[PATCH net-next v2 0/3] Add SCM_PIDFD and SO_PEERPIDFD

From: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
To: davem@davemloft.net
Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
	Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>,
	Eric Dumazet <edumazet@google.com>,
	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>,
	Kuniyuki Iwashima <kuniyu@amazon.com>,
	Lennart Poettering <mzxreary@0pointer.de>
Subject: [PATCH net-next v2 0/3] Add SCM_PIDFD and SO_PEERPIDFD
Date: Tue, 21 Mar 2023 19:33:39 +0100	[thread overview]
Message-ID: <20230321183342.617114-1-aleksandr.mikhalitsyn@canonical.com> (raw)

1. Implement SCM_PIDFD, a new type of CMSG type analogical to SCM_CREDENTIALS,
but it contains pidfd instead of plain pid, which allows programmers not
to care about PID reuse problem.

2. Add SO_PEERPIDFD which allows to get pidfd of peer socket holder pidfd.
This thing is direct analog of SO_PEERCRED which allows to get plain PID.

3. Add SCM_PIDFD / SO_PEERPIDFD kselftest

Idea comes from UAPI kernel group:
https://uapi-group.org/kernel-features/

Big thanks to Christian Brauner and Lennart Poettering for productive
discussions about this.

Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: David Ahern <dsahern@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Kees Cook <keescook@chromium.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Kuniyuki Iwashima <kuniyu@amazon.com>
Cc: Lennart Poettering <mzxreary@0pointer.de>

Alexander Mikhalitsyn (3):
  scm: add SO_PASSPIDFD and SCM_PIDFD
  net: core: add getsockopt SO_PEERPIDFD
  selftests: net: add SCM_PIDFD / SO_PEERPIDFD test

 arch/alpha/include/uapi/asm/socket.h          |   3 +
 arch/mips/include/uapi/asm/socket.h           |   3 +
 arch/parisc/include/uapi/asm/socket.h         |   3 +
 arch/sparc/include/uapi/asm/socket.h          |   3 +
 include/linux/net.h                           |   1 +
 include/linux/socket.h                        |   1 +
 include/net/scm.h                             |  14 +-
 include/uapi/asm-generic/socket.h             |   3 +
 net/core/sock.c                               |  32 ++
 net/mptcp/sockopt.c                           |   1 +
 net/unix/af_unix.c                            |  18 +-
 tools/include/uapi/asm-generic/socket.h       |   3 +
 tools/testing/selftests/net/.gitignore        |   1 +
 tools/testing/selftests/net/af_unix/Makefile  |   3 +-
 .../testing/selftests/net/af_unix/scm_pidfd.c | 336 ++++++++++++++++++
 15 files changed, 417 insertions(+), 8 deletions(-)
 create mode 100644 tools/testing/selftests/net/af_unix/scm_pidfd.c

-- 
2.34.1