xref: /openbmc/linux/net/sunrpc/auth.c (revision c21b37f6) 
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 
55 int
56 rpcauth_unregister(const struct rpc_authops *ops)
57 {
58 	rpc_authflavor_t flavor;
59 	int ret = -EPERM;
60 
61 	if ((flavor = ops->au_flavor) >= RPC_AUTH_MAXFLAVOR)
62 		return -EINVAL;
63 	spin_lock(&rpc_authflavor_lock);
64 	if (auth_flavors[flavor] == ops) {
65 		auth_flavors[flavor] = NULL;
66 		ret = 0;
67 	}
68 	spin_unlock(&rpc_authflavor_lock);
69 	return ret;
70 }
71 
72 struct rpc_auth *
73 rpcauth_create(rpc_authflavor_t pseudoflavor, struct rpc_clnt *clnt)
74 {
75 	struct rpc_auth		*auth;
76 	const struct rpc_authops *ops;
77 	u32			flavor = pseudoflavor_to_flavor(pseudoflavor);
78 
79 	auth = ERR_PTR(-EINVAL);
80 	if (flavor >= RPC_AUTH_MAXFLAVOR)
81 		goto out;
82 
83 #ifdef CONFIG_KMOD
84 	if ((ops = auth_flavors[flavor]) == NULL)
85 		request_module("rpc-auth-%u", flavor);
86 #endif
87 	spin_lock(&rpc_authflavor_lock);
88 	ops = auth_flavors[flavor];
89 	if (ops == NULL || !try_module_get(ops->owner)) {
90 		spin_unlock(&rpc_authflavor_lock);
91 		goto out;
92 	}
93 	spin_unlock(&rpc_authflavor_lock);
94 	auth = ops->create(clnt, pseudoflavor);
95 	module_put(ops->owner);
96 	if (IS_ERR(auth))
97 		return auth;
98 	if (clnt->cl_auth)
99 		rpcauth_release(clnt->cl_auth);
100 	clnt->cl_auth = auth;
101 
102 out:
103 	return auth;
104 }
105 
106 void
107 rpcauth_release(struct rpc_auth *auth)
108 {
109 	if (!atomic_dec_and_test(&auth->au_count))
110 		return;
111 	auth->au_ops->destroy(auth);
112 }
113 
114 static DEFINE_SPINLOCK(rpc_credcache_lock);
115 
116 static void
117 rpcauth_unhash_cred_locked(struct rpc_cred *cred)
118 {
119 	hlist_del_rcu(&cred->cr_hash);
120 	smp_mb__before_clear_bit();
121 	clear_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags);
122 }
123 
124 static void
125 rpcauth_unhash_cred(struct rpc_cred *cred)
126 {
127 	spinlock_t *cache_lock;
128 
129 	cache_lock = &cred->cr_auth->au_credcache->lock;
130 	spin_lock(cache_lock);
131 	if (atomic_read(&cred->cr_count) == 0)
132 		rpcauth_unhash_cred_locked(cred);
133 	spin_unlock(cache_lock);
134 }
135 
136 /*
137  * Initialize RPC credential cache
138  */
139 int
140 rpcauth_init_credcache(struct rpc_auth *auth)
141 {
142 	struct rpc_cred_cache *new;
143 	int i;
144 
145 	new = kmalloc(sizeof(*new), GFP_KERNEL);
146 	if (!new)
147 		return -ENOMEM;
148 	for (i = 0; i < RPC_CREDCACHE_NR; i++)
149 		INIT_HLIST_HEAD(&new->hashtable[i]);
150 	spin_lock_init(&new->lock);
151 	auth->au_credcache = new;
152 	return 0;
153 }
154 
155 /*
156  * Destroy a list of credentials
157  */
158 static inline
159 void rpcauth_destroy_credlist(struct list_head *head)
160 {
161 	struct rpc_cred *cred;
162 
163 	while (!list_empty(head)) {
164 		cred = list_entry(head->next, struct rpc_cred, cr_lru);
165 		list_del_init(&cred->cr_lru);
166 		put_rpccred(cred);
167 	}
168 }
169 
170 /*
171  * Clear the RPC credential cache, and delete those credentials
172  * that are not referenced.
173  */
174 void
175 rpcauth_clear_credcache(struct rpc_cred_cache *cache)
176 {
177 	LIST_HEAD(free);
178 	struct hlist_head *head;
179 	struct rpc_cred	*cred;
180 	int		i;
181 
182 	spin_lock(&rpc_credcache_lock);
183 	spin_lock(&cache->lock);
184 	for (i = 0; i < RPC_CREDCACHE_NR; i++) {
185 		head = &cache->hashtable[i];
186 		while (!hlist_empty(head)) {
187 			cred = hlist_entry(head->first, struct rpc_cred, cr_hash);
188 			get_rpccred(cred);
189 			if (!list_empty(&cred->cr_lru)) {
190 				list_del(&cred->cr_lru);
191 				number_cred_unused--;
192 			}
193 			list_add_tail(&cred->cr_lru, &free);
194 			rpcauth_unhash_cred_locked(cred);
195 		}
196 	}
197 	spin_unlock(&cache->lock);
198 	spin_unlock(&rpc_credcache_lock);
199 	rpcauth_destroy_credlist(&free);
200 }
201 
202 /*
203  * Destroy the RPC credential cache
204  */
205 void
206 rpcauth_destroy_credcache(struct rpc_auth *auth)
207 {
208 	struct rpc_cred_cache *cache = auth->au_credcache;
209 
210 	if (cache) {
211 		auth->au_credcache = NULL;
212 		rpcauth_clear_credcache(cache);
213 		kfree(cache);
214 	}
215 }
216 
217 /*
218  * Remove stale credentials. Avoid sleeping inside the loop.
219  */
220 static int
221 rpcauth_prune_expired(struct list_head *free, int nr_to_scan)
222 {
223 	spinlock_t *cache_lock;
224 	struct rpc_cred *cred;
225 
226 	while (!list_empty(&cred_unused)) {
227 		cred = list_entry(cred_unused.next, struct rpc_cred, cr_lru);
228 		list_del_init(&cred->cr_lru);
229 		number_cred_unused--;
230 		if (atomic_read(&cred->cr_count) != 0)
231 			continue;
232 		cache_lock = &cred->cr_auth->au_credcache->lock;
233 		spin_lock(cache_lock);
234 		if (atomic_read(&cred->cr_count) == 0) {
235 			get_rpccred(cred);
236 			list_add_tail(&cred->cr_lru, free);
237 			rpcauth_unhash_cred_locked(cred);
238 			nr_to_scan--;
239 		}
240 		spin_unlock(cache_lock);
241 		if (nr_to_scan == 0)
242 			break;
243 	}
244 	return nr_to_scan;
245 }
246 
247 /*
248  * Run memory cache shrinker.
249  */
250 static int
251 rpcauth_cache_shrinker(int nr_to_scan, gfp_t gfp_mask)
252 {
253 	LIST_HEAD(free);
254 	int res;
255 
256 	if (list_empty(&cred_unused))
257 		return 0;
258 	spin_lock(&rpc_credcache_lock);
259 	nr_to_scan = rpcauth_prune_expired(&free, nr_to_scan);
260 	res = (number_cred_unused / 100) * sysctl_vfs_cache_pressure;
261 	spin_unlock(&rpc_credcache_lock);
262 	rpcauth_destroy_credlist(&free);
263 	return res;
264 }
265 
266 /*
267  * Look up a process' credentials in the authentication cache
268  */
269 struct rpc_cred *
270 rpcauth_lookup_credcache(struct rpc_auth *auth, struct auth_cred * acred,
271 		int flags)
272 {
273 	LIST_HEAD(free);
274 	struct rpc_cred_cache *cache = auth->au_credcache;
275 	struct hlist_node *pos;
276 	struct rpc_cred	*cred = NULL,
277 			*entry, *new;
278 	int		nr = 0;
279 
280 	if (!(flags & RPCAUTH_LOOKUP_ROOTCREDS))
281 		nr = acred->uid & RPC_CREDCACHE_MASK;
282 
283 	rcu_read_lock();
284 	hlist_for_each_entry_rcu(entry, pos, &cache->hashtable[nr], cr_hash) {
285 		if (!entry->cr_ops->crmatch(acred, entry, flags))
286 			continue;
287 		spin_lock(&cache->lock);
288 		if (test_bit(RPCAUTH_CRED_HASHED, &entry->cr_flags) == 0) {
289 			spin_unlock(&cache->lock);
290 			continue;
291 		}
292 		cred = get_rpccred(entry);
293 		spin_unlock(&cache->lock);
294 		break;
295 	}
296 	rcu_read_unlock();
297 
298 	if (cred != NULL)
299 		goto found;
300 
301 	new = auth->au_ops->crcreate(auth, acred, flags);
302 	if (IS_ERR(new)) {
303 		cred = new;
304 		goto out;
305 	}
306 
307 	spin_lock(&cache->lock);
308 	hlist_for_each_entry(entry, pos, &cache->hashtable[nr], cr_hash) {
309 		if (!entry->cr_ops->crmatch(acred, entry, flags))
310 			continue;
311 		cred = get_rpccred(entry);
312 		break;
313 	}
314 	if (cred == NULL) {
315 		cred = new;
316 		set_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags);
317 		hlist_add_head_rcu(&cred->cr_hash, &cache->hashtable[nr]);
318 	} else
319 		list_add_tail(&new->cr_lru, &free);
320 	spin_unlock(&cache->lock);
321 found:
322 	if (test_bit(RPCAUTH_CRED_NEW, &cred->cr_flags)
323 			&& cred->cr_ops->cr_init != NULL
324 			&& !(flags & RPCAUTH_LOOKUP_NEW)) {
325 		int res = cred->cr_ops->cr_init(auth, cred);
326 		if (res < 0) {
327 			put_rpccred(cred);
328 			cred = ERR_PTR(res);
329 		}
330 	}
331 	rpcauth_destroy_credlist(&free);
332 out:
333 	return cred;
334 }
335 
336 struct rpc_cred *
337 rpcauth_lookupcred(struct rpc_auth *auth, int flags)
338 {
339 	struct auth_cred acred = {
340 		.uid = current->fsuid,
341 		.gid = current->fsgid,
342 		.group_info = current->group_info,
343 	};
344 	struct rpc_cred *ret;
345 
346 	dprintk("RPC:       looking up %s cred\n",
347 		auth->au_ops->au_name);
348 	get_group_info(acred.group_info);
349 	ret = auth->au_ops->lookup_cred(auth, &acred, flags);
350 	put_group_info(acred.group_info);
351 	return ret;
352 }
353 
354 void
355 rpcauth_init_cred(struct rpc_cred *cred, const struct auth_cred *acred,
356 		  struct rpc_auth *auth, const struct rpc_credops *ops)
357 {
358 	INIT_HLIST_NODE(&cred->cr_hash);
359 	INIT_LIST_HEAD(&cred->cr_lru);
360 	atomic_set(&cred->cr_count, 1);
361 	cred->cr_auth = auth;
362 	cred->cr_ops = ops;
363 	cred->cr_expire = jiffies;
364 #ifdef RPC_DEBUG
365 	cred->cr_magic = RPCAUTH_CRED_MAGIC;
366 #endif
367 	cred->cr_uid = acred->uid;
368 }
369 EXPORT_SYMBOL(rpcauth_init_cred);
370 
371 struct rpc_cred *
372 rpcauth_bindcred(struct rpc_task *task)
373 {
374 	struct rpc_auth *auth = task->tk_client->cl_auth;
375 	struct auth_cred acred = {
376 		.uid = current->fsuid,
377 		.gid = current->fsgid,
378 		.group_info = current->group_info,
379 	};
380 	struct rpc_cred *ret;
381 	int flags = 0;
382 
383 	dprintk("RPC: %5u looking up %s cred\n",
384 		task->tk_pid, task->tk_client->cl_auth->au_ops->au_name);
385 	get_group_info(acred.group_info);
386 	if (task->tk_flags & RPC_TASK_ROOTCREDS)
387 		flags |= RPCAUTH_LOOKUP_ROOTCREDS;
388 	ret = auth->au_ops->lookup_cred(auth, &acred, flags);
389 	if (!IS_ERR(ret))
390 		task->tk_msg.rpc_cred = ret;
391 	else
392 		task->tk_status = PTR_ERR(ret);
393 	put_group_info(acred.group_info);
394 	return ret;
395 }
396 
397 void
398 rpcauth_holdcred(struct rpc_task *task)
399 {
400 	struct rpc_cred *cred = task->tk_msg.rpc_cred;
401 	if (cred != NULL) {
402 		get_rpccred(cred);
403 		dprintk("RPC: %5u holding %s cred %p\n", task->tk_pid,
404 				cred->cr_auth->au_ops->au_name, cred);
405 	}
406 }
407 
408 void
409 put_rpccred(struct rpc_cred *cred)
410 {
411 	/* Fast path for unhashed credentials */
412 	if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0)
413 		goto need_lock;
414 
415 	if (!atomic_dec_and_test(&cred->cr_count))
416 		return;
417 	goto out_destroy;
418 need_lock:
419 	if (!atomic_dec_and_lock(&cred->cr_count, &rpc_credcache_lock))
420 		return;
421 	if (!list_empty(&cred->cr_lru)) {
422 		number_cred_unused--;
423 		list_del_init(&cred->cr_lru);
424 	}
425 	if (test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) == 0)
426 		rpcauth_unhash_cred(cred);
427 	else if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0) {
428 		cred->cr_expire = jiffies;
429 		list_add_tail(&cred->cr_lru, &cred_unused);
430 		number_cred_unused++;
431 		spin_unlock(&rpc_credcache_lock);
432 		return;
433 	}
434 	spin_unlock(&rpc_credcache_lock);
435 out_destroy:
436 	cred->cr_ops->crdestroy(cred);
437 }
438 
439 void
440 rpcauth_unbindcred(struct rpc_task *task)
441 {
442 	struct rpc_cred	*cred = task->tk_msg.rpc_cred;
443 
444 	dprintk("RPC: %5u releasing %s cred %p\n",
445 		task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
446 
447 	put_rpccred(cred);
448 	task->tk_msg.rpc_cred = NULL;
449 }
450 
451 __be32 *
452 rpcauth_marshcred(struct rpc_task *task, __be32 *p)
453 {
454 	struct rpc_cred	*cred = task->tk_msg.rpc_cred;
455 
456 	dprintk("RPC: %5u marshaling %s cred %p\n",
457 		task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
458 
459 	return cred->cr_ops->crmarshal(task, p);
460 }
461 
462 __be32 *
463 rpcauth_checkverf(struct rpc_task *task, __be32 *p)
464 {
465 	struct rpc_cred	*cred = task->tk_msg.rpc_cred;
466 
467 	dprintk("RPC: %5u validating %s cred %p\n",
468 		task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
469 
470 	return cred->cr_ops->crvalidate(task, p);
471 }
472 
473 int
474 rpcauth_wrap_req(struct rpc_task *task, kxdrproc_t encode, void *rqstp,
475 		__be32 *data, void *obj)
476 {
477 	struct rpc_cred *cred = task->tk_msg.rpc_cred;
478 
479 	dprintk("RPC: %5u using %s cred %p to wrap rpc data\n",
480 			task->tk_pid, cred->cr_ops->cr_name, cred);
481 	if (cred->cr_ops->crwrap_req)
482 		return cred->cr_ops->crwrap_req(task, encode, rqstp, data, obj);
483 	/* By default, we encode the arguments normally. */
484 	return rpc_call_xdrproc(encode, rqstp, data, obj);
485 }
486 
487 int
488 rpcauth_unwrap_resp(struct rpc_task *task, kxdrproc_t decode, void *rqstp,
489 		__be32 *data, void *obj)
490 {
491 	struct rpc_cred *cred = task->tk_msg.rpc_cred;
492 
493 	dprintk("RPC: %5u using %s cred %p to unwrap rpc data\n",
494 			task->tk_pid, cred->cr_ops->cr_name, cred);
495 	if (cred->cr_ops->crunwrap_resp)
496 		return cred->cr_ops->crunwrap_resp(task, decode, rqstp,
497 						   data, obj);
498 	/* By default, we decode the arguments normally. */
499 	return rpc_call_xdrproc(decode, rqstp, data, obj);
500 }
501 
502 int
503 rpcauth_refreshcred(struct rpc_task *task)
504 {
505 	struct rpc_cred	*cred = task->tk_msg.rpc_cred;
506 	int err;
507 
508 	dprintk("RPC: %5u refreshing %s cred %p\n",
509 		task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
510 
511 	err = cred->cr_ops->crrefresh(task);
512 	if (err < 0)
513 		task->tk_status = err;
514 	return err;
515 }
516 
517 void
518 rpcauth_invalcred(struct rpc_task *task)
519 {
520 	struct rpc_cred *cred = task->tk_msg.rpc_cred;
521 
522 	dprintk("RPC: %5u invalidating %s cred %p\n",
523 		task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
524 	if (cred)
525 		clear_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
526 }
527 
528 int
529 rpcauth_uptodatecred(struct rpc_task *task)
530 {
531 	struct rpc_cred *cred = task->tk_msg.rpc_cred;
532 
533 	return cred == NULL ||
534 		test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0;
535 }
536 
537 static struct shrinker rpc_cred_shrinker = {
538 	.shrink = rpcauth_cache_shrinker,
539 	.seeks = DEFAULT_SEEKS,
540 };
541 
542 void __init rpcauth_init_module(void)
543 {
544 	rpc_init_authunix();
545 	register_shrinker(&rpc_cred_shrinker);
546 }
547 
548 void __exit rpcauth_remove_module(void)
549 {
550 	unregister_shrinker(&rpc_cred_shrinker);
551 }
552