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References: <20230316131526.283569-1-aleksandr.mikhalitsyn@canonical.com> <20230316131526.283569-2-aleksandr.mikhalitsyn@canonical.com>
In-Reply-To: <20230316131526.283569-2-aleksandr.mikhalitsyn@canonical.com>
From:   Eric Dumazet <edumazet@google.com>
Date:   Thu, 16 Mar 2023 07:34:24 -0700
Message-ID: <CANn89i+s7TG4jqC1qanboKff=-DRmDjB-vEkoLKbEDwv195ytg@mail.gmail.com>
Subject: Re: [PATCH net-next 1/3] scm: add SO_PASSPIDFD and SCM_PIDFD
To:     Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
Cc:     davem@davemloft.net, linux-kernel@vger.kernel.org,
        netdev@vger.kernel.org, Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Leon Romanovsky <leon@kernel.org>,
        David Ahern <dsahern@kernel.org>,
        Arnd Bergmann <arnd@arndb.de>,
        Kees Cook <keescook@chromium.org>,
        Christian Brauner <brauner@kernel.org>,
        linux-arch@vger.kernel.org
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On Thu, Mar 16, 2023 at 6:16=E2=80=AFAM Alexander Mikhalitsyn
<aleksandr.mikhalitsyn@canonical.com> wrote:
>
> Implement SCM_PIDFD, a new type of CMSG type analogical to SCM_CREDENTIAL=
S,
> but it contains pidfd instead of plain pid, which allows programmers not
> to care about PID reuse problem.

Hi Alexander

This would add yet another conditional in af_unix fast path.

It seems that we already can use pidfd_open() (since linux-5.3), and
pass the resulting fd in af_unix SCM_RIGHTS message ?

If you think this is not suitable, it should at least be mentioned in
the changelog.

Thanks.