xref: /openbmc/linux/net/rxrpc/key.c (revision 0d3b051a) 
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* RxRPC key management
3  *
4  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
5  * Written by David Howells (dhowells@redhat.com)
6  *
7  * RxRPC keys should have a description of describing their purpose:
8  *	"afs@example.com"
9  */
10 
11 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12 
13 #include <crypto/skcipher.h>
14 #include <linux/module.h>
15 #include <linux/net.h>
16 #include <linux/skbuff.h>
17 #include <linux/key-type.h>
18 #include <linux/ctype.h>
19 #include <linux/slab.h>
20 #include <net/sock.h>
21 #include <net/af_rxrpc.h>
22 #include <keys/rxrpc-type.h>
23 #include <keys/user-type.h>
24 #include "ar-internal.h"
25 
26 static int rxrpc_preparse(struct key_preparsed_payload *);
27 static void rxrpc_free_preparse(struct key_preparsed_payload *);
28 static void rxrpc_destroy(struct key *);
29 static void rxrpc_describe(const struct key *, struct seq_file *);
30 static long rxrpc_read(const struct key *, char *, size_t);
31 
32 /*
33  * rxrpc defined keys take an arbitrary string as the description and an
34  * arbitrary blob of data as the payload
35  */
36 struct key_type key_type_rxrpc = {
37 	.name		= "rxrpc",
38 	.flags		= KEY_TYPE_NET_DOMAIN,
39 	.preparse	= rxrpc_preparse,
40 	.free_preparse	= rxrpc_free_preparse,
41 	.instantiate	= generic_key_instantiate,
42 	.destroy	= rxrpc_destroy,
43 	.describe	= rxrpc_describe,
44 	.read		= rxrpc_read,
45 };
46 EXPORT_SYMBOL(key_type_rxrpc);
47 
48 /*
49  * parse an RxKAD type XDR format token
50  * - the caller guarantees we have at least 4 words
51  */
52 static int rxrpc_preparse_xdr_rxkad(struct key_preparsed_payload *prep,
53 				    size_t datalen,
54 				    const __be32 *xdr, unsigned int toklen)
55 {
56 	struct rxrpc_key_token *token, **pptoken;
57 	time64_t expiry;
58 	size_t plen;
59 	u32 tktlen;
60 
61 	_enter(",{%x,%x,%x,%x},%u",
62 	       ntohl(xdr[0]), ntohl(xdr[1]), ntohl(xdr[2]), ntohl(xdr[3]),
63 	       toklen);
64 
65 	if (toklen <= 8 * 4)
66 		return -EKEYREJECTED;
67 	tktlen = ntohl(xdr[7]);
68 	_debug("tktlen: %x", tktlen);
69 	if (tktlen > AFSTOKEN_RK_TIX_MAX)
70 		return -EKEYREJECTED;
71 	if (toklen < 8 * 4 + tktlen)
72 		return -EKEYREJECTED;
73 
74 	plen = sizeof(*token) + sizeof(*token->kad) + tktlen;
75 	prep->quotalen = datalen + plen;
76 
77 	plen -= sizeof(*token);
78 	token = kzalloc(sizeof(*token), GFP_KERNEL);
79 	if (!token)
80 		return -ENOMEM;
81 
82 	token->kad = kzalloc(plen, GFP_KERNEL);
83 	if (!token->kad) {
84 		kfree(token);
85 		return -ENOMEM;
86 	}
87 
88 	token->security_index	= RXRPC_SECURITY_RXKAD;
89 	token->kad->ticket_len	= tktlen;
90 	token->kad->vice_id	= ntohl(xdr[0]);
91 	token->kad->kvno	= ntohl(xdr[1]);
92 	token->kad->start	= ntohl(xdr[4]);
93 	token->kad->expiry	= ntohl(xdr[5]);
94 	token->kad->primary_flag = ntohl(xdr[6]);
95 	memcpy(&token->kad->session_key, &xdr[2], 8);
96 	memcpy(&token->kad->ticket, &xdr[8], tktlen);
97 
98 	_debug("SCIX: %u", token->security_index);
99 	_debug("TLEN: %u", token->kad->ticket_len);
100 	_debug("EXPY: %x", token->kad->expiry);
101 	_debug("KVNO: %u", token->kad->kvno);
102 	_debug("PRIM: %u", token->kad->primary_flag);
103 	_debug("SKEY: %02x%02x%02x%02x%02x%02x%02x%02x",
104 	       token->kad->session_key[0], token->kad->session_key[1],
105 	       token->kad->session_key[2], token->kad->session_key[3],
106 	       token->kad->session_key[4], token->kad->session_key[5],
107 	       token->kad->session_key[6], token->kad->session_key[7]);
108 	if (token->kad->ticket_len >= 8)
109 		_debug("TCKT: %02x%02x%02x%02x%02x%02x%02x%02x",
110 		       token->kad->ticket[0], token->kad->ticket[1],
111 		       token->kad->ticket[2], token->kad->ticket[3],
112 		       token->kad->ticket[4], token->kad->ticket[5],
113 		       token->kad->ticket[6], token->kad->ticket[7]);
114 
115 	/* count the number of tokens attached */
116 	prep->payload.data[1] = (void *)((unsigned long)prep->payload.data[1] + 1);
117 
118 	/* attach the data */
119 	for (pptoken = (struct rxrpc_key_token **)&prep->payload.data[0];
120 	     *pptoken;
121 	     pptoken = &(*pptoken)->next)
122 		continue;
123 	*pptoken = token;
124 	expiry = rxrpc_u32_to_time64(token->kad->expiry);
125 	if (expiry < prep->expiry)
126 		prep->expiry = expiry;
127 
128 	_leave(" = 0");
129 	return 0;
130 }
131 
132 /*
133  * attempt to parse the data as the XDR format
134  * - the caller guarantees we have more than 7 words
135  */
136 static int rxrpc_preparse_xdr(struct key_preparsed_payload *prep)
137 {
138 	const __be32 *xdr = prep->data, *token, *p;
139 	const char *cp;
140 	unsigned int len, paddedlen, loop, ntoken, toklen, sec_ix;
141 	size_t datalen = prep->datalen;
142 	int ret, ret2;
143 
144 	_enter(",{%x,%x,%x,%x},%zu",
145 	       ntohl(xdr[0]), ntohl(xdr[1]), ntohl(xdr[2]), ntohl(xdr[3]),
146 	       prep->datalen);
147 
148 	if (datalen > AFSTOKEN_LENGTH_MAX)
149 		goto not_xdr;
150 
151 	/* XDR is an array of __be32's */
152 	if (datalen & 3)
153 		goto not_xdr;
154 
155 	/* the flags should be 0 (the setpag bit must be handled by
156 	 * userspace) */
157 	if (ntohl(*xdr++) != 0)
158 		goto not_xdr;
159 	datalen -= 4;
160 
161 	/* check the cell name */
162 	len = ntohl(*xdr++);
163 	if (len < 1 || len > AFSTOKEN_CELL_MAX)
164 		goto not_xdr;
165 	datalen -= 4;
166 	paddedlen = (len + 3) & ~3;
167 	if (paddedlen > datalen)
168 		goto not_xdr;
169 
170 	cp = (const char *) xdr;
171 	for (loop = 0; loop < len; loop++)
172 		if (!isprint(cp[loop]))
173 			goto not_xdr;
174 	for (; loop < paddedlen; loop++)
175 		if (cp[loop])
176 			goto not_xdr;
177 	_debug("cellname: [%u/%u] '%*.*s'",
178 	       len, paddedlen, len, len, (const char *) xdr);
179 	datalen -= paddedlen;
180 	xdr += paddedlen >> 2;
181 
182 	/* get the token count */
183 	if (datalen < 12)
184 		goto not_xdr;
185 	ntoken = ntohl(*xdr++);
186 	datalen -= 4;
187 	_debug("ntoken: %x", ntoken);
188 	if (ntoken < 1 || ntoken > AFSTOKEN_MAX)
189 		goto not_xdr;
190 
191 	/* check each token wrapper */
192 	p = xdr;
193 	loop = ntoken;
194 	do {
195 		if (datalen < 8)
196 			goto not_xdr;
197 		toklen = ntohl(*p++);
198 		sec_ix = ntohl(*p);
199 		datalen -= 4;
200 		_debug("token: [%x/%zx] %x", toklen, datalen, sec_ix);
201 		paddedlen = (toklen + 3) & ~3;
202 		if (toklen < 20 || toklen > datalen || paddedlen > datalen)
203 			goto not_xdr;
204 		datalen -= paddedlen;
205 		p += paddedlen >> 2;
206 
207 	} while (--loop > 0);
208 
209 	_debug("remainder: %zu", datalen);
210 	if (datalen != 0)
211 		goto not_xdr;
212 
213 	/* okay: we're going to assume it's valid XDR format
214 	 * - we ignore the cellname, relying on the key to be correctly named
215 	 */
216 	ret = -EPROTONOSUPPORT;
217 	do {
218 		toklen = ntohl(*xdr++);
219 		token = xdr;
220 		xdr += (toklen + 3) / 4;
221 
222 		sec_ix = ntohl(*token++);
223 		toklen -= 4;
224 
225 		_debug("TOKEN type=%x len=%x", sec_ix, toklen);
226 
227 		switch (sec_ix) {
228 		case RXRPC_SECURITY_RXKAD:
229 			ret2 = rxrpc_preparse_xdr_rxkad(prep, datalen, token, toklen);
230 			break;
231 		default:
232 			ret2 = -EPROTONOSUPPORT;
233 			break;
234 		}
235 
236 		switch (ret2) {
237 		case 0:
238 			ret = 0;
239 			break;
240 		case -EPROTONOSUPPORT:
241 			break;
242 		case -ENOPKG:
243 			if (ret != 0)
244 				ret = -ENOPKG;
245 			break;
246 		default:
247 			ret = ret2;
248 			goto error;
249 		}
250 
251 	} while (--ntoken > 0);
252 
253 error:
254 	_leave(" = %d", ret);
255 	return ret;
256 
257 not_xdr:
258 	_leave(" = -EPROTO");
259 	return -EPROTO;
260 }
261 
262 /*
263  * Preparse an rxrpc defined key.
264  *
265  * Data should be of the form:
266  *	OFFSET	LEN	CONTENT
267  *	0	4	key interface version number
268  *	4	2	security index (type)
269  *	6	2	ticket length
270  *	8	4	key expiry time (time_t)
271  *	12	4	kvno
272  *	16	8	session key
273  *	24	[len]	ticket
274  *
275  * if no data is provided, then a no-security key is made
276  */
277 static int rxrpc_preparse(struct key_preparsed_payload *prep)
278 {
279 	const struct rxrpc_key_data_v1 *v1;
280 	struct rxrpc_key_token *token, **pp;
281 	time64_t expiry;
282 	size_t plen;
283 	u32 kver;
284 	int ret;
285 
286 	_enter("%zu", prep->datalen);
287 
288 	/* handle a no-security key */
289 	if (!prep->data && prep->datalen == 0)
290 		return 0;
291 
292 	/* determine if the XDR payload format is being used */
293 	if (prep->datalen > 7 * 4) {
294 		ret = rxrpc_preparse_xdr(prep);
295 		if (ret != -EPROTO)
296 			return ret;
297 	}
298 
299 	/* get the key interface version number */
300 	ret = -EINVAL;
301 	if (prep->datalen <= 4 || !prep->data)
302 		goto error;
303 	memcpy(&kver, prep->data, sizeof(kver));
304 	prep->data += sizeof(kver);
305 	prep->datalen -= sizeof(kver);
306 
307 	_debug("KEY I/F VERSION: %u", kver);
308 
309 	ret = -EKEYREJECTED;
310 	if (kver != 1)
311 		goto error;
312 
313 	/* deal with a version 1 key */
314 	ret = -EINVAL;
315 	if (prep->datalen < sizeof(*v1))
316 		goto error;
317 
318 	v1 = prep->data;
319 	if (prep->datalen != sizeof(*v1) + v1->ticket_length)
320 		goto error;
321 
322 	_debug("SCIX: %u", v1->security_index);
323 	_debug("TLEN: %u", v1->ticket_length);
324 	_debug("EXPY: %x", v1->expiry);
325 	_debug("KVNO: %u", v1->kvno);
326 	_debug("SKEY: %02x%02x%02x%02x%02x%02x%02x%02x",
327 	       v1->session_key[0], v1->session_key[1],
328 	       v1->session_key[2], v1->session_key[3],
329 	       v1->session_key[4], v1->session_key[5],
330 	       v1->session_key[6], v1->session_key[7]);
331 	if (v1->ticket_length >= 8)
332 		_debug("TCKT: %02x%02x%02x%02x%02x%02x%02x%02x",
333 		       v1->ticket[0], v1->ticket[1],
334 		       v1->ticket[2], v1->ticket[3],
335 		       v1->ticket[4], v1->ticket[5],
336 		       v1->ticket[6], v1->ticket[7]);
337 
338 	ret = -EPROTONOSUPPORT;
339 	if (v1->security_index != RXRPC_SECURITY_RXKAD)
340 		goto error;
341 
342 	plen = sizeof(*token->kad) + v1->ticket_length;
343 	prep->quotalen = plen + sizeof(*token);
344 
345 	ret = -ENOMEM;
346 	token = kzalloc(sizeof(*token), GFP_KERNEL);
347 	if (!token)
348 		goto error;
349 	token->kad = kzalloc(plen, GFP_KERNEL);
350 	if (!token->kad)
351 		goto error_free;
352 
353 	token->security_index		= RXRPC_SECURITY_RXKAD;
354 	token->kad->ticket_len		= v1->ticket_length;
355 	token->kad->expiry		= v1->expiry;
356 	token->kad->kvno		= v1->kvno;
357 	memcpy(&token->kad->session_key, &v1->session_key, 8);
358 	memcpy(&token->kad->ticket, v1->ticket, v1->ticket_length);
359 
360 	/* count the number of tokens attached */
361 	prep->payload.data[1] = (void *)((unsigned long)prep->payload.data[1] + 1);
362 
363 	/* attach the data */
364 	pp = (struct rxrpc_key_token **)&prep->payload.data[0];
365 	while (*pp)
366 		pp = &(*pp)->next;
367 	*pp = token;
368 	expiry = rxrpc_u32_to_time64(token->kad->expiry);
369 	if (expiry < prep->expiry)
370 		prep->expiry = expiry;
371 	token = NULL;
372 	ret = 0;
373 
374 error_free:
375 	kfree(token);
376 error:
377 	return ret;
378 }
379 
380 /*
381  * Free token list.
382  */
383 static void rxrpc_free_token_list(struct rxrpc_key_token *token)
384 {
385 	struct rxrpc_key_token *next;
386 
387 	for (; token; token = next) {
388 		next = token->next;
389 		switch (token->security_index) {
390 		case RXRPC_SECURITY_RXKAD:
391 			kfree(token->kad);
392 			break;
393 		default:
394 			pr_err("Unknown token type %x on rxrpc key\n",
395 			       token->security_index);
396 			BUG();
397 		}
398 
399 		kfree(token);
400 	}
401 }
402 
403 /*
404  * Clean up preparse data.
405  */
406 static void rxrpc_free_preparse(struct key_preparsed_payload *prep)
407 {
408 	rxrpc_free_token_list(prep->payload.data[0]);
409 }
410 
411 /*
412  * dispose of the data dangling from the corpse of a rxrpc key
413  */
414 static void rxrpc_destroy(struct key *key)
415 {
416 	rxrpc_free_token_list(key->payload.data[0]);
417 }
418 
419 /*
420  * describe the rxrpc key
421  */
422 static void rxrpc_describe(const struct key *key, struct seq_file *m)
423 {
424 	const struct rxrpc_key_token *token;
425 	const char *sep = ": ";
426 
427 	seq_puts(m, key->description);
428 
429 	for (token = key->payload.data[0]; token; token = token->next) {
430 		seq_puts(m, sep);
431 
432 		switch (token->security_index) {
433 		case RXRPC_SECURITY_RXKAD:
434 			seq_puts(m, "ka");
435 			break;
436 		default: /* we have a ticket we can't encode */
437 			seq_printf(m, "%u", token->security_index);
438 			break;
439 		}
440 
441 		sep = " ";
442 	}
443 }
444 
445 /*
446  * grab the security key for a socket
447  */
448 int rxrpc_request_key(struct rxrpc_sock *rx, sockptr_t optval, int optlen)
449 {
450 	struct key *key;
451 	char *description;
452 
453 	_enter("");
454 
455 	if (optlen <= 0 || optlen > PAGE_SIZE - 1 || rx->securities)
456 		return -EINVAL;
457 
458 	description = memdup_sockptr_nul(optval, optlen);
459 	if (IS_ERR(description))
460 		return PTR_ERR(description);
461 
462 	key = request_key_net(&key_type_rxrpc, description, sock_net(&rx->sk), NULL);
463 	if (IS_ERR(key)) {
464 		kfree(description);
465 		_leave(" = %ld", PTR_ERR(key));
466 		return PTR_ERR(key);
467 	}
468 
469 	rx->key = key;
470 	kfree(description);
471 	_leave(" = 0 [key %x]", key->serial);
472 	return 0;
473 }
474 
475 /*
476  * generate a server data key
477  */
478 int rxrpc_get_server_data_key(struct rxrpc_connection *conn,
479 			      const void *session_key,
480 			      time64_t expiry,
481 			      u32 kvno)
482 {
483 	const struct cred *cred = current_cred();
484 	struct key *key;
485 	int ret;
486 
487 	struct {
488 		u32 kver;
489 		struct rxrpc_key_data_v1 v1;
490 	} data;
491 
492 	_enter("");
493 
494 	key = key_alloc(&key_type_rxrpc, "x",
495 			GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, cred, 0,
496 			KEY_ALLOC_NOT_IN_QUOTA, NULL);
497 	if (IS_ERR(key)) {
498 		_leave(" = -ENOMEM [alloc %ld]", PTR_ERR(key));
499 		return -ENOMEM;
500 	}
501 
502 	_debug("key %d", key_serial(key));
503 
504 	data.kver = 1;
505 	data.v1.security_index = RXRPC_SECURITY_RXKAD;
506 	data.v1.ticket_length = 0;
507 	data.v1.expiry = rxrpc_time64_to_u32(expiry);
508 	data.v1.kvno = 0;
509 
510 	memcpy(&data.v1.session_key, session_key, sizeof(data.v1.session_key));
511 
512 	ret = key_instantiate_and_link(key, &data, sizeof(data), NULL, NULL);
513 	if (ret < 0)
514 		goto error;
515 
516 	conn->params.key = key;
517 	_leave(" = 0 [%d]", key_serial(key));
518 	return 0;
519 
520 error:
521 	key_revoke(key);
522 	key_put(key);
523 	_leave(" = -ENOMEM [ins %d]", ret);
524 	return -ENOMEM;
525 }
526 EXPORT_SYMBOL(rxrpc_get_server_data_key);
527 
528 /**
529  * rxrpc_get_null_key - Generate a null RxRPC key
530  * @keyname: The name to give the key.
531  *
532  * Generate a null RxRPC key that can be used to indicate anonymous security is
533  * required for a particular domain.
534  */
535 struct key *rxrpc_get_null_key(const char *keyname)
536 {
537 	const struct cred *cred = current_cred();
538 	struct key *key;
539 	int ret;
540 
541 	key = key_alloc(&key_type_rxrpc, keyname,
542 			GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, cred,
543 			KEY_POS_SEARCH, KEY_ALLOC_NOT_IN_QUOTA, NULL);
544 	if (IS_ERR(key))
545 		return key;
546 
547 	ret = key_instantiate_and_link(key, NULL, 0, NULL, NULL);
548 	if (ret < 0) {
549 		key_revoke(key);
550 		key_put(key);
551 		return ERR_PTR(ret);
552 	}
553 
554 	return key;
555 }
556 EXPORT_SYMBOL(rxrpc_get_null_key);
557 
558 /*
559  * read the contents of an rxrpc key
560  * - this returns the result in XDR form
561  */
562 static long rxrpc_read(const struct key *key,
563 		       char *buffer, size_t buflen)
564 {
565 	const struct rxrpc_key_token *token;
566 	size_t size;
567 	__be32 *xdr, *oldxdr;
568 	u32 cnlen, toksize, ntoks, tok, zero;
569 	u16 toksizes[AFSTOKEN_MAX];
570 
571 	_enter("");
572 
573 	/* we don't know what form we should return non-AFS keys in */
574 	if (memcmp(key->description, "afs@", 4) != 0)
575 		return -EOPNOTSUPP;
576 	cnlen = strlen(key->description + 4);
577 
578 #define RND(X) (((X) + 3) & ~3)
579 
580 	/* AFS keys we return in XDR form, so we need to work out the size of
581 	 * the XDR */
582 	size = 2 * 4;	/* flags, cellname len */
583 	size += RND(cnlen);	/* cellname */
584 	size += 1 * 4;	/* token count */
585 
586 	ntoks = 0;
587 	for (token = key->payload.data[0]; token; token = token->next) {
588 		toksize = 4;	/* sec index */
589 
590 		switch (token->security_index) {
591 		case RXRPC_SECURITY_RXKAD:
592 			toksize += 8 * 4;	/* viceid, kvno, key*2, begin,
593 						 * end, primary, tktlen */
594 			if (!token->no_leak_key)
595 				toksize += RND(token->kad->ticket_len);
596 			break;
597 
598 		default: /* we have a ticket we can't encode */
599 			pr_err("Unsupported key token type (%u)\n",
600 			       token->security_index);
601 			continue;
602 		}
603 
604 		_debug("token[%u]: toksize=%u", ntoks, toksize);
605 		ASSERTCMP(toksize, <=, AFSTOKEN_LENGTH_MAX);
606 
607 		toksizes[ntoks++] = toksize;
608 		size += toksize + 4; /* each token has a length word */
609 	}
610 
611 #undef RND
612 
613 	if (!buffer || buflen < size)
614 		return size;
615 
616 	xdr = (__be32 *)buffer;
617 	zero = 0;
618 #define ENCODE(x)				\
619 	do {					\
620 		*xdr++ = htonl(x);		\
621 	} while(0)
622 #define ENCODE_DATA(l, s)						\
623 	do {								\
624 		u32 _l = (l);						\
625 		ENCODE(l);						\
626 		memcpy(xdr, (s), _l);					\
627 		if (_l & 3)						\
628 			memcpy((u8 *)xdr + _l, &zero, 4 - (_l & 3));	\
629 		xdr += (_l + 3) >> 2;					\
630 	} while(0)
631 #define ENCODE_BYTES(l, s)						\
632 	do {								\
633 		u32 _l = (l);						\
634 		memcpy(xdr, (s), _l);					\
635 		if (_l & 3)						\
636 			memcpy((u8 *)xdr + _l, &zero, 4 - (_l & 3));	\
637 		xdr += (_l + 3) >> 2;					\
638 	} while(0)
639 #define ENCODE64(x)					\
640 	do {						\
641 		__be64 y = cpu_to_be64(x);		\
642 		memcpy(xdr, &y, 8);			\
643 		xdr += 8 >> 2;				\
644 	} while(0)
645 #define ENCODE_STR(s)				\
646 	do {					\
647 		const char *_s = (s);		\
648 		ENCODE_DATA(strlen(_s), _s);	\
649 	} while(0)
650 
651 	ENCODE(0);					/* flags */
652 	ENCODE_DATA(cnlen, key->description + 4);	/* cellname */
653 	ENCODE(ntoks);
654 
655 	tok = 0;
656 	for (token = key->payload.data[0]; token; token = token->next) {
657 		toksize = toksizes[tok++];
658 		ENCODE(toksize);
659 		oldxdr = xdr;
660 		ENCODE(token->security_index);
661 
662 		switch (token->security_index) {
663 		case RXRPC_SECURITY_RXKAD:
664 			ENCODE(token->kad->vice_id);
665 			ENCODE(token->kad->kvno);
666 			ENCODE_BYTES(8, token->kad->session_key);
667 			ENCODE(token->kad->start);
668 			ENCODE(token->kad->expiry);
669 			ENCODE(token->kad->primary_flag);
670 			if (token->no_leak_key)
671 				ENCODE(0);
672 			else
673 				ENCODE_DATA(token->kad->ticket_len, token->kad->ticket);
674 			break;
675 
676 		default:
677 			break;
678 		}
679 
680 		ASSERTCMP((unsigned long)xdr - (unsigned long)oldxdr, ==,
681 			  toksize);
682 	}
683 
684 #undef ENCODE_STR
685 #undef ENCODE_DATA
686 #undef ENCODE64
687 #undef ENCODE
688 
689 	ASSERTCMP(tok, ==, ntoks);
690 	ASSERTCMP((char __user *) xdr - buffer, ==, size);
691 	_leave(" = %zu", size);
692 	return size;
693 }
694