From 7d31f4602f8d366072471ca138e4ea7b8edf9be0 Mon Sep 17 00:00:00 2001 From: Matthew Garrett Date: Mon, 19 Aug 2019 17:17:42 -0700 Subject: 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: David Howells Signed-off-by: Matthew Garrett Acked-by: Dave Young Reviewed-by: Kees Cook cc: kexec@lists.infradead.org Signed-off-by: James Morris --- kernel/kexec.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'kernel/kexec.c') diff --git a/kernel/kexec.c b/kernel/kexec.c index 1b018f1a6e0d..bc933c0db9bf 100644 --- a/kernel/kexec.c +++ b/kernel/kexec.c @@ -205,6 +205,14 @@ 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 + */ + result = security_locked_down(LOCKDOWN_KEXEC); + if (result) + return result; + /* * Verify we have a legal set of flags * This leaves us room for future extensions. -- cgit v1.2.3-70-g09d2