c40856f589f03f0583ada299251f56c61dd9cb30
[linux-3.10.git] / net / sunrpc / auth.c
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                 /*
240                  * Enforce a 60 second garbage collection moratorium
241                  * Note that the cred_unused list must be time-ordered.
242                  */
243                 if (time_in_range(cred->cr_expire, expired, jiffies) &&
244                     test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0)
245                         return 0;
246
247                 list_del_init(&cred->cr_lru);
248                 number_cred_unused--;
249                 if (atomic_read(&cred->cr_count) != 0)
250                         continue;
251
252                 cache_lock = &cred->cr_auth->au_credcache->lock;
253                 spin_lock(cache_lock);
254                 if (atomic_read(&cred->cr_count) == 0) {
255                         get_rpccred(cred);
256                         list_add_tail(&cred->cr_lru, free);
257                         rpcauth_unhash_cred_locked(cred);
258                         nr_to_scan--;
259                 }
260                 spin_unlock(cache_lock);
261                 if (nr_to_scan == 0)
262                         break;
263         }
264         return (number_cred_unused / 100) * sysctl_vfs_cache_pressure;
265 }
266
267 /*
268  * Run memory cache shrinker.
269  */
270 static int
271 rpcauth_cache_shrinker(int nr_to_scan, gfp_t gfp_mask)
272 {
273         LIST_HEAD(free);
274         int res;
275
276         if ((gfp_mask & GFP_KERNEL) != GFP_KERNEL)
277                 return (nr_to_scan == 0) ? 0 : -1;
278         if (list_empty(&cred_unused))
279                 return 0;
280         spin_lock(&rpc_credcache_lock);
281         res = rpcauth_prune_expired(&free, nr_to_scan);
282         spin_unlock(&rpc_credcache_lock);
283         rpcauth_destroy_credlist(&free);
284         return res;
285 }
286
287 /*
288  * Look up a process' credentials in the authentication cache
289  */
290 struct rpc_cred *
291 rpcauth_lookup_credcache(struct rpc_auth *auth, struct auth_cred * acred,
292                 int flags)
293 {
294         LIST_HEAD(free);
295         struct rpc_cred_cache *cache = auth->au_credcache;
296         struct hlist_node *pos;
297         struct rpc_cred *cred = NULL,
298                         *entry, *new;
299         unsigned int nr;
300
301         nr = hash_long(acred->uid, RPC_CREDCACHE_HASHBITS);
302
303         rcu_read_lock();
304         hlist_for_each_entry_rcu(entry, pos, &cache->hashtable[nr], cr_hash) {
305                 if (!entry->cr_ops->crmatch(acred, entry, flags))
306                         continue;
307                 spin_lock(&cache->lock);
308                 if (test_bit(RPCAUTH_CRED_HASHED, &entry->cr_flags) == 0) {
309                         spin_unlock(&cache->lock);
310                         continue;
311                 }
312                 cred = get_rpccred(entry);
313                 spin_unlock(&cache->lock);
314                 break;
315         }
316         rcu_read_unlock();
317
318         if (cred != NULL)
319                 goto found;
320
321         new = auth->au_ops->crcreate(auth, acred, flags);
322         if (IS_ERR(new)) {
323                 cred = new;
324                 goto out;
325         }
326
327         spin_lock(&cache->lock);
328         hlist_for_each_entry(entry, pos, &cache->hashtable[nr], cr_hash) {
329                 if (!entry->cr_ops->crmatch(acred, entry, flags))
330                         continue;
331                 cred = get_rpccred(entry);
332                 break;
333         }
334         if (cred == NULL) {
335                 cred = new;
336                 set_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags);
337                 hlist_add_head_rcu(&cred->cr_hash, &cache->hashtable[nr]);
338         } else
339                 list_add_tail(&new->cr_lru, &free);
340         spin_unlock(&cache->lock);
341 found:
342         if (test_bit(RPCAUTH_CRED_NEW, &cred->cr_flags) &&
343             cred->cr_ops->cr_init != NULL &&
344             !(flags & RPCAUTH_LOOKUP_NEW)) {
345                 int res = cred->cr_ops->cr_init(auth, cred);
346                 if (res < 0) {
347                         put_rpccred(cred);
348                         cred = ERR_PTR(res);
349                 }
350         }
351         rpcauth_destroy_credlist(&free);
352 out:
353         return cred;
354 }
355 EXPORT_SYMBOL_GPL(rpcauth_lookup_credcache);
356
357 struct rpc_cred *
358 rpcauth_lookupcred(struct rpc_auth *auth, int flags)
359 {
360         struct auth_cred acred;
361         struct rpc_cred *ret;
362         const struct cred *cred = current_cred();
363
364         dprintk("RPC:       looking up %s cred\n",
365                 auth->au_ops->au_name);
366
367         memset(&acred, 0, sizeof(acred));
368         acred.uid = cred->fsuid;
369         acred.gid = cred->fsgid;
370         acred.group_info = get_group_info(((struct cred *)cred)->group_info);
371
372         ret = auth->au_ops->lookup_cred(auth, &acred, flags);
373         put_group_info(acred.group_info);
374         return ret;
375 }
376
377 void
378 rpcauth_init_cred(struct rpc_cred *cred, const struct auth_cred *acred,
379                   struct rpc_auth *auth, const struct rpc_credops *ops)
380 {
381         INIT_HLIST_NODE(&cred->cr_hash);
382         INIT_LIST_HEAD(&cred->cr_lru);
383         atomic_set(&cred->cr_count, 1);
384         cred->cr_auth = auth;
385         cred->cr_ops = ops;
386         cred->cr_expire = jiffies;
387 #ifdef RPC_DEBUG
388         cred->cr_magic = RPCAUTH_CRED_MAGIC;
389 #endif
390         cred->cr_uid = acred->uid;
391 }
392 EXPORT_SYMBOL_GPL(rpcauth_init_cred);
393
394 void
395 rpcauth_generic_bind_cred(struct rpc_task *task, struct rpc_cred *cred, int lookupflags)
396 {
397         task->tk_msg.rpc_cred = get_rpccred(cred);
398         dprintk("RPC: %5u holding %s cred %p\n", task->tk_pid,
399                         cred->cr_auth->au_ops->au_name, cred);
400 }
401 EXPORT_SYMBOL_GPL(rpcauth_generic_bind_cred);
402
403 static void
404 rpcauth_bind_root_cred(struct rpc_task *task, int lookupflags)
405 {
406         struct rpc_auth *auth = task->tk_client->cl_auth;
407         struct auth_cred acred = {
408                 .uid = 0,
409                 .gid = 0,
410         };
411         struct rpc_cred *ret;
412
413         dprintk("RPC: %5u looking up %s cred\n",
414                 task->tk_pid, task->tk_client->cl_auth->au_ops->au_name);
415         ret = auth->au_ops->lookup_cred(auth, &acred, lookupflags);
416         if (!IS_ERR(ret))
417                 task->tk_msg.rpc_cred = ret;
418         else
419                 task->tk_status = PTR_ERR(ret);
420 }
421
422 static void
423 rpcauth_bind_new_cred(struct rpc_task *task, int lookupflags)
424 {
425         struct rpc_auth *auth = task->tk_client->cl_auth;
426         struct rpc_cred *ret;
427
428         dprintk("RPC: %5u looking up %s cred\n",
429                 task->tk_pid, auth->au_ops->au_name);
430         ret = rpcauth_lookupcred(auth, lookupflags);
431         if (!IS_ERR(ret))
432                 task->tk_msg.rpc_cred = ret;
433         else
434                 task->tk_status = PTR_ERR(ret);
435 }
436
437 void
438 rpcauth_bindcred(struct rpc_task *task, struct rpc_cred *cred, int flags)
439 {
440         int lookupflags = 0;
441
442         if (flags & RPC_TASK_ASYNC)
443                 lookupflags |= RPCAUTH_LOOKUP_NEW;
444         if (cred != NULL)
445                 cred->cr_ops->crbind(task, cred, lookupflags);
446         else if (flags & RPC_TASK_ROOTCREDS)
447                 rpcauth_bind_root_cred(task, lookupflags);
448         else
449                 rpcauth_bind_new_cred(task, lookupflags);
450 }
451
452 void
453 put_rpccred(struct rpc_cred *cred)
454 {
455         /* Fast path for unhashed credentials */
456         if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) == 0) {
457                 if (atomic_dec_and_test(&cred->cr_count))
458                         cred->cr_ops->crdestroy(cred);
459                 return;
460         }
461
462         if (!atomic_dec_and_lock(&cred->cr_count, &rpc_credcache_lock))
463                 return;
464         if (!list_empty(&cred->cr_lru)) {
465                 number_cred_unused--;
466                 list_del_init(&cred->cr_lru);
467         }
468         if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0) {
469                 if (test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0) {
470                         cred->cr_expire = jiffies;
471                         list_add_tail(&cred->cr_lru, &cred_unused);
472                         number_cred_unused++;
473                         goto out_nodestroy;
474                 }
475                 if (!rpcauth_unhash_cred(cred)) {
476                         /* We were hashed and someone looked us up... */
477                         goto out_nodestroy;
478                 }
479         }
480         spin_unlock(&rpc_credcache_lock);
481         cred->cr_ops->crdestroy(cred);
482         return;
483 out_nodestroy:
484         spin_unlock(&rpc_credcache_lock);
485 }
486 EXPORT_SYMBOL_GPL(put_rpccred);
487
488 void
489 rpcauth_unbindcred(struct rpc_task *task)
490 {
491         struct rpc_cred *cred = task->tk_msg.rpc_cred;
492
493         dprintk("RPC: %5u releasing %s cred %p\n",
494                 task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
495
496         put_rpccred(cred);
497         task->tk_msg.rpc_cred = NULL;
498 }
499
500 __be32 *
501 rpcauth_marshcred(struct rpc_task *task, __be32 *p)
502 {
503         struct rpc_cred *cred = task->tk_msg.rpc_cred;
504
505         dprintk("RPC: %5u marshaling %s cred %p\n",
506                 task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
507
508         return cred->cr_ops->crmarshal(task, p);
509 }
510
511 __be32 *
512 rpcauth_checkverf(struct rpc_task *task, __be32 *p)
513 {
514         struct rpc_cred *cred = task->tk_msg.rpc_cred;
515
516         dprintk("RPC: %5u validating %s cred %p\n",
517                 task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
518
519         return cred->cr_ops->crvalidate(task, p);
520 }
521
522 int
523 rpcauth_wrap_req(struct rpc_task *task, kxdrproc_t encode, void *rqstp,
524                 __be32 *data, void *obj)
525 {
526         struct rpc_cred *cred = task->tk_msg.rpc_cred;
527
528         dprintk("RPC: %5u using %s cred %p to wrap rpc data\n",
529                         task->tk_pid, cred->cr_ops->cr_name, cred);
530         if (cred->cr_ops->crwrap_req)
531                 return cred->cr_ops->crwrap_req(task, encode, rqstp, data, obj);
532         /* By default, we encode the arguments normally. */
533         return encode(rqstp, data, obj);
534 }
535
536 int
537 rpcauth_unwrap_resp(struct rpc_task *task, kxdrproc_t decode, void *rqstp,
538                 __be32 *data, void *obj)
539 {
540         struct rpc_cred *cred = task->tk_msg.rpc_cred;
541
542         dprintk("RPC: %5u using %s cred %p to unwrap rpc data\n",
543                         task->tk_pid, cred->cr_ops->cr_name, cred);
544         if (cred->cr_ops->crunwrap_resp)
545                 return cred->cr_ops->crunwrap_resp(task, decode, rqstp,
546                                                    data, obj);
547         /* By default, we decode the arguments normally. */
548         return decode(rqstp, data, obj);
549 }
550
551 int
552 rpcauth_refreshcred(struct rpc_task *task)
553 {
554         struct rpc_cred *cred = task->tk_msg.rpc_cred;
555         int err;
556
557         dprintk("RPC: %5u refreshing %s cred %p\n",
558                 task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
559
560         err = cred->cr_ops->crrefresh(task);
561         if (err < 0)
562                 task->tk_status = err;
563         return err;
564 }
565
566 void
567 rpcauth_invalcred(struct rpc_task *task)
568 {
569         struct rpc_cred *cred = task->tk_msg.rpc_cred;
570
571         dprintk("RPC: %5u invalidating %s cred %p\n",
572                 task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
573         if (cred)
574                 clear_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
575 }
576
577 int
578 rpcauth_uptodatecred(struct rpc_task *task)
579 {
580         struct rpc_cred *cred = task->tk_msg.rpc_cred;
581
582         return cred == NULL ||
583                 test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0;
584 }
585
586 static struct shrinker rpc_cred_shrinker = {
587         .shrink = rpcauth_cache_shrinker,
588         .seeks = DEFAULT_SEEKS,
589 };
590
591 void __init rpcauth_init_module(void)
592 {
593         rpc_init_authunix();
594         rpc_init_generic_auth();
595         register_shrinker(&rpc_cred_shrinker);
596 }
597
598 void __exit rpcauth_remove_module(void)
599 {
600         unregister_shrinker(&rpc_cred_shrinker);
601 }