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