kernel_optimize_test/kernel/user.c
Pavel Emelyanov aee16ce73c namespaces: cleanup the code managed with the USER_NS option
Make the user_namespace.o compilation depend on this option and move the
init_user_ns into user.c file to make the kernel compile and work without the
namespaces support.  This make the user namespace code be organized similar to
other namespaces'.

Also mask the USER_NS option as "depend on NAMESPACES".

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: Kirill Korotaev <dev@sw.ru>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-08 09:22:23 -08:00

484 lines
11 KiB
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>
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_KEYS
.uid_keyring = &root_user_keyring,
.session_keyring = &root_session_keyring,
#endif
#ifdef CONFIG_FAIR_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_FAIR_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();
if (IS_ERR(up->tg))
rc = -ENOMEM;
return rc;
}
static void sched_switch_user(struct task_struct *p)
{
sched_move_task(p);
}
#else /* CONFIG_FAIR_USER_SCHED */
static void sched_destroy_user(struct user_struct *up) { }
static int sched_create_user(struct user_struct *up) { return 0; }
static void sched_switch_user(struct task_struct *p) { }
#endif /* CONFIG_FAIR_USER_SCHED */
#if defined(CONFIG_FAIR_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 */
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);
/* default attributes per uid directory */
static struct attribute *uids_attributes[] = {
&cpu_share_attr.attr,
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_FAIR_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_alloc(uid_cachep, GFP_KERNEL);
if (!new)
goto out_unlock;
new->uid = uid;
atomic_set(&new->__count, 1);
atomic_set(&new->processes, 0);
atomic_set(&new->files, 0);
atomic_set(&new->sigpending, 0);
#ifdef CONFIG_INOTIFY_USER
atomic_set(&new->inotify_watches, 0);
atomic_set(&new->inotify_devs, 0);
#endif
#ifdef CONFIG_POSIX_MQUEUE
new->mq_bytes = 0;
#endif
new->locked_shm = 0;
if (alloc_uid_keyring(new, current) < 0)
goto out_free_user;
if (sched_create_user(new) < 0)
goto out_put_keys;
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_FAIR_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_put_keys:
key_put(new->uid_keyring);
key_put(new->session_keyring);
out_free_user:
kmem_cache_free(uid_cachep, new);
out_unlock:
uids_mutex_unlock();
return NULL;
}
void switch_uid(struct user_struct *new_user)
{
struct user_struct *old_user;
/* What if a process setreuid()'s and this brings the
* new uid over his NPROC rlimit? We can check this now
* cheaply with the new uid cache, so if it matters
* we should be checking for it. -DaveM
*/
old_user = current->user;
atomic_inc(&new_user->processes);
atomic_dec(&old_user->processes);
switch_uid_keyring(new_user);
current->user = new_user;
sched_switch_user(current);
/*
* We need to synchronize with __sigqueue_alloc()
* doing a get_uid(p->user).. If that saw the old
* user value, we need to wait until it has exited
* its critical region before we can free the old
* structure.
*/
smp_mb();
spin_unlock_wait(&current->sighand->siglock);
free_uid(old_user);
suid_keys(current);
}
#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);