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Commit 70328660 authored by Eric W. Biederman's avatar Eric W. Biederman
Browse files

netns: Add a limit on the number of net namespaces 



Acked-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
parent d08311dd

include/linux/user_namespace.h

+1 −0
Original line number Diff line number Diff line
@@ -29,6 +29,7 @@ enum ucount_type { 
	UCOUNT_PID_NAMESPACES,

	UCOUNT_UTS_NAMESPACES,

	UCOUNT_IPC_NAMESPACES,

	UCOUNT_NET_NAMESPACES,

	UCOUNT_CGROUP_NAMESPACES,

	UCOUNT_COUNTS,

};

include/net/net_namespace.h

+1 −0
Original line number Diff line number Diff line
@@ -60,6 +60,7 @@ struct net { 
	struct list_head	exit_list;	/* Use only net_mutex */



	struct user_namespace   *user_ns;	/* Owning user namespace */

	struct ucounts		*ucounts;

	spinlock_t		nsid_lock;

	struct idr		netns_ids;

kernel/ucount.c

+1 −0
Original line number Diff line number Diff line
@@ -71,6 +71,7 @@ static struct ctl_table user_table[] = { 
	UCOUNT_ENTRY("max_pid_namespaces"),

	UCOUNT_ENTRY("max_uts_namespaces"),

	UCOUNT_ENTRY("max_ipc_namespaces"),

	UCOUNT_ENTRY("max_net_namespaces"),

	UCOUNT_ENTRY("max_cgroup_namespaces"),

	{ }

};

net/core/net_namespace.c

+21 −1
Original line number Diff line number Diff line
@@ -266,6 +266,16 @@ struct net *get_net_ns_by_id(struct net *net, int id) 
	return peer;

}



static struct ucounts *inc_net_namespaces(struct user_namespace *ns)

{

	return inc_ucount(ns, current_euid(), UCOUNT_NET_NAMESPACES);

}



static void dec_net_namespaces(struct ucounts *ucounts)

{

	dec_ucount(ucounts, UCOUNT_NET_NAMESPACES);

}



/*

 * setup_net runs the initializers for the network namespace object.

 */
@@ -351,19 +361,27 @@ void net_drop_ns(void *p) 
struct net *copy_net_ns(unsigned long flags,

			struct user_namespace *user_ns, struct net *old_net)

{

	struct ucounts *ucounts;

	struct net *net;

	int rv;



	if (!(flags & CLONE_NEWNET))

		return get_net(old_net);



	ucounts = inc_net_namespaces(user_ns);

	if (!ucounts)

		return ERR_PTR(-ENFILE);



	net = net_alloc();

	if (!net)

	if (!net) {

		dec_net_namespaces(ucounts);

		return ERR_PTR(-ENOMEM);

	}



	get_user_ns(user_ns);



	mutex_lock(&net_mutex);

	net->ucounts = ucounts;

	rv = setup_net(net, user_ns);

	if (rv == 0) {

		rtnl_lock();
@@ -372,6 +390,7 @@ struct net *copy_net_ns(unsigned long flags, 
	}

	mutex_unlock(&net_mutex);

	if (rv < 0) {

		dec_net_namespaces(ucounts);

		put_user_ns(user_ns);

		net_drop_ns(net);

		return ERR_PTR(rv);
@@ -444,6 +463,7 @@ static void cleanup_net(struct work_struct *work) 
	/* Finally it is safe to free my network namespace structure */

	list_for_each_entry_safe(net, tmp, &net_exit_list, exit_list) {

		list_del_init(&net->exit_list);

		dec_net_namespaces(net->ucounts);

		put_user_ns(net->user_ns);

		net_drop_ns(net);

	}