2019-06-04 10:10:52 +02:00
// SPDX-License-Identifier: GPL-2.0-only
2017-02-03 12:55:33 -05:00
/*
* Copyright 2016 Broadcom
*/
# include <linux/kernel.h>
# include <linux/string.h>
# include "util.h"
# include "spu.h"
# include "spum.h"
# include "cipher.h"
char * hash_alg_name [ ] = { " None " , " md5 " , " sha1 " , " sha224 " , " sha256 " , " aes " ,
" sha384 " , " sha512 " , " sha3_224 " , " sha3_256 " , " sha3_384 " , " sha3_512 " } ;
char * aead_alg_name [ ] = { " ccm(aes) " , " gcm(aes) " , " authenc " } ;
/* Assumes SPU-M messages are in big endian */
void spum_dump_msg_hdr ( u8 * buf , unsigned int buf_len )
{
u8 * ptr = buf ;
struct SPUHEADER * spuh = ( struct SPUHEADER * ) buf ;
unsigned int hash_key_len = 0 ;
unsigned int hash_state_len = 0 ;
unsigned int cipher_key_len = 0 ;
unsigned int iv_len ;
u32 pflags ;
u32 cflags ;
u32 ecf ;
u32 cipher_alg ;
u32 cipher_mode ;
u32 cipher_type ;
u32 hash_alg ;
u32 hash_mode ;
u32 hash_type ;
u32 sctx_size ; /* SCTX length in words */
u32 sctx_pl_len ; /* SCTX payload length in bytes */
packet_log ( " \n " ) ;
packet_log ( " SPU Message header %p len: %u \n " , buf , buf_len ) ;
/* ========== Decode MH ========== */
packet_log ( " MH 0x%08x \n " , be32_to_cpu ( * ( ( u32 * ) ptr ) ) ) ;
if ( spuh - > mh . flags & MH_SCTX_PRES )
packet_log ( " SCTX present \n " ) ;
if ( spuh - > mh . flags & MH_BDESC_PRES )
packet_log ( " BDESC present \n " ) ;
if ( spuh - > mh . flags & MH_MFM_PRES )
packet_log ( " MFM present \n " ) ;
if ( spuh - > mh . flags & MH_BD_PRES )
packet_log ( " BD present \n " ) ;
if ( spuh - > mh . flags & MH_HASH_PRES )
packet_log ( " HASH present \n " ) ;
if ( spuh - > mh . flags & MH_SUPDT_PRES )
packet_log ( " SUPDT present \n " ) ;
packet_log ( " Opcode 0x%02x \n " , spuh - > mh . op_code ) ;
ptr + = sizeof ( spuh - > mh ) + sizeof ( spuh - > emh ) ; /* skip emh. unused */
/* ========== Decode SCTX ========== */
if ( spuh - > mh . flags & MH_SCTX_PRES ) {
pflags = be32_to_cpu ( spuh - > sa . proto_flags ) ;
packet_log ( " SCTX[0] 0x%08x \n " , pflags ) ;
sctx_size = pflags & SCTX_SIZE ;
packet_log ( " Size %u words \n " , sctx_size ) ;
cflags = be32_to_cpu ( spuh - > sa . cipher_flags ) ;
packet_log ( " SCTX[1] 0x%08x \n " , cflags ) ;
packet_log ( " Inbound:%lu (1:decrypt/vrfy 0:encrypt/auth) \n " ,
( cflags & CIPHER_INBOUND ) > > CIPHER_INBOUND_SHIFT ) ;
packet_log ( " Order:%lu (1:AuthFirst 0:EncFirst) \n " ,
( cflags & CIPHER_ORDER ) > > CIPHER_ORDER_SHIFT ) ;
packet_log ( " ICV_IS_512:%lx \n " ,
( cflags & ICV_IS_512 ) > > ICV_IS_512_SHIFT ) ;
cipher_alg = ( cflags & CIPHER_ALG ) > > CIPHER_ALG_SHIFT ;
cipher_mode = ( cflags & CIPHER_MODE ) > > CIPHER_MODE_SHIFT ;
cipher_type = ( cflags & CIPHER_TYPE ) > > CIPHER_TYPE_SHIFT ;
packet_log ( " Crypto Alg:%u Mode:%u Type:%u \n " ,
cipher_alg , cipher_mode , cipher_type ) ;
hash_alg = ( cflags & HASH_ALG ) > > HASH_ALG_SHIFT ;
hash_mode = ( cflags & HASH_MODE ) > > HASH_MODE_SHIFT ;
hash_type = ( cflags & HASH_TYPE ) > > HASH_TYPE_SHIFT ;
packet_log ( " Hash Alg:%x Mode:%x Type:%x \n " ,
hash_alg , hash_mode , hash_type ) ;
packet_log ( " UPDT_Offset:%u \n " , cflags & UPDT_OFST ) ;
ecf = be32_to_cpu ( spuh - > sa . ecf ) ;
packet_log ( " SCTX[2] 0x%08x \n " , ecf ) ;
packet_log ( " WriteICV:%lu CheckICV:%lu ICV_SIZE:%u " ,
( ecf & INSERT_ICV ) > > INSERT_ICV_SHIFT ,
( ecf & CHECK_ICV ) > > CHECK_ICV_SHIFT ,
( ecf & ICV_SIZE ) > > ICV_SIZE_SHIFT ) ;
packet_log ( " BD_SUPPRESS:%lu \n " ,
( ecf & BD_SUPPRESS ) > > BD_SUPPRESS_SHIFT ) ;
packet_log ( " SCTX_IV:%lu ExplicitIV:%lu GenIV:%lu " ,
( ecf & SCTX_IV ) > > SCTX_IV_SHIFT ,
( ecf & EXPLICIT_IV ) > > EXPLICIT_IV_SHIFT ,
( ecf & GEN_IV ) > > GEN_IV_SHIFT ) ;
packet_log ( " IV_OV_OFST:%lu EXP_IV_SIZE:%u \n " ,
( ecf & IV_OFFSET ) > > IV_OFFSET_SHIFT ,
ecf & EXP_IV_SIZE ) ;
ptr + = sizeof ( struct SCTX ) ;
if ( hash_alg & & hash_mode ) {
char * name = " NONE " ;
switch ( hash_alg ) {
case HASH_ALG_MD5 :
hash_key_len = 16 ;
name = " MD5 " ;
break ;
case HASH_ALG_SHA1 :
hash_key_len = 20 ;
name = " SHA1 " ;
break ;
case HASH_ALG_SHA224 :
hash_key_len = 28 ;
name = " SHA224 " ;
break ;
case HASH_ALG_SHA256 :
hash_key_len = 32 ;
name = " SHA256 " ;
break ;
case HASH_ALG_SHA384 :
hash_key_len = 48 ;
name = " SHA384 " ;
break ;
case HASH_ALG_SHA512 :
hash_key_len = 64 ;
name = " SHA512 " ;
break ;
case HASH_ALG_AES :
hash_key_len = 0 ;
name = " AES " ;
break ;
case HASH_ALG_NONE :
break ;
}
packet_log ( " Auth Key Type:%s Length:%u Bytes \n " ,
name , hash_key_len ) ;
packet_dump ( " KEY: " , ptr , hash_key_len ) ;
ptr + = hash_key_len ;
} else if ( ( hash_alg = = HASH_ALG_AES ) & &
( hash_mode = = HASH_MODE_XCBC ) ) {
char * name = " NONE " ;
switch ( cipher_type ) {
case CIPHER_TYPE_AES128 :
hash_key_len = 16 ;
name = " AES128-XCBC " ;
break ;
case CIPHER_TYPE_AES192 :
hash_key_len = 24 ;
name = " AES192-XCBC " ;
break ;
case CIPHER_TYPE_AES256 :
hash_key_len = 32 ;
name = " AES256-XCBC " ;
break ;
}
packet_log ( " Auth Key Type:%s Length:%u Bytes \n " ,
name , hash_key_len ) ;
packet_dump ( " KEY: " , ptr , hash_key_len ) ;
ptr + = hash_key_len ;
}
if ( hash_alg & & ( hash_mode = = HASH_MODE_NONE ) & &
( hash_type = = HASH_TYPE_UPDT ) ) {
char * name = " NONE " ;
switch ( hash_alg ) {
case HASH_ALG_MD5 :
hash_state_len = 16 ;
name = " MD5 " ;
break ;
case HASH_ALG_SHA1 :
hash_state_len = 20 ;
name = " SHA1 " ;
break ;
case HASH_ALG_SHA224 :
hash_state_len = 32 ;
name = " SHA224 " ;
break ;
case HASH_ALG_SHA256 :
hash_state_len = 32 ;
name = " SHA256 " ;
break ;
case HASH_ALG_SHA384 :
hash_state_len = 48 ;
name = " SHA384 " ;
break ;
case HASH_ALG_SHA512 :
hash_state_len = 64 ;
name = " SHA512 " ;
break ;
case HASH_ALG_AES :
hash_state_len = 0 ;
name = " AES " ;
break ;
case HASH_ALG_NONE :
break ;
}
packet_log ( " Auth State Type:%s Length:%u Bytes \n " ,
name , hash_state_len ) ;
packet_dump ( " State: " , ptr , hash_state_len ) ;
ptr + = hash_state_len ;
}
if ( cipher_alg ) {
char * name = " NONE " ;
switch ( cipher_alg ) {
case CIPHER_ALG_DES :
cipher_key_len = 8 ;
name = " DES " ;
break ;
case CIPHER_ALG_3DES :
cipher_key_len = 24 ;
name = " 3DES " ;
break ;
case CIPHER_ALG_RC4 :
cipher_key_len = 260 ;
name = " ARC4 " ;
break ;
case CIPHER_ALG_AES :
switch ( cipher_type ) {
case CIPHER_TYPE_AES128 :
cipher_key_len = 16 ;
name = " AES128 " ;
break ;
case CIPHER_TYPE_AES192 :
cipher_key_len = 24 ;
name = " AES192 " ;
break ;
case CIPHER_TYPE_AES256 :
cipher_key_len = 32 ;
name = " AES256 " ;
break ;
}
break ;
case CIPHER_ALG_NONE :
break ;
}
packet_log ( " Cipher Key Type:%s Length:%u Bytes \n " ,
name , cipher_key_len ) ;
/* XTS has two keys */
if ( cipher_mode = = CIPHER_MODE_XTS ) {
packet_dump ( " KEY2: " , ptr , cipher_key_len ) ;
ptr + = cipher_key_len ;
packet_dump ( " KEY1: " , ptr , cipher_key_len ) ;
ptr + = cipher_key_len ;
cipher_key_len * = 2 ;
} else {
packet_dump ( " KEY: " , ptr , cipher_key_len ) ;
ptr + = cipher_key_len ;
}
if ( ecf & SCTX_IV ) {
sctx_pl_len = sctx_size * sizeof ( u32 ) -
sizeof ( struct SCTX ) ;
iv_len = sctx_pl_len -
( hash_key_len + hash_state_len +
cipher_key_len ) ;
packet_log ( " IV Length:%u Bytes \n " , iv_len ) ;
packet_dump ( " IV: " , ptr , iv_len ) ;
ptr + = iv_len ;
}
}
}
/* ========== Decode BDESC ========== */
if ( spuh - > mh . flags & MH_BDESC_PRES ) {
# ifdef DEBUG
struct BDESC_HEADER * bdesc = ( struct BDESC_HEADER * ) ptr ;
# endif
packet_log ( " BDESC[0] 0x%08x \n " , be32_to_cpu ( * ( ( u32 * ) ptr ) ) ) ;
packet_log ( " OffsetMAC:%u LengthMAC:%u \n " ,
be16_to_cpu ( bdesc - > offset_mac ) ,
be16_to_cpu ( bdesc - > length_mac ) ) ;
ptr + = sizeof ( u32 ) ;
packet_log ( " BDESC[1] 0x%08x \n " , be32_to_cpu ( * ( ( u32 * ) ptr ) ) ) ;
packet_log ( " OffsetCrypto:%u LengthCrypto:%u \n " ,
be16_to_cpu ( bdesc - > offset_crypto ) ,
be16_to_cpu ( bdesc - > length_crypto ) ) ;
ptr + = sizeof ( u32 ) ;
packet_log ( " BDESC[2] 0x%08x \n " , be32_to_cpu ( * ( ( u32 * ) ptr ) ) ) ;
packet_log ( " OffsetICV:%u OffsetIV:%u \n " ,
be16_to_cpu ( bdesc - > offset_icv ) ,
be16_to_cpu ( bdesc - > offset_iv ) ) ;
ptr + = sizeof ( u32 ) ;
}
/* ========== Decode BD ========== */
if ( spuh - > mh . flags & MH_BD_PRES ) {
# ifdef DEBUG
struct BD_HEADER * bd = ( struct BD_HEADER * ) ptr ;
# endif
packet_log ( " BD[0] 0x%08x \n " , be32_to_cpu ( * ( ( u32 * ) ptr ) ) ) ;
packet_log ( " Size:%ubytes PrevLength:%u \n " ,
be16_to_cpu ( bd - > size ) , be16_to_cpu ( bd - > prev_length ) ) ;
ptr + = 4 ;
}
/* Double check sanity */
if ( buf + buf_len ! = ptr ) {
packet_log ( " Packet parsed incorrectly. " ) ;
packet_log ( " buf:%p buf_len:%u buf+buf_len:%p ptr:%p \n " ,
buf , buf_len , buf + buf_len , ptr ) ;
}
packet_log ( " \n " ) ;
}
/**
* spum_ns2_ctx_max_payload ( ) - Determine the max length of the payload for a
* SPU message for a given cipher and hash alg context .
* @ cipher_alg : The cipher algorithm
* @ cipher_mode : The cipher mode
* @ blocksize : The size of a block of data for this algo
*
* The max payload must be a multiple of the blocksize so that if a request is
* too large to fit in a single SPU message , the request can be broken into
* max_payload sized chunks . Each chunk must be a multiple of blocksize .
*
* Return : Max payload length in bytes
*/
u32 spum_ns2_ctx_max_payload ( enum spu_cipher_alg cipher_alg ,
enum spu_cipher_mode cipher_mode ,
unsigned int blocksize )
{
u32 max_payload = SPUM_NS2_MAX_PAYLOAD ;
u32 excess ;
/* In XTS on SPU-M, we'll need to insert tweak before input data */
if ( cipher_mode = = CIPHER_MODE_XTS )
max_payload - = SPU_XTS_TWEAK_SIZE ;
excess = max_payload % blocksize ;
return max_payload - excess ;
}
/**
* spum_nsp_ctx_max_payload ( ) - Determine the max length of the payload for a
* SPU message for a given cipher and hash alg context .
* @ cipher_alg : The cipher algorithm
* @ cipher_mode : The cipher mode
* @ blocksize : The size of a block of data for this algo
*
* The max payload must be a multiple of the blocksize so that if a request is
* too large to fit in a single SPU message , the request can be broken into
* max_payload sized chunks . Each chunk must be a multiple of blocksize .
*
* Return : Max payload length in bytes
*/
u32 spum_nsp_ctx_max_payload ( enum spu_cipher_alg cipher_alg ,
enum spu_cipher_mode cipher_mode ,
unsigned int blocksize )
{
u32 max_payload = SPUM_NSP_MAX_PAYLOAD ;
u32 excess ;
/* In XTS on SPU-M, we'll need to insert tweak before input data */
if ( cipher_mode = = CIPHER_MODE_XTS )
max_payload - = SPU_XTS_TWEAK_SIZE ;
excess = max_payload % blocksize ;
return max_payload - excess ;
}
/** spum_payload_length() - Given a SPU-M message header, extract the payload
* length .
* @ spu_hdr : Start of SPU header
*
* Assumes just MH , EMH , BD ( no SCTX , BDESC . Works for response frames .
*
* Return : payload length in bytes
*/
u32 spum_payload_length ( u8 * spu_hdr )
{
struct BD_HEADER * bd ;
u32 pl_len ;
/* Find BD header. skip MH, EMH */
bd = ( struct BD_HEADER * ) ( spu_hdr + 8 ) ;
pl_len = be16_to_cpu ( bd - > size ) ;
return pl_len ;
}
/**
* spum_response_hdr_len ( ) - Given the length of the hash key and encryption
* key , determine the expected length of a SPU response header .
* @ auth_key_len : authentication key length ( bytes )
* @ enc_key_len : encryption key length ( bytes )
* @ is_hash : true if response message is for a hash operation
*
* Return : length of SPU response header ( bytes )
*/
u16 spum_response_hdr_len ( u16 auth_key_len , u16 enc_key_len , bool is_hash )
{
if ( is_hash )
return SPU_HASH_RESP_HDR_LEN ;
else
return SPU_RESP_HDR_LEN ;
}
/**
* spum_hash_pad_len ( ) - Calculate the length of hash padding required to extend
* data to a full block size .
* @ hash_alg : hash algorithm
* @ hash_mode : hash mode
* @ chunksize : length of data , in bytes
* @ hash_block_size : size of a block of data for hash algorithm
*
* Reserve space for 1 byte ( 0x80 ) start of pad and the total length as u64
*
* Return : length of hash pad in bytes
*/
u16 spum_hash_pad_len ( enum hash_alg hash_alg , enum hash_mode hash_mode ,
u32 chunksize , u16 hash_block_size )
{
unsigned int length_len ;
unsigned int used_space_last_block ;
int hash_pad_len ;
/* AES-XCBC hash requires just padding to next block boundary */
if ( ( hash_alg = = HASH_ALG_AES ) & & ( hash_mode = = HASH_MODE_XCBC ) ) {
used_space_last_block = chunksize % hash_block_size ;
hash_pad_len = hash_block_size - used_space_last_block ;
if ( hash_pad_len > = hash_block_size )
hash_pad_len - = hash_block_size ;
return hash_pad_len ;
}
used_space_last_block = chunksize % hash_block_size + 1 ;
if ( ( hash_alg = = HASH_ALG_SHA384 ) | | ( hash_alg = = HASH_ALG_SHA512 ) )
length_len = 2 * sizeof ( u64 ) ;
else
length_len = sizeof ( u64 ) ;
used_space_last_block + = length_len ;
hash_pad_len = hash_block_size - used_space_last_block ;
if ( hash_pad_len < 0 )
hash_pad_len + = hash_block_size ;
hash_pad_len + = 1 + length_len ;
return hash_pad_len ;
}
/**
* spum_gcm_ccm_pad_len ( ) - Determine the required length of GCM or CCM padding .
* @ cipher_mode : Algo type
* @ data_size : Length of plaintext ( bytes )
*
* @ Return : Length of padding , in bytes
*/
u32 spum_gcm_ccm_pad_len ( enum spu_cipher_mode cipher_mode ,
unsigned int data_size )
{
u32 pad_len = 0 ;
u32 m1 = SPU_GCM_CCM_ALIGN - 1 ;
if ( ( cipher_mode = = CIPHER_MODE_GCM ) | |
( cipher_mode = = CIPHER_MODE_CCM ) )
pad_len = ( ( data_size + m1 ) & ~ m1 ) - data_size ;
return pad_len ;
}
/**
* spum_assoc_resp_len ( ) - Determine the size of the receive buffer required to
* catch associated data .
* @ cipher_mode : cipher mode
* @ assoc_len : length of associated data ( bytes )
* @ iv_len : length of IV ( bytes )
* @ is_encrypt : true if encrypting . false if decrypting .
*
* Return : length of associated data in response message ( bytes )
*/
u32 spum_assoc_resp_len ( enum spu_cipher_mode cipher_mode ,
unsigned int assoc_len , unsigned int iv_len ,
bool is_encrypt )
{
u32 buflen = 0 ;
u32 pad ;
if ( assoc_len )
buflen = assoc_len ;
if ( cipher_mode = = CIPHER_MODE_GCM ) {
/* AAD needs to be padded in responses too */
pad = spum_gcm_ccm_pad_len ( cipher_mode , buflen ) ;
buflen + = pad ;
}
if ( cipher_mode = = CIPHER_MODE_CCM ) {
/*
* AAD needs to be padded in responses too
* for CCM , len + 2 needs to be 128 - bit aligned .
*/
pad = spum_gcm_ccm_pad_len ( cipher_mode , buflen + 2 ) ;
buflen + = pad ;
}
return buflen ;
}
/**
* spu_aead_ivlen ( ) - Calculate the length of the AEAD IV to be included
* in a SPU request after the AAD and before the payload .
* @ cipher_mode : cipher mode
* @ iv_ctr_len : initialization vector length in bytes
*
* In Linux ~ 4.2 and later , the assoc_data sg includes the IV . So no need
* to include the IV as a separate field in the SPU request msg .
*
* Return : Length of AEAD IV in bytes
*/
u8 spum_aead_ivlen ( enum spu_cipher_mode cipher_mode , u16 iv_len )
{
return 0 ;
}
/**
* spum_hash_type ( ) - Determine the type of hash operation .
* @ src_sent : The number of bytes in the current request that have already
* been sent to the SPU to be hashed .
*
* We do not use HASH_TYPE_FULL for requests that fit in a single SPU message .
* Using FULL causes failures ( such as when the string to be hashed is empty ) .
* For similar reasons , we never use HASH_TYPE_FIN . Instead , submit messages
* as INIT or UPDT and do the hash padding in sw .
*/
enum hash_type spum_hash_type ( u32 src_sent )
{
return src_sent ? HASH_TYPE_UPDT : HASH_TYPE_INIT ;
}
/**
* spum_digest_size ( ) - Determine the size of a hash digest to expect the SPU to
* return .
* alg_digest_size : Number of bytes in the final digest for the given algo
* alg : The hash algorithm
* htype : Type of hash operation ( init , update , full , etc )
*
* When doing incremental hashing for an algorithm with a truncated hash
* ( e . g . , SHA224 ) , the SPU returns the full digest so that it can be fed back as
* a partial result for the next chunk .
*/
u32 spum_digest_size ( u32 alg_digest_size , enum hash_alg alg ,
enum hash_type htype )
{
u32 digestsize = alg_digest_size ;
/* SPU returns complete digest when doing incremental hash and truncated
* hash algo .
*/
if ( ( htype = = HASH_TYPE_INIT ) | | ( htype = = HASH_TYPE_UPDT ) ) {
if ( alg = = HASH_ALG_SHA224 )
digestsize = SHA256_DIGEST_SIZE ;
else if ( alg = = HASH_ALG_SHA384 )
digestsize = SHA512_DIGEST_SIZE ;
}
return digestsize ;
}
/**
* spum_create_request ( ) - Build a SPU request message header , up to and
* including the BD header . Construct the message starting at spu_hdr . Caller
* should allocate this buffer in DMA - able memory at least SPU_HEADER_ALLOC_LEN
* bytes long .
* @ spu_hdr : Start of buffer where SPU request header is to be written
* @ req_opts : SPU request message options
* @ cipher_parms : Parameters related to cipher algorithm
* @ hash_parms : Parameters related to hash algorithm
* @ aead_parms : Parameters related to AEAD operation
* @ data_size : Length of data to be encrypted or authenticated . If AEAD , does
* not include length of AAD .
* Return : the length of the SPU header in bytes . 0 if an error occurs .
*/
u32 spum_create_request ( u8 * spu_hdr ,
struct spu_request_opts * req_opts ,
struct spu_cipher_parms * cipher_parms ,
struct spu_hash_parms * hash_parms ,
struct spu_aead_parms * aead_parms ,
unsigned int data_size )
{
struct SPUHEADER * spuh ;
struct BDESC_HEADER * bdesc ;
struct BD_HEADER * bd ;
u8 * ptr ;
u32 protocol_bits = 0 ;
u32 cipher_bits = 0 ;
u32 ecf_bits = 0 ;
u8 sctx_words = 0 ;
unsigned int buf_len = 0 ;
/* size of the cipher payload */
unsigned int cipher_len = hash_parms - > prebuf_len + data_size +
hash_parms - > pad_len ;
/* offset of prebuf or data from end of BD header */
unsigned int cipher_offset = aead_parms - > assoc_size +
aead_parms - > iv_len + aead_parms - > aad_pad_len ;
/* total size of the DB data (without STAT word padding) */
unsigned int real_db_size = spu_real_db_size ( aead_parms - > assoc_size ,
aead_parms - > iv_len ,
hash_parms - > prebuf_len ,
data_size ,
aead_parms - > aad_pad_len ,
aead_parms - > data_pad_len ,
hash_parms - > pad_len ) ;
unsigned int auth_offset = 0 ;
unsigned int offset_iv = 0 ;
/* size/offset of the auth payload */
unsigned int auth_len ;
auth_len = real_db_size ;
if ( req_opts - > is_aead & & req_opts - > is_inbound )
cipher_len - = hash_parms - > digestsize ;
if ( req_opts - > is_aead & & req_opts - > is_inbound )
auth_len - = hash_parms - > digestsize ;
if ( ( hash_parms - > alg = = HASH_ALG_AES ) & &
( hash_parms - > mode = = HASH_MODE_XCBC ) ) {
auth_len - = hash_parms - > pad_len ;
cipher_len - = hash_parms - > pad_len ;
}
flow_log ( " %s() \n " , __func__ ) ;
flow_log ( " in:%u authFirst:%u \n " ,
req_opts - > is_inbound , req_opts - > auth_first ) ;
flow_log ( " %s. cipher alg:%u mode:%u type %u \n " ,
spu_alg_name ( cipher_parms - > alg , cipher_parms - > mode ) ,
cipher_parms - > alg , cipher_parms - > mode , cipher_parms - > type ) ;
flow_log ( " key: %d \n " , cipher_parms - > key_len ) ;
flow_dump ( " key: " , cipher_parms - > key_buf , cipher_parms - > key_len ) ;
flow_log ( " iv: %d \n " , cipher_parms - > iv_len ) ;
flow_dump ( " iv: " , cipher_parms - > iv_buf , cipher_parms - > iv_len ) ;
flow_log ( " auth alg:%u mode:%u type %u \n " ,
hash_parms - > alg , hash_parms - > mode , hash_parms - > type ) ;
flow_log ( " digestsize: %u \n " , hash_parms - > digestsize ) ;
flow_log ( " authkey: %d \n " , hash_parms - > key_len ) ;
flow_dump ( " authkey: " , hash_parms - > key_buf , hash_parms - > key_len ) ;
flow_log ( " assoc_size:%u \n " , aead_parms - > assoc_size ) ;
flow_log ( " prebuf_len:%u \n " , hash_parms - > prebuf_len ) ;
flow_log ( " data_size:%u \n " , data_size ) ;
flow_log ( " hash_pad_len:%u \n " , hash_parms - > pad_len ) ;
flow_log ( " real_db_size:%u \n " , real_db_size ) ;
flow_log ( " auth_offset:%u auth_len:%u cipher_offset:%u cipher_len:%u \n " ,
auth_offset , auth_len , cipher_offset , cipher_len ) ;
flow_log ( " aead_iv: %u \n " , aead_parms - > iv_len ) ;
/* starting out: zero the header (plus some) */
ptr = spu_hdr ;
memset ( ptr , 0 , sizeof ( struct SPUHEADER ) ) ;
/* format master header word */
/* Do not set the next bit even though the datasheet says to */
spuh = ( struct SPUHEADER * ) ptr ;
ptr + = sizeof ( struct SPUHEADER ) ;
buf_len + = sizeof ( struct SPUHEADER ) ;
spuh - > mh . op_code = SPU_CRYPTO_OPERATION_GENERIC ;
spuh - > mh . flags | = ( MH_SCTX_PRES | MH_BDESC_PRES | MH_BD_PRES ) ;
/* Format sctx word 0 (protocol_bits) */
sctx_words = 3 ; /* size in words */
/* Format sctx word 1 (cipher_bits) */
if ( req_opts - > is_inbound )
cipher_bits | = CIPHER_INBOUND ;
if ( req_opts - > auth_first )
cipher_bits | = CIPHER_ORDER ;
/* Set the crypto parameters in the cipher.flags */
cipher_bits | = cipher_parms - > alg < < CIPHER_ALG_SHIFT ;
cipher_bits | = cipher_parms - > mode < < CIPHER_MODE_SHIFT ;
cipher_bits | = cipher_parms - > type < < CIPHER_TYPE_SHIFT ;
/* Set the auth parameters in the cipher.flags */
cipher_bits | = hash_parms - > alg < < HASH_ALG_SHIFT ;
cipher_bits | = hash_parms - > mode < < HASH_MODE_SHIFT ;
cipher_bits | = hash_parms - > type < < HASH_TYPE_SHIFT ;
/*
* Format sctx extensions if required , and update main fields if
* required )
*/
if ( hash_parms - > alg ) {
/* Write the authentication key material if present */
if ( hash_parms - > key_len ) {
memcpy ( ptr , hash_parms - > key_buf , hash_parms - > key_len ) ;
ptr + = hash_parms - > key_len ;
buf_len + = hash_parms - > key_len ;
sctx_words + = hash_parms - > key_len / 4 ;
}
if ( ( cipher_parms - > mode = = CIPHER_MODE_GCM ) | |
( cipher_parms - > mode = = CIPHER_MODE_CCM ) )
/* unpadded length */
offset_iv = aead_parms - > assoc_size ;
/* if GCM/CCM we need to write ICV into the payload */
if ( ! req_opts - > is_inbound ) {
if ( ( cipher_parms - > mode = = CIPHER_MODE_GCM ) | |
( cipher_parms - > mode = = CIPHER_MODE_CCM ) )
ecf_bits | = 1 < < INSERT_ICV_SHIFT ;
} else {
ecf_bits | = CHECK_ICV ;
}
/* Inform the SPU of the ICV size (in words) */
if ( hash_parms - > digestsize = = 64 )
cipher_bits | = ICV_IS_512 ;
else
ecf_bits | =
( hash_parms - > digestsize / 4 ) < < ICV_SIZE_SHIFT ;
}
if ( req_opts - > bd_suppress )
ecf_bits | = BD_SUPPRESS ;
/* copy the encryption keys in the SAD entry */
if ( cipher_parms - > alg ) {
if ( cipher_parms - > key_len ) {
memcpy ( ptr , cipher_parms - > key_buf ,
cipher_parms - > key_len ) ;
ptr + = cipher_parms - > key_len ;
buf_len + = cipher_parms - > key_len ;
sctx_words + = cipher_parms - > key_len / 4 ;
}
/*
* if encrypting then set IV size , use SCTX IV unless no IV
* given here
*/
if ( cipher_parms - > iv_buf & & cipher_parms - > iv_len ) {
/* Use SCTX IV */
ecf_bits | = SCTX_IV ;
/* cipher iv provided so put it in here */
memcpy ( ptr , cipher_parms - > iv_buf , cipher_parms - > iv_len ) ;
ptr + = cipher_parms - > iv_len ;
buf_len + = cipher_parms - > iv_len ;
sctx_words + = cipher_parms - > iv_len / 4 ;
}
}
/*
* RFC4543 ( GMAC / ESP ) requires data to be sent as part of AAD
* so we need to override the BDESC parameters .
*/
if ( req_opts - > is_rfc4543 ) {
if ( req_opts - > is_inbound )
data_size - = hash_parms - > digestsize ;
offset_iv = aead_parms - > assoc_size + data_size ;
cipher_len = 0 ;
cipher_offset = offset_iv ;
auth_len = cipher_offset + aead_parms - > data_pad_len ;
}
/* write in the total sctx length now that we know it */
protocol_bits | = sctx_words ;
/* Endian adjust the SCTX */
spuh - > sa . proto_flags = cpu_to_be32 ( protocol_bits ) ;
spuh - > sa . cipher_flags = cpu_to_be32 ( cipher_bits ) ;
spuh - > sa . ecf = cpu_to_be32 ( ecf_bits ) ;
/* === create the BDESC section === */
bdesc = ( struct BDESC_HEADER * ) ptr ;
bdesc - > offset_mac = cpu_to_be16 ( auth_offset ) ;
bdesc - > length_mac = cpu_to_be16 ( auth_len ) ;
bdesc - > offset_crypto = cpu_to_be16 ( cipher_offset ) ;
bdesc - > length_crypto = cpu_to_be16 ( cipher_len ) ;
/*
* CCM in SPU - M requires that ICV not be in same 32 - bit word as data or
* padding . So account for padding as necessary .
*/
if ( cipher_parms - > mode = = CIPHER_MODE_CCM )
auth_len + = spum_wordalign_padlen ( auth_len ) ;
bdesc - > offset_icv = cpu_to_be16 ( auth_len ) ;
bdesc - > offset_iv = cpu_to_be16 ( offset_iv ) ;
ptr + = sizeof ( struct BDESC_HEADER ) ;
buf_len + = sizeof ( struct BDESC_HEADER ) ;
/* === no MFM section === */
/* === create the BD section === */
/* add the BD header */
bd = ( struct BD_HEADER * ) ptr ;
bd - > size = cpu_to_be16 ( real_db_size ) ;
bd - > prev_length = 0 ;
ptr + = sizeof ( struct BD_HEADER ) ;
buf_len + = sizeof ( struct BD_HEADER ) ;
packet_dump ( " SPU request header: " , spu_hdr , buf_len ) ;
return buf_len ;
}
/**
* spum_cipher_req_init ( ) - Build a SPU request message header , up to and
* including the BD header .
* @ spu_hdr : Start of SPU request header ( MH )
* @ cipher_parms : Parameters that describe the cipher request
*
* Construct the message starting at spu_hdr . Caller should allocate this buffer
* in DMA - able memory at least SPU_HEADER_ALLOC_LEN bytes long .
*
* Return : the length of the SPU header in bytes . 0 if an error occurs .
*/
u16 spum_cipher_req_init ( u8 * spu_hdr , struct spu_cipher_parms * cipher_parms )
{
struct SPUHEADER * spuh ;
u32 protocol_bits = 0 ;
u32 cipher_bits = 0 ;
u32 ecf_bits = 0 ;
u8 sctx_words = 0 ;
u8 * ptr = spu_hdr ;
flow_log ( " %s() \n " , __func__ ) ;
flow_log ( " cipher alg:%u mode:%u type %u \n " , cipher_parms - > alg ,
cipher_parms - > mode , cipher_parms - > type ) ;
flow_log ( " cipher_iv_len: %u \n " , cipher_parms - > iv_len ) ;
flow_log ( " key: %d \n " , cipher_parms - > key_len ) ;
flow_dump ( " key: " , cipher_parms - > key_buf , cipher_parms - > key_len ) ;
/* starting out: zero the header (plus some) */
memset ( spu_hdr , 0 , sizeof ( struct SPUHEADER ) ) ;
ptr + = sizeof ( struct SPUHEADER ) ;
/* format master header word */
/* Do not set the next bit even though the datasheet says to */
spuh = ( struct SPUHEADER * ) spu_hdr ;
spuh - > mh . op_code = SPU_CRYPTO_OPERATION_GENERIC ;
spuh - > mh . flags | = ( MH_SCTX_PRES | MH_BDESC_PRES | MH_BD_PRES ) ;
/* Format sctx word 0 (protocol_bits) */
sctx_words = 3 ; /* size in words */
/* copy the encryption keys in the SAD entry */
if ( cipher_parms - > alg ) {
if ( cipher_parms - > key_len ) {
ptr + = cipher_parms - > key_len ;
sctx_words + = cipher_parms - > key_len / 4 ;
}
/*
* if encrypting then set IV size , use SCTX IV unless no IV
* given here
*/
if ( cipher_parms - > iv_len ) {
/* Use SCTX IV */
ecf_bits | = SCTX_IV ;
ptr + = cipher_parms - > iv_len ;
sctx_words + = cipher_parms - > iv_len / 4 ;
}
}
/* Set the crypto parameters in the cipher.flags */
cipher_bits | = cipher_parms - > alg < < CIPHER_ALG_SHIFT ;
cipher_bits | = cipher_parms - > mode < < CIPHER_MODE_SHIFT ;
cipher_bits | = cipher_parms - > type < < CIPHER_TYPE_SHIFT ;
/* copy the encryption keys in the SAD entry */
if ( cipher_parms - > alg & & cipher_parms - > key_len )
memcpy ( spuh + 1 , cipher_parms - > key_buf , cipher_parms - > key_len ) ;
/* write in the total sctx length now that we know it */
protocol_bits | = sctx_words ;
/* Endian adjust the SCTX */
spuh - > sa . proto_flags = cpu_to_be32 ( protocol_bits ) ;
/* Endian adjust the SCTX */
spuh - > sa . cipher_flags = cpu_to_be32 ( cipher_bits ) ;
spuh - > sa . ecf = cpu_to_be32 ( ecf_bits ) ;
packet_dump ( " SPU request header: " , spu_hdr ,
sizeof ( struct SPUHEADER ) ) ;
return sizeof ( struct SPUHEADER ) + cipher_parms - > key_len +
cipher_parms - > iv_len + sizeof ( struct BDESC_HEADER ) +
sizeof ( struct BD_HEADER ) ;
}
/**
* spum_cipher_req_finish ( ) - Finish building a SPU request message header for a
* block cipher request . Assumes much of the header was already filled in at
* setkey ( ) time in spu_cipher_req_init ( ) .
* @ spu_hdr : Start of the request message header ( MH field )
* @ spu_req_hdr_len : Length in bytes of the SPU request header
* @ isInbound : 0 encrypt , 1 decrypt
* @ cipher_parms : Parameters describing cipher operation to be performed
* @ update_key : If true , rewrite the cipher key in SCTX
* @ data_size : Length of the data in the BD field
*
* Assumes much of the header was already filled in at setkey ( ) time in
* spum_cipher_req_init ( ) .
* spum_cipher_req_init ( ) fills in the encryption key . For RC4 , when submitting
* a request for a non - first chunk , we use the 260 - byte SUPDT field from the
* previous response as the key . update_key is true for this case . Unused in all
* other cases .
*/
void spum_cipher_req_finish ( u8 * spu_hdr ,
u16 spu_req_hdr_len ,
unsigned int is_inbound ,
struct spu_cipher_parms * cipher_parms ,
bool update_key ,
unsigned int data_size )
{
struct SPUHEADER * spuh ;
struct BDESC_HEADER * bdesc ;
struct BD_HEADER * bd ;
u8 * bdesc_ptr = spu_hdr + spu_req_hdr_len -
( sizeof ( struct BD_HEADER ) + sizeof ( struct BDESC_HEADER ) ) ;
u32 cipher_bits ;
flow_log ( " %s() \n " , __func__ ) ;
flow_log ( " in: %u \n " , is_inbound ) ;
flow_log ( " cipher alg: %u, cipher_type: %u \n " , cipher_parms - > alg ,
cipher_parms - > type ) ;
if ( update_key ) {
flow_log ( " cipher key len: %u \n " , cipher_parms - > key_len ) ;
flow_dump ( " key: " , cipher_parms - > key_buf ,
cipher_parms - > key_len ) ;
}
/*
* In XTS mode , API puts " i " parameter ( block tweak ) in IV . For
* SPU - M , should be in start of the BD ; tx_sg_create ( ) copies it there .
* IV in SPU msg for SPU - M should be 0 , since that ' s the " j " parameter
* ( block ctr within larger data unit ) - given we can send entire disk
* block ( < = 4 KB ) in 1 SPU msg , don ' t need to use this parameter .
*/
if ( cipher_parms - > mode = = CIPHER_MODE_XTS )
memset ( cipher_parms - > iv_buf , 0 , cipher_parms - > iv_len ) ;
flow_log ( " iv len: %d \n " , cipher_parms - > iv_len ) ;
flow_dump ( " iv: " , cipher_parms - > iv_buf , cipher_parms - > iv_len ) ;
flow_log ( " data_size: %u \n " , data_size ) ;
/* format master header word */
/* Do not set the next bit even though the datasheet says to */
spuh = ( struct SPUHEADER * ) spu_hdr ;
/* cipher_bits was initialized at setkey time */
cipher_bits = be32_to_cpu ( spuh - > sa . cipher_flags ) ;
/* Format sctx word 1 (cipher_bits) */
if ( is_inbound )
cipher_bits | = CIPHER_INBOUND ;
else
cipher_bits & = ~ CIPHER_INBOUND ;
/* update encryption key for RC4 on non-first chunk */
if ( update_key ) {
spuh - > sa . cipher_flags | =
cipher_parms - > type < < CIPHER_TYPE_SHIFT ;
memcpy ( spuh + 1 , cipher_parms - > key_buf , cipher_parms - > key_len ) ;
}
if ( cipher_parms - > alg & & cipher_parms - > iv_buf & & cipher_parms - > iv_len )
/* cipher iv provided so put it in here */
memcpy ( bdesc_ptr - cipher_parms - > iv_len , cipher_parms - > iv_buf ,
cipher_parms - > iv_len ) ;
spuh - > sa . cipher_flags = cpu_to_be32 ( cipher_bits ) ;
/* === create the BDESC section === */
bdesc = ( struct BDESC_HEADER * ) bdesc_ptr ;
bdesc - > offset_mac = 0 ;
bdesc - > length_mac = 0 ;
bdesc - > offset_crypto = 0 ;
/* XTS mode, data_size needs to include tweak parameter */
if ( cipher_parms - > mode = = CIPHER_MODE_XTS )
bdesc - > length_crypto = cpu_to_be16 ( data_size +
SPU_XTS_TWEAK_SIZE ) ;
else
bdesc - > length_crypto = cpu_to_be16 ( data_size ) ;
bdesc - > offset_icv = 0 ;
bdesc - > offset_iv = 0 ;
/* === no MFM section === */
/* === create the BD section === */
/* add the BD header */
bd = ( struct BD_HEADER * ) ( bdesc_ptr + sizeof ( struct BDESC_HEADER ) ) ;
bd - > size = cpu_to_be16 ( data_size ) ;
/* XTS mode, data_size needs to include tweak parameter */
if ( cipher_parms - > mode = = CIPHER_MODE_XTS )
bd - > size = cpu_to_be16 ( data_size + SPU_XTS_TWEAK_SIZE ) ;
else
bd - > size = cpu_to_be16 ( data_size ) ;
bd - > prev_length = 0 ;
packet_dump ( " SPU request header: " , spu_hdr , spu_req_hdr_len ) ;
}
/**
* spum_request_pad ( ) - Create pad bytes at the end of the data .
* @ pad_start : Start of buffer where pad bytes are to be written
* @ gcm_ccm_padding : length of GCM / CCM padding , in bytes
* @ hash_pad_len : Number of bytes of padding extend data to full block
* @ auth_alg : authentication algorithm
* @ auth_mode : authentication mode
* @ total_sent : length inserted at end of hash pad
* @ status_padding : Number of bytes of padding to align STATUS word
*
* There may be three forms of pad :
* 1. GCM / CCM pad - for GCM / CCM mode ciphers , pad to 16 - byte alignment
* 2. hash pad - pad to a block length , with 0x80 data terminator and
* size at the end
* 3. STAT pad - to ensure the STAT field is 4 - byte aligned
*/
void spum_request_pad ( u8 * pad_start ,
u32 gcm_ccm_padding ,
u32 hash_pad_len ,
enum hash_alg auth_alg ,
enum hash_mode auth_mode ,
unsigned int total_sent , u32 status_padding )
{
u8 * ptr = pad_start ;
/* fix data alignent for GCM/CCM */
if ( gcm_ccm_padding > 0 ) {
flow_log ( " GCM: padding to 16 byte alignment: %u bytes \n " ,
gcm_ccm_padding ) ;
memset ( ptr , 0 , gcm_ccm_padding ) ;
ptr + = gcm_ccm_padding ;
}
if ( hash_pad_len > 0 ) {
/* clear the padding section */
memset ( ptr , 0 , hash_pad_len ) ;
if ( ( auth_alg = = HASH_ALG_AES ) & &
( auth_mode = = HASH_MODE_XCBC ) ) {
/* AES/XCBC just requires padding to be 0s */
ptr + = hash_pad_len ;
} else {
/* terminate the data */
* ptr = 0x80 ;
ptr + = ( hash_pad_len - sizeof ( u64 ) ) ;
/* add the size at the end as required per alg */
if ( auth_alg = = HASH_ALG_MD5 )
* ( u64 * ) ptr = cpu_to_le64 ( ( u64 ) total_sent * 8 ) ;
else /* SHA1, SHA2-224, SHA2-256 */
* ( u64 * ) ptr = cpu_to_be64 ( ( u64 ) total_sent * 8 ) ;
ptr + = sizeof ( u64 ) ;
}
}
/* pad to a 4byte alignment for STAT */
if ( status_padding > 0 ) {
flow_log ( " STAT: padding to 4 byte alignment: %u bytes \n " ,
status_padding ) ;
memset ( ptr , 0 , status_padding ) ;
ptr + = status_padding ;
}
}
/**
* spum_xts_tweak_in_payload ( ) - Indicate that SPUM DOES place the XTS tweak
* field in the packet payload ( rather than using IV )
*
* Return : 1
*/
u8 spum_xts_tweak_in_payload ( void )
{
return 1 ;
}
/**
* spum_tx_status_len ( ) - Return the length of the STATUS field in a SPU
* response message .
*
* Return : Length of STATUS field in bytes .
*/
u8 spum_tx_status_len ( void )
{
return SPU_TX_STATUS_LEN ;
}
/**
* spum_rx_status_len ( ) - Return the length of the STATUS field in a SPU
* response message .
*
* Return : Length of STATUS field in bytes .
*/
u8 spum_rx_status_len ( void )
{
return SPU_RX_STATUS_LEN ;
}
/**
* spum_status_process ( ) - Process the status from a SPU response message .
* @ statp : start of STATUS word
* Return :
* 0 - if status is good and response should be processed
* ! 0 - status indicates an error and response is invalid
*/
int spum_status_process ( u8 * statp )
{
u32 status ;
status = __be32_to_cpu ( * ( __be32 * ) statp ) ;
flow_log ( " SPU response STATUS %#08x \n " , status ) ;
if ( status & SPU_STATUS_ERROR_FLAG ) {
pr_err ( " %s() Warning: Error result from SPU: %#08x \n " ,
__func__ , status ) ;
if ( status & SPU_STATUS_INVALID_ICV )
return SPU_INVALID_ICV ;
return - EBADMSG ;
}
return 0 ;
}
/**
* spum_ccm_update_iv ( ) - Update the IV as per the requirements for CCM mode .
*
* @ digestsize : Digest size of this request
* @ cipher_parms : ( pointer to ) cipher parmaeters , includes IV buf & IV len
* @ assoclen : Length of AAD data
* @ chunksize : length of input data to be sent in this req
* @ is_encrypt : true if this is an output / encrypt operation
* @ is_esp : true if this is an ESP / RFC4309 operation
*
*/
void spum_ccm_update_iv ( unsigned int digestsize ,
struct spu_cipher_parms * cipher_parms ,
unsigned int assoclen ,
unsigned int chunksize ,
bool is_encrypt ,
bool is_esp )
{
u8 L ; /* L from CCM algorithm, length of plaintext data */
u8 mprime ; /* M' from CCM algo, (M - 2) / 2, where M=authsize */
u8 adata ;
if ( cipher_parms - > iv_len ! = CCM_AES_IV_SIZE ) {
pr_err ( " %s(): Invalid IV len %d for CCM mode, should be %d \n " ,
__func__ , cipher_parms - > iv_len , CCM_AES_IV_SIZE ) ;
return ;
}
/*
* IV needs to be formatted as follows :
*
* | Byte 0 | Bytes 1 - N | Bytes ( N + 1 ) - 15 |
* | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | Bits 7 - 0 | Bits 7 - 0 |
* | 0 | Ad ? | ( M - 2 ) / 2 | L - 1 | Nonce | Plaintext Length |
*
* Ad ? = 1 if AAD present , 0 if not present
* M = size of auth field , 8 , 12 , or 16 bytes ( SPU - M ) - or -
* 4 , 6 , 8 , 10 , 12 , 14 , 16 bytes ( SPU2 )
* L = Size of Plaintext Length field ; Nonce size = 15 - L
*
* It appears that the crypto API already expects the L - 1 portion
* to be set in the first byte of the IV , which implicitly determines
* the nonce size , and also fills in the nonce . But the other bits
* in byte 0 as well as the plaintext length need to be filled in .
*
* In rfc4309 / esp mode , L is not already in the supplied IV and
* we need to fill it in , as well as move the IV data to be after
* the salt
*/
if ( is_esp ) {
L = CCM_ESP_L_VALUE ; /* RFC4309 has fixed L */
} else {
/* L' = plaintext length - 1 so Plaintext length is L' + 1 */
L = ( ( cipher_parms - > iv_buf [ 0 ] & CCM_B0_L_PRIME ) > >
CCM_B0_L_PRIME_SHIFT ) + 1 ;
}
mprime = ( digestsize - 2 ) > > 1 ; /* M' = (M - 2) / 2 */
adata = ( assoclen > 0 ) ; /* adata = 1 if any associated data */
cipher_parms - > iv_buf [ 0 ] = ( adata < < CCM_B0_ADATA_SHIFT ) |
( mprime < < CCM_B0_M_PRIME_SHIFT ) |
( ( L - 1 ) < < CCM_B0_L_PRIME_SHIFT ) ;
/* Nonce is already filled in by crypto API, and is 15 - L bytes */
/* Don't include digest in plaintext size when decrypting */
if ( ! is_encrypt )
chunksize - = digestsize ;
/* Fill in length of plaintext, formatted to be L bytes long */
format_value_ccm ( chunksize , & cipher_parms - > iv_buf [ 15 - L + 1 ] , L ) ;
}
/**
* spum_wordalign_padlen ( ) - Given the length of a data field , determine the
* padding required to align the data following this field on a 4 - byte boundary .
* @ data_size : length of data field in bytes
*
* Return : length of status field padding , in bytes
*/
u32 spum_wordalign_padlen ( u32 data_size )
{
return ( ( data_size + 3 ) & ~ 3 ) - data_size ;
}