Re: [PATCH net-next 3/4] ipv4: Reject routes specifying ECN bits in rtm_tos

[Shuah Khan <skhan@linuxfoundation.org>]

On 2/4/22 6:58 AM, Guillaume Nault wrote:
> Use the new dscp_t type to replace the fc_tos field of fib_config, to
> ensure IPv4 routes aren't influenced by ECN bits when configured with
> non-zero rtm_tos.
> 
> Before this patch, IPv4 routes specifying an rtm_tos with some of the
> ECN bits set were accepted. However they wouldn't work (never match) as
> IPv4 normally clears the ECN bits with IPTOS_RT_MASK before doing a FIB
> lookup (although a few buggy code paths don't).
> 
> After this patch, IPv4 routes specifying an rtm_tos with any ECN bit
> set is rejected.
> 
> Note: IPv6 routes ignore rtm_tos altogether, any rtm_tos is accepted,
> but treated as if it were 0.
> 
> Signed-off-by: Guillaume Nault <gnault@redhat.com>
> ---
> Shuah, FYI, this is the patch I was refering to in our discussion about
> testing invalid tos values:
> https://lore.kernel.org/netdev/20220202232555.GC15826@pc-4.home/
> 

This give me context. Thank you.

thanks,
-- Shuah