/*
* Copyright (C) 2021 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 );
#include <string.h>
#include <errno.h>
#include <ipxe/acpi.h>
#include <ipxe/base16.h>
#include <ipxe/ethernet.h>
#include <ipxe/if_ether.h>
#include <ipxe/settings.h>
#include <ipxe/acpimac.h>
/** @file
*
* ACPI MAC address
*
*/
/** Colour for debug messages */
#define colour FADT_SIGNATURE
/** AMAC signature */
#define AMAC_SIGNATURE ACPI_SIGNATURE ( 'A', 'M', 'A', 'C' )
/** MACA signature */
#define MACA_SIGNATURE ACPI_SIGNATURE ( 'M', 'A', 'C', 'A' )
/** RTMA signature */
#define RTMA_SIGNATURE ACPI_SIGNATURE ( 'R', 'T', 'M', 'A' )
/** Maximum number of bytes to skip after ACPI signature
*
* This is entirely empirical.
*/
#define ACPIMAC_MAX_SKIP 8
/** An ACPI MAC extraction mechanism */
struct acpimac_extractor {
/** Prefix string */
const char *prefix;
/** Encoded MAC length */
size_t len;
/** Decode MAC
*
* @v mac Encoded MAC
* @v hw_addr MAC address to fill in
* @ret rc Return status code
*/
int ( * decode ) ( const char *mac, uint8_t *hw_addr );
};
/**
* Decode Base16-encoded MAC address
*
* @v mac Encoded MAC
* @v hw_addr MAC address to fill in
* @ret rc Return status code
*/
static int acpimac_decode_base16 ( const char *mac, uint8_t *hw_addr ) {
int len;
int rc;
/* Attempt to base16-decode MAC address */
len = base16_decode ( mac, hw_addr, ETH_ALEN );
if ( len < 0 ) {
rc = len;
DBGC ( colour, "ACPI could not decode base16 MAC \"%s\": %s\n",
mac, strerror ( rc ) );
return rc;
}
return 0;
}
/**
* Decode raw MAC address
*
* @v mac Encoded MAC
* @v hw_addr MAC address to fill in
* @ret rc Return status code
*/
static int acpimac_decode_raw ( const char *mac, uint8_t *hw_addr ) {
memcpy ( hw_addr, mac, ETH_ALEN );
return 0;
}
/** "_AUXMAC_" extraction mechanism */
static struct acpimac_extractor acpimac_auxmac = {
.prefix = "_AUXMAC_#",
.len = ( ETH_ALEN * 2 ),
.decode = acpimac_decode_base16,
};
/** "_RTXMAC_" extraction mechanism */
static struct acpimac_extractor acpimac_rtxmac = {
.prefix = "_RTXMAC_#",
.len = ETH_ALEN,
.decode = acpimac_decode_raw,
};
/**
* Extract MAC address from DSDT/SSDT
*
* @v zsdt DSDT or SSDT
* @v len Length of DSDT/SSDT
* @v offset Offset of signature within DSDT/SSDT
* @v data Data buffer
* @v extractor ACPI MAC address extractor
* @ret rc Return status code
*
* Some vendors provide a "system MAC address" within the DSDT/SSDT,
* to be used to override the MAC address for a USB docking station.
*
* A full implementation would require an ACPI bytecode interpreter,
* since at least one OEM allows the MAC address to be constructed by
* executable ACPI bytecode (rather than a fixed data structure).
*
* We instead attempt to extract a plausible-looking "_AUXMAC_#.....#"
* string that appears shortly after an "AMAC" or "MACA" signature.
* This should work for most implementations encountered in practice.
*/
static int acpimac_extract ( userptr_t zsdt, size_t len, size_t offset,
void *data, struct acpimac_extractor *extractor ){
size_t prefix_len = strlen ( extractor->prefix );
uint8_t *hw_addr = data;
size_t skip = 0;
char buf[ prefix_len + extractor->len + 1 /* "#" */ + 1 /* NUL */ ];
char *mac = &buf[prefix_len];
int rc;
/* Skip signature and at least one tag byte */
offset += ( 4 /* signature */ + 1 /* tag byte */ );
/* Scan for suitable string close to signature */
for ( skip = 0 ;
( ( skip < ACPIMAC_MAX_SKIP ) &&
( offset + skip + sizeof ( buf ) ) <= len ) ;
skip++ ) {
/* Read value */
copy_from_user ( buf, zsdt, ( offset + skip ),
sizeof ( buf ) );
/* Check for expected format */
if ( memcmp ( buf, extractor->prefix, prefix_len ) != 0 )
continue;
if ( buf[ sizeof ( buf ) - 2 ] != '#' )
continue;
if ( buf[ sizeof ( buf ) - 1 ] != '\0' )
continue;
DBGC ( colour, "ACPI found MAC:\n" );
DBGC_HDA ( colour, ( offset + skip ), buf, sizeof ( buf ) );
/* Terminate MAC address string */
mac[extractor->len] = '\0';
/* Decode MAC address */
if ( ( rc = extractor->decode ( mac, hw_addr ) ) != 0 )
return rc;
/* Check MAC address validity */
if ( ! is_valid_ether_addr ( hw_addr ) ) {
DBGC ( colour, "ACPI has invalid MAC %s\n",
eth_ntoa ( hw_addr ) );
return -EINVAL;
}
return 0;
}
return -ENOENT;
}
/**
* Extract "_AUXMAC_" MAC address from DSDT/SSDT
*
* @v zsdt DSDT or SSDT
* @v len Length of DSDT/SSDT
* @v offset Offset of signature within DSDT/SSDT
* @v data Data buffer
* @ret rc Return status code
*/
static int acpimac_extract_auxmac ( userptr_t zsdt, size_t len, size_t offset,
void *data ) {
return acpimac_extract ( zsdt, len, offset, data, &acpimac_auxmac );
}
/**
* Extract "_RTXMAC_" MAC address from DSDT/SSDT
*
* @v zsdt DSDT or SSDT
* @v len Length of DSDT/SSDT
* @v offset Offset of signature within DSDT/SSDT
* @v data Data buffer
* @ret rc Return status code
*/
static int acpimac_extract_rtxmac ( userptr_t zsdt, size_t len, size_t offset,
void *data ) {
return acpimac_extract ( zsdt, len, offset, data, &acpimac_rtxmac );
}
/**
* Extract MAC address from DSDT/SSDT
*
* @v hw_addr MAC address to fill in
* @ret rc Return status code
*/
int acpi_mac ( uint8_t *hw_addr ) {
int rc;
/* Look for an "AMAC" address */
if ( ( rc = acpi_extract ( AMAC_SIGNATURE, hw_addr,
acpimac_extract_auxmac ) ) == 0 )
return 0;
/* Look for a "MACA" address */
if ( ( rc = acpi_extract ( MACA_SIGNATURE, hw_addr,
acpimac_extract_auxmac ) ) == 0 )
return 0;
/* Look for a "RTMA" address */
if ( ( rc = acpi_extract ( RTMA_SIGNATURE, hw_addr,
acpimac_extract_rtxmac ) ) == 0 )
return 0;
return -ENOENT;
}
/**
* Fetch system MAC address setting
*
* @v data Buffer to fill with setting data
* @v len Length of buffer
* @ret len Length of setting data, or negative error
*/
static int sysmac_fetch ( void *data, size_t len ) {
uint8_t mac[ETH_ALEN];
int rc;
/* Try fetching ACPI MAC address */
if ( ( rc = acpi_mac ( mac ) ) != 0 )
return rc;
/* Return MAC address */
if ( len > sizeof ( mac ) )
len = sizeof ( mac );
memcpy ( data, mac, len );
return ( sizeof ( mac ) );
}
/** System MAC address setting */
const struct setting sysmac_setting __setting ( SETTING_MISC, sysmac ) = {
.name = "sysmac",
.description = "System MAC",
.type = &setting_type_hex,
.scope = &builtin_scope,
};
/** System MAC address built-in setting */
struct builtin_setting sysmac_builtin_setting __builtin_setting = {
.setting = &sysmac_setting,
.fetch = sysmac_fetch,
};
