VLAN network script if-up.d/ip limits rp_filter value to 0 or 1

[Juan Fernandez]

[impact]

Using ifupdown, vlan supported setting an interface's rp-filter value, but that can only set 0 or 1, but it cannot be set to 2.

[test case]

On any system using ifupdown to manage interfaces, add to an interface's config:

if-rp-filter 2

When the interface is brought up, its /proc/sys/net/ipv4/conf/$IFACE/rp_filter value will be set to 1 instead of 2. With the fixed vlan package, its value will correctly be set to 2.
See also c#9 for a test example

[regression potential]

problems with this change could affect the value of an interface's rp_filter value.

[other]

the upstream debian bug for this has been open for 3 years without change, so it is unlikely debian will fix this.

As outlined in c#4 and c#13 this setting is vlan not generally required for vlans (but often used with them). So it in question if eventually it should be added elsewhere and removed here, but for the SRU the bug is where it is (in the vlan package) and there it has to be fixed.

---

[original description]

When configuring a VLAN interface on /etc/network/interfaces, setting the ip-rp-filter value to 2 (loose mode reverse filtering) gets overridden by the /etc/network/if-up.d/ip script, which only allows for values 0 and 1.

This is the relevant configuration in /etc/network/interfaces

# The primary network interface
auto eno1
iface eno1 inet static
 address 10.1.2.36
 netmask 255.255.0.0
 gateway 10.1.1.2
 dns-search xxx.yy
 dns-nameservers 10.1.2.22 10.1.2.24

# The administrative network
auto eno1.2
iface eno1.2 inet static
 address 172.16.1.8
 netmask 255.255.0.0
 ip-rp-filter 2
 vlan-raw-device eno1

But it does not get correctly set

~# cat /proc/sys/net/ipv4/conf/eno1.2/rp_filter
1

And this is the script overriding the configuration

~# cat /etc/network/if-up.d/ip
#!/bin/sh
# This should probably go into ifupdown
# But usually only those with lots of interfaces (vlans) need these
if [ -d "/proc/sys/net/ipv4/conf/$IFACE" ]
then
 if [ -n "$IF_IP_PROXY_ARP" ]; then
  if [ "$IF_IP_PROXY_ARP" -eq "1" ]; then
   echo 1 > "/proc/sys/net/ipv4/conf/$IFACE/proxy_arp"
  else
   echo 0 > "/proc/sys/net/ipv4/conf/$IFACE/proxy_arp"
  fi
 fi
 if [ -n "$IF_IP_RP_FILTER" ]; then
  if [ "$IF_IP_RP_FILTER" -eq "0" ]; then
   echo 0 > "/proc/sys/net/ipv4/conf/$IFACE/rp_filter"
  else
   echo 1 > "/proc/sys/net/ipv4/conf/$IFACE/rp_filter"
  fi
 fi
fi

It checks if $IF_IP_RP_FILTER is 0 and sets it as 0, otherwise sets it as 1, so it never allows to set is to 2 (loose mode).

[Juan Fernandez (jfernandezr)]

The following modification on /etc/network/if-up.d/ip makes it work.

*** 13,18 ****
--- 13,20 ----
   if [ -n "$IF_IP_RP_FILTER" ]; then
    if [ "$IF_IP_RP_FILTER" -eq "0" ]; then
     echo 0 > "/proc/sys/net/ipv4/conf/$IFACE/rp_filter"
+ elif [ "$IF_IP_RP_FILTER" -eq "2" ]; then
+ echo 2 > "/proc/sys/net/ipv4/conf/$IFACE/rp_filter"
    else
     echo 1 > "/proc/sys/net/ipv4/conf/$IFACE/rp_filter"
    fi

[Christian Ehrhardt  (paelzer)]

Related doc ont he parameter:
https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt

There is not more than 0,1,2.

I agree to the suggested solution in general.
The issue applies to current dev back to trusty.

I'm not sure if in Artful with netplan and potential impacts on these hooks this needs an extra change.

[Christian Ehrhardt  (paelzer)]

@Dan - IIRC you look currently for work that is sponsored for your uploader application. This looks like a great case and more than that you did the last 6 uploads to this package so you likely have some sort of test environment already.
Would you mind picking that up?

And while on that this issue as well as the former one applies to Debian as well. So
@Juan - would you mind reporting that to Debian as well so that at some day we can drop the Delta?

[Dan Streetman (ddstreet)]

As the comment says in the vlan if-up script, this setting has nothing to do with vlans and really should go into ifupdown itself; it makes no sense for the setting to only work if the 'vlan' package is installed (and it will work for vlan and non-vlan interfaces as long as 'vlan' is installed).

However, since this is 'how it has always worked' with ifupdown and nobody has complained, and ifupdown is riding into the sunset, it makes no sense to do more than the minimum to fix this. I'll make the tweak to the vlan if-up script and leave it at that.

[Dan Streetman (ddstreet)]

test ppa: https://launchpad.net/~ddstreet/+archive/ubuntu/lp1716964

root@vlan-artful:~# dpkg -l | grep vlan
ii vlan 1.9-3.2ubuntu4 amd64 user mode programs to enable VLANs on your ethernet devices

root@vlan-artful:~# cat /etc/network/interfaces
# interfaces(5) file used by ifup(8) and ifdown(8)
# Include files from /etc/network/interfaces.d:
source-directory /etc/network/interfaces.d

auto eth0
iface eth0 inet dhcp
  ip-rp-filter 2

root@vlan-artful:~# systemctl restart networking
root@vlan-artful:~# cat /proc/sys/net/ipv4/conf/eth0/rp_filter
1

root@vlan-artful:~# apt install vlan
...
root@vlan-artful:~# dpkg -l | grep vlan
ii vlan 1.9-3.2ubuntu5 amd64 user mode programs to enable VLANs on your ethernet devices
root@vlan-artful:~# systemctl restart networking
root@vlan-artful:~# cat /proc/sys/net/ipv4/conf/eth0/rp_filter
2

[Christian Ehrhardt  (paelzer)]

Well it needs ifupdown for it to work (with and without your fix).
For the fix at hand it is that is ok - no need to block this or the SRUs on that.
But add it to the steps to reproduce.

I was able to confirm on the ppa that it works then.

But @ddstreet: you should think about how this will continue to work in a no ifupdown world - spawn a new bug for yourself if you want. Until it is gone a dependency to ifupdown would be correct. I assume lacking one atm makes this being not seen by the people that work on netplan and co.

[Christian Ehrhardt  (paelzer)]

Sponsored the Artful upload [1], please as mentioned look into the post ifupdown world case and consider fixing vlan for that as well.

Ping me if all migrated in artful and SRU templates are ready to sponsor those as well.

[1]: https://launchpad.net/ubuntu/+source/vlan/1.9-3.2ubuntu5

[Dan Streetman (ddstreet)]

@paelzer re: ifupdown, the vlan package is only used by ifupdown. How other nw management allows changing an interface's rp_filter is up to that tool, e.g. netplan or networkd, and this particular bug does apply (they may do it wrong also, but it has nothing to do with the vlan package).

[Christian Ehrhardt  (paelzer)]

After IRC discussion the answer to the non ifupdown world is that this should never have been in vlan and the fix is more to be correct on the SRU path than on the future - thanks for explaining ddstreet.

[Ubuntu Foundations Team Bug Bot (crichton)]

The attachment "lp1716964-artful.debdiff" seems to be a debdiff. The ubuntu-sponsors team has been subscribed to the bug report so that they can review and hopefully sponsor the debdiff. If the attachment isn't a patch, please remove the "patch" flag from the attachment, remove the "patch" tag, and if you are member of the ~ubuntu-sponsors, unsubscribe the team.

[This is an automated message performed by a Launchpad user owned by ~brian-murray, for any issue please contact him.]

[Launchpad Janitor (janitor)]

This bug was fixed in the package vlan - 1.9-3.2ubuntu5

---------------
vlan (1.9-3.2ubuntu5) artful; urgency=medium

  * Allow ip-rp-filter to be 0, 1, or 2 instead of only 0 or 1
    (LP: #1716964)

 -- Dan Streetman <email address hidden> Wed, 20 Sep 2017 09:30:21 -0400

[Christian Ehrhardt  (paelzer)]

BTW it has to do with vlan (example [1][2] - just not dependent as it has use cases without vlan, never the less this shouldn't be the place where it should have been implemented in the first place. But for now this is bugfixing and not a rewrite of hwo things should be.

I have slightly improved your SRU Template, if the SRU Team has further needs they can ask you.

BTW Lintian floods me with version (and other) warnings, but you are just spinning forward the versioning style it has which is ok and all others are due to the package being rather old.

I checked the diffs once more and think in the term of the SRU fixing of this issue they are correct, so sponsoring for T/X/Z.

[1]: https://serverfault.com/questions/369947/linux-vlan-routing
[2]: https://serverfault.com/questions/816393/disabling-rp-filter-on-one-interface

[Brian Murray (brian-murray)]

Hello Juan, or anyone else affected,

Accepted vlan into zesty-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/vlan/1.9-3.2ubuntu2.17.04.3 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed.Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested and change the tag from verification-needed-zesty to verification-done-zesty. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-zesty. In either case, details of your testing will help us make a better decision.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

[Brian Murray (brian-murray)]

Hello Juan, or anyone else affected,

Accepted vlan into xenial-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/vlan/1.9-3.2ubuntu1.16.04.4 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed.Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested and change the tag from verification-needed-xenial to verification-done-xenial. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-xenial. In either case, details of your testing will help us make a better decision.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

[Brian Murray (brian-murray)]

Hello Juan, or anyone else affected,

Accepted vlan into trusty-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/vlan/1.9-3ubuntu10.5 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed.Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested and change the tag from verification-needed-trusty to verification-done-trusty. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-trusty. In either case, details of your testing will help us make a better decision.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

[Dan Streetman (ddstreet)]

trusty:

root@vlan-trusty:~# cat /etc/network/interfaces.d/eth0.cfg
# The primary network interface
auto eth0
iface eth0 inet dhcp
  ip-rp-filter 2

root@vlan-trusty:~# dpkg -l | grep vlan
ii vlan 1.9-3ubuntu10.4 amd64 user mode programs to enable VLANs on your ethernet devices
root@vlan-trusty:~# ifdown eth0
Internet Systems Consortium DHCP Client 4.2.4
Copyright 2004-2012 Internet Systems Consortium.
All rights reserved.
For info, please visit https://www.isc.org/software/dhcp/

Listening on LPF/eth0/00:16:3e:f7:82:fa
Sending on LPF/eth0/00:16:3e:f7:82:fa
Sending on Socket/fallback
DHCPRELEASE on eth0 to 10.1.255.1 port 67 (xid=0x1bed540d)
root@vlan-trusty:~# ifup eth0
Internet Systems Consortium DHCP Client 4.2.4
Copyright 2004-2012 Internet Systems Consortium.
All rights reserved.
For info, please visit https://www.isc.org/software/dhcp/

Listening on LPF/eth0/00:16:3e:f7:82:fa
Sending on LPF/eth0/00:16:3e:f7:82:fa
Sending on Socket/fallback
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 3 (xid=0xf32ce957)
DHCPREQUEST of 10.1.255.79 on eth0 to 255.255.255.255 port 67 (xid=0x57e92cf3)
DHCPOFFER of 10.1.255.79 from 10.1.255.1
DHCPACK of 10.1.255.79 from 10.1.255.1
bound to 10.1.255.79 -- renewal in 1747 seconds.
root@vlan-trusty:~# grep . /proc/sys/net/ipv4/conf/*/rp_filter
/proc/sys/net/ipv4/conf/all/rp_filter:1
/proc/sys/net/ipv4/conf/default/rp_filter:1
/proc/sys/net/ipv4/conf/eth0/rp_filter:1
/proc/sys/net/ipv4/conf/lo/rp_filter:1

upgrade vlan to -proposed pkg:

root@vlan-trusty:~# dpkg -l | grep vlan
ii vlan 1.9-3ubuntu10.5 amd64 user mode programs to enable VLANs on your ethernet devices
root@vlan-trusty:~# ifdown eth0
Internet Systems Consortium DHCP Client 4.2.4
Copyright 2004-2012 Internet Systems Consortium.
All rights reserved.
For info, please visit https://www.isc.org/software/dhcp/

Listening on LPF/eth0/00:16:3e:f7:82:fa
Sending on LPF/eth0/00:16:3e:f7:82:fa
Sending on Socket/fallback
DHCPRELEASE on eth0 to 10.1.255.1 port 67 (xid=0x22e79e9b)
root@vlan-trusty:~# ifup eth0
Internet Systems Consortium DHCP Client 4.2.4
Copyright 2004-2012 Internet Systems Consortium.
All rights reserved.
For info, please visit https://www.isc.org/software/dhcp/

Listening on LPF/eth0/00:16:3e:f7:82:fa
Sending on LPF/eth0/00:16:3e:f7:82:fa
Sending on Socket/fallback
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 3 (xid=0x39089e72)
DHCPREQUEST of 10.1.255.79 on eth0 to 255.255.255.255 port 67 (xid=0x729e0839)
DHCPOFFER of 10.1.255.79 from 10.1.255.1
DHCPACK of 10.1.255.79 from 10.1.255.1
bound to 10.1.255.79 -- renewal in 1710 seconds.
root@vlan-trusty:~# grep . /proc/sys/net/ipv4/conf/*/rp_filter
/proc/sys/net/ipv4/conf/all/rp_filter:1
/proc/sys/net/ipv4/conf/default/rp_filter:1
/proc/sys/net/ipv4/conf/eth0/rp_filter:2
/proc/sys/net/ipv4/conf/lo/rp_filter:1

[Dan Streetman (ddstreet)]

xenial:

root@vlan-xenial:~# cat /etc/network/interfaces.d/50-cloud-init.cfg
# This file is generated from information provided by
# the datasource. Changes to it will not persist across an instance.
# To disable cloud-init's network configuration capabilities, write a file
# /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following:
# network: {config: disabled}
auto lo
iface lo inet loopback

auto eth0
iface eth0 inet dhcp
  ip-rp-filter 2

root@vlan-xenial:~# dpkg -l | grep vlan
ii vlan 1.9-3.2ubuntu1.16.04.3 amd64 user mode programs to enable VLANs on your ethernet devices
root@vlan-xenial:~# systemctl restart networking
root@vlan-xenial:~# grep . /proc/sys/net/ipv4/conf/*/rp_filter
/proc/sys/net/ipv4/conf/all/rp_filter:1
/proc/sys/net/ipv4/conf/default/rp_filter:1
/proc/sys/net/ipv4/conf/eth0/rp_filter:1
/proc/sys/net/ipv4/conf/lo/rp_filter:1

after upgrade:

root@vlan-xenial:~# dpkg -l | grep vlan
ii vlan 1.9-3.2ubuntu1.16.04.4 amd64 user mode programs to enable VLANs on your ethernet devices
root@vlan-xenial:~# systemctl restart networking
root@vlan-xenial:~# grep . /proc/sys/net/ipv4/conf/*/rp_filter
/proc/sys/net/ipv4/conf/all/rp_filter:1
/proc/sys/net/ipv4/conf/default/rp_filter:1
/proc/sys/net/ipv4/conf/eth0/rp_filter:2
/proc/sys/net/ipv4/conf/lo/rp_filter:1

[Dan Streetman (ddstreet)]

zesty:

root@vlan-zesty:~# cat /etc/network/interfaces.d/50-cloud-init.cfg
# This file is generated from information provided by
# the datasource. Changes to it will not persist across an instance.
# To disable cloud-init's network configuration capabilities, write a file
# /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following:
# network: {config: disabled}
auto lo
iface lo inet loopback

auto eth0
iface eth0 inet dhcp
  ip-rp-filter 2

root@vlan-zesty:~# dpkg -l | grep vlan
ii vlan 1.9-3.2ubuntu2.17.04.2 amd64 user mode programs to enable VLANs on your ethernet devices
root@vlan-zesty:~# systemctl restart networking
root@vlan-zesty:~# grep . /proc/sys/net/ipv4/conf/*/rp_filter
/proc/sys/net/ipv4/conf/all/rp_filter:1
/proc/sys/net/ipv4/conf/default/rp_filter:1
/proc/sys/net/ipv4/conf/eth0/rp_filter:1
/proc/sys/net/ipv4/conf/lo/rp_filter:1

after upgrade:

root@vlan-zesty:~# dpkg -l | grep vlan
ii vlan 1.9-3.2ubuntu2.17.04.3 amd64 user mode programs to enable VLANs on your ethernet devices
root@vlan-zesty:~# systemctl restart networking
root@vlan-zesty:~# grep . /proc/sys/net/ipv4/conf/*/rp_filter
/proc/sys/net/ipv4/conf/all/rp_filter:1
/proc/sys/net/ipv4/conf/default/rp_filter:1
/proc/sys/net/ipv4/conf/eth0/rp_filter:2
/proc/sys/net/ipv4/conf/lo/rp_filter:1

[Launchpad Janitor (janitor)]

This bug was fixed in the package vlan - 1.9-3ubuntu10.5

---------------
vlan (1.9-3ubuntu10.5) trusty; urgency=medium

  * Allow ip-rp-filter to be 0, 1, or 2 instead of only 0 or 1
    (LP: #1716964)

 -- Dan Streetman <email address hidden> Wed, 20 Sep 2017 09:30:21 -0400

[Brian Murray (brian-murray)]

The verification of the Stable Release Update for vlan has completed successfully and the package has now been released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.

[Launchpad Janitor (janitor)]

This bug was fixed in the package vlan - 1.9-3.2ubuntu1.16.04.4

---------------
vlan (1.9-3.2ubuntu1.16.04.4) xenial; urgency=medium

  * Allow ip-rp-filter to be 0, 1, or 2 instead of only 0 or 1
    (LP: #1716964)

 -- Dan Streetman <email address hidden> Wed, 20 Sep 2017 09:30:21 -0400

[Launchpad Janitor (janitor)]

This bug was fixed in the package vlan - 1.9-3.2ubuntu2.17.04.3

---------------
vlan (1.9-3.2ubuntu2.17.04.3) zesty; urgency=medium

  * Allow ip-rp-filter to be 0, 1, or 2 instead of only 0 or 1
    (LP: #1716964)

 -- Dan Streetman <email address hidden> Wed, 20 Sep 2017 09:30:21 -0400