SUNRPC: Fix a potential race in rpc_wake_up_task()
[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 struct rpc_authops *     auth_flavors[RPC_AUTH_MAXFLAVOR] = {
22         &authnull_ops,          /* AUTH_NULL */
23         &authunix_ops,          /* AUTH_UNIX */
24         NULL,                   /* others can be loadable modules */
25 };
26
27 static u32
28 pseudoflavor_to_flavor(u32 flavor) {
29         if (flavor >= RPC_AUTH_MAXFLAVOR)
30                 return RPC_AUTH_GSS;
31         return flavor;
32 }
33
34 int
35 rpcauth_register(struct rpc_authops *ops)
36 {
37         rpc_authflavor_t flavor;
38
39         if ((flavor = ops->au_flavor) >= RPC_AUTH_MAXFLAVOR)
40                 return -EINVAL;
41         if (auth_flavors[flavor] != NULL)
42                 return -EPERM;          /* what else? */
43         auth_flavors[flavor] = ops;
44         return 0;
45 }
46
47 int
48 rpcauth_unregister(struct rpc_authops *ops)
49 {
50         rpc_authflavor_t flavor;
51
52         if ((flavor = ops->au_flavor) >= RPC_AUTH_MAXFLAVOR)
53                 return -EINVAL;
54         if (auth_flavors[flavor] != ops)
55                 return -EPERM;          /* what else? */
56         auth_flavors[flavor] = NULL;
57         return 0;
58 }
59
60 struct rpc_auth *
61 rpcauth_create(rpc_authflavor_t pseudoflavor, struct rpc_clnt *clnt)
62 {
63         struct rpc_auth         *auth;
64         struct rpc_authops      *ops;
65         u32                     flavor = pseudoflavor_to_flavor(pseudoflavor);
66
67         auth = ERR_PTR(-EINVAL);
68         if (flavor >= RPC_AUTH_MAXFLAVOR)
69                 goto out;
70
71         /* FIXME - auth_flavors[] really needs an rw lock,
72          * and module refcounting. */
73 #ifdef CONFIG_KMOD
74         if ((ops = auth_flavors[flavor]) == NULL)
75                 request_module("rpc-auth-%u", flavor);
76 #endif
77         if ((ops = auth_flavors[flavor]) == NULL)
78                 goto out;
79         auth = ops->create(clnt, pseudoflavor);
80         if (IS_ERR(auth))
81                 return auth;
82         if (clnt->cl_auth)
83                 rpcauth_destroy(clnt->cl_auth);
84         clnt->cl_auth = auth;
85
86 out:
87         return auth;
88 }
89
90 void
91 rpcauth_destroy(struct rpc_auth *auth)
92 {
93         if (!atomic_dec_and_test(&auth->au_count))
94                 return;
95         auth->au_ops->destroy(auth);
96 }
97
98 static DEFINE_SPINLOCK(rpc_credcache_lock);
99
100 /*
101  * Initialize RPC credential cache
102  */
103 int
104 rpcauth_init_credcache(struct rpc_auth *auth, unsigned long expire)
105 {
106         struct rpc_cred_cache *new;
107         int i;
108
109         new = kmalloc(sizeof(*new), GFP_KERNEL);
110         if (!new)
111                 return -ENOMEM;
112         for (i = 0; i < RPC_CREDCACHE_NR; i++)
113                 INIT_HLIST_HEAD(&new->hashtable[i]);
114         new->expire = expire;
115         new->nextgc = jiffies + (expire >> 1);
116         auth->au_credcache = new;
117         return 0;
118 }
119
120 /*
121  * Destroy a list of credentials
122  */
123 static inline
124 void rpcauth_destroy_credlist(struct hlist_head *head)
125 {
126         struct rpc_cred *cred;
127
128         while (!hlist_empty(head)) {
129                 cred = hlist_entry(head->first, struct rpc_cred, cr_hash);
130                 hlist_del_init(&cred->cr_hash);
131                 put_rpccred(cred);
132         }
133 }
134
135 /*
136  * Clear the RPC credential cache, and delete those credentials
137  * that are not referenced.
138  */
139 void
140 rpcauth_free_credcache(struct rpc_auth *auth)
141 {
142         struct rpc_cred_cache *cache = auth->au_credcache;
143         HLIST_HEAD(free);
144         struct hlist_node *pos, *next;
145         struct rpc_cred *cred;
146         int             i;
147
148         spin_lock(&rpc_credcache_lock);
149         for (i = 0; i < RPC_CREDCACHE_NR; i++) {
150                 hlist_for_each_safe(pos, next, &cache->hashtable[i]) {
151                         cred = hlist_entry(pos, struct rpc_cred, cr_hash);
152                         __hlist_del(&cred->cr_hash);
153                         hlist_add_head(&cred->cr_hash, &free);
154                 }
155         }
156         spin_unlock(&rpc_credcache_lock);
157         rpcauth_destroy_credlist(&free);
158 }
159
160 static void
161 rpcauth_prune_expired(struct rpc_auth *auth, struct rpc_cred *cred, struct hlist_head *free)
162 {
163         if (atomic_read(&cred->cr_count) != 1)
164                return;
165         if (time_after(jiffies, cred->cr_expire + auth->au_credcache->expire))
166                 cred->cr_flags &= ~RPCAUTH_CRED_UPTODATE;
167         if (!(cred->cr_flags & RPCAUTH_CRED_UPTODATE)) {
168                 __hlist_del(&cred->cr_hash);
169                 hlist_add_head(&cred->cr_hash, free);
170         }
171 }
172
173 /*
174  * Remove stale credentials. Avoid sleeping inside the loop.
175  */
176 static void
177 rpcauth_gc_credcache(struct rpc_auth *auth, struct hlist_head *free)
178 {
179         struct rpc_cred_cache *cache = auth->au_credcache;
180         struct hlist_node *pos, *next;
181         struct rpc_cred *cred;
182         int             i;
183
184         dprintk("RPC: gc'ing RPC credentials for auth %p\n", auth);
185         for (i = 0; i < RPC_CREDCACHE_NR; i++) {
186                 hlist_for_each_safe(pos, next, &cache->hashtable[i]) {
187                         cred = hlist_entry(pos, struct rpc_cred, cr_hash);
188                         rpcauth_prune_expired(auth, cred, free);
189                 }
190         }
191         cache->nextgc = jiffies + cache->expire;
192 }
193
194 /*
195  * Look up a process' credentials in the authentication cache
196  */
197 struct rpc_cred *
198 rpcauth_lookup_credcache(struct rpc_auth *auth, struct auth_cred * acred,
199                 int flags)
200 {
201         struct rpc_cred_cache *cache = auth->au_credcache;
202         HLIST_HEAD(free);
203         struct hlist_node *pos, *next;
204         struct rpc_cred *new = NULL,
205                         *cred = NULL;
206         int             nr = 0;
207
208         if (!(flags & RPCAUTH_LOOKUP_ROOTCREDS))
209                 nr = acred->uid & RPC_CREDCACHE_MASK;
210 retry:
211         spin_lock(&rpc_credcache_lock);
212         if (time_before(cache->nextgc, jiffies))
213                 rpcauth_gc_credcache(auth, &free);
214         hlist_for_each_safe(pos, next, &cache->hashtable[nr]) {
215                 struct rpc_cred *entry;
216                 entry = hlist_entry(pos, struct rpc_cred, cr_hash);
217                 if (entry->cr_ops->crmatch(acred, entry, flags)) {
218                         hlist_del(&entry->cr_hash);
219                         cred = entry;
220                         break;
221                 }
222                 rpcauth_prune_expired(auth, entry, &free);
223         }
224         if (new) {
225                 if (cred)
226                         hlist_add_head(&new->cr_hash, &free);
227                 else
228                         cred = new;
229         }
230         if (cred) {
231                 hlist_add_head(&cred->cr_hash, &cache->hashtable[nr]);
232                 get_rpccred(cred);
233         }
234         spin_unlock(&rpc_credcache_lock);
235
236         rpcauth_destroy_credlist(&free);
237
238         if (!cred) {
239                 new = auth->au_ops->crcreate(auth, acred, flags);
240                 if (!IS_ERR(new)) {
241 #ifdef RPC_DEBUG
242                         new->cr_magic = RPCAUTH_CRED_MAGIC;
243 #endif
244                         goto retry;
245                 } else
246                         cred = new;
247         } else if ((cred->cr_flags & RPCAUTH_CRED_NEW)
248                         && cred->cr_ops->cr_init != NULL
249                         && !(flags & RPCAUTH_LOOKUP_NEW)) {
250                 int res = cred->cr_ops->cr_init(auth, cred);
251                 if (res < 0) {
252                         put_rpccred(cred);
253                         cred = ERR_PTR(res);
254                 }
255         }
256
257         return (struct rpc_cred *) cred;
258 }
259
260 struct rpc_cred *
261 rpcauth_lookupcred(struct rpc_auth *auth, int flags)
262 {
263         struct auth_cred acred = {
264                 .uid = current->fsuid,
265                 .gid = current->fsgid,
266                 .group_info = current->group_info,
267         };
268         struct rpc_cred *ret;
269
270         dprintk("RPC:     looking up %s cred\n",
271                 auth->au_ops->au_name);
272         get_group_info(acred.group_info);
273         ret = auth->au_ops->lookup_cred(auth, &acred, flags);
274         put_group_info(acred.group_info);
275         return ret;
276 }
277
278 struct rpc_cred *
279 rpcauth_bindcred(struct rpc_task *task)
280 {
281         struct rpc_auth *auth = task->tk_auth;
282         struct auth_cred acred = {
283                 .uid = current->fsuid,
284                 .gid = current->fsgid,
285                 .group_info = current->group_info,
286         };
287         struct rpc_cred *ret;
288         int flags = 0;
289
290         dprintk("RPC: %4d looking up %s cred\n",
291                 task->tk_pid, task->tk_auth->au_ops->au_name);
292         get_group_info(acred.group_info);
293         if (task->tk_flags & RPC_TASK_ROOTCREDS)
294                 flags |= RPCAUTH_LOOKUP_ROOTCREDS;
295         ret = auth->au_ops->lookup_cred(auth, &acred, flags);
296         if (!IS_ERR(ret))
297                 task->tk_msg.rpc_cred = ret;
298         else
299                 task->tk_status = PTR_ERR(ret);
300         put_group_info(acred.group_info);
301         return ret;
302 }
303
304 void
305 rpcauth_holdcred(struct rpc_task *task)
306 {
307         dprintk("RPC: %4d holding %s cred %p\n",
308                 task->tk_pid, task->tk_auth->au_ops->au_name, task->tk_msg.rpc_cred);
309         if (task->tk_msg.rpc_cred)
310                 get_rpccred(task->tk_msg.rpc_cred);
311 }
312
313 void
314 put_rpccred(struct rpc_cred *cred)
315 {
316         cred->cr_expire = jiffies;
317         if (!atomic_dec_and_test(&cred->cr_count))
318                 return;
319         cred->cr_ops->crdestroy(cred);
320 }
321
322 void
323 rpcauth_unbindcred(struct rpc_task *task)
324 {
325         struct rpc_cred *cred = task->tk_msg.rpc_cred;
326
327         dprintk("RPC: %4d releasing %s cred %p\n",
328                 task->tk_pid, task->tk_auth->au_ops->au_name, cred);
329
330         put_rpccred(cred);
331         task->tk_msg.rpc_cred = NULL;
332 }
333
334 __be32 *
335 rpcauth_marshcred(struct rpc_task *task, __be32 *p)
336 {
337         struct rpc_cred *cred = task->tk_msg.rpc_cred;
338
339         dprintk("RPC: %4d marshaling %s cred %p\n",
340                 task->tk_pid, task->tk_auth->au_ops->au_name, cred);
341
342         return cred->cr_ops->crmarshal(task, p);
343 }
344
345 __be32 *
346 rpcauth_checkverf(struct rpc_task *task, __be32 *p)
347 {
348         struct rpc_cred *cred = task->tk_msg.rpc_cred;
349
350         dprintk("RPC: %4d validating %s cred %p\n",
351                 task->tk_pid, task->tk_auth->au_ops->au_name, cred);
352
353         return cred->cr_ops->crvalidate(task, p);
354 }
355
356 int
357 rpcauth_wrap_req(struct rpc_task *task, kxdrproc_t encode, void *rqstp,
358                 __be32 *data, void *obj)
359 {
360         struct rpc_cred *cred = task->tk_msg.rpc_cred;
361
362         dprintk("RPC: %4d using %s cred %p to wrap rpc data\n",
363                         task->tk_pid, cred->cr_ops->cr_name, cred);
364         if (cred->cr_ops->crwrap_req)
365                 return cred->cr_ops->crwrap_req(task, encode, rqstp, data, obj);
366         /* By default, we encode the arguments normally. */
367         return encode(rqstp, data, obj);
368 }
369
370 int
371 rpcauth_unwrap_resp(struct rpc_task *task, kxdrproc_t decode, void *rqstp,
372                 __be32 *data, void *obj)
373 {
374         struct rpc_cred *cred = task->tk_msg.rpc_cred;
375
376         dprintk("RPC: %4d using %s cred %p to unwrap rpc data\n",
377                         task->tk_pid, cred->cr_ops->cr_name, cred);
378         if (cred->cr_ops->crunwrap_resp)
379                 return cred->cr_ops->crunwrap_resp(task, decode, rqstp,
380                                                    data, obj);
381         /* By default, we decode the arguments normally. */
382         return decode(rqstp, data, obj);
383 }
384
385 int
386 rpcauth_refreshcred(struct rpc_task *task)
387 {
388         struct rpc_cred *cred = task->tk_msg.rpc_cred;
389         int err;
390
391         dprintk("RPC: %4d refreshing %s cred %p\n",
392                 task->tk_pid, task->tk_auth->au_ops->au_name, cred);
393
394         err = cred->cr_ops->crrefresh(task);
395         if (err < 0)
396                 task->tk_status = err;
397         return err;
398 }
399
400 void
401 rpcauth_invalcred(struct rpc_task *task)
402 {
403         dprintk("RPC: %4d invalidating %s cred %p\n",
404                 task->tk_pid, task->tk_auth->au_ops->au_name, task->tk_msg.rpc_cred);
405         spin_lock(&rpc_credcache_lock);
406         if (task->tk_msg.rpc_cred)
407                 task->tk_msg.rpc_cred->cr_flags &= ~RPCAUTH_CRED_UPTODATE;
408         spin_unlock(&rpc_credcache_lock);
409 }
410
411 int
412 rpcauth_uptodatecred(struct rpc_task *task)
413 {
414         return !(task->tk_msg.rpc_cred) ||
415                 (task->tk_msg.rpc_cred->cr_flags & RPCAUTH_CRED_UPTODATE);
416 }