unix_diag: Unix peer inode NLA

Report the peer socket inode ID as NLA. With this it's finally
possible to find out the other end of an interesting unix connection.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 24 insertions, 0 deletions

diff --git a/net/unix/diag.c b/net/unix/diag.c
index 83799ef19b49..0e0fda786afe 100644
--- a/net/unix/diag.c
+++ b/net/unix/diag.c
@@ -43,6 +43,26 @@ rtattr_failure:
         return -EMSGSIZE;
 }
 
+static int sk_diag_dump_peer(struct sock *sk, struct sk_buff *nlskb)
+{
+        struct sock *peer;
+        int ino;
+
+        peer = unix_peer_get(sk);
+        if (peer) {
+                unix_state_lock(peer);
+                ino = sock_i_ino(peer);
+                unix_state_unlock(peer);
+                sock_put(peer);
+
+                RTA_PUT_U32(nlskb, UNIX_DIAG_PEER, ino);
+        }
+
+        return 0;
+rtattr_failure:
+        return -EMSGSIZE;
+}
+
 static int sk_diag_fill(struct sock *sk, struct sk_buff *skb, struct unix_diag_req *req,
                 u32 pid, u32 seq, u32 flags, int sk_ino)
 {
@@ -69,6 +89,10 @@ static int sk_diag_fill(struct sock *sk, struct sk_buff *skb, struct unix_diag_r
                         sk_diag_dump_vfs(sk, skb))
                 goto nlmsg_failure;
 
+        if ((req->udiag_show & UDIAG_SHOW_PEER) &&
+                        sk_diag_dump_peer(sk, skb))
+                goto nlmsg_failure;
+
         nlh->nlmsg_len = skb_tail_pointer(skb) - b;
         return skb->len;