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Message-ID: <a95f1211-0f1b-4957-8e31-1b53af888cb5@redhat.com>
Date: Tue, 20 Aug 2024 15:13:43 +0200
From: Paolo Abeni <pabeni@...hat.com>
To: Nils Fuhler <nils@...sfuhler.de>, davem@...emloft.net,
dsahern@...nel.org, edumazet@...gle.com, kuba@...nel.org
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] net: ip6: ndisc: fix incorrect forwarding of proxied
ns packets
On 8/15/24 17:18, Nils Fuhler wrote:
> When enabling proxy_ndp per interface instead of globally, neighbor
> solicitation packets sent to proxied global unicast addresses are
> forwarded instead of generating a neighbor advertisement. When
> proxy_ndp is enabled globally, these packets generate na responses as
> expected.
>
> This patch fixes this behaviour. When an ns packet is sent to a
> proxied unicast address, it generates an na response regardless
> whether proxy_ndp is enabled per interface or globally.
>
> Signed-off-by: Nils Fuhler <nils@...sfuhler.de>
I have mixed feeling WRT this patch. It looks like a fix, but it's
changing an established behaviour that is there since a lot of time.
I think it could go via the net-next tree, without fixes
tag to avoid stable backports. As such I guess it deserves a self-test
script validating the new behavior.
> ---
> v1 -> v2: ensure that idev is not NULL
>
> net/ipv6/ip6_output.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
> index ab504d31f0cd..0356c8189e21 100644
> --- a/net/ipv6/ip6_output.c
> +++ b/net/ipv6/ip6_output.c
> @@ -551,8 +551,8 @@ int ip6_forward(struct sk_buff *skb)
> return -ETIMEDOUT;
> }
>
> - /* XXX: idev->cnf.proxy_ndp? */
> - if (READ_ONCE(net->ipv6.devconf_all->proxy_ndp) &&
> + if ((READ_ONCE(net->ipv6.devconf_all->proxy_ndp) ||
> + (idev && READ_ONCE(idev->cnf.proxy_ndp))) &&
> pneigh_lookup(&nd_tbl, net, &hdr->daddr, skb->dev, 0)) {
> int proxied = ip6_forward_proxy_check(skb);
> if (proxied > 0) {
Note that there is similar chunk in ndisc_recv_na() that also ignores
idev->cnf.proxy_ndp, why don't you need to such function, too?
Thanks,
Paolo
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