From a9bccd374d23f67d2c3604f7c069be40ec996f9f Mon Sep 17 00:00:00 2001 From: Lans Zhang Date: Thu, 22 Jun 2017 15:22:01 +0800 Subject: [PATCH] Add a module for reading EFI global variables Add functions to read EFI global variables. Signed-off-by: Lans Zhang [lz: Add git log.] Signed-off-by: Li Zhou --- grub-core/Makefile.core.def | 8 ++ grub-core/commands/efi/efivar.c | 238 ++++++++++++++++++++++++++++++++ 2 files changed, 246 insertions(+) create mode 100644 grub-core/commands/efi/efivar.c diff --git a/grub-core/Makefile.core.def b/grub-core/Makefile.core.def index 8022e1c..f8fad6e 100644 --- a/grub-core/Makefile.core.def +++ b/grub-core/Makefile.core.def @@ -761,6 +761,14 @@ module = { enable = i386_multiboot; }; +module = { + name = efivar; + + common = commands/efi/efivar.c; + + enable = efi; +}; + module = { name = lsacpi; diff --git a/grub-core/commands/efi/efivar.c b/grub-core/commands/efi/efivar.c new file mode 100644 index 0000000..bb9aed3 --- /dev/null +++ b/grub-core/commands/efi/efivar.c @@ -0,0 +1,238 @@ +/* efivar.c - Read EFI global variables. */ +/* + * GRUB -- GRand Unified Bootloader + * Copyright (C) 2015 Free Software Foundation, Inc. + * Copyright (C) 2015 CloudFlare, Inc. + * + * GRUB is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * GRUB is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with GRUB. If not, see . + */ + +#include +#include +#include +#include +#include +#include +#include +#include + +GRUB_MOD_LICENSE ("GPLv3+"); + +static const struct grub_arg_option options[] = { + {"format", 'f', GRUB_ARG_OPTION_OPTIONAL, N_("Parse EFI_VAR in specific format (hex, uint8, ascii, dump). Default: hex."), N_("FORMAT"), ARG_TYPE_STRING}, + {"set", 's', GRUB_ARG_OPTION_OPTIONAL, N_("Save parsed result to environment variable (does not work with dump)."), N_("ENV_VAR"), ARG_TYPE_STRING}, + {0, 0, 0, 0, 0, 0} +}; + +enum efi_var_type + { + EFI_VAR_ASCII = 0, + EFI_VAR_UINT8, + EFI_VAR_HEX, + EFI_VAR_DUMP, + EFI_VAR_INVALID = -1 + }; + +static enum efi_var_type +parse_efi_var_type (const char *type) +{ + if (!grub_strncmp (type, "ascii", sizeof("ascii"))) + return EFI_VAR_ASCII; + + if (!grub_strncmp (type, "uint8", sizeof("uint8"))) + return EFI_VAR_UINT8; + + if (!grub_strncmp (type, "hex", sizeof("hex"))) + return EFI_VAR_HEX; + + if (!grub_strncmp (type, "dump", sizeof("dump"))) + return EFI_VAR_DUMP; + + return EFI_VAR_INVALID; +} + +static int +grub_print_ascii (char *str, char c) +{ + if (grub_iscntrl (c)) + { + switch (c) + { + case '\0': + str[0] = '\\'; + str[1] = '0'; + return 2; + + case '\a': + str[0] = '\\'; + str[1] = 'a'; + return 2; + + case '\b': + str[0] = '\\'; + str[1] = 'b'; + return 2; + + case '\f': + str[0] = '\\'; + str[1] = 'f'; + return 2; + + case '\n': + str[0] = '\\'; + str[1] = 'n'; + return 2; + + case '\r': + str[0] = '\\'; + str[1] = 'r'; + return 2; + + case '\t': + str[0] = '\\'; + str[1] = 't'; + return 2; + + case '\v': + str[0] = '\\'; + str[1] = 'v'; + return 2; + + default: + str[0] = '.'; /* as in hexdump -C */ + return 1; + } + } + + str[0] = c; + return 1; +} + +static grub_err_t +grub_cmd_get_efi_var (struct grub_extcmd_context *ctxt, + int argc, char **args) +{ + struct grub_arg_list *state = ctxt->state; + grub_err_t status; + void *efi_var = NULL; + grub_size_t efi_var_size = 0; + enum efi_var_type efi_type = EFI_VAR_HEX; + grub_efi_guid_t global = GRUB_EFI_GLOBAL_VARIABLE_GUID; + char *env_var = NULL; + grub_size_t i; + char *ptr; + + if (1 != argc) + return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("one argument expected")); + + if (state[0].set) + efi_type = parse_efi_var_type (state[0].arg); + + if (EFI_VAR_INVALID == efi_type) + return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("invalid format specifier")); + + grub_efi_get_variable (args[0], &global, &efi_var_size, &efi_var); + if (!efi_var || !efi_var_size) + { + status = grub_error (GRUB_ERR_READ_ERROR, N_("cannot read variable")); + goto err; + } + + switch (efi_type) + { + case EFI_VAR_ASCII: + env_var = grub_malloc (efi_var_size * 2 + 1); + if (!env_var) + { + status = grub_error (GRUB_ERR_OUT_OF_MEMORY, N_("out of memory")); + break; + } + + ptr = env_var; + + for (i = 0; i < efi_var_size; i++) + ptr += grub_print_ascii (ptr, ((const char *)efi_var)[i]); + *ptr = '\0'; + break; + + case EFI_VAR_UINT8: + env_var = grub_malloc (4); + if (!env_var) + { + status = grub_error (GRUB_ERR_OUT_OF_MEMORY, N_("out of memory")); + break; + } + grub_snprintf (env_var, 4, "%u", *((grub_uint8_t *)efi_var)); + break; + + case EFI_VAR_HEX: + env_var = grub_malloc (efi_var_size * 2 + 1); + if (!env_var) + { + status = grub_error (GRUB_ERR_OUT_OF_MEMORY, N_("out of memory")); + break; + } + for (i = 0; i < efi_var_size; i++) + grub_snprintf (env_var + (i * 2), 3, "%02x", ((grub_uint8_t *)efi_var)[i]); + break; + + case EFI_VAR_DUMP: + if (state[1].set) + status = grub_error (GRUB_ERR_BAD_ARGUMENT, N_("cannot set variable with dump format specifier")); + else + { + hexdump (0, (char *)efi_var, efi_var_size); + status = GRUB_ERR_NONE; + } + break; + + default: + status = grub_error (GRUB_ERR_BUG, N_("should not happen (bug in module?)")); + } + + if (efi_type != EFI_VAR_DUMP) + { + if (state[1].set) + status = grub_env_set (state[1].arg, env_var); + else + { + grub_printf ("%s\n", (const char *)env_var); + status = GRUB_ERR_NONE; + } + } + +err: + + if (env_var) + grub_free (env_var); + + if (efi_var) + grub_free (efi_var); + + return status; +} + +static grub_extcmd_t cmd = NULL; + +GRUB_MOD_INIT (efivar) +{ + cmd = grub_register_extcmd ("get_efivar", grub_cmd_get_efi_var, 0, N_("[-f FORMAT] [-s ENV_VAR] EFI_VAR"), + N_("Read EFI variable and print it or save its contents to environment variable."), options); +} + +GRUB_MOD_FINI (efivar) +{ + if (cmd) + grub_unregister_extcmd (cmd); +} -- 2.17.1