1 files changed, 409 insertions, 0 deletions
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
new file mode 100644
index 000000000..a65ba137f
--- /dev/null
+++ b/kernel/pid_namespace.c
@@ -0,0 +1,409 @@
+/*
+ * Pid namespaces
+ *
+ * Authors:
+ *    (C) 2007 Pavel Emelyanov <xemul@openvz.org>, OpenVZ, SWsoft Inc.
+ *    (C) 2007 Sukadev Bhattiprolu <sukadev@us.ibm.com>, IBM
+ *     Many thanks to Oleg Nesterov for comments and help
+ *
+ */
+
+#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>
+#include <linux/slab.h>
+#include <linux/proc_ns.h>
+#include <linux/reboot.h>
+#include <linux/export.h>
+
+struct pid_cache {
+	int nr_ids;
+	char name[16];
+	struct kmem_cache *cachep;
+	struct list_head list;
+};
+
+static LIST_HEAD(pid_caches_lh);
+static DEFINE_MUTEX(pid_caches_mutex);
+static struct kmem_cache *pid_ns_cachep;
+
+/*
+ * creates the kmem cache to allocate pids from.
+ * @nr_ids: the number of numerical ids this pid will have to carry
+ */
+
+static struct kmem_cache *create_pid_cachep(int nr_ids)
+{
+	struct pid_cache *pcache;
+	struct kmem_cache *cachep;
+
+	mutex_lock(&pid_caches_mutex);
+	list_for_each_entry(pcache, &pid_caches_lh, list)
+		if (pcache->nr_ids == nr_ids)
+			goto out;
+
+	pcache = kmalloc(sizeof(struct pid_cache), GFP_KERNEL);
+	if (pcache == NULL)
+		goto err_alloc;
+
+	snprintf(pcache->name, sizeof(pcache->name), "pid_%d", nr_ids);
+	cachep = kmem_cache_create(pcache->name,
+			sizeof(struct pid) + (nr_ids - 1) * sizeof(struct upid),
+			0, SLAB_HWCACHE_ALIGN, NULL);
+	if (cachep == NULL)
+		goto err_cachep;
+
+	pcache->nr_ids = nr_ids;
+	pcache->cachep = cachep;
+	list_add(&pcache->list, &pid_caches_lh);
+out:
+	mutex_unlock(&pid_caches_mutex);
+	return pcache->cachep;
+
+err_cachep:
+	kfree(pcache);
+err_alloc:
+	mutex_unlock(&pid_caches_mutex);
+	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 user_namespace *user_ns,
+	struct pid_namespace *parent_pid_ns)
+{
+	struct pid_namespace *ns;
+	unsigned int level = parent_pid_ns->level + 1;
+	int i;
+	int err;
+
+	if (level > MAX_PID_NS_LEVEL) {
+		err = -EINVAL;
+		goto out;
+	}
+
+	err = -ENOMEM;
+	ns = kmem_cache_zalloc(pid_ns_cachep, GFP_KERNEL);
+	if (ns == NULL)
+		goto out;
+
+	ns->pidmap[0].page = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!ns->pidmap[0].page)
+		goto out_free;
+
+	ns->pid_cachep = create_pid_cachep(level + 1);
+	if (ns->pid_cachep == NULL)
+		goto out_free_map;
+
+	err = ns_alloc_inum(&ns->ns);
+	if (err)
+		goto out_free_map;
+	ns->ns.ops = &pidns_operations;
+
+	kref_init(&ns->kref);
+	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);
+	atomic_set(&ns->pidmap[0].nr_free, BITS_PER_PAGE - 1);
+
+	for (i = 1; i < PIDMAP_ENTRIES; i++)
+		atomic_set(&ns->pidmap[i].nr_free, BITS_PER_PAGE);
+
+	return ns;
+
+out_free_map:
+	kfree(ns->pidmap[0].page);
+out_free:
+	kmem_cache_free(pid_ns_cachep, ns);
+out:
+	return ERR_PTR(err);
+}
+
+static void delayed_free_pidns(struct rcu_head *p)
+{
+	kmem_cache_free(pid_ns_cachep,
+			container_of(p, struct pid_namespace, rcu));
+}
+
+static void destroy_pid_namespace(struct pid_namespace *ns)
+{
+	int i;
+
+	ns_free_inum(&ns->ns);
+	for (i = 0; i < PIDMAP_ENTRIES; i++)
+		kfree(ns->pidmap[i].page);
+	put_user_ns(ns->user_ns);
+	call_rcu(&ns->rcu, delayed_free_pidns);
+}
+
+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 (task_active_pid_ns(current) != old_ns)
+		return ERR_PTR(-EINVAL);
+	return create_pid_namespace(user_ns, old_ns);
+}
+
+static void free_pid_ns(struct kref *kref)
+{
+	struct pid_namespace *ns;
+
+	ns = container_of(kref, struct pid_namespace, kref);
+	destroy_pid_namespace(ns);
+}
+
+void put_pid_ns(struct pid_namespace *ns)
+{
+	struct pid_namespace *parent;
+
+	while (ns != &init_pid_ns) {
+		parent = ns->parent;
+		if (!kref_put(&ns->kref, free_pid_ns))
+			break;
+		ns = parent;
+	}
+}
+EXPORT_SYMBOL_GPL(put_pid_ns);
+
+void zap_pid_ns_processes(struct pid_namespace *pid_ns)
+{
+	int nr;
+	int rc;
+	struct task_struct *task, *me = current;
+	int init_pids = thread_group_leader(me) ? 1 : 2;
+
+	/* Don't allow any more processes into the pid namespace */
+	disable_pid_allocation(pid_ns);
+
+	/*
+	 * Ignore SIGCHLD causing any terminated children to autoreap.
+	 * This speeds up the namespace shutdown, plus see the comment
+	 * below.
+	 */
+	spin_lock_irq(&me->sighand->siglock);
+	me->sighand->action[SIGCHLD - 1].sa.sa_handler = SIG_IGN;
+	spin_unlock_irq(&me->sighand->siglock);
+
+	/*
+	 * The last thread in the cgroup-init thread group is terminating.
+	 * Find remaining pid_ts in the namespace, signal and wait for them
+	 * to exit.
+	 *
+	 * Note:  This signals each threads in the namespace - even those that
+	 * 	  belong to the same thread group, To avoid this, we would have
+	 * 	  to walk the entire tasklist looking a processes in this
+	 * 	  namespace, but that could be unnecessarily expensive if the
+	 * 	  pid namespace has just a few processes. Or we need to
+	 * 	  maintain a tasklist for each pid namespace.
+	 *
+	 */
+	read_lock(&tasklist_lock);
+	nr = next_pidmap(pid_ns, 1);
+	while (nr > 0) {
+		rcu_read_lock();
+
+		task = pid_task(find_vpid(nr), PIDTYPE_PID);
+		if (task && !__fatal_signal_pending(task))
+			send_sig_info(SIGKILL, SEND_SIG_FORCED, task);
+
+		rcu_read_unlock();
+
+		nr = next_pidmap(pid_ns, nr);
+	}
+	read_unlock(&tasklist_lock);
+
+	/*
+	 * Reap the EXIT_ZOMBIE children we had before we ignored SIGCHLD.
+	 * sys_wait4() will also block until our children traced from the
+	 * parent namespace are detached and become EXIT_DEAD.
+	 */
+	do {
+		clear_thread_flag(TIF_SIGPENDING);
+		rc = sys_wait4(-1, NULL, __WALL, NULL);
+	} while (rc != -ECHILD);
+
+	/*
+	 * sys_wait4() above can't reap the EXIT_DEAD children but we do not
+	 * really care, we could reparent them to the global init. We could
+	 * exit and reap ->child_reaper even if it is not the last thread in
+	 * this pid_ns, free_pid(nr_hashed == 0) calls proc_cleanup_work(),
+	 * pid_ns can not go away until proc_kill_sb() drops the reference.
+	 *
+	 * But this ns can also have other tasks injected by setns()+fork().
+	 * Again, ignoring the user visible semantics we do not really need
+	 * to wait until they are all reaped, but they can be reparented to
+	 * us and thus we need to ensure that pid->child_reaper stays valid
+	 * until they all go away. See free_pid()->wake_up_process().
+	 *
+	 * We rely on ignored SIGCHLD, an injected zombie must be autoreaped
+	 * if reparented.
+	 */
+	for (;;) {
+		set_current_state(TASK_UNINTERRUPTIBLE);
+		if (pid_ns->nr_hashed == init_pids)
+			break;
+		schedule();
+	}
+	__set_current_state(TASK_RUNNING);
+
+	if (pid_ns->reboot)
+		current->signal->group_exit_code = pid_ns->reboot;
+
+	acct_exit_ns(pid_ns);
+	return;
+}
+
+#ifdef CONFIG_CHECKPOINT_RESTORE
+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 && !ns_capable(pid_ns->user_ns, CAP_SYS_ADMIN))
+		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.
+	 */
+
+	tmp.data = &pid_ns->last_pid;
+	return proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
+}
+
+extern int pid_max;
+static int zero = 0;
+static 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 = &zero,
+		.extra2 = &pid_max,
+	},
+	{ }
+};
+static struct ctl_path kern_path[] = { { .procname = "kernel", }, { } };
+#endif	/* CONFIG_CHECKPOINT_RESTORE */
+
+int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd)
+{
+	if (pid_ns == &init_pid_ns)
+		return 0;
+
+	switch (cmd) {
+	case LINUX_REBOOT_CMD_RESTART2:
+	case LINUX_REBOOT_CMD_RESTART:
+		pid_ns->reboot = SIGHUP;
+		break;
+
+	case LINUX_REBOOT_CMD_POWER_OFF:
+	case LINUX_REBOOT_CMD_HALT:
+		pid_ns->reboot = SIGINT;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	read_lock(&tasklist_lock);
+	force_sig(SIGKILL, pid_ns->child_reaper);
+	read_unlock(&tasklist_lock);
+
+	do_exit(0);
+
+	/* Not reached */
+	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;
+
+	rcu_read_lock();
+	ns = task_active_pid_ns(task);
+	if (ns)
+		get_pid_ns(ns);
+	rcu_read_unlock();
+
+	return ns ? &ns->ns : NULL;
+}
+
+static void pidns_put(struct ns_common *ns)
+{
+	put_pid_ns(to_pid_ns(ns));
+}
+
+static int pidns_install(struct nsproxy *nsproxy, struct ns_common *ns)
+{
+	struct pid_namespace *active = task_active_pid_ns(current);
+	struct pid_namespace *ancestor, *new = to_pid_ns(ns);
+
+	if (!ns_capable(new->user_ns, CAP_SYS_ADMIN) ||
+	    !ns_capable(current_user_ns(), 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_for_children);
+	nsproxy->pid_ns_for_children = get_pid_ns(new);
+	return 0;
+}
+
+const struct proc_ns_operations pidns_operations = {
+	.name		= "pid",
+	.type		= CLONE_NEWPID,
+	.get		= pidns_get,
+	.put		= pidns_put,
+	.install	= pidns_install,
+};
+
+static __init int pid_namespaces_init(void)
+{
+	pid_ns_cachep = KMEM_CACHE(pid_namespace, SLAB_PANIC);
+
+#ifdef CONFIG_CHECKPOINT_RESTORE
+	register_sysctl_paths(kern_path, pid_ns_ctl_table);
+#endif
+	return 0;
+}
+
+__initcall(pid_namespaces_init);