Re: [PATCH net-next] icmp: add a global rate limitation

[David Miller <davem@davemloft.net>]

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Fri, 19 Sep 2014 07:38:40 -0700

> From: Eric Dumazet <edumazet@google.com>
> 
> Current ICMP rate limiting uses inetpeer cache, which is an RBL tree
> protected by a lock, meaning that hosts can be stuck hard if all cpus
> want to check ICMP limits.
> 
> When say a DNS or NTP server process is restarted, inetpeer tree grows
> quick and machine comes to its knees.
> 
> iptables can not help because the bottleneck happens before ICMP
> messages are even cooked and sent.
> 
> This patch adds a new global limitation, using a token bucket filter,
> controlled by two new sysctl :
> 
> icmp_msgs_per_sec - INTEGER
>     Limit maximal number of ICMP packets sent per second from this host.
>     Only messages whose type matches icmp_ratemask are
>     controlled by this limit.
>     Default: 1000
> 
> icmp_msgs_burst - INTEGER
>     icmp_msgs_per_sec controls number of ICMP packets sent per second,
>     while icmp_msgs_burst controls the burst size of these packets.
>     Default: 50
> 
> Note that if we really want to send millions of ICMP messages per
> second, we might extend idea and infra added in commit 04ca6973f7c1a
> ("ip: make IP identifiers less predictable") :
> add a token bucket in the ip_idents hash and no longer rely on inetpeer.
> 
> Signed-off-by: Eric Dumazet <edumazet@google.com>

Applied.