[PATCH 10/10] Add command to set an environment variable to an EFI variable

[Simon Glass]

Hi Heinrich,

On Sun, 24 Nov 2024 at 08:11, Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
>
> On 11/23/24 20:55, Matthew Garrett wrote:
> > From: Matthew Garrett <mgarrett at aurora.tech>
> >
> > We may want to make things conditional on EFI variable state
> >
> > Signed-off-by: Matthew Garrett <mgarrett at aurora.tech>
> > ---
> >
> >   cmd/Kconfig     |   4 ++
> >   cmd/Makefile    |   1 +
> >   cmd/efigetenv.c | 133 ++++++++++++++++++++++++++++++++++++++++++++++++
> >   3 files changed, 138 insertions(+)
> >   create mode 100644 cmd/efigetenv.c
> >
> > diff --git a/cmd/Kconfig b/cmd/Kconfig
> > index 33bf3d1ad39..118fb721081 100644
> > --- a/cmd/Kconfig
> > +++ b/cmd/Kconfig
> > @@ -752,6 +752,10 @@ config CMD_NVEDIT_SELECT
> >       help
> >         Select the compiled-in persistent storage of environment variables.
> >
> > +config CMD_EFI_GET_ENV
> > +     bool "efi get env"
> > +     help
> > +       Set an environment variable to the contents of an EFI variable
> >   endmenu
> >
> >   menu "Memory commands"
> > diff --git a/cmd/Makefile b/cmd/Makefile
> > index 38cb7a4aea5..0507c204c0e 100644
> > --- a/cmd/Makefile
> > +++ b/cmd/Makefile
> > @@ -69,6 +69,7 @@ obj-$(CONFIG_CMD_EEPROM) += eeprom.o
> >   obj-$(CONFIG_EFI) += efi.o efi_common.o
> >   obj-$(CONFIG_CMD_EFIDEBUG) += efidebug.o efi_common.o
> >   obj-$(CONFIG_CMD_EFICONFIG) += eficonfig.o
> > +obj-$(CONFIG_CMD_EFI_GET_ENV) += efigetenv.o
> >   ifdef CONFIG_CMD_EFICONFIG
> >   ifdef CONFIG_EFI_MM_COMM_TEE
> >   obj-$(CONFIG_EFI_SECURE_BOOT) += eficonfig_sbkey.o
> > diff --git a/cmd/efigetenv.c b/cmd/efigetenv.c
> > new file mode 100644
> > index 00000000000..5284ee92d6c
> > --- /dev/null
> > +++ b/cmd/efigetenv.c
> > @@ -0,0 +1,133 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +#include <charset.h>
> > +#include <command.h>
> > +#include <efi_loader.h>
> > +#include <efi_variable.h>
> > +#include <env.h>
> > +#include <hexdump.h>
> > +#include <malloc.h>
> > +#include <uuid.h>
> > +
> > +/* Set a U-Boot environment variable to the contents of a UEFI variable */
> > +int do_efi_get_env(struct cmd_tbl *cmdtb, int flat, int argc, char *const argv[])
> > +{
> > +     u16 *var_name = NULL;
> > +     char *strdata = NULL;
> > +     efi_uintn_t size = 0;
> > +     bool var_content_is_utf16_string = false;
> > +     efi_status_t ret;
> > +     efi_guid_t guid;
> > +     u8 *data = NULL;
> > +     u32 attributes;
> > +     size_t len;
> > +     u64 time;
> > +     u16 *p;
> > +
> > +     ret = efi_init_obj_list();
> > +     if (ret != EFI_SUCCESS) {
> > +             printf("Error: Cannot initialize UEFI sub-system, r = %lu\n",
> > +                    ret & ~EFI_ERROR_MASK);
> > +             return CMD_RET_FAILURE;
> > +     }
> > +
> > +     argv++;
> > +     argc--;
> > +
> > +     if (argc != 3 && argc != 4)
> > +             return CMD_RET_USAGE;
> > +
> > +     if (argc == 4) {
> > +             if (strcmp(argv[0], "-s"))
> > +                     return CMD_RET_USAGE;
> > +             var_content_is_utf16_string = true;
> > +             argv++;
> > +             argc--;
> > +     }
> > +
> > +     len = utf8_utf16_strnlen(argv[0], strlen(argv[0]));
> > +     var_name = malloc((len + 1) * 2);
> > +     if (!var_name) {
> > +             printf("## Out of memory\n");
> > +             return CMD_RET_FAILURE;
> > +     }
> > +     p = var_name;
> > +     utf8_utf16_strncpy(&p, argv[0], len + 1);
> > +
> > +     if (uuid_str_to_bin(argv[1], guid.b, UUID_STR_FORMAT_GUID)) {
> > +             ret = CMD_RET_USAGE;
> > +             goto out;
> > +     }
> > +
> > +     ret = efi_get_variable_int(var_name, &guid, &attributes, &size, data,
> > +                                &time);
> > +     if (ret == EFI_BUFFER_TOO_SMALL) {
> > +             data = malloc(size);
> > +             if (!data) {
> > +                     printf("## Out of memory\n");
> > +                     ret = CMD_RET_FAILURE;
> > +                     goto out;
> > +             }
> > +             ret = efi_get_variable_int(var_name, &guid, &attributes,
> > +                                        &size, data, &time);
>
> This duplicates code in efi_dump_single_var(), do_efi_capsule_res(),
> get_dp_device() and others.
>
> We should carve out a function.

Can you have a look at what to do here and send a patch? As in the
comment Ilias made, it seems like we may need some of the EFI-loader
code to move to lib/efi
>
> > +     }
> > +
> > +     if (ret == EFI_NOT_FOUND) {
> > +             printf("Error: \"%ls\" not defined\n", var_name);
> > +             ret = CMD_RET_FAILURE;
> > +             goto out;
> > +     }
> > +
> > +     if (ret != EFI_SUCCESS) {
> > +             printf("Error: Cannot read variable, r = %lu\n",
> > +                    ret & ~EFI_ERROR_MASK);
> > +             ret = CMD_RET_FAILURE;
> > +             goto out;
> > +     }
> > +
> > +     if (var_content_is_utf16_string) {
> > +             char *p;
> > +
> > +             len = utf16_utf8_strnlen((u16 *)data, size / 2);
> > +             strdata = malloc(len + 1);
> > +             if (!strdata) {
> > +                     printf("## Out of memory\n");
> > +                     ret = CMD_RET_FAILURE;
> > +                     goto out;
> > +             }
> > +             p = strdata;
> > +             utf16_utf8_strncpy(&p, (u16 *)data, size / 2);
> > +     } else {
> > +             len = size * 2;
> > +             strdata = malloc(len + 1);
> > +             if (!strdata) {
> > +                     printf("## Out of memory\n");
> > +                     ret = CMD_RET_FAILURE;
> > +                     goto out;
> > +             }
> > +             bin2hex(strdata, data, size);
> > +     }
> > +
> > +     strdata[len] = '\0';
> > +
> > +     ret = env_set(argv[2], strdata);
> > +     if (ret) {
> > +             ret = CMD_RET_FAILURE;
> > +             goto out;
> > +     }
> > +
> > +     ret = CMD_RET_SUCCESS;
> > +out:
> > +     free(strdata);
> > +     free(data);
> > +     free(var_name);
> > +
> > +     return ret;
> > +}
> > +
> > +U_BOOT_CMD(
> > +     efigetenv, 5, 4, do_efi_get_env,
> > +     "set environment variable to content of EFI variable",
> > +     "[-s] name guid envvar\n"
> > +     "    - set environment variable 'envvar' to the EFI variable 'name'-'guid'\n"
> > +     "      \"-s\": Interpret the EFI variable value as a UTF-16 string\n"
> > +);
>

Regards,
SImon