Re: VFS, NFS security bug? Should CAP_MKNOD and CAP_LINUX_IMMUTABLE be added to CAP_FS_MASK?

[Michael Kerrisk]

On Sat, Mar 14, 2009 at 6:58 AM, J. Bruce Fields <bfields@xxxxxxxxxxxx> wrote:
> On Fri, Mar 13, 2009 at 09:21:23AM +1300, Michael Kerrisk wrote:
>> On Fri, Mar 13, 2009 at 5:10 AM, Serge E. Hallyn <serue@xxxxxxxxxx> wrote:
>> > Quoting J. Bruce Fields (bfields@xxxxxxxxxxxx):
>> >> On Wed, Mar 11, 2009 at 03:53:34PM +0300, Igor Zhbanov wrote:
>> >> > Hello!
>> >> >
>> >> > It seems that CAP_MKNOD and CAP_LINUX_IMMUTABLE were forgotten to be
>> >> > added to CAP_FS_MASK_B0 in linux-2.6.x and to CAP_FS_MASK in
>> >> > linux-2.4.x. Both capabilities affects file system and can be
>> >> > considered file system capabilities.
>> >>
>> >> Sounds right to me--I'd expect rootsquash to guarantee that new device
>> >> nodes can't be created from the network.  Cc'ing random people from the
>> >> git log for include/linux/capability.h in hopes they can help.
>> >
>> > Yeah it seems reasonable.  If it is, then does that mean that we
>> > also need CAP_SYS_ADMIN (to write selinux labels) and CAP_SETFCAP
>> > (to set file capabilities) as well?
>>
>> If a change is made to CAP_FS_MASK, please do remember to CC
>> mtk.manpages@xxxxxxxxx, and linux-api@.
>
> OK, that's because the exact set of capabilities that is dropped on
> setfsuid is documented in capabilities(7)?  (Anywhere else?)

Not that I know of.


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
git://git.kernel.org/pub/scm/docs/man-pages/man-pages.git
man-pages online: http://www.kernel.org/doc/man-pages/online_pages.html
Found a bug? http://www.kernel.org/doc/man-pages/reporting_bugs.html
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/