ovl: use vfs_set_acl_prepare()

The posix_acl_from_xattr() helper should mainly be used in
i_op->get_acl() handlers. It translates from the uapi struct into the
kernel internal POSIX ACL representation and doesn't care about mount
idmappings.

Use the vfs_set_acl_prepare() helper to generate a kernel internal POSIX
ACL representation in struct posix_acl format taking care to map from
the mount idmapping into the filesystem's idmapping.

The returned struct posix_acl is in the correct format to be cached by
the VFS or passed to the filesystem's i_op->set_acl() method to write to
the backing store.

Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Reviewed-by: Seth Forshee (DigitalOcean) <sforshee@kernel.org>
This commit is contained in:
Christian Brauner 2022-08-29 14:38:44 +02:00 committed by Christian Brauner (Microsoft)
parent 52edb4080e
commit 7e1401acd9
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1 changed files with 14 additions and 1 deletions

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@ -1022,7 +1022,20 @@ ovl_posix_acl_xattr_set(const struct xattr_handler *handler,
/* Check that everything is OK before copy-up */
if (value) {
acl = posix_acl_from_xattr(&init_user_ns, value, size);
/* The above comment can be understood in two ways:
*
* 1. We just want to check whether the basic POSIX ACL format
* is ok. For example, if the header is correct and the size
* is sane.
* 2. We want to know whether the ACL_{GROUP,USER} entries can
* be mapped according to the underlying filesystem.
*
* Currently, we only check 1. If we wanted to check 2. we
* would need to pass the mnt_userns and the fs_userns of the
* underlying filesystem. But frankly, I think checking 1. is
* enough to start the copy-up.
*/
acl = vfs_set_acl_prepare(&init_user_ns, &init_user_ns, value, size);
if (IS_ERR(acl))
return PTR_ERR(acl);
}