SUNRPC: Convert the credential garbage collector into a shrinker callback
[linux-2.6.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/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_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_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         dprintk("RPC: %5u holding %s cred %p\n",
401                 task->tk_pid, task->tk_auth->au_ops->au_name,
402                 task->tk_msg.rpc_cred);
403         if (task->tk_msg.rpc_cred)
404                 get_rpccred(task->tk_msg.rpc_cred);
405 }
406
407 void
408 put_rpccred(struct rpc_cred *cred)
409 {
410         /* Fast path for unhashed credentials */
411         if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0)
412                 goto need_lock;
413
414         if (!atomic_dec_and_test(&cred->cr_count))
415                 return;
416         goto out_destroy;
417 need_lock:
418         if (!atomic_dec_and_lock(&cred->cr_count, &rpc_credcache_lock))
419                 return;
420         if (!list_empty(&cred->cr_lru)) {
421                 number_cred_unused--;
422                 list_del_init(&cred->cr_lru);
423         }
424         if (test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) == 0)
425                 rpcauth_unhash_cred(cred);
426         else if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0) {
427                 cred->cr_expire = jiffies;
428                 list_add_tail(&cred->cr_lru, &cred_unused);
429                 number_cred_unused++;
430                 spin_unlock(&rpc_credcache_lock);
431                 return;
432         }
433         spin_unlock(&rpc_credcache_lock);
434 out_destroy:
435         cred->cr_ops->crdestroy(cred);
436 }
437
438 void
439 rpcauth_unbindcred(struct rpc_task *task)
440 {
441         struct rpc_cred *cred = task->tk_msg.rpc_cred;
442
443         dprintk("RPC: %5u releasing %s cred %p\n",
444                 task->tk_pid, task->tk_auth->au_ops->au_name, cred);
445
446         put_rpccred(cred);
447         task->tk_msg.rpc_cred = NULL;
448 }
449
450 __be32 *
451 rpcauth_marshcred(struct rpc_task *task, __be32 *p)
452 {
453         struct rpc_cred *cred = task->tk_msg.rpc_cred;
454
455         dprintk("RPC: %5u marshaling %s cred %p\n",
456                 task->tk_pid, task->tk_auth->au_ops->au_name, cred);
457
458         return cred->cr_ops->crmarshal(task, p);
459 }
460
461 __be32 *
462 rpcauth_checkverf(struct rpc_task *task, __be32 *p)
463 {
464         struct rpc_cred *cred = task->tk_msg.rpc_cred;
465
466         dprintk("RPC: %5u validating %s cred %p\n",
467                 task->tk_pid, task->tk_auth->au_ops->au_name, cred);
468
469         return cred->cr_ops->crvalidate(task, p);
470 }
471
472 int
473 rpcauth_wrap_req(struct rpc_task *task, kxdrproc_t encode, void *rqstp,
474                 __be32 *data, void *obj)
475 {
476         struct rpc_cred *cred = task->tk_msg.rpc_cred;
477
478         dprintk("RPC: %5u using %s cred %p to wrap rpc data\n",
479                         task->tk_pid, cred->cr_ops->cr_name, cred);
480         if (cred->cr_ops->crwrap_req)
481                 return cred->cr_ops->crwrap_req(task, encode, rqstp, data, obj);
482         /* By default, we encode the arguments normally. */
483         return encode(rqstp, data, obj);
484 }
485
486 int
487 rpcauth_unwrap_resp(struct rpc_task *task, kxdrproc_t decode, void *rqstp,
488                 __be32 *data, void *obj)
489 {
490         struct rpc_cred *cred = task->tk_msg.rpc_cred;
491
492         dprintk("RPC: %5u using %s cred %p to unwrap rpc data\n",
493                         task->tk_pid, cred->cr_ops->cr_name, cred);
494         if (cred->cr_ops->crunwrap_resp)
495                 return cred->cr_ops->crunwrap_resp(task, decode, rqstp,
496                                                    data, obj);
497         /* By default, we decode the arguments normally. */
498         return decode(rqstp, data, obj);
499 }
500
501 int
502 rpcauth_refreshcred(struct rpc_task *task)
503 {
504         struct rpc_cred *cred = task->tk_msg.rpc_cred;
505         int err;
506
507         dprintk("RPC: %5u refreshing %s cred %p\n",
508                 task->tk_pid, task->tk_auth->au_ops->au_name, cred);
509
510         err = cred->cr_ops->crrefresh(task);
511         if (err < 0)
512                 task->tk_status = err;
513         return err;
514 }
515
516 void
517 rpcauth_invalcred(struct rpc_task *task)
518 {
519         struct rpc_cred *cred = task->tk_msg.rpc_cred;
520
521         dprintk("RPC: %5u invalidating %s cred %p\n",
522                 task->tk_pid, task->tk_auth->au_ops->au_name, cred);
523         if (cred)
524                 clear_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
525 }
526
527 int
528 rpcauth_uptodatecred(struct rpc_task *task)
529 {
530         struct rpc_cred *cred = task->tk_msg.rpc_cred;
531
532         return cred == NULL ||
533                 test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0;
534 }
535
536
537 static struct shrinker *rpc_cred_shrinker;
538
539 void __init rpcauth_init_module(void)
540 {
541         rpc_init_authunix();
542         rpc_cred_shrinker = set_shrinker(DEFAULT_SEEKS, rpcauth_cache_shrinker);
543 }
544
545 void __exit rpcauth_remove_module(void)
546 {
547         if (rpc_cred_shrinker != NULL)
548                 remove_shrinker(rpc_cred_shrinker);
549 }