user namespace: make each net (net_ns) belong to a user_ns

This way we can target capabilites at the user_ns which created the
net ns.

Changelog:
   jul 8: nsproxy: don't assign netns->userns if not cloning.

Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>

3 files changed, 7 insertions, 0 deletions

diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index 3bb6fa0eace01..d91fe5f7b59fe 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -29,6 +29,7 @@ struct ctl_table_header;
 struct net_generic;
 struct sock;
 struct netns_ipvs;
+struct user_namespace;
 
 
 #define NETDEV_HASHBITS    8
@@ -101,6 +102,7 @@ struct net {
 	struct netns_xfrm	xfrm;
 #endif
 	struct netns_ipvs	*ipvs;
+	struct user_namespace	*user_ns;
 };
 
 
diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
index cadcee0529359..62a995de27f3a 100644
--- a/kernel/nsproxy.c
+++ b/kernel/nsproxy.c
@@ -95,6 +95,8 @@ static struct nsproxy *create_new_namespaces(unsigned long flags,
 		err = PTR_ERR(new_nsp->net_ns);
 		goto out_net;
 	}
+	if (flags & CLONE_NEWNET)
+		new_nsp->net_ns->user_ns = get_user_ns(task_cred_xxx(tsk, user_ns));
 
 	return new_nsp;
 
diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index 90c97f63365dc..8778a0a558077 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -10,6 +10,7 @@
 #include <linux/nsproxy.h>
 #include <linux/proc_fs.h>
 #include <linux/file.h>
+#include <linux/user_namespace.h>
 #include <net/net_namespace.h>
 #include <net/netns/generic.h>
 
@@ -209,6 +210,7 @@ static void net_free(struct net *net)
 	}
 #endif
 	kfree(net->gen);
+	put_user_ns(net->user_ns);
 	kmem_cache_free(net_cachep, net);
 }
 
@@ -389,6 +391,7 @@ static int __init net_ns_init(void)
 	rcu_assign_pointer(init_net.gen, ng);
 
 	mutex_lock(&net_mutex);
+	init_net.user_ns = &init_user_ns;
 	if (setup_net(&init_net))
 		panic("Could not setup the initial network namespace");