1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* GSSAPI-based RxRPC security
3  *
4  * Copyright (C) 2025 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 <linux/net.h>
11 #include <linux/skbuff.h>
12 #include <linux/slab.h>
13 #include <linux/key-type.h>
14 #include "ar-internal.h"
15 #include "rxgk_common.h"
16 
17 /*
18  * Parse the information from a server key
19  */
20 static int rxgk_preparse_server_key(struct key_preparsed_payload *prep)
21 {
22 	const struct krb5_enctype *krb5;
23 	struct krb5_buffer *server_key = (void *)&prep->payload.data[2];
24 	unsigned int service, sec_class, kvno, enctype;
25 	int n = 0;
26 
27 	_enter("%zu", prep->datalen);
28 
29 	if (sscanf(prep->orig_description, "%u:%u:%u:%u%n",
30 		   &service, &sec_class, &kvno, &enctype, &n) != 4)
31 		return -EINVAL;
32 
33 	if (prep->orig_description[n])
34 		return -EINVAL;
35 
36 	krb5 = crypto_krb5_find_enctype(enctype);
37 	if (!krb5)
38 		return -ENOPKG;
39 
40 	prep->payload.data[0] = (struct krb5_enctype *)krb5;
41 
42 	if (prep->datalen != krb5->key_len)
43 		return -EKEYREJECTED;
44 
45 	server_key->len = prep->datalen;
46 	server_key->data = kmemdup(prep->data, prep->datalen, GFP_KERNEL);
47 	if (!server_key->data)
48 		return -ENOMEM;
49 
50 	_leave(" = 0");
51 	return 0;
52 }
53 
54 static void rxgk_free_server_key(union key_payload *payload)
55 {
56 	struct krb5_buffer *server_key = (void *)&payload->data[2];
57 
58 	kfree_sensitive(server_key->data);
59 }
60 
61 static void rxgk_free_preparse_server_key(struct key_preparsed_payload *prep)
62 {
63 	rxgk_free_server_key(&prep->payload);
64 }
65 
66 static void rxgk_destroy_server_key(struct key *key)
67 {
68 	rxgk_free_server_key(&key->payload);
69 }
70 
71 static void rxgk_describe_server_key(const struct key *key, struct seq_file *m)
72 {
73 	const struct krb5_enctype *krb5 = key->payload.data[0];
74 
75 	if (krb5)
76 		seq_printf(m, ": %s", krb5->name);
77 }
78 
79 /*
80  * Handle rekeying the connection when we see our limits overrun or when the
81  * far side decided to rekey.
82  *
83  * Returns a ref on the context if successful or -ESTALE if the key is out of
84  * date.
85  */
86 static struct rxgk_context *rxgk_rekey(struct rxrpc_connection *conn,
87 				       const u16 *specific_key_number)
88 {
89 	struct rxgk_context *gk, *dead = NULL;
90 	unsigned int key_number, current_key, mask = ARRAY_SIZE(conn->rxgk.keys) - 1;
91 	bool crank = false;
92 
93 	_enter("%d", specific_key_number ? *specific_key_number : -1);
94 
95 	mutex_lock(&conn->security_lock);
96 
97 	current_key = conn->rxgk.key_number;
98 	if (!specific_key_number) {
99 		key_number = current_key;
100 	} else {
101 		if (*specific_key_number == (u16)current_key)
102 			key_number = current_key;
103 		else if (*specific_key_number == (u16)(current_key - 1))
104 			key_number = current_key - 1;
105 		else if (*specific_key_number == (u16)(current_key + 1))
106 			goto crank_window;
107 		else
108 			goto bad_key;
109 	}
110 
111 	gk = conn->rxgk.keys[key_number & mask];
112 	if (!gk)
113 		goto generate_key;
114 	if (!specific_key_number &&
115 	    test_bit(RXGK_TK_NEEDS_REKEY, &gk->flags))
116 		goto crank_window;
117 
118 grab:
119 	refcount_inc(&gk->usage);
120 	mutex_unlock(&conn->security_lock);
121 	rxgk_put(dead);
122 	return gk;
123 
124 crank_window:
125 	trace_rxrpc_rxgk_rekey(conn, current_key,
126 			       specific_key_number ? *specific_key_number : -1);
127 	if (current_key == UINT_MAX)
128 		goto bad_key;
129 	if (current_key + 1 == UINT_MAX)
130 		set_bit(RXRPC_CONN_DONT_REUSE, &conn->flags);
131 
132 	key_number = current_key + 1;
133 	if (WARN_ON(conn->rxgk.keys[key_number & mask]))
134 		goto bad_key;
135 	crank = true;
136 
137 generate_key:
138 	gk = conn->rxgk.keys[current_key & mask];
139 	gk = rxgk_generate_transport_key(conn, gk->key, key_number, GFP_NOFS);
140 	if (IS_ERR(gk)) {
141 		mutex_unlock(&conn->security_lock);
142 		return gk;
143 	}
144 
145 	write_lock(&conn->security_use_lock);
146 	if (crank) {
147 		current_key++;
148 		conn->rxgk.key_number = current_key;
149 		dead = conn->rxgk.keys[(current_key - 2) & mask];
150 		conn->rxgk.keys[(current_key - 2) & mask] = NULL;
151 	}
152 	conn->rxgk.keys[current_key & mask] = gk;
153 	write_unlock(&conn->security_use_lock);
154 	goto grab;
155 
156 bad_key:
157 	mutex_unlock(&conn->security_lock);
158 	return ERR_PTR(-ESTALE);
159 }
160 
161 /*
162  * Get the specified keying context.
163  *
164  * Returns a ref on the context if successful or -ESTALE if the key is out of
165  * date.
166  */
167 static struct rxgk_context *rxgk_get_key(struct rxrpc_connection *conn,
168 					 const u16 *specific_key_number)
169 {
170 	struct rxgk_context *gk;
171 	unsigned int key_number, current_key, mask = ARRAY_SIZE(conn->rxgk.keys) - 1;
172 
173 	_enter("{%u},%d",
174 	       conn->rxgk.key_number, specific_key_number ? *specific_key_number : -1);
175 
176 	read_lock(&conn->security_use_lock);
177 
178 	current_key = conn->rxgk.key_number;
179 	if (!specific_key_number) {
180 		key_number = current_key;
181 	} else {
182 		/* Only the bottom 16 bits of the key number are exposed in the
183 		 * header, so we try and keep the upper 16 bits in step.  The
184 		 * whole 32 bits are used to generate the TK.
185 		 */
186 		if (*specific_key_number == (u16)current_key)
187 			key_number = current_key;
188 		else if (*specific_key_number == (u16)(current_key - 1))
189 			key_number = current_key - 1;
190 		else if (*specific_key_number == (u16)(current_key + 1))
191 			goto rekey;
192 		else
193 			goto bad_key;
194 	}
195 
196 	gk = conn->rxgk.keys[key_number & mask];
197 	if (!gk)
198 		goto slow_path;
199 	if (!specific_key_number &&
200 	    key_number < UINT_MAX) {
201 		if (time_after(jiffies, gk->expiry) ||
202 		    gk->bytes_remaining < 0) {
203 			set_bit(RXGK_TK_NEEDS_REKEY, &gk->flags);
204 			goto slow_path;
205 		}
206 
207 		if (test_bit(RXGK_TK_NEEDS_REKEY, &gk->flags))
208 			goto slow_path;
209 	}
210 
211 	refcount_inc(&gk->usage);
212 	read_unlock(&conn->security_use_lock);
213 	return gk;
214 
215 rekey:
216 	_debug("rekey");
217 	if (current_key == UINT_MAX)
218 		goto bad_key;
219 	gk = conn->rxgk.keys[current_key & mask];
220 	if (gk)
221 		set_bit(RXGK_TK_NEEDS_REKEY, &gk->flags);
222 slow_path:
223 	read_unlock(&conn->security_use_lock);
224 	return rxgk_rekey(conn, specific_key_number);
225 bad_key:
226 	read_unlock(&conn->security_use_lock);
227 	return ERR_PTR(-ESTALE);
228 }
229 
230 /*
231  * initialise connection security
232  */
233 static int rxgk_init_connection_security(struct rxrpc_connection *conn,
234 					 struct rxrpc_key_token *token)
235 {
236 	struct rxgk_context *gk;
237 	int ret;
238 
239 	_enter("{%d,%u},{%x}",
240 	       conn->debug_id, conn->rxgk.key_number, key_serial(conn->key));
241 
242 	conn->security_ix = token->security_index;
243 	conn->security_level = token->rxgk->level;
244 
245 	if (rxrpc_conn_is_client(conn)) {
246 		conn->rxgk.start_time = ktime_get();
247 		do_div(conn->rxgk.start_time, 100);
248 	}
249 
250 	gk = rxgk_generate_transport_key(conn, token->rxgk, conn->rxgk.key_number,
251 					 GFP_NOFS);
252 	if (IS_ERR(gk))
253 		return PTR_ERR(gk);
254 	conn->rxgk.enctype = gk->krb5->etype;
255 	conn->rxgk.keys[gk->key_number & 3] = gk;
256 
257 	switch (conn->security_level) {
258 	case RXRPC_SECURITY_PLAIN:
259 	case RXRPC_SECURITY_AUTH:
260 	case RXRPC_SECURITY_ENCRYPT:
261 		break;
262 	default:
263 		ret = -EKEYREJECTED;
264 		goto error;
265 	}
266 
267 	ret = 0;
268 error:
269 	_leave(" = %d", ret);
270 	return ret;
271 }
272 
273 /*
274  * Clean up the crypto on a call.
275  */
276 static void rxgk_free_call_crypto(struct rxrpc_call *call)
277 {
278 }
279 
280 /*
281  * Work out how much data we can put in a packet.
282  */
283 static struct rxrpc_txbuf *rxgk_alloc_txbuf(struct rxrpc_call *call, size_t remain, gfp_t gfp)
284 {
285 	enum krb5_crypto_mode mode;
286 	struct rxgk_context *gk;
287 	struct rxrpc_txbuf *txb;
288 	size_t shdr, alloc, limit, part, offset, gap;
289 
290 	switch (call->conn->security_level) {
291 	default:
292 		alloc = umin(remain, RXRPC_JUMBO_DATALEN);
293 		return rxrpc_alloc_data_txbuf(call, alloc, 1, gfp);
294 	case RXRPC_SECURITY_AUTH:
295 		shdr = 0;
296 		mode = KRB5_CHECKSUM_MODE;
297 		break;
298 	case RXRPC_SECURITY_ENCRYPT:
299 		shdr = sizeof(struct rxgk_header);
300 		mode = KRB5_ENCRYPT_MODE;
301 		break;
302 	}
303 
304 	gk = rxgk_get_key(call->conn, NULL);
305 	if (IS_ERR(gk))
306 		return NULL;
307 
308 	/* Work out the maximum amount of data that will fit. */
309 	alloc = RXRPC_JUMBO_DATALEN;
310 	limit = crypto_krb5_how_much_data(gk->krb5, mode, &alloc, &offset);
311 
312 	if (remain < limit - shdr) {
313 		part = remain;
314 		alloc = crypto_krb5_how_much_buffer(gk->krb5, mode,
315 						    shdr + part, &offset);
316 		gap = 0;
317 	} else {
318 		part = limit - shdr;
319 		gap = RXRPC_JUMBO_DATALEN - alloc;
320 		alloc = RXRPC_JUMBO_DATALEN;
321 	}
322 
323 	rxgk_put(gk);
324 
325 	txb = rxrpc_alloc_data_txbuf(call, alloc, 16, gfp);
326 	if (!txb)
327 		return NULL;
328 
329 	txb->crypto_header	= offset;
330 	txb->sec_header		= shdr;
331 	txb->offset		+= offset + shdr;
332 	txb->space		= part;
333 
334 	/* Clear excess space in the packet */
335 	if (gap)
336 		memset(txb->data + alloc - gap, 0, gap);
337 	return txb;
338 }
339 
340 /*
341  * Integrity mode (sign a packet - level 1 security)
342  */
343 static int rxgk_secure_packet_integrity(const struct rxrpc_call *call,
344 					struct rxgk_context *gk,
345 					struct rxrpc_txbuf *txb)
346 {
347 	struct rxgk_header *hdr;
348 	struct scatterlist sg[1];
349 	struct krb5_buffer metadata;
350 	int ret = -ENOMEM;
351 
352 	_enter("");
353 
354 	hdr = kzalloc(sizeof(*hdr), GFP_NOFS);
355 	if (!hdr)
356 		goto error_gk;
357 
358 	hdr->epoch	= htonl(call->conn->proto.epoch);
359 	hdr->cid	= htonl(call->cid);
360 	hdr->call_number = htonl(call->call_id);
361 	hdr->seq	= htonl(txb->seq);
362 	hdr->sec_index	= htonl(call->security_ix);
363 	hdr->data_len	= htonl(txb->len);
364 	metadata.len = sizeof(*hdr);
365 	metadata.data = hdr;
366 
367 	sg_init_table(sg, 1);
368 	sg_set_buf(&sg[0], txb->data, txb->alloc_size);
369 
370 	ret = crypto_krb5_get_mic(gk->krb5, gk->tx_Kc, &metadata,
371 				  sg, 1, txb->alloc_size,
372 				  txb->crypto_header, txb->sec_header + txb->len);
373 	if (ret >= 0) {
374 		txb->pkt_len = ret;
375 		if (txb->alloc_size == RXRPC_JUMBO_DATALEN)
376 			txb->jumboable = true;
377 		gk->bytes_remaining -= ret;
378 	}
379 	kfree(hdr);
380 error_gk:
381 	rxgk_put(gk);
382 	_leave(" = %d", ret);
383 	return ret;
384 }
385 
386 /*
387  * wholly encrypt a packet (level 2 security)
388  */
389 static int rxgk_secure_packet_encrypted(const struct rxrpc_call *call,
390 					struct rxgk_context *gk,
391 					struct rxrpc_txbuf *txb)
392 {
393 	struct rxgk_header *hdr;
394 	struct scatterlist sg[1];
395 	int ret;
396 
397 	_enter("%x", txb->len);
398 
399 	/* Insert the header into the buffer. */
400 	hdr = txb->data + txb->crypto_header;
401 	hdr->epoch	 = htonl(call->conn->proto.epoch);
402 	hdr->cid	 = htonl(call->cid);
403 	hdr->call_number = htonl(call->call_id);
404 	hdr->seq	 = htonl(txb->seq);
405 	hdr->sec_index	 = htonl(call->security_ix);
406 	hdr->data_len	 = htonl(txb->len);
407 
408 	sg_init_table(sg, 1);
409 	sg_set_buf(&sg[0], txb->data, txb->alloc_size);
410 
411 	ret = crypto_krb5_encrypt(gk->krb5, gk->tx_enc,
412 				  sg, 1, txb->alloc_size,
413 				  txb->crypto_header, txb->sec_header + txb->len,
414 				  false);
415 	if (ret >= 0) {
416 		txb->pkt_len = ret;
417 		if (txb->alloc_size == RXRPC_JUMBO_DATALEN)
418 			txb->jumboable = true;
419 		gk->bytes_remaining -= ret;
420 	}
421 
422 	rxgk_put(gk);
423 	_leave(" = %d", ret);
424 	return ret;
425 }
426 
427 /*
428  * checksum an RxRPC packet header
429  */
430 static int rxgk_secure_packet(struct rxrpc_call *call, struct rxrpc_txbuf *txb)
431 {
432 	struct rxgk_context *gk;
433 	int ret;
434 
435 	_enter("{%d{%x}},{#%u},%u,",
436 	       call->debug_id, key_serial(call->conn->key), txb->seq, txb->len);
437 
438 	gk = rxgk_get_key(call->conn, NULL);
439 	if (IS_ERR(gk))
440 		return PTR_ERR(gk) == -ESTALE ? -EKEYREJECTED : PTR_ERR(gk);
441 
442 	ret = key_validate(call->conn->key);
443 	if (ret < 0) {
444 		rxgk_put(gk);
445 		return ret;
446 	}
447 
448 	call->security_enctype = gk->krb5->etype;
449 	txb->cksum = htons(gk->key_number);
450 
451 	switch (call->conn->security_level) {
452 	case RXRPC_SECURITY_PLAIN:
453 		rxgk_put(gk);
454 		txb->pkt_len = txb->len;
455 		return 0;
456 	case RXRPC_SECURITY_AUTH:
457 		return rxgk_secure_packet_integrity(call, gk, txb);
458 	case RXRPC_SECURITY_ENCRYPT:
459 		return rxgk_secure_packet_encrypted(call, gk, txb);
460 	default:
461 		rxgk_put(gk);
462 		return -EPERM;
463 	}
464 }
465 
466 /*
467  * Integrity mode (check the signature on a packet - level 1 security)
468  */
469 static int rxgk_verify_packet_integrity(struct rxrpc_call *call,
470 					struct rxgk_context *gk,
471 					struct sk_buff *skb)
472 {
473 	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
474 	struct rxgk_header *hdr;
475 	struct krb5_buffer metadata;
476 	unsigned int offset = sp->offset, len = sp->len;
477 	size_t data_offset = 0, data_len = len;
478 	u32 ac;
479 	int ret = -ENOMEM;
480 
481 	_enter("");
482 
483 	crypto_krb5_where_is_the_data(gk->krb5, KRB5_CHECKSUM_MODE,
484 				      &data_offset, &data_len);
485 
486 	hdr = kzalloc(sizeof(*hdr), GFP_NOFS);
487 	if (!hdr)
488 		goto put_gk;
489 
490 	hdr->epoch	= htonl(call->conn->proto.epoch);
491 	hdr->cid	= htonl(call->cid);
492 	hdr->call_number = htonl(call->call_id);
493 	hdr->seq	= htonl(sp->hdr.seq);
494 	hdr->sec_index	= htonl(call->security_ix);
495 	hdr->data_len	= htonl(data_len);
496 
497 	metadata.len = sizeof(*hdr);
498 	metadata.data = hdr;
499 	ret = rxgk_verify_mic_skb(gk->krb5, gk->rx_Kc, &metadata,
500 				  skb, &offset, &len, &ac);
501 	kfree(hdr);
502 	if (ret == -EPROTO) {
503 		rxrpc_abort_eproto(call, skb, ac,
504 				   rxgk_abort_1_verify_mic_eproto);
505 	} else {
506 		sp->offset = offset;
507 		sp->len = len;
508 	}
509 
510 put_gk:
511 	rxgk_put(gk);
512 	_leave(" = %d", ret);
513 	return ret;
514 }
515 
516 /*
517  * Decrypt an encrypted packet (level 2 security).
518  */
519 static int rxgk_verify_packet_encrypted(struct rxrpc_call *call,
520 					struct rxgk_context *gk,
521 					struct sk_buff *skb)
522 {
523 	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
524 	struct rxgk_header hdr;
525 	unsigned int offset = sp->offset, len = sp->len;
526 	int ret;
527 	u32 ac;
528 
529 	_enter("");
530 
531 	ret = rxgk_decrypt_skb(gk->krb5, gk->rx_enc, skb, &offset, &len, &ac);
532 	if (ret == -EPROTO)
533 		rxrpc_abort_eproto(call, skb, ac, rxgk_abort_2_decrypt_eproto);
534 	if (ret < 0)
535 		goto error;
536 
537 	if (len < sizeof(hdr)) {
538 		ret = rxrpc_abort_eproto(call, skb, RXGK_PACKETSHORT,
539 					 rxgk_abort_2_short_header);
540 		goto error;
541 	}
542 
543 	/* Extract the header from the skb */
544 	ret = skb_copy_bits(skb, offset, &hdr, sizeof(hdr));
545 	if (ret < 0) {
546 		ret = rxrpc_abort_eproto(call, skb, RXGK_PACKETSHORT,
547 					 rxgk_abort_2_short_encdata);
548 		goto error;
549 	}
550 	offset += sizeof(hdr);
551 	len -= sizeof(hdr);
552 
553 	if (ntohl(hdr.epoch)		!= call->conn->proto.epoch ||
554 	    ntohl(hdr.cid)		!= call->cid ||
555 	    ntohl(hdr.call_number)	!= call->call_id ||
556 	    ntohl(hdr.seq)		!= sp->hdr.seq ||
557 	    ntohl(hdr.sec_index)	!= call->security_ix ||
558 	    ntohl(hdr.data_len)		> len) {
559 		ret = rxrpc_abort_eproto(call, skb, RXGK_SEALEDINCON,
560 					 rxgk_abort_2_short_data);
561 		goto error;
562 	}
563 
564 	sp->offset = offset;
565 	sp->len = ntohl(hdr.data_len);
566 	ret = 0;
567 error:
568 	rxgk_put(gk);
569 	_leave(" = %d", ret);
570 	return ret;
571 }
572 
573 /*
574  * Verify the security on a received packet or subpacket (if part of a
575  * jumbo packet).
576  */
577 static int rxgk_verify_packet(struct rxrpc_call *call, struct sk_buff *skb)
578 {
579 	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
580 	struct rxgk_context *gk;
581 	u16 key_number = sp->hdr.cksum;
582 
583 	_enter("{%d{%x}},{#%u}",
584 	       call->debug_id, key_serial(call->conn->key), sp->hdr.seq);
585 
586 	gk = rxgk_get_key(call->conn, &key_number);
587 	if (IS_ERR(gk)) {
588 		switch (PTR_ERR(gk)) {
589 		case -ESTALE:
590 			return rxrpc_abort_eproto(call, skb, RXGK_BADKEYNO,
591 						  rxgk_abort_bad_key_number);
592 		default:
593 			return PTR_ERR(gk);
594 		}
595 	}
596 
597 	call->security_enctype = gk->krb5->etype;
598 	switch (call->conn->security_level) {
599 	case RXRPC_SECURITY_PLAIN:
600 		rxgk_put(gk);
601 		return 0;
602 	case RXRPC_SECURITY_AUTH:
603 		return rxgk_verify_packet_integrity(call, gk, skb);
604 	case RXRPC_SECURITY_ENCRYPT:
605 		return rxgk_verify_packet_encrypted(call, gk, skb);
606 	default:
607 		rxgk_put(gk);
608 		return -ENOANO;
609 	}
610 }
611 
612 /*
613  * Allocate memory to hold a challenge or a response packet.  We're not running
614  * in the io_thread, so we can't use ->tx_alloc.
615  */
616 static struct page *rxgk_alloc_packet(size_t total_len)
617 {
618 	gfp_t gfp = GFP_NOFS;
619 	int order;
620 
621 	order = get_order(total_len);
622 	if (order > 0)
623 		gfp |= __GFP_COMP;
624 	return alloc_pages(gfp, order);
625 }
626 
627 /*
628  * Issue a challenge.
629  */
630 static int rxgk_issue_challenge(struct rxrpc_connection *conn)
631 {
632 	struct rxrpc_wire_header *whdr;
633 	struct bio_vec bvec[1];
634 	struct msghdr msg;
635 	struct page *page;
636 	size_t len = sizeof(*whdr) + sizeof(conn->rxgk.nonce);
637 	u32 serial;
638 	int ret;
639 
640 	_enter("{%d}", conn->debug_id);
641 
642 	get_random_bytes(&conn->rxgk.nonce, sizeof(conn->rxgk.nonce));
643 
644 	/* We can't use conn->tx_alloc without a lock */
645 	page = rxgk_alloc_packet(sizeof(*whdr) + sizeof(conn->rxgk.nonce));
646 	if (!page)
647 		return -ENOMEM;
648 
649 	bvec_set_page(&bvec[0], page, len, 0);
650 	iov_iter_bvec(&msg.msg_iter, WRITE, bvec, 1, len);
651 
652 	msg.msg_name	= &conn->peer->srx.transport;
653 	msg.msg_namelen	= conn->peer->srx.transport_len;
654 	msg.msg_control	= NULL;
655 	msg.msg_controllen = 0;
656 	msg.msg_flags	= MSG_SPLICE_PAGES;
657 
658 	whdr = page_address(page);
659 	whdr->epoch	= htonl(conn->proto.epoch);
660 	whdr->cid	= htonl(conn->proto.cid);
661 	whdr->callNumber = 0;
662 	whdr->seq	= 0;
663 	whdr->type	= RXRPC_PACKET_TYPE_CHALLENGE;
664 	whdr->flags	= conn->out_clientflag;
665 	whdr->userStatus = 0;
666 	whdr->securityIndex = conn->security_ix;
667 	whdr->_rsvd	= 0;
668 	whdr->serviceId	= htons(conn->service_id);
669 
670 	memcpy(whdr + 1, conn->rxgk.nonce, sizeof(conn->rxgk.nonce));
671 
672 	serial = rxrpc_get_next_serials(conn, 1);
673 	whdr->serial = htonl(serial);
674 
675 	trace_rxrpc_tx_challenge(conn, serial, 0, *(u32 *)&conn->rxgk.nonce);
676 
677 	ret = do_udp_sendmsg(conn->local->socket, &msg, len);
678 	if (ret > 0)
679 		conn->peer->last_tx_at = ktime_get_seconds();
680 	__free_page(page);
681 
682 	if (ret < 0) {
683 		trace_rxrpc_tx_fail(conn->debug_id, serial, ret,
684 				    rxrpc_tx_point_rxgk_challenge);
685 		return -EAGAIN;
686 	}
687 
688 	trace_rxrpc_tx_packet(conn->debug_id, whdr,
689 			      rxrpc_tx_point_rxgk_challenge);
690 	_leave(" = 0");
691 	return 0;
692 }
693 
694 /*
695  * Validate a challenge packet.
696  */
697 static bool rxgk_validate_challenge(struct rxrpc_connection *conn,
698 				    struct sk_buff *skb)
699 {
700 	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
701 	u8 nonce[20];
702 
703 	if (!conn->key) {
704 		rxrpc_abort_conn(conn, skb, RX_PROTOCOL_ERROR, -EPROTO,
705 				 rxgk_abort_chall_no_key);
706 		return false;
707 	}
708 
709 	if (key_validate(conn->key) < 0) {
710 		rxrpc_abort_conn(conn, skb, RXGK_EXPIRED, -EPROTO,
711 				 rxgk_abort_chall_key_expired);
712 		return false;
713 	}
714 
715 	if (skb_copy_bits(skb, sizeof(struct rxrpc_wire_header),
716 			  nonce, sizeof(nonce)) < 0) {
717 		rxrpc_abort_conn(conn, skb, RXGK_PACKETSHORT, -EPROTO,
718 				 rxgk_abort_chall_short);
719 		return false;
720 	}
721 
722 	trace_rxrpc_rx_challenge(conn, sp->hdr.serial, 0, *(u32 *)nonce, 0);
723 	return true;
724 }
725 
726 /**
727  * rxgk_kernel_query_challenge - Query RxGK-specific challenge parameters
728  * @challenge: The challenge packet to query
729  *
730  * Return: The Kerberos 5 encoding type for the challenged connection.
731  */
732 u32 rxgk_kernel_query_challenge(struct sk_buff *challenge)
733 {
734 	struct rxrpc_skb_priv *sp = rxrpc_skb(challenge);
735 
736 	return sp->chall.conn->rxgk.enctype;
737 }
738 EXPORT_SYMBOL(rxgk_kernel_query_challenge);
739 
740 /*
741  * Fill out the control message to pass to userspace to inform about the
742  * challenge.
743  */
744 static int rxgk_challenge_to_recvmsg(struct rxrpc_connection *conn,
745 				     struct sk_buff *challenge,
746 				     struct msghdr *msg)
747 {
748 	struct rxgk_challenge chall;
749 
750 	chall.base.service_id		= conn->service_id;
751 	chall.base.security_index	= conn->security_ix;
752 	chall.enctype			= conn->rxgk.enctype;
753 
754 	return put_cmsg(msg, SOL_RXRPC, RXRPC_CHALLENGED, sizeof(chall), &chall);
755 }
756 
757 /*
758  * Insert the requisite amount of XDR padding for the length given.
759  */
760 static int rxgk_pad_out(struct sk_buff *response, size_t len, size_t offset)
761 {
762 	__be32 zero = 0;
763 	size_t pad = xdr_round_up(len) - len;
764 	int ret;
765 
766 	if (!pad)
767 		return 0;
768 
769 	ret = skb_store_bits(response, offset, &zero, pad);
770 	if (ret < 0)
771 		return ret;
772 	return pad;
773 }
774 
775 /*
776  * Insert the header into the response.
777  */
778 static noinline ssize_t rxgk_insert_response_header(struct rxrpc_connection *conn,
779 						    struct rxgk_context *gk,
780 						    struct sk_buff *response,
781 						    size_t offset)
782 {
783 	struct rxrpc_skb_priv *rsp = rxrpc_skb(response);
784 
785 	struct {
786 		struct rxrpc_wire_header whdr;
787 		__be32 start_time_msw;
788 		__be32 start_time_lsw;
789 		__be32 ticket_len;
790 	} h;
791 	int ret;
792 
793 	rsp->resp.kvno		= gk->key_number;
794 	rsp->resp.version	= gk->krb5->etype;
795 
796 	h.whdr.epoch		= htonl(conn->proto.epoch);
797 	h.whdr.cid		= htonl(conn->proto.cid);
798 	h.whdr.callNumber	= 0;
799 	h.whdr.serial		= 0;
800 	h.whdr.seq		= 0;
801 	h.whdr.type		= RXRPC_PACKET_TYPE_RESPONSE;
802 	h.whdr.flags		= conn->out_clientflag;
803 	h.whdr.userStatus	= 0;
804 	h.whdr.securityIndex	= conn->security_ix;
805 	h.whdr.cksum		= htons(gk->key_number);
806 	h.whdr.serviceId	= htons(conn->service_id);
807 	h.start_time_msw	= htonl(upper_32_bits(conn->rxgk.start_time));
808 	h.start_time_lsw	= htonl(lower_32_bits(conn->rxgk.start_time));
809 	h.ticket_len		= htonl(gk->key->ticket.len);
810 
811 	ret = skb_store_bits(response, offset, &h, sizeof(h));
812 	return ret < 0 ? ret : sizeof(h);
813 }
814 
815 /*
816  * Construct the authenticator to go in the response packet
817  *
818  * struct RXGK_Authenticator {
819  *	opaque nonce[20];
820  *	opaque appdata<>;
821  *	RXGK_Level level;
822  *	unsigned int epoch;
823  *	unsigned int cid;
824  *	unsigned int call_numbers<>;
825  * };
826  */
827 static ssize_t rxgk_construct_authenticator(struct rxrpc_connection *conn,
828 					    struct sk_buff *challenge,
829 					    const struct krb5_buffer *appdata,
830 					    struct sk_buff *response,
831 					    size_t offset)
832 {
833 	struct {
834 		u8	nonce[20];
835 		__be32	appdata_len;
836 	} a;
837 	struct {
838 		__be32	level;
839 		__be32	epoch;
840 		__be32	cid;
841 		__be32	call_numbers_count;
842 		__be32	call_numbers[4];
843 	} b;
844 	int ret;
845 
846 	ret = skb_copy_bits(challenge, sizeof(struct rxrpc_wire_header),
847 			    a.nonce, sizeof(a.nonce));
848 	if (ret < 0)
849 		return -EPROTO;
850 
851 	a.appdata_len = htonl(appdata->len);
852 
853 	ret = skb_store_bits(response, offset, &a, sizeof(a));
854 	if (ret < 0)
855 		return ret;
856 	offset += sizeof(a);
857 
858 	if (appdata->len) {
859 		ret = skb_store_bits(response, offset, appdata->data, appdata->len);
860 		if (ret < 0)
861 			return ret;
862 		offset += appdata->len;
863 
864 		ret = rxgk_pad_out(response, appdata->len, offset);
865 		if (ret < 0)
866 			return ret;
867 		offset += ret;
868 	}
869 
870 	b.level			= htonl(conn->security_level);
871 	b.epoch			= htonl(conn->proto.epoch);
872 	b.cid			= htonl(conn->proto.cid);
873 	b.call_numbers_count	= htonl(4);
874 	b.call_numbers[0]	= htonl(conn->channels[0].call_counter);
875 	b.call_numbers[1]	= htonl(conn->channels[1].call_counter);
876 	b.call_numbers[2]	= htonl(conn->channels[2].call_counter);
877 	b.call_numbers[3]	= htonl(conn->channels[3].call_counter);
878 
879 	ret = skb_store_bits(response, offset, &b, sizeof(b));
880 	if (ret < 0)
881 		return ret;
882 	return sizeof(a) + xdr_round_up(appdata->len) + sizeof(b);
883 }
884 
885 static ssize_t rxgk_encrypt_authenticator(struct rxrpc_connection *conn,
886 					  struct rxgk_context *gk,
887 					  struct sk_buff *response,
888 					  size_t offset,
889 					  size_t alloc_len,
890 					  size_t auth_offset,
891 					  size_t auth_len)
892 {
893 	struct scatterlist sg[16];
894 	int nr_sg;
895 
896 	sg_init_table(sg, ARRAY_SIZE(sg));
897 	nr_sg = skb_to_sgvec(response, sg, offset, alloc_len);
898 	if (unlikely(nr_sg < 0))
899 		return nr_sg;
900 	return crypto_krb5_encrypt(gk->krb5, gk->resp_enc, sg, nr_sg, alloc_len,
901 				   auth_offset, auth_len, false);
902 }
903 
904 /*
905  * Construct the response.
906  *
907  * struct RXGK_Response {
908  *	rxgkTime start_time;
909  *	RXGK_Data token;
910  *	opaque authenticator<RXGK_MAXAUTHENTICATOR>
911  * };
912  */
913 static int rxgk_construct_response(struct rxrpc_connection *conn,
914 				   struct sk_buff *challenge,
915 				   struct krb5_buffer *appdata)
916 {
917 	struct rxrpc_skb_priv *csp, *rsp;
918 	struct rxgk_context *gk;
919 	struct sk_buff *response;
920 	size_t len, auth_len, authx_len, offset, auth_offset, authx_offset;
921 	__be32 tmp;
922 	int ret;
923 
924 	gk = rxgk_get_key(conn, NULL);
925 	if (IS_ERR(gk))
926 		return PTR_ERR(gk);
927 
928 	auth_len = 20 + (4 + appdata->len) + 12 + (1 + 4) * 4;
929 	authx_len = crypto_krb5_how_much_buffer(gk->krb5, KRB5_ENCRYPT_MODE,
930 						auth_len, &auth_offset);
931 	len = sizeof(struct rxrpc_wire_header) +
932 		8 + (4 + xdr_round_up(gk->key->ticket.len)) + (4 + authx_len);
933 
934 	response = alloc_skb_with_frags(0, len, 0, &ret, GFP_NOFS);
935 	if (!response)
936 		goto error;
937 	rxrpc_new_skb(response, rxrpc_skb_new_response_rxgk);
938 	response->len = len;
939 	response->data_len = len;
940 
941 	ret = rxgk_insert_response_header(conn, gk, response, 0);
942 	if (ret < 0)
943 		goto error;
944 	offset = ret;
945 
946 	ret = skb_store_bits(response, offset, gk->key->ticket.data, gk->key->ticket.len);
947 	if (ret < 0)
948 		goto error;
949 	offset += gk->key->ticket.len;
950 	ret = rxgk_pad_out(response, gk->key->ticket.len, offset);
951 	if (ret < 0)
952 		goto error;
953 
954 	authx_offset = offset + ret + 4; /* Leave a gap for the length. */
955 
956 	ret = rxgk_construct_authenticator(conn, challenge, appdata, response,
957 					   authx_offset + auth_offset);
958 	if (ret < 0)
959 		goto error;
960 	auth_len = ret;
961 
962 	ret = rxgk_encrypt_authenticator(conn, gk, response,
963 					 authx_offset, authx_len,
964 					 auth_offset, auth_len);
965 	if (ret < 0)
966 		goto error;
967 	authx_len = ret;
968 
969 	tmp = htonl(authx_len);
970 	ret = skb_store_bits(response, authx_offset - 4, &tmp, 4);
971 	if (ret < 0)
972 		goto error;
973 
974 	ret = rxgk_pad_out(response, authx_len, authx_offset + authx_len);
975 	if (ret < 0)
976 		goto error;
977 	len = authx_offset + authx_len + ret;
978 
979 	if (len != response->len) {
980 		response->len = len;
981 		response->data_len = len;
982 	}
983 
984 	csp = rxrpc_skb(challenge);
985 	rsp = rxrpc_skb(response);
986 	rsp->resp.len = len;
987 	rsp->resp.challenge_serial = csp->hdr.serial;
988 	rxrpc_post_response(conn, response);
989 	response = NULL;
990 	ret = 0;
991 
992 error:
993 	rxrpc_free_skb(response, rxrpc_skb_put_response);
994 	rxgk_put(gk);
995 	_leave(" = %d", ret);
996 	return ret;
997 }
998 
999 /*
1000  * Respond to a challenge packet.
1001  */
1002 static int rxgk_respond_to_challenge(struct rxrpc_connection *conn,
1003 				     struct sk_buff *challenge,
1004 				     struct krb5_buffer *appdata)
1005 {
1006 	_enter("{%d,%x}", conn->debug_id, key_serial(conn->key));
1007 
1008 	if (key_validate(conn->key) < 0)
1009 		return rxrpc_abort_conn(conn, NULL, RXGK_EXPIRED, -EPROTO,
1010 					rxgk_abort_chall_key_expired);
1011 
1012 	return rxgk_construct_response(conn, challenge, appdata);
1013 }
1014 
1015 static int rxgk_respond_to_challenge_no_appdata(struct rxrpc_connection *conn,
1016 						struct sk_buff *challenge)
1017 {
1018 	struct krb5_buffer appdata = {};
1019 
1020 	return rxgk_respond_to_challenge(conn, challenge, &appdata);
1021 }
1022 
1023 /**
1024  * rxgk_kernel_respond_to_challenge - Respond to a challenge with appdata
1025  * @challenge: The challenge to respond to
1026  * @appdata: The application data to include in the RESPONSE authenticator
1027  *
1028  * Allow a kernel application to respond to a CHALLENGE with application data
1029  * to be included in the RxGK RESPONSE Authenticator.
1030  *
1031  * Return: %0 if successful and a negative error code otherwise.
1032  */
1033 int rxgk_kernel_respond_to_challenge(struct sk_buff *challenge,
1034 				     struct krb5_buffer *appdata)
1035 {
1036 	struct rxrpc_skb_priv *csp = rxrpc_skb(challenge);
1037 
1038 	return rxgk_respond_to_challenge(csp->chall.conn, challenge, appdata);
1039 }
1040 EXPORT_SYMBOL(rxgk_kernel_respond_to_challenge);
1041 
1042 /*
1043  * Parse sendmsg() control message and respond to challenge.  We need to see if
1044  * there's an appdata to fish out.
1045  */
1046 static int rxgk_sendmsg_respond_to_challenge(struct sk_buff *challenge,
1047 					     struct msghdr *msg)
1048 {
1049 	struct krb5_buffer appdata = {};
1050 	struct cmsghdr *cmsg;
1051 
1052 	for_each_cmsghdr(cmsg, msg) {
1053 		if (cmsg->cmsg_level != SOL_RXRPC ||
1054 		    cmsg->cmsg_type != RXRPC_RESP_RXGK_APPDATA)
1055 			continue;
1056 		if (appdata.data)
1057 			return -EINVAL;
1058 		appdata.data = CMSG_DATA(cmsg);
1059 		appdata.len = cmsg->cmsg_len - sizeof(struct cmsghdr);
1060 	}
1061 
1062 	return rxgk_kernel_respond_to_challenge(challenge, &appdata);
1063 }
1064 
1065 /*
1066  * Verify the authenticator.
1067  *
1068  * struct RXGK_Authenticator {
1069  *	opaque nonce[20];
1070  *	opaque appdata<>;
1071  *	RXGK_Level level;
1072  *	unsigned int epoch;
1073  *	unsigned int cid;
1074  *	unsigned int call_numbers<>;
1075  * };
1076  */
1077 static int rxgk_do_verify_authenticator(struct rxrpc_connection *conn,
1078 					const struct krb5_enctype *krb5,
1079 					struct sk_buff *skb,
1080 					__be32 *p, __be32 *end)
1081 {
1082 	u32 app_len, call_count, level, epoch, cid, i;
1083 
1084 	_enter("");
1085 
1086 	if (memcmp(p, conn->rxgk.nonce, 20) != 0)
1087 		return rxrpc_abort_conn(conn, skb, RXGK_NOTAUTH, -EPROTO,
1088 					rxgk_abort_resp_bad_nonce);
1089 	p += 20 / sizeof(__be32);
1090 
1091 	app_len	= ntohl(*p++);
1092 	if (app_len > (end - p) * sizeof(__be32))
1093 		return rxrpc_abort_conn(conn, skb, RXGK_NOTAUTH, -EPROTO,
1094 					rxgk_abort_resp_short_applen);
1095 
1096 	p += xdr_round_up(app_len) / sizeof(__be32);
1097 	if (end - p < 4)
1098 		return rxrpc_abort_conn(conn, skb, RXGK_NOTAUTH, -EPROTO,
1099 					rxgk_abort_resp_short_applen);
1100 
1101 	level	= ntohl(*p++);
1102 	epoch	= ntohl(*p++);
1103 	cid	= ntohl(*p++);
1104 	call_count = ntohl(*p++);
1105 
1106 	if (level	!= conn->security_level ||
1107 	    epoch	!= conn->proto.epoch ||
1108 	    cid		!= conn->proto.cid ||
1109 	    call_count	> 4)
1110 		return rxrpc_abort_conn(conn, skb, RXGK_NOTAUTH, -EPROTO,
1111 					rxgk_abort_resp_bad_param);
1112 
1113 	if (end - p < call_count)
1114 		return rxrpc_abort_conn(conn, skb, RXGK_NOTAUTH, -EPROTO,
1115 					rxgk_abort_resp_short_call_list);
1116 
1117 	for (i = 0; i < call_count; i++) {
1118 		u32 call_id = ntohl(*p++);
1119 
1120 		if (call_id > INT_MAX)
1121 			return rxrpc_abort_conn(conn, skb, RXGK_NOTAUTH, -EPROTO,
1122 						rxgk_abort_resp_bad_callid);
1123 
1124 		if (call_id < conn->channels[i].call_counter)
1125 			return rxrpc_abort_conn(conn, skb, RXGK_NOTAUTH, -EPROTO,
1126 						rxgk_abort_resp_call_ctr);
1127 
1128 		if (call_id > conn->channels[i].call_counter) {
1129 			if (conn->channels[i].call)
1130 				return rxrpc_abort_conn(conn, skb, RXGK_NOTAUTH, -EPROTO,
1131 							rxgk_abort_resp_call_state);
1132 
1133 			conn->channels[i].call_counter = call_id;
1134 		}
1135 	}
1136 
1137 	_leave(" = 0");
1138 	return 0;
1139 }
1140 
1141 /*
1142  * Extract the authenticator and verify it.
1143  */
1144 static int rxgk_verify_authenticator(struct rxrpc_connection *conn,
1145 				     const struct krb5_enctype *krb5,
1146 				     struct sk_buff *skb,
1147 				     unsigned int auth_offset, unsigned int auth_len)
1148 {
1149 	void *auth;
1150 	__be32 *p;
1151 	int ret;
1152 
1153 	auth = kmalloc(auth_len, GFP_NOFS);
1154 	if (!auth)
1155 		return -ENOMEM;
1156 
1157 	ret = skb_copy_bits(skb, auth_offset, auth, auth_len);
1158 	if (ret < 0) {
1159 		ret = rxrpc_abort_conn(conn, skb, RXGK_NOTAUTH, -EPROTO,
1160 				       rxgk_abort_resp_short_auth);
1161 		goto error;
1162 	}
1163 
1164 	p = auth;
1165 	ret = rxgk_do_verify_authenticator(conn, krb5, skb, p, p + auth_len);
1166 error:
1167 	kfree(auth);
1168 	return ret;
1169 }
1170 
1171 /*
1172  * Verify a response.
1173  *
1174  * struct RXGK_Response {
1175  *	rxgkTime	start_time;
1176  *	RXGK_Data	token;
1177  *	opaque		authenticator<RXGK_MAXAUTHENTICATOR>
1178  * };
1179  */
1180 static int rxgk_verify_response(struct rxrpc_connection *conn,
1181 				struct sk_buff *skb)
1182 {
1183 	const struct krb5_enctype *krb5;
1184 	struct rxrpc_key_token *token;
1185 	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
1186 	struct rxgk_response rhdr;
1187 	struct rxgk_context *gk;
1188 	struct key *key = NULL;
1189 	unsigned int offset = sizeof(struct rxrpc_wire_header);
1190 	unsigned int len = skb->len - sizeof(struct rxrpc_wire_header);
1191 	unsigned int token_offset, token_len;
1192 	unsigned int auth_offset, auth_len;
1193 	__be32 xauth_len;
1194 	int ret, ec;
1195 
1196 	_enter("{%d}", conn->debug_id);
1197 
1198 	/* Parse the RXGK_Response object */
1199 	if (sizeof(rhdr) + sizeof(__be32) > len)
1200 		goto short_packet;
1201 
1202 	if (skb_copy_bits(skb, offset, &rhdr, sizeof(rhdr)) < 0)
1203 		goto short_packet;
1204 	offset	+= sizeof(rhdr);
1205 	len	-= sizeof(rhdr);
1206 
1207 	token_offset	= offset;
1208 	token_len	= ntohl(rhdr.token_len);
1209 	if (xdr_round_up(token_len) + sizeof(__be32) > len)
1210 		goto short_packet;
1211 
1212 	trace_rxrpc_rx_response(conn, sp->hdr.serial, 0, sp->hdr.cksum, token_len);
1213 
1214 	offset	+= xdr_round_up(token_len);
1215 	len	-= xdr_round_up(token_len);
1216 
1217 	if (skb_copy_bits(skb, offset, &xauth_len, sizeof(xauth_len)) < 0)
1218 		goto short_packet;
1219 	offset	+= sizeof(xauth_len);
1220 	len	-= sizeof(xauth_len);
1221 
1222 	auth_offset	= offset;
1223 	auth_len	= ntohl(xauth_len);
1224 	if (auth_len < len)
1225 		goto short_packet;
1226 	if (auth_len & 3)
1227 		goto inconsistent;
1228 	if (auth_len < 20 + 9 * 4)
1229 		goto auth_too_short;
1230 
1231 	/* We need to extract and decrypt the token and instantiate a session
1232 	 * key for it.  This bit, however, is application-specific.  If
1233 	 * possible, we use a default parser, but we might end up bumping this
1234 	 * to the app to deal with - which might mean a round trip to
1235 	 * userspace.
1236 	 */
1237 	ret = rxgk_extract_token(conn, skb, token_offset, token_len, &key);
1238 	if (ret < 0)
1239 		goto out;
1240 
1241 	/* We now have a key instantiated from the decrypted ticket.  We can
1242 	 * pass this to the application so that they can parse the ticket
1243 	 * content and we can use the session key it contains to derive the
1244 	 * keys we need.
1245 	 *
1246 	 * Note that we have to switch enctype at this point as the enctype of
1247 	 * the ticket doesn't necessarily match that of the transport.
1248 	 */
1249 	token = key->payload.data[0];
1250 	conn->security_level = token->rxgk->level;
1251 	conn->rxgk.start_time = __be64_to_cpu(rhdr.start_time);
1252 
1253 	gk = rxgk_generate_transport_key(conn, token->rxgk, sp->hdr.cksum, GFP_NOFS);
1254 	if (IS_ERR(gk)) {
1255 		ret = PTR_ERR(gk);
1256 		goto cant_get_token;
1257 	}
1258 
1259 	krb5 = gk->krb5;
1260 
1261 	trace_rxrpc_rx_response(conn, sp->hdr.serial, krb5->etype, sp->hdr.cksum, token_len);
1262 
1263 	/* Decrypt, parse and verify the authenticator. */
1264 	ret = rxgk_decrypt_skb(krb5, gk->resp_enc, skb,
1265 			       &auth_offset, &auth_len, &ec);
1266 	if (ret < 0) {
1267 		rxrpc_abort_conn(conn, skb, RXGK_SEALEDINCON, ret,
1268 				 rxgk_abort_resp_auth_dec);
1269 		goto out;
1270 	}
1271 
1272 	ret = rxgk_verify_authenticator(conn, krb5, skb, auth_offset, auth_len);
1273 	if (ret < 0)
1274 		goto out;
1275 
1276 	conn->key = key;
1277 	key = NULL;
1278 	ret = 0;
1279 out:
1280 	key_put(key);
1281 	_leave(" = %d", ret);
1282 	return ret;
1283 
1284 inconsistent:
1285 	ret = rxrpc_abort_conn(conn, skb, RXGK_INCONSISTENCY, -EPROTO,
1286 			       rxgk_abort_resp_xdr_align);
1287 	goto out;
1288 auth_too_short:
1289 	ret = rxrpc_abort_conn(conn, skb, RXGK_PACKETSHORT, -EPROTO,
1290 			       rxgk_abort_resp_short_auth);
1291 	goto out;
1292 short_packet:
1293 	ret = rxrpc_abort_conn(conn, skb, RXGK_PACKETSHORT, -EPROTO,
1294 			       rxgk_abort_resp_short_packet);
1295 	goto out;
1296 
1297 cant_get_token:
1298 	switch (ret) {
1299 	case -ENOMEM:
1300 		goto temporary_error;
1301 	case -EINVAL:
1302 		ret = rxrpc_abort_conn(conn, skb, RXGK_NOTAUTH, -EKEYREJECTED,
1303 				       rxgk_abort_resp_internal_error);
1304 		goto out;
1305 	case -ENOPKG:
1306 		ret = rxrpc_abort_conn(conn, skb, KRB5_PROG_KEYTYPE_NOSUPP,
1307 				       -EKEYREJECTED, rxgk_abort_resp_nopkg);
1308 		goto out;
1309 	}
1310 
1311 temporary_error:
1312 	/* Ignore the response packet if we got a temporary error such as
1313 	 * ENOMEM.  We just want to send the challenge again.  Note that we
1314 	 * also come out this way if the ticket decryption fails.
1315 	 */
1316 	goto out;
1317 }
1318 
1319 /*
1320  * clear the connection security
1321  */
1322 static void rxgk_clear(struct rxrpc_connection *conn)
1323 {
1324 	int i;
1325 
1326 	for (i = 0; i < ARRAY_SIZE(conn->rxgk.keys); i++)
1327 		rxgk_put(conn->rxgk.keys[i]);
1328 }
1329 
1330 /*
1331  * Initialise the RxGK security service.
1332  */
1333 static int rxgk_init(void)
1334 {
1335 	return 0;
1336 }
1337 
1338 /*
1339  * Clean up the RxGK security service.
1340  */
1341 static void rxgk_exit(void)
1342 {
1343 }
1344 
1345 /*
1346  * RxRPC YFS GSSAPI-based security
1347  */
1348 const struct rxrpc_security rxgk_yfs = {
1349 	.name				= "yfs-rxgk",
1350 	.security_index			= RXRPC_SECURITY_YFS_RXGK,
1351 	.no_key_abort			= RXGK_NOTAUTH,
1352 	.init				= rxgk_init,
1353 	.exit				= rxgk_exit,
1354 	.preparse_server_key		= rxgk_preparse_server_key,
1355 	.free_preparse_server_key	= rxgk_free_preparse_server_key,
1356 	.destroy_server_key		= rxgk_destroy_server_key,
1357 	.describe_server_key		= rxgk_describe_server_key,
1358 	.init_connection_security	= rxgk_init_connection_security,
1359 	.alloc_txbuf			= rxgk_alloc_txbuf,
1360 	.secure_packet			= rxgk_secure_packet,
1361 	.verify_packet			= rxgk_verify_packet,
1362 	.free_call_crypto		= rxgk_free_call_crypto,
1363 	.issue_challenge		= rxgk_issue_challenge,
1364 	.validate_challenge		= rxgk_validate_challenge,
1365 	.challenge_to_recvmsg		= rxgk_challenge_to_recvmsg,
1366 	.sendmsg_respond_to_challenge	= rxgk_sendmsg_respond_to_challenge,
1367 	.respond_to_challenge		= rxgk_respond_to_challenge_no_appdata,
1368 	.verify_response		= rxgk_verify_response,
1369 	.clear				= rxgk_clear,
1370 	.default_decode_ticket		= rxgk_yfs_decode_ticket,
1371 };
1372