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 */
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
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
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 */
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 */
148 static struct rxrpc_txbuf *rxkad_alloc_txbuf(struct rxrpc_call *call, size_t remain, gfp_t gfp)
149 {
150 struct rxrpc_txbuf *txb;
151 size_t shdr, space;
152
153 remain = min(remain, 65535 - sizeof(struct rxrpc_wire_header));
154
155 switch (call->conn->security_level) {
156 default:
157 space = min_t(size_t, remain, RXRPC_JUMBO_DATALEN);
158 return rxrpc_alloc_data_txbuf(call, space, 1, gfp);
159 case RXRPC_SECURITY_AUTH:
160 shdr = sizeof(struct rxkad_level1_hdr);
161 break;
162 case RXRPC_SECURITY_ENCRYPT:
163 shdr = sizeof(struct rxkad_level2_hdr);
164 break;
165 }
166
167 space = min_t(size_t, round_down(RXRPC_JUMBO_DATALEN, RXKAD_ALIGN), remain + shdr);
168 space = round_up(space, RXKAD_ALIGN);
169
170 txb = rxrpc_alloc_data_txbuf(call, space, RXKAD_ALIGN, gfp);
171 if (!txb)
172 return NULL;
173
174 txb->offset += shdr;
175 txb->space -= shdr;
176 return txb;
177 }
178
179 /*
180 * prime the encryption state with the invariant parts of a connection's
181 * description
182 */
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 */
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 */
243 static void rxkad_free_call_crypto(struct rxrpc_call *call)
244 {
245 }
246
247 /*
248 * partially encrypt a packet (level 1 security)
249 */
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 rxrpc_wire_header *whdr = txb->kvec[0].iov_base;
255 struct rxkad_level1_hdr *hdr = (void *)(whdr + 1);
256 struct rxrpc_crypt iv;
257 struct scatterlist sg;
258 size_t pad;
259 u16 check;
260
261 _enter("");
262
263 check = txb->seq ^ call->call_id;
264 hdr->data_size = htonl((u32)check << 16 | txb->len);
265
266 txb->len += sizeof(struct rxkad_level1_hdr);
267 pad = txb->len;
268 pad = RXKAD_ALIGN - pad;
269 pad &= RXKAD_ALIGN - 1;
270 if (pad) {
271 memset(txb->kvec[0].iov_base + txb->offset, 0, pad);
272 txb->len += pad;
273 }
274
275 /* start the encryption afresh */
276 memset(&iv, 0, sizeof(iv));
277
278 sg_init_one(&sg, hdr, 8);
279 skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher);
280 skcipher_request_set_callback(req, 0, NULL, NULL);
281 skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x);
282 crypto_skcipher_encrypt(req);
283 skcipher_request_zero(req);
284
285 _leave(" = 0");
286 return 0;
287 }
288
289 /*
290 * wholly encrypt a packet (level 2 security)
291 */
292 static int rxkad_secure_packet_encrypt(const struct rxrpc_call *call,
293 struct rxrpc_txbuf *txb,
294 struct skcipher_request *req)
295 {
296 const struct rxrpc_key_token *token;
297 struct rxrpc_wire_header *whdr = txb->kvec[0].iov_base;
298 struct rxkad_level2_hdr *rxkhdr = (void *)(whdr + 1);
299 struct rxrpc_crypt iv;
300 struct scatterlist sg;
301 size_t pad;
302 u16 check;
303 int ret;
304
305 _enter("");
306
307 check = txb->seq ^ call->call_id;
308
309 rxkhdr->data_size = htonl(txb->len | (u32)check << 16);
310 rxkhdr->checksum = 0;
311
312 txb->len += sizeof(struct rxkad_level2_hdr);
313 pad = txb->len;
314 pad = RXKAD_ALIGN - pad;
315 pad &= RXKAD_ALIGN - 1;
316 if (pad) {
317 memset(txb->kvec[0].iov_base + txb->offset, 0, pad);
318 txb->len += pad;
319 }
320
321 /* encrypt from the session key */
322 token = call->conn->key->payload.data[0];
323 memcpy(&iv, token->kad->session_key, sizeof(iv));
324
325 sg_init_one(&sg, rxkhdr, txb->len);
326 skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher);
327 skcipher_request_set_callback(req, 0, NULL, NULL);
328 skcipher_request_set_crypt(req, &sg, &sg, txb->len, iv.x);
329 ret = crypto_skcipher_encrypt(req);
330 skcipher_request_zero(req);
331 return ret;
332 }
333
334 /*
335 * checksum an RxRPC packet header
336 */
337 static int rxkad_secure_packet(struct rxrpc_call *call, struct rxrpc_txbuf *txb)
338 {
339 struct skcipher_request *req;
340 struct rxrpc_crypt iv;
341 struct scatterlist sg;
342 union {
343 __be32 buf[2];
344 } crypto __aligned(8);
345 u32 x, y;
346 int ret;
347
348 _enter("{%d{%x}},{#%u},%u,",
349 call->debug_id, key_serial(call->conn->key),
350 txb->seq, txb->len);
351
352 if (!call->conn->rxkad.cipher)
353 return 0;
354
355 ret = key_validate(call->conn->key);
356 if (ret < 0)
357 return ret;
358
359 req = rxkad_get_call_crypto(call);
360 if (!req)
361 return -ENOMEM;
362
363 /* continue encrypting from where we left off */
364 memcpy(&iv, call->conn->rxkad.csum_iv.x, sizeof(iv));
365
366 /* calculate the security checksum */
367 x = (call->cid & RXRPC_CHANNELMASK) << (32 - RXRPC_CIDSHIFT);
368 x |= txb->seq & 0x3fffffff;
369 crypto.buf[0] = htonl(call->call_id);
370 crypto.buf[1] = htonl(x);
371
372 sg_init_one(&sg, crypto.buf, 8);
373 skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher);
374 skcipher_request_set_callback(req, 0, NULL, NULL);
375 skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x);
376 crypto_skcipher_encrypt(req);
377 skcipher_request_zero(req);
378
379 y = ntohl(crypto.buf[1]);
380 y = (y >> 16) & 0xffff;
381 if (y == 0)
382 y = 1; /* zero checksums are not permitted */
383 txb->cksum = htons(y);
384
385 switch (call->conn->security_level) {
386 case RXRPC_SECURITY_PLAIN:
387 ret = 0;
388 break;
389 case RXRPC_SECURITY_AUTH:
390 ret = rxkad_secure_packet_auth(call, txb, req);
391 break;
392 case RXRPC_SECURITY_ENCRYPT:
393 ret = rxkad_secure_packet_encrypt(call, txb, req);
394 break;
395 default:
396 ret = -EPERM;
397 break;
398 }
399
400 skcipher_request_free(req);
401 _leave(" = %d [set %x]", ret, y);
402 return ret;
403 }
404
405 /*
406 * decrypt partial encryption on a packet (level 1 security)
407 */
408 static int rxkad_verify_packet_1(struct rxrpc_call *call, struct sk_buff *skb,
409 rxrpc_seq_t seq,
410 struct skcipher_request *req)
411 {
412 struct rxkad_level1_hdr sechdr;
413 struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
414 struct rxrpc_crypt iv;
415 struct scatterlist sg[16];
416 u32 data_size, buf;
417 u16 check;
418 int ret;
419
420 _enter("");
421
422 if (sp->len < 8)
423 return rxrpc_abort_eproto(call, skb, RXKADSEALEDINCON,
424 rxkad_abort_1_short_header);
425
426 /* Decrypt the skbuff in-place. TODO: We really want to decrypt
427 * directly into the target buffer.
428 */
429 sg_init_table(sg, ARRAY_SIZE(sg));
430 ret = skb_to_sgvec(skb, sg, sp->offset, 8);
431 if (unlikely(ret < 0))
432 return ret;
433
434 /* start the decryption afresh */
435 memset(&iv, 0, sizeof(iv));
436
437 skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher);
438 skcipher_request_set_callback(req, 0, NULL, NULL);
439 skcipher_request_set_crypt(req, sg, sg, 8, iv.x);
440 crypto_skcipher_decrypt(req);
441 skcipher_request_zero(req);
442
443 /* Extract the decrypted packet length */
444 if (skb_copy_bits(skb, sp->offset, &sechdr, sizeof(sechdr)) < 0)
445 return rxrpc_abort_eproto(call, skb, RXKADDATALEN,
446 rxkad_abort_1_short_encdata);
447 sp->offset += sizeof(sechdr);
448 sp->len -= sizeof(sechdr);
449
450 buf = ntohl(sechdr.data_size);
451 data_size = buf & 0xffff;
452
453 check = buf >> 16;
454 check ^= seq ^ call->call_id;
455 check &= 0xffff;
456 if (check != 0)
457 return rxrpc_abort_eproto(call, skb, RXKADSEALEDINCON,
458 rxkad_abort_1_short_check);
459 if (data_size > sp->len)
460 return rxrpc_abort_eproto(call, skb, RXKADDATALEN,
461 rxkad_abort_1_short_data);
462 sp->len = data_size;
463
464 _leave(" = 0 [dlen=%x]", data_size);
465 return 0;
466 }
467
468 /*
469 * wholly decrypt a packet (level 2 security)
470 */
471 static int rxkad_verify_packet_2(struct rxrpc_call *call, struct sk_buff *skb,
472 rxrpc_seq_t seq,
473 struct skcipher_request *req)
474 {
475 const struct rxrpc_key_token *token;
476 struct rxkad_level2_hdr sechdr;
477 struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
478 struct rxrpc_crypt iv;
479 struct scatterlist _sg[4], *sg;
480 u32 data_size, buf;
481 u16 check;
482 int nsg, ret;
483
484 _enter(",{%d}", sp->len);
485
486 if (sp->len < 8)
487 return rxrpc_abort_eproto(call, skb, RXKADSEALEDINCON,
488 rxkad_abort_2_short_header);
489
490 /* Decrypt the skbuff in-place. TODO: We really want to decrypt
491 * directly into the target buffer.
492 */
493 sg = _sg;
494 nsg = skb_shinfo(skb)->nr_frags + 1;
495 if (nsg <= 4) {
496 nsg = 4;
497 } else {
498 sg = kmalloc_array(nsg, sizeof(*sg), GFP_NOIO);
499 if (!sg)
500 return -ENOMEM;
501 }
502
503 sg_init_table(sg, nsg);
504 ret = skb_to_sgvec(skb, sg, sp->offset, sp->len);
505 if (unlikely(ret < 0)) {
506 if (sg != _sg)
507 kfree(sg);
508 return ret;
509 }
510
511 /* decrypt from the session key */
512 token = call->conn->key->payload.data[0];
513 memcpy(&iv, token->kad->session_key, sizeof(iv));
514
515 skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher);
516 skcipher_request_set_callback(req, 0, NULL, NULL);
517 skcipher_request_set_crypt(req, sg, sg, sp->len, iv.x);
518 crypto_skcipher_decrypt(req);
519 skcipher_request_zero(req);
520 if (sg != _sg)
521 kfree(sg);
522
523 /* Extract the decrypted packet length */
524 if (skb_copy_bits(skb, sp->offset, &sechdr, sizeof(sechdr)) < 0)
525 return rxrpc_abort_eproto(call, skb, RXKADDATALEN,
526 rxkad_abort_2_short_len);
527 sp->offset += sizeof(sechdr);
528 sp->len -= sizeof(sechdr);
529
530 buf = ntohl(sechdr.data_size);
531 data_size = buf & 0xffff;
532
533 check = buf >> 16;
534 check ^= seq ^ call->call_id;
535 check &= 0xffff;
536 if (check != 0)
537 return rxrpc_abort_eproto(call, skb, RXKADSEALEDINCON,
538 rxkad_abort_2_short_check);
539
540 if (data_size > sp->len)
541 return rxrpc_abort_eproto(call, skb, RXKADDATALEN,
542 rxkad_abort_2_short_data);
543
544 sp->len = data_size;
545 _leave(" = 0 [dlen=%x]", data_size);
546 return 0;
547 }
548
549 /*
550 * Verify the security on a received packet and the subpackets therein.
551 */
552 static int rxkad_verify_packet(struct rxrpc_call *call, struct sk_buff *skb)
553 {
554 struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
555 struct skcipher_request *req;
556 struct rxrpc_crypt iv;
557 struct scatterlist sg;
558 union {
559 __be32 buf[2];
560 } crypto __aligned(8);
561 rxrpc_seq_t seq = sp->hdr.seq;
562 int ret;
563 u16 cksum;
564 u32 x, y;
565
566 _enter("{%d{%x}},{#%u}",
567 call->debug_id, key_serial(call->conn->key), seq);
568
569 if (!call->conn->rxkad.cipher)
570 return 0;
571
572 req = rxkad_get_call_crypto(call);
573 if (!req)
574 return -ENOMEM;
575
576 /* continue encrypting from where we left off */
577 memcpy(&iv, call->conn->rxkad.csum_iv.x, sizeof(iv));
578
579 /* validate the security checksum */
580 x = (call->cid & RXRPC_CHANNELMASK) << (32 - RXRPC_CIDSHIFT);
581 x |= seq & 0x3fffffff;
582 crypto.buf[0] = htonl(call->call_id);
583 crypto.buf[1] = htonl(x);
584
585 sg_init_one(&sg, crypto.buf, 8);
586 skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher);
587 skcipher_request_set_callback(req, 0, NULL, NULL);
588 skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x);
589 crypto_skcipher_encrypt(req);
590 skcipher_request_zero(req);
591
592 y = ntohl(crypto.buf[1]);
593 cksum = (y >> 16) & 0xffff;
594 if (cksum == 0)
595 cksum = 1; /* zero checksums are not permitted */
596
597 if (cksum != sp->hdr.cksum) {
598 ret = rxrpc_abort_eproto(call, skb, RXKADSEALEDINCON,
599 rxkad_abort_bad_checksum);
600 goto out;
601 }
602
603 switch (call->conn->security_level) {
604 case RXRPC_SECURITY_PLAIN:
605 ret = 0;
606 break;
607 case RXRPC_SECURITY_AUTH:
608 ret = rxkad_verify_packet_1(call, skb, seq, req);
609 break;
610 case RXRPC_SECURITY_ENCRYPT:
611 ret = rxkad_verify_packet_2(call, skb, seq, req);
612 break;
613 default:
614 ret = -ENOANO;
615 break;
616 }
617
618 out:
619 skcipher_request_free(req);
620 return ret;
621 }
622
623 /*
624 * issue a challenge
625 */
626 static int rxkad_issue_challenge(struct rxrpc_connection *conn)
627 {
628 struct rxkad_challenge challenge;
629 struct rxrpc_wire_header whdr;
630 struct msghdr msg;
631 struct kvec iov[2];
632 size_t len;
633 u32 serial;
634 int ret;
635
636 _enter("{%d}", conn->debug_id);
637
638 get_random_bytes(&conn->rxkad.nonce, sizeof(conn->rxkad.nonce));
639
640 challenge.version = htonl(2);
641 challenge.nonce = htonl(conn->rxkad.nonce);
642 challenge.min_level = htonl(0);
643 challenge.__padding = 0;
644
645 msg.msg_name = &conn->peer->srx.transport;
646 msg.msg_namelen = conn->peer->srx.transport_len;
647 msg.msg_control = NULL;
648 msg.msg_controllen = 0;
649 msg.msg_flags = 0;
650
651 whdr.epoch = htonl(conn->proto.epoch);
652 whdr.cid = htonl(conn->proto.cid);
653 whdr.callNumber = 0;
654 whdr.seq = 0;
655 whdr.type = RXRPC_PACKET_TYPE_CHALLENGE;
656 whdr.flags = conn->out_clientflag;
657 whdr.userStatus = 0;
658 whdr.securityIndex = conn->security_ix;
659 whdr._rsvd = 0;
660 whdr.serviceId = htons(conn->service_id);
661
662 iov[0].iov_base = &whdr;
663 iov[0].iov_len = sizeof(whdr);
664 iov[1].iov_base = &challenge;
665 iov[1].iov_len = sizeof(challenge);
666
667 len = iov[0].iov_len + iov[1].iov_len;
668
669 serial = rxrpc_get_next_serial(conn);
670 whdr.serial = htonl(serial);
671
672 ret = kernel_sendmsg(conn->local->socket, &msg, iov, 2, len);
673 if (ret < 0) {
674 trace_rxrpc_tx_fail(conn->debug_id, serial, ret,
675 rxrpc_tx_point_rxkad_challenge);
676 return -EAGAIN;
677 }
678
679 conn->peer->last_tx_at = ktime_get_seconds();
680 trace_rxrpc_tx_packet(conn->debug_id, &whdr,
681 rxrpc_tx_point_rxkad_challenge);
682 _leave(" = 0");
683 return 0;
684 }
685
686 /*
687 * send a Kerberos security response
688 */
689 static int rxkad_send_response(struct rxrpc_connection *conn,
690 struct rxrpc_host_header *hdr,
691 struct rxkad_response *resp,
692 const struct rxkad_key *s2)
693 {
694 struct rxrpc_wire_header whdr;
695 struct msghdr msg;
696 struct kvec iov[3];
697 size_t len;
698 u32 serial;
699 int ret;
700
701 _enter("");
702
703 msg.msg_name = &conn->peer->srx.transport;
704 msg.msg_namelen = conn->peer->srx.transport_len;
705 msg.msg_control = NULL;
706 msg.msg_controllen = 0;
707 msg.msg_flags = 0;
708
709 memset(&whdr, 0, sizeof(whdr));
710 whdr.epoch = htonl(hdr->epoch);
711 whdr.cid = htonl(hdr->cid);
712 whdr.type = RXRPC_PACKET_TYPE_RESPONSE;
713 whdr.flags = conn->out_clientflag;
714 whdr.securityIndex = hdr->securityIndex;
715 whdr.serviceId = htons(hdr->serviceId);
716
717 iov[0].iov_base = &whdr;
718 iov[0].iov_len = sizeof(whdr);
719 iov[1].iov_base = resp;
720 iov[1].iov_len = sizeof(*resp);
721 iov[2].iov_base = (void *)s2->ticket;
722 iov[2].iov_len = s2->ticket_len;
723
724 len = iov[0].iov_len + iov[1].iov_len + iov[2].iov_len;
725
726 serial = rxrpc_get_next_serial(conn);
727 whdr.serial = htonl(serial);
728
729 rxrpc_local_dont_fragment(conn->local, false);
730 ret = kernel_sendmsg(conn->local->socket, &msg, iov, 3, len);
731 if (ret < 0) {
732 trace_rxrpc_tx_fail(conn->debug_id, serial, ret,
733 rxrpc_tx_point_rxkad_response);
734 return -EAGAIN;
735 }
736
737 conn->peer->last_tx_at = ktime_get_seconds();
738 _leave(" = 0");
739 return 0;
740 }
741
742 /*
743 * calculate the response checksum
744 */
745 static void rxkad_calc_response_checksum(struct rxkad_response *response)
746 {
747 u32 csum = 1000003;
748 int loop;
749 u8 *p = (u8 *) response;
750
751 for (loop = sizeof(*response); loop > 0; loop--)
752 csum = csum * 0x10204081 + *p++;
753
754 response->encrypted.checksum = htonl(csum);
755 }
756
757 /*
758 * encrypt the response packet
759 */
760 static int rxkad_encrypt_response(struct rxrpc_connection *conn,
761 struct rxkad_response *resp,
762 const struct rxkad_key *s2)
763 {
764 struct skcipher_request *req;
765 struct rxrpc_crypt iv;
766 struct scatterlist sg[1];
767
768 req = skcipher_request_alloc(&conn->rxkad.cipher->base, GFP_NOFS);
769 if (!req)
770 return -ENOMEM;
771
772 /* continue encrypting from where we left off */
773 memcpy(&iv, s2->session_key, sizeof(iv));
774
775 sg_init_table(sg, 1);
776 sg_set_buf(sg, &resp->encrypted, sizeof(resp->encrypted));
777 skcipher_request_set_sync_tfm(req, conn->rxkad.cipher);
778 skcipher_request_set_callback(req, 0, NULL, NULL);
779 skcipher_request_set_crypt(req, sg, sg, sizeof(resp->encrypted), iv.x);
780 crypto_skcipher_encrypt(req);
781 skcipher_request_free(req);
782 return 0;
783 }
784
785 /*
786 * respond to a challenge packet
787 */
788 static int rxkad_respond_to_challenge(struct rxrpc_connection *conn,
789 struct sk_buff *skb)
790 {
791 const struct rxrpc_key_token *token;
792 struct rxkad_challenge challenge;
793 struct rxkad_response *resp;
794 struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
795 u32 version, nonce, min_level;
796 int ret = -EPROTO;
797
798 _enter("{%d,%x}", conn->debug_id, key_serial(conn->key));
799
800 if (!conn->key)
801 return rxrpc_abort_conn(conn, skb, RX_PROTOCOL_ERROR, -EPROTO,
802 rxkad_abort_chall_no_key);
803
804 ret = key_validate(conn->key);
805 if (ret < 0)
806 return rxrpc_abort_conn(conn, skb, RXKADEXPIRED, ret,
807 rxkad_abort_chall_key_expired);
808
809 if (skb_copy_bits(skb, sizeof(struct rxrpc_wire_header),
810 &challenge, sizeof(challenge)) < 0)
811 return rxrpc_abort_conn(conn, skb, RXKADPACKETSHORT, -EPROTO,
812 rxkad_abort_chall_short);
813
814 version = ntohl(challenge.version);
815 nonce = ntohl(challenge.nonce);
816 min_level = ntohl(challenge.min_level);
817
818 trace_rxrpc_rx_challenge(conn, sp->hdr.serial, version, nonce, min_level);
819
820 if (version != RXKAD_VERSION)
821 return rxrpc_abort_conn(conn, skb, RXKADINCONSISTENCY, -EPROTO,
822 rxkad_abort_chall_version);
823
824 if (conn->security_level < min_level)
825 return rxrpc_abort_conn(conn, skb, RXKADLEVELFAIL, -EACCES,
826 rxkad_abort_chall_level);
827
828 token = conn->key->payload.data[0];
829
830 /* build the response packet */
831 resp = kzalloc(sizeof(struct rxkad_response), GFP_NOFS);
832 if (!resp)
833 return -ENOMEM;
834
835 resp->version = htonl(RXKAD_VERSION);
836 resp->encrypted.epoch = htonl(conn->proto.epoch);
837 resp->encrypted.cid = htonl(conn->proto.cid);
838 resp->encrypted.securityIndex = htonl(conn->security_ix);
839 resp->encrypted.inc_nonce = htonl(nonce + 1);
840 resp->encrypted.level = htonl(conn->security_level);
841 resp->kvno = htonl(token->kad->kvno);
842 resp->ticket_len = htonl(token->kad->ticket_len);
843 resp->encrypted.call_id[0] = htonl(conn->channels[0].call_counter);
844 resp->encrypted.call_id[1] = htonl(conn->channels[1].call_counter);
845 resp->encrypted.call_id[2] = htonl(conn->channels[2].call_counter);
846 resp->encrypted.call_id[3] = htonl(conn->channels[3].call_counter);
847
848 /* calculate the response checksum and then do the encryption */
849 rxkad_calc_response_checksum(resp);
850 ret = rxkad_encrypt_response(conn, resp, token->kad);
851 if (ret == 0)
852 ret = rxkad_send_response(conn, &sp->hdr, resp, token->kad);
853 kfree(resp);
854 return ret;
855 }
856
857 /*
858 * decrypt the kerberos IV ticket in the response
859 */
860 static int rxkad_decrypt_ticket(struct rxrpc_connection *conn,
861 struct key *server_key,
862 struct sk_buff *skb,
863 void *ticket, size_t ticket_len,
864 struct rxrpc_crypt *_session_key,
865 time64_t *_expiry)
866 {
867 struct skcipher_request *req;
868 struct rxrpc_crypt iv, key;
869 struct scatterlist sg[1];
870 struct in_addr addr;
871 unsigned int life;
872 time64_t issue, now;
873 bool little_endian;
874 u8 *p, *q, *name, *end;
875
876 _enter("{%d},{%x}", conn->debug_id, key_serial(server_key));
877
878 *_expiry = 0;
879
880 ASSERT(server_key->payload.data[0] != NULL);
881 ASSERTCMP((unsigned long) ticket & 7UL, ==, 0);
882
883 memcpy(&iv, &server_key->payload.data[2], sizeof(iv));
884
885 req = skcipher_request_alloc(server_key->payload.data[0], GFP_NOFS);
886 if (!req)
887 return -ENOMEM;
888
889 sg_init_one(&sg[0], ticket, ticket_len);
890 skcipher_request_set_callback(req, 0, NULL, NULL);
891 skcipher_request_set_crypt(req, sg, sg, ticket_len, iv.x);
892 crypto_skcipher_decrypt(req);
893 skcipher_request_free(req);
894
895 p = ticket;
896 end = p + ticket_len;
897
898 #define Z(field, fieldl) \
899 ({ \
900 u8 *__str = p; \
901 q = memchr(p, 0, end - p); \
902 if (!q || q - p > field##_SZ) \
903 return rxrpc_abort_conn( \
904 conn, skb, RXKADBADTICKET, -EPROTO, \
905 rxkad_abort_resp_tkt_##fieldl); \
906 for (; p < q; p++) \
907 if (!isprint(*p)) \
908 return rxrpc_abort_conn( \
909 conn, skb, RXKADBADTICKET, -EPROTO, \
910 rxkad_abort_resp_tkt_##fieldl); \
911 p++; \
912 __str; \
913 })
914
915 /* extract the ticket flags */
916 _debug("KIV FLAGS: %x", *p);
917 little_endian = *p & 1;
918 p++;
919
920 /* extract the authentication name */
921 name = Z(ANAME, aname);
922 _debug("KIV ANAME: %s", name);
923
924 /* extract the principal's instance */
925 name = Z(INST, inst);
926 _debug("KIV INST : %s", name);
927
928 /* extract the principal's authentication domain */
929 name = Z(REALM, realm);
930 _debug("KIV REALM: %s", name);
931
932 if (end - p < 4 + 8 + 4 + 2)
933 return rxrpc_abort_conn(conn, skb, RXKADBADTICKET, -EPROTO,
934 rxkad_abort_resp_tkt_short);
935
936 /* get the IPv4 address of the entity that requested the ticket */
937 memcpy(&addr, p, sizeof(addr));
938 p += 4;
939 _debug("KIV ADDR : %pI4", &addr);
940
941 /* get the session key from the ticket */
942 memcpy(&key, p, sizeof(key));
943 p += 8;
944 _debug("KIV KEY : %08x %08x", ntohl(key.n[0]), ntohl(key.n[1]));
945 memcpy(_session_key, &key, sizeof(key));
946
947 /* get the ticket's lifetime */
948 life = *p++ * 5 * 60;
949 _debug("KIV LIFE : %u", life);
950
951 /* get the issue time of the ticket */
952 if (little_endian) {
953 __le32 stamp;
954 memcpy(&stamp, p, 4);
955 issue = rxrpc_u32_to_time64(le32_to_cpu(stamp));
956 } else {
957 __be32 stamp;
958 memcpy(&stamp, p, 4);
959 issue = rxrpc_u32_to_time64(be32_to_cpu(stamp));
960 }
961 p += 4;
962 now = ktime_get_real_seconds();
963 _debug("KIV ISSUE: %llx [%llx]", issue, now);
964
965 /* check the ticket is in date */
966 if (issue > now)
967 return rxrpc_abort_conn(conn, skb, RXKADNOAUTH, -EKEYREJECTED,
968 rxkad_abort_resp_tkt_future);
969 if (issue < now - life)
970 return rxrpc_abort_conn(conn, skb, RXKADEXPIRED, -EKEYEXPIRED,
971 rxkad_abort_resp_tkt_expired);
972
973 *_expiry = issue + life;
974
975 /* get the service name */
976 name = Z(SNAME, sname);
977 _debug("KIV SNAME: %s", name);
978
979 /* get the service instance name */
980 name = Z(INST, sinst);
981 _debug("KIV SINST: %s", name);
982 return 0;
983 }
984
985 /*
986 * decrypt the response packet
987 */
988 static void rxkad_decrypt_response(struct rxrpc_connection *conn,
989 struct rxkad_response *resp,
990 const struct rxrpc_crypt *session_key)
991 {
992 struct skcipher_request *req = rxkad_ci_req;
993 struct scatterlist sg[1];
994 struct rxrpc_crypt iv;
995
996 _enter(",,%08x%08x",
997 ntohl(session_key->n[0]), ntohl(session_key->n[1]));
998
999 mutex_lock(&rxkad_ci_mutex);
1000 if (crypto_sync_skcipher_setkey(rxkad_ci, session_key->x,
1001 sizeof(*session_key)) < 0)
1002 BUG();
1003
1004 memcpy(&iv, session_key, sizeof(iv));
1005
1006 sg_init_table(sg, 1);
1007 sg_set_buf(sg, &resp->encrypted, sizeof(resp->encrypted));
1008 skcipher_request_set_sync_tfm(req, rxkad_ci);
1009 skcipher_request_set_callback(req, 0, NULL, NULL);
1010 skcipher_request_set_crypt(req, sg, sg, sizeof(resp->encrypted), iv.x);
1011 crypto_skcipher_decrypt(req);
1012 skcipher_request_zero(req);
1013
1014 mutex_unlock(&rxkad_ci_mutex);
1015
1016 _leave("");
1017 }
1018
1019 /*
1020 * verify a response
1021 */
1022 static int rxkad_verify_response(struct rxrpc_connection *conn,
1023 struct sk_buff *skb)
1024 {
1025 struct rxkad_response *response;
1026 struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
1027 struct rxrpc_crypt session_key;
1028 struct key *server_key;
1029 time64_t expiry;
1030 void *ticket;
1031 u32 version, kvno, ticket_len, level;
1032 __be32 csum;
1033 int ret, i;
1034
1035 _enter("{%d}", conn->debug_id);
1036
1037 server_key = rxrpc_look_up_server_security(conn, skb, 0, 0);
1038 if (IS_ERR(server_key)) {
1039 ret = PTR_ERR(server_key);
1040 switch (ret) {
1041 case -ENOKEY:
1042 return rxrpc_abort_conn(conn, skb, RXKADUNKNOWNKEY, ret,
1043 rxkad_abort_resp_nokey);
1044 case -EKEYEXPIRED:
1045 return rxrpc_abort_conn(conn, skb, RXKADEXPIRED, ret,
1046 rxkad_abort_resp_key_expired);
1047 default:
1048 return rxrpc_abort_conn(conn, skb, RXKADNOAUTH, ret,
1049 rxkad_abort_resp_key_rejected);
1050 }
1051 }
1052
1053 ret = -ENOMEM;
1054 response = kzalloc(sizeof(struct rxkad_response), GFP_NOFS);
1055 if (!response)
1056 goto temporary_error;
1057
1058 if (skb_copy_bits(skb, sizeof(struct rxrpc_wire_header),
1059 response, sizeof(*response)) < 0) {
1060 rxrpc_abort_conn(conn, skb, RXKADPACKETSHORT, -EPROTO,
1061 rxkad_abort_resp_short);
1062 goto protocol_error;
1063 }
1064
1065 version = ntohl(response->version);
1066 ticket_len = ntohl(response->ticket_len);
1067 kvno = ntohl(response->kvno);
1068
1069 trace_rxrpc_rx_response(conn, sp->hdr.serial, version, kvno, ticket_len);
1070
1071 if (version != RXKAD_VERSION) {
1072 rxrpc_abort_conn(conn, skb, RXKADINCONSISTENCY, -EPROTO,
1073 rxkad_abort_resp_version);
1074 goto protocol_error;
1075 }
1076
1077 if (ticket_len < 4 || ticket_len > MAXKRB5TICKETLEN) {
1078 rxrpc_abort_conn(conn, skb, RXKADTICKETLEN, -EPROTO,
1079 rxkad_abort_resp_tkt_len);
1080 goto protocol_error;
1081 }
1082
1083 if (kvno >= RXKAD_TKT_TYPE_KERBEROS_V5) {
1084 rxrpc_abort_conn(conn, skb, RXKADUNKNOWNKEY, -EPROTO,
1085 rxkad_abort_resp_unknown_tkt);
1086 goto protocol_error;
1087 }
1088
1089 /* extract the kerberos ticket and decrypt and decode it */
1090 ret = -ENOMEM;
1091 ticket = kmalloc(ticket_len, GFP_NOFS);
1092 if (!ticket)
1093 goto temporary_error_free_resp;
1094
1095 if (skb_copy_bits(skb, sizeof(struct rxrpc_wire_header) + sizeof(*response),
1096 ticket, ticket_len) < 0) {
1097 rxrpc_abort_conn(conn, skb, RXKADPACKETSHORT, -EPROTO,
1098 rxkad_abort_resp_short_tkt);
1099 goto protocol_error;
1100 }
1101
1102 ret = rxkad_decrypt_ticket(conn, server_key, skb, ticket, ticket_len,
1103 &session_key, &expiry);
1104 if (ret < 0)
1105 goto temporary_error_free_ticket;
1106
1107 /* use the session key from inside the ticket to decrypt the
1108 * response */
1109 rxkad_decrypt_response(conn, response, &session_key);
1110
1111 if (ntohl(response->encrypted.epoch) != conn->proto.epoch ||
1112 ntohl(response->encrypted.cid) != conn->proto.cid ||
1113 ntohl(response->encrypted.securityIndex) != conn->security_ix) {
1114 rxrpc_abort_conn(conn, skb, RXKADSEALEDINCON, -EPROTO,
1115 rxkad_abort_resp_bad_param);
1116 goto protocol_error_free;
1117 }
1118
1119 csum = response->encrypted.checksum;
1120 response->encrypted.checksum = 0;
1121 rxkad_calc_response_checksum(response);
1122 if (response->encrypted.checksum != csum) {
1123 rxrpc_abort_conn(conn, skb, RXKADSEALEDINCON, -EPROTO,
1124 rxkad_abort_resp_bad_checksum);
1125 goto protocol_error_free;
1126 }
1127
1128 for (i = 0; i < RXRPC_MAXCALLS; i++) {
1129 u32 call_id = ntohl(response->encrypted.call_id[i]);
1130 u32 counter = READ_ONCE(conn->channels[i].call_counter);
1131
1132 if (call_id > INT_MAX) {
1133 rxrpc_abort_conn(conn, skb, RXKADSEALEDINCON, -EPROTO,
1134 rxkad_abort_resp_bad_callid);
1135 goto protocol_error_free;
1136 }
1137
1138 if (call_id < counter) {
1139 rxrpc_abort_conn(conn, skb, RXKADSEALEDINCON, -EPROTO,
1140 rxkad_abort_resp_call_ctr);
1141 goto protocol_error_free;
1142 }
1143
1144 if (call_id > counter) {
1145 if (conn->channels[i].call) {
1146 rxrpc_abort_conn(conn, skb, RXKADSEALEDINCON, -EPROTO,
1147 rxkad_abort_resp_call_state);
1148 goto protocol_error_free;
1149 }
1150 conn->channels[i].call_counter = call_id;
1151 }
1152 }
1153
1154 if (ntohl(response->encrypted.inc_nonce) != conn->rxkad.nonce + 1) {
1155 rxrpc_abort_conn(conn, skb, RXKADOUTOFSEQUENCE, -EPROTO,
1156 rxkad_abort_resp_ooseq);
1157 goto protocol_error_free;
1158 }
1159
1160 level = ntohl(response->encrypted.level);
1161 if (level > RXRPC_SECURITY_ENCRYPT) {
1162 rxrpc_abort_conn(conn, skb, RXKADLEVELFAIL, -EPROTO,
1163 rxkad_abort_resp_level);
1164 goto protocol_error_free;
1165 }
1166 conn->security_level = level;
1167
1168 /* create a key to hold the security data and expiration time - after
1169 * this the connection security can be handled in exactly the same way
1170 * as for a client connection */
1171 ret = rxrpc_get_server_data_key(conn, &session_key, expiry, kvno);
1172 if (ret < 0)
1173 goto temporary_error_free_ticket;
1174
1175 kfree(ticket);
1176 kfree(response);
1177 _leave(" = 0");
1178 return 0;
1179
1180 protocol_error_free:
1181 kfree(ticket);
1182 protocol_error:
1183 kfree(response);
1184 key_put(server_key);
1185 return -EPROTO;
1186
1187 temporary_error_free_ticket:
1188 kfree(ticket);
1189 temporary_error_free_resp:
1190 kfree(response);
1191 temporary_error:
1192 /* Ignore the response packet if we got a temporary error such as
1193 * ENOMEM. We just want to send the challenge again. Note that we
1194 * also come out this way if the ticket decryption fails.
1195 */
1196 key_put(server_key);
1197 return ret;
1198 }
1199
1200 /*
1201 * clear the connection security
1202 */
1203 static void rxkad_clear(struct rxrpc_connection *conn)
1204 {
1205 _enter("");
1206
1207 if (conn->rxkad.cipher)
1208 crypto_free_sync_skcipher(conn->rxkad.cipher);
1209 }
1210
1211 /*
1212 * Initialise the rxkad security service.
1213 */
1214 static int rxkad_init(void)
1215 {
1216 struct crypto_sync_skcipher *tfm;
1217 struct skcipher_request *req;
1218
1219 /* pin the cipher we need so that the crypto layer doesn't invoke
1220 * keventd to go get it */
1221 tfm = crypto_alloc_sync_skcipher("pcbc(fcrypt)", 0, 0);
1222 if (IS_ERR(tfm))
1223 return PTR_ERR(tfm);
1224
1225 req = skcipher_request_alloc(&tfm->base, GFP_KERNEL);
1226 if (!req)
1227 goto nomem_tfm;
1228
1229 rxkad_ci_req = req;
1230 rxkad_ci = tfm;
1231 return 0;
1232
1233 nomem_tfm:
1234 crypto_free_sync_skcipher(tfm);
1235 return -ENOMEM;
1236 }
1237
1238 /*
1239 * Clean up the rxkad security service.
1240 */
1241 static void rxkad_exit(void)
1242 {
1243 crypto_free_sync_skcipher(rxkad_ci);
1244 skcipher_request_free(rxkad_ci_req);
1245 }
1246
1247 /*
1248 * RxRPC Kerberos-based security
1249 */
1250 const struct rxrpc_security rxkad = {
1251 .name = "rxkad",
1252 .security_index = RXRPC_SECURITY_RXKAD,
1253 .no_key_abort = RXKADUNKNOWNKEY,
1254 .init = rxkad_init,
1255 .exit = rxkad_exit,
1256 .preparse_server_key = rxkad_preparse_server_key,
1257 .free_preparse_server_key = rxkad_free_preparse_server_key,
1258 .destroy_server_key = rxkad_destroy_server_key,
1259 .init_connection_security = rxkad_init_connection_security,
1260 .alloc_txbuf = rxkad_alloc_txbuf,
1261 .secure_packet = rxkad_secure_packet,
1262 .verify_packet = rxkad_verify_packet,
1263 .free_call_crypto = rxkad_free_call_crypto,
1264 .issue_challenge = rxkad_issue_challenge,
1265 .respond_to_challenge = rxkad_respond_to_challenge,
1266 .verify_response = rxkad_verify_response,
1267 .clear = rxkad_clear,
1268 };
1269
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