linux-kernel - [PATCH 3/4] Do not allow umounting of frozen filesystems

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]

Date:	Thu, 27 Aug 2009 23:06:07 +0900
From:	Fernando Luis Vázquez Cao 
	<fernando@....ntt.co.jp>
To:	Christoph Hellwig <hch@....de>
CC:	t-sato@...jp.nec.com, m-hamaguchi@...jp.nec.com,
	Al Viro <viro@...iv.linux.org.uk>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Eric Sandeen <sandeen@...hat.com>
Subject: [PATCH 3/4] Do not allow umounting of frozen filesystems

Instead of making umount users wait until the filesystem is
unfreezed return EBUSY, which is very convenient in HA
configurations.

This could have been implemented at a lower level but it would
require considerable plumbing in functions such as release_mounts
which do not return errors.

Signed-off-by: Fernando Luis Vazquez Cao <fernando@....ntt.co.jp>
---

diff -urNp linux-2.6.31-rc7-orig/fs/namespace.c linux-2.6.31-rc7/fs/namespace.c
--- linux-2.6.31-rc7-orig/fs/namespace.c	2009-08-27 19:34:35.000000000 +0900
+++ linux-2.6.31-rc7/fs/namespace.c	2009-08-27 22:45:14.000000000 +0900
@@ -1086,6 +1086,14 @@ static int do_umount(struct vfsmount *mn
  		return retval;
  	}

+	if (sb->s_bdev != NULL) {
+		mutex_lock(&sb->s_bdev->bd_fsfreeze_mutex);
+		if (sb->s_frozen != SB_UNFROZEN) {
+			mutex_unlock(&sb->s_bdev->bd_fsfreeze_mutex);
+			return -EBUSY;
+		}
+	}
+
  	down_write(&namespace_sem);
  	spin_lock(&vfsmount_lock);
  	event++;
@@ -1104,6 +1112,10 @@ static int do_umount(struct vfsmount *mn
  		security_sb_umount_busy(mnt);
  	up_write(&namespace_sem);
  	release_mounts(&umount_list);
+
+	if (sb->s_bdev != NULL)
+		mutex_unlock(&sb->s_bdev->bd_fsfreeze_mutex);
+
  	return retval;
  }

--
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/