xref: /openbmc/linux/net/sunrpc/auth.c (revision 1fa6ac37) 
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 static DEFINE_SPINLOCK(rpc_authflavor_lock);
23 static const struct rpc_authops *auth_flavors[RPC_AUTH_MAXFLAVOR] = {
24 	&authnull_ops,		/* AUTH_NULL */
25 	&authunix_ops,		/* AUTH_UNIX */
26 	NULL,			/* others can be loadable modules */
27 };
28 
29 static LIST_HEAD(cred_unused);
30 static unsigned long number_cred_unused;
31 
32 static u32
33 pseudoflavor_to_flavor(u32 flavor) {
34 	if (flavor >= RPC_AUTH_MAXFLAVOR)
35 		return RPC_AUTH_GSS;
36 	return flavor;
37 }
38 
39 int
40 rpcauth_register(const struct rpc_authops *ops)
41 {
42 	rpc_authflavor_t flavor;
43 	int ret = -EPERM;
44 
45 	if ((flavor = ops->au_flavor) >= RPC_AUTH_MAXFLAVOR)
46 		return -EINVAL;
47 	spin_lock(&rpc_authflavor_lock);
48 	if (auth_flavors[flavor] == NULL) {
49 		auth_flavors[flavor] = ops;
50 		ret = 0;
51 	}
52 	spin_unlock(&rpc_authflavor_lock);
53 	return ret;
54 }
55 EXPORT_SYMBOL_GPL(rpcauth_register);
56 
57 int
58 rpcauth_unregister(const struct rpc_authops *ops)
59 {
60 	rpc_authflavor_t flavor;
61 	int ret = -EPERM;
62 
63 	if ((flavor = ops->au_flavor) >= RPC_AUTH_MAXFLAVOR)
64 		return -EINVAL;
65 	spin_lock(&rpc_authflavor_lock);
66 	if (auth_flavors[flavor] == ops) {
67 		auth_flavors[flavor] = NULL;
68 		ret = 0;
69 	}
70 	spin_unlock(&rpc_authflavor_lock);
71 	return ret;
72 }
73 EXPORT_SYMBOL_GPL(rpcauth_unregister);
74 
75 struct rpc_auth *
76 rpcauth_create(rpc_authflavor_t pseudoflavor, struct rpc_clnt *clnt)
77 {
78 	struct rpc_auth		*auth;
79 	const struct rpc_authops *ops;
80 	u32			flavor = pseudoflavor_to_flavor(pseudoflavor);
81 
82 	auth = ERR_PTR(-EINVAL);
83 	if (flavor >= RPC_AUTH_MAXFLAVOR)
84 		goto out;
85 
86 	if ((ops = auth_flavors[flavor]) == NULL)
87 		request_module("rpc-auth-%u", flavor);
88 	spin_lock(&rpc_authflavor_lock);
89 	ops = auth_flavors[flavor];
90 	if (ops == NULL || !try_module_get(ops->owner)) {
91 		spin_unlock(&rpc_authflavor_lock);
92 		goto out;
93 	}
94 	spin_unlock(&rpc_authflavor_lock);
95 	auth = ops->create(clnt, pseudoflavor);
96 	module_put(ops->owner);
97 	if (IS_ERR(auth))
98 		return auth;
99 	if (clnt->cl_auth)
100 		rpcauth_release(clnt->cl_auth);
101 	clnt->cl_auth = auth;
102 
103 out:
104 	return auth;
105 }
106 EXPORT_SYMBOL_GPL(rpcauth_create);
107 
108 void
109 rpcauth_release(struct rpc_auth *auth)
110 {
111 	if (!atomic_dec_and_test(&auth->au_count))
112 		return;
113 	auth->au_ops->destroy(auth);
114 }
115 
116 static DEFINE_SPINLOCK(rpc_credcache_lock);
117 
118 static void
119 rpcauth_unhash_cred_locked(struct rpc_cred *cred)
120 {
121 	hlist_del_rcu(&cred->cr_hash);
122 	smp_mb__before_clear_bit();
123 	clear_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags);
124 }
125 
126 static int
127 rpcauth_unhash_cred(struct rpc_cred *cred)
128 {
129 	spinlock_t *cache_lock;
130 	int ret;
131 
132 	cache_lock = &cred->cr_auth->au_credcache->lock;
133 	spin_lock(cache_lock);
134 	ret = atomic_read(&cred->cr_count) == 0;
135 	if (ret)
136 		rpcauth_unhash_cred_locked(cred);
137 	spin_unlock(cache_lock);
138 	return ret;
139 }
140 
141 /*
142  * Initialize RPC credential cache
143  */
144 int
145 rpcauth_init_credcache(struct rpc_auth *auth)
146 {
147 	struct rpc_cred_cache *new;
148 	int i;
149 
150 	new = kmalloc(sizeof(*new), GFP_KERNEL);
151 	if (!new)
152 		return -ENOMEM;
153 	for (i = 0; i < RPC_CREDCACHE_NR; i++)
154 		INIT_HLIST_HEAD(&new->hashtable[i]);
155 	spin_lock_init(&new->lock);
156 	auth->au_credcache = new;
157 	return 0;
158 }
159 EXPORT_SYMBOL_GPL(rpcauth_init_credcache);
160 
161 /*
162  * Destroy a list of credentials
163  */
164 static inline
165 void rpcauth_destroy_credlist(struct list_head *head)
166 {
167 	struct rpc_cred *cred;
168 
169 	while (!list_empty(head)) {
170 		cred = list_entry(head->next, struct rpc_cred, cr_lru);
171 		list_del_init(&cred->cr_lru);
172 		put_rpccred(cred);
173 	}
174 }
175 
176 /*
177  * Clear the RPC credential cache, and delete those credentials
178  * that are not referenced.
179  */
180 void
181 rpcauth_clear_credcache(struct rpc_cred_cache *cache)
182 {
183 	LIST_HEAD(free);
184 	struct hlist_head *head;
185 	struct rpc_cred	*cred;
186 	int		i;
187 
188 	spin_lock(&rpc_credcache_lock);
189 	spin_lock(&cache->lock);
190 	for (i = 0; i < RPC_CREDCACHE_NR; i++) {
191 		head = &cache->hashtable[i];
192 		while (!hlist_empty(head)) {
193 			cred = hlist_entry(head->first, struct rpc_cred, cr_hash);
194 			get_rpccred(cred);
195 			if (!list_empty(&cred->cr_lru)) {
196 				list_del(&cred->cr_lru);
197 				number_cred_unused--;
198 			}
199 			list_add_tail(&cred->cr_lru, &free);
200 			rpcauth_unhash_cred_locked(cred);
201 		}
202 	}
203 	spin_unlock(&cache->lock);
204 	spin_unlock(&rpc_credcache_lock);
205 	rpcauth_destroy_credlist(&free);
206 }
207 
208 /*
209  * Destroy the RPC credential cache
210  */
211 void
212 rpcauth_destroy_credcache(struct rpc_auth *auth)
213 {
214 	struct rpc_cred_cache *cache = auth->au_credcache;
215 
216 	if (cache) {
217 		auth->au_credcache = NULL;
218 		rpcauth_clear_credcache(cache);
219 		kfree(cache);
220 	}
221 }
222 EXPORT_SYMBOL_GPL(rpcauth_destroy_credcache);
223 
224 
225 #define RPC_AUTH_EXPIRY_MORATORIUM (60 * HZ)
226 
227 /*
228  * Remove stale credentials. Avoid sleeping inside the loop.
229  */
230 static int
231 rpcauth_prune_expired(struct list_head *free, int nr_to_scan)
232 {
233 	spinlock_t *cache_lock;
234 	struct rpc_cred *cred, *next;
235 	unsigned long expired = jiffies - RPC_AUTH_EXPIRY_MORATORIUM;
236 
237 	list_for_each_entry_safe(cred, next, &cred_unused, cr_lru) {
238 
239 		if (nr_to_scan-- == 0)
240 			break;
241 		/*
242 		 * Enforce a 60 second garbage collection moratorium
243 		 * Note that the cred_unused list must be time-ordered.
244 		 */
245 		if (time_in_range(cred->cr_expire, expired, jiffies) &&
246 		    test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0)
247 			return 0;
248 
249 		list_del_init(&cred->cr_lru);
250 		number_cred_unused--;
251 		if (atomic_read(&cred->cr_count) != 0)
252 			continue;
253 
254 		cache_lock = &cred->cr_auth->au_credcache->lock;
255 		spin_lock(cache_lock);
256 		if (atomic_read(&cred->cr_count) == 0) {
257 			get_rpccred(cred);
258 			list_add_tail(&cred->cr_lru, free);
259 			rpcauth_unhash_cred_locked(cred);
260 		}
261 		spin_unlock(cache_lock);
262 	}
263 	return (number_cred_unused / 100) * sysctl_vfs_cache_pressure;
264 }
265 
266 /*
267  * Run memory cache shrinker.
268  */
269 static int
270 rpcauth_cache_shrinker(int nr_to_scan, gfp_t gfp_mask)
271 {
272 	LIST_HEAD(free);
273 	int res;
274 
275 	if ((gfp_mask & GFP_KERNEL) != GFP_KERNEL)
276 		return (nr_to_scan == 0) ? 0 : -1;
277 	if (list_empty(&cred_unused))
278 		return 0;
279 	spin_lock(&rpc_credcache_lock);
280 	res = rpcauth_prune_expired(&free, nr_to_scan);
281 	spin_unlock(&rpc_credcache_lock);
282 	rpcauth_destroy_credlist(&free);
283 	return res;
284 }
285 
286 /*
287  * Look up a process' credentials in the authentication cache
288  */
289 struct rpc_cred *
290 rpcauth_lookup_credcache(struct rpc_auth *auth, struct auth_cred * acred,
291 		int flags)
292 {
293 	LIST_HEAD(free);
294 	struct rpc_cred_cache *cache = auth->au_credcache;
295 	struct hlist_node *pos;
296 	struct rpc_cred	*cred = NULL,
297 			*entry, *new;
298 	unsigned int nr;
299 
300 	nr = hash_long(acred->uid, RPC_CREDCACHE_HASHBITS);
301 
302 	rcu_read_lock();
303 	hlist_for_each_entry_rcu(entry, pos, &cache->hashtable[nr], cr_hash) {
304 		if (!entry->cr_ops->crmatch(acred, entry, flags))
305 			continue;
306 		spin_lock(&cache->lock);
307 		if (test_bit(RPCAUTH_CRED_HASHED, &entry->cr_flags) == 0) {
308 			spin_unlock(&cache->lock);
309 			continue;
310 		}
311 		cred = get_rpccred(entry);
312 		spin_unlock(&cache->lock);
313 		break;
314 	}
315 	rcu_read_unlock();
316 
317 	if (cred != NULL)
318 		goto found;
319 
320 	new = auth->au_ops->crcreate(auth, acred, flags);
321 	if (IS_ERR(new)) {
322 		cred = new;
323 		goto out;
324 	}
325 
326 	spin_lock(&cache->lock);
327 	hlist_for_each_entry(entry, pos, &cache->hashtable[nr], cr_hash) {
328 		if (!entry->cr_ops->crmatch(acred, entry, flags))
329 			continue;
330 		cred = get_rpccred(entry);
331 		break;
332 	}
333 	if (cred == NULL) {
334 		cred = new;
335 		set_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags);
336 		hlist_add_head_rcu(&cred->cr_hash, &cache->hashtable[nr]);
337 	} else
338 		list_add_tail(&new->cr_lru, &free);
339 	spin_unlock(&cache->lock);
340 found:
341 	if (test_bit(RPCAUTH_CRED_NEW, &cred->cr_flags) &&
342 	    cred->cr_ops->cr_init != NULL &&
343 	    !(flags & RPCAUTH_LOOKUP_NEW)) {
344 		int res = cred->cr_ops->cr_init(auth, cred);
345 		if (res < 0) {
346 			put_rpccred(cred);
347 			cred = ERR_PTR(res);
348 		}
349 	}
350 	rpcauth_destroy_credlist(&free);
351 out:
352 	return cred;
353 }
354 EXPORT_SYMBOL_GPL(rpcauth_lookup_credcache);
355 
356 struct rpc_cred *
357 rpcauth_lookupcred(struct rpc_auth *auth, int flags)
358 {
359 	struct auth_cred acred;
360 	struct rpc_cred *ret;
361 	const struct cred *cred = current_cred();
362 
363 	dprintk("RPC:       looking up %s cred\n",
364 		auth->au_ops->au_name);
365 
366 	memset(&acred, 0, sizeof(acred));
367 	acred.uid = cred->fsuid;
368 	acred.gid = cred->fsgid;
369 	acred.group_info = get_group_info(((struct cred *)cred)->group_info);
370 
371 	ret = auth->au_ops->lookup_cred(auth, &acred, flags);
372 	put_group_info(acred.group_info);
373 	return ret;
374 }
375 
376 void
377 rpcauth_init_cred(struct rpc_cred *cred, const struct auth_cred *acred,
378 		  struct rpc_auth *auth, const struct rpc_credops *ops)
379 {
380 	INIT_HLIST_NODE(&cred->cr_hash);
381 	INIT_LIST_HEAD(&cred->cr_lru);
382 	atomic_set(&cred->cr_count, 1);
383 	cred->cr_auth = auth;
384 	cred->cr_ops = ops;
385 	cred->cr_expire = jiffies;
386 #ifdef RPC_DEBUG
387 	cred->cr_magic = RPCAUTH_CRED_MAGIC;
388 #endif
389 	cred->cr_uid = acred->uid;
390 }
391 EXPORT_SYMBOL_GPL(rpcauth_init_cred);
392 
393 void
394 rpcauth_generic_bind_cred(struct rpc_task *task, struct rpc_cred *cred, int lookupflags)
395 {
396 	task->tk_msg.rpc_cred = get_rpccred(cred);
397 	dprintk("RPC: %5u holding %s cred %p\n", task->tk_pid,
398 			cred->cr_auth->au_ops->au_name, cred);
399 }
400 EXPORT_SYMBOL_GPL(rpcauth_generic_bind_cred);
401 
402 static void
403 rpcauth_bind_root_cred(struct rpc_task *task, int lookupflags)
404 {
405 	struct rpc_auth *auth = task->tk_client->cl_auth;
406 	struct auth_cred acred = {
407 		.uid = 0,
408 		.gid = 0,
409 	};
410 	struct rpc_cred *ret;
411 
412 	dprintk("RPC: %5u looking up %s cred\n",
413 		task->tk_pid, task->tk_client->cl_auth->au_ops->au_name);
414 	ret = auth->au_ops->lookup_cred(auth, &acred, lookupflags);
415 	if (!IS_ERR(ret))
416 		task->tk_msg.rpc_cred = ret;
417 	else
418 		task->tk_status = PTR_ERR(ret);
419 }
420 
421 static void
422 rpcauth_bind_new_cred(struct rpc_task *task, int lookupflags)
423 {
424 	struct rpc_auth *auth = task->tk_client->cl_auth;
425 	struct rpc_cred *ret;
426 
427 	dprintk("RPC: %5u looking up %s cred\n",
428 		task->tk_pid, auth->au_ops->au_name);
429 	ret = rpcauth_lookupcred(auth, lookupflags);
430 	if (!IS_ERR(ret))
431 		task->tk_msg.rpc_cred = ret;
432 	else
433 		task->tk_status = PTR_ERR(ret);
434 }
435 
436 void
437 rpcauth_bindcred(struct rpc_task *task, struct rpc_cred *cred, int flags)
438 {
439 	int lookupflags = 0;
440 
441 	if (flags & RPC_TASK_ASYNC)
442 		lookupflags |= RPCAUTH_LOOKUP_NEW;
443 	if (cred != NULL)
444 		cred->cr_ops->crbind(task, cred, lookupflags);
445 	else if (flags & RPC_TASK_ROOTCREDS)
446 		rpcauth_bind_root_cred(task, lookupflags);
447 	else
448 		rpcauth_bind_new_cred(task, lookupflags);
449 }
450 
451 void
452 put_rpccred(struct rpc_cred *cred)
453 {
454 	/* Fast path for unhashed credentials */
455 	if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) == 0) {
456 		if (atomic_dec_and_test(&cred->cr_count))
457 			cred->cr_ops->crdestroy(cred);
458 		return;
459 	}
460 
461 	if (!atomic_dec_and_lock(&cred->cr_count, &rpc_credcache_lock))
462 		return;
463 	if (!list_empty(&cred->cr_lru)) {
464 		number_cred_unused--;
465 		list_del_init(&cred->cr_lru);
466 	}
467 	if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0) {
468 		if (test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0) {
469 			cred->cr_expire = jiffies;
470 			list_add_tail(&cred->cr_lru, &cred_unused);
471 			number_cred_unused++;
472 			goto out_nodestroy;
473 		}
474 		if (!rpcauth_unhash_cred(cred)) {
475 			/* We were hashed and someone looked us up... */
476 			goto out_nodestroy;
477 		}
478 	}
479 	spin_unlock(&rpc_credcache_lock);
480 	cred->cr_ops->crdestroy(cred);
481 	return;
482 out_nodestroy:
483 	spin_unlock(&rpc_credcache_lock);
484 }
485 EXPORT_SYMBOL_GPL(put_rpccred);
486 
487 void
488 rpcauth_unbindcred(struct rpc_task *task)
489 {
490 	struct rpc_cred	*cred = task->tk_msg.rpc_cred;
491 
492 	dprintk("RPC: %5u releasing %s cred %p\n",
493 		task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
494 
495 	put_rpccred(cred);
496 	task->tk_msg.rpc_cred = NULL;
497 }
498 
499 __be32 *
500 rpcauth_marshcred(struct rpc_task *task, __be32 *p)
501 {
502 	struct rpc_cred	*cred = task->tk_msg.rpc_cred;
503 
504 	dprintk("RPC: %5u marshaling %s cred %p\n",
505 		task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
506 
507 	return cred->cr_ops->crmarshal(task, p);
508 }
509 
510 __be32 *
511 rpcauth_checkverf(struct rpc_task *task, __be32 *p)
512 {
513 	struct rpc_cred	*cred = task->tk_msg.rpc_cred;
514 
515 	dprintk("RPC: %5u validating %s cred %p\n",
516 		task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
517 
518 	return cred->cr_ops->crvalidate(task, p);
519 }
520 
521 int
522 rpcauth_wrap_req(struct rpc_task *task, kxdrproc_t encode, void *rqstp,
523 		__be32 *data, void *obj)
524 {
525 	struct rpc_cred *cred = task->tk_msg.rpc_cred;
526 
527 	dprintk("RPC: %5u using %s cred %p to wrap rpc data\n",
528 			task->tk_pid, cred->cr_ops->cr_name, cred);
529 	if (cred->cr_ops->crwrap_req)
530 		return cred->cr_ops->crwrap_req(task, encode, rqstp, data, obj);
531 	/* By default, we encode the arguments normally. */
532 	return encode(rqstp, data, obj);
533 }
534 
535 int
536 rpcauth_unwrap_resp(struct rpc_task *task, kxdrproc_t decode, void *rqstp,
537 		__be32 *data, void *obj)
538 {
539 	struct rpc_cred *cred = task->tk_msg.rpc_cred;
540 
541 	dprintk("RPC: %5u using %s cred %p to unwrap rpc data\n",
542 			task->tk_pid, cred->cr_ops->cr_name, cred);
543 	if (cred->cr_ops->crunwrap_resp)
544 		return cred->cr_ops->crunwrap_resp(task, decode, rqstp,
545 						   data, obj);
546 	/* By default, we decode the arguments normally. */
547 	return decode(rqstp, data, obj);
548 }
549 
550 int
551 rpcauth_refreshcred(struct rpc_task *task)
552 {
553 	struct rpc_cred	*cred = task->tk_msg.rpc_cred;
554 	int err;
555 
556 	dprintk("RPC: %5u refreshing %s cred %p\n",
557 		task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
558 
559 	err = cred->cr_ops->crrefresh(task);
560 	if (err < 0)
561 		task->tk_status = err;
562 	return err;
563 }
564 
565 void
566 rpcauth_invalcred(struct rpc_task *task)
567 {
568 	struct rpc_cred *cred = task->tk_msg.rpc_cred;
569 
570 	dprintk("RPC: %5u invalidating %s cred %p\n",
571 		task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
572 	if (cred)
573 		clear_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
574 }
575 
576 int
577 rpcauth_uptodatecred(struct rpc_task *task)
578 {
579 	struct rpc_cred *cred = task->tk_msg.rpc_cred;
580 
581 	return cred == NULL ||
582 		test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0;
583 }
584 
585 static struct shrinker rpc_cred_shrinker = {
586 	.shrink = rpcauth_cache_shrinker,
587 	.seeks = DEFAULT_SEEKS,
588 };
589 
590 void __init rpcauth_init_module(void)
591 {
592 	rpc_init_authunix();
593 	rpc_init_generic_auth();
594 	register_shrinker(&rpc_cred_shrinker);
595 }
596 
597 void __exit rpcauth_remove_module(void)
598 {
599 	unregister_shrinker(&rpc_cred_shrinker);
600 }
601