On Tue, 2019-05-14 at 08:19 -0700, Andy Lutomirski wrote: > On Mon, May 13, 2019 at 5:47 AM Roberto Sassu <roberto.sassu@huawei.c > om> wrote: > > On 5/13/2019 11:07 AM, Rob Landley wrote: [...] > > > > The only reason why opening .xattr-list works is that IMA is > > > > not yet initialized (late_initcall vs rootfs_initcall). > > > > > > Launching init before enabling ima is bad because... you didn't > > > think of it? > > > > No, because /init can potentially compromise the integrity of the > > system. > > I think Rob is right here. If /init was statically built into the > kernel image, it has no more ability to compromise the kernel than > anything else in the kernel. What's the problem here? The specific problem is that unless you own the kernel signing key, which is really untrue for most distribution consumers because the distro owns the key, you cannot build the initrd statically into the kernel. You can take the distro signed kernel, link it with the initrd then resign the combination with your key, provided you insert your key into the MoK variables as a trusted secure boot key, but the distros have been unhappy recommending this as standard practice. If our model for security is going to be to link the kernel and the initrd statically to give signature protection over the aggregate then we need to figure out how to execute this via the distros. If we accept that the split model, where the distro owns and signs the kernel but the machine owner builds and is responsible for the initrd, then we need to explore split security models like this proposal. James
