From: Stephen Smalley sds@tycho.nsa.gov
commit 98aa00345de54b8340dc2ddcd87f446d33387b5e upstream.
commit 2db154b3ea8e ("vfs: syscall: Add move_mount(2) to move mounts around") introduced a new move_mount(2) system call and a corresponding new LSM security_move_mount hook but did not implement this hook for any existing LSM. This creates a regression for SELinux with respect to consistent checking of mounts; the existing selinux_mount hook checks mounton permission to the mount point path. Provide a SELinux hook implementation for move_mount that applies this same check for consistency. In the future we may wish to add a new move_mount filesystem permission and check as well, but this addresses the immediate regression.
Fixes: 2db154b3ea8e ("vfs: syscall: Add move_mount(2) to move mounts around") Signed-off-by: Stephen Smalley sds@tycho.nsa.gov Reviewed-by: Ondrej Mosnacek omosnace@redhat.com Signed-off-by: Paul Moore paul@paul-moore.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- security/selinux/hooks.c | 10 ++++++++++ 1 file changed, 10 insertions(+)
--- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -2762,6 +2762,14 @@ static int selinux_mount(const char *dev return path_has_perm(cred, path, FILE__MOUNTON); }
+static int selinux_move_mount(const struct path *from_path, + const struct path *to_path) +{ + const struct cred *cred = current_cred(); + + return path_has_perm(cred, to_path, FILE__MOUNTON); +} + static int selinux_umount(struct vfsmount *mnt, int flags) { const struct cred *cred = current_cred(); @@ -6904,6 +6912,8 @@ static struct security_hook_list selinux LSM_HOOK_INIT(sb_clone_mnt_opts, selinux_sb_clone_mnt_opts), LSM_HOOK_INIT(sb_add_mnt_opt, selinux_add_mnt_opt),
+ LSM_HOOK_INIT(move_mount, selinux_move_mount), + LSM_HOOK_INIT(dentry_init_security, selinux_dentry_init_security), LSM_HOOK_INIT(dentry_create_files_as, selinux_dentry_create_files_as),