vrrpd: send ICMPv6 Neighbor Advertisements

Signed-off-by: Quentin Young <qlyoung@cumulusnetworks.com>

1 files changed, 228 insertions, 0 deletions

diff --git a/vrrpd/vrrp_ndisc.c b/vrrpd/vrrp_ndisc.c
new file mode 100644
index 0000000000..ce6c62c07e
--- /dev/null
+++ b/vrrpd/vrrp_ndisc.c
@@ -0,0 +1,228 @@
+/*
+ * VRRP Neighbor Discovery.
+ * Copyright (C) 2019 Cumulus Networks, Inc.
+ *               Quentin Young
+ * Portions:
+ * 	Copyright (C) 2001-2017 Alexandre Cassen
+ *
+ * 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; see the file COPYING; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+#include <zebra.h>
+
+#include <linux/if_packet.h>
+#include <net/ethernet.h>
+#include <netinet/icmp6.h>
+#include <netinet/in.h>
+
+#include "lib/checksum.h"
+#include "lib/if.h"
+#include "lib/ipaddr.h"
+#include "lib/log.h"
+
+#include "vrrp_ndisc.h"
+
+#define VRRP_LOGPFX "[NDISC] "
+
+#define VRRP_NDISC_HOPLIMIT 255
+#define VRRP_NDISC_SIZE                                                        \
+	ETHER_HDR_LEN + sizeof(struct ip6_hdr)                                 \
+		+ sizeof(struct nd_neighbor_advert)                            \
+		+ sizeof(struct nd_opt_hdr) + ETH_ALEN
+
+/* static vars */
+static int ndisc_fd = -1;
+
+/*
+ * Build an unsolicited Neighbour Advertisement.
+ *
+ * ifp
+ *    Interface to send Neighbor Advertisement on
+ *
+ * ip
+ *    IP address to send Neighbor Advertisement for
+ *
+ * buf
+ *    Buffer to fill with IPv6 Neighbor Advertisement message. Includes
+ *    Ethernet header.
+ *
+ * bufsiz
+ *    Size of buf.
+ *
+ * Returns;
+ *    -1 if bufsiz is too small
+ *     0 otherwise
+ */
+static int vrrp_ndisc_una_build(struct interface *ifp, struct ipaddr *ip,
+			       uint8_t *buf, size_t bufsiz)
+{
+	if (bufsiz < VRRP_NDISC_SIZE)
+		return -1;
+
+	memset(buf, 0x00, bufsiz);
+
+	struct ether_header *eth = (struct ether_header *)buf;
+	struct ip6_hdr *ip6h = (struct ip6_hdr *)((char *)eth + ETHER_HDR_LEN);
+	struct nd_neighbor_advert *ndh =
+		(struct nd_neighbor_advert *)((char *)ip6h
+					      + sizeof(struct ip6_hdr));
+	struct icmp6_hdr *icmp6h = &ndh->nd_na_hdr;
+	struct nd_opt_hdr *nd_opt_h =
+		(struct nd_opt_hdr *)((char *)ndh
+				      + sizeof(struct nd_neighbor_advert));
+	char *nd_opt_lladdr =
+		(char *)((char *)nd_opt_h + sizeof(struct nd_opt_hdr));
+	char *lladdr = (char *)ifp->hw_addr;
+
+	/*
+	 * An IPv6 packet with a multicast destination address DST, consisting
+	 * of the sixteen octets DST[1] through DST[16], is transmitted to the
+	 * Ethernet multicast address whose first two octets are the value 3333
+	 * hexadecimal and whose last four octets are the last four octets of
+	 * DST.
+	 *    - RFC2464.7
+	 *
+	 * In this case we are sending to the all nodes multicast address, so
+	 * the last four octets are 0x00 0x00 0x00 0x01.
+	 */
+	memset(eth->ether_dhost, 0, ETH_ALEN);
+	eth->ether_dhost[0] = 0x33;
+	eth->ether_dhost[1] = 0x33;
+	eth->ether_dhost[5] = 1;
+
+	/* Set source Ethernet address to interface link layer address */
+	memcpy(eth->ether_shost, lladdr, ETH_ALEN);
+	eth->ether_type = htons(ETHERTYPE_IPV6);
+
+	/* IPv6 Header */
+	ip6h->ip6_vfc = 6 << 4;
+	ip6h->ip6_plen = htons(sizeof(struct nd_neighbor_advert)
+			       + sizeof(struct nd_opt_hdr) + ETH_ALEN);
+	ip6h->ip6_nxt = IPPROTO_ICMPV6;
+	ip6h->ip6_hlim = VRRP_NDISC_HOPLIMIT;
+	memcpy(&ip6h->ip6_src, &ip->ipaddr_v6, sizeof(struct in6_addr));
+	/* All nodes multicast address */
+	ip6h->ip6_dst.s6_addr[0] = 0xFF;
+	ip6h->ip6_dst.s6_addr[1] = 0x02;
+	ip6h->ip6_dst.s6_addr[15] = 0x01;
+
+	/* ICMPv6 Header */
+	ndh->nd_na_type = ND_NEIGHBOR_ADVERT;
+	ndh->nd_na_flags_reserved |= ND_NA_FLAG_ROUTER;
+	ndh->nd_na_flags_reserved |= ND_NA_FLAG_OVERRIDE;
+	memcpy(&ndh->nd_na_target, &ip->ipaddr_v6, sizeof(struct in6_addr));
+
+	/* NDISC Option header */
+	nd_opt_h->nd_opt_type = ND_OPT_TARGET_LINKADDR;
+	nd_opt_h->nd_opt_len = 1;
+	memcpy(nd_opt_lladdr, lladdr, ETH_ALEN);
+
+	/* Compute checksum */
+	uint32_t len = sizeof(struct nd_neighbor_advert)
+		       + sizeof(struct nd_opt_hdr) + ETH_ALEN;
+	struct ipv6_ph ph = {};
+	ph.src = ip6h->ip6_src;
+	ph.dst = ip6h->ip6_dst;
+	ph.ulpl = htonl(len);
+	ph.next_hdr = IPPROTO_ICMPV6;
+	icmp6h->icmp6_cksum = in_cksum_with_ph6(&ph, (void *)icmp6h, len);
+
+	return 0;
+}
+
+int vrrp_ndisc_una_send(struct vrrp_router *r, struct ipaddr *ip)
+{
+	assert(r->family == AF_INET6);
+
+	int ret = 0;
+	struct interface *ifp = r->mvl_ifp;
+
+	uint8_t buf[VRRP_NDISC_SIZE];
+	ret = vrrp_ndisc_una_build(ifp, ip, buf, sizeof(buf));
+
+	if (ret == -1)
+		return ret;
+
+	struct sockaddr_ll sll;
+	ssize_t len;
+
+	/* Build the dst device */
+	memset(&sll, 0, sizeof(sll));
+	sll.sll_family = AF_PACKET;
+	memcpy(sll.sll_addr, ifp->hw_addr, ETH_ALEN);
+	sll.sll_halen = ETH_ALEN;
+	sll.sll_ifindex = (int)ifp->ifindex;
+
+	char ipbuf[INET6_ADDRSTRLEN];
+	ipaddr2str(ip, ipbuf, sizeof(ipbuf));
+
+	zlog_debug(VRRP_LOGPFX VRRP_LOGPFX_VRID
+		   "Sending unsolicited Neighbor Advertisement on %s for %s",
+		   r->vr->vrid, ifp->name, ipbuf);
+
+	len = sendto(ndisc_fd, buf, VRRP_NDISC_SIZE, 0, (struct sockaddr *)&sll,
+		     sizeof(sll));
+
+	if (len < 0) {
+		zlog_err(
+			VRRP_LOGPFX VRRP_LOGPFX_VRID
+			"Error sending unsolicited Neighbor Advertisement on %s for %s",
+			r->vr->vrid, ifp->name, ipbuf);
+		ret = -1;
+	}
+
+	return ret;
+}
+
+int vrrp_ndisc_una_send_all(struct vrrp_router *r)
+{
+	assert(r->family == AF_INET6);
+
+	struct listnode *ln;
+	struct ipaddr *ip;
+
+	for (ALL_LIST_ELEMENTS_RO(r->addrs, ln, ip))
+		vrrp_ndisc_una_send(r, ip);
+
+	return 0;
+}
+
+void vrrp_ndisc_init(void)
+{
+	vrrp_privs.change(ZPRIVS_RAISE);
+	{
+		ndisc_fd = socket(AF_PACKET, SOCK_RAW, htons(ETH_P_IPV6));
+	}
+	vrrp_privs.change(ZPRIVS_LOWER);
+
+	if (ndisc_fd > 0)
+		zlog_info(
+			VRRP_LOGPFX
+			"Initialized unsolicited neighbor advertisement socket");
+	else
+		zlog_err(
+			VRRP_LOGPFX
+			"Error initializing unsolicited neighbor advertisement socket");
+}
+
+void vrrp_ndisc_fini(void)
+{
+	close(ndisc_fd);
+	ndisc_fd = -1;
+}
+
+bool vrrp_ndisc_is_init(void)
+{
+	return ndisc_fd > 0;
+}