From ddb34bde59071d361b72338d7a58b36c3dee4e17 Mon Sep 17 00:00:00 2001 From: Matthew Garrett Date: Mon, 18 Feb 2019 12:44:58 +0000 Subject: [PATCH] kexec_load: Disable at runtime if the kernel is locked down The kexec_load() syscall 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_load() in this situation. This does not affect kexec_file_load() syscall which can check for a signature on the image to be booted. Signed-off-by: Matthew Garrett Signed-off-by: David Howells Acked-by: Dave Young Reviewed-by: "Lee, Chun-Yi" Reviewed-by: James Morris cc: kexec@lists.infradead.org Gbp-Pq: Topic features/all/lockdown Gbp-Pq: Name 0006-kexec_load-Disable-at-runtime-if-the-kernel-is-locke.patch --- kernel/kexec.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/kernel/kexec.c b/kernel/kexec.c index 1b018f1a6e0..fc87f152c22 100644 --- a/kernel/kexec.c +++ b/kernel/kexec.c @@ -205,6 +205,13 @@ static inline int kexec_load_check(unsigned long nr_segments, if (result < 0) return result; + /* + * 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. -- 2.30.2