[PATCH 05/27] kexec: Disable at runtime if the kernel is locked down
From: jlee@suse.com (joeyli)
Date: 2017-10-20 06:38:51
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On Thu, Oct 19, 2017 at 03:51:09PM +0100, David Howells wrote:
From: Matthew Garrett <redacted> 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 <redacted> Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Dave Young <redacted>
I have reviewed and tested this patch. Please feel free to add: Reviewed-by: "Lee, Chun-Yi" <jlee@suse.com> Thanks a lot! Joey Lee
quoted hunk ↗ jump to hunk
cc: kexec at 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. */ --To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo at vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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