bitwise.c
/*
* (C) 2012 by Pablo Neira Ayuso <pablo@netfilter.org>
*
* 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
* (at your option) any later version.
*
* This code has been sponsored by Sophos Astaro <http://www.sophos.com>
*/
#include "internal.h"
#include <stdio.h>
#include <stdint.h>
#include <string.h> /* for memcpy */
#include <arpa/inet.h>
#include <errno.h>
#include <libmnl/libmnl.h>
#include <linux/netfilter/nf_tables.h>
#include <libnftnl/expr.h>
#include <libnftnl/rule.h>
struct nftnl_expr_bitwise {
enum nft_registers sreg;
enum nft_registers dreg;
enum nft_bitwise_ops op;
unsigned int len;
union nftnl_data_reg mask;
union nftnl_data_reg xor;
union nftnl_data_reg data;
};
static int
nftnl_expr_bitwise_set(struct nftnl_expr *e, uint16_t type,
const void *data, uint32_t data_len)
{
struct nftnl_expr_bitwise *bitwise = nftnl_expr_data(e);
switch(type) {
case NFTNL_EXPR_BITWISE_SREG:
memcpy(&bitwise->sreg, data, sizeof(bitwise->sreg));
break;
case NFTNL_EXPR_BITWISE_DREG:
memcpy(&bitwise->dreg, data, sizeof(bitwise->dreg));
break;
case NFTNL_EXPR_BITWISE_OP:
memcpy(&bitwise->op, data, sizeof(bitwise->op));
break;
case NFTNL_EXPR_BITWISE_LEN:
memcpy(&bitwise->len, data, sizeof(bitwise->len));
break;
case NFTNL_EXPR_BITWISE_MASK:
memcpy(&bitwise->mask.val, data, data_len);
bitwise->mask.len = data_len;
break;
case NFTNL_EXPR_BITWISE_XOR:
memcpy(&bitwise->xor.val, data, data_len);
bitwise->xor.len = data_len;
break;
case NFTNL_EXPR_BITWISE_DATA:
memcpy(&bitwise->data.val, data, data_len);
bitwise->data.len = data_len;
break;
default:
return -1;
}
return 0;
}
static const void *
nftnl_expr_bitwise_get(const struct nftnl_expr *e, uint16_t type,
uint32_t *data_len)
{
struct nftnl_expr_bitwise *bitwise = nftnl_expr_data(e);
switch(type) {
case NFTNL_EXPR_BITWISE_SREG:
*data_len = sizeof(bitwise->sreg);
return &bitwise->sreg;
case NFTNL_EXPR_BITWISE_DREG:
*data_len = sizeof(bitwise->dreg);
return &bitwise->dreg;
case NFTNL_EXPR_BITWISE_OP:
*data_len = sizeof(bitwise->op);
return &bitwise->op;
case NFTNL_EXPR_BITWISE_LEN:
*data_len = sizeof(bitwise->len);
return &bitwise->len;
case NFTNL_EXPR_BITWISE_MASK:
*data_len = bitwise->mask.len;
return &bitwise->mask.val;
case NFTNL_EXPR_BITWISE_XOR:
*data_len = bitwise->xor.len;
return &bitwise->xor.val;
case NFTNL_EXPR_BITWISE_DATA:
*data_len = bitwise->data.len;
return &bitwise->data.val;
}
return NULL;
}
static int nftnl_expr_bitwise_cb(const struct nlattr *attr, void *data)
{
const struct nlattr **tb = data;
int type = mnl_attr_get_type(attr);
if (mnl_attr_type_valid(attr, NFTA_BITWISE_MAX) < 0)
return MNL_CB_OK;
switch(type) {
case NFTA_BITWISE_SREG:
case NFTA_BITWISE_DREG:
case NFTA_BITWISE_OP:
case NFTA_BITWISE_LEN:
if (mnl_attr_validate(attr, MNL_TYPE_U32) < 0)
abi_breakage();
break;
case NFTA_BITWISE_MASK:
case NFTA_BITWISE_XOR:
case NFTA_BITWISE_DATA:
if (mnl_attr_validate(attr, MNL_TYPE_BINARY) < 0)
abi_breakage();
break;
}
tb[type] = attr;
return MNL_CB_OK;
}
static void
nftnl_expr_bitwise_build(struct nlmsghdr *nlh, const struct nftnl_expr *e)
{
struct nftnl_expr_bitwise *bitwise = nftnl_expr_data(e);
if (e->flags & (1 << NFTNL_EXPR_BITWISE_SREG))
mnl_attr_put_u32(nlh, NFTA_BITWISE_SREG, htonl(bitwise->sreg));
if (e->flags & (1 << NFTNL_EXPR_BITWISE_DREG))
mnl_attr_put_u32(nlh, NFTA_BITWISE_DREG, htonl(bitwise->dreg));
if (e->flags & (1 << NFTNL_EXPR_BITWISE_OP))
mnl_attr_put_u32(nlh, NFTA_BITWISE_OP, htonl(bitwise->op));
if (e->flags & (1 << NFTNL_EXPR_BITWISE_LEN))
mnl_attr_put_u32(nlh, NFTA_BITWISE_LEN, htonl(bitwise->len));
if (e->flags & (1 << NFTNL_EXPR_BITWISE_MASK)) {
struct nlattr *nest;
nest = mnl_attr_nest_start(nlh, NFTA_BITWISE_MASK);
mnl_attr_put(nlh, NFTA_DATA_VALUE, bitwise->mask.len,
bitwise->mask.val);
mnl_attr_nest_end(nlh, nest);
}
if (e->flags & (1 << NFTNL_EXPR_BITWISE_XOR)) {
struct nlattr *nest;
nest = mnl_attr_nest_start(nlh, NFTA_BITWISE_XOR);
mnl_attr_put(nlh, NFTA_DATA_VALUE, bitwise->xor.len,
bitwise->xor.val);
mnl_attr_nest_end(nlh, nest);
}
if (e->flags & (1 << NFTNL_EXPR_BITWISE_DATA)) {
struct nlattr *nest;
nest = mnl_attr_nest_start(nlh, NFTA_BITWISE_DATA);
mnl_attr_put(nlh, NFTA_DATA_VALUE, bitwise->data.len,
bitwise->data.val);
mnl_attr_nest_end(nlh, nest);
}
}
static int
nftnl_expr_bitwise_parse(struct nftnl_expr *e, struct nlattr *attr)
{
struct nftnl_expr_bitwise *bitwise = nftnl_expr_data(e);
struct nlattr *tb[NFTA_BITWISE_MAX+1] = {};
int ret = 0;
if (mnl_attr_parse_nested(attr, nftnl_expr_bitwise_cb, tb) < 0)
return -1;
if (tb[NFTA_BITWISE_SREG]) {
bitwise->sreg = ntohl(mnl_attr_get_u32(tb[NFTA_BITWISE_SREG]));
e->flags |= (1 << NFTNL_EXPR_BITWISE_SREG);
}
if (tb[NFTA_BITWISE_DREG]) {
bitwise->dreg = ntohl(mnl_attr_get_u32(tb[NFTA_BITWISE_DREG]));
e->flags |= (1 << NFTNL_EXPR_BITWISE_DREG);
}
if (tb[NFTA_BITWISE_OP]) {
bitwise->op = ntohl(mnl_attr_get_u32(tb[NFTA_BITWISE_OP]));
e->flags |= (1 << NFTNL_EXPR_BITWISE_OP);
}
if (tb[NFTA_BITWISE_LEN]) {
bitwise->len = ntohl(mnl_attr_get_u32(tb[NFTA_BITWISE_LEN]));
e->flags |= (1 << NFTNL_EXPR_BITWISE_LEN);
}
if (tb[NFTA_BITWISE_MASK]) {
ret = nftnl_parse_data(&bitwise->mask, tb[NFTA_BITWISE_MASK], NULL);
e->flags |= (1 << NFTA_BITWISE_MASK);
}
if (tb[NFTA_BITWISE_XOR]) {
ret = nftnl_parse_data(&bitwise->xor, tb[NFTA_BITWISE_XOR], NULL);
e->flags |= (1 << NFTA_BITWISE_XOR);
}
if (tb[NFTA_BITWISE_DATA]) {
ret = nftnl_parse_data(&bitwise->data, tb[NFTA_BITWISE_DATA], NULL);
e->flags |= (1 << NFTNL_EXPR_BITWISE_DATA);
}
return ret;
}
static int
nftnl_expr_bitwise_snprintf_bool(char *buf, size_t size,
const struct nftnl_expr_bitwise *bitwise)
{
int remain = size, offset = 0, ret;
ret = snprintf(buf, remain, "reg %u = ( reg %u & ",
bitwise->dreg, bitwise->sreg);
SNPRINTF_BUFFER_SIZE(ret, remain, offset);
ret = nftnl_data_reg_snprintf(buf + offset, remain, &bitwise->mask,
NFTNL_OUTPUT_DEFAULT, 0, DATA_VALUE);
SNPRINTF_BUFFER_SIZE(ret, remain, offset);
ret = snprintf(buf + offset, remain, ") ^ ");
SNPRINTF_BUFFER_SIZE(ret, remain, offset);
ret = nftnl_data_reg_snprintf(buf + offset, remain, &bitwise->xor,
NFTNL_OUTPUT_DEFAULT, 0, DATA_VALUE);
SNPRINTF_BUFFER_SIZE(ret, remain, offset);
return offset;
}
static int
nftnl_expr_bitwise_snprintf_shift(char *buf, size_t size, const char *op,
const struct nftnl_expr_bitwise *bitwise)
{ int remain = size, offset = 0, ret;
ret = snprintf(buf, remain, "reg %u = ( reg %u %s ",
bitwise->dreg, bitwise->sreg, op);
SNPRINTF_BUFFER_SIZE(ret, remain, offset);
ret = nftnl_data_reg_snprintf(buf + offset, remain, &bitwise->data,
NFTNL_OUTPUT_DEFAULT, 0, DATA_VALUE);
SNPRINTF_BUFFER_SIZE(ret, remain, offset);
ret = snprintf(buf + offset, remain, ") ");
SNPRINTF_BUFFER_SIZE(ret, remain, offset);
return offset;
}
static int nftnl_expr_bitwise_snprintf_default(char *buf, size_t size,
const struct nftnl_expr *e)
{
struct nftnl_expr_bitwise *bitwise = nftnl_expr_data(e);
int err = -1;
switch (bitwise->op) {
case NFT_BITWISE_BOOL:
err = nftnl_expr_bitwise_snprintf_bool(buf, size, bitwise);
break;
case NFT_BITWISE_LSHIFT:
err = nftnl_expr_bitwise_snprintf_shift(buf, size, "<<", bitwise);
break;
case NFT_BITWISE_RSHIFT:
err = nftnl_expr_bitwise_snprintf_shift(buf, size, ">>", bitwise);
break;
}
return err;
}
static int
nftnl_expr_bitwise_snprintf(char *buf, size_t size, uint32_t type,
uint32_t flags, const struct nftnl_expr *e)
{
switch (type) {
case NFTNL_OUTPUT_DEFAULT:
return nftnl_expr_bitwise_snprintf_default(buf, size, e);
default:
break;
}
return -1;
}
struct expr_ops expr_ops_bitwise = {
.name = "bitwise",
.alloc_len = sizeof(struct nftnl_expr_bitwise),
.max_attr = NFTA_BITWISE_MAX,
.set = nftnl_expr_bitwise_set,
.get = nftnl_expr_bitwise_get,
.parse = nftnl_expr_bitwise_parse,
.build = nftnl_expr_bitwise_build,
.snprintf = nftnl_expr_bitwise_snprintf,
};
nftnl_expr_bitwise
Definition: bitwise.c:24