diff options
| -rw-r--r-- | include/linux/pid.h | 1 | ||||
| -rw-r--r-- | include/linux/pid_namespace.h | 4 | ||||
| -rw-r--r-- | kernel/pid.c | 15 | ||||
| -rw-r--r-- | kernel/pid_namespace.c | 4 |
4 files changed, 20 insertions, 4 deletions
diff --git a/include/linux/pid.h b/include/linux/pid.h index b152d44fb18..2381c973d89 100644 --- a/include/linux/pid.h +++ b/include/linux/pid.h @@ -121,6 +121,7 @@ int next_pidmap(struct pid_namespace *pid_ns, unsigned int last); extern struct pid *alloc_pid(struct pid_namespace *ns); extern void free_pid(struct pid *pid); +extern void disable_pid_allocation(struct pid_namespace *ns); /* * ns_of_pid() returns the pid namespace in which the specified pid was diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h index bf285999273..215e5e3dda1 100644 --- a/include/linux/pid_namespace.h +++ b/include/linux/pid_namespace.h @@ -21,7 +21,7 @@ struct pid_namespace { struct kref kref; struct pidmap pidmap[PIDMAP_ENTRIES]; int last_pid; - int nr_hashed; + unsigned int nr_hashed; struct task_struct *child_reaper; struct kmem_cache *pid_cachep; unsigned int level; @@ -42,6 +42,8 @@ struct pid_namespace { extern struct pid_namespace init_pid_ns; +#define PIDNS_HASH_ADDING (1U << 31) + #ifdef CONFIG_PID_NS static inline struct pid_namespace *get_pid_ns(struct pid_namespace *ns) { diff --git a/kernel/pid.c b/kernel/pid.c index 36aa02ff17d..de9af600006 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -270,7 +270,6 @@ void free_pid(struct pid *pid) wake_up_process(ns->child_reaper); break; case 0: - ns->nr_hashed = -1; schedule_work(&ns->proc_work); break; } @@ -319,7 +318,7 @@ struct pid *alloc_pid(struct pid_namespace *ns) upid = pid->numbers + ns->level; spin_lock_irq(&pidmap_lock); - if (ns->nr_hashed < 0) + if (!(ns->nr_hashed & PIDNS_HASH_ADDING)) goto out_unlock; for ( ; upid >= pid->numbers; --upid) { hlist_add_head_rcu(&upid->pid_chain, @@ -342,6 +341,13 @@ out_free: goto out; } +void disable_pid_allocation(struct pid_namespace *ns) +{ + spin_lock_irq(&pidmap_lock); + ns->nr_hashed &= ~PIDNS_HASH_ADDING; + spin_unlock_irq(&pidmap_lock); +} + struct pid *find_pid_ns(int nr, struct pid_namespace *ns) { struct hlist_node *elem; @@ -573,6 +579,9 @@ void __init pidhash_init(void) void __init pidmap_init(void) { + /* Veryify no one has done anything silly */ + BUILD_BUG_ON(PID_MAX_LIMIT >= PIDNS_HASH_ADDING); + /* bump default and minimum pid_max based on number of cpus */ pid_max = min(pid_max_max, max_t(int, pid_max, PIDS_PER_CPU_DEFAULT * num_possible_cpus())); @@ -584,7 +593,7 @@ void __init pidmap_init(void) /* Reserve PID 0. We never call free_pidmap(0) */ set_bit(0, init_pid_ns.pidmap[0].page); atomic_dec(&init_pid_ns.pidmap[0].nr_free); - init_pid_ns.nr_hashed = 1; + init_pid_ns.nr_hashed = PIDNS_HASH_ADDING; init_pid_ns.pid_cachep = KMEM_CACHE(pid, SLAB_HWCACHE_ALIGN | SLAB_PANIC); diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c index fdbd0cdf271..c1c3dc1c602 100644 --- a/kernel/pid_namespace.c +++ b/kernel/pid_namespace.c @@ -115,6 +115,7 @@ static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns ns->level = level; ns->parent = get_pid_ns(parent_pid_ns); ns->user_ns = get_user_ns(user_ns); + ns->nr_hashed = PIDNS_HASH_ADDING; INIT_WORK(&ns->proc_work, proc_cleanup_work); set_bit(0, ns->pidmap[0].page); @@ -181,6 +182,9 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns) int rc; struct task_struct *task, *me = current; + /* Don't allow any more processes into the pid namespace */ + disable_pid_allocation(pid_ns); + /* Ignore SIGCHLD causing any terminated children to autoreap */ spin_lock_irq(&me->sighand->siglock); me->sighand->action[SIGCHLD - 1].sa.sa_handler = SIG_IGN; |