SUNRPC: Convert the credcache lookup code to use RCU
[linux-2.6] / 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 /*
124  * Initialize RPC credential cache
125  */
126 int
127 rpcauth_init_credcache(struct rpc_auth *auth, unsigned long expire)
128 {
129         struct rpc_cred_cache *new;
130         int i;
131
132         new = kmalloc(sizeof(*new), GFP_KERNEL);
133         if (!new)
134                 return -ENOMEM;
135         for (i = 0; i < RPC_CREDCACHE_NR; i++)
136                 INIT_HLIST_HEAD(&new->hashtable[i]);
137         new->expire = expire;
138         new->nextgc = jiffies + (expire >> 1);
139         auth->au_credcache = new;
140         return 0;
141 }
142
143 /*
144  * Destroy a list of credentials
145  */
146 static inline
147 void rpcauth_destroy_credlist(struct list_head *head)
148 {
149         struct rpc_cred *cred;
150
151         while (!list_empty(head)) {
152                 cred = list_entry(head->next, struct rpc_cred, cr_lru);
153                 list_del_init(&cred->cr_lru);
154                 put_rpccred(cred);
155         }
156 }
157
158 /*
159  * Clear the RPC credential cache, and delete those credentials
160  * that are not referenced.
161  */
162 void
163 rpcauth_clear_credcache(struct rpc_cred_cache *cache)
164 {
165         LIST_HEAD(free);
166         struct hlist_head *head;
167         struct rpc_cred *cred;
168         int             i;
169
170         spin_lock(&rpc_credcache_lock);
171         for (i = 0; i < RPC_CREDCACHE_NR; i++) {
172                 head = &cache->hashtable[i];
173                 while (!hlist_empty(head)) {
174                         cred = hlist_entry(head->first, struct rpc_cred, cr_hash);
175                         get_rpccred(cred);
176                         list_move_tail(&cred->cr_lru, &free);
177                         rpcauth_unhash_cred_locked(cred);
178                 }
179         }
180         spin_unlock(&rpc_credcache_lock);
181         rpcauth_destroy_credlist(&free);
182 }
183
184 /*
185  * Destroy the RPC credential cache
186  */
187 void
188 rpcauth_destroy_credcache(struct rpc_auth *auth)
189 {
190         struct rpc_cred_cache *cache = auth->au_credcache;
191
192         if (cache) {
193                 auth->au_credcache = NULL;
194                 rpcauth_clear_credcache(cache);
195                 kfree(cache);
196         }
197 }
198
199 /*
200  * Remove stale credentials. Avoid sleeping inside the loop.
201  */
202 static void
203 rpcauth_prune_expired(struct list_head *free)
204 {
205         struct rpc_cred *cred;
206
207         while (!list_empty(&cred_unused)) {
208                 cred = list_entry(cred_unused.next, struct rpc_cred, cr_lru);
209                 if (time_after(jiffies, cred->cr_expire +
210                                         cred->cr_auth->au_credcache->expire))
211                         break;
212                 list_del_init(&cred->cr_lru);
213                 if (atomic_read(&cred->cr_count) != 0)
214                         continue;
215                 get_rpccred(cred);
216                 list_add_tail(&cred->cr_lru, free);
217                 rpcauth_unhash_cred_locked(cred);
218         }
219 }
220
221 /*
222  * Run garbage collector.
223  */
224 static void
225 rpcauth_gc_credcache(struct rpc_cred_cache *cache, struct list_head *free)
226 {
227         if (list_empty(&cred_unused) || time_before(jiffies, cache->nextgc))
228                 return;
229         spin_lock(&rpc_credcache_lock);
230         cache->nextgc = jiffies + cache->expire;
231         rpcauth_prune_expired(free);
232         spin_unlock(&rpc_credcache_lock);
233 }
234
235 /*
236  * Look up a process' credentials in the authentication cache
237  */
238 struct rpc_cred *
239 rpcauth_lookup_credcache(struct rpc_auth *auth, struct auth_cred * acred,
240                 int flags)
241 {
242         LIST_HEAD(free);
243         struct rpc_cred_cache *cache = auth->au_credcache;
244         struct hlist_node *pos;
245         struct rpc_cred *cred = NULL,
246                         *entry, *new;
247         int             nr = 0;
248
249         if (!(flags & RPCAUTH_LOOKUP_ROOTCREDS))
250                 nr = acred->uid & RPC_CREDCACHE_MASK;
251
252         rcu_read_lock();
253         hlist_for_each_entry_rcu(entry, pos, &cache->hashtable[nr], cr_hash) {
254                 if (!entry->cr_ops->crmatch(acred, entry, flags))
255                         continue;
256                 spin_lock(&rpc_credcache_lock);
257                 if (test_bit(RPCAUTH_CRED_HASHED, &entry->cr_flags) == 0) {
258                         spin_unlock(&rpc_credcache_lock);
259                         continue;
260                 }
261                 cred = get_rpccred(entry);
262                 spin_unlock(&rpc_credcache_lock);
263                 break;
264         }
265         rcu_read_unlock();
266
267         if (cred != NULL) {
268                 rpcauth_gc_credcache(cache, &free);
269                 goto found;
270         }
271
272         new = auth->au_ops->crcreate(auth, acred, flags);
273         if (IS_ERR(new)) {
274                 cred = new;
275                 goto out;
276         }
277
278         spin_lock(&rpc_credcache_lock);
279         hlist_for_each_entry(entry, pos, &cache->hashtable[nr], cr_hash) {
280                 if (!entry->cr_ops->crmatch(acred, entry, flags))
281                         continue;
282                 cred = get_rpccred(entry);
283                 break;
284         }
285         if (cred == NULL) {
286                 cred = new;
287                 set_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags);
288                 hlist_add_head_rcu(&cred->cr_hash, &cache->hashtable[nr]);
289         } else
290                 list_add_tail(&new->cr_lru, &free);
291         rpcauth_prune_expired(&free);
292         cache->nextgc = jiffies + cache->expire;
293         spin_unlock(&rpc_credcache_lock);
294 found:
295         if (test_bit(RPCAUTH_CRED_NEW, &cred->cr_flags)
296                         && cred->cr_ops->cr_init != NULL
297                         && !(flags & RPCAUTH_LOOKUP_NEW)) {
298                 int res = cred->cr_ops->cr_init(auth, cred);
299                 if (res < 0) {
300                         put_rpccred(cred);
301                         cred = ERR_PTR(res);
302                 }
303         }
304         rpcauth_destroy_credlist(&free);
305 out:
306         return cred;
307 }
308
309 struct rpc_cred *
310 rpcauth_lookupcred(struct rpc_auth *auth, int flags)
311 {
312         struct auth_cred acred = {
313                 .uid = current->fsuid,
314                 .gid = current->fsgid,
315                 .group_info = current->group_info,
316         };
317         struct rpc_cred *ret;
318
319         dprintk("RPC:       looking up %s cred\n",
320                 auth->au_ops->au_name);
321         get_group_info(acred.group_info);
322         ret = auth->au_ops->lookup_cred(auth, &acred, flags);
323         put_group_info(acred.group_info);
324         return ret;
325 }
326
327 void
328 rpcauth_init_cred(struct rpc_cred *cred, const struct auth_cred *acred,
329                   struct rpc_auth *auth, const struct rpc_credops *ops)
330 {
331         INIT_HLIST_NODE(&cred->cr_hash);
332         INIT_LIST_HEAD(&cred->cr_lru);
333         atomic_set(&cred->cr_count, 1);
334         cred->cr_auth = auth;
335         cred->cr_ops = ops;
336         cred->cr_expire = jiffies;
337 #ifdef RPC_DEBUG
338         cred->cr_magic = RPCAUTH_CRED_MAGIC;
339 #endif
340         cred->cr_uid = acred->uid;
341 }
342 EXPORT_SYMBOL(rpcauth_init_cred);
343
344 struct rpc_cred *
345 rpcauth_bindcred(struct rpc_task *task)
346 {
347         struct rpc_auth *auth = task->tk_auth;
348         struct auth_cred acred = {
349                 .uid = current->fsuid,
350                 .gid = current->fsgid,
351                 .group_info = current->group_info,
352         };
353         struct rpc_cred *ret;
354         int flags = 0;
355
356         dprintk("RPC: %5u looking up %s cred\n",
357                 task->tk_pid, task->tk_auth->au_ops->au_name);
358         get_group_info(acred.group_info);
359         if (task->tk_flags & RPC_TASK_ROOTCREDS)
360                 flags |= RPCAUTH_LOOKUP_ROOTCREDS;
361         ret = auth->au_ops->lookup_cred(auth, &acred, flags);
362         if (!IS_ERR(ret))
363                 task->tk_msg.rpc_cred = ret;
364         else
365                 task->tk_status = PTR_ERR(ret);
366         put_group_info(acred.group_info);
367         return ret;
368 }
369
370 void
371 rpcauth_holdcred(struct rpc_task *task)
372 {
373         dprintk("RPC: %5u holding %s cred %p\n",
374                 task->tk_pid, task->tk_auth->au_ops->au_name,
375                 task->tk_msg.rpc_cred);
376         if (task->tk_msg.rpc_cred)
377                 get_rpccred(task->tk_msg.rpc_cred);
378 }
379
380 void
381 put_rpccred(struct rpc_cred *cred)
382 {
383         /* Fast path for unhashed credentials */
384         if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0)
385                 goto need_lock;
386
387         if (!atomic_dec_and_test(&cred->cr_count))
388                 return;
389         goto out_destroy;
390 need_lock:
391         if (!atomic_dec_and_lock(&cred->cr_count, &rpc_credcache_lock))
392                 return;
393         if (!list_empty(&cred->cr_lru))
394                 list_del_init(&cred->cr_lru);
395         if (test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) == 0)
396                 rpcauth_unhash_cred_locked(cred);
397         else if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0) {
398                 cred->cr_expire = jiffies;
399                 list_add_tail(&cred->cr_lru, &cred_unused);
400                 spin_unlock(&rpc_credcache_lock);
401                 return;
402         }
403         spin_unlock(&rpc_credcache_lock);
404 out_destroy:
405         cred->cr_ops->crdestroy(cred);
406 }
407
408 void
409 rpcauth_unbindcred(struct rpc_task *task)
410 {
411         struct rpc_cred *cred = task->tk_msg.rpc_cred;
412
413         dprintk("RPC: %5u releasing %s cred %p\n",
414                 task->tk_pid, task->tk_auth->au_ops->au_name, cred);
415
416         put_rpccred(cred);
417         task->tk_msg.rpc_cred = NULL;
418 }
419
420 __be32 *
421 rpcauth_marshcred(struct rpc_task *task, __be32 *p)
422 {
423         struct rpc_cred *cred = task->tk_msg.rpc_cred;
424
425         dprintk("RPC: %5u marshaling %s cred %p\n",
426                 task->tk_pid, task->tk_auth->au_ops->au_name, cred);
427
428         return cred->cr_ops->crmarshal(task, p);
429 }
430
431 __be32 *
432 rpcauth_checkverf(struct rpc_task *task, __be32 *p)
433 {
434         struct rpc_cred *cred = task->tk_msg.rpc_cred;
435
436         dprintk("RPC: %5u validating %s cred %p\n",
437                 task->tk_pid, task->tk_auth->au_ops->au_name, cred);
438
439         return cred->cr_ops->crvalidate(task, p);
440 }
441
442 int
443 rpcauth_wrap_req(struct rpc_task *task, kxdrproc_t encode, void *rqstp,
444                 __be32 *data, void *obj)
445 {
446         struct rpc_cred *cred = task->tk_msg.rpc_cred;
447
448         dprintk("RPC: %5u using %s cred %p to wrap rpc data\n",
449                         task->tk_pid, cred->cr_ops->cr_name, cred);
450         if (cred->cr_ops->crwrap_req)
451                 return cred->cr_ops->crwrap_req(task, encode, rqstp, data, obj);
452         /* By default, we encode the arguments normally. */
453         return encode(rqstp, data, obj);
454 }
455
456 int
457 rpcauth_unwrap_resp(struct rpc_task *task, kxdrproc_t decode, void *rqstp,
458                 __be32 *data, void *obj)
459 {
460         struct rpc_cred *cred = task->tk_msg.rpc_cred;
461
462         dprintk("RPC: %5u using %s cred %p to unwrap rpc data\n",
463                         task->tk_pid, cred->cr_ops->cr_name, cred);
464         if (cred->cr_ops->crunwrap_resp)
465                 return cred->cr_ops->crunwrap_resp(task, decode, rqstp,
466                                                    data, obj);
467         /* By default, we decode the arguments normally. */
468         return decode(rqstp, data, obj);
469 }
470
471 int
472 rpcauth_refreshcred(struct rpc_task *task)
473 {
474         struct rpc_cred *cred = task->tk_msg.rpc_cred;
475         int err;
476
477         dprintk("RPC: %5u refreshing %s cred %p\n",
478                 task->tk_pid, task->tk_auth->au_ops->au_name, cred);
479
480         err = cred->cr_ops->crrefresh(task);
481         if (err < 0)
482                 task->tk_status = err;
483         return err;
484 }
485
486 void
487 rpcauth_invalcred(struct rpc_task *task)
488 {
489         struct rpc_cred *cred = task->tk_msg.rpc_cred;
490
491         dprintk("RPC: %5u invalidating %s cred %p\n",
492                 task->tk_pid, task->tk_auth->au_ops->au_name, cred);
493         if (cred)
494                 clear_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
495 }
496
497 int
498 rpcauth_uptodatecred(struct rpc_task *task)
499 {
500         struct rpc_cred *cred = task->tk_msg.rpc_cred;
501
502         return cred == NULL ||
503                 test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0;
504 }