xref: /openbmc/linux/net/sunrpc/auth.c (revision 61a3e166) 
1 /*
2  * linux/net/sunrpc/auth.c
3  *
4  * Generic RPC client authentication API.
5  *
6  * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
7  */
8 
9 #include <linux/types.h>
10 #include <linux/sched.h>
11 #include <linux/module.h>
12 #include <linux/slab.h>
13 #include <linux/errno.h>
14 #include <linux/hash.h>
15 #include <linux/sunrpc/clnt.h>
16 #include <linux/spinlock.h>
17 
18 #ifdef RPC_DEBUG
19 # define RPCDBG_FACILITY	RPCDBG_AUTH
20 #endif
21 
22 #define RPC_CREDCACHE_DEFAULT_HASHBITS	(4)
23 struct rpc_cred_cache {
24 	struct hlist_head	*hashtable;
25 	unsigned int		hashbits;
26 	spinlock_t		lock;
27 };
28 
29 static unsigned int auth_hashbits = RPC_CREDCACHE_DEFAULT_HASHBITS;
30 
31 static DEFINE_SPINLOCK(rpc_authflavor_lock);
32 static const struct rpc_authops *auth_flavors[RPC_AUTH_MAXFLAVOR] = {
33 	&authnull_ops,		/* AUTH_NULL */
34 	&authunix_ops,		/* AUTH_UNIX */
35 	NULL,			/* others can be loadable modules */
36 };
37 
38 static LIST_HEAD(cred_unused);
39 static unsigned long number_cred_unused;
40 
41 #define MAX_HASHTABLE_BITS (10)
42 static int param_set_hashtbl_sz(const char *val, struct kernel_param *kp)
43 {
44 	unsigned long num;
45 	unsigned int nbits;
46 	int ret;
47 
48 	if (!val)
49 		goto out_inval;
50 	ret = strict_strtoul(val, 0, &num);
51 	if (ret == -EINVAL)
52 		goto out_inval;
53 	nbits = fls(num);
54 	if (num > (1U << nbits))
55 		nbits++;
56 	if (nbits > MAX_HASHTABLE_BITS || nbits < 2)
57 		goto out_inval;
58 	*(unsigned int *)kp->arg = nbits;
59 	return 0;
60 out_inval:
61 	return -EINVAL;
62 }
63 
64 static int param_get_hashtbl_sz(char *buffer, struct kernel_param *kp)
65 {
66 	unsigned int nbits;
67 
68 	nbits = *(unsigned int *)kp->arg;
69 	return sprintf(buffer, "%u", 1U << nbits);
70 }
71 
72 #define param_check_hashtbl_sz(name, p) __param_check(name, p, unsigned int);
73 
74 module_param_named(auth_hashtable_size, auth_hashbits, hashtbl_sz, 0644);
75 MODULE_PARM_DESC(auth_hashtable_size, "RPC credential cache hashtable size");
76 
77 static u32
78 pseudoflavor_to_flavor(u32 flavor) {
79 	if (flavor >= RPC_AUTH_MAXFLAVOR)
80 		return RPC_AUTH_GSS;
81 	return flavor;
82 }
83 
84 int
85 rpcauth_register(const struct rpc_authops *ops)
86 {
87 	rpc_authflavor_t flavor;
88 	int ret = -EPERM;
89 
90 	if ((flavor = ops->au_flavor) >= RPC_AUTH_MAXFLAVOR)
91 		return -EINVAL;
92 	spin_lock(&rpc_authflavor_lock);
93 	if (auth_flavors[flavor] == NULL) {
94 		auth_flavors[flavor] = ops;
95 		ret = 0;
96 	}
97 	spin_unlock(&rpc_authflavor_lock);
98 	return ret;
99 }
100 EXPORT_SYMBOL_GPL(rpcauth_register);
101 
102 int
103 rpcauth_unregister(const struct rpc_authops *ops)
104 {
105 	rpc_authflavor_t flavor;
106 	int ret = -EPERM;
107 
108 	if ((flavor = ops->au_flavor) >= RPC_AUTH_MAXFLAVOR)
109 		return -EINVAL;
110 	spin_lock(&rpc_authflavor_lock);
111 	if (auth_flavors[flavor] == ops) {
112 		auth_flavors[flavor] = NULL;
113 		ret = 0;
114 	}
115 	spin_unlock(&rpc_authflavor_lock);
116 	return ret;
117 }
118 EXPORT_SYMBOL_GPL(rpcauth_unregister);
119 
120 struct rpc_auth *
121 rpcauth_create(rpc_authflavor_t pseudoflavor, struct rpc_clnt *clnt)
122 {
123 	struct rpc_auth		*auth;
124 	const struct rpc_authops *ops;
125 	u32			flavor = pseudoflavor_to_flavor(pseudoflavor);
126 
127 	auth = ERR_PTR(-EINVAL);
128 	if (flavor >= RPC_AUTH_MAXFLAVOR)
129 		goto out;
130 
131 	if ((ops = auth_flavors[flavor]) == NULL)
132 		request_module("rpc-auth-%u", flavor);
133 	spin_lock(&rpc_authflavor_lock);
134 	ops = auth_flavors[flavor];
135 	if (ops == NULL || !try_module_get(ops->owner)) {
136 		spin_unlock(&rpc_authflavor_lock);
137 		goto out;
138 	}
139 	spin_unlock(&rpc_authflavor_lock);
140 	auth = ops->create(clnt, pseudoflavor);
141 	module_put(ops->owner);
142 	if (IS_ERR(auth))
143 		return auth;
144 	if (clnt->cl_auth)
145 		rpcauth_release(clnt->cl_auth);
146 	clnt->cl_auth = auth;
147 
148 out:
149 	return auth;
150 }
151 EXPORT_SYMBOL_GPL(rpcauth_create);
152 
153 void
154 rpcauth_release(struct rpc_auth *auth)
155 {
156 	if (!atomic_dec_and_test(&auth->au_count))
157 		return;
158 	auth->au_ops->destroy(auth);
159 }
160 
161 static DEFINE_SPINLOCK(rpc_credcache_lock);
162 
163 static void
164 rpcauth_unhash_cred_locked(struct rpc_cred *cred)
165 {
166 	hlist_del_rcu(&cred->cr_hash);
167 	smp_mb__before_clear_bit();
168 	clear_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags);
169 }
170 
171 static int
172 rpcauth_unhash_cred(struct rpc_cred *cred)
173 {
174 	spinlock_t *cache_lock;
175 	int ret;
176 
177 	cache_lock = &cred->cr_auth->au_credcache->lock;
178 	spin_lock(cache_lock);
179 	ret = atomic_read(&cred->cr_count) == 0;
180 	if (ret)
181 		rpcauth_unhash_cred_locked(cred);
182 	spin_unlock(cache_lock);
183 	return ret;
184 }
185 
186 /*
187  * Initialize RPC credential cache
188  */
189 int
190 rpcauth_init_credcache(struct rpc_auth *auth)
191 {
192 	struct rpc_cred_cache *new;
193 	unsigned int hashsize;
194 
195 	new = kmalloc(sizeof(*new), GFP_KERNEL);
196 	if (!new)
197 		goto out_nocache;
198 	new->hashbits = auth_hashbits;
199 	hashsize = 1U << new->hashbits;
200 	new->hashtable = kcalloc(hashsize, sizeof(new->hashtable[0]), GFP_KERNEL);
201 	if (!new->hashtable)
202 		goto out_nohashtbl;
203 	spin_lock_init(&new->lock);
204 	auth->au_credcache = new;
205 	return 0;
206 out_nohashtbl:
207 	kfree(new);
208 out_nocache:
209 	return -ENOMEM;
210 }
211 EXPORT_SYMBOL_GPL(rpcauth_init_credcache);
212 
213 /*
214  * Destroy a list of credentials
215  */
216 static inline
217 void rpcauth_destroy_credlist(struct list_head *head)
218 {
219 	struct rpc_cred *cred;
220 
221 	while (!list_empty(head)) {
222 		cred = list_entry(head->next, struct rpc_cred, cr_lru);
223 		list_del_init(&cred->cr_lru);
224 		put_rpccred(cred);
225 	}
226 }
227 
228 /*
229  * Clear the RPC credential cache, and delete those credentials
230  * that are not referenced.
231  */
232 void
233 rpcauth_clear_credcache(struct rpc_cred_cache *cache)
234 {
235 	LIST_HEAD(free);
236 	struct hlist_head *head;
237 	struct rpc_cred	*cred;
238 	unsigned int hashsize = 1U << cache->hashbits;
239 	int		i;
240 
241 	spin_lock(&rpc_credcache_lock);
242 	spin_lock(&cache->lock);
243 	for (i = 0; i < hashsize; i++) {
244 		head = &cache->hashtable[i];
245 		while (!hlist_empty(head)) {
246 			cred = hlist_entry(head->first, struct rpc_cred, cr_hash);
247 			get_rpccred(cred);
248 			if (!list_empty(&cred->cr_lru)) {
249 				list_del(&cred->cr_lru);
250 				number_cred_unused--;
251 			}
252 			list_add_tail(&cred->cr_lru, &free);
253 			rpcauth_unhash_cred_locked(cred);
254 		}
255 	}
256 	spin_unlock(&cache->lock);
257 	spin_unlock(&rpc_credcache_lock);
258 	rpcauth_destroy_credlist(&free);
259 }
260 
261 /*
262  * Destroy the RPC credential cache
263  */
264 void
265 rpcauth_destroy_credcache(struct rpc_auth *auth)
266 {
267 	struct rpc_cred_cache *cache = auth->au_credcache;
268 
269 	if (cache) {
270 		auth->au_credcache = NULL;
271 		rpcauth_clear_credcache(cache);
272 		kfree(cache->hashtable);
273 		kfree(cache);
274 	}
275 }
276 EXPORT_SYMBOL_GPL(rpcauth_destroy_credcache);
277 
278 
279 #define RPC_AUTH_EXPIRY_MORATORIUM (60 * HZ)
280 
281 /*
282  * Remove stale credentials. Avoid sleeping inside the loop.
283  */
284 static int
285 rpcauth_prune_expired(struct list_head *free, int nr_to_scan)
286 {
287 	spinlock_t *cache_lock;
288 	struct rpc_cred *cred, *next;
289 	unsigned long expired = jiffies - RPC_AUTH_EXPIRY_MORATORIUM;
290 
291 	list_for_each_entry_safe(cred, next, &cred_unused, cr_lru) {
292 
293 		if (nr_to_scan-- == 0)
294 			break;
295 		/*
296 		 * Enforce a 60 second garbage collection moratorium
297 		 * Note that the cred_unused list must be time-ordered.
298 		 */
299 		if (time_in_range(cred->cr_expire, expired, jiffies) &&
300 		    test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0)
301 			return 0;
302 
303 		list_del_init(&cred->cr_lru);
304 		number_cred_unused--;
305 		if (atomic_read(&cred->cr_count) != 0)
306 			continue;
307 
308 		cache_lock = &cred->cr_auth->au_credcache->lock;
309 		spin_lock(cache_lock);
310 		if (atomic_read(&cred->cr_count) == 0) {
311 			get_rpccred(cred);
312 			list_add_tail(&cred->cr_lru, free);
313 			rpcauth_unhash_cred_locked(cred);
314 		}
315 		spin_unlock(cache_lock);
316 	}
317 	return (number_cred_unused / 100) * sysctl_vfs_cache_pressure;
318 }
319 
320 /*
321  * Run memory cache shrinker.
322  */
323 static int
324 rpcauth_cache_shrinker(struct shrinker *shrink, int nr_to_scan, gfp_t gfp_mask)
325 {
326 	LIST_HEAD(free);
327 	int res;
328 
329 	if ((gfp_mask & GFP_KERNEL) != GFP_KERNEL)
330 		return (nr_to_scan == 0) ? 0 : -1;
331 	if (list_empty(&cred_unused))
332 		return 0;
333 	spin_lock(&rpc_credcache_lock);
334 	res = rpcauth_prune_expired(&free, nr_to_scan);
335 	spin_unlock(&rpc_credcache_lock);
336 	rpcauth_destroy_credlist(&free);
337 	return res;
338 }
339 
340 /*
341  * Look up a process' credentials in the authentication cache
342  */
343 struct rpc_cred *
344 rpcauth_lookup_credcache(struct rpc_auth *auth, struct auth_cred * acred,
345 		int flags)
346 {
347 	LIST_HEAD(free);
348 	struct rpc_cred_cache *cache = auth->au_credcache;
349 	struct hlist_node *pos;
350 	struct rpc_cred	*cred = NULL,
351 			*entry, *new;
352 	unsigned int nr;
353 
354 	nr = hash_long(acred->uid, cache->hashbits);
355 
356 	rcu_read_lock();
357 	hlist_for_each_entry_rcu(entry, pos, &cache->hashtable[nr], cr_hash) {
358 		if (!entry->cr_ops->crmatch(acred, entry, flags))
359 			continue;
360 		spin_lock(&cache->lock);
361 		if (test_bit(RPCAUTH_CRED_HASHED, &entry->cr_flags) == 0) {
362 			spin_unlock(&cache->lock);
363 			continue;
364 		}
365 		cred = get_rpccred(entry);
366 		spin_unlock(&cache->lock);
367 		break;
368 	}
369 	rcu_read_unlock();
370 
371 	if (cred != NULL)
372 		goto found;
373 
374 	new = auth->au_ops->crcreate(auth, acred, flags);
375 	if (IS_ERR(new)) {
376 		cred = new;
377 		goto out;
378 	}
379 
380 	spin_lock(&cache->lock);
381 	hlist_for_each_entry(entry, pos, &cache->hashtable[nr], cr_hash) {
382 		if (!entry->cr_ops->crmatch(acred, entry, flags))
383 			continue;
384 		cred = get_rpccred(entry);
385 		break;
386 	}
387 	if (cred == NULL) {
388 		cred = new;
389 		set_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags);
390 		hlist_add_head_rcu(&cred->cr_hash, &cache->hashtable[nr]);
391 	} else
392 		list_add_tail(&new->cr_lru, &free);
393 	spin_unlock(&cache->lock);
394 found:
395 	if (test_bit(RPCAUTH_CRED_NEW, &cred->cr_flags) &&
396 	    cred->cr_ops->cr_init != NULL &&
397 	    !(flags & RPCAUTH_LOOKUP_NEW)) {
398 		int res = cred->cr_ops->cr_init(auth, cred);
399 		if (res < 0) {
400 			put_rpccred(cred);
401 			cred = ERR_PTR(res);
402 		}
403 	}
404 	rpcauth_destroy_credlist(&free);
405 out:
406 	return cred;
407 }
408 EXPORT_SYMBOL_GPL(rpcauth_lookup_credcache);
409 
410 struct rpc_cred *
411 rpcauth_lookupcred(struct rpc_auth *auth, int flags)
412 {
413 	struct auth_cred acred;
414 	struct rpc_cred *ret;
415 	const struct cred *cred = current_cred();
416 
417 	dprintk("RPC:       looking up %s cred\n",
418 		auth->au_ops->au_name);
419 
420 	memset(&acred, 0, sizeof(acred));
421 	acred.uid = cred->fsuid;
422 	acred.gid = cred->fsgid;
423 	acred.group_info = get_group_info(((struct cred *)cred)->group_info);
424 
425 	ret = auth->au_ops->lookup_cred(auth, &acred, flags);
426 	put_group_info(acred.group_info);
427 	return ret;
428 }
429 
430 void
431 rpcauth_init_cred(struct rpc_cred *cred, const struct auth_cred *acred,
432 		  struct rpc_auth *auth, const struct rpc_credops *ops)
433 {
434 	INIT_HLIST_NODE(&cred->cr_hash);
435 	INIT_LIST_HEAD(&cred->cr_lru);
436 	atomic_set(&cred->cr_count, 1);
437 	cred->cr_auth = auth;
438 	cred->cr_ops = ops;
439 	cred->cr_expire = jiffies;
440 #ifdef RPC_DEBUG
441 	cred->cr_magic = RPCAUTH_CRED_MAGIC;
442 #endif
443 	cred->cr_uid = acred->uid;
444 }
445 EXPORT_SYMBOL_GPL(rpcauth_init_cred);
446 
447 struct rpc_cred *
448 rpcauth_generic_bind_cred(struct rpc_task *task, struct rpc_cred *cred, int lookupflags)
449 {
450 	dprintk("RPC: %5u holding %s cred %p\n", task->tk_pid,
451 			cred->cr_auth->au_ops->au_name, cred);
452 	return get_rpccred(cred);
453 }
454 EXPORT_SYMBOL_GPL(rpcauth_generic_bind_cred);
455 
456 static struct rpc_cred *
457 rpcauth_bind_root_cred(struct rpc_task *task, int lookupflags)
458 {
459 	struct rpc_auth *auth = task->tk_client->cl_auth;
460 	struct auth_cred acred = {
461 		.uid = 0,
462 		.gid = 0,
463 	};
464 
465 	dprintk("RPC: %5u looking up %s cred\n",
466 		task->tk_pid, task->tk_client->cl_auth->au_ops->au_name);
467 	return auth->au_ops->lookup_cred(auth, &acred, lookupflags);
468 }
469 
470 static struct rpc_cred *
471 rpcauth_bind_new_cred(struct rpc_task *task, int lookupflags)
472 {
473 	struct rpc_auth *auth = task->tk_client->cl_auth;
474 
475 	dprintk("RPC: %5u looking up %s cred\n",
476 		task->tk_pid, auth->au_ops->au_name);
477 	return rpcauth_lookupcred(auth, lookupflags);
478 }
479 
480 static int
481 rpcauth_bindcred(struct rpc_task *task, struct rpc_cred *cred, int flags)
482 {
483 	struct rpc_rqst *req = task->tk_rqstp;
484 	struct rpc_cred *new;
485 	int lookupflags = 0;
486 
487 	if (flags & RPC_TASK_ASYNC)
488 		lookupflags |= RPCAUTH_LOOKUP_NEW;
489 	if (cred != NULL)
490 		new = cred->cr_ops->crbind(task, cred, lookupflags);
491 	else if (flags & RPC_TASK_ROOTCREDS)
492 		new = rpcauth_bind_root_cred(task, lookupflags);
493 	else
494 		new = rpcauth_bind_new_cred(task, lookupflags);
495 	if (IS_ERR(new))
496 		return PTR_ERR(new);
497 	if (req->rq_cred != NULL)
498 		put_rpccred(req->rq_cred);
499 	req->rq_cred = new;
500 	return 0;
501 }
502 
503 void
504 put_rpccred(struct rpc_cred *cred)
505 {
506 	/* Fast path for unhashed credentials */
507 	if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) == 0) {
508 		if (atomic_dec_and_test(&cred->cr_count))
509 			cred->cr_ops->crdestroy(cred);
510 		return;
511 	}
512 
513 	if (!atomic_dec_and_lock(&cred->cr_count, &rpc_credcache_lock))
514 		return;
515 	if (!list_empty(&cred->cr_lru)) {
516 		number_cred_unused--;
517 		list_del_init(&cred->cr_lru);
518 	}
519 	if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0) {
520 		if (test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0) {
521 			cred->cr_expire = jiffies;
522 			list_add_tail(&cred->cr_lru, &cred_unused);
523 			number_cred_unused++;
524 			goto out_nodestroy;
525 		}
526 		if (!rpcauth_unhash_cred(cred)) {
527 			/* We were hashed and someone looked us up... */
528 			goto out_nodestroy;
529 		}
530 	}
531 	spin_unlock(&rpc_credcache_lock);
532 	cred->cr_ops->crdestroy(cred);
533 	return;
534 out_nodestroy:
535 	spin_unlock(&rpc_credcache_lock);
536 }
537 EXPORT_SYMBOL_GPL(put_rpccred);
538 
539 __be32 *
540 rpcauth_marshcred(struct rpc_task *task, __be32 *p)
541 {
542 	struct rpc_cred	*cred = task->tk_rqstp->rq_cred;
543 
544 	dprintk("RPC: %5u marshaling %s cred %p\n",
545 		task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
546 
547 	return cred->cr_ops->crmarshal(task, p);
548 }
549 
550 __be32 *
551 rpcauth_checkverf(struct rpc_task *task, __be32 *p)
552 {
553 	struct rpc_cred	*cred = task->tk_rqstp->rq_cred;
554 
555 	dprintk("RPC: %5u validating %s cred %p\n",
556 		task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
557 
558 	return cred->cr_ops->crvalidate(task, p);
559 }
560 
561 int
562 rpcauth_wrap_req(struct rpc_task *task, kxdrproc_t encode, void *rqstp,
563 		__be32 *data, void *obj)
564 {
565 	struct rpc_cred *cred = task->tk_rqstp->rq_cred;
566 
567 	dprintk("RPC: %5u using %s cred %p to wrap rpc data\n",
568 			task->tk_pid, cred->cr_ops->cr_name, cred);
569 	if (cred->cr_ops->crwrap_req)
570 		return cred->cr_ops->crwrap_req(task, encode, rqstp, data, obj);
571 	/* By default, we encode the arguments normally. */
572 	return encode(rqstp, data, obj);
573 }
574 
575 int
576 rpcauth_unwrap_resp(struct rpc_task *task, kxdrproc_t decode, void *rqstp,
577 		__be32 *data, void *obj)
578 {
579 	struct rpc_cred *cred = task->tk_rqstp->rq_cred;
580 
581 	dprintk("RPC: %5u using %s cred %p to unwrap rpc data\n",
582 			task->tk_pid, cred->cr_ops->cr_name, cred);
583 	if (cred->cr_ops->crunwrap_resp)
584 		return cred->cr_ops->crunwrap_resp(task, decode, rqstp,
585 						   data, obj);
586 	/* By default, we decode the arguments normally. */
587 	return decode(rqstp, data, obj);
588 }
589 
590 int
591 rpcauth_refreshcred(struct rpc_task *task)
592 {
593 	struct rpc_cred	*cred = task->tk_rqstp->rq_cred;
594 	int err;
595 
596 	cred = task->tk_rqstp->rq_cred;
597 	if (cred == NULL) {
598 		err = rpcauth_bindcred(task, task->tk_msg.rpc_cred, task->tk_flags);
599 		if (err < 0)
600 			goto out;
601 		cred = task->tk_rqstp->rq_cred;
602 	};
603 	dprintk("RPC: %5u refreshing %s cred %p\n",
604 		task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
605 
606 	err = cred->cr_ops->crrefresh(task);
607 out:
608 	if (err < 0)
609 		task->tk_status = err;
610 	return err;
611 }
612 
613 void
614 rpcauth_invalcred(struct rpc_task *task)
615 {
616 	struct rpc_cred *cred = task->tk_rqstp->rq_cred;
617 
618 	dprintk("RPC: %5u invalidating %s cred %p\n",
619 		task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
620 	if (cred)
621 		clear_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
622 }
623 
624 int
625 rpcauth_uptodatecred(struct rpc_task *task)
626 {
627 	struct rpc_cred *cred = task->tk_rqstp->rq_cred;
628 
629 	return cred == NULL ||
630 		test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0;
631 }
632 
633 static struct shrinker rpc_cred_shrinker = {
634 	.shrink = rpcauth_cache_shrinker,
635 	.seeks = DEFAULT_SEEKS,
636 };
637 
638 int __init rpcauth_init_module(void)
639 {
640 	int err;
641 
642 	err = rpc_init_authunix();
643 	if (err < 0)
644 		goto out1;
645 	err = rpc_init_generic_auth();
646 	if (err < 0)
647 		goto out2;
648 	register_shrinker(&rpc_cred_shrinker);
649 	return 0;
650 out2:
651 	rpc_destroy_authunix();
652 out1:
653 	return err;
654 }
655 
656 void __exit rpcauth_remove_module(void)
657 {
658 	rpc_destroy_authunix();
659 	rpc_destroy_generic_auth();
660 	unregister_shrinker(&rpc_cred_shrinker);
661 }
662