lib/efi_loader/efi_bootmgr.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  *  EFI boot manager
   4  *
   5  *  Copyright (c) 2017 Rob Clark
   6  */
   7
   8 #define LOG_CATEGORY LOGC_EFI
   9
  10 #include <common.h>
  11 #include <charset.h>
  12 #include <log.h>
  13 #include <malloc.h>
  14 #include <efi_loader.h>
  15 #include <efi_variable.h>
  16 #include <asm/unaligned.h>
  17
  18 static const struct efi_boot_services *bs;
  19 static const struct efi_runtime_services *rs;
  20
  21 /*
  22  * bootmgr implements the logic of trying to find a payload to boot
  23  * based on the BootOrder + BootXXXX variables, and then loading it.
  24  *
  25  * TODO detecting a special key held (f9?) and displaying a boot menu
  26  * like you would get on a PC would be clever.
  27  *
  28  * TODO if we had a way to write and persist variables after the OS
  29  * has started, we'd also want to check OsIndications to see if we
  30  * should do normal or recovery boot.
  31  */
  32
  33 /**
  34  * efi_set_load_options() - set the load options of a loaded image
  35  *
  36  * @handle:             the image handle
  37  * @load_options_size:  size of load options
  38  * @load_options:       pointer to load options
  39  * Return:              status code
  40  */
  41 efi_status_t efi_set_load_options(efi_handle_t handle,
  42                                   efi_uintn_t load_options_size,
  43                                   void *load_options)
  44 {
  45         struct efi_loaded_image *loaded_image_info;
  46         efi_status_t ret;
  47
  48         ret = EFI_CALL(systab.boottime->open_protocol(
  49                                         handle,
  50                                         &efi_guid_loaded_image,
  51                                         (void **)&loaded_image_info,
  52                                         efi_root, NULL,
  53                                         EFI_OPEN_PROTOCOL_BY_HANDLE_PROTOCOL));
  54         if (ret != EFI_SUCCESS)
  55                 return EFI_INVALID_PARAMETER;
  56
  57         loaded_image_info->load_options = load_options;
  58         loaded_image_info->load_options_size = load_options_size;
  59
  60         return EFI_CALL(systab.boottime->close_protocol(handle,
  61                                                         &efi_guid_loaded_image,
  62                                                         efi_root, NULL));
  63 }
  64
  65
  66 /**
  67  * efi_deserialize_load_option() - parse serialized data
  68  *
  69  * Parse serialized data describing a load option and transform it to the
  70  * efi_load_option structure.
  71  *
  72  * @lo:         pointer to target
  73  * @data:       serialized data
  74  * @size:       size of the load option, on return size of the optional data
  75  * Return:      status code
  76  */
  77 efi_status_t efi_deserialize_load_option(struct efi_load_option *lo, u8 *data,
  78                                          efi_uintn_t *size)
  79 {
  80         efi_uintn_t len;
  81
  82         len = sizeof(u32);
  83         if (*size < len + 2 * sizeof(u16))
  84                 return EFI_INVALID_PARAMETER;
  85         lo->attributes = get_unaligned_le32(data);
  86         data += len;
  87         *size -= len;
  88
  89         len = sizeof(u16);
  90         lo->file_path_length = get_unaligned_le16(data);
  91         data += len;
  92         *size -= len;
  93
  94         lo->label = (u16 *)data;
  95         len = u16_strnlen(lo->label, *size / sizeof(u16) - 1);
  96         if (lo->label[len])
  97                 return EFI_INVALID_PARAMETER;
  98         len = (len + 1) * sizeof(u16);
  99         if (*size < len)
 100                 return EFI_INVALID_PARAMETER;
 101         data += len;
 102         *size -= len;
 103
 104         len = lo->file_path_length;
 105         if (*size < len)
 106                 return EFI_INVALID_PARAMETER;
 107         lo->file_path = (struct efi_device_path *)data;
 108         if (efi_dp_check_length(lo->file_path, len) < 0)
 109                 return EFI_INVALID_PARAMETER;
 110         data += len;
 111         *size -= len;
 112
 113         lo->optional_data = data;
 114
 115         return EFI_SUCCESS;
 116 }
 117
 118 /**
 119  * efi_serialize_load_option() - serialize load option
 120  *
 121  * Serialize efi_load_option structure into byte stream for BootXXXX.
 122  *
 123  * @data:       buffer for serialized data
 124  * @lo:         load option
 125  * Return:      size of allocated buffer
 126  */
 127 unsigned long efi_serialize_load_option(struct efi_load_option *lo, u8 **data)
 128 {
 129         unsigned long label_len;
 130         unsigned long size;
 131         u8 *p;
 132
 133         label_len = (u16_strlen(lo->label) + 1) * sizeof(u16);
 134
 135         /* total size */
 136         size = sizeof(lo->attributes);
 137         size += sizeof(lo->file_path_length);
 138         size += label_len;
 139         size += lo->file_path_length;
 140         if (lo->optional_data)
 141                 size += (utf8_utf16_strlen((const char *)lo->optional_data)
 142                                            + 1) * sizeof(u16);
 143         p = malloc(size);
 144         if (!p)
 145                 return 0;
 146
 147         /* copy data */
 148         *data = p;
 149         memcpy(p, &lo->attributes, sizeof(lo->attributes));
 150         p += sizeof(lo->attributes);
 151
 152         memcpy(p, &lo->file_path_length, sizeof(lo->file_path_length));
 153         p += sizeof(lo->file_path_length);
 154
 155         memcpy(p, lo->label, label_len);
 156         p += label_len;
 157
 158         memcpy(p, lo->file_path, lo->file_path_length);
 159         p += lo->file_path_length;
 160
 161         if (lo->optional_data) {
 162                 utf8_utf16_strcpy((u16 **)&p, (const char *)lo->optional_data);
 163                 p += sizeof(u16); /* size of trailing \0 */
 164         }
 165         return size;
 166 }
 167
 168 /**
 169  * get_var() - get UEFI variable
 170  *
 171  * It is the caller's duty to free the returned buffer.
 172  *
 173  * @name:       name of variable
 174  * @vendor:     vendor GUID of variable
 175  * @size:       size of allocated buffer
 176  * Return:      buffer with variable data or NULL
 177  */
 178 static void *get_var(u16 *name, const efi_guid_t *vendor,
 179                      efi_uintn_t *size)
 180 {
 181         efi_status_t ret;
 182         void *buf = NULL;
 183
 184         *size = 0;
 185         ret = efi_get_variable_int(name, vendor, NULL, size, buf, NULL);
 186         if (ret == EFI_BUFFER_TOO_SMALL) {
 187                 buf = malloc(*size);
 188                 ret = efi_get_variable_int(name, vendor, NULL, size, buf, NULL);
 189         }
 190
 191         if (ret != EFI_SUCCESS) {
 192                 free(buf);
 193                 *size = 0;
 194                 return NULL;
 195         }
 196
 197         return buf;
 198 }
 199
 200 /**
 201  * try_load_entry() - try to load image for boot option
 202  *
 203  * Attempt to load load-option number 'n', returning device_path and file_path
 204  * if successful. This checks that the EFI_LOAD_OPTION is active (enabled)
 205  * and that the specified file to boot exists.
 206  *
 207  * @n:                  number of the boot option, e.g. 0x0a13 for Boot0A13
 208  * @handle:             on return handle for the newly installed image
 209  * @load_options:       load options set on the loaded image protocol
 210  * Return:              status code
 211  */
 212 static efi_status_t try_load_entry(u16 n, efi_handle_t *handle,
 213                                    void **load_options)
 214 {
 215         struct efi_load_option lo;
 216         u16 varname[] = L"Boot0000";
 217         u16 hexmap[] = L"0123456789ABCDEF";
 218         void *load_option;
 219         efi_uintn_t size;
 220         efi_status_t ret;
 221
 222         varname[4] = hexmap[(n & 0xf000) >> 12];
 223         varname[5] = hexmap[(n & 0x0f00) >> 8];
 224         varname[6] = hexmap[(n & 0x00f0) >> 4];
 225         varname[7] = hexmap[(n & 0x000f) >> 0];
 226
 227         load_option = get_var(varname, &efi_global_variable_guid, &size);
 228         if (!load_option)
 229                 return EFI_LOAD_ERROR;
 230
 231         ret = efi_deserialize_load_option(&lo, load_option, &size);
 232         if (ret != EFI_SUCCESS) {
 233                 log_warning("Invalid load option for %ls\n", varname);
 234                 goto error;
 235         }
 236
 237         if (lo.attributes & LOAD_OPTION_ACTIVE) {
 238                 u32 attributes;
 239
 240                 log_debug("%s: trying to load \"%ls\" from %pD\n",
 241                           __func__, lo.label, lo.file_path);
 242
 243                 ret = EFI_CALL(efi_load_image(true, efi_root, lo.file_path,
 244                                               NULL, 0, handle));
 245                 if (ret != EFI_SUCCESS) {
 246                         log_warning("Loading %ls '%ls' failed\n",
 247                                     varname, lo.label);
 248                         goto error;
 249                 }
 250
 251                 attributes = EFI_VARIABLE_BOOTSERVICE_ACCESS |
 252                              EFI_VARIABLE_RUNTIME_ACCESS;
 253                 ret = efi_set_variable_int(L"BootCurrent",
 254                                            &efi_global_variable_guid,
 255                                            attributes, sizeof(n), &n, false);
 256                 if (ret != EFI_SUCCESS) {
 257                         if (EFI_CALL(efi_unload_image(*handle))
 258                             != EFI_SUCCESS)
 259                                 log_err("Unloading image failed\n");
 260                         goto error;
 261                 }
 262
 263                 log_info("Booting: %ls\n", lo.label);
 264         } else {
 265                 ret = EFI_LOAD_ERROR;
 266         }
 267
 268         /* Set load options */
 269         if (size) {
 270                 *load_options = malloc(size);
 271                 if (!*load_options) {
 272                         ret = EFI_OUT_OF_RESOURCES;
 273                         goto error;
 274                 }
 275                 memcpy(*load_options, lo.optional_data, size);
 276                 ret = efi_set_load_options(*handle, size, *load_options);
 277         } else {
 278                 load_options = NULL;
 279         }
 280
 281 error:
 282         free(load_option);
 283
 284         return ret;
 285 }
 286
 287 /**
 288  * efi_bootmgr_load() - try to load from BootNext or BootOrder
 289  *
 290  * Attempt to load from BootNext or in the order specified by BootOrder
 291  * EFI variable, the available load-options, finding and returning
 292  * the first one that can be loaded successfully.
 293  *
 294  * @handle:             on return handle for the newly installed image
 295  * @load_options:       load options set on the loaded image protocol
 296  * Return:              status code
 297  */
 298 efi_status_t efi_bootmgr_load(efi_handle_t *handle, void **load_options)
 299 {
 300         u16 bootnext, *bootorder;
 301         efi_uintn_t size;
 302         int i, num;
 303         efi_status_t ret;
 304
 305         bs = systab.boottime;
 306         rs = systab.runtime;
 307
 308         /* BootNext */
 309         size = sizeof(bootnext);
 310         ret = efi_get_variable_int(L"BootNext",
 311                                    &efi_global_variable_guid,
 312                                    NULL, &size, &bootnext, NULL);
 313         if (ret == EFI_SUCCESS || ret == EFI_BUFFER_TOO_SMALL) {
 314                 /* BootNext does exist here */
 315                 if (ret == EFI_BUFFER_TOO_SMALL || size != sizeof(u16))
 316                         log_err("BootNext must be 16-bit integer\n");
 317
 318                 /* delete BootNext */
 319                 ret = efi_set_variable_int(L"BootNext",
 320                                            &efi_global_variable_guid,
 321                                            0, 0, NULL, false);
 322
 323                 /* load BootNext */
 324                 if (ret == EFI_SUCCESS) {
 325                         if (size == sizeof(u16)) {
 326                                 ret = try_load_entry(bootnext, handle,
 327                                                      load_options);
 328                                 if (ret == EFI_SUCCESS)
 329                                         return ret;
 330                                 log_warning(
 331                                         "Loading from BootNext failed, falling back to BootOrder\n");
 332                         }
 333                 } else {
 334                         log_err("Deleting BootNext failed\n");
 335                 }
 336         }
 337
 338         /* BootOrder */
 339         bootorder = get_var(L"BootOrder", &efi_global_variable_guid, &size);
 340         if (!bootorder) {
 341                 log_info("BootOrder not defined\n");
 342                 ret = EFI_NOT_FOUND;
 343                 goto error;
 344         }
 345
 346         num = size / sizeof(uint16_t);
 347         for (i = 0; i < num; i++) {
 348                 log_debug("%s trying to load Boot%04X\n", __func__,
 349                           bootorder[i]);
 350                 ret = try_load_entry(bootorder[i], handle, load_options);
 351                 if (ret == EFI_SUCCESS)
 352                         break;
 353         }
 354
 355         free(bootorder);
 356
 357 error:
 358         return ret;
 359 }