svn commit: r327655 - in stable/11: share/man/man4 sys/conf sys/dev/md
Ian Lepore
ian at FreeBSD.org
Sat Jan 6 23:20:36 UTC 2018
Author: ian
Date: Sat Jan 6 23:20:35 2018
New Revision: 327655
URL: https://svnweb.freebsd.org/changeset/base/327655
Log:
MFC r327032:
Add a new kernel config option, MD_ROOT_READONLY, which forces on the
MD_READONLY flag for the md device automatically instantiated during
kernel init for an mdroot filesystem.
Note that there is specifically and by design no tunable or sysctl
control over this feature. Without this option, you already have control
over whether the mdroot fs is writeable using vfs.root.mountfrom.options
from loader(8), the root_rw_mount rcvar, and by using "mount -u[rw] /"
or equivelent on the fly. This option is being added to provide a way
to make the mdroot fs truly immutable before userland code begins running.
Differential Revision: https://reviews.freebsd.org/D13411
Modified:
stable/11/share/man/man4/md.4
stable/11/sys/conf/NOTES
stable/11/sys/conf/options
stable/11/sys/dev/md/md.c
Directory Properties:
stable/11/ (props changed)
Modified: stable/11/share/man/man4/md.4
==============================================================================
--- stable/11/share/man/man4/md.4 Sat Jan 6 23:12:32 2018 (r327654)
+++ stable/11/share/man/man4/md.4 Sat Jan 6 23:20:35 2018 (r327655)
@@ -7,7 +7,7 @@
.\"
.\" $FreeBSD$
.\"
-.Dd November 5, 2017
+.Dd December 7, 2017
.Dt MD 4
.Os
.Sh NAME
@@ -79,7 +79,8 @@ To create a kernel with a ramdisk or MD file system, y
needs the following options:
.Bd -literal -offset indent
options MD_ROOT # MD is a potential root device
-options MD_ROOT_SIZE=8192 # 8MB ram disk
+options MD_ROOT_READONLY # disallow mounting root writeable
+options MD_ROOT_SIZE=8192 # 8MB ram disk
makeoptions MFS_IMAGE=/h/foo/ARM-MD
options ROOTDEVNAME=\\"ufs:md0\\"
.Ed
Modified: stable/11/sys/conf/NOTES
==============================================================================
--- stable/11/sys/conf/NOTES Sat Jan 6 23:12:32 2018 (r327654)
+++ stable/11/sys/conf/NOTES Sat Jan 6 23:20:35 2018 (r327655)
@@ -1102,6 +1102,9 @@ options MD_ROOT_SIZE=10
# images of type mfs_root or md_root.
options MD_ROOT
+# Write-protect the md root device so that it may not be mounted writeable.
+options MD_ROOT_READONLY
+
# Disk quotas are supported when this option is enabled.
options QUOTA #enable disk quotas
Modified: stable/11/sys/conf/options
==============================================================================
--- stable/11/sys/conf/options Sat Jan 6 23:12:32 2018 (r327654)
+++ stable/11/sys/conf/options Sat Jan 6 23:20:35 2018 (r327655)
@@ -165,6 +165,7 @@ MAC_STUB opt_dontuse.h
MAC_TEST opt_dontuse.h
MD_ROOT opt_md.h
MD_ROOT_FSTYPE opt_md.h
+MD_ROOT_READONLY opt_md.h
MD_ROOT_SIZE opt_md.h
MFI_DEBUG opt_mfi.h
MFI_DECODE_LOG opt_mfi.h
Modified: stable/11/sys/dev/md/md.c
==============================================================================
--- stable/11/sys/dev/md/md.c Sat Jan 6 23:12:32 2018 (r327654)
+++ stable/11/sys/dev/md/md.c Sat Jan 6 23:20:35 2018 (r327655)
@@ -1755,9 +1755,15 @@ md_preloaded(u_char *image, size_t length, const char
sc->pl_ptr = image;
sc->pl_len = length;
sc->start = mdstart_preload;
-#if defined(MD_ROOT) && !defined(ROOTDEVNAME)
- if (sc->unit == 0)
+#ifdef MD_ROOT
+ if (sc->unit == 0) {
+#ifndef ROOTDEVNAME
rootdevnames[0] = MD_ROOT_FSTYPE ":/dev/md0";
+#endif
+#ifdef MD_ROOT_READONLY
+ sc->flags |= MD_READONLY;
+#endif
+ }
#endif
mdinit(sc);
if (name != NULL) {
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