conntrackd: add cthelper infrastructure (+ example FTP helper)

This patch adds the user-space helper infrastructure. It also
contains the implementation of the FTP helper in user-space.

There's one example file that you can use to configure conntrackd
as user-space connection tracking helper under:

 doc/helper/conntrackd.conf

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 619 insertions, 0 deletions

diff --git a/src/nfct-extensions/helper.c b/src/nfct-extensions/helper.c
new file mode 100644
index 0000000..e8f85bb
--- /dev/null
+++ b/src/nfct-extensions/helper.c
@@ -0,0 +1,619 @@
+/*
+ * (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 Vyatta Inc. <http://www.vyatta.com>
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <dirent.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <time.h>
+#include <netinet/in.h>
+#include <errno.h>
+#include <dlfcn.h>
+
+#include <libmnl/libmnl.h>
+#include <linux/netfilter/nfnetlink_cthelper.h>
+#include <libnetfilter_cthelper/libnetfilter_cthelper.h>
+
+#include "nfct.h"
+#include "helper.h"
+
+static void
+nfct_cmd_helper_usage(char *argv[])
+{
+	fprintf(stderr, "nfct v%s: Missing command\n"
+			"%s helper list|add|delete|get|flush "
+			"[parameters...]\n", VERSION, argv[0]);
+}
+
+int
+nfct_cmd_helper_parse_params(int argc, char *argv[])
+{
+	int cmd = NFCT_CMD_NONE, ret = 0;
+
+	if (argc < 3) {
+		fprintf(stderr, "nfct v%s: Missing command\n"
+				"%s helper list|add|delete|get|flush "
+				"[parameters...]\n", VERSION, argv[0]);
+		exit(EXIT_FAILURE);
+	}
+	if (strncmp(argv[2], "list", strlen(argv[2])) == 0)
+		cmd = NFCT_CMD_LIST;
+	else if (strncmp(argv[2], "add", strlen(argv[2])) == 0)
+		cmd = NFCT_CMD_ADD;
+	else if (strncmp(argv[2], "delete", strlen(argv[2])) == 0)
+		cmd = NFCT_CMD_DELETE;
+	else if (strncmp(argv[2], "get", strlen(argv[2])) == 0)
+		cmd = NFCT_CMD_GET;
+	else if (strncmp(argv[2], "flush", strlen(argv[2])) == 0)
+		cmd = NFCT_CMD_FLUSH;
+	else if (strncmp(argv[2], "disable", strlen(argv[2])) == 0)
+		cmd = NFCT_CMD_DISABLE;
+	else {
+		fprintf(stderr, "nfct v%s: Unknown command: %s\n",
+			VERSION, argv[2]);
+		nfct_cmd_helper_usage(argv);
+		exit(EXIT_FAILURE);
+	}
+	switch(cmd) {
+	case NFCT_CMD_LIST:
+		ret = nfct_cmd_helper_list(argc, argv);
+		break;
+	case NFCT_CMD_ADD:
+		ret = nfct_cmd_helper_add(argc, argv);
+		break;
+	case NFCT_CMD_DELETE:
+		ret = nfct_cmd_helper_delete(argc, argv);
+		break;
+	case NFCT_CMD_GET:
+		ret = nfct_cmd_helper_get(argc, argv);
+		break;
+	case NFCT_CMD_FLUSH:
+		ret = nfct_cmd_helper_flush(argc, argv);
+		break;
+	case NFCT_CMD_DISABLE:
+		ret = nfct_cmd_helper_disable(argc, argv);
+		break;
+	}
+
+	return ret;
+}
+
+static int nfct_helper_cb(const struct nlmsghdr *nlh, void *data)
+{
+	struct nfct_helper *t;
+	char buf[4096];
+
+	t = nfct_helper_alloc();
+	if (t == NULL) {
+		nfct_perror("OOM");
+		goto err;
+	}
+
+	if (nfct_helper_nlmsg_parse_payload(nlh, t) < 0) {
+		nfct_perror("nfct_helper_nlmsg_parse_payload");
+		goto err_free;
+	}
+
+	nfct_helper_snprintf(buf, sizeof(buf), t, 0, 0);
+	printf("%s\n", buf);
+
+err_free:
+	nfct_helper_free(t);
+err:
+	return MNL_CB_OK;
+}
+
+int nfct_cmd_helper_list(int argc, char *argv[])
+{
+	struct mnl_socket *nl;
+	char buf[MNL_SOCKET_BUFFER_SIZE];
+	struct nlmsghdr *nlh;
+	unsigned int seq, portid;
+	int ret;
+
+	if (argc > 3) {
+		nfct_perror("too many arguments");
+		return -1;
+	}
+
+	seq = time(NULL);
+	nlh = nfct_helper_nlmsg_build_hdr(buf, NFNL_MSG_CTHELPER_GET,
+						NLM_F_DUMP, seq);
+
+	nl = mnl_socket_open(NETLINK_NETFILTER);
+	if (nl == NULL) {
+		nfct_perror("mnl_socket_open");
+		return -1;
+	}
+
+	if (mnl_socket_bind(nl, 0, MNL_SOCKET_AUTOPID) < 0) {
+		nfct_perror("mnl_socket_bind");
+		return -1;
+	}
+	portid = mnl_socket_get_portid(nl);
+
+	if (mnl_socket_sendto(nl, nlh, nlh->nlmsg_len) < 0) {
+		nfct_perror("mnl_socket_send");
+		return -1;
+	}
+
+	ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
+	while (ret > 0) {
+		ret = mnl_cb_run(buf, ret, seq, portid, nfct_helper_cb, NULL);
+		if (ret <= 0)
+			break;
+		ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
+	}
+	if (ret == -1) {
+		nfct_perror("error");
+		return -1;
+	}
+	mnl_socket_close(nl);
+
+	return 0;
+}
+
+int nfct_cmd_helper_add(int argc, char *argv[])
+{
+	struct mnl_socket *nl;
+	char buf[MNL_SOCKET_BUFFER_SIZE];
+	struct nlmsghdr *nlh;
+	uint32_t portid, seq;
+	struct nfct_helper *t;
+	uint16_t l3proto;
+	uint8_t l4proto;
+	struct ctd_helper *helper;
+	int ret, j;
+
+	if (argc < 6) {
+		nfct_perror("missing parameters\n"
+			    "syntax: nfct helper add name "
+			    "family protocol");
+		return -1;
+	}
+
+	if (strcmp(argv[4], "inet") == 0)
+		l3proto = AF_INET;
+	else if (strcmp(argv[4], "inet6") == 0)
+		l3proto = AF_INET6;
+	else {
+		nfct_perror("unknown layer 3 protocol");
+		return -1;
+	}
+
+	if (strcmp(argv[5], "tcp") == 0)
+		l4proto = IPPROTO_TCP;
+	else if (strcmp(argv[5], "udp") == 0)
+		l4proto = IPPROTO_UDP;
+	else {
+		nfct_perror("unsupported layer 4 protocol");
+		return -1;
+	}
+
+	/* XXX use prefix defined in configure.ac. */
+	helper = helper_find("/usr/lib/conntrack-tools",
+				argv[3], l4proto, RTLD_LAZY);
+	if (helper == NULL) {
+		nfct_perror("that helper is not supported");
+		return -1;
+	}
+
+	t = nfct_helper_alloc();
+	if (t == NULL) {
+		nfct_perror("OOM");
+		return -1;
+	}
+	nfct_helper_attr_set(t, NFCTH_ATTR_NAME, argv[3]);
+	nfct_helper_attr_set_u16(t, NFCTH_ATTR_PROTO_L3NUM, l3proto);
+	nfct_helper_attr_set_u8(t, NFCTH_ATTR_PROTO_L4NUM, l4proto);
+	nfct_helper_attr_set_u32(t, NFCTH_ATTR_PRIV_DATA_LEN,
+				 helper->priv_data_len);
+
+	for (j=0; j<CTD_HELPER_POLICY_MAX; j++) {
+		struct nfct_helper_policy *p;
+
+		if (!helper->policy[j].name[0])
+			break;
+
+		p = nfct_helper_policy_alloc();
+		if (p == NULL) {
+			nfct_perror("OOM");
+			return -1;
+		}
+
+		nfct_helper_policy_attr_set(p, NFCTH_ATTR_POLICY_NAME,
+					helper->policy[j].name);
+		nfct_helper_policy_attr_set_u32(p, NFCTH_ATTR_POLICY_TIMEOUT,
+					helper->policy[j].expect_timeout);
+		nfct_helper_policy_attr_set_u32(p, NFCTH_ATTR_POLICY_MAX,
+					helper->policy[j].expect_max);
+
+		nfct_helper_attr_set(t, NFCTH_ATTR_POLICY+j, p);
+	}
+
+	seq = time(NULL);
+	nlh = nfct_helper_nlmsg_build_hdr(buf, NFNL_MSG_CTHELPER_NEW,
+					  NLM_F_CREATE | NLM_F_ACK, seq);
+	nfct_helper_nlmsg_build_payload(nlh, t);
+
+	nfct_helper_free(t);
+
+	nl = mnl_socket_open(NETLINK_NETFILTER);
+	if (nl == NULL) {
+		nfct_perror("mnl_socket_open");
+		return -1;
+	}
+
+	if (mnl_socket_bind(nl, 0, MNL_SOCKET_AUTOPID) < 0) {
+		nfct_perror("mnl_socket_bind");
+		return -1;
+	}
+	portid = mnl_socket_get_portid(nl);
+
+	if (mnl_socket_sendto(nl, nlh, nlh->nlmsg_len) < 0) {
+		nfct_perror("mnl_socket_send");
+		return -1;
+	}
+
+	ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
+	while (ret > 0) {
+		ret = mnl_cb_run(buf, ret, seq, portid, NULL, NULL);
+		if (ret <= 0)
+			break;
+		ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
+	}
+	if (ret == -1) {
+		nfct_perror("error");
+		return -1;
+	}
+	mnl_socket_close(nl);
+
+	return 0;
+}
+
+int nfct_cmd_helper_delete(int argc, char *argv[])
+{
+	struct mnl_socket *nl;
+	char buf[MNL_SOCKET_BUFFER_SIZE];
+	struct nlmsghdr *nlh;
+	uint32_t portid, seq;
+	struct nfct_helper *t;
+	int ret;
+
+	if (argc < 4) {
+		nfct_perror("missing helper policy name");
+		return -1;
+	} else if (argc > 6) {
+		nfct_perror("too many arguments");
+		return -1;
+	}
+
+	t = nfct_helper_alloc();
+	if (t == NULL) {
+		nfct_perror("OOM");
+		return -1;
+	}
+
+	nfct_helper_attr_set(t, NFCTH_ATTR_NAME, argv[3]);
+
+	if (argc >= 5) {
+		uint16_t l3proto;
+
+		if (strcmp(argv[4], "inet") == 0)
+			l3proto = AF_INET;
+		else if (strcmp(argv[4], "inet6") == 0)
+			l3proto = AF_INET6;
+		else {
+			nfct_perror("unknown layer 3 protocol");
+			return -1;
+		}
+		nfct_helper_attr_set_u16(t, NFCTH_ATTR_PROTO_L3NUM, l3proto);
+	}
+
+	if (argc == 6) {
+		uint8_t l4proto;
+
+		if (strcmp(argv[5], "tcp") == 0)
+			l4proto = IPPROTO_TCP;
+		else if (strcmp(argv[5], "udp") == 0)
+			l4proto = IPPROTO_UDP;
+		else {
+			nfct_perror("unsupported layer 4 protocol");
+			return -1;
+		}
+		nfct_helper_attr_set_u32(t, NFCTH_ATTR_PROTO_L4NUM, l4proto);
+	}
+
+	seq = time(NULL);
+	nlh = nfct_helper_nlmsg_build_hdr(buf, NFNL_MSG_CTHELPER_DEL,
+					  NLM_F_ACK, seq);
+	nfct_helper_nlmsg_build_payload(nlh, t);
+
+	nfct_helper_free(t);
+
+	nl = mnl_socket_open(NETLINK_NETFILTER);
+	if (nl == NULL) {
+		nfct_perror("mnl_socket_open");
+		return -1;
+	}
+
+	if (mnl_socket_bind(nl, 0, MNL_SOCKET_AUTOPID) < 0) {
+		nfct_perror("mnl_socket_bind");
+		return -1;
+	}
+	portid = mnl_socket_get_portid(nl);
+
+	if (mnl_socket_sendto(nl, nlh, nlh->nlmsg_len) < 0) {
+		nfct_perror("mnl_socket_send");
+		return -1;
+	}
+
+	ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
+	while (ret > 0) {
+		ret = mnl_cb_run(buf, ret, seq, portid, NULL, NULL);
+		if (ret <= 0)
+			break;
+		ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
+	}
+	if (ret == -1) {
+		nfct_perror("error");
+		return -1;
+	}
+
+	mnl_socket_close(nl);
+
+	return 0;
+}
+
+int nfct_cmd_helper_get(int argc, char *argv[])
+{
+	struct mnl_socket *nl;
+	char buf[MNL_SOCKET_BUFFER_SIZE];
+	struct nlmsghdr *nlh;
+	uint32_t portid, seq;
+	struct nfct_helper *t;
+	int ret;
+
+	if (argc < 4) {
+		nfct_perror("missing helper policy name");
+		return -1;
+	} else if (argc > 6) {
+		nfct_perror("too many arguments");
+		return -1;
+	}
+
+	t = nfct_helper_alloc();
+	if (t == NULL) {
+		nfct_perror("OOM");
+		return -1;
+	}
+	nfct_helper_attr_set(t, NFCTH_ATTR_NAME, argv[3]);
+
+	if (argc >= 5) {
+		uint16_t l3proto;
+
+		if (strcmp(argv[4], "inet") == 0)
+			l3proto = AF_INET;
+		else if (strcmp(argv[4], "inet6") == 0)
+			l3proto = AF_INET6;
+		else {
+			nfct_perror("unknown layer 3 protocol");
+			return -1;
+		}
+		nfct_helper_attr_set_u16(t, NFCTH_ATTR_PROTO_L3NUM, l3proto);
+	}
+
+	if (argc == 6) {
+		uint8_t l4proto;
+
+		if (strcmp(argv[5], "tcp") == 0)
+			l4proto = IPPROTO_TCP;
+		else if (strcmp(argv[5], "udp") == 0)
+			l4proto = IPPROTO_UDP;
+		else {
+			nfct_perror("unsupported layer 4 protocol");
+			return -1;
+		}
+		nfct_helper_attr_set_u32(t, NFCTH_ATTR_PROTO_L4NUM, l4proto);
+	}
+
+	seq = time(NULL);
+	nlh = nfct_helper_nlmsg_build_hdr(buf, NFNL_MSG_CTHELPER_GET,
+					  NLM_F_ACK, seq);
+
+	nfct_helper_nlmsg_build_payload(nlh, t);
+
+	nfct_helper_free(t);
+
+	nl = mnl_socket_open(NETLINK_NETFILTER);
+	if (nl == NULL) {
+		nfct_perror("mnl_socket_open");
+		return -1;
+	}
+
+	if (mnl_socket_bind(nl, 0, MNL_SOCKET_AUTOPID) < 0) {
+		nfct_perror("mnl_socket_bind");
+		return -1;
+	}
+	portid = mnl_socket_get_portid(nl);
+
+	if (mnl_socket_sendto(nl, nlh, nlh->nlmsg_len) < 0) {
+		nfct_perror("mnl_socket_send");
+		return -1;
+	}
+
+	ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
+	while (ret > 0) {
+		ret = mnl_cb_run(buf, ret, seq, portid, nfct_helper_cb, NULL);
+		if (ret <= 0)
+			break;
+		ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
+	}
+	if (ret == -1) {
+		nfct_perror("error");
+		return -1;
+	}
+	mnl_socket_close(nl);
+
+	return 0;
+}
+
+int nfct_cmd_helper_flush(int argc, char *argv[])
+{
+	struct mnl_socket *nl;
+	char buf[MNL_SOCKET_BUFFER_SIZE];
+	struct nlmsghdr *nlh;
+	uint32_t portid, seq;
+	int ret;
+
+	if (argc > 3) {
+		nfct_perror("too many arguments");
+		return -1;
+	}
+
+	seq = time(NULL);
+	nlh = nfct_helper_nlmsg_build_hdr(buf, NFNL_MSG_CTHELPER_DEL,
+					   NLM_F_ACK, seq);
+
+	nl = mnl_socket_open(NETLINK_NETFILTER);
+	if (nl == NULL) {
+		nfct_perror("mnl_socket_open");
+		return -1;
+	}
+
+	if (mnl_socket_bind(nl, 0, MNL_SOCKET_AUTOPID) < 0) {
+		nfct_perror("mnl_socket_bind");
+		return -1;
+	}
+	portid = mnl_socket_get_portid(nl);
+
+	if (mnl_socket_sendto(nl, nlh, nlh->nlmsg_len) < 0) {
+		nfct_perror("mnl_socket_send");
+		return -1;
+	}
+
+	ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
+	while (ret > 0) {
+		ret = mnl_cb_run(buf, ret, seq, portid, NULL, NULL);
+		if (ret <= 0)
+			break;
+		ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
+	}
+	if (ret == -1) {
+		nfct_perror("error");
+		return -1;
+	}
+
+	mnl_socket_close(nl);
+
+	return 0;
+}
+
+int nfct_cmd_helper_disable(int argc, char *argv[])
+{
+	struct mnl_socket *nl;
+	char buf[MNL_SOCKET_BUFFER_SIZE];
+	struct nlmsghdr *nlh;
+	uint32_t portid, seq;
+	struct nfct_helper *t;
+	uint16_t l3proto;
+	uint8_t l4proto;
+	struct ctd_helper *helper;
+	int ret;
+
+	if (argc < 6) {
+		nfct_perror("missing parameters\n"
+			    "syntax: nfct helper add name "
+			    "family protocol");
+		return -1;
+	}
+
+	if (strcmp(argv[4], "inet") == 0)
+		l3proto = AF_INET;
+	else if (strcmp(argv[4], "inet6") == 0)
+		l3proto = AF_INET6;
+	else {
+		nfct_perror("unknown layer 3 protocol");
+		return -1;
+	}
+
+	if (strcmp(argv[5], "tcp") == 0)
+		l4proto = IPPROTO_TCP;
+	else if (strcmp(argv[5], "udp") == 0)
+		l4proto = IPPROTO_UDP;
+	else {
+		nfct_perror("unsupported layer 4 protocol");
+		return -1;
+	}
+
+	/* XXX use prefix defined in configure.ac. */
+	helper = helper_find("/usr/lib/conntrack-tools",
+				argv[3], l4proto, RTLD_LAZY);
+	if (helper == NULL) {
+		nfct_perror("that helper is not supported");
+		return -1;
+	}
+
+	t = nfct_helper_alloc();
+	if (t == NULL) {
+		nfct_perror("OOM");
+		return -1;
+	}
+	nfct_helper_attr_set(t, NFCTH_ATTR_NAME, argv[3]);
+	nfct_helper_attr_set_u16(t, NFCTH_ATTR_PROTO_L3NUM, l3proto);
+	nfct_helper_attr_set_u8(t, NFCTH_ATTR_PROTO_L4NUM, l4proto);
+	nfct_helper_attr_set_u32(t, NFCTH_ATTR_STATUS,
+					NFCT_HELPER_STATUS_DISABLED);
+
+	seq = time(NULL);
+	nlh = nfct_helper_nlmsg_build_hdr(buf, NFNL_MSG_CTHELPER_NEW,
+					  NLM_F_CREATE | NLM_F_ACK, seq);
+	nfct_helper_nlmsg_build_payload(nlh, t);
+
+	nfct_helper_free(t);
+
+	nl = mnl_socket_open(NETLINK_NETFILTER);
+	if (nl == NULL) {
+		nfct_perror("mnl_socket_open");
+		return -1;
+	}
+
+	if (mnl_socket_bind(nl, 0, MNL_SOCKET_AUTOPID) < 0) {
+		nfct_perror("mnl_socket_bind");
+		return -1;
+	}
+	portid = mnl_socket_get_portid(nl);
+
+	if (mnl_socket_sendto(nl, nlh, nlh->nlmsg_len) < 0) {
+		nfct_perror("mnl_socket_send");
+		return -1;
+	}
+
+	ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
+	while (ret > 0) {
+		ret = mnl_cb_run(buf, ret, seq, portid, NULL, NULL);
+		if (ret <= 0)
+			break;
+		ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
+	}
+	if (ret == -1) {
+		nfct_perror("error");
+		return -1;
+	}
+	mnl_socket_close(nl);
+
+	return 0;
+}
+