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References: <20230511132506.379102-1-aleksandr.mikhalitsyn@canonical.com> <ZFzuvDopKWB9wmQf@t14s.localdomain>
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From:   Xin Long <lucien.xin@gmail.com>
Date:   Thu, 11 May 2023 10:20:57 -0400
Message-ID: <CADvbK_daDKfwDimJ=uovyO86i4KJZM32305fG70pSWw3Qe89Pg@mail.gmail.com>
Subject: Re: [PATCH net-next v3] sctp: add bpf_bypass_getsockopt proto callback
To:     Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Cc:     Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>,
        nhorman@tuxdriver.com, davem@davemloft.net,
        Daniel Borkmann <daniel@iogearbox.net>,
        Christian Brauner <brauner@kernel.org>,
        Stanislav Fomichev <sdf@google.com>,
        linux-sctp@vger.kernel.org, linux-kernel@vger.kernel.org,
        netdev@vger.kernel.org
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On Thu, May 11, 2023 at 9:33=E2=80=AFAM Marcelo Ricardo Leitner
<marcelo.leitner@gmail.com> wrote:
>
> On Thu, May 11, 2023 at 03:25:06PM +0200, Alexander Mikhalitsyn wrote:
> > Implement ->bpf_bypass_getsockopt proto callback and filter out
> > SCTP_SOCKOPT_PEELOFF, SCTP_SOCKOPT_PEELOFF_FLAGS and SCTP_SOCKOPT_CONNE=
CTX3
> > socket options from running eBPF hook on them.
> >
> > SCTP_SOCKOPT_PEELOFF and SCTP_SOCKOPT_PEELOFF_FLAGS options do fd_insta=
ll(),
> > and if BPF_CGROUP_RUN_PROG_GETSOCKOPT hook returns an error after succe=
ss of
> > the original handler sctp_getsockopt(...), userspace will receive an er=
ror
> > from getsockopt syscall and will be not aware that fd was successfully
> > installed into a fdtable.
> >
> > As pointed by Marcelo Ricardo Leitner it seems reasonable to skip
> > bpf getsockopt hook for SCTP_SOCKOPT_CONNECTX3 sockopt too.
> > Because internaly, it triggers connect() and if error is masked
> > then userspace will be confused.
> >
> > This patch was born as a result of discussion around a new SCM_PIDFD in=
terface:
> > https://lore.kernel.org/all/20230413133355.350571-3-aleksandr.mikhalits=
yn@canonical.com/
> >
> > Fixes: 0d01da6afc54 ("bpf: implement getsockopt and setsockopt hooks")
> > Cc: Daniel Borkmann <daniel@iogearbox.net>
> > Cc: Christian Brauner <brauner@kernel.org>
> > Cc: Stanislav Fomichev <sdf@google.com>
> > Cc: Neil Horman <nhorman@tuxdriver.com>
> > Cc: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
> > Cc: Xin Long <lucien.xin@gmail.com>
> > Cc: linux-sctp@vger.kernel.org
> > Cc: linux-kernel@vger.kernel.org
> > Cc: netdev@vger.kernel.org
> > Suggested-by: Stanislav Fomichev <sdf@google.com>
> > Acked-by: Stanislav Fomichev <sdf@google.com>
> > Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.c=
om>
>
> Thx!
>
> Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Acked-by: Xin Long <lucien.xin@gmail.com>