9a852bcf90
[ Upstream commit bf1ac16edf6770a92bc75cf2373f1f9feea398a4 ]
Idmapped mounts should not allow a user to map file ownsership into a
range of ids which is not under the control of that user. However, we
currently don't check whether the mounter is privileged wrt to the
target user namespace.
Currently no FS_USERNS_MOUNT filesystems support idmapped mounts, thus
this is not a problem as only CAP_SYS_ADMIN in init_user_ns is allowed
to set up idmapped mounts. But this could change in the future, so add a
check to refuse to create idmapped mounts when the mounter does not have
CAP_SYS_ADMIN in the target user namespace.
Fixes: bd303368b776 ("fs: support mapped mounts of mapped filesystems")
Signed-off-by: Seth Forshee <sforshee@digitalocean.com>
Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Link: https://lore.kernel.org/r/20220816164752.2595240-1-sforshee@digitalocean.com
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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.