X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=kernel%2Fuser.c;h=7e72614b736d82dd108d99ab79daefa55e6cdfe3;hb=af507ae8a0512a83728b17d8f8c5fa1561669f50;hp=4869563080e9e080954d26f34b70bbffc13de18b;hpb=e18b890bb0881bbab6f4f1a6cd20d9c60d66b003;p=safe%2Fjmp%2Flinux-2.6 diff --git a/kernel/user.c b/kernel/user.c index 4869563..7e72614 100644 --- a/kernel/user.c +++ b/kernel/user.c @@ -14,20 +14,27 @@ #include #include #include +#include +#include + +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 struct list_head uidhash_table[UIDHASH_SZ]; /* * The uidhash_lock is mostly taken from process context, but it is @@ -40,42 +47,37 @@ static struct list_head uidhash_table[UIDHASH_SZ]; */ 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; } @@ -84,6 +86,19 @@ static inline struct user_struct *uid_hash_find(uid_t uid, struct list_head *has 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(). @@ -94,9 +109,10 @@ struct user_struct *find_user(uid_t uid) { struct user_struct *ret; unsigned long flags; + struct user_namespace *ns = current_user_ns(); spin_lock_irqsave(&uidhash_lock, flags); - ret = uid_hash_find(uid, uidhashentry(uid)); + ret = uid_hash_find(uid, uidhashentry(ns, uid)); spin_unlock_irqrestore(&uidhash_lock, flags); return ret; } @@ -109,49 +125,30 @@ void free_uid(struct user_struct *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); - } else { + 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_irq(&uidhash_lock); up = uid_hash_find(uid, hashent); spin_unlock_irq(&uidhash_lock); if (!up) { - struct user_struct *new; - - new = kmem_cache_alloc(uid_cachep, GFP_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_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, current) < 0) { - kmem_cache_free(uid_cachep, new); - return NULL; - } + + new->user_ns = get_user_ns(ns); /* * Before adding this, check whether we raced @@ -168,54 +165,27 @@ struct user_struct * alloc_uid(uid_t uid) up = new; } 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; - - /* - * 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); +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_irq(&uidhash_lock); - uid_hash_insert(&root_user, uidhashentry(0)); + uid_hash_insert(&root_user, uidhashentry(&init_user_ns, 0)); spin_unlock_irq(&uidhash_lock); return 0;