From: yupeng yupeng0921@gmail.com
[ Upstream commit 0fbe82e628c817e292ff588cd5847fc935e025f2 ]
after set SO_DONTROUTE to 1, the IP layer should not route packets if the dest IP address is not in link scope. But if the socket has cached the dst_entry, such packets would be routed until the sk_dst_cache expires. So we should clean the sk_dst_cache when a user set SO_DONTROUTE option. Below are server/client python scripts which could reprodue this issue:
server side code:
========================================================================== import socket import struct import time
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.bind(('0.0.0.0', 9000)) s.listen(1) sock, addr = s.accept() sock.setsockopt(socket.SOL_SOCKET, socket.SO_DONTROUTE, struct.pack('i', 1)) while True: sock.send(b'foo') time.sleep(1) ==========================================================================
client side code: ========================================================================== import socket import time
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.connect(('server_address', 9000)) while True: data = s.recv(1024) print(data) ==========================================================================
Signed-off-by: yupeng yupeng0921@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- net/core/sock.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/net/core/sock.c b/net/core/sock.c index 36f19458e2fe..33584eb7f0cf 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -735,6 +735,7 @@ int sock_setsockopt(struct socket *sock, int level, int optname, break; case SO_DONTROUTE: sock_valbool_flag(sk, SOCK_LOCALROUTE, valbool); + sk_dst_reset(sk); break; case SO_BROADCAST: sock_valbool_flag(sk, SOCK_BROADCAST, valbool);