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ip_carp.c
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ip_carp.c
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/*-
* SPDX-License-Identifier: BSD-2-Clause
*
* Copyright (c) 2002 Michael Shalayeff.
* Copyright (c) 2003 Ryan McBride.
* Copyright (c) 2011 Gleb Smirnoff <glebius@FreeBSD.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR OR HIS RELATIVES BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF MIND, USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/cdefs.h>
#include "opt_bpf.h"
#include "opt_inet.h"
#include "opt_inet6.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/devctl.h>
#include <sys/jail.h>
#include <sys/kernel.h>
#include <sys/limits.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/module.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/socket.h>
#include <sys/sockio.h>
#include <sys/sysctl.h>
#include <sys/syslog.h>
#include <sys/taskqueue.h>
#include <sys/counter.h>
#include <net/ethernet.h>
#include <net/if.h>
#include <net/if_var.h>
#include <net/if_dl.h>
#include <net/if_llatbl.h>
#include <net/if_private.h>
#include <net/if_types.h>
#include <net/route.h>
#include <net/vnet.h>
#if defined(INET) || defined(INET6)
#include <netinet/in.h>
#include <netinet/in_var.h>
#include <netinet/ip_carp.h>
#include <netinet/ip_carp_nl.h>
#include <netinet/ip.h>
#include <machine/in_cksum.h>
#endif
#ifdef INET
#include <netinet/ip_var.h>
#include <netinet/if_ether.h>
#endif
#ifdef INET6
#include <netinet/icmp6.h>
#include <netinet/ip6.h>
#include <netinet6/in6_var.h>
#include <netinet6/ip6_var.h>
#include <netinet6/scope6_var.h>
#include <netinet6/nd6.h>
#endif
#include <netlink/netlink.h>
#include <netlink/netlink_ctl.h>
#include <netlink/netlink_generic.h>
#include <netlink/netlink_message_parser.h>
#include <crypto/sha1.h>
static MALLOC_DEFINE(M_CARP, "CARP", "CARP addresses");
struct carp_softc {
struct ifnet *sc_carpdev; /* Pointer to parent ifnet. */
struct ifaddr **sc_ifas; /* Our ifaddrs. */
struct sockaddr_dl sc_addr; /* Our link level address. */
struct callout sc_ad_tmo; /* Advertising timeout. */
#ifdef INET
struct callout sc_md_tmo; /* Master down timeout. */
#endif
#ifdef INET6
struct callout sc_md6_tmo; /* XXX: Master down timeout. */
#endif
struct mtx sc_mtx;
int sc_vhid;
int sc_advskew;
int sc_advbase;
struct in_addr sc_carpaddr;
struct in6_addr sc_carpaddr6;
int sc_naddrs;
int sc_naddrs6;
int sc_ifasiz;
enum { INIT = 0, BACKUP, MASTER } sc_state;
int sc_suppress;
int sc_sendad_errors;
#define CARP_SENDAD_MAX_ERRORS 3
int sc_sendad_success;
#define CARP_SENDAD_MIN_SUCCESS 3
int sc_init_counter;
uint64_t sc_counter;
/* authentication */
#define CARP_HMAC_PAD 64
unsigned char sc_key[CARP_KEY_LEN];
unsigned char sc_pad[CARP_HMAC_PAD];
SHA1_CTX sc_sha1;
TAILQ_ENTRY(carp_softc) sc_list; /* On the carp_if list. */
LIST_ENTRY(carp_softc) sc_next; /* On the global list. */
};
struct carp_if {
#ifdef INET
int cif_naddrs;
#endif
#ifdef INET6
int cif_naddrs6;
#endif
TAILQ_HEAD(, carp_softc) cif_vrs;
#ifdef INET
struct ip_moptions cif_imo;
#endif
#ifdef INET6
struct ip6_moptions cif_im6o;
#endif
struct ifnet *cif_ifp;
struct mtx cif_mtx;
uint32_t cif_flags;
#define CIF_PROMISC 0x00000001
};
/* Kernel equivalent of struct carpreq, but with more fields for new features.
* */
struct carpkreq {
int carpr_count;
int carpr_vhid;
int carpr_state;
int carpr_advskew;
int carpr_advbase;
unsigned char carpr_key[CARP_KEY_LEN];
/* Everything above this is identical to carpreq */
struct in_addr carpr_addr;
struct in6_addr carpr_addr6;
};
/*
* Brief design of carp(4).
*
* Any carp-capable ifnet may have a list of carp softcs hanging off
* its ifp->if_carp pointer. Each softc represents one unique virtual
* host id, or vhid. The softc has a back pointer to the ifnet. All
* softcs are joined in a global list, which has quite limited use.
*
* Any interface address that takes part in CARP negotiation has a
* pointer to the softc of its vhid, ifa->ifa_carp. That could be either
* AF_INET or AF_INET6 address.
*
* Although, one can get the softc's backpointer to ifnet and traverse
* through its ifp->if_addrhead queue to find all interface addresses
* involved in CARP, we keep a growable array of ifaddr pointers. This
* allows us to avoid grabbing the IF_ADDR_LOCK() in many traversals that
* do calls into the network stack, thus avoiding LORs.
*
* Locking:
*
* Each softc has a lock sc_mtx. It is used to synchronise carp_input_c(),
* callout-driven events and ioctl()s.
*
* To traverse the list of softcs on an ifnet we use CIF_LOCK() or carp_sx.
* To traverse the global list we use the mutex carp_mtx.
*
* Known issues with locking:
*
* - Sending ad, we put the pointer to the softc in an mtag, and no reference
* counting is done on the softc.
* - On module unload we may race (?) with packet processing thread
* dereferencing our function pointers.
*/
/* Accept incoming CARP packets. */
VNET_DEFINE_STATIC(int, carp_allow) = 1;
#define V_carp_allow VNET(carp_allow)
/* Set DSCP in outgoing CARP packets. */
VNET_DEFINE_STATIC(int, carp_dscp) = 56;
#define V_carp_dscp VNET(carp_dscp)
/* Preempt slower nodes. */
VNET_DEFINE_STATIC(int, carp_preempt) = 0;
#define V_carp_preempt VNET(carp_preempt)
/* Log level. */
VNET_DEFINE_STATIC(int, carp_log) = 1;
#define V_carp_log VNET(carp_log)
/* Global advskew demotion. */
VNET_DEFINE_STATIC(int, carp_demotion) = 0;
#define V_carp_demotion VNET(carp_demotion)
/* Send error demotion factor. */
VNET_DEFINE_STATIC(int, carp_senderr_adj) = CARP_MAXSKEW;
#define V_carp_senderr_adj VNET(carp_senderr_adj)
/* Iface down demotion factor. */
VNET_DEFINE_STATIC(int, carp_ifdown_adj) = CARP_MAXSKEW;
#define V_carp_ifdown_adj VNET(carp_ifdown_adj)
static int carp_allow_sysctl(SYSCTL_HANDLER_ARGS);
static int carp_dscp_sysctl(SYSCTL_HANDLER_ARGS);
static int carp_demote_adj_sysctl(SYSCTL_HANDLER_ARGS);
SYSCTL_NODE(_net_inet, IPPROTO_CARP, carp, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
"CARP");
SYSCTL_PROC(_net_inet_carp, OID_AUTO, allow,
CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RWTUN | CTLFLAG_MPSAFE,
&VNET_NAME(carp_allow), 0, carp_allow_sysctl, "I",
"Accept incoming CARP packets");
SYSCTL_PROC(_net_inet_carp, OID_AUTO, dscp,
CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE,
0, 0, carp_dscp_sysctl, "I",
"DSCP value for carp packets");
SYSCTL_INT(_net_inet_carp, OID_AUTO, preempt, CTLFLAG_VNET | CTLFLAG_RW,
&VNET_NAME(carp_preempt), 0, "High-priority backup preemption mode");
SYSCTL_INT(_net_inet_carp, OID_AUTO, log, CTLFLAG_VNET | CTLFLAG_RW,
&VNET_NAME(carp_log), 0, "CARP log level");
SYSCTL_PROC(_net_inet_carp, OID_AUTO, demotion,
CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE,
0, 0, carp_demote_adj_sysctl, "I",
"Adjust demotion factor (skew of advskew)");
SYSCTL_INT(_net_inet_carp, OID_AUTO, senderr_demotion_factor,
CTLFLAG_VNET | CTLFLAG_RW,
&VNET_NAME(carp_senderr_adj), 0, "Send error demotion factor adjustment");
SYSCTL_INT(_net_inet_carp, OID_AUTO, ifdown_demotion_factor,
CTLFLAG_VNET | CTLFLAG_RW,
&VNET_NAME(carp_ifdown_adj), 0,
"Interface down demotion factor adjustment");
VNET_PCPUSTAT_DEFINE(struct carpstats, carpstats);
VNET_PCPUSTAT_SYSINIT(carpstats);
VNET_PCPUSTAT_SYSUNINIT(carpstats);
#define CARPSTATS_ADD(name, val) \
counter_u64_add(VNET(carpstats)[offsetof(struct carpstats, name) / \
sizeof(uint64_t)], (val))
#define CARPSTATS_INC(name) CARPSTATS_ADD(name, 1)
SYSCTL_VNET_PCPUSTAT(_net_inet_carp, OID_AUTO, stats, struct carpstats,
carpstats, "CARP statistics (struct carpstats, netinet/ip_carp.h)");
#define CARP_LOCK_INIT(sc) mtx_init(&(sc)->sc_mtx, "carp_softc", \
NULL, MTX_DEF)
#define CARP_LOCK_DESTROY(sc) mtx_destroy(&(sc)->sc_mtx)
#define CARP_LOCK_ASSERT(sc) mtx_assert(&(sc)->sc_mtx, MA_OWNED)
#define CARP_LOCK(sc) mtx_lock(&(sc)->sc_mtx)
#define CARP_UNLOCK(sc) mtx_unlock(&(sc)->sc_mtx)
#define CIF_LOCK_INIT(cif) mtx_init(&(cif)->cif_mtx, "carp_if", \
NULL, MTX_DEF)
#define CIF_LOCK_DESTROY(cif) mtx_destroy(&(cif)->cif_mtx)
#define CIF_LOCK_ASSERT(cif) mtx_assert(&(cif)->cif_mtx, MA_OWNED)
#define CIF_LOCK(cif) mtx_lock(&(cif)->cif_mtx)
#define CIF_UNLOCK(cif) mtx_unlock(&(cif)->cif_mtx)
#define CIF_FREE(cif) do { \
CIF_LOCK(cif); \
if (TAILQ_EMPTY(&(cif)->cif_vrs)) \
carp_free_if(cif); \
else \
CIF_UNLOCK(cif); \
} while (0)
#define CARP_LOG(...) do { \
if (V_carp_log > 0) \
log(LOG_INFO, "carp: " __VA_ARGS__); \
} while (0)
#define CARP_DEBUG(...) do { \
if (V_carp_log > 1) \
log(LOG_DEBUG, __VA_ARGS__); \
} while (0)
#define IFNET_FOREACH_IFA(ifp, ifa) \
CK_STAILQ_FOREACH((ifa), &(ifp)->if_addrhead, ifa_link) \
if ((ifa)->ifa_carp != NULL)
#define CARP_FOREACH_IFA(sc, ifa) \
CARP_LOCK_ASSERT(sc); \
for (int _i = 0; \
_i < (sc)->sc_naddrs + (sc)->sc_naddrs6 && \
((ifa) = sc->sc_ifas[_i]) != NULL; \
++_i)
#define IFNET_FOREACH_CARP(ifp, sc) \
KASSERT(mtx_owned(&ifp->if_carp->cif_mtx) || \
sx_xlocked(&carp_sx), ("cif_vrs not locked")); \
TAILQ_FOREACH((sc), &(ifp)->if_carp->cif_vrs, sc_list)
#define DEMOTE_ADVSKEW(sc) \
(((sc)->sc_advskew + V_carp_demotion > CARP_MAXSKEW) ? \
CARP_MAXSKEW : \
(((sc)->sc_advskew + V_carp_demotion < 0) ? \
0 : ((sc)->sc_advskew + V_carp_demotion)))
static void carp_input_c(struct mbuf *, struct carp_header *, sa_family_t, int);
static struct carp_softc
*carp_alloc(struct ifnet *);
static void carp_destroy(struct carp_softc *);
static struct carp_if
*carp_alloc_if(struct ifnet *);
static void carp_free_if(struct carp_if *);
static void carp_set_state(struct carp_softc *, int, const char* reason);
static void carp_sc_state(struct carp_softc *);
static void carp_setrun(struct carp_softc *, sa_family_t);
static void carp_master_down(void *);
static void carp_master_down_locked(struct carp_softc *,
const char* reason);
static void carp_send_ad(void *);
static void carp_send_ad_locked(struct carp_softc *);
static void carp_addroute(struct carp_softc *);
static void carp_ifa_addroute(struct ifaddr *);
static void carp_delroute(struct carp_softc *);
static void carp_ifa_delroute(struct ifaddr *);
static void carp_send_ad_all(void *, int);
static void carp_demote_adj(int, char *);
static LIST_HEAD(, carp_softc) carp_list;
static struct mtx carp_mtx;
static struct sx carp_sx;
static struct task carp_sendall_task =
TASK_INITIALIZER(0, carp_send_ad_all, NULL);
static int
carp_is_supported_if(if_t ifp)
{
if (ifp == NULL)
return (ENXIO);
switch (ifp->if_type) {
case IFT_ETHER:
case IFT_L2VLAN:
case IFT_BRIDGE:
break;
default:
return (EOPNOTSUPP);
}
return (0);
}
static void
carp_hmac_prepare(struct carp_softc *sc)
{
uint8_t version = CARP_VERSION, type = CARP_ADVERTISEMENT;
uint8_t vhid = sc->sc_vhid & 0xff;
struct ifaddr *ifa;
int i, found;
#ifdef INET
struct in_addr last, cur, in;
#endif
#ifdef INET6
struct in6_addr last6, cur6, in6;
#endif
CARP_LOCK_ASSERT(sc);
/* Compute ipad from key. */
bzero(sc->sc_pad, sizeof(sc->sc_pad));
bcopy(sc->sc_key, sc->sc_pad, sizeof(sc->sc_key));
for (i = 0; i < sizeof(sc->sc_pad); i++)
sc->sc_pad[i] ^= 0x36;
/* Precompute first part of inner hash. */
SHA1Init(&sc->sc_sha1);
SHA1Update(&sc->sc_sha1, sc->sc_pad, sizeof(sc->sc_pad));
SHA1Update(&sc->sc_sha1, (void *)&version, sizeof(version));
SHA1Update(&sc->sc_sha1, (void *)&type, sizeof(type));
SHA1Update(&sc->sc_sha1, (void *)&vhid, sizeof(vhid));
#ifdef INET
cur.s_addr = 0;
do {
found = 0;
last = cur;
cur.s_addr = 0xffffffff;
CARP_FOREACH_IFA(sc, ifa) {
in.s_addr = ifatoia(ifa)->ia_addr.sin_addr.s_addr;
if (ifa->ifa_addr->sa_family == AF_INET &&
ntohl(in.s_addr) > ntohl(last.s_addr) &&
ntohl(in.s_addr) < ntohl(cur.s_addr)) {
cur.s_addr = in.s_addr;
found++;
}
}
if (found)
SHA1Update(&sc->sc_sha1, (void *)&cur, sizeof(cur));
} while (found);
#endif /* INET */
#ifdef INET6
memset(&cur6, 0, sizeof(cur6));
do {
found = 0;
last6 = cur6;
memset(&cur6, 0xff, sizeof(cur6));
CARP_FOREACH_IFA(sc, ifa) {
in6 = ifatoia6(ifa)->ia_addr.sin6_addr;
if (IN6_IS_SCOPE_EMBED(&in6))
in6.s6_addr16[1] = 0;
if (ifa->ifa_addr->sa_family == AF_INET6 &&
memcmp(&in6, &last6, sizeof(in6)) > 0 &&
memcmp(&in6, &cur6, sizeof(in6)) < 0) {
cur6 = in6;
found++;
}
}
if (found)
SHA1Update(&sc->sc_sha1, (void *)&cur6, sizeof(cur6));
} while (found);
#endif /* INET6 */
/* convert ipad to opad */
for (i = 0; i < sizeof(sc->sc_pad); i++)
sc->sc_pad[i] ^= 0x36 ^ 0x5c;
}
static void
carp_hmac_generate(struct carp_softc *sc, uint32_t counter[2],
unsigned char md[20])
{
SHA1_CTX sha1ctx;
CARP_LOCK_ASSERT(sc);
/* fetch first half of inner hash */
bcopy(&sc->sc_sha1, &sha1ctx, sizeof(sha1ctx));
SHA1Update(&sha1ctx, (void *)counter, sizeof(sc->sc_counter));
SHA1Final(md, &sha1ctx);
/* outer hash */
SHA1Init(&sha1ctx);
SHA1Update(&sha1ctx, sc->sc_pad, sizeof(sc->sc_pad));
SHA1Update(&sha1ctx, md, 20);
SHA1Final(md, &sha1ctx);
}
static int
carp_hmac_verify(struct carp_softc *sc, uint32_t counter[2],
unsigned char md[20])
{
unsigned char md2[20];
CARP_LOCK_ASSERT(sc);
carp_hmac_generate(sc, counter, md2);
return (bcmp(md, md2, sizeof(md2)));
}
/*
* process input packet.
* we have rearranged checks order compared to the rfc,
* but it seems more efficient this way or not possible otherwise.
*/
#ifdef INET
static int
carp_input(struct mbuf **mp, int *offp, int proto)
{
struct mbuf *m = *mp;
struct ip *ip = mtod(m, struct ip *);
struct carp_header *ch;
int iplen, len;
iplen = *offp;
*mp = NULL;
CARPSTATS_INC(carps_ipackets);
if (!V_carp_allow) {
m_freem(m);
return (IPPROTO_DONE);
}
iplen = ip->ip_hl << 2;
if (m->m_pkthdr.len < iplen + sizeof(*ch)) {
CARPSTATS_INC(carps_badlen);
CARP_DEBUG("%s: received len %zd < sizeof(struct carp_header) "
"on %s\n", __func__, m->m_len - sizeof(struct ip),
if_name(m->m_pkthdr.rcvif));
m_freem(m);
return (IPPROTO_DONE);
}
if (iplen + sizeof(*ch) < m->m_len) {
if ((m = m_pullup(m, iplen + sizeof(*ch))) == NULL) {
CARPSTATS_INC(carps_hdrops);
CARP_DEBUG("%s: pullup failed\n", __func__);
return (IPPROTO_DONE);
}
ip = mtod(m, struct ip *);
}
ch = (struct carp_header *)((char *)ip + iplen);
/*
* verify that the received packet length is
* equal to the CARP header
*/
len = iplen + sizeof(*ch);
if (len > m->m_pkthdr.len) {
CARPSTATS_INC(carps_badlen);
CARP_DEBUG("%s: packet too short %d on %s\n", __func__,
m->m_pkthdr.len,
if_name(m->m_pkthdr.rcvif));
m_freem(m);
return (IPPROTO_DONE);
}
if ((m = m_pullup(m, len)) == NULL) {
CARPSTATS_INC(carps_hdrops);
return (IPPROTO_DONE);
}
ip = mtod(m, struct ip *);
ch = (struct carp_header *)((char *)ip + iplen);
/* verify the CARP checksum */
m->m_data += iplen;
if (in_cksum(m, len - iplen)) {
CARPSTATS_INC(carps_badsum);
CARP_DEBUG("%s: checksum failed on %s\n", __func__,
if_name(m->m_pkthdr.rcvif));
m_freem(m);
return (IPPROTO_DONE);
}
m->m_data -= iplen;
carp_input_c(m, ch, AF_INET, ip->ip_ttl);
return (IPPROTO_DONE);
}
#endif
#ifdef INET6
static int
carp6_input(struct mbuf **mp, int *offp, int proto)
{
struct mbuf *m = *mp;
struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
struct carp_header *ch;
u_int len;
CARPSTATS_INC(carps_ipackets6);
if (!V_carp_allow) {
m_freem(m);
return (IPPROTO_DONE);
}
/* check if received on a valid carp interface */
if (m->m_pkthdr.rcvif->if_carp == NULL) {
CARPSTATS_INC(carps_badif);
CARP_DEBUG("%s: packet received on non-carp interface: %s\n",
__func__, if_name(m->m_pkthdr.rcvif));
m_freem(m);
return (IPPROTO_DONE);
}
/* verify that we have a complete carp packet */
if (m->m_len < *offp + sizeof(*ch)) {
len = m->m_len;
m = m_pullup(m, *offp + sizeof(*ch));
if (m == NULL) {
CARPSTATS_INC(carps_badlen);
CARP_DEBUG("%s: packet size %u too small\n", __func__, len);
return (IPPROTO_DONE);
}
ip6 = mtod(m, struct ip6_hdr *);
}
ch = (struct carp_header *)(mtod(m, char *) + *offp);
/* verify the CARP checksum */
m->m_data += *offp;
if (in_cksum(m, sizeof(*ch))) {
CARPSTATS_INC(carps_badsum);
CARP_DEBUG("%s: checksum failed, on %s\n", __func__,
if_name(m->m_pkthdr.rcvif));
m_freem(m);
return (IPPROTO_DONE);
}
m->m_data -= *offp;
carp_input_c(m, ch, AF_INET6, ip6->ip6_hlim);
return (IPPROTO_DONE);
}
#endif /* INET6 */
/*
* This routine should not be necessary at all, but some switches
* (VMWare ESX vswitches) can echo our own packets back at us,
* and we must ignore them or they will cause us to drop out of
* MASTER mode.
*
* We cannot catch all cases of network loops. Instead, what we
* do here is catch any packet that arrives with a carp header
* with a VHID of 0, that comes from an address that is our own.
* These packets are by definition "from us" (even if they are from
* a misconfigured host that is pretending to be us).
*
* The VHID test is outside this mini-function.
*/
static int
carp_source_is_self(struct mbuf *m, struct ifaddr *ifa, sa_family_t af)
{
#ifdef INET
struct ip *ip4;
struct in_addr in4;
#endif
#ifdef INET6
struct ip6_hdr *ip6;
struct in6_addr in6;
#endif
switch (af) {
#ifdef INET
case AF_INET:
ip4 = mtod(m, struct ip *);
in4 = ifatoia(ifa)->ia_addr.sin_addr;
return (in4.s_addr == ip4->ip_src.s_addr);
#endif
#ifdef INET6
case AF_INET6:
ip6 = mtod(m, struct ip6_hdr *);
in6 = ifatoia6(ifa)->ia_addr.sin6_addr;
return (memcmp(&in6, &ip6->ip6_src, sizeof(in6)) == 0);
#endif
default:
break;
}
return (0);
}
static void
carp_input_c(struct mbuf *m, struct carp_header *ch, sa_family_t af, int ttl)
{
struct ifnet *ifp = m->m_pkthdr.rcvif;
struct ifaddr *ifa, *match;
struct carp_softc *sc;
uint64_t tmp_counter;
struct timeval sc_tv, ch_tv;
int error;
bool multicast = false;
NET_EPOCH_ASSERT();
/*
* Verify that the VHID is valid on the receiving interface.
*
* There should be just one match. If there are none
* the VHID is not valid and we drop the packet. If
* there are multiple VHID matches, take just the first
* one, for compatibility with previous code. While we're
* scanning, check for obvious loops in the network topology
* (these should never happen, and as noted above, we may
* miss real loops; this is just a double-check).
*/
error = 0;
match = NULL;
IFNET_FOREACH_IFA(ifp, ifa) {
if (match == NULL && ifa->ifa_carp != NULL &&
ifa->ifa_addr->sa_family == af &&
ifa->ifa_carp->sc_vhid == ch->carp_vhid)
match = ifa;
if (ch->carp_vhid == 0 && carp_source_is_self(m, ifa, af))
error = ELOOP;
}
ifa = error ? NULL : match;
if (ifa != NULL)
ifa_ref(ifa);
if (ifa == NULL) {
if (error == ELOOP) {
CARP_DEBUG("dropping looped packet on interface %s\n",
if_name(ifp));
CARPSTATS_INC(carps_badif); /* ??? */
} else {
CARPSTATS_INC(carps_badvhid);
}
m_freem(m);
return;
}
/* verify the CARP version. */
if (ch->carp_version != CARP_VERSION) {
CARPSTATS_INC(carps_badver);
CARP_DEBUG("%s: invalid version %d\n", if_name(ifp),
ch->carp_version);
ifa_free(ifa);
m_freem(m);
return;
}
sc = ifa->ifa_carp;
CARP_LOCK(sc);
if (ifa->ifa_addr->sa_family == AF_INET) {
multicast = IN_MULTICAST(sc->sc_carpaddr.s_addr);
} else {
multicast = IN6_IS_ADDR_MULTICAST(&sc->sc_carpaddr6);
}
ifa_free(ifa);
/* verify that the IP TTL is 255, but only if we're not in unicast mode. */
if (multicast && ttl != CARP_DFLTTL) {
CARPSTATS_INC(carps_badttl);
CARP_DEBUG("%s: received ttl %d != 255 on %s\n", __func__,
ttl, if_name(m->m_pkthdr.rcvif));
goto out;
}
if (carp_hmac_verify(sc, ch->carp_counter, ch->carp_md)) {
CARPSTATS_INC(carps_badauth);
CARP_DEBUG("%s: incorrect hash for VHID %u@%s\n", __func__,
sc->sc_vhid, if_name(ifp));
goto out;
}
tmp_counter = ntohl(ch->carp_counter[0]);
tmp_counter = tmp_counter<<32;
tmp_counter += ntohl(ch->carp_counter[1]);
/* XXX Replay protection goes here */
sc->sc_init_counter = 0;
sc->sc_counter = tmp_counter;
sc_tv.tv_sec = sc->sc_advbase;
sc_tv.tv_usec = DEMOTE_ADVSKEW(sc) * 1000000 / 256;
ch_tv.tv_sec = ch->carp_advbase;
ch_tv.tv_usec = ch->carp_advskew * 1000000 / 256;
switch (sc->sc_state) {
case INIT:
break;
case MASTER:
/*
* If we receive an advertisement from a master who's going to
* be more frequent than us, go into BACKUP state.
*/
if (timevalcmp(&sc_tv, &ch_tv, >) ||
timevalcmp(&sc_tv, &ch_tv, ==)) {
callout_stop(&sc->sc_ad_tmo);
carp_set_state(sc, BACKUP,
"more frequent advertisement received");
carp_setrun(sc, 0);
carp_delroute(sc);
}
break;
case BACKUP:
/*
* If we're pre-empting masters who advertise slower than us,
* and this one claims to be slower, treat him as down.
*/
if (V_carp_preempt && timevalcmp(&sc_tv, &ch_tv, <)) {
carp_master_down_locked(sc,
"preempting a slower master");
break;
}
/*
* If the master is going to advertise at such a low frequency
* that he's guaranteed to time out, we'd might as well just
* treat him as timed out now.
*/
sc_tv.tv_sec = sc->sc_advbase * 3;
if (timevalcmp(&sc_tv, &ch_tv, <)) {
carp_master_down_locked(sc, "master will time out");
break;
}
/*
* Otherwise, we reset the counter and wait for the next
* advertisement.
*/
carp_setrun(sc, af);
break;
}
out:
CARP_UNLOCK(sc);
m_freem(m);
}
static int
carp_prepare_ad(struct mbuf *m, struct carp_softc *sc, struct carp_header *ch)
{
struct m_tag *mtag;
if (sc->sc_init_counter) {
/* this could also be seconds since unix epoch */
sc->sc_counter = arc4random();
sc->sc_counter = sc->sc_counter << 32;
sc->sc_counter += arc4random();
} else
sc->sc_counter++;
ch->carp_counter[0] = htonl((sc->sc_counter>>32)&0xffffffff);
ch->carp_counter[1] = htonl(sc->sc_counter&0xffffffff);
carp_hmac_generate(sc, ch->carp_counter, ch->carp_md);
/* Tag packet for carp_output */
if ((mtag = m_tag_get(PACKET_TAG_CARP, sizeof(struct carp_softc *),
M_NOWAIT)) == NULL) {
m_freem(m);
CARPSTATS_INC(carps_onomem);
return (ENOMEM);
}
bcopy(&sc, mtag + 1, sizeof(sc));
m_tag_prepend(m, mtag);
return (0);
}
/*
* To avoid LORs and possible recursions this function shouldn't
* be called directly, but scheduled via taskqueue.
*/
static void
carp_send_ad_all(void *ctx __unused, int pending __unused)
{
struct carp_softc *sc;
struct epoch_tracker et;
NET_EPOCH_ENTER(et);
mtx_lock(&carp_mtx);
LIST_FOREACH(sc, &carp_list, sc_next)
if (sc->sc_state == MASTER) {
CARP_LOCK(sc);
CURVNET_SET(sc->sc_carpdev->if_vnet);
carp_send_ad_locked(sc);
CURVNET_RESTORE();
CARP_UNLOCK(sc);
}
mtx_unlock(&carp_mtx);
NET_EPOCH_EXIT(et);
}
/* Send a periodic advertisement, executed in callout context. */
static void
carp_send_ad(void *v)
{
struct carp_softc *sc = v;
struct epoch_tracker et;
NET_EPOCH_ENTER(et);
CARP_LOCK_ASSERT(sc);
CURVNET_SET(sc->sc_carpdev->if_vnet);
carp_send_ad_locked(sc);
CURVNET_RESTORE();
CARP_UNLOCK(sc);
NET_EPOCH_EXIT(et);
}
static void
carp_send_ad_error(struct carp_softc *sc, int error)
{
/*
* We track errors and successful sends with this logic:
* - Any error resets success counter to 0.
* - MAX_ERRORS triggers demotion.
* - MIN_SUCCESS successes resets error counter to 0.
* - MIN_SUCCESS reverts demotion, if it was triggered before.
*/
if (error) {
if (sc->sc_sendad_errors < INT_MAX)
sc->sc_sendad_errors++;
if (sc->sc_sendad_errors == CARP_SENDAD_MAX_ERRORS) {
static const char fmt[] = "send error %d on %s";
char msg[sizeof(fmt) + IFNAMSIZ];
sprintf(msg, fmt, error, if_name(sc->sc_carpdev));
carp_demote_adj(V_carp_senderr_adj, msg);
}
sc->sc_sendad_success = 0;
} else if (sc->sc_sendad_errors > 0) {
if (++sc->sc_sendad_success >= CARP_SENDAD_MIN_SUCCESS) {
if (sc->sc_sendad_errors >= CARP_SENDAD_MAX_ERRORS) {
static const char fmt[] = "send ok on %s";
char msg[sizeof(fmt) + IFNAMSIZ];
sprintf(msg, fmt, if_name(sc->sc_carpdev));
carp_demote_adj(-V_carp_senderr_adj, msg);
}
sc->sc_sendad_errors = 0;
}
}
}
/*
* Pick the best ifaddr on the given ifp for sending CARP
* advertisements.
*
* "Best" here is defined by ifa_preferred(). This function is much
* much like ifaof_ifpforaddr() except that we just use ifa_preferred().
*
* (This could be simplified to return the actual address, except that
* it has a different format in AF_INET and AF_INET6.)
*/
static struct ifaddr *
carp_best_ifa(int af, struct ifnet *ifp)
{
struct ifaddr *ifa, *best;
NET_EPOCH_ASSERT();
if (af >= AF_MAX)
return (NULL);
best = NULL;
CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
if (ifa->ifa_addr->sa_family == af &&
(best == NULL || ifa_preferred(best, ifa)))
best = ifa;
}
if (best != NULL)
ifa_ref(best);
return (best);
}
static void
carp_send_ad_locked(struct carp_softc *sc)
{
struct carp_header ch;
struct timeval tv;
struct ifaddr *ifa;
struct carp_header *ch_ptr;
struct mbuf *m;
int len, advskew;
NET_EPOCH_ASSERT();
CARP_LOCK_ASSERT(sc);
advskew = DEMOTE_ADVSKEW(sc);
tv.tv_sec = sc->sc_advbase;
tv.tv_usec = advskew * 1000000 / 256;
ch.carp_version = CARP_VERSION;
ch.carp_type = CARP_ADVERTISEMENT;
ch.carp_vhid = sc->sc_vhid;
ch.carp_advbase = sc->sc_advbase;
ch.carp_advskew = advskew;
ch.carp_authlen = 7; /* XXX DEFINE */
ch.carp_pad1 = 0; /* must be zero */
ch.carp_cksum = 0;
/* XXXGL: OpenBSD picks first ifaddr with needed family. */
#ifdef INET
if (sc->sc_naddrs) {
struct ip *ip;
m = m_gethdr(M_NOWAIT, MT_DATA);
if (m == NULL) {
CARPSTATS_INC(carps_onomem);
goto resched;
}
len = sizeof(*ip) + sizeof(ch);
m->m_pkthdr.len = len;
m->m_pkthdr.rcvif = NULL;
m->m_len = len;
M_ALIGN(m, m->m_len);
if (IN_MULTICAST(sc->sc_carpaddr.s_addr))
m->m_flags |= M_MCAST;
ip = mtod(m, struct ip *);
ip->ip_v = IPVERSION;
ip->ip_hl = sizeof(*ip) >> 2;
ip->ip_tos = V_carp_dscp << IPTOS_DSCP_OFFSET;
ip->ip_len = htons(len);
ip->ip_off = htons(IP_DF);
ip->ip_ttl = CARP_DFLTTL;
ip->ip_p = IPPROTO_CARP;