mirror of
https://github.com/torvalds/linux.git
synced 2026-05-05 23:05:25 -04:00
bc4eee85ca
Pull vfs fixes from Christian Brauner:
"This contains two fixes for this merge window:
VFS:
- I noticed that it is possible for a privileged user to mount most
filesystems with a non-initial user namespace in sb->s_user_ns.
When fsopen() is called in a non-init namespace the caller's
namespace is recorded in fs_context->user_ns. If the returned file
descriptor is then passed to a process privileged in init_user_ns,
that process can call fsconfig(fd_fs, FSCONFIG_CMD_CREATE*),
creating a new superblock with sb->s_user_ns set to the namespace
of the process which called fsopen().
This is problematic as only filesystems that raise FS_USERNS_MOUNT
are known to be able to support a non-initial s_user_ns. Others may
suffer security issues, on-disk corruption or outright crash the
kernel. Prevent that by restricting such delegation to filesystems
that allow FS_USERNS_MOUNT.
Note, that this delegation requires a privileged process to
actually create the superblock so either the privileged process is
cooperaing or someone must have tricked a privileged process into
operating on a fscontext file descriptor whose origin it doesn't
know (a stupid idea).
The bug dates back to about 5 years afaict.
Misc:
- Fix hostfs parsing when the mount request comes in via the legacy
mount api.
In the legacy mount api hostfs allows to specify the host directory
mount without any key.
Restore that behavior"
* tag 'vfs-6.11-rc1.fixes.3' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
hostfs: fix the host directory parse when mounting.
fs: don't allow non-init s_user_ns for filesystems without FS_USERNS_MOUNT
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.