From: David Ahern <dsahern@gmail.com>
To: Hangbin Liu <liuhangbin@gmail.com>
Cc: netdev@vger.kernel.org, Stefano Brivio <sbrivio@redhat.com>,
Marcelo Ricardo Leitner <mleitner@redhat.com>,
"David S . Miller" <davem@davemloft.net>
Subject: Re: [PATCH net] ipv4/route: do not check saddr dev if iif is LOOPBACK_IFINDEX
Date: Thu, 1 Aug 2019 22:16:00 -0600 [thread overview]
Message-ID: <209d2ebf-aeb1-de08-2343-f478d51b92fa@gmail.com> (raw)
In-Reply-To: <20190802041358.GT18865@dhcp-12-139.nay.redhat.com>
On 8/1/19 10:13 PM, Hangbin Liu wrote:
> On Thu, Aug 01, 2019 at 01:51:25PM -0600, David Ahern wrote:
>> On 8/1/19 2:29 AM, Hangbin Liu wrote:
>>> Jianlin reported a bug that for IPv4, ip route get from src_addr would fail
>>> if src_addr is not an address on local system.
>>>
>>> \# ip route get 1.1.1.1 from 2.2.2.2
>>> RTNETLINK answers: Invalid argument
>>
>> so this is a forwarding lookup in which case iif should be set. Based on
>
> with out setting iif in userspace, the kernel set iif to lo by default.
right, it presumes locally generated traffic.
>
>> the above 'route get' inet_rtm_getroute is doing a lookup as if it is
>> locally generated traffic.
>
> yeah... but what about the IPv6 part. That cause a different behavior in
> userspace.
just one of many, many annoying differences between v4 and v6. We could
try to catalog it.
next prev parent reply other threads:[~2019-08-02 4:16 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-01 8:29 [PATCH net] ipv4/route: do not check saddr dev if iif is LOOPBACK_IFINDEX Hangbin Liu
2019-08-01 19:51 ` David Ahern
2019-08-02 4:13 ` Hangbin Liu
2019-08-02 4:16 ` David Ahern [this message]
2019-08-12 3:49 ` David Miller
2019-08-12 22:58 ` Stefano Brivio
2019-08-13 0:23 ` David Ahern
2019-08-02 20:35 ` Stefano Brivio
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