The firmware has a set of flags that indicate whether secure boot is enabled
and enforcing. Use them to indicate whether the kernel should lock itself
down.
Signed-off-by: Matthew Garrett <mjg@xxxxxxxxxx>
---
Documentation/x86/zero-page.txt | 2 ++
arch/x86/boot/compressed/eboot.c | 32 ++++++++++++++++++++++++++++++++
arch/x86/include/asm/bootparam.h | 3 ++-
arch/x86/kernel/setup.c | 3 +++
include/linux/cred.h | 2 ++
5 files changed, 41 insertions(+), 1 deletion(-)
diff --git a/Documentation/x86/zero-page.txt b/Documentation/x86/zero-page.txt
index cf5437d..7f9ed48 100644
--- a/Documentation/x86/zero-page.txt
+++ b/Documentation/x86/zero-page.txt
@@ -27,6 +27,8 @@ Offset Proto Name Meaning
1E9/001 ALL eddbuf_entries Number of entries in eddbuf (below)
1EA/001 ALL edd_mbr_sig_buf_entries Number of entries in edd_mbr_sig_buffer
(below)
+1EB/001 ALL kbd_status Numlock is enabled
+1EC/001 ALL secure_boot Kernel should enable secure boot lockdowns
290/040 ALL edd_mbr_sig_buffer EDD MBR signatures
2D0/A00 ALL e820_map E820 memory map table
(array of struct e820entry)
diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
index b3e0227..3789356 100644
--- a/arch/x86/boot/compressed/eboot.c
+++ b/arch/x86/boot/compressed/eboot.c
@@ -724,6 +724,36 @@ fail:
return status;
}
+static int get_secure_boot(efi_system_table_t *_table)
+{
+ u8 sb, setup;
+ unsigned long datasize = sizeof(sb);
+ efi_guid_t var_guid = EFI_GLOBAL_VARIABLE_GUID;
+ efi_status_t status;
+
+ status = efi_call_phys5(sys_table->runtime->get_variable,
+ L"SecureBoot", &var_guid, NULL, &datasize, &sb);
+
+ if (status != EFI_SUCCESS)
+ return 0;
+
+ if (sb == 0)
+ return 0;
+
+
+ status = efi_call_phys5(sys_table->runtime->get_variable,
+ L"SetupMode", &var_guid, NULL, &datasize,
+ &setup);
+
+ if (status != EFI_SUCCESS)
+ return 0;
+
+ if (setup == 1)
+ return 0;
+
+ return 1;
+}
+
/*
* Because the x86 boot code expects to be passed a boot_params we
* need to create one ourselves (usually the bootloader would create
@@ -1018,6 +1048,8 @@ struct boot_params *efi_main(void *handle, efi_system_table_t *_table,
if (sys_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE)
goto fail;
+ boot_params->secure_boot = get_secure_boot(sys_table);
+
setup_graphics(boot_params);
status = efi_call_phys3(sys_table->boottime->allocate_pool,
diff --git a/arch/x86/include/asm/bootparam.h b/arch/x86/include/asm/bootparam.h
index 2ad874c..c7338e0 100644
--- a/arch/x86/include/asm/bootparam.h
+++ b/arch/x86/include/asm/bootparam.h
@@ -114,7 +114,8 @@ struct boot_params {
__u8 eddbuf_entries; /* 0x1e9 */
__u8 edd_mbr_sig_buf_entries; /* 0x1ea */
__u8 kbd_status; /* 0x1eb */
- __u8 _pad6[5]; /* 0x1ec */
+ __u8 secure_boot; /* 0x1ec */
+ __u8 _pad6[4]; /* 0x1ed */
struct setup_header hdr; /* setup header */ /* 0x1f1 */
__u8 _pad7[0x290-0x1f1-sizeof(struct setup_header)];
__u32 edd_mbr_sig_buffer[EDD_MBR_SIG_MAX]; /* 0x290 */
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index f4b9b80..239bf2a 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -947,6 +947,9 @@ void __init setup_arch(char **cmdline_p)
io_delay_init();
+ if (boot_params.secure_boot)
+ secureboot_enable();
+
/*
* Parse the ACPI tables for possible boot-time SMP configuration.
*/
diff --git a/include/linux/cred.h b/include/linux/cred.h
index ebbed2c..a24faf1 100644
--- a/include/linux/cred.h
+++ b/include/linux/cred.h
@@ -170,6 +170,8 @@ extern int set_security_override_from_ctx(struct cred *, const char *);
extern int set_create_files_as(struct cred *, struct inode *);
extern void __init cred_init(void);
+extern void secureboot_enable(void);
+
/*
* check for validity of credentials
*/
--
1.7.11.4
--
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