1. 28 6月, 2012 1 次提交
    • E
      ipv4: tcp: dont cache unconfirmed intput dst · c074da28
      Eric Dumazet 提交于
      DDOS synflood attacks hit badly IP route cache.
      
      On typical machines, this cache is allowed to hold up to 8 Millions dst
      entries, 256 bytes for each, for a total of 2GB of memory.
      
      rt_garbage_collect() triggers and tries to cleanup things.
      
      Eventually route cache is disabled but machine is under fire and might
      OOM and crash.
      
      This patch exploits the new TCP early demux, to set a nocache
      boolean in case incoming TCP frame is for a not yet ESTABLISHED or
      TIMEWAIT socket.
      
      This 'nocache' boolean is then used in case dst entry is not found in
      route cache, to create an unhashed dst entry (DST_NOCACHE)
      
      SYN-cookie-ACK sent use a similar mechanism (ipv4: tcp: dont cache
      output dst for syncookies), so after this patch, a machine is able to
      absorb a DDOS synflood attack without polluting its IP route cache.
      Signed-off-by: NEric Dumazet <edumazet@google.com>
      Cc: Hans Schillstrom <hans.schillstrom@ericsson.com>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      c074da28
  2. 27 6月, 2012 39 次提交