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efi/arm64: ignore dtb= when UEFI SecureBoot is enabled

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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>
This commit is contained in:
Ard Biesheuvel 2014-04-03 17:46:58 +02:00 committed by Matt Fleming
parent cdd7857898
commit 345c736edd
1 changed files with 35 additions and 4 deletions
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39
drivers/firmware/efi/arm-stub.c
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@ -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,