#include <linux/slab.h>
#include <linux/bitops.h>
#include <linux/key.h>
+#include <linux/interrupt.h>
/*
* UID task count cache, to get fast user lookup in "alloc_uid"
#define __uidhashfn(xid,uid) ((((uid) >> UIDHASH_BITS) + ((uid)^(xid))) & UIDHASH_MASK)
#define uidhashentry(xid,uid) (uidhash_table + __uidhashfn((xid),(uid)))
-static kmem_cache_t *uid_cachep;
+static struct kmem_cache *uid_cachep;
static struct list_head uidhash_table[UIDHASH_SZ];
+
+/*
+ * 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 = {
struct user_struct *find_user(xid_t xid, uid_t uid)
{
struct user_struct *ret;
+ unsigned long flags;
- spin_lock(&uidhash_lock);
+ spin_lock_irqsave(&uidhash_lock, flags);
ret = uid_hash_find(xid, uid, uidhashentry(xid, uid));
- spin_unlock(&uidhash_lock);
+ spin_unlock_irqrestore(&uidhash_lock, flags);
return ret;
}
void free_uid(struct user_struct *up)
{
- if (up && atomic_dec_and_lock(&up->__count, &uidhash_lock)) {
+ unsigned long flags;
+
+ if (!up)
+ return;
+
+ local_irq_save(flags);
+ if (atomic_dec_and_lock(&up->__count, &uidhash_lock)) {
uid_hash_remove(up);
+ spin_unlock_irqrestore(&uidhash_lock, flags);
key_put(up->uid_keyring);
key_put(up->session_keyring);
kmem_cache_free(uid_cachep, up);
- spin_unlock(&uidhash_lock);
+ } else {
+ local_irq_restore(flags);
}
}
struct list_head *hashent = uidhashentry(xid, uid);
struct user_struct *up;
- spin_lock(&uidhash_lock);
+ spin_lock_irq(&uidhash_lock);
up = uid_hash_find(xid, uid, hashent);
- spin_unlock(&uidhash_lock);
+ spin_unlock_irq(&uidhash_lock);
if (!up) {
struct user_struct *new;
- new = kmem_cache_alloc(uid_cachep, SLAB_KERNEL);
+ new = kmem_cache_alloc(uid_cachep, GFP_KERNEL);
if (!new)
return NULL;
new->uid = uid;
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
new->mq_bytes = 0;
new->locked_shm = 0;
- if (alloc_uid_keyring(new) < 0) {
+ if (alloc_uid_keyring(new, current) < 0) {
kmem_cache_free(uid_cachep, new);
return NULL;
}
* Before adding this, check whether we raced
* on adding the same user already..
*/
- spin_lock(&uidhash_lock);
+ spin_lock_irq(&uidhash_lock);
up = uid_hash_find(xid, uid, hashent);
if (up) {
key_put(new->uid_keyring);
uid_hash_insert(new, hashent);
up = new;
}
- spin_unlock(&uidhash_lock);
+ spin_unlock_irq(&uidhash_lock);
}
return up;
atomic_dec(&old_user->processes);
switch_uid_keyring(new_user);
current->user = new_user;
+
+ /*
+ * 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(¤t->sighand->siglock);
+
free_uid(old_user);
suid_keys(current);
}
INIT_LIST_HEAD(uidhash_table + n);
/* Insert the root user immediately (init already runs as root) */
- spin_lock(&uidhash_lock);
+ spin_lock_irq(&uidhash_lock);
uid_hash_insert(&root_user, uidhashentry(0,0));
- spin_unlock(&uidhash_lock);
+ spin_unlock_irq(&uidhash_lock);
return 0;
}