Re: [PATCH net] ipv4: Fix route deletion when nexthop info is not specified

[David Ahern <dsahern@gmail.com>]

On 11/24/22 2:09 PM, Ido Schimmel wrote:
> When the kernel receives a route deletion request from user space it
> tries to delete a route that matches the route attributes specified in
> the request.
> 
> If only prefix information is specified in the request, the kernel
> should delete the first matching FIB alias regardless of its associated
> FIB info. However, an error is currently returned when the FIB info is
> backed by a nexthop object:
> 
>  # ip nexthop add id 1 via 192.0.2.2 dev dummy10
>  # ip route add 198.51.100.0/24 nhid 1
>  # ip route del 198.51.100.0/24
>  RTNETLINK answers: No such process
> 
> Fix by matching on such a FIB info when legacy nexthop attributes are
> not specified in the request. An earlier check already covers the case
> where a nexthop ID is specified in the request.
> 
> Add tests that cover these flows. Before the fix:
> 
>  # ./fib_nexthops.sh -t ipv4_fcnal
>  ...
>  TEST: Delete route when not specifying nexthop attributes           [FAIL]
> 
>  Tests passed:  11
>  Tests failed:   1
> 
> After the fix:
> 
>  # ./fib_nexthops.sh -t ipv4_fcnal
>  ...
>  TEST: Delete route when not specifying nexthop attributes           [ OK ]
> 
>  Tests passed:  12
>  Tests failed:   0
> 
> No regressions in other tests:
> 
>  # ./fib_nexthops.sh
>  ...
>  Tests passed: 228
>  Tests failed:   0
> 
>  # ./fib_tests.sh
>  ...
>  Tests passed: 186
>  Tests failed:   0
> 
> Cc: stable@vger.kernel.org
> Reported-by: Jonas Gorski <jonas.gorski@gmail.com>
> Tested-by: Jonas Gorski <jonas.gorski@gmail.com>
> Fixes: 493ced1ac47c ("ipv4: Allow routes to use nexthop objects")
> Fixes: 6bf92d70e690 ("net: ipv4: fix route with nexthop object delete warning")
> Fixes: 61b91eb33a69 ("ipv4: Handle attempt to delete multipath route when fib_info contains an nh reference")
> Signed-off-by: Ido Schimmel <idosch@nvidia.com>
> ---
>  net/ipv4/fib_semantics.c                    |  8 +++++---
>  tools/testing/selftests/net/fib_nexthops.sh | 11 +++++++++++
>  2 files changed, 16 insertions(+), 3 deletions(-)
> 

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