linux/net/mpls
Robert Shearman 72dcac96c7 mpls: don't dump RTA_VIA attribute if not specified
The problem seen is that when adding a route with a nexthop with no
via address specified, iproute2 generates bogus output:

  # ip -f mpls route add 100 dev lo
  # ip -f mpls route list
  100 via inet 0.0.8.0 dev lo

The reason for this is that the kernel generates an RTA_VIA attribute
with the family set to AF_INET, but the via address data having zero
length. The cause of family being AF_INET is that on route insert
cfg->rc_via_table is left set to 0, which just happens to be
NEIGH_ARP_TABLE which is then translated into AF_INET.

iproute2 doesn't validate the length prior to printing and so prints
garbage. Although it could be fixed to do the validation, I would
argue that AF_INET addresses should always be exactly 4 bytes so the
kernel is really giving userspace bogus data.

Therefore, avoid generating the RTA_VIA attribute when dumping the
route if the via address wasn't specified on add/modify. This is
indicated by NEIGH_ARP_TABLE and a zero via address length - if the
user specified a via address the address length would have been
validated such that it was 4 bytes. Although this is a change in
behaviour that is visible to userspace, I believe that what was
generated before was invalid and as such userspace wouldn't be
expecting it.

Signed-off-by: Robert Shearman <rshearma@brocade.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-12-12 00:43:44 -05:00
..
af_mpls.c mpls: don't dump RTA_VIA attribute if not specified 2015-12-12 00:43:44 -05:00
internal.h mpls: reduce memory usage of routes 2015-10-27 19:52:59 -07:00
Kconfig mpls: ip tunnel support 2015-07-21 10:39:05 -07:00
Makefile mpls: ip tunnel support 2015-07-21 10:39:05 -07:00
mpls_gso.c net: Add priority to packet_offload objects. 2015-06-01 14:56:09 -07:00
mpls_iptunnel.c mpls: fix sending of local encapped packets 2015-12-07 16:32:47 -05:00