linux-kernel - Re: [RFC PATCH 2/3] ipv6: Run a reverse sk

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Message-ID: <Zumo9rNztx4PJgRP@GHGHG14>
Date: Tue, 17 Sep 2024 17:06:14 +0100
From: Tiago Lam <tiagolam@...udflare.com>
To: Simon Horman <horms@...nel.org>
Cc: "David S. Miller" <davem@...emloft.net>,
	David Ahern <dsahern@...nel.org>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Willem de Bruijn <willemdebruijn.kernel@...il.com>,
	Alexei Starovoitov <ast@...nel.org>,
	Daniel Borkmann <daniel@...earbox.net>,
	Andrii Nakryiko <andrii@...nel.org>,
	Martin KaFai Lau <martin.lau@...ux.dev>,
	Eduard Zingerman <eddyz87@...il.com>, Song Liu <song@...nel.org>,
	Yonghong Song <yonghong.song@...ux.dev>,
	John Fastabend <john.fastabend@...il.com>,
	KP Singh <kpsingh@...nel.org>, Stanislav Fomichev <sdf@...ichev.me>,
	Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>,
	Mykola Lysenko <mykolal@...com>, Shuah Khan <shuah@...nel.org>,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	bpf@...r.kernel.org, linux-kselftest@...r.kernel.org,
	Jakub Sitnicki <jakub@...udflare.com>, kernel-team@...udflare.com
Subject: Re: [RFC PATCH 2/3] ipv6: Run a reverse sk_lookup on sendmsg.

On Sat, Sep 14, 2024 at 09:59:50AM +0100, Simon Horman wrote:
> On Fri, Sep 13, 2024 at 10:39:20AM +0100, Tiago Lam wrote:
> > This follows the same rationale provided for the ipv4 counterpart, where
> > it now runs a reverse socket lookup when source addresses and/or ports
> > are changed, on sendmsg, to check whether egress traffic should be
> > allowed to go through or not.
> > 
> > As with ipv4, the ipv6 sendmsg path is also extended here to support the
> > IPV6_ORIGDSTADDR ancilliary message to be able to specify a source
> 
> Hi Tiago Lam,
> 
> Some minor nits from my side.
> 
> ancilliary -> ancillary
> 
> Likewise in patch 3/3.
> Flagged by checkpatch.pl --codespell
> 
> > address/port.
> > 
> > Suggested-by: Jakub Sitnicki <jakub@...udflare.com>
> > Signed-off-by: Tiago Lam <tiagolam@...udflare.com>
> > ---
> >  net/ipv6/datagram.c | 76 +++++++++++++++++++++++++++++++++++++++++++++++++++++
> >  net/ipv6/udp.c      |  8 ++++--
> >  2 files changed, 82 insertions(+), 2 deletions(-)
> > 
> > diff --git a/net/ipv6/datagram.c b/net/ipv6/datagram.c
> > index fff78496803d..4214dda1c320 100644
> > --- a/net/ipv6/datagram.c
> > +++ b/net/ipv6/datagram.c
> > @@ -756,6 +756,27 @@ void ip6_datagram_recv_ctl(struct sock *sk, struct msghdr *msg,
> >  }
> >  EXPORT_SYMBOL_GPL(ip6_datagram_recv_ctl);
> >  
> > +static inline bool reverse_sk_lookup(struct flowi6 *fl6, struct sock *sk,
> > +				     struct in6_addr *saddr, __be16 sport)
> > +{
> > +	if (static_branch_unlikely(&bpf_sk_lookup_enabled) &&
> > +	    (saddr && sport) &&
> > +	    (ipv6_addr_cmp(&sk->sk_v6_rcv_saddr, saddr) || inet_sk(sk)->inet_sport != sport)) {
> 
> Please consider, where it can trivially be achieved, limiting Networking
> code to 80 columns wide.
> 
> Checkpatch can be run with a flag to check for this.
> 

Thanks for the hints here, I've addressed these and will include the
changes into the next revision. I use b4 which takes care of some of
this checks, but I'll make sure I change my settings to use
`--max-line-length=80` as well.

Tiago.