# \[PATCH v3 net-next 0/9\] af\_unix: Introduce SO\_PASSRIGHTS.

- From: Kuniyuki Iwashima \<hidden\>
- Date: 2025-05-14 16:52:39 
- List: netdev
- Page: https://ratatoskr.run/netdev/2025/05/11327261
- Thread: https://ratatoskr.run/netdev/2025/05/11327261/t.md

```text
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:
  v3:
    * Patch 3
      * Remove inline in scm.c
    * Patch 4 & 5 & 8
      * Return -EOPNOTSUPP in getsockopt()
    * Patch 5
      * Add CONFIG_SECURITY_NETWORK check for SO_PASSSEC
    * Patch 6
      * Add kdoc for sk_scm_unused
      * Update sk_scm_XXX under lock_sock() in setsockopt()
    * Patch 7
      * Update changelog (recent change -> aed6ecef55d7)

  v2: https://lore.kernel.org/netdev/20250510015652.9931-1-kuniyu@amazon.com/
    * 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                            |  30 ++++-
 include/uapi/asm-generic/socket.h             |   2 +
 net/core/scm.c                                | 122 ++++++++++++++++++
 net/core/sock.c                               |  63 +++++++--
 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, 352 insertions(+), 191 deletions(-)

-- 
2.49.0

```