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Kuniyuki Iwashima 3f84d577b7 af_unix: Inherit sk_flags at connect().
For SOCK_STREAM embryo sockets, the SO_PASS{CRED,PIDFD,SEC} options
are inherited from the parent listen()ing socket.

Currently, this inheritance happens at accept(), because these
attributes were stored in sk->sk_socket->flags and the struct socket
is not allocated until accept().

This leads to unintentional behaviour.

When a peer sends data to an embryo socket in the accept() queue,
unix_maybe_add_creds() embeds credentials into the skb, even if
neither the peer nor the listener has enabled these options.

If the option is enabled, the embryo socket receives the ancillary
data after accept().  If not, the data is silently discarded.

This conservative approach works for SO_PASS{CRED,PIDFD,SEC}, but
would not for SO_PASSRIGHTS; once an SCM_RIGHTS with a hung file
descriptor was sent, it'd be game over.

To avoid this, we will need to preserve SOCK_PASSRIGHTS even on embryo
sockets.

Commit aed6ecef55 ("af_unix: Save listener for embryo socket.")
made it possible to access the parent's flags in sendmsg() via
unix_sk(other)->listener->sk->sk_socket->flags, but this introduces
an unnecessary condition that is irrelevant for most sockets,
accept()ed sockets and clients.

Therefore, we moved SOCK_PASSXXX into struct sock.

Let’s inherit sk->sk_scm_recv_flags at connect() to avoid receiving
SCM_RIGHTS on embryo sockets created from a parent with SO_PASSRIGHTS=0.

Note that the parent socket is locked in connect() so we don't need
READ_ONCE() for sk_scm_recv_flags.

Now, we can remove !other->sk_socket check in unix_maybe_add_creds()
to avoid slow SOCK_PASS{CRED,PIDFD} handling for embryo sockets
created from a parent with SO_PASS{CRED,PIDFD}=0.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2025-05-23 10:24:18 +01:00
arch Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2025-05-22 09:42:41 -07:00
block SCSI fixes on 20250516 2025-05-16 10:28:22 -07:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2025-05-22 09:42:41 -07:00
Documentation Lots of new things, notably: 2025-05-22 14:05:18 -07:00
drivers Lots of new things, notably: 2025-05-22 14:05:18 -07:00
fs Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2025-05-22 09:42:41 -07:00
include af_unix: Move SOCK_PASS{CRED,PIDFD,SEC} to struct sock. 2025-05-23 10:24:18 +01:00
init init: remove unused CONFIG_CC_CAN_LINK_STATIC 2025-05-12 15:03:46 +09:00
io_uring Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2025-05-22 09:42:41 -07:00
ipc treewide: const qualify ctl_tables where applicable 2025-01-28 13:48:37 +01:00
kernel Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2025-05-22 09:42:41 -07:00
lib lib/crc32: remove unused support for CRC32C combination 2025-05-21 15:40:17 -07:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2025-05-22 09:42:41 -07:00
net af_unix: Inherit sk_flags at connect(). 2025-05-23 10:24:18 +01:00
rust net: phy: pass PHY driver to .match_phy_device OP 2025-05-21 15:56:09 -07:00
samples Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2025-05-15 11:28:30 -07:00
scripts Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2025-05-15 11:28:30 -07:00
security Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2025-05-22 09:42:41 -07:00
sound ALSA: hda/realtek - Add new HP ZBook laptop with micmute led fixup 2025-05-20 16:09:06 +02:00
tools tcp: Restrict SO_TXREHASH to TCP socket. 2025-05-23 10:24:18 +01:00
usr usr/include: openrisc: don't HDRTEST bpf_perf_event.h 2025-05-12 15:03:17 +09:00
virt ARM: 2025-04-08 13:47:55 -07:00
.clang-format clang-format: Update the ForEachMacros list for v6.15-rc1 2025-04-13 11:03:59 +02:00
.clippy.toml rust: clean Rust 1.88.0's warning about clippy::disallowed_macros configuration 2025-05-07 00:11:47 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore MAINTAINERS: Retire Ralf Baechle 2024-11-12 15:48:59 +01:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: Create intermediate vmlinux build with relocations preserved 2025-03-17 00:29:50 +09:00
.mailmap soc: fixes for 6.15, part 2 2025-05-14 09:11:05 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: update SLAB ALLOCATOR maintainers 2025-04-17 20:10:06 -07:00
Kbuild drm: ensure drm headers are self-contained and pass kernel-doc 2025-02-12 10:44:43 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2025-05-22 09:42:41 -07:00
Makefile Linux 6.15-rc7 2025-05-18 13:57:29 -07:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.