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| author | Eric Dumazet <eric.dumazet@gmail.com> | 2010-06-03 09:03:58 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2010-06-04 15:56:02 -0700 |
| commit | ca55158c6ecb7832a6ad80ac44a14d23bab8cdfc (patch) | |
| tree | e701c78b85016247fa5962de0e0793e5b985930e /net/ipv4/tcp_ipv4.c | |
| parent | 536e00e570c87f258554e919c444b81a7002e46d (diff) | |
| download | blackbird-obmc-linux-ca55158c6ecb7832a6ad80ac44a14d23bab8cdfc.tar.gz blackbird-obmc-linux-ca55158c6ecb7832a6ad80ac44a14d23bab8cdfc.zip | |
rps: tcp: fix rps_sock_flow_table table updates
I believe a moderate SYN flood attack can corrupt RFS flow table
(rps_sock_flow_table), making RPS/RFS much less effective.
Even in a normal situation, server handling short lived sessions suffer
from bad steering for the first data packet of a session, if another SYN
packet is received for another session.
We do following action in tcp_v4_rcv() :
sock_rps_save_rxhash(sk, skb->rxhash);
We should _not_ do this if sk is a LISTEN socket, as about each
packet received on a LISTEN socket has a different rxhash than
previous one.
-> RPS_NO_CPU markers are spread all over rps_sock_flow_table.
Also, it makes sense to protect sk->rxhash field changes with socket
lock (We currently can change it even if user thread owns the lock
and might use rxhash)
This patch moves sock_rps_save_rxhash() to a sock locked section,
and only for non LISTEN sockets.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_ipv4.c')
| -rw-r--r-- | net/ipv4/tcp_ipv4.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 202cf09c4cd4..fe193e53af44 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -1555,6 +1555,7 @@ int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb) #endif if (sk->sk_state == TCP_ESTABLISHED) { /* Fast path */ + sock_rps_save_rxhash(sk, skb->rxhash); TCP_CHECK_TIMER(sk); if (tcp_rcv_established(sk, skb, tcp_hdr(skb), skb->len)) { rsk = sk; @@ -1579,7 +1580,9 @@ int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb) } return 0; } - } + } else + sock_rps_save_rxhash(sk, skb->rxhash); + TCP_CHECK_TIMER(sk); if (tcp_rcv_state_process(sk, skb, tcp_hdr(skb), skb->len)) { @@ -1672,8 +1675,6 @@ process: skb->dev = NULL; - sock_rps_save_rxhash(sk, skb->rxhash); - bh_lock_sock_nested(sk); ret = 0; if (!sock_owned_by_user(sk)) { |
