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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* VRRP Neighbor Discovery.
* Copyright (C) 2019 Cumulus Networks, Inc.
* Quentin Young
*
* Portions:
* Copyright (C) 2001-2017 Alexandre Cassen
*/
#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_debug.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 *)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;
/* Suppress static analysis warnings about accessing icmp6 oob */
void *offset = icmp6h;
icmp6h->icmp6_cksum = in_cksum_with_ph6(&ph, offset, 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));
DEBUGD(&vrrp_dbg_ndisc,
VRRP_LOGPFX VRRP_LOGPFX_VRID VRRP_LOGPFX_FAM
"Sending unsolicited Neighbor Advertisement on %s for %s",
r->vr->vrid, family2str(r->family), ifp->name, ipbuf);
if (DEBUG_MODE_CHECK(&vrrp_dbg_ndisc, DEBUG_MODE_ALL)
&& DEBUG_MODE_CHECK(&vrrp_dbg_pkt, DEBUG_MODE_ALL))
zlog_hexdump(buf, VRRP_NDISC_SIZE);
len = sendto(ndisc_fd, buf, VRRP_NDISC_SIZE, 0, (struct sockaddr *)&sll,
sizeof(sll));
if (len < 0) {
zlog_err(
VRRP_LOGPFX VRRP_LOGPFX_VRID VRRP_LOGPFX_FAM
"Error sending unsolicited Neighbor Advertisement on %s for %s",
r->vr->vrid, family2str(r->family), ifp->name, ipbuf);
ret = -1;
} else {
++r->stats.una_tx_cnt;
}
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)
{
frr_with_privs(&vrrp_privs) {
ndisc_fd = socket(AF_PACKET, SOCK_RAW, htons(ETH_P_IPV6));
}
if (ndisc_fd > 0) {
DEBUGD(&vrrp_dbg_sock,
VRRP_LOGPFX "Initialized Neighbor Discovery socket");
DEBUGD(&vrrp_dbg_ndisc,
VRRP_LOGPFX "Initialized Neighbor Discovery subsystem");
} else {
zlog_err(VRRP_LOGPFX
"Error initializing Neighbor Discovery socket");
}
}
void vrrp_ndisc_fini(void)
{
close(ndisc_fd);
ndisc_fd = -1;
DEBUGD(&vrrp_dbg_ndisc,
VRRP_LOGPFX "Deinitialized Neighbor Discovery subsystem");
}
bool vrrp_ndisc_is_init(void)
{
return ndisc_fd > 0;
}
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