• Patrick McHardy's avatar
    packet: support extensible, 64 bit clean mmaped ring structure · bbd6ef87
    Patrick McHardy authored
    The tpacket_hdr is not 64 bit clean due to use of an unsigned long
    and can't be extended because the following struct sockaddr_ll needs
    to be at a fixed offset.
    
    Add support for a version 2 tpacket protocol that removes these
    limitations.
    
    Userspace can query the header size through a new getsockopt option
    and change the protocol version through a setsockopt option. The
    changes needed to switch to the new protocol version are:
    
    1. replace struct tpacket_hdr by struct tpacket2_hdr
    2. query header len and save
    3. set protocol version to 2
     - set up ring as usual
    4. for getting the sockaddr_ll, use (void *)hdr + TPACKET_ALIGN(hdrlen)
       instead of (void *)hdr + TPACKET_ALIGN(sizeof(struct tpacket_hdr))
    
    Steps 2 and 4 can be omitted if the struct sockaddr_ll isn't needed.
    Signed-off-by: default avatarPatrick McHardy <kaber@trash.net>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    bbd6ef87
af_packet.c 45.7 KB