![Ard Biesheuvel](/assets/img/avatar_default.png)
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>
279 lines
7.9 KiB
C
279 lines
7.9 KiB
C
/*
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* EFI stub implementation that is shared by arm and arm64 architectures.
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* This should be #included by the EFI stub implementation files.
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*
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* Copyright (C) 2013,2014 Linaro Limited
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* Roy Franz <roy.franz@linaro.org
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* Copyright (C) 2013 Red Hat, Inc.
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* Mark Salter <msalter@redhat.com>
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*
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* This file is part of the Linux kernel, and is made available under the
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* terms of the GNU General Public License version 2.
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*
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*/
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static int __init efi_secureboot_enabled(efi_system_table_t *sys_table_arg)
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{
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static efi_guid_t const var_guid __initconst = EFI_GLOBAL_VARIABLE_GUID;
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static efi_char16_t const var_name[] __initconst = {
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'S', 'e', 'c', 'u', 'r', 'e', 'B', 'o', 'o', 't', 0 };
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efi_get_variable_t *f_getvar = sys_table_arg->runtime->get_variable;
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unsigned long size = sizeof(u8);
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efi_status_t status;
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u8 val;
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status = f_getvar((efi_char16_t *)var_name, (efi_guid_t *)&var_guid,
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NULL, &size, &val);
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switch (status) {
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case EFI_SUCCESS:
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return val;
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case EFI_NOT_FOUND:
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return 0;
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default:
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return 1;
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}
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}
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static efi_status_t efi_open_volume(efi_system_table_t *sys_table_arg,
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void *__image, void **__fh)
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{
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efi_file_io_interface_t *io;
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efi_loaded_image_t *image = __image;
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efi_file_handle_t *fh;
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efi_guid_t fs_proto = EFI_FILE_SYSTEM_GUID;
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efi_status_t status;
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void *handle = (void *)(unsigned long)image->device_handle;
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status = sys_table_arg->boottime->handle_protocol(handle,
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&fs_proto, (void **)&io);
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if (status != EFI_SUCCESS) {
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efi_printk(sys_table_arg, "Failed to handle fs_proto\n");
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return status;
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}
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status = io->open_volume(io, &fh);
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if (status != EFI_SUCCESS)
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efi_printk(sys_table_arg, "Failed to open volume\n");
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*__fh = fh;
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return status;
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}
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static efi_status_t efi_file_close(void *handle)
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{
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efi_file_handle_t *fh = handle;
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return fh->close(handle);
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}
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static efi_status_t
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efi_file_read(void *handle, unsigned long *size, void *addr)
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{
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efi_file_handle_t *fh = handle;
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return fh->read(handle, size, addr);
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}
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static efi_status_t
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efi_file_size(efi_system_table_t *sys_table_arg, void *__fh,
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efi_char16_t *filename_16, void **handle, u64 *file_sz)
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{
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efi_file_handle_t *h, *fh = __fh;
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efi_file_info_t *info;
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efi_status_t status;
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efi_guid_t info_guid = EFI_FILE_INFO_ID;
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unsigned long info_sz;
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status = fh->open(fh, &h, filename_16, EFI_FILE_MODE_READ, (u64)0);
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if (status != EFI_SUCCESS) {
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efi_printk(sys_table_arg, "Failed to open file: ");
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efi_char16_printk(sys_table_arg, filename_16);
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efi_printk(sys_table_arg, "\n");
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return status;
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}
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*handle = h;
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info_sz = 0;
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status = h->get_info(h, &info_guid, &info_sz, NULL);
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if (status != EFI_BUFFER_TOO_SMALL) {
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efi_printk(sys_table_arg, "Failed to get file info size\n");
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return status;
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}
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grow:
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status = sys_table_arg->boottime->allocate_pool(EFI_LOADER_DATA,
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info_sz, (void **)&info);
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if (status != EFI_SUCCESS) {
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efi_printk(sys_table_arg, "Failed to alloc mem for file info\n");
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return status;
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}
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status = h->get_info(h, &info_guid, &info_sz,
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info);
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if (status == EFI_BUFFER_TOO_SMALL) {
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sys_table_arg->boottime->free_pool(info);
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goto grow;
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}
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*file_sz = info->file_size;
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sys_table_arg->boottime->free_pool(info);
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if (status != EFI_SUCCESS)
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efi_printk(sys_table_arg, "Failed to get initrd info\n");
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return status;
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}
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static void efi_char16_printk(efi_system_table_t *sys_table_arg,
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efi_char16_t *str)
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{
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struct efi_simple_text_output_protocol *out;
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out = (struct efi_simple_text_output_protocol *)sys_table_arg->con_out;
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out->output_string(out, str);
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}
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/*
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* This function handles the architcture specific differences between arm and
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* arm64 regarding where the kernel image must be loaded and any memory that
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* must be reserved. On failure it is required to free all
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* all allocations it has made.
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*/
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static efi_status_t handle_kernel_image(efi_system_table_t *sys_table,
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unsigned long *image_addr,
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unsigned long *image_size,
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unsigned long *reserve_addr,
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unsigned long *reserve_size,
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unsigned long dram_base,
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efi_loaded_image_t *image);
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/*
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* EFI entry point for the arm/arm64 EFI stubs. This is the entrypoint
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* that is described in the PE/COFF header. Most of the code is the same
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* for both archictectures, with the arch-specific code provided in the
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* handle_kernel_image() function.
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*/
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unsigned long __init efi_entry(void *handle, efi_system_table_t *sys_table,
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unsigned long *image_addr)
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{
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efi_loaded_image_t *image;
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efi_status_t status;
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unsigned long image_size = 0;
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unsigned long dram_base;
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/* addr/point and size pairs for memory management*/
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unsigned long initrd_addr;
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u64 initrd_size = 0;
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unsigned long fdt_addr = 0; /* Original DTB */
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u64 fdt_size = 0; /* We don't get size from configuration table */
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char *cmdline_ptr = NULL;
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int cmdline_size = 0;
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unsigned long new_fdt_addr;
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efi_guid_t loaded_image_proto = LOADED_IMAGE_PROTOCOL_GUID;
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unsigned long reserve_addr = 0;
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unsigned long reserve_size = 0;
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/* Check if we were booted by the EFI firmware */
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if (sys_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE)
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goto fail;
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pr_efi(sys_table, "Booting Linux Kernel...\n");
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/*
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* Get a handle to the loaded image protocol. This is used to get
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* information about the running image, such as size and the command
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* line.
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*/
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status = sys_table->boottime->handle_protocol(handle,
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&loaded_image_proto, (void *)&image);
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if (status != EFI_SUCCESS) {
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pr_efi_err(sys_table, "Failed to get loaded image protocol\n");
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goto fail;
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}
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dram_base = get_dram_base(sys_table);
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if (dram_base == EFI_ERROR) {
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pr_efi_err(sys_table, "Failed to find DRAM base\n");
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goto fail;
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}
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status = handle_kernel_image(sys_table, image_addr, &image_size,
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&reserve_addr,
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&reserve_size,
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dram_base, image);
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if (status != EFI_SUCCESS) {
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pr_efi_err(sys_table, "Failed to relocate kernel\n");
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goto fail;
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}
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/*
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* Get the command line from EFI, using the LOADED_IMAGE
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* protocol. We are going to copy the command line into the
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* device tree, so this can be allocated anywhere.
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*/
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cmdline_ptr = efi_convert_cmdline(sys_table, image, &cmdline_size);
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if (!cmdline_ptr) {
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pr_efi_err(sys_table, "getting command line via LOADED_IMAGE_PROTOCOL\n");
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goto fail_free_image;
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}
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/*
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* Unauthenticated device tree data is a security hazard, so
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* ignore 'dtb=' unless UEFI Secure Boot is disabled.
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*/
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if (efi_secureboot_enabled(sys_table)) {
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pr_efi(sys_table, "UEFI Secure Boot is enabled.\n");
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} else {
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status = handle_cmdline_files(sys_table, image, cmdline_ptr,
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"dtb=",
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~0UL, (unsigned long *)&fdt_addr,
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(unsigned long *)&fdt_size);
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if (status != EFI_SUCCESS) {
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pr_efi_err(sys_table, "Failed to load device tree!\n");
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goto fail_free_cmdline;
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}
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}
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if (!fdt_addr)
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/* Look for a device tree configuration table entry. */
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fdt_addr = (uintptr_t)get_fdt(sys_table);
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status = handle_cmdline_files(sys_table, image, cmdline_ptr,
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"initrd=", dram_base + SZ_512M,
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(unsigned long *)&initrd_addr,
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(unsigned long *)&initrd_size);
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if (status != EFI_SUCCESS)
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pr_efi_err(sys_table, "Failed initrd from command line!\n");
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new_fdt_addr = fdt_addr;
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status = allocate_new_fdt_and_exit_boot(sys_table, handle,
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&new_fdt_addr, dram_base + MAX_FDT_OFFSET,
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initrd_addr, initrd_size, cmdline_ptr,
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fdt_addr, fdt_size);
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/*
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* If all went well, we need to return the FDT address to the
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* calling function so it can be passed to kernel as part of
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* the kernel boot protocol.
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*/
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if (status == EFI_SUCCESS)
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return new_fdt_addr;
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pr_efi_err(sys_table, "Failed to update FDT and exit boot services\n");
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efi_free(sys_table, initrd_size, initrd_addr);
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efi_free(sys_table, fdt_size, fdt_addr);
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fail_free_cmdline:
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efi_free(sys_table, cmdline_size, (unsigned long)cmdline_ptr);
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fail_free_image:
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efi_free(sys_table, image_size, *image_addr);
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efi_free(sys_table, reserve_size, reserve_addr);
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fail:
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return EFI_ERROR;
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}
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