xref: /openbmc/linux/net/sunrpc/auth.c (revision 9ac8d3fb)
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 void
127 rpcauth_unhash_cred(struct rpc_cred *cred)
128 {
129 	spinlock_t *cache_lock;
130 
131 	cache_lock = &cred->cr_auth->au_credcache->lock;
132 	spin_lock(cache_lock);
133 	if (atomic_read(&cred->cr_count) == 0)
134 		rpcauth_unhash_cred_locked(cred);
135 	spin_unlock(cache_lock);
136 }
137 
138 /*
139  * Initialize RPC credential cache
140  */
141 int
142 rpcauth_init_credcache(struct rpc_auth *auth)
143 {
144 	struct rpc_cred_cache *new;
145 	int i;
146 
147 	new = kmalloc(sizeof(*new), GFP_KERNEL);
148 	if (!new)
149 		return -ENOMEM;
150 	for (i = 0; i < RPC_CREDCACHE_NR; i++)
151 		INIT_HLIST_HEAD(&new->hashtable[i]);
152 	spin_lock_init(&new->lock);
153 	auth->au_credcache = new;
154 	return 0;
155 }
156 EXPORT_SYMBOL_GPL(rpcauth_init_credcache);
157 
158 /*
159  * Destroy a list of credentials
160  */
161 static inline
162 void rpcauth_destroy_credlist(struct list_head *head)
163 {
164 	struct rpc_cred *cred;
165 
166 	while (!list_empty(head)) {
167 		cred = list_entry(head->next, struct rpc_cred, cr_lru);
168 		list_del_init(&cred->cr_lru);
169 		put_rpccred(cred);
170 	}
171 }
172 
173 /*
174  * Clear the RPC credential cache, and delete those credentials
175  * that are not referenced.
176  */
177 void
178 rpcauth_clear_credcache(struct rpc_cred_cache *cache)
179 {
180 	LIST_HEAD(free);
181 	struct hlist_head *head;
182 	struct rpc_cred	*cred;
183 	int		i;
184 
185 	spin_lock(&rpc_credcache_lock);
186 	spin_lock(&cache->lock);
187 	for (i = 0; i < RPC_CREDCACHE_NR; i++) {
188 		head = &cache->hashtable[i];
189 		while (!hlist_empty(head)) {
190 			cred = hlist_entry(head->first, struct rpc_cred, cr_hash);
191 			get_rpccred(cred);
192 			if (!list_empty(&cred->cr_lru)) {
193 				list_del(&cred->cr_lru);
194 				number_cred_unused--;
195 			}
196 			list_add_tail(&cred->cr_lru, &free);
197 			rpcauth_unhash_cred_locked(cred);
198 		}
199 	}
200 	spin_unlock(&cache->lock);
201 	spin_unlock(&rpc_credcache_lock);
202 	rpcauth_destroy_credlist(&free);
203 }
204 
205 /*
206  * Destroy the RPC credential cache
207  */
208 void
209 rpcauth_destroy_credcache(struct rpc_auth *auth)
210 {
211 	struct rpc_cred_cache *cache = auth->au_credcache;
212 
213 	if (cache) {
214 		auth->au_credcache = NULL;
215 		rpcauth_clear_credcache(cache);
216 		kfree(cache);
217 	}
218 }
219 EXPORT_SYMBOL_GPL(rpcauth_destroy_credcache);
220 
221 
222 #define RPC_AUTH_EXPIRY_MORATORIUM (60 * HZ)
223 
224 /*
225  * Remove stale credentials. Avoid sleeping inside the loop.
226  */
227 static int
228 rpcauth_prune_expired(struct list_head *free, int nr_to_scan)
229 {
230 	spinlock_t *cache_lock;
231 	struct rpc_cred *cred, *next;
232 	unsigned long expired = jiffies - RPC_AUTH_EXPIRY_MORATORIUM;
233 
234 	list_for_each_entry_safe(cred, next, &cred_unused, cr_lru) {
235 
236 		/* Enforce a 60 second garbage collection moratorium */
237 		if (time_in_range(cred->cr_expire, expired, jiffies) &&
238 		    test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0)
239 			continue;
240 
241 		list_del_init(&cred->cr_lru);
242 		number_cred_unused--;
243 		if (atomic_read(&cred->cr_count) != 0)
244 			continue;
245 
246 		cache_lock = &cred->cr_auth->au_credcache->lock;
247 		spin_lock(cache_lock);
248 		if (atomic_read(&cred->cr_count) == 0) {
249 			get_rpccred(cred);
250 			list_add_tail(&cred->cr_lru, free);
251 			rpcauth_unhash_cred_locked(cred);
252 			nr_to_scan--;
253 		}
254 		spin_unlock(cache_lock);
255 		if (nr_to_scan == 0)
256 			break;
257 	}
258 	return nr_to_scan;
259 }
260 
261 /*
262  * Run memory cache shrinker.
263  */
264 static int
265 rpcauth_cache_shrinker(int nr_to_scan, gfp_t gfp_mask)
266 {
267 	LIST_HEAD(free);
268 	int res;
269 
270 	if (list_empty(&cred_unused))
271 		return 0;
272 	spin_lock(&rpc_credcache_lock);
273 	nr_to_scan = rpcauth_prune_expired(&free, nr_to_scan);
274 	res = (number_cred_unused / 100) * sysctl_vfs_cache_pressure;
275 	spin_unlock(&rpc_credcache_lock);
276 	rpcauth_destroy_credlist(&free);
277 	return res;
278 }
279 
280 /*
281  * Look up a process' credentials in the authentication cache
282  */
283 struct rpc_cred *
284 rpcauth_lookup_credcache(struct rpc_auth *auth, struct auth_cred * acred,
285 		int flags)
286 {
287 	LIST_HEAD(free);
288 	struct rpc_cred_cache *cache = auth->au_credcache;
289 	struct hlist_node *pos;
290 	struct rpc_cred	*cred = NULL,
291 			*entry, *new;
292 	unsigned int nr;
293 
294 	nr = hash_long(acred->uid, RPC_CREDCACHE_HASHBITS);
295 
296 	rcu_read_lock();
297 	hlist_for_each_entry_rcu(entry, pos, &cache->hashtable[nr], cr_hash) {
298 		if (!entry->cr_ops->crmatch(acred, entry, flags))
299 			continue;
300 		spin_lock(&cache->lock);
301 		if (test_bit(RPCAUTH_CRED_HASHED, &entry->cr_flags) == 0) {
302 			spin_unlock(&cache->lock);
303 			continue;
304 		}
305 		cred = get_rpccred(entry);
306 		spin_unlock(&cache->lock);
307 		break;
308 	}
309 	rcu_read_unlock();
310 
311 	if (cred != NULL)
312 		goto found;
313 
314 	new = auth->au_ops->crcreate(auth, acred, flags);
315 	if (IS_ERR(new)) {
316 		cred = new;
317 		goto out;
318 	}
319 
320 	spin_lock(&cache->lock);
321 	hlist_for_each_entry(entry, pos, &cache->hashtable[nr], cr_hash) {
322 		if (!entry->cr_ops->crmatch(acred, entry, flags))
323 			continue;
324 		cred = get_rpccred(entry);
325 		break;
326 	}
327 	if (cred == NULL) {
328 		cred = new;
329 		set_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags);
330 		hlist_add_head_rcu(&cred->cr_hash, &cache->hashtable[nr]);
331 	} else
332 		list_add_tail(&new->cr_lru, &free);
333 	spin_unlock(&cache->lock);
334 found:
335 	if (test_bit(RPCAUTH_CRED_NEW, &cred->cr_flags)
336 			&& cred->cr_ops->cr_init != NULL
337 			&& !(flags & RPCAUTH_LOOKUP_NEW)) {
338 		int res = cred->cr_ops->cr_init(auth, cred);
339 		if (res < 0) {
340 			put_rpccred(cred);
341 			cred = ERR_PTR(res);
342 		}
343 	}
344 	rpcauth_destroy_credlist(&free);
345 out:
346 	return cred;
347 }
348 EXPORT_SYMBOL_GPL(rpcauth_lookup_credcache);
349 
350 struct rpc_cred *
351 rpcauth_lookupcred(struct rpc_auth *auth, int flags)
352 {
353 	struct auth_cred acred = {
354 		.uid = current->fsuid,
355 		.gid = current->fsgid,
356 		.group_info = current->group_info,
357 	};
358 	struct rpc_cred *ret;
359 
360 	dprintk("RPC:       looking up %s cred\n",
361 		auth->au_ops->au_name);
362 	get_group_info(acred.group_info);
363 	ret = auth->au_ops->lookup_cred(auth, &acred, flags);
364 	put_group_info(acred.group_info);
365 	return ret;
366 }
367 
368 void
369 rpcauth_init_cred(struct rpc_cred *cred, const struct auth_cred *acred,
370 		  struct rpc_auth *auth, const struct rpc_credops *ops)
371 {
372 	INIT_HLIST_NODE(&cred->cr_hash);
373 	INIT_LIST_HEAD(&cred->cr_lru);
374 	atomic_set(&cred->cr_count, 1);
375 	cred->cr_auth = auth;
376 	cred->cr_ops = ops;
377 	cred->cr_expire = jiffies;
378 #ifdef RPC_DEBUG
379 	cred->cr_magic = RPCAUTH_CRED_MAGIC;
380 #endif
381 	cred->cr_uid = acred->uid;
382 }
383 EXPORT_SYMBOL_GPL(rpcauth_init_cred);
384 
385 void
386 rpcauth_generic_bind_cred(struct rpc_task *task, struct rpc_cred *cred)
387 {
388 	task->tk_msg.rpc_cred = get_rpccred(cred);
389 	dprintk("RPC: %5u holding %s cred %p\n", task->tk_pid,
390 			cred->cr_auth->au_ops->au_name, cred);
391 }
392 EXPORT_SYMBOL_GPL(rpcauth_generic_bind_cred);
393 
394 static void
395 rpcauth_bind_root_cred(struct rpc_task *task)
396 {
397 	struct rpc_auth *auth = task->tk_client->cl_auth;
398 	struct auth_cred acred = {
399 		.uid = 0,
400 		.gid = 0,
401 	};
402 	struct rpc_cred *ret;
403 
404 	dprintk("RPC: %5u looking up %s cred\n",
405 		task->tk_pid, task->tk_client->cl_auth->au_ops->au_name);
406 	ret = auth->au_ops->lookup_cred(auth, &acred, 0);
407 	if (!IS_ERR(ret))
408 		task->tk_msg.rpc_cred = ret;
409 	else
410 		task->tk_status = PTR_ERR(ret);
411 }
412 
413 static void
414 rpcauth_bind_new_cred(struct rpc_task *task)
415 {
416 	struct rpc_auth *auth = task->tk_client->cl_auth;
417 	struct rpc_cred *ret;
418 
419 	dprintk("RPC: %5u looking up %s cred\n",
420 		task->tk_pid, auth->au_ops->au_name);
421 	ret = rpcauth_lookupcred(auth, 0);
422 	if (!IS_ERR(ret))
423 		task->tk_msg.rpc_cred = ret;
424 	else
425 		task->tk_status = PTR_ERR(ret);
426 }
427 
428 void
429 rpcauth_bindcred(struct rpc_task *task, struct rpc_cred *cred, int flags)
430 {
431 	if (cred != NULL)
432 		cred->cr_ops->crbind(task, cred);
433 	else if (flags & RPC_TASK_ROOTCREDS)
434 		rpcauth_bind_root_cred(task);
435 	else
436 		rpcauth_bind_new_cred(task);
437 }
438 
439 void
440 put_rpccred(struct rpc_cred *cred)
441 {
442 	/* Fast path for unhashed credentials */
443 	if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0)
444 		goto need_lock;
445 
446 	if (!atomic_dec_and_test(&cred->cr_count))
447 		return;
448 	goto out_destroy;
449 need_lock:
450 	if (!atomic_dec_and_lock(&cred->cr_count, &rpc_credcache_lock))
451 		return;
452 	if (!list_empty(&cred->cr_lru)) {
453 		number_cred_unused--;
454 		list_del_init(&cred->cr_lru);
455 	}
456 	if (test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) == 0)
457 		rpcauth_unhash_cred(cred);
458 	if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0) {
459 		cred->cr_expire = jiffies;
460 		list_add_tail(&cred->cr_lru, &cred_unused);
461 		number_cred_unused++;
462 		spin_unlock(&rpc_credcache_lock);
463 		return;
464 	}
465 	spin_unlock(&rpc_credcache_lock);
466 out_destroy:
467 	cred->cr_ops->crdestroy(cred);
468 }
469 EXPORT_SYMBOL_GPL(put_rpccred);
470 
471 void
472 rpcauth_unbindcred(struct rpc_task *task)
473 {
474 	struct rpc_cred	*cred = task->tk_msg.rpc_cred;
475 
476 	dprintk("RPC: %5u releasing %s cred %p\n",
477 		task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
478 
479 	put_rpccred(cred);
480 	task->tk_msg.rpc_cred = NULL;
481 }
482 
483 __be32 *
484 rpcauth_marshcred(struct rpc_task *task, __be32 *p)
485 {
486 	struct rpc_cred	*cred = task->tk_msg.rpc_cred;
487 
488 	dprintk("RPC: %5u marshaling %s cred %p\n",
489 		task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
490 
491 	return cred->cr_ops->crmarshal(task, p);
492 }
493 
494 __be32 *
495 rpcauth_checkverf(struct rpc_task *task, __be32 *p)
496 {
497 	struct rpc_cred	*cred = task->tk_msg.rpc_cred;
498 
499 	dprintk("RPC: %5u validating %s cred %p\n",
500 		task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
501 
502 	return cred->cr_ops->crvalidate(task, p);
503 }
504 
505 int
506 rpcauth_wrap_req(struct rpc_task *task, kxdrproc_t encode, void *rqstp,
507 		__be32 *data, void *obj)
508 {
509 	struct rpc_cred *cred = task->tk_msg.rpc_cred;
510 
511 	dprintk("RPC: %5u using %s cred %p to wrap rpc data\n",
512 			task->tk_pid, cred->cr_ops->cr_name, cred);
513 	if (cred->cr_ops->crwrap_req)
514 		return cred->cr_ops->crwrap_req(task, encode, rqstp, data, obj);
515 	/* By default, we encode the arguments normally. */
516 	return rpc_call_xdrproc(encode, rqstp, data, obj);
517 }
518 
519 int
520 rpcauth_unwrap_resp(struct rpc_task *task, kxdrproc_t decode, void *rqstp,
521 		__be32 *data, void *obj)
522 {
523 	struct rpc_cred *cred = task->tk_msg.rpc_cred;
524 
525 	dprintk("RPC: %5u using %s cred %p to unwrap rpc data\n",
526 			task->tk_pid, cred->cr_ops->cr_name, cred);
527 	if (cred->cr_ops->crunwrap_resp)
528 		return cred->cr_ops->crunwrap_resp(task, decode, rqstp,
529 						   data, obj);
530 	/* By default, we decode the arguments normally. */
531 	return rpc_call_xdrproc(decode, rqstp, data, obj);
532 }
533 
534 int
535 rpcauth_refreshcred(struct rpc_task *task)
536 {
537 	struct rpc_cred	*cred = task->tk_msg.rpc_cred;
538 	int err;
539 
540 	dprintk("RPC: %5u refreshing %s cred %p\n",
541 		task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
542 
543 	err = cred->cr_ops->crrefresh(task);
544 	if (err < 0)
545 		task->tk_status = err;
546 	return err;
547 }
548 
549 void
550 rpcauth_invalcred(struct rpc_task *task)
551 {
552 	struct rpc_cred *cred = task->tk_msg.rpc_cred;
553 
554 	dprintk("RPC: %5u invalidating %s cred %p\n",
555 		task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
556 	if (cred)
557 		clear_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
558 }
559 
560 int
561 rpcauth_uptodatecred(struct rpc_task *task)
562 {
563 	struct rpc_cred *cred = task->tk_msg.rpc_cred;
564 
565 	return cred == NULL ||
566 		test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0;
567 }
568 
569 static struct shrinker rpc_cred_shrinker = {
570 	.shrink = rpcauth_cache_shrinker,
571 	.seeks = DEFAULT_SEEKS,
572 };
573 
574 void __init rpcauth_init_module(void)
575 {
576 	rpc_init_authunix();
577 	rpc_init_generic_auth();
578 	register_shrinker(&rpc_cred_shrinker);
579 }
580 
581 void __exit rpcauth_remove_module(void)
582 {
583 	unregister_shrinker(&rpc_cred_shrinker);
584 }
585