[GitHub/MotorolaMobilityLLC/kernel-slsi.git] / kernel / user.c

/*
 * The "user cache".
 *
 * (C) Copyright 1991-2000 Linus Torvalds
 *
 * We have a per-user structure to keep track of how many
 * processes, files etc the user has claimed, in order to be
 * able to have per-user limits for system resources. 
 */

#include <linux/init.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/bitops.h>
#include <linux/key.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/user_namespace.h>
#include "cred-internals.h"

struct user_namespace init_user_ns = {
	.kref = {
		.refcount	= ATOMIC_INIT(2),
	},
	.root_user = &root_user,
};
EXPORT_SYMBOL_GPL(init_user_ns);

/*
 * UID task count cache, to get fast user lookup in "alloc_uid"
 * when changing user ID's (ie setuid() and friends).
 */

#define UIDHASH_MASK		(UIDHASH_SZ - 1)
#define __uidhashfn(uid)	(((uid >> UIDHASH_BITS) + uid) & UIDHASH_MASK)
#define uidhashentry(ns, uid)	((ns)->uidhash_table + __uidhashfn((uid)))

static struct kmem_cache *uid_cachep;

/*
 * The uidhash_lock is mostly taken from process context, but it is
 * occasionally also taken from softirq/tasklet context, when
 * task-structs get RCU-freed. Hence all locking must be softirq-safe.
 * But free_uid() is also called with local interrupts disabled, and running
 * local_bh_enable() with local interrupts disabled is an error - we'll run
 * softirq callbacks, and they can unconditionally enable interrupts, and
 * the caller of free_uid() didn't expect that..
 */
static DEFINE_SPINLOCK(uidhash_lock);

struct user_struct root_user = {
	.__count	= ATOMIC_INIT(1),
	.processes	= ATOMIC_INIT(1),
	.files		= ATOMIC_INIT(0),
	.sigpending	= ATOMIC_INIT(0),
	.locked_shm     = 0,
#ifdef CONFIG_USER_SCHED
	.tg		= &init_task_group,
#endif
};

/*
 * These routines must be called with the uidhash spinlock held!
 */
static void uid_hash_insert(struct user_struct *up, struct hlist_head *hashent)
{
	hlist_add_head(&up->uidhash_node, hashent);
}

static void uid_hash_remove(struct user_struct *up)
{
	hlist_del_init(&up->uidhash_node);
}

static struct user_struct *uid_hash_find(uid_t uid, struct hlist_head *hashent)
{
	struct user_struct *user;
	struct hlist_node *h;

	hlist_for_each_entry(user, h, hashent, uidhash_node) {
		if (user->uid == uid) {
			atomic_inc(&user->__count);
			return user;
		}
	}

	return NULL;
}

#ifdef CONFIG_USER_SCHED

static void sched_destroy_user(struct user_struct *up)
{
	sched_destroy_group(up->tg);
}

static int sched_create_user(struct user_struct *up)
{
	int rc = 0;

	up->tg = sched_create_group(&root_task_group);
	if (IS_ERR(up->tg))
		rc = -ENOMEM;

	return rc;
}

#else	/* CONFIG_USER_SCHED */

static void sched_destroy_user(struct user_struct *up) { }
static int sched_create_user(struct user_struct *up) { return 0; }

#endif	/* CONFIG_USER_SCHED */

#if defined(CONFIG_USER_SCHED) && defined(CONFIG_SYSFS)

static struct kset *uids_kset; /* represents the /sys/kernel/uids/ directory */
static DEFINE_MUTEX(uids_mutex);

static inline void uids_mutex_lock(void)
{
	mutex_lock(&uids_mutex);
}

static inline void uids_mutex_unlock(void)
{
	mutex_unlock(&uids_mutex);
}

/* uid directory attributes */
#ifdef CONFIG_FAIR_GROUP_SCHED
static ssize_t cpu_shares_show(struct kobject *kobj,
			       struct kobj_attribute *attr,
			       char *buf)
{
	struct user_struct *up = container_of(kobj, struct user_struct, kobj);

	return sprintf(buf, "%lu\n", sched_group_shares(up->tg));
}

static ssize_t cpu_shares_store(struct kobject *kobj,
				struct kobj_attribute *attr,
				const char *buf, size_t size)
{
	struct user_struct *up = container_of(kobj, struct user_struct, kobj);
	unsigned long shares;
	int rc;

	sscanf(buf, "%lu", &shares);

	rc = sched_group_set_shares(up->tg, shares);

	return (rc ? rc : size);
}

static struct kobj_attribute cpu_share_attr =
	__ATTR(cpu_share, 0644, cpu_shares_show, cpu_shares_store);
#endif

#ifdef CONFIG_RT_GROUP_SCHED
static ssize_t cpu_rt_runtime_show(struct kobject *kobj,
				   struct kobj_attribute *attr,
				   char *buf)
{
	struct user_struct *up = container_of(kobj, struct user_struct, kobj);

	return sprintf(buf, "%ld\n", sched_group_rt_runtime(up->tg));
}

static ssize_t cpu_rt_runtime_store(struct kobject *kobj,
				    struct kobj_attribute *attr,
				    const char *buf, size_t size)
{
	struct user_struct *up = container_of(kobj, struct user_struct, kobj);
	unsigned long rt_runtime;
	int rc;

	sscanf(buf, "%ld", &rt_runtime);

	rc = sched_group_set_rt_runtime(up->tg, rt_runtime);

	return (rc ? rc : size);
}

static struct kobj_attribute cpu_rt_runtime_attr =
	__ATTR(cpu_rt_runtime, 0644, cpu_rt_runtime_show, cpu_rt_runtime_store);

static ssize_t cpu_rt_period_show(struct kobject *kobj,
				   struct kobj_attribute *attr,
				   char *buf)
{
	struct user_struct *up = container_of(kobj, struct user_struct, kobj);

	return sprintf(buf, "%lu\n", sched_group_rt_period(up->tg));
}

static ssize_t cpu_rt_period_store(struct kobject *kobj,
				    struct kobj_attribute *attr,
				    const char *buf, size_t size)
{
	struct user_struct *up = container_of(kobj, struct user_struct, kobj);
	unsigned long rt_period;
	int rc;

	sscanf(buf, "%lu", &rt_period);

	rc = sched_group_set_rt_period(up->tg, rt_period);

	return (rc ? rc : size);
}

static struct kobj_attribute cpu_rt_period_attr =
	__ATTR(cpu_rt_period, 0644, cpu_rt_period_show, cpu_rt_period_store);
#endif

/* default attributes per uid directory */
static struct attribute *uids_attributes[] = {
#ifdef CONFIG_FAIR_GROUP_SCHED
	&cpu_share_attr.attr,
#endif
#ifdef CONFIG_RT_GROUP_SCHED
	&cpu_rt_runtime_attr.attr,
	&cpu_rt_period_attr.attr,
#endif
	NULL
};

/* the lifetime of user_struct is not managed by the core (now) */
static void uids_release(struct kobject *kobj)
{
	return;
}

static struct kobj_type uids_ktype = {
	.sysfs_ops = &kobj_sysfs_ops,
	.default_attrs = uids_attributes,
	.release = uids_release,
};

/* create /sys/kernel/uids/<uid>/cpu_share file for this user */
static int uids_user_create(struct user_struct *up)
{
	struct kobject *kobj = &up->kobj;
	int error;

	memset(kobj, 0, sizeof(struct kobject));
	kobj->kset = uids_kset;
	error = kobject_init_and_add(kobj, &uids_ktype, NULL, "%d", up->uid);
	if (error) {
		kobject_put(kobj);
		goto done;
	}

	kobject_uevent(kobj, KOBJ_ADD);
done:
	return error;
}

/* create these entries in sysfs:
 * 	"/sys/kernel/uids" directory
 * 	"/sys/kernel/uids/0" directory (for root user)
 * 	"/sys/kernel/uids/0/cpu_share" file (for root user)
 */
int __init uids_sysfs_init(void)
{
	uids_kset = kset_create_and_add("uids", NULL, kernel_kobj);
	if (!uids_kset)
		return -ENOMEM;

	return uids_user_create(&root_user);
}

/* work function to remove sysfs directory for a user and free up
 * corresponding structures.
 */
static void remove_user_sysfs_dir(struct work_struct *w)
{
	struct user_struct *up = container_of(w, struct user_struct, work);
	unsigned long flags;
	int remove_user = 0;

	/* Make uid_hash_remove() + sysfs_remove_file() + kobject_del()
	 * atomic.
	 */
	uids_mutex_lock();

	local_irq_save(flags);

	if (atomic_dec_and_lock(&up->__count, &uidhash_lock)) {
		uid_hash_remove(up);
		remove_user = 1;
		spin_unlock_irqrestore(&uidhash_lock, flags);
	} else {
		local_irq_restore(flags);
	}

	if (!remove_user)
		goto done;

	kobject_uevent(&up->kobj, KOBJ_REMOVE);
	kobject_del(&up->kobj);
	kobject_put(&up->kobj);

	sched_destroy_user(up);
	key_put(up->uid_keyring);
	key_put(up->session_keyring);
	kmem_cache_free(uid_cachep, up);

done:
	uids_mutex_unlock();
}

/* IRQs are disabled and uidhash_lock is held upon function entry.
 * IRQ state (as stored in flags) is restored and uidhash_lock released
 * upon function exit.
 */
static inline void free_user(struct user_struct *up, unsigned long flags)
{
	/* restore back the count */
	atomic_inc(&up->__count);
	spin_unlock_irqrestore(&uidhash_lock, flags);

	INIT_WORK(&up->work, remove_user_sysfs_dir);
	schedule_work(&up->work);
}

#else	/* CONFIG_USER_SCHED && CONFIG_SYSFS */

int uids_sysfs_init(void) { return 0; }
static inline int uids_user_create(struct user_struct *up) { return 0; }
static inline void uids_mutex_lock(void) { }
static inline void uids_mutex_unlock(void) { }

/* IRQs are disabled and uidhash_lock is held upon function entry.
 * IRQ state (as stored in flags) is restored and uidhash_lock released
 * upon function exit.
 */
static inline void free_user(struct user_struct *up, unsigned long flags)
{
	uid_hash_remove(up);
	spin_unlock_irqrestore(&uidhash_lock, flags);
	sched_destroy_user(up);
	key_put(up->uid_keyring);
	key_put(up->session_keyring);
	kmem_cache_free(uid_cachep, up);
}

#endif

/*
 * Locate the user_struct for the passed UID.  If found, take a ref on it.  The
 * caller must undo that ref with free_uid().
 *
 * If the user_struct could not be found, return NULL.
 */
struct user_struct *find_user(uid_t uid)
{
	struct user_struct *ret;
	unsigned long flags;
	struct user_namespace *ns = current->nsproxy->user_ns;

	spin_lock_irqsave(&uidhash_lock, flags);
	ret = uid_hash_find(uid, uidhashentry(ns, uid));
	spin_unlock_irqrestore(&uidhash_lock, flags);
	return ret;
}

void free_uid(struct user_struct *up)
{
	unsigned long flags;

	if (!up)
		return;

	local_irq_save(flags);
	if (atomic_dec_and_lock(&up->__count, &uidhash_lock))
		free_user(up, flags);
	else
		local_irq_restore(flags);
}

struct user_struct *alloc_uid(struct user_namespace *ns, uid_t uid)
{
	struct hlist_head *hashent = uidhashentry(ns, uid);
	struct user_struct *up, *new;

	/* Make uid_hash_find() + uids_user_create() + uid_hash_insert()
	 * atomic.
	 */
	uids_mutex_lock();

	spin_lock_irq(&uidhash_lock);
	up = uid_hash_find(uid, hashent);
	spin_unlock_irq(&uidhash_lock);

	if (!up) {
		new = kmem_cache_zalloc(uid_cachep, GFP_KERNEL);
		if (!new)
			goto out_unlock;

		new->uid = uid;
		atomic_set(&new->__count, 1);

		if (sched_create_user(new) < 0)
			goto out_free_user;

		if (uids_user_create(new))
			goto out_destoy_sched;

		/*
		 * Before adding this, check whether we raced
		 * on adding the same user already..
		 */
		spin_lock_irq(&uidhash_lock);
		up = uid_hash_find(uid, hashent);
		if (up) {
			/* This case is not possible when CONFIG_USER_SCHED
			 * is defined, since we serialize alloc_uid() using
			 * uids_mutex. Hence no need to call
			 * sched_destroy_user() or remove_user_sysfs_dir().
			 */
			key_put(new->uid_keyring);
			key_put(new->session_keyring);
			kmem_cache_free(uid_cachep, new);
		} else {
			uid_hash_insert(new, hashent);
			up = new;
		}
		spin_unlock_irq(&uidhash_lock);

	}

	uids_mutex_unlock();

	return up;

out_destoy_sched:
	sched_destroy_user(new);
out_free_user:
	kmem_cache_free(uid_cachep, new);
out_unlock:
	uids_mutex_unlock();
	return NULL;
}

#ifdef CONFIG_USER_NS
void release_uids(struct user_namespace *ns)
{
	int i;
	unsigned long flags;
	struct hlist_head *head;
	struct hlist_node *nd;

	spin_lock_irqsave(&uidhash_lock, flags);
	/*
	 * collapse the chains so that the user_struct-s will
	 * be still alive, but not in hashes. subsequent free_uid()
	 * will free them.
	 */
	for (i = 0; i < UIDHASH_SZ; i++) {
		head = ns->uidhash_table + i;
		while (!hlist_empty(head)) {
			nd = head->first;
			hlist_del_init(nd);
		}
	}
	spin_unlock_irqrestore(&uidhash_lock, flags);

	free_uid(ns->root_user);
}
#endif

static int __init uid_cache_init(void)
{
	int n;

	uid_cachep = kmem_cache_create("uid_cache", sizeof(struct user_struct),
			0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);

	for(n = 0; n < UIDHASH_SZ; ++n)
		INIT_HLIST_HEAD(init_user_ns.uidhash_table + n);

	/* Insert the root user immediately (init already runs as root) */
	spin_lock_irq(&uidhash_lock);
	uid_hash_insert(&root_user, uidhashentry(&init_user_ns, 0));
	spin_unlock_irq(&uidhash_lock);

	return 0;
}

module_init(uid_cache_init);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* The "user cache".
	3	*
	4	* (C) Copyright 1991-2000 Linus Torvalds
	5	*
	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	*/
	10
	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>
4021cb27	16	#include <linux/interrupt.h>
acce292c CLG	17	#include <linux/module.h>
acce292c CLG	18	#include <linux/user_namespace.h>
d84f4f99	19	#include "cred-internals.h"
1da177e4	20
aee16ce7 PE	21	struct user_namespace init_user_ns = {
	22	.kref = {
	23	.refcount = ATOMIC_INIT(2),
	24	},
	25	.root_user = &root_user,
	26	};
	27	EXPORT_SYMBOL_GPL(init_user_ns);
	28
1da177e4 LT	29	/*
	30	* UID task count cache, to get fast user lookup in "alloc_uid"
	31	* when changing user ID's (ie setuid() and friends).
	32	*/
	33
1da177e4 LT	34	#define UIDHASH_MASK (UIDHASH_SZ - 1)
1da177e4 LT	35	#define __uidhashfn(uid) (((uid >> UIDHASH_BITS) + uid) & UIDHASH_MASK)
acce292c	36	#define uidhashentry(ns, uid) ((ns)->uidhash_table + __uidhashfn((uid)))
1da177e4	37
e18b890b	38	static struct kmem_cache *uid_cachep;
4021cb27 IM	39
	40	/*
	41	* The uidhash_lock is mostly taken from process context, but it is
	42	* occasionally also taken from softirq/tasklet context, when
	43	* task-structs get RCU-freed. Hence all locking must be softirq-safe.
3fa97c9d AM	44	* But free_uid() is also called with local interrupts disabled, and running
	45	* local_bh_enable() with local interrupts disabled is an error - we'll run
	46	* softirq callbacks, and they can unconditionally enable interrupts, and
	47	* the caller of free_uid() didn't expect that..
4021cb27	48	*/
1da177e4 LT	49	static DEFINE_SPINLOCK(uidhash_lock);
	50
	51	struct user_struct root_user = {
	52	.__count = ATOMIC_INIT(1),
	53	.processes = ATOMIC_INIT(1),
	54	.files = ATOMIC_INIT(0),
	55	.sigpending = ATOMIC_INIT(0),
1da177e4	56	.locked_shm = 0,
052f1dc7	57	#ifdef CONFIG_USER_SCHED
4cf86d77	58	.tg = &init_task_group,
24e377a8	59	#endif
1da177e4 LT	60	};
1da177e4 LT	61
5cb350ba DG	62	/*
	63	* These routines must be called with the uidhash spinlock held!
	64	*/
40aeb400	65	static void uid_hash_insert(struct user_struct up, struct hlist_head hashent)
5cb350ba DG	66	{
	67	hlist_add_head(&up->uidhash_node, hashent);
	68	}
	69
40aeb400	70	static void uid_hash_remove(struct user_struct *up)
5cb350ba DG	71	{
	72	hlist_del_init(&up->uidhash_node);
	73	}
	74
40aeb400	75	static struct user_struct uid_hash_find(uid_t uid, struct hlist_head hashent)
5cb350ba DG	76	{
	77	struct user_struct *user;
	78	struct hlist_node *h;
	79
	80	hlist_for_each_entry(user, h, hashent, uidhash_node) {
	81	if (user->uid == uid) {
	82	atomic_inc(&user->__count);
	83	return user;
	84	}
	85	}
	86
	87	return NULL;
	88	}
	89
052f1dc7	90	#ifdef CONFIG_USER_SCHED
5cb350ba	91
24e377a8 SV	92	static void sched_destroy_user(struct user_struct *up)
	93	{
	94	sched_destroy_group(up->tg);
	95	}
	96
	97	static int sched_create_user(struct user_struct *up)
	98	{
	99	int rc = 0;
	100
eff766a6	101	up->tg = sched_create_group(&root_task_group);
24e377a8 SV	102	if (IS_ERR(up->tg))
	103	rc = -ENOMEM;
	104
	105	return rc;
	106	}
	107
052f1dc7	108	#else /* CONFIG_USER_SCHED */
b1a8c172 DG	109
	110	static void sched_destroy_user(struct user_struct *up) { }
	111	static int sched_create_user(struct user_struct *up) { return 0; }
b1a8c172	112
052f1dc7	113	#endif /* CONFIG_USER_SCHED */
b1a8c172	114
052f1dc7	115	#if defined(CONFIG_USER_SCHED) && defined(CONFIG_SYSFS)
b1a8c172	116
eb41d946	117	static struct kset uids_kset; / represents the /sys/kernel/uids/ directory */
b1a8c172 DG	118	static DEFINE_MUTEX(uids_mutex);
b1a8c172 DG	119
5cb350ba DG	120	static inline void uids_mutex_lock(void)
	121	{
	122	mutex_lock(&uids_mutex);
	123	}
24e377a8	124
5cb350ba DG	125	static inline void uids_mutex_unlock(void)
	126	{
	127	mutex_unlock(&uids_mutex);
	128	}
24e377a8	129
eb41d946	130	/* uid directory attributes */
052f1dc7	131	#ifdef CONFIG_FAIR_GROUP_SCHED
eb41d946 KS	132	static ssize_t cpu_shares_show(struct kobject *kobj,
	133	struct kobj_attribute *attr,
	134	char *buf)
5cb350ba	135	{
eb41d946	136	struct user_struct *up = container_of(kobj, struct user_struct, kobj);
24e377a8	137
eb41d946	138	return sprintf(buf, "%lu\n", sched_group_shares(up->tg));
5cb350ba DG	139	}
5cb350ba DG	140
eb41d946 KS	141	static ssize_t cpu_shares_store(struct kobject *kobj,
	142	struct kobj_attribute *attr,
	143	const char *buf, size_t size)
5cb350ba	144	{
eb41d946	145	struct user_struct *up = container_of(kobj, struct user_struct, kobj);
5cb350ba DG	146	unsigned long shares;
	147	int rc;
	148
eb41d946	149	sscanf(buf, "%lu", &shares);
5cb350ba DG	150
	151	rc = sched_group_set_shares(up->tg, shares);
	152
	153	return (rc ? rc : size);
	154	}
	155
eb41d946 KS	156	static struct kobj_attribute cpu_share_attr =
eb41d946 KS	157	__ATTR(cpu_share, 0644, cpu_shares_show, cpu_shares_store);
052f1dc7	158	#endif
eb41d946	159
052f1dc7	160	#ifdef CONFIG_RT_GROUP_SCHED
9f0c1e56 PZ	161	static ssize_t cpu_rt_runtime_show(struct kobject *kobj,
	162	struct kobj_attribute *attr,
	163	char *buf)
	164	{
	165	struct user_struct *up = container_of(kobj, struct user_struct, kobj);
	166
af4491e5	167	return sprintf(buf, "%ld\n", sched_group_rt_runtime(up->tg));
9f0c1e56 PZ	168	}
	169
	170	static ssize_t cpu_rt_runtime_store(struct kobject *kobj,
	171	struct kobj_attribute *attr,
	172	const char *buf, size_t size)
	173	{
	174	struct user_struct *up = container_of(kobj, struct user_struct, kobj);
	175	unsigned long rt_runtime;
	176	int rc;
	177
af4491e5	178	sscanf(buf, "%ld", &rt_runtime);
9f0c1e56 PZ	179
	180	rc = sched_group_set_rt_runtime(up->tg, rt_runtime);
	181
	182	return (rc ? rc : size);
	183	}
	184
	185	static struct kobj_attribute cpu_rt_runtime_attr =
	186	__ATTR(cpu_rt_runtime, 0644, cpu_rt_runtime_show, cpu_rt_runtime_store);
d0b27fa7 PZ	187
	188	static ssize_t cpu_rt_period_show(struct kobject *kobj,
	189	struct kobj_attribute *attr,
	190	char *buf)
	191	{
	192	struct user_struct *up = container_of(kobj, struct user_struct, kobj);
	193
	194	return sprintf(buf, "%lu\n", sched_group_rt_period(up->tg));
	195	}
	196
	197	static ssize_t cpu_rt_period_store(struct kobject *kobj,
	198	struct kobj_attribute *attr,
	199	const char *buf, size_t size)
	200	{
	201	struct user_struct *up = container_of(kobj, struct user_struct, kobj);
	202	unsigned long rt_period;
	203	int rc;
	204
	205	sscanf(buf, "%lu", &rt_period);
	206
	207	rc = sched_group_set_rt_period(up->tg, rt_period);
	208
	209	return (rc ? rc : size);
	210	}
	211
	212	static struct kobj_attribute cpu_rt_period_attr =
	213	__ATTR(cpu_rt_period, 0644, cpu_rt_period_show, cpu_rt_period_store);
052f1dc7	214	#endif
9f0c1e56	215
eb41d946 KS	216	/* default attributes per uid directory */
eb41d946 KS	217	static struct attribute *uids_attributes[] = {
052f1dc7	218	#ifdef CONFIG_FAIR_GROUP_SCHED
eb41d946	219	&cpu_share_attr.attr,
052f1dc7 PZ	220	#endif
052f1dc7 PZ	221	#ifdef CONFIG_RT_GROUP_SCHED
9f0c1e56	222	&cpu_rt_runtime_attr.attr,
d0b27fa7	223	&cpu_rt_period_attr.attr,
052f1dc7	224	#endif
eb41d946 KS	225	NULL
	226	};
	227
	228	/* the lifetime of user_struct is not managed by the core (now) */
	229	static void uids_release(struct kobject *kobj)
5cb350ba	230	{
eb41d946	231	return;
5cb350ba DG	232	}
5cb350ba DG	233
eb41d946 KS	234	static struct kobj_type uids_ktype = {
	235	.sysfs_ops = &kobj_sysfs_ops,
	236	.default_attrs = uids_attributes,
	237	.release = uids_release,
	238	};
	239
	240	/* create /sys/kernel/uids/<uid>/cpu_share file for this user */
	241	static int uids_user_create(struct user_struct *up)
1da177e4	242	{
eb41d946	243	struct kobject *kobj = &up->kobj;
5cb350ba DG	244	int error;
5cb350ba DG	245
eb41d946	246	memset(kobj, 0, sizeof(struct kobject));
eb41d946	247	kobj->kset = uids_kset;
cf15126b GKH	248	error = kobject_init_and_add(kobj, &uids_ktype, NULL, "%d", up->uid);
	249	if (error) {
	250	kobject_put(kobj);
5cb350ba	251	goto done;
cf15126b	252	}
5cb350ba	253
fb7dde37	254	kobject_uevent(kobj, KOBJ_ADD);
5cb350ba DG	255	done:
5cb350ba DG	256	return error;
1da177e4 LT	257	}
1da177e4 LT	258
eb41d946	259	/* create these entries in sysfs:
5cb350ba DG	260	* "/sys/kernel/uids" directory
	261	* "/sys/kernel/uids/0" directory (for root user)
	262	* "/sys/kernel/uids/0/cpu_share" file (for root user)
	263	*/
eb41d946	264	int __init uids_sysfs_init(void)
1da177e4	265	{
0ff21e46	266	uids_kset = kset_create_and_add("uids", NULL, kernel_kobj);
eb41d946 KS	267	if (!uids_kset)
eb41d946 KS	268	return -ENOMEM;
5cb350ba	269
eb41d946	270	return uids_user_create(&root_user);
1da177e4 LT	271	}
1da177e4 LT	272
5cb350ba DG	273	/* work function to remove sysfs directory for a user and free up
	274	* corresponding structures.
	275	*/
	276	static void remove_user_sysfs_dir(struct work_struct *w)
1da177e4	277	{
5cb350ba	278	struct user_struct *up = container_of(w, struct user_struct, work);
5cb350ba DG	279	unsigned long flags;
5cb350ba DG	280	int remove_user = 0;
1da177e4	281
5cb350ba DG	282	/* Make uid_hash_remove() + sysfs_remove_file() + kobject_del()
	283	* atomic.
	284	*/
	285	uids_mutex_lock();
	286
	287	local_irq_save(flags);
	288
	289	if (atomic_dec_and_lock(&up->__count, &uidhash_lock)) {
	290	uid_hash_remove(up);
	291	remove_user = 1;
	292	spin_unlock_irqrestore(&uidhash_lock, flags);
	293	} else {
	294	local_irq_restore(flags);
1da177e4 LT	295	}
1da177e4 LT	296
5cb350ba DG	297	if (!remove_user)
	298	goto done;
	299
eb41d946 KS	300	kobject_uevent(&up->kobj, KOBJ_REMOVE);
	301	kobject_del(&up->kobj);
	302	kobject_put(&up->kobj);
5cb350ba DG	303
	304	sched_destroy_user(up);
	305	key_put(up->uid_keyring);
	306	key_put(up->session_keyring);
	307	kmem_cache_free(uid_cachep, up);
	308
	309	done:
	310	uids_mutex_unlock();
	311	}
	312
	313	/* IRQs are disabled and uidhash_lock is held upon function entry.
	314	* IRQ state (as stored in flags) is restored and uidhash_lock released
	315	* upon function exit.
	316	*/
	317	static inline void free_user(struct user_struct *up, unsigned long flags)
	318	{
	319	/* restore back the count */
	320	atomic_inc(&up->__count);
	321	spin_unlock_irqrestore(&uidhash_lock, flags);
	322
	323	INIT_WORK(&up->work, remove_user_sysfs_dir);
	324	schedule_work(&up->work);
1da177e4 LT	325	}
1da177e4 LT	326
052f1dc7	327	#else /* CONFIG_USER_SCHED && CONFIG_SYSFS */
5cb350ba	328
eb41d946 KS	329	int uids_sysfs_init(void) { return 0; }
eb41d946 KS	330	static inline int uids_user_create(struct user_struct *up) { return 0; }
5cb350ba DG	331	static inline void uids_mutex_lock(void) { }
	332	static inline void uids_mutex_unlock(void) { }
	333
	334	/* IRQs are disabled and uidhash_lock is held upon function entry.
	335	* IRQ state (as stored in flags) is restored and uidhash_lock released
	336	* upon function exit.
	337	*/
	338	static inline void free_user(struct user_struct *up, unsigned long flags)
	339	{
	340	uid_hash_remove(up);
	341	spin_unlock_irqrestore(&uidhash_lock, flags);
	342	sched_destroy_user(up);
	343	key_put(up->uid_keyring);
	344	key_put(up->session_keyring);
	345	kmem_cache_free(uid_cachep, up);
	346	}
	347
b1a8c172	348	#endif
5cb350ba	349
1da177e4 LT	350	/*
	351	* Locate the user_struct for the passed UID. If found, take a ref on it. The
	352	* caller must undo that ref with free_uid().
	353	*
	354	* If the user_struct could not be found, return NULL.
	355	*/
	356	struct user_struct *find_user(uid_t uid)
	357	{
	358	struct user_struct *ret;
3fa97c9d	359	unsigned long flags;
acce292c	360	struct user_namespace *ns = current->nsproxy->user_ns;
1da177e4	361
3fa97c9d	362	spin_lock_irqsave(&uidhash_lock, flags);
acce292c	363	ret = uid_hash_find(uid, uidhashentry(ns, uid));
3fa97c9d	364	spin_unlock_irqrestore(&uidhash_lock, flags);
1da177e4 LT	365	return ret;
	366	}
	367
	368	void free_uid(struct user_struct *up)
	369	{
3fa97c9d AM	370	unsigned long flags;
3fa97c9d AM	371
36f57413 AM	372	if (!up)
	373	return;
	374
3fa97c9d	375	local_irq_save(flags);
5cb350ba DG	376	if (atomic_dec_and_lock(&up->__count, &uidhash_lock))
	377	free_user(up, flags);
	378	else
36f57413	379	local_irq_restore(flags);
1da177e4 LT	380	}
1da177e4 LT	381
354a1f4d	382	struct user_struct alloc_uid(struct user_namespace ns, uid_t uid)
1da177e4	383	{
735de223	384	struct hlist_head *hashent = uidhashentry(ns, uid);
8eb703e4	385	struct user_struct up, new;
1da177e4	386
eb41d946	387	/* Make uid_hash_find() + uids_user_create() + uid_hash_insert()
5cb350ba DG	388	* atomic.
	389	*/
	390	uids_mutex_lock();
	391
3fa97c9d	392	spin_lock_irq(&uidhash_lock);
1da177e4	393	up = uid_hash_find(uid, hashent);
3fa97c9d	394	spin_unlock_irq(&uidhash_lock);
1da177e4 LT	395
1da177e4 LT	396	if (!up) {
354a1f4d	397	new = kmem_cache_zalloc(uid_cachep, GFP_KERNEL);
8eb703e4 PE	398	if (!new)
8eb703e4 PE	399	goto out_unlock;
5e8869bb	400
1da177e4 LT	401	new->uid = uid;
1da177e4 LT	402	atomic_set(&new->__count, 1);
1da177e4	403
8eb703e4	404	if (sched_create_user(new) < 0)
69664cf1	405	goto out_free_user;
24e377a8	406
8eb703e4 PE	407	if (uids_user_create(new))
8eb703e4 PE	408	goto out_destoy_sched;
5cb350ba	409
1da177e4 LT	410	/*
	411	* Before adding this, check whether we raced
	412	* on adding the same user already..
	413	*/
3fa97c9d	414	spin_lock_irq(&uidhash_lock);
1da177e4 LT	415	up = uid_hash_find(uid, hashent);
1da177e4 LT	416	if (up) {
052f1dc7	417	/* This case is not possible when CONFIG_USER_SCHED
5cb350ba DG	418	* is defined, since we serialize alloc_uid() using
	419	* uids_mutex. Hence no need to call
	420	* sched_destroy_user() or remove_user_sysfs_dir().
	421	*/
1da177e4 LT	422	key_put(new->uid_keyring);
	423	key_put(new->session_keyring);
	424	kmem_cache_free(uid_cachep, new);
	425	} else {
	426	uid_hash_insert(new, hashent);
	427	up = new;
	428	}
3fa97c9d	429	spin_unlock_irq(&uidhash_lock);
1da177e4 LT	430
1da177e4 LT	431	}
5cb350ba DG	432
	433	uids_mutex_unlock();
	434
1da177e4	435	return up;
8eb703e4 PE	436
	437	out_destoy_sched:
	438	sched_destroy_user(new);
8eb703e4 PE	439	out_free_user:
	440	kmem_cache_free(uid_cachep, new);
	441	out_unlock:
	442	uids_mutex_unlock();
	443	return NULL;
1da177e4 LT	444	}
1da177e4 LT	445
aee16ce7	446	#ifdef CONFIG_USER_NS
28f300d2 PE	447	void release_uids(struct user_namespace *ns)
	448	{
	449	int i;
	450	unsigned long flags;
	451	struct hlist_head *head;
	452	struct hlist_node *nd;
	453
	454	spin_lock_irqsave(&uidhash_lock, flags);
	455	/*
	456	* collapse the chains so that the user_struct-s will
	457	* be still alive, but not in hashes. subsequent free_uid()
	458	* will free them.
	459	*/
	460	for (i = 0; i < UIDHASH_SZ; i++) {
	461	head = ns->uidhash_table + i;
	462	while (!hlist_empty(head)) {
	463	nd = head->first;
	464	hlist_del_init(nd);
	465	}
	466	}
	467	spin_unlock_irqrestore(&uidhash_lock, flags);
	468
	469	free_uid(ns->root_user);
	470	}
aee16ce7	471	#endif
1da177e4 LT	472
	473	static int __init uid_cache_init(void)
	474	{
	475	int n;
	476
	477	uid_cachep = kmem_cache_create("uid_cache", sizeof(struct user_struct),
20c2df83	478	0, SLAB_HWCACHE_ALIGN\|SLAB_PANIC, NULL);
1da177e4 LT	479
1da177e4 LT	480	for(n = 0; n < UIDHASH_SZ; ++n)
735de223	481	INIT_HLIST_HEAD(init_user_ns.uidhash_table + n);
1da177e4 LT	482
1da177e4 LT	483	/* Insert the root user immediately (init already runs as root) */
3fa97c9d	484	spin_lock_irq(&uidhash_lock);
acce292c	485	uid_hash_insert(&root_user, uidhashentry(&init_user_ns, 0));
3fa97c9d	486	spin_unlock_irq(&uidhash_lock);
1da177e4 LT	487
	488	return 0;
	489	}
	490
	491	module_init(uid_cache_init);