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[PATCH v3 06/10] Add a module for the Boot Loader Interface
From: |
Oliver Steffen |
Subject: |
[PATCH v3 06/10] Add a module for the Boot Loader Interface |
Date: |
Thu, 2 Mar 2023 19:20:41 +0100 |
Add a new module named boot_loader_interface, which provides a command
with the same name. 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.
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 only available on EFI platforms.
[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>
---
grub-core/Makefile.core.def | 6 ++
grub-core/commands/bli.c | 199 ++++++++++++++++++++++++++++++++++++
include/grub/efi/api.h | 5 +
3 files changed, 210 insertions(+)
create mode 100644 grub-core/commands/bli.c
diff --git a/grub-core/Makefile.core.def b/grub-core/Makefile.core.def
index 71093a100..cdfa2d101 100644
--- a/grub-core/Makefile.core.def
+++ b/grub-core/Makefile.core.def
@@ -2548,3 +2548,9 @@ module = {
common = commands/i386/wrmsr.c;
enable = x86;
};
+
+module = {
+ name = bli;
+ efi = commands/bli.c;
+ enable = efi;
+};
diff --git a/grub-core/commands/bli.c b/grub-core/commands/bli.c
new file mode 100644
index 000000000..0ff44d58a
--- /dev/null
+++ b/grub-core/commands/bli.c
@@ -0,0 +1,199 @@
+/*
+ * GRUB -- GRand Unified Bootloader
+ * Copyright (C) 2023 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/>.
+ *
+ * Implementation of the Boot Loader Interface.
+ */
+
+#include <grub/charset.h>
+#include <grub/efi/api.h>
+#include <grub/efi/disk.h>
+#include <grub/efi/efi.h>
+#include <grub/err.h>
+#include <grub/extcmd.h>
+#include <grub/gpt_partition.h>
+#include <grub/misc.h>
+#include <grub/mm.h>
+#include <grub/partition.h>
+#include <grub/types.h>
+
+GRUB_MOD_LICENSE ("GPLv3+");
+
+#define MODNAME "bli"
+
+static const grub_guid_t bli_vendor_guid =
GRUB_EFI_VENDOR_BOOT_LOADER_INTERFACE_GUID;
+
+static grub_err_t
+get_part_uuid (grub_device_t dev, char **part_uuid)
+{
+ grub_err_t status = GRUB_ERR_NONE;
+ grub_disk_t disk;
+ struct grub_gpt_partentry entry;
+
+ if (dev == NULL || dev->disk == NULL || dev->disk->partition == NULL)
+ return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("invalid device"));
+
+ disk = grub_disk_open (dev->disk->name);
+ if (disk == NULL)
+ {
+ status = grub_errno;
+ char *part = grub_partition_get_name (dev->disk->partition);
+ grub_dprintf (MODNAME, "error opening disk: %s%s%s\n", dev->disk->name,
+ dev->disk->partition != NULL ? "," : "",
+ part != NULL ? part : "UNKNOWN");
+ grub_free (part);
+ return status;
+ }
+
+ if (grub_strcmp (dev->disk->partition->partmap->name, "gpt") != 0)
+ {
+ char *part = grub_partition_get_name (dev->disk->partition);
+ status = grub_error (GRUB_ERR_BAD_PART_TABLE,
+ "this is not a GPT partition table: %s%s%s",
dev->disk->name,
+ dev->disk->partition != NULL ? "," : "",
+ part != NULL ? part : "UNKNOWN");
+ grub_free (part);
+ goto fail;
+ }
+
+ if (grub_disk_read (disk, dev->disk->partition->offset,
+ dev->disk->partition->index, sizeof (entry), &entry) !=
GRUB_ERR_NONE)
+ {
+ status = grub_errno;
+ char *part = grub_partition_get_name (dev->disk->partition);
+ grub_dprintf (MODNAME, "read error: %s%s%s\n", dev->disk->name,
+ dev->disk->partition != NULL ? "," : "",
+ part != NULL ? part : "UNKNOWN");
+ grub_free (part);
+ goto fail;
+ }
+
+ *part_uuid = grub_xasprintf ("%pG", &entry.guid);
+ if (*part_uuid == NULL)
+ status = grub_errno;
+
+ fail:
+ grub_disk_close (disk);
+
+ return status;
+}
+
+static grub_err_t
+set_efi_str_variable (const char *name, const grub_guid_t *guid,
+ const char *value)
+{
+ grub_size_t len, len16;
+ grub_efi_char16_t *value_16;
+ grub_err_t status;
+
+ len = grub_strlen (value);
+
+ /* Check for integer overflow */
+ if (len > GRUB_SIZE_MAX / GRUB_MAX_UTF16_PER_UTF8 - 1)
+ return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("data too large"));
+
+ len16 = len * GRUB_MAX_UTF16_PER_UTF8;
+
+ value_16 = grub_calloc (len16 + 1, sizeof (value_16[0]));
+ if (value_16 == NULL)
+ return grub_errno;
+
+ len16 = grub_utf8_to_utf16 (value_16, len16, (grub_uint8_t *) value, len,
NULL);
+
+ status = grub_efi_set_variable_with_attributes (name, guid,
+ (void *) value_16, (len16 + 1) * sizeof (value_16[0]),
+ GRUB_EFI_VARIABLE_BOOTSERVICE_ACCESS
+ | GRUB_EFI_VARIABLE_RUNTIME_ACCESS);
+ if (status != GRUB_ERR_NONE)
+ grub_dprintf (MODNAME, "Error setting EFI variable %s: %d\n", name,
status);
+
+ grub_free (value_16);
+
+ return status;
+}
+
+static grub_err_t
+set_loader_device_part_uuid (void)
+{
+ grub_efi_loaded_image_t *image;
+ char *device_name;
+ grub_err_t status = GRUB_ERR_NONE;
+ grub_device_t device;
+ char *part_uuid = NULL;
+
+ image = grub_efi_get_loaded_image (grub_efi_image_handle);
+ if (image == NULL)
+ return grub_error (GRUB_ERR_BAD_DEVICE, N_("unable to find boot device"));
+
+ device_name = grub_efidisk_get_device_name (image->device_handle);
+ if (device_name == NULL)
+ return grub_error (GRUB_ERR_BAD_DEVICE, N_("unable to find boot device"));
+
+ device = grub_device_open (device_name);
+ if (device == NULL)
+ {
+ status = grub_errno;
+ grub_dprintf (MODNAME, "Error opening device: %s", device_name);
+ goto fail;
+ }
+
+ status = get_part_uuid (device, &part_uuid);
+
+ grub_device_close (device);
+
+ if (status == GRUB_ERR_NONE)
+ status = set_efi_str_variable ("LoaderDevicePartUUID",
+ &bli_vendor_guid,
+ part_uuid);
+
+ fail:
+ grub_free (part_uuid);
+ grub_free (device_name);
+ return status;
+}
+
+static grub_err_t
+grub_cmd_bli (grub_extcmd_context_t ctxt __attribute__ ((unused)),
+ int argc __attribute__ ((unused)),
+ char **args __attribute__ ((unused)))
+{
+ grub_err_t status;
+
+ status = set_efi_str_variable ("LoaderInfo", &bli_vendor_guid,
PACKAGE_STRING);
+ if (status != GRUB_ERR_NONE)
+ return status;
+
+ status = set_loader_device_part_uuid ();
+ if (status != GRUB_ERR_NONE)
+ return status;
+
+ return GRUB_ERR_NONE;
+}
+
+static grub_extcmd_t cmd;
+
+GRUB_MOD_INIT (bli)
+{
+ grub_dprintf (MODNAME, "%s got here\n", __func__);
+ cmd = grub_register_extcmd ("bli", grub_cmd_bli, 0, NULL,
+ N_("Set EFI variables according to Boot Loader
Interface spec."), NULL);
+}
+
+GRUB_MOD_FINI (bli)
+{
+ grub_unregister_extcmd (cmd);
+}
+
diff --git a/include/grub/efi/api.h b/include/grub/efi/api.h
index a6bd74b96..d5b4f8c8e 100644
--- a/include/grub/efi/api.h
+++ b/include/grub/efi/api.h
@@ -374,6 +374,11 @@
{ 0xac, 0x74, 0xca, 0x55, 0x52, 0x31, 0xcc, 0x68 } \
}
+#define GRUB_EFI_VENDOR_BOOT_LOADER_INTERFACE_GUID \
+ { 0x4a67b082, 0x0a4c, 0x41cf, \
+ {0xb6, 0xc7, 0x44, 0x0b, 0x29, 0xbb, 0x8c, 0x4f } \
+ }
+
struct grub_efi_sal_system_table
{
grub_uint32_t signature;
--
2.39.2
- [PATCH v3 00/10] Add basic Boot Loader Interface support, Oliver Steffen, 2023/03/02
- [PATCH v3 01/10] efi: Add grub_efi_set_variable_with_attributes, Oliver Steffen, 2023/03/02
- [PATCH v3 04/10] kern/misc: Add a format specifier GUIDs., Oliver Steffen, 2023/03/02
- [PATCH v3 03/10] Unify GUID types, Oliver Steffen, 2023/03/02
- [PATCH v3 07/10] grub-core/kern/efi: Remove redundant null-termination, Oliver Steffen, 2023/03/02
- [PATCH v3 02/10] efi: Check for integer overflow in string conversion, Oliver Steffen, 2023/03/02
- [PATCH v3 05/10] grub-core: Make use of guid printf format specifier, Oliver Steffen, 2023/03/02
- [PATCH v3 06/10] Add a module for the Boot Loader Interface,
Oliver Steffen <=
- [PATCH v3 08/10] types.h: Add GRUB_SSIZE_MAX, Oliver Steffen, 2023/03/02
- [PATCH v3 10/10] util/grub.d: Activate bli module on EFI, Oliver Steffen, 2023/03/02
- [PATCH v3 09/10] commands/bli: Extract uft8 to utf16 conversion, Oliver Steffen, 2023/03/02