On Thu, Sep 20, 2012 at 3:14 PM, Kees Cook <keesc...@chromium.org> wrote: > As part of the effort to create a stronger boundary between root and > kernel, Chrome OS wants to be able to enforce that kernel modules are > being loaded only from our read-only crypto-hash verified (dm_verity) > root filesystem. Since the init_module syscall hands the kernel a module > as a memory blob, no reasoning about the origin of the blob can be made. > > Earlier proposals for appending signatures to kernel modules would not be > useful in Chrome OS, since it would involve adding an additional set of > keys to our kernel and builds for no good reason: we already trust the > contents of our root filesystem. We don't need to verify those kernel > modules a second time. Having to do signature checking on module loading > would slow us down and be redundant. All we need to know is where a > module is coming from so we can say yes/no to loading it. > > If a file descriptor is used as the source of a kernel module, many more > things can be reasoned about. In Chrome OS's case, we could enforce that > the module lives on the filesystem we expect it to live on. In the case > of IMA (or other LSMs), it would be possible, for example, to examine > extended attributes that may contain signatures over the contents of > the module. > > This introduces a new syscall (on x86), similar to init_module, that has > only two arguments. The first argument is used as a file descriptor to > the module and the second argument is a pointer to the NULL terminated > string of module arguments.
Hi Rusty, Is this likely to land in the 3.7 change window? I'd really like to get the syscall number assigned so I can start sending patches to glibc, kmod, etc. My tree is here, FWIW: http://git.kernel.org/?p=linux/kernel/git/kees/linux.git;a=shortlog;h=refs/heads/module-fd-syscall Thanks! -Kees -- Kees Cook Chrome OS Security -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/