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