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authorDavid Howells <dhowells@redhat.com>2017-02-06 11:22:43 +0000
committerIngo Molnar <mingo@kernel.org>2017-02-07 10:42:10 +0100
commitde8cb458625c164bb3f93c4e415e479afce8fa9d (patch)
tree6da87e0a45c5d1e39bc5f46413123358734d8eba /drivers/firmware
parente58910cdc9f43cda2e52fcdf2fddbdc74e80b2f7 (diff)
downloadlinux-de8cb458625c164bb3f93c4e415e479afce8fa9d.tar.bz2
efi: Get and store the secure boot status
Get the firmware's secure-boot status in the kernel boot wrapper and stash it somewhere that the main kernel image can find. The efi_get_secureboot() function is extracted from the ARM stub and (a) generalised so that it can be called from x86 and (b) made to use efi_call_runtime() so that it can be run in mixed-mode. For x86, it is stored in boot_params and can be overridden by the boot loader or kexec. This allows secure-boot mode to be passed on to a new kernel. Suggested-by: Lukas Wunner <lukas@wunner.de> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matt Fleming <matt@codeblueprint.co.uk> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/1486380166-31868-5-git-send-email-ard.biesheuvel@linaro.org [ Small readability edits. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'drivers/firmware')
-rw-r--r--drivers/firmware/efi/libstub/Makefile2
-rw-r--r--drivers/firmware/efi/libstub/arm-stub.c63
-rw-r--r--drivers/firmware/efi/libstub/secureboot.c61
3 files changed, 68 insertions, 58 deletions
diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
index 33e0e2f1a730..f7425960f6a5 100644
--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -28,7 +28,7 @@ OBJECT_FILES_NON_STANDARD := y
# Prevents link failures: __sanitizer_cov_trace_pc() is not linked in.
KCOV_INSTRUMENT := n
-lib-y := efi-stub-helper.o gop.o
+lib-y := efi-stub-helper.o gop.o secureboot.o
# include the stub's generic dependencies from lib/ when building for ARM/arm64
arm-deps := fdt_rw.c fdt_ro.c fdt_wip.c fdt.c fdt_empty_tree.c fdt_sw.c sort.c
diff --git a/drivers/firmware/efi/libstub/arm-stub.c b/drivers/firmware/efi/libstub/arm-stub.c
index 6fca48c9e054..d4056c6be1ec 100644
--- a/drivers/firmware/efi/libstub/arm-stub.c
+++ b/drivers/firmware/efi/libstub/arm-stub.c
@@ -20,52 +20,6 @@
bool __nokaslr;
-static int efi_get_secureboot(efi_system_table_t *sys_table_arg)
-{
- static efi_char16_t const sb_var_name[] = {
- 'S', 'e', 'c', 'u', 'r', 'e', 'B', 'o', 'o', 't', 0 };
- static efi_char16_t const sm_var_name[] = {
- 'S', 'e', 't', 'u', 'p', 'M', 'o', 'd', 'e', 0 };
-
- efi_guid_t var_guid = EFI_GLOBAL_VARIABLE_GUID;
- efi_get_variable_t *f_getvar = sys_table_arg->runtime->get_variable;
- u8 val;
- unsigned long size = sizeof(val);
- efi_status_t status;
-
- status = f_getvar((efi_char16_t *)sb_var_name, (efi_guid_t *)&var_guid,
- NULL, &size, &val);
-
- if (status != EFI_SUCCESS)
- goto out_efi_err;
-
- if (val == 0)
- return 0;
-
- status = f_getvar((efi_char16_t *)sm_var_name, (efi_guid_t *)&var_guid,
- NULL, &size, &val);
-
- if (status != EFI_SUCCESS)
- goto out_efi_err;
-
- if (val == 1)
- return 0;
-
- return 1;
-
-out_efi_err:
- switch (status) {
- case EFI_NOT_FOUND:
- return 0;
- case EFI_DEVICE_ERROR:
- return -EIO;
- case EFI_SECURITY_VIOLATION:
- return -EACCES;
- default:
- return -EINVAL;
- }
-}
-
efi_status_t efi_open_volume(efi_system_table_t *sys_table_arg,
void *__image, void **__fh)
{
@@ -157,7 +111,7 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table,
efi_guid_t loaded_image_proto = LOADED_IMAGE_PROTOCOL_GUID;
unsigned long reserve_addr = 0;
unsigned long reserve_size = 0;
- int secure_boot = 0;
+ enum efi_secureboot_mode secure_boot;
struct screen_info *si;
/* Check if we were booted by the EFI firmware */
@@ -227,19 +181,14 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table,
pr_efi_err(sys_table, "Failed to parse EFI cmdline options\n");
secure_boot = efi_get_secureboot(sys_table);
- if (secure_boot > 0)
- pr_efi(sys_table, "UEFI Secure Boot is enabled.\n");
-
- if (secure_boot < 0) {
- pr_efi_err(sys_table,
- "could not determine UEFI Secure Boot status.\n");
- }
/*
- * Unauthenticated device tree data is a security hazard, so
- * ignore 'dtb=' unless UEFI Secure Boot is disabled.
+ * Unauthenticated device tree data is a security hazard, so ignore
+ * 'dtb=' unless UEFI Secure Boot is disabled. We assume that secure
+ * boot is enabled if we can't determine its state.
*/
- if (secure_boot != 0 && strstr(cmdline_ptr, "dtb=")) {
+ if (secure_boot != efi_secureboot_mode_disabled &&
+ strstr(cmdline_ptr, "dtb=")) {
pr_efi(sys_table, "Ignoring DTB from command line.\n");
} else {
status = handle_cmdline_files(sys_table, image, cmdline_ptr,
diff --git a/drivers/firmware/efi/libstub/secureboot.c b/drivers/firmware/efi/libstub/secureboot.c
new file mode 100644
index 000000000000..b20b8b460d77
--- /dev/null
+++ b/drivers/firmware/efi/libstub/secureboot.c
@@ -0,0 +1,61 @@
+/*
+ * Secure boot handling.
+ *
+ * Copyright (C) 2013,2014 Linaro Limited
+ * Roy Franz <roy.franz@linaro.org
+ * Copyright (C) 2013 Red Hat, Inc.
+ * Mark Salter <msalter@redhat.com>
+ *
+ * This file is part of the Linux kernel, and is made available under the
+ * terms of the GNU General Public License version 2.
+ */
+#include <linux/efi.h>
+#include <asm/efi.h>
+
+/* BIOS variables */
+static const efi_guid_t efi_variable_guid = EFI_GLOBAL_VARIABLE_GUID;
+static const efi_char16_t const efi_SecureBoot_name[] = {
+ 'S', 'e', 'c', 'u', 'r', 'e', 'B', 'o', 'o', 't', 0
+};
+static const efi_char16_t const efi_SetupMode_name[] = {
+ 'S', 'e', 't', 'u', 'p', 'M', 'o', 'd', 'e', 0
+};
+
+#define get_efi_var(name, vendor, ...) \
+ efi_call_runtime(get_variable, \
+ (efi_char16_t *)(name), (efi_guid_t *)(vendor), \
+ __VA_ARGS__);
+
+/*
+ * Determine whether we're in secure boot mode.
+ */
+enum efi_secureboot_mode efi_get_secureboot(efi_system_table_t *sys_table_arg)
+{
+ u8 secboot, setupmode;
+ unsigned long size;
+ efi_status_t status;
+
+ size = sizeof(secboot);
+ status = get_efi_var(efi_SecureBoot_name, &efi_variable_guid,
+ NULL, &size, &secboot);
+ if (status != EFI_SUCCESS)
+ goto out_efi_err;
+
+ size = sizeof(setupmode);
+ status = get_efi_var(efi_SetupMode_name, &efi_variable_guid,
+ NULL, &size, &setupmode);
+ if (status != EFI_SUCCESS)
+ goto out_efi_err;
+
+ if (secboot == 0 || setupmode == 1)
+ return efi_secureboot_mode_disabled;
+
+ pr_efi(sys_table_arg, "UEFI Secure Boot is enabled.\n");
+ return efi_secureboot_mode_enabled;
+
+out_efi_err:
+ pr_efi_err(sys_table_arg, "Could not determine UEFI Secure Boot status.\n");
+ if (status == EFI_NOT_FOUND)
+ return efi_secureboot_mode_disabled;
+ return efi_secureboot_mode_unknown;
+}