/* * ntp_proto.c - NTP version 4 protocol machinery * * ATTENTION: Get approval from Harlan on all changes to this file! * (Harlan will be discussing these changes with Dave Mills.) * */ #ifdef HAVE_CONFIG_H #include #endif #include "ntpd.h" #include "ntp_stdlib.h" #include "ntp_unixtime.h" #include "ntp_control.h" #include "ntp_string.h" #include "ntp_leapsec.h" #include "ntp_psl.h" #include "refidsmear.h" #include #ifdef HAVE_LIBSCF_H #include #endif #ifdef HAVE_UNISTD_H #include #endif /* [Bug 3031] define automatic broadcastdelay cutoff preset */ #ifndef BDELAY_DEFAULT # define BDELAY_DEFAULT (-0.050) #endif #define SRVFUZ_SHIFT 6 /* 64 seconds */ #define SRVRSP_FUZZ(x) \ do { \ x.l_uf = 0; \ x.l_ui &= ~((1 << SRVFUZ_SHIFT) - 1U); \ } while (FALSE) /* * This macro defines the authentication state. If x is 1 authentication * is required; otherwise it is optional. */ #define AUTH(x, y) ((x) ? (y) == AUTH_OK \ : (y) == AUTH_OK || (y) == AUTH_NONE) typedef enum auth_state { AUTH_UNKNOWN = -1, /* Unknown */ AUTH_NONE, /* authentication not required */ AUTH_OK, /* authentication OK */ AUTH_ERROR, /* authentication error */ AUTH_CRYPTO /* crypto_NAK */ } auth_code; /* * Set up Kiss Code values */ typedef enum kiss_codes { NOKISS, /* No Kiss Code */ RATEKISS, /* Rate limit Kiss Code */ DENYKISS, /* Deny Kiss */ RSTRKISS, /* Restricted Kiss */ XKISS /* Experimental Kiss */ } kiss_code; typedef enum nak_error_codes { NONAK, /* No NAK seen */ INVALIDNAK, /* NAK cannot be used */ VALIDNAK /* NAK is valid */ } nak_code; /* * traffic shaping parameters */ #define NTP_IBURST 6 /* packets in iburst */ #define RESP_DELAY 1 /* refclock burst delay (s) */ /* * pool soliciting restriction duration (s) */ #define POOL_SOLICIT_WINDOW 8 /* * flag bits propagated from pool/manycast to individual peers */ #define POOL_FLAG_PMASK (FLAG_IBURST | FLAG_NOSELECT) /* * peer_select groups statistics for a peer used by clock_select() and * clock_cluster(). */ typedef struct peer_select_tag { struct peer * peer; double synch; /* sync distance */ double error; /* jitter */ double seljit; /* selection jitter */ } peer_select; /* * System variables are declared here. Unless specified otherwise, all * times are in seconds. */ u_char sys_leap; /* system leap indicator, use set_sys_leap() to change this */ u_char xmt_leap; /* leap indicator sent in client requests, set up by set_sys_leap() */ u_char sys_stratum; /* system stratum */ s_char sys_precision; /* local clock precision (log2 s) */ double sys_rootdelay; /* roundtrip delay to root (primary source) */ double sys_rootdisp; /* dispersion to root (primary source) */ double prev_rootdisp; /* previous root dispersion */ double p2_rootdisp; /* previous previous root dispersion */ u_int32 sys_refid; /* reference id (network byte order) */ l_fp sys_reftime; /* last update time */ l_fp prev_reftime; /* previous sys_reftime */ l_fp p2_reftime; /* previous previous sys_reftime */ u_long prev_time; /* "current_time" when saved prev_time */ u_long p2_time; /* previous prev_time */ struct peer *sys_peer; /* current peer */ #ifdef LEAP_SMEAR struct leap_smear_info leap_smear; #endif int leap_sec_in_progress; /* * Rate controls. Leaky buckets are used to throttle the packet * transmission rates in order to protect busy servers such as at NIST * and USNO. There is a counter for each association and another for KoD * packets. The association counter decrements each second, but not * below zero. Each time a packet is sent the counter is incremented by * a configurable value representing the average interval between * packets. A packet is delayed as long as the counter is greater than * zero. Note this does not affect the time value computations. */ /* * Nonspecified system state variables */ int sys_bclient; /* broadcast client enable */ int sys_mclient; /* multicast client enable */ double sys_bdelay; /* broadcast client default delay */ int sys_authenticate; /* requre authentication for config */ l_fp sys_authdelay; /* authentication delay */ double sys_offset; /* current local clock offset */ double sys_mindisp = MINDISPERSE; /* minimum distance (s) */ double sys_maxdist = MAXDISTANCE; /* selection threshold */ double sys_jitter; /* system jitter */ u_long sys_epoch; /* last clock update time */ static double sys_clockhop; /* clockhop threshold */ static int leap_vote_ins; /* leap consensus for insert */ static int leap_vote_del; /* leap consensus for delete */ keyid_t sys_private; /* private value for session seed */ int sys_manycastserver; /* respond to manycast client pkts */ int ntp_mode7; /* respond to ntpdc (mode7) */ int peer_ntpdate; /* active peers in ntpdate mode */ int sys_survivors; /* truest of the truechimers */ char *sys_ident = NULL; /* identity scheme */ /* * TOS and multicast mapping stuff */ int sys_floor = 0; /* cluster stratum floor */ u_char sys_bcpollbstep = 0; /* Broadcast Poll backstep gate */ int sys_ceiling = STRATUM_UNSPEC - 1; /* cluster stratum ceiling */ int sys_minsane = 1; /* minimum candidates */ int sys_minclock = NTP_MINCLOCK; /* minimum candidates */ int sys_maxclock = NTP_MAXCLOCK; /* maximum candidates */ int sys_cohort = 0; /* cohort switch */ int sys_orphan = STRATUM_UNSPEC + 1; /* orphan stratum */ int sys_orphwait = NTP_ORPHWAIT; /* orphan wait */ int sys_beacon = BEACON; /* manycast beacon interval */ u_int sys_ttlmax; /* max ttl mapping vector index */ u_char sys_ttl[MAX_TTL]; /* ttl mapping vector */ /* * Statistics counters - first the good, then the bad */ u_long sys_stattime; /* elapsed time */ u_long sys_received; /* packets received */ u_long sys_processed; /* packets for this host */ u_long sys_newversion; /* current version */ u_long sys_oldversion; /* old version */ u_long sys_restricted; /* access denied */ u_long sys_badlength; /* bad length or format */ u_long sys_badauth; /* bad authentication */ u_long sys_declined; /* declined */ u_long sys_limitrejected; /* rate exceeded */ u_long sys_kodsent; /* KoD sent */ /* * Mechanism knobs: how soon do we peer_clear() or unpeer()? * * The default way is "on-receipt". If this was a packet from a * well-behaved source, on-receipt will offer the fastest recovery. * If this was from a DoS attack, the default way makes it easier * for a bad-guy to DoS us. So look and see what bites you harder * and choose according to your environment. */ int peer_clear_digest_early = 1; /* bad digest (TEST5) and Autokey */ int unpeer_crypto_early = 1; /* bad crypto (TEST9) */ int unpeer_crypto_nak_early = 1; /* crypto_NAK (TEST5) */ int unpeer_digest_early = 1; /* bad digest (TEST5) */ int dynamic_interleave = DYNAMIC_INTERLEAVE; /* Bug 2978 mitigation */ int kiss_code_check(u_char hisleap, u_char hisstratum, u_char hismode, u_int32 refid); nak_code valid_NAK (struct peer *peer, struct recvbuf *rbufp, u_char hismode); static double root_distance (struct peer *); static void clock_combine (peer_select *, int, int); static void peer_xmit (struct peer *); static void fast_xmit (struct recvbuf *, int, keyid_t, int); static void pool_xmit (struct peer *); static void clock_update (struct peer *); static void measure_precision(void); static double measure_tick_fuzz(void); static int local_refid (struct peer *); static int peer_unfit (struct peer *); #ifdef AUTOKEY static int group_test (char *, char *); #endif /* AUTOKEY */ #ifdef WORKER void pool_name_resolved (int, int, void *, const char *, const char *, const struct addrinfo *, const struct addrinfo *); #endif /* WORKER */ const char * amtoa (int am); void set_sys_leap( u_char new_sys_leap ) { sys_leap = new_sys_leap; xmt_leap = sys_leap; /* * Under certain conditions we send faked leap bits to clients, so * eventually change xmt_leap below, but never change LEAP_NOTINSYNC. */ if (xmt_leap != LEAP_NOTINSYNC) { if (leap_sec_in_progress) { /* always send "not sync" */ xmt_leap = LEAP_NOTINSYNC; } #ifdef LEAP_SMEAR else { /* * If leap smear is enabled in general we must * never send a leap second warning to clients, * so make sure we only send "in sync". */ if (leap_smear.enabled) xmt_leap = LEAP_NOWARNING; } #endif /* LEAP_SMEAR */ } } /* * Kiss Code check */ int kiss_code_check( u_char hisleap, u_char hisstratum, u_char hismode, u_int32 refid ) { if ( hismode == MODE_SERVER && hisleap == LEAP_NOTINSYNC && hisstratum == STRATUM_UNSPEC) { if(memcmp(&refid,"RATE", 4) == 0) { return (RATEKISS); } else if(memcmp(&refid,"DENY", 4) == 0) { return (DENYKISS); } else if(memcmp(&refid,"RSTR", 4) == 0) { return (RSTRKISS); } else if(memcmp(&refid,"X", 1) == 0) { return (XKISS); } } return (NOKISS); } /* * Check that NAK is valid */ nak_code valid_NAK( struct peer *peer, struct recvbuf *rbufp, u_char hismode ) { int base_packet_length = MIN_V4_PKT_LEN; int remainder_size; struct pkt * rpkt; int keyid; l_fp p_org; /* origin timestamp */ const l_fp * myorg; /* selected peer origin */ /* * Check to see if there is something beyond the basic packet */ if (rbufp->recv_length == base_packet_length) { return NONAK; } remainder_size = rbufp->recv_length - base_packet_length; /* * Is this a potential NAK? */ if (remainder_size != 4) { return NONAK; } /* * Only server responses can contain NAK's */ if (hismode != MODE_SERVER && hismode != MODE_ACTIVE && hismode != MODE_PASSIVE ) { return INVALIDNAK; } /* * Make sure that the extra field in the packet is all zeros */ rpkt = &rbufp->recv_pkt; keyid = ntohl(((u_int32 *)rpkt)[base_packet_length / 4]); if (keyid != 0) { return INVALIDNAK; } /* * During the first few packets of the autokey dance there will * not (yet) be a keyid, but in this case FLAG_SKEY is set. * So the NAK is invalid if either there's no peer, or * if the keyid is 0 and FLAG_SKEY is not set. */ if (!peer || (!peer->keyid && !(peer->flags & FLAG_SKEY))) { return INVALIDNAK; } /* * The ORIGIN must match, or this cannot be a valid NAK, either. */ if (FLAG_LOOPNONCE & peer->flags) { myorg = &peer->nonce; } else { if (peer->flip > 0) { myorg = &peer->borg; } else { myorg = &peer->aorg; } } NTOHL_FP(&rpkt->org, &p_org); if (L_ISZERO(&p_org) || L_ISZERO( myorg) || !L_ISEQU(&p_org, myorg)) { return INVALIDNAK; } /* If we ever passed all that checks, we should be safe. Well, * as safe as we can ever be with an unauthenticated crypto-nak. */ return VALIDNAK; } /* * transmit - transmit procedure called by poll timeout */ void transmit( struct peer *peer /* peer structure pointer */ ) { u_char hpoll; /* * The polling state machine. There are two kinds of machines, * those that never expect a reply (broadcast and manycast * server modes) and those that do (all other modes). The dance * is intricate... */ hpoll = peer->hpoll; /* * If we haven't received anything (even if unsync) since last * send, reset ppoll. */ if (peer->outdate > peer->timelastrec && !peer->reach) peer->ppoll = peer->maxpoll; /* * In broadcast mode the poll interval is never changed from * minpoll. */ if (peer->cast_flags & (MDF_BCAST | MDF_MCAST)) { peer->outdate = current_time; poll_update(peer, hpoll, 0); if (sys_leap != LEAP_NOTINSYNC) peer_xmit(peer); return; } /* * In manycast mode we start with unity ttl. The ttl is * increased by one for each poll until either sys_maxclock * servers have been found or the maximum ttl is reached. When * sys_maxclock servers are found we stop polling until one or * more servers have timed out or until less than sys_minclock * associations turn up. In this case additional better servers * are dragged in and preempt the existing ones. Once every * sys_beacon seconds we are to transmit unconditionally, but * this code is not quite right -- peer->unreach counts polls * and is being compared with sys_beacon, so the beacons happen * every sys_beacon polls. */ if (peer->cast_flags & MDF_ACAST) { peer->outdate = current_time; poll_update(peer, hpoll, 0); if (peer->unreach > sys_beacon) { peer->unreach = 0; peer->ttl = 0; peer_xmit(peer); } else if ( sys_survivors < sys_minclock || peer_associations < sys_maxclock) { if (peer->ttl < sys_ttlmax) peer->ttl++; peer_xmit(peer); } peer->unreach++; return; } /* * Pool associations transmit unicast solicitations when there * are less than a hard limit of 2 * sys_maxclock associations, * and either less than sys_minclock survivors or less than * sys_maxclock associations. The hard limit prevents unbounded * growth in associations if the system clock or network quality * result in survivor count dipping below sys_minclock often. * This was observed testing with pool, where sys_maxclock == 12 * resulted in 60 associations without the hard limit. A * similar hard limit on manycastclient ephemeral associations * may be appropriate. */ if (peer->cast_flags & MDF_POOL) { peer->outdate = current_time; poll_update(peer, hpoll, 0); if ( (peer_associations <= 2 * sys_maxclock) && ( peer_associations < sys_maxclock || sys_survivors < sys_minclock)) pool_xmit(peer); return; } /* [Bug 3851] drop pool servers which can no longer be reached. */ if (MDF_PCLNT & peer->cast_flags) { if ( (IS_IPV6(&peer->srcadr) && !nonlocal_v6_addr_up) || !nonlocal_v4_addr_up) { unpeer(peer); return; } } /* * In unicast modes the dance is much more intricate. It is * designed to back off whenever possible to minimize network * traffic. */ if (peer->burst == 0) { u_char oreach; /* * Update the reachability status. If not heard for * three consecutive polls, stuff infinity in the clock * filter. */ oreach = peer->reach; peer->outdate = current_time; peer->unreach++; peer->reach <<= 1; if (!peer->reach) { /* * Here the peer is unreachable. If it was * previously reachable raise a trap. Send a * burst if enabled. */ clock_filter(peer, 0., 0., MAXDISPERSE); if (oreach) { peer_unfit(peer); report_event(PEVNT_UNREACH, peer, NULL); } if ( (peer->flags & FLAG_IBURST) && peer->retry == 0) peer->retry = NTP_RETRY; } else { /* * Here the peer is reachable. Send a burst if * enabled and the peer is fit. Reset unreach * for persistent and ephemeral associations. * Unreach is also reset for survivors in * clock_select(). */ hpoll = sys_poll; if (!(peer->flags & FLAG_PREEMPT)) peer->unreach = 0; if ( (peer->flags & FLAG_BURST) && peer->retry == 0 && !peer_unfit(peer)) peer->retry = NTP_RETRY; } /* * Watch for timeout. If ephemeral, toss the rascal; * otherwise, bump the poll interval. Note the * poll_update() routine will clamp it to maxpoll. * If preemptible and we have more peers than maxclock, * and this peer has the minimum score of preemptibles, * demobilize. */ if (peer->unreach >= NTP_UNREACH) { hpoll++; /* ephemeral: no FLAG_CONFIG nor FLAG_PREEMPT */ if (!(peer->flags & (FLAG_CONFIG | FLAG_PREEMPT))) { report_event(PEVNT_RESTART, peer, "timeout"); peer_clear(peer, "TIME"); unpeer(peer); return; } if ( (peer->flags & FLAG_PREEMPT) && (peer_associations > sys_maxclock) && score_all(peer)) { report_event(PEVNT_RESTART, peer, "timeout"); peer_clear(peer, "TIME"); unpeer(peer); return; } } } else { peer->burst--; if (peer->burst == 0) { /* * If ntpdate mode and the clock has not been * set and all peers have completed the burst, * we declare a successful failure. */ if (mode_ntpdate) { peer_ntpdate--; if (peer_ntpdate == 0) { msyslog(LOG_NOTICE, "ntpd: no servers found"); if (!msyslog_term) printf( "ntpd: no servers found\n"); exit (0); } } } } if (peer->retry > 0) peer->retry--; /* * Do not transmit if in broadcast client mode. */ poll_update(peer, hpoll, (peer->hmode == MODE_CLIENT)); if (peer->hmode != MODE_BCLIENT) peer_xmit(peer); return; } #ifdef DEBUG const char * amtoa( int am ) { char *bp; switch(am) { case AM_ERR: return "AM_ERR"; case AM_NOMATCH: return "AM_NOMATCH"; case AM_PROCPKT: return "AM_PROCPKT"; case AM_BCST: return "AM_BCST"; case AM_FXMIT: return "AM_FXMIT"; case AM_MANYCAST: return "AM_MANYCAST"; case AM_NEWPASS: return "AM_NEWPASS"; case AM_NEWBCL: return "AM_NEWBCL"; case AM_POSSBCL: return "AM_POSSBCL"; default: LIB_GETBUF(bp); snprintf(bp, LIB_BUFLENGTH, "AM_#%d", am); return bp; } } #endif /* DEBUG */ /* * receive - receive procedure called for each packet received */ void receive( struct recvbuf *rbufp ) { register struct peer *peer; /* peer structure pointer */ register struct pkt *pkt; /* receive packet pointer */ u_char hisversion; /* packet version */ u_char hisleap; /* packet leap indicator */ u_char hismode; /* packet mode */ u_char hisstratum; /* packet stratum */ r4addr r4a; /* address restrictions */ u_short restrict_mask; /* restrict bits */ const char *hm_str; /* hismode string */ int kissCode = NOKISS; /* Kiss Code */ int has_mac; /* length of MAC field */ int authlen; /* offset of MAC field */ auth_code is_authentic = AUTH_UNKNOWN; /* Was AUTH_NONE */ nak_code crypto_nak_test; /* result of crypto-NAK check */ int retcode = AM_NOMATCH; /* match code */ keyid_t skeyid = 0; /* key IDs */ u_int32 opcode = 0; /* extension field opcode */ sockaddr_u *dstadr_sin; /* active runway */ u_char cast_flags; /* MDF_* flags for newpeer() */ struct peer *peer2; /* aux peer structure pointer */ endpt *match_ep; /* newpeer() local address */ l_fp p_org; /* origin timestamp */ l_fp p_rec; /* receive timestamp */ l_fp p_xmt; /* transmit timestamp */ #ifdef DEBUG const char *am_str; /* association match string */ #endif #ifdef AUTOKEY char hostname[NTP_MAXSTRLEN + 1]; char *groupname = NULL; struct autokey *ap; /* autokey structure pointer */ int rval; /* cookie snatcher */ keyid_t pkeyid = 0, tkeyid = 0; /* key IDs */ #endif /* AUTOKEY */ #ifdef HAVE_NTP_SIGND static unsigned char zero_key[16]; #endif /* HAVE_NTP_SIGND */ /* * Note that there are many places we do not call record_raw_stats(). * * We only want to call it *after* we've sent a response, or perhaps * when we've decided to drop a packet. */ /* * Monitor the packet and get restrictions. Note that the packet * length for control and private mode packets must be checked * by the service routines. Some restrictions have to be handled * later in order to generate a kiss-o'-death packet. */ /* * Bogus port check is before anything, since it probably * reveals a clogging attack. Likewise the mimimum packet size * of 2 bytes (for mode 6/7) must be checked first. */ sys_received++; if (0 == SRCPORT(&rbufp->recv_srcadr) || rbufp->recv_length < 2) { sys_badlength++; return; /* bogus port / length */ } restrictions(&rbufp->recv_srcadr, &r4a); restrict_mask = r4a.rflags; pkt = &rbufp->recv_pkt; hisversion = PKT_VERSION(pkt->li_vn_mode); hismode = (int)PKT_MODE(pkt->li_vn_mode); if (restrict_mask & RES_IGNORE) { DPRINTF(2, ("receive: drop: RES_IGNORE\n")); sys_restricted++; return; /* ignore everything */ } if (hismode == MODE_PRIVATE) { if (!ntp_mode7 || (restrict_mask & RES_NOQUERY)) { DPRINTF(2, ("receive: drop: !mode7 or RES_NOQUERY\n")); sys_restricted++; return; /* no query private */ } process_private(rbufp, !(RES_NOMODIFY & restrict_mask)); return; } if (hismode == MODE_CONTROL) { if (restrict_mask & RES_NOQUERY) { DPRINTF(2, ("receive: drop: RES_NOQUERY\n")); sys_restricted++; return; /* no query control */ } process_control(rbufp, restrict_mask); return; } if (restrict_mask & RES_DONTSERVE) { DPRINTF(2, ("receive: drop: RES_DONTSERVE\n")); sys_restricted++; return; /* no time serve */ } /* If we arrive here, we should have a standard NTP packet. We * check that the minimum size is available and fetch some more * items from the packet once we can be sure they are indeed * there. */ if (rbufp->recv_length < LEN_PKT_NOMAC) { sys_badlength++; return; /* bogus length */ } hisleap = PKT_LEAP(pkt->li_vn_mode); hisstratum = PKT_TO_STRATUM(pkt->stratum); DEBUG_INSIST(0 != hisstratum); /* paranoia check PKT_TO_STRATUM result */ /* TODO: this should be in a unit test */ DPRINTF(1, ("receive: at %ld %s<-%s ippeerlimit %d mode %d iflags %s " "restrict %s org 0x%x.%08x xmt 0x%x.%08x\n", current_time, stoa(&rbufp->dstadr->sin), stoa(&rbufp->recv_srcadr), r4a.ippeerlimit, hismode, iflags_str(rbufp->dstadr->flags), rflags_str(restrict_mask), ntohl(pkt->org.l_ui), ntohl(pkt->org.l_uf), ntohl(pkt->xmt.l_ui), ntohl(pkt->xmt.l_uf))); /* * This is for testing. If restricted drop ten percent of * surviving packets. */ if (restrict_mask & RES_FLAKE) { if (ntp_uurandom() < .1) { DPRINTF(2, ("receive: drop: RES_FLAKE\n")); sys_restricted++; return; /* no flakeway */ } } /* ** Format Layer Checks ** ** Validate the packet format. The packet size, packet header, ** and any extension field lengths are checked. We identify ** the beginning of the MAC, to identify the upper limit of ** of the hash computation. ** ** In case of a format layer check violation, the packet is ** discarded with no further processing. */ /* * Version check must be after the query packets, since they * intentionally use an early version. */ if (hisversion == NTP_VERSION) { sys_newversion++; /* new version */ } else if ( !(restrict_mask & RES_VERSION) && hisversion >= NTP_OLDVERSION) { sys_oldversion++; /* previous version */ } else { DPRINTF(2, ("receive: drop: RES_VERSION\n")); sys_badlength++; return; /* old version */ } /* * Figure out his mode and validate the packet. This has some * legacy raunch that probably should be removed. In very early * NTP versions mode 0 was equivalent to what later versions * would interpret as client mode. */ if (hismode == MODE_UNSPEC) { if (hisversion == NTP_OLDVERSION) { hismode = MODE_CLIENT; } else { DPRINTF(2, ("receive: drop: MODE_UNSPEC\n")); sys_badlength++; return; /* invalid mode */ } } /* * Validate the poll interval in the packet. * 0 probably indicates a data-minimized packet. * A valid poll interval is required for RATEKISS, where * a value of 0 is not allowed. We check for this below. * * There might be arguments against this check. If you have * any of these arguments, please let us know. * * At this point, the packet cannot be a mode[67] packet. */ if ( pkt->ppoll && ( (NTP_MINPOLL > pkt->ppoll) || (NTP_MAXPOLL < pkt->ppoll) ) ) { #ifdef BUG3870 DPRINTF(2, ("receive: drop: Invalid ppoll (%d) from %s\n", pkt->ppoll, stoa(&rbufp->recv_srcadr))); sys_badlength++; return; /* invalid packet poll */ #else DPRINTF(2, ("receive: info: Invalid ppoll (%d) from %s\n", pkt->ppoll, stoa(&rbufp->recv_srcadr))); #endif } /* * Parse the extension field if present. We figure out whether * an extension field is present by measuring the MAC size. If * the number of words following the packet header is 0, no MAC * is present and the packet is not authenticated. If 1, the * packet is a crypto-NAK; if 3, the packet is authenticated * with DES; if 5, the packet is authenticated with MD5; if 6, * the packet is authenticated with SHA. If 2 or * 4, the packet * is a runt and discarded forthwith. If greater than 6, an * extension field is present, so we subtract the length of the * field and go around again. * * Note the above description is lame. We should/could also check * the two bytes that make up the EF type and subtype, and then * check the two bytes that tell us the EF length. A legacy MAC * has a 4 byte keyID, and for conforming symmetric keys its value * must be <= 64k, meaning the top two bytes will always be zero. * Since the EF Type of 0 is reserved/unused, there's no way a * conforming legacy MAC could ever be misinterpreted as an EF. * * There is more, but this isn't the place to document it. */ authlen = LEN_PKT_NOMAC; has_mac = rbufp->recv_length - authlen; while (has_mac > 0) { u_int32 len; #ifdef AUTOKEY u_int32 hostlen; struct exten *ep; #endif /*AUTOKEY */ if (has_mac % 4 != 0 || has_mac < (int)MIN_MAC_LEN) { DPRINTF(2, ("receive: drop: bad post-packet length\n")); sys_badlength++; return; /* bad length */ } /* * This next test is clearly wrong - it needlessly * prohibits short EFs (which don't yet exist) */ if (has_mac <= (int)MAX_MAC_LEN) { skeyid = ntohl(((u_int32 *)pkt)[authlen / 4]); break; } else { opcode = ntohl(((u_int32 *)pkt)[authlen / 4]); len = opcode & 0xffff; if ( len % 4 != 0 || len < 4 || (int)len + authlen > rbufp->recv_length) { DPRINTF(2, ("receive: drop: bad EF length\n")); sys_badlength++; return; /* bad length */ } #ifdef AUTOKEY /* * Extract calling group name for later. If * sys_groupname is non-NULL, there must be * a group name provided to elicit a response. */ if ( (opcode & 0x3fff0000) == CRYPTO_ASSOC && sys_groupname != NULL) { ep = (struct exten *)&((u_int32 *)pkt)[authlen / 4]; hostlen = ntohl(ep->vallen); if ( hostlen >= sizeof(hostname) || hostlen > len - offsetof(struct exten, pkt)) { DPRINTF(2, ("receive: drop: bad autokey hostname length\n")); sys_badlength++; return; /* bad length */ } memcpy(hostname, &ep->pkt, hostlen); hostname[hostlen] = '\0'; groupname = strchr(hostname, '@'); if (groupname == NULL) { DPRINTF(2, ("receive: drop: empty autokey groupname\n")); sys_declined++; return; } groupname++; } #endif /* AUTOKEY */ authlen += len; has_mac -= len; } } /* * If has_mac is < 0 we had a malformed packet. */ if (has_mac < 0) { DPRINTF(2, ("receive: drop: post-packet under-read\n")); sys_badlength++; return; /* bad length */ } /* ** Packet Data Verification Layer ** ** This layer verifies the packet data content. If ** authentication is required, a MAC must be present. ** If a MAC is present, it must validate. ** Crypto-NAK? Look - a shiny thing! ** ** If authentication fails, we're done. */ /* * If authentication is explicitly required, a MAC must be present. */ if (restrict_mask & RES_DONTTRUST && has_mac == 0) { DPRINTF(2, ("receive: drop: RES_DONTTRUST\n")); sys_restricted++; return; /* access denied */ } /* * Update the MRU list and finger the cloggers. It can be a * little expensive, so turn it off for production use. * RES_LIMITED and RES_KOD will be cleared in the returned * restrict_mask unless one or both actions are warranted. */ restrict_mask = ntp_monitor(rbufp, restrict_mask); if (restrict_mask & RES_LIMITED) { sys_limitrejected++; if ( !(restrict_mask & RES_KOD) || MODE_BROADCAST == hismode || MODE_SERVER == hismode) { if (MODE_SERVER == hismode) { DPRINTF(1, ("Possibly self-induced rate limiting of MODE_SERVER from %s\n", stoa(&rbufp->recv_srcadr))); } else { DPRINTF(2, ("receive: drop: RES_KOD\n")); } return; /* rate exceeded */ } if (hismode == MODE_CLIENT) { fast_xmit(rbufp, MODE_SERVER, skeyid, restrict_mask); } else { fast_xmit(rbufp, MODE_ACTIVE, skeyid, restrict_mask); } return; /* rate exceeded */ } restrict_mask &= ~RES_KOD; /* * We have tossed out as many buggy packets as possible early in * the game to reduce the exposure to a clogging attack. Now we * have to burn some cycles to find the association and * authenticate the packet if required. Note that we burn only * digest cycles, again to reduce exposure. There may be no * matching association and that's okay. * * More on the autokey mambo. Normally the local interface is * found when the association was mobilized with respect to a * designated remote address. We assume packets arriving from * the remote address arrive via this interface and the local * address used to construct the autokey is the unicast address * of the interface. However, if the sender is a broadcaster, * the interface broadcast address is used instead. * Notwithstanding this technobabble, if the sender is a * multicaster, the broadcast address is null, so we use the * unicast address anyway. Don't ask. */ peer = findpeer(rbufp, hismode, &retcode); dstadr_sin = &rbufp->dstadr->sin; NTOHL_FP(&pkt->org, &p_org); NTOHL_FP(&pkt->rec, &p_rec); NTOHL_FP(&pkt->xmt, &p_xmt); hm_str = modetoa(hismode); #ifdef DEBUG am_str = amtoa(retcode); #endif /* * Authentication is conditioned by three switches: * * NOPEER (RES_NOPEER) do not mobilize an association unless * authenticated * NOTRUST (RES_DONTTRUST) do not allow access unless * authenticated (implies NOPEER) * enable (sys_authenticate) master NOPEER switch, by default * on * * The NOPEER and NOTRUST can be specified on a per-client basis * using the restrict command. The enable switch if on implies * NOPEER for all clients. There are four outcomes: * * NONE The packet has no MAC. * OK the packet has a MAC and authentication succeeds * ERROR the packet has a MAC and authentication fails * CRYPTO crypto-NAK. The MAC has four octets only. * * Note: The AUTH(x, y) macro is used to filter outcomes. If x * is zero, acceptable outcomes of y are NONE and OK. If x is * one, the only acceptable outcome of y is OK. */ crypto_nak_test = valid_NAK(peer, rbufp, hismode); /* * Drop any invalid crypto-NAKs */ if (crypto_nak_test == INVALIDNAK) { report_event(PEVNT_AUTH, peer, "Invalid_NAK"); if (0 != peer) { peer->badNAK++; } msyslog(LOG_ERR, "Invalid-NAK error at %ld %s<-%s", current_time, stoa(dstadr_sin), stoa(&rbufp->recv_srcadr)); return; } if (has_mac == 0) { restrict_mask &= ~RES_MSSNTP; is_authentic = AUTH_NONE; /* not required */ DPRINTF(1, ("receive: at %ld %s<-%s mode %d/%s:%s len %d org 0x%x.%08x xmt 0x%x.%08x NOMAC\n", current_time, stoa(dstadr_sin), stoa(&rbufp->recv_srcadr), hismode, hm_str, am_str, authlen, ntohl(pkt->org.l_ui), ntohl(pkt->org.l_uf), ntohl(pkt->xmt.l_ui), ntohl(pkt->xmt.l_uf))); } else if (crypto_nak_test == VALIDNAK) { restrict_mask &= ~RES_MSSNTP; is_authentic = AUTH_CRYPTO; /* crypto-NAK */ DPRINTF(1, ("receive: at %ld %s<-%s mode %d/%s:%s keyid %08x len %d auth %d org 0x%x.%08x xmt 0x%x.%08x CRYPTONAK\n", current_time, stoa(dstadr_sin), stoa(&rbufp->recv_srcadr), hismode, hm_str, am_str, skeyid, authlen + has_mac, is_authentic, ntohl(pkt->org.l_ui), ntohl(pkt->org.l_uf), ntohl(pkt->xmt.l_ui), ntohl(pkt->xmt.l_uf))); #ifdef HAVE_NTP_SIGND /* * If the signature is 20 bytes long, the last 16 of * which are zero, then this is a Microsoft client * wanting AD-style authentication of the server's * reply. * * This is described in Microsoft's WSPP docs, in MS-SNTP: * http://msdn.microsoft.com/en-us/library/cc212930.aspx */ } else if ( has_mac == MAX_MD5_LEN && (restrict_mask & RES_MSSNTP) && (retcode == AM_FXMIT || retcode == AM_NEWPASS) && (memcmp(zero_key, (char *)pkt + authlen + 4, MAX_MD5_LEN - 4) == 0)) { is_authentic = AUTH_NONE; DPRINTF(1, ("receive: at %ld %s<-%s mode %d/%s:%s len %d org %x.%08x xmt %x.%08x SIGND\n", current_time, stoa(dstadr_sin), stoa(&rbufp->recv_srcadr), hismode, hm_str, am_str, authlen, ntohl(pkt->org.l_ui), ntohl(pkt->org.l_uf), ntohl(pkt->xmt.l_ui), ntohl(pkt->xmt.l_uf))); #endif /* HAVE_NTP_SIGND */ } else { /* * has_mac is not 0 * Not a VALID_NAK * Not an MS-SNTP SIGND packet * * So there is a MAC here. */ restrict_mask &= ~RES_MSSNTP; #ifdef AUTOKEY /* * For autokey modes, generate the session key * and install in the key cache. Use the socket * broadcast or unicast address as appropriate. */ if (crypto_flags && skeyid > NTP_MAXKEY) { /* * More on the autokey dance (AKD). A cookie is * constructed from public and private values. * For broadcast packets, the cookie is public * (zero). For packets that match no * association, the cookie is hashed from the * addresses and private value. For server * packets, the cookie was previously obtained * from the server. For symmetric modes, the * cookie was previously constructed using an * agreement protocol; however, should PKI be * unavailable, we construct a fake agreement as * the EXOR of the peer and host cookies. * * hismode ephemeral persistent * ======================================= * active 0 cookie# * passive 0% cookie# * client sys cookie 0% * server 0% sys cookie * broadcast 0 0 * * # if unsync, 0 * % can't happen */ if (has_mac < (int)MAX_MD5_LEN) { DPRINTF(2, ("receive: drop: MD5 digest too short\n")); sys_badauth++; return; } if (hismode == MODE_BROADCAST) { /* * For broadcaster, use the interface * broadcast address when available; * otherwise, use the unicast address * found when the association was * mobilized. However, if this is from * the wildcard interface, game over. */ if ( crypto_flags && rbufp->dstadr == ANY_INTERFACE_CHOOSE(&rbufp->recv_srcadr)) { DPRINTF(2, ("receive: drop: BCAST from wildcard\n")); sys_restricted++; return; /* no wildcard */ } pkeyid = 0; if (!SOCK_UNSPEC(&rbufp->dstadr->bcast)) dstadr_sin = &rbufp->dstadr->bcast; } else if (peer == NULL) { pkeyid = session_key( &rbufp->recv_srcadr, dstadr_sin, 0, sys_private, 0); } else { pkeyid = peer->pcookie; } /* * The session key includes both the public * values and cookie. In case of an extension * field, the cookie used for authentication * purposes is zero. Note the hash is saved for * use later in the autokey mambo. */ if (authlen > (int)LEN_PKT_NOMAC && pkeyid != 0) { session_key(&rbufp->recv_srcadr, dstadr_sin, skeyid, 0, 2); tkeyid = session_key( &rbufp->recv_srcadr, dstadr_sin, skeyid, pkeyid, 0); } else { tkeyid = session_key( &rbufp->recv_srcadr, dstadr_sin, skeyid, pkeyid, 2); } } #endif /* AUTOKEY */ /* * Compute the cryptosum. Note a clogging attack may * succeed in bloating the key cache. If an autokey, * purge it immediately, since we won't be needing it * again. If the packet is authentic, it can mobilize an * association. Note that there is no key zero. */ if (!authdecrypt(skeyid, (u_int32 *)pkt, authlen, has_mac)) is_authentic = AUTH_ERROR; else is_authentic = AUTH_OK; #ifdef AUTOKEY if (crypto_flags && skeyid > NTP_MAXKEY) authtrust(skeyid, 0); #endif /* AUTOKEY */ DPRINTF(1, ("receive: at %ld %s<-%s mode %d/%s:%s keyid %08x len %d auth %d org 0x%x.%08x xmt 0x%x.%08x MAC\n", current_time, stoa(dstadr_sin), stoa(&rbufp->recv_srcadr), hismode, hm_str, am_str, skeyid, authlen + has_mac, is_authentic, ntohl(pkt->org.l_ui), ntohl(pkt->org.l_uf), ntohl(pkt->xmt.l_ui), ntohl(pkt->xmt.l_uf))); } /* * Bug 3454: * * Now come at this from a different perspective: * - If we expect a MAC and it's not there, we drop it. * - If we expect one keyID and get another, we drop it. * - If we have a MAC ahd it hasn't been validated yet, try. * - if the provided MAC doesn't validate, we drop it. * * There might be more to this. */ if (0 != peer && 0 != peer->keyid) { /* Should we msyslog() any of these? */ /* * This should catch: * - no keyID where one is expected, * - different keyID than what we expect. */ if (peer->keyid != skeyid) { DPRINTF(2, ("receive: drop: Wanted keyID %d, got %d from %s\n", peer->keyid, skeyid, stoa(&rbufp->recv_srcadr))); sys_restricted++; return; /* drop: access denied */ } /* * if has_mac != 0 ... * - If it has not yet been validated, do so. * (under what circumstances might that happen?) * - if missing or bad MAC, log and drop. */ if (0 != has_mac) { if (is_authentic == AUTH_UNKNOWN) { /* How can this happen? */ DPRINTF(2, ("receive: 3454 check: AUTH_UNKNOWN from %s\n", stoa(&rbufp->recv_srcadr))); if (!authdecrypt(skeyid, (u_int32 *)pkt, authlen, has_mac)) { /* MAC invalid or not found */ is_authentic = AUTH_ERROR; } else { is_authentic = AUTH_OK; } } if (is_authentic != AUTH_OK) { DPRINTF(2, ("receive: drop: missing or bad MAC from %s\n", stoa(&rbufp->recv_srcadr))); sys_restricted++; return; /* drop: access denied */ } } } /**/ /* ** On-Wire Protocol Layer ** ** Verify protocol operations consistent with the on-wire protocol. ** The protocol discards bogus and duplicate packets as well as ** minimizes disruptions doe to protocol restarts and dropped ** packets. The operations are controlled by two timestamps: ** the transmit timestamp saved in the client state variables, ** and the origin timestamp in the server packet header. The ** comparison of these two timestamps is called the loopback test. ** The transmit timestamp functions as a nonce to verify that the ** response corresponds to the original request. The transmit ** timestamp also serves to discard replays of the most recent ** packet. Upon failure of either test, the packet is discarded ** with no further action. */ /* * The association matching rules are implemented by a set of * routines and an association table. A packet matching an * association is processed by the peer process for that * association. If there are no errors, an ephemeral association * is mobilized: a broadcast packet mobilizes a broadcast client * aassociation; a manycast server packet mobilizes a manycast * client association; a symmetric active packet mobilizes a * symmetric passive association. */ DPRINTF(1, ("receive: MATCH_ASSOC dispatch: mode %d/%s:%s \n", hismode, hm_str, am_str)); switch (retcode) { /* * This is a client mode packet not matching any association. If * an ordinary client, simply toss a server mode packet back * over the fence. If a manycast client, we have to work a * little harder. * * There are cases here where we do not call record_raw_stats(). */ case AM_FXMIT: /* * If authentication OK, send a server reply; otherwise, * send a crypto-NAK. */ if (!(rbufp->dstadr->flags & INT_MCASTOPEN)) { /* HMS: would be nice to log FAST_XMIT|BADAUTH|RESTRICTED */ record_raw_stats(&rbufp->recv_srcadr, &rbufp->dstadr->sin, &p_org, &p_rec, &p_xmt, &rbufp->recv_time, PKT_LEAP(pkt->li_vn_mode), PKT_VERSION(pkt->li_vn_mode), PKT_MODE(pkt->li_vn_mode), PKT_TO_STRATUM(pkt->stratum), pkt->ppoll, pkt->precision, FPTOD(NTOHS_FP(pkt->rootdelay)), FPTOD(NTOHS_FP(pkt->rootdisp)), pkt->refid, rbufp->recv_length - MIN_V4_PKT_LEN, (u_char *)&pkt->exten); if (AUTH(restrict_mask & RES_DONTTRUST, is_authentic)) { /* Bug 3596: Do we want to fuzz the reftime? */ fast_xmit(rbufp, MODE_SERVER, skeyid, restrict_mask); } else if (is_authentic == AUTH_ERROR) { /* Bug 3596: Do we want to fuzz the reftime? */ fast_xmit(rbufp, MODE_SERVER, 0, restrict_mask); sys_badauth++; } else { DPRINTF(2, ("receive: AM_FXMIT drop: !mcast restricted\n")); sys_restricted++; } return; /* hooray */ } /* * This must be manycast. Do not respond if not * configured as a manycast server. */ if (!sys_manycastserver) { DPRINTF(2, ("receive: AM_FXMIT drop: Not manycastserver\n")); sys_restricted++; return; /* not enabled */ } #ifdef AUTOKEY /* * Do not respond if not the same group. */ if (group_test(groupname, NULL)) { DPRINTF(2, ("receive: AM_FXMIT drop: empty groupname\n")); sys_declined++; return; } #endif /* AUTOKEY */ /* * Do not respond if we are not synchronized or our * stratum is greater than the manycaster or the * manycaster has already synchronized to us. */ if ( sys_leap == LEAP_NOTINSYNC || sys_stratum >= hisstratum || (!sys_cohort && sys_stratum == hisstratum + 1) || rbufp->dstadr->addr_refid == pkt->refid # ifdef WORDS_BIGENDIAN /* see local_refid() comment */ || ( IS_IPV6(&rbufp->dstadr->sin) &&rbufp->dstadr->old_refid == pkt->refid) # endif ) { DPRINTF(2, ("receive: sys leap: %0x, sys_stratum %d > hisstratum+1 %d, !sys_cohort %d && sys_stratum == hisstratum+1, loop refid %#x == pkt refid %#x\n", sys_leap, sys_stratum, hisstratum + 1, !sys_cohort, rbufp->dstadr->addr_refid, pkt->refid)); DPRINTF(2, ("receive: AM_FXMIT drop: LEAP_NOTINSYNC || stratum || loop\n")); sys_declined++; return; /* no help */ } /* * Do not respond if the packet came into an IPv6 link-local * address on an interface where we also have a usable * global address, to avoid duplicate associations. */ if (INT_LL_OF_GLOB & rbufp->dstadr->flags) { DPRINTF(2, ("receive: declining manycast solicitation on link-local IPv6\n")); sys_declined++; return; } /* * Respond only if authentication succeeds. Don't do a * crypto-NAK, as that would not be useful. */ if (AUTH(restrict_mask & RES_DONTTRUST, is_authentic)) { record_raw_stats(&rbufp->recv_srcadr, &rbufp->dstadr->sin, &p_org, &p_rec, &p_xmt, &rbufp->recv_time, PKT_LEAP(pkt->li_vn_mode), PKT_VERSION(pkt->li_vn_mode), PKT_MODE(pkt->li_vn_mode), PKT_TO_STRATUM(pkt->stratum), pkt->ppoll, pkt->precision, FPTOD(NTOHS_FP(pkt->rootdelay)), FPTOD(NTOHS_FP(pkt->rootdisp)), pkt->refid, rbufp->recv_length - MIN_V4_PKT_LEN, (u_char *)&pkt->exten); /* Bug 3596: Do we want to fuzz the reftime? */ fast_xmit(rbufp, MODE_SERVER, skeyid, restrict_mask); } return; /* hooray */ /* * This is a server mode packet returned in response to a client * mode packet sent to a multicast group address (for * manycastclient) or to a unicast address (for pool). The * origin timestamp is a good nonce to reliably associate the * reply with what was sent. If there is no match, that's * curious and could be an intruder attempting to clog, so we * just ignore it. * * If the packet is authentic and the manycastclient or pool * association is found, we mobilize a client association and * copy pertinent variables from the manycastclient or pool * association to the new client association. If not, just * ignore the packet. * * There is an implosion hazard at the manycast client, since * the manycast servers send the server packet immediately. If * the guy is already here, don't fire up a duplicate. * * There are cases here where we do not call record_raw_stats(). */ case AM_MANYCAST: #ifdef AUTOKEY /* * Do not respond if not the same group. */ if (group_test(groupname, NULL)) { DPRINTF(2, ("receive: AM_MANYCAST drop: empty groupname\n")); sys_declined++; return; } #endif /* AUTOKEY */ /* Do not spin up duplicate manycast associations */ if (INT_LL_OF_GLOB & rbufp->dstadr->flags) { DPRINTF(2, ("receive: AM_MANYCAST drop: link-local server\n")); sys_declined++; return; } if ((peer2 = findmanycastpeer(rbufp)) == NULL) { DPRINTF(2, ("receive: AM_MANYCAST drop: No manycast peer\n")); sys_restricted++; return; /* not enabled */ } if (!AUTH( (!(peer2->cast_flags & MDF_POOL) && sys_authenticate) || (restrict_mask & (RES_NOPEER | RES_DONTTRUST)), is_authentic) /* MC: RES_NOEPEER? */ ) { DPRINTF(2, ("receive: AM_MANYCAST drop: bad auth || (NOPEER|DONTTRUST)\n")); sys_restricted++; return; /* access denied */ } /* * Do not respond if unsynchronized or stratum is below * the floor or at or above the ceiling. */ if ( hisleap == LEAP_NOTINSYNC || hisstratum < sys_floor || hisstratum >= sys_ceiling) { DPRINTF(2, ("receive: AM_MANYCAST drop: unsync/stratum\n")); sys_declined++; return; /* no help */ } cast_flags = MDF_UCAST; if (MDF_POOL & peer2->cast_flags) { cast_flags |= MDF_PCLNT; } peer = newpeer(&rbufp->recv_srcadr, NULL, rbufp->dstadr, r4a.ippeerlimit, MODE_CLIENT, hisversion, peer2->minpoll, peer2->maxpoll, (FLAG_PREEMPT | (POOL_FLAG_PMASK & peer2->flags)), cast_flags, 0, skeyid, sys_ident); if (NULL == peer) { DPRINTF(2, ("receive: AM_MANYCAST drop: duplicate\n")); sys_declined++; return; /* ignore duplicate */ } /* * After each ephemeral pool association is spun, * accelerate the next poll for the pool solicitor so * the pool will fill promptly. */ if (peer2->cast_flags & MDF_POOL) peer2->nextdate = current_time + 1; /* * Further processing of the solicitation response would * simply detect its origin timestamp as bogus for the * brand-new association (it matches the prototype * association) and tinker with peer->nextdate delaying * first sync. */ return; /* solicitation response handled */ /* * This is the first packet received from a broadcast server. If * the packet is authentic and we are enabled as broadcast * client, mobilize a broadcast client association. We don't * kiss any frogs here. * * There are cases here where we do not call record_raw_stats(). */ case AM_NEWBCL: #ifdef AUTOKEY /* * Do not respond if not the same group. */ if (group_test(groupname, sys_ident)) { DPRINTF(2, ("receive: AM_NEWBCL drop: groupname mismatch\n")); sys_declined++; return; } #endif /* AUTOKEY */ if (!sys_bclient && !sys_mclient) { DPRINTF(2, ("receive: AM_NEWBCL drop: not a bclient/mclient\n")); sys_restricted++; return; /* not enabled */ } if (!AUTH(sys_authenticate | (restrict_mask & (RES_NOPEER | RES_DONTTRUST)), is_authentic) /* NEWBCL: RES_NOEPEER? */ ) { DPRINTF(2, ("receive: AM_NEWBCL drop: AUTH failed\n")); sys_restricted++; return; /* access denied */ } /* * Do not respond if unsynchronized or stratum is below * the floor or at or above the ceiling. */ if ( hisleap == LEAP_NOTINSYNC || hisstratum < sys_floor || hisstratum >= sys_ceiling) { DPRINTF(2, ("receive: AM_NEWBCL drop: Unsync or bad stratum\n")); sys_declined++; return; /* no help */ } #ifdef AUTOKEY /* * Do not respond if Autokey and the opcode is not a * CRYPTO_ASSOC response with association ID. */ if ( crypto_flags && skeyid > NTP_MAXKEY && (opcode & 0xffff0000) != (CRYPTO_ASSOC | CRYPTO_RESP)) { DPRINTF(2, ("receive: AM_NEWBCL drop: Autokey but not CRYPTO_ASSOC\n")); sys_declined++; return; /* protocol error */ } #endif /* AUTOKEY */ /* * Broadcasts received via a multicast address may * arrive after a unicast volley has begun * with the same remote address. newpeer() will not * find duplicate associations on other local endpoints * if a non-NULL endpoint is supplied. multicastclient * ephemeral associations are unique across all local * endpoints. */ if (!(INT_MCASTOPEN & rbufp->dstadr->flags)) match_ep = rbufp->dstadr; else match_ep = NULL; /* * Determine whether to execute the initial volley. */ if (sys_bdelay > 0.0) { #ifdef AUTOKEY /* * If a two-way exchange is not possible, * neither is Autokey. */ if (crypto_flags && skeyid > NTP_MAXKEY) { sys_restricted++; DPRINTF(2, ("receive: AM_NEWBCL drop: Autokey but not 2-way\n")); return; /* no autokey */ } #endif /* AUTOKEY */ /* * Do not execute the volley. Start out in * broadcast client mode. */ peer = newpeer(&rbufp->recv_srcadr, NULL, match_ep, r4a.ippeerlimit, MODE_BCLIENT, hisversion, pkt->ppoll, pkt->ppoll, FLAG_PREEMPT, MDF_BCLNT, 0, skeyid, sys_ident); if (NULL == peer) { DPRINTF(2, ("receive: AM_NEWBCL drop: duplicate\n")); sys_restricted++; return; /* ignore duplicate */ } else { peer->delay = sys_bdelay; peer->bxmt = p_xmt; } break; } /* * Execute the initial volley in order to calibrate the * propagation delay and run the Autokey protocol. * * Note that the minpoll is taken from the broadcast * packet, normally 6 (64 s) and that the poll interval * is fixed at this value. */ peer = newpeer(&rbufp->recv_srcadr, NULL, match_ep, r4a.ippeerlimit, MODE_CLIENT, hisversion, pkt->ppoll, pkt->ppoll, FLAG_BC_VOL | FLAG_IBURST | FLAG_PREEMPT, MDF_BCLNT, 0, skeyid, sys_ident); if (NULL == peer) { DPRINTF(2, ("receive: AM_NEWBCL drop: empty newpeer() failed\n")); sys_restricted++; return; /* ignore duplicate */ } peer->bxmt = p_xmt; #ifdef AUTOKEY if (skeyid > NTP_MAXKEY) crypto_recv(peer, rbufp); #endif /* AUTOKEY */ return; /* hooray */ /* * This is the first packet received from a potential ephemeral * symmetric active peer. First, deal with broken Windows clients. * Then, if NOEPEER is enabled, drop it. If the packet meets our * authenticty requirements and is the first he sent, mobilize * a passive association. * Otherwise, kiss the frog. * * There are cases here where we do not call record_raw_stats(). */ case AM_NEWPASS: DEBUG_REQUIRE(MODE_ACTIVE == hismode); #ifdef AUTOKEY /* * Do not respond if not the same group. */ if (group_test(groupname, sys_ident)) { DPRINTF(2, ("receive: AM_NEWPASS drop: Autokey group mismatch\n")); sys_declined++; return; } #endif /* AUTOKEY */ if (!AUTH(sys_authenticate | (restrict_mask & (RES_NOPEER | RES_DONTTRUST)), is_authentic) ) { /* * If authenticated but cannot mobilize an * association, send a symmetric passive * response without mobilizing an association. * This is for drat broken Windows clients. See * Microsoft KB 875424 for preferred workaround. */ if (AUTH(restrict_mask & RES_DONTTRUST, is_authentic)) { fast_xmit(rbufp, MODE_PASSIVE, skeyid, restrict_mask); return; /* hooray */ } /* HMS: Why is this next set of lines a feature? */ if (is_authentic == AUTH_ERROR) { fast_xmit(rbufp, MODE_PASSIVE, 0, restrict_mask); sys_restricted++; return; } if (restrict_mask & RES_NOEPEER) { DPRINTF(2, ("receive: AM_NEWPASS drop: NOEPEER\n")); sys_declined++; return; } /* [Bug 2941] * If we got here, the packet isn't part of an * existing association, either isn't correctly * authenticated or it is but we are refusing * ephemeral peer requests, and it didn't meet * either of the previous two special cases so we * should just drop it on the floor. For example, * crypto-NAKs (is_authentic == AUTH_CRYPTO) * will make it this far. This is just * debug-printed and not logged to avoid log * flooding. */ DPRINTF(2, ("receive: at %ld refusing to mobilize passive association" " with unknown peer %s mode %d/%s:%s keyid %08x len %d auth %d\n", current_time, stoa(&rbufp->recv_srcadr), hismode, hm_str, am_str, skeyid, (authlen + has_mac), is_authentic)); sys_declined++; return; } if (restrict_mask & RES_NOEPEER) { DPRINTF(2, ("receive: AM_NEWPASS drop: NOEPEER\n")); sys_declined++; return; } /* * Do not respond if synchronized and if stratum is * below the floor or at or above the ceiling. Note, * this allows an unsynchronized peer to synchronize to * us. It would be very strange if he did and then was * nipped, but that could only happen if we were * operating at the top end of the range. It also means * we will spin an ephemeral association in response to * MODE_ACTIVE KoDs, which will time out eventually. */ if ( hisleap != LEAP_NOTINSYNC && (hisstratum < sys_floor || hisstratum >= sys_ceiling)) { DPRINTF(2, ("receive: AM_NEWPASS drop: Remote stratum (%d) out of range\n", hisstratum)); sys_declined++; return; /* no help */ } /* * The message is correctly authenticated and allowed. * Mobilize a symmetric passive association, if we won't * exceed the ippeerlimit. */ if ((peer = newpeer(&rbufp->recv_srcadr, NULL, rbufp->dstadr, r4a.ippeerlimit, MODE_PASSIVE, hisversion, pkt->ppoll, NTP_MAXDPOLL, 0, MDF_UCAST, 0, skeyid, sys_ident)) == NULL) { DPRINTF(2, ("receive: AM_NEWPASS drop: newpeer() failed\n")); sys_declined++; return; /* ignore duplicate */ } break; /* * Process regular packet. Nothing special. * * There are cases here where we do not call record_raw_stats(). */ case AM_PROCPKT: #ifdef AUTOKEY /* * Do not respond if not the same group. */ if (group_test(groupname, peer->ident)) { DPRINTF(2, ("receive: AM_PROCPKT drop: Autokey group mismatch\n")); sys_declined++; return; } #endif /* AUTOKEY */ if (MODE_BROADCAST == hismode) { int bail = 0; l_fp tdiff; u_long deadband; DPRINTF(2, ("receive: PROCPKT/BROADCAST: prev pkt %ld seconds ago, ppoll: %d, %d secs\n", (current_time - peer->timelastrec), peer->ppoll, (1 << peer->ppoll) )); /* Things we can check: * * Did the poll interval change? * Is the poll interval in the packet in-range? * Did this packet arrive too soon? * Is the timestamp in this packet monotonic * with respect to the previous packet? */ /* This is noteworthy, not error-worthy */ if (pkt->ppoll != peer->ppoll) { msyslog(LOG_INFO, "receive: broadcast poll from %s changed from %u to %u", stoa(&rbufp->recv_srcadr), peer->ppoll, pkt->ppoll); } /* This is error-worthy */ if ( pkt->ppoll < peer->minpoll || pkt->ppoll > peer->maxpoll) { msyslog(LOG_INFO, "receive: broadcast poll of %u from %s is out-of-range (%d to %d)!", pkt->ppoll, stoa(&rbufp->recv_srcadr), peer->minpoll, peer->maxpoll); ++bail; } /* too early? worth an error, too! * * [Bug 3113] Ensure that at least one poll * interval has elapsed since the last **clean** * packet was received. We limit the check to * **clean** packets to prevent replayed packets * and incorrectly authenticated packets, which * we'll discard, from being used to create a * denial of service condition. */ deadband = (1u << pkt->ppoll); if (FLAG_BC_VOL & peer->flags) deadband -= 3; /* allow greater fuzz after volley */ if ((current_time - peer->timereceived) < deadband) { msyslog(LOG_INFO, "receive: broadcast packet from %s arrived after %lu, not %lu seconds!", stoa(&rbufp->recv_srcadr), (current_time - peer->timereceived), deadband); ++bail; } /* Alert if time from the server is non-monotonic. * * [Bug 3114] is about Broadcast mode replay DoS. * * Broadcast mode *assumes* a trusted network. * Even so, it's nice to be robust in the face * of attacks. * * If we get an authenticated broadcast packet * with an "earlier" timestamp, it means one of * two things: * * - the broadcast server had a backward step. * * - somebody is trying a replay attack. * * deadband: By default, we assume the broadcast * network is trustable, so we take our accepted * broadcast packets as we receive them. But * some folks might want to take additional poll * delays before believing a backward step. */ if (sys_bcpollbstep) { /* pkt->ppoll or peer->ppoll ? */ deadband = (1u << pkt->ppoll) * sys_bcpollbstep + 2; } else { deadband = 0; } if (L_ISZERO(&peer->bxmt)) { tdiff.l_ui = tdiff.l_uf = 0; } else { tdiff = p_xmt; L_SUB(&tdiff, &peer->bxmt); } if ( tdiff.l_i < 0 && (current_time - peer->timereceived) < deadband) { msyslog(LOG_INFO, "receive: broadcast packet from %s contains non-monotonic timestamp: 0x%x.%08x -> 0x%x.%08x", stoa(&rbufp->recv_srcadr), peer->bxmt.l_ui, peer->bxmt.l_uf, p_xmt.l_ui, p_xmt.l_uf ); ++bail; } if (bail) { DPRINTF(2, ("receive: AM_PROCPKT drop: bail\n")); peer->timelastrec = current_time; sys_declined++; return; } } break; /* * A passive packet matches a passive association. This is * usually the result of reconfiguring a client on the fly. As * this association might be legitimate and this packet an * attempt to deny service, just ignore it. */ case AM_ERR: DPRINTF(2, ("receive: AM_ERR drop.\n")); sys_declined++; return; /* * For everything else there is the bit bucket. */ default: DPRINTF(2, ("receive: default drop.\n")); sys_declined++; return; } #ifdef AUTOKEY /* * If the association is configured for Autokey, the packet must * have a public key ID; if not, the packet must have a * symmetric key ID. */ if ( is_authentic != AUTH_CRYPTO && ( ((peer->flags & FLAG_SKEY) && skeyid <= NTP_MAXKEY) || (!(peer->flags & FLAG_SKEY) && skeyid > NTP_MAXKEY))) { DPRINTF(2, ("receive: drop: Autokey but wrong/bad auth\n")); sys_badauth++; return; } #endif /* AUTOKEY */ peer->received++; peer->flash &= ~PKT_TEST_MASK; if (peer->flags & FLAG_XBOGUS) { peer->flags &= ~FLAG_XBOGUS; peer->flash |= TEST3; } /* * Next comes a rigorous schedule of timestamp checking. If the * transmit timestamp is zero, the server has not initialized in * interleaved modes or is horribly broken. * * A KoD packet we pay attention to cannot have a 0 transmit * timestamp. */ kissCode = kiss_code_check(hisleap, hisstratum, hismode, pkt->refid); if (L_ISZERO(&p_xmt)) { peer->flash |= TEST3; /* unsynch */ if (kissCode != NOKISS) { /* KoD packet */ peer->bogusorg++; /* for TEST2 or TEST3 */ msyslog(LOG_INFO, "receive: Unexpected zero transmit timestamp in KoD from %s", ntoa(&peer->srcadr)); return; } /* * If the transmit timestamp duplicates our previous one, the * packet is a replay. This prevents the bad guys from replaying * the most recent packet, authenticated or not. */ } else if ( ((FLAG_LOOPNONCE & peer->flags) && L_ISEQU(&peer->nonce, &p_xmt)) || (!(FLAG_LOOPNONCE & peer->flags) && L_ISEQU(&peer->xmt, &p_xmt)) ) { DPRINTF(2, ("receive: drop: Duplicate xmit\n")); peer->flash |= TEST1; /* duplicate */ peer->oldpkt++; return; /* * If this is a broadcast mode packet, make sure hisstratum * is appropriate. Don't do anything else here - we wait to * see if this is an interleave broadcast packet until after * we've validated the MAC that SHOULD be provided. * * hisstratum cannot be 0 - see assertion above. * If hisstratum is 15, then we'll advertise as UNSPEC but * at least we'll be able to sync with the broadcast server. */ } else if (hismode == MODE_BROADCAST) { /* 0 is unexpected too, and impossible */ if (STRATUM_UNSPEC <= hisstratum) { /* Is this a ++sys_declined or ??? */ msyslog(LOG_INFO, "receive: Unexpected stratum (%d) in broadcast from %s", hisstratum, ntoa(&peer->srcadr)); return; } /* * Basic KoD validation checking: * * KoD packets are a mixed-blessing. Forged KoD packets * are DoS attacks. There are rare situations where we might * get a valid KoD response, though. Since KoD packets are * a special case that complicate the checks we do next, we * handle the basic KoD checks here. * * Note that we expect the incoming KoD packet to have its * (nonzero) org, rec, and xmt timestamps set to the xmt timestamp * that we have previously sent out. Watch interleave mode. */ } else if (kissCode != NOKISS) { DEBUG_INSIST(!L_ISZERO(&p_xmt)); if ( L_ISZERO(&p_org) /* We checked p_xmt above */ || L_ISZERO(&p_rec)) { peer->bogusorg++; msyslog(LOG_INFO, "receive: KoD packet from %s has a zero org or rec timestamp. Ignoring.", ntoa(&peer->srcadr)); return; } if ( !L_ISEQU(&p_xmt, &p_org) || !L_ISEQU(&p_xmt, &p_rec)) { peer->bogusorg++; msyslog(LOG_INFO, "receive: KoD packet from %s has inconsistent xmt/org/rec timestamps. Ignoring.", ntoa(&peer->srcadr)); return; } /* Be conservative */ if (peer->flip == 0 && !L_ISEQU(&p_org, &peer->aorg)) { peer->bogusorg++; msyslog(LOG_INFO, "receive: flip 0 KoD origin timestamp 0x%x.%08x from %s does not match 0x%x.%08x - ignoring.", p_org.l_ui, p_org.l_uf, ntoa(&peer->srcadr), peer->aorg.l_ui, peer->aorg.l_uf); return; } else if (peer->flip == 1 && !L_ISEQU(&p_org, &peer->borg)) { peer->bogusorg++; msyslog(LOG_INFO, "receive: flip 1 KoD origin timestamp 0x%x.%08x from %s does not match interleave 0x%x.%08x - ignoring.", p_org.l_ui, p_org.l_uf, ntoa(&peer->srcadr), peer->borg.l_ui, peer->borg.l_uf); return; } /* * Basic mode checks: * * If there is no origin timestamp, it's either an initial * packet or we've already received a response to our query. * Of course, should 'aorg' be all-zero because this really * was the original transmit timestamp, we'll ignore this * reply. There is a window of one nanosecond once every * 136 years' time where this is possible. We currently * ignore this situation, as a completely zero timestamp * is (quietly?) disallowed. * * Otherwise, check for bogus packet in basic mode. * If it is bogus, switch to interleaved mode and * resynchronize, but only after confirming the packet is * not bogus in symmetric interleaved mode. * * This could also mean somebody is forging packets claiming * to be from us, attempting to cause our server to KoD us. * * We have earlier asserted that hisstratum cannot be 0. * If hisstratum is STRATUM_UNSPEC, it means he's not sync'd. */ /* XXX: FLAG_LOOPNONCE */ DEBUG_INSIST(0 == (FLAG_LOOPNONCE & peer->flags)); if (RATEKISS == kissCode) { msyslog(LOG_INFO, "RATE KoD from %s poll %u", ntoa(&peer->srcadr), 1u << pkt->ppoll); } else { msyslog(LOG_INFO, "KoD %s from %s", refid_str(pkt->refid, -1), ntoa(&peer->srcadr)); } } else if (peer->flip == 0) { if (0) { } else if (L_ISZERO(&p_org)) { const char *action; #ifdef BUG3361 msyslog(LOG_INFO, "receive: BUG 3361: Clearing peer->aorg "); L_CLR(&peer->aorg); /* Clear peer->nonce, too? */ #endif /**/ switch (hismode) { /* We allow 0org for: */ case UCHAR_MAX: action = "Allow"; break; /* We disallow 0org for: */ case MODE_UNSPEC: case MODE_ACTIVE: case MODE_PASSIVE: case MODE_CLIENT: case MODE_SERVER: case MODE_BROADCAST: action = "Drop"; peer->bogusorg++; peer->flash |= TEST2; /* bogus */ break; default: action = ""; /* for cranky compilers / MSVC */ INSIST(!"receive(): impossible hismode"); break; } /**/ msyslog(LOG_INFO, "receive: %s 0 origin timestamp from %s@%s xmt 0x%x.%08x", action, hm_str, ntoa(&peer->srcadr), ntohl(pkt->xmt.l_ui), ntohl(pkt->xmt.l_uf)); } else if ( L_ISZERO(&peer->aorg) && MODE_CLIENT != hismode && !memcmp("STEP", &peer->refid, 4)) { /* response came in just after we stepped clock, normal */ } else if (!L_ISEQU(&p_org, &peer->aorg)) { /* are there cases here where we should bail? */ /* Should we set TEST2 if we decide to try xleave? */ peer->bogusorg++; peer->flash |= TEST2; /* bogus */ msyslog(LOG_INFO, "duplicate or replay: org 0x%x.%08x does not match 0x%x.%08x from %s@%s", ntohl(pkt->org.l_ui), ntohl(pkt->org.l_uf), peer->aorg.l_ui, peer->aorg.l_uf, hm_str, ntoa(&peer->srcadr)); if ( !L_ISZERO(&peer->dst) && L_ISEQU(&p_org, &peer->dst)) { /* Might be the start of an interleave */ if (dynamic_interleave) { peer->flip = 1; report_event(PEVNT_XLEAVE, peer, NULL); } else { msyslog(LOG_INFO, "receive: Dynamic interleave from %s@%s denied", hm_str, ntoa(&peer->srcadr)); } } } else { L_CLR(&peer->aorg); /* XXX: FLAG_LOOPNONCE */ } /* * Check for valid nonzero timestamp fields. */ } else if ( L_ISZERO(&p_org) || L_ISZERO(&p_rec) || L_ISZERO(&peer->dst)) { peer->flash |= TEST3; /* unsynch */ /* * Check for bogus packet in interleaved symmetric mode. This * can happen if a packet is lost, duplicated or crossed. If * found, flip and resynchronize. */ } else if ( !L_ISZERO(&peer->dst) && !L_ISEQU(&p_org, &peer->dst)) { DPRINTF(2, ("receive: drop: Bogus packet in interleaved symmetric mode\n")); peer->bogusorg++; peer->flags |= FLAG_XBOGUS; peer->flash |= TEST2; /* bogus */ #ifdef BUG3453 return; /* Bogus packet, we are done */ #endif } /**/ /* * If this is a crypto_NAK, the server cannot authenticate a * client packet. The server might have just changed keys. Clear * the association and restart the protocol. */ if (crypto_nak_test == VALIDNAK) { report_event(PEVNT_AUTH, peer, "crypto_NAK"); peer->flash |= TEST5; /* bad auth */ peer->badauth++; if (peer->flags & FLAG_PREEMPT) { if (unpeer_crypto_nak_early) { unpeer(peer); } DPRINTF(2, ("receive: drop: PREEMPT crypto_NAK\n")); return; } #ifdef AUTOKEY if (peer->crypto) { peer_clear(peer, "AUTH"); } #endif /* AUTOKEY */ DPRINTF(2, ("receive: drop: crypto_NAK\n")); return; /* * If the digest fails or it's missing for authenticated * associations, the client cannot authenticate a server * reply to a client packet previously sent. The loopback check * is designed to avoid a bait-and-switch attack, which was * possible in past versions. If symmetric modes, return a * crypto-NAK. The peer should restart the protocol. */ } else if (!AUTH(peer->keyid || has_mac || (restrict_mask & RES_DONTTRUST), is_authentic)) { if (peer->flash & PKT_TEST_MASK) { msyslog(LOG_INFO, "receive: Bad auth in packet with bad timestamps from %s denied - spoof?", ntoa(&peer->srcadr)); return; } report_event(PEVNT_AUTH, peer, "digest"); peer->flash |= TEST5; /* bad auth */ peer->badauth++; if ( has_mac && ( hismode == MODE_ACTIVE || hismode == MODE_PASSIVE)) fast_xmit(rbufp, MODE_ACTIVE, 0, restrict_mask); if (peer->flags & FLAG_PREEMPT) { if (unpeer_digest_early) { unpeer(peer); } } #ifdef AUTOKEY else if (peer_clear_digest_early && peer->crypto) { peer_clear(peer, "AUTH"); } #endif /* AUTOKEY */ DPRINTF(2, ("receive: drop: Bad or missing AUTH\n")); return; } /* * For broadcast packets: * * HMS: This next line never made much sense to me, even * when it was up higher: * If an initial volley, bail out now and let the * client do its stuff. * * If the packet has not failed authentication, then * - if the origin timestamp is nonzero this is an * interleaved broadcast, so restart the protocol. * - else, this is not an interleaved broadcast packet. */ if (hismode == MODE_BROADCAST) { if ( is_authentic == AUTH_OK || is_authentic == AUTH_NONE) { if (!L_ISZERO(&p_org)) { if (!(peer->flags & FLAG_XB)) { msyslog(LOG_INFO, "receive: Broadcast server at %s is in interleave mode", ntoa(&peer->srcadr)); peer->flags |= FLAG_XB; peer->aorg = p_xmt; peer->borg = rbufp->recv_time; report_event(PEVNT_XLEAVE, peer, NULL); return; } } else if (peer->flags & FLAG_XB) { msyslog(LOG_INFO, "receive: Broadcast server at %s is no longer in interleave mode", ntoa(&peer->srcadr)); peer->flags &= ~FLAG_XB; } } else { msyslog(LOG_INFO, "receive: Bad broadcast auth (%d) from %s", is_authentic, ntoa(&peer->srcadr)); } /* * Now that we know the packet is correctly authenticated, * update peer->bxmt. */ peer->bxmt = p_xmt; } /* ** Update the state variables. */ if (peer->flip == 0) { if (hismode != MODE_BROADCAST) peer->rec = p_xmt; peer->dst = rbufp->recv_time; } peer->xmt = p_xmt; /* * Set the peer ppoll to the maximum of the packet ppoll and the * peer minpoll. If a kiss-o'-death, set the peer minpoll to * this maximum and advance the headway to give the sender some * headroom. Very intricate. */ /* * Check for any kiss codes. Note this is only used when a server * responds to a packet request. */ /* * Check to see if this is a RATE Kiss Code * Currently this kiss code will accept whatever valid poll * rate that the server sends */ if ( (NTP_MINPOLL > pkt->ppoll) || (NTP_MAXPOLL < pkt->ppoll) ) { DPRINTF(2, ("RATEKISS: Invalid ppoll (%d) from %s\n", pkt->ppoll, stoa(&rbufp->recv_srcadr))); sys_badlength++; return; /* invalid packet poll */ } peer->ppoll = max(peer->minpoll, pkt->ppoll); if (kissCode == RATEKISS) { peer->selbroken++; /* Increment the KoD count */ report_event(PEVNT_RATE, peer, NULL); if (pkt->ppoll > peer->minpoll) peer->minpoll = peer->ppoll; peer->burst = peer->retry = 0; peer->throttle = (NTP_SHIFT + 1) * (1 << peer->minpoll); poll_update(peer, pkt->ppoll, 0); return; /* kiss-o'-death */ } if (kissCode != NOKISS) { peer->selbroken++; /* Increment the KoD count */ return; /* Drop any other kiss code packets */ } /* * XXX */ /* * If: * - this is a *cast (uni-, broad-, or m-) server packet * - and it's symmetric-key authenticated * then see if the sender's IP is trusted for this keyid. * If it is, great - nothing special to do here. * Otherwise, we should report and bail. * * Autokey-authenticated packets are accepted. */ switch (hismode) { case MODE_SERVER: /* server mode */ case MODE_BROADCAST: /* broadcast mode */ case MODE_ACTIVE: /* symmetric active mode */ case MODE_PASSIVE: /* symmetric passive mode */ if ( is_authentic == AUTH_OK && skeyid && skeyid <= NTP_MAXKEY && !authistrustedip(skeyid, &peer->srcadr)) { report_event(PEVNT_AUTH, peer, "authIP"); peer->badauth++; return; } break; case MODE_CLIENT: /* client mode */ #if 0 /* At this point, MODE_CONTROL is overloaded by MODE_BCLIENT */ case MODE_CONTROL: /* control mode */ #endif case MODE_PRIVATE: /* private mode */ case MODE_BCLIENT: /* broadcast client mode */ break; case MODE_UNSPEC: /* unspecified (old version) */ default: msyslog(LOG_INFO, "receive: Unexpected mode (%d) in packet from %s", hismode, ntoa(&peer->srcadr)); break; } /* * That was hard and I am sweaty, but the packet is squeaky * clean. Get on with real work. */ peer->timereceived = current_time; peer->timelastrec = current_time; if (is_authentic == AUTH_OK) peer->flags |= FLAG_AUTHENTIC; else peer->flags &= ~FLAG_AUTHENTIC; #ifdef AUTOKEY /* * More autokey dance. The rules of the cha-cha are as follows: * * 1. If there is no key or the key is not auto, do nothing. * * 2. If this packet is in response to the one just previously * sent or from a broadcast server, do the extension fields. * Otherwise, assume bogosity and bail out. * * 3. If an extension field contains a verified signature, it is * self-authenticated and we sit the dance. * * 4. If this is a server reply, check only to see that the * transmitted key ID matches the received key ID. * * 5. Check to see that one or more hashes of the current key ID * matches the previous key ID or ultimate original key ID * obtained from the broadcaster or symmetric peer. If no * match, sit the dance and call for new autokey values. * * In case of crypto error, fire the orchestra, stop dancing and * restart the protocol. */ if (peer->flags & FLAG_SKEY) { /* * Decrement remaining autokey hashes. This isn't * perfect if a packet is lost, but results in no harm. */ ap = (struct autokey *)peer->recval.ptr; if (ap != NULL) { if (ap->seq > 0) ap->seq--; } peer->flash |= TEST8; rval = crypto_recv(peer, rbufp); if (rval == XEVNT_OK) { peer->unreach = 0; } else { if (rval == XEVNT_ERR) { report_event(PEVNT_RESTART, peer, "crypto error"); peer_clear(peer, "CRYP"); peer->flash |= TEST9; /* bad crypt */ if (peer->flags & FLAG_PREEMPT) { if (unpeer_crypto_early) { unpeer(peer); } } } return; } /* * If server mode, verify the receive key ID matches * the transmit key ID. */ if (hismode == MODE_SERVER) { if (skeyid == peer->keyid) peer->flash &= ~TEST8; /* * If an extension field is present, verify only that it * has been correctly signed. We don't need a sequence * check here, but the sequence continues. */ } else if (!(peer->flash & TEST8)) { peer->pkeyid = skeyid; /* * Now the fun part. Here, skeyid is the current ID in * the packet, pkeyid is the ID in the last packet and * tkeyid is the hash of skeyid. If the autokey values * have not been received, this is an automatic error. * If so, check that the tkeyid matches pkeyid. If not, * hash tkeyid and try again. If the number of hashes * exceeds the number remaining in the sequence, declare * a successful failure and refresh the autokey values. */ } else if (ap != NULL) { int i; for (i = 0; ; i++) { if ( tkeyid == peer->pkeyid || tkeyid == ap->key) { peer->flash &= ~TEST8; peer->pkeyid = skeyid; ap->seq -= i; break; } if (i > ap->seq) { peer->crypto &= ~CRYPTO_FLAG_AUTO; break; } tkeyid = session_key( &rbufp->recv_srcadr, dstadr_sin, tkeyid, pkeyid, 0); } if (peer->flash & TEST8) report_event(PEVNT_AUTH, peer, "keylist"); } if (!(peer->crypto & CRYPTO_FLAG_PROV)) /* test 9 */ peer->flash |= TEST8; /* bad autokey */ /* * The maximum lifetime of the protocol is about one * week before restarting the Autokey protocol to * refresh certificates and leapseconds values. */ if (current_time > peer->refresh) { report_event(PEVNT_RESTART, peer, "crypto refresh"); peer_clear(peer, "TIME"); return; } } #endif /* AUTOKEY */ /* * The dance is complete and the flash bits have been lit. Toss * the packet over the fence for processing, which may light up * more flashers. Leave if the packet is not good. */ process_packet(peer, pkt, rbufp->recv_length); /* Bug 2734: TEST3 prevents initial interleave sync */ if ((~TEST3 & peer->flash) & PKT_TEST_MASK) { return; } /* [bug 3592] Update poll. Ideally this should not happen in a * receive branch, but too much is going on here... at least we * do it only if the packet was good! */ poll_update(peer, peer->hpoll, (peer->hmode == MODE_CLIENT)); /* * In interleaved mode update the state variables. Also adjust the * transmit phase to avoid crossover. */ if (peer->flip != 0) { peer->rec = p_rec; peer->dst = rbufp->recv_time; if (peer->nextdate - current_time < (1U << min(peer->ppoll, peer->hpoll)) / 2) peer->nextdate++; else peer->nextdate--; } } /* * process_packet - Packet Procedure, a la Section 3.4.4 of RFC-1305 * Or almost, at least. If we're in here we have a reasonable * expectation that we will be having a long term * relationship with this host. */ void process_packet( register struct peer *peer, register struct pkt *pkt, u_int len ) { double t34, t21; double p_offset, p_del, p_disp; l_fp p_rec, p_xmt, p_org, p_reftime, ci; u_char pmode, pleap, pversion, pstratum; #ifdef ASSYM int itemp; double etemp, ftemp, td; #endif /* ASSYM */ p_del = FPTOD(NTOHS_FP(pkt->rootdelay)); p_offset = 0; p_disp = FPTOD(NTOHS_FP(pkt->rootdisp)); NTOHL_FP(&pkt->reftime, &p_reftime); NTOHL_FP(&pkt->org, &p_org); NTOHL_FP(&pkt->rec, &p_rec); NTOHL_FP(&pkt->xmt, &p_xmt); pmode = PKT_MODE(pkt->li_vn_mode); pleap = PKT_LEAP(pkt->li_vn_mode); pversion = PKT_VERSION(pkt->li_vn_mode); pstratum = PKT_TO_STRATUM(pkt->stratum); /* * Verify the server is synchronized; that is, the leap bits, * stratum and root distance are valid. */ if ( pleap == LEAP_NOTINSYNC /* test 6 */ || pstratum < sys_floor || pstratum >= sys_ceiling) peer->flash |= TEST6; /* bad synch or strat */ if (p_del / 2 + p_disp >= MAXDISPERSE) /* test 7 */ peer->flash |= TEST7; /* bad header */ /* * If any tests fail at this point, the packet is discarded. * Note that some flashers may have already been set in the * receive() routine. */ if (peer->flash & PKT_TEST_MASK) { peer->seldisptoolarge++; DPRINTF(1, ("packet: flash header %04x\n", peer->flash)); /* [Bug 3592] do *not* update poll on bad packets! */ return; } /* * update stats, now that we really handle this packet: */ sys_processed++; peer->processed++; /* * Capture the header values in the client/peer association.. */ record_raw_stats(&peer->srcadr, peer->dstadr ? &peer->dstadr->sin : NULL, &p_org, &p_rec, &p_xmt, &peer->dst, pleap, pversion, pmode, pstratum, pkt->ppoll, pkt->precision, p_del, p_disp, pkt->refid, len - MIN_V4_PKT_LEN, (u_char *)&pkt->exten); peer->leap = pleap; peer->stratum = min(pstratum, STRATUM_UNSPEC); peer->pmode = pmode; peer->precision = pkt->precision; peer->rootdelay = p_del; peer->rootdisp = p_disp; peer->refid = pkt->refid; /* network byte order */ peer->reftime = p_reftime; /* * First, if either burst mode is armed, enable the burst. * Compute the headway for the next packet and delay if * necessary to avoid exceeding the threshold. */ if (peer->retry > 0) { peer->retry = 0; if (peer->reach) peer->burst = min(1 << (peer->hpoll - peer->minpoll), NTP_SHIFT) - 1; else peer->burst = NTP_IBURST - 1; if (peer->burst > 0) peer->nextdate = current_time; } /* * If the peer was previously unreachable, raise a trap. In any * case, mark it reachable. */ if (!peer->reach) { report_event(PEVNT_REACH, peer, NULL); peer->timereachable = current_time; } peer->reach |= 1; /* * For a client/server association, calculate the clock offset, * roundtrip delay and dispersion. The equations are reordered * from the spec for more efficient use of temporaries. For a * broadcast association, offset the last measurement by the * computed delay during the client/server volley. Note the * computation of dispersion includes the system precision plus * that due to the frequency error since the origin time. * * It is very important to respect the hazards of overflow. The * only permitted operation on raw timestamps is subtraction, * where the result is a signed quantity spanning from 68 years * in the past to 68 years in the future. To avoid loss of * precision, these calculations are done using 64-bit integer * arithmetic. However, the offset and delay calculations are * sums and differences of these first-order differences, which * if done using 64-bit integer arithmetic, would be valid over * only half that span. Since the typical first-order * differences are usually very small, they are converted to 64- * bit doubles and all remaining calculations done in floating- * double arithmetic. This preserves the accuracy while * retaining the 68-year span. * * There are three interleaving schemes, basic, interleaved * symmetric and interleaved broadcast. The timestamps are * idioscyncratically different. See the onwire briefing/white * paper at www.eecis.udel.edu/~mills for details. * * Interleaved symmetric mode * t1 = peer->aorg/borg, t2 = peer->rec, t3 = p_xmt, * t4 = peer->dst */ if (peer->flip != 0) { ci = p_xmt; /* t3 - t4 */ L_SUB(&ci, &peer->dst); LFPTOD(&ci, t34); ci = p_rec; /* t2 - t1 */ if (peer->flip > 0) L_SUB(&ci, &peer->borg); else L_SUB(&ci, &peer->aorg); LFPTOD(&ci, t21); p_del = t21 - t34; p_offset = (t21 + t34) / 2.; if (p_del < 0 || p_del > 1.) { mprintf_event(PEVNT_XERR, peer, "t21 %.9f t34 %.9f", t21, t34); return; } /* * Broadcast modes */ } else if (peer->pmode == MODE_BROADCAST) { /* * Interleaved broadcast mode. Use interleaved timestamps. * t1 = peer->borg, t2 = p_org, t3 = p_org, t4 = aorg */ if (peer->flags & FLAG_XB) { ci = p_org; /* delay */ L_SUB(&ci, &peer->aorg); LFPTOD(&ci, t34); ci = p_org; /* t2 - t1 */ L_SUB(&ci, &peer->borg); LFPTOD(&ci, t21); peer->aorg = p_xmt; peer->borg = peer->dst; if (t34 < 0 || t34 > 1.) { /* drop all if in the initial volley */ if (FLAG_BC_VOL & peer->flags) goto bcc_init_volley_fail; mprintf_event(PEVNT_XERR, peer, "offset %.9f delay %.9f", t21, t34); return; } p_offset = t21; peer->xleave = t34; /* * Basic broadcast - use direct timestamps. * t3 = p_xmt, t4 = peer->dst */ } else { ci = p_xmt; /* t3 - t4 */ L_SUB(&ci, &peer->dst); LFPTOD(&ci, t34); p_offset = t34; } /* * When calibration is complete and the clock is * synchronized, the bias is calculated as the difference * between the unicast timestamp and the broadcast * timestamp. This works for both basic and interleaved * modes. * [Bug 3031] Don't keep this peer when the delay * calculation gives reason to suspect clock steps. * This is assumed for delays > 50ms. */ if (FLAG_BC_VOL & peer->flags) { peer->flags &= ~FLAG_BC_VOL; peer->delay = fabs(peer->offset - p_offset) * 2; DPRINTF(2, ("broadcast volley: initial delay=%.6f\n", peer->delay)); if (peer->delay > fabs(sys_bdelay)) { bcc_init_volley_fail: DPRINTF(2, ("%s", "broadcast volley: initial delay exceeds limit\n")); unpeer(peer); return; } } peer->nextdate = current_time + (1u << peer->ppoll) - 2u; p_del = peer->delay; p_offset += p_del / 2; /* * Basic mode, otherwise known as the old fashioned way. * * t1 = p_org, t2 = p_rec, t3 = p_xmt, t4 = peer->dst */ } else { ci = p_xmt; /* t3 - t4 */ L_SUB(&ci, &peer->dst); LFPTOD(&ci, t34); ci = p_rec; /* t2 - t1 */ L_SUB(&ci, &p_org); LFPTOD(&ci, t21); p_del = fabs(t21 - t34); p_offset = (t21 + t34) / 2.; } p_del = max(p_del, LOGTOD(sys_precision)); p_disp = LOGTOD(sys_precision) + LOGTOD(peer->precision) + clock_phi * p_del; #if ASSYM /* * This code calculates the outbound and inbound data rates by * measuring the differences between timestamps at different * packet lengths. This is helpful in cases of large asymmetric * delays commonly experienced on deep space communication * links. */ if (peer->t21_last > 0 && peer->t34_bytes > 0) { itemp = peer->t21_bytes - peer->t21_last; if (itemp > 25) { etemp = t21 - peer->t21; if (fabs(etemp) > 1e-6) { ftemp = itemp / etemp; if (ftemp > 1000.) peer->r21 = ftemp; } } itemp = len - peer->t34_bytes; if (itemp > 25) { etemp = -t34 - peer->t34; if (fabs(etemp) > 1e-6) { ftemp = itemp / etemp; if (ftemp > 1000.) peer->r34 = ftemp; } } } /* * The following section compensates for different data rates on * the outbound (d21) and inbound (t34) directions. To do this, * it finds t such that r21 * t - r34 * (d - t) = 0, where d is * the roundtrip delay. Then it calculates the correction as a * fraction of d. */ peer->t21 = t21; peer->t21_last = peer->t21_bytes; peer->t34 = -t34; peer->t34_bytes = len; DPRINTF(2, ("packet: t21 %.9lf %d t34 %.9lf %d\n", peer->t21, peer->t21_bytes, peer->t34, peer->t34_bytes)); if (peer->r21 > 0 && peer->r34 > 0 && p_del > 0) { if (peer->pmode != MODE_BROADCAST) td = (peer->r34 / (peer->r21 + peer->r34) - .5) * p_del; else td = 0; /* * Unfortunately, in many cases the errors are * unacceptable, so for the present the rates are not * used. In future, we might find conditions where the * calculations are useful, so this should be considered * a work in progress. */ t21 -= td; t34 -= td; DPRINTF(2, ("packet: del %.6lf r21 %.1lf r34 %.1lf %.6lf\n", p_del, peer->r21 / 1e3, peer->r34 / 1e3, td)); } #endif /* ASSYM */ /* * That was awesome. Now hand off to the clock filter. */ clock_filter(peer, p_offset + peer->bias, p_del, p_disp); /* * If we are in broadcast calibrate mode, return to broadcast * client mode when the client is fit and the autokey dance is * complete. */ if ( (FLAG_BC_VOL & peer->flags) && MODE_CLIENT == peer->hmode && !(TEST11 & peer_unfit(peer))) { /* distance exceeded */ #ifdef AUTOKEY if (peer->flags & FLAG_SKEY) { if (!(~peer->crypto & CRYPTO_FLAG_ALL)) peer->hmode = MODE_BCLIENT; } else { peer->hmode = MODE_BCLIENT; } #else /* !AUTOKEY follows */ peer->hmode = MODE_BCLIENT; #endif /* !AUTOKEY */ } } /* * clock_update - Called at system process update intervals. */ static void clock_update( struct peer *peer /* peer structure pointer */ ) { double dtemp; l_fp now; #ifdef HAVE_LIBSCF_H char *fmri; #endif /* HAVE_LIBSCF_H */ /* * Update the system state variables. We do this very carefully, * as the poll interval might need to be clamped differently. */ sys_peer = peer; sys_epoch = peer->epoch; if (sys_poll < peer->minpoll) sys_poll = peer->minpoll; if (sys_poll > peer->maxpoll) sys_poll = peer->maxpoll; poll_update(peer, sys_poll, 0); sys_stratum = min(peer->stratum + 1, STRATUM_UNSPEC); if ( peer->stratum == STRATUM_REFCLOCK || peer->stratum == STRATUM_UNSPEC) sys_refid = peer->refid; else sys_refid = addr2refid(&peer->srcadr); /* * Root Dispersion (E) is defined (in RFC 5905) as: * * E = p.epsilon_r + p.epsilon + p.psi + PHI*(s.t - p.t) + |THETA| * * where: * p.epsilon_r is the PollProc's root dispersion * p.epsilon is the PollProc's dispersion * p.psi is the PollProc's jitter * THETA is the combined offset * * NB: Think Hard about where these numbers come from and * what they mean. When did peer->update happen? Has anything * interesting happened since then? What values are the most * defensible? Why? * * DLM thinks this equation is probably the best of all worse choices. */ dtemp = peer->rootdisp + peer->disp + sys_jitter + clock_phi * (current_time - peer->update) + fabs(sys_offset); p2_rootdisp = prev_rootdisp; prev_rootdisp = sys_rootdisp; if (dtemp > sys_mindisp) sys_rootdisp = dtemp; else sys_rootdisp = sys_mindisp; sys_rootdelay = peer->delay + peer->rootdelay; p2_reftime = prev_reftime; p2_time = prev_time; prev_reftime = sys_reftime; prev_time = current_time + 64 + (rand() & 0x3f); /* 64-127 s */ sys_reftime = peer->dst; DPRINTF(1, ("clock_update: at %lu sample %lu associd %d\n", current_time, peer->epoch, peer->associd)); /* * Comes now the moment of truth. Crank the clock discipline and * see what comes out. */ switch (local_clock(peer, sys_offset)) { /* * Clock exceeds panic threshold. Life as we know it ends. */ case -1: msyslog(LOG_ERR, "Clock offset exceeds panic threshold."); #ifdef HAVE_LIBSCF_H /* * For Solaris enter the maintenance mode. */ if ((fmri = getenv("SMF_FMRI")) != NULL) { if (smf_maintain_instance(fmri, 0) < 0) { msyslog(LOG_ERR, "smf_maintain_instance: %s", scf_strerror(scf_error())); exit(1); } /* * Sleep until SMF kills us. */ msyslog(LOG_ERR, "%s placed into maintenance. " "Set system clock by hand before clearing.", fmri); for (;;) pause(); } #endif /* HAVE_LIBSCF_H */ msyslog(LOG_ERR, "Set system clock by hand."); exit (-1); /* not reached */ /* * Clock was stepped. Flush all time values of all peers. */ case 2: clear_all(); set_sys_leap(LEAP_NOTINSYNC); sys_stratum = STRATUM_UNSPEC; memcpy(&sys_refid, "STEP", 4); sys_rootdelay = 0; p2_rootdisp = 0; prev_rootdisp = 0; sys_rootdisp = 0; L_CLR(&p2_reftime); /* Should we clear p2_reftime? */ L_CLR(&prev_reftime); /* Should we clear prev_reftime? */ L_CLR(&sys_reftime); sys_jitter = LOGTOD(sys_precision); leapsec_reset_frame(); break; /* * Clock was slewed. Handle the leapsecond stuff. */ case 1: /* * If this is the first time the clock is set, reset the * leap bits. If crypto, the timer will goose the setup * process. */ if (sys_leap == LEAP_NOTINSYNC) { set_sys_leap(LEAP_NOWARNING); #ifdef AUTOKEY if (crypto_flags) crypto_update(); #endif /* AUTOKEY */ } /* * If there is no leap second pending and the number of * survivor leap bits is greater than half the number of * survivors, try to schedule a leap for the end of the * current month. (This only works if no leap second for * that range is in the table, so doing this more than * once is mostly harmless.) */ if (leapsec == LSPROX_NOWARN) { if ( leap_vote_ins > leap_vote_del && leap_vote_ins > sys_survivors / 2) { get_systime(&now); leapsec_add_dyn(TRUE, now.l_ui, NULL); } if ( leap_vote_del > leap_vote_ins && leap_vote_del > sys_survivors / 2) { get_systime(&now); leapsec_add_dyn(FALSE, now.l_ui, NULL); } } break; /* * Popcorn spike or step threshold exceeded. Pretend it never * happened. */ default: break; } } /* * poll_update - update peer poll interval */ void poll_update( struct peer *peer, /* peer structure pointer */ u_char mpoll, u_char skewpoll ) { u_long next, utemp, limit; u_char hpoll; /* * This routine figures out when the next poll should be sent. * That turns out to be wickedly complicated. One problem is * that sometimes the time for the next poll is in the past when * the poll interval is reduced. We watch out for races here * between the receive process and the poll process. * * Clamp the poll interval between minpoll and maxpoll. */ hpoll = max(min(peer->maxpoll, mpoll), peer->minpoll); #ifdef AUTOKEY /* * If during the crypto protocol the poll interval has changed, * the lifetimes in the key list are probably bogus. Purge the * the key list and regenerate it later. */ if ((peer->flags & FLAG_SKEY) && hpoll != peer->hpoll) key_expire(peer); #endif /* AUTOKEY */ peer->hpoll = hpoll; /* * There are three variables important for poll scheduling, the * current time (current_time), next scheduled time (nextdate) * and the earliest time (utemp). The earliest time is 2 s * seconds, but could be more due to rate management. When * sending in a burst, use the earliest time. When not in a * burst but with a reply pending, send at the earliest time * unless the next scheduled time has not advanced. This can * only happen if multiple replies are pending in the same * response interval. Otherwise, send at the later of the next * scheduled time and the earliest time. * * Now we figure out if there is an override. If a burst is in * progress and we get called from the receive process, just * slink away. If called from the poll process, delay 1 s for a * reference clock, otherwise 2 s. */ utemp = current_time + max(peer->throttle - (NTP_SHIFT - 1) * (1 << peer->minpoll), ntp_minpkt); /*[Bug 3592] avoid unlimited postpone of next poll */ limit = (2u << hpoll); if (limit > 64) limit -= (limit >> 2); limit += peer->outdate; if (limit < current_time) limit = current_time; if (peer->burst > 0) { if (peer->nextdate > current_time) return; #ifdef REFCLOCK else if (peer->flags & FLAG_REFCLOCK) peer->nextdate = current_time + RESP_DELAY; #endif /* REFCLOCK */ else peer->nextdate = utemp; #ifdef AUTOKEY /* * If a burst is not in progress and a crypto response message * is pending, delay 2 s, but only if this is a new interval. */ } else if (peer->cmmd != NULL) { if (peer->nextdate > current_time) { if (peer->nextdate + ntp_minpkt != utemp) peer->nextdate = utemp; } else { peer->nextdate = utemp; } #endif /* AUTOKEY */ /* * The ordinary case. If a retry, use minpoll; if unreachable, * use host poll; otherwise, use the minimum of host and peer * polls; In other words, oversampling is okay but * understampling is evil. Use the maximum of this value and the * headway. If the average headway is greater than the headway * threshold, increase the headway by the minimum interval. */ } else { if (peer->retry > 0) hpoll = peer->minpoll; else hpoll = min(peer->ppoll, peer->hpoll); #ifdef REFCLOCK if (peer->flags & FLAG_REFCLOCK) next = 1 << hpoll; else #endif /* REFCLOCK */ next = ((0x1000UL | (ntp_random() & 0x0ff)) << hpoll) >> 12; next += peer->outdate; /* XXX: bug3596: Deal with poll skew list? */ if (skewpoll) { psl_item psi; if (0 == get_pollskew(hpoll, &psi)) { int sub = psi.sub; int qty = psi.qty; int msk = psi.msk; int val; if ( 0 != sub || 0 != qty) { do { val = ntp_random() & msk; } while (val > qty); next -= sub; next += val; } } else { /* get_pollskew() already logged this */ } } if (next > utemp) peer->nextdate = next; else peer->nextdate = utemp; if (peer->throttle > (1 << peer->minpoll)) peer->nextdate += ntp_minpkt; } /*[Bug 3592] avoid unlimited postpone of next poll */ if (peer->nextdate > limit) { DPRINTF(1, ("poll_update: clamp reached; limit %lu next %lu\n", limit, peer->nextdate)); peer->nextdate = limit; } DPRINTF(2, ("poll_update: at %lu %s poll %d burst %d retry %d head %d early %lu next %lu\n", current_time, ntoa(&peer->srcadr), peer->hpoll, peer->burst, peer->retry, peer->throttle, utemp - current_time, peer->nextdate - current_time)); } /* * peer_clear - clear peer filter registers. See Section 3.4.8 of the * spec. */ void peer_clear( struct peer *peer, /* peer structure */ const char *ident /* tally lights */ ) { static u_long earliest; u_char u; l_fp bxmt = peer->bxmt; /* bcast clients retain this! */ #ifdef AUTOKEY /* * If cryptographic credentials have been acquired, toss them to * Valhalla. Note that autokeys are ephemeral, in that they are * tossed immediately upon use. Therefore, the keylist can be * purged anytime without needing to preserve random keys. Note * that, if the peer is purged, the cryptographic variables are * purged, too. This makes it much harder to sneak in some * unauthenticated data in the clock filter. */ key_expire(peer); if (peer->iffval != NULL) BN_free(peer->iffval); value_free(&peer->cookval); value_free(&peer->recval); value_free(&peer->encrypt); value_free(&peer->sndval); if (peer->cmmd != NULL) free(peer->cmmd); if (peer->subject != NULL) free(peer->subject); if (peer->issuer != NULL) free(peer->issuer); #endif /* AUTOKEY */ /* * Clear all values, including the optional crypto values above. */ memset(CLEAR_TO_ZERO(peer), 0, LEN_CLEAR_TO_ZERO(peer)); peer->ppoll = peer->maxpoll; peer->hpoll = peer->minpoll; peer->disp = MAXDISPERSE; peer->flash = peer_unfit(peer); peer->jitter = LOGTOD(sys_precision); /* Don't throw away our broadcast replay protection */ if (peer->hmode == MODE_BCLIENT) peer->bxmt = bxmt; /* * If interleave mode, initialize the alternate origin switch. */ if (peer->flags & FLAG_XLEAVE) peer->flip = 1; for (u = 0; u < NTP_SHIFT; u++) { peer->filter_order[u] = u; peer->filter_disp[u] = MAXDISPERSE; } #ifdef REFCLOCK if (!(peer->flags & FLAG_REFCLOCK)) { #endif peer->leap = LEAP_NOTINSYNC; peer->stratum = STRATUM_UNSPEC; memcpy(&peer->refid, ident, 4); #ifdef REFCLOCK } else { /* Clear refclock sample filter */ peer->procptr->codeproc = 0; peer->procptr->coderecv = 0; } #endif /* * During initialization use the association count to spread out * the polls at one-second intervals. Unconfigured associations' * first poll is delayed by the "discard minimum" plus 1 to avoid * rate limiting. Other post-startup new or cleared associations * randomize the first poll over the minimum poll interval to * avoid implosion. */ peer->nextdate = peer->update = peer->outdate = current_time; if (initializing) { peer->nextdate += peer_associations; } else if (!(FLAG_CONFIG & peer->flags)) { peer->nextdate += ntp_minpkt + 1; /* space out manycastclient first polls */ if (peer->nextdate < earliest) { peer->nextdate = earliest; } earliest = peer->nextdate + 1; } else { peer->nextdate += ntp_random() % (1 << peer->minpoll); } #ifdef AUTOKEY peer->refresh = current_time + (1 << NTP_REFRESH); #endif /* AUTOKEY */ DPRINTF(1, ("peer_clear: at %ld next %ld associd %d refid %s\n", current_time, peer->nextdate, peer->associd, ident)); } /* * clock_filter - add incoming clock sample to filter register and run * the filter procedure to find the best sample. */ void clock_filter( struct peer *peer, /* peer structure pointer */ double sample_offset, /* clock offset */ double sample_delay, /* roundtrip delay */ double sample_disp /* dispersion */ ) { double dst[NTP_SHIFT]; /* distance vector */ u_char ord[NTP_SHIFT]; /* index vector */ short i, j; u_char k, m; double dtemp, etemp; /* * A sample consists of the offset, delay, dispersion and epoch * of arrival. The offset and delay are determined by the on- * wire protocol. The dispersion grows from the last outbound * packet to the arrival of this one increased by the sum of the * peer precision and the system precision as required by the * error budget. First, shift the new arrival into the shift * register discarding the oldest one. */ j = peer->filter_nextpt; peer->filter_offset[j] = sample_offset; peer->filter_delay[j] = sample_delay; peer->filter_disp[j] = sample_disp; peer->filter_epoch[j] = current_time; j = (j + 1) % NTP_SHIFT; peer->filter_nextpt = (u_char)j; /* * Update dispersions since the last update and at the same * time initialize the distance and index lists. Since samples * become increasingly uncorrelated beyond the Allan intercept, * only under exceptional cases will an older sample be used. * Therefore, the distance list uses a compound metric. If the * dispersion is greater than the maximum dispersion, clamp the * distance at that value. If the time since the last update is * less than the Allan intercept use the delay; otherwise, use * the sum of the delay and dispersion. */ dtemp = clock_phi * (current_time - peer->update); peer->update = current_time; for (i = NTP_SHIFT - 1; i >= 0; i--) { if (i != 0) peer->filter_disp[j] += dtemp; if (peer->filter_disp[j] >= MAXDISPERSE) { peer->filter_disp[j] = MAXDISPERSE; dst[i] = MAXDISPERSE; } else if (peer->update - peer->filter_epoch[j] > (u_long)ULOGTOD(allan_xpt)) { dst[i] = peer->filter_delay[j] + peer->filter_disp[j]; } else { dst[i] = peer->filter_delay[j]; } ord[i] = (u_char)j; j = (j + 1) % NTP_SHIFT; } /* * If the clock has stabilized, sort the samples by distance. */ if (freq_cnt == 0) { for (i = 1; i < NTP_SHIFT; i++) { for (j = 0; j < i; j++) { if (dst[j] > dst[i]) { k = ord[j]; ord[j] = ord[i]; ord[i] = k; etemp = dst[j]; dst[j] = dst[i]; dst[i] = etemp; } } } } /* * Copy the index list to the association structure so ntpq * can see it later. Prune the distance list to leave only * samples less than the maximum dispersion, which disfavors * uncorrelated samples older than the Allan intercept. To * further improve the jitter estimate, of the remainder leave * only samples less than the maximum distance, but keep at * least two samples for jitter calculation. */ m = 0; for (i = 0; i < NTP_SHIFT; i++) { peer->filter_order[i] = ord[i]; if ( dst[i] >= MAXDISPERSE || (m >= 2 && dst[i] >= sys_maxdist)) continue; m++; } /* * Compute the dispersion and jitter. The dispersion is weighted * exponentially by NTP_FWEIGHT (0.5) so it is normalized close * to 1.0. The jitter is the RMS differences relative to the * lowest delay sample. */ peer->disp = peer->jitter = 0; k = ord[0]; for (i = NTP_SHIFT - 1; i >= 0; i--) { j = ord[i]; peer->disp = NTP_FWEIGHT * ( peer->disp + peer->filter_disp[j]); if (i < m) { peer->jitter += DIFF(peer->filter_offset[j], peer->filter_offset[k]); } } /* * If no acceptable samples remain in the shift register, * quietly tiptoe home leaving only the dispersion. Otherwise, * save the offset, delay and jitter. Note the jitter must not * be less than the precision. */ if (0 == m) { clock_select(); return; } etemp = fabs(peer->offset - peer->filter_offset[k]); peer->offset = peer->filter_offset[k]; peer->delay = peer->filter_delay[k]; if (m > 1) { peer->jitter /= m - 1; } peer->jitter = max(SQRT(peer->jitter), LOGTOD(sys_precision)); /* * If the the new sample and the current sample are both valid * and the difference between their offsets exceeds CLOCK_SGATE * (3) times the jitter and the interval between them is less * than twice the host poll interval, consider the new sample * a popcorn spike and ignore it. */ if ( peer->disp < sys_maxdist && peer->filter_disp[k] < sys_maxdist && etemp > CLOCK_SGATE * peer->jitter && peer->filter_epoch[k] - peer->epoch < 2. * ULOGTOD(peer->hpoll)) { mprintf_event(PEVNT_POPCORN, peer, "%.9f s", etemp); return; } /* * A new minimum sample is useful only if it is later than the * last one used. In this design the maximum lifetime of any * sample is not greater than NTP_SHIFT (8) times the poll * interval, so the maximum interval between minimum samples is * NTP_SHIFT packets. */ if (peer->filter_epoch[k] <= peer->epoch) { DPRINTF(2, ("clock_filter: old sample %lu s\n", current_time - peer->filter_epoch[k])); return; } peer->epoch = peer->filter_epoch[k]; /* * The mitigated sample statistics are saved for later * processing. If not synchronized or not in a burst, tickle the * clock select algorithm. */ record_peer_stats(&peer->srcadr, ctlpeerstatus(peer), peer->offset, peer->delay, peer->disp, peer->jitter); DPRINTF(1, ("clock_filter: n %hu off %.9f del %.9f dsp %.9f jit %.9f\n", (u_short)m, peer->offset, peer->delay, peer->disp, peer->jitter)); if (0 == peer->burst || LEAP_NOTINSYNC == sys_leap) { clock_select(); } } /* * clock_select - find the pick-of-the-litter clock * * LOCKCLOCK: (1) If the local clock is the prefer peer, it will always * be enabled, even if declared falseticker, (2) only the prefer peer * can be selected as the system peer, (3) if the external source is * down, the system leap bits are set to 11 and the stratum set to * infinity. */ void clock_select(void) { struct peer *peer; int i, j, k, n; int nlist, nl2; int allow; int speer; double d, e, f, g; double high, low; double speermet; double lastresort_dist = MAXDISPERSE; double orphmet = 2.0 * U_INT32_MAX; /* 2x is greater than */ struct endpoint endp; struct peer *osys_peer; struct peer *sys_prefer = NULL; /* prefer peer */ struct peer *typesystem = NULL; struct peer *typelastresort = NULL; struct peer *typeorphan = NULL; #ifdef REFCLOCK struct peer *typeacts = NULL; struct peer *typelocal = NULL; struct peer *typepps = NULL; #endif /* REFCLOCK */ static struct endpoint *endpoint = NULL; static int *indx = NULL; static peer_select *peers = NULL; static u_int endpoint_size = 0; static u_int peers_size = 0; static u_int indx_size = 0; size_t octets; /* * Initialize and create endpoint, index and peer lists big * enough to handle all associations. */ osys_peer = sys_peer; sys_survivors = 0; #ifdef LOCKCLOCK set_sys_leap(LEAP_NOTINSYNC); sys_stratum = STRATUM_UNSPEC; memcpy(&sys_refid, "DOWN", 4); #endif /* LOCKCLOCK */ /* * Allocate dynamic space depending on the number of * associations. */ nlist = 1; for (peer = peer_list; peer != NULL; peer = peer->p_link) nlist++; endpoint_size = ALIGNED_SIZE(nlist * 2 * sizeof(*endpoint)); peers_size = ALIGNED_SIZE(nlist * sizeof(*peers)); indx_size = ALIGNED_SIZE(nlist * 2 * sizeof(*indx)); octets = endpoint_size + peers_size + indx_size; endpoint = erealloc(endpoint, octets); peers = INC_ALIGNED_PTR(endpoint, endpoint_size); indx = INC_ALIGNED_PTR(peers, peers_size); /* * Initially, we populate the island with all the rifraff peers * that happen to be lying around. Those with seriously * defective clocks are immediately booted off the island. Then, * the falsetickers are culled and put to sea. The truechimers * remaining are subject to repeated rounds where the most * unpopular at each round is kicked off. When the population * has dwindled to sys_minclock, the survivors split a million * bucks and collectively crank the chimes. */ nlist = nl2 = 0; /* none yet */ for (peer = peer_list; peer != NULL; peer = peer->p_link) { peer->new_status = CTL_PST_SEL_REJECT; /* * Leave the island immediately if the peer is * unfit to synchronize. */ if (peer_unfit(peer)) { continue; } /* * If we have never been synchronised, look for any peer * which has ever been synchronised and pick the one which * has the lowest root distance. This can be used as a last * resort if all else fails. Once we get an initial sync * with this peer, sys_reftime gets set and so this * function becomes disabled. */ if (L_ISZERO(&sys_reftime)) { d = root_distance(peer); if (!L_ISZERO(&peer->reftime) && d < lastresort_dist) { typelastresort = peer; lastresort_dist = d; } } /* * If this peer is an orphan parent, elect the * one with the lowest metric defined as the * IPv4 address or the first 64 bits of the * hashed IPv6 address. To ensure convergence * on the same selected orphan, consider as * well that this system may have the lowest * metric and be the orphan parent. If this * system wins, sys_peer will be NULL to trigger * orphan mode in timer(). */ if (peer->stratum == sys_orphan) { u_int32 localmet; u_int32 peermet; if (peer->dstadr != NULL) localmet = ntohl(peer->dstadr->addr_refid); else localmet = U_INT32_MAX; peermet = ntohl(addr2refid(&peer->srcadr)); if (peermet < localmet && peermet < orphmet) { typeorphan = peer; orphmet = peermet; } continue; } /* * If this peer could have the orphan parent * as a synchronization ancestor, exclude it * from selection to avoid forming a * synchronization loop within the orphan mesh, * triggering stratum climb to infinity * instability. Peers at stratum higher than * the orphan stratum could have the orphan * parent in ancestry so are excluded. * See http://bugs.ntp.org/2050 */ if (peer->stratum > sys_orphan) { continue; } #ifdef REFCLOCK /* * The following are special cases. We deal * with them later. */ if (!(peer->flags & FLAG_PREFER)) { switch (peer->refclktype) { case REFCLK_LOCALCLOCK: if ( current_time > orphwait && typelocal == NULL) typelocal = peer; continue; case REFCLK_ACTS: if ( current_time > orphwait && typeacts == NULL) typeacts = peer; continue; } } #endif /* REFCLOCK */ /* * If we get this far, the peer can stay on the * island, but does not yet have the immunity * idol. */ peer->new_status = CTL_PST_SEL_SANE; f = root_distance(peer); peers[nlist].peer = peer; peers[nlist].error = peer->jitter; peers[nlist].synch = f; nlist++; /* * Insert each interval endpoint on the unsorted * endpoint[] list. */ e = peer->offset; endpoint[nl2].type = -1; /* lower end */ endpoint[nl2].val = e - f; nl2++; endpoint[nl2].type = 1; /* upper end */ endpoint[nl2].val = e + f; nl2++; } /* * Construct sorted indx[] of endpoint[] indexes ordered by * offset. */ for (i = 0; i < nl2; i++) indx[i] = i; for (i = 0; i < nl2; i++) { endp = endpoint[indx[i]]; e = endp.val; k = i; for (j = i + 1; j < nl2; j++) { endp = endpoint[indx[j]]; if (endp.val < e) { e = endp.val; k = j; } } if (k != i) { j = indx[k]; indx[k] = indx[i]; indx[i] = j; } } for (i = 0; i < nl2; i++) DPRINTF(3, ("select: endpoint %2d %.6f\n", endpoint[indx[i]].type, endpoint[indx[i]].val)); /* * This is the actual algorithm that cleaves the truechimers * from the falsetickers. The original algorithm was described * in Keith Marzullo's dissertation, but has been modified for * better accuracy. * * Briefly put, we first assume there are no falsetickers, then * scan the candidate list first from the low end upwards and * then from the high end downwards. The scans stop when the * number of intersections equals the number of candidates less * the number of falsetickers. If this doesn't happen for a * given number of falsetickers, we bump the number of * falsetickers and try again. If the number of falsetickers * becomes equal to or greater than half the number of * candidates, the Albanians have won the Byzantine wars and * correct synchronization is not possible. * * Here, nlist is the number of candidates and allow is the * number of falsetickers. Upon exit, the truechimers are the * survivors with offsets not less than low and not greater than * high. There may be none of them. */ low = 1e9; high = -1e9; for (allow = 0; 2 * allow < nlist; allow++) { /* * Bound the interval (low, high) as the smallest * interval containing points from the most sources. */ n = 0; for (i = 0; i < nl2; i++) { low = endpoint[indx[i]].val; n -= endpoint[indx[i]].type; if (n >= nlist - allow) break; } n = 0; for (j = nl2 - 1; j >= 0; j--) { high = endpoint[indx[j]].val; n += endpoint[indx[j]].type; if (n >= nlist - allow) break; } /* * If an interval containing truechimers is found, stop. * If not, increase the number of falsetickers and go * around again. */ if (high > low) break; } /* * Clustering algorithm. Whittle candidate list of falsetickers, * who leave the island immediately. The TRUE peer is always a * truechimer. We must leave at least one peer to collect the * million bucks. * * We assert the correct time is contained in the interval, but * the best offset estimate for the interval might not be * contained in the interval. For this purpose, a truechimer is * defined as the midpoint of an interval that overlaps the * intersection interval. */ j = 0; for (i = 0; i < nlist; i++) { double h; peer = peers[i].peer; h = peers[i].synch; if (( high <= low || peer->offset + h < low || peer->offset - h > high ) && !(peer->flags & FLAG_TRUE)) continue; #ifdef REFCLOCK /* * Eligible PPS peers must survive the intersection * algorithm. Use the first one found, but don't * include any of them in the cluster population. */ if (peer->flags & FLAG_PPS) { if (typepps == NULL) typepps = peer; if (!(peer->flags & FLAG_TSTAMP_PPS)) continue; } #endif /* REFCLOCK */ if (j != i) peers[j] = peers[i]; j++; } nlist = j; /* * If no survivors remain at this point, check if the modem * driver, local driver or orphan parent in that order. If so, * nominate the first one found as the only survivor. * Otherwise, give up and leave the island to the rats. */ if (nlist == 0) { peers[0].error = 0; peers[0].synch = sys_mindisp; #ifdef REFCLOCK if (typeacts != NULL) { peers[0].peer = typeacts; nlist = 1; } else if (typelocal != NULL) { peers[0].peer = typelocal; nlist = 1; } else #endif /* REFCLOCK */ if (typeorphan != NULL) { peers[0].peer = typeorphan; nlist = 1; } else if (typelastresort != NULL) { peers[0].peer = typelastresort; nlist = 1; } } /* * Mark the candidates at this point as truechimers. */ for (i = 0; i < nlist; i++) { peers[i].peer->new_status = CTL_PST_SEL_SELCAND; DPRINTF(2, ("select: survivor %s %f\n", stoa(&peers[i].peer->srcadr), peers[i].synch)); } /* * Now, vote outliers off the island by select jitter weighted * by root distance. Continue voting as long as there are more * than sys_minclock survivors and the select jitter of the peer * with the worst metric is greater than the minimum peer * jitter. Stop if we are about to discard a TRUE or PREFER * peer, who of course have the immunity idol. */ while (1) { d = 1e9; e = -1e9; g = 0; k = 0; for (i = 0; i < nlist; i++) { if (peers[i].error < d) d = peers[i].error; peers[i].seljit = 0; if (nlist > 1) { f = 0; for (j = 0; j < nlist; j++) f += DIFF(peers[j].peer->offset, peers[i].peer->offset); peers[i].seljit = SQRT(f / (nlist - 1)); } if (peers[i].seljit * peers[i].synch > e) { g = peers[i].seljit; e = peers[i].seljit * peers[i].synch; k = i; } } g = max(g, LOGTOD(sys_precision)); if ( nlist <= max(1, sys_minclock) || g <= d || ((FLAG_TRUE | FLAG_PREFER) & peers[k].peer->flags)) break; DPRINTF(3, ("select: drop %s seljit %.9f jit %.9f\n", ntoa(&peers[k].peer->srcadr), g, d)); if (nlist > sys_maxclock) peers[k].peer->new_status = CTL_PST_SEL_EXCESS; for (j = k + 1; j < nlist; j++) peers[j - 1] = peers[j]; nlist--; } /* * What remains is a list usually not greater than sys_minclock * peers. Note that unsynchronized peers cannot survive this * far. Count and mark these survivors. * * While at it, count the number of leap warning bits found. * This will be used later to vote the system leap warning bit. * If a leap warning bit is found on a reference clock, the vote * is always won. * * Choose the system peer using a hybrid metric composed of the * selection jitter scaled by the root distance augmented by * stratum scaled by sys_mindisp (.001 by default). The goal of * the small stratum factor is to avoid clockhop between a * reference clock and a network peer which has a refclock and * is using an older ntpd, which does not floor sys_rootdisp at * sys_mindisp. * * In contrast, ntpd 4.2.6 and earlier used stratum primarily * in selecting the system peer, using a weight of 1 second of * additional root distance per stratum. This heavy bias is no * longer appropriate, as the scaled root distance provides a * more rational metric carrying the cumulative error budget. */ e = 1e9; speer = 0; leap_vote_ins = 0; leap_vote_del = 0; for (i = 0; i < nlist; i++) { peer = peers[i].peer; peer->unreach = 0; peer->new_status = CTL_PST_SEL_SYNCCAND; sys_survivors++; if (peer->leap == LEAP_ADDSECOND) { if (peer->flags & FLAG_REFCLOCK) leap_vote_ins = nlist; else if (leap_vote_ins < nlist) leap_vote_ins++; } if (peer->leap == LEAP_DELSECOND) { if (peer->flags & FLAG_REFCLOCK) leap_vote_del = nlist; else if (leap_vote_del < nlist) leap_vote_del++; } if (peer->flags & FLAG_PREFER) sys_prefer = peer; speermet = peers[i].seljit * peers[i].synch + peer->stratum * sys_mindisp; if (speermet < e) { e = speermet; speer = i; } } /* * Unless there are at least sys_misane survivors, leave the * building dark. Otherwise, do a clockhop dance. Ordinarily, * use the selected survivor speer. However, if the current * system peer is not speer, stay with the current system peer * as long as it doesn't get too old or too ugly. */ if (nlist > 0 && nlist >= sys_minsane) { double x; typesystem = peers[speer].peer; if (osys_peer == NULL || osys_peer == typesystem) { sys_clockhop = 0; } else if ((x = fabs(typesystem->offset - osys_peer->offset)) < sys_mindisp) { if (0 == sys_clockhop) sys_clockhop = sys_mindisp; else sys_clockhop *= .5; DPRINTF(1, ("select: clockhop %d %.9f %.9f\n", j, x, sys_clockhop)); if (x < sys_clockhop) typesystem = osys_peer; else sys_clockhop = 0; } else { sys_clockhop = 0; } } /* * Mitigation rules of the game. We have the pick of the * litter in typesystem if any survivors are left. If * there is a prefer peer, use its offset and jitter. * Otherwise, use the combined offset and jitter of all kitters. */ if (typesystem != NULL) { if (sys_prefer == NULL) { typesystem->new_status = CTL_PST_SEL_SYSPEER; clock_combine(peers, sys_survivors, speer); } else { typesystem = sys_prefer; sys_clockhop = 0; typesystem->new_status = CTL_PST_SEL_SYSPEER; sys_offset = typesystem->offset; sys_jitter = typesystem->jitter; } DPRINTF(1, ("select: combine offset %.9f jitter %.9f\n", sys_offset, sys_jitter)); } #ifdef REFCLOCK /* * If a PPS driver is lit and the combined offset is less than * 0.4 s, select the driver as the PPS peer and use its offset * and jitter. However, if this is the atom driver, use it only * if there is a prefer peer or there are no survivors and none * are required. */ if ( typepps != NULL && fabs(sys_offset) < 0.4 && ( typepps->refclktype != REFCLK_ATOM_PPS || ( typepps->refclktype == REFCLK_ATOM_PPS && ( sys_prefer != NULL || (typesystem == NULL && sys_minsane == 0))))) { typesystem = typepps; sys_clockhop = 0; typesystem->new_status = CTL_PST_SEL_PPS; sys_offset = typesystem->offset; sys_jitter = typesystem->jitter; DPRINTF(1, ("select: pps offset %.9f jitter %.9f\n", sys_offset, sys_jitter)); } #endif /* REFCLOCK */ /* * If there are no survivors at this point, there is no * system peer. If so and this is an old update, keep the * current statistics, but do not update the clock. */ if (typesystem == NULL) { if (osys_peer != NULL) { orphwait = current_time + sys_orphwait; report_event(EVNT_NOPEER, NULL, NULL); } sys_peer = NULL; for (peer = peer_list; peer != NULL; peer = peer->p_link) peer->status = peer->new_status; return; } /* * Do not use old data, as this may mess up the clock discipline * stability. */ if (typesystem->epoch <= sys_epoch) return; /* * We have found the alpha male. Wind the clock. */ if (osys_peer != typesystem) report_event(PEVNT_NEWPEER, typesystem, NULL); for (peer = peer_list; peer != NULL; peer = peer->p_link) peer->status = peer->new_status; clock_update(typesystem); } static void clock_combine( peer_select * peers, /* survivor list */ int npeers, /* number of survivors */ int syspeer /* index of sys.peer */ ) { int i; double x, y, z, w; y = z = w = 0; for (i = 0; i < npeers; i++) { x = 1. / peers[i].synch; y += x; z += x * peers[i].peer->offset; w += x * DIFF(peers[i].peer->offset, peers[syspeer].peer->offset); } sys_offset = z / y; sys_jitter = SQRT(w / y + SQUARE(peers[syspeer].seljit)); } /* * root_distance - compute synchronization distance from peer to root */ static double root_distance( struct peer *peer /* peer structure pointer */ ) { double dtemp; /* * Root Distance (LAMBDA) is defined as: * (delta + DELTA)/2 + epsilon + EPSILON + D * * where: * delta is the round-trip delay * DELTA is the root delay * epsilon is the peer dispersion * + (15 usec each second) * EPSILON is the root dispersion * D is sys_jitter * * NB: Think hard about why we are using these values, and what * the alternatives are, and the various pros/cons. * * DLM thinks these are probably the best choices from any of the * other worse choices. */ dtemp = (peer->delay + peer->rootdelay) / 2 + peer->disp + clock_phi * (current_time - peer->update) + peer->rootdisp + peer->jitter; /* * Careful squeak here. The value returned must be greater than * the minimum root dispersion in order to avoid clockhop with * highly precise reference clocks. Note that the root distance * cannot exceed the sys_maxdist, as this is the cutoff by the * selection algorithm. */ if (dtemp < sys_mindisp) dtemp = sys_mindisp; return (dtemp); } /* * peer_xmit - send packet for persistent association. */ static void peer_xmit( struct peer *peer /* peer structure pointer */ ) { struct pkt xpkt; /* transmit packet */ size_t sendlen, authlen; keyid_t xkeyid = 0; /* transmit key ID */ l_fp xmt_tx, xmt_ty; if (!peer->dstadr) { /* can't send */ return; } xpkt.li_vn_mode = PKT_LI_VN_MODE(sys_leap, peer->version, peer->hmode); xpkt.stratum = STRATUM_TO_PKT(sys_stratum); xpkt.ppoll = peer->hpoll; xpkt.precision = sys_precision; xpkt.refid = sys_refid; xpkt.rootdelay = HTONS_FP(DTOFP(sys_rootdelay)); xpkt.rootdisp = HTONS_FP(DTOUFP(sys_rootdisp)); /* Use sys_reftime for peer exchanges */ HTONL_FP(&sys_reftime, &xpkt.reftime); HTONL_FP(&peer->rec, &xpkt.org); HTONL_FP(&peer->dst, &xpkt.rec); /* * If the received packet contains a MAC, the transmitted packet * is authenticated and contains a MAC. If not, the transmitted * packet is not authenticated. * * It is most important when autokey is in use that the local * interface IP address be known before the first packet is * sent. Otherwise, it is not possible to compute a correct MAC * the recipient will accept. Thus, the I/O semantics have to do * a little more work. In particular, the wildcard interface * might not be usable. */ sendlen = LEN_PKT_NOMAC; if ( #ifdef AUTOKEY !(peer->flags & FLAG_SKEY) && #endif /* !AUTOKEY */ peer->keyid == 0) { /* * Transmit a-priori timestamps */ get_systime(&xmt_tx); if (peer->flip == 0) { /* basic mode */ peer->aorg = xmt_tx; HTONL_FP(&xmt_tx, &xpkt.xmt); } else { /* interleaved modes */ if (peer->hmode == MODE_BROADCAST) { /* bcst */ HTONL_FP(&xmt_tx, &xpkt.xmt); if (peer->flip > 0) HTONL_FP(&peer->borg, &xpkt.org); else HTONL_FP(&peer->aorg, &xpkt.org); } else { /* symmetric */ if (peer->flip > 0) HTONL_FP(&peer->borg, &xpkt.xmt); else HTONL_FP(&peer->aorg, &xpkt.xmt); } } peer->t21_bytes = sendlen; sendpkt(&peer->srcadr, peer->dstadr, sys_ttl[(peer->ttl >= sys_ttlmax) ? sys_ttlmax : peer->ttl], &xpkt, sendlen); peer->sent++; peer->throttle += (1 << peer->minpoll) - 2; /* * Capture a-posteriori timestamps */ get_systime(&xmt_ty); if (peer->flip != 0) { /* interleaved modes */ if (peer->flip > 0) peer->aorg = xmt_ty; else peer->borg = xmt_ty; peer->flip = -peer->flip; } L_SUB(&xmt_ty, &xmt_tx); LFPTOD(&xmt_ty, peer->xleave); DPRINTF(1, ("peer_xmit: at %ld %s->%s mode %d len %zu xmt 0x%x.%08x\n", current_time, latoa(peer->dstadr), stoa(&peer->srcadr), peer->hmode, sendlen, xmt_tx.l_ui, xmt_tx.l_uf)); return; } /* * Authentication is enabled, so the transmitted packet must be * authenticated. If autokey is enabled, fuss with the various * modes; otherwise, symmetric key cryptography is used. */ #ifdef AUTOKEY if (peer->flags & FLAG_SKEY) { struct exten *exten; /* extension field */ /* * The Public Key Dance (PKD): Cryptographic credentials * are contained in extension fields, each including a * 4-octet length/code word followed by a 4-octet * association ID and optional additional data. Optional * data includes a 4-octet data length field followed by * the data itself. Request messages are sent from a * configured association; response messages can be sent * from a configured association or can take the fast * path without ever matching an association. Response * messages have the same code as the request, but have * a response bit and possibly an error bit set. In this * implementation, a message may contain no more than * one command and one or more responses. * * Cryptographic session keys include both a public and * a private componet. Request and response messages * using extension fields are always sent with the * private component set to zero. Packets without * extension fields indlude the private component when * the session key is generated. */ while (1) { /* * Allocate and initialize a keylist if not * already done. Then, use the list in inverse * order, discarding keys once used. Keep the * latest key around until the next one, so * clients can use client/server packets to * compute propagation delay. * * Note that once a key is used from the list, * it is retained in the key cache until the * next key is used. This is to allow a client * to retrieve the encrypted session key * identifier to verify authenticity. * * If for some reason a key is no longer in the * key cache, a birthday has happened or the key * has expired, so the pseudo-random sequence is * broken. In that case, purge the keylist and * regenerate it. */ if (peer->keynumber == 0) make_keylist(peer, peer->dstadr); else peer->keynumber--; xkeyid = peer->keylist[peer->keynumber]; if (authistrusted(xkeyid)) break; else key_expire(peer); } peer->keyid = xkeyid; exten = NULL; switch (peer->hmode) { /* * In broadcast server mode the autokey values are * required by the broadcast clients. Push them when a * new keylist is generated; otherwise, push the * association message so the client can request them at * other times. */ case MODE_BROADCAST: if (peer->flags & FLAG_ASSOC) exten = crypto_args(peer, CRYPTO_AUTO | CRYPTO_RESP, peer->associd, NULL); else exten = crypto_args(peer, CRYPTO_ASSOC | CRYPTO_RESP, peer->associd, NULL); break; /* * In symmetric modes the parameter, certificate, * identity, cookie and autokey exchanges are * required. The leapsecond exchange is optional. But, a * peer will not believe the other peer until the other * peer has synchronized, so the certificate exchange * might loop until then. If a peer finds a broken * autokey sequence, it uses the autokey exchange to * retrieve the autokey values. In any case, if a new * keylist is generated, the autokey values are pushed. */ case MODE_ACTIVE: case MODE_PASSIVE: /* * Parameter, certificate and identity. */ if (!peer->crypto) exten = crypto_args(peer, CRYPTO_ASSOC, peer->associd, hostval.ptr); else if (!(peer->crypto & CRYPTO_FLAG_CERT)) exten = crypto_args(peer, CRYPTO_CERT, peer->associd, peer->issuer); else if (!(peer->crypto & CRYPTO_FLAG_VRFY)) exten = crypto_args(peer, crypto_ident(peer), peer->associd, NULL); /* * Cookie and autokey. We request the cookie * only when the this peer and the other peer * are synchronized. But, this peer needs the * autokey values when the cookie is zero. Any * time we regenerate the key list, we offer the * autokey values without being asked. If for * some reason either peer finds a broken * autokey sequence, the autokey exchange is * used to retrieve the autokey values. */ else if ( sys_leap != LEAP_NOTINSYNC && peer->leap != LEAP_NOTINSYNC && !(peer->crypto & CRYPTO_FLAG_COOK)) exten = crypto_args(peer, CRYPTO_COOK, peer->associd, NULL); else if (!(peer->crypto & CRYPTO_FLAG_AUTO)) exten = crypto_args(peer, CRYPTO_AUTO, peer->associd, NULL); else if ( peer->flags & FLAG_ASSOC && peer->crypto & CRYPTO_FLAG_SIGN) exten = crypto_args(peer, CRYPTO_AUTO | CRYPTO_RESP, peer->assoc, NULL); /* * Wait for clock sync, then sign the * certificate and retrieve the leapsecond * values. */ else if (sys_leap == LEAP_NOTINSYNC) break; else if (!(peer->crypto & CRYPTO_FLAG_SIGN)) exten = crypto_args(peer, CRYPTO_SIGN, peer->associd, hostval.ptr); else if (!(peer->crypto & CRYPTO_FLAG_LEAP)) exten = crypto_args(peer, CRYPTO_LEAP, peer->associd, NULL); break; /* * In client mode the parameter, certificate, identity, * cookie and sign exchanges are required. The * leapsecond exchange is optional. If broadcast client * mode the same exchanges are required, except that the * autokey exchange is substitutes for the cookie * exchange, since the cookie is always zero. If the * broadcast client finds a broken autokey sequence, it * uses the autokey exchange to retrieve the autokey * values. */ case MODE_CLIENT: /* * Parameter, certificate and identity. */ if (!peer->crypto) exten = crypto_args(peer, CRYPTO_ASSOC, peer->associd, hostval.ptr); else if (!(peer->crypto & CRYPTO_FLAG_CERT)) exten = crypto_args(peer, CRYPTO_CERT, peer->associd, peer->issuer); else if (!(peer->crypto & CRYPTO_FLAG_VRFY)) exten = crypto_args(peer, crypto_ident(peer), peer->associd, NULL); /* * Cookie and autokey. These are requests, but * we use the peer association ID with autokey * rather than our own. */ else if (!(peer->crypto & CRYPTO_FLAG_COOK)) exten = crypto_args(peer, CRYPTO_COOK, peer->associd, NULL); else if (!(peer->crypto & CRYPTO_FLAG_AUTO)) exten = crypto_args(peer, CRYPTO_AUTO, peer->assoc, NULL); /* * Wait for clock sync, then sign the * certificate and retrieve the leapsecond * values. */ else if (sys_leap == LEAP_NOTINSYNC) break; else if (!(peer->crypto & CRYPTO_FLAG_SIGN)) exten = crypto_args(peer, CRYPTO_SIGN, peer->associd, hostval.ptr); else if (!(peer->crypto & CRYPTO_FLAG_LEAP)) exten = crypto_args(peer, CRYPTO_LEAP, peer->associd, NULL); break; } /* * Add a queued extension field if present. This is * always a request message, so the reply ID is already * in the message. If an error occurs, the error bit is * lit in the response. */ if (peer->cmmd != NULL) { u_int32 temp32; temp32 = CRYPTO_RESP; peer->cmmd->opcode |= htonl(temp32); sendlen += crypto_xmit(peer, &xpkt, NULL, sendlen, peer->cmmd, 0); free(peer->cmmd); peer->cmmd = NULL; } /* * Add an extension field created above. All but the * autokey response message are request messages. */ if (exten != NULL) { if (exten->opcode != 0) sendlen += crypto_xmit(peer, &xpkt, NULL, sendlen, exten, 0); free(exten); } /* * Calculate the next session key. Since extension * fields are present, the cookie value is zero. */ if (sendlen > (int)LEN_PKT_NOMAC) { session_key(&peer->dstadr->sin, &peer->srcadr, xkeyid, 0, 2); } } #endif /* AUTOKEY */ /* * Transmit a-priori timestamps */ get_systime(&xmt_tx); if (peer->flip == 0) { /* basic mode */ peer->aorg = xmt_tx; HTONL_FP(&xmt_tx, &xpkt.xmt); } else { /* interleaved modes */ if (peer->hmode == MODE_BROADCAST) { /* bcst */ HTONL_FP(&xmt_tx, &xpkt.xmt); if (peer->flip > 0) HTONL_FP(&peer->borg, &xpkt.org); else HTONL_FP(&peer->aorg, &xpkt.org); } else { /* symmetric */ if (peer->flip > 0) HTONL_FP(&peer->borg, &xpkt.xmt); else HTONL_FP(&peer->aorg, &xpkt.xmt); } } xkeyid = peer->keyid; authlen = authencrypt(xkeyid, (u_int32 *)&xpkt, sendlen); if (authlen == 0) { report_event(PEVNT_AUTH, peer, "no key"); peer->flash |= TEST5; /* auth error */ peer->badauth++; return; } sendlen += authlen; #ifdef AUTOKEY if (xkeyid > NTP_MAXKEY) authtrust(xkeyid, 0); #endif /* AUTOKEY */ if (sendlen > sizeof(xpkt)) { msyslog(LOG_ERR, "peer_xmit: buffer overflow %u", (u_int)sendlen); exit(EX_SOFTWARE); } peer->t21_bytes = sendlen; sendpkt(&peer->srcadr, peer->dstadr, sys_ttl[(peer->ttl >= sys_ttlmax) ? sys_ttlmax : peer->ttl], &xpkt, sendlen); peer->sent++; peer->throttle += (1 << peer->minpoll) - 2; /* * Capture a-posteriori timestamps */ get_systime(&xmt_ty); if (peer->flip != 0) { /* interleaved modes */ if (peer->flip > 0) peer->aorg = xmt_ty; else peer->borg = xmt_ty; peer->flip = -peer->flip; } L_SUB(&xmt_ty, &xmt_tx); LFPTOD(&xmt_ty, peer->xleave); #ifdef AUTOKEY DPRINTF(1, ("peer_xmit: at %ld %s->%s mode %d keyid %08x len %zu index %d\n", current_time, latoa(peer->dstadr), stoa(&peer->srcadr), peer->hmode, xkeyid, sendlen, peer->keynumber)); #else /* !AUTOKEY follows */ DPRINTF(1, ("peer_xmit: at %ld %s->%s mode %d keyid %08x len %zu\n", current_time, peer->dstadr ? ntoa(&peer->dstadr->sin) : "-", ntoa(&peer->srcadr), peer->hmode, xkeyid, sendlen)); #endif /* !AUTOKEY */ return; } #ifdef LEAP_SMEAR static void leap_smear_add_offs( l_fp *t, l_fp *t_recv ) { L_ADD(t, &leap_smear.offset); /* ** XXX: Should the smear be added to the root dispersion? */ return; } #endif /* LEAP_SMEAR */ /* * fast_xmit - Send packet for nonpersistent association. Note that * neither the source or destination can be a broadcast address. */ static void fast_xmit( struct recvbuf* rbufp, /* receive packet pointer */ int xmode, /* receive mode */ /* XXX: HMS: really? */ keyid_t xkeyid, /* transmit key ID */ int flags /* restrict mask */ ) { struct pkt xpkt; /* transmit packet structure */ struct pkt* rpkt; /* receive packet structure */ l_fp xmt_tx, xmt_ty; size_t sendlen; #ifdef AUTOKEY u_int32 temp32; #endif /* * Initialize transmit packet header fields from the receive * buffer provided. We leave the fields intact as received, but * set the peer poll at the maximum of the receive peer poll and * the system minimum poll (ntp_minpoll). This is for KoD rate * control and not strictly specification compliant, but doesn't * break anything. */ rpkt = &rbufp->recv_pkt; /* * If the packet was received on an endpoint open only on * a multicast address, the response needs to go out from * a unicast endpoint. */ #ifndef MULTICAST_NONEWSOCKET if (rbufp->dstadr->flags & INT_MCASTOPEN) { rbufp->dstadr = findinterface(&rbufp->recv_srcadr); if (NULL == rbufp->dstadr || ANY_INTERFACE_CHOOSE(&rbufp->recv_srcadr) /* wildcard */ == rbufp->dstadr) { DPRINTF(2, ("No unicast local address found for" " reply to %s mcast.", stoa(&rbufp->recv_srcadr))); return; } } #endif /* * If this is a kiss-o'-death (KoD) packet, show leap * unsynchronized, stratum zero, reference ID the four-character * kiss code and (???) system root delay. Note we don't reveal * the local time, so these packets can't be used for * synchronization. */ if (flags & RES_KOD) { sys_kodsent++; xpkt.li_vn_mode = PKT_LI_VN_MODE(LEAP_NOTINSYNC, PKT_VERSION(rpkt->li_vn_mode), xmode); xpkt.stratum = STRATUM_PKT_UNSPEC; xpkt.ppoll = max(rpkt->ppoll, ntp_minpoll); xpkt.precision = rpkt->precision; memcpy(&xpkt.refid, "RATE", 4); xpkt.rootdelay = rpkt->rootdelay; xpkt.rootdisp = rpkt->rootdisp; xpkt.reftime = rpkt->reftime; xpkt.org = rpkt->xmt; xpkt.rec = rpkt->xmt; xpkt.xmt = rpkt->xmt; /* * This is a normal packet. Use the system variables. */ } else { double this_rootdisp; l_fp this_ref_time; #ifdef LEAP_SMEAR /* * Make copies of the variables which can be affected by smearing. */ l_fp this_recv_time; #endif /* * If we are inside the leap smear interval we add * the current smear offset to: * - the packet receive time, * - the packet transmit time, * - and eventually to the reftime to make sure the * reftime isn't later than the transmit/receive times. */ xpkt.li_vn_mode = PKT_LI_VN_MODE(xmt_leap, PKT_VERSION(rpkt->li_vn_mode), xmode); xpkt.stratum = STRATUM_TO_PKT(sys_stratum); xpkt.ppoll = max(rpkt->ppoll, ntp_minpoll); xpkt.precision = sys_precision; xpkt.refid = sys_refid; xpkt.rootdelay = HTONS_FP(DTOFP(sys_rootdelay)); /* ** Server Response Fuzzing ** ** Which values do we want to use for reftime and rootdisp? */ if ( MODE_SERVER == xmode && RES_SRVRSPFUZ & flags) { if (current_time < p2_time) { this_ref_time = p2_reftime; this_rootdisp = p2_rootdisp; } else if (current_time < prev_time) { this_ref_time = prev_reftime; this_rootdisp = prev_rootdisp; } else { this_ref_time = sys_reftime; this_rootdisp = sys_rootdisp; } SRVRSP_FUZZ(this_ref_time); } else { this_ref_time = sys_reftime; this_rootdisp = sys_rootdisp; } /* ** ROOT DISPERSION */ xpkt.rootdisp = HTONS_FP(DTOUFP(this_rootdisp)); /* ** REFTIME */ #ifdef LEAP_SMEAR if (leap_smear.in_progress) { /* adjust the reftime by the same amount as the * leap smear, as we don't want to risk the * reftime being later than the transmit time. */ leap_smear_add_offs(&this_ref_time, NULL); } #endif HTONL_FP(&this_ref_time, &xpkt.reftime); /* ** REFID */ #ifdef LEAP_SMEAR if (leap_smear.in_progress) { xpkt.refid = convertLFPToRefID(leap_smear.offset); DPRINTF(2, ("fast_xmit: leap_smear.in_progress: refid %8x, smear %s\n", ntohl(xpkt.refid), lfptoa(&leap_smear.offset, 8) )); } #endif /* ** ORIGIN */ xpkt.org = rpkt->xmt; /* ** RECEIVE */ #ifdef LEAP_SMEAR this_recv_time = rbufp->recv_time; if (leap_smear.in_progress) leap_smear_add_offs(&this_recv_time, NULL); HTONL_FP(&this_recv_time, &xpkt.rec); #else HTONL_FP(&rbufp->recv_time, &xpkt.rec); #endif /* ** TRANSMIT */ get_systime(&xmt_tx); #ifdef LEAP_SMEAR if (leap_smear.in_progress) leap_smear_add_offs(&xmt_tx, &this_recv_time); #endif HTONL_FP(&xmt_tx, &xpkt.xmt); } #ifdef HAVE_NTP_SIGND if (flags & RES_MSSNTP) { send_via_ntp_signd(rbufp, xmode, xkeyid, flags, &xpkt); return; } #endif /* HAVE_NTP_SIGND */ /* * If the received packet contains a MAC, the transmitted packet * is authenticated and contains a MAC. If not, the transmitted * packet is not authenticated. */ sendlen = LEN_PKT_NOMAC; if (rbufp->recv_length == sendlen) { sendpkt(&rbufp->recv_srcadr, rbufp->dstadr, 0, &xpkt, sendlen); DPRINTF(1, ("fast_xmit: at %ld %s->%s mode %d len %lu\n", current_time, stoa(&rbufp->dstadr->sin), stoa(&rbufp->recv_srcadr), xmode, (u_long)sendlen)); return; } /* * The received packet contains a MAC, so the transmitted packet * must be authenticated. For symmetric key cryptography, use * the predefined and trusted symmetric keys to generate the * cryptosum. For autokey cryptography, use the server private * value to generate the cookie, which is unique for every * source-destination-key ID combination. */ #ifdef AUTOKEY if (xkeyid > NTP_MAXKEY) { keyid_t cookie; /* * The only way to get here is a reply to a legitimate * client request message, so the mode must be * MODE_SERVER. If an extension field is present, there * can be only one and that must be a command. Do what * needs, but with private value of zero so the poor * jerk can decode it. If no extension field is present, * use the cookie to generate the session key. */ cookie = session_key(&rbufp->recv_srcadr, &rbufp->dstadr->sin, 0, sys_private, 0); if ((size_t)rbufp->recv_length > sendlen + MAX_MAC_LEN) { session_key(&rbufp->dstadr->sin, &rbufp->recv_srcadr, xkeyid, 0, 2); temp32 = CRYPTO_RESP; rpkt->exten[0] |= htonl(temp32); sendlen += crypto_xmit(NULL, &xpkt, rbufp, sendlen, (struct exten *)rpkt->exten, cookie); } else { session_key(&rbufp->dstadr->sin, &rbufp->recv_srcadr, xkeyid, cookie, 2); } } #endif /* AUTOKEY */ get_systime(&xmt_tx); sendlen += authencrypt(xkeyid, (u_int32 *)&xpkt, sendlen); #ifdef AUTOKEY if (xkeyid > NTP_MAXKEY) authtrust(xkeyid, 0); #endif /* AUTOKEY */ sendpkt(&rbufp->recv_srcadr, rbufp->dstadr, 0, &xpkt, sendlen); get_systime(&xmt_ty); L_SUB(&xmt_ty, &xmt_tx); sys_authdelay = xmt_ty; DPRINTF(1, ("fast_xmit: at %ld %s->%s mode %d keyid %08x len %lu\n", current_time, ntoa(&rbufp->dstadr->sin), ntoa(&rbufp->recv_srcadr), xmode, xkeyid, (u_long)sendlen)); } /* * pool_xmit - resolve hostname or send unicast solicitation for pool. */ static void pool_xmit( struct peer *pool /* pool solicitor association */ ) { #ifdef WORKER struct pkt xpkt; /* transmit packet structure */ struct addrinfo hints; int rc; endpt * lcladr; sockaddr_u * rmtadr; u_short af; struct peer * p; l_fp xmt_tx; DEBUG_REQUIRE(pool); if (NULL == pool->ai) { if (pool->addrs != NULL) { /* free() is used with copy_addrinfo_list() */ free(pool->addrs); pool->addrs = NULL; } af = AF(&pool->srcadr); if ( (AF_INET == af && !nonlocal_v4_addr_up) || (AF_INET6 == af && !nonlocal_v6_addr_up) || ( AF_UNSPEC == af && !nonlocal_v4_addr_up && !nonlocal_v6_addr_up)) { /* POOL DNS query would be useless [Bug 3845] */ return; } ZERO(hints); hints.ai_family = AF(&pool->srcadr); hints.ai_socktype = SOCK_DGRAM; hints.ai_protocol = IPPROTO_UDP; /* ignore getaddrinfo_sometime() errors, we will retry */ rc = getaddrinfo_sometime( pool->hostname, "ntp", &hints, 0, /* no retry */ &pool_name_resolved, (void *)(intptr_t)pool->associd); if (!rc) DPRINTF(1, ("pool DNS lookup %s started\n", pool->hostname)); else msyslog(LOG_ERR, "unable to start pool DNS %s: %m", pool->hostname); return; } do { /* copy_addrinfo_list ai_addr points to a sockaddr_u */ rmtadr = (sockaddr_u *)(void *)pool->ai->ai_addr; pool->ai = pool->ai->ai_next; /* do not solicit when hopeless [Bug 3845] */ if ( (IS_IPV4(rmtadr) && !nonlocal_v4_addr_up) || (IS_IPV6(rmtadr) && !nonlocal_v6_addr_up)) { continue; } p = findexistingpeer(rmtadr, NULL, NULL, MODE_CLIENT, 0, NULL); } while (p != NULL && pool->ai != NULL); if (p != NULL) { return; /* out of addresses, re-query DNS next poll */ } restrict_source(rmtadr, FALSE, 1 + POOL_SOLICIT_WINDOW); lcladr = findinterface(rmtadr); memset(&xpkt, 0, sizeof(xpkt)); xpkt.li_vn_mode = PKT_LI_VN_MODE(sys_leap, pool->version, MODE_CLIENT); xpkt.stratum = STRATUM_TO_PKT(sys_stratum); xpkt.ppoll = pool->hpoll; xpkt.precision = sys_precision; xpkt.refid = sys_refid; xpkt.rootdelay = HTONS_FP(DTOFP(sys_rootdelay)); xpkt.rootdisp = HTONS_FP(DTOUFP(sys_rootdisp)); /* Bug 3596: What are the pros/cons of using sys_reftime here? */ HTONL_FP(&sys_reftime, &xpkt.reftime); get_systime(&xmt_tx); pool->aorg = xmt_tx; if (FLAG_LOOPNONCE & pool->flags) { l_fp nonce; do { nonce.l_ui = ntp_random(); } while (0 == nonce.l_ui); do { nonce.l_uf = ntp_random(); } while (0 == nonce.l_uf); pool->nonce = nonce; HTONL_FP(&nonce, &xpkt.xmt); } else { L_CLR(&pool->nonce); HTONL_FP(&xmt_tx, &xpkt.xmt); } pool->sent++; pool->throttle += (1 << pool->minpoll) - 2; DPRINTF(1, ("pool_xmit: at %ld %s->%s pool\n", current_time, latoa(lcladr), stoa(rmtadr))); msyslog(LOG_INFO, "Soliciting pool server %s", stoa(rmtadr)); sendpkt(rmtadr, lcladr, sys_ttl[(pool->ttl >= sys_ttlmax) ? sys_ttlmax : pool->ttl], &xpkt, LEN_PKT_NOMAC); #endif /* WORKER */ } #ifdef AUTOKEY /* * group_test - test if this is the same group * * host assoc return action * none none 0 mobilize * * none group 0 mobilize * * group none 0 mobilize * * group group 1 mobilize * group different 1 ignore * * ignore if notrust */ int group_test( char *grp, char *ident ) { if (grp == NULL) return (0); if (strcmp(grp, sys_groupname) == 0) return (0); if (ident == NULL) return (1); if (strcmp(grp, ident) == 0) return (0); return (1); } #endif /* AUTOKEY */ #ifdef WORKER void pool_name_resolved( int rescode, int gai_errno, void * context, const char * name, const char * service, const struct addrinfo * hints, const struct addrinfo * res ) { struct peer * pool; /* pool solicitor association */ associd_t assoc; if (rescode) { msyslog(LOG_ERR, "error resolving pool %s: %s (%d)", name, gai_strerror(rescode), rescode); return; } assoc = (associd_t)(intptr_t)context; pool = findpeerbyassoc(assoc); if (NULL == pool) { msyslog(LOG_ERR, "Could not find assoc %u for pool DNS %s", assoc, name); return; } DPRINTF(1, ("pool DNS %s completed\n", name)); pool->addrs = copy_addrinfo_list(res); pool->ai = pool->addrs; pool_xmit(pool); } #endif /* WORKER */ #ifdef AUTOKEY /* * key_expire - purge the key list */ void key_expire( struct peer *peer /* peer structure pointer */ ) { int i; if (peer->keylist != NULL) { for (i = 0; i <= peer->keynumber; i++) authtrust(peer->keylist[i], 0); free(peer->keylist); peer->keylist = NULL; } value_free(&peer->sndval); peer->keynumber = 0; peer->flags &= ~FLAG_ASSOC; DPRINTF(1, ("key_expire: at %lu associd %d\n", current_time, peer->associd)); } #endif /* AUTOKEY */ /* * local_refid(peer) - Check peer refid to avoid selecting peers * currently synced to this ntpd. * Note that until 4.2.8p18 and 4.3.1XX ntpd calculated the IPv6 * refid differently on different-endian systems. It now calculates * the refid the same on both, the same way it did on little-endian * in the past. On big-endian systems, ntpd also calculates a * byte-swapped version of each of its IPv6 local addresses' refids, * as endpt.old_refid and also detects a loop when seeing it. This * ensures new BE ntpd will detect loops interoperating with older * BE ntpd, and keeps the more-common LE old ntpd code detecting * loops with IPv6 refids correctly. Thanks to Hal Murray for * the byte-swapping idea. */ static int local_refid( struct peer * p ) { endpt * unicast_ep; if (p->dstadr != NULL && !(INT_MCASTIF & p->dstadr->flags)) unicast_ep = p->dstadr; else unicast_ep = findinterface(&p->srcadr); if (unicast_ep != NULL && ( p->refid == unicast_ep->addr_refid #ifdef WORDS_BIGENDIAN || ( IS_IPV6(&unicast_ep->sin) && p->refid == unicast_ep->old_refid) #endif )) { return TRUE; } else { return FALSE; } } /* * Determine if the peer is unfit for synchronization * * A peer is unfit for synchronization if * > TEST10 bad leap or stratum below floor or at or above ceiling * > TEST11 root distance exceeded for remote peer * > TEST12 a direct or indirect synchronization loop would form * > TEST13 unreachable or noselect */ int /* FALSE if fit, TRUE if unfit */ peer_unfit( struct peer *peer /* peer structure pointer */ ) { int rval = 0; /* * A stratum error occurs if (1) the server has never been * synchronized, (2) the server stratum is below the floor or * greater than or equal to the ceiling. */ if ( peer->leap == LEAP_NOTINSYNC || peer->stratum < sys_floor || peer->stratum >= sys_ceiling) { rval |= TEST10; /* bad synch or stratum */ } /* * A distance error for a remote peer occurs if the root * distance is greater than or equal to the distance threshold * plus the increment due to one host poll interval. */ if ( !(peer->flags & FLAG_REFCLOCK) && root_distance(peer) >= sys_maxdist + clock_phi * ULOGTOD(peer->hpoll)) { rval |= TEST11; /* distance exceeded */ } /* * A loop error occurs if the remote peer is synchronized to the * local peer or if the remote peer is synchronized to the same * server as the local peer but only if the remote peer is * neither a reference clock nor an orphan. */ if (peer->stratum > 1 && local_refid(peer)) { rval |= TEST12; /* synchronization loop */ } /* * An unreachable error occurs if the server is unreachable or * the noselect bit is set. */ if (!peer->reach || (peer->flags & FLAG_NOSELECT)) { rval |= TEST13; /* unreachable */ } peer->flash &= ~PEER_TEST_MASK; peer->flash |= rval; return (rval); } /* * Find the precision of this particular machine */ #define MINSTEP 20e-9 /* minimum clock increment (s) */ #define MAXSTEP 1 /* maximum clock increment (s) */ #define MINCHANGES 12 /* minimum number of step samples */ #define MAXLOOPS ((int)(1. / MINSTEP)) /* avoid infinite loop */ /* * This routine measures the system precision defined as the minimum of * a sequence of differences between successive readings of the system * clock. However, if a difference is less than MINSTEP, the clock has * been read more than once during a clock tick and the difference is * ignored. We set MINSTEP greater than zero in case something happens * like a cache miss, and to tolerate underlying system clocks which * ensure each reading is strictly greater than prior readings while * using an underlying stepping (not interpolated) clock. * * sys_tick and sys_precision represent the time to read the clock for * systems with high-precision clocks, and the tick interval or step * size for lower-precision stepping clocks. * * This routine also measures the time to read the clock on stepping * system clocks by counting the number of readings between changes of * the underlying clock. With either type of clock, the minimum time * to read the clock is saved as sys_fuzz, and used to ensure the * get_systime() readings always increase and are fuzzed below sys_fuzz. */ void measure_precision(void) { /* * With sys_fuzz set to zero, get_systime() fuzzing of low bits * is effectively disabled. trunc_os_clock is FALSE to disable * get_ostime() simulation of a low-precision system clock. */ set_sys_fuzz(0.); trunc_os_clock = FALSE; measured_tick = measure_tick_fuzz(); set_sys_tick_precision(measured_tick); msyslog(LOG_INFO, "proto: precision = %.3f usec (%d)", sys_tick * 1e6, sys_precision); if (sys_fuzz < sys_tick) { msyslog(LOG_NOTICE, "proto: fuzz beneath %.3f usec", sys_fuzz * 1e6); } } /* * measure_tick_fuzz() * * measures the minimum time to read the clock (stored in sys_fuzz) * and returns the tick, the larger of the minimum increment observed * between successive clock readings and the time to read the clock. */ double measure_tick_fuzz(void) { l_fp minstep; /* MINSTEP as l_fp */ l_fp val; /* current seconds fraction */ l_fp last; /* last seconds fraction */ l_fp ldiff; /* val - last */ double tick; /* computed tick value */ double diff; long repeats; long max_repeats; int changes; int i; /* log2 precision */ tick = MAXSTEP; max_repeats = 0; repeats = 0; changes = 0; DTOLFP(MINSTEP, &minstep); get_systime(&last); for (i = 0; i < MAXLOOPS && changes < MINCHANGES; i++) { get_systime(&val); ldiff = val; L_SUB(&ldiff, &last); last = val; if (L_ISGT(&ldiff, &minstep)) { max_repeats = max(repeats, max_repeats); repeats = 0; changes++; LFPTOD(&ldiff, diff); tick = min(diff, tick); } else { repeats++; } } if (changes < MINCHANGES) { msyslog(LOG_ERR, "Fatal error: precision could not be measured (MINSTEP too large?)"); exit(1); } if (0 == max_repeats) { set_sys_fuzz(tick); } else { set_sys_fuzz(tick / max_repeats); } return tick; } void set_sys_tick_precision( double tick ) { int i; if (tick > 1.) { msyslog(LOG_ERR, "unsupported tick %.3f > 1s ignored", tick); return; } if (tick < measured_tick) { msyslog(LOG_ERR, "proto: tick %.3f less than measured tick %.3f, ignored", tick, measured_tick); return; } else if (tick > measured_tick) { trunc_os_clock = TRUE; msyslog(LOG_NOTICE, "proto: truncating system clock to multiples of %.9f", tick); } sys_tick = tick; /* * Find the nearest power of two. */ for (i = 0; tick <= 1; i--) tick *= 2; if (tick - 1 > 1 - tick / 2) i++; sys_precision = (s_char)i; } /* * init_proto - initialize the protocol module's data */ void init_proto(void) { l_fp dummy; int i; /* * Fill in the sys_* stuff. Default is don't listen to * broadcasting, require authentication. */ set_sys_leap(LEAP_NOTINSYNC); sys_stratum = STRATUM_UNSPEC; memcpy(&sys_refid, "INIT", 4); sys_peer = NULL; sys_rootdelay = 0; sys_rootdisp = 0; L_CLR(&sys_reftime); sys_jitter = 0; measure_precision(); get_systime(&dummy); sys_survivors = 0; sys_manycastserver = 0; sys_bclient = 0; sys_mclient = 0; sys_bdelay = BDELAY_DEFAULT; /*[Bug 3031] delay cutoff */ sys_authenticate = 1; sys_stattime = current_time; orphwait = current_time + sys_orphwait; proto_clr_stats(); for (i = 0; i < MAX_TTL; ++i) sys_ttl[i] = (u_char)((i * 256) / MAX_TTL); sys_ttlmax = (MAX_TTL - 1); hardpps_enable = 0; stats_control = 1; } /* * proto_config - configure the protocol module */ void proto_config( int item, u_long value, double dvalue, sockaddr_u *svalue ) { /* * Figure out what he wants to change, then do it */ DPRINTF(2, ("proto_config: code %d value %lu dvalue %lf\n", item, value, dvalue)); switch (item) { /* * enable and disable commands - arguments are Boolean. */ case PROTO_AUTHENTICATE: /* authentication (auth) */ sys_authenticate = value; break; case PROTO_BROADCLIENT: /* broadcast client (bclient) */ sys_bclient = (int)value; if (!sys_bclient) io_unsetbclient(); else io_setbclient(); break; #ifdef REFCLOCK case PROTO_CAL: /* refclock calibrate (calibrate) */ cal_enable = value; break; #endif /* REFCLOCK */ case PROTO_KERNEL: /* kernel discipline (kernel) */ select_loop(value); break; case PROTO_MONITOR: /* monitoring (monitor) */ if (value) mon_start(MON_ON); else { mon_stop(MON_ON); if (mon_enabled) msyslog(LOG_WARNING, "restrict: 'monitor' cannot be disabled while 'limited' is enabled"); } break; case PROTO_NTP: /* NTP discipline (ntp) */ ntp_enable = value; break; case PROTO_MODE7: /* mode7 management (ntpdc) */ ntp_mode7 = value; break; case PROTO_PPS: /* PPS discipline (pps) */ hardpps_enable = value; break; case PROTO_FILEGEN: /* statistics (stats) */ stats_control = value; break; /* * tos command - arguments are double, sometimes cast to int */ case PROTO_BCPOLLBSTEP: /* Broadcast Poll Backstep gate (bcpollbstep) */ sys_bcpollbstep = (u_char)dvalue; break; case PROTO_BEACON: /* manycast beacon (beacon) */ sys_beacon = (int)dvalue; break; case PROTO_BROADDELAY: /* default broadcast delay (bdelay) */ sys_bdelay = (dvalue ? dvalue : BDELAY_DEFAULT); break; case PROTO_CEILING: /* stratum ceiling (ceiling) */ sys_ceiling = (int)dvalue; break; case PROTO_COHORT: /* cohort switch (cohort) */ sys_cohort = (int)dvalue; break; case PROTO_FLOOR: /* stratum floor (floor) */ sys_floor = (int)dvalue; break; case PROTO_MAXCLOCK: /* maximum candidates (maxclock) */ sys_maxclock = (int)dvalue; break; case PROTO_MAXDIST: /* select threshold (maxdist) */ sys_maxdist = dvalue; break; case PROTO_CALLDELAY: /* modem call delay (mdelay) */ break; /* NOT USED */ case PROTO_MINCLOCK: /* minimum candidates (minclock) */ sys_minclock = (int)dvalue; break; case PROTO_MINDISP: /* minimum distance (mindist) */ sys_mindisp = dvalue; break; case PROTO_MINSANE: /* minimum survivors (minsane) */ sys_minsane = (int)dvalue; break; case PROTO_ORPHAN: /* orphan stratum (orphan) */ sys_orphan = (int)dvalue; break; case PROTO_ORPHWAIT: /* orphan wait (orphwait) */ orphwait -= sys_orphwait; sys_orphwait = (dvalue >= 1) ? (int)dvalue : NTP_ORPHWAIT; orphwait += sys_orphwait; break; /* * Miscellaneous commands */ case PROTO_MULTICAST_ADD: /* add group address */ if (svalue != NULL) io_multicast_add(svalue); sys_mclient = 1; break; case PROTO_MULTICAST_DEL: /* delete group address */ if (svalue != NULL) io_multicast_del(svalue); break; /* * Peer_clear Early policy choices */ case PROTO_PCEDIGEST: /* Digest */ peer_clear_digest_early = value; break; /* * Unpeer Early policy choices */ case PROTO_UECRYPTO: /* Crypto */ unpeer_crypto_early = value; break; case PROTO_UECRYPTONAK: /* Crypto_NAK */ unpeer_crypto_nak_early = value; break; case PROTO_UEDIGEST: /* Digest */ unpeer_digest_early = value; break; default: msyslog(LOG_NOTICE, "proto: unsupported option %d", item); } } /* * proto_clr_stats - clear protocol stat counters */ void proto_clr_stats(void) { sys_stattime = current_time; sys_received = 0; sys_processed = 0; sys_newversion = 0; sys_oldversion = 0; sys_declined = 0; sys_restricted = 0; sys_badlength = 0; sys_badauth = 0; sys_limitrejected = 0; sys_kodsent = 0; sys_lamport = 0; sys_tsrounding = 0; }