1 files changed, 57 insertions, 57 deletions

diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index 619972c78774..e48f5de41361 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -23,6 +23,8 @@
 #include <linux/sched/task.h>
 #include <linux/sched/signal.h>
 #include <linux/idr.h>
+#include <linux/nstree.h>
+#include <uapi/linux/wait.h>
 #include "pid_sysctl.h"
 
 static DEFINE_MUTEX(pid_caches_mutex);
@@ -69,6 +71,8 @@ static void dec_pid_namespaces(struct ucounts *ucounts)
 	dec_ucount(ucounts, UCOUNT_PID_NAMESPACES);
 }
 
+static void destroy_pid_namespace_work(struct work_struct *work);
+
 static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns,
 	struct pid_namespace *parent_pid_ns)
 {
@@ -99,22 +103,31 @@ static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns
 	if (ns->pid_cachep == NULL)
 		goto out_free_idr;
 
-	err = ns_alloc_inum(&ns->ns);
+	err = ns_common_init(ns);
 	if (err)
 		goto out_free_idr;
-	ns->ns.ops = &pidns_operations;
 
-	refcount_set(&ns->ns.count, 1);
+	ns->pid_max = PID_MAX_LIMIT;
+	err = register_pidns_sysctls(ns);
+	if (err)
+		goto out_free_inum;
+
 	ns->level = level;
 	ns->parent = get_pid_ns(parent_pid_ns);
 	ns->user_ns = get_user_ns(user_ns);
 	ns->ucounts = ucounts;
 	ns->pid_allocated = PIDNS_ADDING;
+	INIT_WORK(&ns->work, destroy_pid_namespace_work);
+
 #if defined(CONFIG_SYSCTL) && defined(CONFIG_MEMFD_CREATE)
 	ns->memfd_noexec_scope = pidns_memfd_noexec_scope(parent_pid_ns);
 #endif
+
+	ns_tree_add(ns);
 	return ns;
 
+out_free_inum:
+	ns_common_free(ns);
 out_free_idr:
 	idr_destroy(&ns->idr);
 	kmem_cache_free(pid_ns_cachep, ns);
@@ -136,13 +149,30 @@ static void delayed_free_pidns(struct rcu_head *p)
 
 static void destroy_pid_namespace(struct pid_namespace *ns)
 {
-	ns_free_inum(&ns->ns);
+	ns_tree_remove(ns);
+	unregister_pidns_sysctls(ns);
+
+	ns_common_free(ns);
 
 	idr_destroy(&ns->idr);
 	call_rcu(&ns->rcu, delayed_free_pidns);
 }
 
-struct pid_namespace *copy_pid_ns(unsigned long flags,
+static void destroy_pid_namespace_work(struct work_struct *work)
+{
+	struct pid_namespace *ns =
+		container_of(work, struct pid_namespace, work);
+
+	do {
+		struct pid_namespace *parent;
+
+		parent = ns->parent;
+		destroy_pid_namespace(ns);
+		ns = parent;
+	} while (ns != &init_pid_ns && ns_ref_put(ns));
+}
+
+struct pid_namespace *copy_pid_ns(u64 flags,
 	struct user_namespace *user_ns, struct pid_namespace *old_ns)
 {
 	if (!(flags & CLONE_NEWPID))
@@ -154,15 +184,8 @@ struct pid_namespace *copy_pid_ns(unsigned long flags,
 
 void put_pid_ns(struct pid_namespace *ns)
 {
-	struct pid_namespace *parent;
-
-	while (ns != &init_pid_ns) {
-		parent = ns->parent;
-		if (!refcount_dec_and_test(&ns->ns.count))
-			break;
-		destroy_pid_namespace(ns);
-		ns = parent;
-	}
+	if (ns && ns_ref_put(ns))
+		schedule_work(&ns->work);
 }
 EXPORT_SYMBOL_GPL(put_pid_ns);
 
@@ -217,6 +240,7 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns)
 	 */
 	do {
 		clear_thread_flag(TIF_SIGPENDING);
+		clear_thread_flag(TIF_NOTIFY_SIGNAL);
 		rc = kernel_wait4(-1, NULL, __WALL, NULL);
 	} while (rc != -ECHILD);
 
@@ -247,24 +271,7 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns)
 		set_current_state(TASK_INTERRUPTIBLE);
 		if (pid_ns->pid_allocated == init_pids)
 			break;
-		/*
-		 * Release tasks_rcu_exit_srcu to avoid following deadlock:
-		 *
-		 * 1) TASK A unshare(CLONE_NEWPID)
-		 * 2) TASK A fork() twice -> TASK B (child reaper for new ns)
-		 *    and TASK C
-		 * 3) TASK B exits, kills TASK C, waits for TASK A to reap it
-		 * 4) TASK A calls synchronize_rcu_tasks()
-		 *                   -> synchronize_srcu(tasks_rcu_exit_srcu)
-		 * 5) *DEADLOCK*
-		 *
-		 * It is considered safe to release tasks_rcu_exit_srcu here
-		 * because we assume the current task can not be concurrently
-		 * reaped at this point.
-		 */
-		exit_tasks_rcu_stop();
 		schedule();
-		exit_tasks_rcu_start();
 	}
 	__set_current_state(TASK_RUNNING);
 
@@ -276,7 +283,7 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns)
 }
 
 #ifdef CONFIG_CHECKPOINT_RESTORE
-static int pid_ns_ctl_handler(struct ctl_table *table, int write,
+static int pid_ns_ctl_handler(const struct ctl_table *table, int write,
 		void *buffer, size_t *lenp, loff_t *ppos)
 {
 	struct pid_namespace *pid_ns = task_active_pid_ns(current);
@@ -286,15 +293,10 @@ static int pid_ns_ctl_handler(struct ctl_table *table, int write,
 	if (write && !checkpoint_restore_ns_capable(pid_ns->user_ns))
 		return -EPERM;
 
-	/*
-	 * Writing directly to ns' last_pid field is OK, since this field
-	 * is volatile in a living namespace anyway and a code writing to
-	 * it should synchronize its usage with external means.
-	 */
-
 	next = idr_get_cursor(&pid_ns->idr) - 1;
 
 	tmp.data = &next;
+	tmp.extra2 = &pid_ns->pid_max;
 	ret = proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
 	if (!ret && write)
 		idr_set_cursor(&pid_ns->idr, next + 1);
@@ -302,17 +304,15 @@ static int pid_ns_ctl_handler(struct ctl_table *table, int write,
 	return ret;
 }
 
-extern int pid_max;
-static struct ctl_table pid_ns_ctl_table[] = {
+static const struct ctl_table pid_ns_ctl_table[] = {
 	{
 		.procname = "ns_last_pid",
 		.maxlen = sizeof(int),
 		.mode = 0666, /* permissions are checked in the handler */
 		.proc_handler = pid_ns_ctl_handler,
 		.extra1 = SYSCTL_ZERO,
-		.extra2 = &pid_max,
+		.extra2 = &init_pid_ns.pid_max,
 	},
-	{ }
 };
 #endif	/* CONFIG_CHECKPOINT_RESTORE */
 
@@ -345,11 +345,6 @@ int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd)
 	return 0;
 }
 
-static inline struct pid_namespace *to_pid_ns(struct ns_common *ns)
-{
-	return container_of(ns, struct pid_namespace, ns);
-}
-
 static struct ns_common *pidns_get(struct task_struct *task)
 {
 	struct pid_namespace *ns;
@@ -391,11 +386,23 @@ static void pidns_put(struct ns_common *ns)
 	put_pid_ns(to_pid_ns(ns));
 }
 
+bool pidns_is_ancestor(struct pid_namespace *child,
+		       struct pid_namespace *ancestor)
+{
+	struct pid_namespace *ns;
+
+	if (child->level < ancestor->level)
+		return false;
+	for (ns = child; ns->level > ancestor->level; ns = ns->parent)
+		;
+	return ns == ancestor;
+}
+
 static int pidns_install(struct nsset *nsset, struct ns_common *ns)
 {
 	struct nsproxy *nsproxy = nsset->nsproxy;
 	struct pid_namespace *active = task_active_pid_ns(current);
-	struct pid_namespace *ancestor, *new = to_pid_ns(ns);
+	struct pid_namespace *new = to_pid_ns(ns);
 
 	if (!ns_capable(new->user_ns, CAP_SYS_ADMIN) ||
 	    !ns_capable(nsset->cred->user_ns, CAP_SYS_ADMIN))
@@ -409,13 +416,7 @@ static int pidns_install(struct nsset *nsset, struct ns_common *ns)
 	 * this maintains the property that processes and their
 	 * children can not escape their current pid namespace.
 	 */
-	if (new->level < active->level)
-		return -EINVAL;
-
-	ancestor = new;
-	while (ancestor->level > active->level)
-		ancestor = ancestor->parent;
-	if (ancestor != active)
+	if (!pidns_is_ancestor(new, active))
 		return -EINVAL;
 
 	put_pid_ns(nsproxy->pid_ns_for_children);
@@ -448,7 +449,6 @@ static struct user_namespace *pidns_owner(struct ns_common *ns)
 
 const struct proc_ns_operations pidns_operations = {
 	.name		= "pid",
-	.type		= CLONE_NEWPID,
 	.get		= pidns_get,
 	.put		= pidns_put,
 	.install	= pidns_install,
@@ -459,7 +459,6 @@ const struct proc_ns_operations pidns_operations = {
 const struct proc_ns_operations pidns_for_children_operations = {
 	.name		= "pid_for_children",
 	.real_ns_name	= "pid",
-	.type		= CLONE_NEWPID,
 	.get		= pidns_for_children_get,
 	.put		= pidns_put,
 	.install	= pidns_install,
@@ -476,6 +475,7 @@ static __init int pid_namespaces_init(void)
 #endif
 
 	register_pid_ns_sysctl_table_vm();
+	ns_tree_add(&init_pid_ns);
 	return 0;
 }