linux-kernel - [PATCH v2 0/4] Atomic addfd send and reply

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Message-Id: <20210517193908.3113-1-sargun@sargun.me>
Date:   Mon, 17 May 2021 12:39:04 -0700
From:   Sargun Dhillon <sargun@...gun.me>
To:     Kees Cook <keescook@...omium.org>,
        LKML <linux-kernel@...r.kernel.org>, containers@...ts.linux.dev,
        Tycho Andersen <tycho@...ho.pizza>,
        Andy Lutomirski <luto@...nel.org>
Cc:     Sargun Dhillon <sargun@...gun.me>,
        Mauricio Vásquez Bernal <mauricio@...volk.io>,
        Rodrigo Campos <rodrigo@...volk.io>,
        Giuseppe Scrivano <gscrivan@...hat.com>,
        Christian Brauner <christian.brauner@...ntu.com>,
        Mickaël Salaün <mic@...ux.microsoft.com>
Subject: [PATCH v2 0/4] Atomic addfd send and reply

This is somewhat of a respin of "Handle seccomp notification preemption"
but without the controversial parts.

This patchset addresses a race condition we've dealt with recently with
seccomp. Specifically programs interrupting syscalls while they're in
progress. This was exacerbated by Golang's recent adoption of "async
preemption", in which they try to interrupt any syscall that's been running
for more than 10ms during GC. During certain syscalls, it's non-trivial to
write them in a reetrant manner in userspace (socket).

It focuses on one use cases, which is adding file descriptors to a process
"atomically" during the seccomp reply, as opposed to discretizing the calls
which may result in a potential file descriptor leak and inconsistent
program state.

Changes since v1:
 * Clarifcation to commit comments

Rodrigo Campos (2):
  seccomp: Support atomic "addfd + send reply"
  selftests/seccomp: Add test for atomic addfd+send

Sargun Dhillon (2):
  Documentation: seccomp: Fix user notification documentation
  seccomp: Refactor notification handler to prepare for new semantics

 .../userspace-api/seccomp_filter.rst          | 28 +++++--
 include/uapi/linux/seccomp.h                  |  1 +
 kernel/seccomp.c                              | 79 ++++++++++++++-----
 tools/testing/selftests/seccomp/seccomp_bpf.c | 38 +++++++++
 4 files changed, 120 insertions(+), 26 deletions(-)

-- 
2.25.1