• Craig Gallek's avatar
    soreuseport: fix ordering for mixed v4/v6 sockets · d894ba18
    Craig Gallek authored
    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: 's avatarMaciej Żenczykowski <maze@google.com>
    Signed-off-by: 's avatarCraig Gallek <kraig@google.com>
    Signed-off-by: 's avatarEric Dumazet <edumazet@google.com>
    Signed-off-by: 's avatarDavid S. Miller <davem@davemloft.net>
    d894ba18
rculist_nulls.h 5.49 KB