tcp_syncache.c revision 130555
186764Sjlemon/*- 292275Srwatson * Copyright (c) 2001 Networks Associates Technology, Inc. 386764Sjlemon * All rights reserved. 486764Sjlemon * 586764Sjlemon * This software was developed for the FreeBSD Project by Jonathan Lemon 686764Sjlemon * and NAI Labs, the Security Research Division of Network Associates, Inc. 786764Sjlemon * under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the 886764Sjlemon * DARPA CHATS research program. 986764Sjlemon * 1086764Sjlemon * Redistribution and use in source and binary forms, with or without 1186764Sjlemon * modification, are permitted provided that the following conditions 1286764Sjlemon * are met: 1386764Sjlemon * 1. Redistributions of source code must retain the above copyright 1486764Sjlemon * notice, this list of conditions and the following disclaimer. 1586764Sjlemon * 2. Redistributions in binary form must reproduce the above copyright 1686764Sjlemon * notice, this list of conditions and the following disclaimer in the 1786764Sjlemon * documentation and/or other materials provided with the distribution. 1886764Sjlemon * 3. The name of the author may not be used to endorse or promote 1986764Sjlemon * products derived from this software without specific prior written 2086764Sjlemon * permission. 2186764Sjlemon * 2286764Sjlemon * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 2386764Sjlemon * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 2486764Sjlemon * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 2586764Sjlemon * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 2686764Sjlemon * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 2786764Sjlemon * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 2886764Sjlemon * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 2986764Sjlemon * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 3086764Sjlemon * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 3186764Sjlemon * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 3286764Sjlemon * SUCH DAMAGE. 3386764Sjlemon * 3486764Sjlemon * $FreeBSD: head/sys/netinet/tcp_syncache.c 130555 2004-06-16 03:36:06Z rwatson $ 3586764Sjlemon */ 3686764Sjlemon 37125680Sbms#include "opt_inet.h" 3886764Sjlemon#include "opt_inet6.h" 3986764Sjlemon#include "opt_ipsec.h" 40101106Srwatson#include "opt_mac.h" 41118864Sharti#include "opt_tcpdebug.h" 4286764Sjlemon 4386764Sjlemon#include <sys/param.h> 4486764Sjlemon#include <sys/systm.h> 4586764Sjlemon#include <sys/kernel.h> 4686764Sjlemon#include <sys/sysctl.h> 4786764Sjlemon#include <sys/malloc.h> 48101106Srwatson#include <sys/mac.h> 4986764Sjlemon#include <sys/mbuf.h> 5086764Sjlemon#include <sys/md5.h> 5186764Sjlemon#include <sys/proc.h> /* for proc0 declaration */ 5286764Sjlemon#include <sys/random.h> 5386764Sjlemon#include <sys/socket.h> 5486764Sjlemon#include <sys/socketvar.h> 5586764Sjlemon 5686764Sjlemon#include <net/if.h> 5786764Sjlemon#include <net/route.h> 5886764Sjlemon 5986764Sjlemon#include <netinet/in.h> 6086764Sjlemon#include <netinet/in_systm.h> 6186764Sjlemon#include <netinet/ip.h> 6286764Sjlemon#include <netinet/in_var.h> 6386764Sjlemon#include <netinet/in_pcb.h> 6486764Sjlemon#include <netinet/ip_var.h> 6586764Sjlemon#ifdef INET6 6686764Sjlemon#include <netinet/ip6.h> 6786764Sjlemon#include <netinet/icmp6.h> 6886764Sjlemon#include <netinet6/nd6.h> 6986764Sjlemon#include <netinet6/ip6_var.h> 7086764Sjlemon#include <netinet6/in6_pcb.h> 7186764Sjlemon#endif 7286764Sjlemon#include <netinet/tcp.h> 73118864Sharti#ifdef TCPDEBUG 74118864Sharti#include <netinet/tcpip.h> 75118864Sharti#endif 7686764Sjlemon#include <netinet/tcp_fsm.h> 7786764Sjlemon#include <netinet/tcp_seq.h> 7886764Sjlemon#include <netinet/tcp_timer.h> 7986764Sjlemon#include <netinet/tcp_var.h> 80118864Sharti#ifdef TCPDEBUG 81118864Sharti#include <netinet/tcp_debug.h> 82118864Sharti#endif 8386764Sjlemon#ifdef INET6 8486764Sjlemon#include <netinet6/tcp6_var.h> 8586764Sjlemon#endif 8686764Sjlemon 8786764Sjlemon#ifdef IPSEC 8886764Sjlemon#include <netinet6/ipsec.h> 8986764Sjlemon#ifdef INET6 9086764Sjlemon#include <netinet6/ipsec6.h> 9186764Sjlemon#endif 9286764Sjlemon#endif /*IPSEC*/ 9386764Sjlemon 94105199Ssam#ifdef FAST_IPSEC 95105199Ssam#include <netipsec/ipsec.h> 96105199Ssam#ifdef INET6 97105199Ssam#include <netipsec/ipsec6.h> 98105199Ssam#endif 99105199Ssam#include <netipsec/key.h> 100105199Ssam#endif /*FAST_IPSEC*/ 101105199Ssam 10286764Sjlemon#include <machine/in_cksum.h> 10392760Sjeff#include <vm/uma.h> 10486764Sjlemon 10588180Sjlemonstatic int tcp_syncookies = 1; 10688180SjlemonSYSCTL_INT(_net_inet_tcp, OID_AUTO, syncookies, CTLFLAG_RW, 10788180Sjlemon &tcp_syncookies, 0, 10888180Sjlemon "Use TCP SYN cookies if the syncache overflows"); 10988180Sjlemon 11086764Sjlemonstatic void syncache_drop(struct syncache *, struct syncache_head *); 11186764Sjlemonstatic void syncache_free(struct syncache *); 11288180Sjlemonstatic void syncache_insert(struct syncache *, struct syncache_head *); 11386764Sjlemonstruct syncache *syncache_lookup(struct in_conninfo *, struct syncache_head **); 114118864Sharti#ifdef TCPDEBUG 115118864Shartistatic int syncache_respond(struct syncache *, struct mbuf *, struct socket *); 116118864Sharti#else 11786764Sjlemonstatic int syncache_respond(struct syncache *, struct mbuf *); 118118864Sharti#endif 11996602Srwatsonstatic struct socket *syncache_socket(struct syncache *, struct socket *, 12096602Srwatson struct mbuf *m); 12186764Sjlemonstatic void syncache_timer(void *); 12288180Sjlemonstatic u_int32_t syncookie_generate(struct syncache *); 12388180Sjlemonstatic struct syncache *syncookie_lookup(struct in_conninfo *, 12488180Sjlemon struct tcphdr *, struct socket *); 12586764Sjlemon 12686764Sjlemon/* 12786764Sjlemon * Transmit the SYN,ACK fewer times than TCP_MAXRXTSHIFT specifies. 12886764Sjlemon * 3 retransmits corresponds to a timeout of (1 + 2 + 4 + 8 == 15) seconds, 12986764Sjlemon * the odds are that the user has given up attempting to connect by then. 13086764Sjlemon */ 13186764Sjlemon#define SYNCACHE_MAXREXMTS 3 13286764Sjlemon 13386764Sjlemon/* Arbitrary values */ 13486764Sjlemon#define TCP_SYNCACHE_HASHSIZE 512 13586764Sjlemon#define TCP_SYNCACHE_BUCKETLIMIT 30 13686764Sjlemon 13786764Sjlemonstruct tcp_syncache { 13886764Sjlemon struct syncache_head *hashbase; 13992760Sjeff uma_zone_t zone; 14086764Sjlemon u_int hashsize; 14186764Sjlemon u_int hashmask; 14286764Sjlemon u_int bucket_limit; 14386764Sjlemon u_int cache_count; 14486764Sjlemon u_int cache_limit; 14586764Sjlemon u_int rexmt_limit; 14686764Sjlemon u_int hash_secret; 14786764Sjlemon TAILQ_HEAD(, syncache) timerq[SYNCACHE_MAXREXMTS + 1]; 14886764Sjlemon struct callout tt_timerq[SYNCACHE_MAXREXMTS + 1]; 14986764Sjlemon}; 15086764Sjlemonstatic struct tcp_syncache tcp_syncache; 15186764Sjlemon 15286764SjlemonSYSCTL_NODE(_net_inet_tcp, OID_AUTO, syncache, CTLFLAG_RW, 0, "TCP SYN cache"); 15386764Sjlemon 154121307SsilbySYSCTL_INT(_net_inet_tcp_syncache, OID_AUTO, bucketlimit, CTLFLAG_RDTUN, 15586764Sjlemon &tcp_syncache.bucket_limit, 0, "Per-bucket hash limit for syncache"); 15686764Sjlemon 157121307SsilbySYSCTL_INT(_net_inet_tcp_syncache, OID_AUTO, cachelimit, CTLFLAG_RDTUN, 15886764Sjlemon &tcp_syncache.cache_limit, 0, "Overall entry limit for syncache"); 15986764Sjlemon 16086764SjlemonSYSCTL_INT(_net_inet_tcp_syncache, OID_AUTO, count, CTLFLAG_RD, 16186764Sjlemon &tcp_syncache.cache_count, 0, "Current number of entries in syncache"); 16286764Sjlemon 163121307SsilbySYSCTL_INT(_net_inet_tcp_syncache, OID_AUTO, hashsize, CTLFLAG_RDTUN, 16486764Sjlemon &tcp_syncache.hashsize, 0, "Size of TCP syncache hashtable"); 16586764Sjlemon 16686764SjlemonSYSCTL_INT(_net_inet_tcp_syncache, OID_AUTO, rexmtlimit, CTLFLAG_RW, 16786764Sjlemon &tcp_syncache.rexmt_limit, 0, "Limit on SYN/ACK retransmissions"); 16886764Sjlemon 16986764Sjlemonstatic MALLOC_DEFINE(M_SYNCACHE, "syncache", "TCP syncache"); 17086764Sjlemon 17186764Sjlemon#define SYNCACHE_HASH(inc, mask) \ 17286764Sjlemon ((tcp_syncache.hash_secret ^ \ 17386764Sjlemon (inc)->inc_faddr.s_addr ^ \ 17486764Sjlemon ((inc)->inc_faddr.s_addr >> 16) ^ \ 17586764Sjlemon (inc)->inc_fport ^ (inc)->inc_lport) & mask) 17686764Sjlemon 17786764Sjlemon#define SYNCACHE_HASH6(inc, mask) \ 17886764Sjlemon ((tcp_syncache.hash_secret ^ \ 17986764Sjlemon (inc)->inc6_faddr.s6_addr32[0] ^ \ 18086764Sjlemon (inc)->inc6_faddr.s6_addr32[3] ^ \ 18186764Sjlemon (inc)->inc_fport ^ (inc)->inc_lport) & mask) 18286764Sjlemon 18386764Sjlemon#define ENDPTS_EQ(a, b) ( \ 18489667Sjlemon (a)->ie_fport == (b)->ie_fport && \ 18586764Sjlemon (a)->ie_lport == (b)->ie_lport && \ 18686764Sjlemon (a)->ie_faddr.s_addr == (b)->ie_faddr.s_addr && \ 18786764Sjlemon (a)->ie_laddr.s_addr == (b)->ie_laddr.s_addr \ 18886764Sjlemon) 18986764Sjlemon 19086764Sjlemon#define ENDPTS6_EQ(a, b) (memcmp(a, b, sizeof(*a)) == 0) 19186764Sjlemon 192106696Salfred#define SYNCACHE_TIMEOUT(sc, slot) do { \ 193106696Salfred sc->sc_rxtslot = (slot); \ 194106696Salfred sc->sc_rxttime = ticks + TCPTV_RTOBASE * tcp_backoff[(slot)]; \ 195106696Salfred TAILQ_INSERT_TAIL(&tcp_syncache.timerq[(slot)], sc, sc_timerq); \ 196106696Salfred if (!callout_active(&tcp_syncache.tt_timerq[(slot)])) \ 197106696Salfred callout_reset(&tcp_syncache.tt_timerq[(slot)], \ 198106696Salfred TCPTV_RTOBASE * tcp_backoff[(slot)], \ 199106696Salfred syncache_timer, (void *)((intptr_t)(slot))); \ 20086764Sjlemon} while (0) 20186764Sjlemon 20286764Sjlemonstatic void 20386764Sjlemonsyncache_free(struct syncache *sc) 20486764Sjlemon{ 20586764Sjlemon if (sc->sc_ipopts) 20686764Sjlemon (void) m_free(sc->sc_ipopts); 207122922Sandre 20892760Sjeff uma_zfree(tcp_syncache.zone, sc); 20986764Sjlemon} 21086764Sjlemon 21186764Sjlemonvoid 21286764Sjlemonsyncache_init(void) 21386764Sjlemon{ 21486764Sjlemon int i; 21586764Sjlemon 21686764Sjlemon tcp_syncache.cache_count = 0; 21786764Sjlemon tcp_syncache.hashsize = TCP_SYNCACHE_HASHSIZE; 21886764Sjlemon tcp_syncache.bucket_limit = TCP_SYNCACHE_BUCKETLIMIT; 21986764Sjlemon tcp_syncache.cache_limit = 22086764Sjlemon tcp_syncache.hashsize * tcp_syncache.bucket_limit; 22186764Sjlemon tcp_syncache.rexmt_limit = SYNCACHE_MAXREXMTS; 22286764Sjlemon tcp_syncache.hash_secret = arc4random(); 22386764Sjlemon 22486764Sjlemon TUNABLE_INT_FETCH("net.inet.tcp.syncache.hashsize", 22586764Sjlemon &tcp_syncache.hashsize); 22686764Sjlemon TUNABLE_INT_FETCH("net.inet.tcp.syncache.cachelimit", 22786764Sjlemon &tcp_syncache.cache_limit); 22886764Sjlemon TUNABLE_INT_FETCH("net.inet.tcp.syncache.bucketlimit", 22986764Sjlemon &tcp_syncache.bucket_limit); 23086764Sjlemon if (!powerof2(tcp_syncache.hashsize)) { 23186764Sjlemon printf("WARNING: syncache hash size is not a power of 2.\n"); 23286764Sjlemon tcp_syncache.hashsize = 512; /* safe default */ 23386764Sjlemon } 23486764Sjlemon tcp_syncache.hashmask = tcp_syncache.hashsize - 1; 23586764Sjlemon 23686764Sjlemon /* Allocate the hash table. */ 23786764Sjlemon MALLOC(tcp_syncache.hashbase, struct syncache_head *, 23886764Sjlemon tcp_syncache.hashsize * sizeof(struct syncache_head), 239111119Simp M_SYNCACHE, M_WAITOK); 24086764Sjlemon 24186764Sjlemon /* Initialize the hash buckets. */ 24286764Sjlemon for (i = 0; i < tcp_syncache.hashsize; i++) { 24386764Sjlemon TAILQ_INIT(&tcp_syncache.hashbase[i].sch_bucket); 24486764Sjlemon tcp_syncache.hashbase[i].sch_length = 0; 24586764Sjlemon } 24686764Sjlemon 24786764Sjlemon /* Initialize the timer queues. */ 24886814Sbde for (i = 0; i <= SYNCACHE_MAXREXMTS; i++) { 24986764Sjlemon TAILQ_INIT(&tcp_syncache.timerq[i]); 250122449Ssam callout_init(&tcp_syncache.tt_timerq[i], 251122449Ssam debug_mpsafenet ? CALLOUT_MPSAFE : 0); 25286764Sjlemon } 25386764Sjlemon 25486764Sjlemon /* 25586764Sjlemon * Allocate the syncache entries. Allow the zone to allocate one 25686764Sjlemon * more entry than cache limit, so a new entry can bump out an 25786764Sjlemon * older one. 25886764Sjlemon */ 25992760Sjeff tcp_syncache.zone = uma_zcreate("syncache", sizeof(struct syncache), 26092760Sjeff NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 26192760Sjeff uma_zone_set_max(tcp_syncache.zone, tcp_syncache.cache_limit); 262124848Sandre tcp_syncache.cache_limit -= 1; 26386764Sjlemon} 26486764Sjlemon 26588180Sjlemonstatic void 26686764Sjlemonsyncache_insert(sc, sch) 26786764Sjlemon struct syncache *sc; 26886764Sjlemon struct syncache_head *sch; 26986764Sjlemon{ 27086764Sjlemon struct syncache *sc2; 271122496Ssam int i; 27286764Sjlemon 273122496Ssam INP_INFO_WLOCK_ASSERT(&tcbinfo); 274122496Ssam 27586764Sjlemon /* 27686764Sjlemon * Make sure that we don't overflow the per-bucket 27786764Sjlemon * limit or the total cache size limit. 27886764Sjlemon */ 27986764Sjlemon if (sch->sch_length >= tcp_syncache.bucket_limit) { 28086764Sjlemon /* 28186764Sjlemon * The bucket is full, toss the oldest element. 28286764Sjlemon */ 28386764Sjlemon sc2 = TAILQ_FIRST(&sch->sch_bucket); 28488180Sjlemon sc2->sc_tp->ts_recent = ticks; 28586764Sjlemon syncache_drop(sc2, sch); 28686764Sjlemon tcpstat.tcps_sc_bucketoverflow++; 28786764Sjlemon } else if (tcp_syncache.cache_count >= tcp_syncache.cache_limit) { 28886764Sjlemon /* 28986764Sjlemon * The cache is full. Toss the oldest entry in the 29086764Sjlemon * entire cache. This is the front entry in the 29186764Sjlemon * first non-empty timer queue with the largest 29286764Sjlemon * timeout value. 29386764Sjlemon */ 29486764Sjlemon for (i = SYNCACHE_MAXREXMTS; i >= 0; i--) { 29586764Sjlemon sc2 = TAILQ_FIRST(&tcp_syncache.timerq[i]); 29686764Sjlemon if (sc2 != NULL) 29786764Sjlemon break; 29886764Sjlemon } 29988180Sjlemon sc2->sc_tp->ts_recent = ticks; 30086764Sjlemon syncache_drop(sc2, NULL); 30186764Sjlemon tcpstat.tcps_sc_cacheoverflow++; 30286764Sjlemon } 30386764Sjlemon 30486764Sjlemon /* Initialize the entry's timer. */ 30586764Sjlemon SYNCACHE_TIMEOUT(sc, 0); 30686764Sjlemon 30786764Sjlemon /* Put it into the bucket. */ 30886764Sjlemon TAILQ_INSERT_TAIL(&sch->sch_bucket, sc, sc_hash); 30986764Sjlemon sch->sch_length++; 31086764Sjlemon tcp_syncache.cache_count++; 31186764Sjlemon tcpstat.tcps_sc_added++; 31286764Sjlemon} 31386764Sjlemon 31486764Sjlemonstatic void 31586764Sjlemonsyncache_drop(sc, sch) 31686764Sjlemon struct syncache *sc; 31786764Sjlemon struct syncache_head *sch; 31886764Sjlemon{ 319122496Ssam INP_INFO_WLOCK_ASSERT(&tcbinfo); 32086764Sjlemon 32186764Sjlemon if (sch == NULL) { 32286764Sjlemon#ifdef INET6 32386764Sjlemon if (sc->sc_inc.inc_isipv6) { 32486764Sjlemon sch = &tcp_syncache.hashbase[ 32586764Sjlemon SYNCACHE_HASH6(&sc->sc_inc, tcp_syncache.hashmask)]; 32686764Sjlemon } else 32786764Sjlemon#endif 32886764Sjlemon { 32986764Sjlemon sch = &tcp_syncache.hashbase[ 33086764Sjlemon SYNCACHE_HASH(&sc->sc_inc, tcp_syncache.hashmask)]; 33186764Sjlemon } 33286764Sjlemon } 33386764Sjlemon 33486764Sjlemon TAILQ_REMOVE(&sch->sch_bucket, sc, sc_hash); 33586764Sjlemon sch->sch_length--; 33686764Sjlemon tcp_syncache.cache_count--; 33786764Sjlemon 33886764Sjlemon TAILQ_REMOVE(&tcp_syncache.timerq[sc->sc_rxtslot], sc, sc_timerq); 33986764Sjlemon if (TAILQ_EMPTY(&tcp_syncache.timerq[sc->sc_rxtslot])) 34086764Sjlemon callout_stop(&tcp_syncache.tt_timerq[sc->sc_rxtslot]); 34186764Sjlemon 34286764Sjlemon syncache_free(sc); 34386764Sjlemon} 34486764Sjlemon 34586764Sjlemon/* 34686764Sjlemon * Walk the timer queues, looking for SYN,ACKs that need to be retransmitted. 34786764Sjlemon * If we have retransmitted an entry the maximum number of times, expire it. 34886764Sjlemon */ 34986764Sjlemonstatic void 35086764Sjlemonsyncache_timer(xslot) 35186764Sjlemon void *xslot; 35286764Sjlemon{ 35388195Sjlemon intptr_t slot = (intptr_t)xslot; 35486764Sjlemon struct syncache *sc, *nsc; 35586764Sjlemon struct inpcb *inp; 35686764Sjlemon 357110737Shsu INP_INFO_WLOCK(&tcbinfo); 35886764Sjlemon if (callout_pending(&tcp_syncache.tt_timerq[slot]) || 35986764Sjlemon !callout_active(&tcp_syncache.tt_timerq[slot])) { 360122496Ssam /* XXX can this happen? */ 361122501Ssam INP_INFO_WUNLOCK(&tcbinfo); 36286764Sjlemon return; 36386764Sjlemon } 36486764Sjlemon callout_deactivate(&tcp_syncache.tt_timerq[slot]); 36586764Sjlemon 36686764Sjlemon nsc = TAILQ_FIRST(&tcp_syncache.timerq[slot]); 36786764Sjlemon while (nsc != NULL) { 36886764Sjlemon if (ticks < nsc->sc_rxttime) 36986764Sjlemon break; 37086764Sjlemon sc = nsc; 37186764Sjlemon inp = sc->sc_tp->t_inpcb; 37286764Sjlemon if (slot == SYNCACHE_MAXREXMTS || 37386764Sjlemon slot >= tcp_syncache.rexmt_limit || 374108703Shsu inp == NULL || inp->inp_gencnt != sc->sc_inp_gencnt) { 37598982Sjlemon nsc = TAILQ_NEXT(sc, sc_timerq); 37686764Sjlemon syncache_drop(sc, NULL); 37786764Sjlemon tcpstat.tcps_sc_stale++; 37886764Sjlemon continue; 37986764Sjlemon } 38098982Sjlemon /* 38198982Sjlemon * syncache_respond() may call back into the syncache to 38298982Sjlemon * to modify another entry, so do not obtain the next 38398982Sjlemon * entry on the timer chain until it has completed. 38498982Sjlemon */ 385118864Sharti#ifdef TCPDEBUG 386118864Sharti (void) syncache_respond(sc, NULL, NULL); 387118864Sharti#else 38886764Sjlemon (void) syncache_respond(sc, NULL); 389118864Sharti#endif 39098982Sjlemon nsc = TAILQ_NEXT(sc, sc_timerq); 39186764Sjlemon tcpstat.tcps_sc_retransmitted++; 39286764Sjlemon TAILQ_REMOVE(&tcp_syncache.timerq[slot], sc, sc_timerq); 39386764Sjlemon SYNCACHE_TIMEOUT(sc, slot + 1); 39486764Sjlemon } 39586764Sjlemon if (nsc != NULL) 39686764Sjlemon callout_reset(&tcp_syncache.tt_timerq[slot], 39786764Sjlemon nsc->sc_rxttime - ticks, syncache_timer, (void *)(slot)); 398122501Ssam INP_INFO_WUNLOCK(&tcbinfo); 39986764Sjlemon} 40086764Sjlemon 40186764Sjlemon/* 40286764Sjlemon * Find an entry in the syncache. 40386764Sjlemon */ 40486764Sjlemonstruct syncache * 40586764Sjlemonsyncache_lookup(inc, schp) 40686764Sjlemon struct in_conninfo *inc; 40786764Sjlemon struct syncache_head **schp; 40886764Sjlemon{ 40986764Sjlemon struct syncache *sc; 41086764Sjlemon struct syncache_head *sch; 41186764Sjlemon 412122496Ssam INP_INFO_WLOCK_ASSERT(&tcbinfo); 413122496Ssam 41486764Sjlemon#ifdef INET6 41586764Sjlemon if (inc->inc_isipv6) { 41686764Sjlemon sch = &tcp_syncache.hashbase[ 41786764Sjlemon SYNCACHE_HASH6(inc, tcp_syncache.hashmask)]; 41886764Sjlemon *schp = sch; 41986764Sjlemon TAILQ_FOREACH(sc, &sch->sch_bucket, sc_hash) { 420122496Ssam if (ENDPTS6_EQ(&inc->inc_ie, &sc->sc_inc.inc_ie)) 42186764Sjlemon return (sc); 42286764Sjlemon } 42386764Sjlemon } else 42486764Sjlemon#endif 42586764Sjlemon { 42686764Sjlemon sch = &tcp_syncache.hashbase[ 42786764Sjlemon SYNCACHE_HASH(inc, tcp_syncache.hashmask)]; 42886764Sjlemon *schp = sch; 42986764Sjlemon TAILQ_FOREACH(sc, &sch->sch_bucket, sc_hash) { 43086764Sjlemon#ifdef INET6 43186764Sjlemon if (sc->sc_inc.inc_isipv6) 43286764Sjlemon continue; 43386764Sjlemon#endif 434122496Ssam if (ENDPTS_EQ(&inc->inc_ie, &sc->sc_inc.inc_ie)) 43586764Sjlemon return (sc); 43686764Sjlemon } 43786764Sjlemon } 43886764Sjlemon return (NULL); 43986764Sjlemon} 44086764Sjlemon 44186764Sjlemon/* 44286764Sjlemon * This function is called when we get a RST for a 44386764Sjlemon * non-existent connection, so that we can see if the 44486764Sjlemon * connection is in the syn cache. If it is, zap it. 44586764Sjlemon */ 44686764Sjlemonvoid 44786764Sjlemonsyncache_chkrst(inc, th) 44886764Sjlemon struct in_conninfo *inc; 44986764Sjlemon struct tcphdr *th; 45086764Sjlemon{ 45186764Sjlemon struct syncache *sc; 45286764Sjlemon struct syncache_head *sch; 45386764Sjlemon 454122496Ssam INP_INFO_WLOCK_ASSERT(&tcbinfo); 455122496Ssam 45686764Sjlemon sc = syncache_lookup(inc, &sch); 45786764Sjlemon if (sc == NULL) 45886764Sjlemon return; 45986764Sjlemon /* 46086764Sjlemon * If the RST bit is set, check the sequence number to see 46186764Sjlemon * if this is a valid reset segment. 46286764Sjlemon * RFC 793 page 37: 46386764Sjlemon * In all states except SYN-SENT, all reset (RST) segments 46486764Sjlemon * are validated by checking their SEQ-fields. A reset is 46586764Sjlemon * valid if its sequence number is in the window. 46686764Sjlemon * 46786764Sjlemon * The sequence number in the reset segment is normally an 46886764Sjlemon * echo of our outgoing acknowlegement numbers, but some hosts 46986764Sjlemon * send a reset with the sequence number at the rightmost edge 47086764Sjlemon * of our receive window, and we have to handle this case. 47186764Sjlemon */ 47286764Sjlemon if (SEQ_GEQ(th->th_seq, sc->sc_irs) && 47386764Sjlemon SEQ_LEQ(th->th_seq, sc->sc_irs + sc->sc_wnd)) { 47486764Sjlemon syncache_drop(sc, sch); 47586764Sjlemon tcpstat.tcps_sc_reset++; 47686764Sjlemon } 47786764Sjlemon} 47886764Sjlemon 47986764Sjlemonvoid 48086764Sjlemonsyncache_badack(inc) 48186764Sjlemon struct in_conninfo *inc; 48286764Sjlemon{ 48386764Sjlemon struct syncache *sc; 48486764Sjlemon struct syncache_head *sch; 48586764Sjlemon 486122496Ssam INP_INFO_WLOCK_ASSERT(&tcbinfo); 487122496Ssam 48886764Sjlemon sc = syncache_lookup(inc, &sch); 48986764Sjlemon if (sc != NULL) { 49086764Sjlemon syncache_drop(sc, sch); 49186764Sjlemon tcpstat.tcps_sc_badack++; 49286764Sjlemon } 49386764Sjlemon} 49486764Sjlemon 49586764Sjlemonvoid 49686764Sjlemonsyncache_unreach(inc, th) 49786764Sjlemon struct in_conninfo *inc; 49886764Sjlemon struct tcphdr *th; 49986764Sjlemon{ 50086764Sjlemon struct syncache *sc; 50186764Sjlemon struct syncache_head *sch; 50286764Sjlemon 503122496Ssam INP_INFO_WLOCK_ASSERT(&tcbinfo); 504122496Ssam 50586764Sjlemon /* we are called at splnet() here */ 50686764Sjlemon sc = syncache_lookup(inc, &sch); 50786764Sjlemon if (sc == NULL) 50886764Sjlemon return; 50986764Sjlemon 51086764Sjlemon /* If the sequence number != sc_iss, then it's a bogus ICMP msg */ 51186764Sjlemon if (ntohl(th->th_seq) != sc->sc_iss) 51286764Sjlemon return; 51386764Sjlemon 51486764Sjlemon /* 51586764Sjlemon * If we've rertransmitted 3 times and this is our second error, 51686764Sjlemon * we remove the entry. Otherwise, we allow it to continue on. 51786764Sjlemon * This prevents us from incorrectly nuking an entry during a 51886764Sjlemon * spurious network outage. 51986764Sjlemon * 52086764Sjlemon * See tcp_notify(). 52186764Sjlemon */ 52286764Sjlemon if ((sc->sc_flags & SCF_UNREACH) == 0 || sc->sc_rxtslot < 3) { 52386764Sjlemon sc->sc_flags |= SCF_UNREACH; 52486764Sjlemon return; 52586764Sjlemon } 52686764Sjlemon syncache_drop(sc, sch); 52786764Sjlemon tcpstat.tcps_sc_unreach++; 52886764Sjlemon} 52986764Sjlemon 53086764Sjlemon/* 53186764Sjlemon * Build a new TCP socket structure from a syncache entry. 53286764Sjlemon */ 53386764Sjlemonstatic struct socket * 53496602Srwatsonsyncache_socket(sc, lso, m) 53586764Sjlemon struct syncache *sc; 53686764Sjlemon struct socket *lso; 53796602Srwatson struct mbuf *m; 53886764Sjlemon{ 53986764Sjlemon struct inpcb *inp = NULL; 54086764Sjlemon struct socket *so; 54186764Sjlemon struct tcpcb *tp; 54286764Sjlemon 543130555Srwatson NET_ASSERT_GIANT(); 544122496Ssam INP_INFO_WLOCK_ASSERT(&tcbinfo); 545122496Ssam 54686764Sjlemon /* 54786764Sjlemon * Ok, create the full blown connection, and set things up 54886764Sjlemon * as they would have been set up if we had created the 54986764Sjlemon * connection when the SYN arrived. If we can't create 55086764Sjlemon * the connection, abort it. 55186764Sjlemon */ 55286764Sjlemon so = sonewconn(lso, SS_ISCONNECTED); 55386764Sjlemon if (so == NULL) { 55486764Sjlemon /* 55586764Sjlemon * Drop the connection; we will send a RST if the peer 55686764Sjlemon * retransmits the ACK, 55786764Sjlemon */ 55886764Sjlemon tcpstat.tcps_listendrop++; 559122496Ssam goto abort2; 56086764Sjlemon } 561101106Srwatson#ifdef MAC 562130398Srwatson SOCK_LOCK(so); 563101106Srwatson mac_set_socket_peer_from_mbuf(m, so); 564130398Srwatson SOCK_UNLOCK(so); 565101106Srwatson#endif 56686764Sjlemon 56786764Sjlemon inp = sotoinpcb(so); 568122496Ssam INP_LOCK(inp); 56986764Sjlemon 57086764Sjlemon /* 57186764Sjlemon * Insert new socket into hash list. 57286764Sjlemon */ 57391492Sume inp->inp_inc.inc_isipv6 = sc->sc_inc.inc_isipv6; 57486764Sjlemon#ifdef INET6 57586764Sjlemon if (sc->sc_inc.inc_isipv6) { 57686764Sjlemon inp->in6p_laddr = sc->sc_inc.inc6_laddr; 57786764Sjlemon } else { 57886764Sjlemon inp->inp_vflag &= ~INP_IPV6; 57986764Sjlemon inp->inp_vflag |= INP_IPV4; 58086764Sjlemon#endif 58186764Sjlemon inp->inp_laddr = sc->sc_inc.inc_laddr; 58286764Sjlemon#ifdef INET6 58386764Sjlemon } 58486764Sjlemon#endif 58586764Sjlemon inp->inp_lport = sc->sc_inc.inc_lport; 58686764Sjlemon if (in_pcbinshash(inp) != 0) { 58786764Sjlemon /* 58886764Sjlemon * Undo the assignments above if we failed to 58986764Sjlemon * put the PCB on the hash lists. 59086764Sjlemon */ 59186764Sjlemon#ifdef INET6 59286764Sjlemon if (sc->sc_inc.inc_isipv6) 59386764Sjlemon inp->in6p_laddr = in6addr_any; 59486764Sjlemon else 59586764Sjlemon#endif 59686764Sjlemon inp->inp_laddr.s_addr = INADDR_ANY; 59786764Sjlemon inp->inp_lport = 0; 59886764Sjlemon goto abort; 59986764Sjlemon } 60086764Sjlemon#ifdef IPSEC 60186764Sjlemon /* copy old policy into new socket's */ 602122062Sume if (ipsec_copy_pcbpolicy(sotoinpcb(lso)->inp_sp, inp->inp_sp)) 603122062Sume printf("syncache_expand: could not copy policy\n"); 604122062Sume#endif 605122062Sume#ifdef FAST_IPSEC 606122062Sume /* copy old policy into new socket's */ 60786764Sjlemon if (ipsec_copy_policy(sotoinpcb(lso)->inp_sp, inp->inp_sp)) 60886764Sjlemon printf("syncache_expand: could not copy policy\n"); 60986764Sjlemon#endif 61086764Sjlemon#ifdef INET6 61186764Sjlemon if (sc->sc_inc.inc_isipv6) { 61286764Sjlemon struct inpcb *oinp = sotoinpcb(lso); 61386764Sjlemon struct in6_addr laddr6; 614124847Sandre struct sockaddr_in6 sin6; 61586764Sjlemon /* 61686764Sjlemon * Inherit socket options from the listening socket. 61786764Sjlemon * Note that in6p_inputopts are not (and should not be) 61886764Sjlemon * copied, since it stores previously received options and is 61986764Sjlemon * used to detect if each new option is different than the 62086764Sjlemon * previous one and hence should be passed to a user. 62186764Sjlemon * If we copied in6p_inputopts, a user would not be able to 62286764Sjlemon * receive options just after calling the accept system call. 62386764Sjlemon */ 62486764Sjlemon inp->inp_flags |= oinp->inp_flags & INP_CONTROLOPTS; 62586764Sjlemon if (oinp->in6p_outputopts) 62686764Sjlemon inp->in6p_outputopts = 62786764Sjlemon ip6_copypktopts(oinp->in6p_outputopts, M_NOWAIT); 62886764Sjlemon 629124847Sandre sin6.sin6_family = AF_INET6; 630124847Sandre sin6.sin6_len = sizeof(sin6); 631124847Sandre sin6.sin6_addr = sc->sc_inc.inc6_faddr; 632124847Sandre sin6.sin6_port = sc->sc_inc.inc_fport; 633124847Sandre sin6.sin6_flowinfo = sin6.sin6_scope_id = 0; 63486764Sjlemon laddr6 = inp->in6p_laddr; 63586764Sjlemon if (IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_laddr)) 63686764Sjlemon inp->in6p_laddr = sc->sc_inc.inc6_laddr; 637127505Spjd if (in6_pcbconnect(inp, (struct sockaddr *)&sin6, 638127505Spjd thread0.td_ucred)) { 63986764Sjlemon inp->in6p_laddr = laddr6; 64086764Sjlemon goto abort; 64186764Sjlemon } 64286764Sjlemon } else 64386764Sjlemon#endif 64486764Sjlemon { 64586764Sjlemon struct in_addr laddr; 646124847Sandre struct sockaddr_in sin; 64786764Sjlemon 64886764Sjlemon inp->inp_options = ip_srcroute(); 64986764Sjlemon if (inp->inp_options == NULL) { 65086764Sjlemon inp->inp_options = sc->sc_ipopts; 65186764Sjlemon sc->sc_ipopts = NULL; 65286764Sjlemon } 65386764Sjlemon 654124847Sandre sin.sin_family = AF_INET; 655124847Sandre sin.sin_len = sizeof(sin); 656124847Sandre sin.sin_addr = sc->sc_inc.inc_faddr; 657124847Sandre sin.sin_port = sc->sc_inc.inc_fport; 658124847Sandre bzero((caddr_t)sin.sin_zero, sizeof(sin.sin_zero)); 65986764Sjlemon laddr = inp->inp_laddr; 66086764Sjlemon if (inp->inp_laddr.s_addr == INADDR_ANY) 66186764Sjlemon inp->inp_laddr = sc->sc_inc.inc_laddr; 662127505Spjd if (in_pcbconnect(inp, (struct sockaddr *)&sin, 663127505Spjd thread0.td_ucred)) { 66486764Sjlemon inp->inp_laddr = laddr; 66586764Sjlemon goto abort; 66686764Sjlemon } 66786764Sjlemon } 66886764Sjlemon 66986764Sjlemon tp = intotcpcb(inp); 67086764Sjlemon tp->t_state = TCPS_SYN_RECEIVED; 67186764Sjlemon tp->iss = sc->sc_iss; 67286764Sjlemon tp->irs = sc->sc_irs; 67386764Sjlemon tcp_rcvseqinit(tp); 67486764Sjlemon tcp_sendseqinit(tp); 67586764Sjlemon tp->snd_wl1 = sc->sc_irs; 67686764Sjlemon tp->rcv_up = sc->sc_irs + 1; 67786764Sjlemon tp->rcv_wnd = sc->sc_wnd; 67886764Sjlemon tp->rcv_adv += tp->rcv_wnd; 67986764Sjlemon 68090982Sjlemon tp->t_flags = sototcpcb(lso)->t_flags & (TF_NOPUSH|TF_NODELAY); 68186764Sjlemon if (sc->sc_flags & SCF_NOOPT) 68286764Sjlemon tp->t_flags |= TF_NOOPT; 68386764Sjlemon if (sc->sc_flags & SCF_WINSCALE) { 68486764Sjlemon tp->t_flags |= TF_REQ_SCALE|TF_RCVD_SCALE; 68586764Sjlemon tp->requested_s_scale = sc->sc_requested_s_scale; 68686764Sjlemon tp->request_r_scale = sc->sc_request_r_scale; 68786764Sjlemon } 68886764Sjlemon if (sc->sc_flags & SCF_TIMESTAMP) { 68986764Sjlemon tp->t_flags |= TF_REQ_TSTMP|TF_RCVD_TSTMP; 69086764Sjlemon tp->ts_recent = sc->sc_tsrecent; 69186764Sjlemon tp->ts_recent_age = ticks; 69286764Sjlemon } 69386764Sjlemon if (sc->sc_flags & SCF_CC) { 69486764Sjlemon /* 69586764Sjlemon * Initialization of the tcpcb for transaction; 69686764Sjlemon * set SND.WND = SEG.WND, 69786764Sjlemon * initialize CCsend and CCrecv. 69886764Sjlemon */ 69986764Sjlemon tp->t_flags |= TF_REQ_CC|TF_RCVD_CC; 70086764Sjlemon tp->cc_send = sc->sc_cc_send; 70186764Sjlemon tp->cc_recv = sc->sc_cc_recv; 70286764Sjlemon } 703125680Sbms#ifdef TCP_SIGNATURE 704125680Sbms if (sc->sc_flags & SCF_SIGNATURE) 705125680Sbms tp->t_flags |= TF_SIGNATURE; 706125783Sbms#endif 70786764Sjlemon 708122922Sandre /* 709122922Sandre * Set up MSS and get cached values from tcp_hostcache. 710122922Sandre * This might overwrite some of the defaults we just set. 711122922Sandre */ 71286764Sjlemon tcp_mss(tp, sc->sc_peer_mss); 71386764Sjlemon 71486764Sjlemon /* 71586764Sjlemon * If the SYN,ACK was retransmitted, reset cwnd to 1 segment. 71686764Sjlemon */ 71786764Sjlemon if (sc->sc_rxtslot != 0) 71886764Sjlemon tp->snd_cwnd = tp->t_maxseg; 71986764Sjlemon callout_reset(tp->tt_keep, tcp_keepinit, tcp_timer_keep, tp); 72086764Sjlemon 721122496Ssam INP_UNLOCK(inp); 722122496Ssam 72386764Sjlemon tcpstat.tcps_accepts++; 72486764Sjlemon return (so); 72586764Sjlemon 72686764Sjlemonabort: 727122496Ssam INP_UNLOCK(inp); 728122496Ssamabort2: 72986764Sjlemon if (so != NULL) 73086764Sjlemon (void) soabort(so); 73186764Sjlemon return (NULL); 73286764Sjlemon} 73386764Sjlemon 73486764Sjlemon/* 73586764Sjlemon * This function gets called when we receive an ACK for a 73686764Sjlemon * socket in the LISTEN state. We look up the connection 73786764Sjlemon * in the syncache, and if its there, we pull it out of 73886764Sjlemon * the cache and turn it into a full-blown connection in 73986764Sjlemon * the SYN-RECEIVED state. 74086764Sjlemon */ 74186764Sjlemonint 74286764Sjlemonsyncache_expand(inc, th, sop, m) 74386764Sjlemon struct in_conninfo *inc; 74486764Sjlemon struct tcphdr *th; 74586764Sjlemon struct socket **sop; 74686764Sjlemon struct mbuf *m; 74786764Sjlemon{ 74886764Sjlemon struct syncache *sc; 74986764Sjlemon struct syncache_head *sch; 75086764Sjlemon struct socket *so; 75186764Sjlemon 752122496Ssam INP_INFO_WLOCK_ASSERT(&tcbinfo); 753122496Ssam 75486764Sjlemon sc = syncache_lookup(inc, &sch); 75588180Sjlemon if (sc == NULL) { 75688180Sjlemon /* 75788180Sjlemon * There is no syncache entry, so see if this ACK is 75888180Sjlemon * a returning syncookie. To do this, first: 75988180Sjlemon * A. See if this socket has had a syncache entry dropped in 76088180Sjlemon * the past. We don't want to accept a bogus syncookie 76188180Sjlemon * if we've never received a SYN. 76288180Sjlemon * B. check that the syncookie is valid. If it is, then 76388180Sjlemon * cobble up a fake syncache entry, and return. 76488180Sjlemon */ 76588180Sjlemon if (!tcp_syncookies) 76688180Sjlemon return (0); 76788180Sjlemon sc = syncookie_lookup(inc, th, *sop); 76888180Sjlemon if (sc == NULL) 76988180Sjlemon return (0); 77088180Sjlemon sch = NULL; 77188180Sjlemon tcpstat.tcps_sc_recvcookie++; 77288180Sjlemon } 77386764Sjlemon 77486764Sjlemon /* 77586764Sjlemon * If seg contains an ACK, but not for our SYN/ACK, send a RST. 77686764Sjlemon */ 77786764Sjlemon if (th->th_ack != sc->sc_iss + 1) 77886764Sjlemon return (0); 77986764Sjlemon 78096602Srwatson so = syncache_socket(sc, *sop, m); 78186764Sjlemon if (so == NULL) { 78286764Sjlemon#if 0 78386764Sjlemonresetandabort: 78486764Sjlemon /* XXXjlemon check this - is this correct? */ 78586764Sjlemon (void) tcp_respond(NULL, m, m, th, 78686764Sjlemon th->th_seq + tlen, (tcp_seq)0, TH_RST|TH_ACK); 78786764Sjlemon#endif 78886764Sjlemon m_freem(m); /* XXX only needed for above */ 78986764Sjlemon tcpstat.tcps_sc_aborted++; 790122922Sandre } else 79186764Sjlemon tcpstat.tcps_sc_completed++; 792122922Sandre 79386764Sjlemon if (sch == NULL) 79486764Sjlemon syncache_free(sc); 79586764Sjlemon else 79686764Sjlemon syncache_drop(sc, sch); 79786764Sjlemon *sop = so; 79886764Sjlemon return (1); 79986764Sjlemon} 80086764Sjlemon 80186764Sjlemon/* 80286764Sjlemon * Given a LISTEN socket and an inbound SYN request, add 80386764Sjlemon * this to the syn cache, and send back a segment: 80486764Sjlemon * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK> 80586764Sjlemon * to the source. 80686764Sjlemon * 80786764Sjlemon * IMPORTANT NOTE: We do _NOT_ ACK data that might accompany the SYN. 80886764Sjlemon * Doing so would require that we hold onto the data and deliver it 80986764Sjlemon * to the application. However, if we are the target of a SYN-flood 81086764Sjlemon * DoS attack, an attacker could send data which would eventually 81186764Sjlemon * consume all available buffer space if it were ACKed. By not ACKing 81286764Sjlemon * the data, we avoid this DoS scenario. 81386764Sjlemon */ 81486764Sjlemonint 81586764Sjlemonsyncache_add(inc, to, th, sop, m) 81686764Sjlemon struct in_conninfo *inc; 81786764Sjlemon struct tcpopt *to; 81886764Sjlemon struct tcphdr *th; 81986764Sjlemon struct socket **sop; 82086764Sjlemon struct mbuf *m; 82186764Sjlemon{ 82286764Sjlemon struct tcpcb *tp; 82386764Sjlemon struct socket *so; 82486764Sjlemon struct syncache *sc = NULL; 82586764Sjlemon struct syncache_head *sch; 82686764Sjlemon struct mbuf *ipopts = NULL; 827122922Sandre struct rmxp_tao tao; 828122496Ssam int i, win; 82986764Sjlemon 830122496Ssam INP_INFO_WLOCK_ASSERT(&tcbinfo); 831122496Ssam 83286764Sjlemon so = *sop; 83386764Sjlemon tp = sototcpcb(so); 834122922Sandre bzero(&tao, sizeof(tao)); 83586764Sjlemon 83686764Sjlemon /* 83786764Sjlemon * Remember the IP options, if any. 83886764Sjlemon */ 83986764Sjlemon#ifdef INET6 84086764Sjlemon if (!inc->inc_isipv6) 84186764Sjlemon#endif 84286764Sjlemon ipopts = ip_srcroute(); 84386764Sjlemon 84486764Sjlemon /* 84586764Sjlemon * See if we already have an entry for this connection. 84686764Sjlemon * If we do, resend the SYN,ACK, and reset the retransmit timer. 84786764Sjlemon * 84886764Sjlemon * XXX 84986764Sjlemon * should the syncache be re-initialized with the contents 85086764Sjlemon * of the new SYN here (which may have different options?) 85186764Sjlemon */ 85286764Sjlemon sc = syncache_lookup(inc, &sch); 85386764Sjlemon if (sc != NULL) { 85486764Sjlemon tcpstat.tcps_sc_dupsyn++; 85586764Sjlemon if (ipopts) { 85686764Sjlemon /* 85786764Sjlemon * If we were remembering a previous source route, 85886764Sjlemon * forget it and use the new one we've been given. 85986764Sjlemon */ 86086764Sjlemon if (sc->sc_ipopts) 86186764Sjlemon (void) m_free(sc->sc_ipopts); 86286764Sjlemon sc->sc_ipopts = ipopts; 86386764Sjlemon } 86486764Sjlemon /* 86586764Sjlemon * Update timestamp if present. 86686764Sjlemon */ 86786764Sjlemon if (sc->sc_flags & SCF_TIMESTAMP) 86886764Sjlemon sc->sc_tsrecent = to->to_tsval; 86990556Sjlemon /* 87090556Sjlemon * PCB may have changed, pick up new values. 87190556Sjlemon */ 87290556Sjlemon sc->sc_tp = tp; 87390556Sjlemon sc->sc_inp_gencnt = tp->t_inpcb->inp_gencnt; 874118864Sharti#ifdef TCPDEBUG 875118864Sharti if (syncache_respond(sc, m, so) == 0) { 876118864Sharti#else 87786764Sjlemon if (syncache_respond(sc, m) == 0) { 878118864Sharti#endif 879122496Ssam /* NB: guarded by INP_INFO_WLOCK(&tcbinfo) */ 88086764Sjlemon TAILQ_REMOVE(&tcp_syncache.timerq[sc->sc_rxtslot], 88186764Sjlemon sc, sc_timerq); 88286764Sjlemon SYNCACHE_TIMEOUT(sc, sc->sc_rxtslot); 88386764Sjlemon tcpstat.tcps_sndacks++; 88486764Sjlemon tcpstat.tcps_sndtotal++; 88586764Sjlemon } 88686764Sjlemon *sop = NULL; 88786764Sjlemon return (1); 88886764Sjlemon } 88986764Sjlemon 89092760Sjeff sc = uma_zalloc(tcp_syncache.zone, M_NOWAIT); 89186764Sjlemon if (sc == NULL) { 89286764Sjlemon /* 89386764Sjlemon * The zone allocator couldn't provide more entries. 89486764Sjlemon * Treat this as if the cache was full; drop the oldest 89586764Sjlemon * entry and insert the new one. 89686764Sjlemon */ 897122496Ssam /* NB: guarded by INP_INFO_WLOCK(&tcbinfo) */ 89886764Sjlemon for (i = SYNCACHE_MAXREXMTS; i >= 0; i--) { 89986764Sjlemon sc = TAILQ_FIRST(&tcp_syncache.timerq[i]); 90086764Sjlemon if (sc != NULL) 90186764Sjlemon break; 90286764Sjlemon } 90388180Sjlemon sc->sc_tp->ts_recent = ticks; 90486764Sjlemon syncache_drop(sc, NULL); 90586764Sjlemon tcpstat.tcps_sc_zonefail++; 90692760Sjeff sc = uma_zalloc(tcp_syncache.zone, M_NOWAIT); 90786764Sjlemon if (sc == NULL) { 90886764Sjlemon if (ipopts) 90986764Sjlemon (void) m_free(ipopts); 91086764Sjlemon return (0); 91186764Sjlemon } 91286764Sjlemon } 91386764Sjlemon 91486764Sjlemon /* 91586764Sjlemon * Fill in the syncache values. 91686764Sjlemon */ 91786958Stanimura bzero(sc, sizeof(*sc)); 91886764Sjlemon sc->sc_tp = tp; 91986764Sjlemon sc->sc_inp_gencnt = tp->t_inpcb->inp_gencnt; 92086764Sjlemon sc->sc_ipopts = ipopts; 92186764Sjlemon sc->sc_inc.inc_fport = inc->inc_fport; 92286764Sjlemon sc->sc_inc.inc_lport = inc->inc_lport; 92386764Sjlemon#ifdef INET6 92486764Sjlemon sc->sc_inc.inc_isipv6 = inc->inc_isipv6; 92586764Sjlemon if (inc->inc_isipv6) { 92686764Sjlemon sc->sc_inc.inc6_faddr = inc->inc6_faddr; 92786764Sjlemon sc->sc_inc.inc6_laddr = inc->inc6_laddr; 92886764Sjlemon } else 92986764Sjlemon#endif 93086764Sjlemon { 93186764Sjlemon sc->sc_inc.inc_faddr = inc->inc_faddr; 93286764Sjlemon sc->sc_inc.inc_laddr = inc->inc_laddr; 93386764Sjlemon } 93486764Sjlemon sc->sc_irs = th->th_seq; 935110023Ssilby sc->sc_flags = 0; 936110023Ssilby sc->sc_peer_mss = to->to_flags & TOF_MSS ? to->to_mss : 0; 93788330Sjlemon if (tcp_syncookies) 93888330Sjlemon sc->sc_iss = syncookie_generate(sc); 93988330Sjlemon else 94088330Sjlemon sc->sc_iss = arc4random(); 94186764Sjlemon 94286764Sjlemon /* Initial receive window: clip sbspace to [0 .. TCP_MAXWIN] */ 94386764Sjlemon win = sbspace(&so->so_rcv); 94486764Sjlemon win = imax(win, 0); 94586764Sjlemon win = imin(win, TCP_MAXWIN); 94686764Sjlemon sc->sc_wnd = win; 94786764Sjlemon 94886764Sjlemon if (tcp_do_rfc1323) { 94986764Sjlemon /* 95086764Sjlemon * A timestamp received in a SYN makes 95186764Sjlemon * it ok to send timestamp requests and replies. 95286764Sjlemon */ 95386764Sjlemon if (to->to_flags & TOF_TS) { 95486764Sjlemon sc->sc_tsrecent = to->to_tsval; 95586764Sjlemon sc->sc_flags |= SCF_TIMESTAMP; 95686764Sjlemon } 95786764Sjlemon if (to->to_flags & TOF_SCALE) { 95886764Sjlemon int wscale = 0; 95986764Sjlemon 96086764Sjlemon /* Compute proper scaling value from buffer space */ 96186764Sjlemon while (wscale < TCP_MAX_WINSHIFT && 96286764Sjlemon (TCP_MAXWIN << wscale) < so->so_rcv.sb_hiwat) 96386764Sjlemon wscale++; 96486764Sjlemon sc->sc_request_r_scale = wscale; 96586764Sjlemon sc->sc_requested_s_scale = to->to_requested_s_scale; 96686764Sjlemon sc->sc_flags |= SCF_WINSCALE; 96786764Sjlemon } 96886764Sjlemon } 96986764Sjlemon if (tcp_do_rfc1644) { 97086764Sjlemon /* 97186764Sjlemon * A CC or CC.new option received in a SYN makes 97286764Sjlemon * it ok to send CC in subsequent segments. 97386764Sjlemon */ 97486764Sjlemon if (to->to_flags & (TOF_CC|TOF_CCNEW)) { 97586764Sjlemon sc->sc_cc_recv = to->to_cc; 97686764Sjlemon sc->sc_cc_send = CC_INC(tcp_ccgen); 97786764Sjlemon sc->sc_flags |= SCF_CC; 97886764Sjlemon } 97986764Sjlemon } 98086764Sjlemon if (tp->t_flags & TF_NOOPT) 98186764Sjlemon sc->sc_flags = SCF_NOOPT; 982125680Sbms#ifdef TCP_SIGNATURE 983125680Sbms /* 984125680Sbms * If listening socket requested TCP digests, and received SYN 985125680Sbms * contains the option, flag this in the syncache so that 986125680Sbms * syncache_respond() will do the right thing with the SYN+ACK. 987125680Sbms * XXX Currently we always record the option by default and will 988125680Sbms * attempt to use it in syncache_respond(). 989125680Sbms */ 990125680Sbms if (to->to_flags & TOF_SIGNATURE) 991125680Sbms sc->sc_flags = SCF_SIGNATURE; 992125783Sbms#endif 99386764Sjlemon 99486764Sjlemon /* 99586764Sjlemon * XXX 99686764Sjlemon * We have the option here of not doing TAO (even if the segment 99786764Sjlemon * qualifies) and instead fall back to a normal 3WHS via the syncache. 99886764Sjlemon * This allows us to apply synflood protection to TAO-qualifying SYNs 99986764Sjlemon * also. However, there should be a hueristic to determine when to 100086764Sjlemon * do this, and is not present at the moment. 100186764Sjlemon */ 100286764Sjlemon 100386764Sjlemon /* 100486764Sjlemon * Perform TAO test on incoming CC (SEG.CC) option, if any. 100586764Sjlemon * - compare SEG.CC against cached CC from the same host, if any. 100686764Sjlemon * - if SEG.CC > chached value, SYN must be new and is accepted 100786764Sjlemon * immediately: save new CC in the cache, mark the socket 100886764Sjlemon * connected, enter ESTABLISHED state, turn on flag to 100986764Sjlemon * send a SYN in the next segment. 101086764Sjlemon * A virtual advertised window is set in rcv_adv to 101186764Sjlemon * initialize SWS prevention. Then enter normal segment 101286764Sjlemon * processing: drop SYN, process data and FIN. 101386764Sjlemon * - otherwise do a normal 3-way handshake. 101486764Sjlemon */ 1015122922Sandre if (tcp_do_rfc1644) 1016122922Sandre tcp_hc_gettao(&sc->sc_inc, &tao); 1017122922Sandre 101886764Sjlemon if ((to->to_flags & TOF_CC) != 0) { 101986764Sjlemon if (((tp->t_flags & TF_NOPUSH) != 0) && 1020122922Sandre sc->sc_flags & SCF_CC && tao.tao_cc != 0 && 1021122922Sandre CC_GT(to->to_cc, tao.tao_cc)) { 102286764Sjlemon sc->sc_rxtslot = 0; 102396602Srwatson so = syncache_socket(sc, *sop, m); 102486764Sjlemon if (so != NULL) { 1025122922Sandre tao.tao_cc = to->to_cc; 1026122922Sandre tcp_hc_updatetao(&sc->sc_inc, TCP_HC_TAO_CC, 1027122922Sandre tao.tao_cc, 0); 102886764Sjlemon *sop = so; 102986764Sjlemon } 103086764Sjlemon syncache_free(sc); 103186764Sjlemon return (so != NULL); 103286764Sjlemon } 103386764Sjlemon } else { 103486764Sjlemon /* 103586764Sjlemon * No CC option, but maybe CC.NEW: invalidate cached value. 103686764Sjlemon */ 1037122922Sandre if (tcp_do_rfc1644) { 1038122922Sandre tao.tao_cc = 0; 1039122922Sandre tcp_hc_updatetao(&sc->sc_inc, TCP_HC_TAO_CC, 1040122922Sandre tao.tao_cc, 0); 1041122922Sandre } 104286764Sjlemon } 1043122922Sandre 104486764Sjlemon /* 104586764Sjlemon * TAO test failed or there was no CC option, 104686764Sjlemon * do a standard 3-way handshake. 104786764Sjlemon */ 1048118864Sharti#ifdef TCPDEBUG 1049118864Sharti if (syncache_respond(sc, m, so) == 0) { 1050118864Sharti#else 105188180Sjlemon if (syncache_respond(sc, m) == 0) { 1052118864Sharti#endif 105388180Sjlemon syncache_insert(sc, sch); 105488180Sjlemon tcpstat.tcps_sndacks++; 105588180Sjlemon tcpstat.tcps_sndtotal++; 105686764Sjlemon } else { 105786764Sjlemon syncache_free(sc); 105888180Sjlemon tcpstat.tcps_sc_dropped++; 105986764Sjlemon } 106086764Sjlemon *sop = NULL; 106186764Sjlemon return (1); 106286764Sjlemon} 106386764Sjlemon 1064118864Sharti#ifdef TCPDEBUG 106586764Sjlemonstatic int 1066118864Shartisyncache_respond(sc, m, so) 1067118864Sharti struct syncache *sc; 1068118864Sharti struct mbuf *m; 1069118864Sharti struct socket *so; 1070118864Sharti#else 1071118864Shartistatic int 107286764Sjlemonsyncache_respond(sc, m) 107386764Sjlemon struct syncache *sc; 107486764Sjlemon struct mbuf *m; 1075118864Sharti#endif 107686764Sjlemon{ 107786764Sjlemon u_int8_t *optp; 107886764Sjlemon int optlen, error; 107986764Sjlemon u_int16_t tlen, hlen, mssopt; 108086764Sjlemon struct ip *ip = NULL; 108186764Sjlemon struct tcphdr *th; 1082122496Ssam struct inpcb *inp; 108386764Sjlemon#ifdef INET6 108486764Sjlemon struct ip6_hdr *ip6 = NULL; 108586764Sjlemon#endif 108686764Sjlemon 1087122922Sandre hlen = 108886764Sjlemon#ifdef INET6 1089122922Sandre (sc->sc_inc.inc_isipv6) ? sizeof(struct ip6_hdr) : 109086764Sjlemon#endif 1091122922Sandre sizeof(struct ip); 109286764Sjlemon 1093122922Sandre KASSERT((&sc->sc_inc) != NULL, ("syncache_respond with NULL in_conninfo pointer")); 1094122922Sandre 1095122922Sandre /* Determine MSS we advertize to other end of connection */ 1096122922Sandre mssopt = tcp_mssopt(&sc->sc_inc); 1097122922Sandre 109886764Sjlemon /* Compute the size of the TCP options. */ 109986764Sjlemon if (sc->sc_flags & SCF_NOOPT) { 110086764Sjlemon optlen = 0; 110186764Sjlemon } else { 110286764Sjlemon optlen = TCPOLEN_MAXSEG + 110386764Sjlemon ((sc->sc_flags & SCF_WINSCALE) ? 4 : 0) + 110486764Sjlemon ((sc->sc_flags & SCF_TIMESTAMP) ? TCPOLEN_TSTAMP_APPA : 0) + 110586764Sjlemon ((sc->sc_flags & SCF_CC) ? TCPOLEN_CC_APPA * 2 : 0); 1106125680Sbms#ifdef TCP_SIGNATURE 1107125783Sbms optlen += (sc->sc_flags & SCF_SIGNATURE) ? 1108125819Sbms TCPOLEN_SIGNATURE + 2 : 0; 1109125783Sbms#endif 111086764Sjlemon } 111186764Sjlemon tlen = hlen + sizeof(struct tcphdr) + optlen; 111286764Sjlemon 111386764Sjlemon /* 111486764Sjlemon * XXX 111586764Sjlemon * assume that the entire packet will fit in a header mbuf 111686764Sjlemon */ 111786764Sjlemon KASSERT(max_linkhdr + tlen <= MHLEN, ("syncache: mbuf too small")); 111886764Sjlemon 111986764Sjlemon /* 112086764Sjlemon * XXX shouldn't this reuse the mbuf if possible ? 112186764Sjlemon * Create the IP+TCP header from scratch. 112286764Sjlemon */ 112386764Sjlemon if (m) 112486764Sjlemon m_freem(m); 112586764Sjlemon 1126111119Simp m = m_gethdr(M_DONTWAIT, MT_HEADER); 112786764Sjlemon if (m == NULL) 112886764Sjlemon return (ENOBUFS); 112986764Sjlemon m->m_data += max_linkhdr; 113086764Sjlemon m->m_len = tlen; 113186764Sjlemon m->m_pkthdr.len = tlen; 113286764Sjlemon m->m_pkthdr.rcvif = NULL; 1133122496Ssam inp = sc->sc_tp->t_inpcb; 1134122496Ssam INP_LOCK(inp); 1135101106Srwatson#ifdef MAC 1136128905Srwatson mac_create_mbuf_from_inpcb(inp, m); 1137101106Srwatson#endif 113886764Sjlemon 113986764Sjlemon#ifdef INET6 114086764Sjlemon if (sc->sc_inc.inc_isipv6) { 114186764Sjlemon ip6 = mtod(m, struct ip6_hdr *); 114286764Sjlemon ip6->ip6_vfc = IPV6_VERSION; 114386764Sjlemon ip6->ip6_nxt = IPPROTO_TCP; 114486764Sjlemon ip6->ip6_src = sc->sc_inc.inc6_laddr; 114586764Sjlemon ip6->ip6_dst = sc->sc_inc.inc6_faddr; 114686764Sjlemon ip6->ip6_plen = htons(tlen - hlen); 114786764Sjlemon /* ip6_hlim is set after checksum */ 114886764Sjlemon /* ip6_flow = ??? */ 114986764Sjlemon 115086764Sjlemon th = (struct tcphdr *)(ip6 + 1); 115186764Sjlemon } else 115286764Sjlemon#endif 115386764Sjlemon { 115486764Sjlemon ip = mtod(m, struct ip *); 115586764Sjlemon ip->ip_v = IPVERSION; 115686764Sjlemon ip->ip_hl = sizeof(struct ip) >> 2; 115786764Sjlemon ip->ip_len = tlen; 115886764Sjlemon ip->ip_id = 0; 115986764Sjlemon ip->ip_off = 0; 116086764Sjlemon ip->ip_sum = 0; 116186764Sjlemon ip->ip_p = IPPROTO_TCP; 116286764Sjlemon ip->ip_src = sc->sc_inc.inc_laddr; 116386764Sjlemon ip->ip_dst = sc->sc_inc.inc_faddr; 1164122496Ssam ip->ip_ttl = inp->inp_ip_ttl; /* XXX */ 1165122496Ssam ip->ip_tos = inp->inp_ip_tos; /* XXX */ 116686764Sjlemon 116798204Ssilby /* 1168108125Shsu * See if we should do MTU discovery. Route lookups are 1169108125Shsu * expensive, so we will only unset the DF bit if: 1170101405Ssilby * 1171101405Ssilby * 1) path_mtu_discovery is disabled 1172101405Ssilby * 2) the SCF_UNREACH flag has been set 117398204Ssilby */ 1174108125Shsu if (path_mtu_discovery && ((sc->sc_flags & SCF_UNREACH) == 0)) 117598204Ssilby ip->ip_off |= IP_DF; 117698204Ssilby 117786764Sjlemon th = (struct tcphdr *)(ip + 1); 117886764Sjlemon } 117986764Sjlemon th->th_sport = sc->sc_inc.inc_lport; 118086764Sjlemon th->th_dport = sc->sc_inc.inc_fport; 118186764Sjlemon 118286764Sjlemon th->th_seq = htonl(sc->sc_iss); 118386764Sjlemon th->th_ack = htonl(sc->sc_irs + 1); 118486764Sjlemon th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 118586764Sjlemon th->th_x2 = 0; 118686764Sjlemon th->th_flags = TH_SYN|TH_ACK; 118786764Sjlemon th->th_win = htons(sc->sc_wnd); 118886764Sjlemon th->th_urp = 0; 118986764Sjlemon 119086764Sjlemon /* Tack on the TCP options. */ 1191108125Shsu if (optlen != 0) { 1192108125Shsu optp = (u_int8_t *)(th + 1); 1193108125Shsu *optp++ = TCPOPT_MAXSEG; 1194108125Shsu *optp++ = TCPOLEN_MAXSEG; 1195108125Shsu *optp++ = (mssopt >> 8) & 0xff; 1196108125Shsu *optp++ = mssopt & 0xff; 119786764Sjlemon 1198108125Shsu if (sc->sc_flags & SCF_WINSCALE) { 1199108125Shsu *((u_int32_t *)optp) = htonl(TCPOPT_NOP << 24 | 1200108125Shsu TCPOPT_WINDOW << 16 | TCPOLEN_WINDOW << 8 | 1201108125Shsu sc->sc_request_r_scale); 1202108125Shsu optp += 4; 1203108125Shsu } 120486764Sjlemon 1205108125Shsu if (sc->sc_flags & SCF_TIMESTAMP) { 1206108125Shsu u_int32_t *lp = (u_int32_t *)(optp); 120786764Sjlemon 1208108125Shsu /* Form timestamp option per appendix A of RFC 1323. */ 1209108125Shsu *lp++ = htonl(TCPOPT_TSTAMP_HDR); 1210108125Shsu *lp++ = htonl(ticks); 1211108125Shsu *lp = htonl(sc->sc_tsrecent); 1212108125Shsu optp += TCPOLEN_TSTAMP_APPA; 1213108125Shsu } 121486764Sjlemon 1215108125Shsu /* 1216108125Shsu * Send CC and CC.echo if we received CC from our peer. 1217108125Shsu */ 1218108125Shsu if (sc->sc_flags & SCF_CC) { 1219108125Shsu u_int32_t *lp = (u_int32_t *)(optp); 122086764Sjlemon 1221108125Shsu *lp++ = htonl(TCPOPT_CC_HDR(TCPOPT_CC)); 1222108125Shsu *lp++ = htonl(sc->sc_cc_send); 1223108125Shsu *lp++ = htonl(TCPOPT_CC_HDR(TCPOPT_CCECHO)); 1224108125Shsu *lp = htonl(sc->sc_cc_recv); 1225108125Shsu optp += TCPOLEN_CC_APPA * 2; 1226108125Shsu } 1227125680Sbms 1228125680Sbms#ifdef TCP_SIGNATURE 1229125680Sbms /* 1230125680Sbms * Handle TCP-MD5 passive opener response. 1231125680Sbms */ 1232125680Sbms if (sc->sc_flags & SCF_SIGNATURE) { 1233125680Sbms u_int8_t *bp = optp; 1234125680Sbms int i; 1235125680Sbms 1236125680Sbms *bp++ = TCPOPT_SIGNATURE; 1237125680Sbms *bp++ = TCPOLEN_SIGNATURE; 1238125680Sbms for (i = 0; i < TCP_SIGLEN; i++) 1239125680Sbms *bp++ = 0; 1240125783Sbms tcp_signature_compute(m, sizeof(struct ip), 0, optlen, 1241125680Sbms optp + 2, IPSEC_DIR_OUTBOUND); 1242125680Sbms *bp++ = TCPOPT_NOP; 1243125680Sbms *bp++ = TCPOPT_EOL; 1244125680Sbms optp += TCPOLEN_SIGNATURE + 2; 1245125680Sbms } 1246125680Sbms#endif /* TCP_SIGNATURE */ 124786764Sjlemon } 124886764Sjlemon 124986764Sjlemon#ifdef INET6 125086764Sjlemon if (sc->sc_inc.inc_isipv6) { 125186764Sjlemon th->th_sum = 0; 125286764Sjlemon th->th_sum = in6_cksum(m, IPPROTO_TCP, hlen, tlen - hlen); 1253122922Sandre ip6->ip6_hlim = in6_selecthlim(NULL, NULL); 1254122922Sandre error = ip6_output(m, NULL, NULL, 0, NULL, NULL, inp); 125586764Sjlemon } else 125686764Sjlemon#endif 125786764Sjlemon { 125886764Sjlemon th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, 125986764Sjlemon htons(tlen - hlen + IPPROTO_TCP)); 126086764Sjlemon m->m_pkthdr.csum_flags = CSUM_TCP; 126186764Sjlemon m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 1262118864Sharti#ifdef TCPDEBUG 1263118864Sharti /* 1264118864Sharti * Trace. 1265118864Sharti */ 1266118864Sharti if (so != NULL && so->so_options & SO_DEBUG) { 1267118864Sharti struct tcpcb *tp = sototcpcb(so); 1268118864Sharti tcp_trace(TA_OUTPUT, tp->t_state, tp, 1269118864Sharti mtod(m, void *), th, 0); 1270118864Sharti } 1271118864Sharti#endif 1272122922Sandre error = ip_output(m, sc->sc_ipopts, NULL, 0, NULL, inp); 127386764Sjlemon } 1274122496Ssam INP_UNLOCK(inp); 127586764Sjlemon return (error); 127686764Sjlemon} 127788180Sjlemon 127888180Sjlemon/* 127988180Sjlemon * cookie layers: 128088180Sjlemon * 128188180Sjlemon * |. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .| 128288180Sjlemon * | peer iss | 1283111405Ssilby * | MD5(laddr,faddr,secret,lport,fport) |. . . . . . .| 128488180Sjlemon * | 0 |(A)| | 128588180Sjlemon * (A): peer mss index 128688180Sjlemon */ 128788180Sjlemon 128888180Sjlemon/* 128988180Sjlemon * The values below are chosen to minimize the size of the tcp_secret 1290111338Ssilby * table, as well as providing roughly a 16 second lifetime for the cookie. 129188180Sjlemon */ 129288180Sjlemon 1293111338Ssilby#define SYNCOOKIE_WNDBITS 5 /* exposed bits for window indexing */ 1294111338Ssilby#define SYNCOOKIE_TIMESHIFT 1 /* scale ticks to window time units */ 129588180Sjlemon 129688180Sjlemon#define SYNCOOKIE_WNDMASK ((1 << SYNCOOKIE_WNDBITS) - 1) 1297111338Ssilby#define SYNCOOKIE_NSECRETS (1 << SYNCOOKIE_WNDBITS) 129888180Sjlemon#define SYNCOOKIE_TIMEOUT \ 129988180Sjlemon (hz * (1 << SYNCOOKIE_WNDBITS) / (1 << SYNCOOKIE_TIMESHIFT)) 130088180Sjlemon#define SYNCOOKIE_DATAMASK ((3 << SYNCOOKIE_WNDBITS) | SYNCOOKIE_WNDMASK) 130188180Sjlemon 130288180Sjlemonstatic struct { 1303111338Ssilby u_int32_t ts_secbits[4]; 130488180Sjlemon u_int ts_expire; 130588180Sjlemon} tcp_secret[SYNCOOKIE_NSECRETS]; 130688180Sjlemon 130788180Sjlemonstatic int tcp_msstab[] = { 0, 536, 1460, 8960 }; 130888180Sjlemon 130988180Sjlemonstatic MD5_CTX syn_ctx; 131088180Sjlemon 131188180Sjlemon#define MD5Add(v) MD5Update(&syn_ctx, (u_char *)&v, sizeof(v)) 131288180Sjlemon 1313111338Ssilbystruct md5_add { 1314111338Ssilby u_int32_t laddr, faddr; 1315111338Ssilby u_int32_t secbits[4]; 1316111338Ssilby u_int16_t lport, fport; 1317111338Ssilby}; 1318111338Ssilby 1319111338Ssilby#ifdef CTASSERT 1320111338SsilbyCTASSERT(sizeof(struct md5_add) == 28); 1321111338Ssilby#endif 1322111338Ssilby 132388180Sjlemon/* 132488180Sjlemon * Consider the problem of a recreated (and retransmitted) cookie. If the 132588180Sjlemon * original SYN was accepted, the connection is established. The second 132688180Sjlemon * SYN is inflight, and if it arrives with an ISN that falls within the 132788180Sjlemon * receive window, the connection is killed. 132888180Sjlemon * 132988180Sjlemon * However, since cookies have other problems, this may not be worth 133088180Sjlemon * worrying about. 133188180Sjlemon */ 133288180Sjlemon 133388180Sjlemonstatic u_int32_t 133488180Sjlemonsyncookie_generate(struct syncache *sc) 133588180Sjlemon{ 133688180Sjlemon u_int32_t md5_buffer[4]; 133788180Sjlemon u_int32_t data; 1338111338Ssilby int idx, i; 1339111338Ssilby struct md5_add add; 134088180Sjlemon 1341122496Ssam /* NB: single threaded; could add INP_INFO_WLOCK_ASSERT(&tcbinfo) */ 1342122496Ssam 1343111338Ssilby idx = ((ticks << SYNCOOKIE_TIMESHIFT) / hz) & SYNCOOKIE_WNDMASK; 134488180Sjlemon if (tcp_secret[idx].ts_expire < ticks) { 1345111338Ssilby for (i = 0; i < 4; i++) 1346111338Ssilby tcp_secret[idx].ts_secbits[i] = arc4random(); 134788180Sjlemon tcp_secret[idx].ts_expire = ticks + SYNCOOKIE_TIMEOUT; 134888180Sjlemon } 134988180Sjlemon for (data = sizeof(tcp_msstab) / sizeof(int) - 1; data > 0; data--) 135088180Sjlemon if (tcp_msstab[data] <= sc->sc_peer_mss) 135188180Sjlemon break; 1352111338Ssilby data = (data << SYNCOOKIE_WNDBITS) | idx; 135388180Sjlemon data ^= sc->sc_irs; /* peer's iss */ 135488180Sjlemon MD5Init(&syn_ctx); 135588180Sjlemon#ifdef INET6 135688180Sjlemon if (sc->sc_inc.inc_isipv6) { 135788180Sjlemon MD5Add(sc->sc_inc.inc6_laddr); 135888180Sjlemon MD5Add(sc->sc_inc.inc6_faddr); 1359111338Ssilby add.laddr = 0; 1360111338Ssilby add.faddr = 0; 136188180Sjlemon } else 136288180Sjlemon#endif 136388180Sjlemon { 1364111338Ssilby add.laddr = sc->sc_inc.inc_laddr.s_addr; 1365111338Ssilby add.faddr = sc->sc_inc.inc_faddr.s_addr; 136688180Sjlemon } 1367111338Ssilby add.lport = sc->sc_inc.inc_lport; 1368111338Ssilby add.fport = sc->sc_inc.inc_fport; 1369111338Ssilby add.secbits[0] = tcp_secret[idx].ts_secbits[0]; 1370111338Ssilby add.secbits[1] = tcp_secret[idx].ts_secbits[1]; 1371111338Ssilby add.secbits[2] = tcp_secret[idx].ts_secbits[2]; 1372111338Ssilby add.secbits[3] = tcp_secret[idx].ts_secbits[3]; 1373111338Ssilby MD5Add(add); 137488180Sjlemon MD5Final((u_char *)&md5_buffer, &syn_ctx); 1375111338Ssilby data ^= (md5_buffer[0] & ~SYNCOOKIE_WNDMASK); 137688180Sjlemon return (data); 137788180Sjlemon} 137888180Sjlemon 137988180Sjlemonstatic struct syncache * 138088180Sjlemonsyncookie_lookup(inc, th, so) 138188180Sjlemon struct in_conninfo *inc; 138288180Sjlemon struct tcphdr *th; 138388180Sjlemon struct socket *so; 138488180Sjlemon{ 138588180Sjlemon u_int32_t md5_buffer[4]; 138688180Sjlemon struct syncache *sc; 138788180Sjlemon u_int32_t data; 138888180Sjlemon int wnd, idx; 1389111338Ssilby struct md5_add add; 139088180Sjlemon 1391122496Ssam /* NB: single threaded; could add INP_INFO_WLOCK_ASSERT(&tcbinfo) */ 1392122496Ssam 139388180Sjlemon data = (th->th_ack - 1) ^ (th->th_seq - 1); /* remove ISS */ 1394111338Ssilby idx = data & SYNCOOKIE_WNDMASK; 139588180Sjlemon if (tcp_secret[idx].ts_expire < ticks || 139688180Sjlemon sototcpcb(so)->ts_recent + SYNCOOKIE_TIMEOUT < ticks) 139788180Sjlemon return (NULL); 139888180Sjlemon MD5Init(&syn_ctx); 139988180Sjlemon#ifdef INET6 140088180Sjlemon if (inc->inc_isipv6) { 140188180Sjlemon MD5Add(inc->inc6_laddr); 140288180Sjlemon MD5Add(inc->inc6_faddr); 1403111338Ssilby add.laddr = 0; 1404111338Ssilby add.faddr = 0; 140588180Sjlemon } else 140688180Sjlemon#endif 140788180Sjlemon { 1408111338Ssilby add.laddr = inc->inc_laddr.s_addr; 1409111338Ssilby add.faddr = inc->inc_faddr.s_addr; 141088180Sjlemon } 1411111338Ssilby add.lport = inc->inc_lport; 1412111338Ssilby add.fport = inc->inc_fport; 1413111338Ssilby add.secbits[0] = tcp_secret[idx].ts_secbits[0]; 1414111338Ssilby add.secbits[1] = tcp_secret[idx].ts_secbits[1]; 1415111338Ssilby add.secbits[2] = tcp_secret[idx].ts_secbits[2]; 1416111338Ssilby add.secbits[3] = tcp_secret[idx].ts_secbits[3]; 1417111338Ssilby MD5Add(add); 141888180Sjlemon MD5Final((u_char *)&md5_buffer, &syn_ctx); 1419111338Ssilby data ^= md5_buffer[0]; 142088180Sjlemon if ((data & ~SYNCOOKIE_DATAMASK) != 0) 142188180Sjlemon return (NULL); 142288180Sjlemon data = data >> SYNCOOKIE_WNDBITS; 142388180Sjlemon 142492760Sjeff sc = uma_zalloc(tcp_syncache.zone, M_NOWAIT); 142588180Sjlemon if (sc == NULL) 142688180Sjlemon return (NULL); 142788180Sjlemon /* 142888180Sjlemon * Fill in the syncache values. 142988180Sjlemon * XXX duplicate code from syncache_add 143088180Sjlemon */ 143188180Sjlemon sc->sc_ipopts = NULL; 143288180Sjlemon sc->sc_inc.inc_fport = inc->inc_fport; 143388180Sjlemon sc->sc_inc.inc_lport = inc->inc_lport; 143488180Sjlemon#ifdef INET6 143588180Sjlemon sc->sc_inc.inc_isipv6 = inc->inc_isipv6; 143688180Sjlemon if (inc->inc_isipv6) { 143788180Sjlemon sc->sc_inc.inc6_faddr = inc->inc6_faddr; 143888180Sjlemon sc->sc_inc.inc6_laddr = inc->inc6_laddr; 143988180Sjlemon } else 144088180Sjlemon#endif 144188180Sjlemon { 144288180Sjlemon sc->sc_inc.inc_faddr = inc->inc_faddr; 144388180Sjlemon sc->sc_inc.inc_laddr = inc->inc_laddr; 144488180Sjlemon } 144588180Sjlemon sc->sc_irs = th->th_seq - 1; 144688180Sjlemon sc->sc_iss = th->th_ack - 1; 144788180Sjlemon wnd = sbspace(&so->so_rcv); 144888180Sjlemon wnd = imax(wnd, 0); 144988180Sjlemon wnd = imin(wnd, TCP_MAXWIN); 145088180Sjlemon sc->sc_wnd = wnd; 145188180Sjlemon sc->sc_flags = 0; 145288180Sjlemon sc->sc_rxtslot = 0; 145388180Sjlemon sc->sc_peer_mss = tcp_msstab[data]; 145488180Sjlemon return (sc); 145588180Sjlemon} 1456