e0fa7dc84c
Add a new module named bli. It implements a small but quite useful part of the Boot Loader Interface [0]. This interface uses EFI variables for communication between the boot loader and the operating system. When loaded, this module sets two EFI variables under the vendor GUID 4a67b082-0a4c-41cf-b6c7-440b29bb8c4f: - LoaderInfo: contains GRUB + <version number>. This allows the running operating system to identify the boot loader used during boot. - LoaderDevicePartUUID: contains the partition UUID of the EFI System Partition (ESP). This is used by systemd-gpt-auto-generator [1] to find the root partitions (and others too), via partition type IDs [2]. This module is available on EFI platforms only. The bli module relies on the part_gpt module which has to be loaded beforehand to make the GPT partitions discoverable. Update the documentation, add a new chapter "Modules" and describe the bli module there. [0] https://systemd.io/BOOT_LOADER_INTERFACE/ [1] https://www.freedesktop.org/software/systemd/man/systemd-gpt-auto-generator.html [2] https://uapi-group.org/specifications/specs/discoverable_partitions_specification/ Signed-off-by: Oliver Steffen <osteffen@redhat.com> Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
121 lines
3.5 KiB
C
121 lines
3.5 KiB
C
/*
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* GRUB -- GRand Unified Bootloader
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* Copyright (C) 2023 Free Software Foundation, Inc.
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*
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* GRUB is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* GRUB is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with GRUB. If not, see <http://www.gnu.org/licenses/>.
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*
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* Implementation of the Boot Loader Interface.
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*/
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#include <grub/charset.h>
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#include <grub/efi/api.h>
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#include <grub/efi/disk.h>
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#include <grub/efi/efi.h>
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#include <grub/err.h>
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#include <grub/extcmd.h>
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#include <grub/gpt_partition.h>
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#include <grub/misc.h>
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#include <grub/mm.h>
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#include <grub/partition.h>
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#include <grub/types.h>
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GRUB_MOD_LICENSE ("GPLv3+");
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#define MODNAME "bli"
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static const grub_guid_t bli_vendor_guid = GRUB_EFI_VENDOR_BOOT_LOADER_INTERFACE_GUID;
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static grub_err_t
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get_part_uuid (const char *device_name, char **part_uuid)
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{
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grub_device_t device;
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grub_err_t status = GRUB_ERR_NONE;
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grub_disk_t disk = NULL;
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struct grub_gpt_partentry entry;
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device = grub_device_open (device_name);
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if (device == NULL)
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return grub_error (grub_errno, N_("cannot open device: %s"), device_name);
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disk = grub_disk_open (device->disk->name);
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if (disk == NULL)
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{
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status = grub_error (grub_errno, N_("cannot open disk: %s"), device_name);
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grub_device_close (device);
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return status;
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}
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if (grub_strcmp (device->disk->partition->partmap->name, "gpt") != 0)
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{
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status = grub_error (GRUB_ERR_BAD_PART_TABLE,
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N_("this is not a GPT partition table: %s"), device_name);
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goto fail;
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}
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if (grub_disk_read (disk, device->disk->partition->offset,
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device->disk->partition->index, sizeof (entry), &entry) != GRUB_ERR_NONE)
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{
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status = grub_error (grub_errno, N_("read error: %s"), device_name);
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goto fail;
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}
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*part_uuid = grub_xasprintf ("%pG", &entry.guid);
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if (*part_uuid == NULL)
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status = grub_errno;
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fail:
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grub_disk_close (disk);
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grub_device_close (device);
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return status;
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}
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static grub_err_t
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set_loader_device_part_uuid (void)
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{
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grub_efi_loaded_image_t *image;
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char *device_name;
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grub_err_t status = GRUB_ERR_NONE;
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char *part_uuid = NULL;
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image = grub_efi_get_loaded_image (grub_efi_image_handle);
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if (image == NULL)
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return grub_error (GRUB_ERR_BAD_DEVICE, N_("unable to find boot device"));
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device_name = grub_efidisk_get_device_name (image->device_handle);
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if (device_name == NULL)
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return grub_error (GRUB_ERR_BAD_DEVICE, N_("unable to find boot device"));
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status = get_part_uuid (device_name, &part_uuid);
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if (status == GRUB_ERR_NONE)
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status = grub_efi_set_variable_to_string ("LoaderDevicePartUUID", &bli_vendor_guid, part_uuid,
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GRUB_EFI_VARIABLE_BOOTSERVICE_ACCESS |
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GRUB_EFI_VARIABLE_RUNTIME_ACCESS);
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else
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grub_error (status, N_("unable to determine partition UUID of boot device"));
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grub_free (part_uuid);
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grub_free (device_name);
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return status;
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}
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GRUB_MOD_INIT (bli)
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{
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grub_efi_set_variable_to_string ("LoaderInfo", &bli_vendor_guid, PACKAGE_STRING,
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GRUB_EFI_VARIABLE_BOOTSERVICE_ACCESS |
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GRUB_EFI_VARIABLE_RUNTIME_ACCESS);
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set_loader_device_part_uuid ();
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}
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