[PATCH v2 15/16] PM / hibernate: Bypass verification logic on legacy BIOS

Lee, Chun-Yi
2015-08-11T06:19:35Z

Current hibernate signature verification solution relies on EFI stub
and efi boot service variable on x86 architecture. So the verification
logic was bypassed on legacy BIOS through checking EFI_BOOT flag.

Reviewed-by: Jiri Kosina <jkosina@suse.com>
Tested-by: Jiri Kosina <jkosina@suse.com>
Signed-off-by: Lee, Chun-Yi <jlee@suse.com>
---
drivers/firmware/efi/efi-hibernate_keys.c | 3 +++
kernel/power/Kconfig | 3 ++-
kernel/power/snapshot.c | 8 ++++++--
kernel/power/user.c | 6 +++++-
4 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/drivers/firmware/efi/efi-hibernate_keys.c b/drivers/firmware/efi/efi-hibernate_keys.c
index 8a50bf1..2125302 100644
--- a/drivers/firmware/efi/efi-hibernate_keys.c
+++ b/drivers/firmware/efi/efi-hibernate_keys.c
@@ -17,6 +17,9 @@ void create_hibernation_key_regen_flag(void)
struct efivar_entry *entry = NULL;
int err = 0;

+ if (!efi_enabled(EFI_RUNTIME_SERVICES))
+ return;
+
if (!set_hibernation_key_regen_flag)
return;

diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
index 1a03777..c30598e 100644
--- a/kernel/power/Kconfig
+++ b/kernel/power/Kconfig
@@ -78,7 +78,8 @@ config HIBERNATE_VERIFICATION
This option provides support for generating and verifying the
signature of memory snapshot image by HMAC-SHA1. Current mechanism
relies on UEFI secure boot environment, EFI stub generates HMAC
- key for hibernate verification.
+ key for hibernate verification. So, the verification logic will be
+ bypassed on legacy BIOS.

config HIBERNATE_VERIFICATION_FORCE
bool "Require hibernate snapshot image to be validly signed"
diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
index 486dd73..22b80b7 100644
--- a/kernel/power/snapshot.c
+++ b/kernel/power/snapshot.c
@@ -29,6 +29,7 @@
#include <linux/slab.h>
#include <linux/compiler.h>
#include <linux/ktime.h>
+#include <linux/efi.h>

#include <asm/uaccess.h>
#include <asm/mmu_context.h>
@@ -1469,8 +1470,11 @@ error_digest:
forward_ret:
if (ret)
pr_warn("PM: Signature verifying failed: %d\n", ret);
- /* forward check result when verifying pass or not enforce verifying */
- if (!ret || !sigenforce) {
+ if (ret == -ENODEV && !efi_enabled(EFI_BOOT)) {
+ pr_warn("PM: Bypass verification on non-EFI machine\n");
+ ret = 0;
+ } else if (!ret || !sigenforce) {
+ /* forward check result when verifying pass or not enforce verifying */
snapshot_fill_sig_forward_info(ret);
ret = 0;
}
diff --git a/kernel/power/user.c b/kernel/power/user.c
index a183abd..686d095 100644
--- a/kernel/power/user.c
+++ b/kernel/power/user.c
@@ -24,6 +24,7 @@
#include <linux/console.h>
#include <linux/cpu.h>
#include <linux/freezer.h>
+#include <linux/efi.h>

#include <asm/uaccess.h>

@@ -393,7 +394,10 @@ static long snapshot_ioctl(struct file *filp, unsigned int cmd,
break;

case SNAPSHOT_REGENERATE_KEY:
- set_hibernation_key_regen_flag = !!arg;
+ if (!efi_enabled(EFI_BOOT))
+ error = -ENODEV;
+ else
+ set_hibernation_key_regen_flag = !!arg;
break;

default:
--
2.1.4