Re: [PATCH net 2/2] ipv4: Fix incorrect route flushing when table ID 0 is used

[David Ahern <dsahern@kernel.org>]

On 12/4/22 12:50 AM, Ido Schimmel wrote:
> Cited commit added the table ID to the FIB info structure, but did not
> properly initialize it when table ID 0 is used. This can lead to a route
> in the default VRF with a preferred source address not being flushed
> when the address is deleted.
> 
> Consider the following example:
> 
>  # ip address add dev dummy1 192.0.2.1/28
>  # ip address add dev dummy1 192.0.2.17/28
>  # ip route add 198.51.100.0/24 via 192.0.2.2 src 192.0.2.17 metric 100
>  # ip route add table 0 198.51.100.0/24 via 192.0.2.2 src 192.0.2.17 metric 200
>  # ip route show 198.51.100.0/24
>  198.51.100.0/24 via 192.0.2.2 dev dummy1 src 192.0.2.17 metric 100
>  198.51.100.0/24 via 192.0.2.2 dev dummy1 src 192.0.2.17 metric 200
> 
> Both routes are installed in the default VRF, but they are using two
> different FIB info structures. One with a metric of 100 and table ID of
> 254 (main) and one with a metric of 200 and table ID of 0. Therefore,
> when the preferred source address is deleted from the default VRF,
> the second route is not flushed:
> 
>  # ip address del dev dummy1 192.0.2.17/28
>  # ip route show 198.51.100.0/24
>  198.51.100.0/24 via 192.0.2.2 dev dummy1 src 192.0.2.17 metric 200
> 
> Fix by storing a table ID of 254 instead of 0 in the route configuration
> structure.
> 
> Add a test case that fails before the fix:
> 
>  # ./fib_tests.sh -t ipv4_del_addr
> 
>  IPv4 delete address route tests
>      Regular FIB info
>      TEST: Route removed from VRF when source address deleted            [ OK ]
>      TEST: Route in default VRF not removed                              [ OK ]
>      TEST: Route removed in default VRF when source address deleted      [ OK ]
>      TEST: Route in VRF is not removed by address delete                 [ OK ]
>      Identical FIB info with different table ID
>      TEST: Route removed from VRF when source address deleted            [ OK ]
>      TEST: Route in default VRF not removed                              [ OK ]
>      TEST: Route removed in default VRF when source address deleted      [ OK ]
>      TEST: Route in VRF is not removed by address delete                 [ OK ]
>      Table ID 0
>      TEST: Route removed in default VRF when source address deleted      [FAIL]
> 
>  Tests passed:   8
>  Tests failed:   1
> 
> And passes after:
> 
>  # ./fib_tests.sh -t ipv4_del_addr
> 
>  IPv4 delete address route tests
>      Regular FIB info
>      TEST: Route removed from VRF when source address deleted            [ OK ]
>      TEST: Route in default VRF not removed                              [ OK ]
>      TEST: Route removed in default VRF when source address deleted      [ OK ]
>      TEST: Route in VRF is not removed by address delete                 [ OK ]
>      Identical FIB info with different table ID
>      TEST: Route removed from VRF when source address deleted            [ OK ]
>      TEST: Route in default VRF not removed                              [ OK ]
>      TEST: Route removed in default VRF when source address deleted      [ OK ]
>      TEST: Route in VRF is not removed by address delete                 [ OK ]
>      Table ID 0
>      TEST: Route removed in default VRF when source address deleted      [ OK ]
> 
>  Tests passed:   9
>  Tests failed:   0
> 
> Fixes: 5a56a0b3a45d ("net: Don't delete routes in different VRFs")
> Reported-by: Donald Sharp <sharpd@nvidia.com>
> Signed-off-by: Ido Schimmel <idosch@nvidia.com>
> ---
>  net/ipv4/fib_frontend.c                  |  3 +++
>  tools/testing/selftests/net/fib_tests.sh | 10 ++++++++++
>  2 files changed, 13 insertions(+)
> 

Reviewed-by: David Ahern <dsahern@kernel.org>