Quoting Eric Paris (eparis@xxxxxxxxxx): > On Thu, 2009-08-13 at 09:03 -0500, Serge E. Hallyn wrote: > > Quoting Eric Paris (eparis@xxxxxxxxxx): > > > Calling request_module() will trigger a userspace upcall which will load a > > > new module into the kernel. This can be a dangerous event if the process > > > able to trigger request_module() is able to control either the modprobe > > > binary or the module binary. This patch adds a new security hook to > > > request_module() which can be used by an LSM to control a processes ability > > > to call request_module(). > > > > Is there a specific case in which you'd want to deny this ability > > from a real task? > > qemu and any network facing daemon are all programs I don't want to be > able to even ask the kernel to load a module. Clearly you are right, ... What if the network facing daemon might want to use a kernel crypto module? What if qemu needs the tun module loaded? > that the best protection is done by controlling access to modprobe and > the modules on disk (which we are working to fix vs what happened in the > xen fb exploit I showed earlier) but stopping it from the other > direction is, I feel, a useful defense in depth. > > If they can't get modprobe called, they can't take over the system > directly, even if they did change a module or change modprobe. I agree > it's not strong security as if they can change modprobe or modules they > might be able to just wait until something else calls modprobe (next > reboot maybe?) to take over the system. But I'd find it very > interesting to know that a high threat target tried to do anything which > attempted to load a module.... > > -Eric > > -- > To unsubscribe from this list: send the line "unsubscribe linux-security-module" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- This message was distributed to subscribers of the selinux mailing list. If you no longer wish to subscribe, send mail to majordomo@xxxxxxxxxxxxx with the words "unsubscribe selinux" without quotes as the message.
