ZFS bug - candidate for Security Advisory?
Michal
On 10/11/2009 in "HEADS UP: Important bug fix in ZFS replay code!" post
on freebsd-fs PJD wrote:
"There was important bug in ZFS replay code. If there were setattr logs
(not related to permission change) in ZIL during unclean shutdown, one
can end up with files that have mode set to 07777.
This is very dangerous, especially if you have untrusted local users, as
this will set setuid bit on such files. Note that FreeBSD will remove
setuid bits when someone will try to modify the file, but it is still
dangerous."
It is not fixed in 8.0 as I got bitten by this bug just recently (and
other users report it on freebsd-fs). In my case it was about ten files
in /var/www, / and two users home directory.
Is it feasible to issue a SA and warn people? As far as I understand PJD
post it's got important security implications. I'm wondering how many
systems are sitting out there with bunch of 7777 files all over the
place because administrator/user is not following freebsd-fs.
Cheers, Michal
--
"There cannot be a crisis next week. My schedule is already full."
-Henry Kissinger
Robert Watson
> On 10/11/2009 in "HEADS UP: Important bug fix in ZFS replay code!" post on
> freebsd-fs PJD wrote: "There was important bug in ZFS replay code. If there
> were setattr logs (not related to permission change) in ZIL during unclean
> shutdown, one can end up with files that have mode set to 07777. This is
> very dangerous, especially if you have untrusted local users, as this will
> set setuid bit on such files. Note that FreeBSD will remove setuid bits when
> someone will try to modify the file, but it is still dangerous."
Hi Michal--
The fix didn't make 8.0 due to timing, but has been in the queue for the
forthcoming first errata notice for 8.0. After a bit of discussion over the
last few days, I believe we have decided to upgrade it to a security advisory,
which should go out between Christmas and New Years (with any luck). It is an
important fix, and making it a security advisory instead of just part of the
errata set will give it more exposure to ensure users install it. Making it
an advisory will also allow it to float free of the errata set in case that's
delayed further for some reason (there are about 4-6 fixes in the set and we
plan to do them as a single notice fairly soon). So look for something soon
in this department.
Thanks for the e-mail,
Robert N M Watson
Computer Laboratory
University of Cambridge
>
> It is not fixed in 8.0 as I got bitten by this bug just recently (and other
> users report it on freebsd-fs). In my case it was about ten files in
> /var/www, / and two users home directory.
> Is it feasible to issue a SA and warn people? As far as I understand PJD post
> it's got important security implications. I'm wondering how many systems are
> sitting out there with bunch of 7777 files all over the place because
> administrator/user is not following freebsd-fs.
>
> Cheers, Michal
> --
> "There cannot be a crisis next week. My schedule is already full." -Henry
> Kissinger
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