diff options
| author | Jakub Kicinski <kuba@kernel.org> | 2022-08-31 19:56:53 -0700 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2022-08-31 19:56:54 -0700 |
| commit | a3daac631e4824a68a5449f60dd86b90bb7be91a (patch) | |
| tree | 639b61f605e41a495d774f43c4e3062296bd3836 /net/ipv4/tcp_input.c | |
| parent | 52267ce25f60f37ae40ccbca0b21328ebae5ae75 (diff) | |
| parent | 79e3602caa6f9d59c4f66a268407080496dae408 (diff) | |
Merge branch 'tcp-tcp-challenge-ack-fixes'
Eric Dumazet says:
====================
tcp: tcp challenge ack fixes
syzbot found a typical data-race addressed in the first patch.
While we are at it, second patch makes the global rate limit
per net-ns and disabled by default.
====================
Link: https://lore.kernel.org/r/20220830185656.268523-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/ipv4/tcp_input.c')
| -rw-r--r-- | net/ipv4/tcp_input.c | 21 |
1 files changed, 11 insertions, 10 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index ab5f0ea166f1..b85a9f755da4 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -3614,12 +3614,9 @@ bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb, /* RFC 5961 7 [ACK Throttling] */ static void tcp_send_challenge_ack(struct sock *sk) { - /* unprotected vars, we dont care of overwrites */ - static u32 challenge_timestamp; - static unsigned int challenge_count; struct tcp_sock *tp = tcp_sk(sk); struct net *net = sock_net(sk); - u32 count, now; + u32 count, now, ack_limit; /* First check our per-socket dupack rate limit. */ if (__tcp_oow_rate_limited(net, @@ -3627,18 +3624,22 @@ static void tcp_send_challenge_ack(struct sock *sk) &tp->last_oow_ack_time)) return; + ack_limit = READ_ONCE(net->ipv4.sysctl_tcp_challenge_ack_limit); + if (ack_limit == INT_MAX) + goto send_ack; + /* Then check host-wide RFC 5961 rate limit. */ now = jiffies / HZ; - if (now != challenge_timestamp) { - u32 ack_limit = READ_ONCE(net->ipv4.sysctl_tcp_challenge_ack_limit); + if (now != READ_ONCE(net->ipv4.tcp_challenge_timestamp)) { u32 half = (ack_limit + 1) >> 1; - challenge_timestamp = now; - WRITE_ONCE(challenge_count, half + prandom_u32_max(ack_limit)); + WRITE_ONCE(net->ipv4.tcp_challenge_timestamp, now); + WRITE_ONCE(net->ipv4.tcp_challenge_count, half + prandom_u32_max(ack_limit)); } - count = READ_ONCE(challenge_count); + count = READ_ONCE(net->ipv4.tcp_challenge_count); if (count > 0) { - WRITE_ONCE(challenge_count, count - 1); + WRITE_ONCE(net->ipv4.tcp_challenge_count, count - 1); +send_ack: NET_INC_STATS(net, LINUX_MIB_TCPCHALLENGEACK); tcp_send_ack(sk); } |