[PATCH v2 net-next 0/9] af_unix: Introduce SO_PASSRIGHTS

[Kuniyuki Iwashima <kuniyu@amazon.com>]

As long as recvmsg() or recvmmsg() is used with cmsg, it is not
possible to avoid receiving file descriptors via SCM_RIGHTS.

This series introduces a new socket option, SO_PASSRIGHTS, to allow
disabling SCM_RIGHTS.  The option is enabled by default.

See patch 8 for background/context.

This series is related to [0], but is split into a separate series,
as most of the patches are specific to af_unix.

The v2 of the BPF LSM extension part will be posted later, once
this series is merged into net-next and has landed in bpf-next.

[0]: https://lore.kernel.org/bpf/20250505215802.48449-1-kuniyu@amazon.com/


Changes:
  v2:
    * Added patch 4 & 5 to reuse sk_txrehash for scm_recv() flags

  v1: https://lore.kernel.org/netdev/20250508013021.79654-1-kuniyu@amazon.com/


Kuniyuki Iwashima (9):
  af_unix: Factorise test_bit() for SOCK_PASSCRED and SOCK_PASSPIDFD.
  af_unix: Don't pass struct socket to maybe_add_creds().
  scm: Move scm_recv() from scm.h to scm.c.
  tcp: Restrict SO_TXREHASH to TCP socket.
  net: Restrict SO_PASS{CRED,PIDFD,SEC} to AF_{UNIX,NETLINK,BLUETOOTH}.
  af_unix: Move SOCK_PASS{CRED,PIDFD,SEC} to struct sock.
  af_unix: Inherit sk_flags at connect().
  af_unix: Introduce SO_PASSRIGHTS.
  selftest: af_unix: Test SO_PASSRIGHTS.

 arch/alpha/include/uapi/asm/socket.h          |   2 +
 arch/mips/include/uapi/asm/socket.h           |   2 +
 arch/parisc/include/uapi/asm/socket.h         |   2 +
 arch/sparc/include/uapi/asm/socket.h          |   2 +
 include/linux/net.h                           |  15 +--
 include/net/scm.h                             | 121 +-----------------
 include/net/sock.h                            |  29 ++++-
 include/uapi/asm-generic/socket.h             |   2 +
 net/core/scm.c                                | 121 ++++++++++++++++++
 net/core/sock.c                               |  52 ++++++--
 net/unix/af_unix.c                            |  96 +++++++-------
 tools/include/uapi/asm-generic/socket.h       |   2 +
 .../selftests/net/af_unix/scm_rights.c        |  84 +++++++++++-
 13 files changed, 343 insertions(+), 187 deletions(-)

-- 
2.49.0