linux-kernel - [PATCH 3/3] dm: do not forward ioctls from logical volumes to the underlying device

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Message-Id: <1324576939-23619-4-git-send-email-pbonzini@redhat.com>
Date:	Thu, 22 Dec 2011 19:02:19 +0100
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	linux-kernel@...r.kernel.org, security@...nel.org,
	pmatouse@...hat.com, agk@...hat.com, jbottomley@...allels.com,
	mchristi@...hat.com, msnitzer@...hat.com,
	torvalds@...ux-foundation.org
Subject: [PATCH 3/3] dm: do not forward ioctls from logical volumes to the underlying device

A logical volume can map to just part of underlying physical volume.
In this case, it must be treated like a partition.

Based on a patch from Alasdair G Kergon.

Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 drivers/md/dm-flakey.c |   11 ++++++++++-
 drivers/md/dm-linear.c |   12 +++++++++++-
 drivers/md/dm-mpath.c  |    6 ++++++
 3 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/drivers/md/dm-flakey.c b/drivers/md/dm-flakey.c
index f84c080..9fb18c1 100644
--- a/drivers/md/dm-flakey.c
+++ b/drivers/md/dm-flakey.c
@@ -368,8 +368,17 @@ static int flakey_status(struct dm_target *ti, status_type_t type,
 static int flakey_ioctl(struct dm_target *ti, unsigned int cmd, unsigned long arg)
 {
 	struct flakey_c *fc = ti->private;
+	struct dm_dev *dev = fc->dev;
+	int r = 0;
 
-	return __blkdev_driver_ioctl(fc->dev->bdev, fc->dev->mode, cmd, arg);
+	/*
+	 * Only pass ioctls through if the device sizes match exactly.
+	 */
+	if (fc->start ||
+	    ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT)
+		r = scsi_verify_blk_ioctl(NULL, cmd);
+
+	return r ? : __blkdev_driver_ioctl(dev->bdev, dev->mode, cmd, arg);
 }
 
 static int flakey_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
index 3921e3b..9728839 100644
--- a/drivers/md/dm-linear.c
+++ b/drivers/md/dm-linear.c
@@ -116,7 +116,17 @@ static int linear_ioctl(struct dm_target *ti, unsigned int cmd,
 			unsigned long arg)
 {
 	struct linear_c *lc = (struct linear_c *) ti->private;
-	return __blkdev_driver_ioctl(lc->dev->bdev, lc->dev->mode, cmd, arg);
+	struct dm_dev *dev = lc->dev;
+	int r = 0;
+
+	/*
+	 * Only pass ioctls through if the device sizes match exactly.
+	 */
+	if (lc->start ||
+	    ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT)
+		r = scsi_verify_blk_ioctl(NULL, cmd);
+
+	return r ? : __blkdev_driver_ioctl(dev->bdev, dev->mode, cmd, arg);
 }
 
 static int linear_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index 8ab377f..2bfbdb9 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -1521,6 +1521,12 @@ static int multipath_ioctl(struct dm_target *ti, unsigned int cmd,
 
 	spin_unlock_irqrestore(&m->lock, flags);
 
+	/*
+	 * Only pass ioctls through if the device sizes match exactly.
+	 */
+	if (!r && ti->len != i_size_read(bdev->bd_inode) >> SECTOR_SHIFT)
+		r = scsi_verify_blk_ioctl(NULL, cmd);
+
 	return r ? : __blkdev_driver_ioctl(bdev, mode, cmd, arg);
 }
 
-- 
1.7.7.1
--
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