xref: /openbmc/linux/net/sunrpc/auth.c (revision 7dd65feb) 
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 		/* Enforce a 60 second garbage collection moratorium */
240 		if (time_in_range_open(cred->cr_expire, expired, jiffies) &&
241 		    test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0)
242 			continue;
243 
244 		list_del_init(&cred->cr_lru);
245 		number_cred_unused--;
246 		if (atomic_read(&cred->cr_count) != 0)
247 			continue;
248 
249 		cache_lock = &cred->cr_auth->au_credcache->lock;
250 		spin_lock(cache_lock);
251 		if (atomic_read(&cred->cr_count) == 0) {
252 			get_rpccred(cred);
253 			list_add_tail(&cred->cr_lru, free);
254 			rpcauth_unhash_cred_locked(cred);
255 			nr_to_scan--;
256 		}
257 		spin_unlock(cache_lock);
258 		if (nr_to_scan == 0)
259 			break;
260 	}
261 	return nr_to_scan;
262 }
263 
264 /*
265  * Run memory cache shrinker.
266  */
267 static int
268 rpcauth_cache_shrinker(int nr_to_scan, gfp_t gfp_mask)
269 {
270 	LIST_HEAD(free);
271 	int res;
272 
273 	if (list_empty(&cred_unused))
274 		return 0;
275 	spin_lock(&rpc_credcache_lock);
276 	nr_to_scan = rpcauth_prune_expired(&free, nr_to_scan);
277 	res = (number_cred_unused / 100) * sysctl_vfs_cache_pressure;
278 	spin_unlock(&rpc_credcache_lock);
279 	rpcauth_destroy_credlist(&free);
280 	return res;
281 }
282 
283 /*
284  * Look up a process' credentials in the authentication cache
285  */
286 struct rpc_cred *
287 rpcauth_lookup_credcache(struct rpc_auth *auth, struct auth_cred * acred,
288 		int flags)
289 {
290 	LIST_HEAD(free);
291 	struct rpc_cred_cache *cache = auth->au_credcache;
292 	struct hlist_node *pos;
293 	struct rpc_cred	*cred = NULL,
294 			*entry, *new;
295 	unsigned int nr;
296 
297 	nr = hash_long(acred->uid, RPC_CREDCACHE_HASHBITS);
298 
299 	rcu_read_lock();
300 	hlist_for_each_entry_rcu(entry, pos, &cache->hashtable[nr], cr_hash) {
301 		if (!entry->cr_ops->crmatch(acred, entry, flags))
302 			continue;
303 		spin_lock(&cache->lock);
304 		if (test_bit(RPCAUTH_CRED_HASHED, &entry->cr_flags) == 0) {
305 			spin_unlock(&cache->lock);
306 			continue;
307 		}
308 		cred = get_rpccred(entry);
309 		spin_unlock(&cache->lock);
310 		break;
311 	}
312 	rcu_read_unlock();
313 
314 	if (cred != NULL)
315 		goto found;
316 
317 	new = auth->au_ops->crcreate(auth, acred, flags);
318 	if (IS_ERR(new)) {
319 		cred = new;
320 		goto out;
321 	}
322 
323 	spin_lock(&cache->lock);
324 	hlist_for_each_entry(entry, pos, &cache->hashtable[nr], cr_hash) {
325 		if (!entry->cr_ops->crmatch(acred, entry, flags))
326 			continue;
327 		cred = get_rpccred(entry);
328 		break;
329 	}
330 	if (cred == NULL) {
331 		cred = new;
332 		set_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags);
333 		hlist_add_head_rcu(&cred->cr_hash, &cache->hashtable[nr]);
334 	} else
335 		list_add_tail(&new->cr_lru, &free);
336 	spin_unlock(&cache->lock);
337 found:
338 	if (test_bit(RPCAUTH_CRED_NEW, &cred->cr_flags) &&
339 	    cred->cr_ops->cr_init != NULL &&
340 	    !(flags & RPCAUTH_LOOKUP_NEW)) {
341 		int res = cred->cr_ops->cr_init(auth, cred);
342 		if (res < 0) {
343 			put_rpccred(cred);
344 			cred = ERR_PTR(res);
345 		}
346 	}
347 	rpcauth_destroy_credlist(&free);
348 out:
349 	return cred;
350 }
351 EXPORT_SYMBOL_GPL(rpcauth_lookup_credcache);
352 
353 struct rpc_cred *
354 rpcauth_lookupcred(struct rpc_auth *auth, int flags)
355 {
356 	struct auth_cred acred;
357 	struct rpc_cred *ret;
358 	const struct cred *cred = current_cred();
359 
360 	dprintk("RPC:       looking up %s cred\n",
361 		auth->au_ops->au_name);
362 
363 	memset(&acred, 0, sizeof(acred));
364 	acred.uid = cred->fsuid;
365 	acred.gid = cred->fsgid;
366 	acred.group_info = get_group_info(((struct cred *)cred)->group_info);
367 
368 	ret = auth->au_ops->lookup_cred(auth, &acred, flags);
369 	put_group_info(acred.group_info);
370 	return ret;
371 }
372 
373 void
374 rpcauth_init_cred(struct rpc_cred *cred, const struct auth_cred *acred,
375 		  struct rpc_auth *auth, const struct rpc_credops *ops)
376 {
377 	INIT_HLIST_NODE(&cred->cr_hash);
378 	INIT_LIST_HEAD(&cred->cr_lru);
379 	atomic_set(&cred->cr_count, 1);
380 	cred->cr_auth = auth;
381 	cred->cr_ops = ops;
382 	cred->cr_expire = jiffies;
383 #ifdef RPC_DEBUG
384 	cred->cr_magic = RPCAUTH_CRED_MAGIC;
385 #endif
386 	cred->cr_uid = acred->uid;
387 }
388 EXPORT_SYMBOL_GPL(rpcauth_init_cred);
389 
390 void
391 rpcauth_generic_bind_cred(struct rpc_task *task, struct rpc_cred *cred, int lookupflags)
392 {
393 	task->tk_msg.rpc_cred = get_rpccred(cred);
394 	dprintk("RPC: %5u holding %s cred %p\n", task->tk_pid,
395 			cred->cr_auth->au_ops->au_name, cred);
396 }
397 EXPORT_SYMBOL_GPL(rpcauth_generic_bind_cred);
398 
399 static void
400 rpcauth_bind_root_cred(struct rpc_task *task, int lookupflags)
401 {
402 	struct rpc_auth *auth = task->tk_client->cl_auth;
403 	struct auth_cred acred = {
404 		.uid = 0,
405 		.gid = 0,
406 	};
407 	struct rpc_cred *ret;
408 
409 	dprintk("RPC: %5u looking up %s cred\n",
410 		task->tk_pid, task->tk_client->cl_auth->au_ops->au_name);
411 	ret = auth->au_ops->lookup_cred(auth, &acred, lookupflags);
412 	if (!IS_ERR(ret))
413 		task->tk_msg.rpc_cred = ret;
414 	else
415 		task->tk_status = PTR_ERR(ret);
416 }
417 
418 static void
419 rpcauth_bind_new_cred(struct rpc_task *task, int lookupflags)
420 {
421 	struct rpc_auth *auth = task->tk_client->cl_auth;
422 	struct rpc_cred *ret;
423 
424 	dprintk("RPC: %5u looking up %s cred\n",
425 		task->tk_pid, auth->au_ops->au_name);
426 	ret = rpcauth_lookupcred(auth, lookupflags);
427 	if (!IS_ERR(ret))
428 		task->tk_msg.rpc_cred = ret;
429 	else
430 		task->tk_status = PTR_ERR(ret);
431 }
432 
433 void
434 rpcauth_bindcred(struct rpc_task *task, struct rpc_cred *cred, int flags)
435 {
436 	int lookupflags = 0;
437 
438 	if (flags & RPC_TASK_ASYNC)
439 		lookupflags |= RPCAUTH_LOOKUP_NEW;
440 	if (cred != NULL)
441 		cred->cr_ops->crbind(task, cred, lookupflags);
442 	else if (flags & RPC_TASK_ROOTCREDS)
443 		rpcauth_bind_root_cred(task, lookupflags);
444 	else
445 		rpcauth_bind_new_cred(task, lookupflags);
446 }
447 
448 void
449 put_rpccred(struct rpc_cred *cred)
450 {
451 	/* Fast path for unhashed credentials */
452 	if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) == 0) {
453 		if (atomic_dec_and_test(&cred->cr_count))
454 			cred->cr_ops->crdestroy(cred);
455 		return;
456 	}
457 
458 	if (!atomic_dec_and_lock(&cred->cr_count, &rpc_credcache_lock))
459 		return;
460 	if (!list_empty(&cred->cr_lru)) {
461 		number_cred_unused--;
462 		list_del_init(&cred->cr_lru);
463 	}
464 	if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0) {
465 		if (test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0) {
466 			cred->cr_expire = jiffies;
467 			list_add_tail(&cred->cr_lru, &cred_unused);
468 			number_cred_unused++;
469 			goto out_nodestroy;
470 		}
471 		if (!rpcauth_unhash_cred(cred)) {
472 			/* We were hashed and someone looked us up... */
473 			goto out_nodestroy;
474 		}
475 	}
476 	spin_unlock(&rpc_credcache_lock);
477 	cred->cr_ops->crdestroy(cred);
478 	return;
479 out_nodestroy:
480 	spin_unlock(&rpc_credcache_lock);
481 }
482 EXPORT_SYMBOL_GPL(put_rpccred);
483 
484 void
485 rpcauth_unbindcred(struct rpc_task *task)
486 {
487 	struct rpc_cred	*cred = task->tk_msg.rpc_cred;
488 
489 	dprintk("RPC: %5u releasing %s cred %p\n",
490 		task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
491 
492 	put_rpccred(cred);
493 	task->tk_msg.rpc_cred = NULL;
494 }
495 
496 __be32 *
497 rpcauth_marshcred(struct rpc_task *task, __be32 *p)
498 {
499 	struct rpc_cred	*cred = task->tk_msg.rpc_cred;
500 
501 	dprintk("RPC: %5u marshaling %s cred %p\n",
502 		task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
503 
504 	return cred->cr_ops->crmarshal(task, p);
505 }
506 
507 __be32 *
508 rpcauth_checkverf(struct rpc_task *task, __be32 *p)
509 {
510 	struct rpc_cred	*cred = task->tk_msg.rpc_cred;
511 
512 	dprintk("RPC: %5u validating %s cred %p\n",
513 		task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
514 
515 	return cred->cr_ops->crvalidate(task, p);
516 }
517 
518 int
519 rpcauth_wrap_req(struct rpc_task *task, kxdrproc_t encode, void *rqstp,
520 		__be32 *data, void *obj)
521 {
522 	struct rpc_cred *cred = task->tk_msg.rpc_cred;
523 
524 	dprintk("RPC: %5u using %s cred %p to wrap rpc data\n",
525 			task->tk_pid, cred->cr_ops->cr_name, cred);
526 	if (cred->cr_ops->crwrap_req)
527 		return cred->cr_ops->crwrap_req(task, encode, rqstp, data, obj);
528 	/* By default, we encode the arguments normally. */
529 	return encode(rqstp, data, obj);
530 }
531 
532 int
533 rpcauth_unwrap_resp(struct rpc_task *task, kxdrproc_t decode, void *rqstp,
534 		__be32 *data, void *obj)
535 {
536 	struct rpc_cred *cred = task->tk_msg.rpc_cred;
537 
538 	dprintk("RPC: %5u using %s cred %p to unwrap rpc data\n",
539 			task->tk_pid, cred->cr_ops->cr_name, cred);
540 	if (cred->cr_ops->crunwrap_resp)
541 		return cred->cr_ops->crunwrap_resp(task, decode, rqstp,
542 						   data, obj);
543 	/* By default, we decode the arguments normally. */
544 	return decode(rqstp, data, obj);
545 }
546 
547 int
548 rpcauth_refreshcred(struct rpc_task *task)
549 {
550 	struct rpc_cred	*cred = task->tk_msg.rpc_cred;
551 	int err;
552 
553 	dprintk("RPC: %5u refreshing %s cred %p\n",
554 		task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
555 
556 	err = cred->cr_ops->crrefresh(task);
557 	if (err < 0)
558 		task->tk_status = err;
559 	return err;
560 }
561 
562 void
563 rpcauth_invalcred(struct rpc_task *task)
564 {
565 	struct rpc_cred *cred = task->tk_msg.rpc_cred;
566 
567 	dprintk("RPC: %5u invalidating %s cred %p\n",
568 		task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
569 	if (cred)
570 		clear_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
571 }
572 
573 int
574 rpcauth_uptodatecred(struct rpc_task *task)
575 {
576 	struct rpc_cred *cred = task->tk_msg.rpc_cred;
577 
578 	return cred == NULL ||
579 		test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0;
580 }
581 
582 static struct shrinker rpc_cred_shrinker = {
583 	.shrink = rpcauth_cache_shrinker,
584 	.seeks = DEFAULT_SEEKS,
585 };
586 
587 void __init rpcauth_init_module(void)
588 {
589 	rpc_init_authunix();
590 	rpc_init_generic_auth();
591 	register_shrinker(&rpc_cred_shrinker);
592 }
593 
594 void __exit rpcauth_remove_module(void)
595 {
596 	unregister_shrinker(&rpc_cred_shrinker);
597 }
598