xref: /openbmc/linux/net/sunrpc/auth.c (revision 643d1f7f) 
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/sunrpc/clnt.h>
15 #include <linux/spinlock.h>
16 
17 #ifdef RPC_DEBUG
18 # define RPCDBG_FACILITY	RPCDBG_AUTH
19 #endif
20 
21 static DEFINE_SPINLOCK(rpc_authflavor_lock);
22 static const struct rpc_authops *auth_flavors[RPC_AUTH_MAXFLAVOR] = {
23 	&authnull_ops,		/* AUTH_NULL */
24 	&authunix_ops,		/* AUTH_UNIX */
25 	NULL,			/* others can be loadable modules */
26 };
27 
28 static LIST_HEAD(cred_unused);
29 static unsigned long number_cred_unused;
30 
31 static u32
32 pseudoflavor_to_flavor(u32 flavor) {
33 	if (flavor >= RPC_AUTH_MAXFLAVOR)
34 		return RPC_AUTH_GSS;
35 	return flavor;
36 }
37 
38 int
39 rpcauth_register(const struct rpc_authops *ops)
40 {
41 	rpc_authflavor_t flavor;
42 	int ret = -EPERM;
43 
44 	if ((flavor = ops->au_flavor) >= RPC_AUTH_MAXFLAVOR)
45 		return -EINVAL;
46 	spin_lock(&rpc_authflavor_lock);
47 	if (auth_flavors[flavor] == NULL) {
48 		auth_flavors[flavor] = ops;
49 		ret = 0;
50 	}
51 	spin_unlock(&rpc_authflavor_lock);
52 	return ret;
53 }
54 EXPORT_SYMBOL_GPL(rpcauth_register);
55 
56 int
57 rpcauth_unregister(const struct rpc_authops *ops)
58 {
59 	rpc_authflavor_t flavor;
60 	int ret = -EPERM;
61 
62 	if ((flavor = ops->au_flavor) >= RPC_AUTH_MAXFLAVOR)
63 		return -EINVAL;
64 	spin_lock(&rpc_authflavor_lock);
65 	if (auth_flavors[flavor] == ops) {
66 		auth_flavors[flavor] = NULL;
67 		ret = 0;
68 	}
69 	spin_unlock(&rpc_authflavor_lock);
70 	return ret;
71 }
72 EXPORT_SYMBOL_GPL(rpcauth_unregister);
73 
74 struct rpc_auth *
75 rpcauth_create(rpc_authflavor_t pseudoflavor, struct rpc_clnt *clnt)
76 {
77 	struct rpc_auth		*auth;
78 	const struct rpc_authops *ops;
79 	u32			flavor = pseudoflavor_to_flavor(pseudoflavor);
80 
81 	auth = ERR_PTR(-EINVAL);
82 	if (flavor >= RPC_AUTH_MAXFLAVOR)
83 		goto out;
84 
85 #ifdef CONFIG_KMOD
86 	if ((ops = auth_flavors[flavor]) == NULL)
87 		request_module("rpc-auth-%u", flavor);
88 #endif
89 	spin_lock(&rpc_authflavor_lock);
90 	ops = auth_flavors[flavor];
91 	if (ops == NULL || !try_module_get(ops->owner)) {
92 		spin_unlock(&rpc_authflavor_lock);
93 		goto out;
94 	}
95 	spin_unlock(&rpc_authflavor_lock);
96 	auth = ops->create(clnt, pseudoflavor);
97 	module_put(ops->owner);
98 	if (IS_ERR(auth))
99 		return auth;
100 	if (clnt->cl_auth)
101 		rpcauth_release(clnt->cl_auth);
102 	clnt->cl_auth = auth;
103 
104 out:
105 	return auth;
106 }
107 EXPORT_SYMBOL_GPL(rpcauth_create);
108 
109 void
110 rpcauth_release(struct rpc_auth *auth)
111 {
112 	if (!atomic_dec_and_test(&auth->au_count))
113 		return;
114 	auth->au_ops->destroy(auth);
115 }
116 
117 static DEFINE_SPINLOCK(rpc_credcache_lock);
118 
119 static void
120 rpcauth_unhash_cred_locked(struct rpc_cred *cred)
121 {
122 	hlist_del_rcu(&cred->cr_hash);
123 	smp_mb__before_clear_bit();
124 	clear_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags);
125 }
126 
127 static void
128 rpcauth_unhash_cred(struct rpc_cred *cred)
129 {
130 	spinlock_t *cache_lock;
131 
132 	cache_lock = &cred->cr_auth->au_credcache->lock;
133 	spin_lock(cache_lock);
134 	if (atomic_read(&cred->cr_count) == 0)
135 		rpcauth_unhash_cred_locked(cred);
136 	spin_unlock(cache_lock);
137 }
138 
139 /*
140  * Initialize RPC credential cache
141  */
142 int
143 rpcauth_init_credcache(struct rpc_auth *auth)
144 {
145 	struct rpc_cred_cache *new;
146 	int i;
147 
148 	new = kmalloc(sizeof(*new), GFP_KERNEL);
149 	if (!new)
150 		return -ENOMEM;
151 	for (i = 0; i < RPC_CREDCACHE_NR; i++)
152 		INIT_HLIST_HEAD(&new->hashtable[i]);
153 	spin_lock_init(&new->lock);
154 	auth->au_credcache = new;
155 	return 0;
156 }
157 EXPORT_SYMBOL_GPL(rpcauth_init_credcache);
158 
159 /*
160  * Destroy a list of credentials
161  */
162 static inline
163 void rpcauth_destroy_credlist(struct list_head *head)
164 {
165 	struct rpc_cred *cred;
166 
167 	while (!list_empty(head)) {
168 		cred = list_entry(head->next, struct rpc_cred, cr_lru);
169 		list_del_init(&cred->cr_lru);
170 		put_rpccred(cred);
171 	}
172 }
173 
174 /*
175  * Clear the RPC credential cache, and delete those credentials
176  * that are not referenced.
177  */
178 void
179 rpcauth_clear_credcache(struct rpc_cred_cache *cache)
180 {
181 	LIST_HEAD(free);
182 	struct hlist_head *head;
183 	struct rpc_cred	*cred;
184 	int		i;
185 
186 	spin_lock(&rpc_credcache_lock);
187 	spin_lock(&cache->lock);
188 	for (i = 0; i < RPC_CREDCACHE_NR; i++) {
189 		head = &cache->hashtable[i];
190 		while (!hlist_empty(head)) {
191 			cred = hlist_entry(head->first, struct rpc_cred, cr_hash);
192 			get_rpccred(cred);
193 			if (!list_empty(&cred->cr_lru)) {
194 				list_del(&cred->cr_lru);
195 				number_cred_unused--;
196 			}
197 			list_add_tail(&cred->cr_lru, &free);
198 			rpcauth_unhash_cred_locked(cred);
199 		}
200 	}
201 	spin_unlock(&cache->lock);
202 	spin_unlock(&rpc_credcache_lock);
203 	rpcauth_destroy_credlist(&free);
204 }
205 
206 /*
207  * Destroy the RPC credential cache
208  */
209 void
210 rpcauth_destroy_credcache(struct rpc_auth *auth)
211 {
212 	struct rpc_cred_cache *cache = auth->au_credcache;
213 
214 	if (cache) {
215 		auth->au_credcache = NULL;
216 		rpcauth_clear_credcache(cache);
217 		kfree(cache);
218 	}
219 }
220 EXPORT_SYMBOL_GPL(rpcauth_destroy_credcache);
221 
222 /*
223  * Remove stale credentials. Avoid sleeping inside the loop.
224  */
225 static int
226 rpcauth_prune_expired(struct list_head *free, int nr_to_scan)
227 {
228 	spinlock_t *cache_lock;
229 	struct rpc_cred *cred;
230 
231 	while (!list_empty(&cred_unused)) {
232 		cred = list_entry(cred_unused.next, struct rpc_cred, cr_lru);
233 		list_del_init(&cred->cr_lru);
234 		number_cred_unused--;
235 		if (atomic_read(&cred->cr_count) != 0)
236 			continue;
237 		cache_lock = &cred->cr_auth->au_credcache->lock;
238 		spin_lock(cache_lock);
239 		if (atomic_read(&cred->cr_count) == 0) {
240 			get_rpccred(cred);
241 			list_add_tail(&cred->cr_lru, free);
242 			rpcauth_unhash_cred_locked(cred);
243 			nr_to_scan--;
244 		}
245 		spin_unlock(cache_lock);
246 		if (nr_to_scan == 0)
247 			break;
248 	}
249 	return nr_to_scan;
250 }
251 
252 /*
253  * Run memory cache shrinker.
254  */
255 static int
256 rpcauth_cache_shrinker(int nr_to_scan, gfp_t gfp_mask)
257 {
258 	LIST_HEAD(free);
259 	int res;
260 
261 	if (list_empty(&cred_unused))
262 		return 0;
263 	spin_lock(&rpc_credcache_lock);
264 	nr_to_scan = rpcauth_prune_expired(&free, nr_to_scan);
265 	res = (number_cred_unused / 100) * sysctl_vfs_cache_pressure;
266 	spin_unlock(&rpc_credcache_lock);
267 	rpcauth_destroy_credlist(&free);
268 	return res;
269 }
270 
271 /*
272  * Look up a process' credentials in the authentication cache
273  */
274 struct rpc_cred *
275 rpcauth_lookup_credcache(struct rpc_auth *auth, struct auth_cred * acred,
276 		int flags)
277 {
278 	LIST_HEAD(free);
279 	struct rpc_cred_cache *cache = auth->au_credcache;
280 	struct hlist_node *pos;
281 	struct rpc_cred	*cred = NULL,
282 			*entry, *new;
283 	int		nr = 0;
284 
285 	if (!(flags & RPCAUTH_LOOKUP_ROOTCREDS))
286 		nr = acred->uid & RPC_CREDCACHE_MASK;
287 
288 	rcu_read_lock();
289 	hlist_for_each_entry_rcu(entry, pos, &cache->hashtable[nr], cr_hash) {
290 		if (!entry->cr_ops->crmatch(acred, entry, flags))
291 			continue;
292 		spin_lock(&cache->lock);
293 		if (test_bit(RPCAUTH_CRED_HASHED, &entry->cr_flags) == 0) {
294 			spin_unlock(&cache->lock);
295 			continue;
296 		}
297 		cred = get_rpccred(entry);
298 		spin_unlock(&cache->lock);
299 		break;
300 	}
301 	rcu_read_unlock();
302 
303 	if (cred != NULL)
304 		goto found;
305 
306 	new = auth->au_ops->crcreate(auth, acred, flags);
307 	if (IS_ERR(new)) {
308 		cred = new;
309 		goto out;
310 	}
311 
312 	spin_lock(&cache->lock);
313 	hlist_for_each_entry(entry, pos, &cache->hashtable[nr], cr_hash) {
314 		if (!entry->cr_ops->crmatch(acred, entry, flags))
315 			continue;
316 		cred = get_rpccred(entry);
317 		break;
318 	}
319 	if (cred == NULL) {
320 		cred = new;
321 		set_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags);
322 		hlist_add_head_rcu(&cred->cr_hash, &cache->hashtable[nr]);
323 	} else
324 		list_add_tail(&new->cr_lru, &free);
325 	spin_unlock(&cache->lock);
326 found:
327 	if (test_bit(RPCAUTH_CRED_NEW, &cred->cr_flags)
328 			&& cred->cr_ops->cr_init != NULL
329 			&& !(flags & RPCAUTH_LOOKUP_NEW)) {
330 		int res = cred->cr_ops->cr_init(auth, cred);
331 		if (res < 0) {
332 			put_rpccred(cred);
333 			cred = ERR_PTR(res);
334 		}
335 	}
336 	rpcauth_destroy_credlist(&free);
337 out:
338 	return cred;
339 }
340 EXPORT_SYMBOL_GPL(rpcauth_lookup_credcache);
341 
342 struct rpc_cred *
343 rpcauth_lookupcred(struct rpc_auth *auth, int flags)
344 {
345 	struct auth_cred acred = {
346 		.uid = current->fsuid,
347 		.gid = current->fsgid,
348 		.group_info = current->group_info,
349 	};
350 	struct rpc_cred *ret;
351 
352 	dprintk("RPC:       looking up %s cred\n",
353 		auth->au_ops->au_name);
354 	get_group_info(acred.group_info);
355 	ret = auth->au_ops->lookup_cred(auth, &acred, flags);
356 	put_group_info(acred.group_info);
357 	return ret;
358 }
359 EXPORT_SYMBOL_GPL(rpcauth_lookupcred);
360 
361 void
362 rpcauth_init_cred(struct rpc_cred *cred, const struct auth_cred *acred,
363 		  struct rpc_auth *auth, const struct rpc_credops *ops)
364 {
365 	INIT_HLIST_NODE(&cred->cr_hash);
366 	INIT_LIST_HEAD(&cred->cr_lru);
367 	atomic_set(&cred->cr_count, 1);
368 	cred->cr_auth = auth;
369 	cred->cr_ops = ops;
370 	cred->cr_expire = jiffies;
371 #ifdef RPC_DEBUG
372 	cred->cr_magic = RPCAUTH_CRED_MAGIC;
373 #endif
374 	cred->cr_uid = acred->uid;
375 }
376 EXPORT_SYMBOL_GPL(rpcauth_init_cred);
377 
378 struct rpc_cred *
379 rpcauth_bindcred(struct rpc_task *task)
380 {
381 	struct rpc_auth *auth = task->tk_client->cl_auth;
382 	struct auth_cred acred = {
383 		.uid = current->fsuid,
384 		.gid = current->fsgid,
385 		.group_info = current->group_info,
386 	};
387 	struct rpc_cred *ret;
388 	int flags = 0;
389 
390 	dprintk("RPC: %5u looking up %s cred\n",
391 		task->tk_pid, task->tk_client->cl_auth->au_ops->au_name);
392 	get_group_info(acred.group_info);
393 	if (task->tk_flags & RPC_TASK_ROOTCREDS)
394 		flags |= RPCAUTH_LOOKUP_ROOTCREDS;
395 	ret = auth->au_ops->lookup_cred(auth, &acred, flags);
396 	if (!IS_ERR(ret))
397 		task->tk_msg.rpc_cred = ret;
398 	else
399 		task->tk_status = PTR_ERR(ret);
400 	put_group_info(acred.group_info);
401 	return ret;
402 }
403 
404 void
405 rpcauth_holdcred(struct rpc_task *task)
406 {
407 	struct rpc_cred *cred = task->tk_msg.rpc_cred;
408 	if (cred != NULL) {
409 		get_rpccred(cred);
410 		dprintk("RPC: %5u holding %s cred %p\n", task->tk_pid,
411 				cred->cr_auth->au_ops->au_name, cred);
412 	}
413 }
414 
415 void
416 put_rpccred(struct rpc_cred *cred)
417 {
418 	/* Fast path for unhashed credentials */
419 	if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0)
420 		goto need_lock;
421 
422 	if (!atomic_dec_and_test(&cred->cr_count))
423 		return;
424 	goto out_destroy;
425 need_lock:
426 	if (!atomic_dec_and_lock(&cred->cr_count, &rpc_credcache_lock))
427 		return;
428 	if (!list_empty(&cred->cr_lru)) {
429 		number_cred_unused--;
430 		list_del_init(&cred->cr_lru);
431 	}
432 	if (test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) == 0)
433 		rpcauth_unhash_cred(cred);
434 	else if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0) {
435 		cred->cr_expire = jiffies;
436 		list_add_tail(&cred->cr_lru, &cred_unused);
437 		number_cred_unused++;
438 		spin_unlock(&rpc_credcache_lock);
439 		return;
440 	}
441 	spin_unlock(&rpc_credcache_lock);
442 out_destroy:
443 	cred->cr_ops->crdestroy(cred);
444 }
445 EXPORT_SYMBOL_GPL(put_rpccred);
446 
447 void
448 rpcauth_unbindcred(struct rpc_task *task)
449 {
450 	struct rpc_cred	*cred = task->tk_msg.rpc_cred;
451 
452 	dprintk("RPC: %5u releasing %s cred %p\n",
453 		task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
454 
455 	put_rpccred(cred);
456 	task->tk_msg.rpc_cred = NULL;
457 }
458 
459 __be32 *
460 rpcauth_marshcred(struct rpc_task *task, __be32 *p)
461 {
462 	struct rpc_cred	*cred = task->tk_msg.rpc_cred;
463 
464 	dprintk("RPC: %5u marshaling %s cred %p\n",
465 		task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
466 
467 	return cred->cr_ops->crmarshal(task, p);
468 }
469 
470 __be32 *
471 rpcauth_checkverf(struct rpc_task *task, __be32 *p)
472 {
473 	struct rpc_cred	*cred = task->tk_msg.rpc_cred;
474 
475 	dprintk("RPC: %5u validating %s cred %p\n",
476 		task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
477 
478 	return cred->cr_ops->crvalidate(task, p);
479 }
480 
481 int
482 rpcauth_wrap_req(struct rpc_task *task, kxdrproc_t encode, void *rqstp,
483 		__be32 *data, void *obj)
484 {
485 	struct rpc_cred *cred = task->tk_msg.rpc_cred;
486 
487 	dprintk("RPC: %5u using %s cred %p to wrap rpc data\n",
488 			task->tk_pid, cred->cr_ops->cr_name, cred);
489 	if (cred->cr_ops->crwrap_req)
490 		return cred->cr_ops->crwrap_req(task, encode, rqstp, data, obj);
491 	/* By default, we encode the arguments normally. */
492 	return rpc_call_xdrproc(encode, rqstp, data, obj);
493 }
494 
495 int
496 rpcauth_unwrap_resp(struct rpc_task *task, kxdrproc_t decode, void *rqstp,
497 		__be32 *data, void *obj)
498 {
499 	struct rpc_cred *cred = task->tk_msg.rpc_cred;
500 
501 	dprintk("RPC: %5u using %s cred %p to unwrap rpc data\n",
502 			task->tk_pid, cred->cr_ops->cr_name, cred);
503 	if (cred->cr_ops->crunwrap_resp)
504 		return cred->cr_ops->crunwrap_resp(task, decode, rqstp,
505 						   data, obj);
506 	/* By default, we decode the arguments normally. */
507 	return rpc_call_xdrproc(decode, rqstp, data, obj);
508 }
509 
510 int
511 rpcauth_refreshcred(struct rpc_task *task)
512 {
513 	struct rpc_cred	*cred = task->tk_msg.rpc_cred;
514 	int err;
515 
516 	dprintk("RPC: %5u refreshing %s cred %p\n",
517 		task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
518 
519 	err = cred->cr_ops->crrefresh(task);
520 	if (err < 0)
521 		task->tk_status = err;
522 	return err;
523 }
524 
525 void
526 rpcauth_invalcred(struct rpc_task *task)
527 {
528 	struct rpc_cred *cred = task->tk_msg.rpc_cred;
529 
530 	dprintk("RPC: %5u invalidating %s cred %p\n",
531 		task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
532 	if (cred)
533 		clear_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
534 }
535 
536 int
537 rpcauth_uptodatecred(struct rpc_task *task)
538 {
539 	struct rpc_cred *cred = task->tk_msg.rpc_cred;
540 
541 	return cred == NULL ||
542 		test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0;
543 }
544 
545 static struct shrinker rpc_cred_shrinker = {
546 	.shrink = rpcauth_cache_shrinker,
547 	.seeks = DEFAULT_SEEKS,
548 };
549 
550 void __init rpcauth_init_module(void)
551 {
552 	rpc_init_authunix();
553 	register_shrinker(&rpc_cred_shrinker);
554 }
555 
556 void __exit rpcauth_remove_module(void)
557 {
558 	unregister_shrinker(&rpc_cred_shrinker);
559 }
560