Re: Back-porting request

[Sasha Levin <sashal@kernel.org>]

On Mon, Jul 29, 2019 at 05:56:27PM +0200, Greg KH wrote:
>On Mon, Jul 29, 2019 at 11:42:34AM -0400, Stephen Suryaputra wrote:
>> Hello,
>>
>> I'm requesting this commit to be back-ported to v4.14:
>> ---
>> commit 5b18f1289808fee5d04a7e6ecf200189f41a4db6
>> Author: Stephen Suryaputra <ssuryaextr@gmail.com>
>> Date:   Wed Jun 26 02:21:16 2019 -0400
>>
>>     ipv4: reset rt_iif for recirculated mcast/bcast out pkts
>>
>>     Multicast or broadcast egress packets have rt_iif set to the oif. These
>>     packets might be recirculated back as input and lookup to the raw
>>     sockets may fail because they are bound to the incoming interface
>>     (skb_iif). If rt_iif is not zero, during the lookup, inet_iif() function
>>     returns rt_iif instead of skb_iif. Hence, the lookup fails.
>>
>>     v2: Make it non vrf specific (David Ahern). Reword the changelog to
>>         reflect it.
>>     Signed-off-by: Stephen Suryaputra <ssuryaextr@gmail.com>
>>     Reviewed-by: David Ahern <dsahern@gmail.com>
>>     Signed-off-by: David S. Miller <davem@davemloft.net>
>> ---
>>
>> We found the issue in that release and the above commit is on
>> linux-stable. On the discussion behind this commit, please see:
>> https://www.spinics.net/lists/netdev/msg581045.html
>>
>> I think after the following diff is needed on top of the above commit
>> for v4.14:
>>
>> ---
>> diff --git a/net/ipv4/route.c b/net/ipv4/route.c
>> index 4d85a4fdfdb0..ad2718c1624e 100644
>> --- a/net/ipv4/route.c
>> +++ b/net/ipv4/route.c
>> @@ -1623,11 +1623,8 @@ struct rtable *rt_dst_clone(struct net_device *dev, struct rtable *rt)
>>  		new_rt->rt_iif = rt->rt_iif;
>>  		new_rt->rt_pmtu = rt->rt_pmtu;
>>  		new_rt->rt_mtu_locked = rt->rt_mtu_locked;
>> -		new_rt->rt_gw_family = rt->rt_gw_family;
>> -		if (rt->rt_gw_family == AF_INET)
>> -			new_rt->rt_gw4 = rt->rt_gw4;
>> -		else if (rt->rt_gw_family == AF_INET6)
>> -			new_rt->rt_gw6 = rt->rt_gw6;
>> +		new_rt->rt_gateway = rt->rt_gateway;
>> +		new_rt->rt_table_id = rt->rt_table_id;
>>  		INIT_LIST_HEAD(&new_rt->rt_uncached);
>>
>>  		new_rt->dst.flags |= DST_HOST;
>> ---
>>
>> Thank you,
>
>For networking patches to be applied to the stable kernel tree(s),
>please read:
>    https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
>for how to do this properly.
>
>There is a section for how to do this for networking patches as they are
>accepted a bit differently from other patches.

To clarify a bit more here: technically you're asking for a patch to be
included in 4.14, which isn't one of the "last two stable releases", so
that document will tell you to send that patch directly to us.

However, this patch isn't in 4.19 either, which is still Dave's domain,
and we can't take it in 4.14 if it's not in 4.19 (we don't want to
introduce regressions for people who are upgrading their kernels), so
this will still need to go through Dave.

--
Thanks,
Sasha