[PATCH 08/12] kexec: Disable at runtime if trusted_kernel is true

[Matthew Garrett <matthew.garrett@nebula.com>]

kexec permits the loading and execution of arbitrary code in ring 0, which
permits the modification of the running kernel. Prevent this if
 trusted_kernel is true.

Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>
---
 kernel/kexec.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/kernel/kexec.c b/kernel/kexec.c
index 60bafbe..281ddd0 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -32,6 +32,7 @@
 #include <linux/vmalloc.h>
 #include <linux/swap.h>
 #include <linux/syscore_ops.h>
+#include <linux/security.h>
 
 #include <asm/page.h>
 #include <asm/uaccess.h>
@@ -946,6 +947,9 @@ SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments,
 	if (!capable(CAP_SYS_BOOT) || kexec_load_disabled)
 		return -EPERM;
 
+	if (get_trusted_kernel())
+		return -EPERM;
+
 	/*
 	 * Verify we have a legal set of flags
 	 * This leaves us room for future extensions.
-- 
1.8.5.3