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),
56 #ifdef CONFIG_USER_SCHED
57 .tg
= &init_task_group
,
62 * These routines must be called with the uidhash spinlock held!
64 static void uid_hash_insert(struct user_struct
*up
, struct hlist_head
*hashent
)
66 hlist_add_head(&up
->uidhash_node
, hashent
);
69 static void uid_hash_remove(struct user_struct
*up
)
71 hlist_del_init(&up
->uidhash_node
);
74 static struct user_struct
*uid_hash_find(uid_t uid
, struct hlist_head
*hashent
)
76 struct user_struct
*user
;
79 hlist_for_each_entry(user
, h
, hashent
, uidhash_node
) {
80 if (user
->uid
== uid
) {
81 atomic_inc(&user
->__count
);
89 #ifdef CONFIG_USER_SCHED
91 static void sched_destroy_user(struct user_struct
*up
)
93 sched_destroy_group(up
->tg
);
96 static int sched_create_user(struct user_struct
*up
)
100 up
->tg
= sched_create_group(&root_task_group
);
109 static void sched_switch_user(struct task_struct
*p
)
114 #else /* CONFIG_USER_SCHED */
116 static void sched_destroy_user(struct user_struct
*up
) { }
117 static int sched_create_user(struct user_struct
*up
) { return 0; }
118 static void sched_switch_user(struct task_struct
*p
) { }
120 #endif /* CONFIG_USER_SCHED */
122 #if defined(CONFIG_USER_SCHED) && defined(CONFIG_SYSFS)
124 static struct kset
*uids_kset
; /* represents the /sys/kernel/uids/ directory */
125 static DEFINE_MUTEX(uids_mutex
);
127 static inline void uids_mutex_lock(void)
129 mutex_lock(&uids_mutex
);
132 static inline void uids_mutex_unlock(void)
134 mutex_unlock(&uids_mutex
);
137 /* uid directory attributes */
138 #ifdef CONFIG_FAIR_GROUP_SCHED
139 static ssize_t
cpu_shares_show(struct kobject
*kobj
,
140 struct kobj_attribute
*attr
,
143 struct user_struct
*up
= container_of(kobj
, struct user_struct
, kobj
);
145 return sprintf(buf
, "%lu\n", sched_group_shares(up
->tg
));
148 static ssize_t
cpu_shares_store(struct kobject
*kobj
,
149 struct kobj_attribute
*attr
,
150 const char *buf
, size_t size
)
152 struct user_struct
*up
= container_of(kobj
, struct user_struct
, kobj
);
153 unsigned long shares
;
156 sscanf(buf
, "%lu", &shares
);
158 rc
= sched_group_set_shares(up
->tg
, shares
);
160 return (rc
? rc
: size
);
163 static struct kobj_attribute cpu_share_attr
=
164 __ATTR(cpu_share
, 0644, cpu_shares_show
, cpu_shares_store
);
167 #ifdef CONFIG_RT_GROUP_SCHED
168 static ssize_t
cpu_rt_runtime_show(struct kobject
*kobj
,
169 struct kobj_attribute
*attr
,
172 struct user_struct
*up
= container_of(kobj
, struct user_struct
, kobj
);
174 return sprintf(buf
, "%ld\n", sched_group_rt_runtime(up
->tg
));
177 static ssize_t
cpu_rt_runtime_store(struct kobject
*kobj
,
178 struct kobj_attribute
*attr
,
179 const char *buf
, size_t size
)
181 struct user_struct
*up
= container_of(kobj
, struct user_struct
, kobj
);
182 unsigned long rt_runtime
;
185 sscanf(buf
, "%ld", &rt_runtime
);
187 rc
= sched_group_set_rt_runtime(up
->tg
, rt_runtime
);
189 return (rc
? rc
: size
);
192 static struct kobj_attribute cpu_rt_runtime_attr
=
193 __ATTR(cpu_rt_runtime
, 0644, cpu_rt_runtime_show
, cpu_rt_runtime_store
);
195 static ssize_t
cpu_rt_period_show(struct kobject
*kobj
,
196 struct kobj_attribute
*attr
,
199 struct user_struct
*up
= container_of(kobj
, struct user_struct
, kobj
);
201 return sprintf(buf
, "%lu\n", sched_group_rt_period(up
->tg
));
204 static ssize_t
cpu_rt_period_store(struct kobject
*kobj
,
205 struct kobj_attribute
*attr
,
206 const char *buf
, size_t size
)
208 struct user_struct
*up
= container_of(kobj
, struct user_struct
, kobj
);
209 unsigned long rt_period
;
212 sscanf(buf
, "%lu", &rt_period
);
214 rc
= sched_group_set_rt_period(up
->tg
, rt_period
);
216 return (rc
? rc
: size
);
219 static struct kobj_attribute cpu_rt_period_attr
=
220 __ATTR(cpu_rt_period
, 0644, cpu_rt_period_show
, cpu_rt_period_store
);
223 /* default attributes per uid directory */
224 static struct attribute
*uids_attributes
[] = {
225 #ifdef CONFIG_FAIR_GROUP_SCHED
226 &cpu_share_attr
.attr
,
228 #ifdef CONFIG_RT_GROUP_SCHED
229 &cpu_rt_runtime_attr
.attr
,
230 &cpu_rt_period_attr
.attr
,
235 /* the lifetime of user_struct is not managed by the core (now) */
236 static void uids_release(struct kobject
*kobj
)
241 static struct kobj_type uids_ktype
= {
242 .sysfs_ops
= &kobj_sysfs_ops
,
243 .default_attrs
= uids_attributes
,
244 .release
= uids_release
,
247 /* create /sys/kernel/uids/<uid>/cpu_share file for this user */
248 static int uids_user_create(struct user_struct
*up
)
250 struct kobject
*kobj
= &up
->kobj
;
253 memset(kobj
, 0, sizeof(struct kobject
));
254 kobj
->kset
= uids_kset
;
255 error
= kobject_init_and_add(kobj
, &uids_ktype
, NULL
, "%d", up
->uid
);
261 kobject_uevent(kobj
, KOBJ_ADD
);
266 /* create these entries in sysfs:
267 * "/sys/kernel/uids" directory
268 * "/sys/kernel/uids/0" directory (for root user)
269 * "/sys/kernel/uids/0/cpu_share" file (for root user)
271 int __init
uids_sysfs_init(void)
273 uids_kset
= kset_create_and_add("uids", NULL
, kernel_kobj
);
277 return uids_user_create(&root_user
);
280 /* work function to remove sysfs directory for a user and free up
281 * corresponding structures.
283 static void remove_user_sysfs_dir(struct work_struct
*w
)
285 struct user_struct
*up
= container_of(w
, struct user_struct
, work
);
289 /* Make uid_hash_remove() + sysfs_remove_file() + kobject_del()
294 local_irq_save(flags
);
296 if (atomic_dec_and_lock(&up
->__count
, &uidhash_lock
)) {
299 spin_unlock_irqrestore(&uidhash_lock
, flags
);
301 local_irq_restore(flags
);
307 kobject_uevent(&up
->kobj
, KOBJ_REMOVE
);
308 kobject_del(&up
->kobj
);
309 kobject_put(&up
->kobj
);
311 sched_destroy_user(up
);
312 key_put(up
->uid_keyring
);
313 key_put(up
->session_keyring
);
314 kmem_cache_free(uid_cachep
, up
);
320 /* IRQs are disabled and uidhash_lock is held upon function entry.
321 * IRQ state (as stored in flags) is restored and uidhash_lock released
322 * upon function exit.
324 static inline void free_user(struct user_struct
*up
, unsigned long flags
)
326 /* restore back the count */
327 atomic_inc(&up
->__count
);
328 spin_unlock_irqrestore(&uidhash_lock
, flags
);
330 INIT_WORK(&up
->work
, remove_user_sysfs_dir
);
331 schedule_work(&up
->work
);
334 #else /* CONFIG_USER_SCHED && CONFIG_SYSFS */
336 int uids_sysfs_init(void) { return 0; }
337 static inline int uids_user_create(struct user_struct
*up
) { return 0; }
338 static inline void uids_mutex_lock(void) { }
339 static inline void uids_mutex_unlock(void) { }
341 /* IRQs are disabled and uidhash_lock is held upon function entry.
342 * IRQ state (as stored in flags) is restored and uidhash_lock released
343 * upon function exit.
345 static inline void free_user(struct user_struct
*up
, unsigned long flags
)
348 spin_unlock_irqrestore(&uidhash_lock
, flags
);
349 sched_destroy_user(up
);
350 key_put(up
->uid_keyring
);
351 key_put(up
->session_keyring
);
352 kmem_cache_free(uid_cachep
, up
);
358 * Locate the user_struct for the passed UID. If found, take a ref on it. The
359 * caller must undo that ref with free_uid().
361 * If the user_struct could not be found, return NULL.
363 struct user_struct
*find_user(uid_t uid
)
365 struct user_struct
*ret
;
367 struct user_namespace
*ns
= current
->nsproxy
->user_ns
;
369 spin_lock_irqsave(&uidhash_lock
, flags
);
370 ret
= uid_hash_find(uid
, uidhashentry(ns
, uid
));
371 spin_unlock_irqrestore(&uidhash_lock
, flags
);
375 void free_uid(struct user_struct
*up
)
382 local_irq_save(flags
);
383 if (atomic_dec_and_lock(&up
->__count
, &uidhash_lock
))
384 free_user(up
, flags
);
386 local_irq_restore(flags
);
389 struct user_struct
*alloc_uid(struct user_namespace
*ns
, uid_t uid
)
391 struct hlist_head
*hashent
= uidhashentry(ns
, uid
);
392 struct user_struct
*up
, *new;
394 /* Make uid_hash_find() + uids_user_create() + uid_hash_insert()
399 spin_lock_irq(&uidhash_lock
);
400 up
= uid_hash_find(uid
, hashent
);
401 spin_unlock_irq(&uidhash_lock
);
404 new = kmem_cache_zalloc(uid_cachep
, GFP_KERNEL
);
409 atomic_set(&new->__count
, 1);
411 if (sched_create_user(new) < 0)
414 if (uids_user_create(new))
415 goto out_destoy_sched
;
418 * Before adding this, check whether we raced
419 * on adding the same user already..
421 spin_lock_irq(&uidhash_lock
);
422 up
= uid_hash_find(uid
, hashent
);
424 /* This case is not possible when CONFIG_USER_SCHED
425 * is defined, since we serialize alloc_uid() using
426 * uids_mutex. Hence no need to call
427 * sched_destroy_user() or remove_user_sysfs_dir().
429 key_put(new->uid_keyring
);
430 key_put(new->session_keyring
);
431 kmem_cache_free(uid_cachep
, new);
433 uid_hash_insert(new, hashent
);
436 spin_unlock_irq(&uidhash_lock
);
445 sched_destroy_user(new);
447 kmem_cache_free(uid_cachep
, new);
453 void switch_uid(struct user_struct
*new_user
)
455 struct user_struct
*old_user
;
457 /* What if a process setreuid()'s and this brings the
458 * new uid over his NPROC rlimit? We can check this now
459 * cheaply with the new uid cache, so if it matters
460 * we should be checking for it. -DaveM
462 old_user
= current
->user
;
463 atomic_inc(&new_user
->processes
);
464 atomic_dec(&old_user
->processes
);
465 switch_uid_keyring(new_user
);
466 current
->user
= new_user
;
467 sched_switch_user(current
);
470 * We need to synchronize with __sigqueue_alloc()
471 * doing a get_uid(p->user).. If that saw the old
472 * user value, we need to wait until it has exited
473 * its critical region before we can free the old
477 spin_unlock_wait(¤t
->sighand
->siglock
);
483 #ifdef CONFIG_USER_NS
484 void release_uids(struct user_namespace
*ns
)
488 struct hlist_head
*head
;
489 struct hlist_node
*nd
;
491 spin_lock_irqsave(&uidhash_lock
, flags
);
493 * collapse the chains so that the user_struct-s will
494 * be still alive, but not in hashes. subsequent free_uid()
497 for (i
= 0; i
< UIDHASH_SZ
; i
++) {
498 head
= ns
->uidhash_table
+ i
;
499 while (!hlist_empty(head
)) {
504 spin_unlock_irqrestore(&uidhash_lock
, flags
);
506 free_uid(ns
->root_user
);
510 static int __init
uid_cache_init(void)
514 uid_cachep
= kmem_cache_create("uid_cache", sizeof(struct user_struct
),
515 0, SLAB_HWCACHE_ALIGN
|SLAB_PANIC
, NULL
);
517 for(n
= 0; n
< UIDHASH_SZ
; ++n
)
518 INIT_HLIST_HEAD(init_user_ns
.uidhash_table
+ n
);
520 /* Insert the root user immediately (init already runs as root) */
521 spin_lock_irq(&uidhash_lock
);
522 uid_hash_insert(&root_user
, uidhashentry(&init_user_ns
, 0));
523 spin_unlock_irq(&uidhash_lock
);
528 module_init(uid_cache_init
);