Loading...
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
33struct rxkad_level1_hdr {
34 __be32 data_size; /* true data size (excluding padding) */
35};
36
37struct rxkad_level2_hdr {
38 __be32 data_size; /* true data size (excluding padding) */
39 __be32 checksum; /* decrypted data checksum */
40};
41
42static 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 */
50static struct crypto_sync_skcipher *rxkad_ci;
51static struct skcipher_request *rxkad_ci_req;
52static 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 */
59static 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
82static 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
89static 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 */
100static 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
138error_ci:
139 crypto_free_sync_skcipher(ci);
140error:
141 _leave(" = %d", ret);
142 return ret;
143}
144
145/*
146 * Work out how much data we can put in a packet.
147 */
148static 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
172out:
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 */
183static 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 */
233static 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 */
243static void rxkad_free_call_crypto(struct rxrpc_call *call)
244{
245}
246
247/*
248 * partially encrypt a packet (level 1 security)
249 */
250static 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 ^ ntohl(txb->wire.callNumber);
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 */
291static 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 ^ ntohl(txb->wire.callNumber);
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 */
335static 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 = (ntohl(txb->wire.cid) & RXRPC_CHANNELMASK) << (32 - RXRPC_CIDSHIFT);
366 x |= txb->seq & 0x3fffffff;
367 crypto.buf[0] = txb->wire.callNumber;
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 */
406static 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 */
469static 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 */
550static 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
616out:
617 skcipher_request_free(req);
618 return ret;
619}
620
621/*
622 * issue a challenge
623 */
624static 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 = atomic_inc_return(&conn->serial);
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 */
687static 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 = atomic_inc_return(&conn->serial);
725 whdr.serial = htonl(serial);
726
727 ret = kernel_sendmsg(conn->local->socket, &msg, iov, 3, len);
728 if (ret < 0) {
729 trace_rxrpc_tx_fail(conn->debug_id, serial, ret,
730 rxrpc_tx_point_rxkad_response);
731 return -EAGAIN;
732 }
733
734 conn->peer->last_tx_at = ktime_get_seconds();
735 _leave(" = 0");
736 return 0;
737}
738
739/*
740 * calculate the response checksum
741 */
742static void rxkad_calc_response_checksum(struct rxkad_response *response)
743{
744 u32 csum = 1000003;
745 int loop;
746 u8 *p = (u8 *) response;
747
748 for (loop = sizeof(*response); loop > 0; loop--)
749 csum = csum * 0x10204081 + *p++;
750
751 response->encrypted.checksum = htonl(csum);
752}
753
754/*
755 * encrypt the response packet
756 */
757static int rxkad_encrypt_response(struct rxrpc_connection *conn,
758 struct rxkad_response *resp,
759 const struct rxkad_key *s2)
760{
761 struct skcipher_request *req;
762 struct rxrpc_crypt iv;
763 struct scatterlist sg[1];
764
765 req = skcipher_request_alloc(&conn->rxkad.cipher->base, GFP_NOFS);
766 if (!req)
767 return -ENOMEM;
768
769 /* continue encrypting from where we left off */
770 memcpy(&iv, s2->session_key, sizeof(iv));
771
772 sg_init_table(sg, 1);
773 sg_set_buf(sg, &resp->encrypted, sizeof(resp->encrypted));
774 skcipher_request_set_sync_tfm(req, conn->rxkad.cipher);
775 skcipher_request_set_callback(req, 0, NULL, NULL);
776 skcipher_request_set_crypt(req, sg, sg, sizeof(resp->encrypted), iv.x);
777 crypto_skcipher_encrypt(req);
778 skcipher_request_free(req);
779 return 0;
780}
781
782/*
783 * respond to a challenge packet
784 */
785static int rxkad_respond_to_challenge(struct rxrpc_connection *conn,
786 struct sk_buff *skb)
787{
788 const struct rxrpc_key_token *token;
789 struct rxkad_challenge challenge;
790 struct rxkad_response *resp;
791 struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
792 u32 version, nonce, min_level;
793 int ret = -EPROTO;
794
795 _enter("{%d,%x}", conn->debug_id, key_serial(conn->key));
796
797 if (!conn->key)
798 return rxrpc_abort_conn(conn, skb, RX_PROTOCOL_ERROR, -EPROTO,
799 rxkad_abort_chall_no_key);
800
801 ret = key_validate(conn->key);
802 if (ret < 0)
803 return rxrpc_abort_conn(conn, skb, RXKADEXPIRED, ret,
804 rxkad_abort_chall_key_expired);
805
806 if (skb_copy_bits(skb, sizeof(struct rxrpc_wire_header),
807 &challenge, sizeof(challenge)) < 0)
808 return rxrpc_abort_conn(conn, skb, RXKADPACKETSHORT, -EPROTO,
809 rxkad_abort_chall_short);
810
811 version = ntohl(challenge.version);
812 nonce = ntohl(challenge.nonce);
813 min_level = ntohl(challenge.min_level);
814
815 trace_rxrpc_rx_challenge(conn, sp->hdr.serial, version, nonce, min_level);
816
817 if (version != RXKAD_VERSION)
818 return rxrpc_abort_conn(conn, skb, RXKADINCONSISTENCY, -EPROTO,
819 rxkad_abort_chall_version);
820
821 if (conn->security_level < min_level)
822 return rxrpc_abort_conn(conn, skb, RXKADLEVELFAIL, -EACCES,
823 rxkad_abort_chall_level);
824
825 token = conn->key->payload.data[0];
826
827 /* build the response packet */
828 resp = kzalloc(sizeof(struct rxkad_response), GFP_NOFS);
829 if (!resp)
830 return -ENOMEM;
831
832 resp->version = htonl(RXKAD_VERSION);
833 resp->encrypted.epoch = htonl(conn->proto.epoch);
834 resp->encrypted.cid = htonl(conn->proto.cid);
835 resp->encrypted.securityIndex = htonl(conn->security_ix);
836 resp->encrypted.inc_nonce = htonl(nonce + 1);
837 resp->encrypted.level = htonl(conn->security_level);
838 resp->kvno = htonl(token->kad->kvno);
839 resp->ticket_len = htonl(token->kad->ticket_len);
840 resp->encrypted.call_id[0] = htonl(conn->channels[0].call_counter);
841 resp->encrypted.call_id[1] = htonl(conn->channels[1].call_counter);
842 resp->encrypted.call_id[2] = htonl(conn->channels[2].call_counter);
843 resp->encrypted.call_id[3] = htonl(conn->channels[3].call_counter);
844
845 /* calculate the response checksum and then do the encryption */
846 rxkad_calc_response_checksum(resp);
847 ret = rxkad_encrypt_response(conn, resp, token->kad);
848 if (ret == 0)
849 ret = rxkad_send_response(conn, &sp->hdr, resp, token->kad);
850 kfree(resp);
851 return ret;
852}
853
854/*
855 * decrypt the kerberos IV ticket in the response
856 */
857static int rxkad_decrypt_ticket(struct rxrpc_connection *conn,
858 struct key *server_key,
859 struct sk_buff *skb,
860 void *ticket, size_t ticket_len,
861 struct rxrpc_crypt *_session_key,
862 time64_t *_expiry)
863{
864 struct skcipher_request *req;
865 struct rxrpc_crypt iv, key;
866 struct scatterlist sg[1];
867 struct in_addr addr;
868 unsigned int life;
869 time64_t issue, now;
870 bool little_endian;
871 u8 *p, *q, *name, *end;
872
873 _enter("{%d},{%x}", conn->debug_id, key_serial(server_key));
874
875 *_expiry = 0;
876
877 ASSERT(server_key->payload.data[0] != NULL);
878 ASSERTCMP((unsigned long) ticket & 7UL, ==, 0);
879
880 memcpy(&iv, &server_key->payload.data[2], sizeof(iv));
881
882 req = skcipher_request_alloc(server_key->payload.data[0], GFP_NOFS);
883 if (!req)
884 return -ENOMEM;
885
886 sg_init_one(&sg[0], ticket, ticket_len);
887 skcipher_request_set_callback(req, 0, NULL, NULL);
888 skcipher_request_set_crypt(req, sg, sg, ticket_len, iv.x);
889 crypto_skcipher_decrypt(req);
890 skcipher_request_free(req);
891
892 p = ticket;
893 end = p + ticket_len;
894
895#define Z(field, fieldl) \
896 ({ \
897 u8 *__str = p; \
898 q = memchr(p, 0, end - p); \
899 if (!q || q - p > field##_SZ) \
900 return rxrpc_abort_conn( \
901 conn, skb, RXKADBADTICKET, -EPROTO, \
902 rxkad_abort_resp_tkt_##fieldl); \
903 for (; p < q; p++) \
904 if (!isprint(*p)) \
905 return rxrpc_abort_conn( \
906 conn, skb, RXKADBADTICKET, -EPROTO, \
907 rxkad_abort_resp_tkt_##fieldl); \
908 p++; \
909 __str; \
910 })
911
912 /* extract the ticket flags */
913 _debug("KIV FLAGS: %x", *p);
914 little_endian = *p & 1;
915 p++;
916
917 /* extract the authentication name */
918 name = Z(ANAME, aname);
919 _debug("KIV ANAME: %s", name);
920
921 /* extract the principal's instance */
922 name = Z(INST, inst);
923 _debug("KIV INST : %s", name);
924
925 /* extract the principal's authentication domain */
926 name = Z(REALM, realm);
927 _debug("KIV REALM: %s", name);
928
929 if (end - p < 4 + 8 + 4 + 2)
930 return rxrpc_abort_conn(conn, skb, RXKADBADTICKET, -EPROTO,
931 rxkad_abort_resp_tkt_short);
932
933 /* get the IPv4 address of the entity that requested the ticket */
934 memcpy(&addr, p, sizeof(addr));
935 p += 4;
936 _debug("KIV ADDR : %pI4", &addr);
937
938 /* get the session key from the ticket */
939 memcpy(&key, p, sizeof(key));
940 p += 8;
941 _debug("KIV KEY : %08x %08x", ntohl(key.n[0]), ntohl(key.n[1]));
942 memcpy(_session_key, &key, sizeof(key));
943
944 /* get the ticket's lifetime */
945 life = *p++ * 5 * 60;
946 _debug("KIV LIFE : %u", life);
947
948 /* get the issue time of the ticket */
949 if (little_endian) {
950 __le32 stamp;
951 memcpy(&stamp, p, 4);
952 issue = rxrpc_u32_to_time64(le32_to_cpu(stamp));
953 } else {
954 __be32 stamp;
955 memcpy(&stamp, p, 4);
956 issue = rxrpc_u32_to_time64(be32_to_cpu(stamp));
957 }
958 p += 4;
959 now = ktime_get_real_seconds();
960 _debug("KIV ISSUE: %llx [%llx]", issue, now);
961
962 /* check the ticket is in date */
963 if (issue > now)
964 return rxrpc_abort_conn(conn, skb, RXKADNOAUTH, -EKEYREJECTED,
965 rxkad_abort_resp_tkt_future);
966 if (issue < now - life)
967 return rxrpc_abort_conn(conn, skb, RXKADEXPIRED, -EKEYEXPIRED,
968 rxkad_abort_resp_tkt_expired);
969
970 *_expiry = issue + life;
971
972 /* get the service name */
973 name = Z(SNAME, sname);
974 _debug("KIV SNAME: %s", name);
975
976 /* get the service instance name */
977 name = Z(INST, sinst);
978 _debug("KIV SINST: %s", name);
979 return 0;
980}
981
982/*
983 * decrypt the response packet
984 */
985static void rxkad_decrypt_response(struct rxrpc_connection *conn,
986 struct rxkad_response *resp,
987 const struct rxrpc_crypt *session_key)
988{
989 struct skcipher_request *req = rxkad_ci_req;
990 struct scatterlist sg[1];
991 struct rxrpc_crypt iv;
992
993 _enter(",,%08x%08x",
994 ntohl(session_key->n[0]), ntohl(session_key->n[1]));
995
996 mutex_lock(&rxkad_ci_mutex);
997 if (crypto_sync_skcipher_setkey(rxkad_ci, session_key->x,
998 sizeof(*session_key)) < 0)
999 BUG();
1000
1001 memcpy(&iv, session_key, sizeof(iv));
1002
1003 sg_init_table(sg, 1);
1004 sg_set_buf(sg, &resp->encrypted, sizeof(resp->encrypted));
1005 skcipher_request_set_sync_tfm(req, rxkad_ci);
1006 skcipher_request_set_callback(req, 0, NULL, NULL);
1007 skcipher_request_set_crypt(req, sg, sg, sizeof(resp->encrypted), iv.x);
1008 crypto_skcipher_decrypt(req);
1009 skcipher_request_zero(req);
1010
1011 mutex_unlock(&rxkad_ci_mutex);
1012
1013 _leave("");
1014}
1015
1016/*
1017 * verify a response
1018 */
1019static int rxkad_verify_response(struct rxrpc_connection *conn,
1020 struct sk_buff *skb)
1021{
1022 struct rxkad_response *response;
1023 struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
1024 struct rxrpc_crypt session_key;
1025 struct key *server_key;
1026 time64_t expiry;
1027 void *ticket;
1028 u32 version, kvno, ticket_len, level;
1029 __be32 csum;
1030 int ret, i;
1031
1032 _enter("{%d}", conn->debug_id);
1033
1034 server_key = rxrpc_look_up_server_security(conn, skb, 0, 0);
1035 if (IS_ERR(server_key)) {
1036 ret = PTR_ERR(server_key);
1037 switch (ret) {
1038 case -ENOKEY:
1039 return rxrpc_abort_conn(conn, skb, RXKADUNKNOWNKEY, ret,
1040 rxkad_abort_resp_nokey);
1041 case -EKEYEXPIRED:
1042 return rxrpc_abort_conn(conn, skb, RXKADEXPIRED, ret,
1043 rxkad_abort_resp_key_expired);
1044 default:
1045 return rxrpc_abort_conn(conn, skb, RXKADNOAUTH, ret,
1046 rxkad_abort_resp_key_rejected);
1047 }
1048 }
1049
1050 ret = -ENOMEM;
1051 response = kzalloc(sizeof(struct rxkad_response), GFP_NOFS);
1052 if (!response)
1053 goto temporary_error;
1054
1055 if (skb_copy_bits(skb, sizeof(struct rxrpc_wire_header),
1056 response, sizeof(*response)) < 0) {
1057 rxrpc_abort_conn(conn, skb, RXKADPACKETSHORT, -EPROTO,
1058 rxkad_abort_resp_short);
1059 goto protocol_error;
1060 }
1061
1062 version = ntohl(response->version);
1063 ticket_len = ntohl(response->ticket_len);
1064 kvno = ntohl(response->kvno);
1065
1066 trace_rxrpc_rx_response(conn, sp->hdr.serial, version, kvno, ticket_len);
1067
1068 if (version != RXKAD_VERSION) {
1069 rxrpc_abort_conn(conn, skb, RXKADINCONSISTENCY, -EPROTO,
1070 rxkad_abort_resp_version);
1071 goto protocol_error;
1072 }
1073
1074 if (ticket_len < 4 || ticket_len > MAXKRB5TICKETLEN) {
1075 rxrpc_abort_conn(conn, skb, RXKADTICKETLEN, -EPROTO,
1076 rxkad_abort_resp_tkt_len);
1077 goto protocol_error;
1078 }
1079
1080 if (kvno >= RXKAD_TKT_TYPE_KERBEROS_V5) {
1081 rxrpc_abort_conn(conn, skb, RXKADUNKNOWNKEY, -EPROTO,
1082 rxkad_abort_resp_unknown_tkt);
1083 goto protocol_error;
1084 }
1085
1086 /* extract the kerberos ticket and decrypt and decode it */
1087 ret = -ENOMEM;
1088 ticket = kmalloc(ticket_len, GFP_NOFS);
1089 if (!ticket)
1090 goto temporary_error_free_resp;
1091
1092 if (skb_copy_bits(skb, sizeof(struct rxrpc_wire_header) + sizeof(*response),
1093 ticket, ticket_len) < 0) {
1094 rxrpc_abort_conn(conn, skb, RXKADPACKETSHORT, -EPROTO,
1095 rxkad_abort_resp_short_tkt);
1096 goto protocol_error;
1097 }
1098
1099 ret = rxkad_decrypt_ticket(conn, server_key, skb, ticket, ticket_len,
1100 &session_key, &expiry);
1101 if (ret < 0)
1102 goto temporary_error_free_ticket;
1103
1104 /* use the session key from inside the ticket to decrypt the
1105 * response */
1106 rxkad_decrypt_response(conn, response, &session_key);
1107
1108 if (ntohl(response->encrypted.epoch) != conn->proto.epoch ||
1109 ntohl(response->encrypted.cid) != conn->proto.cid ||
1110 ntohl(response->encrypted.securityIndex) != conn->security_ix) {
1111 rxrpc_abort_conn(conn, skb, RXKADSEALEDINCON, -EPROTO,
1112 rxkad_abort_resp_bad_param);
1113 goto protocol_error_free;
1114 }
1115
1116 csum = response->encrypted.checksum;
1117 response->encrypted.checksum = 0;
1118 rxkad_calc_response_checksum(response);
1119 if (response->encrypted.checksum != csum) {
1120 rxrpc_abort_conn(conn, skb, RXKADSEALEDINCON, -EPROTO,
1121 rxkad_abort_resp_bad_checksum);
1122 goto protocol_error_free;
1123 }
1124
1125 for (i = 0; i < RXRPC_MAXCALLS; i++) {
1126 u32 call_id = ntohl(response->encrypted.call_id[i]);
1127 u32 counter = READ_ONCE(conn->channels[i].call_counter);
1128
1129 if (call_id > INT_MAX) {
1130 rxrpc_abort_conn(conn, skb, RXKADSEALEDINCON, -EPROTO,
1131 rxkad_abort_resp_bad_callid);
1132 goto protocol_error_free;
1133 }
1134
1135 if (call_id < counter) {
1136 rxrpc_abort_conn(conn, skb, RXKADSEALEDINCON, -EPROTO,
1137 rxkad_abort_resp_call_ctr);
1138 goto protocol_error_free;
1139 }
1140
1141 if (call_id > counter) {
1142 if (conn->channels[i].call) {
1143 rxrpc_abort_conn(conn, skb, RXKADSEALEDINCON, -EPROTO,
1144 rxkad_abort_resp_call_state);
1145 goto protocol_error_free;
1146 }
1147 conn->channels[i].call_counter = call_id;
1148 }
1149 }
1150
1151 if (ntohl(response->encrypted.inc_nonce) != conn->rxkad.nonce + 1) {
1152 rxrpc_abort_conn(conn, skb, RXKADOUTOFSEQUENCE, -EPROTO,
1153 rxkad_abort_resp_ooseq);
1154 goto protocol_error_free;
1155 }
1156
1157 level = ntohl(response->encrypted.level);
1158 if (level > RXRPC_SECURITY_ENCRYPT) {
1159 rxrpc_abort_conn(conn, skb, RXKADLEVELFAIL, -EPROTO,
1160 rxkad_abort_resp_level);
1161 goto protocol_error_free;
1162 }
1163 conn->security_level = level;
1164
1165 /* create a key to hold the security data and expiration time - after
1166 * this the connection security can be handled in exactly the same way
1167 * as for a client connection */
1168 ret = rxrpc_get_server_data_key(conn, &session_key, expiry, kvno);
1169 if (ret < 0)
1170 goto temporary_error_free_ticket;
1171
1172 kfree(ticket);
1173 kfree(response);
1174 _leave(" = 0");
1175 return 0;
1176
1177protocol_error_free:
1178 kfree(ticket);
1179protocol_error:
1180 kfree(response);
1181 key_put(server_key);
1182 return -EPROTO;
1183
1184temporary_error_free_ticket:
1185 kfree(ticket);
1186temporary_error_free_resp:
1187 kfree(response);
1188temporary_error:
1189 /* Ignore the response packet if we got a temporary error such as
1190 * ENOMEM. We just want to send the challenge again. Note that we
1191 * also come out this way if the ticket decryption fails.
1192 */
1193 key_put(server_key);
1194 return ret;
1195}
1196
1197/*
1198 * clear the connection security
1199 */
1200static void rxkad_clear(struct rxrpc_connection *conn)
1201{
1202 _enter("");
1203
1204 if (conn->rxkad.cipher)
1205 crypto_free_sync_skcipher(conn->rxkad.cipher);
1206}
1207
1208/*
1209 * Initialise the rxkad security service.
1210 */
1211static int rxkad_init(void)
1212{
1213 struct crypto_sync_skcipher *tfm;
1214 struct skcipher_request *req;
1215
1216 /* pin the cipher we need so that the crypto layer doesn't invoke
1217 * keventd to go get it */
1218 tfm = crypto_alloc_sync_skcipher("pcbc(fcrypt)", 0, 0);
1219 if (IS_ERR(tfm))
1220 return PTR_ERR(tfm);
1221
1222 req = skcipher_request_alloc(&tfm->base, GFP_KERNEL);
1223 if (!req)
1224 goto nomem_tfm;
1225
1226 rxkad_ci_req = req;
1227 rxkad_ci = tfm;
1228 return 0;
1229
1230nomem_tfm:
1231 crypto_free_sync_skcipher(tfm);
1232 return -ENOMEM;
1233}
1234
1235/*
1236 * Clean up the rxkad security service.
1237 */
1238static void rxkad_exit(void)
1239{
1240 crypto_free_sync_skcipher(rxkad_ci);
1241 skcipher_request_free(rxkad_ci_req);
1242}
1243
1244/*
1245 * RxRPC Kerberos-based security
1246 */
1247const struct rxrpc_security rxkad = {
1248 .name = "rxkad",
1249 .security_index = RXRPC_SECURITY_RXKAD,
1250 .no_key_abort = RXKADUNKNOWNKEY,
1251 .init = rxkad_init,
1252 .exit = rxkad_exit,
1253 .preparse_server_key = rxkad_preparse_server_key,
1254 .free_preparse_server_key = rxkad_free_preparse_server_key,
1255 .destroy_server_key = rxkad_destroy_server_key,
1256 .init_connection_security = rxkad_init_connection_security,
1257 .how_much_data = rxkad_how_much_data,
1258 .secure_packet = rxkad_secure_packet,
1259 .verify_packet = rxkad_verify_packet,
1260 .free_call_crypto = rxkad_free_call_crypto,
1261 .issue_challenge = rxkad_issue_challenge,
1262 .respond_to_challenge = rxkad_respond_to_challenge,
1263 .verify_response = rxkad_verify_response,
1264 .clear = rxkad_clear,
1265};
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
33struct rxkad_level1_hdr {
34 __be32 data_size; /* true data size (excluding padding) */
35};
36
37struct rxkad_level2_hdr {
38 __be32 data_size; /* true data size (excluding padding) */
39 __be32 checksum; /* decrypted data checksum */
40};
41
42static 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 */
50static struct crypto_sync_skcipher *rxkad_ci;
51static struct skcipher_request *rxkad_ci_req;
52static 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 */
59static 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
82static 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
89static 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 */
100static 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
138error_ci:
139 crypto_free_sync_skcipher(ci);
140error:
141 _leave(" = %d", ret);
142 return ret;
143}
144
145/*
146 * Work out how much data we can put in a packet.
147 */
148static 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 */
183static 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 */
233static 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 */
243static void rxkad_free_call_crypto(struct rxrpc_call *call)
244{
245}
246
247/*
248 * partially encrypt a packet (level 1 security)
249 */
250static 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 */
292static 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 */
337static 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 */
408static 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 */
471static 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 */
552static 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
618out:
619 skcipher_request_free(req);
620 return ret;
621}
622
623/*
624 * issue a challenge
625 */
626static 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 */
689static 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 */
745static 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 */
760static 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 */
788static 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 */
860static 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 */
988static 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 */
1022static 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
1180protocol_error_free:
1181 kfree(ticket);
1182protocol_error:
1183 kfree(response);
1184 key_put(server_key);
1185 return -EPROTO;
1186
1187temporary_error_free_ticket:
1188 kfree(ticket);
1189temporary_error_free_resp:
1190 kfree(response);
1191temporary_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 */
1203static 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 */
1214static 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
1233nomem_tfm:
1234 crypto_free_sync_skcipher(tfm);
1235 return -ENOMEM;
1236}
1237
1238/*
1239 * Clean up the rxkad security service.
1240 */
1241static 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 */
1250const 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};