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.
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
= {
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),
57 .uid_keyring
= &root_user_keyring
,
58 .session_keyring
= &root_session_keyring
,
60 #ifdef CONFIG_FAIR_USER_SCHED
61 .tg
= &init_task_group
,
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
;
83 hlist_for_each_entry(user
, h
, hashent
, uidhash_node
) {
84 if (user
->uid
== uid
) {
85 atomic_inc(&user
->__count
);
93 #ifdef CONFIG_FAIR_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
)
104 up
->tg
= sched_create_group();
111 static void sched_switch_user(struct task_struct
*p
)
116 #else /* CONFIG_FAIR_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_FAIR_USER_SCHED */
124 #if defined(CONFIG_FAIR_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 static ssize_t
cpu_shares_show(struct kobject
*kobj
,
141 struct kobj_attribute
*attr
,
144 struct user_struct
*up
= container_of(kobj
, struct user_struct
, kobj
);
146 return sprintf(buf
, "%lu\n", sched_group_shares(up
->tg
));
149 static ssize_t
cpu_shares_store(struct kobject
*kobj
,
150 struct kobj_attribute
*attr
,
151 const char *buf
, size_t size
)
153 struct user_struct
*up
= container_of(kobj
, struct user_struct
, kobj
);
154 unsigned long shares
;
157 sscanf(buf
, "%lu", &shares
);
159 rc
= sched_group_set_shares(up
->tg
, shares
);
161 return (rc
? rc
: size
);
164 static struct kobj_attribute cpu_share_attr
=
165 __ATTR(cpu_share
, 0644, cpu_shares_show
, cpu_shares_store
);
167 static ssize_t
cpu_rt_runtime_show(struct kobject
*kobj
,
168 struct kobj_attribute
*attr
,
171 struct user_struct
*up
= container_of(kobj
, struct user_struct
, kobj
);
173 return sprintf(buf
, "%lu\n", sched_group_rt_runtime(up
->tg
));
176 static ssize_t
cpu_rt_runtime_store(struct kobject
*kobj
,
177 struct kobj_attribute
*attr
,
178 const char *buf
, size_t size
)
180 struct user_struct
*up
= container_of(kobj
, struct user_struct
, kobj
);
181 unsigned long rt_runtime
;
184 sscanf(buf
, "%lu", &rt_runtime
);
186 rc
= sched_group_set_rt_runtime(up
->tg
, rt_runtime
);
188 return (rc
? rc
: size
);
191 static struct kobj_attribute cpu_rt_runtime_attr
=
192 __ATTR(cpu_rt_runtime
, 0644, cpu_rt_runtime_show
, cpu_rt_runtime_store
);
194 /* default attributes per uid directory */
195 static struct attribute
*uids_attributes
[] = {
196 &cpu_share_attr
.attr
,
197 &cpu_rt_runtime_attr
.attr
,
201 /* the lifetime of user_struct is not managed by the core (now) */
202 static void uids_release(struct kobject
*kobj
)
207 static struct kobj_type uids_ktype
= {
208 .sysfs_ops
= &kobj_sysfs_ops
,
209 .default_attrs
= uids_attributes
,
210 .release
= uids_release
,
213 /* create /sys/kernel/uids/<uid>/cpu_share file for this user */
214 static int uids_user_create(struct user_struct
*up
)
216 struct kobject
*kobj
= &up
->kobj
;
219 memset(kobj
, 0, sizeof(struct kobject
));
220 kobj
->kset
= uids_kset
;
221 error
= kobject_init_and_add(kobj
, &uids_ktype
, NULL
, "%d", up
->uid
);
227 kobject_uevent(kobj
, KOBJ_ADD
);
232 /* create these entries in sysfs:
233 * "/sys/kernel/uids" directory
234 * "/sys/kernel/uids/0" directory (for root user)
235 * "/sys/kernel/uids/0/cpu_share" file (for root user)
237 int __init
uids_sysfs_init(void)
239 uids_kset
= kset_create_and_add("uids", NULL
, kernel_kobj
);
243 return uids_user_create(&root_user
);
246 /* work function to remove sysfs directory for a user and free up
247 * corresponding structures.
249 static void remove_user_sysfs_dir(struct work_struct
*w
)
251 struct user_struct
*up
= container_of(w
, struct user_struct
, work
);
255 /* Make uid_hash_remove() + sysfs_remove_file() + kobject_del()
260 local_irq_save(flags
);
262 if (atomic_dec_and_lock(&up
->__count
, &uidhash_lock
)) {
265 spin_unlock_irqrestore(&uidhash_lock
, flags
);
267 local_irq_restore(flags
);
273 kobject_uevent(&up
->kobj
, KOBJ_REMOVE
);
274 kobject_del(&up
->kobj
);
275 kobject_put(&up
->kobj
);
277 sched_destroy_user(up
);
278 key_put(up
->uid_keyring
);
279 key_put(up
->session_keyring
);
280 kmem_cache_free(uid_cachep
, up
);
286 /* IRQs are disabled and uidhash_lock is held upon function entry.
287 * IRQ state (as stored in flags) is restored and uidhash_lock released
288 * upon function exit.
290 static inline void free_user(struct user_struct
*up
, unsigned long flags
)
292 /* restore back the count */
293 atomic_inc(&up
->__count
);
294 spin_unlock_irqrestore(&uidhash_lock
, flags
);
296 INIT_WORK(&up
->work
, remove_user_sysfs_dir
);
297 schedule_work(&up
->work
);
300 #else /* CONFIG_FAIR_USER_SCHED && CONFIG_SYSFS */
302 int uids_sysfs_init(void) { return 0; }
303 static inline int uids_user_create(struct user_struct
*up
) { return 0; }
304 static inline void uids_mutex_lock(void) { }
305 static inline void uids_mutex_unlock(void) { }
307 /* IRQs are disabled and uidhash_lock is held upon function entry.
308 * IRQ state (as stored in flags) is restored and uidhash_lock released
309 * upon function exit.
311 static inline void free_user(struct user_struct
*up
, unsigned long flags
)
314 spin_unlock_irqrestore(&uidhash_lock
, flags
);
315 sched_destroy_user(up
);
316 key_put(up
->uid_keyring
);
317 key_put(up
->session_keyring
);
318 kmem_cache_free(uid_cachep
, up
);
324 * Locate the user_struct for the passed UID. If found, take a ref on it. The
325 * caller must undo that ref with free_uid().
327 * If the user_struct could not be found, return NULL.
329 struct user_struct
*find_user(uid_t uid
)
331 struct user_struct
*ret
;
333 struct user_namespace
*ns
= current
->nsproxy
->user_ns
;
335 spin_lock_irqsave(&uidhash_lock
, flags
);
336 ret
= uid_hash_find(uid
, uidhashentry(ns
, uid
));
337 spin_unlock_irqrestore(&uidhash_lock
, flags
);
341 void free_uid(struct user_struct
*up
)
348 local_irq_save(flags
);
349 if (atomic_dec_and_lock(&up
->__count
, &uidhash_lock
))
350 free_user(up
, flags
);
352 local_irq_restore(flags
);
355 struct user_struct
* alloc_uid(struct user_namespace
*ns
, uid_t uid
)
357 struct hlist_head
*hashent
= uidhashentry(ns
, uid
);
358 struct user_struct
*up
, *new;
360 /* Make uid_hash_find() + uids_user_create() + uid_hash_insert()
365 spin_lock_irq(&uidhash_lock
);
366 up
= uid_hash_find(uid
, hashent
);
367 spin_unlock_irq(&uidhash_lock
);
370 new = kmem_cache_alloc(uid_cachep
, GFP_KERNEL
);
375 atomic_set(&new->__count
, 1);
376 atomic_set(&new->processes
, 0);
377 atomic_set(&new->files
, 0);
378 atomic_set(&new->sigpending
, 0);
379 #ifdef CONFIG_INOTIFY_USER
380 atomic_set(&new->inotify_watches
, 0);
381 atomic_set(&new->inotify_devs
, 0);
383 #ifdef CONFIG_POSIX_MQUEUE
388 if (alloc_uid_keyring(new, current
) < 0)
391 if (sched_create_user(new) < 0)
394 if (uids_user_create(new))
395 goto out_destoy_sched
;
398 * Before adding this, check whether we raced
399 * on adding the same user already..
401 spin_lock_irq(&uidhash_lock
);
402 up
= uid_hash_find(uid
, hashent
);
404 /* This case is not possible when CONFIG_FAIR_USER_SCHED
405 * is defined, since we serialize alloc_uid() using
406 * uids_mutex. Hence no need to call
407 * sched_destroy_user() or remove_user_sysfs_dir().
409 key_put(new->uid_keyring
);
410 key_put(new->session_keyring
);
411 kmem_cache_free(uid_cachep
, new);
413 uid_hash_insert(new, hashent
);
416 spin_unlock_irq(&uidhash_lock
);
425 sched_destroy_user(new);
427 key_put(new->uid_keyring
);
428 key_put(new->session_keyring
);
430 kmem_cache_free(uid_cachep
, new);
436 void switch_uid(struct user_struct
*new_user
)
438 struct user_struct
*old_user
;
440 /* What if a process setreuid()'s and this brings the
441 * new uid over his NPROC rlimit? We can check this now
442 * cheaply with the new uid cache, so if it matters
443 * we should be checking for it. -DaveM
445 old_user
= current
->user
;
446 atomic_inc(&new_user
->processes
);
447 atomic_dec(&old_user
->processes
);
448 switch_uid_keyring(new_user
);
449 current
->user
= new_user
;
450 sched_switch_user(current
);
453 * We need to synchronize with __sigqueue_alloc()
454 * doing a get_uid(p->user).. If that saw the old
455 * user value, we need to wait until it has exited
456 * its critical region before we can free the old
460 spin_unlock_wait(¤t
->sighand
->siglock
);
466 #ifdef CONFIG_USER_NS
467 void release_uids(struct user_namespace
*ns
)
471 struct hlist_head
*head
;
472 struct hlist_node
*nd
;
474 spin_lock_irqsave(&uidhash_lock
, flags
);
476 * collapse the chains so that the user_struct-s will
477 * be still alive, but not in hashes. subsequent free_uid()
480 for (i
= 0; i
< UIDHASH_SZ
; i
++) {
481 head
= ns
->uidhash_table
+ i
;
482 while (!hlist_empty(head
)) {
487 spin_unlock_irqrestore(&uidhash_lock
, flags
);
489 free_uid(ns
->root_user
);
493 static int __init
uid_cache_init(void)
497 uid_cachep
= kmem_cache_create("uid_cache", sizeof(struct user_struct
),
498 0, SLAB_HWCACHE_ALIGN
|SLAB_PANIC
, NULL
);
500 for(n
= 0; n
< UIDHASH_SZ
; ++n
)
501 INIT_HLIST_HEAD(init_user_ns
.uidhash_table
+ n
);
503 /* Insert the root user immediately (init already runs as root) */
504 spin_lock_irq(&uidhash_lock
);
505 uid_hash_insert(&root_user
, uidhashentry(&init_user_ns
, 0));
506 spin_unlock_irq(&uidhash_lock
);
511 module_init(uid_cache_init
);