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Jann Horn 0618021e34 fuse: Remove user_ns check for FUSE_DEV_IOC_CLONE
Commit 8ed1f0e22f ("fs/fuse: fix ioctl type confusion") fixed a type
confusion bug by adding an ->f_op comparison.

Based on some off-list discussion back then, another check was added to
compare the f_cred->user_ns.  This is not for security reasons, but was
based on the idea that a FUSE device FD should be using the UID/GID
mappings of its f_cred->user_ns, and those translations are done using
fc->user_ns, which matches the f_cred->user_ns of the initial FUSE device
FD thanks to the check in fuse_fill_super().  See also commit 8cb08329b0
("fuse: Support fuse filesystems outside of init_user_ns").

But FUSE_DEV_IOC_CLONE is, at a higher level, a *cloning* operation that
copies an existing context (with a weird API that involves first opening
/dev/fuse, then tying the resulting new FUSE device FD to an existing FUSE
instance).  So if an application is already passing FUSE FDs across userns
boundaries and dealing with the resulting ID mapping complications somehow,
it doesn't make much sense to block this cloning operation.

I've heard that this check is an obstacle for some folks, and I don't see a
good reason to keep it, so remove it.

Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2022-11-23 09:10:49 +01:00
arch - Do not hold fpregs lock when inheriting FPU permissions because the 2022-11-20 10:47:39 -08:00
block block-6.1-2022-11-18 2022-11-18 13:59:45 -08:00
certs certs: make system keyring depend on built-in x509 parser 2022-09-24 04:31:18 +09:00
crypto treewide: use get_random_bytes() when possible 2022-10-11 17:42:58 -06:00
Documentation Input updates for v6.1-rc5 2022-11-18 17:56:29 -08:00
drivers SCSI fixes on 20221119 2022-11-19 15:51:22 -08:00
fs fuse: Remove user_ns check for FUSE_DEV_IOC_CLONE 2022-11-23 09:10:49 +01:00
include fuse: add "expire only" mode to FUSE_NOTIFY_INVAL_ENTRY 2022-11-23 09:10:49 +01:00
init init: Kconfig: fix spelling mistake "satify" -> "satisfy" 2022-10-20 21:27:22 -07:00
io_uring io_uring: disallow self-propelled ring polling 2022-11-18 09:29:31 -07:00
ipc ipc/msg.c: fix percpu_counter use after free 2022-10-28 13:37:22 -07:00
kernel tracing/probes: Fixes for v6.1 2022-11-20 15:31:20 -08:00
lib maple_tree: don't set a new maximum on the node when not reusing nodes 2022-11-08 15:57:25 -08:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm Networking fixes for 6.1-rc6, including fixes from bpf 2022-11-17 08:58:36 -08:00
net tcp: configurable source port perturb table size 2022-11-16 13:02:04 +00:00
rust Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
samples VFIO updates for v6.1-rc1 2022-10-12 14:46:48 -07:00
scripts kbuild: Restore .version auto-increment behaviour for Debian packages 2022-11-17 17:51:45 +09:00
security lsm/stable-6.1 PR 20221031 2022-10-31 12:09:42 -07:00
sound ALSA: hda/realtek: Fix the speaker output on Samsung Galaxy Book Pro 360 2022-11-15 18:03:31 +01:00
tools Char/Misc driver fixes for 6.1-rc6 2022-11-18 10:29:25 -08:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt Merge tag 'kvmarm-fixes-6.1-3' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD 2022-11-06 03:30:49 -05:00
.clang-format PCI/DOE: Add DOE mailbox support functions 2022-07-19 15:38:04 -07:00
.cocciconfig
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
.mailmap sound fixes for 6.1-rc6 2022-11-18 09:52:10 -08:00
.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: Remove Michal Marek from Kbuild maintainers 2022-11-16 14:53:00 +09:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Kbuild fixes for v6.1 (3rd) 2022-11-19 09:03:20 -08:00
Makefile Linux 6.1-rc6 2022-11-20 16:02:16 -08:00
README

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 Restructured Text 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.