Patchwork [v2,net-next] call sk_dst_reset when set SO_DONTROUTE

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Submitter peng yu
Date Dec. 6, 2018, 2:56 a.m.
Message ID <20181206025628.3130-1-yupeng0921@gmail.com>
Download mbox | patch
Permalink /patch/673747/
State New
Headers show

Comments

peng yu - Dec. 6, 2018, 2:56 a.m.
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:
David Miller - Dec. 8, 2018, 12:12 a.m.
From: yupeng <yupeng0921@gmail.com>
Date: Wed,  5 Dec 2018 18:56:28 -0800

> 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:
 ...
> Signed-off-by: yupeng <yupeng0921@gmail.com>

Applied.

Patch

==========================================================================
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>
---
 net/core/sock.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/core/sock.c b/net/core/sock.c
index f5bb89785e47..f00902c532cc 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -700,6 +700,7 @@  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);