net: move and export get_net_ns_by_pid

The function get_net_ns_by_pid(), to get a network
namespace from a pid_t, will be required in cfg80211
as well. Therefore, let's move it to net_namespace.c
and export it. We can't make it a static inline in
the !NETNS case because it needs to verify that the
given pid even exists (and return -ESRCH).

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 22 insertions, 20 deletions

diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index 5cd0b22e649d..ddd2cd2b1775 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -7,6 +7,7 @@
 #include <linux/sched.h>
 #include <linux/idr.h>
 #include <linux/rculist.h>
+#include <linux/nsproxy.h>
 #include <net/net_namespace.h>
 #include <net/netns/generic.h>
 
@@ -201,6 +202,26 @@ struct net *copy_net_ns(unsigned long flags, struct net *old_net)
 }
 #endif
 
+struct net *get_net_ns_by_pid(pid_t pid)
+{
+        struct task_struct *tsk;
+        struct net *net;
+
+        /* Lookup the network namespace */
+        net = ERR_PTR(-ESRCH);
+        rcu_read_lock();
+        tsk = find_task_by_vpid(pid);
+        if (tsk) {
+                struct nsproxy *nsproxy;
+                nsproxy = task_nsproxy(tsk);
+                if (nsproxy)
+                        net = get_net(nsproxy->net_ns);
+        }
+        rcu_read_unlock();
+        return net;
+}
+EXPORT_SYMBOL_GPL(get_net_ns_by_pid);
+
 static int __init net_ns_init(void)
 {
         struct net_generic *ng;
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index d78030f88bd0..b44775f9f2bf 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -35,7 +35,6 @@
 #include <linux/security.h>
 #include <linux/mutex.h>
 #include <linux/if_addr.h>
-#include <linux/nsproxy.h>
 
 #include <asm/uaccess.h>
 #include <asm/system.h>
@@ -52,6 +51,7 @@
 #include <net/pkt_sched.h>
 #include <net/fib_rules.h>
 #include <net/rtnetlink.h>
+#include <net/net_namespace.h>
 
 struct rtnl_link
 {
@@ -725,25 +725,6 @@ static const struct nla_policy ifla_info_policy[IFLA_INFO_MAX+1] = {
         [IFLA_INFO_DATA]        = { .type = NLA_NESTED },
 };
 
-static struct net *get_net_ns_by_pid(pid_t pid)
-{
-        struct task_struct *tsk;
-        struct net *net;
-
-        /* Lookup the network namespace */
-        net = ERR_PTR(-ESRCH);
-        rcu_read_lock();
-        tsk = find_task_by_vpid(pid);
-        if (tsk) {
-                struct nsproxy *nsproxy;
-                nsproxy = task_nsproxy(tsk);
-                if (nsproxy)
-                        net = get_net(nsproxy->net_ns);
-        }
-        rcu_read_unlock();
-        return net;
-}
-
 static int validate_linkmsg(struct net_device *dev, struct nlattr *tb[])
 {
         if (dev) {