inet_diag: Export inet diag cookie checking routine

The netlink diag susbsys stores sk address bits in the nl message
as a "cookie" and uses one when dumps details about particular
socket.

The same will be required for udp diag module, so introduce a heler
in inet_diag module

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

1 files changed, 14 insertions, 5 deletions

diff --git a/net/ipv4/inet_diag.c b/net/ipv4/inet_diag.c
index bd3f661803a7..ba3ae1f73abf 100644
--- a/net/ipv4/inet_diag.c
+++ b/net/ipv4/inet_diag.c
@@ -246,6 +246,18 @@ static int sk_diag_fill(struct sock *sk, struct sk_buff *skb,
         return inet_csk_diag_fill(sk, skb, r, pid, seq, nlmsg_flags, unlh);
 }
 
+int inet_diag_check_cookie(struct sock *sk, struct inet_diag_req *req)
+{
+        if ((req->id.idiag_cookie[0] != INET_DIAG_NOCOOKIE ||
+             req->id.idiag_cookie[1] != INET_DIAG_NOCOOKIE) &&
+            ((u32)(unsigned long)sk != req->id.idiag_cookie[0] ||
+             (u32)((((unsigned long)sk) >> 31) >> 1) != req->id.idiag_cookie[1]))
+                return -ESTALE;
+        else
+                return 0;
+}
+EXPORT_SYMBOL_GPL(inet_diag_check_cookie);
+
 static int inet_diag_get_exact(struct sk_buff *in_skb,
                                const struct nlmsghdr *nlh,
                                struct inet_diag_req *req)
@@ -288,11 +300,8 @@ static int inet_diag_get_exact(struct sk_buff *in_skb,
         if (sk == NULL)
                 goto unlock;
 
-        err = -ESTALE;
-        if ((req->id.idiag_cookie[0] != INET_DIAG_NOCOOKIE ||
-             req->id.idiag_cookie[1] != INET_DIAG_NOCOOKIE) &&
-            ((u32)(unsigned long)sk != req->id.idiag_cookie[0] ||
-             (u32)((((unsigned long)sk) >> 31) >> 1) != req->id.idiag_cookie[1]))
+        err = inet_diag_check_cookie(sk, req);
+        if (err)
                 goto out;
 
         err = -ENOMEM;