linux-kernel - [ 162/171] rbd: do not allow remove of mounted-on image

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20130115224325.014069923@linuxfoundation.org>
Date:	Tue, 15 Jan 2013 14:45:27 -0800
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	alan@...rguk.ukuu.org.uk, Alex Elder <elder@...tank.com>,
	Sage Weil <sage@...tank.com>
Subject: [ 162/171] rbd: do not allow remove of mounted-on image

3.4-stable review patch.  If anyone has any objections, please let me know.

------------------


From: Alex Elder <elder@...tank.com>

There is no check in rbd_remove() to see if anybody holds open the
image being removed.  That's not cool.

Add a simple open count that goes up and down with opens and closes
(releases) of the device, and don't allow an rbd image to be removed
if the count is non-zero.

Protect the updates of the open count value with ctl_mutex to ensure
the underlying rbd device doesn't get removed while concurrently
being opened.

Signed-off-by: Alex Elder <elder@...tank.com>
Reviewed-by: Sage Weil <sage@...tank.com>
(based on commit 42382b709bd1d143b9f0fa93e0a3a1f2f4210707)
---
 drivers/block/rbd.c |   13 +++++++++++++
 1 file changed, 13 insertions(+)

--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -189,6 +189,7 @@ struct rbd_device {
 
 	/* sysfs related */
 	struct device		dev;
+	unsigned long		open_count;
 };
 
 static DEFINE_MUTEX(ctl_mutex);	  /* Serialize open/close/setup/teardown */
@@ -249,8 +250,11 @@ static int rbd_open(struct block_device
 	if ((mode & FMODE_WRITE) && rbd_dev->read_only)
 		return -EROFS;
 
+	mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);
 	rbd_get_dev(rbd_dev);
 	set_device_ro(bdev, rbd_dev->read_only);
+	rbd_dev->open_count++;
+	mutex_unlock(&ctl_mutex);
 
 	return 0;
 }
@@ -259,7 +263,11 @@ static int rbd_release(struct gendisk *d
 {
 	struct rbd_device *rbd_dev = disk->private_data;
 
+	mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);
+	BUG_ON(!rbd_dev->open_count);
+	rbd_dev->open_count--;
 	rbd_put_dev(rbd_dev);
+	mutex_unlock(&ctl_mutex);
 
 	return 0;
 }
@@ -2448,6 +2456,11 @@ static ssize_t rbd_remove(struct bus_typ
 		goto done;
 	}
 
+	if (rbd_dev->open_count) {
+		ret = -EBUSY;
+		goto done;
+	}
+
 	__rbd_remove_all_snaps(rbd_dev);
 	rbd_bus_del_dev(rbd_dev);
 


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/