Commit 98aa0034 authored Jan 17, 2020 by Stephen Smalley Committed by Paul Moore Jan 20, 2020

selinux: fix regression introduced by move_mount(2) syscall



commit 2db154b3 ("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: 2db154b3 ("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>

parent dd89b9d9

security/selinux/hooks.c

+10 −0

Original line number	Diff line number	Diff line
		@@ -2724,6 +2724,14 @@ static int selinux_mount(const char *dev_name,
		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();
		@@ -6913,6 +6921,8 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
		LSM_HOOK_INIT(sb_set_mnt_opts, selinux_set_mnt_opts),
		LSM_HOOK_INIT(sb_clone_mnt_opts, selinux_sb_clone_mnt_opts),

		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),

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