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Date: Tue, 8 Aug 2023 15:00:11 +0200
From: Simon Horman <horms@kernel.org>
To: David Rheinsberg <david@readahead.eu>
Cc: netdev@vger.kernel.org, Alexander Mikhalitsyn <alexander@mihalicyn.com>,
	Christian Brauner <brauner@kernel.org>,
	"David S . Miller" <davem@davemloft.net>,
	Stanislav Fomichev <sdf@google.com>,
	Luca Boccassi <bluca@debian.org>,
	Eric Dumazet <edumazet@google.com>
Subject: Re: [PATCH] net/unix: use consistent error code in SO_PEERPIDFD
Message-ID: <ZNI8W78I3FxvT333@vergenet.net>
References: <20230807081225.816199-1-david@readahead.eu>
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In-Reply-To: <20230807081225.816199-1-david@readahead.eu>

On Mon, Aug 07, 2023 at 10:12:25AM +0200, David Rheinsberg wrote:
> Change the new (unreleased) SO_PEERPIDFD sockopt to return ENODATA
> rather than ESRCH if a socket type does not support remote peer-PID
> queries.
> 
> Currently, SO_PEERPIDFD returns ESRCH when the socket in question is
> not an AF_UNIX socket. This is quite unexpected, given that one would
> assume ESRCH means the peer process already exited and thus cannot be
> found. However, in that case the sockopt actually returns EINVAL (via
> pidfd_prepare()). This is rather inconsistent with other syscalls, which
> usually return ESRCH if a given PID refers to a non-existant process.
> 
> This changes SO_PEERPIDFD to return ENODATA instead. This is also what
> SO_PEERGROUPS returns, and thus keeps a consistent behavior across
> sockopts.
> 
> Note that this code is returned in 2 cases: First, if the socket type is
> not AF_UNIX, and secondly if the socket was not yet connected. In both
> cases ENODATA seems suitable.
> 
> Signed-off-by: David Rheinsberg <david@readahead.eu>
> ---
> Hi!
> 
> The SO_PEERPIDFD sockopt has been queued for 6.5, so hopefully we can
> get that in before the release?
> 
> Thanks
> David

As a fix, it should probably have a fixes tag.
This one seems appropriate.

Fixes: 7b26952a91cf ("net: core: add getsockopt SO_PEERPIDFD")

And the patch should be targeted at net

	Subject: [PATCH net] ...

It's probably not necessary to repost just to address these minor points.
But please consider them if you need to post a v2 for some other reason.