aboutsummaryrefslogtreecommitdiff
path: root/net/sunrpc/auth.c
blob: a9f0d17fdb0d64dce0bd0829ee58b31f024d1a0c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
// SPDX-License-Identifier: GPL-2.0-only
/*
 * linux/net/sunrpc/auth.c
 *
 * Generic RPC client authentication API.
 *
 * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
 */

#include <linux/types.h>
#include <linux/sched.h>
#include <linux/cred.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/hash.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/gss_api.h>
#include <linux/spinlock.h>

#include <trace/events/sunrpc.h>

#define RPC_CREDCACHE_DEFAULT_HASHBITS	(4)
struct rpc_cred_cache {
	struct hlist_head	*hashtable;
	unsigned int		hashbits;
	spinlock_t		lock;
};

static unsigned int auth_hashbits = RPC_CREDCACHE_DEFAULT_HASHBITS;

static const struct rpc_authops __rcu *auth_flavors[RPC_AUTH_MAXFLAVOR] = {
	[RPC_AUTH_NULL] = (const struct rpc_authops __force __rcu *)&authnull_ops,
	[RPC_AUTH_UNIX] = (const struct rpc_authops __force __rcu *)&authunix_ops,
	NULL,			/* others can be loadable modules */
};

static LIST_HEAD(cred_unused);
static unsigned long number_cred_unused;

static struct cred machine_cred = {
	.usage = ATOMIC_INIT(1),
#ifdef CONFIG_DEBUG_CREDENTIALS
	.magic = CRED_MAGIC,
#endif
};

/*
 * Return the machine_cred pointer to be used whenever
 * the a generic machine credential is needed.
 */
const struct cred *rpc_machine_cred(void)
{
	return &machine_cred;
}
EXPORT_SYMBOL_GPL(rpc_machine_cred);

#define MAX_HASHTABLE_BITS (14)
static int param_set_hashtbl_sz(const char *val, const struct kernel_param *kp)
{
	unsigned long num;
	unsigned int nbits;
	int ret;

	if (!val)
		goto out_inval;
	ret = kstrtoul(val, 0, &num);
	if (ret)
		goto out_inval;
	nbits = fls(num - 1);
	if (nbits > MAX_HASHTABLE_BITS || nbits < 2)
		goto out_inval;
	*(unsigned int *)kp->arg = nbits;
	return 0;
out_inval:
	return -EINVAL;
}

static int param_get_hashtbl_sz(char *buffer, const struct kernel_param *kp)
{
	unsigned int nbits;

	nbits = *(unsigned int *)kp->arg;
	return sprintf(buffer, "%u\n", 1U << nbits);
}

#define param_check_hashtbl_sz(name, p) __param_check(name, p, unsigned int);

static const struct kernel_param_ops param_ops_hashtbl_sz = {
	.set = param_set_hashtbl_sz,
	.get = param_get_hashtbl_sz,
};

module_param_named(auth_hashtable_size, auth_hashbits, hashtbl_sz, 0644);
MODULE_PARM_DESC(auth_hashtable_size, "RPC credential cache hashtable size");

static unsigned long auth_max_cred_cachesize = ULONG_MAX;
module_param(auth_max_cred_cachesize, ulong, 0644);
MODULE_PARM_DESC(auth_max_cred_cachesize, "RPC credential maximum total cache size");

static u32
pseudoflavor_to_flavor(u32 flavor) {
	if (flavor > RPC_AUTH_MAXFLAVOR)
		return RPC_AUTH_GSS;
	return flavor;
}

int
rpcauth_register(const struct rpc_authops *ops)
{
	const struct rpc_authops *old;
	rpc_authflavor_t flavor;

	if ((flavor = ops->au_flavor) >= RPC_AUTH_MAXFLAVOR)
		return -EINVAL;
	old = cmpxchg((const struct rpc_authops ** __force)&auth_flavors[flavor], NULL, ops);
	if (old == NULL || old == ops)
		return 0;
	return -EPERM;
}
EXPORT_SYMBOL_GPL(rpcauth_register);

int
rpcauth_unregister(const struct rpc_authops *ops)
{
	const struct rpc_authops *old;
	rpc_authflavor_t flavor;

	if ((flavor = ops->au_flavor) >= RPC_AUTH_MAXFLAVOR)
		return -EINVAL;

	old = cmpxchg((const struct rpc_authops ** __force)&auth_flavors[flavor], ops, NULL);
	if (old == ops || old == NULL)
		return 0;
	return -EPERM;
}
EXPORT_SYMBOL_GPL(rpcauth_unregister);

static const struct rpc_authops *
rpcauth_get_authops(rpc_authflavor_t flavor)
{
	const struct rpc_authops *ops;

	if (flavor >= RPC_AUTH_MAXFLAVOR)
		return NULL;

	rcu_read_lock();
	ops = rcu_dereference(auth_flavors[flavor]);
	if (ops == NULL) {
		rcu_read_unlock();
		request_module("rpc-auth-%u", flavor);
		rcu_read_lock();
		ops = rcu_dereference(auth_flavors[flavor]);
		if (ops == NULL)
			goto out;
	}
	if (!try_module_get(ops->owner))
		ops = NULL;
out:
	rcu_read_unlock();
	return ops;
}

static void
rpcauth_put_authops(const struct rpc_authops *ops)
{
	module_put(ops->owner);
}

/**
 * rpcauth_get_pseudoflavor - check if security flavor is supported
 * @flavor: a security flavor
 * @info: a GSS mech OID, quality of protection, and service value
 *
 * Verifies that an appropriate kernel module is available or already loaded.
 * Returns an equivalent pseudoflavor, or RPC_AUTH_MAXFLAVOR if "flavor" is
 * not supported locally.
 */
rpc_authflavor_t
rpcauth_get_pseudoflavor(rpc_authflavor_t flavor, struct rpcsec_gss_info *info)
{
	const struct rpc_authops *ops = rpcauth_get_authops(flavor);
	rpc_authflavor_t pseudoflavor;

	if (!ops)
		return RPC_AUTH_MAXFLAVOR;
	pseudoflavor = flavor;
	if (ops->info2flavor != NULL)
		pseudoflavor = ops->info2flavor(info);

	rpcauth_put_authops(ops);
	return pseudoflavor;
}
EXPORT_SYMBOL_GPL(rpcauth_get_pseudoflavor);

/**
 * rpcauth_get_gssinfo - find GSS tuple matching a GSS pseudoflavor
 * @pseudoflavor: GSS pseudoflavor to match
 * @info: rpcsec_gss_info structure to fill in
 *
 * Returns zero and fills in "info" if pseudoflavor matches a
 * supported mechanism.
 */
int
rpcauth_get_gssinfo(rpc_authflavor_t pseudoflavor, struct rpcsec_gss_info *info)
{
	rpc_authflavor_t flavor = pseudoflavor_to_flavor(pseudoflavor);
	const struct rpc_authops *ops;
	int result;

	ops = rpcauth_get_authops(flavor);
	if (ops == NULL)
		return -ENOENT;

	result = -ENOENT;
	if (ops->flavor2info != NULL)
		result = ops->flavor2info(pseudoflavor, info);

	rpcauth_put_authops(ops);
	return result;
}
EXPORT_SYMBOL_GPL(rpcauth_get_gssinfo);

struct rpc_auth *
rpcauth_create(const struct rpc_auth_create_args *args, struct rpc_clnt *clnt)
{
	struct rpc_auth	*auth = ERR_PTR(-EINVAL);
	const struct rpc_authops *ops;
	u32 flavor = pseudoflavor_to_flavor(args->pseudoflavor);

	ops = rpcauth_get_authops(flavor);
	if (ops == NULL)
		goto out;

	auth = ops->create(args, clnt);

	rpcauth_put_authops(ops);
	if (IS_ERR(auth))
		return auth;
	if (clnt->cl_auth)
		rpcauth_release(clnt->cl_auth);
	clnt->cl_auth = auth;

out:
	return auth;
}
EXPORT_SYMBOL_GPL(rpcauth_create);

void
rpcauth_release(struct rpc_auth *auth)
{
	if (!refcount_dec_and_test(&auth->au_count))
		return;
	auth->au_ops->destroy(auth);
}

static DEFINE_SPINLOCK(rpc_credcache_lock);

/*
 * On success, the caller is responsible for freeing the reference
 * held by the hashtable
 */
static bool
rpcauth_unhash_cred_locked(struct rpc_cred *cred)
{
	if (!test_and_clear_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags))
		return false;
	hlist_del_rcu(&cred->cr_hash);
	return true;
}

static bool
rpcauth_unhash_cred(struct rpc_cred *cred)
{
	spinlock_t *cache_lock;
	bool ret;

	if (!test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags))
		return false;
	cache_lock = &cred->cr_auth->au_credcache->lock;
	spin_lock(cache_lock);
	ret = rpcauth_unhash_cred_locked(cred);
	spin_unlock(cache_lock);
	return ret;
}

/*
 * Initialize RPC credential cache
 */
int
rpcauth_init_credcache(struct rpc_auth *auth)
{
	struct rpc_cred_cache *new;
	unsigned int hashsize;

	new = kmalloc(sizeof(*new), GFP_KERNEL);
	if (!new)
		goto out_nocache;
	new->hashbits = auth_hashbits;
	hashsize = 1U << new->hashbits;
	new->hashtable = kcalloc(hashsize, sizeof(new->hashtable[0]), GFP_KERNEL);
	if (!new->hashtable)
		goto out_nohashtbl;
	spin_lock_init(&new->lock);
	auth->au_credcache = new;
	return 0;
out_nohashtbl:
	kfree(new);
out_nocache:
	return -ENOMEM;
}
EXPORT_SYMBOL_GPL(rpcauth_init_credcache);

char *
rpcauth_stringify_acceptor(struct rpc_cred *cred)
{
	if (!cred->cr_ops->crstringify_acceptor)
		return NULL;
	return cred->cr_ops->crstringify_acceptor(cred);
}
EXPORT_SYMBOL_GPL(rpcauth_stringify_acceptor);

/*
 * Destroy a list of credentials
 */
static inline
void rpcauth_destroy_credlist(struct list_head *head)
{
	struct rpc_cred *cred;

	while (!list_empty(head)) {
		cred = list_entry(head->next, struct rpc_cred, cr_lru);
		list_del_init(&cred->cr_lru);
		put_rpccred(cred);
	}
}

static void
rpcauth_lru_add_locked(struct rpc_cred *cred)
{
	if (!list_empty(&cred->cr_lru))
		return;
	number_cred_unused++;
	list_add_tail(&cred->cr_lru, &cred_unused);
}

static void
rpcauth_lru_add(struct rpc_cred *cred)
{
	if (!list_empty(&cred->cr_lru))
		return;
	spin_lock(&rpc_credcache_lock);
	rpcauth_lru_add_locked(cred);
	spin_unlock(&rpc_credcache_lock);
}

static void
rpcauth_lru_remove_locked(struct rpc_cred *cred)
{
	if (list_empty(&cred->cr_lru))
		return;
	number_cred_unused--;
	list_del_init(&cred->cr_lru);
}

static void
rpcauth_lru_remove(struct rpc_cred *cred)
{
	if (list_empty(&cred->cr_lru))
		return;
	spin_lock(&rpc_credcache_lock);
	rpcauth_lru_remove_locked(cred);
	spin_unlock(&rpc_credcache_lock);
}

/*
 * Clear the RPC credential cache, and delete those credentials
 * that are not referenced.
 */
void
rpcauth_clear_credcache(struct rpc_cred_cache *cache)
{
	LIST_HEAD(free);
	struct hlist_head *head;
	struct rpc_cred	*cred;
	unsigned int hashsize = 1U << cache->hashbits;
	int		i;

	spin_lock(&rpc_credcache_lock);
	spin_lock(&cache->lock);
	for (i = 0; i < hashsize; i++) {
		head = &cache->hashtable[i];
		while (!hlist_empty(head)) {
			cred = hlist_entry(head->first, struct rpc_cred, cr_hash);
			rpcauth_unhash_cred_locked(cred);
			/* Note: We now hold a reference to cred */
			rpcauth_lru_remove_locked(cred);
			list_add_tail(&cred->cr_lru, &free);
		}
	}
	spin_unlock(&cache->lock);
	spin_unlock(&rpc_credcache_lock);
	rpcauth_destroy_credlist(&free);
}

/*
 * Destroy the RPC credential cache
 */
void
rpcauth_destroy_credcache(struct rpc_auth *auth)
{
	struct rpc_cred_cache *cache = auth->au_credcache;

	if (cache) {
		auth->au_credcache = NULL;
		rpcauth_clear_credcache(cache);
		kfree(cache->hashtable);
		kfree(cache);
	}
}
EXPORT_SYMBOL_GPL(rpcauth_destroy_credcache);


#define RPC_AUTH_EXPIRY_MORATORIUM (60 * HZ)

/*
 * Remove stale credentials. Avoid sleeping inside the loop.
 */
static long
rpcauth_prune_expired(struct list_head *free, int nr_to_scan)
{
	struct rpc_cred *cred, *next;
	unsigned long expired = jiffies - RPC_AUTH_EXPIRY_MORATORIUM;
	long freed = 0;

	list_for_each_entry_safe(cred, next, &cred_unused, cr_lru) {

		if (nr_to_scan-- == 0)
			break;
		if (refcount_read(&cred->cr_count) > 1) {
			rpcauth_lru_remove_locked(cred);
			continue;
		}
		/*
		 * Enforce a 60 second garbage collection moratorium
		 * Note that the cred_unused list must be time-ordered.
		 */
		if (!time_in_range(cred->cr_expire, expired, jiffies))
			continue;
		if (!rpcauth_unhash_cred(cred))
			continue;

		rpcauth_lru_remove_locked(cred);
		freed++;
		list_add_tail(&cred->cr_lru, free);
	}
	return freed ? freed : SHRINK_STOP;
}

static unsigned long
rpcauth_cache_do_shrink(int nr_to_scan)
{
	LIST_HEAD(free);
	unsigned long freed;

	spin_lock(&rpc_credcache_lock);
	freed = rpcauth_prune_expired(&free, nr_to_scan);
	spin_unlock(&rpc_credcache_lock);
	rpcauth_destroy_credlist(&free);

	return freed;
}

/*
 * Run memory cache shrinker.
 */
static unsigned long
rpcauth_cache_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)

{
	if ((sc->gfp_mask & GFP_KERNEL) != GFP_KERNEL)
		return SHRINK_STOP;

	/* nothing left, don't come back */
	if (list_empty(&cred_unused))
		return SHRINK_STOP;

	return rpcauth_cache_do_shrink(sc->nr_to_scan);
}

static unsigned long
rpcauth_cache_shrink_count(struct shrinker *shrink, struct shrink_control *sc)

{
	return number_cred_unused * sysctl_vfs_cache_pressure / 100;
}

static void
rpcauth_cache_enforce_limit(void)
{
	unsigned long diff;
	unsigned int nr_to_scan;

	if (number_cred_unused <= auth_max_cred_cachesize)
		return;
	diff = number_cred_unused - auth_max_cred_cachesize;
	nr_to_scan = 100;
	if (diff < nr_to_scan)
		nr_to_scan = diff;
	rpcauth_cache_do_shrink(nr_to_scan);
}

/*
 * Look up a process' credentials in the authentication cache
 */
struct rpc_cred *
rpcauth_lookup_credcache(struct rpc_auth *auth, struct auth_cred * acred,
		int flags, gfp_t gfp)
{
	LIST_HEAD(free);
	struct rpc_cred_cache *cache = auth->au_credcache;
	struct rpc_cred	*cred = NULL,
			*entry, *new;
	unsigned int nr;

	nr = auth->au_ops->hash_cred(acred, cache->hashbits);

	rcu_read_lock();
	hlist_for_each_entry_rcu(entry, &cache->hashtable[nr], cr_hash) {
		if (!entry->cr_ops->crmatch(acred, entry, flags))
			continue;
		cred = get_rpccred(entry);
		if (cred)
			break;
	}
	rcu_read_unlock();

	if (cred != NULL)
		goto found;

	new = auth->au_ops->crcreate(auth, acred, flags, gfp);
	if (IS_ERR(new)) {
		cred = new;
		goto out;
	}

	spin_lock(&cache->lock);
	hlist_for_each_entry(entry, &cache->hashtable[nr], cr_hash) {
		if (!entry->cr_ops->crmatch(acred, entry, flags))
			continue;
		cred = get_rpccred(entry);
		if (cred)
			break;
	}
	if (cred == NULL) {
		cred = new;
		set_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags);
		refcount_inc(&cred->cr_count);
		hlist_add_head_rcu(&cred->cr_hash, &cache->hashtable[nr]);
	} else
		list_add_tail(&new->cr_lru, &free);
	spin_unlock(&cache->lock);
	rpcauth_cache_enforce_limit();
found:
	if (test_bit(RPCAUTH_CRED_NEW, &cred->cr_flags) &&
	    cred->cr_ops->cr_init != NULL &&
	    !(flags & RPCAUTH_LOOKUP_NEW)) {
		int res = cred->cr_ops->cr_init(auth, cred);
		if (res < 0) {
			put_rpccred(cred);
			cred = ERR_PTR(res);
		}
	}
	rpcauth_destroy_credlist(&free);
out:
	return cred;
}
EXPORT_SYMBOL_GPL(rpcauth_lookup_credcache);

struct rpc_cred *
rpcauth_lookupcred(struct rpc_auth *auth, int flags)
{
	struct auth_cred acred;
	struct rpc_cred *ret;
	const struct cred *cred = current_cred();

	memset(&acred, 0, sizeof(acred));
	acred.cred = cred;
	ret = auth->au_ops->lookup_cred(auth, &acred, flags);
	return ret;
}
EXPORT_SYMBOL_GPL(rpcauth_lookupcred);

void
rpcauth_init_cred(struct rpc_cred *cred, const struct auth_cred *acred,
		  struct rpc_auth *auth, const struct rpc_credops *ops)
{
	INIT_HLIST_NODE(&cred->cr_hash);
	INIT_LIST_HEAD(&cred->cr_lru);
	refcount_set(&cred->cr_count, 1);
	cred->cr_auth = auth;
	cred->cr_flags = 0;
	cred->cr_ops = ops;
	cred->cr_expire = jiffies;
	cred->cr_cred = get_cred(acred->cred);
}
EXPORT_SYMBOL_GPL(rpcauth_init_cred);

static struct rpc_cred *
rpcauth_bind_root_cred(struct rpc_task *task, int lookupflags)
{
	struct rpc_auth *auth = task->tk_client->cl_auth;
	struct auth_cred acred = {
		.cred = get_task_cred(&init_task),
	};
	struct rpc_cred *ret;

	ret = auth->au_ops->lookup_cred(auth, &acred, lookupflags);
	put_cred(acred.cred);
	return ret;
}

static struct rpc_cred *
rpcauth_bind_machine_cred(struct rpc_task *task, int lookupflags)
{
	struct rpc_auth *auth = task->tk_client->cl_auth;
	struct auth_cred acred = {
		.principal = task->tk_client->cl_principal,
		.cred = init_task.cred,
	};

	if (!acred.principal)
		return NULL;
	return auth->au_ops->lookup_cred(auth, &acred, lookupflags);
}

static struct rpc_cred *
rpcauth_bind_new_cred(struct rpc_task *task, int lookupflags)
{
	struct rpc_auth *auth = task->tk_client->cl_auth;

	return rpcauth_lookupcred(auth, lookupflags);
}

static int
rpcauth_bindcred(struct rpc_task *task, const struct cred *cred, int flags)
{
	struct rpc_rqst *req = task->tk_rqstp;
	struct rpc_cred *new = NULL;
	int lookupflags = 0;
	struct rpc_auth *auth = task->tk_client->cl_auth;
	struct auth_cred acred = {
		.cred = cred,
	};

	if (flags & RPC_TASK_ASYNC)
		lookupflags |= RPCAUTH_LOOKUP_NEW;
	if (task->tk_op_cred)
		/* Task must use exactly this rpc_cred */
		new = get_rpccred(task->tk_op_cred);
	else if (cred != NULL && cred != &machine_cred)
		new = auth->au_ops->lookup_cred(auth, &acred, lookupflags);
	else if (cred == &machine_cred)
		new = rpcauth_bind_machine_cred(task, lookupflags);

	/* If machine cred couldn't be bound, try a root cred */
	if (new)
		;
	else if (cred == &machine_cred || (flags & RPC_TASK_ROOTCREDS))
		new = rpcauth_bind_root_cred(task, lookupflags);
	else if (flags & RPC_TASK_NULLCREDS)
		new = authnull_ops.lookup_cred(NULL, NULL, 0);
	else
		new = rpcauth_bind_new_cred(task, lookupflags);
	if (IS_ERR(new))
		return PTR_ERR(new);
	put_rpccred(req->rq_cred);
	req->rq_cred = new;
	return 0;
}

void
put_rpccred(struct rpc_cred *cred)
{
	if (cred == NULL)
		return;
	rcu_read_lock();
	if (refcount_dec_and_test(&cred->cr_count))
		goto destroy;
	if (refcount_read(&cred->cr_count) != 1 ||
	    !test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags))
		goto out;
	if (test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0) {
		cred->cr_expire = jiffies;
		rpcauth_lru_add(cred);
		/* Race breaker */
		if (unlikely(!test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags)))
			rpcauth_lru_remove(cred);
	} else if (rpcauth_unhash_cred(cred)) {
		rpcauth_lru_remove(cred);
		if (refcount_dec_and_test(&cred->cr_count))
			goto destroy;
	}
out:
	rcu_read_unlock();
	return;
destroy:
	rcu_read_unlock();
	cred->cr_ops->crdestroy(cred);
}
EXPORT_SYMBOL_GPL(put_rpccred);

/**
 * rpcauth_marshcred - Append RPC credential to end of @xdr
 * @task: controlling RPC task
 * @xdr: xdr_stream containing initial portion of RPC Call header
 *
 * On success, an appropriate verifier is added to @xdr, @xdr is
 * updated to point past the verifier, and zero is returned.
 * Otherwise, @xdr is in an undefined state and a negative errno
 * is returned.
 */
int rpcauth_marshcred(struct rpc_task *task, struct xdr_stream *xdr)
{
	const struct rpc_credops *ops = task->tk_rqstp->rq_cred->cr_ops;

	return ops->crmarshal(task, xdr);
}

/**
 * rpcauth_wrap_req_encode - XDR encode the RPC procedure
 * @task: controlling RPC task
 * @xdr: stream where on-the-wire bytes are to be marshalled
 *
 * On success, @xdr contains the encoded and wrapped message.
 * Otherwise, @xdr is in an undefined state.
 */
int rpcauth_wrap_req_encode(struct rpc_task *task, struct xdr_stream *xdr)
{
	kxdreproc_t encode = task->tk_msg.rpc_proc->p_encode;

	encode(task->tk_rqstp, xdr, task->tk_msg.rpc_argp);
	return 0;
}
EXPORT_SYMBOL_GPL(rpcauth_wrap_req_encode);

/**
 * rpcauth_wrap_req - XDR encode and wrap the RPC procedure
 * @task: controlling RPC task
 * @xdr: stream where on-the-wire bytes are to be marshalled
 *
 * On success, @xdr contains the encoded and wrapped message,
 * and zero is returned. Otherwise, @xdr is in an undefined
 * state and a negative errno is returned.
 */
int rpcauth_wrap_req(struct rpc_task *task, struct xdr_stream *xdr)
{
	const struct rpc_credops *ops = task->tk_rqstp->rq_cred->cr_ops;

	return ops->crwrap_req(task, xdr);
}

/**
 * rpcauth_checkverf - Validate verifier in RPC Reply header
 * @task: controlling RPC task
 * @xdr: xdr_stream containing RPC Reply header
 *
 * On success, @xdr is updated to point past the verifier and
 * zero is returned. Otherwise, @xdr is in an undefined state
 * and a negative errno is returned.
 */
int
rpcauth_checkverf(struct rpc_task *task, struct xdr_stream *xdr)
{
	const struct rpc_credops *ops = task->tk_rqstp->rq_cred->cr_ops;

	return ops->crvalidate(task, xdr);
}

/**
 * rpcauth_unwrap_resp_decode - Invoke XDR decode function
 * @task: controlling RPC task
 * @xdr: stream where the Reply message resides
 *
 * Returns zero on success; otherwise a negative errno is returned.
 */
int
rpcauth_unwrap_resp_decode(struct rpc_task *task, struct xdr_stream *xdr)
{
	kxdrdproc_t decode = task->tk_msg.rpc_proc->p_decode;

	return decode(task->tk_rqstp, xdr, task->tk_msg.rpc_resp);
}
EXPORT_SYMBOL_GPL(rpcauth_unwrap_resp_decode);

/**
 * rpcauth_unwrap_resp - Invoke unwrap and decode function for the cred
 * @task: controlling RPC task
 * @xdr: stream where the Reply message resides
 *
 * Returns zero on success; otherwise a negative errno is returned.
 */
int
rpcauth_unwrap_resp(struct rpc_task *task, struct xdr_stream *xdr)
{
	const struct rpc_credops *ops = task->tk_rqstp->rq_cred->cr_ops;

	return ops->crunwrap_resp(task, xdr);
}

bool
rpcauth_xmit_need_reencode(struct rpc_task *task)
{
	struct rpc_cred *cred = task->tk_rqstp->rq_cred;

	if (!cred || !cred->cr_ops->crneed_reencode)
		return false;
	return cred->cr_ops->crneed_reencode(task);
}

int
rpcauth_refreshcred(struct rpc_task *task)
{
	struct rpc_cred	*cred;
	int err;

	cred = task->tk_rqstp->rq_cred;
	if (cred == NULL) {
		err = rpcauth_bindcred(task, task->tk_msg.rpc_cred, task->tk_flags);
		if (err < 0)
			goto out;
		cred = task->tk_rqstp->rq_cred;
	}

	err = cred->cr_ops->crrefresh(task);
out:
	if (err < 0)
		task->tk_status = err;
	return err;
}

void
rpcauth_invalcred(struct rpc_task *task)
{
	struct rpc_cred *cred = task->tk_rqstp->rq_cred;

	if (cred)
		clear_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
}

int
rpcauth_uptodatecred(struct rpc_task *task)
{
	struct rpc_cred *cred = task->tk_rqstp->rq_cred;

	return cred == NULL ||
		test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0;
}

static struct shrinker rpc_cred_shrinker = {
	.count_objects = rpcauth_cache_shrink_count,
	.scan_objects = rpcauth_cache_shrink_scan,
	.seeks = DEFAULT_SEEKS,
};

int __init rpcauth_init_module(void)
{
	int err;

	err = rpc_init_authunix();
	if (err < 0)
		goto out1;
	err = register_shrinker(&rpc_cred_shrinker);
	if (err < 0)
		goto out2;
	return 0;
out2:
	rpc_destroy_authunix();
out1:
	return err;
}

void rpcauth_remove_module(void)
{
	rpc_destroy_authunix();
	unregister_shrinker(&rpc_cred_shrinker);
}