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Ondrej Mosnacek
30500acfc4
commit9fe595fad5upstream. The commit fixing the overlayfs mmap() and mprotect() access checks failed to skip the execmem check in __file_map_prot_check() for the case where the "mounter check" is being performed. This check should be performed only against the credentials of the task that is calling mmap()/mprotect(), since it doesn't pertain to the file itself, but rather just gates the ability of the calling task to get an executable memory mapping in general. The purpose of the "mounter check" is to guard against using an overlayfs mount to gain file access that would otherwise be denied to the mounter. For execmem this is not relevant, as there is no further file access granted based on it (notice that the file's context is not used as the target in the check), so checking it also against the mounter credentials would be incorrect. Fix this by passing a boolean to [__]file_map_prot_check() and selinux_mmap_file_common() that indicates if we are doing the "mounter check" and skiping the execmem check in that case. Since this boolean also indicates if we use current_cred() or the mounter cred as the subject, also remove the "cred" argument from these functions and determine it based on the boolean and the file struct. Cc: stable@vger.kernel.org Fixes:82544d36b1("selinux: fix overlayfs mmap() and mprotect() access checks") Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com> Reviewed-by: Stephen Smalley <stephen.smalley.work@gmail.com> Signed-off-by: Paul Moore <paul@paul-moore.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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.