util linux patches

Signed-off-by: basebuilder_pel7ppc64bebuilder0 <basebuilder@powerel.org>
6 years ago · 9be389064d
1 changed files with 159 additions and 0 deletions
--- a/SOURCES/0084-libmount-add-support-for-bind-ro.patch
+++ b/SOURCES/0084-libmount-add-support-for-bind-ro.patch
@ -0,0 +1,159 @@
				@@ -0,0 +1,159 @@
+From 2218dc0d130bb72809e2d8b26a36402bf6293727 Mon Sep 17 00:00:00 2001
+From: Karel Zak <kzak@redhat.com>
+Date: Mon, 17 Aug 2015 11:54:26 +0200
+Subject: [PATCH 84/86] libmount: add support for "bind,ro"
+
+Now it's necessary to use two mount(8) calls to create a read-only
+mount:
+
+  mount /foo /bar -o bind
+  mount /bar -o remount,ro,bind
+
+This patch allows to specify "bind,ro" and the remount is done
+automatically by libmount by additional mount(2) syscall. It's not
+atomic of course.
+
+Addresses: http://bugzilla.redhat.com/show_bug.cgi?id=1281839
+Signed-off-by: Karel Zak <kzak@redhat.com>
+---
+ libmount/src/context_mount.c | 46 ++++++++++++++++++++++++++++++++++++++++++++
+ sys-utils/mount.8            | 37 ++++++++++++++++++-----------------
+ 2 files changed, 65 insertions(+), 18 deletions(-)
+
+diff --git a/libmount/src/context_mount.c b/libmount/src/context_mount.c
+index d6691eb..4df2646 100644
+--- a/libmount/src/context_mount.c
+++ b/libmount/src/context_mount.c
+@@ -62,6 +62,10 @@ static int mnt_context_append_additional_mount(struct libmnt_context *cxt,
+	return 0;
+ }
+
+/*
+ * add additional mount(2) syscall requests when necessary to set propagation flags
+ * after regular mount(2).
+ */
+ static int init_propagation(struct libmnt_context *cxt)
+ {
+	char *name;
+@@ -102,6 +106,41 @@ static int init_propagation(struct libmnt_context *cxt)
+ }
+
+ /*
+ * add additional mount(2) syscall request to implement "ro,bind", the first regular
+ * mount(2) is the "bind" operation, the second is "remount,ro,bind" call.
+ *
+ * Note that we don't remove "ro" from the first syscall (kernel silently
+ * ignores this flags for bind operation) -- maybe one day kernel will support
+ * read-only binds in one step and then all will be done by the firts mount(2) and the
+ * second remount will be noop...
+ */
+static int init_robind(struct libmnt_context *cxt)
+{
+	struct libmnt_addmount *ad;
+	int rc;
+
+	assert(cxt);
+	assert(cxt->mountflags & MS_BIND);
+	assert(cxt->mountflags & MS_RDONLY);
+	assert(!(cxt->mountflags & MS_REMOUNT));
+
+	DBG(CXT, mnt_debug_h(cxt, "mount: initialize additional ro,bind mount"));
+
+	ad = mnt_new_addmount();
+	if (!ad)
+		return -ENOMEM;
+
+	ad->mountflags = MS_REMOUNT | MS_BIND | MS_RDONLY;
+	if (cxt->mountflags & MS_REC)
+		ad->mountflags |= MS_REC;
+	rc = mnt_context_append_additional_mount(cxt, ad);
+	if (rc)
+		return rc;
+
+	return 0;
+}
+
+/*
+  * this has to be called after mnt_context_evaluate_permissions()
+  */
+ static int fix_optstr(struct libmnt_context *cxt)
+@@ -174,6 +213,13 @@ static int fix_optstr(struct libmnt_context *cxt)
+		if (rc)
+			return rc;
+	}
+	if ((cxt->mountflags & MS_BIND)
+	    && (cxt->mountflags & MS_RDONLY)
+	    && !(cxt->mountflags & MS_REMOUNT)) {
+		rc = init_robind(cxt);
+		if (rc)
+			return rc;
+	}
+
+	next = fs->fs_optstr;
+
+diff --git a/sys-utils/mount.8 b/sys-utils/mount.8
+index 3648870..49cb281 100644
+--- a/sys-utils/mount.8
+++ b/sys-utils/mount.8
+@@ -388,25 +388,25 @@ or shortoption
+ .\" available since Linux 2.4.11.
+
+ Note that the filesystem mount options will remain the same as those
+-on the original mount point, and cannot be changed by passing the -o
+-option along with --bind/--rbind. The mount options can be
+-changed by a separate remount command, for example:
+on the original mount point.
+
+.BR mount(8)
+since v2.27 (backported to RHEL7.3) allow to change the options by passing the
+.B \-o
+option along with
+.BR \-\-bind
+for example:
+
+ .RS
+ .br
+-.B mount --bind
+-.I olddir newdir
+-.br
+-.B mount -o remount,ro
+-.I newdir
+.B mount \-\-bind,ro foo foo
+ .RE
+
+-Note that behavior of the remount operation depends on the /etc/mtab file. The
+-first command stores the 'bind' flag to the /etc/mtab file and the second
+-command reads the flag from the file.  If you have a system without the
+-/etc/mtab file or if you explicitly define source and target for the remount
+-command (then mount(8) does not read /etc/mtab), then you have to use bind flag
+-(or option) for the remount command too. For example:
+This feature is not supported by Linux kernel and it is implemented in userspace
+by additional remount mount(2) syscall. This solution is not atomic.
+
+The alternative (classic) way to create a read-only bind mount is to use remount
+operation, for example:
+
+ .RS
+ .br
+@@ -417,14 +417,15 @@ command (then mount(8) does not read /etc/mtab), then you have to use bind flag
+ .I olddir newdir
+ .RE
+
+-Note that
+-.I remount,ro,bind
+-will create a read-only mountpoint (VFS entry), but the original filesystem suberblock
+-will be still writable, it means that the
+Note that read-only bind will create a read-only mountpoint (VFS entry), but the
+original filesystem superblock will still be writable, meaning that the
+ .I olddir
+ will be writable, but the
+ .I newdir
+ will be read-only.
+
+It's impossible to change mount options recursively
+(for example with \fB -o rbind,ro\fR).
+ .RE
+
+ .B The move operation.
+--
+2.7.4