X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=kernel%2Fuser.c;h=0f3aa0234107e3742b7727565b8343539df122c9;hb=adb34022eb7a11126fecef6b5abb4741a17360c6;hp=89e562feb1b10829ec3d689eb969f670868be686;hpb=0eeca28300df110bd6ed54b31193c83b87921443;p=safe%2Fjmp%2Flinux-2.6 diff --git a/kernel/user.c b/kernel/user.c index 89e562f..0f3aa02 100644 --- a/kernel/user.c +++ b/kernel/user.c @@ -13,20 +13,30 @@ #include #include #include +#include +#include +#include /* * 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 kmem_cache_t *uid_cachep; -static struct list_head uidhash_table[UIDHASH_SZ]; +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 = { @@ -34,37 +44,36 @@ struct user_struct root_user = { .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 +#ifdef CONFIG_FAIR_USER_SCHED + .tg = &init_task_group, +#endif }; /* * 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); } -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; + struct user_struct *user; + struct hlist_node *h; - list_for_each(up, hashent) { - struct user_struct *user; - - user = list_entry(up, struct user_struct, uidhash_list); - - if(user->uid == uid) { + hlist_for_each_entry(user, h, hashent, uidhash_node) { + if (user->uid == uid) { atomic_inc(&user->__count); return user; } @@ -73,6 +82,211 @@ static inline struct user_struct *uid_hash_find(uid_t uid, struct list_head *has 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 kobject uids_kobject; /* represents /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); +} + +/* return cpu shares held by the user */ +static ssize_t cpu_shares_show(struct kset *kset, char *buffer) +{ + struct user_struct *up = container_of(kset, struct user_struct, kset); + + return sprintf(buffer, "%lu\n", sched_group_shares(up->tg)); +} + +/* modify cpu shares held by the user */ +static ssize_t cpu_shares_store(struct kset *kset, const char *buffer, + size_t size) +{ + struct user_struct *up = container_of(kset, struct user_struct, kset); + unsigned long shares; + int rc; + + sscanf(buffer, "%lu", &shares); + + rc = sched_group_set_shares(up->tg, shares); + + return (rc ? rc : size); +} + +static void user_attr_init(struct subsys_attribute *sa, char *name, int mode) +{ + sa->attr.name = name; + sa->attr.mode = mode; + sa->show = cpu_shares_show; + sa->store = cpu_shares_store; +} + +/* Create "/sys/kernel/uids/" directory and + * "/sys/kernel/uids//cpu_share" file for this user. + */ +static int user_kobject_create(struct user_struct *up) +{ + struct kset *kset = &up->kset; + struct kobject *kobj = &kset->kobj; + int error; + + memset(kset, 0, sizeof(struct kset)); + kobj->parent = &uids_kobject; /* create under /sys/kernel/uids dir */ + kobject_set_name(kobj, "%d", up->uid); + kset_init(kset); + user_attr_init(&up->user_attr, "cpu_share", 0644); + + error = kobject_add(kobj); + if (error) + goto done; + + error = sysfs_create_file(kobj, &up->user_attr.attr); + if (error) + kobject_del(kobj); + + kobject_uevent(kobj, KOBJ_ADD); + +done: + return error; +} + +/* create these in sysfs filesystem: + * "/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_kobject_init(void) +{ + int error; + + /* create under /sys/kernel dir */ + uids_kobject.parent = &kernel_subsys.kobj; + uids_kobject.kset = &kernel_subsys; + kobject_set_name(&uids_kobject, "uids"); + kobject_init(&uids_kobject); + + error = kobject_add(&uids_kobject); + if (!error) + error = user_kobject_create(&root_user); + + return error; +} + +/* 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); + struct kobject *kobj = &up->kset.kobj; + 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; + + sysfs_remove_file(kobj, &up->user_attr.attr); + kobject_uevent(kobj, KOBJ_REMOVE); + kobject_del(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 */ + +static inline int user_kobject_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(). @@ -82,37 +296,47 @@ static inline struct user_struct *uid_hash_find(uid_t uid, struct list_head *has 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(&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 hlist_head *hashent = uidhashentry(ns, uid); struct user_struct *up; - spin_lock(&uidhash_lock); + /* Make uid_hash_find() + user_kobject_create() + uid_hash_insert() + * atomic. + */ + uids_mutex_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_alloc(uid_cachep, GFP_KERNEL); if (!new) return NULL; new->uid = uid; @@ -120,16 +344,33 @@ struct user_struct * alloc_uid(uid_t uid) atomic_set(&new->processes, 0); atomic_set(&new->files, 0); atomic_set(&new->sigpending, 0); -#ifdef CONFIG_INOTIFY +#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) < 0) { + if (alloc_uid_keyring(new, current) < 0) { + kmem_cache_free(uid_cachep, new); + return NULL; + } + + if (sched_create_user(new) < 0) { + key_put(new->uid_keyring); + key_put(new->session_keyring); + kmem_cache_free(uid_cachep, new); + return NULL; + } + + if (user_kobject_create(new)) { + sched_destroy_user(new); + key_put(new->uid_keyring); + key_put(new->session_keyring); kmem_cache_free(uid_cachep, new); + uids_mutex_unlock(); return NULL; } @@ -137,9 +378,14 @@ struct user_struct * alloc_uid(uid_t uid) * 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) { + /* 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); @@ -147,9 +393,12 @@ struct user_struct * alloc_uid(uid_t uid) uid_hash_insert(new, hashent); up = new; } - spin_unlock(&uidhash_lock); + spin_unlock_irq(&uidhash_lock); } + + uids_mutex_unlock(); + return up; } @@ -167,25 +416,61 @@ void switch_uid(struct user_struct *new_user) 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(¤t->sighand->siglock); + free_uid(old_user); suid_keys(current); } +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); +} 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; }