#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),
+ },
+ .creator = &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_BITS (CONFIG_BASE_SMALL ? 3 : 8)
-#define UIDHASH_SZ (1 << UIDHASH_BITS)
#define UIDHASH_MASK (UIDHASH_SZ - 1)
#define __uidhashfn(uid) (((uid >> UIDHASH_BITS) + uid) & UIDHASH_MASK)
-#define uidhashentry(uid) (uidhash_table + __uidhashfn((uid)))
+#define uidhashentry(ns, uid) ((ns)->uidhash_table + __uidhashfn((uid)))
+
+static struct kmem_cache *uid_cachep;
-static kmem_cache_t *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);
+/* root_user.__count is 2, 1 for init task cred, 1 for init_user_ns->creator */
struct user_struct root_user = {
- .__count = ATOMIC_INIT(1),
+ .__count = ATOMIC_INIT(2),
.processes = ATOMIC_INIT(1),
.files = ATOMIC_INIT(0),
.sigpending = ATOMIC_INIT(0),
- .mq_bytes = 0,
.locked_shm = 0,
-#ifdef CONFIG_KEYS
- .uid_keyring = &root_user_keyring,
- .session_keyring = &root_session_keyring,
-#endif
+ .user_ns = &init_user_ns,
};
/*
* These routines must be called with the uidhash spinlock held!
*/
-static inline void uid_hash_insert(struct user_struct *up, struct list_head *hashent)
+static void uid_hash_insert(struct user_struct *up, struct hlist_head *hashent)
{
- list_add(&up->uidhash_list, hashent);
+ hlist_add_head(&up->uidhash_node, hashent);
}
-static inline void uid_hash_remove(struct user_struct *up)
+static void uid_hash_remove(struct user_struct *up)
{
- list_del(&up->uidhash_list);
+ hlist_del_init(&up->uidhash_node);
+ put_user_ns(up->user_ns);
}
-static inline struct user_struct *uid_hash_find(uid_t uid, struct list_head *hashent)
+static struct user_struct *uid_hash_find(uid_t uid, struct hlist_head *hashent)
{
- struct list_head *up;
-
- list_for_each(up, hashent) {
- struct user_struct *user;
-
- user = list_entry(up, struct user_struct, uidhash_list);
+ struct user_struct *user;
+ struct hlist_node *h;
- if(user->uid == uid) {
+ hlist_for_each_entry(user, h, hashent, uidhash_node) {
+ if (user->uid == uid) {
atomic_inc(&user->__count);
return user;
}
return NULL;
}
+/* 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 void free_user(struct user_struct *up, unsigned long flags)
+{
+ 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);
+}
+
/*
* Locate the user_struct for the passed UID. If found, take a ref on it. The
* caller must undo that ref with free_uid().
struct user_struct *find_user(uid_t uid)
{
struct user_struct *ret;
+ unsigned long flags;
+ struct user_namespace *ns = current_user_ns();
- spin_lock(&uidhash_lock);
- ret = uid_hash_find(uid, uidhashentry(uid));
- spin_unlock(&uidhash_lock);
+ 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)
{
- if (up && atomic_dec_and_lock(&up->__count, &uidhash_lock)) {
- uid_hash_remove(up);
- key_put(up->uid_keyring);
- key_put(up->session_keyring);
- kmem_cache_free(uid_cachep, up);
- spin_unlock(&uidhash_lock);
- }
+ 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(uid_t uid)
+struct user_struct *alloc_uid(struct user_namespace *ns, uid_t uid)
{
- struct list_head *hashent = uidhashentry(uid);
- struct user_struct *up;
+ struct hlist_head *hashent = uidhashentry(ns, uid);
+ struct user_struct *up, *new;
- spin_lock(&uidhash_lock);
+ spin_lock_irq(&uidhash_lock);
up = uid_hash_find(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_zalloc(uid_cachep, GFP_KERNEL);
if (!new)
- return NULL;
+ 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
- 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) {
- kmem_cache_free(uid_cachep, new);
- return NULL;
- }
+
+ new->user_ns = get_user_ns(ns);
/*
* 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(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;
-}
-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;
- free_uid(old_user);
- suid_keys(current);
+out_unlock:
+ return NULL;
}
-
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, NULL);
+ 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
for(n = 0; n < UIDHASH_SZ; ++n)
- INIT_LIST_HEAD(uidhash_table + n);
+ INIT_HLIST_HEAD(init_user_ns.uidhash_table + n);
/* Insert the root user immediately (init already runs as root) */
- spin_lock(&uidhash_lock);
- uid_hash_insert(&root_user, uidhashentry(0));
- spin_unlock(&uidhash_lock);
+ spin_lock_irq(&uidhash_lock);
+ uid_hash_insert(&root_user, uidhashentry(&init_user_ns, 0));
+ spin_unlock_irq(&uidhash_lock);
return 0;
}
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff