drivers/firmware/efi/libstub/file.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Helper functions used by the EFI stub on multiple
   4  * architectures. This should be #included by the EFI stub
   5  * implementation files.
   6  *
   7  * Copyright 2011 Intel Corporation; author Matt Fleming
   8  */
   9
  10 #include <linux/efi.h>
  11 #include <asm/efi.h>
  12
  13 #include "efistub.h"
  14
  15 #define MAX_FILENAME_SIZE       256
  16
  17 /*
  18  * Some firmware implementations have problems reading files in one go.
  19  * A read chunk size of 1MB seems to work for most platforms.
  20  *
  21  * Unfortunately, reading files in chunks triggers *other* bugs on some
  22  * platforms, so we provide a way to disable this workaround, which can
  23  * be done by passing "efi=nochunk" on the EFI boot stub command line.
  24  *
  25  * If you experience issues with initrd images being corrupt it's worth
  26  * trying efi=nochunk, but chunking is enabled by default on x86 because
  27  * there are far more machines that require the workaround than those that
  28  * break with it enabled.
  29  */
  30 #define EFI_READ_CHUNK_SIZE     SZ_1M
  31
  32 struct finfo {
  33         efi_file_info_t info;
  34         efi_char16_t    filename[MAX_FILENAME_SIZE];
  35 };
  36
  37 static efi_status_t efi_open_file(efi_file_protocol_t *volume,
  38                                   struct finfo *fi,
  39                                   efi_file_protocol_t **handle,
  40                                   unsigned long *file_size)
  41 {
  42         efi_guid_t info_guid = EFI_FILE_INFO_ID;
  43         efi_file_protocol_t *fh;
  44         unsigned long info_sz;
  45         efi_status_t status;
  46
  47         status = volume->open(volume, &fh, fi->filename, EFI_FILE_MODE_READ, 0);
  48         if (status != EFI_SUCCESS) {
  49                 pr_efi_err("Failed to open file: ");
  50                 efi_char16_printk(fi->filename);
  51                 efi_printk("\n");
  52                 return status;
  53         }
  54
  55         info_sz = sizeof(struct finfo);
  56         status = fh->get_info(fh, &info_guid, &info_sz, fi);
  57         if (status != EFI_SUCCESS) {
  58                 pr_efi_err("Failed to get file info\n");
  59                 fh->close(fh);
  60                 return status;
  61         }
  62
  63         *handle = fh;
  64         *file_size = fi->info.file_size;
  65         return EFI_SUCCESS;
  66 }
  67
  68 static efi_status_t efi_open_volume(efi_loaded_image_t *image,
  69                                     efi_file_protocol_t **fh)
  70 {
  71         efi_guid_t fs_proto = EFI_FILE_SYSTEM_GUID;
  72         efi_simple_file_system_protocol_t *io;
  73         efi_status_t status;
  74
  75         status = efi_bs_call(handle_protocol, image->device_handle, &fs_proto,
  76                              (void **)&io);
  77         if (status != EFI_SUCCESS) {
  78                 pr_efi_err("Failed to handle fs_proto\n");
  79                 return status;
  80         }
  81
  82         status = io->open_volume(io, fh);
  83         if (status != EFI_SUCCESS)
  84                 pr_efi_err("Failed to open volume\n");
  85
  86         return status;
  87 }
  88
  89 static int find_file_option(const efi_char16_t *cmdline, int cmdline_len,
  90                             const efi_char16_t *prefix, int prefix_size,
  91                             efi_char16_t *result, int result_len)
  92 {
  93         int prefix_len = prefix_size / 2;
  94         bool found = false;
  95         int i;
  96
  97         for (i = prefix_len; i < cmdline_len; i++) {
  98                 if (!memcmp(&cmdline[i - prefix_len], prefix, prefix_size)) {
  99                         found = true;
 100                         break;
 101                 }
 102         }
 103
 104         if (!found)
 105                 return 0;
 106
 107         while (--result_len > 0 && i < cmdline_len) {
 108                 if (cmdline[i] == L'\0' ||
 109                     cmdline[i] == L'\n' ||
 110                     cmdline[i] == L' ')
 111                         break;
 112                 *result++ = cmdline[i++];
 113         }
 114         *result = L'\0';
 115         return i;
 116 }
 117
 118 /*
 119  * Check the cmdline for a LILO-style file= arguments.
 120  *
 121  * We only support loading a file from the same filesystem as
 122  * the kernel image.
 123  */
 124 static efi_status_t handle_cmdline_files(efi_loaded_image_t *image,
 125                                          const efi_char16_t *optstr,
 126                                          int optstr_size,
 127                                          unsigned long soft_limit,
 128                                          unsigned long hard_limit,
 129                                          unsigned long *load_addr,
 130                                          unsigned long *load_size)
 131 {
 132         const efi_char16_t *cmdline = image->load_options;
 133         int cmdline_len = image->load_options_size / 2;
 134         unsigned long efi_chunk_size = ULONG_MAX;
 135         efi_file_protocol_t *volume = NULL;
 136         efi_file_protocol_t *file;
 137         unsigned long alloc_addr;
 138         unsigned long alloc_size;
 139         efi_status_t status;
 140         int offset;
 141
 142         if (!load_addr || !load_size)
 143                 return EFI_INVALID_PARAMETER;
 144
 145         if (IS_ENABLED(CONFIG_X86) && !nochunk())
 146                 efi_chunk_size = EFI_READ_CHUNK_SIZE;
 147
 148         alloc_addr = alloc_size = 0;
 149         do {
 150                 struct finfo fi;
 151                 unsigned long size;
 152                 void *addr;
 153
 154                 offset = find_file_option(cmdline, cmdline_len,
 155                                           optstr, optstr_size,
 156                                           fi.filename, ARRAY_SIZE(fi.filename));
 157
 158                 if (!offset)
 159                         break;
 160
 161                 cmdline += offset;
 162                 cmdline_len -= offset;
 163
 164                 if (!volume) {
 165                         status = efi_open_volume(image, &volume);
 166                         if (status != EFI_SUCCESS)
 167                                 return status;
 168                 }
 169
 170                 status = efi_open_file(volume, &fi, &file, &size);
 171                 if (status != EFI_SUCCESS)
 172                         goto err_close_volume;
 173
 174                 /*
 175                  * Check whether the existing allocation can contain the next
 176                  * file. This condition will also trigger naturally during the
 177                  * first (and typically only) iteration of the loop, given that
 178                  * alloc_size == 0 in that case.
 179                  */
 180                 if (round_up(alloc_size + size, EFI_ALLOC_ALIGN) >
 181                     round_up(alloc_size, EFI_ALLOC_ALIGN)) {
 182                         unsigned long old_addr = alloc_addr;
 183
 184                         status = EFI_OUT_OF_RESOURCES;
 185                         if (soft_limit < hard_limit)
 186                                 status = efi_allocate_pages(alloc_size + size,
 187                                                             &alloc_addr,
 188                                                             soft_limit);
 189                         if (status == EFI_OUT_OF_RESOURCES)
 190                                 status = efi_allocate_pages(alloc_size + size,
 191                                                             &alloc_addr,
 192                                                             hard_limit);
 193                         if (status != EFI_SUCCESS) {
 194                                 pr_efi_err("Failed to allocate memory for files\n");
 195                                 goto err_close_file;
 196                         }
 197
 198                         if (old_addr != 0) {
 199                                 /*
 200                                  * This is not the first time we've gone
 201                                  * around this loop, and so we are loading
 202                                  * multiple files that need to be concatenated
 203                                  * and returned in a single buffer.
 204                                  */
 205                                 memcpy((void *)alloc_addr, (void *)old_addr, alloc_size);
 206                                 efi_free(alloc_size, old_addr);
 207                         }
 208                 }
 209
 210                 addr = (void *)alloc_addr + alloc_size;
 211                 alloc_size += size;
 212
 213                 while (size) {
 214                         unsigned long chunksize = min(size, efi_chunk_size);
 215
 216                         status = file->read(file, &chunksize, addr);
 217                         if (status != EFI_SUCCESS) {
 218                                 pr_efi_err("Failed to read file\n");
 219                                 goto err_close_file;
 220                         }
 221                         addr += chunksize;
 222                         size -= chunksize;
 223                 }
 224                 file->close(file);
 225         } while (offset > 0);
 226
 227         *load_addr = alloc_addr;
 228         *load_size = alloc_size;
 229
 230         if (volume)
 231                 volume->close(volume);
 232         return EFI_SUCCESS;
 233
 234 err_close_file:
 235         file->close(file);
 236
 237 err_close_volume:
 238         volume->close(volume);
 239         efi_free(alloc_size, alloc_addr);
 240         return status;
 241 }
 242
 243 efi_status_t efi_load_dtb(efi_loaded_image_t *image,
 244                           unsigned long *load_addr,
 245                           unsigned long *load_size)
 246 {
 247         return handle_cmdline_files(image, L"dtb=", sizeof(L"dtb=") - 2,
 248                                     ULONG_MAX, ULONG_MAX, load_addr, load_size);
 249 }
 250
 251 efi_status_t efi_load_initrd(efi_loaded_image_t *image,
 252                              unsigned long *load_addr,
 253                              unsigned long *load_size,
 254                              unsigned long soft_limit,
 255                              unsigned long hard_limit)
 256 {
 257         return handle_cmdline_files(image, L"initrd=", sizeof(L"initrd=") - 2,
 258                                     soft_limit, hard_limit, load_addr, load_size);
 259 }