lkml.org 
[lkml]   [2016]   [Nov]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Subject[PATCH 07/16] kexec: Disable at runtime if the kernel is locked down
From
Date
From: Matthew Garrett <matthew.garrett@nebula.com>

kexec 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 in this situation.

This does not affect kexec_file_load() which can check for a signature on the
image to be booted.

Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>
Signed-off-by: David Howells <dhowells@redhat.com>
---

kernel/kexec.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/kernel/kexec.c b/kernel/kexec.c
index 980936a90ee6..c6aa4620d1bf 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -12,6 +12,7 @@
#include <linux/mm.h>
#include <linux/file.h>
#include <linux/kexec.h>
+#include <linux/security.h>
#include <linux/mutex.h>
#include <linux/list.h>
#include <linux/syscalls.h>
@@ -194,6 +195,13 @@ SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments,
return -EPERM;

/*
+ * kexec can be used to circumvent module loading restrictions, so
+ * prevent loading in that case
+ */
+ if (kernel_is_locked_down())
+ return -EPERM;
+
+ /*
* Verify we have a legal set of flags
* This leaves us room for future extensions.
*/
\
 
 \ /
  Last update: 2016-11-16 22:49    [W:0.433 / U:1.120 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site