[v6,2/8] kexec: add call to LSM hook in original kexec_load syscall

Commit Message

Mimi Zohar July 13, 2018, 6:05 p.m. UTC

In order for LSMs and IMA-appraisal to differentiate between kexec_load
and kexec_file_load syscalls, both the original and new syscalls must
call an LSM hook.  This patch adds a call to security_kernel_load_data()
in the original kexec_load syscall.

Signed-off-by: Mimi Zohar <[e-mail]>
Cc: Eric Biederman <[e-mail]>
Cc: Kees Cook <[e-mail]>
Acked-by: Serge Hallyn <[e-mail]>
---
 kernel/kexec.c | 8 ++++++++
 1 file changed, 8 insertions(+)

Comments

Kees Cook July 15, 2018, 2:14 a.m. UTC | #1

On Fri, Jul 13, 2018 at 11:05 AM, Mimi Zohar <[e-mail]> wrote:
> In order for LSMs and IMA-appraisal to differentiate between kexec_load
> and kexec_file_load syscalls, both the original and new syscalls must
> call an LSM hook.  This patch adds a call to security_kernel_load_data()
> in the original kexec_load syscall.
>
> Signed-off-by: Mimi Zohar <[e-mail]>
> Cc: Eric Biederman <[e-mail]>
> Cc: Kees Cook <[e-mail]>
> Acked-by: Serge Hallyn <[e-mail]>

Acked-by: Kees Cook <[e-mail]>

-Kees

Patch

diff --git a/kernel/kexec.c b/kernel/kexec.c
index aed8fb2564b3..68559808fdfa 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -11,6 +11,7 @@ 
 #include <linux/capability.h>
 #include <linux/mm.h>
 #include <linux/file.h>
+#include <linux/security.h>
 #include <linux/kexec.h>
 #include <linux/mutex.h>
 #include <linux/list.h>
@@ -195,10 +196,17 @@  static int do_kexec_load(unsigned long entry, unsigned long nr_segments,
 static inline int kexec_load_check(unsigned long nr_segments,
 				   unsigned long flags)
 {
+	int result;
+
 	/* We only trust the superuser with rebooting the system. */
 	if (!capable(CAP_SYS_BOOT) || kexec_load_disabled)
 		return -EPERM;
 
+	/* Permit LSMs and IMA to fail the kexec */
+	result = security_kernel_load_data(LOADING_KEXEC_IMAGE);
+	if (result < 0)
+		return result;
+
 	/*
 	 * Verify we have a legal set of flags
 	 * This leaves us room for future extensions.