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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 <net/sock.h>
19#include <net/af_rxrpc.h>
20#include <keys/rxrpc-type.h>
21#include "ar-internal.h"
22
23#define RXKAD_VERSION 2
24#define MAXKRB5TICKETLEN 1024
25#define RXKAD_TKT_TYPE_KERBEROS_V5 256
26#define ANAME_SZ 40 /* size of authentication name */
27#define INST_SZ 40 /* size of principal's instance */
28#define REALM_SZ 40 /* size of principal's auth domain */
29#define SNAME_SZ 40 /* size of service name */
30
31struct rxkad_level1_hdr {
32 __be32 data_size; /* true data size (excluding padding) */
33};
34
35struct rxkad_level2_hdr {
36 __be32 data_size; /* true data size (excluding padding) */
37 __be32 checksum; /* decrypted data checksum */
38};
39
40/*
41 * this holds a pinned cipher so that keventd doesn't get called by the cipher
42 * alloc routine, but since we have it to hand, we use it to decrypt RESPONSE
43 * packets
44 */
45static struct crypto_sync_skcipher *rxkad_ci;
46static struct skcipher_request *rxkad_ci_req;
47static DEFINE_MUTEX(rxkad_ci_mutex);
48
49/*
50 * initialise connection security
51 */
52static int rxkad_init_connection_security(struct rxrpc_connection *conn)
53{
54 struct crypto_sync_skcipher *ci;
55 struct rxrpc_key_token *token;
56 int ret;
57
58 _enter("{%d},{%x}", conn->debug_id, key_serial(conn->params.key));
59
60 token = conn->params.key->payload.data[0];
61 conn->security_ix = token->security_index;
62
63 ci = crypto_alloc_sync_skcipher("pcbc(fcrypt)", 0, 0);
64 if (IS_ERR(ci)) {
65 _debug("no cipher");
66 ret = PTR_ERR(ci);
67 goto error;
68 }
69
70 if (crypto_sync_skcipher_setkey(ci, token->kad->session_key,
71 sizeof(token->kad->session_key)) < 0)
72 BUG();
73
74 switch (conn->params.security_level) {
75 case RXRPC_SECURITY_PLAIN:
76 break;
77 case RXRPC_SECURITY_AUTH:
78 conn->size_align = 8;
79 conn->security_size = sizeof(struct rxkad_level1_hdr);
80 break;
81 case RXRPC_SECURITY_ENCRYPT:
82 conn->size_align = 8;
83 conn->security_size = sizeof(struct rxkad_level2_hdr);
84 break;
85 default:
86 ret = -EKEYREJECTED;
87 goto error;
88 }
89
90 conn->cipher = ci;
91 ret = 0;
92error:
93 _leave(" = %d", ret);
94 return ret;
95}
96
97/*
98 * prime the encryption state with the invariant parts of a connection's
99 * description
100 */
101static int rxkad_prime_packet_security(struct rxrpc_connection *conn)
102{
103 struct skcipher_request *req;
104 struct rxrpc_key_token *token;
105 struct scatterlist sg;
106 struct rxrpc_crypt iv;
107 __be32 *tmpbuf;
108 size_t tmpsize = 4 * sizeof(__be32);
109
110 _enter("");
111
112 if (!conn->params.key)
113 return 0;
114
115 tmpbuf = kmalloc(tmpsize, GFP_KERNEL);
116 if (!tmpbuf)
117 return -ENOMEM;
118
119 req = skcipher_request_alloc(&conn->cipher->base, GFP_NOFS);
120 if (!req) {
121 kfree(tmpbuf);
122 return -ENOMEM;
123 }
124
125 token = conn->params.key->payload.data[0];
126 memcpy(&iv, token->kad->session_key, sizeof(iv));
127
128 tmpbuf[0] = htonl(conn->proto.epoch);
129 tmpbuf[1] = htonl(conn->proto.cid);
130 tmpbuf[2] = 0;
131 tmpbuf[3] = htonl(conn->security_ix);
132
133 sg_init_one(&sg, tmpbuf, tmpsize);
134 skcipher_request_set_sync_tfm(req, conn->cipher);
135 skcipher_request_set_callback(req, 0, NULL, NULL);
136 skcipher_request_set_crypt(req, &sg, &sg, tmpsize, iv.x);
137 crypto_skcipher_encrypt(req);
138 skcipher_request_free(req);
139
140 memcpy(&conn->csum_iv, tmpbuf + 2, sizeof(conn->csum_iv));
141 kfree(tmpbuf);
142 _leave(" = 0");
143 return 0;
144}
145
146/*
147 * Allocate and prepare the crypto request on a call. For any particular call,
148 * this is called serially for the packets, so no lock should be necessary.
149 */
150static struct skcipher_request *rxkad_get_call_crypto(struct rxrpc_call *call)
151{
152 struct crypto_skcipher *tfm = &call->conn->cipher->base;
153 struct skcipher_request *cipher_req = call->cipher_req;
154
155 if (!cipher_req) {
156 cipher_req = skcipher_request_alloc(tfm, GFP_NOFS);
157 if (!cipher_req)
158 return NULL;
159 call->cipher_req = cipher_req;
160 }
161
162 return cipher_req;
163}
164
165/*
166 * Clean up the crypto on a call.
167 */
168static void rxkad_free_call_crypto(struct rxrpc_call *call)
169{
170 if (call->cipher_req)
171 skcipher_request_free(call->cipher_req);
172 call->cipher_req = NULL;
173}
174
175/*
176 * partially encrypt a packet (level 1 security)
177 */
178static int rxkad_secure_packet_auth(const struct rxrpc_call *call,
179 struct sk_buff *skb,
180 u32 data_size,
181 void *sechdr,
182 struct skcipher_request *req)
183{
184 struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
185 struct rxkad_level1_hdr hdr;
186 struct rxrpc_crypt iv;
187 struct scatterlist sg;
188 u16 check;
189
190 _enter("");
191
192 check = sp->hdr.seq ^ call->call_id;
193 data_size |= (u32)check << 16;
194
195 hdr.data_size = htonl(data_size);
196 memcpy(sechdr, &hdr, sizeof(hdr));
197
198 /* start the encryption afresh */
199 memset(&iv, 0, sizeof(iv));
200
201 sg_init_one(&sg, sechdr, 8);
202 skcipher_request_set_sync_tfm(req, call->conn->cipher);
203 skcipher_request_set_callback(req, 0, NULL, NULL);
204 skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x);
205 crypto_skcipher_encrypt(req);
206 skcipher_request_zero(req);
207
208 _leave(" = 0");
209 return 0;
210}
211
212/*
213 * wholly encrypt a packet (level 2 security)
214 */
215static int rxkad_secure_packet_encrypt(const struct rxrpc_call *call,
216 struct sk_buff *skb,
217 u32 data_size,
218 void *sechdr,
219 struct skcipher_request *req)
220{
221 const struct rxrpc_key_token *token;
222 struct rxkad_level2_hdr rxkhdr;
223 struct rxrpc_skb_priv *sp;
224 struct rxrpc_crypt iv;
225 struct scatterlist sg[16];
226 unsigned int len;
227 u16 check;
228 int err;
229
230 sp = rxrpc_skb(skb);
231
232 _enter("");
233
234 check = sp->hdr.seq ^ call->call_id;
235
236 rxkhdr.data_size = htonl(data_size | (u32)check << 16);
237 rxkhdr.checksum = 0;
238 memcpy(sechdr, &rxkhdr, sizeof(rxkhdr));
239
240 /* encrypt from the session key */
241 token = call->conn->params.key->payload.data[0];
242 memcpy(&iv, token->kad->session_key, sizeof(iv));
243
244 sg_init_one(&sg[0], sechdr, sizeof(rxkhdr));
245 skcipher_request_set_sync_tfm(req, call->conn->cipher);
246 skcipher_request_set_callback(req, 0, NULL, NULL);
247 skcipher_request_set_crypt(req, &sg[0], &sg[0], sizeof(rxkhdr), iv.x);
248 crypto_skcipher_encrypt(req);
249
250 /* we want to encrypt the skbuff in-place */
251 err = -EMSGSIZE;
252 if (skb_shinfo(skb)->nr_frags > 16)
253 goto out;
254
255 len = data_size + call->conn->size_align - 1;
256 len &= ~(call->conn->size_align - 1);
257
258 sg_init_table(sg, ARRAY_SIZE(sg));
259 err = skb_to_sgvec(skb, sg, 0, len);
260 if (unlikely(err < 0))
261 goto out;
262 skcipher_request_set_crypt(req, sg, sg, len, iv.x);
263 crypto_skcipher_encrypt(req);
264
265 _leave(" = 0");
266 err = 0;
267
268out:
269 skcipher_request_zero(req);
270 return err;
271}
272
273/*
274 * checksum an RxRPC packet header
275 */
276static int rxkad_secure_packet(struct rxrpc_call *call,
277 struct sk_buff *skb,
278 size_t data_size,
279 void *sechdr)
280{
281 struct rxrpc_skb_priv *sp;
282 struct skcipher_request *req;
283 struct rxrpc_crypt iv;
284 struct scatterlist sg;
285 u32 x, y;
286 int ret;
287
288 sp = rxrpc_skb(skb);
289
290 _enter("{%d{%x}},{#%u},%zu,",
291 call->debug_id, key_serial(call->conn->params.key),
292 sp->hdr.seq, data_size);
293
294 if (!call->conn->cipher)
295 return 0;
296
297 ret = key_validate(call->conn->params.key);
298 if (ret < 0)
299 return ret;
300
301 req = rxkad_get_call_crypto(call);
302 if (!req)
303 return -ENOMEM;
304
305 /* continue encrypting from where we left off */
306 memcpy(&iv, call->conn->csum_iv.x, sizeof(iv));
307
308 /* calculate the security checksum */
309 x = (call->cid & RXRPC_CHANNELMASK) << (32 - RXRPC_CIDSHIFT);
310 x |= sp->hdr.seq & 0x3fffffff;
311 call->crypto_buf[0] = htonl(call->call_id);
312 call->crypto_buf[1] = htonl(x);
313
314 sg_init_one(&sg, call->crypto_buf, 8);
315 skcipher_request_set_sync_tfm(req, call->conn->cipher);
316 skcipher_request_set_callback(req, 0, NULL, NULL);
317 skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x);
318 crypto_skcipher_encrypt(req);
319 skcipher_request_zero(req);
320
321 y = ntohl(call->crypto_buf[1]);
322 y = (y >> 16) & 0xffff;
323 if (y == 0)
324 y = 1; /* zero checksums are not permitted */
325 sp->hdr.cksum = y;
326
327 switch (call->conn->params.security_level) {
328 case RXRPC_SECURITY_PLAIN:
329 ret = 0;
330 break;
331 case RXRPC_SECURITY_AUTH:
332 ret = rxkad_secure_packet_auth(call, skb, data_size, sechdr,
333 req);
334 break;
335 case RXRPC_SECURITY_ENCRYPT:
336 ret = rxkad_secure_packet_encrypt(call, skb, data_size,
337 sechdr, req);
338 break;
339 default:
340 ret = -EPERM;
341 break;
342 }
343
344 _leave(" = %d [set %hx]", ret, y);
345 return ret;
346}
347
348/*
349 * decrypt partial encryption on a packet (level 1 security)
350 */
351static int rxkad_verify_packet_1(struct rxrpc_call *call, struct sk_buff *skb,
352 unsigned int offset, unsigned int len,
353 rxrpc_seq_t seq,
354 struct skcipher_request *req)
355{
356 struct rxkad_level1_hdr sechdr;
357 struct rxrpc_crypt iv;
358 struct scatterlist sg[16];
359 bool aborted;
360 u32 data_size, buf;
361 u16 check;
362 int ret;
363
364 _enter("");
365
366 if (len < 8) {
367 aborted = rxrpc_abort_eproto(call, skb, "rxkad_1_hdr", "V1H",
368 RXKADSEALEDINCON);
369 goto protocol_error;
370 }
371
372 /* Decrypt the skbuff in-place. TODO: We really want to decrypt
373 * directly into the target buffer.
374 */
375 sg_init_table(sg, ARRAY_SIZE(sg));
376 ret = skb_to_sgvec(skb, sg, offset, 8);
377 if (unlikely(ret < 0))
378 return ret;
379
380 /* start the decryption afresh */
381 memset(&iv, 0, sizeof(iv));
382
383 skcipher_request_set_sync_tfm(req, call->conn->cipher);
384 skcipher_request_set_callback(req, 0, NULL, NULL);
385 skcipher_request_set_crypt(req, sg, sg, 8, iv.x);
386 crypto_skcipher_decrypt(req);
387 skcipher_request_zero(req);
388
389 /* Extract the decrypted packet length */
390 if (skb_copy_bits(skb, offset, &sechdr, sizeof(sechdr)) < 0) {
391 aborted = rxrpc_abort_eproto(call, skb, "rxkad_1_len", "XV1",
392 RXKADDATALEN);
393 goto protocol_error;
394 }
395 offset += sizeof(sechdr);
396 len -= sizeof(sechdr);
397
398 buf = ntohl(sechdr.data_size);
399 data_size = buf & 0xffff;
400
401 check = buf >> 16;
402 check ^= seq ^ call->call_id;
403 check &= 0xffff;
404 if (check != 0) {
405 aborted = rxrpc_abort_eproto(call, skb, "rxkad_1_check", "V1C",
406 RXKADSEALEDINCON);
407 goto protocol_error;
408 }
409
410 if (data_size > len) {
411 aborted = rxrpc_abort_eproto(call, skb, "rxkad_1_datalen", "V1L",
412 RXKADDATALEN);
413 goto protocol_error;
414 }
415
416 _leave(" = 0 [dlen=%x]", data_size);
417 return 0;
418
419protocol_error:
420 if (aborted)
421 rxrpc_send_abort_packet(call);
422 return -EPROTO;
423}
424
425/*
426 * wholly decrypt a packet (level 2 security)
427 */
428static int rxkad_verify_packet_2(struct rxrpc_call *call, struct sk_buff *skb,
429 unsigned int offset, unsigned int len,
430 rxrpc_seq_t seq,
431 struct skcipher_request *req)
432{
433 const struct rxrpc_key_token *token;
434 struct rxkad_level2_hdr sechdr;
435 struct rxrpc_crypt iv;
436 struct scatterlist _sg[4], *sg;
437 bool aborted;
438 u32 data_size, buf;
439 u16 check;
440 int nsg, ret;
441
442 _enter(",{%d}", skb->len);
443
444 if (len < 8) {
445 aborted = rxrpc_abort_eproto(call, skb, "rxkad_2_hdr", "V2H",
446 RXKADSEALEDINCON);
447 goto protocol_error;
448 }
449
450 /* Decrypt the skbuff in-place. TODO: We really want to decrypt
451 * directly into the target buffer.
452 */
453 sg = _sg;
454 nsg = skb_shinfo(skb)->nr_frags;
455 if (nsg <= 4) {
456 nsg = 4;
457 } else {
458 sg = kmalloc_array(nsg, sizeof(*sg), GFP_NOIO);
459 if (!sg)
460 goto nomem;
461 }
462
463 sg_init_table(sg, nsg);
464 ret = skb_to_sgvec(skb, sg, offset, len);
465 if (unlikely(ret < 0)) {
466 if (sg != _sg)
467 kfree(sg);
468 return ret;
469 }
470
471 /* decrypt from the session key */
472 token = call->conn->params.key->payload.data[0];
473 memcpy(&iv, token->kad->session_key, sizeof(iv));
474
475 skcipher_request_set_sync_tfm(req, call->conn->cipher);
476 skcipher_request_set_callback(req, 0, NULL, NULL);
477 skcipher_request_set_crypt(req, sg, sg, len, iv.x);
478 crypto_skcipher_decrypt(req);
479 skcipher_request_zero(req);
480 if (sg != _sg)
481 kfree(sg);
482
483 /* Extract the decrypted packet length */
484 if (skb_copy_bits(skb, offset, &sechdr, sizeof(sechdr)) < 0) {
485 aborted = rxrpc_abort_eproto(call, skb, "rxkad_2_len", "XV2",
486 RXKADDATALEN);
487 goto protocol_error;
488 }
489 offset += sizeof(sechdr);
490 len -= sizeof(sechdr);
491
492 buf = ntohl(sechdr.data_size);
493 data_size = buf & 0xffff;
494
495 check = buf >> 16;
496 check ^= seq ^ call->call_id;
497 check &= 0xffff;
498 if (check != 0) {
499 aborted = rxrpc_abort_eproto(call, skb, "rxkad_2_check", "V2C",
500 RXKADSEALEDINCON);
501 goto protocol_error;
502 }
503
504 if (data_size > len) {
505 aborted = rxrpc_abort_eproto(call, skb, "rxkad_2_datalen", "V2L",
506 RXKADDATALEN);
507 goto protocol_error;
508 }
509
510 _leave(" = 0 [dlen=%x]", data_size);
511 return 0;
512
513protocol_error:
514 if (aborted)
515 rxrpc_send_abort_packet(call);
516 return -EPROTO;
517
518nomem:
519 _leave(" = -ENOMEM");
520 return -ENOMEM;
521}
522
523/*
524 * Verify the security on a received packet or subpacket (if part of a
525 * jumbo packet).
526 */
527static int rxkad_verify_packet(struct rxrpc_call *call, struct sk_buff *skb,
528 unsigned int offset, unsigned int len,
529 rxrpc_seq_t seq, u16 expected_cksum)
530{
531 struct skcipher_request *req;
532 struct rxrpc_crypt iv;
533 struct scatterlist sg;
534 bool aborted;
535 u16 cksum;
536 u32 x, y;
537
538 _enter("{%d{%x}},{#%u}",
539 call->debug_id, key_serial(call->conn->params.key), seq);
540
541 if (!call->conn->cipher)
542 return 0;
543
544 req = rxkad_get_call_crypto(call);
545 if (!req)
546 return -ENOMEM;
547
548 /* continue encrypting from where we left off */
549 memcpy(&iv, call->conn->csum_iv.x, sizeof(iv));
550
551 /* validate the security checksum */
552 x = (call->cid & RXRPC_CHANNELMASK) << (32 - RXRPC_CIDSHIFT);
553 x |= seq & 0x3fffffff;
554 call->crypto_buf[0] = htonl(call->call_id);
555 call->crypto_buf[1] = htonl(x);
556
557 sg_init_one(&sg, call->crypto_buf, 8);
558 skcipher_request_set_sync_tfm(req, call->conn->cipher);
559 skcipher_request_set_callback(req, 0, NULL, NULL);
560 skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x);
561 crypto_skcipher_encrypt(req);
562 skcipher_request_zero(req);
563
564 y = ntohl(call->crypto_buf[1]);
565 cksum = (y >> 16) & 0xffff;
566 if (cksum == 0)
567 cksum = 1; /* zero checksums are not permitted */
568
569 if (cksum != expected_cksum) {
570 aborted = rxrpc_abort_eproto(call, skb, "rxkad_csum", "VCK",
571 RXKADSEALEDINCON);
572 goto protocol_error;
573 }
574
575 switch (call->conn->params.security_level) {
576 case RXRPC_SECURITY_PLAIN:
577 return 0;
578 case RXRPC_SECURITY_AUTH:
579 return rxkad_verify_packet_1(call, skb, offset, len, seq, req);
580 case RXRPC_SECURITY_ENCRYPT:
581 return rxkad_verify_packet_2(call, skb, offset, len, seq, req);
582 default:
583 return -ENOANO;
584 }
585
586protocol_error:
587 if (aborted)
588 rxrpc_send_abort_packet(call);
589 return -EPROTO;
590}
591
592/*
593 * Locate the data contained in a packet that was partially encrypted.
594 */
595static void rxkad_locate_data_1(struct rxrpc_call *call, struct sk_buff *skb,
596 unsigned int *_offset, unsigned int *_len)
597{
598 struct rxkad_level1_hdr sechdr;
599
600 if (skb_copy_bits(skb, *_offset, &sechdr, sizeof(sechdr)) < 0)
601 BUG();
602 *_offset += sizeof(sechdr);
603 *_len = ntohl(sechdr.data_size) & 0xffff;
604}
605
606/*
607 * Locate the data contained in a packet that was completely encrypted.
608 */
609static void rxkad_locate_data_2(struct rxrpc_call *call, struct sk_buff *skb,
610 unsigned int *_offset, unsigned int *_len)
611{
612 struct rxkad_level2_hdr sechdr;
613
614 if (skb_copy_bits(skb, *_offset, &sechdr, sizeof(sechdr)) < 0)
615 BUG();
616 *_offset += sizeof(sechdr);
617 *_len = ntohl(sechdr.data_size) & 0xffff;
618}
619
620/*
621 * Locate the data contained in an already decrypted packet.
622 */
623static void rxkad_locate_data(struct rxrpc_call *call, struct sk_buff *skb,
624 unsigned int *_offset, unsigned int *_len)
625{
626 switch (call->conn->params.security_level) {
627 case RXRPC_SECURITY_AUTH:
628 rxkad_locate_data_1(call, skb, _offset, _len);
629 return;
630 case RXRPC_SECURITY_ENCRYPT:
631 rxkad_locate_data_2(call, skb, _offset, _len);
632 return;
633 default:
634 return;
635 }
636}
637
638/*
639 * issue a challenge
640 */
641static int rxkad_issue_challenge(struct rxrpc_connection *conn)
642{
643 struct rxkad_challenge challenge;
644 struct rxrpc_wire_header whdr;
645 struct msghdr msg;
646 struct kvec iov[2];
647 size_t len;
648 u32 serial;
649 int ret;
650
651 _enter("{%d,%x}", conn->debug_id, key_serial(conn->params.key));
652
653 ret = key_validate(conn->params.key);
654 if (ret < 0)
655 return ret;
656
657 get_random_bytes(&conn->security_nonce, sizeof(conn->security_nonce));
658
659 challenge.version = htonl(2);
660 challenge.nonce = htonl(conn->security_nonce);
661 challenge.min_level = htonl(0);
662 challenge.__padding = 0;
663
664 msg.msg_name = &conn->params.peer->srx.transport;
665 msg.msg_namelen = conn->params.peer->srx.transport_len;
666 msg.msg_control = NULL;
667 msg.msg_controllen = 0;
668 msg.msg_flags = 0;
669
670 whdr.epoch = htonl(conn->proto.epoch);
671 whdr.cid = htonl(conn->proto.cid);
672 whdr.callNumber = 0;
673 whdr.seq = 0;
674 whdr.type = RXRPC_PACKET_TYPE_CHALLENGE;
675 whdr.flags = conn->out_clientflag;
676 whdr.userStatus = 0;
677 whdr.securityIndex = conn->security_ix;
678 whdr._rsvd = 0;
679 whdr.serviceId = htons(conn->service_id);
680
681 iov[0].iov_base = &whdr;
682 iov[0].iov_len = sizeof(whdr);
683 iov[1].iov_base = &challenge;
684 iov[1].iov_len = sizeof(challenge);
685
686 len = iov[0].iov_len + iov[1].iov_len;
687
688 serial = atomic_inc_return(&conn->serial);
689 whdr.serial = htonl(serial);
690 _proto("Tx CHALLENGE %%%u", serial);
691
692 ret = kernel_sendmsg(conn->params.local->socket, &msg, iov, 2, len);
693 if (ret < 0) {
694 trace_rxrpc_tx_fail(conn->debug_id, serial, ret,
695 rxrpc_tx_point_rxkad_challenge);
696 return -EAGAIN;
697 }
698
699 conn->params.peer->last_tx_at = ktime_get_seconds();
700 trace_rxrpc_tx_packet(conn->debug_id, &whdr,
701 rxrpc_tx_point_rxkad_challenge);
702 _leave(" = 0");
703 return 0;
704}
705
706/*
707 * send a Kerberos security response
708 */
709static int rxkad_send_response(struct rxrpc_connection *conn,
710 struct rxrpc_host_header *hdr,
711 struct rxkad_response *resp,
712 const struct rxkad_key *s2)
713{
714 struct rxrpc_wire_header whdr;
715 struct msghdr msg;
716 struct kvec iov[3];
717 size_t len;
718 u32 serial;
719 int ret;
720
721 _enter("");
722
723 msg.msg_name = &conn->params.peer->srx.transport;
724 msg.msg_namelen = conn->params.peer->srx.transport_len;
725 msg.msg_control = NULL;
726 msg.msg_controllen = 0;
727 msg.msg_flags = 0;
728
729 memset(&whdr, 0, sizeof(whdr));
730 whdr.epoch = htonl(hdr->epoch);
731 whdr.cid = htonl(hdr->cid);
732 whdr.type = RXRPC_PACKET_TYPE_RESPONSE;
733 whdr.flags = conn->out_clientflag;
734 whdr.securityIndex = hdr->securityIndex;
735 whdr.serviceId = htons(hdr->serviceId);
736
737 iov[0].iov_base = &whdr;
738 iov[0].iov_len = sizeof(whdr);
739 iov[1].iov_base = resp;
740 iov[1].iov_len = sizeof(*resp);
741 iov[2].iov_base = (void *)s2->ticket;
742 iov[2].iov_len = s2->ticket_len;
743
744 len = iov[0].iov_len + iov[1].iov_len + iov[2].iov_len;
745
746 serial = atomic_inc_return(&conn->serial);
747 whdr.serial = htonl(serial);
748 _proto("Tx RESPONSE %%%u", serial);
749
750 ret = kernel_sendmsg(conn->params.local->socket, &msg, iov, 3, len);
751 if (ret < 0) {
752 trace_rxrpc_tx_fail(conn->debug_id, serial, ret,
753 rxrpc_tx_point_rxkad_response);
754 return -EAGAIN;
755 }
756
757 conn->params.peer->last_tx_at = ktime_get_seconds();
758 _leave(" = 0");
759 return 0;
760}
761
762/*
763 * calculate the response checksum
764 */
765static void rxkad_calc_response_checksum(struct rxkad_response *response)
766{
767 u32 csum = 1000003;
768 int loop;
769 u8 *p = (u8 *) response;
770
771 for (loop = sizeof(*response); loop > 0; loop--)
772 csum = csum * 0x10204081 + *p++;
773
774 response->encrypted.checksum = htonl(csum);
775}
776
777/*
778 * encrypt the response packet
779 */
780static int rxkad_encrypt_response(struct rxrpc_connection *conn,
781 struct rxkad_response *resp,
782 const struct rxkad_key *s2)
783{
784 struct skcipher_request *req;
785 struct rxrpc_crypt iv;
786 struct scatterlist sg[1];
787
788 req = skcipher_request_alloc(&conn->cipher->base, GFP_NOFS);
789 if (!req)
790 return -ENOMEM;
791
792 /* continue encrypting from where we left off */
793 memcpy(&iv, s2->session_key, sizeof(iv));
794
795 sg_init_table(sg, 1);
796 sg_set_buf(sg, &resp->encrypted, sizeof(resp->encrypted));
797 skcipher_request_set_sync_tfm(req, conn->cipher);
798 skcipher_request_set_callback(req, 0, NULL, NULL);
799 skcipher_request_set_crypt(req, sg, sg, sizeof(resp->encrypted), iv.x);
800 crypto_skcipher_encrypt(req);
801 skcipher_request_free(req);
802 return 0;
803}
804
805/*
806 * respond to a challenge packet
807 */
808static int rxkad_respond_to_challenge(struct rxrpc_connection *conn,
809 struct sk_buff *skb,
810 u32 *_abort_code)
811{
812 const struct rxrpc_key_token *token;
813 struct rxkad_challenge challenge;
814 struct rxkad_response *resp;
815 struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
816 const char *eproto;
817 u32 version, nonce, min_level, abort_code;
818 int ret;
819
820 _enter("{%d,%x}", conn->debug_id, key_serial(conn->params.key));
821
822 eproto = tracepoint_string("chall_no_key");
823 abort_code = RX_PROTOCOL_ERROR;
824 if (!conn->params.key)
825 goto protocol_error;
826
827 abort_code = RXKADEXPIRED;
828 ret = key_validate(conn->params.key);
829 if (ret < 0)
830 goto other_error;
831
832 eproto = tracepoint_string("chall_short");
833 abort_code = RXKADPACKETSHORT;
834 if (skb_copy_bits(skb, sizeof(struct rxrpc_wire_header),
835 &challenge, sizeof(challenge)) < 0)
836 goto protocol_error;
837
838 version = ntohl(challenge.version);
839 nonce = ntohl(challenge.nonce);
840 min_level = ntohl(challenge.min_level);
841
842 _proto("Rx CHALLENGE %%%u { v=%u n=%u ml=%u }",
843 sp->hdr.serial, version, nonce, min_level);
844
845 eproto = tracepoint_string("chall_ver");
846 abort_code = RXKADINCONSISTENCY;
847 if (version != RXKAD_VERSION)
848 goto protocol_error;
849
850 abort_code = RXKADLEVELFAIL;
851 ret = -EACCES;
852 if (conn->params.security_level < min_level)
853 goto other_error;
854
855 token = conn->params.key->payload.data[0];
856
857 /* build the response packet */
858 resp = kzalloc(sizeof(struct rxkad_response), GFP_NOFS);
859 if (!resp)
860 return -ENOMEM;
861
862 resp->version = htonl(RXKAD_VERSION);
863 resp->encrypted.epoch = htonl(conn->proto.epoch);
864 resp->encrypted.cid = htonl(conn->proto.cid);
865 resp->encrypted.securityIndex = htonl(conn->security_ix);
866 resp->encrypted.inc_nonce = htonl(nonce + 1);
867 resp->encrypted.level = htonl(conn->params.security_level);
868 resp->kvno = htonl(token->kad->kvno);
869 resp->ticket_len = htonl(token->kad->ticket_len);
870 resp->encrypted.call_id[0] = htonl(conn->channels[0].call_counter);
871 resp->encrypted.call_id[1] = htonl(conn->channels[1].call_counter);
872 resp->encrypted.call_id[2] = htonl(conn->channels[2].call_counter);
873 resp->encrypted.call_id[3] = htonl(conn->channels[3].call_counter);
874
875 /* calculate the response checksum and then do the encryption */
876 rxkad_calc_response_checksum(resp);
877 ret = rxkad_encrypt_response(conn, resp, token->kad);
878 if (ret == 0)
879 ret = rxkad_send_response(conn, &sp->hdr, resp, token->kad);
880 kfree(resp);
881 return ret;
882
883protocol_error:
884 trace_rxrpc_rx_eproto(NULL, sp->hdr.serial, eproto);
885 ret = -EPROTO;
886other_error:
887 *_abort_code = abort_code;
888 return ret;
889}
890
891/*
892 * decrypt the kerberos IV ticket in the response
893 */
894static int rxkad_decrypt_ticket(struct rxrpc_connection *conn,
895 struct sk_buff *skb,
896 void *ticket, size_t ticket_len,
897 struct rxrpc_crypt *_session_key,
898 time64_t *_expiry,
899 u32 *_abort_code)
900{
901 struct skcipher_request *req;
902 struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
903 struct rxrpc_crypt iv, key;
904 struct scatterlist sg[1];
905 struct in_addr addr;
906 unsigned int life;
907 const char *eproto;
908 time64_t issue, now;
909 bool little_endian;
910 int ret;
911 u32 abort_code;
912 u8 *p, *q, *name, *end;
913
914 _enter("{%d},{%x}", conn->debug_id, key_serial(conn->server_key));
915
916 *_expiry = 0;
917
918 ret = key_validate(conn->server_key);
919 if (ret < 0) {
920 switch (ret) {
921 case -EKEYEXPIRED:
922 abort_code = RXKADEXPIRED;
923 goto other_error;
924 default:
925 abort_code = RXKADNOAUTH;
926 goto other_error;
927 }
928 }
929
930 ASSERT(conn->server_key->payload.data[0] != NULL);
931 ASSERTCMP((unsigned long) ticket & 7UL, ==, 0);
932
933 memcpy(&iv, &conn->server_key->payload.data[2], sizeof(iv));
934
935 ret = -ENOMEM;
936 req = skcipher_request_alloc(conn->server_key->payload.data[0],
937 GFP_NOFS);
938 if (!req)
939 goto temporary_error;
940
941 sg_init_one(&sg[0], ticket, ticket_len);
942 skcipher_request_set_callback(req, 0, NULL, NULL);
943 skcipher_request_set_crypt(req, sg, sg, ticket_len, iv.x);
944 crypto_skcipher_decrypt(req);
945 skcipher_request_free(req);
946
947 p = ticket;
948 end = p + ticket_len;
949
950#define Z(field) \
951 ({ \
952 u8 *__str = p; \
953 eproto = tracepoint_string("rxkad_bad_"#field); \
954 q = memchr(p, 0, end - p); \
955 if (!q || q - p > (field##_SZ)) \
956 goto bad_ticket; \
957 for (; p < q; p++) \
958 if (!isprint(*p)) \
959 goto bad_ticket; \
960 p++; \
961 __str; \
962 })
963
964 /* extract the ticket flags */
965 _debug("KIV FLAGS: %x", *p);
966 little_endian = *p & 1;
967 p++;
968
969 /* extract the authentication name */
970 name = Z(ANAME);
971 _debug("KIV ANAME: %s", name);
972
973 /* extract the principal's instance */
974 name = Z(INST);
975 _debug("KIV INST : %s", name);
976
977 /* extract the principal's authentication domain */
978 name = Z(REALM);
979 _debug("KIV REALM: %s", name);
980
981 eproto = tracepoint_string("rxkad_bad_len");
982 if (end - p < 4 + 8 + 4 + 2)
983 goto bad_ticket;
984
985 /* get the IPv4 address of the entity that requested the ticket */
986 memcpy(&addr, p, sizeof(addr));
987 p += 4;
988 _debug("KIV ADDR : %pI4", &addr);
989
990 /* get the session key from the ticket */
991 memcpy(&key, p, sizeof(key));
992 p += 8;
993 _debug("KIV KEY : %08x %08x", ntohl(key.n[0]), ntohl(key.n[1]));
994 memcpy(_session_key, &key, sizeof(key));
995
996 /* get the ticket's lifetime */
997 life = *p++ * 5 * 60;
998 _debug("KIV LIFE : %u", life);
999
1000 /* get the issue time of the ticket */
1001 if (little_endian) {
1002 __le32 stamp;
1003 memcpy(&stamp, p, 4);
1004 issue = rxrpc_u32_to_time64(le32_to_cpu(stamp));
1005 } else {
1006 __be32 stamp;
1007 memcpy(&stamp, p, 4);
1008 issue = rxrpc_u32_to_time64(be32_to_cpu(stamp));
1009 }
1010 p += 4;
1011 now = ktime_get_real_seconds();
1012 _debug("KIV ISSUE: %llx [%llx]", issue, now);
1013
1014 /* check the ticket is in date */
1015 if (issue > now) {
1016 abort_code = RXKADNOAUTH;
1017 ret = -EKEYREJECTED;
1018 goto other_error;
1019 }
1020
1021 if (issue < now - life) {
1022 abort_code = RXKADEXPIRED;
1023 ret = -EKEYEXPIRED;
1024 goto other_error;
1025 }
1026
1027 *_expiry = issue + life;
1028
1029 /* get the service name */
1030 name = Z(SNAME);
1031 _debug("KIV SNAME: %s", name);
1032
1033 /* get the service instance name */
1034 name = Z(INST);
1035 _debug("KIV SINST: %s", name);
1036 return 0;
1037
1038bad_ticket:
1039 trace_rxrpc_rx_eproto(NULL, sp->hdr.serial, eproto);
1040 abort_code = RXKADBADTICKET;
1041 ret = -EPROTO;
1042other_error:
1043 *_abort_code = abort_code;
1044 return ret;
1045temporary_error:
1046 return ret;
1047}
1048
1049/*
1050 * decrypt the response packet
1051 */
1052static void rxkad_decrypt_response(struct rxrpc_connection *conn,
1053 struct rxkad_response *resp,
1054 const struct rxrpc_crypt *session_key)
1055{
1056 struct skcipher_request *req = rxkad_ci_req;
1057 struct scatterlist sg[1];
1058 struct rxrpc_crypt iv;
1059
1060 _enter(",,%08x%08x",
1061 ntohl(session_key->n[0]), ntohl(session_key->n[1]));
1062
1063 mutex_lock(&rxkad_ci_mutex);
1064 if (crypto_sync_skcipher_setkey(rxkad_ci, session_key->x,
1065 sizeof(*session_key)) < 0)
1066 BUG();
1067
1068 memcpy(&iv, session_key, sizeof(iv));
1069
1070 sg_init_table(sg, 1);
1071 sg_set_buf(sg, &resp->encrypted, sizeof(resp->encrypted));
1072 skcipher_request_set_sync_tfm(req, rxkad_ci);
1073 skcipher_request_set_callback(req, 0, NULL, NULL);
1074 skcipher_request_set_crypt(req, sg, sg, sizeof(resp->encrypted), iv.x);
1075 crypto_skcipher_decrypt(req);
1076 skcipher_request_zero(req);
1077
1078 mutex_unlock(&rxkad_ci_mutex);
1079
1080 _leave("");
1081}
1082
1083/*
1084 * verify a response
1085 */
1086static int rxkad_verify_response(struct rxrpc_connection *conn,
1087 struct sk_buff *skb,
1088 u32 *_abort_code)
1089{
1090 struct rxkad_response *response;
1091 struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
1092 struct rxrpc_crypt session_key;
1093 const char *eproto;
1094 time64_t expiry;
1095 void *ticket;
1096 u32 abort_code, version, kvno, ticket_len, level;
1097 __be32 csum;
1098 int ret, i;
1099
1100 _enter("{%d,%x}", conn->debug_id, key_serial(conn->server_key));
1101
1102 ret = -ENOMEM;
1103 response = kzalloc(sizeof(struct rxkad_response), GFP_NOFS);
1104 if (!response)
1105 goto temporary_error;
1106
1107 eproto = tracepoint_string("rxkad_rsp_short");
1108 abort_code = RXKADPACKETSHORT;
1109 if (skb_copy_bits(skb, sizeof(struct rxrpc_wire_header),
1110 response, sizeof(*response)) < 0)
1111 goto protocol_error;
1112 if (!pskb_pull(skb, sizeof(*response)))
1113 BUG();
1114
1115 version = ntohl(response->version);
1116 ticket_len = ntohl(response->ticket_len);
1117 kvno = ntohl(response->kvno);
1118 _proto("Rx RESPONSE %%%u { v=%u kv=%u tl=%u }",
1119 sp->hdr.serial, version, kvno, ticket_len);
1120
1121 eproto = tracepoint_string("rxkad_rsp_ver");
1122 abort_code = RXKADINCONSISTENCY;
1123 if (version != RXKAD_VERSION)
1124 goto protocol_error;
1125
1126 eproto = tracepoint_string("rxkad_rsp_tktlen");
1127 abort_code = RXKADTICKETLEN;
1128 if (ticket_len < 4 || ticket_len > MAXKRB5TICKETLEN)
1129 goto protocol_error;
1130
1131 eproto = tracepoint_string("rxkad_rsp_unkkey");
1132 abort_code = RXKADUNKNOWNKEY;
1133 if (kvno >= RXKAD_TKT_TYPE_KERBEROS_V5)
1134 goto protocol_error;
1135
1136 /* extract the kerberos ticket and decrypt and decode it */
1137 ret = -ENOMEM;
1138 ticket = kmalloc(ticket_len, GFP_NOFS);
1139 if (!ticket)
1140 goto temporary_error;
1141
1142 eproto = tracepoint_string("rxkad_tkt_short");
1143 abort_code = RXKADPACKETSHORT;
1144 if (skb_copy_bits(skb, sizeof(struct rxrpc_wire_header),
1145 ticket, ticket_len) < 0)
1146 goto protocol_error_free;
1147
1148 ret = rxkad_decrypt_ticket(conn, skb, ticket, ticket_len, &session_key,
1149 &expiry, _abort_code);
1150 if (ret < 0)
1151 goto temporary_error_free_resp;
1152
1153 /* use the session key from inside the ticket to decrypt the
1154 * response */
1155 rxkad_decrypt_response(conn, response, &session_key);
1156
1157 eproto = tracepoint_string("rxkad_rsp_param");
1158 abort_code = RXKADSEALEDINCON;
1159 if (ntohl(response->encrypted.epoch) != conn->proto.epoch)
1160 goto protocol_error_free;
1161 if (ntohl(response->encrypted.cid) != conn->proto.cid)
1162 goto protocol_error_free;
1163 if (ntohl(response->encrypted.securityIndex) != conn->security_ix)
1164 goto protocol_error_free;
1165 csum = response->encrypted.checksum;
1166 response->encrypted.checksum = 0;
1167 rxkad_calc_response_checksum(response);
1168 eproto = tracepoint_string("rxkad_rsp_csum");
1169 if (response->encrypted.checksum != csum)
1170 goto protocol_error_free;
1171
1172 spin_lock(&conn->channel_lock);
1173 for (i = 0; i < RXRPC_MAXCALLS; i++) {
1174 struct rxrpc_call *call;
1175 u32 call_id = ntohl(response->encrypted.call_id[i]);
1176
1177 eproto = tracepoint_string("rxkad_rsp_callid");
1178 if (call_id > INT_MAX)
1179 goto protocol_error_unlock;
1180
1181 eproto = tracepoint_string("rxkad_rsp_callctr");
1182 if (call_id < conn->channels[i].call_counter)
1183 goto protocol_error_unlock;
1184
1185 eproto = tracepoint_string("rxkad_rsp_callst");
1186 if (call_id > conn->channels[i].call_counter) {
1187 call = rcu_dereference_protected(
1188 conn->channels[i].call,
1189 lockdep_is_held(&conn->channel_lock));
1190 if (call && call->state < RXRPC_CALL_COMPLETE)
1191 goto protocol_error_unlock;
1192 conn->channels[i].call_counter = call_id;
1193 }
1194 }
1195 spin_unlock(&conn->channel_lock);
1196
1197 eproto = tracepoint_string("rxkad_rsp_seq");
1198 abort_code = RXKADOUTOFSEQUENCE;
1199 if (ntohl(response->encrypted.inc_nonce) != conn->security_nonce + 1)
1200 goto protocol_error_free;
1201
1202 eproto = tracepoint_string("rxkad_rsp_level");
1203 abort_code = RXKADLEVELFAIL;
1204 level = ntohl(response->encrypted.level);
1205 if (level > RXRPC_SECURITY_ENCRYPT)
1206 goto protocol_error_free;
1207 conn->params.security_level = level;
1208
1209 /* create a key to hold the security data and expiration time - after
1210 * this the connection security can be handled in exactly the same way
1211 * as for a client connection */
1212 ret = rxrpc_get_server_data_key(conn, &session_key, expiry, kvno);
1213 if (ret < 0)
1214 goto temporary_error_free_ticket;
1215
1216 kfree(ticket);
1217 kfree(response);
1218 _leave(" = 0");
1219 return 0;
1220
1221protocol_error_unlock:
1222 spin_unlock(&conn->channel_lock);
1223protocol_error_free:
1224 kfree(ticket);
1225protocol_error:
1226 kfree(response);
1227 trace_rxrpc_rx_eproto(NULL, sp->hdr.serial, eproto);
1228 *_abort_code = abort_code;
1229 return -EPROTO;
1230
1231temporary_error_free_ticket:
1232 kfree(ticket);
1233temporary_error_free_resp:
1234 kfree(response);
1235temporary_error:
1236 /* Ignore the response packet if we got a temporary error such as
1237 * ENOMEM. We just want to send the challenge again. Note that we
1238 * also come out this way if the ticket decryption fails.
1239 */
1240 return ret;
1241}
1242
1243/*
1244 * clear the connection security
1245 */
1246static void rxkad_clear(struct rxrpc_connection *conn)
1247{
1248 _enter("");
1249
1250 if (conn->cipher)
1251 crypto_free_sync_skcipher(conn->cipher);
1252}
1253
1254/*
1255 * Initialise the rxkad security service.
1256 */
1257static int rxkad_init(void)
1258{
1259 struct crypto_sync_skcipher *tfm;
1260 struct skcipher_request *req;
1261
1262 /* pin the cipher we need so that the crypto layer doesn't invoke
1263 * keventd to go get it */
1264 tfm = crypto_alloc_sync_skcipher("pcbc(fcrypt)", 0, 0);
1265 if (IS_ERR(tfm))
1266 return PTR_ERR(tfm);
1267
1268 req = skcipher_request_alloc(&tfm->base, GFP_KERNEL);
1269 if (!req)
1270 goto nomem_tfm;
1271
1272 rxkad_ci_req = req;
1273 rxkad_ci = tfm;
1274 return 0;
1275
1276nomem_tfm:
1277 crypto_free_sync_skcipher(tfm);
1278 return -ENOMEM;
1279}
1280
1281/*
1282 * Clean up the rxkad security service.
1283 */
1284static void rxkad_exit(void)
1285{
1286 crypto_free_sync_skcipher(rxkad_ci);
1287 skcipher_request_free(rxkad_ci_req);
1288}
1289
1290/*
1291 * RxRPC Kerberos-based security
1292 */
1293const struct rxrpc_security rxkad = {
1294 .name = "rxkad",
1295 .security_index = RXRPC_SECURITY_RXKAD,
1296 .init = rxkad_init,
1297 .exit = rxkad_exit,
1298 .init_connection_security = rxkad_init_connection_security,
1299 .prime_packet_security = rxkad_prime_packet_security,
1300 .secure_packet = rxkad_secure_packet,
1301 .verify_packet = rxkad_verify_packet,
1302 .free_call_crypto = rxkad_free_call_crypto,
1303 .locate_data = rxkad_locate_data,
1304 .issue_challenge = rxkad_issue_challenge,
1305 .respond_to_challenge = rxkad_respond_to_challenge,
1306 .verify_response = rxkad_verify_response,
1307 .clear = rxkad_clear,
1308};