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/ (local)
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/ (local)
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