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Re: [PATCH 2/2] core: commands: efi: add commands to get/set EFI vars
|
From: |
Glenn Washburn |
|
Subject: |
Re: [PATCH 2/2] core: commands: efi: add commands to get/set EFI vars |
|
Date: |
Mon, 29 Aug 2022 00:28:30 -0500 |
On Wed, 29 Apr 2020 16:54:10 +0200
Flavio Suligoi <f.suligoi@asem.it> wrote:
> Sometimes, using a GRUB boot script (i.e. grub.cfg), it is very important
> to get/set an EFI variable, especially in embedded systems, to detect
> some custom BIOS features.
> For example, based on the content of some EFI variables, a script can decide
> to boot a special kernel instead of the usual kernel, or add some custom boot
> parameters to the kernel command line, etc.
>
> This patch add two useful commands:
>
> - efivar_get
> - efivar_set
>
> to get/set an EFI variable.
>
> The "get" function can display the EFI variable in ASCII or in HEX+ASCII
> mode (like the Linux command "hexdump"), while the "set" function can set the
> EFI variable in ASCII mode only.
>
> As GUID, the default GUID used is the standard EFI_GLOBAL_VARIABLE_GUID,
> but it is possible to use any other GUID (standard or custom) using an
> environment variable.
>
> Example: set the EFI variable "Configuration"" to the ASCII value
> ‘Board_special
> version 1.0.0’, with the following custom GUID:
>
> ‘Configuration-a87cb185-864c-4683-a93e-3666ad3cf6b6’
>
> grub> set guid_used=a87cb185-864c-4683-a93e-3666ad3cf6b6
> grub>
> grub> efivar_set -g guid_used Configuration "Board_special version 1.0.0"
I think it makes more sense for -g to take the literal guid as the
argument. So instead the above line would be:
efivar_set -g ${guid_used} Configuration "Board_special version 1.0.0"
> grub>
> grub> efivar_get -g guid_used -xv Configuration
> Configuration-a87cb185-864c-4683-a93e-3666ad3cf6b6 :
>
> 0000 - 42 6f 61 72 64 5f 73 70 65 63 69 61 6c 20 76 65 |Board_special ve|
> 0010 - 72 73 69 6f 6e 20 31 2e 30 2e 30 00 |rsion 1.0.0. |
>
> -----
> Usage
> -----
>
> Usage: efivar_get [OPTIONS] VAR
>
> Read EFI VAR variable (if not specified, use EFI_GLOBAL_VARIABLE_GUID as
> default GUID: {8be4df61-93ca-11d2-aa0d-00e098032b8c}).
> If --set is specified, the version is set to a variable.
>
> -s, --set=VARNAME Assign return value to variable VARNAME.
> -g, --guid-var=GUIDVARNAME Use the content of GUIDVARNAME as GUID
Per comment above, just use --guid=GUID and change the description
> -x, --hexdump Display EFI variable content in hex mode
> -v, --verbose Display more info about EFI variable.
> -h, --help Display this help and exit.
> -u, --usage Display the usage of this command and exit.
>
> Usage: efivar_set [OPTIONS] VAR VALUE
>
> Write VALUE to EFI variable VAR (if not specified, use
> EFI_GLOBAL_VARIABLE_GUID
> as default GUID:{8be4df61-93ca-11d2-aa0d-00e098032b8c}).
> If --set is specified, the same EFI variable value is set to a variable.
> If --non-volatile is specified, the non-volatile EFI attribute is set.
>
> Note: an existing EFI variable can be changed only maintainig the same
> volatile/non-volatile attribute.
>
> -s, --set=VARNAME Assign the same EFI variable value to variable
> VARNAME.
> -g, --guid-var=GUIDVARNAME Use the content of GUIDVARNAME as GUID
> -n, --non-volatile Set non-volatile attribute.
> -v, --verbose Display more info about EFI variable
> -h, --help Display this help and exit.
> -u, --usage Display the usage of this command and exit.
>
> Signed-off-by: Flavio Suligoi <f.suligoi@asem.it>
> ---
> docs/grub.texi | 137 +++++++++++++++
> grub-core/Makefile.core.def | 5 +
> grub-core/commands/efi/efivar_get_set.c | 288
> ++++++++++++++++++++++++++++++++
> grub-core/kern/efi/efi.c | 57 +++++++
> include/grub/efi/efi.h | 4 +
> 5 files changed, 491 insertions(+)
> create mode 100644 grub-core/commands/efi/efivar_get_set.c
>
> diff --git a/docs/grub.texi b/docs/grub.texi
> index d6408d2..ee59079 100644
> --- a/docs/grub.texi
> +++ b/docs/grub.texi
> @@ -3978,6 +3978,8 @@ you forget a command, you can run the command
> @command{help}
> * distrust:: Remove a pubkey from trusted keys
> * drivemap:: Map a drive to another
> * echo:: Display a line of text
> +* efivar_get:: Get EFI variable
> +* efivar_set:: Set EFI variable
> * eval:: Evaluate agruments as GRUB commands
> * export:: Export an environment variable
> * false:: Do nothing, unsuccessfully
> @@ -4397,6 +4399,141 @@ character will print that character.
> @end deffn
>
>
> +@node efivar_get
> +@subsection efivar_get
> +@deffn Command efivar_get [@option{--set} var] [@option{--guid-var}
> guidvarname] [@option{--hexdump}] [@option{--verbose}] efivar
> +Get and display an EFI variable @var{efivar} in ASCII or hex+ASCII format.
> +
> +The EFI GUID can be loaded from an environment variable, using the option
> +@option{--guid-var @var{guidvarname}}. If this option is not used and
> +consequently no GUID is specified, the GUID:
> +
> +
> +@center EFI_GLOBAL_VARIABLE_GUID = 8be4df61-93ca-11d2-aa0d-00e098032b8c
> +
> +is implicitly assumed.
> +
> +If the option @option{--set @var{var}} is specified, store the EFI variable
> to
> +the environment variable @var{var} instead of printing it.
> +
> +If the option @option{--hexdump} is specified, the output is in hexdecimal
> +format.
> +
> +The option @option{--verbose} improve the data information output.
> +
> +@emph{Example:} read the EFI variable:
> +
> +@center @samp{PlatformInfo-19ad5244-fd6b-4e5c-826a-414646d6da6a}
> +
> +@smallexample
> +grub> set guid_used=19ad5244-fd6b-4e5c-826a-414646d6da6a
> +grub> efivar_get -g guid_used -xv PlatformInfo
> +PlatformInfo-19ad5244-fd6b-4e5c-826a-414646d6da6a :
> +
> +0000 - 00 00 e2 00 00 00 00 00 00 00 00 00 f0 5a 0d 00 |.............Z..|
> +0010 - 00 00 00 00 00 00 00 00 00 a8 ff ff ff df 00 00 |................|
> +0020 - 00 00 0f 00 00 00 ff ff ff ff 0f 00 00 00 00 00 |................|
> +0030 - 00 e0 00 00 00 00 00 00 00 04 00 01 24 00 00 00 |............$...|
> +0040 - 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
> +0050 - 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
> +0060 - 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
> +0070 - 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
> +0080 - 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
> +0090 - 00 00 00 00 00 00 00 00 00 00 00 00 00 00 a8 00 |................|
> +00a0 - 00 00 a8 00 00 00 00 00 00 c0 a0 ef 7a 00 80 01 |............z...|
> +00b0 - 00 00 00 f9 ff ff 8b 0d 9c f9 ff ff c1 e9 02 00 |................|
> +00c0 - 00 00 00 0f 00 00 00 00 00 00 00 10 00 00 00 d0 |................|
> +00d0 - e6 80 eb 80 05 01 00 00 00 00 00 00 00 00 00 00 |................|
> +00e0 - 00 00 00 00 00 00 00 00 01 86 80 34 12 00 00 49 |...........4...I|
> +00f0 - 4e 54 45 4c 20 20 20 45 44 4b 32 20 20 20 20 00 |NTEL EDK2 .|
> +0100 - 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
> +0110 - 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
> +0120 - 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
> +0130 - 00 00 00 00 00 00 00 00 00 00 30 32 b7 7a c8 3a |..........02.z.:|
> +0140 - b7 7a b0 34 b7 7a 88 3e b7 7a 00 00 00 00 00 00 |.z.4.z.>.z......|
> +0150 - 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
> +0160 - 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
> +0170 - 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
> +0180 - 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
> +0190 - 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
> +01a0 - 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
> +01b0 - 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
> +01c0 - 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
> +01d0 - 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
> +01e0 - 00 00 00 00 00 00 00 00 00 fc 8b 3d 98 |...........=. |
> +grub>
> +@end smallexample
> +
> +
> +@emph{Note:} in Linux, the dump of any EFI var in
> +@file{/sys/firmware/efi/efivars} shows, before the variable data, also the
> +4 bytes of the variable attributes. In GRUB, instead, a dump of any EFI
> variable
> +shows the variable data only.
> +
> +@end deffn
> +
> +
> +@node efivar_set
> +@subsection efivar_set
> +@deffn Command efivar_set [@option{--set} var] [@option{--guid-var}
> guidvarname] [@option{--non-volatile}] [@option{--verbose}] efivar value
> +Set an EFI variable @var{efivar} with the value @var{value} in ASCII format.
> +
> +The EFI GUID can be loaded from an environment variable, using the option
> +@option{--guid-var @var{guidvarname}}. If this option is not used and
> consequently
> +no GUID is specified, the GUID:
> +
> +
> +@center EFI_GLOBAL_VARIABLE_GUID = 8be4df61-93ca-11d2-aa0d-00e098032b8c
> +
> +is implicitly assumed.
> +
> +About the EFI variable attributes, the following attributes are set:
> +@itemize @bullet
> +@item
> +GRUB_EFI_VARIABLE_BOOTSERVICE_ACCESS
> +@item
> +GRUB_EFI_VARIABLE_RUNTIME_ACCESS
> +@end itemize
> +If the option @option{--non-volatile} is give, the variable is also set with
> +the attribute:
> +@itemize @bullet
> +@item
> +GRUB_EFI_VARIABLE_NON_VOLATILE
> +@end itemize
> +In this way the variable will be stored in the board NVRAM.
s/./ and preserved across reboots./
> +
> +If the option @option{--set @var{var}} is specified, in addition to set the
> EFI
> +variable with the value @var{value}, also store this value to the environment
> +variable @var{var}.
> +
> +The option @option{--verbose} improve the data information output.
> +
> +@emph{Example:} set the EFI variable @var{Configuration} to the ASCII value
> +@samp{Board_special version 1.0.0}, with the following
> +custom GUID:
> +
> +@center @samp{Configuration-a87cb185-864c-4683-a93e-3666ad3cf6b6}
> +
> +@smallexample
> +grub> set guid_used=a87cb185-864c-4683-a93e-3666ad3cf6b6
> +grub> efivar_set -g guid_used Configuration "Board_special version 1.0.0"
> +grub> efivar_get -g guid_used -xv Configuration
> +Configuration-a87cb185-864c-4683-a93e-3666ad3cf6b6 :
> +
> +0000 - 42 6f 61 72 64 5f 73 70 65 63 69 61 6c 20 76 65 |Board_special ve|
> +0010 - 72 73 69 6f 6e 20 31 2e 30 2e 30 00 |rsion 1.0.0. |
> +grub>
> +@end smallexample
> +
> +
> +@emph{Note:} in Linux, the dump of any EFI var in
> +@file{/sys/firmware/efi/efivars} shows, before the variable data, also the
> +4 bytes of the variable attributes. In GRUB, instead, a dump of any EFI
> variable
> +shows the variable data only.
> +
> +@end deffn
> +
> +
> @node eval
> @subsection eval
>
> diff --git a/grub-core/Makefile.core.def b/grub-core/Makefile.core.def
> index 48b82e7..12535ba 100644
> --- a/grub-core/Makefile.core.def
> +++ b/grub-core/Makefile.core.def
> @@ -2534,3 +2534,8 @@ module = {
> common = commands/i386/wrmsr.c;
> enable = x86;
> };
> +
> +module = {
> + name = efivar_get_set;
> + common = commands/efi/efivar_get_set.c;
Perhaps just call this efivars.
> +};
> diff --git a/grub-core/commands/efi/efivar_get_set.c
> b/grub-core/commands/efi/efivar_get_set.c
> new file mode 100644
> index 0000000..f1d1cd9
> --- /dev/null
> +++ b/grub-core/commands/efi/efivar_get_set.c
> @@ -0,0 +1,288 @@
> +/* efivar_get_set.c - command to get/set an EFI variable */
s/command/commands/
> +/*
> + * GRUB -- GRand Unified Bootloader
> + * Copyright (C) 2020 Free Software Foundation, 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/dl.h>
> +#include <grub/command.h>
> +#include <grub/misc.h>
> +#include <grub/mm.h>
> +#include <grub/env.h>
> +#include <grub/extcmd.h>
> +#include <grub/i18n.h>
> +#include <grub/efi/api.h>
> +#include <grub/efi/efi.h>
> +
> +GRUB_MOD_LICENSE ("GPLv3+");
> +
> +static const struct grub_arg_option options_efivar_rd[] =
> +{
> + { "set", 's', 0, N_("Assign return value to variable VARNAME."),
> + N_("VARNAME"), ARG_TYPE_STRING },
> + { "guid-var", 'g', 0, N_("Use the content of GUIDVARNAME as GUID"),
> + N_("GUIDVARNAME"), ARG_TYPE_STRING },
It would be very useful to have another options, say --convert-utf8 or
-c for short, to convert the value of the EFI variable from UTF16 to
UTF8. This should probably not be the default because variable need not
contain strings.
> + {"hexdump", 'x', 0, N_("Display EFI variable content in hex mode"), 0, 0},
> + {"verbose", 'v', 0, N_("Display more info about EFI variable."), 0, 0},
> + { 0, 0, 0, 0, 0, 0 }
> +};
> +
> +static const struct grub_arg_option options_efivar_wr[] =
> +{
> + { "set", 's', 0, N_("Assign the same EFI variable value to variable
> VARNAME."),
> + N_("VARNAME"), ARG_TYPE_STRING },
> + { "guid-var", 'g', 0, N_("Use the content of GUIDVARNAME as GUID"),
> + N_("GUIDVARNAME"), ARG_TYPE_STRING },
Ditto.
Also, by default variables should be GRUB_EFI_VARIABLE_BOOTSERVICE_ACCESS
but if -r or --runtime-access is passed, then use
GRUB_EFI_VARIABLE_RUNTIME_ACCESS as well.
> + { "non-volatile", 'n', 0, N_("Set non-volatile attribute."), 0,
> ARG_TYPE_NONE },
> + { "verbose", 'v', 0, N_("Display more info about EFI variable"), 0, 0},
> + { 0, 0, 0, 0, 0, 0 }
> +};
> +
> +static void
> +dump_efi_var_hex (void *efi_var, grub_size_t efi_var_data_size,
> + grub_uint8_t verbose)
> +{
> + #define DUMP_EFI_VAR_HEX_ROW_LEN 16
This should probably go near the top of the file after #include.
> + grub_uint32_t i, j;
> + grub_uint8_t *val = efi_var;
> +
> + grub_printf ("\n");
> + for (i = 0; i <= (efi_var_data_size / DUMP_EFI_VAR_HEX_ROW_LEN) ; i++)
> + {
> + if (verbose)
> + grub_printf ("%04x - ", i * DUMP_EFI_VAR_HEX_ROW_LEN);
> +
> + /* Print numerical values */
> + for (j = 0; j < DUMP_EFI_VAR_HEX_ROW_LEN; j++)
> + {
> + if ((i * DUMP_EFI_VAR_HEX_ROW_LEN + j) < efi_var_data_size)
> + {
> + grub_printf ("%02x", (unsigned int) val[i *
> DUMP_EFI_VAR_HEX_ROW_LEN + j]);
> + }
> + else
> + grub_printf (" ");
> + if (verbose)
> + grub_printf (" ");
> + }
> +
> + /* If verbose is active, print ASCII chars */
> + if (verbose)
> + {
> + grub_printf (" |");
> + for (j = 0; j < DUMP_EFI_VAR_HEX_ROW_LEN; j++)
> + {
> + if ((i * DUMP_EFI_VAR_HEX_ROW_LEN + j) < efi_var_data_size)
> + {
> + if (grub_isprint (val[i * DUMP_EFI_VAR_HEX_ROW_LEN + j]))
> + grub_printf ("%c", (unsigned int) val[i *
> DUMP_EFI_VAR_HEX_ROW_LEN + j]);
> + else
> + grub_printf(".");
> + }
> + else
> + grub_printf(" ");
> + }
> + grub_printf ("|\n");
> + }
> + }
> +}
> +
> +static void
> +dump_efi_guid (char *efi_var_name, grub_efi_guid_t guid)
> +{
> + grub_printf ("%s-%08x-%04x-%04x-%02x%02x-%02x%02x%02x%02x%02x%02x :\n",
> + efi_var_name,
> + (unsigned) guid.data1,
> + (unsigned) guid.data2,
> + (unsigned) guid.data3,
> + (unsigned) guid.data4[0],
> + (unsigned) guid.data4[1],
> + (unsigned) guid.data4[2],
> + (unsigned) guid.data4[3],
> + (unsigned) guid.data4[4],
> + (unsigned) guid.data4[5],
> + (unsigned) guid.data4[6],
> + (unsigned) guid.data4[7]);
> +}
> +
> +static grub_err_t
> +grub_cmd_efivar_get (grub_extcmd_context_t ctxt, int argc, char **args)
> +{
> + void *efi_var = NULL;
> + grub_size_t efi_var_data_size = 0;
> + char *buf = 0;
> + grub_efi_guid_t guid = GRUB_EFI_GLOBAL_VARIABLE_GUID;
> + const char *guid_str;
> + grub_err_t err;
> +
> + /* One argument required */
> + if (argc != 1)
> + return grub_error (GRUB_ERR_BAD_ARGUMENT,
> + N_("one argument required: EFI variable name"));
> +
> + /* Get GUID from env variable */
> + if (ctxt->state[1].set)
> + {
> + guid_str = grub_env_get (ctxt->state[1].arg);
> + if (guid_str)
> + {
> + err = grub_efi_str_to_guid (guid_str, &guid);
> + if (err)
> + return err;
> + }
> + else
> + return grub_error (GRUB_ERR_BAD_ARGUMENT,
> + N_("GUID environment variable not found"));
> + }
> + else
> + grub_printf ("No custom GUID provided, use EFI_GLOBAL_VARIABLE_GUID.\n");
This should be a grub_dprintf() if anything.
> +
> + /* Get EFI variable */
> + efi_var = grub_efi_get_variable (args[0], &guid, &efi_var_data_size);
> + if (!efi_var || !efi_var_data_size)
> + return grub_error (GRUB_ERR_READ_ERROR, N_("cannot read EFI variable"));
> +
> + /* Get EFI var data string */
> + buf = grub_malloc (efi_var_data_size * 2 + 1);
> + if (!buf)
> + return grub_errno;
> +
> + /* Copy EFI variable data */
> + grub_strncpy (buf, efi_var, efi_var_data_size);
> +
> + /* Set env variable required? */
> + if (ctxt->state[0].set)
> + grub_env_set (ctxt->state[0].arg, buf);
If the data in buf is a UTF16 string (what UEFI uses for strings), then
this will probably always set the environment variable to the empty
string because the first byte will be '\0'.
> + else
> + {
> + /* Verbose ? */
> + if (ctxt->state[3].set)
> + {
> + /* Print GUID */
> + dump_efi_guid (args[0], guid);
> +
> + /* Hexdump ? */
> + if (ctxt->state[2].set)
> + dump_efi_var_hex(efi_var, efi_var_data_size, 1);
> + else
> + grub_printf ("%s", buf);
> + }
> + else
> + /* Hexdump ? */
> + if (ctxt->state[2].set)
> + dump_efi_var_hex(efi_var, efi_var_data_size, 0);
> + else
> + grub_printf ("%s", buf);
> + }
> +
> + grub_free (buf);
> +
> + return 0;
> +}
> +
> +static grub_err_t
> +grub_cmd_efivar_set (grub_extcmd_context_t ctxt, int argc, char **args)
> +{
> + grub_err_t efi_err;
> + grub_efi_guid_t guid = GRUB_EFI_GLOBAL_VARIABLE_GUID;
> + const char *guid_str;
> + grub_efi_boolean_t non_volatile = 0;
> + grub_err_t err;
> +
> + /* Two arguments required */
> + if (argc != 2)
> + return grub_error (GRUB_ERR_BAD_ARGUMENT,
> + N_("two arguments required: EFI variable name and
> value"));
> +
> + /* Get GUID from env variable */
> + if (ctxt->state[1].set)
> + {
> + guid_str = grub_env_get (ctxt->state[1].arg);
> + if (guid_str)
> + {
> + err = grub_efi_str_to_guid (guid_str, &guid);
> + if (err)
> + return err;
> + }
> + else
> + return grub_error (GRUB_ERR_BAD_ARGUMENT,
> + N_("GUID environment variable not found"));
> + }
> + else
> + grub_printf ("No custom GUID provided, use EFI_GLOBAL_VARIABLE_GUID.\n");
> +
> + /* Volatile or non-volatile ? */
> + if (ctxt->state[2].set)
> + non_volatile = 1;
> +
> + /* Set EFI variable */
> + efi_err = grub_efi_set_variable (args[0], &guid, args[1],
> + (grub_size_t) grub_strlen(args[1]) + 1,
> + non_volatile);
> + if (efi_err != GRUB_ERR_NONE)
> + return grub_error (GRUB_ERR_WRITE_ERROR, N_("cannot write EFI
> variable"));
> +
> + /* Set env variable required? */
> + if (ctxt->state[0].set)
> + grub_env_set (ctxt->state[0].arg, args[1]);
> +
> + /* Verbose ? */
> + if (ctxt->state[3].set)
> + {
> + /* Print GUID */
> + dump_efi_guid (args[0], guid);
> +
> + grub_printf("%s EFI variable: %s set to value: %s\n",
> + non_volatile ? "Non-volatile" : "volatile",
> + args[0], args[1]);
> + }
> + return 0;
> +}
> +
> +static grub_extcmd_t cmd_rd_efi_var, cmd_wr_efi_var;
> +
> +GRUB_MOD_INIT(version)
> +{
> + cmd_rd_efi_var = grub_register_extcmd ("efivar_get",
> + grub_cmd_efivar_get, 0,
> + N_("[OPTIONS] VAR"),
Put the actual options supported here.
> + N_("\nRead EFI VAR variable (if not
> specified, use "
> + "EFI_GLOBAL_VARIABLE_GUID as
> default GUID: "
> +
> "{8be4df61-93ca-11d2-aa0d-00e098032b8c}).\n"
> + "If --set is specified, the
> version is set to a variable."
> + ),
> + options_efivar_rd);
> +
> + cmd_wr_efi_var = grub_register_extcmd ("efivar_set",
> + grub_cmd_efivar_set, 0,
> + N_("[OPTIONS] VAR VALUE"),
Ditto.
> + N_("\nWrite VALUE to EFI variable
> VAR (if not specified, use "
> + "EFI_GLOBAL_VARIABLE_GUID as
> default GUID:"
> +
> "{8be4df61-93ca-11d2-aa0d-00e098032b8c}).\n"
> + "If --set is specified, the same
> EFI variable value "
> + "is set to a variable.\n"
> + "If --non-volatile is specified,
> the non-volatile "
> + "EFI attribute is set.\n"
> + "\nNote: an existing EFI
> variable can be changed only "
> + "maintainig the same
> volatile/non-volatile attribute."
> + ),
> + options_efivar_wr);
> +}
> +
> +GRUB_MOD_FINI(version)
> +{
> + grub_unregister_extcmd (cmd_rd_efi_var);
> + grub_unregister_extcmd (cmd_wr_efi_var);
> +}
> diff --git a/grub-core/kern/efi/efi.c b/grub-core/kern/efi/efi.c
> index dcb09b2..5d7a8ed 100644
> --- a/grub-core/kern/efi/efi.c
> +++ b/grub-core/kern/efi/efi.c
> @@ -960,3 +960,60 @@ grub_efi_compare_device_paths (const
> grub_efi_device_path_t *dp1,
>
> return 0;
> }
> +
> +/* Convert a GUID from string format to grub_efi_guid_t format.
> + * For example:
> + *
> + * 8be4df61-93ca-11d2-aa0d-00e098032b8c -->
> + *
> + * --> { 0x8BE4DF61, 0x93CA, 0x11d2, \
> + * { 0xAA, 0x0D, 0x00, 0xE0, 0x98, 0x03, 0x2B, 0x8C }}
> +*/
Multiline comment not quite right, should be
/*
* ....
*/
> +grub_err_t
> +grub_efi_str_to_guid(const char *guid_str, grub_efi_guid_t *guid)
> +{
> + char guid_str_tmp[32];
> + unsigned int i;
> + union
> + {
> + grub_uint64_t octet_64;
> + grub_uint8_t octet_8[8];
> + } guid_octet;
> +
> + /* Check string size */
> + if (grub_strlen(guid_str) != EFI_GUID_STRING_LENGTH)
> + return grub_error (GRUB_ERR_BAD_ARGUMENT,
> + N_("GUID string must be %d chars long\n"),
> + EFI_GUID_STRING_LENGTH);
> +
Should check that guid is not NULL.
> + /* Remove dashes for string check */
> + grub_snprintf (&guid_str_tmp[0], 9, "%s", guid_str);
> + grub_snprintf (&guid_str_tmp[8], 5, "%s", guid_str + 9);
> + grub_snprintf (&guid_str_tmp[12], 5, "%s", guid_str + 14);
> + grub_snprintf (&guid_str_tmp[16], 5, "%s", guid_str + 19);
> + grub_snprintf (&guid_str_tmp[20], 13, "%s", guid_str + 24);
> +
> + /* Check for hex digit only */
> + for (i = 0; i < grub_strlen (guid_str_tmp); i++)
> + {
> + guid_str_tmp[i] = grub_tolower(guid_str_tmp[i]);
> +
> + if (!(grub_isxdigit (guid_str_tmp[i]))) {
> +
> + return grub_error (GRUB_ERR_BAD_ARGUMENT,
> + N_("GUID string must be like the following:
> 8be4df61-93ca-11d2-aa0d-00e098032b8c"));
> + }
> + }
> +
> + /* Convert from string to GUID */
> + guid->data1 = grub_strtoul (&guid_str[0], NULL, 16);
> + guid->data2 = grub_strtoul (&guid_str[9], NULL, 16);
> + guid->data3 = grub_strtoul (&guid_str[14], NULL, 16);
> + guid_octet.octet_64 = grub_strtoull (&guid_str_tmp[16], NULL, 16);
> + for (i = 0; i <= 7; i++)
> + {
> + guid->data4[i] = guid_octet.octet_8[7 - i];
> + }
This function seems like its doing a lot more work than necessary. I
think it would be better to loop over every byte of guid_str, skipping
dashes. On each non-dash, error if its not a hex digit. Convert the
hexdigit character to a number and put it directly into the guid as
appropriate, keeping track that the appropriate number of hexdigits
have been seen and error otherwise. I don't we need to care if the
dashes are in the right position or there at all.
Glenn
> +
> + return GRUB_ERR_NONE;
> +}
> \ No newline at end of file
> diff --git a/include/grub/efi/efi.h b/include/grub/efi/efi.h
> index 9b04150..dc87cc2 100644
> --- a/include/grub/efi/efi.h
> +++ b/include/grub/efi/efi.h
> @@ -24,6 +24,8 @@
> #include <grub/dl.h>
> #include <grub/efi/api.h>
>
> +#define EFI_GUID_STRING_LENGTH 36
> +
> /* Functions. */
> void *EXPORT_FUNC(grub_efi_locate_protocol) (grub_efi_guid_t *protocol,
> void *registration);
> @@ -90,6 +92,8 @@ EXPORT_FUNC (grub_efi_compare_device_paths) (const
> grub_efi_device_path_t *dp1,
> extern void (*EXPORT_VAR(grub_efi_net_config)) (grub_efi_handle_t hnd,
> char **device,
> char **path);
> +grub_err_t
> +EXPORT_FUNC(grub_efi_str_to_guid)(const char *guid_str, grub_efi_guid_t
> *guid);
>
> #if defined(__arm__) || defined(__aarch64__) || defined(__riscv)
> void *EXPORT_FUNC(grub_efi_get_firmware_fdt)(void);
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Glenn Washburn <=