From 703286608a220d53584cca5986aad5305eec75ed Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Mon, 8 Aug 2016 14:33:23 -0500 Subject: netns: Add a limit on the number of net namespaces Acked-by: Kees Cook Signed-off-by: "Eric W. Biederman" --- net/core/net_namespace.c | 22 +++++++++++++++++++++- 1 file changed, 21 insertions(+), 1 deletion(-) (limited to 'net/core/net_namespace.c') diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c index 2c2eb1b629b1..3e2812aeceb7 100644 --- a/net/core/net_namespace.c +++ b/net/core/net_namespace.c @@ -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); } -- cgit v1.2.3-59-g8ed1b