Since commit c84bf6dd2b ("mm: introduce new .mmap_prepare() file
callback"), the f_op->mmap() hook has been deprecated in favour of
f_op->mmap_prepare().
Additionally, commit bb666b7c27 ("mm: add mmap_prepare() compatibility
layer for nested file systems") permits the use of the .mmap_prepare() hook
even in nested filesystems like overlayfs.
There are a number of places where we check only for f_op->mmap - this is
incorrect now mmap_prepare exists, so update all of these to use the
general helper can_mmap_file().
Most notably, this updates the elf logic to allow for the ability to
execute binaries on filesystems which have the .mmap_prepare hook, but
additionally we update nested filesystems.
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Link: https://lore.kernel.org/b68145b609532e62bab603dd9686faa6562046ec.1750099179.git.lorenzo.stoakes@oracle.com
Acked-by: Kees Cook <kees@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
The call_mmap() function violates the existing convention in
include/linux/fs.h whereby invocations of virtual file system hooks is
performed by functions prefixed with vfs_xxx().
Correct this by renaming call_mmap() to vfs_mmap(). This also avoids
confusion as to the fact that f_op->mmap_prepare may be invoked here.
Also rename __call_mmap_prepare() function to vfs_mmap_prepare() and adjust
to accept a file parameter, this is useful later for nested file systems.
Finally, fix up the VMA userland tests and ensure the mmap_prepare -> mmap
shim is implemented there.
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Link: https://lore.kernel.org/8d389f4994fa736aa8f9172bef8533c10a9e9011.1750099179.git.lorenzo.stoakes@oracle.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
As the credentials used by backing-file are long lived in relation to
the critical section (override_creds() -> revert_creds()) we can
replace them by their lighter alternatives.
Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
- Pass iocb to ctx->end_write() instead of file + pos
- Get rid of ctx->user_file, which is redundant most of the time
- Instead pass iocb to backing_file_splice_read and
backing_file_splice_write
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Combine inode creation with opening a file.
There are six separate objects that are being set up: the backing inode,
dentry and file, and the overlay inode, dentry and file. Cleanup in case
of an error is a bit of a challenge and is difficult to test, so careful
review is needed.
All tmpfile testcases except generic/509 now run/pass, and no regressions
are observed with full xfstests.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Assert that the file object is allocated in a backing_file container
so that file_user_path() could be used to display the user path and
not the backing file's path in /proc/<pid>/maps.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
There is not much in those helpers, but it makes sense to have them
logically next to the backing_file_{read,write}_iter() helpers as they
may grow more common logic in the future.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
In preparation for factoring out some backing file io helpers from
overlayfs, move backing_file_open() into a new file fs/backing-file.c
and header.
Add a MAINTAINERS entry for stackable filesystems and add a Kconfig
FS_STACK which stackable filesystems need to select.
For now, the backing_file struct, the backing_file alloc/free functions
and the backing_file_real_path() accessor remain internal to file_table.c.
We may change that in the future.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
