[PATCH V40 10/29] hibernate: Disable when the kernel is locked down

[Matthew Garrett]

From: Josh Boyer <jwboyer at fedoraproject.org>

There is currently no way to verify the resume image when returning
from hibernate.  This might compromise the signed modules trust model,
so until we can work with signed hibernate images we disable it when the
kernel is locked down.

Signed-off-by: Josh Boyer <jwboyer at fedoraproject.org>
Signed-off-by: David Howells <dhowells at redhat.com>
Signed-off-by: Matthew Garrett <mjg59 at google.com>
Reviewed-by: Kees Cook <keescook at chromium.org>
Cc: rjw at rjwysocki.net
Cc: pavel at ucw.cz
cc: linux-pm at vger.kernel.org
Signed-off-by: James Morris <jmorris at namei.org>
---
 include/linux/security.h     | 1 +
 kernel/power/hibernate.c     | 3 ++-
 security/lockdown/lockdown.c | 1 +
 3 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/include/linux/security.h b/include/linux/security.h
index b607a8ac97fe..80ac7fb27aa9 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -106,6 +106,7 @@ enum lockdown_reason {
 	LOCKDOWN_MODULE_SIGNATURE,
 	LOCKDOWN_DEV_MEM,
 	LOCKDOWN_KEXEC,
+	LOCKDOWN_HIBERNATION,
 	LOCKDOWN_INTEGRITY_MAX,
 	LOCKDOWN_CONFIDENTIALITY_MAX,
 };
diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index cd7434e6000d..3c0a5a8170b0 100644
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -30,6 +30,7 @@
 #include <linux/ctype.h>
 #include <linux/genhd.h>
 #include <linux/ktime.h>
+#include <linux/security.h>
 #include <trace/events/power.h>
 
 #include "power.h"
@@ -68,7 +69,7 @@ static const struct platform_hibernation_ops *hibernation_ops;
 
 bool hibernation_available(void)
 {
-	return (nohibernate == 0);
+	return nohibernate == 0 && !security_locked_down(LOCKDOWN_HIBERNATION);
 }
 
 /**
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index aaf30ad351f9..3462f7edcaac 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -21,6 +21,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
 	[LOCKDOWN_MODULE_SIGNATURE] = "unsigned module loading",
 	[LOCKDOWN_DEV_MEM] = "/dev/mem,kmem,port",
 	[LOCKDOWN_KEXEC] = "kexec of unsigned images",
+	[LOCKDOWN_HIBERNATION] = "hibernation",
 	[LOCKDOWN_INTEGRITY_MAX] = "integrity",
 	[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
 };
-- 
2.23.0.rc1.153.gdeed80330f-goog