On Tue, 2012-09-04 at 11:55 -0400, Matthew Garrett wrote: > kexec could be used as a vector for a malicious user to use a signed kernel > to circumvent the secure boot trust model. In the long run we'll want to > support signed kexec payloads, but for the moment we should just disable > loading entirely in that situation. > > Signed-off-by: Matthew Garrett <[email protected]> > --- > kernel/kexec.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/kexec.c b/kernel/kexec.c > index 0668d58..48852ec 100644 > --- a/kernel/kexec.c > +++ b/kernel/kexec.c > @@ -944,7 +944,7 @@ SYSCALL_DEFINE4(kexec_load, unsigned long, entry, > unsigned long, nr_segments, > int result; > > /* We only trust the superuser with rebooting the system. */ > - if (!capable(CAP_SYS_BOOT)) > + if (!capable(CAP_SYS_BOOT) || !capable(CAP_SECURE_FIRMWARE)) > return -EPERM; > > /*
Normally capabilities provide additional permissions. So if you don't have the capability, an errno is returned. CAP_SYS_BOOT is a good example. With CAP_SECURE_FIRMWARE, it reads backwards - if not CAP_SECURE_FIRMWARE, return error. I think you want to invert the name to CAP_NOT_SECURE_FIRMWARE, CAP_NOT_SECURE_BOOT or perhaps CAP_UNSECURED_BOOT. Mimi -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
