From 8c2bd38b95f75f3d2a08c93e35303e26d480d24e Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 29 Aug 2024 14:46:39 +0000 Subject: icmp: change the order of rate limits ICMP messages are ratelimited : After the blamed commits, the two rate limiters are applied in this order: 1) host wide ratelimit (icmp_global_allow()) 2) Per destination ratelimit (inetpeer based) In order to avoid side-channels attacks, we need to apply the per destination check first. This patch makes the following change : 1) icmp_global_allow() checks if the host wide limit is reached. But credits are not yet consumed. This is deferred to 3) 2) The per destination limit is checked/updated. This might add a new node in inetpeer tree. 3) icmp_global_consume() consumes tokens if prior operations succeeded. This means that host wide ratelimit is still effective in keeping inetpeer tree small even under DDOS. As a bonus, I removed icmp_global.lock as the fast path can use a lock-free operation. Fixes: c0303efeab73 ("net: reduce cycles spend on ICMP replies that gets rate limited") Fixes: 4cdf507d5452 ("icmp: add a global rate limitation") Reported-by: Keyu Man Signed-off-by: Eric Dumazet Reviewed-by: David Ahern Cc: Jesper Dangaard Brouer Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20240829144641.3880376-2-edumazet@google.com Signed-off-by: Jakub Kicinski --- include/net/ip.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include') diff --git a/include/net/ip.h b/include/net/ip.h index c5606cadb1a5..82248813619e 100644 --- a/include/net/ip.h +++ b/include/net/ip.h @@ -795,6 +795,8 @@ static inline void ip_cmsg_recv(struct msghdr *msg, struct sk_buff *skb) } bool icmp_global_allow(void); +void icmp_global_consume(void); + extern int sysctl_icmp_msgs_per_sec; extern int sysctl_icmp_msgs_burst; -- cgit v1.2.3