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/*
* (C) 2006-2012 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 program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* This code has been sponsored by Vyatta Inc. <http://www.vyatta.com>
*/
#include "conntrackd.h"
#include "log.h"
#include "fds.h"
#include "helper.h"
#include <unistd.h>
#include <fcntl.h>
#include <time.h>
#include <errno.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/ip6.h>
#include <netinet/tcp.h>
#include <netinet/udp.h>
#include <net/ethernet.h>
#ifndef __aligned_be64
#define __aligned_be64 unsigned long long __attribute__((aligned(8)))
#endif
#include <linux/netfilter/nfnetlink_queue.h>
#include <libmnl/libmnl.h>
#include <libnetfilter_queue/libnetfilter_queue.h>
#include <libnetfilter_queue/pktbuff.h>
#include <libnetfilter_cthelper/libnetfilter_cthelper.h>
#include <linux/netfilter.h>
#include <libnetfilter_queue/pktbuff.h>
void cthelper_kill(void)
{
mnl_socket_close(STATE_CTH(nl));
free(state.cthelper);
}
int cthelper_local(int fd, int type, void *data)
{
/* No services to obtain information on helpers yet, sorry */
return LOCAL_RET_OK;
}
static struct nlmsghdr *
nfq_hdr_put(char *buf, int type, uint32_t queue_num)
{
struct nlmsghdr *nlh = mnl_nlmsg_put_header(buf);
nlh->nlmsg_type = (NFNL_SUBSYS_QUEUE << 8) | type;
nlh->nlmsg_flags = NLM_F_REQUEST;
struct nfgenmsg *nfg = mnl_nlmsg_put_extra_header(nlh, sizeof(*nfg));
nfg->nfgen_family = AF_UNSPEC;
nfg->version = NFNETLINK_V0;
nfg->res_id = htons(queue_num);
return nlh;
}
static int
pkt_get(void *pkt, uint32_t pktlen, uint16_t proto, uint32_t *protoff)
{
uint8_t protocol;
switch(proto) {
case ETHERTYPE_IP: {
struct iphdr *ip = (struct iphdr *) pkt;
/* No room for IPv4 header. */
if (pktlen < sizeof(struct iphdr)) {
dlog(LOG_ERR, "no room for IPv4 header");
return -1;
}
/* this is not IPv4, skip. */
if (ip->version != 4) {
dlog(LOG_ERR, "not IPv4, skipping");
return -1;
}
*protoff = 4 * ip->ihl;
protocol = ip->protocol;
break;
}
case ETHERTYPE_IPV6: {
struct iphdr *ip = (struct iphdr *) pkt;
struct ip6_hdr *ip6 = (struct ip6_hdr *) pkt;
/* No room for IPv6 header. */
if (pktlen < sizeof(struct ip6_hdr)) {
dlog(LOG_ERR, "no room for IPv6 header");
return -1;
}
/* this is not IPv6, skip. */
if (ip->version != 6) {
dlog(LOG_ERR, "not IPv6, skipping");
return -1;
}
*protoff = sizeof(struct ip6_hdr);
protocol = ip6->ip6_nxt;
break;
}
default:
/* Unknown layer 3 protocol. */
dlog(LOG_ERR, "unknown layer 3 protocol (%d), skipping", proto);
return -1;
}
switch (protocol) {
case IPPROTO_TCP: {
struct tcphdr *tcph =
(struct tcphdr *) ((char *)pkt + *protoff);
/* No room for IPv4 header plus TCP header. */
if (pktlen < *protoff + sizeof(struct tcphdr) ||
pktlen < *protoff + tcph->doff * 4) {
dlog(LOG_ERR, "no room for IPv4 + TCP header, skip");
return -1;
}
return 0;
}
case IPPROTO_UDP:
/* No room for IPv4 header plus UDP header. */
if (pktlen < *protoff + sizeof(struct udphdr)) {
dlog(LOG_ERR, "no room for IPv4 + UDP header, skip");
return -1;
}
return 0;
default:
dlog(LOG_ERR, "not TCP/UDP, skipping");
return -1;
}
return 0;
}
static int
pkt_verdict_issue(struct ctd_helper_instance *cur, struct myct *myct,
uint16_t queue_num, uint32_t id, uint32_t verdict,
struct pkt_buff *pktb)
{
struct nlmsghdr *nlh;
char buf[MNL_SOCKET_BUFFER_SIZE];
struct nlattr *nest;
nlh = nfq_hdr_put(buf, NFQNL_MSG_VERDICT, queue_num);
/* save private data and send it back to kernel-space, if any. */
if (myct->priv_data) {
nfct_set_attr_l(myct->ct, ATTR_HELPER_INFO, myct->priv_data,
cur->helper->priv_data_len);
}
nfq_nlmsg_verdict_put(nlh, id, verdict);
if (pktb_mangled(pktb))
nfq_nlmsg_verdict_put_pkt(nlh, pktb_data(pktb), pktb_len(pktb));
nest = mnl_attr_nest_start(nlh, NFQA_CT);
if (nest == NULL)
return -1;
nfct_nlmsg_build(nlh, myct->ct);
mnl_attr_nest_end(nlh, nest);
if (myct->exp) {
nest = mnl_attr_nest_start(nlh, NFQA_EXP);
if (nest == NULL)
return -1;
nfexp_nlmsg_build(nlh, myct->exp);
mnl_attr_nest_end(nlh, nest);
}
if (mnl_socket_sendto(STATE_CTH(nl), nlh, nlh->nlmsg_len) < 0) {
dlog(LOG_ERR, "failed to send verdict: %s", strerror(errno));
return -1;
}
return 0;
}
static int
pkt_verdict_error(uint16_t queue_num, uint32_t id)
{
struct nlmsghdr *nlh;
char buf[MNL_SOCKET_BUFFER_SIZE];
nlh = nfq_hdr_put(buf, NFQNL_MSG_VERDICT, queue_num);
nfq_nlmsg_verdict_put(nlh, id, NF_ACCEPT);
if (mnl_socket_sendto(STATE_CTH(nl), nlh, nlh->nlmsg_len) < 0) {
dlog(LOG_ERR, "failed to send verdict: %s", strerror(errno));
return -1;
}
return 0;
}
static struct ctd_helper_instance *
helper_run(struct pkt_buff *pktb, uint32_t protoff, struct myct *myct,
uint32_t ctinfo, uint32_t queue_num, int *verdict)
{
struct ctd_helper_instance *cur, *helper = NULL;
list_for_each_entry(cur, &CONFIG(cthelper).list, head) {
if (cur->queue_num == queue_num) {
const void *priv_data;
/* retrieve helper private data. */
priv_data = nfct_get_attr(myct->ct, ATTR_HELPER_INFO);
if (priv_data != NULL) {
myct->priv_data =
calloc(1, cur->helper->priv_data_len);
if (myct->priv_data == NULL)
continue;
memcpy(myct->priv_data, priv_data,
cur->helper->priv_data_len);
}
*verdict = cur->helper->cb(pktb, protoff, myct, ctinfo);
helper = cur;
break;
}
}
return helper;
}
static int nfq_queue_cb(const struct nlmsghdr *nlh, void *data)
{
struct nfqnl_msg_packet_hdr *ph = NULL;
struct nlattr *attr[NFQA_MAX+1] = {};
struct nfgenmsg *nfg;
uint8_t *pkt;
uint16_t l3num;
uint32_t id, ctinfo, queue_num = 0, protoff = 0, pktlen;
struct nf_conntrack *ct = NULL;
struct myct *myct;
struct ctd_helper_instance *helper;
struct pkt_buff *pktb;
int verdict = NF_ACCEPT;
if (nfq_nlmsg_parse(nlh, attr) < 0) {
dlog(LOG_ERR, "problems parsing message from kernel");
return MNL_CB_ERROR;
}
ph = (struct nfqnl_msg_packet_hdr *)
mnl_attr_get_payload(attr[NFQA_PACKET_HDR]);
if (ph == NULL) {
dlog(LOG_ERR, "problems retrieving metaheader");
return MNL_CB_ERROR;
}
id = ntohl(ph->packet_id);
if (!attr[NFQA_PAYLOAD]) {
dlog(LOG_ERR, "packet with no payload");
goto err;
}
if (!attr[NFQA_CT] || !attr[NFQA_CT_INFO]) {
dlog(LOG_ERR, "no CT attached to this packet");
goto err;
}
pkt = mnl_attr_get_payload(attr[NFQA_PAYLOAD]);
pktlen = mnl_attr_get_payload_len(attr[NFQA_PAYLOAD]);
nfg = mnl_nlmsg_get_payload(nlh);
l3num = nfg->nfgen_family;
queue_num = ntohs(nfg->res_id);
if (pkt_get(pkt, pktlen, ntohs(ph->hw_protocol), &protoff))
goto err;
ct = nfct_new();
if (ct == NULL)
goto err;
if (nfct_payload_parse(mnl_attr_get_payload(attr[NFQA_CT]),
mnl_attr_get_payload_len(attr[NFQA_CT]),
l3num, ct) < 0) {
dlog(LOG_ERR, "cannot convert message to CT");
goto err;
}
myct = calloc(1, sizeof(struct myct));
if (myct == NULL)
goto err;
myct->ct = ct;
ctinfo = ntohl(mnl_attr_get_u32(attr[NFQA_CT_INFO]));
/* XXX: 256 bytes enough for possible NAT mangling in helpers? */
pktb = pktb_alloc(AF_INET, pkt, pktlen, 256);
if (pktb == NULL)
goto err;
/* Misconfiguration: if no helper found, accept the packet. */
helper = helper_run(pktb, protoff, myct, ctinfo, queue_num, &verdict);
if (!helper)
goto err_pktb;
if (pkt_verdict_issue(helper, myct, queue_num, id, verdict, pktb) < 0)
goto err_pktb;
if (ct != NULL)
nfct_destroy(ct);
if (myct->exp != NULL)
nfexp_destroy(myct->exp);
if (myct && myct->priv_data != NULL)
free(myct->priv_data);
if (myct != NULL)
free(myct);
return MNL_CB_OK;
err_pktb:
pktb_free(pktb);
err:
/* In case of error, we don't want to disrupt traffic. We accept all.
* This is connection tracking after all. The policy is not to drop
* packet unless we enter some inconsistent state.
*/
pkt_verdict_error(queue_num, id);
if (ct != NULL)
nfct_destroy(ct);
return MNL_CB_OK;
}
static void nfq_cb(void *data)
{
char buf[MNL_SOCKET_BUFFER_SIZE];
int ret;
ret = mnl_socket_recvfrom(STATE_CTH(nl), buf, sizeof(buf));
if (ret == -1) {
dlog(LOG_ERR, "failed to receive message: %s", strerror(errno));
return;
}
ret = mnl_cb_run(buf, ret, 0, STATE_CTH(portid), nfq_queue_cb, NULL);
if (ret < 0){
dlog(LOG_ERR, "failed to process message");
return;
}
}
static int cthelper_setup(struct ctd_helper_instance *cur)
{
struct nfct_helper *t;
char buf[MNL_SOCKET_BUFFER_SIZE];
struct nlmsghdr *nlh;
uint32_t seq;
int j, ret;
t = nfct_helper_alloc();
if (t == NULL) {
dlog(LOG_ERR, "cannot allocate object for helper");
return -1;
}
nfct_helper_attr_set(t, NFCTH_ATTR_NAME, cur->helper->name);
nfct_helper_attr_set_u32(t, NFCTH_ATTR_QUEUE_NUM, cur->queue_num);
nfct_helper_attr_set_u16(t, NFCTH_ATTR_PROTO_L3NUM, cur->l3proto);
nfct_helper_attr_set_u8(t, NFCTH_ATTR_PROTO_L4NUM, cur->l4proto);
nfct_helper_attr_set_u32(t, NFCTH_ATTR_STATUS,
NFCT_HELPER_STATUS_ENABLED);
dlog(LOG_NOTICE, "configuring helper `%s' with queuenum=%d and "
"queuelen=%d", cur->helper->name, cur->queue_num,
cur->queue_len);
for (j=0; j<CTD_HELPER_POLICY_MAX; j++) {
struct nfct_helper_policy *p;
if (!cur->helper->policy[j].name[0])
break;
p = nfct_helper_policy_alloc();
if (p == NULL) {
dlog(LOG_ERR, "cannot allocate object for helper");
return -1;
}
/* FIXME: get existing policy values from the kernel first. */
nfct_helper_policy_attr_set(p, NFCTH_ATTR_POLICY_NAME,
cur->helper->policy[j].name);
nfct_helper_policy_attr_set_u32(p, NFCTH_ATTR_POLICY_TIMEOUT,
cur->helper->policy[j].expect_timeout);
nfct_helper_policy_attr_set_u32(p, NFCTH_ATTR_POLICY_MAX,
cur->helper->policy[j].expect_max);
dlog(LOG_NOTICE, "policy name=%s expect_timeout=%d expect_max=%d",
cur->helper->policy[j].name,
cur->helper->policy[j].expect_timeout,
cur->helper->policy[j].expect_max);
nfct_helper_attr_set(t, NFCTH_ATTR_POLICY+j, p);
}
if (j == 0) {
dlog(LOG_ERR, "you have to define one policy for helper");
return -1;
}
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);
if (mnl_socket_sendto(STATE_CTH(nl), nlh, nlh->nlmsg_len) < 0) {
dlog(LOG_ERR, "sending cthelper configuration");
return -1;
}
ret = mnl_socket_recvfrom(STATE_CTH(nl), buf, sizeof(buf));
while (ret > 0) {
ret = mnl_cb_run(buf, ret, seq, STATE_CTH(portid), NULL, NULL);
if (ret <= 0)
break;
ret = mnl_socket_recvfrom(STATE_CTH(nl), buf, sizeof(buf));
}
if (ret == -1) {
dlog(LOG_ERR, "trying to configure cthelper `%s': %s",
cur->helper->name, strerror(errno));
return -1;
}
return 0;
}
static int cthelper_nfqueue_setup(struct ctd_helper_instance *cur)
{
char buf[MNL_SOCKET_BUFFER_SIZE];
struct nlmsghdr *nlh;
nlh = nfq_hdr_put(buf, NFQNL_MSG_CONFIG, cur->queue_num);
nfq_nlmsg_cfg_put_cmd(nlh, AF_INET, NFQNL_CFG_CMD_BIND);
if (mnl_socket_sendto(STATE_CTH(nl), nlh, nlh->nlmsg_len) < 0) {
dlog(LOG_ERR, "failed to send bind command");
return -1;
}
nlh = nfq_hdr_put(buf, NFQNL_MSG_CONFIG, cur->queue_num);
nfq_nlmsg_cfg_put_params(nlh, NFQNL_COPY_PACKET, 0xffff);
mnl_attr_put_u32(nlh, NFQA_CFG_FLAGS, htonl(NFQA_CFG_F_CONNTRACK));
mnl_attr_put_u32(nlh, NFQA_CFG_MASK, htonl(0xffffffff));
mnl_attr_put_u32(nlh, NFQA_CFG_QUEUE_MAXLEN, htonl(cur->queue_len));
if (mnl_socket_sendto(STATE_CTH(nl), nlh, nlh->nlmsg_len) < 0) {
dlog(LOG_ERR, "failed to send configuration");
return -1;
}
return 0;
}
static int cthelper_configure(struct ctd_helper_instance *cur)
{
/* First, configure cthelper. */
if (cthelper_setup(cur) < 0)
return -1;
/* Now, we are ready to configure nfqueue attached to this helper. */
if (cthelper_nfqueue_setup(cur) < 0)
return -1;
dlog(LOG_NOTICE, "helper `%s' configured successfully",
cur->helper->name);
return 0;
}
static int nfq_configure(void)
{
char buf[MNL_SOCKET_BUFFER_SIZE];
struct nlmsghdr *nlh;
nlh = nfq_hdr_put(buf, NFQNL_MSG_CONFIG, 0);
nfq_nlmsg_cfg_put_cmd(nlh, AF_INET, NFQNL_CFG_CMD_PF_UNBIND);
if (mnl_socket_sendto(STATE_CTH(nl), nlh, nlh->nlmsg_len) < 0) {
dlog(LOG_ERR, "failed to send pf unbind command");
return -1;
}
nlh = nfq_hdr_put(buf, NFQNL_MSG_CONFIG, 0);
nfq_nlmsg_cfg_put_cmd(nlh, AF_INET, NFQNL_CFG_CMD_PF_BIND);
if (mnl_socket_sendto(STATE_CTH(nl), nlh, nlh->nlmsg_len) < 0) {
dlog(LOG_ERR, "failed to send pf bind command");
return -1;
}
return 0;
}
int cthelper_init(void)
{
struct ctd_helper_instance *cur;
int ret;
state.cthelper = calloc(1, sizeof(struct ct_helper_state));
if (state.cthelper == NULL) {
dlog(LOG_ERR, "can't allocate memory for cthelper struct");
return -1;
}
STATE_CTH(nl) = mnl_socket_open(NETLINK_NETFILTER);
if (STATE_CTH(nl) == NULL) {
dlog(LOG_ERR, "cannot open nfq socket");
return -1;
}
fcntl(mnl_socket_get_fd(STATE_CTH(nl)), F_SETFL, O_NONBLOCK);
if (mnl_socket_bind(STATE_CTH(nl), 0, MNL_SOCKET_AUTOPID) < 0) {
dlog(LOG_ERR, "cannot bind nfq socket");
return -1;
}
STATE_CTH(portid) = mnl_socket_get_portid(STATE_CTH(nl));
if (nfq_configure())
return -1;
list_for_each_entry(cur, &CONFIG(cthelper).list, head) {
ret = cthelper_configure(cur);
if (ret < 0)
return ret;
}
register_fd(mnl_socket_get_fd(STATE_CTH(nl)), nfq_cb, NULL, STATE(fds));
return 0;
}
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