From: Eric Dumazet <[email protected]> Date: Thu, 20 Nov 2014 18:22:07 -0800
> On Thu, 2014-11-20 at 17:47 -0800, Calvin Owens wrote: > >> That's actually not what led to finding this, but it's a good point. :) >> >> What if the challenge-ACK counter were decremented in tcp_validate_incoming() >> when a valid RST packet is seen? That would allow legitimate remote >> hosts to reestablish connections without being ratelimited, and still >> prevent a malicious host from guessing sequence numbers. >> >> There would need to be a way to tell if a challenge ACK had in fact been >> sent and only decrement in that case, since otherwise a local attacker >> could establish and immediately reset lots of connections to keep the >> counter below the ratelimit threshold and guess sequence numbers. >> >> Simply adding a flag to struct tcp_sock would work: just set the flag >> whenever a challenge ACK is sent, and clear it and decrement the counter >> only if it is set when a valid RST packet is seen. > > Seems tricky, a Challenge ACK do not necessarily gives an RST. > > Anyway this certainly can wait, as we already have a sysctl to > eventually work around the issue. > > Acked-by: Eric Dumazet <[email protected]> Applied, thanks everyone. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
