udp4: fix IP_CMSG_CHECKSUM for connected sockets

commit 2abb7cdc0dc8 ("udp: Add support for doing checksum
unnecessary conversion") left out the early demux path for
connected sockets. As a result IP_CMSG_CHECKSUM gives wrong
values for such socket when GRO is not enabled/available.

This change addresses the issue by moving the csum conversion to a
common helper and using such helper in both the default and the
early demux rx path.

Fixes: 2abb7cdc0dc8 ("udp: Add support for doing checksum unnecessary conversion")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index f4e35b2ff8b8dc3956da415cb6a29bb147e25f04..7d69dd6fa7e8c63929a27edad74fb0d6f9f3ee31 100644 (file)
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -2124,6 +2124,28 @@ static inline int udp4_csum_init(struct sk_buff *skb, struct udphdr *uh,
                                                         inet_compute_pseudo);
 }
 
+/* wrapper for udp_queue_rcv_skb tacking care of csum conversion and
+ * return code conversion for ip layer consumption
+ */
+static int udp_unicast_rcv_skb(struct sock *sk, struct sk_buff *skb,
+                              struct udphdr *uh)
+{
+       int ret;
+
+       if (inet_get_convert_csum(sk) && uh->check && !IS_UDPLITE(sk))
+               skb_checksum_try_convert(skb, IPPROTO_UDP, uh->check,
+                                        inet_compute_pseudo);
+
+       ret = udp_queue_rcv_skb(sk, skb);
+
+       /* a return value > 0 means to resubmit the input, but
+        * it wants the return to be -protocol, or 0
+        */
+       if (ret > 0)
+               return -ret;
+       return 0;
+}
+
 /*
  *     All we need to do is get the socket, and then do a checksum.
  */
@@ -2170,14 +2192,9 @@ int __udp4_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
                if (unlikely(sk->sk_rx_dst != dst))
                        udp_sk_rx_dst_set(sk, dst);
 
-               ret = udp_queue_rcv_skb(sk, skb);
+               ret = udp_unicast_rcv_skb(sk, skb, uh);
                sock_put(sk);
-               /* a return value > 0 means to resubmit the input, but
-                * it wants the return to be -protocol, or 0
-                */
-               if (ret > 0)
-                       return -ret;
-               return 0;
+               return ret;
        }
 
        if (rt->rt_flags & (RTCF_BROADCAST|RTCF_MULTICAST))
@@ -2185,22 +2202,8 @@ int __udp4_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
                                                saddr, daddr, udptable, proto);
 
        sk = __udp4_lib_lookup_skb(skb, uh->source, uh->dest, udptable);
-       if (sk) {
-               int ret;
-
-               if (inet_get_convert_csum(sk) && uh->check && !IS_UDPLITE(sk))
-                       skb_checksum_try_convert(skb, IPPROTO_UDP, uh->check,
-                                                inet_compute_pseudo);
-
-               ret = udp_queue_rcv_skb(sk, skb);
-
-               /* a return value > 0 means to resubmit the input, but
-                * it wants the return to be -protocol, or 0
-                */
-               if (ret > 0)
-                       return -ret;
-               return 0;
-       }
+       if (sk)
+               return udp_unicast_rcv_skb(sk, skb, uh);
 
        if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
                goto drop;