143 lines
3.7 KiB
C
143 lines
3.7 KiB
C
/*
|
|
* GRUB -- GRand Unified Bootloader
|
|
* Copyright (C) 2017 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/>.
|
|
*
|
|
* EFI shim lock verifier.
|
|
*/
|
|
|
|
#include <grub/dl.h>
|
|
#include <grub/efi/efi.h>
|
|
#include <grub/err.h>
|
|
#include <grub/file.h>
|
|
#include <grub/misc.h>
|
|
#include <grub/verify.h>
|
|
|
|
GRUB_MOD_LICENSE ("GPLv3+");
|
|
|
|
#define GRUB_EFI_SHIM_LOCK_GUID \
|
|
{ 0x605dab50, 0xe046, 0x4300, \
|
|
{ 0xab, 0xb6, 0x3d, 0xd8, 0x10, 0xdd, 0x8b, 0x23 } \
|
|
}
|
|
|
|
struct grub_efi_shim_lock_protocol
|
|
{
|
|
grub_efi_status_t
|
|
(*verify) (void *buffer, grub_uint32_t size);
|
|
};
|
|
typedef struct grub_efi_shim_lock_protocol grub_efi_shim_lock_protocol_t;
|
|
|
|
static grub_efi_guid_t shim_lock_guid = GRUB_EFI_SHIM_LOCK_GUID;
|
|
static grub_efi_shim_lock_protocol_t *sl;
|
|
|
|
/* List of modules which cannot be loaded if UEFI secure boot mode is enabled. */
|
|
static const char * const disabled_mods[] = {"iorw", "memrw", "wrmsr", NULL};
|
|
|
|
static grub_err_t
|
|
shim_lock_init (grub_file_t io, enum grub_file_type type,
|
|
void **context __attribute__ ((unused)),
|
|
enum grub_verify_flags *flags)
|
|
{
|
|
const char *b, *e;
|
|
int i;
|
|
|
|
*flags = GRUB_VERIFY_FLAGS_SKIP_VERIFICATION;
|
|
|
|
if (!sl)
|
|
return GRUB_ERR_NONE;
|
|
|
|
switch (type & GRUB_FILE_TYPE_MASK)
|
|
{
|
|
case GRUB_FILE_TYPE_GRUB_MODULE:
|
|
/* Establish GRUB module name. */
|
|
b = grub_strrchr (io->name, '/');
|
|
e = grub_strrchr (io->name, '.');
|
|
|
|
b = b ? (b + 1) : io->name;
|
|
e = e ? e : io->name + grub_strlen (io->name);
|
|
e = (e > b) ? e : io->name + grub_strlen (io->name);
|
|
|
|
for (i = 0; disabled_mods[i]; i++)
|
|
if (!grub_strncmp (b, disabled_mods[i], grub_strlen (b) - grub_strlen (e)))
|
|
{
|
|
grub_error (GRUB_ERR_ACCESS_DENIED,
|
|
N_("module cannot be loaded in UEFI secure boot mode: %s"),
|
|
io->name);
|
|
return GRUB_ERR_ACCESS_DENIED;
|
|
}
|
|
|
|
/* Fall through. */
|
|
|
|
case GRUB_FILE_TYPE_ACPI_TABLE:
|
|
case GRUB_FILE_TYPE_DEVICE_TREE_IMAGE:
|
|
*flags = GRUB_VERIFY_FLAGS_DEFER_AUTH;
|
|
|
|
return GRUB_ERR_NONE;
|
|
|
|
case GRUB_FILE_TYPE_LINUX_KERNEL:
|
|
case GRUB_FILE_TYPE_MULTIBOOT_KERNEL:
|
|
case GRUB_FILE_TYPE_BSD_KERNEL:
|
|
case GRUB_FILE_TYPE_XNU_KERNEL:
|
|
case GRUB_FILE_TYPE_PLAN9_KERNEL:
|
|
for (i = 0; disabled_mods[i]; i++)
|
|
if (grub_dl_get (disabled_mods[i]))
|
|
{
|
|
grub_error (GRUB_ERR_ACCESS_DENIED,
|
|
N_("cannot boot due to dangerous module in memory: %s"),
|
|
disabled_mods[i]);
|
|
return GRUB_ERR_ACCESS_DENIED;
|
|
}
|
|
|
|
*flags = GRUB_VERIFY_FLAGS_SINGLE_CHUNK;
|
|
|
|
/* Fall through. */
|
|
|
|
default:
|
|
return GRUB_ERR_NONE;
|
|
}
|
|
}
|
|
|
|
static grub_err_t
|
|
shim_lock_write (void *context __attribute__ ((unused)), void *buf, grub_size_t size)
|
|
{
|
|
if (sl->verify (buf, size) != GRUB_EFI_SUCCESS)
|
|
return grub_error (GRUB_ERR_BAD_SIGNATURE, N_("bad shim signature"));
|
|
|
|
return GRUB_ERR_NONE;
|
|
}
|
|
|
|
struct grub_file_verifier shim_lock =
|
|
{
|
|
.name = "shim_lock",
|
|
.init = shim_lock_init,
|
|
.write = shim_lock_write
|
|
};
|
|
|
|
GRUB_MOD_INIT(shim_lock)
|
|
{
|
|
sl = grub_efi_locate_protocol (&shim_lock_guid, 0);
|
|
grub_verifier_register (&shim_lock);
|
|
|
|
if (!sl)
|
|
return;
|
|
|
|
grub_dl_set_persistent (mod);
|
|
}
|
|
|
|
GRUB_MOD_FINI(shim_lock)
|
|
{
|
|
grub_verifier_unregister (&shim_lock);
|
|
}
|