diff options
| author | Eric W. Biederman <ebiederm@xmission.com> | 2014-10-04 14:44:03 -0700 |
|---|---|---|
| committer | Jiri Slaby <jslaby@suse.cz> | 2015-01-07 17:55:09 +0100 |
| commit | e3783a9e6f416ee140ac4ca7184f269c537593f1 (patch) | |
| tree | e67cea4f584c05a550c2c4b3c561376546ec1af7 | |
| parent | c7c5d7123d0b13ed4f4631061080f7b1d6dcfd98 (diff) | |
umount: Disallow unprivileged mount force
commit b2f5d4dc38e034eecb7987e513255265ff9aa1cf 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: Jiri Slaby <jslaby@suse.cz>
| -rw-r--r-- | fs/namespace.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index 6b42c6d1590e..7c3c0f6d2744 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -1347,6 +1347,9 @@ SYSCALL_DEFINE2(umount, char __user *, name, int, flags) goto dput_and_out; if (mnt->mnt.mnt_flags & MNT_LOCKED) goto dput_and_out; + retval = -EPERM; + if (flags & MNT_FORCE && !capable(CAP_SYS_ADMIN)) + goto dput_and_out; retval = do_umount(mnt, flags); dput_and_out: |