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Diffstat (limited to 'examples/nft-rule-add.c')
| -rw-r--r-- | examples/nft-rule-add.c | 204 |
1 files changed, 204 insertions, 0 deletions
diff --git a/examples/nft-rule-add.c b/examples/nft-rule-add.c new file mode 100644 index 0000000..7d13b92 --- /dev/null +++ b/examples/nft-rule-add.c @@ -0,0 +1,204 @@ +/* + * (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 software has been sponsored by Sophos Astaro <http://www.sophos.com> + */ + +#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 void add_payload(struct nftnl_rule *r, uint32_t base, uint32_t dreg, + uint32_t offset, uint32_t len) +{ + struct nftnl_expr *e; + + e = nftnl_expr_alloc("payload"); + if (e == NULL) { + perror("expr payload oom"); + exit(EXIT_FAILURE); + } + + nftnl_expr_set_u32(e, NFTNL_EXPR_PAYLOAD_BASE, base); + nftnl_expr_set_u32(e, NFTNL_EXPR_PAYLOAD_DREG, dreg); + nftnl_expr_set_u32(e, NFTNL_EXPR_PAYLOAD_OFFSET, offset); + nftnl_expr_set_u32(e, NFTNL_EXPR_PAYLOAD_LEN, len); + + nftnl_rule_add_expr(r, e); +} + +static void add_cmp(struct nftnl_rule *r, uint32_t sreg, uint32_t op, + const void *data, uint32_t data_len) +{ + struct nftnl_expr *e; + + e = nftnl_expr_alloc("cmp"); + if (e == NULL) { + perror("expr cmp oom"); + exit(EXIT_FAILURE); + } + + nftnl_expr_set_u32(e, NFTNL_EXPR_CMP_SREG, sreg); + nftnl_expr_set_u32(e, NFTNL_EXPR_CMP_OP, op); + nftnl_expr_set(e, NFTNL_EXPR_CMP_DATA, data, data_len); + + nftnl_rule_add_expr(r, e); +} + +static void add_counter(struct nftnl_rule *r) +{ + struct nftnl_expr *e; + + e = nftnl_expr_alloc("counter"); + if (e == NULL) { + perror("expr counter oom"); + exit(EXIT_FAILURE); + } + + nftnl_rule_add_expr(r, e); +} + +static struct nftnl_rule *setup_rule(uint8_t family, const char *table, + const char *chain, const char *handle) +{ + struct nftnl_rule *r = NULL; + uint8_t proto; + uint16_t dport; + 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); + } + + proto = IPPROTO_TCP; + add_payload(r, NFT_PAYLOAD_NETWORK_HEADER, NFT_REG_1, + offsetof(struct iphdr, protocol), sizeof(uint8_t)); + add_cmp(r, NFT_REG_1, NFT_CMP_EQ, &proto, sizeof(uint8_t)); + + dport = htons(22); + add_payload(r, NFT_PAYLOAD_TRANSPORT_HEADER, NFT_REG_1, + offsetof(struct tcphdr, dest), sizeof(uint16_t)); + add_cmp(r, NFT_REG_1, NFT_CMP_EQ, &dport, sizeof(uint16_t)); + + add_counter(r); + + return r; +} + +int main(int argc, char *argv[]) +{ + struct mnl_socket *nl; + struct nftnl_rule *r; + struct nlmsghdr *nlh; + struct mnl_nlmsg_batch *batch; + uint8_t family; + char buf[MNL_SOCKET_BUFFER_SIZE]; + uint32_t seq = time(NULL); + int ret; + + if (argc < 4 || argc > 5) { + fprintf(stderr, "Usage: %s <family> <table> <chain>\n", argv[0]); + exit(EXIT_FAILURE); + } + + if (strcmp(argv[1], "ip") == 0) + family = NFPROTO_IPV4; + else if (strcmp(argv[1], "ip6") == 0) + family = NFPROTO_IPV6; + else if (strcmp(argv[1], "inet") == 0) + family = NFPROTO_INET; + else { + fprintf(stderr, "Unknown family: ip, ip6, inet\n"); + exit(EXIT_FAILURE); + } + + if (argc != 5) + r = setup_rule(family, argv[2], argv[3], NULL); + else + r = setup_rule(family, argv[2], argv[3], argv[4]); + + 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_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; +} |