vfs: Suppress MS_* flag defs within the kernel unless explicitly enabled

Only the mount namespace code that implements mount(2) should be using the
MS_* flags.  Suppress them inside the kernel unless uapi/linux/mount.h is
included.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Reviewed-by: David Howells <dhowells@redhat.com>

arch/arc/kernel/setup.c

@@ -19,6 +19,7 @@
 #include <linux/of_fdt.h>
 #include <linux/of.h>
 #include <linux/cache.h>
+#include <uapi/linux/mount.h>
 #include <asm/sections.h>
 #include <asm/arcregs.h>
 #include <asm/tlb.h>

arch/arm/kernel/atags_parse.c

@@ -24,6 +24,7 @@
 #include <linux/root_dev.h>
 #include <linux/screen_info.h>
 #include <linux/memblock.h>
+#include <uapi/linux/mount.h>
 
 #include <asm/setup.h>
 #include <asm/system_info.h>

arch/sh/kernel/setup.c

@@ -32,6 +32,7 @@
 #include <linux/of.h>
 #include <linux/of_fdt.h>
 #include <linux/uaccess.h>
+#include <uapi/linux/mount.h>
 #include <asm/io.h>
 #include <asm/page.h>
 #include <asm/elf.h>

arch/sparc/kernel/setup_32.c

@@ -34,6 +34,7 @@
 #include <linux/kdebug.h>
 #include <linux/export.h>
 #include <linux/start_kernel.h>
+#include <uapi/linux/mount.h>
 
 #include <asm/io.h>
 #include <asm/processor.h>

arch/sparc/kernel/setup_64.c

@@ -33,6 +33,7 @@
 #include <linux/module.h>
 #include <linux/start_kernel.h>
 #include <linux/memblock.h>
+#include <uapi/linux/mount.h>
 
 #include <asm/io.h>
 #include <asm/processor.h>

arch/x86/kernel/setup.c

@@ -50,6 +50,7 @@
 #include <linux/kvm_para.h>
 #include <linux/dma-contiguous.h>
 #include <xen/xen.h>
+#include <uapi/linux/mount.h>
 
 #include <linux/errno.h>
 #include <linux/kernel.h>

drivers/base/devtmpfs.c

@@ -25,6 +25,7 @@
 #include <linux/sched.h>
 #include <linux/slab.h>
 #include <linux/kthread.h>
+#include <uapi/linux/mount.h>
 #include "base.h"
 
 static struct task_struct *thread;

fs/namespace.c

@@ -26,6 +26,7 @@
 #include <linux/memblock.h>
 #include <linux/task_work.h>
 #include <linux/sched/task.h>
+#include <uapi/linux/mount.h>
 
 #include "pnode.h"
 #include "internal.h"

fs/pnode.c

@@ -10,6 +10,7 @@
 #include <linux/mount.h>
 #include <linux/fs.h>
 #include <linux/nsproxy.h>
+#include <uapi/linux/mount.h>
 #include "internal.h"
 #include "pnode.h"
 

fs/super.c

@@ -35,6 +35,7 @@
 #include <linux/fsnotify.h>
 #include <linux/lockdep.h>
 #include <linux/user_namespace.h>
+#include <uapi/linux/mount.h>
 #include "internal.h"
 
 static int thaw_super_locked(struct super_block *sb);

include/uapi/linux/fs.h

@@ -14,6 +14,11 @@
 #include <linux/ioctl.h>
 #include <linux/types.h>
 
+/* Use of MS_* flags within the kernel is restricted to core mount(2) code. */
+#if !defined(__KERNEL__)
+#include <linux/mount.h>
+#endif
+
 /*
  * It's silly to have NR_OPEN bigger than NR_FILE, but you can change
  * the file limit at runtime and only root can increase the per-process
@@ -101,57 +106,6 @@ struct inodes_stat_t {
 
 #define NR_FILE  8192	/* this can well be larger on a larger system */
 
-
-/*
- * These are the fs-independent mount-flags: up to 32 flags are supported
- */
-#define MS_RDONLY	 1	/* Mount read-only */
-#define MS_NOSUID	 2	/* Ignore suid and sgid bits */
-#define MS_NODEV	 4	/* Disallow access to device special files */
-#define MS_NOEXEC	 8	/* Disallow program execution */
-#define MS_SYNCHRONOUS	16	/* Writes are synced at once */
-#define MS_REMOUNT	32	/* Alter flags of a mounted FS */
-#define MS_MANDLOCK	64	/* Allow mandatory locks on an FS */
-#define MS_DIRSYNC	128	/* Directory modifications are synchronous */
-#define MS_NOATIME	1024	/* Do not update access times. */
-#define MS_NODIRATIME	2048	/* Do not update directory access times */
-#define MS_BIND		4096
-#define MS_MOVE		8192
-#define MS_REC		16384
-#define MS_VERBOSE	32768	/* War is peace. Verbosity is silence.
-				   MS_VERBOSE is deprecated. */
-#define MS_SILENT	32768
-#define MS_POSIXACL	(1<<16)	/* VFS does not apply the umask */
-#define MS_UNBINDABLE	(1<<17)	/* change to unbindable */
-#define MS_PRIVATE	(1<<18)	/* change to private */
-#define MS_SLAVE	(1<<19)	/* change to slave */
-#define MS_SHARED	(1<<20)	/* change to shared */
-#define MS_RELATIME	(1<<21)	/* Update atime relative to mtime/ctime. */
-#define MS_KERNMOUNT	(1<<22) /* this is a kern_mount call */
-#define MS_I_VERSION	(1<<23) /* Update inode I_version field */
-#define MS_STRICTATIME	(1<<24) /* Always perform atime updates */
-#define MS_LAZYTIME	(1<<25) /* Update the on-disk [acm]times lazily */
-
-/* These sb flags are internal to the kernel */
-#define MS_SUBMOUNT     (1<<26)
-#define MS_NOREMOTELOCK	(1<<27)
-#define MS_NOSEC	(1<<28)
-#define MS_BORN		(1<<29)
-#define MS_ACTIVE	(1<<30)
-#define MS_NOUSER	(1<<31)
-
-/*
- * Superblock flags that can be altered by MS_REMOUNT
- */
-#define MS_RMT_MASK	(MS_RDONLY|MS_SYNCHRONOUS|MS_MANDLOCK|MS_I_VERSION|\
-			 MS_LAZYTIME)
-
-/*
- * Old magic mount flag and mask
- */
-#define MS_MGC_VAL 0xC0ED0000
-#define MS_MGC_MSK 0xffff0000
-
 /*
  * Structure for FS_IOC_FSGETXATTR[A] and FS_IOC_FSSETXATTR.
  */

include/uapi/linux/mount.h

@@ -0,0 +1,58 @@
+#ifndef _UAPI_LINUX_MOUNT_H
+#define _UAPI_LINUX_MOUNT_H
+
+/*
+ * These are the fs-independent mount-flags: up to 32 flags are supported
+ *
+ * Usage of these is restricted within the kernel to core mount(2) code and
+ * callers of sys_mount() only.  Filesystems should be using the SB_*
+ * equivalent instead.
+ */
+#define MS_RDONLY	 1	/* Mount read-only */
+#define MS_NOSUID	 2	/* Ignore suid and sgid bits */
+#define MS_NODEV	 4	/* Disallow access to device special files */
+#define MS_NOEXEC	 8	/* Disallow program execution */
+#define MS_SYNCHRONOUS	16	/* Writes are synced at once */
+#define MS_REMOUNT	32	/* Alter flags of a mounted FS */
+#define MS_MANDLOCK	64	/* Allow mandatory locks on an FS */
+#define MS_DIRSYNC	128	/* Directory modifications are synchronous */
+#define MS_NOATIME	1024	/* Do not update access times. */
+#define MS_NODIRATIME	2048	/* Do not update directory access times */
+#define MS_BIND		4096
+#define MS_MOVE		8192
+#define MS_REC		16384
+#define MS_VERBOSE	32768	/* War is peace. Verbosity is silence.
+				   MS_VERBOSE is deprecated. */
+#define MS_SILENT	32768
+#define MS_POSIXACL	(1<<16)	/* VFS does not apply the umask */
+#define MS_UNBINDABLE	(1<<17)	/* change to unbindable */
+#define MS_PRIVATE	(1<<18)	/* change to private */
+#define MS_SLAVE	(1<<19)	/* change to slave */
+#define MS_SHARED	(1<<20)	/* change to shared */
+#define MS_RELATIME	(1<<21)	/* Update atime relative to mtime/ctime. */
+#define MS_KERNMOUNT	(1<<22) /* this is a kern_mount call */
+#define MS_I_VERSION	(1<<23) /* Update inode I_version field */
+#define MS_STRICTATIME	(1<<24) /* Always perform atime updates */
+#define MS_LAZYTIME	(1<<25) /* Update the on-disk [acm]times lazily */
+
+/* These sb flags are internal to the kernel */
+#define MS_SUBMOUNT     (1<<26)
+#define MS_NOREMOTELOCK	(1<<27)
+#define MS_NOSEC	(1<<28)
+#define MS_BORN		(1<<29)
+#define MS_ACTIVE	(1<<30)
+#define MS_NOUSER	(1<<31)
+
+/*
+ * Superblock flags that can be altered by MS_REMOUNT
+ */
+#define MS_RMT_MASK	(MS_RDONLY|MS_SYNCHRONOUS|MS_MANDLOCK|MS_I_VERSION|\
+			 MS_LAZYTIME)
+
+/*
+ * Old magic mount flag and mask
+ */
+#define MS_MGC_VAL 0xC0ED0000
+#define MS_MGC_MSK 0xffff0000
+
+#endif /* _UAPI_LINUX_MOUNT_H */

init/do_mounts.c

@@ -22,6 +22,7 @@
 #include <linux/nfs_fs.h>
 #include <linux/nfs_fs_sb.h>
 #include <linux/nfs_mount.h>
+#include <uapi/linux/mount.h>
 
 #include "do_mounts.h"
 

init/do_mounts_initrd.c

@@ -8,6 +8,7 @@
 #include <linux/sched.h>
 #include <linux/freezer.h>
 #include <linux/kmod.h>
+#include <uapi/linux/mount.h>
 
 #include "do_mounts.h"
 

security/apparmor/lsm.c

@@ -26,6 +26,7 @@
 #include <linux/netfilter_ipv4.h>
 #include <linux/netfilter_ipv6.h>
 #include <net/sock.h>
+#include <uapi/linux/mount.h>
 
 #include "include/apparmor.h"
 #include "include/apparmorfs.h"

security/apparmor/mount.c

@@ -15,6 +15,7 @@
 #include <linux/fs.h>
 #include <linux/mount.h>
 #include <linux/namei.h>
+#include <uapi/linux/mount.h>
 
 #include "include/apparmor.h"
 #include "include/audit.h"

security/selinux/hooks.c

@@ -88,6 +88,7 @@
 #include <linux/msg.h>
 #include <linux/shm.h>
 #include <linux/bpf.h>
+#include <uapi/linux/mount.h>
 
 #include "avc.h"
 #include "objsec.h"

security/tomoyo/mount.c

@@ -6,6 +6,7 @@
  */
 
 #include <linux/slab.h>
+#include <uapi/linux/mount.h>
 #include "common.h"
 
 /* String table for special mount operations. */