umount: Disallow unprivileged mount force

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commit b2f5d4dc38 upstream.

Forced unmount affects not just the mount namespace but the underlying
superblock as well.  Restrict forced unmount to the global root user
for now.  Otherwise it becomes possible a user in a less privileged
mount namespace to force the shutdown of a superblock of a filesystem
in a more privileged mount namespace, allowing a DOS attack on root.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

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Eric W. Biederman 2014-10-04 14:44:03 -07:00 • committed by Luis Henriques

parent 0f8730f4a2

commit bb825fea6a

1 changed files with 3 additions and 0 deletions

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fs/namespace.c

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