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11#include <crypto/hash.h>
12#include <linux/kernel.h>
13#include <linux/string.h>
14#include <linux/err.h>
15#include <linux/random.h>
16#include <linux/scatterlist.h>
17#include <target/iscsi/iscsi_target_core.h>
18#include "iscsi_target_nego.h"
19#include "iscsi_target_auth.h"
20
21static int chap_gen_challenge(
22 struct iscsi_conn *conn,
23 int caller,
24 char *c_str,
25 unsigned int *c_len)
26{
27 int ret;
28 unsigned char challenge_asciihex[CHAP_CHALLENGE_LENGTH * 2 + 1];
29 struct iscsi_chap *chap = conn->auth_protocol;
30
31 memset(challenge_asciihex, 0, CHAP_CHALLENGE_LENGTH * 2 + 1);
32
33 ret = get_random_bytes_wait(chap->challenge, CHAP_CHALLENGE_LENGTH);
34 if (unlikely(ret))
35 return ret;
36 bin2hex(challenge_asciihex, chap->challenge,
37 CHAP_CHALLENGE_LENGTH);
38
39
40
41 *c_len += sprintf(c_str + *c_len, "CHAP_C=0x%s", challenge_asciihex);
42 *c_len += 1;
43
44 pr_debug("[%s] Sending CHAP_C=0x%s\n\n", (caller) ? "server" : "client",
45 challenge_asciihex);
46 return 0;
47}
48
49static int chap_check_algorithm(const char *a_str)
50{
51 char *tmp, *orig, *token;
52
53 tmp = kstrdup(a_str, GFP_KERNEL);
54 if (!tmp) {
55 pr_err("Memory allocation failed for CHAP_A temporary buffer\n");
56 return CHAP_DIGEST_UNKNOWN;
57 }
58 orig = tmp;
59
60 token = strsep(&tmp, "=");
61 if (!token)
62 goto out;
63
64 if (strcmp(token, "CHAP_A")) {
65 pr_err("Unable to locate CHAP_A key\n");
66 goto out;
67 }
68 while (token) {
69 token = strsep(&tmp, ",");
70 if (!token)
71 goto out;
72
73 if (!strncmp(token, "5", 1)) {
74 pr_debug("Selected MD5 Algorithm\n");
75 kfree(orig);
76 return CHAP_DIGEST_MD5;
77 }
78 }
79out:
80 kfree(orig);
81 return CHAP_DIGEST_UNKNOWN;
82}
83
84static void chap_close(struct iscsi_conn *conn)
85{
86 kfree(conn->auth_protocol);
87 conn->auth_protocol = NULL;
88}
89
90static struct iscsi_chap *chap_server_open(
91 struct iscsi_conn *conn,
92 struct iscsi_node_auth *auth,
93 const char *a_str,
94 char *aic_str,
95 unsigned int *aic_len)
96{
97 int ret;
98 struct iscsi_chap *chap;
99
100 if (!(auth->naf_flags & NAF_USERID_SET) ||
101 !(auth->naf_flags & NAF_PASSWORD_SET)) {
102 pr_err("CHAP user or password not set for"
103 " Initiator ACL\n");
104 return NULL;
105 }
106
107 conn->auth_protocol = kzalloc(sizeof(struct iscsi_chap), GFP_KERNEL);
108 if (!conn->auth_protocol)
109 return NULL;
110
111 chap = conn->auth_protocol;
112 ret = chap_check_algorithm(a_str);
113 switch (ret) {
114 case CHAP_DIGEST_MD5:
115 pr_debug("[server] Got CHAP_A=5\n");
116
117
118
119 *aic_len = sprintf(aic_str, "CHAP_A=5");
120 *aic_len += 1;
121 chap->digest_type = CHAP_DIGEST_MD5;
122 pr_debug("[server] Sending CHAP_A=%d\n", chap->digest_type);
123 break;
124 case CHAP_DIGEST_UNKNOWN:
125 default:
126 pr_err("Unsupported CHAP_A value\n");
127 chap_close(conn);
128 return NULL;
129 }
130
131
132
133
134 chap->id = conn->tpg->tpg_chap_id++;
135 *aic_len += sprintf(aic_str + *aic_len, "CHAP_I=%d", chap->id);
136 *aic_len += 1;
137 pr_debug("[server] Sending CHAP_I=%d\n", chap->id);
138
139
140
141 if (chap_gen_challenge(conn, 1, aic_str, aic_len) < 0) {
142 chap_close(conn);
143 return NULL;
144 }
145
146 return chap;
147}
148
149static int chap_server_compute_md5(
150 struct iscsi_conn *conn,
151 struct iscsi_node_auth *auth,
152 char *nr_in_ptr,
153 char *nr_out_ptr,
154 unsigned int *nr_out_len)
155{
156 unsigned long id;
157 unsigned char id_as_uchar;
158 unsigned char digest[MD5_SIGNATURE_SIZE];
159 unsigned char type, response[MD5_SIGNATURE_SIZE * 2 + 2];
160 unsigned char identifier[10], *challenge = NULL;
161 unsigned char *challenge_binhex = NULL;
162 unsigned char client_digest[MD5_SIGNATURE_SIZE];
163 unsigned char server_digest[MD5_SIGNATURE_SIZE];
164 unsigned char chap_n[MAX_CHAP_N_SIZE], chap_r[MAX_RESPONSE_LENGTH];
165 size_t compare_len;
166 struct iscsi_chap *chap = conn->auth_protocol;
167 struct crypto_shash *tfm = NULL;
168 struct shash_desc *desc = NULL;
169 int auth_ret = -1, ret, challenge_len;
170
171 memset(identifier, 0, 10);
172 memset(chap_n, 0, MAX_CHAP_N_SIZE);
173 memset(chap_r, 0, MAX_RESPONSE_LENGTH);
174 memset(digest, 0, MD5_SIGNATURE_SIZE);
175 memset(response, 0, MD5_SIGNATURE_SIZE * 2 + 2);
176 memset(client_digest, 0, MD5_SIGNATURE_SIZE);
177 memset(server_digest, 0, MD5_SIGNATURE_SIZE);
178
179 challenge = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL);
180 if (!challenge) {
181 pr_err("Unable to allocate challenge buffer\n");
182 goto out;
183 }
184
185 challenge_binhex = kzalloc(CHAP_CHALLENGE_STR_LEN, GFP_KERNEL);
186 if (!challenge_binhex) {
187 pr_err("Unable to allocate challenge_binhex buffer\n");
188 goto out;
189 }
190
191
192
193 if (extract_param(nr_in_ptr, "CHAP_N", MAX_CHAP_N_SIZE, chap_n,
194 &type) < 0) {
195 pr_err("Could not find CHAP_N.\n");
196 goto out;
197 }
198 if (type == HEX) {
199 pr_err("Could not find CHAP_N.\n");
200 goto out;
201 }
202
203
204 compare_len = strlen(auth->userid) + 1;
205 if (strncmp(chap_n, auth->userid, compare_len) != 0) {
206 pr_err("CHAP_N values do not match!\n");
207 goto out;
208 }
209 pr_debug("[server] Got CHAP_N=%s\n", chap_n);
210
211
212
213 if (extract_param(nr_in_ptr, "CHAP_R", MAX_RESPONSE_LENGTH, chap_r,
214 &type) < 0) {
215 pr_err("Could not find CHAP_R.\n");
216 goto out;
217 }
218 if (type != HEX) {
219 pr_err("Could not find CHAP_R.\n");
220 goto out;
221 }
222 if (strlen(chap_r) != MD5_SIGNATURE_SIZE * 2) {
223 pr_err("Malformed CHAP_R\n");
224 goto out;
225 }
226 if (hex2bin(client_digest, chap_r, MD5_SIGNATURE_SIZE) < 0) {
227 pr_err("Malformed CHAP_R\n");
228 goto out;
229 }
230
231 pr_debug("[server] Got CHAP_R=%s\n", chap_r);
232
233 tfm = crypto_alloc_shash("md5", 0, 0);
234 if (IS_ERR(tfm)) {
235 tfm = NULL;
236 pr_err("Unable to allocate struct crypto_shash\n");
237 goto out;
238 }
239
240 desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(tfm), GFP_KERNEL);
241 if (!desc) {
242 pr_err("Unable to allocate struct shash_desc\n");
243 goto out;
244 }
245
246 desc->tfm = tfm;
247
248 ret = crypto_shash_init(desc);
249 if (ret < 0) {
250 pr_err("crypto_shash_init() failed\n");
251 goto out;
252 }
253
254 ret = crypto_shash_update(desc, &chap->id, 1);
255 if (ret < 0) {
256 pr_err("crypto_shash_update() failed for id\n");
257 goto out;
258 }
259
260 ret = crypto_shash_update(desc, (char *)&auth->password,
261 strlen(auth->password));
262 if (ret < 0) {
263 pr_err("crypto_shash_update() failed for password\n");
264 goto out;
265 }
266
267 ret = crypto_shash_finup(desc, chap->challenge,
268 CHAP_CHALLENGE_LENGTH, server_digest);
269 if (ret < 0) {
270 pr_err("crypto_shash_finup() failed for challenge\n");
271 goto out;
272 }
273
274 bin2hex(response, server_digest, MD5_SIGNATURE_SIZE);
275 pr_debug("[server] MD5 Server Digest: %s\n", response);
276
277 if (memcmp(server_digest, client_digest, MD5_SIGNATURE_SIZE) != 0) {
278 pr_debug("[server] MD5 Digests do not match!\n\n");
279 goto out;
280 } else
281 pr_debug("[server] MD5 Digests match, CHAP connection"
282 " successful.\n\n");
283
284
285
286
287 if (!auth->authenticate_target) {
288 auth_ret = 0;
289 goto out;
290 }
291
292
293
294 if (extract_param(nr_in_ptr, "CHAP_I", 10, identifier, &type) < 0) {
295 pr_err("Could not find CHAP_I.\n");
296 goto out;
297 }
298
299 if (type == HEX)
300 ret = kstrtoul(&identifier[2], 0, &id);
301 else
302 ret = kstrtoul(identifier, 0, &id);
303
304 if (ret < 0) {
305 pr_err("kstrtoul() failed for CHAP identifier: %d\n", ret);
306 goto out;
307 }
308 if (id > 255) {
309 pr_err("chap identifier: %lu greater than 255\n", id);
310 goto out;
311 }
312
313
314
315 pr_debug("[server] Got CHAP_I=%lu\n", id);
316
317
318
319 if (extract_param(nr_in_ptr, "CHAP_C", CHAP_CHALLENGE_STR_LEN,
320 challenge, &type) < 0) {
321 pr_err("Could not find CHAP_C.\n");
322 goto out;
323 }
324
325 if (type != HEX) {
326 pr_err("Could not find CHAP_C.\n");
327 goto out;
328 }
329 challenge_len = DIV_ROUND_UP(strlen(challenge), 2);
330 if (!challenge_len) {
331 pr_err("Unable to convert incoming challenge\n");
332 goto out;
333 }
334 if (challenge_len > 1024) {
335 pr_err("CHAP_C exceeds maximum binary size of 1024 bytes\n");
336 goto out;
337 }
338 if (hex2bin(challenge_binhex, challenge, challenge_len) < 0) {
339 pr_err("Malformed CHAP_C\n");
340 goto out;
341 }
342 pr_debug("[server] Got CHAP_C=%s\n", challenge);
343
344
345
346
347
348 if (!memcmp(challenge_binhex, chap->challenge, CHAP_CHALLENGE_LENGTH)) {
349 pr_err("initiator CHAP_C matches target CHAP_C, failing"
350 " login attempt\n");
351 goto out;
352 }
353
354
355
356 ret = crypto_shash_init(desc);
357 if (ret < 0) {
358 pr_err("crypto_shash_init() failed\n");
359 goto out;
360 }
361
362
363 id_as_uchar = id;
364 ret = crypto_shash_update(desc, &id_as_uchar, 1);
365 if (ret < 0) {
366 pr_err("crypto_shash_update() failed for id\n");
367 goto out;
368 }
369
370 ret = crypto_shash_update(desc, auth->password_mutual,
371 strlen(auth->password_mutual));
372 if (ret < 0) {
373 pr_err("crypto_shash_update() failed for"
374 " password_mutual\n");
375 goto out;
376 }
377
378
379
380 ret = crypto_shash_finup(desc, challenge_binhex, challenge_len,
381 digest);
382 if (ret < 0) {
383 pr_err("crypto_shash_finup() failed for ma challenge\n");
384 goto out;
385 }
386
387
388
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
395
396 bin2hex(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;
402out:
403 kzfree(desc);
404 if (tfm)
405 crypto_free_shash(tfm);
406 kfree(challenge);
407 kfree(challenge_binhex);
408 return auth_ret;
409}
410
411static int chap_got_response(
412 struct iscsi_conn *conn,
413 struct iscsi_node_auth *auth,
414 char *nr_in_ptr,
415 char *nr_out_ptr,
416 unsigned int *nr_out_len)
417{
418 struct iscsi_chap *chap = conn->auth_protocol;
419
420 switch (chap->digest_type) {
421 case CHAP_DIGEST_MD5:
422 if (chap_server_compute_md5(conn, auth, nr_in_ptr,
423 nr_out_ptr, nr_out_len) < 0)
424 return -1;
425 return 0;
426 default:
427 pr_err("Unknown CHAP digest type %d!\n",
428 chap->digest_type);
429 return -1;
430 }
431}
432
433u32 chap_main_loop(
434 struct iscsi_conn *conn,
435 struct iscsi_node_auth *auth,
436 char *in_text,
437 char *out_text,
438 int *in_len,
439 int *out_len)
440{
441 struct iscsi_chap *chap = conn->auth_protocol;
442
443 if (!chap) {
444 chap = chap_server_open(conn, auth, in_text, out_text, out_len);
445 if (!chap)
446 return 2;
447 chap->chap_state = CHAP_STAGE_SERVER_AIC;
448 return 0;
449 } else if (chap->chap_state == CHAP_STAGE_SERVER_AIC) {
450 convert_null_to_semi(in_text, *in_len);
451 if (chap_got_response(conn, auth, in_text, out_text,
452 out_len) < 0) {
453 chap_close(conn);
454 return 2;
455 }
456 if (auth->authenticate_target)
457 chap->chap_state = CHAP_STAGE_SERVER_NR;
458 else
459 *out_len = 0;
460 chap_close(conn);
461 return 1;
462 }
463
464 return 2;
465}
466
