My "smart" email provider blocker me from sending more email. Since I am in South Korea
that is apparently suspicious. Now patch 4 is missing. I'll try to rectify that. Is there
any sane email provider that any of you use?
Thanks,
Jori.
> Op 13-08-2026 12:28 EDT schreef Jori Koolstra <jkoolstra@xs4all.nl>:
>
>
> Right now if some LSM denies an AF_UNIX socket peer to receive a
> SCM_RIGHTS fd, the SCM_RIGHTS fd array will be cut short at
> that point, and MSG_CTRUNC is set on return of recvmsg(2). This is
> highly problematic behaviour, because it leaves the receiver
> wondering what happened. As per man page MSG_CTRUNC is supposed to
> indicate that the control buffer was sized too short, but suddenly
> a permission error might result in the exact same flag being set.
> Moreover, the receiver has no chance to determine how many fds got
> originally sent and how many were suppressed.[1]
>
> Add a SO_RIGHTS_NOTRUNC option to UNIX sockets to enable more useful
> handling of LSM denials when receiving SCM_RIGHTS messages: instead of
> truncating the message at the first blocked fd, keep every fd slot
> and store the LSM errno in the blocked slot. This option is inherited
> by the accept()-ed socket when set on the listen() socket.
>
> [1]: https://github.com/uapi-group/kernel-features#useful-handling-of-lsm-denials-on-scm_rights
>
> Changes:
> v7:
> - block first selftests did not check other slots
> - READ_ONCE() for scm_rights_notrunc field
> v6:
> - Let accept()-ed sockets inherit the SO_RIGHTS_NOTRUNC option from
> the listen() socket, so that you don't need to set it for every
> child.
> v5:
> - Enable SO_RIGHTS_NOTRUNC on all AF_UNIX socket types.
> - Added required BPF CONFIG_ options to
> tools/testing/selftests/net/af_unix/config.
> v4: https://lore.kernel.org/netdev/20260705123826.3818443-1-jkoolstra@xs4all.nl/
> - Removed the __receive_fd() helper and moved logic into
> scm_recv_one_fd() directly (suggested by Brauner).
> - Moved selftest from Smack to BPF (LLM assisted).
> - Add arch specific socket option values for SO_RIGHTS_NOTRUNC.
> - Undo patch that replaced copy_from_sockptr() with
> copy_safe_from_sockptr().
> v3:
> - Separated net and vfs changes.
> - Use kselftest_harness.h and system() to call the test script.
> v2: https://lore.kernel.org/netdev/20260616143020.3458085-2-jkoolstra@xs4all.nl/
> - Reimplemented as a UNIX socket option instead of a per recvmsg(2) flag.
> v1: https://lore.kernel.org/netdev/20260428175125.2705296-1-jkoolstra@xs4all.nl/
>
> *** BLURB HERE ***
>
> Jori Koolstra (4):
> net: af_unix: enable custom setsockopt for all socket types
> net: scm: move scm_detach_fds() from common path to scm_recv_unix()
> net: af_unix: useful handling of LSM denials on SCM_RIGHTS
> selftest: Add tests for useful handling of LSM denials on SCM_RIGHTS
>
> 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/net/af_unix.h | 1 +
> include/net/scm.h | 13 +-
> include/uapi/asm-generic/socket.h | 2 +
> net/compat.c | 4 +-
> net/core/scm.c | 40 ++-
> net/unix/af_unix.c | 22 +-
> .../testing/selftests/net/af_unix/.gitignore | 2 +
> tools/testing/selftests/net/af_unix/Makefile | 8 +
> tools/testing/selftests/net/af_unix/config | 7 +
> .../net/af_unix/scm_rights_denial_lsm.bpf.c | 36 +++
> .../net/af_unix/scm_rights_denial_lsm.c | 292 ++++++++++++++++++
> 15 files changed, 413 insertions(+), 22 deletions(-)
> create mode 100644 tools/testing/selftests/net/af_unix/scm_rights_denial_lsm.bpf.c
> create mode 100644 tools/testing/selftests/net/af_unix/scm_rights_denial_lsm.c
>
>
> base-commit: 3205699d79f262412c1be7fc1c04066610d3cd52
> --
> 2.55.0