| Subject | [PATCH 05/27] kexec: Disable at runtime if the kernel is locked down | From | David Howells <> | Date | Thu, 19 Oct 2017 15:51:09 +0100 |
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From: Matthew Garrett <matthew.garrett@nebula.com>
kexec permits the loading and execution of arbitrary code in ring 0, which is something that lock-down is meant to prevent. It makes sense to disable kexec in this situation.
This does not affect kexec_file_load() which can check for a signature on the image to be booted.
Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com> Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Dave Young <dyoung@redhat.com> cc: kexec@lists.infradead.org ---
kernel/kexec.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/kernel/kexec.c b/kernel/kexec.c index e62ec4dc6620..7dadfed9b676 100644 --- a/kernel/kexec.c +++ b/kernel/kexec.c @@ -202,6 +202,13 @@ SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments, return -EPERM; /* + * kexec can be used to circumvent module loading restrictions, so + * prevent loading in that case + */ + if (kernel_is_locked_down("kexec of unsigned images")) + return -EPERM; + + /* * Verify we have a legal set of flags * This leaves us room for future extensions. */
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