110 if (!conn->auth_protocol)
111 return NULL;
112
113 chap = conn->auth_protocol;
114 ret = chap_check_algorithm(a_str);
115 switch (ret) {
116 case CHAP_DIGEST_MD5:
117 pr_debug("[server] Got CHAP_A=5\n");
118
119
120
121 *aic_len = sprintf(aic_str, "CHAP_A=5");
122 *aic_len += 1;
123 chap->digest_type = CHAP_DIGEST_MD5;
124 pr_debug("[server] Sending CHAP_A=%d\n", chap->digest_type);
125 break;
126 case CHAP_DIGEST_UNKNOWN:
127 default:
128 pr_err("Unsupported CHAP_A value\n");
129 kfree(conn->auth_protocol);
130 return NULL;
131 }
132
133
134
135
136 chap->id = conn->tpg->tpg_chap_id++;
137 *aic_len += sprintf(aic_str + *aic_len, "CHAP_I=%d", chap->id);
138 *aic_len += 1;
139 pr_debug("[server] Sending CHAP_I=%d\n", chap->id);
140
141
142
143 if (chap_gen_challenge(conn, 1, aic_str, aic_len) < 0) {
144 kfree(conn->auth_protocol);
145 return NULL;
146 }
147
148 return chap;
149}
150
151static void chap_close(struct iscsi_conn *conn)
152{
153 kfree(conn->auth_protocol);
154 conn->auth_protocol = NULL;
155}
156
157static int chap_server_compute_md5(
158 struct iscsi_conn *conn,
159 struct iscsi_node_auth *auth,
160 char *nr_in_ptr,
161 char *nr_out_ptr,
162 unsigned int *nr_out_len)
163{
164 unsigned long id;
165 unsigned char id_as_uchar;
166 unsigned char 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 size_t compare_len;
174 struct iscsi_chap *chap = conn->auth_protocol;
175 struct crypto_shash *tfm = NULL;
176 struct shash_desc *desc = NULL;
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
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
212 compare_len = strlen(auth->userid) + 1;
213 if (strncmp(chap_n, auth->userid, compare_len) != 0) {
214 pr_err("CHAP_N values do not match!\n");
215 goto out;
216 }
217 pr_debug("[server] Got CHAP_N=%s\n", chap_n);
218
219
220
221 if (extract_param(nr_in_ptr, "CHAP_R", MAX_RESPONSE_LENGTH, chap_r,
222 &type) < 0) {
223 pr_err("Could not find CHAP_R.\n");
224 goto out;
225 }
226 if (type != HEX) {
227 pr_err("Could not find CHAP_R.\n");
228 goto out;
229 }
230 if (strlen(chap_r) != MD5_SIGNATURE_SIZE * 2) {
231 pr_err("Malformed CHAP_R\n");
232 goto out;
233 }
234 if (hex2bin(client_digest, chap_r, MD5_SIGNATURE_SIZE) < 0) {
235 pr_err("Malformed CHAP_R\n");
236 goto out;
237 }
238
239 pr_debug("[server] Got CHAP_R=%s\n", chap_r);
240
241 tfm = crypto_alloc_shash("md5", 0, 0);
242 if (IS_ERR(tfm)) {
243 tfm = NULL;
244 pr_err("Unable to allocate struct crypto_shash\n");
245 goto out;
246 }
247
248 desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(tfm), GFP_KERNEL);
249 if (!desc) {
250 pr_err("Unable to allocate struct shash_desc\n");
251 goto out;
252 }
253
254 desc->tfm = tfm;
255 desc->flags = 0;
256
257 ret = crypto_shash_init(desc);
258 if (ret < 0) {
259 pr_err("crypto_shash_init() failed\n");
260 goto out;
261 }
262
263 ret = crypto_shash_update(desc, &chap->id, 1);
264 if (ret < 0) {
265 pr_err("crypto_shash_update() failed for id\n");
266 goto out;
267 }
268
269 ret = crypto_shash_update(desc, (char *)&auth->password,
270 strlen(auth->password));
271 if (ret < 0) {
272 pr_err("crypto_shash_update() failed for password\n");
273 goto out;
274 }
275
276 ret = crypto_shash_finup(desc, chap->challenge,
277 CHAP_CHALLENGE_LENGTH, server_digest);
278 if (ret < 0) {
279 pr_err("crypto_shash_finup() failed for challenge\n");
280 goto out;
281 }
282
283 bin2hex(response, server_digest, MD5_SIGNATURE_SIZE);
284 pr_debug("[server] MD5 Server Digest: %s\n", response);
285
286 if (memcmp(server_digest, client_digest, MD5_SIGNATURE_SIZE) != 0) {
287 pr_debug("[server] MD5 Digests do not match!\n\n");
288 goto out;
289 } else
290 pr_debug("[server] MD5 Digests match, CHAP connection"
291 " successful.\n\n");
292
293
294
295
296 if (!auth->authenticate_target) {
297 auth_ret = 0;
298 goto out;
299 }
300
301
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)
309 ret = kstrtoul(&identifier[2], 0, &id);
310 else
311 ret = kstrtoul(identifier, 0, &id);
312
313 if (ret < 0) {
314 pr_err("kstrtoul() failed for CHAP identifier: %d\n", ret);
315 goto out;
316 }
317 if (id > 255) {
318 pr_err("chap identifier: %lu greater than 255\n", id);
319 goto out;
320 }
321
322
323
324 pr_debug("[server] Got CHAP_I=%lu\n", id);
325
326
327
328 if (extract_param(nr_in_ptr, "CHAP_C", CHAP_CHALLENGE_STR_LEN,
329 challenge, &type) < 0) {
330 pr_err("Could not find CHAP_C.\n");
331 goto out;
332 }
333
334 if (type != HEX) {
335 pr_err("Could not find CHAP_C.\n");
336 goto out;
337 }
338 challenge_len = DIV_ROUND_UP(strlen(challenge), 2);
339 if (!challenge_len) {
340 pr_err("Unable to convert incoming challenge\n");
341 goto out;
342 }
343 if (challenge_len > 1024) {
344 pr_err("CHAP_C exceeds maximum binary size of 1024 bytes\n");
345 goto out;
346 }
347 if (hex2bin(challenge_binhex, challenge, challenge_len) < 0) {
348 pr_err("Malformed CHAP_C\n");
349 goto out;
350 }
351 pr_debug("[server] Got CHAP_C=%s\n", challenge);
352
353
354
355
356
357 if (!memcmp(challenge_binhex, chap->challenge, CHAP_CHALLENGE_LENGTH)) {
358 pr_err("initiator CHAP_C matches target CHAP_C, failing"
359 " login attempt\n");
360 goto out;
361 }
362
363
364
365 ret = crypto_shash_init(desc);
366 if (ret < 0) {
367 pr_err("crypto_shash_init() failed\n");
368 goto out;
369 }
370
371
372 id_as_uchar = id;
373 ret = crypto_shash_update(desc, &id_as_uchar, 1);
374 if (ret < 0) {
375 pr_err("crypto_shash_update() failed for id\n");
376 goto out;
377 }
378
379 ret = crypto_shash_update(desc, auth->password_mutual,
380 strlen(auth->password_mutual));
381 if (ret < 0) {
382 pr_err("crypto_shash_update() failed for"
383 " password_mutual\n");
384 goto out;
385 }
386
387
388
389 ret = crypto_shash_finup(desc, challenge_binhex, challenge_len,
390 digest);
391 if (ret < 0) {
392 pr_err("crypto_shash_finup() failed for ma challenge\n");
393 goto out;
394 }
395
396
397
398
399 *nr_out_len = sprintf(nr_out_ptr, "CHAP_N=%s", auth->userid_mutual);
400 *nr_out_len += 1;
401 pr_debug("[server] Sending CHAP_N=%s\n", auth->userid_mutual);
402
403
404
405 bin2hex(response, digest, MD5_SIGNATURE_SIZE);
406 *nr_out_len += sprintf(nr_out_ptr + *nr_out_len, "CHAP_R=0x%s",
407 response);
408 *nr_out_len += 1;
409 pr_debug("[server] Sending CHAP_R=0x%s\n", response);
410 auth_ret = 0;
411out:
412 kzfree(desc);
413 if (tfm)
414 crypto_free_shash(tfm);
415 kfree(challenge);
416 kfree(challenge_binhex);
417 return auth_ret;
418}
419
420static int chap_got_response(
421 struct iscsi_conn *conn,
422 struct iscsi_node_auth *auth,
423 char *nr_in_ptr,
424 char *nr_out_ptr,
425 unsigned int *nr_out_len)
426{
427 struct iscsi_chap *chap = conn->auth_protocol;
428
429 switch (chap->digest_type) {
430 case CHAP_DIGEST_MD5:
431 if (chap_server_compute_md5(conn, auth, nr_in_ptr,
432 nr_out_ptr, nr_out_len) < 0)
433 return -1;
434 return 0;
435 default:
436 pr_err("Unknown CHAP digest type %d!\n",
437 chap->digest_type);
438 return -1;
439 }
440}
441
442u32 chap_main_loop(
443 struct iscsi_conn *conn,
444 struct iscsi_node_auth *auth,
445 char *in_text,
446 char *out_text,
447 int *in_len,
448 int *out_len)
449{
450 struct iscsi_chap *chap = conn->auth_protocol;
451
452 if (!chap) {
453 chap = chap_server_open(conn, auth, in_text, out_text, out_len);
454 if (!chap)
455 return 2;
456 chap->chap_state = CHAP_STAGE_SERVER_AIC;
457 return 0;
458 } else if (chap->chap_state == CHAP_STAGE_SERVER_AIC) {
459 convert_null_to_semi(in_text, *in_len);
460 if (chap_got_response(conn, auth, in_text, out_text,
461 out_len) < 0) {
462 chap_close(conn);
463 return 2;
464 }
465 if (auth->authenticate_target)
466 chap->chap_state = CHAP_STAGE_SERVER_NR;
467 else
468 *out_len = 0;
469 chap_close(conn);
470 return 1;
471 }
472
473 return 2;
474}
475
