[PATCH 020/104] ipv4: sendto/hdrincl: don't use destination address found in header

[Kamal Mostafa]

3.8.13.11 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Chris Clark <chris.clark@xxxxxxxxxxxxxxxxxx>

[ Upstream commit c27c9322d015dc1d9dfdf31724fca71c0476c4d1 ]

ipv4: raw_sendmsg: don't use header's destination address

A sendto() regression was bisected and found to start with commit
f8126f1d5136be1 (ipv4: Adjust semantics of rt->rt_gateway.)

The problem is that it tries to ARP-lookup the constructed packet's
destination address rather than the explicitly provided address.

Fix this using FLOWI_FLAG_KNOWN_NH so that given nexthop is used.

cf. commit 2ad5b9e4bd314fc685086b99e90e5de3bc59e26b

Reported-by: Chris Clark <chris.clark@xxxxxxxxxxxxxxxxxx>
Bisected-by: Chris Clark <chris.clark@xxxxxxxxxxxxxxxxxx>
Tested-by: Chris Clark <chris.clark@xxxxxxxxxxxxxxxxxx>
Suggested-by: Julian Anastasov <ja@xxxxxx>
Signed-off-by: Chris Clark <chris.clark@xxxxxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
 net/ipv4/raw.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
index 6f08991..47b4797 100644
--- a/net/ipv4/raw.c
+++ b/net/ipv4/raw.c
@@ -573,7 +573,8 @@ static int raw_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 	flowi4_init_output(&fl4, ipc.oif, sk->sk_mark, tos,
 			   RT_SCOPE_UNIVERSE,
 			   inet->hdrincl ? IPPROTO_RAW : sk->sk_protocol,
-			   inet_sk_flowi_flags(sk) | FLOWI_FLAG_CAN_SLEEP,
+			   inet_sk_flowi_flags(sk) | FLOWI_FLAG_CAN_SLEEP |
+			    (inet->hdrincl ? FLOWI_FLAG_KNOWN_NH : 0),
 			   daddr, saddr, 0, 0);
 
 	if (!inet->hdrincl) {
-- 
1.8.1.2

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