x86: remove kludge from x86_64
[linux-2.6/mini2440.git] / kernel / user.c
blob7132022a040cc764b1c8cdd53744e7398e05502d
1 /*
2 * The "user cache".
4 * (C) Copyright 1991-2000 Linus Torvalds
6 * We have a per-user structure to keep track of how many
7 * processes, files etc the user has claimed, in order to be
8 * able to have per-user limits for system resources.
9 */
11 #include <linux/init.h>
12 #include <linux/sched.h>
13 #include <linux/slab.h>
14 #include <linux/bitops.h>
15 #include <linux/key.h>
16 #include <linux/interrupt.h>
17 #include <linux/module.h>
18 #include <linux/user_namespace.h>
20 struct user_namespace init_user_ns = {
21 .kref = {
22 .refcount = ATOMIC_INIT(2),
24 .root_user = &root_user,
26 EXPORT_SYMBOL_GPL(init_user_ns);
29 * UID task count cache, to get fast user lookup in "alloc_uid"
30 * when changing user ID's (ie setuid() and friends).
33 #define UIDHASH_MASK (UIDHASH_SZ - 1)
34 #define __uidhashfn(uid) (((uid >> UIDHASH_BITS) + uid) & UIDHASH_MASK)
35 #define uidhashentry(ns, uid) ((ns)->uidhash_table + __uidhashfn((uid)))
37 static struct kmem_cache *uid_cachep;
40 * The uidhash_lock is mostly taken from process context, but it is
41 * occasionally also taken from softirq/tasklet context, when
42 * task-structs get RCU-freed. Hence all locking must be softirq-safe.
43 * But free_uid() is also called with local interrupts disabled, and running
44 * local_bh_enable() with local interrupts disabled is an error - we'll run
45 * softirq callbacks, and they can unconditionally enable interrupts, and
46 * the caller of free_uid() didn't expect that..
48 static DEFINE_SPINLOCK(uidhash_lock);
50 struct user_struct root_user = {
51 .__count = ATOMIC_INIT(1),
52 .processes = ATOMIC_INIT(1),
53 .files = ATOMIC_INIT(0),
54 .sigpending = ATOMIC_INIT(0),
55 .locked_shm = 0,
56 #ifdef CONFIG_KEYS
57 .uid_keyring = &root_user_keyring,
58 .session_keyring = &root_session_keyring,
59 #endif
60 #ifdef CONFIG_USER_SCHED
61 .tg = &init_task_group,
62 #endif
66 * These routines must be called with the uidhash spinlock held!
68 static void uid_hash_insert(struct user_struct *up, struct hlist_head *hashent)
70 hlist_add_head(&up->uidhash_node, hashent);
73 static void uid_hash_remove(struct user_struct *up)
75 hlist_del_init(&up->uidhash_node);
78 static struct user_struct *uid_hash_find(uid_t uid, struct hlist_head *hashent)
80 struct user_struct *user;
81 struct hlist_node *h;
83 hlist_for_each_entry(user, h, hashent, uidhash_node) {
84 if (user->uid == uid) {
85 atomic_inc(&user->__count);
86 return user;
90 return NULL;
93 #ifdef CONFIG_USER_SCHED
95 static void sched_destroy_user(struct user_struct *up)
97 sched_destroy_group(up->tg);
100 static int sched_create_user(struct user_struct *up)
102 int rc = 0;
104 up->tg = sched_create_group();
105 if (IS_ERR(up->tg))
106 rc = -ENOMEM;
108 return rc;
111 static void sched_switch_user(struct task_struct *p)
113 sched_move_task(p);
116 #else /* CONFIG_USER_SCHED */
118 static void sched_destroy_user(struct user_struct *up) { }
119 static int sched_create_user(struct user_struct *up) { return 0; }
120 static void sched_switch_user(struct task_struct *p) { }
122 #endif /* CONFIG_USER_SCHED */
124 #if defined(CONFIG_USER_SCHED) && defined(CONFIG_SYSFS)
126 static struct kset *uids_kset; /* represents the /sys/kernel/uids/ directory */
127 static DEFINE_MUTEX(uids_mutex);
129 static inline void uids_mutex_lock(void)
131 mutex_lock(&uids_mutex);
134 static inline void uids_mutex_unlock(void)
136 mutex_unlock(&uids_mutex);
139 /* uid directory attributes */
140 #ifdef CONFIG_FAIR_GROUP_SCHED
141 static ssize_t cpu_shares_show(struct kobject *kobj,
142 struct kobj_attribute *attr,
143 char *buf)
145 struct user_struct *up = container_of(kobj, struct user_struct, kobj);
147 return sprintf(buf, "%lu\n", sched_group_shares(up->tg));
150 static ssize_t cpu_shares_store(struct kobject *kobj,
151 struct kobj_attribute *attr,
152 const char *buf, size_t size)
154 struct user_struct *up = container_of(kobj, struct user_struct, kobj);
155 unsigned long shares;
156 int rc;
158 sscanf(buf, "%lu", &shares);
160 rc = sched_group_set_shares(up->tg, shares);
162 return (rc ? rc : size);
165 static struct kobj_attribute cpu_share_attr =
166 __ATTR(cpu_share, 0644, cpu_shares_show, cpu_shares_store);
167 #endif
169 #ifdef CONFIG_RT_GROUP_SCHED
170 static ssize_t cpu_rt_runtime_show(struct kobject *kobj,
171 struct kobj_attribute *attr,
172 char *buf)
174 struct user_struct *up = container_of(kobj, struct user_struct, kobj);
176 return sprintf(buf, "%lu\n", sched_group_rt_runtime(up->tg));
179 static ssize_t cpu_rt_runtime_store(struct kobject *kobj,
180 struct kobj_attribute *attr,
181 const char *buf, size_t size)
183 struct user_struct *up = container_of(kobj, struct user_struct, kobj);
184 unsigned long rt_runtime;
185 int rc;
187 sscanf(buf, "%lu", &rt_runtime);
189 rc = sched_group_set_rt_runtime(up->tg, rt_runtime);
191 return (rc ? rc : size);
194 static struct kobj_attribute cpu_rt_runtime_attr =
195 __ATTR(cpu_rt_runtime, 0644, cpu_rt_runtime_show, cpu_rt_runtime_store);
196 #endif
198 /* default attributes per uid directory */
199 static struct attribute *uids_attributes[] = {
200 #ifdef CONFIG_FAIR_GROUP_SCHED
201 &cpu_share_attr.attr,
202 #endif
203 #ifdef CONFIG_RT_GROUP_SCHED
204 &cpu_rt_runtime_attr.attr,
205 #endif
206 NULL
209 /* the lifetime of user_struct is not managed by the core (now) */
210 static void uids_release(struct kobject *kobj)
212 return;
215 static struct kobj_type uids_ktype = {
216 .sysfs_ops = &kobj_sysfs_ops,
217 .default_attrs = uids_attributes,
218 .release = uids_release,
221 /* create /sys/kernel/uids/<uid>/cpu_share file for this user */
222 static int uids_user_create(struct user_struct *up)
224 struct kobject *kobj = &up->kobj;
225 int error;
227 memset(kobj, 0, sizeof(struct kobject));
228 kobj->kset = uids_kset;
229 error = kobject_init_and_add(kobj, &uids_ktype, NULL, "%d", up->uid);
230 if (error) {
231 kobject_put(kobj);
232 goto done;
235 kobject_uevent(kobj, KOBJ_ADD);
236 done:
237 return error;
240 /* create these entries in sysfs:
241 * "/sys/kernel/uids" directory
242 * "/sys/kernel/uids/0" directory (for root user)
243 * "/sys/kernel/uids/0/cpu_share" file (for root user)
245 int __init uids_sysfs_init(void)
247 uids_kset = kset_create_and_add("uids", NULL, kernel_kobj);
248 if (!uids_kset)
249 return -ENOMEM;
251 return uids_user_create(&root_user);
254 /* work function to remove sysfs directory for a user and free up
255 * corresponding structures.
257 static void remove_user_sysfs_dir(struct work_struct *w)
259 struct user_struct *up = container_of(w, struct user_struct, work);
260 unsigned long flags;
261 int remove_user = 0;
263 /* Make uid_hash_remove() + sysfs_remove_file() + kobject_del()
264 * atomic.
266 uids_mutex_lock();
268 local_irq_save(flags);
270 if (atomic_dec_and_lock(&up->__count, &uidhash_lock)) {
271 uid_hash_remove(up);
272 remove_user = 1;
273 spin_unlock_irqrestore(&uidhash_lock, flags);
274 } else {
275 local_irq_restore(flags);
278 if (!remove_user)
279 goto done;
281 kobject_uevent(&up->kobj, KOBJ_REMOVE);
282 kobject_del(&up->kobj);
283 kobject_put(&up->kobj);
285 sched_destroy_user(up);
286 key_put(up->uid_keyring);
287 key_put(up->session_keyring);
288 kmem_cache_free(uid_cachep, up);
290 done:
291 uids_mutex_unlock();
294 /* IRQs are disabled and uidhash_lock is held upon function entry.
295 * IRQ state (as stored in flags) is restored and uidhash_lock released
296 * upon function exit.
298 static inline void free_user(struct user_struct *up, unsigned long flags)
300 /* restore back the count */
301 atomic_inc(&up->__count);
302 spin_unlock_irqrestore(&uidhash_lock, flags);
304 INIT_WORK(&up->work, remove_user_sysfs_dir);
305 schedule_work(&up->work);
308 #else /* CONFIG_USER_SCHED && CONFIG_SYSFS */
310 int uids_sysfs_init(void) { return 0; }
311 static inline int uids_user_create(struct user_struct *up) { return 0; }
312 static inline void uids_mutex_lock(void) { }
313 static inline void uids_mutex_unlock(void) { }
315 /* IRQs are disabled and uidhash_lock is held upon function entry.
316 * IRQ state (as stored in flags) is restored and uidhash_lock released
317 * upon function exit.
319 static inline void free_user(struct user_struct *up, unsigned long flags)
321 uid_hash_remove(up);
322 spin_unlock_irqrestore(&uidhash_lock, flags);
323 sched_destroy_user(up);
324 key_put(up->uid_keyring);
325 key_put(up->session_keyring);
326 kmem_cache_free(uid_cachep, up);
329 #endif
332 * Locate the user_struct for the passed UID. If found, take a ref on it. The
333 * caller must undo that ref with free_uid().
335 * If the user_struct could not be found, return NULL.
337 struct user_struct *find_user(uid_t uid)
339 struct user_struct *ret;
340 unsigned long flags;
341 struct user_namespace *ns = current->nsproxy->user_ns;
343 spin_lock_irqsave(&uidhash_lock, flags);
344 ret = uid_hash_find(uid, uidhashentry(ns, uid));
345 spin_unlock_irqrestore(&uidhash_lock, flags);
346 return ret;
349 void free_uid(struct user_struct *up)
351 unsigned long flags;
353 if (!up)
354 return;
356 local_irq_save(flags);
357 if (atomic_dec_and_lock(&up->__count, &uidhash_lock))
358 free_user(up, flags);
359 else
360 local_irq_restore(flags);
363 struct user_struct * alloc_uid(struct user_namespace *ns, uid_t uid)
365 struct hlist_head *hashent = uidhashentry(ns, uid);
366 struct user_struct *up, *new;
368 /* Make uid_hash_find() + uids_user_create() + uid_hash_insert()
369 * atomic.
371 uids_mutex_lock();
373 spin_lock_irq(&uidhash_lock);
374 up = uid_hash_find(uid, hashent);
375 spin_unlock_irq(&uidhash_lock);
377 if (!up) {
378 new = kmem_cache_alloc(uid_cachep, GFP_KERNEL);
379 if (!new)
380 goto out_unlock;
382 new->uid = uid;
383 atomic_set(&new->__count, 1);
384 atomic_set(&new->processes, 0);
385 atomic_set(&new->files, 0);
386 atomic_set(&new->sigpending, 0);
387 #ifdef CONFIG_INOTIFY_USER
388 atomic_set(&new->inotify_watches, 0);
389 atomic_set(&new->inotify_devs, 0);
390 #endif
391 #ifdef CONFIG_POSIX_MQUEUE
392 new->mq_bytes = 0;
393 #endif
394 new->locked_shm = 0;
396 if (alloc_uid_keyring(new, current) < 0)
397 goto out_free_user;
399 if (sched_create_user(new) < 0)
400 goto out_put_keys;
402 if (uids_user_create(new))
403 goto out_destoy_sched;
406 * Before adding this, check whether we raced
407 * on adding the same user already..
409 spin_lock_irq(&uidhash_lock);
410 up = uid_hash_find(uid, hashent);
411 if (up) {
412 /* This case is not possible when CONFIG_USER_SCHED
413 * is defined, since we serialize alloc_uid() using
414 * uids_mutex. Hence no need to call
415 * sched_destroy_user() or remove_user_sysfs_dir().
417 key_put(new->uid_keyring);
418 key_put(new->session_keyring);
419 kmem_cache_free(uid_cachep, new);
420 } else {
421 uid_hash_insert(new, hashent);
422 up = new;
424 spin_unlock_irq(&uidhash_lock);
428 uids_mutex_unlock();
430 return up;
432 out_destoy_sched:
433 sched_destroy_user(new);
434 out_put_keys:
435 key_put(new->uid_keyring);
436 key_put(new->session_keyring);
437 out_free_user:
438 kmem_cache_free(uid_cachep, new);
439 out_unlock:
440 uids_mutex_unlock();
441 return NULL;
444 void switch_uid(struct user_struct *new_user)
446 struct user_struct *old_user;
448 /* What if a process setreuid()'s and this brings the
449 * new uid over his NPROC rlimit? We can check this now
450 * cheaply with the new uid cache, so if it matters
451 * we should be checking for it. -DaveM
453 old_user = current->user;
454 atomic_inc(&new_user->processes);
455 atomic_dec(&old_user->processes);
456 switch_uid_keyring(new_user);
457 current->user = new_user;
458 sched_switch_user(current);
461 * We need to synchronize with __sigqueue_alloc()
462 * doing a get_uid(p->user).. If that saw the old
463 * user value, we need to wait until it has exited
464 * its critical region before we can free the old
465 * structure.
467 smp_mb();
468 spin_unlock_wait(&current->sighand->siglock);
470 free_uid(old_user);
471 suid_keys(current);
474 #ifdef CONFIG_USER_NS
475 void release_uids(struct user_namespace *ns)
477 int i;
478 unsigned long flags;
479 struct hlist_head *head;
480 struct hlist_node *nd;
482 spin_lock_irqsave(&uidhash_lock, flags);
484 * collapse the chains so that the user_struct-s will
485 * be still alive, but not in hashes. subsequent free_uid()
486 * will free them.
488 for (i = 0; i < UIDHASH_SZ; i++) {
489 head = ns->uidhash_table + i;
490 while (!hlist_empty(head)) {
491 nd = head->first;
492 hlist_del_init(nd);
495 spin_unlock_irqrestore(&uidhash_lock, flags);
497 free_uid(ns->root_user);
499 #endif
501 static int __init uid_cache_init(void)
503 int n;
505 uid_cachep = kmem_cache_create("uid_cache", sizeof(struct user_struct),
506 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
508 for(n = 0; n < UIDHASH_SZ; ++n)
509 INIT_HLIST_HEAD(init_user_ns.uidhash_table + n);
511 /* Insert the root user immediately (init already runs as root) */
512 spin_lock_irq(&uidhash_lock);
513 uid_hash_insert(&root_user, uidhashentry(&init_user_ns, 0));
514 spin_unlock_irq(&uidhash_lock);
516 return 0;
519 module_init(uid_cache_init);