mirror of
https://github.com/moby/moby.git
synced 2026-07-10 08:39:25 +00:00
d216084185
Traditionally when Linux receives remote packets with daddr set to a loopback address, it reject them as 'martians'. However, when a NAT rule is applied through iptables this doesn't happen. Our current DNAT rule used to map host ports to containers is applied unconditionally, even for such 'martian' packets. This means a neighbor host (ie. a host connected to the same L2 segment) can send packets to a port mapped on a loopback address. The purpose of publishing on a loopback address is to make ports inaccessible to remote hosts -- lack of proper filtering defeats that. This commit adds an iptables rule to the raw-PREROUTING chain to drop packets with a loopback dest address and coming from any interface other than lo. To accomodate WSL2 mirrored mode, another rule is inserted beforehand to specifically accept packets coming from the loopback0 interface. Signed-off-by: Albin Kerouanton <albinker@gmail.com>