From: Matthew Garrett <matthew.garrett@nebula.com>
Date: Mon, 9 Sep 2013 22:49:42 +0000 (-0700)
Subject: kexec: Disable at runtime if securelevel has been set.
X-Git-Tag: v4.1.12-92~310^2~7
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=e6c869c53abea68f4582805a8acd2152b0f8b1f3;p=users%2Fjedix%2Flinux-maple.git

kexec: Disable at runtime if securelevel has been set.

Orabug: 21539498

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>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
---

diff --git a/kernel/kexec.c b/kernel/kexec.c
index 7a36fdcca5bf..ed4878ef585d 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -36,6 +36,7 @@
 #include <linux/syscore_ops.h>
 #include <linux/compiler.h>
 #include <linux/hugetlb.h>
+#include <linux/security.h>
 
 #include <asm/page.h>
 #include <asm/uaccess.h>
@@ -1246,6 +1247,9 @@ SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments,
 	if (!capable(CAP_SYS_BOOT) || kexec_load_disabled)
 		return -EPERM;
 
+	if (get_securelevel() > 0)
+		return -EPERM;
+
 	/*
 	 * Verify we have a legal set of flags
 	 * This leaves us room for future extensions.