diff options
| author | Ard Biesheuvel <ard.biesheuvel@linaro.org> | 2014-04-03 17:46:58 +0200 |
|---|---|---|
| committer | Matt Fleming <matt.fleming@intel.com> | 2014-04-30 20:57:06 +0200 |
| commit | 345c736edd07b657a8c48190baed2719b85d0938 (patch) | |
| tree | 6bae228377b6b2f1f7cb60ee6fbce40bcc65cf5e /drivers/firmware | |
| parent | doc: arm64: add description of EFI stub support (diff) | |
| download | linux-345c736edd07b657a8c48190baed2719b85d0938.tar.xz linux-345c736edd07b657a8c48190baed2719b85d0938.zip | |
efi/arm64: ignore dtb= when UEFI SecureBoot is enabled
Loading unauthenticated FDT blobs directly from storage is a security hazard,
so this should only be allowed when running with UEFI Secure Boot disabled.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Leif Lindholm <leif.lindholm@linaro.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Diffstat (limited to 'drivers/firmware')
| -rw-r--r-- | drivers/firmware/efi/arm-stub.c | 39 |
1 files changed, 35 insertions, 4 deletions
diff --git a/drivers/firmware/efi/arm-stub.c b/drivers/firmware/efi/arm-stub.c index 19239a9b7e29..41114ce03b01 100644 --- a/drivers/firmware/efi/arm-stub.c +++ b/drivers/firmware/efi/arm-stub.c @@ -12,6 +12,30 @@ * */ +static int __init efi_secureboot_enabled(efi_system_table_t *sys_table_arg) +{ + static efi_guid_t const var_guid __initconst = EFI_GLOBAL_VARIABLE_GUID; + static efi_char16_t const var_name[] __initconst = { + 'S', 'e', 'c', 'u', 'r', 'e', 'B', 'o', 'o', 't', 0 }; + + efi_get_variable_t *f_getvar = sys_table_arg->runtime->get_variable; + unsigned long size = sizeof(u8); + efi_status_t status; + u8 val; + + status = f_getvar((efi_char16_t *)var_name, (efi_guid_t *)&var_guid, + NULL, &size, &val); + + switch (status) { + case EFI_SUCCESS: + return val; + case EFI_NOT_FOUND: + return 0; + default: + return 1; + } +} + static efi_status_t efi_open_volume(efi_system_table_t *sys_table_arg, void *__image, void **__fh) { @@ -144,7 +168,7 @@ unsigned long __init efi_entry(void *handle, efi_system_table_t *sys_table, /* addr/point and size pairs for memory management*/ unsigned long initrd_addr; u64 initrd_size = 0; - unsigned long fdt_addr; /* Original DTB */ + unsigned long fdt_addr = 0; /* Original DTB */ u64 fdt_size = 0; /* We don't get size from configuration table */ char *cmdline_ptr = NULL; int cmdline_size = 0; @@ -196,9 +220,13 @@ unsigned long __init efi_entry(void *handle, efi_system_table_t *sys_table, goto fail_free_image; } - /* Load a device tree from the configuration table, if present. */ - fdt_addr = (uintptr_t)get_fdt(sys_table); - if (!fdt_addr) { + /* + * 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"); + } else { status = handle_cmdline_files(sys_table, image, cmdline_ptr, "dtb=", ~0UL, (unsigned long *)&fdt_addr, @@ -209,6 +237,9 @@ unsigned long __init efi_entry(void *handle, efi_system_table_t *sys_table, goto fail_free_cmdline; } } + if (!fdt_addr) + /* Look for a device tree configuration table entry. */ + fdt_addr = (uintptr_t)get_fdt(sys_table); status = handle_cmdline_files(sys_table, image, cmdline_ptr, "initrd=", dram_base + SZ_512M, |