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Committer: Michael Beasley <mike@snafu.setup>
[mikesnafu-overlay.git] / net / rxrpc / rxkad.c
blob6d38a81b336d50e89942637f8ad8b715c2a0ae7f
1 /* Kerberos-based RxRPC security
2 *
3 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
12 #include <linux/module.h>
13 #include <linux/net.h>
14 #include <linux/skbuff.h>
15 #include <linux/udp.h>
16 #include <linux/crypto.h>
17 #include <linux/scatterlist.h>
18 #include <linux/ctype.h>
19 #include <net/sock.h>
20 #include <net/af_rxrpc.h>
21 #define rxrpc_debug rxkad_debug
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
32 unsigned rxrpc_debug;
33 module_param_named(debug, rxrpc_debug, uint, S_IWUSR | S_IRUGO);
34 MODULE_PARM_DESC(debug, "rxkad debugging mask");
35
36 struct rxkad_level1_hdr {
37 __be32 data_size; /* true data size (excluding padding) */
38 };
39
40 struct rxkad_level2_hdr {
41 __be32 data_size; /* true data size (excluding padding) */
42 __be32 checksum; /* decrypted data checksum */
43 };
44
45 MODULE_DESCRIPTION("RxRPC network protocol type-2 security (Kerberos)");
46 MODULE_AUTHOR("Red Hat, Inc.");
47 MODULE_LICENSE("GPL");
48
49 /*
50 * this holds a pinned cipher so that keventd doesn't get called by the cipher
51 * alloc routine, but since we have it to hand, we use it to decrypt RESPONSE
52 * packets
53 */
54 static struct crypto_blkcipher *rxkad_ci;
55 static DEFINE_MUTEX(rxkad_ci_mutex);
56
57 /*
58 * initialise connection security
59 */
60 static int rxkad_init_connection_security(struct rxrpc_connection *conn)
61 {
62 struct rxrpc_key_payload *payload;
63 struct crypto_blkcipher *ci;
64 int ret;
65
66 _enter("{%d},{%x}", conn->debug_id, key_serial(conn->key));
67
68 payload = conn->key->payload.data;
69 conn->security_ix = payload->k.security_index;
70
71 ci = crypto_alloc_blkcipher("pcbc(fcrypt)", 0, CRYPTO_ALG_ASYNC);
72 if (IS_ERR(ci)) {
73 _debug("no cipher");
74 ret = PTR_ERR(ci);
75 goto error;
76 }
77
78 if (crypto_blkcipher_setkey(ci, payload->k.session_key,
79 sizeof(payload->k.session_key)) < 0)
80 BUG();
81
82 switch (conn->security_level) {
83 case RXRPC_SECURITY_PLAIN:
84 break;
85 case RXRPC_SECURITY_AUTH:
86 conn->size_align = 8;
87 conn->security_size = sizeof(struct rxkad_level1_hdr);
88 conn->header_size += sizeof(struct rxkad_level1_hdr);
89 break;
90 case RXRPC_SECURITY_ENCRYPT:
91 conn->size_align = 8;
92 conn->security_size = sizeof(struct rxkad_level2_hdr);
93 conn->header_size += sizeof(struct rxkad_level2_hdr);
94 break;
95 default:
96 ret = -EKEYREJECTED;
97 goto error;
98 }
99
100 conn->cipher = ci;
101 ret = 0;
102 error:
103 _leave(" = %d", ret);
104 return ret;
105 }
106
107 /*
108 * prime the encryption state with the invariant parts of a connection's
109 * description
110 */
111 static void rxkad_prime_packet_security(struct rxrpc_connection *conn)
112 {
113 struct rxrpc_key_payload *payload;
114 struct blkcipher_desc desc;
115 struct scatterlist sg[2];
116 struct rxrpc_crypt iv;
117 struct {
118 __be32 x[4];
119 } tmpbuf __attribute__((aligned(16))); /* must all be in same page */
120
121 _enter("");
122
123 if (!conn->key)
124 return;
125
126 payload = conn->key->payload.data;
127 memcpy(&iv, payload->k.session_key, sizeof(iv));
128
129 desc.tfm = conn->cipher;
130 desc.info = iv.x;
131 desc.flags = 0;
132
133 tmpbuf.x[0] = conn->epoch;
134 tmpbuf.x[1] = conn->cid;
135 tmpbuf.x[2] = 0;
136 tmpbuf.x[3] = htonl(conn->security_ix);
137
138 sg_init_one(&sg[0], &tmpbuf, sizeof(tmpbuf));
139 sg_init_one(&sg[1], &tmpbuf, sizeof(tmpbuf));
140 crypto_blkcipher_encrypt_iv(&desc, &sg[0], &sg[1], sizeof(tmpbuf));
141
142 memcpy(&conn->csum_iv, &tmpbuf.x[2], sizeof(conn->csum_iv));
143 ASSERTCMP(conn->csum_iv.n[0], ==, tmpbuf.x[2]);
144
145 _leave("");
146 }
147
148 /*
149 * partially encrypt a packet (level 1 security)
150 */
151 static int rxkad_secure_packet_auth(const struct rxrpc_call *call,
152 struct sk_buff *skb,
153 u32 data_size,
154 void *sechdr)
155 {
156 struct rxrpc_skb_priv *sp;
157 struct blkcipher_desc desc;
158 struct rxrpc_crypt iv;
159 struct scatterlist sg[2];
160 struct {
161 struct rxkad_level1_hdr hdr;
162 __be32 first; /* first four bytes of data and padding */
163 } tmpbuf __attribute__((aligned(8))); /* must all be in same page */
164 u16 check;
165
166 sp = rxrpc_skb(skb);
167
168 _enter("");
169
170 check = ntohl(sp->hdr.seq ^ sp->hdr.callNumber);
171 data_size |= (u32) check << 16;
172
173 tmpbuf.hdr.data_size = htonl(data_size);
174 memcpy(&tmpbuf.first, sechdr + 4, sizeof(tmpbuf.first));
175
176 /* start the encryption afresh */
177 memset(&iv, 0, sizeof(iv));
178 desc.tfm = call->conn->cipher;
179 desc.info = iv.x;
180 desc.flags = 0;
181
182 sg_init_one(&sg[0], &tmpbuf, sizeof(tmpbuf));
183 sg_init_one(&sg[1], &tmpbuf, sizeof(tmpbuf));
184 crypto_blkcipher_encrypt_iv(&desc, &sg[0], &sg[1], sizeof(tmpbuf));
185
186 memcpy(sechdr, &tmpbuf, sizeof(tmpbuf));
187
188 _leave(" = 0");
189 return 0;
190 }
191
192 /*
193 * wholly encrypt a packet (level 2 security)
194 */
195 static int rxkad_secure_packet_encrypt(const struct rxrpc_call *call,
196 struct sk_buff *skb,
197 u32 data_size,
198 void *sechdr)
199 {
200 const struct rxrpc_key_payload *payload;
201 struct rxkad_level2_hdr rxkhdr
202 __attribute__((aligned(8))); /* must be all on one page */
203 struct rxrpc_skb_priv *sp;
204 struct blkcipher_desc desc;
205 struct rxrpc_crypt iv;
206 struct scatterlist sg[16];
207 struct sk_buff *trailer;
208 unsigned len;
209 u16 check;
210 int nsg;
211
212 sp = rxrpc_skb(skb);
213
214 _enter("");
215
216 check = ntohl(sp->hdr.seq ^ sp->hdr.callNumber);
217
218 rxkhdr.data_size = htonl(data_size | (u32) check << 16);
219 rxkhdr.checksum = 0;
220
221 /* encrypt from the session key */
222 payload = call->conn->key->payload.data;
223 memcpy(&iv, payload->k.session_key, sizeof(iv));
224 desc.tfm = call->conn->cipher;
225 desc.info = iv.x;
226 desc.flags = 0;
227
228 sg_init_one(&sg[0], sechdr, sizeof(rxkhdr));
229 sg_init_one(&sg[1], &rxkhdr, sizeof(rxkhdr));
230 crypto_blkcipher_encrypt_iv(&desc, &sg[0], &sg[1], sizeof(rxkhdr));
231
232 /* we want to encrypt the skbuff in-place */
233 nsg = skb_cow_data(skb, 0, &trailer);
234 if (nsg < 0 || nsg > 16)
235 return -ENOMEM;
236
237 len = data_size + call->conn->size_align - 1;
238 len &= ~(call->conn->size_align - 1);
239
240 sg_init_table(sg, nsg);
241 skb_to_sgvec(skb, sg, 0, len);
242 crypto_blkcipher_encrypt_iv(&desc, sg, sg, len);
243
244 _leave(" = 0");
245 return 0;
246 }
247
248 /*
249 * checksum an RxRPC packet header
250 */
251 static int rxkad_secure_packet(const struct rxrpc_call *call,
252 struct sk_buff *skb,
253 size_t data_size,
254 void *sechdr)
255 {
256 struct rxrpc_skb_priv *sp;
257 struct blkcipher_desc desc;
258 struct rxrpc_crypt iv;
259 struct scatterlist sg[2];
260 struct {
261 __be32 x[2];
262 } tmpbuf __attribute__((aligned(8))); /* must all be in same page */
263 __be32 x;
264 u32 y;
265 int ret;
266
267 sp = rxrpc_skb(skb);
268
269 _enter("{%d{%x}},{#%u},%zu,",
270 call->debug_id, key_serial(call->conn->key), ntohl(sp->hdr.seq),
271 data_size);
272
273 if (!call->conn->cipher)
274 return 0;
275
276 ret = key_validate(call->conn->key);
277 if (ret < 0)
278 return ret;
279
280 /* continue encrypting from where we left off */
281 memcpy(&iv, call->conn->csum_iv.x, sizeof(iv));
282 desc.tfm = call->conn->cipher;
283 desc.info = iv.x;
284 desc.flags = 0;
285
286 /* calculate the security checksum */
287 x = htonl(call->channel << (32 - RXRPC_CIDSHIFT));
288 x |= sp->hdr.seq & cpu_to_be32(0x3fffffff);
289 tmpbuf.x[0] = sp->hdr.callNumber;
290 tmpbuf.x[1] = x;
291
292 sg_init_one(&sg[0], &tmpbuf, sizeof(tmpbuf));
293 sg_init_one(&sg[1], &tmpbuf, sizeof(tmpbuf));
294 crypto_blkcipher_encrypt_iv(&desc, &sg[0], &sg[1], sizeof(tmpbuf));
295
296 y = ntohl(tmpbuf.x[1]);
297 y = (y >> 16) & 0xffff;
298 if (y == 0)
299 y = 1; /* zero checksums are not permitted */
300 sp->hdr.cksum = htons(y);
301
302 switch (call->conn->security_level) {
303 case RXRPC_SECURITY_PLAIN:
304 ret = 0;
305 break;
306 case RXRPC_SECURITY_AUTH:
307 ret = rxkad_secure_packet_auth(call, skb, data_size, sechdr);
308 break;
309 case RXRPC_SECURITY_ENCRYPT:
310 ret = rxkad_secure_packet_encrypt(call, skb, data_size,
311 sechdr);
312 break;
313 default:
314 ret = -EPERM;
315 break;
316 }
317
318 _leave(" = %d [set %hx]", ret, y);
319 return ret;
320 }
321
322 /*
323 * decrypt partial encryption on a packet (level 1 security)
324 */
325 static int rxkad_verify_packet_auth(const struct rxrpc_call *call,
326 struct sk_buff *skb,
327 u32 *_abort_code)
328 {
329 struct rxkad_level1_hdr sechdr;
330 struct rxrpc_skb_priv *sp;
331 struct blkcipher_desc desc;
332 struct rxrpc_crypt iv;
333 struct scatterlist sg[16];
334 struct sk_buff *trailer;
335 u32 data_size, buf;
336 u16 check;
337 int nsg;
338
339 _enter("");
340
341 sp = rxrpc_skb(skb);
342
343 /* we want to decrypt the skbuff in-place */
344 nsg = skb_cow_data(skb, 0, &trailer);
345 if (nsg < 0 || nsg > 16)
346 goto nomem;
347
348 sg_init_table(sg, nsg);
349 skb_to_sgvec(skb, sg, 0, 8);
350
351 /* start the decryption afresh */
352 memset(&iv, 0, sizeof(iv));
353 desc.tfm = call->conn->cipher;
354 desc.info = iv.x;
355 desc.flags = 0;
356
357 crypto_blkcipher_decrypt_iv(&desc, sg, sg, 8);
358
359 /* remove the decrypted packet length */
360 if (skb_copy_bits(skb, 0, &sechdr, sizeof(sechdr)) < 0)
361 goto datalen_error;
362 if (!skb_pull(skb, sizeof(sechdr)))
363 BUG();
364
365 buf = ntohl(sechdr.data_size);
366 data_size = buf & 0xffff;
367
368 check = buf >> 16;
369 check ^= ntohl(sp->hdr.seq ^ sp->hdr.callNumber);
370 check &= 0xffff;
371 if (check != 0) {
372 *_abort_code = RXKADSEALEDINCON;
373 goto protocol_error;
374 }
375
376 /* shorten the packet to remove the padding */
377 if (data_size > skb->len)
378 goto datalen_error;
379 else if (data_size < skb->len)
380 skb->len = data_size;
381
382 _leave(" = 0 [dlen=%x]", data_size);
383 return 0;
384
385 datalen_error:
386 *_abort_code = RXKADDATALEN;
387 protocol_error:
388 _leave(" = -EPROTO");
389 return -EPROTO;
390
391 nomem:
392 _leave(" = -ENOMEM");
393 return -ENOMEM;
394 }
395
396 /*
397 * wholly decrypt a packet (level 2 security)
398 */
399 static int rxkad_verify_packet_encrypt(const struct rxrpc_call *call,
400 struct sk_buff *skb,
401 u32 *_abort_code)
402 {
403 const struct rxrpc_key_payload *payload;
404 struct rxkad_level2_hdr sechdr;
405 struct rxrpc_skb_priv *sp;
406 struct blkcipher_desc desc;
407 struct rxrpc_crypt iv;
408 struct scatterlist _sg[4], *sg;
409 struct sk_buff *trailer;
410 u32 data_size, buf;
411 u16 check;
412 int nsg;
413
414 _enter(",{%d}", skb->len);
415
416 sp = rxrpc_skb(skb);
417
418 /* we want to decrypt the skbuff in-place */
419 nsg = skb_cow_data(skb, 0, &trailer);
420 if (nsg < 0)
421 goto nomem;
422
423 sg = _sg;
424 if (unlikely(nsg > 4)) {
425 sg = kmalloc(sizeof(*sg) * nsg, GFP_NOIO);
426 if (!sg)
427 goto nomem;
428 }
429
430 sg_init_table(sg, nsg);
431 skb_to_sgvec(skb, sg, 0, skb->len);
432
433 /* decrypt from the session key */
434 payload = call->conn->key->payload.data;
435 memcpy(&iv, payload->k.session_key, sizeof(iv));
436 desc.tfm = call->conn->cipher;
437 desc.info = iv.x;
438 desc.flags = 0;
439
440 crypto_blkcipher_decrypt_iv(&desc, sg, sg, skb->len);
441 if (sg != _sg)
442 kfree(sg);
443
444 /* remove the decrypted packet length */
445 if (skb_copy_bits(skb, 0, &sechdr, sizeof(sechdr)) < 0)
446 goto datalen_error;
447 if (!skb_pull(skb, sizeof(sechdr)))
448 BUG();
449
450 buf = ntohl(sechdr.data_size);
451 data_size = buf & 0xffff;
452
453 check = buf >> 16;
454 check ^= ntohl(sp->hdr.seq ^ sp->hdr.callNumber);
455 check &= 0xffff;
456 if (check != 0) {
457 *_abort_code = RXKADSEALEDINCON;
458 goto protocol_error;
459 }
460
461 /* shorten the packet to remove the padding */
462 if (data_size > skb->len)
463 goto datalen_error;
464 else if (data_size < skb->len)
465 skb->len = data_size;
466
467 _leave(" = 0 [dlen=%x]", data_size);
468 return 0;
469
470 datalen_error:
471 *_abort_code = RXKADDATALEN;
472 protocol_error:
473 _leave(" = -EPROTO");
474 return -EPROTO;
475
476 nomem:
477 _leave(" = -ENOMEM");
478 return -ENOMEM;
479 }
480
481 /*
482 * verify the security on a received packet
483 */
484 static int rxkad_verify_packet(const struct rxrpc_call *call,
485 struct sk_buff *skb,
486 u32 *_abort_code)
487 {
488 struct blkcipher_desc desc;
489 struct rxrpc_skb_priv *sp;
490 struct rxrpc_crypt iv;
491 struct scatterlist sg[2];
492 struct {
493 __be32 x[2];
494 } tmpbuf __attribute__((aligned(8))); /* must all be in same page */
495 __be32 x;
496 u16 y;
497 __be16 cksum;
498 int ret;
499
500 sp = rxrpc_skb(skb);
501
502 _enter("{%d{%x}},{#%u}",
503 call->debug_id, key_serial(call->conn->key),
504 ntohl(sp->hdr.seq));
505
506 if (!call->conn->cipher)
507 return 0;
508
509 if (sp->hdr.securityIndex != 2) {
510 *_abort_code = RXKADINCONSISTENCY;
511 _leave(" = -EPROTO [not rxkad]");
512 return -EPROTO;
513 }
514
515 /* continue encrypting from where we left off */
516 memcpy(&iv, call->conn->csum_iv.x, sizeof(iv));
517 desc.tfm = call->conn->cipher;
518 desc.info = iv.x;
519 desc.flags = 0;
520
521 /* validate the security checksum */
522 x = htonl(call->channel << (32 - RXRPC_CIDSHIFT));
523 x |= sp->hdr.seq & cpu_to_be32(0x3fffffff);
524 tmpbuf.x[0] = call->call_id;
525 tmpbuf.x[1] = x;
526
527 sg_init_one(&sg[0], &tmpbuf, sizeof(tmpbuf));
528 sg_init_one(&sg[1], &tmpbuf, sizeof(tmpbuf));
529 crypto_blkcipher_encrypt_iv(&desc, &sg[0], &sg[1], sizeof(tmpbuf));
530
531 y = ntohl(tmpbuf.x[1]);
532 y = (y >> 16) & 0xffff;
533 if (y == 0)
534 y = 1; /* zero checksums are not permitted */
535
536 cksum = htons(y);
537 if (sp->hdr.cksum != cksum) {
538 *_abort_code = RXKADSEALEDINCON;
539 _leave(" = -EPROTO [csum failed]");
540 return -EPROTO;
541 }
542
543 switch (call->conn->security_level) {
544 case RXRPC_SECURITY_PLAIN:
545 ret = 0;
546 break;
547 case RXRPC_SECURITY_AUTH:
548 ret = rxkad_verify_packet_auth(call, skb, _abort_code);
549 break;
550 case RXRPC_SECURITY_ENCRYPT:
551 ret = rxkad_verify_packet_encrypt(call, skb, _abort_code);
552 break;
553 default:
554 ret = -ENOANO;
555 break;
556 }
557
558 _leave(" = %d", ret);
559 return ret;
560 }
561
562 /*
563 * issue a challenge
564 */
565 static int rxkad_issue_challenge(struct rxrpc_connection *conn)
566 {
567 struct rxkad_challenge challenge;
568 struct rxrpc_header hdr;
569 struct msghdr msg;
570 struct kvec iov[2];
571 size_t len;
572 int ret;
573
574 _enter("{%d,%x}", conn->debug_id, key_serial(conn->key));
575
576 ret = key_validate(conn->key);
577 if (ret < 0)
578 return ret;
579
580 get_random_bytes(&conn->security_nonce, sizeof(conn->security_nonce));
581
582 challenge.version = htonl(2);
583 challenge.nonce = htonl(conn->security_nonce);
584 challenge.min_level = htonl(0);
585 challenge.__padding = 0;
586
587 msg.msg_name = &conn->trans->peer->srx.transport.sin;
588 msg.msg_namelen = sizeof(conn->trans->peer->srx.transport.sin);
589 msg.msg_control = NULL;
590 msg.msg_controllen = 0;
591 msg.msg_flags = 0;
592
593 hdr.epoch = conn->epoch;
594 hdr.cid = conn->cid;
595 hdr.callNumber = 0;
596 hdr.seq = 0;
597 hdr.type = RXRPC_PACKET_TYPE_CHALLENGE;
598 hdr.flags = conn->out_clientflag;
599 hdr.userStatus = 0;
600 hdr.securityIndex = conn->security_ix;
601 hdr._rsvd = 0;
602 hdr.serviceId = conn->service_id;
603
604 iov[0].iov_base = &hdr;
605 iov[0].iov_len = sizeof(hdr);
606 iov[1].iov_base = &challenge;
607 iov[1].iov_len = sizeof(challenge);
608
609 len = iov[0].iov_len + iov[1].iov_len;
610
611 hdr.serial = htonl(atomic_inc_return(&conn->serial));
612 _proto("Tx CHALLENGE %%%u", ntohl(hdr.serial));
613
614 ret = kernel_sendmsg(conn->trans->local->socket, &msg, iov, 2, len);
615 if (ret < 0) {
616 _debug("sendmsg failed: %d", ret);
617 return -EAGAIN;
618 }
619
620 _leave(" = 0");
621 return 0;
622 }
623
624 /*
625 * send a Kerberos security response
626 */
627 static int rxkad_send_response(struct rxrpc_connection *conn,
628 struct rxrpc_header *hdr,
629 struct rxkad_response *resp,
630 const struct rxkad_key *s2)
631 {
632 struct msghdr msg;
633 struct kvec iov[3];
634 size_t len;
635 int ret;
636
637 _enter("");
638
639 msg.msg_name = &conn->trans->peer->srx.transport.sin;
640 msg.msg_namelen = sizeof(conn->trans->peer->srx.transport.sin);
641 msg.msg_control = NULL;
642 msg.msg_controllen = 0;
643 msg.msg_flags = 0;
644
645 hdr->epoch = conn->epoch;
646 hdr->seq = 0;
647 hdr->type = RXRPC_PACKET_TYPE_RESPONSE;
648 hdr->flags = conn->out_clientflag;
649 hdr->userStatus = 0;
650 hdr->_rsvd = 0;
651
652 iov[0].iov_base = hdr;
653 iov[0].iov_len = sizeof(*hdr);
654 iov[1].iov_base = resp;
655 iov[1].iov_len = sizeof(*resp);
656 iov[2].iov_base = (void *) s2->ticket;
657 iov[2].iov_len = s2->ticket_len;
658
659 len = iov[0].iov_len + iov[1].iov_len + iov[2].iov_len;
660
661 hdr->serial = htonl(atomic_inc_return(&conn->serial));
662 _proto("Tx RESPONSE %%%u", ntohl(hdr->serial));
663
664 ret = kernel_sendmsg(conn->trans->local->socket, &msg, iov, 3, len);
665 if (ret < 0) {
666 _debug("sendmsg failed: %d", ret);
667 return -EAGAIN;
668 }
669
670 _leave(" = 0");
671 return 0;
672 }
673
674 /*
675 * calculate the response checksum
676 */
677 static void rxkad_calc_response_checksum(struct rxkad_response *response)
678 {
679 u32 csum = 1000003;
680 int loop;
681 u8 *p = (u8 *) response;
682
683 for (loop = sizeof(*response); loop > 0; loop--)
684 csum = csum * 0x10204081 + *p++;
685
686 response->encrypted.checksum = htonl(csum);
687 }
688
689 /*
690 * load a scatterlist with a potentially split-page buffer
691 */
692 static void rxkad_sg_set_buf2(struct scatterlist sg[2],
693 void *buf, size_t buflen)
694 {
695 int nsg = 1;
696
697 sg_init_table(sg, 2);
698
699 sg_set_buf(&sg[0], buf, buflen);
700 if (sg[0].offset + buflen > PAGE_SIZE) {
701 /* the buffer was split over two pages */
702 sg[0].length = PAGE_SIZE - sg[0].offset;
703 sg_set_buf(&sg[1], buf + sg[0].length, buflen - sg[0].length);
704 nsg++;
705 }
706
707 sg_mark_end(&sg[nsg - 1]);
708
709 ASSERTCMP(sg[0].length + sg[1].length, ==, buflen);
710 }
711
712 /*
713 * encrypt the response packet
714 */
715 static void rxkad_encrypt_response(struct rxrpc_connection *conn,
716 struct rxkad_response *resp,
717 const struct rxkad_key *s2)
718 {
719 struct blkcipher_desc desc;
720 struct rxrpc_crypt iv;
721 struct scatterlist sg[2];
722
723 /* continue encrypting from where we left off */
724 memcpy(&iv, s2->session_key, sizeof(iv));
725 desc.tfm = conn->cipher;
726 desc.info = iv.x;
727 desc.flags = 0;
728
729 rxkad_sg_set_buf2(sg, &resp->encrypted, sizeof(resp->encrypted));
730 crypto_blkcipher_encrypt_iv(&desc, sg, sg, sizeof(resp->encrypted));
731 }
732
733 /*
734 * respond to a challenge packet
735 */
736 static int rxkad_respond_to_challenge(struct rxrpc_connection *conn,
737 struct sk_buff *skb,
738 u32 *_abort_code)
739 {
740 const struct rxrpc_key_payload *payload;
741 struct rxkad_challenge challenge;
742 struct rxkad_response resp
743 __attribute__((aligned(8))); /* must be aligned for crypto */
744 struct rxrpc_skb_priv *sp;
745 u32 version, nonce, min_level, abort_code;
746 int ret;
747
748 _enter("{%d,%x}", conn->debug_id, key_serial(conn->key));
749
750 if (!conn->key) {
751 _leave(" = -EPROTO [no key]");
752 return -EPROTO;
753 }
754
755 ret = key_validate(conn->key);
756 if (ret < 0) {
757 *_abort_code = RXKADEXPIRED;
758 return ret;
759 }
760
761 abort_code = RXKADPACKETSHORT;
762 sp = rxrpc_skb(skb);
763 if (skb_copy_bits(skb, 0, &challenge, sizeof(challenge)) < 0)
764 goto protocol_error;
765
766 version = ntohl(challenge.version);
767 nonce = ntohl(challenge.nonce);
768 min_level = ntohl(challenge.min_level);
769
770 _proto("Rx CHALLENGE %%%u { v=%u n=%u ml=%u }",
771 ntohl(sp->hdr.serial), version, nonce, min_level);
772
773 abort_code = RXKADINCONSISTENCY;
774 if (version != RXKAD_VERSION)
775 goto protocol_error;
776
777 abort_code = RXKADLEVELFAIL;
778 if (conn->security_level < min_level)
779 goto protocol_error;
780
781 payload = conn->key->payload.data;
782
783 /* build the response packet */
784 memset(&resp, 0, sizeof(resp));
785
786 resp.version = RXKAD_VERSION;
787 resp.encrypted.epoch = conn->epoch;
788 resp.encrypted.cid = conn->cid;
789 resp.encrypted.securityIndex = htonl(conn->security_ix);
790 resp.encrypted.call_id[0] =
791 (conn->channels[0] ? conn->channels[0]->call_id : 0);
792 resp.encrypted.call_id[1] =
793 (conn->channels[1] ? conn->channels[1]->call_id : 0);
794 resp.encrypted.call_id[2] =
795 (conn->channels[2] ? conn->channels[2]->call_id : 0);
796 resp.encrypted.call_id[3] =
797 (conn->channels[3] ? conn->channels[3]->call_id : 0);
798 resp.encrypted.inc_nonce = htonl(nonce + 1);
799 resp.encrypted.level = htonl(conn->security_level);
800 resp.kvno = htonl(payload->k.kvno);
801 resp.ticket_len = htonl(payload->k.ticket_len);
802
803 /* calculate the response checksum and then do the encryption */
804 rxkad_calc_response_checksum(&resp);
805 rxkad_encrypt_response(conn, &resp, &payload->k);
806 return rxkad_send_response(conn, &sp->hdr, &resp, &payload->k);
807
808 protocol_error:
809 *_abort_code = abort_code;
810 _leave(" = -EPROTO [%d]", abort_code);
811 return -EPROTO;
812 }
813
814 /*
815 * decrypt the kerberos IV ticket in the response
816 */
817 static int rxkad_decrypt_ticket(struct rxrpc_connection *conn,
818 void *ticket, size_t ticket_len,
819 struct rxrpc_crypt *_session_key,
820 time_t *_expiry,
821 u32 *_abort_code)
822 {
823 struct blkcipher_desc desc;
824 struct rxrpc_crypt iv, key;
825 struct scatterlist sg[1];
826 struct in_addr addr;
827 unsigned life;
828 time_t issue, now;
829 bool little_endian;
830 int ret;
831 u8 *p, *q, *name, *end;
832
833 _enter("{%d},{%x}", conn->debug_id, key_serial(conn->server_key));
834
835 *_expiry = 0;
836
837 ret = key_validate(conn->server_key);
838 if (ret < 0) {
839 switch (ret) {
840 case -EKEYEXPIRED:
841 *_abort_code = RXKADEXPIRED;
842 goto error;
843 default:
844 *_abort_code = RXKADNOAUTH;
845 goto error;
846 }
847 }
848
849 ASSERT(conn->server_key->payload.data != NULL);
850 ASSERTCMP((unsigned long) ticket & 7UL, ==, 0);
851
852 memcpy(&iv, &conn->server_key->type_data, sizeof(iv));
853
854 desc.tfm = conn->server_key->payload.data;
855 desc.info = iv.x;
856 desc.flags = 0;
857
858 sg_init_one(&sg[0], ticket, ticket_len);
859 crypto_blkcipher_decrypt_iv(&desc, sg, sg, ticket_len);
860
861 p = ticket;
862 end = p + ticket_len;
863
864 #define Z(size) \
865 ({ \
866 u8 *__str = p; \
867 q = memchr(p, 0, end - p); \
868 if (!q || q - p > (size)) \
869 goto bad_ticket; \
870 for (; p < q; p++) \
871 if (!isprint(*p)) \
872 goto bad_ticket; \
873 p++; \
874 __str; \
875 })
876
877 /* extract the ticket flags */
878 _debug("KIV FLAGS: %x", *p);
879 little_endian = *p & 1;
880 p++;
881
882 /* extract the authentication name */
883 name = Z(ANAME_SZ);
884 _debug("KIV ANAME: %s", name);
885
886 /* extract the principal's instance */
887 name = Z(INST_SZ);
888 _debug("KIV INST : %s", name);
889
890 /* extract the principal's authentication domain */
891 name = Z(REALM_SZ);
892 _debug("KIV REALM: %s", name);
893
894 if (end - p < 4 + 8 + 4 + 2)
895 goto bad_ticket;
896
897 /* get the IPv4 address of the entity that requested the ticket */
898 memcpy(&addr, p, sizeof(addr));
899 p += 4;
900 _debug("KIV ADDR : "NIPQUAD_FMT, NIPQUAD(addr));
901
902 /* get the session key from the ticket */
903 memcpy(&key, p, sizeof(key));
904 p += 8;
905 _debug("KIV KEY : %08x %08x", ntohl(key.n[0]), ntohl(key.n[1]));
906 memcpy(_session_key, &key, sizeof(key));
907
908 /* get the ticket's lifetime */
909 life = *p++ * 5 * 60;
910 _debug("KIV LIFE : %u", life);
911
912 /* get the issue time of the ticket */
913 if (little_endian) {
914 __le32 stamp;
915 memcpy(&stamp, p, 4);
916 issue = le32_to_cpu(stamp);
917 } else {
918 __be32 stamp;
919 memcpy(&stamp, p, 4);
920 issue = be32_to_cpu(stamp);
921 }
922 p += 4;
923 now = get_seconds();
924 _debug("KIV ISSUE: %lx [%lx]", issue, now);
925
926 /* check the ticket is in date */
927 if (issue > now) {
928 *_abort_code = RXKADNOAUTH;
929 ret = -EKEYREJECTED;
930 goto error;
931 }
932
933 if (issue < now - life) {
934 *_abort_code = RXKADEXPIRED;
935 ret = -EKEYEXPIRED;
936 goto error;
937 }
938
939 *_expiry = issue + life;
940
941 /* get the service name */
942 name = Z(SNAME_SZ);
943 _debug("KIV SNAME: %s", name);
944
945 /* get the service instance name */
946 name = Z(INST_SZ);
947 _debug("KIV SINST: %s", name);
948
949 ret = 0;
950 error:
951 _leave(" = %d", ret);
952 return ret;
953
954 bad_ticket:
955 *_abort_code = RXKADBADTICKET;
956 ret = -EBADMSG;
957 goto error;
958 }
959
960 /*
961 * decrypt the response packet
962 */
963 static void rxkad_decrypt_response(struct rxrpc_connection *conn,
964 struct rxkad_response *resp,
965 const struct rxrpc_crypt *session_key)
966 {
967 struct blkcipher_desc desc;
968 struct scatterlist sg[2];
969 struct rxrpc_crypt iv;
970
971 _enter(",,%08x%08x",
972 ntohl(session_key->n[0]), ntohl(session_key->n[1]));
973
974 ASSERT(rxkad_ci != NULL);
975
976 mutex_lock(&rxkad_ci_mutex);
977 if (crypto_blkcipher_setkey(rxkad_ci, session_key->x,
978 sizeof(*session_key)) < 0)
979 BUG();
980
981 memcpy(&iv, session_key, sizeof(iv));
982 desc.tfm = rxkad_ci;
983 desc.info = iv.x;
984 desc.flags = 0;
985
986 rxkad_sg_set_buf2(sg, &resp->encrypted, sizeof(resp->encrypted));
987 crypto_blkcipher_decrypt_iv(&desc, sg, sg, sizeof(resp->encrypted));
988 mutex_unlock(&rxkad_ci_mutex);
989
990 _leave("");
991 }
992
993 /*
994 * verify a response
995 */
996 static int rxkad_verify_response(struct rxrpc_connection *conn,
997 struct sk_buff *skb,
998 u32 *_abort_code)
999 {
1000 struct rxkad_response response
1001 __attribute__((aligned(8))); /* must be aligned for crypto */
1002 struct rxrpc_skb_priv *sp;
1003 struct rxrpc_crypt session_key;
1004 time_t expiry;
1005 void *ticket;
1006 u32 abort_code, version, kvno, ticket_len, level;
1007 __be32 csum;
1008 int ret;
1009
1010 _enter("{%d,%x}", conn->debug_id, key_serial(conn->server_key));
1011
1012 abort_code = RXKADPACKETSHORT;
1013 if (skb_copy_bits(skb, 0, &response, sizeof(response)) < 0)
1014 goto protocol_error;
1015 if (!pskb_pull(skb, sizeof(response)))
1016 BUG();
1017
1018 version = ntohl(response.version);
1019 ticket_len = ntohl(response.ticket_len);
1020 kvno = ntohl(response.kvno);
1021 sp = rxrpc_skb(skb);
1022 _proto("Rx RESPONSE %%%u { v=%u kv=%u tl=%u }",
1023 ntohl(sp->hdr.serial), version, kvno, ticket_len);
1024
1025 abort_code = RXKADINCONSISTENCY;
1026 if (version != RXKAD_VERSION)
1027 goto protocol_error;
1028
1029 abort_code = RXKADTICKETLEN;
1030 if (ticket_len < 4 || ticket_len > MAXKRB5TICKETLEN)
1031 goto protocol_error;
1032
1033 abort_code = RXKADUNKNOWNKEY;
1034 if (kvno >= RXKAD_TKT_TYPE_KERBEROS_V5)
1035 goto protocol_error;
1036
1037 /* extract the kerberos ticket and decrypt and decode it */
1038 ticket = kmalloc(ticket_len, GFP_NOFS);
1039 if (!ticket)
1040 return -ENOMEM;
1041
1042 abort_code = RXKADPACKETSHORT;
1043 if (skb_copy_bits(skb, 0, ticket, ticket_len) < 0)
1044 goto protocol_error_free;
1045
1046 ret = rxkad_decrypt_ticket(conn, ticket, ticket_len, &session_key,
1047 &expiry, &abort_code);
1048 if (ret < 0) {
1049 *_abort_code = abort_code;
1050 kfree(ticket);
1051 return ret;
1052 }
1053
1054 /* use the session key from inside the ticket to decrypt the
1055 * response */
1056 rxkad_decrypt_response(conn, &response, &session_key);
1057
1058 abort_code = RXKADSEALEDINCON;
1059 if (response.encrypted.epoch != conn->epoch)
1060 goto protocol_error_free;
1061 if (response.encrypted.cid != conn->cid)
1062 goto protocol_error_free;
1063 if (ntohl(response.encrypted.securityIndex) != conn->security_ix)
1064 goto protocol_error_free;
1065 csum = response.encrypted.checksum;
1066 response.encrypted.checksum = 0;
1067 rxkad_calc_response_checksum(&response);
1068 if (response.encrypted.checksum != csum)
1069 goto protocol_error_free;
1070
1071 if (ntohl(response.encrypted.call_id[0]) > INT_MAX ||
1072 ntohl(response.encrypted.call_id[1]) > INT_MAX ||
1073 ntohl(response.encrypted.call_id[2]) > INT_MAX ||
1074 ntohl(response.encrypted.call_id[3]) > INT_MAX)
1075 goto protocol_error_free;
1076
1077 abort_code = RXKADOUTOFSEQUENCE;
1078 if (response.encrypted.inc_nonce != htonl(conn->security_nonce + 1))
1079 goto protocol_error_free;
1080
1081 abort_code = RXKADLEVELFAIL;
1082 level = ntohl(response.encrypted.level);
1083 if (level > RXRPC_SECURITY_ENCRYPT)
1084 goto protocol_error_free;
1085 conn->security_level = level;
1086
1087 /* create a key to hold the security data and expiration time - after
1088 * this the connection security can be handled in exactly the same way
1089 * as for a client connection */
1090 ret = rxrpc_get_server_data_key(conn, &session_key, expiry, kvno);
1091 if (ret < 0) {
1092 kfree(ticket);
1093 return ret;
1094 }
1095
1096 kfree(ticket);
1097 _leave(" = 0");
1098 return 0;
1099
1100 protocol_error_free:
1101 kfree(ticket);
1102 protocol_error:
1103 *_abort_code = abort_code;
1104 _leave(" = -EPROTO [%d]", abort_code);
1105 return -EPROTO;
1106 }
1107
1108 /*
1109 * clear the connection security
1110 */
1111 static void rxkad_clear(struct rxrpc_connection *conn)
1112 {
1113 _enter("");
1114
1115 if (conn->cipher)
1116 crypto_free_blkcipher(conn->cipher);
1117 }
1118
1119 /*
1120 * RxRPC Kerberos-based security
1121 */
1122 static struct rxrpc_security rxkad = {
1123 .owner = THIS_MODULE,
1124 .name = "rxkad",
1125 .security_index = RXKAD_VERSION,
1126 .init_connection_security = rxkad_init_connection_security,
1127 .prime_packet_security = rxkad_prime_packet_security,
1128 .secure_packet = rxkad_secure_packet,
1129 .verify_packet = rxkad_verify_packet,
1130 .issue_challenge = rxkad_issue_challenge,
1131 .respond_to_challenge = rxkad_respond_to_challenge,
1132 .verify_response = rxkad_verify_response,
1133 .clear = rxkad_clear,
1134 };
1135
1136 static __init int rxkad_init(void)
1137 {
1138 _enter("");
1139
1140 /* pin the cipher we need so that the crypto layer doesn't invoke
1141 * keventd to go get it */
1142 rxkad_ci = crypto_alloc_blkcipher("pcbc(fcrypt)", 0, CRYPTO_ALG_ASYNC);
1143 if (IS_ERR(rxkad_ci))
1144 return PTR_ERR(rxkad_ci);
1145
1146 return rxrpc_register_security(&rxkad);
1147 }
1148
1149 module_init(rxkad_init);
1150
1151 static __exit void rxkad_exit(void)
1152 {
1153 _enter("");
1154
1155 rxrpc_unregister_security(&rxkad);
1156 crypto_free_blkcipher(rxkad_ci);
1157 }
1158
1159 module_exit(rxkad_exit);
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