[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: Grub get and set efi variables
From: |
Andrei Borzenkov |
Subject: |
Re: Grub get and set efi variables |
Date: |
Sun, 29 Nov 2015 11:57:09 +0300 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 |
17.11.2015 14:48, Ignat Korchagin пишет:
> Please, see updated patch below. I tried to reuse GRUB hexdump
> function, so as a result dump will not work with setting vatiables -
> just dumping to stdout. But it doesn't make sense to assign dump to a
> variable anyway.
>
> diff --git a/grub-core/commands/efi/efivar.c b/grub-core/commands/efi/efivar.c
> new file mode 100644
> index 0000000..3ffd5ca
> --- /dev/null
> +++ b/grub-core/commands/efi/efivar.c
> @@ -0,0 +1,253 @@
> +/* 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 <http://www.gnu.org/licenses/>.
> + */
> +
> +#include <grub/types.h>
> +#include <grub/mm.h>
> +#include <grub/misc.h>
> +#include <grub/efi/api.h>
> +#include <grub/efi/efi.h>
> +#include <grub/extcmd.h>
> +#include <grub/env.h>
> +#include <grub/lib/hexdump.h>
> +
> +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, raw, 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_RAW,
> + 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, "raw", sizeof("raw")))
> + 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;
> +
Should not this be strcmp, not str*n*cmp?
> + 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_("two arguments expected"));
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"));
> +
> + efi_var = grub_efi_get_variable (args[0], &global, &efi_var_size);
> + 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_RAW:
> + env_var = grub_malloc (efi_var_size + 1);
> + if (!env_var)
> + {
> + status = grub_error (GRUB_ERR_OUT_OF_MEMORY, N_("out of memory"));
> + break;
> + }
> + grub_memcpy (env_var, efi_var, efi_var_size);
> + env_var[efi_var_size] = '\0';
That would be wrong ("raw" implies no modification) but I am not keen on
keeping "raw" as was discussed.
> + 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);
> +}
> diff --git a/grub-core/Makefile.core.def b/grub-core/Makefile.core.def
> index a6101de..2c8f023 100644
> --- a/grub-core/Makefile.core.def
> +++ b/grub-core/Makefile.core.def
> @@ -728,6 +728,12 @@
> };
>
> module = {
> + name = efivar;
> + efi = commands/efi/efivar.c;
> + enable = efi;
> +};
> +
> +module = {
> name = blocklist;
> common = commands/blocklist.c;
> };
>
> On Sat, Nov 14, 2015 at 4:03 AM, Andrei Borzenkov <address@hidden> wrote:
>> 13.11.2015 22:42, Ignat Korchagin пишет:
>>>>>>
>>>>>> +static enum efi_var_type
>>>>>> +parse_efi_var_type (const char *type)
>>>>>> +{
>>>>>> + if (!grub_strncmp (type, "string", sizeof("string")))
>>>>>> + return EFI_VAR_STRING;
>>>>>> +
>>>>>
>>>>>
>>>>>
>>>>> I think this should be "ascii" or "utf8". "string" is too ambiguous in
>>>>> UEFI
>>>>> environment, it can also mean sequence of UCS-2 characters.
>>>>
>>>> I'm still not sure how exactly GRUB + UEFI interprets "raw buffers"
>>>> when printing. Maybe, to avoid confusion, it might be better to
>>>> completely remove this option. Basically, you do not want to interpret
>>>> raw buffers as strings. For best compatibility "hex" mode should be
>>>> promoted, I guess. What do you think?
>>>
>>> Checked again the UEFI spec. For globally defined variables which are
>>> strings they specify ASCII. So if we leave this option, ascii is the
>>> best name.
>>>
>>
>> What about
>>
>> - ascii - print ASCII characters verbatim, escape non-ASCII in usual way
>> (similar to "od -c")
>>
>> - raw - simply put raw variable without any interpretation.
>>
>> This is better aligned with argument describing output formatting rather
>> than attempting to "type" variable.
>>
>> Alternative (or in addition to) ascii - dump which prints usual pretty hex
>> dump of content (hexdump -C). This is handy to interactively look at
>> variable content.
>>
>> Or, and change name from --type to --format :)
>>
>>
>> _______________________________________________
>> Grub-devel mailing list
>> address@hidden
>> https://lists.gnu.org/mailman/listinfo/grub-devel
>
> _______________________________________________
> Grub-devel mailing list
> address@hidden
> https://lists.gnu.org/mailman/listinfo/grub-devel
>
- Re: Grub get and set efi variables, (continued)
- Re: Grub get and set efi variables, SevenBits, 2015/11/03
- Re: Grub get and set efi variables, Mat Troi, 2015/11/03
- Re: Grub get and set efi variables, Andrei Borzenkov, 2015/11/04
- Re: Grub get and set efi variables, SevenBits, 2015/11/05
- Re: Grub get and set efi variables, Ignat Korchagin, 2015/11/05
- Re: Grub get and set efi variables, Andrei Borzenkov, 2015/11/11
- Re: Grub get and set efi variables, Ignat Korchagin, 2015/11/13
- Re: Grub get and set efi variables, Ignat Korchagin, 2015/11/13
- Re: Grub get and set efi variables, Andrei Borzenkov, 2015/11/13
- Re: Grub get and set efi variables, Ignat Korchagin, 2015/11/17
- Re: Grub get and set efi variables,
Andrei Borzenkov <=
- Re: Grub get and set efi variables, Mat Troi, 2015/11/24
- Re: Grub get and set efi variables, Seth Goldberg, 2015/11/24
- Re: Grub get and set efi variables, Vladimir 'φ-coder/phcoder' Serbinenko, 2015/11/27
- Re: Grub get and set efi variables, Ignat Korchagin, 2015/11/27
- Re: Grub get and set efi variables, Andrei Borzenkov, 2015/11/29