linux/drivers/firmware/efi/arm-stub.c
Ard Biesheuvel 345c736edd 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>
2014-04-30 19:57:06 +01:00

279 lines
7.9 KiB
C

/*
* EFI stub implementation that is shared by arm and arm64 architectures.
* This should be #included by the EFI stub implementation files.
*
* Copyright (C) 2013,2014 Linaro Limited
* Roy Franz <roy.franz@linaro.org
* Copyright (C) 2013 Red Hat, Inc.
* Mark Salter <msalter@redhat.com>
*
* This file is part of the Linux kernel, and is made available under the
* terms of the GNU General Public License version 2.
*
*/
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)
{
efi_file_io_interface_t *io;
efi_loaded_image_t *image = __image;
efi_file_handle_t *fh;
efi_guid_t fs_proto = EFI_FILE_SYSTEM_GUID;
efi_status_t status;
void *handle = (void *)(unsigned long)image->device_handle;
status = sys_table_arg->boottime->handle_protocol(handle,
&fs_proto, (void **)&io);
if (status != EFI_SUCCESS) {
efi_printk(sys_table_arg, "Failed to handle fs_proto\n");
return status;
}
status = io->open_volume(io, &fh);
if (status != EFI_SUCCESS)
efi_printk(sys_table_arg, "Failed to open volume\n");
*__fh = fh;
return status;
}
static efi_status_t efi_file_close(void *handle)
{
efi_file_handle_t *fh = handle;
return fh->close(handle);
}
static efi_status_t
efi_file_read(void *handle, unsigned long *size, void *addr)
{
efi_file_handle_t *fh = handle;
return fh->read(handle, size, addr);
}
static efi_status_t
efi_file_size(efi_system_table_t *sys_table_arg, void *__fh,
efi_char16_t *filename_16, void **handle, u64 *file_sz)
{
efi_file_handle_t *h, *fh = __fh;
efi_file_info_t *info;
efi_status_t status;
efi_guid_t info_guid = EFI_FILE_INFO_ID;
unsigned long info_sz;
status = fh->open(fh, &h, filename_16, EFI_FILE_MODE_READ, (u64)0);
if (status != EFI_SUCCESS) {
efi_printk(sys_table_arg, "Failed to open file: ");
efi_char16_printk(sys_table_arg, filename_16);
efi_printk(sys_table_arg, "\n");
return status;
}
*handle = h;
info_sz = 0;
status = h->get_info(h, &info_guid, &info_sz, NULL);
if (status != EFI_BUFFER_TOO_SMALL) {
efi_printk(sys_table_arg, "Failed to get file info size\n");
return status;
}
grow:
status = sys_table_arg->boottime->allocate_pool(EFI_LOADER_DATA,
info_sz, (void **)&info);
if (status != EFI_SUCCESS) {
efi_printk(sys_table_arg, "Failed to alloc mem for file info\n");
return status;
}
status = h->get_info(h, &info_guid, &info_sz,
info);
if (status == EFI_BUFFER_TOO_SMALL) {
sys_table_arg->boottime->free_pool(info);
goto grow;
}
*file_sz = info->file_size;
sys_table_arg->boottime->free_pool(info);
if (status != EFI_SUCCESS)
efi_printk(sys_table_arg, "Failed to get initrd info\n");
return status;
}
static void efi_char16_printk(efi_system_table_t *sys_table_arg,
efi_char16_t *str)
{
struct efi_simple_text_output_protocol *out;
out = (struct efi_simple_text_output_protocol *)sys_table_arg->con_out;
out->output_string(out, str);
}
/*
* This function handles the architcture specific differences between arm and
* arm64 regarding where the kernel image must be loaded and any memory that
* must be reserved. On failure it is required to free all
* all allocations it has made.
*/
static efi_status_t handle_kernel_image(efi_system_table_t *sys_table,
unsigned long *image_addr,
unsigned long *image_size,
unsigned long *reserve_addr,
unsigned long *reserve_size,
unsigned long dram_base,
efi_loaded_image_t *image);
/*
* EFI entry point for the arm/arm64 EFI stubs. This is the entrypoint
* that is described in the PE/COFF header. Most of the code is the same
* for both archictectures, with the arch-specific code provided in the
* handle_kernel_image() function.
*/
unsigned long __init efi_entry(void *handle, efi_system_table_t *sys_table,
unsigned long *image_addr)
{
efi_loaded_image_t *image;
efi_status_t status;
unsigned long image_size = 0;
unsigned long dram_base;
/* addr/point and size pairs for memory management*/
unsigned long initrd_addr;
u64 initrd_size = 0;
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;
unsigned long new_fdt_addr;
efi_guid_t loaded_image_proto = LOADED_IMAGE_PROTOCOL_GUID;
unsigned long reserve_addr = 0;
unsigned long reserve_size = 0;
/* Check if we were booted by the EFI firmware */
if (sys_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE)
goto fail;
pr_efi(sys_table, "Booting Linux Kernel...\n");
/*
* Get a handle to the loaded image protocol. This is used to get
* information about the running image, such as size and the command
* line.
*/
status = sys_table->boottime->handle_protocol(handle,
&loaded_image_proto, (void *)&image);
if (status != EFI_SUCCESS) {
pr_efi_err(sys_table, "Failed to get loaded image protocol\n");
goto fail;
}
dram_base = get_dram_base(sys_table);
if (dram_base == EFI_ERROR) {
pr_efi_err(sys_table, "Failed to find DRAM base\n");
goto fail;
}
status = handle_kernel_image(sys_table, image_addr, &image_size,
&reserve_addr,
&reserve_size,
dram_base, image);
if (status != EFI_SUCCESS) {
pr_efi_err(sys_table, "Failed to relocate kernel\n");
goto fail;
}
/*
* Get the command line from EFI, using the LOADED_IMAGE
* protocol. We are going to copy the command line into the
* device tree, so this can be allocated anywhere.
*/
cmdline_ptr = efi_convert_cmdline(sys_table, image, &cmdline_size);
if (!cmdline_ptr) {
pr_efi_err(sys_table, "getting command line via LOADED_IMAGE_PROTOCOL\n");
goto fail_free_image;
}
/*
* 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,
(unsigned long *)&fdt_size);
if (status != EFI_SUCCESS) {
pr_efi_err(sys_table, "Failed to load device tree!\n");
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,
(unsigned long *)&initrd_addr,
(unsigned long *)&initrd_size);
if (status != EFI_SUCCESS)
pr_efi_err(sys_table, "Failed initrd from command line!\n");
new_fdt_addr = fdt_addr;
status = allocate_new_fdt_and_exit_boot(sys_table, handle,
&new_fdt_addr, dram_base + MAX_FDT_OFFSET,
initrd_addr, initrd_size, cmdline_ptr,
fdt_addr, fdt_size);
/*
* If all went well, we need to return the FDT address to the
* calling function so it can be passed to kernel as part of
* the kernel boot protocol.
*/
if (status == EFI_SUCCESS)
return new_fdt_addr;
pr_efi_err(sys_table, "Failed to update FDT and exit boot services\n");
efi_free(sys_table, initrd_size, initrd_addr);
efi_free(sys_table, fdt_size, fdt_addr);
fail_free_cmdline:
efi_free(sys_table, cmdline_size, (unsigned long)cmdline_ptr);
fail_free_image:
efi_free(sys_table, image_size, *image_addr);
efi_free(sys_table, reserve_size, reserve_addr);
fail:
return EFI_ERROR;
}