1 files changed, 90 insertions, 23 deletions

diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index 7b07cc0dfb75..fdbd0cdf271a 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -10,6 +10,7 @@
 
 #include <linux/pid.h>
 #include <linux/pid_namespace.h>
+#include <linux/user_namespace.h>
 #include <linux/syscalls.h>
 #include <linux/err.h>
 #include <linux/acct.h>
@@ -71,10 +72,17 @@ err_alloc:
         return NULL;
 }
 
+static void proc_cleanup_work(struct work_struct *work)
+{
+        struct pid_namespace *ns = container_of(work, struct pid_namespace, proc_work);
+        pid_ns_release_proc(ns);
+}
+
 /* MAX_PID_NS_LEVEL is needed for limiting size of 'struct pid' */
 #define MAX_PID_NS_LEVEL 32
 
-static struct pid_namespace *create_pid_namespace(struct pid_namespace *parent_pid_ns)
+static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns,
+        struct pid_namespace *parent_pid_ns)
 {
         struct pid_namespace *ns;
         unsigned int level = parent_pid_ns->level + 1;
@@ -99,9 +107,15 @@ static struct pid_namespace *create_pid_namespace(struct pid_namespace *parent_p
         if (ns->pid_cachep == NULL)
                 goto out_free_map;
 
+        err = proc_alloc_inum(&ns->proc_inum);
+        if (err)
+                goto out_free_map;
+
         kref_init(&ns->kref);
         ns->level = level;
         ns->parent = get_pid_ns(parent_pid_ns);
+        ns->user_ns = get_user_ns(user_ns);
+        INIT_WORK(&ns->proc_work, proc_cleanup_work);
 
         set_bit(0, ns->pidmap[0].page);
         atomic_set(&ns->pidmap[0].nr_free, BITS_PER_PAGE - 1);
@@ -109,14 +123,8 @@ static struct pid_namespace *create_pid_namespace(struct pid_namespace *parent_p
         for (i = 1; i < PIDMAP_ENTRIES; i++)
                 atomic_set(&ns->pidmap[i].nr_free, BITS_PER_PAGE);
 
-        err = pid_ns_prepare_proc(ns);
-        if (err)
-                goto out_put_parent_pid_ns;
-
         return ns;
 
-out_put_parent_pid_ns:
-        put_pid_ns(parent_pid_ns);
 out_free_map:
         kfree(ns->pidmap[0].page);
 out_free:
@@ -129,18 +137,21 @@ static void destroy_pid_namespace(struct pid_namespace *ns)
 {
         int i;
 
+        proc_free_inum(ns->proc_inum);
         for (i = 0; i < PIDMAP_ENTRIES; i++)
                 kfree(ns->pidmap[i].page);
+        put_user_ns(ns->user_ns);
         kmem_cache_free(pid_ns_cachep, ns);
 }
 
-struct pid_namespace *copy_pid_ns(unsigned long flags, struct pid_namespace *old_ns)
+struct pid_namespace *copy_pid_ns(unsigned long flags,
+        struct user_namespace *user_ns, struct pid_namespace *old_ns)
 {
         if (!(flags & CLONE_NEWPID))
                 return get_pid_ns(old_ns);
-        if (flags & (CLONE_THREAD|CLONE_PARENT))
+        if (task_active_pid_ns(current) != old_ns)
                 return ERR_PTR(-EINVAL);
-        return create_pid_namespace(old_ns);
+        return create_pid_namespace(user_ns, old_ns);
 }
 
 static void free_pid_ns(struct kref *kref)
@@ -211,22 +222,15 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns)
 
         /*
          * sys_wait4() above can't reap the TASK_DEAD children.
-         * Make sure they all go away, see __unhash_process().
+         * Make sure they all go away, see free_pid().
          */
         for (;;) {
-                bool need_wait = false;
-
-                read_lock(&tasklist_lock);
-                if (!list_empty(&current->children)) {
-                        __set_current_state(TASK_UNINTERRUPTIBLE);
-                        need_wait = true;
-                }
-                read_unlock(&tasklist_lock);
-
-                if (!need_wait)
+                set_current_state(TASK_UNINTERRUPTIBLE);
+                if (pid_ns->nr_hashed == 1)
                         break;
                 schedule();
         }
+        __set_current_state(TASK_RUNNING);
 
         if (pid_ns->reboot)
                 current->signal->group_exit_code = pid_ns->reboot;
@@ -239,9 +243,10 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns)
 static int pid_ns_ctl_handler(struct ctl_table *table, int write,
                 void __user *buffer, size_t *lenp, loff_t *ppos)
 {
+        struct pid_namespace *pid_ns = task_active_pid_ns(current);
         struct ctl_table tmp = *table;
 
-        if (write && !capable(CAP_SYS_ADMIN))
+        if (write && !ns_capable(pid_ns->user_ns, CAP_SYS_ADMIN))
                 return -EPERM;
 
         /*
@@ -250,7 +255,7 @@ static int pid_ns_ctl_handler(struct ctl_table *table, int write,
          * it should synchronize its usage with external means.
          */
 
-        tmp.data = &current->nsproxy->pid_ns->last_pid;
+        tmp.data = &pid_ns->last_pid;
         return proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
 }
 
@@ -299,6 +304,68 @@ int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd)
         return 0;
 }
 
+static void *pidns_get(struct task_struct *task)
+{
+        struct pid_namespace *ns;
+
+        rcu_read_lock();
+        ns = get_pid_ns(task_active_pid_ns(task));
+        rcu_read_unlock();
+
+        return ns;
+}
+
+static void pidns_put(void *ns)
+{
+        put_pid_ns(ns);
+}
+
+static int pidns_install(struct nsproxy *nsproxy, void *ns)
+{
+        struct pid_namespace *active = task_active_pid_ns(current);
+        struct pid_namespace *ancestor, *new = ns;
+
+        if (!ns_capable(new->user_ns, CAP_SYS_ADMIN) ||
+            !nsown_capable(CAP_SYS_ADMIN))
+                return -EPERM;
+
+        /*
+         * Only allow entering the current active pid namespace
+         * or a child of the current active pid namespace.
+         *
+         * This is required for fork to return a usable pid value and
+         * 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)
+                return -EINVAL;
+
+        put_pid_ns(nsproxy->pid_ns);
+        nsproxy->pid_ns = get_pid_ns(new);
+        return 0;
+}
+
+static unsigned int pidns_inum(void *ns)
+{
+        struct pid_namespace *pid_ns = ns;
+        return pid_ns->proc_inum;
+}
+
+const struct proc_ns_operations pidns_operations = {
+        .name           = "pid",
+        .type           = CLONE_NEWPID,
+        .get            = pidns_get,
+        .put            = pidns_put,
+        .install        = pidns_install,
+        .inum           = pidns_inum,
+};
+
 static __init int pid_namespaces_init(void)
 {
         pid_ns_cachep = KMEM_CACHE(pid_namespace, SLAB_PANIC);