netdev - Re: [PATCH] ipv6: fix icmp6

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Date:   Mon, 11 Feb 2019 12:38:18 -0800 (PST)
From:   David Miller <davem@...emloft.net>
To:     alin.nastac@...il.com
Cc:     netdev@...r.kernel.org
Subject: Re: [PATCH] ipv6: fix icmp6_send() route lookup

From: Alin Nastac <alin.nastac@...il.com>
Date: Thu,  7 Feb 2019 16:05:31 +0100

> Original packet destination address must be used as saddr for the
> route lookup performed by icmp6_send() even when this address is
> not local. This fixes the IPv6 router ability to send back
> destination unreachable ICMPv6 errors for forwarded packets when
> the route toward the saddr of the original packet is source
> filtered (e.g. a default route with a "from PD" attribute, where
> PD is the delegated prefix).
> 
> Signed-off-by: Alin Nastac <alin.nastac@...il.com>

Yes, but however this will change behavior for a lot of situations
not just the one you are interested in.

The base ipv6_chk_addr() test has been there for more than a decade
and I'm not comfortable with changing this logic until I see you
write up a full audit of all of the use cases of icmp6_send() and
how they are impacted by your changes.

Thanks.