[PATCH V38 10/29] hibernate: Disable when the kernel is locked down

[Matthew Garrett]

From: Josh Boyer <jwboyer@xxxxxxxxxxxxxxxxx>

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@xxxxxxxxxxxxxxxxx>
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
Signed-off-by: Matthew Garrett <mjg59@xxxxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: rjw@xxxxxxxxxxxxx
Cc: pavel@xxxxxx
cc: linux-pm@xxxxxxxxxxxxxxx
---
 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 69c5de539e9a..304a155a5628 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 6f302c156bc8..a0996f75629f 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",
 };
-- 
2.22.0.770.g0f2c4a37fd-goog