xref: /linux/net/rxrpc/rxkad.c (revision 1b98f357dadd6ea613a435fbaef1a5dd7b35fd21)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* Kerberos-based RxRPC security
3  *
4  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
5  * Written by David Howells (dhowells@redhat.com)
6  */
7 
8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9 
10 #include <crypto/skcipher.h>
11 #include <linux/module.h>
12 #include <linux/net.h>
13 #include <linux/skbuff.h>
14 #include <linux/udp.h>
15 #include <linux/scatterlist.h>
16 #include <linux/ctype.h>
17 #include <linux/slab.h>
18 #include <linux/key-type.h>
19 #include <net/sock.h>
20 #include <net/af_rxrpc.h>
21 #include <keys/rxrpc-type.h>
22 #include "ar-internal.h"
23 
24 #define RXKAD_VERSION			2
25 #define MAXKRB5TICKETLEN		1024
26 #define RXKAD_TKT_TYPE_KERBEROS_V5	256
27 #define ANAME_SZ			40	/* size of authentication name */
28 #define INST_SZ				40	/* size of principal's instance */
29 #define REALM_SZ			40	/* size of principal's auth domain */
30 #define SNAME_SZ			40	/* size of service name */
31 #define RXKAD_ALIGN			8
32 
33 struct rxkad_level1_hdr {
34 	__be32	data_size;	/* true data size (excluding padding) */
35 };
36 
37 struct rxkad_level2_hdr {
38 	__be32	data_size;	/* true data size (excluding padding) */
39 	__be32	checksum;	/* decrypted data checksum */
40 };
41 
42 static int rxkad_prime_packet_security(struct rxrpc_connection *conn,
43 				       struct crypto_sync_skcipher *ci);
44 
45 /*
46  * this holds a pinned cipher so that keventd doesn't get called by the cipher
47  * alloc routine, but since we have it to hand, we use it to decrypt RESPONSE
48  * packets
49  */
50 static struct crypto_sync_skcipher *rxkad_ci;
51 static struct skcipher_request *rxkad_ci_req;
52 static DEFINE_MUTEX(rxkad_ci_mutex);
53 
54 /*
55  * Parse the information from a server key
56  *
57  * The data should be the 8-byte secret key.
58  */
59 static int rxkad_preparse_server_key(struct key_preparsed_payload *prep)
60 {
61 	struct crypto_skcipher *ci;
62 
63 	if (prep->datalen != 8)
64 		return -EINVAL;
65 
66 	memcpy(&prep->payload.data[2], prep->data, 8);
67 
68 	ci = crypto_alloc_skcipher("pcbc(des)", 0, CRYPTO_ALG_ASYNC);
69 	if (IS_ERR(ci)) {
70 		_leave(" = %ld", PTR_ERR(ci));
71 		return PTR_ERR(ci);
72 	}
73 
74 	if (crypto_skcipher_setkey(ci, prep->data, 8) < 0)
75 		BUG();
76 
77 	prep->payload.data[0] = ci;
78 	_leave(" = 0");
79 	return 0;
80 }
81 
82 static void rxkad_free_preparse_server_key(struct key_preparsed_payload *prep)
83 {
84 
85 	if (prep->payload.data[0])
86 		crypto_free_skcipher(prep->payload.data[0]);
87 }
88 
89 static void rxkad_destroy_server_key(struct key *key)
90 {
91 	if (key->payload.data[0]) {
92 		crypto_free_skcipher(key->payload.data[0]);
93 		key->payload.data[0] = NULL;
94 	}
95 }
96 
97 /*
98  * initialise connection security
99  */
100 static int rxkad_init_connection_security(struct rxrpc_connection *conn,
101 					  struct rxrpc_key_token *token)
102 {
103 	struct crypto_sync_skcipher *ci;
104 	int ret;
105 
106 	_enter("{%d},{%x}", conn->debug_id, key_serial(conn->key));
107 
108 	conn->security_ix = token->security_index;
109 
110 	ci = crypto_alloc_sync_skcipher("pcbc(fcrypt)", 0, 0);
111 	if (IS_ERR(ci)) {
112 		_debug("no cipher");
113 		ret = PTR_ERR(ci);
114 		goto error;
115 	}
116 
117 	if (crypto_sync_skcipher_setkey(ci, token->kad->session_key,
118 				   sizeof(token->kad->session_key)) < 0)
119 		BUG();
120 
121 	switch (conn->security_level) {
122 	case RXRPC_SECURITY_PLAIN:
123 	case RXRPC_SECURITY_AUTH:
124 	case RXRPC_SECURITY_ENCRYPT:
125 		break;
126 	default:
127 		ret = -EKEYREJECTED;
128 		goto error;
129 	}
130 
131 	ret = rxkad_prime_packet_security(conn, ci);
132 	if (ret < 0)
133 		goto error_ci;
134 
135 	conn->rxkad.cipher = ci;
136 	return 0;
137 
138 error_ci:
139 	crypto_free_sync_skcipher(ci);
140 error:
141 	_leave(" = %d", ret);
142 	return ret;
143 }
144 
145 /*
146  * Work out how much data we can put in a packet.
147  */
148 static struct rxrpc_txbuf *rxkad_alloc_txbuf(struct rxrpc_call *call, size_t remain, gfp_t gfp)
149 {
150 	struct rxrpc_txbuf *txb;
151 	size_t shdr, alloc, limit, part;
152 
153 	remain = umin(remain, 65535 - sizeof(struct rxrpc_wire_header));
154 
155 	switch (call->conn->security_level) {
156 	default:
157 		alloc = umin(remain, RXRPC_JUMBO_DATALEN);
158 		return rxrpc_alloc_data_txbuf(call, alloc, 1, gfp);
159 	case RXRPC_SECURITY_AUTH:
160 		shdr = sizeof(struct rxkad_level1_hdr);
161 		break;
162 	case RXRPC_SECURITY_ENCRYPT:
163 		shdr = sizeof(struct rxkad_level2_hdr);
164 		break;
165 	}
166 
167 	limit = round_down(RXRPC_JUMBO_DATALEN, RXKAD_ALIGN) - shdr;
168 	if (remain < limit) {
169 		part = remain;
170 		alloc = round_up(shdr + part, RXKAD_ALIGN);
171 	} else {
172 		part = limit;
173 		alloc = RXRPC_JUMBO_DATALEN;
174 	}
175 
176 	txb = rxrpc_alloc_data_txbuf(call, alloc, RXKAD_ALIGN, gfp);
177 	if (!txb)
178 		return NULL;
179 
180 	txb->crypto_header	= 0;
181 	txb->sec_header		= shdr;
182 	txb->offset		+= shdr;
183 	txb->space		= part;
184 	return txb;
185 }
186 
187 /*
188  * prime the encryption state with the invariant parts of a connection's
189  * description
190  */
191 static int rxkad_prime_packet_security(struct rxrpc_connection *conn,
192 				       struct crypto_sync_skcipher *ci)
193 {
194 	struct skcipher_request *req;
195 	struct rxrpc_key_token *token;
196 	struct scatterlist sg;
197 	struct rxrpc_crypt iv;
198 	__be32 *tmpbuf;
199 	size_t tmpsize = 4 * sizeof(__be32);
200 
201 	_enter("");
202 
203 	if (!conn->key)
204 		return 0;
205 
206 	tmpbuf = kmalloc(tmpsize, GFP_KERNEL);
207 	if (!tmpbuf)
208 		return -ENOMEM;
209 
210 	req = skcipher_request_alloc(&ci->base, GFP_NOFS);
211 	if (!req) {
212 		kfree(tmpbuf);
213 		return -ENOMEM;
214 	}
215 
216 	token = conn->key->payload.data[0];
217 	memcpy(&iv, token->kad->session_key, sizeof(iv));
218 
219 	tmpbuf[0] = htonl(conn->proto.epoch);
220 	tmpbuf[1] = htonl(conn->proto.cid);
221 	tmpbuf[2] = 0;
222 	tmpbuf[3] = htonl(conn->security_ix);
223 
224 	sg_init_one(&sg, tmpbuf, tmpsize);
225 	skcipher_request_set_sync_tfm(req, ci);
226 	skcipher_request_set_callback(req, 0, NULL, NULL);
227 	skcipher_request_set_crypt(req, &sg, &sg, tmpsize, iv.x);
228 	crypto_skcipher_encrypt(req);
229 	skcipher_request_free(req);
230 
231 	memcpy(&conn->rxkad.csum_iv, tmpbuf + 2, sizeof(conn->rxkad.csum_iv));
232 	kfree(tmpbuf);
233 	_leave(" = 0");
234 	return 0;
235 }
236 
237 /*
238  * Allocate and prepare the crypto request on a call.  For any particular call,
239  * this is called serially for the packets, so no lock should be necessary.
240  */
241 static struct skcipher_request *rxkad_get_call_crypto(struct rxrpc_call *call)
242 {
243 	struct crypto_skcipher *tfm = &call->conn->rxkad.cipher->base;
244 
245 	return skcipher_request_alloc(tfm, GFP_NOFS);
246 }
247 
248 /*
249  * Clean up the crypto on a call.
250  */
251 static void rxkad_free_call_crypto(struct rxrpc_call *call)
252 {
253 }
254 
255 /*
256  * partially encrypt a packet (level 1 security)
257  */
258 static int rxkad_secure_packet_auth(const struct rxrpc_call *call,
259 				    struct rxrpc_txbuf *txb,
260 				    struct skcipher_request *req)
261 {
262 	struct rxkad_level1_hdr *hdr = txb->data;
263 	struct rxrpc_crypt iv;
264 	struct scatterlist sg;
265 	size_t pad;
266 	u16 check;
267 
268 	_enter("");
269 
270 	check = txb->seq ^ call->call_id;
271 	hdr->data_size = htonl((u32)check << 16 | txb->len);
272 
273 	txb->pkt_len = sizeof(struct rxkad_level1_hdr) + txb->len;
274 	pad = txb->pkt_len;
275 	pad = RXKAD_ALIGN - pad;
276 	pad &= RXKAD_ALIGN - 1;
277 	if (pad) {
278 		memset(txb->data + txb->offset, 0, pad);
279 		txb->pkt_len += pad;
280 	}
281 
282 	/* start the encryption afresh */
283 	memset(&iv, 0, sizeof(iv));
284 
285 	sg_init_one(&sg, hdr, 8);
286 	skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher);
287 	skcipher_request_set_callback(req, 0, NULL, NULL);
288 	skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x);
289 	crypto_skcipher_encrypt(req);
290 	skcipher_request_zero(req);
291 
292 	_leave(" = 0");
293 	return 0;
294 }
295 
296 /*
297  * wholly encrypt a packet (level 2 security)
298  */
299 static int rxkad_secure_packet_encrypt(const struct rxrpc_call *call,
300 				       struct rxrpc_txbuf *txb,
301 				       struct skcipher_request *req)
302 {
303 	const struct rxrpc_key_token *token;
304 	struct rxkad_level2_hdr *rxkhdr = txb->data;
305 	struct rxrpc_crypt iv;
306 	struct scatterlist sg;
307 	size_t content, pad;
308 	u16 check;
309 	int ret;
310 
311 	_enter("");
312 
313 	check = txb->seq ^ call->call_id;
314 
315 	rxkhdr->data_size = htonl(txb->len | (u32)check << 16);
316 	rxkhdr->checksum = 0;
317 
318 	content = sizeof(struct rxkad_level2_hdr) + txb->len;
319 	txb->pkt_len = round_up(content, RXKAD_ALIGN);
320 	pad = txb->pkt_len - content;
321 	if (pad)
322 		memset(txb->data + txb->offset, 0, pad);
323 
324 	/* encrypt from the session key */
325 	token = call->conn->key->payload.data[0];
326 	memcpy(&iv, token->kad->session_key, sizeof(iv));
327 
328 	sg_init_one(&sg, rxkhdr, txb->pkt_len);
329 	skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher);
330 	skcipher_request_set_callback(req, 0, NULL, NULL);
331 	skcipher_request_set_crypt(req, &sg, &sg, txb->pkt_len, iv.x);
332 	ret = crypto_skcipher_encrypt(req);
333 	skcipher_request_zero(req);
334 	return ret;
335 }
336 
337 /*
338  * checksum an RxRPC packet header
339  */
340 static int rxkad_secure_packet(struct rxrpc_call *call, struct rxrpc_txbuf *txb)
341 {
342 	struct skcipher_request	*req;
343 	struct rxrpc_crypt iv;
344 	struct scatterlist sg;
345 	union {
346 		__be32 buf[2];
347 	} crypto __aligned(8);
348 	u32 x, y;
349 	int ret;
350 
351 	_enter("{%d{%x}},{#%u},%u,",
352 	       call->debug_id, key_serial(call->conn->key),
353 	       txb->seq, txb->len);
354 
355 	if (!call->conn->rxkad.cipher)
356 		return 0;
357 
358 	ret = key_validate(call->conn->key);
359 	if (ret < 0)
360 		return ret;
361 
362 	req = rxkad_get_call_crypto(call);
363 	if (!req)
364 		return -ENOMEM;
365 
366 	/* continue encrypting from where we left off */
367 	memcpy(&iv, call->conn->rxkad.csum_iv.x, sizeof(iv));
368 
369 	/* calculate the security checksum */
370 	x = (call->cid & RXRPC_CHANNELMASK) << (32 - RXRPC_CIDSHIFT);
371 	x |= txb->seq & 0x3fffffff;
372 	crypto.buf[0] = htonl(call->call_id);
373 	crypto.buf[1] = htonl(x);
374 
375 	sg_init_one(&sg, crypto.buf, 8);
376 	skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher);
377 	skcipher_request_set_callback(req, 0, NULL, NULL);
378 	skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x);
379 	crypto_skcipher_encrypt(req);
380 	skcipher_request_zero(req);
381 
382 	y = ntohl(crypto.buf[1]);
383 	y = (y >> 16) & 0xffff;
384 	if (y == 0)
385 		y = 1; /* zero checksums are not permitted */
386 	txb->cksum = htons(y);
387 
388 	switch (call->conn->security_level) {
389 	case RXRPC_SECURITY_PLAIN:
390 		txb->pkt_len = txb->len;
391 		ret = 0;
392 		break;
393 	case RXRPC_SECURITY_AUTH:
394 		ret = rxkad_secure_packet_auth(call, txb, req);
395 		if (txb->alloc_size == RXRPC_JUMBO_DATALEN)
396 			txb->jumboable = true;
397 		break;
398 	case RXRPC_SECURITY_ENCRYPT:
399 		ret = rxkad_secure_packet_encrypt(call, txb, req);
400 		if (txb->alloc_size == RXRPC_JUMBO_DATALEN)
401 			txb->jumboable = true;
402 		break;
403 	default:
404 		ret = -EPERM;
405 		break;
406 	}
407 
408 	/* Clear excess space in the packet */
409 	if (txb->pkt_len < txb->alloc_size) {
410 		size_t gap = txb->alloc_size - txb->pkt_len;
411 		void *p = txb->data;
412 
413 		memset(p + txb->pkt_len, 0, gap);
414 	}
415 
416 	skcipher_request_free(req);
417 	_leave(" = %d [set %x]", ret, y);
418 	return ret;
419 }
420 
421 /*
422  * decrypt partial encryption on a packet (level 1 security)
423  */
424 static int rxkad_verify_packet_1(struct rxrpc_call *call, struct sk_buff *skb,
425 				 rxrpc_seq_t seq,
426 				 struct skcipher_request *req)
427 {
428 	struct rxkad_level1_hdr sechdr;
429 	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
430 	struct rxrpc_crypt iv;
431 	struct scatterlist sg[16];
432 	u32 data_size, buf;
433 	u16 check;
434 	int ret;
435 
436 	_enter("");
437 
438 	if (sp->len < 8)
439 		return rxrpc_abort_eproto(call, skb, RXKADSEALEDINCON,
440 					  rxkad_abort_1_short_header);
441 
442 	/* Decrypt the skbuff in-place.  TODO: We really want to decrypt
443 	 * directly into the target buffer.
444 	 */
445 	sg_init_table(sg, ARRAY_SIZE(sg));
446 	ret = skb_to_sgvec(skb, sg, sp->offset, 8);
447 	if (unlikely(ret < 0))
448 		return ret;
449 
450 	/* start the decryption afresh */
451 	memset(&iv, 0, sizeof(iv));
452 
453 	skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher);
454 	skcipher_request_set_callback(req, 0, NULL, NULL);
455 	skcipher_request_set_crypt(req, sg, sg, 8, iv.x);
456 	crypto_skcipher_decrypt(req);
457 	skcipher_request_zero(req);
458 
459 	/* Extract the decrypted packet length */
460 	if (skb_copy_bits(skb, sp->offset, &sechdr, sizeof(sechdr)) < 0)
461 		return rxrpc_abort_eproto(call, skb, RXKADDATALEN,
462 					  rxkad_abort_1_short_encdata);
463 	sp->offset += sizeof(sechdr);
464 	sp->len    -= sizeof(sechdr);
465 
466 	buf = ntohl(sechdr.data_size);
467 	data_size = buf & 0xffff;
468 
469 	check = buf >> 16;
470 	check ^= seq ^ call->call_id;
471 	check &= 0xffff;
472 	if (check != 0)
473 		return rxrpc_abort_eproto(call, skb, RXKADSEALEDINCON,
474 					  rxkad_abort_1_short_check);
475 	if (data_size > sp->len)
476 		return rxrpc_abort_eproto(call, skb, RXKADDATALEN,
477 					  rxkad_abort_1_short_data);
478 	sp->len = data_size;
479 
480 	_leave(" = 0 [dlen=%x]", data_size);
481 	return 0;
482 }
483 
484 /*
485  * wholly decrypt a packet (level 2 security)
486  */
487 static int rxkad_verify_packet_2(struct rxrpc_call *call, struct sk_buff *skb,
488 				 rxrpc_seq_t seq,
489 				 struct skcipher_request *req)
490 {
491 	const struct rxrpc_key_token *token;
492 	struct rxkad_level2_hdr sechdr;
493 	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
494 	struct rxrpc_crypt iv;
495 	struct scatterlist _sg[4], *sg;
496 	u32 data_size, buf;
497 	u16 check;
498 	int nsg, ret;
499 
500 	_enter(",{%d}", sp->len);
501 
502 	if (sp->len < 8)
503 		return rxrpc_abort_eproto(call, skb, RXKADSEALEDINCON,
504 					  rxkad_abort_2_short_header);
505 
506 	/* Decrypt the skbuff in-place.  TODO: We really want to decrypt
507 	 * directly into the target buffer.
508 	 */
509 	sg = _sg;
510 	nsg = skb_shinfo(skb)->nr_frags + 1;
511 	if (nsg <= 4) {
512 		nsg = 4;
513 	} else {
514 		sg = kmalloc_array(nsg, sizeof(*sg), GFP_NOIO);
515 		if (!sg)
516 			return -ENOMEM;
517 	}
518 
519 	sg_init_table(sg, nsg);
520 	ret = skb_to_sgvec(skb, sg, sp->offset, sp->len);
521 	if (unlikely(ret < 0)) {
522 		if (sg != _sg)
523 			kfree(sg);
524 		return ret;
525 	}
526 
527 	/* decrypt from the session key */
528 	token = call->conn->key->payload.data[0];
529 	memcpy(&iv, token->kad->session_key, sizeof(iv));
530 
531 	skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher);
532 	skcipher_request_set_callback(req, 0, NULL, NULL);
533 	skcipher_request_set_crypt(req, sg, sg, sp->len, iv.x);
534 	crypto_skcipher_decrypt(req);
535 	skcipher_request_zero(req);
536 	if (sg != _sg)
537 		kfree(sg);
538 
539 	/* Extract the decrypted packet length */
540 	if (skb_copy_bits(skb, sp->offset, &sechdr, sizeof(sechdr)) < 0)
541 		return rxrpc_abort_eproto(call, skb, RXKADDATALEN,
542 					  rxkad_abort_2_short_len);
543 	sp->offset += sizeof(sechdr);
544 	sp->len    -= sizeof(sechdr);
545 
546 	buf = ntohl(sechdr.data_size);
547 	data_size = buf & 0xffff;
548 
549 	check = buf >> 16;
550 	check ^= seq ^ call->call_id;
551 	check &= 0xffff;
552 	if (check != 0)
553 		return rxrpc_abort_eproto(call, skb, RXKADSEALEDINCON,
554 					  rxkad_abort_2_short_check);
555 
556 	if (data_size > sp->len)
557 		return rxrpc_abort_eproto(call, skb, RXKADDATALEN,
558 					  rxkad_abort_2_short_data);
559 
560 	sp->len = data_size;
561 	_leave(" = 0 [dlen=%x]", data_size);
562 	return 0;
563 }
564 
565 /*
566  * Verify the security on a received packet and the subpackets therein.
567  */
568 static int rxkad_verify_packet(struct rxrpc_call *call, struct sk_buff *skb)
569 {
570 	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
571 	struct skcipher_request	*req;
572 	struct rxrpc_crypt iv;
573 	struct scatterlist sg;
574 	union {
575 		__be32 buf[2];
576 	} crypto __aligned(8);
577 	rxrpc_seq_t seq = sp->hdr.seq;
578 	int ret;
579 	u16 cksum;
580 	u32 x, y;
581 
582 	_enter("{%d{%x}},{#%u}",
583 	       call->debug_id, key_serial(call->conn->key), seq);
584 
585 	if (!call->conn->rxkad.cipher)
586 		return 0;
587 
588 	req = rxkad_get_call_crypto(call);
589 	if (!req)
590 		return -ENOMEM;
591 
592 	/* continue encrypting from where we left off */
593 	memcpy(&iv, call->conn->rxkad.csum_iv.x, sizeof(iv));
594 
595 	/* validate the security checksum */
596 	x = (call->cid & RXRPC_CHANNELMASK) << (32 - RXRPC_CIDSHIFT);
597 	x |= seq & 0x3fffffff;
598 	crypto.buf[0] = htonl(call->call_id);
599 	crypto.buf[1] = htonl(x);
600 
601 	sg_init_one(&sg, crypto.buf, 8);
602 	skcipher_request_set_sync_tfm(req, call->conn->rxkad.cipher);
603 	skcipher_request_set_callback(req, 0, NULL, NULL);
604 	skcipher_request_set_crypt(req, &sg, &sg, 8, iv.x);
605 	crypto_skcipher_encrypt(req);
606 	skcipher_request_zero(req);
607 
608 	y = ntohl(crypto.buf[1]);
609 	cksum = (y >> 16) & 0xffff;
610 	if (cksum == 0)
611 		cksum = 1; /* zero checksums are not permitted */
612 
613 	if (cksum != sp->hdr.cksum) {
614 		ret = rxrpc_abort_eproto(call, skb, RXKADSEALEDINCON,
615 					 rxkad_abort_bad_checksum);
616 		goto out;
617 	}
618 
619 	switch (call->conn->security_level) {
620 	case RXRPC_SECURITY_PLAIN:
621 		ret = 0;
622 		break;
623 	case RXRPC_SECURITY_AUTH:
624 		ret = rxkad_verify_packet_1(call, skb, seq, req);
625 		break;
626 	case RXRPC_SECURITY_ENCRYPT:
627 		ret = rxkad_verify_packet_2(call, skb, seq, req);
628 		break;
629 	default:
630 		ret = -ENOANO;
631 		break;
632 	}
633 
634 out:
635 	skcipher_request_free(req);
636 	return ret;
637 }
638 
639 /*
640  * issue a challenge
641  */
642 static int rxkad_issue_challenge(struct rxrpc_connection *conn)
643 {
644 	struct rxkad_challenge challenge;
645 	struct rxrpc_wire_header whdr;
646 	struct msghdr msg;
647 	struct kvec iov[2];
648 	size_t len;
649 	u32 serial;
650 	int ret;
651 
652 	_enter("{%d}", conn->debug_id);
653 
654 	get_random_bytes(&conn->rxkad.nonce, sizeof(conn->rxkad.nonce));
655 
656 	challenge.version	= htonl(2);
657 	challenge.nonce		= htonl(conn->rxkad.nonce);
658 	challenge.min_level	= htonl(0);
659 	challenge.__padding	= 0;
660 
661 	msg.msg_name	= &conn->peer->srx.transport;
662 	msg.msg_namelen	= conn->peer->srx.transport_len;
663 	msg.msg_control	= NULL;
664 	msg.msg_controllen = 0;
665 	msg.msg_flags	= 0;
666 
667 	whdr.epoch	= htonl(conn->proto.epoch);
668 	whdr.cid	= htonl(conn->proto.cid);
669 	whdr.callNumber	= 0;
670 	whdr.seq	= 0;
671 	whdr.type	= RXRPC_PACKET_TYPE_CHALLENGE;
672 	whdr.flags	= conn->out_clientflag;
673 	whdr.userStatus	= 0;
674 	whdr.securityIndex = conn->security_ix;
675 	whdr._rsvd	= 0;
676 	whdr.serviceId	= htons(conn->service_id);
677 
678 	iov[0].iov_base	= &whdr;
679 	iov[0].iov_len	= sizeof(whdr);
680 	iov[1].iov_base	= &challenge;
681 	iov[1].iov_len	= sizeof(challenge);
682 
683 	len = iov[0].iov_len + iov[1].iov_len;
684 
685 	serial = rxrpc_get_next_serial(conn);
686 	whdr.serial = htonl(serial);
687 
688 	trace_rxrpc_tx_challenge(conn, serial, 0, conn->rxkad.nonce);
689 
690 	ret = kernel_sendmsg(conn->local->socket, &msg, iov, 2, len);
691 	if (ret < 0) {
692 		trace_rxrpc_tx_fail(conn->debug_id, serial, ret,
693 				    rxrpc_tx_point_rxkad_challenge);
694 		return -EAGAIN;
695 	}
696 
697 	conn->peer->last_tx_at = ktime_get_seconds();
698 	trace_rxrpc_tx_packet(conn->debug_id, &whdr,
699 			      rxrpc_tx_point_rxkad_challenge);
700 	_leave(" = 0");
701 	return 0;
702 }
703 
704 /*
705  * calculate the response checksum
706  */
707 static void rxkad_calc_response_checksum(struct rxkad_response *response)
708 {
709 	u32 csum = 1000003;
710 	int loop;
711 	u8 *p = (u8 *) response;
712 
713 	for (loop = sizeof(*response); loop > 0; loop--)
714 		csum = csum * 0x10204081 + *p++;
715 
716 	response->encrypted.checksum = htonl(csum);
717 }
718 
719 /*
720  * encrypt the response packet
721  */
722 static int rxkad_encrypt_response(struct rxrpc_connection *conn,
723 				  struct sk_buff *response,
724 				  const struct rxkad_key *s2)
725 {
726 	struct skcipher_request *req;
727 	struct rxrpc_crypt iv;
728 	struct scatterlist sg[1];
729 	size_t encsize = sizeof(((struct rxkad_response *)0)->encrypted);
730 	int ret;
731 
732 	sg_init_table(sg, ARRAY_SIZE(sg));
733 	ret = skb_to_sgvec(response, sg,
734 			   sizeof(struct rxrpc_wire_header) +
735 			   offsetof(struct rxkad_response, encrypted), encsize);
736 	if (ret < 0)
737 		return ret;
738 
739 	req = skcipher_request_alloc(&conn->rxkad.cipher->base, GFP_NOFS);
740 	if (!req)
741 		return -ENOMEM;
742 
743 	/* continue encrypting from where we left off */
744 	memcpy(&iv, s2->session_key, sizeof(iv));
745 
746 	skcipher_request_set_sync_tfm(req, conn->rxkad.cipher);
747 	skcipher_request_set_callback(req, 0, NULL, NULL);
748 	skcipher_request_set_crypt(req, sg, sg, encsize, iv.x);
749 	ret = crypto_skcipher_encrypt(req);
750 	skcipher_request_free(req);
751 	return ret;
752 }
753 
754 /*
755  * Validate a challenge packet.
756  */
757 static bool rxkad_validate_challenge(struct rxrpc_connection *conn,
758 				     struct sk_buff *skb)
759 {
760 	struct rxkad_challenge challenge;
761 	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
762 	u32 version, min_level;
763 	int ret;
764 
765 	_enter("{%d,%x}", conn->debug_id, key_serial(conn->key));
766 
767 	if (!conn->key) {
768 		rxrpc_abort_conn(conn, skb, RX_PROTOCOL_ERROR, -EPROTO,
769 				 rxkad_abort_chall_no_key);
770 		return false;
771 	}
772 
773 	ret = key_validate(conn->key);
774 	if (ret < 0) {
775 		rxrpc_abort_conn(conn, skb, RXKADEXPIRED, ret,
776 				 rxkad_abort_chall_key_expired);
777 		return false;
778 	}
779 
780 	if (skb_copy_bits(skb, sizeof(struct rxrpc_wire_header),
781 			  &challenge, sizeof(challenge)) < 0) {
782 		rxrpc_abort_conn(conn, skb, RXKADPACKETSHORT, -EPROTO,
783 				 rxkad_abort_chall_short);
784 		return false;
785 	}
786 
787 	version = ntohl(challenge.version);
788 	sp->chall.rxkad_nonce = ntohl(challenge.nonce);
789 	min_level = ntohl(challenge.min_level);
790 
791 	trace_rxrpc_rx_challenge(conn, sp->hdr.serial, version,
792 				 sp->chall.rxkad_nonce, min_level);
793 
794 	if (version != RXKAD_VERSION) {
795 		rxrpc_abort_conn(conn, skb, RXKADINCONSISTENCY, -EPROTO,
796 				 rxkad_abort_chall_version);
797 		return false;
798 	}
799 
800 	if (conn->security_level < min_level) {
801 		rxrpc_abort_conn(conn, skb, RXKADLEVELFAIL, -EACCES,
802 				 rxkad_abort_chall_level);
803 		return false;
804 	}
805 	return true;
806 }
807 
808 /*
809  * Insert the header into the response.
810  */
811 static noinline
812 int rxkad_insert_response_header(struct rxrpc_connection *conn,
813 				 const struct rxrpc_key_token *token,
814 				 struct sk_buff *challenge,
815 				 struct sk_buff *response,
816 				 size_t *offset)
817 {
818 	struct rxrpc_skb_priv *csp = rxrpc_skb(challenge);
819 	struct {
820 		struct rxrpc_wire_header whdr;
821 		struct rxkad_response	resp;
822 	} h;
823 	int ret;
824 
825 	h.whdr.epoch			= htonl(conn->proto.epoch);
826 	h.whdr.cid			= htonl(conn->proto.cid);
827 	h.whdr.callNumber		= 0;
828 	h.whdr.serial			= 0;
829 	h.whdr.seq			= 0;
830 	h.whdr.type			= RXRPC_PACKET_TYPE_RESPONSE;
831 	h.whdr.flags			= conn->out_clientflag;
832 	h.whdr.userStatus		= 0;
833 	h.whdr.securityIndex		= conn->security_ix;
834 	h.whdr.cksum			= 0;
835 	h.whdr.serviceId		= htons(conn->service_id);
836 	h.resp.version			= htonl(RXKAD_VERSION);
837 	h.resp.__pad			= 0;
838 	h.resp.encrypted.epoch		= htonl(conn->proto.epoch);
839 	h.resp.encrypted.cid		= htonl(conn->proto.cid);
840 	h.resp.encrypted.checksum	= 0;
841 	h.resp.encrypted.securityIndex	= htonl(conn->security_ix);
842 	h.resp.encrypted.call_id[0]	= htonl(conn->channels[0].call_counter);
843 	h.resp.encrypted.call_id[1]	= htonl(conn->channels[1].call_counter);
844 	h.resp.encrypted.call_id[2]	= htonl(conn->channels[2].call_counter);
845 	h.resp.encrypted.call_id[3]	= htonl(conn->channels[3].call_counter);
846 	h.resp.encrypted.inc_nonce	= htonl(csp->chall.rxkad_nonce + 1);
847 	h.resp.encrypted.level		= htonl(conn->security_level);
848 	h.resp.kvno			= htonl(token->kad->kvno);
849 	h.resp.ticket_len		= htonl(token->kad->ticket_len);
850 
851 	rxkad_calc_response_checksum(&h.resp);
852 
853 	ret = skb_store_bits(response, *offset, &h, sizeof(h));
854 	*offset += sizeof(h);
855 	return ret;
856 }
857 
858 /*
859  * respond to a challenge packet
860  */
861 static int rxkad_respond_to_challenge(struct rxrpc_connection *conn,
862 				      struct sk_buff *challenge)
863 {
864 	const struct rxrpc_key_token *token;
865 	struct rxrpc_skb_priv *csp, *rsp;
866 	struct sk_buff *response;
867 	size_t len, offset = 0;
868 	int ret = -EPROTO;
869 
870 	_enter("{%d,%x}", conn->debug_id, key_serial(conn->key));
871 
872 	ret = key_validate(conn->key);
873 	if (ret < 0)
874 		return rxrpc_abort_conn(conn, challenge, RXKADEXPIRED, ret,
875 					rxkad_abort_chall_key_expired);
876 
877 	token = conn->key->payload.data[0];
878 
879 	/* build the response packet */
880 	len = sizeof(struct rxrpc_wire_header) +
881 		sizeof(struct rxkad_response) +
882 		token->kad->ticket_len;
883 
884 	response = alloc_skb_with_frags(0, len, 0, &ret, GFP_NOFS);
885 	if (!response)
886 		goto error;
887 	rxrpc_new_skb(response, rxrpc_skb_new_response_rxkad);
888 	response->len = len;
889 	response->data_len = len;
890 
891 	offset = 0;
892 	ret = rxkad_insert_response_header(conn, token, challenge, response,
893 					   &offset);
894 	if (ret < 0)
895 		goto error;
896 
897 	ret = rxkad_encrypt_response(conn, response, token->kad);
898 	if (ret < 0)
899 		goto error;
900 
901 	ret = skb_store_bits(response, offset, token->kad->ticket,
902 			     token->kad->ticket_len);
903 	if (ret < 0)
904 		goto error;
905 
906 	csp = rxrpc_skb(challenge);
907 	rsp = rxrpc_skb(response);
908 	rsp->resp.len = len;
909 	rsp->resp.challenge_serial = csp->hdr.serial;
910 	rxrpc_post_response(conn, response);
911 	response = NULL;
912 	ret = 0;
913 
914 error:
915 	rxrpc_free_skb(response, rxrpc_skb_put_response);
916 	return ret;
917 }
918 
919 /*
920  * RxKAD does automatic response only as there's nothing to manage that isn't
921  * already in the key.
922  */
923 static int rxkad_sendmsg_respond_to_challenge(struct sk_buff *challenge,
924 					      struct msghdr *msg)
925 {
926 	return -EINVAL;
927 }
928 
929 /**
930  * rxkad_kernel_respond_to_challenge - Respond to a challenge with appdata
931  * @challenge: The challenge to respond to
932  *
933  * Allow a kernel application to respond to a CHALLENGE.
934  *
935  * Return: %0 if successful and a negative error code otherwise.
936  */
937 int rxkad_kernel_respond_to_challenge(struct sk_buff *challenge)
938 {
939 	struct rxrpc_skb_priv *csp = rxrpc_skb(challenge);
940 
941 	return rxkad_respond_to_challenge(csp->chall.conn, challenge);
942 }
943 EXPORT_SYMBOL(rxkad_kernel_respond_to_challenge);
944 
945 /*
946  * decrypt the kerberos IV ticket in the response
947  */
948 static int rxkad_decrypt_ticket(struct rxrpc_connection *conn,
949 				struct key *server_key,
950 				struct sk_buff *skb,
951 				void *ticket, size_t ticket_len,
952 				struct rxrpc_crypt *_session_key,
953 				time64_t *_expiry)
954 {
955 	struct skcipher_request *req;
956 	struct rxrpc_crypt iv, key;
957 	struct scatterlist sg[1];
958 	struct in_addr addr;
959 	unsigned int life;
960 	time64_t issue, now;
961 	bool little_endian;
962 	u8 *p, *q, *name, *end;
963 
964 	_enter("{%d},{%x}", conn->debug_id, key_serial(server_key));
965 
966 	*_expiry = 0;
967 
968 	ASSERT(server_key->payload.data[0] != NULL);
969 	ASSERTCMP((unsigned long) ticket & 7UL, ==, 0);
970 
971 	memcpy(&iv, &server_key->payload.data[2], sizeof(iv));
972 
973 	req = skcipher_request_alloc(server_key->payload.data[0], GFP_NOFS);
974 	if (!req)
975 		return -ENOMEM;
976 
977 	sg_init_one(&sg[0], ticket, ticket_len);
978 	skcipher_request_set_callback(req, 0, NULL, NULL);
979 	skcipher_request_set_crypt(req, sg, sg, ticket_len, iv.x);
980 	crypto_skcipher_decrypt(req);
981 	skcipher_request_free(req);
982 
983 	p = ticket;
984 	end = p + ticket_len;
985 
986 #define Z(field, fieldl)						\
987 	({								\
988 		u8 *__str = p;						\
989 		q = memchr(p, 0, end - p);				\
990 		if (!q || q - p > field##_SZ)				\
991 			return rxrpc_abort_conn(			\
992 				conn, skb, RXKADBADTICKET, -EPROTO,	\
993 				rxkad_abort_resp_tkt_##fieldl);		\
994 		for (; p < q; p++)					\
995 			if (!isprint(*p))				\
996 				return rxrpc_abort_conn(		\
997 					conn, skb, RXKADBADTICKET, -EPROTO, \
998 					rxkad_abort_resp_tkt_##fieldl);	\
999 		p++;							\
1000 		__str;							\
1001 	})
1002 
1003 	/* extract the ticket flags */
1004 	_debug("KIV FLAGS: %x", *p);
1005 	little_endian = *p & 1;
1006 	p++;
1007 
1008 	/* extract the authentication name */
1009 	name = Z(ANAME, aname);
1010 	_debug("KIV ANAME: %s", name);
1011 
1012 	/* extract the principal's instance */
1013 	name = Z(INST, inst);
1014 	_debug("KIV INST : %s", name);
1015 
1016 	/* extract the principal's authentication domain */
1017 	name = Z(REALM, realm);
1018 	_debug("KIV REALM: %s", name);
1019 
1020 	if (end - p < 4 + 8 + 4 + 2)
1021 		return rxrpc_abort_conn(conn, skb, RXKADBADTICKET, -EPROTO,
1022 					rxkad_abort_resp_tkt_short);
1023 
1024 	/* get the IPv4 address of the entity that requested the ticket */
1025 	memcpy(&addr, p, sizeof(addr));
1026 	p += 4;
1027 	_debug("KIV ADDR : %pI4", &addr);
1028 
1029 	/* get the session key from the ticket */
1030 	memcpy(&key, p, sizeof(key));
1031 	p += 8;
1032 	_debug("KIV KEY  : %08x %08x", ntohl(key.n[0]), ntohl(key.n[1]));
1033 	memcpy(_session_key, &key, sizeof(key));
1034 
1035 	/* get the ticket's lifetime */
1036 	life = *p++ * 5 * 60;
1037 	_debug("KIV LIFE : %u", life);
1038 
1039 	/* get the issue time of the ticket */
1040 	if (little_endian) {
1041 		__le32 stamp;
1042 		memcpy(&stamp, p, 4);
1043 		issue = rxrpc_u32_to_time64(le32_to_cpu(stamp));
1044 	} else {
1045 		__be32 stamp;
1046 		memcpy(&stamp, p, 4);
1047 		issue = rxrpc_u32_to_time64(be32_to_cpu(stamp));
1048 	}
1049 	p += 4;
1050 	now = ktime_get_real_seconds();
1051 	_debug("KIV ISSUE: %llx [%llx]", issue, now);
1052 
1053 	/* check the ticket is in date */
1054 	if (issue > now)
1055 		return rxrpc_abort_conn(conn, skb, RXKADNOAUTH, -EKEYREJECTED,
1056 					rxkad_abort_resp_tkt_future);
1057 	if (issue < now - life)
1058 		return rxrpc_abort_conn(conn, skb, RXKADEXPIRED, -EKEYEXPIRED,
1059 					rxkad_abort_resp_tkt_expired);
1060 
1061 	*_expiry = issue + life;
1062 
1063 	/* get the service name */
1064 	name = Z(SNAME, sname);
1065 	_debug("KIV SNAME: %s", name);
1066 
1067 	/* get the service instance name */
1068 	name = Z(INST, sinst);
1069 	_debug("KIV SINST: %s", name);
1070 	return 0;
1071 }
1072 
1073 /*
1074  * decrypt the response packet
1075  */
1076 static void rxkad_decrypt_response(struct rxrpc_connection *conn,
1077 				   struct rxkad_response *resp,
1078 				   const struct rxrpc_crypt *session_key)
1079 {
1080 	struct skcipher_request *req = rxkad_ci_req;
1081 	struct scatterlist sg[1];
1082 	struct rxrpc_crypt iv;
1083 
1084 	_enter(",,%08x%08x",
1085 	       ntohl(session_key->n[0]), ntohl(session_key->n[1]));
1086 
1087 	mutex_lock(&rxkad_ci_mutex);
1088 	if (crypto_sync_skcipher_setkey(rxkad_ci, session_key->x,
1089 					sizeof(*session_key)) < 0)
1090 		BUG();
1091 
1092 	memcpy(&iv, session_key, sizeof(iv));
1093 
1094 	sg_init_table(sg, 1);
1095 	sg_set_buf(sg, &resp->encrypted, sizeof(resp->encrypted));
1096 	skcipher_request_set_sync_tfm(req, rxkad_ci);
1097 	skcipher_request_set_callback(req, 0, NULL, NULL);
1098 	skcipher_request_set_crypt(req, sg, sg, sizeof(resp->encrypted), iv.x);
1099 	crypto_skcipher_decrypt(req);
1100 	skcipher_request_zero(req);
1101 
1102 	mutex_unlock(&rxkad_ci_mutex);
1103 
1104 	_leave("");
1105 }
1106 
1107 /*
1108  * verify a response
1109  */
1110 static int rxkad_verify_response(struct rxrpc_connection *conn,
1111 				 struct sk_buff *skb)
1112 {
1113 	struct rxkad_response *response;
1114 	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
1115 	struct rxrpc_crypt session_key;
1116 	struct key *server_key;
1117 	time64_t expiry;
1118 	void *ticket;
1119 	u32 version, kvno, ticket_len, level;
1120 	__be32 csum;
1121 	int ret, i;
1122 
1123 	_enter("{%d}", conn->debug_id);
1124 
1125 	server_key = rxrpc_look_up_server_security(conn, skb, 0, 0);
1126 	if (IS_ERR(server_key)) {
1127 		ret = PTR_ERR(server_key);
1128 		switch (ret) {
1129 		case -ENOKEY:
1130 			return rxrpc_abort_conn(conn, skb, RXKADUNKNOWNKEY, ret,
1131 						rxkad_abort_resp_nokey);
1132 		case -EKEYEXPIRED:
1133 			return rxrpc_abort_conn(conn, skb, RXKADEXPIRED, ret,
1134 						rxkad_abort_resp_key_expired);
1135 		default:
1136 			return rxrpc_abort_conn(conn, skb, RXKADNOAUTH, ret,
1137 						rxkad_abort_resp_key_rejected);
1138 		}
1139 	}
1140 
1141 	ret = -ENOMEM;
1142 	response = kzalloc(sizeof(struct rxkad_response), GFP_NOFS);
1143 	if (!response)
1144 		goto temporary_error;
1145 
1146 	if (skb_copy_bits(skb, sizeof(struct rxrpc_wire_header),
1147 			  response, sizeof(*response)) < 0) {
1148 		rxrpc_abort_conn(conn, skb, RXKADPACKETSHORT, -EPROTO,
1149 				 rxkad_abort_resp_short);
1150 		goto protocol_error;
1151 	}
1152 
1153 	version = ntohl(response->version);
1154 	ticket_len = ntohl(response->ticket_len);
1155 	kvno = ntohl(response->kvno);
1156 
1157 	trace_rxrpc_rx_response(conn, sp->hdr.serial, version, kvno, ticket_len);
1158 
1159 	if (version != RXKAD_VERSION) {
1160 		rxrpc_abort_conn(conn, skb, RXKADINCONSISTENCY, -EPROTO,
1161 				 rxkad_abort_resp_version);
1162 		goto protocol_error;
1163 	}
1164 
1165 	if (ticket_len < 4 || ticket_len > MAXKRB5TICKETLEN) {
1166 		rxrpc_abort_conn(conn, skb, RXKADTICKETLEN, -EPROTO,
1167 				 rxkad_abort_resp_tkt_len);
1168 		goto protocol_error;
1169 	}
1170 
1171 	if (kvno >= RXKAD_TKT_TYPE_KERBEROS_V5) {
1172 		rxrpc_abort_conn(conn, skb, RXKADUNKNOWNKEY, -EPROTO,
1173 				 rxkad_abort_resp_unknown_tkt);
1174 		goto protocol_error;
1175 	}
1176 
1177 	/* extract the kerberos ticket and decrypt and decode it */
1178 	ret = -ENOMEM;
1179 	ticket = kmalloc(ticket_len, GFP_NOFS);
1180 	if (!ticket)
1181 		goto temporary_error_free_resp;
1182 
1183 	if (skb_copy_bits(skb, sizeof(struct rxrpc_wire_header) + sizeof(*response),
1184 			  ticket, ticket_len) < 0) {
1185 		rxrpc_abort_conn(conn, skb, RXKADPACKETSHORT, -EPROTO,
1186 				 rxkad_abort_resp_short_tkt);
1187 		goto protocol_error;
1188 	}
1189 
1190 	ret = rxkad_decrypt_ticket(conn, server_key, skb, ticket, ticket_len,
1191 				   &session_key, &expiry);
1192 	if (ret < 0)
1193 		goto temporary_error_free_ticket;
1194 
1195 	/* use the session key from inside the ticket to decrypt the
1196 	 * response */
1197 	rxkad_decrypt_response(conn, response, &session_key);
1198 
1199 	if (ntohl(response->encrypted.epoch) != conn->proto.epoch ||
1200 	    ntohl(response->encrypted.cid) != conn->proto.cid ||
1201 	    ntohl(response->encrypted.securityIndex) != conn->security_ix) {
1202 		rxrpc_abort_conn(conn, skb, RXKADSEALEDINCON, -EPROTO,
1203 				 rxkad_abort_resp_bad_param);
1204 		goto protocol_error_free;
1205 	}
1206 
1207 	csum = response->encrypted.checksum;
1208 	response->encrypted.checksum = 0;
1209 	rxkad_calc_response_checksum(response);
1210 	if (response->encrypted.checksum != csum) {
1211 		rxrpc_abort_conn(conn, skb, RXKADSEALEDINCON, -EPROTO,
1212 				 rxkad_abort_resp_bad_checksum);
1213 		goto protocol_error_free;
1214 	}
1215 
1216 	for (i = 0; i < RXRPC_MAXCALLS; i++) {
1217 		u32 call_id = ntohl(response->encrypted.call_id[i]);
1218 		u32 counter = READ_ONCE(conn->channels[i].call_counter);
1219 
1220 		if (call_id > INT_MAX) {
1221 			rxrpc_abort_conn(conn, skb, RXKADSEALEDINCON, -EPROTO,
1222 					 rxkad_abort_resp_bad_callid);
1223 			goto protocol_error_free;
1224 		}
1225 
1226 		if (call_id < counter) {
1227 			rxrpc_abort_conn(conn, skb, RXKADSEALEDINCON, -EPROTO,
1228 					 rxkad_abort_resp_call_ctr);
1229 			goto protocol_error_free;
1230 		}
1231 
1232 		if (call_id > counter) {
1233 			if (conn->channels[i].call) {
1234 				rxrpc_abort_conn(conn, skb, RXKADSEALEDINCON, -EPROTO,
1235 						 rxkad_abort_resp_call_state);
1236 				goto protocol_error_free;
1237 			}
1238 			conn->channels[i].call_counter = call_id;
1239 		}
1240 	}
1241 
1242 	if (ntohl(response->encrypted.inc_nonce) != conn->rxkad.nonce + 1) {
1243 		rxrpc_abort_conn(conn, skb, RXKADOUTOFSEQUENCE, -EPROTO,
1244 				 rxkad_abort_resp_ooseq);
1245 		goto protocol_error_free;
1246 	}
1247 
1248 	level = ntohl(response->encrypted.level);
1249 	if (level > RXRPC_SECURITY_ENCRYPT) {
1250 		rxrpc_abort_conn(conn, skb, RXKADLEVELFAIL, -EPROTO,
1251 				 rxkad_abort_resp_level);
1252 		goto protocol_error_free;
1253 	}
1254 	conn->security_level = level;
1255 
1256 	/* create a key to hold the security data and expiration time - after
1257 	 * this the connection security can be handled in exactly the same way
1258 	 * as for a client connection */
1259 	ret = rxrpc_get_server_data_key(conn, &session_key, expiry, kvno);
1260 	if (ret < 0)
1261 		goto temporary_error_free_ticket;
1262 
1263 	kfree(ticket);
1264 	kfree(response);
1265 	_leave(" = 0");
1266 	return 0;
1267 
1268 protocol_error_free:
1269 	kfree(ticket);
1270 protocol_error:
1271 	kfree(response);
1272 	key_put(server_key);
1273 	return -EPROTO;
1274 
1275 temporary_error_free_ticket:
1276 	kfree(ticket);
1277 temporary_error_free_resp:
1278 	kfree(response);
1279 temporary_error:
1280 	/* Ignore the response packet if we got a temporary error such as
1281 	 * ENOMEM.  We just want to send the challenge again.  Note that we
1282 	 * also come out this way if the ticket decryption fails.
1283 	 */
1284 	key_put(server_key);
1285 	return ret;
1286 }
1287 
1288 /*
1289  * clear the connection security
1290  */
1291 static void rxkad_clear(struct rxrpc_connection *conn)
1292 {
1293 	_enter("");
1294 
1295 	if (conn->rxkad.cipher)
1296 		crypto_free_sync_skcipher(conn->rxkad.cipher);
1297 }
1298 
1299 /*
1300  * Initialise the rxkad security service.
1301  */
1302 static int rxkad_init(void)
1303 {
1304 	struct crypto_sync_skcipher *tfm;
1305 	struct skcipher_request *req;
1306 
1307 	/* pin the cipher we need so that the crypto layer doesn't invoke
1308 	 * keventd to go get it */
1309 	tfm = crypto_alloc_sync_skcipher("pcbc(fcrypt)", 0, 0);
1310 	if (IS_ERR(tfm))
1311 		return PTR_ERR(tfm);
1312 
1313 	req = skcipher_request_alloc(&tfm->base, GFP_KERNEL);
1314 	if (!req)
1315 		goto nomem_tfm;
1316 
1317 	rxkad_ci_req = req;
1318 	rxkad_ci = tfm;
1319 	return 0;
1320 
1321 nomem_tfm:
1322 	crypto_free_sync_skcipher(tfm);
1323 	return -ENOMEM;
1324 }
1325 
1326 /*
1327  * Clean up the rxkad security service.
1328  */
1329 static void rxkad_exit(void)
1330 {
1331 	crypto_free_sync_skcipher(rxkad_ci);
1332 	skcipher_request_free(rxkad_ci_req);
1333 }
1334 
1335 /*
1336  * RxRPC Kerberos-based security
1337  */
1338 const struct rxrpc_security rxkad = {
1339 	.name				= "rxkad",
1340 	.security_index			= RXRPC_SECURITY_RXKAD,
1341 	.no_key_abort			= RXKADUNKNOWNKEY,
1342 	.init				= rxkad_init,
1343 	.exit				= rxkad_exit,
1344 	.preparse_server_key		= rxkad_preparse_server_key,
1345 	.free_preparse_server_key	= rxkad_free_preparse_server_key,
1346 	.destroy_server_key		= rxkad_destroy_server_key,
1347 	.init_connection_security	= rxkad_init_connection_security,
1348 	.alloc_txbuf			= rxkad_alloc_txbuf,
1349 	.secure_packet			= rxkad_secure_packet,
1350 	.verify_packet			= rxkad_verify_packet,
1351 	.free_call_crypto		= rxkad_free_call_crypto,
1352 	.issue_challenge		= rxkad_issue_challenge,
1353 	.validate_challenge		= rxkad_validate_challenge,
1354 	.sendmsg_respond_to_challenge	= rxkad_sendmsg_respond_to_challenge,
1355 	.respond_to_challenge		= rxkad_respond_to_challenge,
1356 	.verify_response		= rxkad_verify_response,
1357 	.clear				= rxkad_clear,
1358 };
1359