1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* Kerberos-based RxRPC security
3 *
4 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9
10 #include <crypto/skcipher.h>
11 #include <linux/module.h>
12 #include <linux/net.h>
13 #include <linux/skbuff.h>
14 #include <linux/udp.h>
15 #include <linux/scatterlist.h>
16 #include <linux/ctype.h>
17 #include <linux/slab.h>
18 #include <linux/key-type.h>
19 #include <net/sock.h>
20 #include <net/af_rxrpc.h>
21 #include <keys/rxrpc-type.h>
22 #include "ar-internal.h"
23
24 #define RXKAD_VERSION 2
25 #define MAXKRB5TICKETLEN 1024
26 #define RXKAD_TKT_TYPE_KERBEROS_V5 256
27 #define ANAME_SZ 40 /* size of authentication name */
28 #define INST_SZ 40 /* size of principal's instance */
29 #define REALM_SZ 40 /* size of principal's auth domain */
30 #define SNAME_SZ 40 /* size of service name */
31 #define RXKAD_ALIGN 8
32
33 struct rxkad_level1_hdr {
34 __be32 data_size; /* true data size (excluding padding) */
35 };
36
37 struct rxkad_level2_hdr {
38 __be32 data_size; /* true data size (excluding padding) */
39 __be32 checksum; /* decrypted data checksum */
40 };
41
42 static int rxkad_prime_packet_security(struct rxrpc_connection *conn,
43 struct crypto_sync_skcipher *ci);
44
45 /*
46 * this holds a pinned cipher so that keventd doesn't get called by the cipher
47 * alloc routine, but since we have it to hand, we use it to decrypt RESPONSE
48 * packets
49 */
50 static struct crypto_sync_skcipher *rxkad_ci;
51 static struct skcipher_request *rxkad_ci_req;
52 static DEFINE_MUTEX(rxkad_ci_mutex);
53
54 /*
55 * Parse the information from a server key
56 *
57 * The data should be the 8-byte secret key.
58 */
rxkad_preparse_server_key(struct key_preparsed_payload * prep)59 static int rxkad_preparse_server_key(struct key_preparsed_payload *prep)
60 {
61 struct crypto_skcipher *ci;
62
63 if (prep->datalen != 8)
64 return -EINVAL;
65
66 memcpy(&prep->payload.data[2], prep->data, 8);
67
68 ci = crypto_alloc_skcipher("pcbc(des)", 0, CRYPTO_ALG_ASYNC);
69 if (IS_ERR(ci)) {
70 _leave(" = %ld", PTR_ERR(ci));
71 return PTR_ERR(ci);
72 }
73
74 if (crypto_skcipher_setkey(ci, prep->data, 8) < 0)
75 BUG();
76
77 prep->payload.data[0] = ci;
78 _leave(" = 0");
79 return 0;
80 }
81
rxkad_free_preparse_server_key(struct key_preparsed_payload * prep)82 static void rxkad_free_preparse_server_key(struct key_preparsed_payload *prep)
83 {
84
85 if (prep->payload.data[0])
86 crypto_free_skcipher(prep->payload.data[0]);
87 }
88
rxkad_destroy_server_key(struct key * key)89 static void rxkad_destroy_server_key(struct key *key)
90 {
91 if (key->payload.data[0]) {
92 crypto_free_skcipher(key->payload.data[0]);
93 key->payload.data[0] = NULL;
94 }
95 }
96
97 /*
98 * initialise connection security
99 */
rxkad_init_connection_security(struct rxrpc_connection * conn,struct rxrpc_key_token * token)100 static int rxkad_init_connection_security(struct rxrpc_connection *conn,
101 struct rxrpc_key_token *token)
102 {
103 struct crypto_sync_skcipher *ci;
104 int ret;
105
106 _enter("{%d},{%x}", conn->debug_id, key_serial(conn->key));
107
108 conn->security_ix = token->security_index;
109
110 ci = crypto_alloc_sync_skcipher("pcbc(fcrypt)", 0, 0);
111 if (IS_ERR(ci)) {
112 _debug("no cipher");
113 ret = PTR_ERR(ci);
114 goto error;
115 }
116
117 if (crypto_sync_skcipher_setkey(ci, token->kad->session_key,
118 sizeof(token->kad->session_key)) < 0)
119 BUG();
120
121 switch (conn->security_level) {
122 case RXRPC_SECURITY_PLAIN:
123 case RXRPC_SECURITY_AUTH:
124 case RXRPC_SECURITY_ENCRYPT:
125 break;
126 default:
127 ret = -EKEYREJECTED;
128 goto error;
129 }
130
131 ret = rxkad_prime_packet_security(conn, ci);
132 if (ret < 0)
133 goto error_ci;
134
135 conn->rxkad.cipher = ci;
136 return 0;
137
138 error_ci:
139 crypto_free_sync_skcipher(ci);
140 error:
141 _leave(" = %d", ret);
142 return ret;
143 }
144
145 /*
146 * Work out how much data we can put in a packet.
147 */
rxkad_how_much_data(struct rxrpc_call * call,size_t remain,size_t * _buf_size,size_t * _data_size,size_t * _offset)148 static int rxkad_how_much_data(struct rxrpc_call *call, size_t remain,
149 size_t *_buf_size, size_t *_data_size, size_t *_offset)
150 {
151 size_t shdr, buf_size, chunk;
152
153 switch (call->conn->security_level) {
154 default:
155 buf_size = chunk = min_t(size_t, remain, RXRPC_JUMBO_DATALEN);
156 shdr = 0;
157 goto out;
158 case RXRPC_SECURITY_AUTH:
159 shdr = sizeof(struct rxkad_level1_hdr);
160 break;
161 case RXRPC_SECURITY_ENCRYPT:
162 shdr = sizeof(struct rxkad_level2_hdr);
163 break;
164 }
165
166 buf_size = round_down(RXRPC_JUMBO_DATALEN, RXKAD_ALIGN);
167
168 chunk = buf_size - shdr;
169 if (remain < chunk)
170 buf_size = round_up(shdr + remain, RXKAD_ALIGN);
171
172 out:
173 *_buf_size = buf_size;
174 *_data_size = chunk;
175 *_offset = shdr;
176 return 0;
177 }
178
179 /*
180 * prime the encryption state with the invariant parts of a connection's
181 * description
182 */
rxkad_prime_packet_security(struct rxrpc_connection * conn,struct crypto_sync_skcipher * ci)183 static int rxkad_prime_packet_security(struct rxrpc_connection *conn,
184 struct crypto_sync_skcipher *ci)
185 {
186 struct skcipher_request *req;
187 struct rxrpc_key_token *token;
188 struct scatterlist sg;
189 struct rxrpc_crypt iv;
190 __be32 *tmpbuf;
191 size_t tmpsize = 4 * sizeof(__be32);
192
193 _enter("");
194
195 if (!conn->key)
196 return 0;
197
198 tmpbuf = kmalloc(tmpsize, GFP_KERNEL);
199 if (!tmpbuf)
200 return -ENOMEM;
201
202 req = skcipher_request_alloc(&ci->base, GFP_NOFS);
203 if (!req) {
204 kfree(tmpbuf);
205 return -ENOMEM;
206 }
207
208 token = conn->key->payload.data[0];
209 memcpy(&iv, token->kad->session_key, sizeof(iv));
210
211 tmpbuf[0] = htonl(conn->proto.epoch);
212 tmpbuf[1] = htonl(conn->proto.cid);
213 tmpbuf[2] = 0;
214 tmpbuf[3] = htonl(conn->security_ix);
215
216 sg_init_one(&sg, tmpbuf, tmpsize);
217 skcipher_request_set_sync_tfm(req, ci);
218 skcipher_request_set_callback(req, 0, NULL, NULL);
219 skcipher_request_set_crypt(req, &sg, &sg, tmpsize, iv.x);
220 crypto_skcipher_encrypt(req);
221 skcipher_request_free(req);
222
223 memcpy(&conn->rxkad.csum_iv, tmpbuf + 2, sizeof(conn->rxkad.csum_iv));
224 kfree(tmpbuf);
225 _leave(" = 0");
226 return 0;
227 }
228
229 /*
230 * Allocate and prepare the crypto request on a call. For any particular call,
231 * this is called serially for the packets, so no lock should be necessary.
232 */
rxkad_get_call_crypto(struct rxrpc_call * call)233 static struct skcipher_request *rxkad_get_call_crypto(struct rxrpc_call *call)
234 {
235 struct crypto_skcipher *tfm = &call->conn->rxkad.cipher->base;
236
237 return skcipher_request_alloc(tfm, GFP_NOFS);
238 }
239
240 /*
241 * Clean up the crypto on a call.
242 */
rxkad_free_call_crypto(struct rxrpc_call * call)243 static void rxkad_free_call_crypto(struct rxrpc_call *call)
244 {
245 }
246
247 /*
248 * partially encrypt a packet (level 1 security)
249 */
rxkad_secure_packet_auth(const struct rxrpc_call * call,struct rxrpc_txbuf * txb,struct skcipher_request * req)250 static int rxkad_secure_packet_auth(const struct rxrpc_call *call,
251 struct rxrpc_txbuf *txb,
252 struct skcipher_request *req)
253 {
254 struct rxkad_level1_hdr *hdr = (void *)txb->data;
255 struct rxrpc_crypt iv;
256 struct scatterlist sg;
257 size_t pad;
258 u16 check;
259
260 _enter("");
261
262 check = txb->seq ^ call->call_id;
263 hdr->data_size = htonl((u32)check << 16 | txb->len);
264
265 txb->len += sizeof(struct rxkad_level1_hdr);
266 pad = txb->len;
267 pad = RXKAD_ALIGN - pad;
268 pad &= RXKAD_ALIGN - 1;
269 if (pad) {
270 memset(txb->data + txb->offset, 0, pad);
271 txb->len += pad;
272 }
273
274 /* start the encryption afresh */
275 memset(&iv, 0, sizeof(iv));
276
277 sg_init_one(&sg, txb->data, 8);
278 skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher);
279 skcipher_request_set_callback(req, 0, NULL, NULL);
280 skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x);
281 crypto_skcipher_encrypt(req);
282 skcipher_request_zero(req);
283
284 _leave(" = 0");
285 return 0;
286 }
287
288 /*
289 * wholly encrypt a packet (level 2 security)
290 */
rxkad_secure_packet_encrypt(const struct rxrpc_call * call,struct rxrpc_txbuf * txb,struct skcipher_request * req)291 static int rxkad_secure_packet_encrypt(const struct rxrpc_call *call,
292 struct rxrpc_txbuf *txb,
293 struct skcipher_request *req)
294 {
295 const struct rxrpc_key_token *token;
296 struct rxkad_level2_hdr *rxkhdr = (void *)txb->data;
297 struct rxrpc_crypt iv;
298 struct scatterlist sg;
299 size_t pad;
300 u16 check;
301 int ret;
302
303 _enter("");
304
305 check = txb->seq ^ call->call_id;
306
307 rxkhdr->data_size = htonl(txb->len | (u32)check << 16);
308 rxkhdr->checksum = 0;
309
310 txb->len += sizeof(struct rxkad_level2_hdr);
311 pad = txb->len;
312 pad = RXKAD_ALIGN - pad;
313 pad &= RXKAD_ALIGN - 1;
314 if (pad) {
315 memset(txb->data + txb->offset, 0, pad);
316 txb->len += pad;
317 }
318
319 /* encrypt from the session key */
320 token = call->conn->key->payload.data[0];
321 memcpy(&iv, token->kad->session_key, sizeof(iv));
322
323 sg_init_one(&sg, txb->data, txb->len);
324 skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher);
325 skcipher_request_set_callback(req, 0, NULL, NULL);
326 skcipher_request_set_crypt(req, &sg, &sg, txb->len, iv.x);
327 ret = crypto_skcipher_encrypt(req);
328 skcipher_request_zero(req);
329 return ret;
330 }
331
332 /*
333 * checksum an RxRPC packet header
334 */
rxkad_secure_packet(struct rxrpc_call * call,struct rxrpc_txbuf * txb)335 static int rxkad_secure_packet(struct rxrpc_call *call, struct rxrpc_txbuf *txb)
336 {
337 struct skcipher_request *req;
338 struct rxrpc_crypt iv;
339 struct scatterlist sg;
340 union {
341 __be32 buf[2];
342 } crypto __aligned(8);
343 u32 x, y;
344 int ret;
345
346 _enter("{%d{%x}},{#%u},%u,",
347 call->debug_id, key_serial(call->conn->key),
348 txb->seq, txb->len);
349
350 if (!call->conn->rxkad.cipher)
351 return 0;
352
353 ret = key_validate(call->conn->key);
354 if (ret < 0)
355 return ret;
356
357 req = rxkad_get_call_crypto(call);
358 if (!req)
359 return -ENOMEM;
360
361 /* continue encrypting from where we left off */
362 memcpy(&iv, call->conn->rxkad.csum_iv.x, sizeof(iv));
363
364 /* calculate the security checksum */
365 x = (call->cid & RXRPC_CHANNELMASK) << (32 - RXRPC_CIDSHIFT);
366 x |= txb->seq & 0x3fffffff;
367 crypto.buf[0] = htonl(call->call_id);
368 crypto.buf[1] = htonl(x);
369
370 sg_init_one(&sg, crypto.buf, 8);
371 skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher);
372 skcipher_request_set_callback(req, 0, NULL, NULL);
373 skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x);
374 crypto_skcipher_encrypt(req);
375 skcipher_request_zero(req);
376
377 y = ntohl(crypto.buf[1]);
378 y = (y >> 16) & 0xffff;
379 if (y == 0)
380 y = 1; /* zero checksums are not permitted */
381 txb->wire.cksum = htons(y);
382
383 switch (call->conn->security_level) {
384 case RXRPC_SECURITY_PLAIN:
385 ret = 0;
386 break;
387 case RXRPC_SECURITY_AUTH:
388 ret = rxkad_secure_packet_auth(call, txb, req);
389 break;
390 case RXRPC_SECURITY_ENCRYPT:
391 ret = rxkad_secure_packet_encrypt(call, txb, req);
392 break;
393 default:
394 ret = -EPERM;
395 break;
396 }
397
398 skcipher_request_free(req);
399 _leave(" = %d [set %x]", ret, y);
400 return ret;
401 }
402
403 /*
404 * decrypt partial encryption on a packet (level 1 security)
405 */
rxkad_verify_packet_1(struct rxrpc_call * call,struct sk_buff * skb,rxrpc_seq_t seq,struct skcipher_request * req)406 static int rxkad_verify_packet_1(struct rxrpc_call *call, struct sk_buff *skb,
407 rxrpc_seq_t seq,
408 struct skcipher_request *req)
409 {
410 struct rxkad_level1_hdr sechdr;
411 struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
412 struct rxrpc_crypt iv;
413 struct scatterlist sg[16];
414 u32 data_size, buf;
415 u16 check;
416 int ret;
417
418 _enter("");
419
420 if (sp->len < 8)
421 return rxrpc_abort_eproto(call, skb, RXKADSEALEDINCON,
422 rxkad_abort_1_short_header);
423
424 /* Decrypt the skbuff in-place. TODO: We really want to decrypt
425 * directly into the target buffer.
426 */
427 sg_init_table(sg, ARRAY_SIZE(sg));
428 ret = skb_to_sgvec(skb, sg, sp->offset, 8);
429 if (unlikely(ret < 0))
430 return ret;
431
432 /* start the decryption afresh */
433 memset(&iv, 0, sizeof(iv));
434
435 skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher);
436 skcipher_request_set_callback(req, 0, NULL, NULL);
437 skcipher_request_set_crypt(req, sg, sg, 8, iv.x);
438 crypto_skcipher_decrypt(req);
439 skcipher_request_zero(req);
440
441 /* Extract the decrypted packet length */
442 if (skb_copy_bits(skb, sp->offset, &sechdr, sizeof(sechdr)) < 0)
443 return rxrpc_abort_eproto(call, skb, RXKADDATALEN,
444 rxkad_abort_1_short_encdata);
445 sp->offset += sizeof(sechdr);
446 sp->len -= sizeof(sechdr);
447
448 buf = ntohl(sechdr.data_size);
449 data_size = buf & 0xffff;
450
451 check = buf >> 16;
452 check ^= seq ^ call->call_id;
453 check &= 0xffff;
454 if (check != 0)
455 return rxrpc_abort_eproto(call, skb, RXKADSEALEDINCON,
456 rxkad_abort_1_short_check);
457 if (data_size > sp->len)
458 return rxrpc_abort_eproto(call, skb, RXKADDATALEN,
459 rxkad_abort_1_short_data);
460 sp->len = data_size;
461
462 _leave(" = 0 [dlen=%x]", data_size);
463 return 0;
464 }
465
466 /*
467 * wholly decrypt a packet (level 2 security)
468 */
rxkad_verify_packet_2(struct rxrpc_call * call,struct sk_buff * skb,rxrpc_seq_t seq,struct skcipher_request * req)469 static int rxkad_verify_packet_2(struct rxrpc_call *call, struct sk_buff *skb,
470 rxrpc_seq_t seq,
471 struct skcipher_request *req)
472 {
473 const struct rxrpc_key_token *token;
474 struct rxkad_level2_hdr sechdr;
475 struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
476 struct rxrpc_crypt iv;
477 struct scatterlist _sg[4], *sg;
478 u32 data_size, buf;
479 u16 check;
480 int nsg, ret;
481
482 _enter(",{%d}", sp->len);
483
484 if (sp->len < 8)
485 return rxrpc_abort_eproto(call, skb, RXKADSEALEDINCON,
486 rxkad_abort_2_short_header);
487
488 /* Decrypt the skbuff in-place. TODO: We really want to decrypt
489 * directly into the target buffer.
490 */
491 sg = _sg;
492 nsg = skb_shinfo(skb)->nr_frags + 1;
493 if (nsg <= 4) {
494 nsg = 4;
495 } else {
496 sg = kmalloc_array(nsg, sizeof(*sg), GFP_NOIO);
497 if (!sg)
498 return -ENOMEM;
499 }
500
501 sg_init_table(sg, nsg);
502 ret = skb_to_sgvec(skb, sg, sp->offset, sp->len);
503 if (unlikely(ret < 0)) {
504 if (sg != _sg)
505 kfree(sg);
506 return ret;
507 }
508
509 /* decrypt from the session key */
510 token = call->conn->key->payload.data[0];
511 memcpy(&iv, token->kad->session_key, sizeof(iv));
512
513 skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher);
514 skcipher_request_set_callback(req, 0, NULL, NULL);
515 skcipher_request_set_crypt(req, sg, sg, sp->len, iv.x);
516 crypto_skcipher_decrypt(req);
517 skcipher_request_zero(req);
518 if (sg != _sg)
519 kfree(sg);
520
521 /* Extract the decrypted packet length */
522 if (skb_copy_bits(skb, sp->offset, &sechdr, sizeof(sechdr)) < 0)
523 return rxrpc_abort_eproto(call, skb, RXKADDATALEN,
524 rxkad_abort_2_short_len);
525 sp->offset += sizeof(sechdr);
526 sp->len -= sizeof(sechdr);
527
528 buf = ntohl(sechdr.data_size);
529 data_size = buf & 0xffff;
530
531 check = buf >> 16;
532 check ^= seq ^ call->call_id;
533 check &= 0xffff;
534 if (check != 0)
535 return rxrpc_abort_eproto(call, skb, RXKADSEALEDINCON,
536 rxkad_abort_2_short_check);
537
538 if (data_size > sp->len)
539 return rxrpc_abort_eproto(call, skb, RXKADDATALEN,
540 rxkad_abort_2_short_data);
541
542 sp->len = data_size;
543 _leave(" = 0 [dlen=%x]", data_size);
544 return 0;
545 }
546
547 /*
548 * Verify the security on a received packet and the subpackets therein.
549 */
rxkad_verify_packet(struct rxrpc_call * call,struct sk_buff * skb)550 static int rxkad_verify_packet(struct rxrpc_call *call, struct sk_buff *skb)
551 {
552 struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
553 struct skcipher_request *req;
554 struct rxrpc_crypt iv;
555 struct scatterlist sg;
556 union {
557 __be32 buf[2];
558 } crypto __aligned(8);
559 rxrpc_seq_t seq = sp->hdr.seq;
560 int ret;
561 u16 cksum;
562 u32 x, y;
563
564 _enter("{%d{%x}},{#%u}",
565 call->debug_id, key_serial(call->conn->key), seq);
566
567 if (!call->conn->rxkad.cipher)
568 return 0;
569
570 req = rxkad_get_call_crypto(call);
571 if (!req)
572 return -ENOMEM;
573
574 /* continue encrypting from where we left off */
575 memcpy(&iv, call->conn->rxkad.csum_iv.x, sizeof(iv));
576
577 /* validate the security checksum */
578 x = (call->cid & RXRPC_CHANNELMASK) << (32 - RXRPC_CIDSHIFT);
579 x |= seq & 0x3fffffff;
580 crypto.buf[0] = htonl(call->call_id);
581 crypto.buf[1] = htonl(x);
582
583 sg_init_one(&sg, crypto.buf, 8);
584 skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher);
585 skcipher_request_set_callback(req, 0, NULL, NULL);
586 skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x);
587 crypto_skcipher_encrypt(req);
588 skcipher_request_zero(req);
589
590 y = ntohl(crypto.buf[1]);
591 cksum = (y >> 16) & 0xffff;
592 if (cksum == 0)
593 cksum = 1; /* zero checksums are not permitted */
594
595 if (cksum != sp->hdr.cksum) {
596 ret = rxrpc_abort_eproto(call, skb, RXKADSEALEDINCON,
597 rxkad_abort_bad_checksum);
598 goto out;
599 }
600
601 switch (call->conn->security_level) {
602 case RXRPC_SECURITY_PLAIN:
603 ret = 0;
604 break;
605 case RXRPC_SECURITY_AUTH:
606 ret = rxkad_verify_packet_1(call, skb, seq, req);
607 break;
608 case RXRPC_SECURITY_ENCRYPT:
609 ret = rxkad_verify_packet_2(call, skb, seq, req);
610 break;
611 default:
612 ret = -ENOANO;
613 break;
614 }
615
616 out:
617 skcipher_request_free(req);
618 return ret;
619 }
620
621 /*
622 * issue a challenge
623 */
rxkad_issue_challenge(struct rxrpc_connection * conn)624 static int rxkad_issue_challenge(struct rxrpc_connection *conn)
625 {
626 struct rxkad_challenge challenge;
627 struct rxrpc_wire_header whdr;
628 struct msghdr msg;
629 struct kvec iov[2];
630 size_t len;
631 u32 serial;
632 int ret;
633
634 _enter("{%d}", conn->debug_id);
635
636 get_random_bytes(&conn->rxkad.nonce, sizeof(conn->rxkad.nonce));
637
638 challenge.version = htonl(2);
639 challenge.nonce = htonl(conn->rxkad.nonce);
640 challenge.min_level = htonl(0);
641 challenge.__padding = 0;
642
643 msg.msg_name = &conn->peer->srx.transport;
644 msg.msg_namelen = conn->peer->srx.transport_len;
645 msg.msg_control = NULL;
646 msg.msg_controllen = 0;
647 msg.msg_flags = 0;
648
649 whdr.epoch = htonl(conn->proto.epoch);
650 whdr.cid = htonl(conn->proto.cid);
651 whdr.callNumber = 0;
652 whdr.seq = 0;
653 whdr.type = RXRPC_PACKET_TYPE_CHALLENGE;
654 whdr.flags = conn->out_clientflag;
655 whdr.userStatus = 0;
656 whdr.securityIndex = conn->security_ix;
657 whdr._rsvd = 0;
658 whdr.serviceId = htons(conn->service_id);
659
660 iov[0].iov_base = &whdr;
661 iov[0].iov_len = sizeof(whdr);
662 iov[1].iov_base = &challenge;
663 iov[1].iov_len = sizeof(challenge);
664
665 len = iov[0].iov_len + iov[1].iov_len;
666
667 serial = rxrpc_get_next_serial(conn);
668 whdr.serial = htonl(serial);
669
670 ret = kernel_sendmsg(conn->local->socket, &msg, iov, 2, len);
671 if (ret < 0) {
672 trace_rxrpc_tx_fail(conn->debug_id, serial, ret,
673 rxrpc_tx_point_rxkad_challenge);
674 return -EAGAIN;
675 }
676
677 conn->peer->last_tx_at = ktime_get_seconds();
678 trace_rxrpc_tx_packet(conn->debug_id, &whdr,
679 rxrpc_tx_point_rxkad_challenge);
680 _leave(" = 0");
681 return 0;
682 }
683
684 /*
685 * send a Kerberos security response
686 */
rxkad_send_response(struct rxrpc_connection * conn,struct rxrpc_host_header * hdr,struct rxkad_response * resp,const struct rxkad_key * s2)687 static int rxkad_send_response(struct rxrpc_connection *conn,
688 struct rxrpc_host_header *hdr,
689 struct rxkad_response *resp,
690 const struct rxkad_key *s2)
691 {
692 struct rxrpc_wire_header whdr;
693 struct msghdr msg;
694 struct kvec iov[3];
695 size_t len;
696 u32 serial;
697 int ret;
698
699 _enter("");
700
701 msg.msg_name = &conn->peer->srx.transport;
702 msg.msg_namelen = conn->peer->srx.transport_len;
703 msg.msg_control = NULL;
704 msg.msg_controllen = 0;
705 msg.msg_flags = 0;
706
707 memset(&whdr, 0, sizeof(whdr));
708 whdr.epoch = htonl(hdr->epoch);
709 whdr.cid = htonl(hdr->cid);
710 whdr.type = RXRPC_PACKET_TYPE_RESPONSE;
711 whdr.flags = conn->out_clientflag;
712 whdr.securityIndex = hdr->securityIndex;
713 whdr.serviceId = htons(hdr->serviceId);
714
715 iov[0].iov_base = &whdr;
716 iov[0].iov_len = sizeof(whdr);
717 iov[1].iov_base = resp;
718 iov[1].iov_len = sizeof(*resp);
719 iov[2].iov_base = (void *)s2->ticket;
720 iov[2].iov_len = s2->ticket_len;
721
722 len = iov[0].iov_len + iov[1].iov_len + iov[2].iov_len;
723
724 serial = rxrpc_get_next_serial(conn);
725 whdr.serial = htonl(serial);
726
727 rxrpc_local_dont_fragment(conn->local, false);
728 ret = kernel_sendmsg(conn->local->socket, &msg, iov, 3, len);
729 rxrpc_local_dont_fragment(conn->local, true);
730 if (ret < 0) {
731 trace_rxrpc_tx_fail(conn->debug_id, serial, ret,
732 rxrpc_tx_point_rxkad_response);
733 return -EAGAIN;
734 }
735
736 conn->peer->last_tx_at = ktime_get_seconds();
737 _leave(" = 0");
738 return 0;
739 }
740
741 /*
742 * calculate the response checksum
743 */
rxkad_calc_response_checksum(struct rxkad_response * response)744 static void rxkad_calc_response_checksum(struct rxkad_response *response)
745 {
746 u32 csum = 1000003;
747 int loop;
748 u8 *p = (u8 *) response;
749
750 for (loop = sizeof(*response); loop > 0; loop--)
751 csum = csum * 0x10204081 + *p++;
752
753 response->encrypted.checksum = htonl(csum);
754 }
755
756 /*
757 * encrypt the response packet
758 */
rxkad_encrypt_response(struct rxrpc_connection * conn,struct rxkad_response * resp,const struct rxkad_key * s2)759 static int rxkad_encrypt_response(struct rxrpc_connection *conn,
760 struct rxkad_response *resp,
761 const struct rxkad_key *s2)
762 {
763 struct skcipher_request *req;
764 struct rxrpc_crypt iv;
765 struct scatterlist sg[1];
766
767 req = skcipher_request_alloc(&conn->rxkad.cipher->base, GFP_NOFS);
768 if (!req)
769 return -ENOMEM;
770
771 /* continue encrypting from where we left off */
772 memcpy(&iv, s2->session_key, sizeof(iv));
773
774 sg_init_table(sg, 1);
775 sg_set_buf(sg, &resp->encrypted, sizeof(resp->encrypted));
776 skcipher_request_set_sync_tfm(req, conn->rxkad.cipher);
777 skcipher_request_set_callback(req, 0, NULL, NULL);
778 skcipher_request_set_crypt(req, sg, sg, sizeof(resp->encrypted), iv.x);
779 crypto_skcipher_encrypt(req);
780 skcipher_request_free(req);
781 return 0;
782 }
783
784 /*
785 * respond to a challenge packet
786 */
rxkad_respond_to_challenge(struct rxrpc_connection * conn,struct sk_buff * skb)787 static int rxkad_respond_to_challenge(struct rxrpc_connection *conn,
788 struct sk_buff *skb)
789 {
790 const struct rxrpc_key_token *token;
791 struct rxkad_challenge challenge;
792 struct rxkad_response *resp;
793 struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
794 u32 version, nonce, min_level;
795 int ret = -EPROTO;
796
797 _enter("{%d,%x}", conn->debug_id, key_serial(conn->key));
798
799 if (!conn->key)
800 return rxrpc_abort_conn(conn, skb, RX_PROTOCOL_ERROR, -EPROTO,
801 rxkad_abort_chall_no_key);
802
803 ret = key_validate(conn->key);
804 if (ret < 0)
805 return rxrpc_abort_conn(conn, skb, RXKADEXPIRED, ret,
806 rxkad_abort_chall_key_expired);
807
808 if (skb_copy_bits(skb, sizeof(struct rxrpc_wire_header),
809 &challenge, sizeof(challenge)) < 0)
810 return rxrpc_abort_conn(conn, skb, RXKADPACKETSHORT, -EPROTO,
811 rxkad_abort_chall_short);
812
813 version = ntohl(challenge.version);
814 nonce = ntohl(challenge.nonce);
815 min_level = ntohl(challenge.min_level);
816
817 trace_rxrpc_rx_challenge(conn, sp->hdr.serial, version, nonce, min_level);
818
819 if (version != RXKAD_VERSION)
820 return rxrpc_abort_conn(conn, skb, RXKADINCONSISTENCY, -EPROTO,
821 rxkad_abort_chall_version);
822
823 if (conn->security_level < min_level)
824 return rxrpc_abort_conn(conn, skb, RXKADLEVELFAIL, -EACCES,
825 rxkad_abort_chall_level);
826
827 token = conn->key->payload.data[0];
828
829 /* build the response packet */
830 resp = kzalloc(sizeof(struct rxkad_response), GFP_NOFS);
831 if (!resp)
832 return -ENOMEM;
833
834 resp->version = htonl(RXKAD_VERSION);
835 resp->encrypted.epoch = htonl(conn->proto.epoch);
836 resp->encrypted.cid = htonl(conn->proto.cid);
837 resp->encrypted.securityIndex = htonl(conn->security_ix);
838 resp->encrypted.inc_nonce = htonl(nonce + 1);
839 resp->encrypted.level = htonl(conn->security_level);
840 resp->kvno = htonl(token->kad->kvno);
841 resp->ticket_len = htonl(token->kad->ticket_len);
842 resp->encrypted.call_id[0] = htonl(conn->channels[0].call_counter);
843 resp->encrypted.call_id[1] = htonl(conn->channels[1].call_counter);
844 resp->encrypted.call_id[2] = htonl(conn->channels[2].call_counter);
845 resp->encrypted.call_id[3] = htonl(conn->channels[3].call_counter);
846
847 /* calculate the response checksum and then do the encryption */
848 rxkad_calc_response_checksum(resp);
849 ret = rxkad_encrypt_response(conn, resp, token->kad);
850 if (ret == 0)
851 ret = rxkad_send_response(conn, &sp->hdr, resp, token->kad);
852 kfree(resp);
853 return ret;
854 }
855
856 /*
857 * decrypt the kerberos IV ticket in the response
858 */
rxkad_decrypt_ticket(struct rxrpc_connection * conn,struct key * server_key,struct sk_buff * skb,void * ticket,size_t ticket_len,struct rxrpc_crypt * _session_key,time64_t * _expiry)859 static int rxkad_decrypt_ticket(struct rxrpc_connection *conn,
860 struct key *server_key,
861 struct sk_buff *skb,
862 void *ticket, size_t ticket_len,
863 struct rxrpc_crypt *_session_key,
864 time64_t *_expiry)
865 {
866 struct skcipher_request *req;
867 struct rxrpc_crypt iv, key;
868 struct scatterlist sg[1];
869 struct in_addr addr;
870 unsigned int life;
871 time64_t issue, now;
872 bool little_endian;
873 u8 *p, *q, *name, *end;
874
875 _enter("{%d},{%x}", conn->debug_id, key_serial(server_key));
876
877 *_expiry = 0;
878
879 ASSERT(server_key->payload.data[0] != NULL);
880 ASSERTCMP((unsigned long) ticket & 7UL, ==, 0);
881
882 memcpy(&iv, &server_key->payload.data[2], sizeof(iv));
883
884 req = skcipher_request_alloc(server_key->payload.data[0], GFP_NOFS);
885 if (!req)
886 return -ENOMEM;
887
888 sg_init_one(&sg[0], ticket, ticket_len);
889 skcipher_request_set_callback(req, 0, NULL, NULL);
890 skcipher_request_set_crypt(req, sg, sg, ticket_len, iv.x);
891 crypto_skcipher_decrypt(req);
892 skcipher_request_free(req);
893
894 p = ticket;
895 end = p + ticket_len;
896
897 #define Z(field, fieldl) \
898 ({ \
899 u8 *__str = p; \
900 q = memchr(p, 0, end - p); \
901 if (!q || q - p > field##_SZ) \
902 return rxrpc_abort_conn( \
903 conn, skb, RXKADBADTICKET, -EPROTO, \
904 rxkad_abort_resp_tkt_##fieldl); \
905 for (; p < q; p++) \
906 if (!isprint(*p)) \
907 return rxrpc_abort_conn( \
908 conn, skb, RXKADBADTICKET, -EPROTO, \
909 rxkad_abort_resp_tkt_##fieldl); \
910 p++; \
911 __str; \
912 })
913
914 /* extract the ticket flags */
915 _debug("KIV FLAGS: %x", *p);
916 little_endian = *p & 1;
917 p++;
918
919 /* extract the authentication name */
920 name = Z(ANAME, aname);
921 _debug("KIV ANAME: %s", name);
922
923 /* extract the principal's instance */
924 name = Z(INST, inst);
925 _debug("KIV INST : %s", name);
926
927 /* extract the principal's authentication domain */
928 name = Z(REALM, realm);
929 _debug("KIV REALM: %s", name);
930
931 if (end - p < 4 + 8 + 4 + 2)
932 return rxrpc_abort_conn(conn, skb, RXKADBADTICKET, -EPROTO,
933 rxkad_abort_resp_tkt_short);
934
935 /* get the IPv4 address of the entity that requested the ticket */
936 memcpy(&addr, p, sizeof(addr));
937 p += 4;
938 _debug("KIV ADDR : %pI4", &addr);
939
940 /* get the session key from the ticket */
941 memcpy(&key, p, sizeof(key));
942 p += 8;
943 _debug("KIV KEY : %08x %08x", ntohl(key.n[0]), ntohl(key.n[1]));
944 memcpy(_session_key, &key, sizeof(key));
945
946 /* get the ticket's lifetime */
947 life = *p++ * 5 * 60;
948 _debug("KIV LIFE : %u", life);
949
950 /* get the issue time of the ticket */
951 if (little_endian) {
952 __le32 stamp;
953 memcpy(&stamp, p, 4);
954 issue = rxrpc_u32_to_time64(le32_to_cpu(stamp));
955 } else {
956 __be32 stamp;
957 memcpy(&stamp, p, 4);
958 issue = rxrpc_u32_to_time64(be32_to_cpu(stamp));
959 }
960 p += 4;
961 now = ktime_get_real_seconds();
962 _debug("KIV ISSUE: %llx [%llx]", issue, now);
963
964 /* check the ticket is in date */
965 if (issue > now)
966 return rxrpc_abort_conn(conn, skb, RXKADNOAUTH, -EKEYREJECTED,
967 rxkad_abort_resp_tkt_future);
968 if (issue < now - life)
969 return rxrpc_abort_conn(conn, skb, RXKADEXPIRED, -EKEYEXPIRED,
970 rxkad_abort_resp_tkt_expired);
971
972 *_expiry = issue + life;
973
974 /* get the service name */
975 name = Z(SNAME, sname);
976 _debug("KIV SNAME: %s", name);
977
978 /* get the service instance name */
979 name = Z(INST, sinst);
980 _debug("KIV SINST: %s", name);
981 return 0;
982 }
983
984 /*
985 * decrypt the response packet
986 */
rxkad_decrypt_response(struct rxrpc_connection * conn,struct rxkad_response * resp,const struct rxrpc_crypt * session_key)987 static void rxkad_decrypt_response(struct rxrpc_connection *conn,
988 struct rxkad_response *resp,
989 const struct rxrpc_crypt *session_key)
990 {
991 struct skcipher_request *req = rxkad_ci_req;
992 struct scatterlist sg[1];
993 struct rxrpc_crypt iv;
994
995 _enter(",,%08x%08x",
996 ntohl(session_key->n[0]), ntohl(session_key->n[1]));
997
998 mutex_lock(&rxkad_ci_mutex);
999 if (crypto_sync_skcipher_setkey(rxkad_ci, session_key->x,
1000 sizeof(*session_key)) < 0)
1001 BUG();
1002
1003 memcpy(&iv, session_key, sizeof(iv));
1004
1005 sg_init_table(sg, 1);
1006 sg_set_buf(sg, &resp->encrypted, sizeof(resp->encrypted));
1007 skcipher_request_set_sync_tfm(req, rxkad_ci);
1008 skcipher_request_set_callback(req, 0, NULL, NULL);
1009 skcipher_request_set_crypt(req, sg, sg, sizeof(resp->encrypted), iv.x);
1010 crypto_skcipher_decrypt(req);
1011 skcipher_request_zero(req);
1012
1013 mutex_unlock(&rxkad_ci_mutex);
1014
1015 _leave("");
1016 }
1017
1018 /*
1019 * verify a response
1020 */
rxkad_verify_response(struct rxrpc_connection * conn,struct sk_buff * skb)1021 static int rxkad_verify_response(struct rxrpc_connection *conn,
1022 struct sk_buff *skb)
1023 {
1024 struct rxkad_response *response;
1025 struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
1026 struct rxrpc_crypt session_key;
1027 struct key *server_key;
1028 time64_t expiry;
1029 void *ticket;
1030 u32 version, kvno, ticket_len, level;
1031 __be32 csum;
1032 int ret, i;
1033
1034 _enter("{%d}", conn->debug_id);
1035
1036 server_key = rxrpc_look_up_server_security(conn, skb, 0, 0);
1037 if (IS_ERR(server_key)) {
1038 ret = PTR_ERR(server_key);
1039 switch (ret) {
1040 case -ENOKEY:
1041 return rxrpc_abort_conn(conn, skb, RXKADUNKNOWNKEY, ret,
1042 rxkad_abort_resp_nokey);
1043 case -EKEYEXPIRED:
1044 return rxrpc_abort_conn(conn, skb, RXKADEXPIRED, ret,
1045 rxkad_abort_resp_key_expired);
1046 default:
1047 return rxrpc_abort_conn(conn, skb, RXKADNOAUTH, ret,
1048 rxkad_abort_resp_key_rejected);
1049 }
1050 }
1051
1052 ret = -ENOMEM;
1053 response = kzalloc(sizeof(struct rxkad_response), GFP_NOFS);
1054 if (!response)
1055 goto temporary_error;
1056
1057 if (skb_copy_bits(skb, sizeof(struct rxrpc_wire_header),
1058 response, sizeof(*response)) < 0) {
1059 rxrpc_abort_conn(conn, skb, RXKADPACKETSHORT, -EPROTO,
1060 rxkad_abort_resp_short);
1061 goto protocol_error;
1062 }
1063
1064 version = ntohl(response->version);
1065 ticket_len = ntohl(response->ticket_len);
1066 kvno = ntohl(response->kvno);
1067
1068 trace_rxrpc_rx_response(conn, sp->hdr.serial, version, kvno, ticket_len);
1069
1070 if (version != RXKAD_VERSION) {
1071 rxrpc_abort_conn(conn, skb, RXKADINCONSISTENCY, -EPROTO,
1072 rxkad_abort_resp_version);
1073 goto protocol_error;
1074 }
1075
1076 if (ticket_len < 4 || ticket_len > MAXKRB5TICKETLEN) {
1077 rxrpc_abort_conn(conn, skb, RXKADTICKETLEN, -EPROTO,
1078 rxkad_abort_resp_tkt_len);
1079 goto protocol_error;
1080 }
1081
1082 if (kvno >= RXKAD_TKT_TYPE_KERBEROS_V5) {
1083 rxrpc_abort_conn(conn, skb, RXKADUNKNOWNKEY, -EPROTO,
1084 rxkad_abort_resp_unknown_tkt);
1085 goto protocol_error;
1086 }
1087
1088 /* extract the kerberos ticket and decrypt and decode it */
1089 ret = -ENOMEM;
1090 ticket = kmalloc(ticket_len, GFP_NOFS);
1091 if (!ticket)
1092 goto temporary_error_free_resp;
1093
1094 if (skb_copy_bits(skb, sizeof(struct rxrpc_wire_header) + sizeof(*response),
1095 ticket, ticket_len) < 0) {
1096 rxrpc_abort_conn(conn, skb, RXKADPACKETSHORT, -EPROTO,
1097 rxkad_abort_resp_short_tkt);
1098 goto protocol_error;
1099 }
1100
1101 ret = rxkad_decrypt_ticket(conn, server_key, skb, ticket, ticket_len,
1102 &session_key, &expiry);
1103 if (ret < 0)
1104 goto temporary_error_free_ticket;
1105
1106 /* use the session key from inside the ticket to decrypt the
1107 * response */
1108 rxkad_decrypt_response(conn, response, &session_key);
1109
1110 if (ntohl(response->encrypted.epoch) != conn->proto.epoch ||
1111 ntohl(response->encrypted.cid) != conn->proto.cid ||
1112 ntohl(response->encrypted.securityIndex) != conn->security_ix) {
1113 rxrpc_abort_conn(conn, skb, RXKADSEALEDINCON, -EPROTO,
1114 rxkad_abort_resp_bad_param);
1115 goto protocol_error_free;
1116 }
1117
1118 csum = response->encrypted.checksum;
1119 response->encrypted.checksum = 0;
1120 rxkad_calc_response_checksum(response);
1121 if (response->encrypted.checksum != csum) {
1122 rxrpc_abort_conn(conn, skb, RXKADSEALEDINCON, -EPROTO,
1123 rxkad_abort_resp_bad_checksum);
1124 goto protocol_error_free;
1125 }
1126
1127 for (i = 0; i < RXRPC_MAXCALLS; i++) {
1128 u32 call_id = ntohl(response->encrypted.call_id[i]);
1129 u32 counter = READ_ONCE(conn->channels[i].call_counter);
1130
1131 if (call_id > INT_MAX) {
1132 rxrpc_abort_conn(conn, skb, RXKADSEALEDINCON, -EPROTO,
1133 rxkad_abort_resp_bad_callid);
1134 goto protocol_error_free;
1135 }
1136
1137 if (call_id < counter) {
1138 rxrpc_abort_conn(conn, skb, RXKADSEALEDINCON, -EPROTO,
1139 rxkad_abort_resp_call_ctr);
1140 goto protocol_error_free;
1141 }
1142
1143 if (call_id > counter) {
1144 if (conn->channels[i].call) {
1145 rxrpc_abort_conn(conn, skb, RXKADSEALEDINCON, -EPROTO,
1146 rxkad_abort_resp_call_state);
1147 goto protocol_error_free;
1148 }
1149 conn->channels[i].call_counter = call_id;
1150 }
1151 }
1152
1153 if (ntohl(response->encrypted.inc_nonce) != conn->rxkad.nonce + 1) {
1154 rxrpc_abort_conn(conn, skb, RXKADOUTOFSEQUENCE, -EPROTO,
1155 rxkad_abort_resp_ooseq);
1156 goto protocol_error_free;
1157 }
1158
1159 level = ntohl(response->encrypted.level);
1160 if (level > RXRPC_SECURITY_ENCRYPT) {
1161 rxrpc_abort_conn(conn, skb, RXKADLEVELFAIL, -EPROTO,
1162 rxkad_abort_resp_level);
1163 goto protocol_error_free;
1164 }
1165 conn->security_level = level;
1166
1167 /* create a key to hold the security data and expiration time - after
1168 * this the connection security can be handled in exactly the same way
1169 * as for a client connection */
1170 ret = rxrpc_get_server_data_key(conn, &session_key, expiry, kvno);
1171 if (ret < 0)
1172 goto temporary_error_free_ticket;
1173
1174 kfree(ticket);
1175 kfree(response);
1176 _leave(" = 0");
1177 return 0;
1178
1179 protocol_error_free:
1180 kfree(ticket);
1181 protocol_error:
1182 kfree(response);
1183 key_put(server_key);
1184 return -EPROTO;
1185
1186 temporary_error_free_ticket:
1187 kfree(ticket);
1188 temporary_error_free_resp:
1189 kfree(response);
1190 temporary_error:
1191 /* Ignore the response packet if we got a temporary error such as
1192 * ENOMEM. We just want to send the challenge again. Note that we
1193 * also come out this way if the ticket decryption fails.
1194 */
1195 key_put(server_key);
1196 return ret;
1197 }
1198
1199 /*
1200 * clear the connection security
1201 */
rxkad_clear(struct rxrpc_connection * conn)1202 static void rxkad_clear(struct rxrpc_connection *conn)
1203 {
1204 _enter("");
1205
1206 if (conn->rxkad.cipher)
1207 crypto_free_sync_skcipher(conn->rxkad.cipher);
1208 }
1209
1210 /*
1211 * Initialise the rxkad security service.
1212 */
rxkad_init(void)1213 static int rxkad_init(void)
1214 {
1215 struct crypto_sync_skcipher *tfm;
1216 struct skcipher_request *req;
1217
1218 /* pin the cipher we need so that the crypto layer doesn't invoke
1219 * keventd to go get it */
1220 tfm = crypto_alloc_sync_skcipher("pcbc(fcrypt)", 0, 0);
1221 if (IS_ERR(tfm))
1222 return PTR_ERR(tfm);
1223
1224 req = skcipher_request_alloc(&tfm->base, GFP_KERNEL);
1225 if (!req)
1226 goto nomem_tfm;
1227
1228 rxkad_ci_req = req;
1229 rxkad_ci = tfm;
1230 return 0;
1231
1232 nomem_tfm:
1233 crypto_free_sync_skcipher(tfm);
1234 return -ENOMEM;
1235 }
1236
1237 /*
1238 * Clean up the rxkad security service.
1239 */
rxkad_exit(void)1240 static void rxkad_exit(void)
1241 {
1242 crypto_free_sync_skcipher(rxkad_ci);
1243 skcipher_request_free(rxkad_ci_req);
1244 }
1245
1246 /*
1247 * RxRPC Kerberos-based security
1248 */
1249 const struct rxrpc_security rxkad = {
1250 .name = "rxkad",
1251 .security_index = RXRPC_SECURITY_RXKAD,
1252 .no_key_abort = RXKADUNKNOWNKEY,
1253 .init = rxkad_init,
1254 .exit = rxkad_exit,
1255 .preparse_server_key = rxkad_preparse_server_key,
1256 .free_preparse_server_key = rxkad_free_preparse_server_key,
1257 .destroy_server_key = rxkad_destroy_server_key,
1258 .init_connection_security = rxkad_init_connection_security,
1259 .how_much_data = rxkad_how_much_data,
1260 .secure_packet = rxkad_secure_packet,
1261 .verify_packet = rxkad_verify_packet,
1262 .free_call_crypto = rxkad_free_call_crypto,
1263 .issue_challenge = rxkad_issue_challenge,
1264 .respond_to_challenge = rxkad_respond_to_challenge,
1265 .verify_response = rxkad_verify_response,
1266 .clear = rxkad_clear,
1267 };
1268