xref: /openbmc/linux/net/sunrpc/auth.c (revision 9726bfcd)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * linux/net/sunrpc/auth.c
4  *
5  * Generic RPC client authentication API.
6  *
7  * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
8  */
9 
10 #include <linux/types.h>
11 #include <linux/sched.h>
12 #include <linux/cred.h>
13 #include <linux/module.h>
14 #include <linux/slab.h>
15 #include <linux/errno.h>
16 #include <linux/hash.h>
17 #include <linux/sunrpc/clnt.h>
18 #include <linux/sunrpc/gss_api.h>
19 #include <linux/spinlock.h>
20 
21 #include <trace/events/sunrpc.h>
22 
23 #define RPC_CREDCACHE_DEFAULT_HASHBITS	(4)
24 struct rpc_cred_cache {
25 	struct hlist_head	*hashtable;
26 	unsigned int		hashbits;
27 	spinlock_t		lock;
28 };
29 
30 static unsigned int auth_hashbits = RPC_CREDCACHE_DEFAULT_HASHBITS;
31 
32 static const struct rpc_authops __rcu *auth_flavors[RPC_AUTH_MAXFLAVOR] = {
33 	[RPC_AUTH_NULL] = (const struct rpc_authops __force __rcu *)&authnull_ops,
34 	[RPC_AUTH_UNIX] = (const struct rpc_authops __force __rcu *)&authunix_ops,
35 	NULL,			/* others can be loadable modules */
36 };
37 
38 static LIST_HEAD(cred_unused);
39 static unsigned long number_cred_unused;
40 
41 static struct cred machine_cred = {
42 	.usage = ATOMIC_INIT(1),
43 #ifdef CONFIG_DEBUG_CREDENTIALS
44 	.magic = CRED_MAGIC,
45 #endif
46 };
47 
48 /*
49  * Return the machine_cred pointer to be used whenever
50  * the a generic machine credential is needed.
51  */
52 const struct cred *rpc_machine_cred(void)
53 {
54 	return &machine_cred;
55 }
56 EXPORT_SYMBOL_GPL(rpc_machine_cred);
57 
58 #define MAX_HASHTABLE_BITS (14)
59 static int param_set_hashtbl_sz(const char *val, const struct kernel_param *kp)
60 {
61 	unsigned long num;
62 	unsigned int nbits;
63 	int ret;
64 
65 	if (!val)
66 		goto out_inval;
67 	ret = kstrtoul(val, 0, &num);
68 	if (ret)
69 		goto out_inval;
70 	nbits = fls(num - 1);
71 	if (nbits > MAX_HASHTABLE_BITS || nbits < 2)
72 		goto out_inval;
73 	*(unsigned int *)kp->arg = nbits;
74 	return 0;
75 out_inval:
76 	return -EINVAL;
77 }
78 
79 static int param_get_hashtbl_sz(char *buffer, const struct kernel_param *kp)
80 {
81 	unsigned int nbits;
82 
83 	nbits = *(unsigned int *)kp->arg;
84 	return sprintf(buffer, "%u", 1U << nbits);
85 }
86 
87 #define param_check_hashtbl_sz(name, p) __param_check(name, p, unsigned int);
88 
89 static const struct kernel_param_ops param_ops_hashtbl_sz = {
90 	.set = param_set_hashtbl_sz,
91 	.get = param_get_hashtbl_sz,
92 };
93 
94 module_param_named(auth_hashtable_size, auth_hashbits, hashtbl_sz, 0644);
95 MODULE_PARM_DESC(auth_hashtable_size, "RPC credential cache hashtable size");
96 
97 static unsigned long auth_max_cred_cachesize = ULONG_MAX;
98 module_param(auth_max_cred_cachesize, ulong, 0644);
99 MODULE_PARM_DESC(auth_max_cred_cachesize, "RPC credential maximum total cache size");
100 
101 static u32
102 pseudoflavor_to_flavor(u32 flavor) {
103 	if (flavor > RPC_AUTH_MAXFLAVOR)
104 		return RPC_AUTH_GSS;
105 	return flavor;
106 }
107 
108 int
109 rpcauth_register(const struct rpc_authops *ops)
110 {
111 	const struct rpc_authops *old;
112 	rpc_authflavor_t flavor;
113 
114 	if ((flavor = ops->au_flavor) >= RPC_AUTH_MAXFLAVOR)
115 		return -EINVAL;
116 	old = cmpxchg((const struct rpc_authops ** __force)&auth_flavors[flavor], NULL, ops);
117 	if (old == NULL || old == ops)
118 		return 0;
119 	return -EPERM;
120 }
121 EXPORT_SYMBOL_GPL(rpcauth_register);
122 
123 int
124 rpcauth_unregister(const struct rpc_authops *ops)
125 {
126 	const struct rpc_authops *old;
127 	rpc_authflavor_t flavor;
128 
129 	if ((flavor = ops->au_flavor) >= RPC_AUTH_MAXFLAVOR)
130 		return -EINVAL;
131 
132 	old = cmpxchg((const struct rpc_authops ** __force)&auth_flavors[flavor], ops, NULL);
133 	if (old == ops || old == NULL)
134 		return 0;
135 	return -EPERM;
136 }
137 EXPORT_SYMBOL_GPL(rpcauth_unregister);
138 
139 static const struct rpc_authops *
140 rpcauth_get_authops(rpc_authflavor_t flavor)
141 {
142 	const struct rpc_authops *ops;
143 
144 	if (flavor >= RPC_AUTH_MAXFLAVOR)
145 		return NULL;
146 
147 	rcu_read_lock();
148 	ops = rcu_dereference(auth_flavors[flavor]);
149 	if (ops == NULL) {
150 		rcu_read_unlock();
151 		request_module("rpc-auth-%u", flavor);
152 		rcu_read_lock();
153 		ops = rcu_dereference(auth_flavors[flavor]);
154 		if (ops == NULL)
155 			goto out;
156 	}
157 	if (!try_module_get(ops->owner))
158 		ops = NULL;
159 out:
160 	rcu_read_unlock();
161 	return ops;
162 }
163 
164 static void
165 rpcauth_put_authops(const struct rpc_authops *ops)
166 {
167 	module_put(ops->owner);
168 }
169 
170 /**
171  * rpcauth_get_pseudoflavor - check if security flavor is supported
172  * @flavor: a security flavor
173  * @info: a GSS mech OID, quality of protection, and service value
174  *
175  * Verifies that an appropriate kernel module is available or already loaded.
176  * Returns an equivalent pseudoflavor, or RPC_AUTH_MAXFLAVOR if "flavor" is
177  * not supported locally.
178  */
179 rpc_authflavor_t
180 rpcauth_get_pseudoflavor(rpc_authflavor_t flavor, struct rpcsec_gss_info *info)
181 {
182 	const struct rpc_authops *ops = rpcauth_get_authops(flavor);
183 	rpc_authflavor_t pseudoflavor;
184 
185 	if (!ops)
186 		return RPC_AUTH_MAXFLAVOR;
187 	pseudoflavor = flavor;
188 	if (ops->info2flavor != NULL)
189 		pseudoflavor = ops->info2flavor(info);
190 
191 	rpcauth_put_authops(ops);
192 	return pseudoflavor;
193 }
194 EXPORT_SYMBOL_GPL(rpcauth_get_pseudoflavor);
195 
196 /**
197  * rpcauth_get_gssinfo - find GSS tuple matching a GSS pseudoflavor
198  * @pseudoflavor: GSS pseudoflavor to match
199  * @info: rpcsec_gss_info structure to fill in
200  *
201  * Returns zero and fills in "info" if pseudoflavor matches a
202  * supported mechanism.
203  */
204 int
205 rpcauth_get_gssinfo(rpc_authflavor_t pseudoflavor, struct rpcsec_gss_info *info)
206 {
207 	rpc_authflavor_t flavor = pseudoflavor_to_flavor(pseudoflavor);
208 	const struct rpc_authops *ops;
209 	int result;
210 
211 	ops = rpcauth_get_authops(flavor);
212 	if (ops == NULL)
213 		return -ENOENT;
214 
215 	result = -ENOENT;
216 	if (ops->flavor2info != NULL)
217 		result = ops->flavor2info(pseudoflavor, info);
218 
219 	rpcauth_put_authops(ops);
220 	return result;
221 }
222 EXPORT_SYMBOL_GPL(rpcauth_get_gssinfo);
223 
224 /**
225  * rpcauth_list_flavors - discover registered flavors and pseudoflavors
226  * @array: array to fill in
227  * @size: size of "array"
228  *
229  * Returns the number of array items filled in, or a negative errno.
230  *
231  * The returned array is not sorted by any policy.  Callers should not
232  * rely on the order of the items in the returned array.
233  */
234 int
235 rpcauth_list_flavors(rpc_authflavor_t *array, int size)
236 {
237 	const struct rpc_authops *ops;
238 	rpc_authflavor_t flavor, pseudos[4];
239 	int i, len, result = 0;
240 
241 	rcu_read_lock();
242 	for (flavor = 0; flavor < RPC_AUTH_MAXFLAVOR; flavor++) {
243 		ops = rcu_dereference(auth_flavors[flavor]);
244 		if (result >= size) {
245 			result = -ENOMEM;
246 			break;
247 		}
248 
249 		if (ops == NULL)
250 			continue;
251 		if (ops->list_pseudoflavors == NULL) {
252 			array[result++] = ops->au_flavor;
253 			continue;
254 		}
255 		len = ops->list_pseudoflavors(pseudos, ARRAY_SIZE(pseudos));
256 		if (len < 0) {
257 			result = len;
258 			break;
259 		}
260 		for (i = 0; i < len; i++) {
261 			if (result >= size) {
262 				result = -ENOMEM;
263 				break;
264 			}
265 			array[result++] = pseudos[i];
266 		}
267 	}
268 	rcu_read_unlock();
269 	return result;
270 }
271 EXPORT_SYMBOL_GPL(rpcauth_list_flavors);
272 
273 struct rpc_auth *
274 rpcauth_create(const struct rpc_auth_create_args *args, struct rpc_clnt *clnt)
275 {
276 	struct rpc_auth	*auth = ERR_PTR(-EINVAL);
277 	const struct rpc_authops *ops;
278 	u32 flavor = pseudoflavor_to_flavor(args->pseudoflavor);
279 
280 	ops = rpcauth_get_authops(flavor);
281 	if (ops == NULL)
282 		goto out;
283 
284 	auth = ops->create(args, clnt);
285 
286 	rpcauth_put_authops(ops);
287 	if (IS_ERR(auth))
288 		return auth;
289 	if (clnt->cl_auth)
290 		rpcauth_release(clnt->cl_auth);
291 	clnt->cl_auth = auth;
292 
293 out:
294 	return auth;
295 }
296 EXPORT_SYMBOL_GPL(rpcauth_create);
297 
298 void
299 rpcauth_release(struct rpc_auth *auth)
300 {
301 	if (!refcount_dec_and_test(&auth->au_count))
302 		return;
303 	auth->au_ops->destroy(auth);
304 }
305 
306 static DEFINE_SPINLOCK(rpc_credcache_lock);
307 
308 /*
309  * On success, the caller is responsible for freeing the reference
310  * held by the hashtable
311  */
312 static bool
313 rpcauth_unhash_cred_locked(struct rpc_cred *cred)
314 {
315 	if (!test_and_clear_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags))
316 		return false;
317 	hlist_del_rcu(&cred->cr_hash);
318 	return true;
319 }
320 
321 static bool
322 rpcauth_unhash_cred(struct rpc_cred *cred)
323 {
324 	spinlock_t *cache_lock;
325 	bool ret;
326 
327 	if (!test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags))
328 		return false;
329 	cache_lock = &cred->cr_auth->au_credcache->lock;
330 	spin_lock(cache_lock);
331 	ret = rpcauth_unhash_cred_locked(cred);
332 	spin_unlock(cache_lock);
333 	return ret;
334 }
335 
336 /*
337  * Initialize RPC credential cache
338  */
339 int
340 rpcauth_init_credcache(struct rpc_auth *auth)
341 {
342 	struct rpc_cred_cache *new;
343 	unsigned int hashsize;
344 
345 	new = kmalloc(sizeof(*new), GFP_KERNEL);
346 	if (!new)
347 		goto out_nocache;
348 	new->hashbits = auth_hashbits;
349 	hashsize = 1U << new->hashbits;
350 	new->hashtable = kcalloc(hashsize, sizeof(new->hashtable[0]), GFP_KERNEL);
351 	if (!new->hashtable)
352 		goto out_nohashtbl;
353 	spin_lock_init(&new->lock);
354 	auth->au_credcache = new;
355 	return 0;
356 out_nohashtbl:
357 	kfree(new);
358 out_nocache:
359 	return -ENOMEM;
360 }
361 EXPORT_SYMBOL_GPL(rpcauth_init_credcache);
362 
363 char *
364 rpcauth_stringify_acceptor(struct rpc_cred *cred)
365 {
366 	if (!cred->cr_ops->crstringify_acceptor)
367 		return NULL;
368 	return cred->cr_ops->crstringify_acceptor(cred);
369 }
370 EXPORT_SYMBOL_GPL(rpcauth_stringify_acceptor);
371 
372 /*
373  * Destroy a list of credentials
374  */
375 static inline
376 void rpcauth_destroy_credlist(struct list_head *head)
377 {
378 	struct rpc_cred *cred;
379 
380 	while (!list_empty(head)) {
381 		cred = list_entry(head->next, struct rpc_cred, cr_lru);
382 		list_del_init(&cred->cr_lru);
383 		put_rpccred(cred);
384 	}
385 }
386 
387 static void
388 rpcauth_lru_add_locked(struct rpc_cred *cred)
389 {
390 	if (!list_empty(&cred->cr_lru))
391 		return;
392 	number_cred_unused++;
393 	list_add_tail(&cred->cr_lru, &cred_unused);
394 }
395 
396 static void
397 rpcauth_lru_add(struct rpc_cred *cred)
398 {
399 	if (!list_empty(&cred->cr_lru))
400 		return;
401 	spin_lock(&rpc_credcache_lock);
402 	rpcauth_lru_add_locked(cred);
403 	spin_unlock(&rpc_credcache_lock);
404 }
405 
406 static void
407 rpcauth_lru_remove_locked(struct rpc_cred *cred)
408 {
409 	if (list_empty(&cred->cr_lru))
410 		return;
411 	number_cred_unused--;
412 	list_del_init(&cred->cr_lru);
413 }
414 
415 static void
416 rpcauth_lru_remove(struct rpc_cred *cred)
417 {
418 	if (list_empty(&cred->cr_lru))
419 		return;
420 	spin_lock(&rpc_credcache_lock);
421 	rpcauth_lru_remove_locked(cred);
422 	spin_unlock(&rpc_credcache_lock);
423 }
424 
425 /*
426  * Clear the RPC credential cache, and delete those credentials
427  * that are not referenced.
428  */
429 void
430 rpcauth_clear_credcache(struct rpc_cred_cache *cache)
431 {
432 	LIST_HEAD(free);
433 	struct hlist_head *head;
434 	struct rpc_cred	*cred;
435 	unsigned int hashsize = 1U << cache->hashbits;
436 	int		i;
437 
438 	spin_lock(&rpc_credcache_lock);
439 	spin_lock(&cache->lock);
440 	for (i = 0; i < hashsize; i++) {
441 		head = &cache->hashtable[i];
442 		while (!hlist_empty(head)) {
443 			cred = hlist_entry(head->first, struct rpc_cred, cr_hash);
444 			rpcauth_unhash_cred_locked(cred);
445 			/* Note: We now hold a reference to cred */
446 			rpcauth_lru_remove_locked(cred);
447 			list_add_tail(&cred->cr_lru, &free);
448 		}
449 	}
450 	spin_unlock(&cache->lock);
451 	spin_unlock(&rpc_credcache_lock);
452 	rpcauth_destroy_credlist(&free);
453 }
454 
455 /*
456  * Destroy the RPC credential cache
457  */
458 void
459 rpcauth_destroy_credcache(struct rpc_auth *auth)
460 {
461 	struct rpc_cred_cache *cache = auth->au_credcache;
462 
463 	if (cache) {
464 		auth->au_credcache = NULL;
465 		rpcauth_clear_credcache(cache);
466 		kfree(cache->hashtable);
467 		kfree(cache);
468 	}
469 }
470 EXPORT_SYMBOL_GPL(rpcauth_destroy_credcache);
471 
472 
473 #define RPC_AUTH_EXPIRY_MORATORIUM (60 * HZ)
474 
475 /*
476  * Remove stale credentials. Avoid sleeping inside the loop.
477  */
478 static long
479 rpcauth_prune_expired(struct list_head *free, int nr_to_scan)
480 {
481 	struct rpc_cred *cred, *next;
482 	unsigned long expired = jiffies - RPC_AUTH_EXPIRY_MORATORIUM;
483 	long freed = 0;
484 
485 	list_for_each_entry_safe(cred, next, &cred_unused, cr_lru) {
486 
487 		if (nr_to_scan-- == 0)
488 			break;
489 		if (refcount_read(&cred->cr_count) > 1) {
490 			rpcauth_lru_remove_locked(cred);
491 			continue;
492 		}
493 		/*
494 		 * Enforce a 60 second garbage collection moratorium
495 		 * Note that the cred_unused list must be time-ordered.
496 		 */
497 		if (!time_in_range(cred->cr_expire, expired, jiffies))
498 			continue;
499 		if (!rpcauth_unhash_cred(cred))
500 			continue;
501 
502 		rpcauth_lru_remove_locked(cred);
503 		freed++;
504 		list_add_tail(&cred->cr_lru, free);
505 	}
506 	return freed ? freed : SHRINK_STOP;
507 }
508 
509 static unsigned long
510 rpcauth_cache_do_shrink(int nr_to_scan)
511 {
512 	LIST_HEAD(free);
513 	unsigned long freed;
514 
515 	spin_lock(&rpc_credcache_lock);
516 	freed = rpcauth_prune_expired(&free, nr_to_scan);
517 	spin_unlock(&rpc_credcache_lock);
518 	rpcauth_destroy_credlist(&free);
519 
520 	return freed;
521 }
522 
523 /*
524  * Run memory cache shrinker.
525  */
526 static unsigned long
527 rpcauth_cache_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
528 
529 {
530 	if ((sc->gfp_mask & GFP_KERNEL) != GFP_KERNEL)
531 		return SHRINK_STOP;
532 
533 	/* nothing left, don't come back */
534 	if (list_empty(&cred_unused))
535 		return SHRINK_STOP;
536 
537 	return rpcauth_cache_do_shrink(sc->nr_to_scan);
538 }
539 
540 static unsigned long
541 rpcauth_cache_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
542 
543 {
544 	return number_cred_unused * sysctl_vfs_cache_pressure / 100;
545 }
546 
547 static void
548 rpcauth_cache_enforce_limit(void)
549 {
550 	unsigned long diff;
551 	unsigned int nr_to_scan;
552 
553 	if (number_cred_unused <= auth_max_cred_cachesize)
554 		return;
555 	diff = number_cred_unused - auth_max_cred_cachesize;
556 	nr_to_scan = 100;
557 	if (diff < nr_to_scan)
558 		nr_to_scan = diff;
559 	rpcauth_cache_do_shrink(nr_to_scan);
560 }
561 
562 /*
563  * Look up a process' credentials in the authentication cache
564  */
565 struct rpc_cred *
566 rpcauth_lookup_credcache(struct rpc_auth *auth, struct auth_cred * acred,
567 		int flags, gfp_t gfp)
568 {
569 	LIST_HEAD(free);
570 	struct rpc_cred_cache *cache = auth->au_credcache;
571 	struct rpc_cred	*cred = NULL,
572 			*entry, *new;
573 	unsigned int nr;
574 
575 	nr = auth->au_ops->hash_cred(acred, cache->hashbits);
576 
577 	rcu_read_lock();
578 	hlist_for_each_entry_rcu(entry, &cache->hashtable[nr], cr_hash) {
579 		if (!entry->cr_ops->crmatch(acred, entry, flags))
580 			continue;
581 		cred = get_rpccred(entry);
582 		if (cred)
583 			break;
584 	}
585 	rcu_read_unlock();
586 
587 	if (cred != NULL)
588 		goto found;
589 
590 	new = auth->au_ops->crcreate(auth, acred, flags, gfp);
591 	if (IS_ERR(new)) {
592 		cred = new;
593 		goto out;
594 	}
595 
596 	spin_lock(&cache->lock);
597 	hlist_for_each_entry(entry, &cache->hashtable[nr], cr_hash) {
598 		if (!entry->cr_ops->crmatch(acred, entry, flags))
599 			continue;
600 		cred = get_rpccred(entry);
601 		if (cred)
602 			break;
603 	}
604 	if (cred == NULL) {
605 		cred = new;
606 		set_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags);
607 		refcount_inc(&cred->cr_count);
608 		hlist_add_head_rcu(&cred->cr_hash, &cache->hashtable[nr]);
609 	} else
610 		list_add_tail(&new->cr_lru, &free);
611 	spin_unlock(&cache->lock);
612 	rpcauth_cache_enforce_limit();
613 found:
614 	if (test_bit(RPCAUTH_CRED_NEW, &cred->cr_flags) &&
615 	    cred->cr_ops->cr_init != NULL &&
616 	    !(flags & RPCAUTH_LOOKUP_NEW)) {
617 		int res = cred->cr_ops->cr_init(auth, cred);
618 		if (res < 0) {
619 			put_rpccred(cred);
620 			cred = ERR_PTR(res);
621 		}
622 	}
623 	rpcauth_destroy_credlist(&free);
624 out:
625 	return cred;
626 }
627 EXPORT_SYMBOL_GPL(rpcauth_lookup_credcache);
628 
629 struct rpc_cred *
630 rpcauth_lookupcred(struct rpc_auth *auth, int flags)
631 {
632 	struct auth_cred acred;
633 	struct rpc_cred *ret;
634 	const struct cred *cred = current_cred();
635 
636 	memset(&acred, 0, sizeof(acred));
637 	acred.cred = cred;
638 	ret = auth->au_ops->lookup_cred(auth, &acred, flags);
639 	return ret;
640 }
641 EXPORT_SYMBOL_GPL(rpcauth_lookupcred);
642 
643 void
644 rpcauth_init_cred(struct rpc_cred *cred, const struct auth_cred *acred,
645 		  struct rpc_auth *auth, const struct rpc_credops *ops)
646 {
647 	INIT_HLIST_NODE(&cred->cr_hash);
648 	INIT_LIST_HEAD(&cred->cr_lru);
649 	refcount_set(&cred->cr_count, 1);
650 	cred->cr_auth = auth;
651 	cred->cr_flags = 0;
652 	cred->cr_ops = ops;
653 	cred->cr_expire = jiffies;
654 	cred->cr_cred = get_cred(acred->cred);
655 }
656 EXPORT_SYMBOL_GPL(rpcauth_init_cred);
657 
658 static struct rpc_cred *
659 rpcauth_bind_root_cred(struct rpc_task *task, int lookupflags)
660 {
661 	struct rpc_auth *auth = task->tk_client->cl_auth;
662 	struct auth_cred acred = {
663 		.cred = get_task_cred(&init_task),
664 	};
665 	struct rpc_cred *ret;
666 
667 	ret = auth->au_ops->lookup_cred(auth, &acred, lookupflags);
668 	put_cred(acred.cred);
669 	return ret;
670 }
671 
672 static struct rpc_cred *
673 rpcauth_bind_machine_cred(struct rpc_task *task, int lookupflags)
674 {
675 	struct rpc_auth *auth = task->tk_client->cl_auth;
676 	struct auth_cred acred = {
677 		.principal = task->tk_client->cl_principal,
678 		.cred = init_task.cred,
679 	};
680 
681 	if (!acred.principal)
682 		return NULL;
683 	return auth->au_ops->lookup_cred(auth, &acred, lookupflags);
684 }
685 
686 static struct rpc_cred *
687 rpcauth_bind_new_cred(struct rpc_task *task, int lookupflags)
688 {
689 	struct rpc_auth *auth = task->tk_client->cl_auth;
690 
691 	return rpcauth_lookupcred(auth, lookupflags);
692 }
693 
694 static int
695 rpcauth_bindcred(struct rpc_task *task, const struct cred *cred, int flags)
696 {
697 	struct rpc_rqst *req = task->tk_rqstp;
698 	struct rpc_cred *new = NULL;
699 	int lookupflags = 0;
700 	struct rpc_auth *auth = task->tk_client->cl_auth;
701 	struct auth_cred acred = {
702 		.cred = cred,
703 	};
704 
705 	if (flags & RPC_TASK_ASYNC)
706 		lookupflags |= RPCAUTH_LOOKUP_NEW;
707 	if (task->tk_op_cred)
708 		/* Task must use exactly this rpc_cred */
709 		new = get_rpccred(task->tk_op_cred);
710 	else if (cred != NULL && cred != &machine_cred)
711 		new = auth->au_ops->lookup_cred(auth, &acred, lookupflags);
712 	else if (cred == &machine_cred)
713 		new = rpcauth_bind_machine_cred(task, lookupflags);
714 
715 	/* If machine cred couldn't be bound, try a root cred */
716 	if (new)
717 		;
718 	else if (cred == &machine_cred || (flags & RPC_TASK_ROOTCREDS))
719 		new = rpcauth_bind_root_cred(task, lookupflags);
720 	else if (flags & RPC_TASK_NULLCREDS)
721 		new = authnull_ops.lookup_cred(NULL, NULL, 0);
722 	else
723 		new = rpcauth_bind_new_cred(task, lookupflags);
724 	if (IS_ERR(new))
725 		return PTR_ERR(new);
726 	put_rpccred(req->rq_cred);
727 	req->rq_cred = new;
728 	return 0;
729 }
730 
731 void
732 put_rpccred(struct rpc_cred *cred)
733 {
734 	if (cred == NULL)
735 		return;
736 	rcu_read_lock();
737 	if (refcount_dec_and_test(&cred->cr_count))
738 		goto destroy;
739 	if (refcount_read(&cred->cr_count) != 1 ||
740 	    !test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags))
741 		goto out;
742 	if (test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0) {
743 		cred->cr_expire = jiffies;
744 		rpcauth_lru_add(cred);
745 		/* Race breaker */
746 		if (unlikely(!test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags)))
747 			rpcauth_lru_remove(cred);
748 	} else if (rpcauth_unhash_cred(cred)) {
749 		rpcauth_lru_remove(cred);
750 		if (refcount_dec_and_test(&cred->cr_count))
751 			goto destroy;
752 	}
753 out:
754 	rcu_read_unlock();
755 	return;
756 destroy:
757 	rcu_read_unlock();
758 	cred->cr_ops->crdestroy(cred);
759 }
760 EXPORT_SYMBOL_GPL(put_rpccred);
761 
762 /**
763  * rpcauth_marshcred - Append RPC credential to end of @xdr
764  * @task: controlling RPC task
765  * @xdr: xdr_stream containing initial portion of RPC Call header
766  *
767  * On success, an appropriate verifier is added to @xdr, @xdr is
768  * updated to point past the verifier, and zero is returned.
769  * Otherwise, @xdr is in an undefined state and a negative errno
770  * is returned.
771  */
772 int rpcauth_marshcred(struct rpc_task *task, struct xdr_stream *xdr)
773 {
774 	const struct rpc_credops *ops = task->tk_rqstp->rq_cred->cr_ops;
775 
776 	return ops->crmarshal(task, xdr);
777 }
778 
779 /**
780  * rpcauth_wrap_req_encode - XDR encode the RPC procedure
781  * @task: controlling RPC task
782  * @xdr: stream where on-the-wire bytes are to be marshalled
783  *
784  * On success, @xdr contains the encoded and wrapped message.
785  * Otherwise, @xdr is in an undefined state.
786  */
787 int rpcauth_wrap_req_encode(struct rpc_task *task, struct xdr_stream *xdr)
788 {
789 	kxdreproc_t encode = task->tk_msg.rpc_proc->p_encode;
790 
791 	encode(task->tk_rqstp, xdr, task->tk_msg.rpc_argp);
792 	return 0;
793 }
794 EXPORT_SYMBOL_GPL(rpcauth_wrap_req_encode);
795 
796 /**
797  * rpcauth_wrap_req - XDR encode and wrap the RPC procedure
798  * @task: controlling RPC task
799  * @xdr: stream where on-the-wire bytes are to be marshalled
800  *
801  * On success, @xdr contains the encoded and wrapped message,
802  * and zero is returned. Otherwise, @xdr is in an undefined
803  * state and a negative errno is returned.
804  */
805 int rpcauth_wrap_req(struct rpc_task *task, struct xdr_stream *xdr)
806 {
807 	const struct rpc_credops *ops = task->tk_rqstp->rq_cred->cr_ops;
808 
809 	return ops->crwrap_req(task, xdr);
810 }
811 
812 /**
813  * rpcauth_checkverf - Validate verifier in RPC Reply header
814  * @task: controlling RPC task
815  * @xdr: xdr_stream containing RPC Reply header
816  *
817  * On success, @xdr is updated to point past the verifier and
818  * zero is returned. Otherwise, @xdr is in an undefined state
819  * and a negative errno is returned.
820  */
821 int
822 rpcauth_checkverf(struct rpc_task *task, struct xdr_stream *xdr)
823 {
824 	const struct rpc_credops *ops = task->tk_rqstp->rq_cred->cr_ops;
825 
826 	return ops->crvalidate(task, xdr);
827 }
828 
829 /**
830  * rpcauth_unwrap_resp_decode - Invoke XDR decode function
831  * @task: controlling RPC task
832  * @xdr: stream where the Reply message resides
833  *
834  * Returns zero on success; otherwise a negative errno is returned.
835  */
836 int
837 rpcauth_unwrap_resp_decode(struct rpc_task *task, struct xdr_stream *xdr)
838 {
839 	kxdrdproc_t decode = task->tk_msg.rpc_proc->p_decode;
840 
841 	return decode(task->tk_rqstp, xdr, task->tk_msg.rpc_resp);
842 }
843 EXPORT_SYMBOL_GPL(rpcauth_unwrap_resp_decode);
844 
845 /**
846  * rpcauth_unwrap_resp - Invoke unwrap and decode function for the cred
847  * @task: controlling RPC task
848  * @xdr: stream where the Reply message resides
849  *
850  * Returns zero on success; otherwise a negative errno is returned.
851  */
852 int
853 rpcauth_unwrap_resp(struct rpc_task *task, struct xdr_stream *xdr)
854 {
855 	const struct rpc_credops *ops = task->tk_rqstp->rq_cred->cr_ops;
856 
857 	return ops->crunwrap_resp(task, xdr);
858 }
859 
860 bool
861 rpcauth_xmit_need_reencode(struct rpc_task *task)
862 {
863 	struct rpc_cred *cred = task->tk_rqstp->rq_cred;
864 
865 	if (!cred || !cred->cr_ops->crneed_reencode)
866 		return false;
867 	return cred->cr_ops->crneed_reencode(task);
868 }
869 
870 int
871 rpcauth_refreshcred(struct rpc_task *task)
872 {
873 	struct rpc_cred	*cred;
874 	int err;
875 
876 	cred = task->tk_rqstp->rq_cred;
877 	if (cred == NULL) {
878 		err = rpcauth_bindcred(task, task->tk_msg.rpc_cred, task->tk_flags);
879 		if (err < 0)
880 			goto out;
881 		cred = task->tk_rqstp->rq_cred;
882 	}
883 
884 	err = cred->cr_ops->crrefresh(task);
885 out:
886 	if (err < 0)
887 		task->tk_status = err;
888 	return err;
889 }
890 
891 void
892 rpcauth_invalcred(struct rpc_task *task)
893 {
894 	struct rpc_cred *cred = task->tk_rqstp->rq_cred;
895 
896 	if (cred)
897 		clear_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
898 }
899 
900 int
901 rpcauth_uptodatecred(struct rpc_task *task)
902 {
903 	struct rpc_cred *cred = task->tk_rqstp->rq_cred;
904 
905 	return cred == NULL ||
906 		test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0;
907 }
908 
909 static struct shrinker rpc_cred_shrinker = {
910 	.count_objects = rpcauth_cache_shrink_count,
911 	.scan_objects = rpcauth_cache_shrink_scan,
912 	.seeks = DEFAULT_SEEKS,
913 };
914 
915 int __init rpcauth_init_module(void)
916 {
917 	int err;
918 
919 	err = rpc_init_authunix();
920 	if (err < 0)
921 		goto out1;
922 	err = register_shrinker(&rpc_cred_shrinker);
923 	if (err < 0)
924 		goto out2;
925 	return 0;
926 out2:
927 	rpc_destroy_authunix();
928 out1:
929 	return err;
930 }
931 
932 void rpcauth_remove_module(void)
933 {
934 	rpc_destroy_authunix();
935 	unregister_shrinker(&rpc_cred_shrinker);
936 }
937