diff options
Diffstat (limited to 'fallback.c')
| -rw-r--r-- | fallback.c | 125 |
1 files changed, 118 insertions, 7 deletions
@@ -12,6 +12,7 @@ #include "ucs2.h" #include "variables.h" +#include "tpm.h" EFI_LOADED_IMAGE *this_image = NULL; @@ -286,6 +287,105 @@ add_boot_option(EFI_DEVICE_PATH *hddp, EFI_DEVICE_PATH *fulldp, return EFI_OUT_OF_RESOURCES; } +/* + * AMI BIOS (e.g, Intel NUC5i3MYHE) may automatically hide and patch BootXXXX + * variables with ami_masked_device_path_guid. We can get the valid device path + * if just skipping it and its next end path. + */ + +static EFI_GUID ami_masked_device_path_guid = { + 0x99e275e7, 0x75a0, 0x4b37, + { 0xa2, 0xe6, 0xc5, 0x38, 0x5e, 0x6c, 0x0, 0xcb } +}; + +static unsigned int +calc_masked_boot_option_size(unsigned int size) +{ + return size + sizeof(EFI_DEVICE_PATH) + + sizeof(ami_masked_device_path_guid) + sizeof(EFI_DEVICE_PATH); +} + +static int +check_masked_boot_option(CHAR8 *candidate, unsigned int candidate_size, + CHAR8 *data, unsigned int data_size) +{ + /* + * The patched BootXXXX variables contain a hardware device path and + * an end path, preceding the real device path. + */ + if (calc_masked_boot_option_size(data_size) != candidate_size) + return 1; + + CHAR8 *cursor = candidate; + + /* Check whether the BootXXXX is patched */ + cursor += sizeof(UINT32) + sizeof(UINT16); + cursor += StrSize((CHAR16 *)cursor); + + unsigned int min_valid_size = cursor - candidate + sizeof(EFI_DEVICE_PATH); + + if (candidate_size <= min_valid_size) + return 1; + + EFI_DEVICE_PATH *dp = (EFI_DEVICE_PATH *)cursor; + unsigned int node_size = DevicePathNodeLength(dp) - sizeof(EFI_DEVICE_PATH); + + min_valid_size += node_size; + if (candidate_size <= min_valid_size || + DevicePathType(dp) != HARDWARE_DEVICE_PATH || + DevicePathSubType(dp) != HW_VENDOR_DP || + node_size != sizeof(ami_masked_device_path_guid) || + CompareGuid((EFI_GUID *)(cursor + sizeof(EFI_DEVICE_PATH)), + &ami_masked_device_path_guid)) + return 1; + + /* Check whether the patched guid is followed by an end path */ + min_valid_size += sizeof(EFI_DEVICE_PATH); + if (candidate_size <= min_valid_size) + return 1; + + dp = NextDevicePathNode(dp); + if (!IsDevicePathEnd(dp)) + return 1; + + /* + * OK. We may really get a masked BootXXXX variable. The next + * step is to test whether it is hidden. + */ + UINT32 attrs = *(UINT32 *)candidate; +#ifndef LOAD_OPTION_HIDDEN +# define LOAD_OPTION_HIDDEN 0x00000008 +#endif + if (!(attrs & LOAD_OPTION_HIDDEN)) + return 1; + + attrs &= ~LOAD_OPTION_HIDDEN; + + /* Compare the field Attributes */ + if (attrs != *(UINT32 *)data) + return 1; + + /* Compare the field FilePathListLength */ + data += sizeof(UINT32); + candidate += sizeof(UINT32); + if (calc_masked_boot_option_size(*(UINT16 *)data) != + *(UINT16 *)candidate) + return 1; + + /* Compare the field Description */ + data += sizeof(UINT16); + candidate += sizeof(UINT16); + if (CompareMem(candidate, data, cursor - candidate)) + return 1; + + /* Compare the filed FilePathList */ + cursor = (CHAR8 *)NextDevicePathNode(dp); + data += sizeof(UINT16); + data += StrSize((CHAR16 *)data); + + return CompareMem(cursor, data, candidate_size - min_valid_size); +} + EFI_STATUS find_boot_option(EFI_DEVICE_PATH *dp, EFI_DEVICE_PATH *fulldp, CHAR16 *filename, CHAR16 *label, CHAR16 *arguments, @@ -315,7 +415,8 @@ find_boot_option(EFI_DEVICE_PATH *dp, EFI_DEVICE_PATH *fulldp, EFI_GUID global = EFI_GLOBAL_VARIABLE; EFI_STATUS rc; - CHAR8 *candidate = AllocateZeroPool(size); + UINTN max_candidate_size = calc_masked_boot_option_size(size); + CHAR8 *candidate = AllocateZeroPool(max_candidate_size); if (!candidate) { FreePool(data); return EFI_OUT_OF_RESOURCES; @@ -327,17 +428,21 @@ find_boot_option(EFI_DEVICE_PATH *dp, EFI_DEVICE_PATH *fulldp, varname[6] = hexmap[(bootorder[i] & 0x00f0) >> 4]; varname[7] = hexmap[(bootorder[i] & 0x000f) >> 0]; - UINTN candidate_size = size; + UINTN candidate_size = max_candidate_size; rc = uefi_call_wrapper(RT->GetVariable, 5, varname, &global, NULL, &candidate_size, candidate); if (EFI_ERROR(rc)) continue; - if (candidate_size != size) + if (candidate_size != size) { + if (check_masked_boot_option(candidate, candidate_size, + data, size)) + continue; + } else if (CompareMem(candidate, data, size)) continue; - if (CompareMem(candidate, data, size)) - continue; + VerbosePrint(L"Found boot entry \"%s\" with label \"%s\" " + L"for file \"%s\"\n", varname, label, filename); /* at this point, we have duplicate data. */ if (!first_new_option) { @@ -481,7 +586,7 @@ add_to_boot_list(CHAR16 *dirname, CHAR16 *filename, CHAR16 *label, CHAR16 *argum err: if (full_device_path) FreePool(full_device_path); - if (dp) + if (dp && dp != full_device_path) FreePool(dp); if (fullpath) FreePool(fullpath); @@ -904,7 +1009,13 @@ efi_main(EFI_HANDLE image, EFI_SYSTEM_TABLE *systab) return rc; } - try_start_first_option(image); + rc = fallback_should_prefer_reset(); + if (EFI_ERROR(rc)) { + VerbosePrint(L"tpm not present, starting the first image\n"); + try_start_first_option(image); + } else { + VerbosePrint(L"tpm present, resetting system\n"); + } Print(L"Reset System\n"); |