libnftnl 1.2.9
nft-rule-add.c
1/* SPDX-License-Identifier: GPL-2.0-or-later */
2/*
3 * (C) 2012 by Pablo Neira Ayuso <pablo@netfilter.org>
4 *
5 * This software has been sponsored by Sophos Astaro <http://www.sophos.com>
6 */
7
8#include <stdlib.h>
9#include <time.h>
10#include <string.h>
11#include <stddef.h> /* for offsetof */
12#include <netinet/in.h>
13#include <netinet/ip.h>
14#include <netinet/tcp.h>
15#include <arpa/inet.h>
16#include <sys/types.h>
17#include <sys/socket.h>
18#include <errno.h>
19
20#include <linux/netfilter.h>
21#include <linux/netfilter/nfnetlink.h>
22#include <linux/netfilter/nf_tables.h>
23
24#include <libmnl/libmnl.h>
25#include <libnftnl/rule.h>
26#include <libnftnl/expr.h>
27
28static void add_payload(struct nftnl_rule *r, uint32_t base, uint32_t dreg,
29 uint32_t offset, uint32_t len)
30{
31 struct nftnl_expr *e;
32
33 e = nftnl_expr_alloc("payload");
34 if (e == NULL) {
35 perror("expr payload oom");
36 exit(EXIT_FAILURE);
37 }
38
39 nftnl_expr_set_u32(e, NFTNL_EXPR_PAYLOAD_BASE, base);
40 nftnl_expr_set_u32(e, NFTNL_EXPR_PAYLOAD_DREG, dreg);
41 nftnl_expr_set_u32(e, NFTNL_EXPR_PAYLOAD_OFFSET, offset);
42 nftnl_expr_set_u32(e, NFTNL_EXPR_PAYLOAD_LEN, len);
43
44 nftnl_rule_add_expr(r, e);
45}
46
47static void add_cmp(struct nftnl_rule *r, uint32_t sreg, uint32_t op,
48 const void *data, uint32_t data_len)
49{
50 struct nftnl_expr *e;
51
52 e = nftnl_expr_alloc("cmp");
53 if (e == NULL) {
54 perror("expr cmp oom");
55 exit(EXIT_FAILURE);
56 }
57
58 nftnl_expr_set_u32(e, NFTNL_EXPR_CMP_SREG, sreg);
59 nftnl_expr_set_u32(e, NFTNL_EXPR_CMP_OP, op);
60 nftnl_expr_set(e, NFTNL_EXPR_CMP_DATA, data, data_len);
61
62 nftnl_rule_add_expr(r, e);
63}
64
65static void add_counter(struct nftnl_rule *r)
66{
67 struct nftnl_expr *e;
68
69 e = nftnl_expr_alloc("counter");
70 if (e == NULL) {
71 perror("expr counter oom");
72 exit(EXIT_FAILURE);
73 }
74
75 nftnl_rule_add_expr(r, e);
76}
77
78static struct nftnl_rule *setup_rule(uint8_t family, const char *table,
79 const char *chain, const char *handle)
80{
81 struct nftnl_rule *r = NULL;
82 uint8_t proto;
83 uint16_t dport;
84 uint64_t handle_num;
85
86 r = nftnl_rule_alloc();
87 if (r == NULL) {
88 perror("OOM");
89 exit(EXIT_FAILURE);
90 }
91
92 nftnl_rule_set_str(r, NFTNL_RULE_TABLE, table);
93 nftnl_rule_set_str(r, NFTNL_RULE_CHAIN, chain);
94 nftnl_rule_set_u32(r, NFTNL_RULE_FAMILY, family);
95
96 if (handle != NULL) {
97 handle_num = atoll(handle);
98 nftnl_rule_set_u64(r, NFTNL_RULE_POSITION, handle_num);
99 }
100
101 proto = IPPROTO_TCP;
102 add_payload(r, NFT_PAYLOAD_NETWORK_HEADER, NFT_REG_1,
103 offsetof(struct iphdr, protocol), sizeof(uint8_t));
104 add_cmp(r, NFT_REG_1, NFT_CMP_EQ, &proto, sizeof(uint8_t));
105
106 dport = htons(22);
107 add_payload(r, NFT_PAYLOAD_TRANSPORT_HEADER, NFT_REG_1,
108 offsetof(struct tcphdr, dest), sizeof(uint16_t));
109 add_cmp(r, NFT_REG_1, NFT_CMP_EQ, &dport, sizeof(uint16_t));
110
111 add_counter(r);
112
113 return r;
114}
115
116int main(int argc, char *argv[])
117{
118 struct mnl_socket *nl;
119 struct nftnl_rule *r;
120 struct nlmsghdr *nlh;
121 struct mnl_nlmsg_batch *batch;
122 uint8_t family;
123 char buf[MNL_SOCKET_BUFFER_SIZE];
124 uint32_t seq = time(NULL);
125 int ret;
126
127 if (argc < 4 || argc > 5) {
128 fprintf(stderr, "Usage: %s <family> <table> <chain>\n", argv[0]);
129 exit(EXIT_FAILURE);
130 }
131
132 if (strcmp(argv[1], "ip") == 0)
133 family = NFPROTO_IPV4;
134 else if (strcmp(argv[1], "ip6") == 0)
135 family = NFPROTO_IPV6;
136 else if (strcmp(argv[1], "inet") == 0)
137 family = NFPROTO_INET;
138 else {
139 fprintf(stderr, "Unknown family: ip, ip6, inet\n");
140 exit(EXIT_FAILURE);
141 }
142
143 if (argc != 5)
144 r = setup_rule(family, argv[2], argv[3], NULL);
145 else
146 r = setup_rule(family, argv[2], argv[3], argv[4]);
147
148 nl = mnl_socket_open(NETLINK_NETFILTER);
149 if (nl == NULL) {
150 perror("mnl_socket_open");
151 exit(EXIT_FAILURE);
152 }
153
154 if (mnl_socket_bind(nl, 0, MNL_SOCKET_AUTOPID) < 0) {
155 perror("mnl_socket_bind");
156 exit(EXIT_FAILURE);
157 }
158
159 batch = mnl_nlmsg_batch_start(buf, sizeof(buf));
160
161 nftnl_batch_begin(mnl_nlmsg_batch_current(batch), seq++);
162 mnl_nlmsg_batch_next(batch);
163
164 nlh = nftnl_nlmsg_build_hdr(mnl_nlmsg_batch_current(batch),
165 NFT_MSG_NEWRULE,
166 nftnl_rule_get_u32(r, NFTNL_RULE_FAMILY),
167 NLM_F_APPEND | NLM_F_CREATE | NLM_F_ACK,
168 seq++);
169 nftnl_rule_nlmsg_build_payload(nlh, r);
170 nftnl_rule_free(r);
171 mnl_nlmsg_batch_next(batch);
172
173 nftnl_batch_end(mnl_nlmsg_batch_current(batch), seq++);
174 mnl_nlmsg_batch_next(batch);
175
176 ret = mnl_socket_sendto(nl, mnl_nlmsg_batch_head(batch),
177 mnl_nlmsg_batch_size(batch));
178 if (ret == -1) {
179 perror("mnl_socket_sendto");
180 exit(EXIT_FAILURE);
181 }
182
183 mnl_nlmsg_batch_stop(batch);
184
185 ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
186 if (ret == -1) {
187 perror("mnl_socket_recvfrom");
188 exit(EXIT_FAILURE);
189 }
190
191 ret = mnl_cb_run(buf, ret, 0, mnl_socket_get_portid(nl), NULL, NULL);
192 if (ret < 0) {
193 perror("mnl_cb_run");
194 exit(EXIT_FAILURE);
195 }
196
197 mnl_socket_close(nl);
198
199 return EXIT_SUCCESS;
200}