Description of problem:

ifup-routes and ifdown-routes scripts have unwanted side-effects when applied to an alias interface for which a PBR rules-<ifname> entry exists for the parent interface.

This is similar, but not identical, to the effects on IPv6 interfaces described in BZ 870271.


Version-Release number of selected component (if applicable):

initscripts-9.03.40-2.el6.centos.x86_64

How reproducible:

Always

Steps to Reproduce:

Create a non-empty set of Policy Based Routing rules and routes in rule-eth0 and route-eth0 respectively.

Create an ifcfg-eth0 for the primary interface on a Host and bring eth0 Up.

Create an ifcfg-eth0:0 alias interface with no associated rule-eth0:0 or route-eth0:0


Fire up eth0:0 manually 

     ifup eth0:0

Shutdown eth0:0 manually

     ifdown eth0:0


Actual results:

When eth0:0 is brought up manually, ifup-routes attempts to bring up the same routes already brought up by eth0 because the script attempts to parse BOTH route-eth0 AND route-eth0:0 when invoked for eth0:0.

This results in error messages like "RTNETLINK answers: File exists" as the kernel rejects the attempt to create the duplicate routes.

Similarly, ifup-routes adds the same rules already brought up by eth0 because the script attempts to parse BOTH rule-eth0 AND rule-eth0:0 when invoked for eth0:0.

This results in duplicate rules showing up in "ip rules list".

When eth0:0 is brought down, the duplicate rules which were added by ifup eth0:0 are removed, leaving only the originals added by ifup eth0. However, the routes added from route-eth0 are completely removed, which potentially destroys important routing policy for traffic on that interface.
 

The problem only arises where an alias interface is shutdown independently of the primary interface, AND the primary interface ALSO has some interface-specific Policy Based Routing configuration.



Expected results:

The actions of ifup eth0:0 and ifdown eth0:0 should be unaffected the contents of rule-eth0 and route-eth0. They should only parse routing policy from the specific files rule-eth0:0 and route-eth0:0



Additional info:

A suggested fix is to change the clause in ifup-routes which deduces which FILES to use to ONLY use the specific interface entry for an alias interface.

i.e. replace this:

...
FILES="/etc/sysconfig/network-scripts/route-$1 /etc/sysconfig/network-scripts/route6-$1"
if [ -n "$2" -a "$2" != "$1" ]; then
    FILES="$FILES /etc/sysconfig/network-scripts/route-$2 /etc/sysconfig/network-scripts/route6-$2"
fi
....
# Routing rules
FILES="/etc/sysconfig/network-scripts/rule-$1 /etc/sysconfig/network-scripts/rule6-$1"
if [ -n "$2" -a "$2" != "$1" ]; then
    FILES="$FILES /etc/sysconfig/network-scripts/rule-$2 /etc/sysconfig/network-scripts/rule6-$2"
fi
....


with:

...
FILES="/etc/sysconfig/network-scripts/route-$1 /etc/sysconfig/network-scripts/route6-$1"
if [ -n "$2" -a "$2" != "$1" ]; then
    FILES="/etc/sysconfig/network-scripts/route-$2 /etc/sysconfig/network-scripts/route6-$2"
fi
....
# Routing rules
FILES="/etc/sysconfig/network-scripts/rule-$1 /etc/sysconfig/network-scripts/rule6-$1"
if [ -n "$2" -a "$2" != "$1" ]; then
    FILES="/etc/sysconfig/network-scripts/rule-$2 /etc/sysconfig/network-scripts/rule6-$2"
fi
....