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                 efi_err("Failed to open file: %ls\n", fi->filename);
  50                 return status;
  51         }
  52
  53         info_sz = sizeof(struct finfo);
  54         status = fh->get_info(fh, &info_guid, &info_sz, fi);
  55         if (status != EFI_SUCCESS) {
  56                 efi_err("Failed to get file info\n");
  57                 fh->close(fh);
  58                 return status;
  59         }
  60
  61         *handle = fh;
  62         *file_size = fi->info.file_size;
  63         return EFI_SUCCESS;
  64 }
  65
  66 static efi_status_t efi_open_volume(efi_loaded_image_t *image,
  67                                     efi_file_protocol_t **fh)
  68 {
  69         efi_guid_t fs_proto = EFI_FILE_SYSTEM_GUID;
  70         efi_simple_file_system_protocol_t *io;
  71         efi_status_t status;
  72
  73         status = efi_bs_call(handle_protocol, image->device_handle, &fs_proto,
  74                              (void **)&io);
  75         if (status != EFI_SUCCESS) {
  76                 efi_err("Failed to handle fs_proto\n");
  77                 return status;
  78         }
  79
  80         status = io->open_volume(io, fh);
  81         if (status != EFI_SUCCESS)
  82                 efi_err("Failed to open volume\n");
  83
  84         return status;
  85 }
  86
  87 static int find_file_option(const efi_char16_t *cmdline, int cmdline_len,
  88                             const efi_char16_t *prefix, int prefix_size,
  89                             efi_char16_t *result, int result_len)
  90 {
  91         int prefix_len = prefix_size / 2;
  92         bool found = false;
  93         int i;
  94
  95         for (i = prefix_len; i < cmdline_len; i++) {
  96                 if (!memcmp(&cmdline[i - prefix_len], prefix, prefix_size)) {
  97                         found = true;
  98                         break;
  99                 }
 100         }
 101
 102         if (!found)
 103                 return 0;
 104
 105         /* Skip any leading slashes */
 106         while (cmdline[i] == L'/' || cmdline[i] == L'\\')
 107                 i++;
 108
 109         while (--result_len > 0 && i < cmdline_len) {
 110                 efi_char16_t c = cmdline[i++];
 111
 112                 if (c == L'\0' || c == L'\n' || c == L' ')
 113                         break;
 114                 else if (c == L'/')
 115                         /* Replace UNIX dir separators with EFI standard ones */
 116                         *result++ = L'\\';
 117                 else
 118                         *result++ = c;
 119         }
 120         *result = L'\0';
 121         return i;
 122 }
 123
 124 /*
 125  * Check the cmdline for a LILO-style file= arguments.
 126  *
 127  * We only support loading a file from the same filesystem as
 128  * the kernel image.
 129  */
 130 efi_status_t handle_cmdline_files(efi_loaded_image_t *image,
 131                                   const efi_char16_t *optstr,
 132                                   int optstr_size,
 133                                   unsigned long soft_limit,
 134                                   unsigned long hard_limit,
 135                                   unsigned long *load_addr,
 136                                   unsigned long *load_size)
 137 {
 138         const efi_char16_t *cmdline = image->load_options;
 139         int cmdline_len = image->load_options_size / 2;
 140         unsigned long efi_chunk_size = ULONG_MAX;
 141         efi_file_protocol_t *volume = NULL;
 142         efi_file_protocol_t *file;
 143         unsigned long alloc_addr;
 144         unsigned long alloc_size;
 145         efi_status_t status;
 146         int offset;
 147
 148         if (!load_addr || !load_size)
 149                 return EFI_INVALID_PARAMETER;
 150
 151         if (IS_ENABLED(CONFIG_X86) && !efi_nochunk)
 152                 efi_chunk_size = EFI_READ_CHUNK_SIZE;
 153
 154         alloc_addr = alloc_size = 0;
 155         do {
 156                 struct finfo fi;
 157                 unsigned long size;
 158                 void *addr;
 159
 160                 offset = find_file_option(cmdline, cmdline_len,
 161                                           optstr, optstr_size,
 162                                           fi.filename, ARRAY_SIZE(fi.filename));
 163
 164                 if (!offset)
 165                         break;
 166
 167                 cmdline += offset;
 168                 cmdline_len -= offset;
 169
 170                 if (!volume) {
 171                         status = efi_open_volume(image, &volume);
 172                         if (status != EFI_SUCCESS)
 173                                 return status;
 174                 }
 175
 176                 status = efi_open_file(volume, &fi, &file, &size);
 177                 if (status != EFI_SUCCESS)
 178                         goto err_close_volume;
 179
 180                 /*
 181                  * Check whether the existing allocation can contain the next
 182                  * file. This condition will also trigger naturally during the
 183                  * first (and typically only) iteration of the loop, given that
 184                  * alloc_size == 0 in that case.
 185                  */
 186                 if (round_up(alloc_size + size, EFI_ALLOC_ALIGN) >
 187                     round_up(alloc_size, EFI_ALLOC_ALIGN)) {
 188                         unsigned long old_addr = alloc_addr;
 189
 190                         status = EFI_OUT_OF_RESOURCES;
 191                         if (soft_limit < hard_limit)
 192                                 status = efi_allocate_pages(alloc_size + size,
 193                                                             &alloc_addr,
 194                                                             soft_limit);
 195                         if (status == EFI_OUT_OF_RESOURCES)
 196                                 status = efi_allocate_pages(alloc_size + size,
 197                                                             &alloc_addr,
 198                                                             hard_limit);
 199                         if (status != EFI_SUCCESS) {
 200                                 efi_err("Failed to allocate memory for files\n");
 201                                 goto err_close_file;
 202                         }
 203
 204                         if (old_addr != 0) {
 205                                 /*
 206                                  * This is not the first time we've gone
 207                                  * around this loop, and so we are loading
 208                                  * multiple files that need to be concatenated
 209                                  * and returned in a single buffer.
 210                                  */
 211                                 memcpy((void *)alloc_addr, (void *)old_addr, alloc_size);
 212                                 efi_free(alloc_size, old_addr);
 213                         }
 214                 }
 215
 216                 addr = (void *)alloc_addr + alloc_size;
 217                 alloc_size += size;
 218
 219                 while (size) {
 220                         unsigned long chunksize = min(size, efi_chunk_size);
 221
 222                         status = file->read(file, &chunksize, addr);
 223                         if (status != EFI_SUCCESS) {
 224                                 efi_err("Failed to read file\n");
 225                                 goto err_close_file;
 226                         }
 227                         addr += chunksize;
 228                         size -= chunksize;
 229                 }
 230                 file->close(file);
 231         } while (offset > 0);
 232
 233         *load_addr = alloc_addr;
 234         *load_size = alloc_size;
 235
 236         if (volume)
 237                 volume->close(volume);
 238         return EFI_SUCCESS;
 239
 240 err_close_file:
 241         file->close(file);
 242
 243 err_close_volume:
 244         volume->close(volume);
 245         efi_free(alloc_size, alloc_addr);
 246         return status;
 247 }