Module Name: src
Committed By: hannken
Date: Fri Dec 9 10:33:18 UTC 2022
Modified Files:
src/sys/kern: vfs_mount.c
src/sys/miscfs/genfs: layer_vfsops.c
Log Message:
Harden layered file systems usage of field "mnt_lower" against
forced unmounts of the lower layer.
- Dont allow "dead_rootmount" as lower layer.
- Take file system busy before a vfs operation walks down the stack.
Reported-by: [email protected]
Reported-by: [email protected]
To generate a diff of this commit:
cvs rdiff -u -r1.100 -r1.101 src/sys/kern/vfs_mount.c
cvs rdiff -u -r1.55 -r1.56 src/sys/miscfs/genfs/layer_vfsops.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/kern/vfs_mount.c
diff -u src/sys/kern/vfs_mount.c:1.100 src/sys/kern/vfs_mount.c:1.101
--- src/sys/kern/vfs_mount.c:1.100 Thu Nov 10 10:55:00 2022
+++ src/sys/kern/vfs_mount.c Fri Dec 9 10:33:18 2022
@@ -1,4 +1,4 @@
-/* $NetBSD: vfs_mount.c,v 1.100 2022/11/10 10:55:00 hannken Exp $ */
+/* $NetBSD: vfs_mount.c,v 1.101 2022/12/09 10:33:18 hannken Exp $ */
/*-
* Copyright (c) 1997-2020 The NetBSD Foundation, Inc.
@@ -67,7 +67,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_mount.c,v 1.100 2022/11/10 10:55:00 hannken Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_mount.c,v 1.101 2022/12/09 10:33:18 hannken Exp $");
#include <sys/param.h>
#include <sys/kernel.h>
@@ -91,6 +91,7 @@ __KERNEL_RCSID(0, "$NetBSD: vfs_mount.c,
#include <sys/vfs_syscalls.h>
#include <sys/vnode_impl.h>
+#include <miscfs/deadfs/deadfs.h>
#include <miscfs/genfs/genfs.h>
#include <miscfs/specfs/specdev.h>
@@ -418,6 +419,8 @@ vfs_set_lowermount(struct mount *mp, str
#endif
if (lowermp) {
+ if (lowermp == dead_rootmount)
+ return ENOENT;
error = vfs_busy(lowermp);
if (error)
return error;
Index: src/sys/miscfs/genfs/layer_vfsops.c
diff -u src/sys/miscfs/genfs/layer_vfsops.c:1.55 src/sys/miscfs/genfs/layer_vfsops.c:1.56
--- src/sys/miscfs/genfs/layer_vfsops.c:1.55 Mon Jul 18 04:30:30 2022
+++ src/sys/miscfs/genfs/layer_vfsops.c Fri Dec 9 10:33:18 2022
@@ -1,4 +1,4 @@
-/* $NetBSD: layer_vfsops.c,v 1.55 2022/07/18 04:30:30 thorpej Exp $ */
+/* $NetBSD: layer_vfsops.c,v 1.56 2022/12/09 10:33:18 hannken Exp $ */
/*
* Copyright (c) 1999 National Aeronautics & Space Administration
@@ -74,7 +74,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: layer_vfsops.c,v 1.55 2022/07/18 04:30:30 thorpej Exp $");
+__KERNEL_RCSID(0, "$NetBSD: layer_vfsops.c,v 1.56 2022/12/09 10:33:18 hannken Exp $");
#include <sys/param.h>
#include <sys/sysctl.h>
@@ -146,8 +146,15 @@ layerfs_root(struct mount *mp, int lktyp
int
layerfs_quotactl(struct mount *mp, struct quotactl_args *args)
{
+ int error;
+
+ error = vfs_busy(mp);
+ if (error == 0) {
+ error = VFS_QUOTACTL(mp->mnt_lower, args);
+ vfs_unbusy(mp);
+ }
- return VFS_QUOTACTL(mp->mnt_lower, args);
+ return error;
}
int
@@ -157,7 +164,11 @@ layerfs_statvfs(struct mount *mp, struct
int error;
sbuf = kmem_zalloc(sizeof(*sbuf), KM_SLEEP);
- error = VFS_STATVFS(mp->mnt_lower, sbuf);
+ error = vfs_busy(mp);
+ if (error == 0) {
+ error = VFS_STATVFS(mp->mnt_lower, sbuf);
+ vfs_unbusy(mp);
+ }
if (error) {
goto done;
}
@@ -234,7 +245,11 @@ layerfs_vget(struct mount *mp, ino_t ino
struct vnode *vp;
int error;
- error = VFS_VGET(mp->mnt_lower, ino, lktype, &vp);
+ error = vfs_busy(mp);
+ if (error == 0) {
+ error = VFS_VGET(mp->mnt_lower, ino, lktype, &vp);
+ vfs_unbusy(mp);
+ }
if (error) {
*vpp = NULL;
return error;
@@ -262,7 +277,11 @@ layerfs_fhtovp(struct mount *mp, struct
struct vnode *vp;
int error;
- error = VFS_FHTOVP(mp->mnt_lower, fidp, lktype, &vp);
+ error = vfs_busy(mp);
+ if (error == 0) {
+ error = VFS_FHTOVP(mp->mnt_lower, fidp, lktype, &vp);
+ vfs_unbusy(mp);
+ }
if (error) {
*vpp = NULL;
return error;
