Commit-ID: 73a6492589c87cd56707c8ac19eec78236c2d576 Gitweb: http://git.kernel.org/tip/73a6492589c87cd56707c8ac19eec78236c2d576 Author: Linn Crosetto <l...@hpe.com> AuthorDate: Mon, 25 Apr 2016 21:06:36 +0100 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Thu, 28 Apr 2016 11:33:48 +0200
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: Linn Crosetto <l...@hpe.com> Signed-off-by: Matt Fleming <m...@codeblueprint.co.uk> Reviewed-by: Ard Biesheuvel <ard.biesheu...@linaro.org> Acked-by: Mark Rutland <mark.rutl...@arm.com> Cc: Borislav Petkov <b...@alien8.de> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Roy Franz <roy.fr...@linaro.org> Cc: Thomas Gleixner <t...@linutronix.de> Cc: linux-...@vger.kernel.org Link: http://lkml.kernel.org/r/1461614832-17633-5-git-send-email-m...@codeblueprint.co.uk Signed-off-by: Ingo Molnar <mi...@kernel.org> --- drivers/firmware/efi/libstub/arm-stub.c | 22 ++++++++++++++++++---- 1 file changed, 18 insertions(+), 4 deletions(-) diff --git a/drivers/firmware/efi/libstub/arm-stub.c b/drivers/firmware/efi/libstub/arm-stub.c index 414deb8..07f967c 100644 --- a/drivers/firmware/efi/libstub/arm-stub.c +++ b/drivers/firmware/efi/libstub/arm-stub.c @@ -20,7 +20,7 @@ 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_char16_t const var_name[] = { @@ -39,8 +39,12 @@ static int efi_secureboot_enabled(efi_system_table_t *sys_table_arg) return val; case EFI_NOT_FOUND: return 0; + case EFI_DEVICE_ERROR: + return -EIO; + case EFI_SECURITY_VIOLATION: + return -EACCES; default: - return 1; + return -EINVAL; } } @@ -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; unsigned long reserve_addr = 0; unsigned long reserve_size = 0; + int secure_boot = 0; /* Check if we were booted by the EFI firmware */ 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, if (status != EFI_SUCCESS) 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. */ - if (efi_secureboot_enabled(sys_table)) { - pr_efi(sys_table, "UEFI Secure Boot is enabled.\n"); + if (secure_boot != 0 && strstr(cmdline_ptr, "dtb=")) { + pr_efi(sys_table, "Ignoring DTB from command line.\n"); } else { status = handle_cmdline_files(sys_table, image, cmdline_ptr, "dtb=",
