On Fri, 2019-02-08 at 11:55 -0500, Clément 'wxcafé' Hertling wrote: > Package: iproute2 > Version: 4.20.0-2 > Severity: normal > Tags: ipv6 upstream > > > When using `ip route get` with 0.0.0.0 or ::, iproute2 shows multiple > incorrect behaviors: > > - `ip route get 0.0.0.0/0` answers "need at least a destination > address", > where it should answer with the default route. 0.0.0.0/0 is a valid > network and it should be possible to query for the default route > that way > - similarly, `ip route get `::/0` also answers "need at least a > destination > address". For the same reason, it should also answer with the > default > route.
Those sound reasonable, can you send a patch upstream and see what they
say?
> - finally, `ip route get 0.0.0.0/1`, or any other non-0 netmask,
> answers
> with "local 0.0.0.0 dev lo src 127.0.0.1 uid 1000", which is simply
> wrong. 0.0.0.0/1 IS NOT routed via lo, and this query should answer
> with the most-specific route for 0.0.0.0/1 or the default if there
> is
> no such route. Interestingly, `ip route get 1.0.0.0/1`, while a
> query
> for the exact same subnet, actually gives the right route (in my
> case,
> the default route).
The netlink messages sent by iproute2 look exactly the same, apart from
the address:
(gdb) p req
$17 = {n = {nlmsg_len = 36, nlmsg_type = 26, nlmsg_flags = 1, nlmsg_seq = 0,
nlmsg_pid = 0}, r = {
rtm_family = 2 '\002', rtm_dst_len = 0 '\000', rtm_src_len = 0 '\000',
rtm_tos = 0 '\000',
rtm_table = 0 '\000', rtm_protocol = 0 '\000', rtm_scope = 0 '\000',
rtm_type = 0 '\000',
rtm_flags = 0}, buf = "\b\000\001", '\000' <repeats 1020 times>}
(gdb) p req
$13 = {n = {nlmsg_len = 36, nlmsg_type = 26, nlmsg_flags = 1, nlmsg_seq = 0,
nlmsg_pid = 0}, r = {
rtm_family = 2 '\002', rtm_dst_len = 0 '\000', rtm_src_len = 0 '\000',
rtm_tos = 0 '\000',
rtm_table = 0 '\000', rtm_protocol = 0 '\000', rtm_scope = 0 '\000',
rtm_type = 0 '\000',
rtm_flags = 0}, buf = "\b\000\001\000\001", '\000' <repeats 1018 times>}
So I would guess the issue is in the kernel.
> The first two problems seem to be caused by this line in iproute2
> error
> handling https://github.com/shemminger/iproute2/blob/master/ip/iprout
> e.c#L1425,
> which is written without taking into consideration that netmasks of
> length 0 are actually valid; I have no idea where the last problem
> originates unfortunately.
>
> Thank you
--
Kind regards,
Luca Boccassi
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