[kernel-hardening] Re: [PATCH v7 2/2] security: tty: make TIOCSTI ioctl require CAP_SYS_ADMIN

[Nick Kralevich]

On Tue, May 30, 2017 at 11:32 AM, Stephen Smalley <sds at tycho.nsa.gov> wrote:
>> Seccomp requires the program in question to "opt-in" so to speak and
>> set
>> certain restrictions on itself. However as you state above, any
>> TIOCSTI
>> protection doesn't matter if the program correctly allocates a
>> tty/pty pair.
>> This protections seeks to protect users from programs that don't do
>> things
>> correctly. Rather than killing bugs, this feature attempts to kill an
>> entire
>> bug class that shows little sign of slowing down in the world of
>> containers and
>> sandboxes.
>
> Just FYI, you can also restrict TIOCSTI (or any other ioctl command)
> via SELinux ioctl whitelisting, and Android is using that feature to
> restrict TIOCSTI usage in Android O (at least based on the developer
> previews to date, also in AOSP master).

For reference, this is https://android-review.googlesource.com/306278
, where we moved to a whitelist for handling ioctls for ptys.

-- Nick
--
To unsubscribe from this list: send the line "unsubscribe linux-security-module" in
the body of a message to majordomo at vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html