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authorArd Biesheuvel <ard.biesheuvel@linaro.org>2014-04-03 17:46:58 +0200
committerMark Brown <broonie@linaro.org>2014-07-24 22:58:42 +0100
commita7d8ac550cb83d8ae0aec1e00aad9bb72ea1eb07 (patch)
tree3a98db660fd88e12b2f793f8c4b02dd6441d967f
parente26b51869efe9b1ea28632d1076953ce64670588 (diff)
downloadlinux-linaro-stable-a7d8ac550cb83d8ae0aec1e00aad9bb72ea1eb07.tar.gz
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> (cherry picked from commit 345c736edd07b657a8c48190baed2719b85d0938) Signed-off-by: Mark Brown <broonie@linaro.org>
-rw-r--r--drivers/firmware/efi/arm-stub.c39
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,