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-rw-r--r--src/helpers/dhcpv6.c123
1 files changed, 123 insertions, 0 deletions
diff --git a/src/helpers/dhcpv6.c b/src/helpers/dhcpv6.c
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+++ b/src/helpers/dhcpv6.c
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+/*
+ * (C) 2013 by Pablo Neira Ayuso <pablo@netfilter.org>
+ *
+ * Adapted from:
+ *
+ * DHCPv6 multicast connection tracking helper.
+ *
+ * (c) 2012 Google Inc.
+ *
+ * Original author: Darren Willis <djw@google.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 "conntrackd.h"
+#include "helper.h"
+#include "myct.h"
+#include "log.h"
+#include <errno.h>
+#include <netinet/ip.h>
+#include <netinet/ip6.h>
+#include <netinet/udp.h>
+#include <libmnl/libmnl.h>
+#include <libnetfilter_conntrack/libnetfilter_conntrack.h>
+#include <libnetfilter_queue/libnetfilter_queue.h>
+#include <libnetfilter_queue/libnetfilter_queue_udp.h>
+#include <libnetfilter_queue/pktbuff.h>
+#include <linux/netfilter.h>
+
+#define DHCPV6_CLIENT_PORT 546
+
+static uint16_t dhcpv6_port;
+
+/* Timeouts for DHCPv6 replies, in seconds, indexed by message type. */
+static const int dhcpv6_timeouts[] = {
+ 0, /* No message has type 0. */
+ 120, /* Solicit. */
+ 0, /* Advertise. */
+ 30, /* Request. */
+ 4, /* Confirm. */
+ 600, /* Renew. */
+ 600, /* Rebind. */
+ 0, /* Reply. */
+ 1, /* Release. */
+ 1, /* Decline. */
+ 0, /* Reconfigure. */
+ 120, /* Information Request. */
+ 0, /* Relay-forward. */
+ 0 /* Relay-reply. */
+};
+
+static inline int ipv6_addr_is_multicast(const struct in6_addr *addr)
+{
+ return (addr->s6_addr32[0] & htonl(0xFF000000)) == htonl(0xFF000000);
+}
+
+static int
+dhcpv6_helper_cb(struct pkt_buff *pkt, uint32_t protoff,
+ struct myct *myct, uint32_t ctinfo)
+{
+ struct iphdr *iph = (struct iphdr *)pktb_network_header(pkt);
+ struct ip6_hdr *ip6h = (struct ip6_hdr *)pktb_network_header(pkt);
+ int dir = CTINFO2DIR(ctinfo);
+ union nfct_attr_grp_addr addr;
+ struct nf_expect *exp;
+ uint8_t *dhcpv6_msg_type;
+
+ if (iph->version != 6 || !ipv6_addr_is_multicast(&ip6h->ip6_dst))
+ return NF_ACCEPT;
+
+ dhcpv6_msg_type = pktb_network_header(pkt) + protoff + sizeof(struct udphdr);
+ if (*dhcpv6_msg_type > ARRAY_SIZE(dhcpv6_timeouts)) {
+ printf("Dropping DHCPv6 message with bad type %u\n",
+ *dhcpv6_msg_type);
+ return NF_DROP;
+ }
+
+ exp = nfexp_new();
+ if (exp == NULL)
+ return NF_ACCEPT;
+
+ cthelper_get_addr_src(myct->ct, dir, &addr);
+
+ if (cthelper_expect_init(exp, myct->ct, 0, NULL, &addr,
+ IPPROTO_UDP, NULL, &dhcpv6_port,
+ NF_CT_EXPECT_PERMANENT)) {
+ nfexp_destroy(exp);
+ return NF_DROP;
+ }
+
+ myct->exp = exp;
+
+ if (dhcpv6_timeouts[*dhcpv6_msg_type] > 0) {
+ nfct_set_attr_u32(myct->ct, ATTR_TIMEOUT,
+ dhcpv6_timeouts[*dhcpv6_msg_type]);
+ }
+
+ return NF_ACCEPT;
+}
+
+static struct ctd_helper dhcpv6_helper = {
+ .name = "dhcpv6",
+ .l4proto = IPPROTO_UDP,
+ .cb = dhcpv6_helper_cb,
+ .policy = {
+ [0] = {
+ .name = "dhcpv6",
+ .expect_max = 1,
+ .expect_timeout = 300,
+ },
+ },
+};
+
+void __attribute__ ((constructor)) dhcpv6_init(void);
+
+void dhcpv6_init(void)
+{
+ dhcpv6_port = htons(DHCPV6_CLIENT_PORT);
+ helper_register(&dhcpv6_helper);
+}