linux-kernel - Q. block: check bdev_read_only() from blkdev

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-next>] [day] [month] [year] [list]

Message-ID: <23846.1295615979@jrobl>
Date:	Fri, 21 Jan 2011 22:19:39 +0900
From:	"J. R. Okajima" <hooanon05@...oo.co.jp>
To:	Tejun Heo <tj@...nel.org>
cc:	David Brownell <dbrownell@...rs.sourceforge.net>,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Q. block: check bdev_read_only() from blkdev_get()


By the commit 75f1dc0
	2010-11-13 block: check bdev_read_only() from blkdev_get()
bdev_read_only() call is added into blkdev_get().

This check makes the loopback block device unable to be mounted as
writable once it is set to readonly, even if the corresponding is
detached and the device becomes free.
We may need to re-initialize the readonly/writable status flag somewhere?

# simple tests with loopback

# mount as writable, succeed
+ sudo mount -o loop ./ext2.img /mnt
+ sudo umount /mnt

# mount as readonly, succeed
+ sudo mount -o ro,loop ./ext2.img /mnt
+ sudo umount /mnt

# mount as writable again, fail
+ sudo mount -o loop ./ext2.img /mnt
/dev/loop0: Permission denied

Now /dev/loop0 is fixed as readonly.


J. R. Okajima
--
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/