Commit 73a64925 authored by Linn Crosetto's avatar Linn Crosetto Committed by Ingo Molnar

efi/arm64: Report unexpected errors when determining Secure Boot status

Certain code in the boot path may require the ability to determine whether
UEFI Secure Boot is definitely enabled, for example printing status to the
console. Other code may need to know when UEFI Secure Boot is definitely
disabled, for example restricting use of kernel parameters.

If an unexpected error is returned from GetVariable() when querying the
status of UEFI Secure Boot, return an error to the caller. This allows the
caller to determine the definite state, and to take appropriate action if
an expected error is returned.
Signed-off-by: default avatarLinn Crosetto <linn@hpe.com>
Signed-off-by: default avatarMatt Fleming <matt@codeblueprint.co.uk>
Reviewed-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: default avatarMark Rutland <mark.rutland@arm.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Roy Franz <roy.franz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/1461614832-17633-5-git-send-email-matt@codeblueprint.co.ukSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 7fc8442f
...@@ -20,7 +20,7 @@ ...@@ -20,7 +20,7 @@
bool __nokaslr; bool __nokaslr;
static int efi_secureboot_enabled(efi_system_table_t *sys_table_arg) static int efi_get_secureboot(efi_system_table_t *sys_table_arg)
{ {
static efi_guid_t const var_guid = EFI_GLOBAL_VARIABLE_GUID; static efi_guid_t const var_guid = EFI_GLOBAL_VARIABLE_GUID;
static efi_char16_t const var_name[] = { static efi_char16_t const var_name[] = {
...@@ -39,8 +39,12 @@ static int efi_secureboot_enabled(efi_system_table_t *sys_table_arg) ...@@ -39,8 +39,12 @@ static int efi_secureboot_enabled(efi_system_table_t *sys_table_arg)
return val; return val;
case EFI_NOT_FOUND: case EFI_NOT_FOUND:
return 0; return 0;
case EFI_DEVICE_ERROR:
return -EIO;
case EFI_SECURITY_VIOLATION:
return -EACCES;
default: default:
return 1; return -EINVAL;
} }
} }
...@@ -185,6 +189,7 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table, ...@@ -185,6 +189,7 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table,
efi_guid_t loaded_image_proto = LOADED_IMAGE_PROTOCOL_GUID; efi_guid_t loaded_image_proto = LOADED_IMAGE_PROTOCOL_GUID;
unsigned long reserve_addr = 0; unsigned long reserve_addr = 0;
unsigned long reserve_size = 0; unsigned long reserve_size = 0;
int secure_boot = 0;
/* Check if we were booted by the EFI firmware */ /* Check if we were booted by the EFI firmware */
if (sys_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE) if (sys_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE)
...@@ -250,12 +255,21 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table, ...@@ -250,12 +255,21 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table,
if (status != EFI_SUCCESS) if (status != EFI_SUCCESS)
pr_efi_err(sys_table, "Failed to parse EFI cmdline options\n"); 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 * Unauthenticated device tree data is a security hazard, so
* ignore 'dtb=' unless UEFI Secure Boot is disabled. * ignore 'dtb=' unless UEFI Secure Boot is disabled.
*/ */
if (efi_secureboot_enabled(sys_table)) { if (secure_boot != 0 && strstr(cmdline_ptr, "dtb=")) {
pr_efi(sys_table, "UEFI Secure Boot is enabled.\n"); pr_efi(sys_table, "Ignoring DTB from command line.\n");
} else { } else {
status = handle_cmdline_files(sys_table, image, cmdline_ptr, status = handle_cmdline_files(sys_table, image, cmdline_ptr,
"dtb=", "dtb=",
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment