diff options
Diffstat (limited to 'src/interface/efi/efi_settings.c')
| -rw-r--r-- | src/interface/efi/efi_settings.c | 236 |
1 files changed, 236 insertions, 0 deletions
diff --git a/src/interface/efi/efi_settings.c b/src/interface/efi/efi_settings.c new file mode 100644 index 00000000..cde0ff8d --- /dev/null +++ b/src/interface/efi/efi_settings.c @@ -0,0 +1,236 @@ +/* + * Copyright (C) 2023 Michael Brown <mbrown@fensystems.co.uk>. + * + * This program 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 2 of the + * License, or any later version. + * + * This program 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 this program; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA + * 02110-1301, USA. + * + * You can also choose to distribute this program under the terms of + * the Unmodified Binary Distribution Licence (as given in the file + * COPYING.UBDL), provided that you have satisfied its requirements. + */ + +FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL ); + +/** + * @file + * + * EFI variable settings + * + */ + +#include <stdlib.h> +#include <string.h> +#include <errno.h> +#include <ipxe/settings.h> +#include <ipxe/init.h> +#include <ipxe/efi/efi.h> +#include <ipxe/efi/efi_strings.h> + +/** EFI variable settings scope */ +static const struct settings_scope efivars_scope; + +/** EFI variable settings */ +static struct settings efivars; + +/** + * Check applicability of EFI variable setting + * + * @v settings Settings block + * @v setting Setting + * @ret applies Setting applies within this settings block + */ +static int efivars_applies ( struct settings *settings __unused, + const struct setting *setting ) { + + return ( setting->scope == &efivars_scope ); +} + +/** + * Find first matching EFI variable name + * + * @v wname Name + * @v guid GUID to fill in + * @ret rc Return status code + */ +static int efivars_find ( const CHAR16 *wname, EFI_GUID *guid ) { + EFI_RUNTIME_SERVICES *rs = efi_systab->RuntimeServices; + size_t wname_len = ( ( wcslen ( wname ) + 1 ) * sizeof ( wname[0] ) ); + CHAR16 *buf; + CHAR16 *tmp; + UINTN size; + EFI_STATUS efirc; + int rc; + + /* Allocate single wNUL for first call to GetNextVariableName() */ + size = sizeof ( buf[0] ); + buf = zalloc ( size ); + if ( ! buf ) + return -ENOMEM; + + /* Iterate over all veriables */ + while ( 1 ) { + + /* Get next variable name */ + efirc = rs->GetNextVariableName ( &size, buf, guid ); + if ( efirc == EFI_BUFFER_TOO_SMALL ) { + tmp = realloc ( buf, size ); + if ( ! tmp ) { + rc = -ENOMEM; + break; + } + buf = tmp; + efirc = rs->GetNextVariableName ( &size, buf, guid ); + } + if ( efirc == EFI_NOT_FOUND ) { + rc = -ENOENT; + break; + } + if ( efirc != 0 ) { + rc = -EEFI ( efirc ); + DBGC ( &efivars, "EFIVARS %s:%ls could not fetch next " + "variable name: %s\n", + efi_guid_ntoa ( guid ), buf, strerror ( rc ) ); + break; + } + DBGC2 ( &efivars, "EFIVARS %s:%ls exists\n", + efi_guid_ntoa ( guid ), buf ); + + /* Check for matching variable name */ + if ( memcmp ( wname, buf, wname_len ) == 0 ) { + rc = 0; + break; + } + } + + /* Free temporary buffer */ + free ( buf ); + + return rc; +} + +/** + * Fetch value of EFI variable setting + * + * @v settings Settings block + * @v setting Setting to fetch + * @v data Buffer to fill with setting data + * @v len Length of buffer + * @ret len Length of setting data, or negative error + */ +static int efivars_fetch ( struct settings *settings __unused, + struct setting *setting, void *data, size_t len ) { + EFI_RUNTIME_SERVICES *rs = efi_systab->RuntimeServices; + size_t name_len = strlen ( setting->name ); + CHAR16 wname[ name_len + 1 /* wNUL */ ]; + EFI_GUID guid; + UINT32 attrs; + UINTN size; + void *buf; + EFI_STATUS efirc; + int rc; + + /* Convert name to UCS-2 */ + efi_snprintf ( wname, sizeof ( wname ), "%s", setting->name ); + + /* Find variable GUID */ + if ( ( rc = efivars_find ( wname, &guid ) ) != 0 ) + goto err_find; + + /* Get variable length */ + size = 0; + if ( ( efirc = rs->GetVariable ( wname, &guid, &attrs, &size, + NULL ) != EFI_BUFFER_TOO_SMALL ) ) { + rc = -EEFI ( efirc ); + DBGC ( &efivars, "EFIVARS %s:%ls could not get size: %s\n", + efi_guid_ntoa ( &guid ), wname, strerror ( rc ) ); + goto err_len; + } + + /* Allocate temporary buffer, since GetVariable() is not + * guaranteed to return partial data for an underlength + * buffer. + */ + buf = malloc ( size ); + if ( ! buf ) { + rc = -ENOMEM; + goto err_alloc; + } + + /* Get variable value */ + if ( ( efirc = rs->GetVariable ( wname, &guid, &attrs, &size, + buf ) ) != 0 ) { + rc = -EEFI ( efirc ); + DBGC ( &efivars, "EFIVARS %s:%ls could not get %zd bytes: " + "%s\n", efi_guid_ntoa ( &guid ), wname, + ( ( size_t ) size ), strerror ( rc ) ); + goto err_get; + } + DBGC ( &efivars, "EFIVARS %s:%ls:\n", efi_guid_ntoa ( &guid ), wname ); + DBGC_HDA ( &efivars, 0, buf, size ); + + /* Return setting value */ + if ( len > size ) + len = size; + memcpy ( data, buf, len ); + if ( ! setting->type ) + setting->type = &setting_type_hex; + + /* Free temporary buffer */ + free ( buf ); + + return size; + + err_get: + free ( buf ); + err_alloc: + err_len: + err_find: + return rc; +} + +/** EFI variable settings operations */ +static struct settings_operations efivars_operations = { + .applies = efivars_applies, + .fetch = efivars_fetch, +}; + +/** EFI variable settings */ +static struct settings efivars = { + .refcnt = NULL, + .siblings = LIST_HEAD_INIT ( efivars.siblings ), + .children = LIST_HEAD_INIT ( efivars.children ), + .op = &efivars_operations, + .default_scope = &efivars_scope, +}; + +/** + * Initialise EFI variable settings + * + */ +static void efivars_init ( void ) { + int rc; + + /* Register settings block */ + if ( ( rc = register_settings ( &efivars, NULL, "efi" ) ) != 0 ) { + DBGC ( &efivars, "EFIVARS could not register: %s\n", + strerror ( rc ) ); + return; + } +} + +/** EFI variable settings initialiser */ +struct init_fn efivars_init_fn __init_fn ( INIT_NORMAL ) = { + .initialise = efivars_init, +}; |