soreuseport: fix ordering for mixed v4/v6 sockets
With the SO_REUSEPORT socket option, it is possible to create sockets in the AF_INET and AF_INET6 domains which are bound to the same IPv4 address. This is only possible with SO_REUSEPORT and when not using IPV6_V6ONLY on the AF_INET6 sockets. Prior to the commits referenced below, an incoming IPv4 packet would always be routed to a socket of type AF_INET when this mixed-mode was used. After those changes, the same packet would be routed to the most recently bound socket (if this happened to be an AF_INET6 socket, it would have an IPv4 mapped IPv6 address). The change in behavior occurred because the recent SO_REUSEPORT optimizations short-circuit the socket scoring logic as soon as they find a match. They did not take into account the scoring logic that favors AF_INET sockets over AF_INET6 sockets in the event of a tie. To fix this problem, this patch changes the insertion order of AF_INET and AF_INET6 addresses in the TCP and UDP socket lists when the sockets have SO_REUSEPORT set. AF_INET sockets will be inserted at the head of the list and AF_INET6 sockets with SO_REUSEPORT set will always be inserted at the tail of the list. This will force AF_INET sockets to always be considered first. Fixes: e32ea7e7 ("soreuseport: fast reuseport UDP socket selection") Fixes: 125e80b88687 ("soreuseport: fast reuseport TCP socket selection") Reported-by: NMaciej Żenczykowski <maze@google.com> Signed-off-by: NCraig Gallek <kraig@google.com> Signed-off-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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