nft-rule-ct-expectation-add.c
/*
* (C) 2019 by Stéphane Veyret <sveyret@gmail.com>
*
* 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.
*/
#include <stdlib.h>
#include <time.h>
#include <string.h>
#include <stddef.h> /* for offsetof */
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/tcp.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <errno.h>
#include <linux/netfilter.h>
#include <linux/netfilter/nfnetlink.h>
#include <linux/netfilter/nf_tables.h>
#include <libmnl/libmnl.h>
#include <libnftnl/rule.h>
#include <libnftnl/expr.h>
static uint16_t parse_family(char *str, const char *option)
{
if (strcmp(str, "ip") == 0)
return NFPROTO_IPV4;
else if (strcmp(str, "ip6") == 0)
return NFPROTO_IPV6;
else if (strcmp(str, "inet") == 0)
return NFPROTO_INET;
else if (strcmp(str, "arp") == 0)
return NFPROTO_INET;
fprintf(stderr, "Unknown %s: ip, ip6, inet, arp\n", option);
exit(EXIT_FAILURE);
}
static void add_ct_expect(struct nftnl_rule *r, const char *obj_name)
{
struct nftnl_expr *e;
e = nftnl_expr_alloc("objref");
if (e == NULL) {
perror("expr objref oom");
exit(EXIT_FAILURE);
}
nftnl_expr_set_str(e, NFTNL_EXPR_OBJREF_IMM_NAME, obj_name);
nftnl_expr_set_u32(e, NFTNL_EXPR_OBJREF_IMM_TYPE, NFT_OBJECT_CT_EXPECT);
nftnl_rule_add_expr(r, e);
}
static struct nftnl_rule *setup_rule(uint8_t family, const char *table,
const char *chain, const char *handle,
const char *obj_name)
{
struct nftnl_rule *r = NULL;
uint64_t handle_num;
r = nftnl_rule_alloc();
if (r == NULL) {
perror("OOM");
exit(EXIT_FAILURE);
}
nftnl_rule_set_str(r, NFTNL_RULE_TABLE, table);
nftnl_rule_set_str(r, NFTNL_RULE_CHAIN, chain);
nftnl_rule_set_u32(r, NFTNL_RULE_FAMILY, family);
if (handle != NULL) {
handle_num = atoll(handle);
nftnl_rule_set_u64(r, NFTNL_RULE_POSITION, handle_num);
}
add_ct_expect(r, obj_name);
return r;
}
int main(int argc, char *argv[])
{
char buf[MNL_SOCKET_BUFFER_SIZE];
struct mnl_nlmsg_batch *batch;
uint32_t seq = time(NULL);
struct mnl_socket *nl;
struct nftnl_rule *r;
struct nlmsghdr *nlh;
uint8_t family;
int ret;
if (argc < 5 || argc > 6) {
fprintf(stderr,
"Usage: %s <family> <table> <chain> [<handle>] <name>\n",
argv[0]);
exit(EXIT_FAILURE);
}
family = parse_family(argv[1], "family");
if (argc < 6)
r = setup_rule(family, argv[2], argv[3], NULL, argv[4]);
else
r = setup_rule(family, argv[2], argv[3], argv[4], argv[5]);
nl = mnl_socket_open(NETLINK_NETFILTER);
if (nl == NULL) {
perror("mnl_socket_open");
exit(EXIT_FAILURE);
}
if (mnl_socket_bind(nl, 0, MNL_SOCKET_AUTOPID) < 0) {
perror("mnl_socket_bind");
exit(EXIT_FAILURE);
}
batch = mnl_nlmsg_batch_start(buf, sizeof(buf));
nftnl_batch_begin(mnl_nlmsg_batch_current(batch), seq++);
mnl_nlmsg_batch_next(batch);
nlh = nftnl_rule_nlmsg_build_hdr(mnl_nlmsg_batch_current(batch),
NFT_MSG_NEWRULE,
nftnl_rule_get_u32(r, NFTNL_RULE_FAMILY),
NLM_F_APPEND|NLM_F_CREATE|NLM_F_ACK,
seq++);
nftnl_rule_nlmsg_build_payload(nlh, r);
nftnl_rule_free(r);
mnl_nlmsg_batch_next(batch);
nftnl_batch_end(mnl_nlmsg_batch_current(batch), seq++);
mnl_nlmsg_batch_next(batch);
ret = mnl_socket_sendto(nl, mnl_nlmsg_batch_head(batch),
mnl_nlmsg_batch_size(batch));
if (ret == -1) {
perror("mnl_socket_sendto");
exit(EXIT_FAILURE);
}
mnl_nlmsg_batch_stop(batch);
ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
if (ret == -1) {
perror("mnl_socket_recvfrom");
exit(EXIT_FAILURE);
}
ret = mnl_cb_run(buf, ret, 0, mnl_socket_get_portid(nl), NULL, NULL);
if (ret < 0) {
perror("mnl_cb_run");
exit(EXIT_FAILURE);
}
mnl_socket_close(nl);
return EXIT_SUCCESS;
}