[PATCH 08/12] kexec: Disable at runtime if securelevel has been set.

Matthew Garrett
2013-09-09T15:52:26Z

kexec permits the loading and execution of arbitrary code in ring 0, which
permits the modification of the running kernel. Prevent this if securelevel
has been set.

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 59f7b55..98db2a1 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>
@@ -942,6 +943,9 @@ SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments,
if (!capable(CAP_SYS_BOOT))
return -EPERM;

+ if (get_securelevel() > 0)
+ return -EPERM;
+
/*
* Verify we have a legal set of flags
* This leaves us room for future extensions.
--
1.8.3.1