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 #include <common.h>
   9 #include <charset.h>
  10 #include <malloc.h>
  11 #include <efi_loader.h>
  12 #include <asm/unaligned.h>
  13
  14 static const struct efi_boot_services *bs;
  15 static const struct efi_runtime_services *rs;
  16
  17 /*
  18  * bootmgr implements the logic of trying to find a payload to boot
  19  * based on the BootOrder + BootXXXX variables, and then loading it.
  20  *
  21  * TODO detecting a special key held (f9?) and displaying a boot menu
  22  * like you would get on a PC would be clever.
  23  *
  24  * TODO if we had a way to write and persist variables after the OS
  25  * has started, we'd also want to check OsIndications to see if we
  26  * should do normal or recovery boot.
  27  */
  28
  29
  30 /* Parse serialized data and transform it into efi_load_option structure */
  31 void efi_deserialize_load_option(struct efi_load_option *lo, u8 *data)
  32 {
  33         lo->attributes = get_unaligned_le32(data);
  34         data += sizeof(u32);
  35
  36         lo->file_path_length = get_unaligned_le16(data);
  37         data += sizeof(u16);
  38
  39         /* FIXME */
  40         lo->label = (u16 *)data;
  41         data += (u16_strlen(lo->label) + 1) * sizeof(u16);
  42
  43         /* FIXME */
  44         lo->file_path = (struct efi_device_path *)data;
  45         data += lo->file_path_length;
  46
  47         lo->optional_data = data;
  48 }
  49
  50 /*
  51  * Serialize efi_load_option structure into byte stream for BootXXXX.
  52  * Return a size of allocated data.
  53  */
  54 unsigned long efi_serialize_load_option(struct efi_load_option *lo, u8 **data)
  55 {
  56         unsigned long label_len;
  57         unsigned long size;
  58         u8 *p;
  59
  60         label_len = (u16_strlen(lo->label) + 1) * sizeof(u16);
  61
  62         /* total size */
  63         size = sizeof(lo->attributes);
  64         size += sizeof(lo->file_path_length);
  65         size += label_len;
  66         size += lo->file_path_length;
  67         if (lo->optional_data)
  68                 size += (utf8_utf16_strlen((const char *)lo->optional_data)
  69                                            + 1) * sizeof(u16);
  70         p = malloc(size);
  71         if (!p)
  72                 return 0;
  73
  74         /* copy data */
  75         *data = p;
  76         memcpy(p, &lo->attributes, sizeof(lo->attributes));
  77         p += sizeof(lo->attributes);
  78
  79         memcpy(p, &lo->file_path_length, sizeof(lo->file_path_length));
  80         p += sizeof(lo->file_path_length);
  81
  82         memcpy(p, lo->label, label_len);
  83         p += label_len;
  84
  85         memcpy(p, lo->file_path, lo->file_path_length);
  86         p += lo->file_path_length;
  87
  88         if (lo->optional_data) {
  89                 utf8_utf16_strcpy((u16 **)&p, (const char *)lo->optional_data);
  90                 p += sizeof(u16); /* size of trailing \0 */
  91         }
  92         return size;
  93 }
  94
  95 /* free() the result */
  96 static void *get_var(u16 *name, const efi_guid_t *vendor,
  97                      efi_uintn_t *size)
  98 {
  99         efi_guid_t *v = (efi_guid_t *)vendor;
 100         efi_status_t ret;
 101         void *buf = NULL;
 102
 103         *size = 0;
 104         EFI_CALL(ret = rs->get_variable(name, v, NULL, size, buf));
 105         if (ret == EFI_BUFFER_TOO_SMALL) {
 106                 buf = malloc(*size);
 107                 EFI_CALL(ret = rs->get_variable(name, v, NULL, size, buf));
 108         }
 109
 110         if (ret != EFI_SUCCESS) {
 111                 free(buf);
 112                 *size = 0;
 113                 return NULL;
 114         }
 115
 116         return buf;
 117 }
 118
 119 /*
 120  * Attempt to load load-option number 'n', returning device_path and file_path
 121  * if successful.  This checks that the EFI_LOAD_OPTION is active (enabled)
 122  * and that the specified file to boot exists.
 123  */
 124 static efi_status_t try_load_entry(u16 n, efi_handle_t *handle)
 125 {
 126         struct efi_load_option lo;
 127         u16 varname[] = L"Boot0000";
 128         u16 hexmap[] = L"0123456789ABCDEF";
 129         void *load_option;
 130         efi_uintn_t size;
 131         efi_status_t ret;
 132
 133         varname[4] = hexmap[(n & 0xf000) >> 12];
 134         varname[5] = hexmap[(n & 0x0f00) >> 8];
 135         varname[6] = hexmap[(n & 0x00f0) >> 4];
 136         varname[7] = hexmap[(n & 0x000f) >> 0];
 137
 138         load_option = get_var(varname, &efi_global_variable_guid, &size);
 139         if (!load_option)
 140                 return EFI_LOAD_ERROR;
 141
 142         efi_deserialize_load_option(&lo, load_option);
 143
 144         if (lo.attributes & LOAD_OPTION_ACTIVE) {
 145                 u32 attributes;
 146
 147                 debug("%s: trying to load \"%ls\" from %pD\n",
 148                       __func__, lo.label, lo.file_path);
 149
 150                 ret = EFI_CALL(efi_load_image(true, efi_root, lo.file_path,
 151                                               NULL, 0, handle));
 152                 if (ret != EFI_SUCCESS) {
 153                         printf("Loading from Boot%04X '%ls' failed\n", n,
 154                                lo.label);
 155                         goto error;
 156                 }
 157
 158                 attributes = EFI_VARIABLE_BOOTSERVICE_ACCESS |
 159                              EFI_VARIABLE_RUNTIME_ACCESS;
 160                 size = sizeof(n);
 161                 ret = EFI_CALL(efi_set_variable(
 162                                 L"BootCurrent",
 163                                 (efi_guid_t *)&efi_global_variable_guid,
 164                                 attributes, size, &n));
 165                 if (ret != EFI_SUCCESS) {
 166                         if (EFI_CALL(efi_unload_image(*handle))
 167                             != EFI_SUCCESS)
 168                                 printf("Unloading image failed\n");
 169                         goto error;
 170                 }
 171
 172                 printf("Booting: %ls\n", lo.label);
 173         } else {
 174                 ret = EFI_LOAD_ERROR;
 175         }
 176
 177 error:
 178         free(load_option);
 179
 180         return ret;
 181 }
 182
 183 /*
 184  * Attempt to load from BootNext or in the order specified by BootOrder
 185  * EFI variable, the available load-options, finding and returning
 186  * the first one that can be loaded successfully.
 187  */
 188 efi_status_t efi_bootmgr_load(efi_handle_t *handle)
 189 {
 190         u16 bootnext, *bootorder;
 191         efi_uintn_t size;
 192         int i, num;
 193         efi_status_t ret;
 194
 195         bs = systab.boottime;
 196         rs = systab.runtime;
 197
 198         /* BootNext */
 199         bootnext = 0;
 200         size = sizeof(bootnext);
 201         ret = EFI_CALL(efi_get_variable(L"BootNext",
 202                                         (efi_guid_t *)&efi_global_variable_guid,
 203                                         NULL, &size, &bootnext));
 204         if (ret == EFI_SUCCESS || ret == EFI_BUFFER_TOO_SMALL) {
 205                 /* BootNext does exist here */
 206                 if (ret == EFI_BUFFER_TOO_SMALL || size != sizeof(u16))
 207                         printf("BootNext must be 16-bit integer\n");
 208
 209                 /* delete BootNext */
 210                 ret = EFI_CALL(efi_set_variable(
 211                                         L"BootNext",
 212                                         (efi_guid_t *)&efi_global_variable_guid,
 213                                         EFI_VARIABLE_NON_VOLATILE, 0,
 214                                         &bootnext));
 215
 216                 /* load BootNext */
 217                 if (ret == EFI_SUCCESS) {
 218                         if (size == sizeof(u16)) {
 219                                 ret = try_load_entry(bootnext, handle);
 220                                 if (ret == EFI_SUCCESS)
 221                                         return ret;
 222                                 printf("Loading from BootNext failed, falling back to BootOrder\n");
 223                         }
 224                 } else {
 225                         printf("Deleting BootNext failed\n");
 226                 }
 227         }
 228
 229         /* BootOrder */
 230         bootorder = get_var(L"BootOrder", &efi_global_variable_guid, &size);
 231         if (!bootorder) {
 232                 printf("BootOrder not defined\n");
 233                 ret = EFI_NOT_FOUND;
 234                 goto error;
 235         }
 236
 237         num = size / sizeof(uint16_t);
 238         for (i = 0; i < num; i++) {
 239                 debug("%s: trying to load Boot%04X\n", __func__, bootorder[i]);
 240                 ret = try_load_entry(bootorder[i], handle);
 241                 if (ret == EFI_SUCCESS)
 242                         break;
 243         }
 244
 245         free(bootorder);
 246
 247 error:
 248         return ret;
 249 }