net: ipv4: Add ability to have GRE ignore DF bit in IPv4 payloads
authorPhilip Prindeville <philipp@redfish-solutions.com>
Tue, 14 Jun 2016 21:53:02 +0000 (15:53 -0600)
committerDavid S. Miller <davem@davemloft.net>
Thu, 16 Jun 2016 04:39:59 +0000 (21:39 -0700)
commit22a59be8b7693eb2d0897a9638f5991f2f8e4ddd
tree633065a94e616e259e2da87a31f006392fda908e
parent810e530bfa1116079bf94b8c93b99b0208959261
net: ipv4: Add ability to have GRE ignore DF bit in IPv4 payloads

    In the presence of firewalls which improperly block ICMP Unreachable
    (including Fragmentation Required) messages, Path MTU Discovery is
    prevented from working.

    A workaround is to handle IPv4 payloads opaquely, ignoring the DF bit--as
    is done for other payloads like AppleTalk--and doing transparent
    fragmentation and reassembly.

    Redux includes the enforcement of mutual exclusion between this feature
    and Path MTU Discovery as suggested by Alexander Duyck.

Cc: Alexander Duyck <alexander.duyck@gmail.com>
Reviewed-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: Philip Prindeville <philipp@redfish-solutions.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
include/net/ip_tunnels.h
include/uapi/linux/if_tunnel.h
net/ipv4/ip_gre.c
net/ipv4/ip_tunnel.c