fragmentation for tunnel devices is not working

Since linux-3.5.x+ fragmentation to gre devices with PMTU (IPsec or pmtu routes) is not working properly. PMTU works properly, though.

This is discussed on linux-netdev on the following threads:
http://marc.info/?t=136318770900003&r=1&w=2
http://marc.info/?l=linux-netdev&m=136380160923566&w=2

(from redmine: issue id 1782, created on 2013-04-12, closed on 2013-06-04)

• Changesets:
  • Revision d0149d1c by Natanael Copa on 2013-05-23T16:11:32Z:

main/linux-grsec: fix for fragmentation issue on tunnel devices

ref #1782

• Revision 4d918a90 by Natanael Copa on 2013-06-03T15:59:51Z:

main/linux-grsec: fix for fragmentation issue on tunnel devices

ref #1782
(cherry picked from commit d0149d1c8a6f773c34c018f6af4c6ba8177e5648)

• Revision 87760fec by Natanael Copa on 2013-06-03T16:00:27Z:

main/linux-grsec: upgrade to 3.9.4 and use reworked arp and frag patches

fixes #1782

(cherry picked from commit a43c9a4092402400bd3f008d2841a468773ddad0)