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FreeBSD/Linux Kernel Cross Reference
sys/netinet/tcp_subr.c

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    1 /*-
    2  * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995
    3  *      The Regents of the University of California.  All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  * 4. Neither the name of the University nor the names of its contributors
   14  *    may be used to endorse or promote products derived from this software
   15  *    without specific prior written permission.
   16  *
   17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   27  * SUCH DAMAGE.
   28  *
   29  *      @(#)tcp_subr.c  8.2 (Berkeley) 5/24/95
   30  */
   31 
   32 #include <sys/cdefs.h>
   33 __FBSDID("$FreeBSD: stable/8/sys/netinet/tcp_subr.c 238027 2012-07-02 20:36:54Z mdf $");
   34 
   35 #include "opt_compat.h"
   36 #include "opt_inet.h"
   37 #include "opt_inet6.h"
   38 #include "opt_ipsec.h"
   39 #include "opt_tcpdebug.h"
   40 
   41 #include <sys/param.h>
   42 #include <sys/systm.h>
   43 #include <sys/callout.h>
   44 #include <sys/hhook.h>
   45 #include <sys/kernel.h>
   46 #include <sys/khelp.h>
   47 #include <sys/sysctl.h>
   48 #include <sys/jail.h>
   49 #include <sys/malloc.h>
   50 #include <sys/mbuf.h>
   51 #ifdef INET6
   52 #include <sys/domain.h>
   53 #endif
   54 #include <sys/priv.h>
   55 #include <sys/proc.h>
   56 #include <sys/socket.h>
   57 #include <sys/socketvar.h>
   58 #include <sys/protosw.h>
   59 #include <sys/random.h>
   60 
   61 #include <vm/uma.h>
   62 
   63 #include <net/route.h>
   64 #include <net/if.h>
   65 #include <net/vnet.h>
   66 
   67 #include <netinet/cc.h>
   68 #include <netinet/in.h>
   69 #include <netinet/in_systm.h>
   70 #include <netinet/ip.h>
   71 #ifdef INET6
   72 #include <netinet/ip6.h>
   73 #endif
   74 #include <netinet/in_pcb.h>
   75 #ifdef INET6
   76 #include <netinet6/in6_pcb.h>
   77 #endif
   78 #include <netinet/in_var.h>
   79 #include <netinet/ip_var.h>
   80 #ifdef INET6
   81 #include <netinet6/ip6_var.h>
   82 #include <netinet6/scope6_var.h>
   83 #include <netinet6/nd6.h>
   84 #endif
   85 #include <netinet/ip_icmp.h>
   86 #include <netinet/tcp_fsm.h>
   87 #include <netinet/tcp_seq.h>
   88 #include <netinet/tcp_timer.h>
   89 #include <netinet/tcp_var.h>
   90 #include <netinet/tcp_syncache.h>
   91 #include <netinet/tcp_offload.h>
   92 #ifdef INET6
   93 #include <netinet6/tcp6_var.h>
   94 #endif
   95 #include <netinet/tcpip.h>
   96 #ifdef TCPDEBUG
   97 #include <netinet/tcp_debug.h>
   98 #endif
   99 #include <netinet6/ip6protosw.h>
  100 
  101 #ifdef IPSEC
  102 #include <netipsec/ipsec.h>
  103 #include <netipsec/xform.h>
  104 #ifdef INET6
  105 #include <netipsec/ipsec6.h>
  106 #endif
  107 #include <netipsec/key.h>
  108 #include <sys/syslog.h>
  109 #endif /*IPSEC*/
  110 
  111 #include <machine/in_cksum.h>
  112 #include <sys/md5.h>
  113 
  114 #include <security/mac/mac_framework.h>
  115 
  116 VNET_DEFINE(int, tcp_mssdflt) = TCP_MSS;
  117 #ifdef INET6
  118 VNET_DEFINE(int, tcp_v6mssdflt) = TCP6_MSS;
  119 #endif
  120 
  121 static int
  122 sysctl_net_inet_tcp_mss_check(SYSCTL_HANDLER_ARGS)
  123 {
  124         int error, new;
  125 
  126         new = V_tcp_mssdflt;
  127         error = sysctl_handle_int(oidp, &new, 0, req);
  128         if (error == 0 && req->newptr) {
  129                 if (new < TCP_MINMSS)
  130                         error = EINVAL;
  131                 else
  132                         V_tcp_mssdflt = new;
  133         }
  134         return (error);
  135 }
  136 
  137 SYSCTL_VNET_PROC(_net_inet_tcp, TCPCTL_MSSDFLT, mssdflt,
  138     CTLTYPE_INT|CTLFLAG_RW, &VNET_NAME(tcp_mssdflt), 0,
  139     &sysctl_net_inet_tcp_mss_check, "I",
  140     "Default TCP Maximum Segment Size");
  141 
  142 #ifdef INET6
  143 static int
  144 sysctl_net_inet_tcp_mss_v6_check(SYSCTL_HANDLER_ARGS)
  145 {
  146         int error, new;
  147 
  148         new = V_tcp_v6mssdflt;
  149         error = sysctl_handle_int(oidp, &new, 0, req);
  150         if (error == 0 && req->newptr) {
  151                 if (new < TCP_MINMSS)
  152                         error = EINVAL;
  153                 else
  154                         V_tcp_v6mssdflt = new;
  155         }
  156         return (error);
  157 }
  158 
  159 SYSCTL_VNET_PROC(_net_inet_tcp, TCPCTL_V6MSSDFLT, v6mssdflt,
  160     CTLTYPE_INT|CTLFLAG_RW, &VNET_NAME(tcp_v6mssdflt), 0,
  161     &sysctl_net_inet_tcp_mss_v6_check, "I",
  162    "Default TCP Maximum Segment Size for IPv6");
  163 #endif
  164 
  165 static int
  166 vnet_sysctl_msec_to_ticks(SYSCTL_HANDLER_ARGS)
  167 {
  168 
  169         VNET_SYSCTL_ARG(req, arg1);
  170         return (sysctl_msec_to_ticks(oidp, arg1, arg2, req));
  171 }
  172 
  173 /*
  174  * Minimum MSS we accept and use. This prevents DoS attacks where
  175  * we are forced to a ridiculous low MSS like 20 and send hundreds
  176  * of packets instead of one. The effect scales with the available
  177  * bandwidth and quickly saturates the CPU and network interface
  178  * with packet generation and sending. Set to zero to disable MINMSS
  179  * checking. This setting prevents us from sending too small packets.
  180  */
  181 VNET_DEFINE(int, tcp_minmss) = TCP_MINMSS;
  182 SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, minmss, CTLFLAG_RW,
  183      &VNET_NAME(tcp_minmss), 0,
  184     "Minmum TCP Maximum Segment Size");
  185 
  186 VNET_DEFINE(int, tcp_do_rfc1323) = 1;
  187 SYSCTL_VNET_INT(_net_inet_tcp, TCPCTL_DO_RFC1323, rfc1323, CTLFLAG_RW,
  188     &VNET_NAME(tcp_do_rfc1323), 0,
  189     "Enable rfc1323 (high performance TCP) extensions");
  190 
  191 static int      tcp_log_debug = 0;
  192 SYSCTL_INT(_net_inet_tcp, OID_AUTO, log_debug, CTLFLAG_RW,
  193     &tcp_log_debug, 0, "Log errors caused by incoming TCP segments");
  194 
  195 static int      tcp_tcbhashsize = 0;
  196 SYSCTL_INT(_net_inet_tcp, OID_AUTO, tcbhashsize, CTLFLAG_RDTUN,
  197     &tcp_tcbhashsize, 0, "Size of TCP control-block hashtable");
  198 
  199 static int      do_tcpdrain = 1;
  200 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_tcpdrain, CTLFLAG_RW, &do_tcpdrain, 0,
  201     "Enable tcp_drain routine for extra help when low on mbufs");
  202 
  203 SYSCTL_VNET_UINT(_net_inet_tcp, OID_AUTO, pcbcount, CTLFLAG_RD,
  204     &VNET_NAME(tcbinfo.ipi_count), 0, "Number of active PCBs");
  205 
  206 static VNET_DEFINE(int, icmp_may_rst) = 1;
  207 #define V_icmp_may_rst                  VNET(icmp_may_rst)
  208 SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, icmp_may_rst, CTLFLAG_RW,
  209     &VNET_NAME(icmp_may_rst), 0,
  210     "Certain ICMP unreachable messages may abort connections in SYN_SENT");
  211 
  212 static VNET_DEFINE(int, tcp_isn_reseed_interval) = 0;
  213 #define V_tcp_isn_reseed_interval       VNET(tcp_isn_reseed_interval)
  214 SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, isn_reseed_interval, CTLFLAG_RW,
  215     &VNET_NAME(tcp_isn_reseed_interval), 0,
  216     "Seconds between reseeding of ISN secret");
  217 
  218 /*
  219  * TCP bandwidth limiting sysctls.  Note that the default lower bound of
  220  * 1024 exists only for debugging.  A good production default would be
  221  * something like 6100.
  222  */
  223 SYSCTL_NODE(_net_inet_tcp, OID_AUTO, inflight, CTLFLAG_RW, 0,
  224     "TCP inflight data limiting");
  225 
  226 static VNET_DEFINE(int, tcp_inflight_enable) = 0;
  227 #define V_tcp_inflight_enable           VNET(tcp_inflight_enable)
  228 SYSCTL_VNET_INT(_net_inet_tcp_inflight, OID_AUTO, enable, CTLFLAG_RW,
  229     &VNET_NAME(tcp_inflight_enable), 0,
  230     "Enable automatic TCP inflight data limiting");
  231 
  232 static int      tcp_inflight_debug = 0;
  233 SYSCTL_INT(_net_inet_tcp_inflight, OID_AUTO, debug, CTLFLAG_RW,
  234     &tcp_inflight_debug, 0,
  235     "Debug TCP inflight calculations");
  236 
  237 static VNET_DEFINE(int, tcp_inflight_rttthresh);
  238 #define V_tcp_inflight_rttthresh        VNET(tcp_inflight_rttthresh)
  239 SYSCTL_VNET_PROC(_net_inet_tcp_inflight, OID_AUTO, rttthresh,
  240     CTLTYPE_INT|CTLFLAG_RW, &VNET_NAME(tcp_inflight_rttthresh), 0,
  241     vnet_sysctl_msec_to_ticks, "I",
  242     "RTT threshold below which inflight will deactivate itself");
  243 
  244 static VNET_DEFINE(int, tcp_inflight_min) = 6144;
  245 #define V_tcp_inflight_min              VNET(tcp_inflight_min)
  246 SYSCTL_VNET_INT(_net_inet_tcp_inflight, OID_AUTO, min, CTLFLAG_RW,
  247     &VNET_NAME(tcp_inflight_min), 0,
  248     "Lower-bound for TCP inflight window");
  249 
  250 static VNET_DEFINE(int, tcp_inflight_max) = TCP_MAXWIN << TCP_MAX_WINSHIFT;
  251 #define V_tcp_inflight_max              VNET(tcp_inflight_max)
  252 SYSCTL_VNET_INT(_net_inet_tcp_inflight, OID_AUTO, max, CTLFLAG_RW,
  253     &VNET_NAME(tcp_inflight_max), 0,
  254     "Upper-bound for TCP inflight window");
  255 
  256 static VNET_DEFINE(int, tcp_inflight_stab) = 20;
  257 #define V_tcp_inflight_stab             VNET(tcp_inflight_stab)
  258 SYSCTL_VNET_INT(_net_inet_tcp_inflight, OID_AUTO, stab, CTLFLAG_RW,
  259     &VNET_NAME(tcp_inflight_stab), 0,
  260     "Inflight Algorithm Stabilization 20 = 2 packets");
  261 
  262 #ifdef TCP_SIGNATURE
  263 static int      tcp_sig_checksigs = 1;
  264 SYSCTL_INT(_net_inet_tcp, OID_AUTO, signature_verify_input, CTLFLAG_RW,
  265     &tcp_sig_checksigs, 0, "Verify RFC2385 digests on inbound traffic");
  266 #endif
  267 
  268 VNET_DEFINE(uma_zone_t, sack_hole_zone);
  269 #define V_sack_hole_zone                VNET(sack_hole_zone)
  270 
  271 VNET_DEFINE(struct hhook_head *, tcp_hhh[HHOOK_TCP_LAST+1]);
  272 
  273 static struct inpcb *tcp_notify(struct inpcb *, int);
  274 static struct inpcb *tcp_mtudisc_notify(struct inpcb *, int);
  275 static void     tcp_isn_tick(void *);
  276 static char *   tcp_log_addr(struct in_conninfo *inc, struct tcphdr *th,
  277                     void *ip4hdr, const void *ip6hdr);
  278 
  279 /*
  280  * Target size of TCP PCB hash tables. Must be a power of two.
  281  *
  282  * Note that this can be overridden by the kernel environment
  283  * variable net.inet.tcp.tcbhashsize
  284  */
  285 #ifndef TCBHASHSIZE
  286 #define TCBHASHSIZE     512
  287 #endif
  288 
  289 /*
  290  * XXX
  291  * Callouts should be moved into struct tcp directly.  They are currently
  292  * separate because the tcpcb structure is exported to userland for sysctl
  293  * parsing purposes, which do not know about callouts.
  294  */
  295 struct tcpcb_mem {
  296         struct  tcpcb           tcb;
  297         struct  tcp_timer       tt;
  298         struct  cc_var          ccv;
  299         struct  osd             osd;
  300 };
  301 
  302 static VNET_DEFINE(uma_zone_t, tcpcb_zone);
  303 #define V_tcpcb_zone                    VNET(tcpcb_zone)
  304 
  305 MALLOC_DEFINE(M_TCPLOG, "tcplog", "TCP address and flags print buffers");
  306 struct callout isn_callout;
  307 static struct mtx isn_mtx;
  308 
  309 #define ISN_LOCK_INIT() mtx_init(&isn_mtx, "isn_mtx", NULL, MTX_DEF)
  310 #define ISN_LOCK()      mtx_lock(&isn_mtx)
  311 #define ISN_UNLOCK()    mtx_unlock(&isn_mtx)
  312 
  313 /*
  314  * TCP initialization.
  315  */
  316 static void
  317 tcp_zone_change(void *tag)
  318 {
  319 
  320         uma_zone_set_max(V_tcbinfo.ipi_zone, maxsockets);
  321         uma_zone_set_max(V_tcpcb_zone, maxsockets);
  322         tcp_tw_zone_change();
  323 }
  324 
  325 static int
  326 tcp_inpcb_init(void *mem, int size, int flags)
  327 {
  328         struct inpcb *inp = mem;
  329 
  330         INP_LOCK_INIT(inp, "inp", "tcpinp");
  331         return (0);
  332 }
  333 
  334 void
  335 tcp_init(void)
  336 {
  337         int hashsize;
  338 
  339         INP_INFO_LOCK_INIT(&V_tcbinfo, "tcp");
  340         LIST_INIT(&V_tcb);
  341 #ifdef VIMAGE
  342         V_tcbinfo.ipi_vnet = curvnet;
  343 #endif
  344         V_tcbinfo.ipi_listhead = &V_tcb;
  345 
  346         if (hhook_head_register(HHOOK_TYPE_TCP, HHOOK_TCP_EST_IN,
  347             &V_tcp_hhh[HHOOK_TCP_EST_IN], HHOOK_NOWAIT|HHOOK_HEADISINVNET) != 0)
  348                 printf("%s: WARNING: unable to register helper hook\n", __func__);
  349         if (hhook_head_register(HHOOK_TYPE_TCP, HHOOK_TCP_EST_OUT,
  350             &V_tcp_hhh[HHOOK_TCP_EST_OUT], HHOOK_NOWAIT|HHOOK_HEADISINVNET) != 0)
  351                 printf("%s: WARNING: unable to register helper hook\n", __func__);
  352 
  353         hashsize = TCBHASHSIZE;
  354         TUNABLE_INT_FETCH("net.inet.tcp.tcbhashsize", &hashsize);
  355         if (!powerof2(hashsize)) {
  356                 printf("WARNING: TCB hash size not a power of 2\n");
  357                 hashsize = 512; /* safe default */
  358         }
  359         V_tcbinfo.ipi_hashbase = hashinit(hashsize, M_PCB,
  360             &V_tcbinfo.ipi_hashmask);
  361         V_tcbinfo.ipi_porthashbase = hashinit(hashsize, M_PCB,
  362             &V_tcbinfo.ipi_porthashmask);
  363         V_tcbinfo.ipi_zone = uma_zcreate("tcp_inpcb", sizeof(struct inpcb),
  364             NULL, NULL, tcp_inpcb_init, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
  365         uma_zone_set_max(V_tcbinfo.ipi_zone, maxsockets);
  366         V_tcp_inflight_rttthresh = TCPTV_INFLIGHT_RTTTHRESH;
  367 
  368         /*
  369          * These have to be type stable for the benefit of the timers.
  370          */
  371         V_tcpcb_zone = uma_zcreate("tcpcb", sizeof(struct tcpcb_mem),
  372             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
  373         uma_zone_set_max(V_tcpcb_zone, maxsockets);
  374 
  375         tcp_tw_init();
  376         syncache_init();
  377         tcp_hc_init();
  378         tcp_reass_init();
  379 
  380         TUNABLE_INT_FETCH("net.inet.tcp.sack.enable", &V_tcp_do_sack);
  381         V_sack_hole_zone = uma_zcreate("sackhole", sizeof(struct sackhole),
  382             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
  383 
  384         /* Skip initialization of globals for non-default instances. */
  385         if (!IS_DEFAULT_VNET(curvnet))
  386                 return;
  387 
  388         /* XXX virtualize those bellow? */
  389         tcp_delacktime = TCPTV_DELACK;
  390         tcp_keepinit = TCPTV_KEEP_INIT;
  391         tcp_keepidle = TCPTV_KEEP_IDLE;
  392         tcp_keepintvl = TCPTV_KEEPINTVL;
  393         tcp_maxpersistidle = TCPTV_KEEP_IDLE;
  394         tcp_msl = TCPTV_MSL;
  395         tcp_rexmit_min = TCPTV_MIN;
  396         if (tcp_rexmit_min < 1)
  397                 tcp_rexmit_min = 1;
  398         tcp_rexmit_slop = TCPTV_CPU_VAR;
  399         tcp_finwait2_timeout = TCPTV_FINWAIT2_TIMEOUT;
  400         tcp_tcbhashsize = hashsize;
  401 
  402 #ifdef INET6
  403 #define TCP_MINPROTOHDR (sizeof(struct ip6_hdr) + sizeof(struct tcphdr))
  404 #else /* INET6 */
  405 #define TCP_MINPROTOHDR (sizeof(struct tcpiphdr))
  406 #endif /* INET6 */
  407         if (max_protohdr < TCP_MINPROTOHDR)
  408                 max_protohdr = TCP_MINPROTOHDR;
  409         if (max_linkhdr + TCP_MINPROTOHDR > MHLEN)
  410                 panic("tcp_init");
  411 #undef TCP_MINPROTOHDR
  412 
  413         ISN_LOCK_INIT();
  414         callout_init(&isn_callout, CALLOUT_MPSAFE);
  415         callout_reset(&isn_callout, hz/100, tcp_isn_tick, NULL);
  416         EVENTHANDLER_REGISTER(shutdown_pre_sync, tcp_fini, NULL,
  417                 SHUTDOWN_PRI_DEFAULT);
  418         EVENTHANDLER_REGISTER(maxsockets_change, tcp_zone_change, NULL,
  419                 EVENTHANDLER_PRI_ANY);
  420 }
  421 
  422 #ifdef VIMAGE
  423 void
  424 tcp_destroy(void)
  425 {
  426 
  427         tcp_reass_destroy();
  428         tcp_hc_destroy();
  429         syncache_destroy();
  430         tcp_tw_destroy();
  431 
  432         /* XXX check that hashes are empty! */
  433         hashdestroy(V_tcbinfo.ipi_hashbase, M_PCB,
  434             V_tcbinfo.ipi_hashmask);
  435         hashdestroy(V_tcbinfo.ipi_porthashbase, M_PCB,
  436             V_tcbinfo.ipi_porthashmask);
  437 
  438         uma_zdestroy(V_sack_hole_zone);
  439         uma_zdestroy(V_tcpcb_zone);
  440         uma_zdestroy(V_tcbinfo.ipi_zone);
  441 
  442         INP_INFO_LOCK_DESTROY(&V_tcbinfo);
  443 }
  444 #endif
  445 
  446 void
  447 tcp_fini(void *xtp)
  448 {
  449 
  450         callout_stop(&isn_callout);
  451 }
  452 
  453 /*
  454  * Fill in the IP and TCP headers for an outgoing packet, given the tcpcb.
  455  * tcp_template used to store this data in mbufs, but we now recopy it out
  456  * of the tcpcb each time to conserve mbufs.
  457  */
  458 void
  459 tcpip_fillheaders(struct inpcb *inp, void *ip_ptr, void *tcp_ptr)
  460 {
  461         struct tcphdr *th = (struct tcphdr *)tcp_ptr;
  462 
  463         INP_WLOCK_ASSERT(inp);
  464 
  465 #ifdef INET6
  466         if ((inp->inp_vflag & INP_IPV6) != 0) {
  467                 struct ip6_hdr *ip6;
  468 
  469                 ip6 = (struct ip6_hdr *)ip_ptr;
  470                 ip6->ip6_flow = (ip6->ip6_flow & ~IPV6_FLOWINFO_MASK) |
  471                         (inp->inp_flow & IPV6_FLOWINFO_MASK);
  472                 ip6->ip6_vfc = (ip6->ip6_vfc & ~IPV6_VERSION_MASK) |
  473                         (IPV6_VERSION & IPV6_VERSION_MASK);
  474                 ip6->ip6_nxt = IPPROTO_TCP;
  475                 ip6->ip6_plen = htons(sizeof(struct tcphdr));
  476                 ip6->ip6_src = inp->in6p_laddr;
  477                 ip6->ip6_dst = inp->in6p_faddr;
  478         } else
  479 #endif
  480         {
  481                 struct ip *ip;
  482 
  483                 ip = (struct ip *)ip_ptr;
  484                 ip->ip_v = IPVERSION;
  485                 ip->ip_hl = 5;
  486                 ip->ip_tos = inp->inp_ip_tos;
  487                 ip->ip_len = 0;
  488                 ip->ip_id = 0;
  489                 ip->ip_off = 0;
  490                 ip->ip_ttl = inp->inp_ip_ttl;
  491                 ip->ip_sum = 0;
  492                 ip->ip_p = IPPROTO_TCP;
  493                 ip->ip_src = inp->inp_laddr;
  494                 ip->ip_dst = inp->inp_faddr;
  495         }
  496         th->th_sport = inp->inp_lport;
  497         th->th_dport = inp->inp_fport;
  498         th->th_seq = 0;
  499         th->th_ack = 0;
  500         th->th_x2 = 0;
  501         th->th_off = 5;
  502         th->th_flags = 0;
  503         th->th_win = 0;
  504         th->th_urp = 0;
  505         th->th_sum = 0;         /* in_pseudo() is called later for ipv4 */
  506 }
  507 
  508 /*
  509  * Create template to be used to send tcp packets on a connection.
  510  * Allocates an mbuf and fills in a skeletal tcp/ip header.  The only
  511  * use for this function is in keepalives, which use tcp_respond.
  512  */
  513 struct tcptemp *
  514 tcpip_maketemplate(struct inpcb *inp)
  515 {
  516         struct tcptemp *t;
  517 
  518         t = malloc(sizeof(*t), M_TEMP, M_NOWAIT);
  519         if (t == NULL)
  520                 return (NULL);
  521         tcpip_fillheaders(inp, (void *)&t->tt_ipgen, (void *)&t->tt_t);
  522         return (t);
  523 }
  524 
  525 /*
  526  * Send a single message to the TCP at address specified by
  527  * the given TCP/IP header.  If m == NULL, then we make a copy
  528  * of the tcpiphdr at ti and send directly to the addressed host.
  529  * This is used to force keep alive messages out using the TCP
  530  * template for a connection.  If flags are given then we send
  531  * a message back to the TCP which originated the * segment ti,
  532  * and discard the mbuf containing it and any other attached mbufs.
  533  *
  534  * In any case the ack and sequence number of the transmitted
  535  * segment are as specified by the parameters.
  536  *
  537  * NOTE: If m != NULL, then ti must point to *inside* the mbuf.
  538  */
  539 void
  540 tcp_respond(struct tcpcb *tp, void *ipgen, struct tcphdr *th, struct mbuf *m,
  541     tcp_seq ack, tcp_seq seq, int flags)
  542 {
  543         int tlen;
  544         int win = 0;
  545         struct ip *ip;
  546         struct tcphdr *nth;
  547 #ifdef INET6
  548         struct ip6_hdr *ip6;
  549         int isipv6;
  550 #endif /* INET6 */
  551         int ipflags = 0;
  552         struct inpcb *inp;
  553 
  554         KASSERT(tp != NULL || m != NULL, ("tcp_respond: tp and m both NULL"));
  555 
  556 #ifdef INET6
  557         isipv6 = ((struct ip *)ipgen)->ip_v == 6;
  558         ip6 = ipgen;
  559 #endif /* INET6 */
  560         ip = ipgen;
  561 
  562         if (tp != NULL) {
  563                 inp = tp->t_inpcb;
  564                 KASSERT(inp != NULL, ("tcp control block w/o inpcb"));
  565                 INP_WLOCK_ASSERT(inp);
  566         } else
  567                 inp = NULL;
  568 
  569         if (tp != NULL) {
  570                 if (!(flags & TH_RST)) {
  571                         win = sbspace(&inp->inp_socket->so_rcv);
  572                         if (win > (long)TCP_MAXWIN << tp->rcv_scale)
  573                                 win = (long)TCP_MAXWIN << tp->rcv_scale;
  574                 }
  575         }
  576         if (m == NULL) {
  577                 m = m_gethdr(M_DONTWAIT, MT_DATA);
  578                 if (m == NULL)
  579                         return;
  580                 tlen = 0;
  581                 m->m_data += max_linkhdr;
  582 #ifdef INET6
  583                 if (isipv6) {
  584                         bcopy((caddr_t)ip6, mtod(m, caddr_t),
  585                               sizeof(struct ip6_hdr));
  586                         ip6 = mtod(m, struct ip6_hdr *);
  587                         nth = (struct tcphdr *)(ip6 + 1);
  588                 } else
  589 #endif /* INET6 */
  590               {
  591                 bcopy((caddr_t)ip, mtod(m, caddr_t), sizeof(struct ip));
  592                 ip = mtod(m, struct ip *);
  593                 nth = (struct tcphdr *)(ip + 1);
  594               }
  595                 bcopy((caddr_t)th, (caddr_t)nth, sizeof(struct tcphdr));
  596                 flags = TH_ACK;
  597         } else {
  598                 /*
  599                  *  reuse the mbuf. 
  600                  * XXX MRT We inherrit the FIB, which is lucky.
  601                  */
  602                 m_freem(m->m_next);
  603                 m->m_next = NULL;
  604                 m->m_data = (caddr_t)ipgen;
  605                 /* m_len is set later */
  606                 tlen = 0;
  607 #define xchg(a,b,type) { type t; t=a; a=b; b=t; }
  608 #ifdef INET6
  609                 if (isipv6) {
  610                         xchg(ip6->ip6_dst, ip6->ip6_src, struct in6_addr);
  611                         nth = (struct tcphdr *)(ip6 + 1);
  612                 } else
  613 #endif /* INET6 */
  614               {
  615                 xchg(ip->ip_dst.s_addr, ip->ip_src.s_addr, uint32_t);
  616                 nth = (struct tcphdr *)(ip + 1);
  617               }
  618                 if (th != nth) {
  619                         /*
  620                          * this is usually a case when an extension header
  621                          * exists between the IPv6 header and the
  622                          * TCP header.
  623                          */
  624                         nth->th_sport = th->th_sport;
  625                         nth->th_dport = th->th_dport;
  626                 }
  627                 xchg(nth->th_dport, nth->th_sport, uint16_t);
  628 #undef xchg
  629         }
  630 #ifdef INET6
  631         if (isipv6) {
  632                 ip6->ip6_flow = 0;
  633                 ip6->ip6_vfc = IPV6_VERSION;
  634                 ip6->ip6_nxt = IPPROTO_TCP;
  635                 ip6->ip6_plen = htons((u_short)(sizeof (struct tcphdr) +
  636                                                 tlen));
  637                 tlen += sizeof (struct ip6_hdr) + sizeof (struct tcphdr);
  638         } else
  639 #endif
  640         {
  641                 tlen += sizeof (struct tcpiphdr);
  642                 ip->ip_len = tlen;
  643                 ip->ip_ttl = V_ip_defttl;
  644                 if (V_path_mtu_discovery)
  645                         ip->ip_off |= IP_DF;
  646         }
  647         m->m_len = tlen;
  648         m->m_pkthdr.len = tlen;
  649         m->m_pkthdr.rcvif = NULL;
  650 #ifdef MAC
  651         if (inp != NULL) {
  652                 /*
  653                  * Packet is associated with a socket, so allow the
  654                  * label of the response to reflect the socket label.
  655                  */
  656                 INP_WLOCK_ASSERT(inp);
  657                 mac_inpcb_create_mbuf(inp, m);
  658         } else {
  659                 /*
  660                  * Packet is not associated with a socket, so possibly
  661                  * update the label in place.
  662                  */
  663                 mac_netinet_tcp_reply(m);
  664         }
  665 #endif
  666         nth->th_seq = htonl(seq);
  667         nth->th_ack = htonl(ack);
  668         nth->th_x2 = 0;
  669         nth->th_off = sizeof (struct tcphdr) >> 2;
  670         nth->th_flags = flags;
  671         if (tp != NULL)
  672                 nth->th_win = htons((u_short) (win >> tp->rcv_scale));
  673         else
  674                 nth->th_win = htons((u_short)win);
  675         nth->th_urp = 0;
  676 #ifdef INET6
  677         if (isipv6) {
  678                 nth->th_sum = 0;
  679                 nth->th_sum = in6_cksum(m, IPPROTO_TCP,
  680                                         sizeof(struct ip6_hdr),
  681                                         tlen - sizeof(struct ip6_hdr));
  682                 ip6->ip6_hlim = in6_selecthlim(tp != NULL ? tp->t_inpcb :
  683                     NULL, NULL);
  684         } else
  685 #endif /* INET6 */
  686         {
  687                 nth->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr,
  688                     htons((u_short)(tlen - sizeof(struct ip) + ip->ip_p)));
  689                 m->m_pkthdr.csum_flags = CSUM_TCP;
  690                 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum);
  691         }
  692 #ifdef TCPDEBUG
  693         if (tp == NULL || (inp->inp_socket->so_options & SO_DEBUG))
  694                 tcp_trace(TA_OUTPUT, 0, tp, mtod(m, void *), th, 0);
  695 #endif
  696 #ifdef INET6
  697         if (isipv6)
  698                 (void) ip6_output(m, NULL, NULL, ipflags, NULL, NULL, inp);
  699         else
  700 #endif /* INET6 */
  701         (void) ip_output(m, NULL, NULL, ipflags, NULL, inp);
  702 }
  703 
  704 /*
  705  * Create a new TCP control block, making an
  706  * empty reassembly queue and hooking it to the argument
  707  * protocol control block.  The `inp' parameter must have
  708  * come from the zone allocator set up in tcp_init().
  709  */
  710 struct tcpcb *
  711 tcp_newtcpcb(struct inpcb *inp)
  712 {
  713         struct tcpcb_mem *tm;
  714         struct tcpcb *tp;
  715 #ifdef INET6
  716         int isipv6 = (inp->inp_vflag & INP_IPV6) != 0;
  717 #endif /* INET6 */
  718 
  719         tm = uma_zalloc(V_tcpcb_zone, M_NOWAIT | M_ZERO);
  720         if (tm == NULL)
  721                 return (NULL);
  722         tp = &tm->tcb;
  723 
  724         /* Initialise cc_var struct for this tcpcb. */
  725         tp->ccv = &tm->ccv;
  726         tp->ccv->type = IPPROTO_TCP;
  727         tp->ccv->ccvc.tcp = tp;
  728 
  729         /*
  730          * Use the current system default CC algorithm.
  731          */
  732         CC_LIST_RLOCK();
  733         KASSERT(!STAILQ_EMPTY(&cc_list), ("cc_list is empty!"));
  734         CC_ALGO(tp) = CC_DEFAULT();
  735         CC_LIST_RUNLOCK();
  736 
  737         if (CC_ALGO(tp)->cb_init != NULL)
  738                 if (CC_ALGO(tp)->cb_init(tp->ccv) > 0) {
  739                         uma_zfree(V_tcpcb_zone, tm);
  740                         return (NULL);
  741                 }
  742 
  743         tp->osd = &tm->osd;
  744         if (khelp_init_osd(HELPER_CLASS_TCP, tp->osd)) {
  745                 uma_zfree(V_tcpcb_zone, tm);
  746                 return (NULL);
  747         }
  748 
  749 #ifdef VIMAGE
  750         tp->t_vnet = inp->inp_vnet;
  751 #endif
  752         tp->t_timers = &tm->tt;
  753         /*      LIST_INIT(&tp->t_segq); */      /* XXX covered by M_ZERO */
  754         tp->t_maxseg = tp->t_maxopd =
  755 #ifdef INET6
  756                 isipv6 ? V_tcp_v6mssdflt :
  757 #endif /* INET6 */
  758                 V_tcp_mssdflt;
  759 
  760         /* Set up our timeouts. */
  761         callout_init(&tp->t_timers->tt_rexmt, CALLOUT_MPSAFE);
  762         callout_init(&tp->t_timers->tt_persist, CALLOUT_MPSAFE);
  763         callout_init(&tp->t_timers->tt_keep, CALLOUT_MPSAFE);
  764         callout_init(&tp->t_timers->tt_2msl, CALLOUT_MPSAFE);
  765         callout_init(&tp->t_timers->tt_delack, CALLOUT_MPSAFE);
  766 
  767         if (V_tcp_do_rfc1323)
  768                 tp->t_flags = (TF_REQ_SCALE|TF_REQ_TSTMP);
  769         if (V_tcp_do_sack)
  770                 tp->t_flags |= TF_SACK_PERMIT;
  771         TAILQ_INIT(&tp->snd_holes);
  772         tp->t_inpcb = inp;      /* XXX */
  773         /*
  774          * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no
  775          * rtt estimate.  Set rttvar so that srtt + 4 * rttvar gives
  776          * reasonable initial retransmit time.
  777          */
  778         tp->t_srtt = TCPTV_SRTTBASE;
  779         tp->t_rttvar = ((TCPTV_RTOBASE - TCPTV_SRTTBASE) << TCP_RTTVAR_SHIFT) / 4;
  780         tp->t_rttmin = tcp_rexmit_min;
  781         tp->t_rxtcur = TCPTV_RTOBASE;
  782         tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
  783         tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
  784         tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT;
  785         tp->t_rcvtime = ticks;
  786         tp->t_bw_rtttime = ticks;
  787         /*
  788          * IPv4 TTL initialization is necessary for an IPv6 socket as well,
  789          * because the socket may be bound to an IPv6 wildcard address,
  790          * which may match an IPv4-mapped IPv6 address.
  791          */
  792         inp->inp_ip_ttl = V_ip_defttl;
  793         inp->inp_ppcb = tp;
  794         return (tp);            /* XXX */
  795 }
  796 
  797 /*
  798  * Switch the congestion control algorithm back to NewReno for any active
  799  * control blocks using an algorithm which is about to go away.
  800  * This ensures the CC framework can allow the unload to proceed without leaving
  801  * any dangling pointers which would trigger a panic.
  802  * Returning non-zero would inform the CC framework that something went wrong
  803  * and it would be unsafe to allow the unload to proceed. However, there is no
  804  * way for this to occur with this implementation so we always return zero.
  805  */
  806 int
  807 tcp_ccalgounload(struct cc_algo *unload_algo)
  808 {
  809         struct cc_algo *tmpalgo;
  810         struct inpcb *inp;
  811         struct tcpcb *tp;
  812         VNET_ITERATOR_DECL(vnet_iter);
  813 
  814         /*
  815          * Check all active control blocks across all network stacks and change
  816          * any that are using "unload_algo" back to NewReno. If "unload_algo"
  817          * requires cleanup code to be run, call it.
  818          */
  819         VNET_LIST_RLOCK();
  820         VNET_FOREACH(vnet_iter) {
  821                 CURVNET_SET(vnet_iter);
  822                 INP_INFO_RLOCK(&V_tcbinfo);
  823                 /*
  824                  * New connections already part way through being initialised
  825                  * with the CC algo we're removing will not race with this code
  826                  * because the INP_INFO_WLOCK is held during initialisation. We
  827                  * therefore don't enter the loop below until the connection
  828                  * list has stabilised.
  829                  */
  830                 LIST_FOREACH(inp, &V_tcb, inp_list) {
  831                         INP_WLOCK(inp);
  832                         /* Important to skip tcptw structs. */
  833                         if (!(inp->inp_flags & INP_TIMEWAIT) &&
  834                             (tp = intotcpcb(inp)) != NULL) {
  835                                 /*
  836                                  * By holding INP_WLOCK here, we are assured
  837                                  * that the connection is not currently
  838                                  * executing inside the CC module's functions
  839                                  * i.e. it is safe to make the switch back to
  840                                  * NewReno.
  841                                  */
  842                                 if (CC_ALGO(tp) == unload_algo) {
  843                                         tmpalgo = CC_ALGO(tp);
  844                                         /* NewReno does not require any init. */
  845                                         CC_ALGO(tp) = &newreno_cc_algo;
  846                                         if (tmpalgo->cb_destroy != NULL)
  847                                                 tmpalgo->cb_destroy(tp->ccv);
  848                                 }
  849                         }
  850                         INP_WUNLOCK(inp);
  851                 }
  852                 INP_INFO_RUNLOCK(&V_tcbinfo);
  853                 CURVNET_RESTORE();
  854         }
  855         VNET_LIST_RUNLOCK();
  856 
  857         return (0);
  858 }
  859 
  860 /*
  861  * Drop a TCP connection, reporting
  862  * the specified error.  If connection is synchronized,
  863  * then send a RST to peer.
  864  */
  865 struct tcpcb *
  866 tcp_drop(struct tcpcb *tp, int errno)
  867 {
  868         struct socket *so = tp->t_inpcb->inp_socket;
  869 
  870         INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
  871         INP_WLOCK_ASSERT(tp->t_inpcb);
  872 
  873         if (TCPS_HAVERCVDSYN(tp->t_state)) {
  874                 tp->t_state = TCPS_CLOSED;
  875                 (void) tcp_output_reset(tp);
  876                 TCPSTAT_INC(tcps_drops);
  877         } else
  878                 TCPSTAT_INC(tcps_conndrops);
  879         if (errno == ETIMEDOUT && tp->t_softerror)
  880                 errno = tp->t_softerror;
  881         so->so_error = errno;
  882         return (tcp_close(tp));
  883 }
  884 
  885 void
  886 tcp_discardcb(struct tcpcb *tp)
  887 {
  888         struct inpcb *inp = tp->t_inpcb;
  889         struct socket *so = inp->inp_socket;
  890 #ifdef INET6
  891         int isipv6 = (inp->inp_vflag & INP_IPV6) != 0;
  892 #endif /* INET6 */
  893 
  894         INP_WLOCK_ASSERT(inp);
  895 
  896         /*
  897          * Make sure that all of our timers are stopped before we
  898          * delete the PCB.
  899          */
  900         callout_stop(&tp->t_timers->tt_rexmt);
  901         callout_stop(&tp->t_timers->tt_persist);
  902         callout_stop(&tp->t_timers->tt_keep);
  903         callout_stop(&tp->t_timers->tt_2msl);
  904         callout_stop(&tp->t_timers->tt_delack);
  905 
  906         /*
  907          * If we got enough samples through the srtt filter,
  908          * save the rtt and rttvar in the routing entry.
  909          * 'Enough' is arbitrarily defined as 4 rtt samples.
  910          * 4 samples is enough for the srtt filter to converge
  911          * to within enough % of the correct value; fewer samples
  912          * and we could save a bogus rtt. The danger is not high
  913          * as tcp quickly recovers from everything.
  914          * XXX: Works very well but needs some more statistics!
  915          */
  916         if (tp->t_rttupdated >= 4) {
  917                 struct hc_metrics_lite metrics;
  918                 u_long ssthresh;
  919 
  920                 bzero(&metrics, sizeof(metrics));
  921                 /*
  922                  * Update the ssthresh always when the conditions below
  923                  * are satisfied. This gives us better new start value
  924                  * for the congestion avoidance for new connections.
  925                  * ssthresh is only set if packet loss occured on a session.
  926                  *
  927                  * XXXRW: 'so' may be NULL here, and/or socket buffer may be
  928                  * being torn down.  Ideally this code would not use 'so'.
  929                  */
  930                 ssthresh = tp->snd_ssthresh;
  931                 if (ssthresh != 0 && ssthresh < so->so_snd.sb_hiwat / 2) {
  932                         /*
  933                          * convert the limit from user data bytes to
  934                          * packets then to packet data bytes.
  935                          */
  936                         ssthresh = (ssthresh + tp->t_maxseg / 2) / tp->t_maxseg;
  937                         if (ssthresh < 2)
  938                                 ssthresh = 2;
  939                         ssthresh *= (u_long)(tp->t_maxseg +
  940 #ifdef INET6
  941                                       (isipv6 ? sizeof (struct ip6_hdr) +
  942                                                sizeof (struct tcphdr) :
  943 #endif
  944                                        sizeof (struct tcpiphdr)
  945 #ifdef INET6
  946                                        )
  947 #endif
  948                                       );
  949                 } else
  950                         ssthresh = 0;
  951                 metrics.rmx_ssthresh = ssthresh;
  952 
  953                 metrics.rmx_rtt = tp->t_srtt;
  954                 metrics.rmx_rttvar = tp->t_rttvar;
  955                 /* XXX: This wraps if the pipe is more than 4 Gbit per second */
  956                 metrics.rmx_bandwidth = tp->snd_bandwidth;
  957                 metrics.rmx_cwnd = tp->snd_cwnd;
  958                 metrics.rmx_sendpipe = 0;
  959                 metrics.rmx_recvpipe = 0;
  960 
  961                 tcp_hc_update(&inp->inp_inc, &metrics);
  962         }
  963 
  964         /* free the reassembly queue, if any */
  965         tcp_reass_flush(tp);
  966         /* Disconnect offload device, if any. */
  967         tcp_offload_detach(tp);
  968                 
  969         tcp_free_sackholes(tp);
  970 
  971         /* Allow the CC algorithm to clean up after itself. */
  972         if (CC_ALGO(tp)->cb_destroy != NULL)
  973                 CC_ALGO(tp)->cb_destroy(tp->ccv);
  974 
  975         khelp_destroy_osd(tp->osd);
  976 
  977         CC_ALGO(tp) = NULL;
  978         inp->inp_ppcb = NULL;
  979         tp->t_inpcb = NULL;
  980         uma_zfree(V_tcpcb_zone, tp);
  981 }
  982 
  983 /*
  984  * Attempt to close a TCP control block, marking it as dropped, and freeing
  985  * the socket if we hold the only reference.
  986  */
  987 struct tcpcb *
  988 tcp_close(struct tcpcb *tp)
  989 {
  990         struct inpcb *inp = tp->t_inpcb;
  991         struct socket *so;
  992 
  993         INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
  994         INP_WLOCK_ASSERT(inp);
  995 
  996         /* Notify any offload devices of listener close */
  997         if (tp->t_state == TCPS_LISTEN)
  998                 tcp_offload_listen_close(tp);
  999         in_pcbdrop(inp);
 1000         TCPSTAT_INC(tcps_closed);
 1001         KASSERT(inp->inp_socket != NULL, ("tcp_close: inp_socket NULL"));
 1002         so = inp->inp_socket;
 1003         soisdisconnected(so);
 1004         if (inp->inp_flags & INP_SOCKREF) {
 1005                 KASSERT(so->so_state & SS_PROTOREF,
 1006                     ("tcp_close: !SS_PROTOREF"));
 1007                 inp->inp_flags &= ~INP_SOCKREF;
 1008                 INP_WUNLOCK(inp);
 1009                 ACCEPT_LOCK();
 1010                 SOCK_LOCK(so);
 1011                 so->so_state &= ~SS_PROTOREF;
 1012                 sofree(so);
 1013                 return (NULL);
 1014         }
 1015         return (tp);
 1016 }
 1017 
 1018 void
 1019 tcp_drain(void)
 1020 {
 1021         VNET_ITERATOR_DECL(vnet_iter);
 1022 
 1023         if (!do_tcpdrain)
 1024                 return;
 1025 
 1026         VNET_LIST_RLOCK_NOSLEEP();
 1027         VNET_FOREACH(vnet_iter) {
 1028                 CURVNET_SET(vnet_iter);
 1029                 struct inpcb *inpb;
 1030                 struct tcpcb *tcpb;
 1031 
 1032         /*
 1033          * Walk the tcpbs, if existing, and flush the reassembly queue,
 1034          * if there is one...
 1035          * XXX: The "Net/3" implementation doesn't imply that the TCP
 1036          *      reassembly queue should be flushed, but in a situation
 1037          *      where we're really low on mbufs, this is potentially
 1038          *      usefull.
 1039          */
 1040                 INP_INFO_RLOCK(&V_tcbinfo);
 1041                 LIST_FOREACH(inpb, V_tcbinfo.ipi_listhead, inp_list) {
 1042                         if (inpb->inp_flags & INP_TIMEWAIT)
 1043                                 continue;
 1044                         INP_WLOCK(inpb);
 1045                         if ((tcpb = intotcpcb(inpb)) != NULL) {
 1046                                 tcp_reass_flush(tcpb);
 1047                                 tcp_clean_sackreport(tcpb);
 1048                         }
 1049                         INP_WUNLOCK(inpb);
 1050                 }
 1051                 INP_INFO_RUNLOCK(&V_tcbinfo);
 1052                 CURVNET_RESTORE();
 1053         }
 1054         VNET_LIST_RUNLOCK_NOSLEEP();
 1055 }
 1056 
 1057 /*
 1058  * Notify a tcp user of an asynchronous error;
 1059  * store error as soft error, but wake up user
 1060  * (for now, won't do anything until can select for soft error).
 1061  *
 1062  * Do not wake up user since there currently is no mechanism for
 1063  * reporting soft errors (yet - a kqueue filter may be added).
 1064  */
 1065 static struct inpcb *
 1066 tcp_notify(struct inpcb *inp, int error)
 1067 {
 1068         struct tcpcb *tp;
 1069 
 1070         INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
 1071         INP_WLOCK_ASSERT(inp);
 1072 
 1073         if ((inp->inp_flags & INP_TIMEWAIT) ||
 1074             (inp->inp_flags & INP_DROPPED))
 1075                 return (inp);
 1076 
 1077         tp = intotcpcb(inp);
 1078         KASSERT(tp != NULL, ("tcp_notify: tp == NULL"));
 1079 
 1080         /*
 1081          * Ignore some errors if we are hooked up.
 1082          * If connection hasn't completed, has retransmitted several times,
 1083          * and receives a second error, give up now.  This is better
 1084          * than waiting a long time to establish a connection that
 1085          * can never complete.
 1086          */
 1087         if (tp->t_state == TCPS_ESTABLISHED &&
 1088             (error == EHOSTUNREACH || error == ENETUNREACH ||
 1089              error == EHOSTDOWN)) {
 1090                 return (inp);
 1091         } else if (tp->t_state < TCPS_ESTABLISHED && tp->t_rxtshift > 3 &&
 1092             tp->t_softerror) {
 1093                 tp = tcp_drop(tp, error);
 1094                 if (tp != NULL)
 1095                         return (inp);
 1096                 else
 1097                         return (NULL);
 1098         } else {
 1099                 tp->t_softerror = error;
 1100                 return (inp);
 1101         }
 1102 #if 0
 1103         wakeup( &so->so_timeo);
 1104         sorwakeup(so);
 1105         sowwakeup(so);
 1106 #endif
 1107 }
 1108 
 1109 static int
 1110 tcp_pcblist(SYSCTL_HANDLER_ARGS)
 1111 {
 1112         int error, i, m, n, pcb_count;
 1113         struct inpcb *inp, **inp_list;
 1114         inp_gen_t gencnt;
 1115         struct xinpgen xig;
 1116 
 1117         /*
 1118          * The process of preparing the TCB list is too time-consuming and
 1119          * resource-intensive to repeat twice on every request.
 1120          */
 1121         if (req->oldptr == NULL) {
 1122                 n = V_tcbinfo.ipi_count + syncache_pcbcount();
 1123                 n += imax(n / 8, 10);
 1124                 req->oldidx = 2 * (sizeof xig) + n * sizeof(struct xtcpcb);
 1125                 return (0);
 1126         }
 1127 
 1128         if (req->newptr != NULL)
 1129                 return (EPERM);
 1130 
 1131         /*
 1132          * OK, now we're committed to doing something.
 1133          */
 1134         INP_INFO_RLOCK(&V_tcbinfo);
 1135         gencnt = V_tcbinfo.ipi_gencnt;
 1136         n = V_tcbinfo.ipi_count;
 1137         INP_INFO_RUNLOCK(&V_tcbinfo);
 1138 
 1139         m = syncache_pcbcount();
 1140 
 1141         error = sysctl_wire_old_buffer(req, 2 * (sizeof xig)
 1142                 + (n + m) * sizeof(struct xtcpcb));
 1143         if (error != 0)
 1144                 return (error);
 1145 
 1146         xig.xig_len = sizeof xig;
 1147         xig.xig_count = n + m;
 1148         xig.xig_gen = gencnt;
 1149         xig.xig_sogen = so_gencnt;
 1150         error = SYSCTL_OUT(req, &xig, sizeof xig);
 1151         if (error)
 1152                 return (error);
 1153 
 1154         error = syncache_pcblist(req, m, &pcb_count);
 1155         if (error)
 1156                 return (error);
 1157 
 1158         inp_list = malloc(n * sizeof *inp_list, M_TEMP, M_WAITOK);
 1159         if (inp_list == NULL)
 1160                 return (ENOMEM);
 1161 
 1162         INP_INFO_RLOCK(&V_tcbinfo);
 1163         for (inp = LIST_FIRST(V_tcbinfo.ipi_listhead), i = 0;
 1164             inp != NULL && i < n; inp = LIST_NEXT(inp, inp_list)) {
 1165                 INP_WLOCK(inp);
 1166                 if (inp->inp_gencnt <= gencnt) {
 1167                         /*
 1168                          * XXX: This use of cr_cansee(), introduced with
 1169                          * TCP state changes, is not quite right, but for
 1170                          * now, better than nothing.
 1171                          */
 1172                         if (inp->inp_flags & INP_TIMEWAIT) {
 1173                                 if (intotw(inp) != NULL)
 1174                                         error = cr_cansee(req->td->td_ucred,
 1175                                             intotw(inp)->tw_cred);
 1176                                 else
 1177                                         error = EINVAL; /* Skip this inp. */
 1178                         } else
 1179                                 error = cr_canseeinpcb(req->td->td_ucred, inp);
 1180                         if (error == 0) {
 1181                                 in_pcbref(inp);
 1182                                 inp_list[i++] = inp;
 1183                         }
 1184                 }
 1185                 INP_WUNLOCK(inp);
 1186         }
 1187         INP_INFO_RUNLOCK(&V_tcbinfo);
 1188         n = i;
 1189 
 1190         error = 0;
 1191         for (i = 0; i < n; i++) {
 1192                 inp = inp_list[i];
 1193                 INP_RLOCK(inp);
 1194                 if (inp->inp_gencnt <= gencnt) {
 1195                         struct xtcpcb xt;
 1196                         void *inp_ppcb;
 1197 
 1198                         bzero(&xt, sizeof(xt));
 1199                         xt.xt_len = sizeof xt;
 1200                         /* XXX should avoid extra copy */
 1201                         bcopy(inp, &xt.xt_inp, sizeof *inp);
 1202                         inp_ppcb = inp->inp_ppcb;
 1203                         if (inp_ppcb == NULL)
 1204                                 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp);
 1205                         else if (inp->inp_flags & INP_TIMEWAIT) {
 1206                                 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp);
 1207                                 xt.xt_tp.t_state = TCPS_TIME_WAIT;
 1208                         } else
 1209                                 bcopy(inp_ppcb, &xt.xt_tp, sizeof xt.xt_tp);
 1210                         if (inp->inp_socket != NULL)
 1211                                 sotoxsocket(inp->inp_socket, &xt.xt_socket);
 1212                         else {
 1213                                 bzero(&xt.xt_socket, sizeof xt.xt_socket);
 1214                                 xt.xt_socket.xso_protocol = IPPROTO_TCP;
 1215                         }
 1216                         xt.xt_inp.inp_gencnt = inp->inp_gencnt;
 1217                         INP_RUNLOCK(inp);
 1218                         error = SYSCTL_OUT(req, &xt, sizeof xt);
 1219                 } else
 1220                         INP_RUNLOCK(inp);
 1221         }
 1222         INP_INFO_WLOCK(&V_tcbinfo);
 1223         for (i = 0; i < n; i++) {
 1224                 inp = inp_list[i];
 1225                 INP_WLOCK(inp);
 1226                 if (!in_pcbrele(inp))
 1227                         INP_WUNLOCK(inp);
 1228         }
 1229         INP_INFO_WUNLOCK(&V_tcbinfo);
 1230 
 1231         if (!error) {
 1232                 /*
 1233                  * Give the user an updated idea of our state.
 1234                  * If the generation differs from what we told
 1235                  * her before, she knows that something happened
 1236                  * while we were processing this request, and it
 1237                  * might be necessary to retry.
 1238                  */
 1239                 INP_INFO_RLOCK(&V_tcbinfo);
 1240                 xig.xig_gen = V_tcbinfo.ipi_gencnt;
 1241                 xig.xig_sogen = so_gencnt;
 1242                 xig.xig_count = V_tcbinfo.ipi_count + pcb_count;
 1243                 INP_INFO_RUNLOCK(&V_tcbinfo);
 1244                 error = SYSCTL_OUT(req, &xig, sizeof xig);
 1245         }
 1246         free(inp_list, M_TEMP);
 1247         return (error);
 1248 }
 1249 
 1250 SYSCTL_PROC(_net_inet_tcp, TCPCTL_PCBLIST, pcblist,
 1251     CTLTYPE_OPAQUE | CTLFLAG_RD, NULL, 0,
 1252     tcp_pcblist, "S,xtcpcb", "List of active TCP connections");
 1253 
 1254 static int
 1255 tcp_getcred(SYSCTL_HANDLER_ARGS)
 1256 {
 1257         struct xucred xuc;
 1258         struct sockaddr_in addrs[2];
 1259         struct inpcb *inp;
 1260         int error;
 1261 
 1262         error = priv_check(req->td, PRIV_NETINET_GETCRED);
 1263         if (error)
 1264                 return (error);
 1265         error = SYSCTL_IN(req, addrs, sizeof(addrs));
 1266         if (error)
 1267                 return (error);
 1268         INP_INFO_RLOCK(&V_tcbinfo);
 1269         inp = in_pcblookup_hash(&V_tcbinfo, addrs[1].sin_addr,
 1270             addrs[1].sin_port, addrs[0].sin_addr, addrs[0].sin_port, 0, NULL);
 1271         if (inp != NULL) {
 1272                 INP_RLOCK(inp);
 1273                 INP_INFO_RUNLOCK(&V_tcbinfo);
 1274                 if (inp->inp_socket == NULL)
 1275                         error = ENOENT;
 1276                 if (error == 0)
 1277                         error = cr_canseeinpcb(req->td->td_ucred, inp);
 1278                 if (error == 0)
 1279                         cru2x(inp->inp_cred, &xuc);
 1280                 INP_RUNLOCK(inp);
 1281         } else {
 1282                 INP_INFO_RUNLOCK(&V_tcbinfo);
 1283                 error = ENOENT;
 1284         }
 1285         if (error == 0)
 1286                 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred));
 1287         return (error);
 1288 }
 1289 
 1290 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, getcred,
 1291     CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0,
 1292     tcp_getcred, "S,xucred", "Get the xucred of a TCP connection");
 1293 
 1294 #ifdef INET6
 1295 static int
 1296 tcp6_getcred(SYSCTL_HANDLER_ARGS)
 1297 {
 1298         struct xucred xuc;
 1299         struct sockaddr_in6 addrs[2];
 1300         struct inpcb *inp;
 1301         int error, mapped = 0;
 1302 
 1303         error = priv_check(req->td, PRIV_NETINET_GETCRED);
 1304         if (error)
 1305                 return (error);
 1306         error = SYSCTL_IN(req, addrs, sizeof(addrs));
 1307         if (error)
 1308                 return (error);
 1309         if ((error = sa6_embedscope(&addrs[0], V_ip6_use_defzone)) != 0 ||
 1310             (error = sa6_embedscope(&addrs[1], V_ip6_use_defzone)) != 0) {
 1311                 return (error);
 1312         }
 1313         if (IN6_IS_ADDR_V4MAPPED(&addrs[0].sin6_addr)) {
 1314                 if (IN6_IS_ADDR_V4MAPPED(&addrs[1].sin6_addr))
 1315                         mapped = 1;
 1316                 else
 1317                         return (EINVAL);
 1318         }
 1319 
 1320         INP_INFO_RLOCK(&V_tcbinfo);
 1321         if (mapped == 1)
 1322                 inp = in_pcblookup_hash(&V_tcbinfo,
 1323                         *(struct in_addr *)&addrs[1].sin6_addr.s6_addr[12],
 1324                         addrs[1].sin6_port,
 1325                         *(struct in_addr *)&addrs[0].sin6_addr.s6_addr[12],
 1326                         addrs[0].sin6_port,
 1327                         0, NULL);
 1328         else
 1329                 inp = in6_pcblookup_hash(&V_tcbinfo,
 1330                         &addrs[1].sin6_addr, addrs[1].sin6_port,
 1331                         &addrs[0].sin6_addr, addrs[0].sin6_port, 0, NULL);
 1332         if (inp != NULL) {
 1333                 INP_RLOCK(inp);
 1334                 INP_INFO_RUNLOCK(&V_tcbinfo);
 1335                 if (inp->inp_socket == NULL)
 1336                         error = ENOENT;
 1337                 if (error == 0)
 1338                         error = cr_canseeinpcb(req->td->td_ucred, inp);
 1339                 if (error == 0)
 1340                         cru2x(inp->inp_cred, &xuc);
 1341                 INP_RUNLOCK(inp);
 1342         } else {
 1343                 INP_INFO_RUNLOCK(&V_tcbinfo);
 1344                 error = ENOENT;
 1345         }
 1346         if (error == 0)
 1347                 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred));
 1348         return (error);
 1349 }
 1350 
 1351 SYSCTL_PROC(_net_inet6_tcp6, OID_AUTO, getcred,
 1352     CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0,
 1353     tcp6_getcred, "S,xucred", "Get the xucred of a TCP6 connection");
 1354 #endif
 1355 
 1356 
 1357 void
 1358 tcp_ctlinput(int cmd, struct sockaddr *sa, void *vip)
 1359 {
 1360         struct ip *ip = vip;
 1361         struct tcphdr *th;
 1362         struct in_addr faddr;
 1363         struct inpcb *inp;
 1364         struct tcpcb *tp;
 1365         struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify;
 1366         struct icmp *icp;
 1367         struct in_conninfo inc;
 1368         tcp_seq icmp_tcp_seq;
 1369         int mtu;
 1370 
 1371         faddr = ((struct sockaddr_in *)sa)->sin_addr;
 1372         if (sa->sa_family != AF_INET || faddr.s_addr == INADDR_ANY)
 1373                 return;
 1374 
 1375         if (cmd == PRC_MSGSIZE)
 1376                 notify = tcp_mtudisc_notify;
 1377         else if (V_icmp_may_rst && (cmd == PRC_UNREACH_ADMIN_PROHIB ||
 1378                 cmd == PRC_UNREACH_PORT || cmd == PRC_TIMXCEED_INTRANS) && ip)
 1379                 notify = tcp_drop_syn_sent;
 1380         /*
 1381          * Redirects don't need to be handled up here.
 1382          */
 1383         else if (PRC_IS_REDIRECT(cmd))
 1384                 return;
 1385         /*
 1386          * Source quench is depreciated.
 1387          */
 1388         else if (cmd == PRC_QUENCH)
 1389                 return;
 1390         /*
 1391          * Hostdead is ugly because it goes linearly through all PCBs.
 1392          * XXX: We never get this from ICMP, otherwise it makes an
 1393          * excellent DoS attack on machines with many connections.
 1394          */
 1395         else if (cmd == PRC_HOSTDEAD)
 1396                 ip = NULL;
 1397         else if ((unsigned)cmd >= PRC_NCMDS || inetctlerrmap[cmd] == 0)
 1398                 return;
 1399         if (ip != NULL) {
 1400                 icp = (struct icmp *)((caddr_t)ip
 1401                                       - offsetof(struct icmp, icmp_ip));
 1402                 th = (struct tcphdr *)((caddr_t)ip
 1403                                        + (ip->ip_hl << 2));
 1404                 INP_INFO_WLOCK(&V_tcbinfo);
 1405                 inp = in_pcblookup_hash(&V_tcbinfo, faddr, th->th_dport,
 1406                     ip->ip_src, th->th_sport, 0, NULL);
 1407                 if (inp != NULL)  {
 1408                         INP_WLOCK(inp);
 1409                         if (!(inp->inp_flags & INP_TIMEWAIT) &&
 1410                             !(inp->inp_flags & INP_DROPPED) &&
 1411                             !(inp->inp_socket == NULL)) {
 1412                                 icmp_tcp_seq = htonl(th->th_seq);
 1413                                 tp = intotcpcb(inp);
 1414                                 if (SEQ_GEQ(icmp_tcp_seq, tp->snd_una) &&
 1415                                     SEQ_LT(icmp_tcp_seq, tp->snd_max)) {
 1416                                         if (cmd == PRC_MSGSIZE) {
 1417                                             /*
 1418                                              * MTU discovery:
 1419                                              * If we got a needfrag set the MTU
 1420                                              * in the route to the suggested new
 1421                                              * value (if given) and then notify.
 1422                                              */
 1423                                             bzero(&inc, sizeof(inc));
 1424                                             inc.inc_faddr = faddr;
 1425                                             inc.inc_fibnum =
 1426                                                 inp->inp_inc.inc_fibnum;
 1427 
 1428                                             mtu = ntohs(icp->icmp_nextmtu);
 1429                                             /*
 1430                                              * If no alternative MTU was
 1431                                              * proposed, try the next smaller
 1432                                              * one.  ip->ip_len has already
 1433                                              * been swapped in icmp_input().
 1434                                              */
 1435                                             if (!mtu)
 1436                                                 mtu = ip_next_mtu(ip->ip_len,
 1437                                                  1);
 1438                                             if (mtu < V_tcp_minmss
 1439                                                  + sizeof(struct tcpiphdr))
 1440                                                 mtu = V_tcp_minmss
 1441                                                  + sizeof(struct tcpiphdr);
 1442                                             /*
 1443                                              * Only cache the MTU if it
 1444                                              * is smaller than the interface
 1445                                              * or route MTU.  tcp_mtudisc()
 1446                                              * will do right thing by itself.
 1447                                              */
 1448                                             if (mtu <= tcp_maxmtu(&inc, NULL))
 1449                                                 tcp_hc_updatemtu(&inc, mtu);
 1450                                             tcp_mtudisc(inp, mtu);
 1451                                         } else
 1452                                                 inp = (*notify)(inp,
 1453                                                     inetctlerrmap[cmd]);
 1454                                 }
 1455                         }
 1456                         if (inp != NULL)
 1457                                 INP_WUNLOCK(inp);
 1458                 } else {
 1459                         bzero(&inc, sizeof(inc));
 1460                         inc.inc_fport = th->th_dport;
 1461                         inc.inc_lport = th->th_sport;
 1462                         inc.inc_faddr = faddr;
 1463                         inc.inc_laddr = ip->ip_src;
 1464                         syncache_unreach(&inc, th);
 1465                 }
 1466                 INP_INFO_WUNLOCK(&V_tcbinfo);
 1467         } else
 1468                 in_pcbnotifyall(&V_tcbinfo, faddr, inetctlerrmap[cmd], notify);
 1469 }
 1470 
 1471 #ifdef INET6
 1472 void
 1473 tcp6_ctlinput(int cmd, struct sockaddr *sa, void *d)
 1474 {
 1475         struct tcphdr th;
 1476         struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify;
 1477         struct ip6_hdr *ip6;
 1478         struct mbuf *m;
 1479         struct ip6ctlparam *ip6cp = NULL;
 1480         const struct sockaddr_in6 *sa6_src = NULL;
 1481         int off;
 1482         struct tcp_portonly {
 1483                 u_int16_t th_sport;
 1484                 u_int16_t th_dport;
 1485         } *thp;
 1486 
 1487         if (sa->sa_family != AF_INET6 ||
 1488             sa->sa_len != sizeof(struct sockaddr_in6))
 1489                 return;
 1490 
 1491         if (cmd == PRC_MSGSIZE)
 1492                 notify = tcp_mtudisc_notify;
 1493         else if (!PRC_IS_REDIRECT(cmd) &&
 1494                  ((unsigned)cmd >= PRC_NCMDS || inet6ctlerrmap[cmd] == 0))
 1495                 return;
 1496         /* Source quench is depreciated. */
 1497         else if (cmd == PRC_QUENCH)
 1498                 return;
 1499 
 1500         /* if the parameter is from icmp6, decode it. */
 1501         if (d != NULL) {
 1502                 ip6cp = (struct ip6ctlparam *)d;
 1503                 m = ip6cp->ip6c_m;
 1504                 ip6 = ip6cp->ip6c_ip6;
 1505                 off = ip6cp->ip6c_off;
 1506                 sa6_src = ip6cp->ip6c_src;
 1507         } else {
 1508                 m = NULL;
 1509                 ip6 = NULL;
 1510                 off = 0;        /* fool gcc */
 1511                 sa6_src = &sa6_any;
 1512         }
 1513 
 1514         if (ip6 != NULL) {
 1515                 struct in_conninfo inc;
 1516                 /*
 1517                  * XXX: We assume that when IPV6 is non NULL,
 1518                  * M and OFF are valid.
 1519                  */
 1520 
 1521                 /* check if we can safely examine src and dst ports */
 1522                 if (m->m_pkthdr.len < off + sizeof(*thp))
 1523                         return;
 1524 
 1525                 bzero(&th, sizeof(th));
 1526                 m_copydata(m, off, sizeof(*thp), (caddr_t)&th);
 1527 
 1528                 in6_pcbnotify(&V_tcbinfo, sa, th.th_dport,
 1529                     (struct sockaddr *)ip6cp->ip6c_src,
 1530                     th.th_sport, cmd, NULL, notify);
 1531 
 1532                 bzero(&inc, sizeof(inc));
 1533                 inc.inc_fport = th.th_dport;
 1534                 inc.inc_lport = th.th_sport;
 1535                 inc.inc6_faddr = ((struct sockaddr_in6 *)sa)->sin6_addr;
 1536                 inc.inc6_laddr = ip6cp->ip6c_src->sin6_addr;
 1537                 inc.inc_flags |= INC_ISIPV6;
 1538                 INP_INFO_WLOCK(&V_tcbinfo);
 1539                 syncache_unreach(&inc, &th);
 1540                 INP_INFO_WUNLOCK(&V_tcbinfo);
 1541         } else
 1542                 in6_pcbnotify(&V_tcbinfo, sa, 0, (const struct sockaddr *)sa6_src,
 1543                               0, cmd, NULL, notify);
 1544 }
 1545 #endif /* INET6 */
 1546 
 1547 
 1548 /*
 1549  * Following is where TCP initial sequence number generation occurs.
 1550  *
 1551  * There are two places where we must use initial sequence numbers:
 1552  * 1.  In SYN-ACK packets.
 1553  * 2.  In SYN packets.
 1554  *
 1555  * All ISNs for SYN-ACK packets are generated by the syncache.  See
 1556  * tcp_syncache.c for details.
 1557  *
 1558  * The ISNs in SYN packets must be monotonic; TIME_WAIT recycling
 1559  * depends on this property.  In addition, these ISNs should be
 1560  * unguessable so as to prevent connection hijacking.  To satisfy
 1561  * the requirements of this situation, the algorithm outlined in
 1562  * RFC 1948 is used, with only small modifications.
 1563  *
 1564  * Implementation details:
 1565  *
 1566  * Time is based off the system timer, and is corrected so that it
 1567  * increases by one megabyte per second.  This allows for proper
 1568  * recycling on high speed LANs while still leaving over an hour
 1569  * before rollover.
 1570  *
 1571  * As reading the *exact* system time is too expensive to be done
 1572  * whenever setting up a TCP connection, we increment the time
 1573  * offset in two ways.  First, a small random positive increment
 1574  * is added to isn_offset for each connection that is set up.
 1575  * Second, the function tcp_isn_tick fires once per clock tick
 1576  * and increments isn_offset as necessary so that sequence numbers
 1577  * are incremented at approximately ISN_BYTES_PER_SECOND.  The
 1578  * random positive increments serve only to ensure that the same
 1579  * exact sequence number is never sent out twice (as could otherwise
 1580  * happen when a port is recycled in less than the system tick
 1581  * interval.)
 1582  *
 1583  * net.inet.tcp.isn_reseed_interval controls the number of seconds
 1584  * between seeding of isn_secret.  This is normally set to zero,
 1585  * as reseeding should not be necessary.
 1586  *
 1587  * Locking of the global variables isn_secret, isn_last_reseed, isn_offset,
 1588  * isn_offset_old, and isn_ctx is performed using the TCP pcbinfo lock.  In
 1589  * general, this means holding an exclusive (write) lock.
 1590  */
 1591 
 1592 #define ISN_BYTES_PER_SECOND 1048576
 1593 #define ISN_STATIC_INCREMENT 4096
 1594 #define ISN_RANDOM_INCREMENT (4096 - 1)
 1595 
 1596 static VNET_DEFINE(u_char, isn_secret[32]);
 1597 static VNET_DEFINE(int, isn_last_reseed);
 1598 static VNET_DEFINE(u_int32_t, isn_offset);
 1599 static VNET_DEFINE(u_int32_t, isn_offset_old);
 1600 
 1601 #define V_isn_secret                    VNET(isn_secret)
 1602 #define V_isn_last_reseed               VNET(isn_last_reseed)
 1603 #define V_isn_offset                    VNET(isn_offset)
 1604 #define V_isn_offset_old                VNET(isn_offset_old)
 1605 
 1606 tcp_seq
 1607 tcp_new_isn(struct tcpcb *tp)
 1608 {
 1609         MD5_CTX isn_ctx;
 1610         u_int32_t md5_buffer[4];
 1611         tcp_seq new_isn;
 1612 
 1613         INP_WLOCK_ASSERT(tp->t_inpcb);
 1614 
 1615         ISN_LOCK();
 1616         /* Seed if this is the first use, reseed if requested. */
 1617         if ((V_isn_last_reseed == 0) || ((V_tcp_isn_reseed_interval > 0) &&
 1618              (((u_int)V_isn_last_reseed + (u_int)V_tcp_isn_reseed_interval*hz)
 1619                 < (u_int)ticks))) {
 1620                 read_random(&V_isn_secret, sizeof(V_isn_secret));
 1621                 V_isn_last_reseed = ticks;
 1622         }
 1623 
 1624         /* Compute the md5 hash and return the ISN. */
 1625         MD5Init(&isn_ctx);
 1626         MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_fport, sizeof(u_short));
 1627         MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_lport, sizeof(u_short));
 1628 #ifdef INET6
 1629         if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) {
 1630                 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_faddr,
 1631                           sizeof(struct in6_addr));
 1632                 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_laddr,
 1633                           sizeof(struct in6_addr));
 1634         } else
 1635 #endif
 1636         {
 1637                 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_faddr,
 1638                           sizeof(struct in_addr));
 1639                 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_laddr,
 1640                           sizeof(struct in_addr));
 1641         }
 1642         MD5Update(&isn_ctx, (u_char *) &V_isn_secret, sizeof(V_isn_secret));
 1643         MD5Final((u_char *) &md5_buffer, &isn_ctx);
 1644         new_isn = (tcp_seq) md5_buffer[0];
 1645         V_isn_offset += ISN_STATIC_INCREMENT +
 1646                 (arc4random() & ISN_RANDOM_INCREMENT);
 1647         new_isn += V_isn_offset;
 1648         ISN_UNLOCK();
 1649         return (new_isn);
 1650 }
 1651 
 1652 /*
 1653  * Increment the offset to the next ISN_BYTES_PER_SECOND / 100 boundary
 1654  * to keep time flowing at a relatively constant rate.  If the random
 1655  * increments have already pushed us past the projected offset, do nothing.
 1656  */
 1657 static void
 1658 tcp_isn_tick(void *xtp)
 1659 {
 1660         VNET_ITERATOR_DECL(vnet_iter);
 1661         u_int32_t projected_offset;
 1662 
 1663         VNET_LIST_RLOCK_NOSLEEP();
 1664         ISN_LOCK();
 1665         VNET_FOREACH(vnet_iter) {
 1666                 CURVNET_SET(vnet_iter); /* XXX appease INVARIANTS */
 1667                 projected_offset =
 1668                     V_isn_offset_old + ISN_BYTES_PER_SECOND / 100;
 1669 
 1670                 if (SEQ_GT(projected_offset, V_isn_offset))
 1671                         V_isn_offset = projected_offset;
 1672 
 1673                 V_isn_offset_old = V_isn_offset;
 1674                 CURVNET_RESTORE();
 1675         }
 1676         ISN_UNLOCK();
 1677         VNET_LIST_RUNLOCK_NOSLEEP();
 1678         callout_reset(&isn_callout, hz/100, tcp_isn_tick, NULL);
 1679 }
 1680 
 1681 /*
 1682  * When a specific ICMP unreachable message is received and the
 1683  * connection state is SYN-SENT, drop the connection.  This behavior
 1684  * is controlled by the icmp_may_rst sysctl.
 1685  */
 1686 struct inpcb *
 1687 tcp_drop_syn_sent(struct inpcb *inp, int errno)
 1688 {
 1689         struct tcpcb *tp;
 1690 
 1691         INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
 1692         INP_WLOCK_ASSERT(inp);
 1693 
 1694         if ((inp->inp_flags & INP_TIMEWAIT) ||
 1695             (inp->inp_flags & INP_DROPPED))
 1696                 return (inp);
 1697 
 1698         tp = intotcpcb(inp);
 1699         if (tp->t_state != TCPS_SYN_SENT)
 1700                 return (inp);
 1701 
 1702         tp = tcp_drop(tp, errno);
 1703         if (tp != NULL)
 1704                 return (inp);
 1705         else
 1706                 return (NULL);
 1707 }
 1708 
 1709 /*
 1710  * When `need fragmentation' ICMP is received, update our idea of the MSS
 1711  * based on the new value. Also nudge TCP to send something, since we
 1712  * know the packet we just sent was dropped.
 1713  * This duplicates some code in the tcp_mss() function in tcp_input.c.
 1714  */
 1715 static struct inpcb *
 1716 tcp_mtudisc_notify(struct inpcb *inp, int error)
 1717 {
 1718 
 1719         return (tcp_mtudisc(inp, -1));
 1720 }
 1721 
 1722 struct inpcb *
 1723 tcp_mtudisc(struct inpcb *inp, int mtuoffer)
 1724 {
 1725         struct tcpcb *tp;
 1726         struct socket *so;
 1727 
 1728         INP_WLOCK_ASSERT(inp);
 1729         if ((inp->inp_flags & INP_TIMEWAIT) ||
 1730             (inp->inp_flags & INP_DROPPED))
 1731                 return (inp);
 1732 
 1733         tp = intotcpcb(inp);
 1734         KASSERT(tp != NULL, ("tcp_mtudisc: tp == NULL"));
 1735 
 1736         tcp_mss_update(tp, -1, mtuoffer, NULL, NULL);
 1737   
 1738         so = inp->inp_socket;
 1739         SOCKBUF_LOCK(&so->so_snd);
 1740         /* If the mss is larger than the socket buffer, decrease the mss. */
 1741         if (so->so_snd.sb_hiwat < tp->t_maxseg)
 1742                 tp->t_maxseg = so->so_snd.sb_hiwat;
 1743         SOCKBUF_UNLOCK(&so->so_snd);
 1744 
 1745         TCPSTAT_INC(tcps_mturesent);
 1746         tp->t_rtttime = 0;
 1747         tp->snd_nxt = tp->snd_una;
 1748         tcp_free_sackholes(tp);
 1749         tp->snd_recover = tp->snd_max;
 1750         if (tp->t_flags & TF_SACK_PERMIT)
 1751                 EXIT_FASTRECOVERY(tp->t_flags);
 1752         tcp_output_send(tp);
 1753         return (inp);
 1754 }
 1755 
 1756 /*
 1757  * Look-up the routing entry to the peer of this inpcb.  If no route
 1758  * is found and it cannot be allocated, then return 0.  This routine
 1759  * is called by TCP routines that access the rmx structure and by
 1760  * tcp_mss_update to get the peer/interface MTU.
 1761  */
 1762 u_long
 1763 tcp_maxmtu(struct in_conninfo *inc, int *flags)
 1764 {
 1765         struct route sro;
 1766         struct sockaddr_in *dst;
 1767         struct ifnet *ifp;
 1768         u_long maxmtu = 0;
 1769 
 1770         KASSERT(inc != NULL, ("tcp_maxmtu with NULL in_conninfo pointer"));
 1771 
 1772         bzero(&sro, sizeof(sro));
 1773         if (inc->inc_faddr.s_addr != INADDR_ANY) {
 1774                 dst = (struct sockaddr_in *)&sro.ro_dst;
 1775                 dst->sin_family = AF_INET;
 1776                 dst->sin_len = sizeof(*dst);
 1777                 dst->sin_addr = inc->inc_faddr;
 1778                 in_rtalloc_ign(&sro, 0, inc->inc_fibnum);
 1779         }
 1780         if (sro.ro_rt != NULL) {
 1781                 ifp = sro.ro_rt->rt_ifp;
 1782                 if (sro.ro_rt->rt_rmx.rmx_mtu == 0)
 1783                         maxmtu = ifp->if_mtu;
 1784                 else
 1785                         maxmtu = min(sro.ro_rt->rt_rmx.rmx_mtu, ifp->if_mtu);
 1786 
 1787                 /* Report additional interface capabilities. */
 1788                 if (flags != NULL) {
 1789                         if (ifp->if_capenable & IFCAP_TSO4 &&
 1790                             ifp->if_hwassist & CSUM_TSO)
 1791                                 *flags |= CSUM_TSO;
 1792                 }
 1793                 RTFREE(sro.ro_rt);
 1794         }
 1795         return (maxmtu);
 1796 }
 1797 
 1798 #ifdef INET6
 1799 u_long
 1800 tcp_maxmtu6(struct in_conninfo *inc, int *flags)
 1801 {
 1802         struct route_in6 sro6;
 1803         struct ifnet *ifp;
 1804         u_long maxmtu = 0;
 1805 
 1806         KASSERT(inc != NULL, ("tcp_maxmtu6 with NULL in_conninfo pointer"));
 1807 
 1808         bzero(&sro6, sizeof(sro6));
 1809         if (!IN6_IS_ADDR_UNSPECIFIED(&inc->inc6_faddr)) {
 1810                 sro6.ro_dst.sin6_family = AF_INET6;
 1811                 sro6.ro_dst.sin6_len = sizeof(struct sockaddr_in6);
 1812                 sro6.ro_dst.sin6_addr = inc->inc6_faddr;
 1813                 in6_rtalloc_ign(&sro6, 0, inc->inc_fibnum);
 1814         }
 1815         if (sro6.ro_rt != NULL) {
 1816                 ifp = sro6.ro_rt->rt_ifp;
 1817                 if (sro6.ro_rt->rt_rmx.rmx_mtu == 0)
 1818                         maxmtu = IN6_LINKMTU(sro6.ro_rt->rt_ifp);
 1819                 else
 1820                         maxmtu = min(sro6.ro_rt->rt_rmx.rmx_mtu,
 1821                                      IN6_LINKMTU(sro6.ro_rt->rt_ifp));
 1822 
 1823                 /* Report additional interface capabilities. */
 1824                 if (flags != NULL) {
 1825                         if (ifp->if_capenable & IFCAP_TSO6 &&
 1826                             ifp->if_hwassist & CSUM_TSO)
 1827                                 *flags |= CSUM_TSO;
 1828                 }
 1829                 RTFREE(sro6.ro_rt);
 1830         }
 1831 
 1832         return (maxmtu);
 1833 }
 1834 #endif /* INET6 */
 1835 
 1836 #ifdef IPSEC
 1837 /* compute ESP/AH header size for TCP, including outer IP header. */
 1838 size_t
 1839 ipsec_hdrsiz_tcp(struct tcpcb *tp)
 1840 {
 1841         struct inpcb *inp;
 1842         struct mbuf *m;
 1843         size_t hdrsiz;
 1844         struct ip *ip;
 1845 #ifdef INET6
 1846         struct ip6_hdr *ip6;
 1847 #endif
 1848         struct tcphdr *th;
 1849 
 1850         if ((tp == NULL) || ((inp = tp->t_inpcb) == NULL))
 1851                 return (0);
 1852         MGETHDR(m, M_DONTWAIT, MT_DATA);
 1853         if (!m)
 1854                 return (0);
 1855 
 1856 #ifdef INET6
 1857         if ((inp->inp_vflag & INP_IPV6) != 0) {
 1858                 ip6 = mtod(m, struct ip6_hdr *);
 1859                 th = (struct tcphdr *)(ip6 + 1);
 1860                 m->m_pkthdr.len = m->m_len =
 1861                         sizeof(struct ip6_hdr) + sizeof(struct tcphdr);
 1862                 tcpip_fillheaders(inp, ip6, th);
 1863                 hdrsiz = ipsec_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp);
 1864         } else
 1865 #endif /* INET6 */
 1866         {
 1867                 ip = mtod(m, struct ip *);
 1868                 th = (struct tcphdr *)(ip + 1);
 1869                 m->m_pkthdr.len = m->m_len = sizeof(struct tcpiphdr);
 1870                 tcpip_fillheaders(inp, ip, th);
 1871                 hdrsiz = ipsec_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp);
 1872         }
 1873 
 1874         m_free(m);
 1875         return (hdrsiz);
 1876 }
 1877 #endif /* IPSEC */
 1878 
 1879 /*
 1880  * TCP BANDWIDTH DELAY PRODUCT WINDOW LIMITING
 1881  *
 1882  * This code attempts to calculate the bandwidth-delay product as a
 1883  * means of determining the optimal window size to maximize bandwidth,
 1884  * minimize RTT, and avoid the over-allocation of buffers on interfaces and
 1885  * routers.  This code also does a fairly good job keeping RTTs in check
 1886  * across slow links like modems.  We implement an algorithm which is very
 1887  * similar (but not meant to be) TCP/Vegas.  The code operates on the
 1888  * transmitter side of a TCP connection and so only effects the transmit
 1889  * side of the connection.
 1890  *
 1891  * BACKGROUND:  TCP makes no provision for the management of buffer space
 1892  * at the end points or at the intermediate routers and switches.  A TCP
 1893  * stream, whether using NewReno or not, will eventually buffer as
 1894  * many packets as it is able and the only reason this typically works is
 1895  * due to the fairly small default buffers made available for a connection
 1896  * (typicaly 16K or 32K).  As machines use larger windows and/or window
 1897  * scaling it is now fairly easy for even a single TCP connection to blow-out
 1898  * all available buffer space not only on the local interface, but on
 1899  * intermediate routers and switches as well.  NewReno makes a misguided
 1900  * attempt to 'solve' this problem by waiting for an actual failure to occur,
 1901  * then backing off, then steadily increasing the window again until another
 1902  * failure occurs, ad-infinitum.  This results in terrible oscillation that
 1903  * is only made worse as network loads increase and the idea of intentionally
 1904  * blowing out network buffers is, frankly, a terrible way to manage network
 1905  * resources.
 1906  *
 1907  * It is far better to limit the transmit window prior to the failure
 1908  * condition being achieved.  There are two general ways to do this:  First
 1909  * you can 'scan' through different transmit window sizes and locate the
 1910  * point where the RTT stops increasing, indicating that you have filled the
 1911  * pipe, then scan backwards until you note that RTT stops decreasing, then
 1912  * repeat ad-infinitum.  This method works in principle but has severe
 1913  * implementation issues due to RTT variances, timer granularity, and
 1914  * instability in the algorithm which can lead to many false positives and
 1915  * create oscillations as well as interact badly with other TCP streams
 1916  * implementing the same algorithm.
 1917  *
 1918  * The second method is to limit the window to the bandwidth delay product
 1919  * of the link.  This is the method we implement.  RTT variances and our
 1920  * own manipulation of the congestion window, bwnd, can potentially
 1921  * destabilize the algorithm.  For this reason we have to stabilize the
 1922  * elements used to calculate the window.  We do this by using the minimum
 1923  * observed RTT, the long term average of the observed bandwidth, and
 1924  * by adding two segments worth of slop.  It isn't perfect but it is able
 1925  * to react to changing conditions and gives us a very stable basis on
 1926  * which to extend the algorithm.
 1927  */
 1928 void
 1929 tcp_xmit_bandwidth_limit(struct tcpcb *tp, tcp_seq ack_seq)
 1930 {
 1931         u_long bw;
 1932         u_long bwnd;
 1933         int save_ticks;
 1934 
 1935         INP_WLOCK_ASSERT(tp->t_inpcb);
 1936 
 1937         /*
 1938          * If inflight_enable is disabled in the middle of a tcp connection,
 1939          * make sure snd_bwnd is effectively disabled.
 1940          */
 1941         if (V_tcp_inflight_enable == 0 ||
 1942             tp->t_rttlow < V_tcp_inflight_rttthresh) {
 1943                 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
 1944                 tp->snd_bandwidth = 0;
 1945                 return;
 1946         }
 1947 
 1948         /*
 1949          * Figure out the bandwidth.  Due to the tick granularity this
 1950          * is a very rough number and it MUST be averaged over a fairly
 1951          * long period of time.  XXX we need to take into account a link
 1952          * that is not using all available bandwidth, but for now our
 1953          * slop will ramp us up if this case occurs and the bandwidth later
 1954          * increases.
 1955          *
 1956          * Note: if ticks rollover 'bw' may wind up negative.  We must
 1957          * effectively reset t_bw_rtttime for this case.
 1958          */
 1959         save_ticks = ticks;
 1960         if ((u_int)(save_ticks - tp->t_bw_rtttime) < 1)
 1961                 return;
 1962 
 1963         bw = (int64_t)(ack_seq - tp->t_bw_rtseq) * hz /
 1964             (save_ticks - tp->t_bw_rtttime);
 1965         tp->t_bw_rtttime = save_ticks;
 1966         tp->t_bw_rtseq = ack_seq;
 1967         if (tp->t_bw_rtttime == 0 || (int)bw < 0)
 1968                 return;
 1969         bw = ((int64_t)tp->snd_bandwidth * 15 + bw) >> 4;
 1970 
 1971         tp->snd_bandwidth = bw;
 1972 
 1973         /*
 1974          * Calculate the semi-static bandwidth delay product, plus two maximal
 1975          * segments.  The additional slop puts us squarely in the sweet
 1976          * spot and also handles the bandwidth run-up case and stabilization.
 1977          * Without the slop we could be locking ourselves into a lower
 1978          * bandwidth.
 1979          *
 1980          * Situations Handled:
 1981          *      (1) Prevents over-queueing of packets on LANs, especially on
 1982          *          high speed LANs, allowing larger TCP buffers to be
 1983          *          specified, and also does a good job preventing
 1984          *          over-queueing of packets over choke points like modems
 1985          *          (at least for the transmit side).
 1986          *
 1987          *      (2) Is able to handle changing network loads (bandwidth
 1988          *          drops so bwnd drops, bandwidth increases so bwnd
 1989          *          increases).
 1990          *
 1991          *      (3) Theoretically should stabilize in the face of multiple
 1992          *          connections implementing the same algorithm (this may need
 1993          *          a little work).
 1994          *
 1995          *      (4) Stability value (defaults to 20 = 2 maximal packets) can
 1996          *          be adjusted with a sysctl but typically only needs to be
 1997          *          on very slow connections.  A value no smaller then 5
 1998          *          should be used, but only reduce this default if you have
 1999          *          no other choice.
 2000          */
 2001 #define USERTT  ((tp->t_srtt + tp->t_rttbest) / 2)
 2002         bwnd = (int64_t)bw * USERTT / (hz << TCP_RTT_SHIFT) + V_tcp_inflight_stab * tp->t_maxseg / 10;
 2003 #undef USERTT
 2004 
 2005         if (tcp_inflight_debug > 0) {
 2006                 static int ltime;
 2007                 if ((u_int)(ticks - ltime) >= hz / tcp_inflight_debug) {
 2008                         ltime = ticks;
 2009                         printf("%p bw %ld rttbest %d srtt %d bwnd %ld\n",
 2010                             tp,
 2011                             bw,
 2012                             tp->t_rttbest,
 2013                             tp->t_srtt,
 2014                             bwnd
 2015                         );
 2016                 }
 2017         }
 2018         if ((long)bwnd < V_tcp_inflight_min)
 2019                 bwnd = V_tcp_inflight_min;
 2020         if (bwnd > V_tcp_inflight_max)
 2021                 bwnd = V_tcp_inflight_max;
 2022         if ((long)bwnd < tp->t_maxseg * 2)
 2023                 bwnd = tp->t_maxseg * 2;
 2024         tp->snd_bwnd = bwnd;
 2025 }
 2026 
 2027 #ifdef TCP_SIGNATURE
 2028 /*
 2029  * Callback function invoked by m_apply() to digest TCP segment data
 2030  * contained within an mbuf chain.
 2031  */
 2032 static int
 2033 tcp_signature_apply(void *fstate, void *data, u_int len)
 2034 {
 2035 
 2036         MD5Update(fstate, (u_char *)data, len);
 2037         return (0);
 2038 }
 2039 
 2040 /*
 2041  * Compute TCP-MD5 hash of a TCP segment. (RFC2385)
 2042  *
 2043  * Parameters:
 2044  * m            pointer to head of mbuf chain
 2045  * _unused      
 2046  * len          length of TCP segment data, excluding options
 2047  * optlen       length of TCP segment options
 2048  * buf          pointer to storage for computed MD5 digest
 2049  * direction    direction of flow (IPSEC_DIR_INBOUND or OUTBOUND)
 2050  *
 2051  * We do this over ip, tcphdr, segment data, and the key in the SADB.
 2052  * When called from tcp_input(), we can be sure that th_sum has been
 2053  * zeroed out and verified already.
 2054  *
 2055  * Return 0 if successful, otherwise return -1.
 2056  *
 2057  * XXX The key is retrieved from the system's PF_KEY SADB, by keying a
 2058  * search with the destination IP address, and a 'magic SPI' to be
 2059  * determined by the application. This is hardcoded elsewhere to 1179
 2060  * right now. Another branch of this code exists which uses the SPD to
 2061  * specify per-application flows but it is unstable.
 2062  */
 2063 int
 2064 tcp_signature_compute(struct mbuf *m, int _unused, int len, int optlen,
 2065     u_char *buf, u_int direction)
 2066 {
 2067         union sockaddr_union dst;
 2068         struct ippseudo ippseudo;
 2069         MD5_CTX ctx;
 2070         int doff;
 2071         struct ip *ip;
 2072         struct ipovly *ipovly;
 2073         struct secasvar *sav;
 2074         struct tcphdr *th;
 2075 #ifdef INET6
 2076         struct ip6_hdr *ip6;
 2077         struct in6_addr in6;
 2078         char ip6buf[INET6_ADDRSTRLEN];
 2079         uint32_t plen;
 2080         uint16_t nhdr;
 2081 #endif
 2082         u_short savecsum;
 2083 
 2084         KASSERT(m != NULL, ("NULL mbuf chain"));
 2085         KASSERT(buf != NULL, ("NULL signature pointer"));
 2086 
 2087         /* Extract the destination from the IP header in the mbuf. */
 2088         bzero(&dst, sizeof(union sockaddr_union));
 2089         ip = mtod(m, struct ip *);
 2090 #ifdef INET6
 2091         ip6 = NULL;     /* Make the compiler happy. */
 2092 #endif
 2093         switch (ip->ip_v) {
 2094         case IPVERSION:
 2095                 dst.sa.sa_len = sizeof(struct sockaddr_in);
 2096                 dst.sa.sa_family = AF_INET;
 2097                 dst.sin.sin_addr = (direction == IPSEC_DIR_INBOUND) ?
 2098                     ip->ip_src : ip->ip_dst;
 2099                 break;
 2100 #ifdef INET6
 2101         case (IPV6_VERSION >> 4):
 2102                 ip6 = mtod(m, struct ip6_hdr *);
 2103                 dst.sa.sa_len = sizeof(struct sockaddr_in6);
 2104                 dst.sa.sa_family = AF_INET6;
 2105                 dst.sin6.sin6_addr = (direction == IPSEC_DIR_INBOUND) ?
 2106                     ip6->ip6_src : ip6->ip6_dst;
 2107                 break;
 2108 #endif
 2109         default:
 2110                 return (EINVAL);
 2111                 /* NOTREACHED */
 2112                 break;
 2113         }
 2114 
 2115         /* Look up an SADB entry which matches the address of the peer. */
 2116         sav = KEY_ALLOCSA(&dst, IPPROTO_TCP, htonl(TCP_SIG_SPI));
 2117         if (sav == NULL) {
 2118                 ipseclog((LOG_ERR, "%s: SADB lookup failed for %s\n", __func__,
 2119                     (ip->ip_v == IPVERSION) ? inet_ntoa(dst.sin.sin_addr) :
 2120 #ifdef INET6
 2121                         (ip->ip_v == (IPV6_VERSION >> 4)) ?
 2122                             ip6_sprintf(ip6buf, &dst.sin6.sin6_addr) :
 2123 #endif
 2124                         "(unsupported)"));
 2125                 return (EINVAL);
 2126         }
 2127 
 2128         MD5Init(&ctx);
 2129         /*
 2130          * Step 1: Update MD5 hash with IP(v6) pseudo-header.
 2131          *
 2132          * XXX The ippseudo header MUST be digested in network byte order,
 2133          * or else we'll fail the regression test. Assume all fields we've
 2134          * been doing arithmetic on have been in host byte order.
 2135          * XXX One cannot depend on ipovly->ih_len here. When called from
 2136          * tcp_output(), the underlying ip_len member has not yet been set.
 2137          */
 2138         switch (ip->ip_v) {
 2139         case IPVERSION:
 2140                 ipovly = (struct ipovly *)ip;
 2141                 ippseudo.ippseudo_src = ipovly->ih_src;
 2142                 ippseudo.ippseudo_dst = ipovly->ih_dst;
 2143                 ippseudo.ippseudo_pad = 0;
 2144                 ippseudo.ippseudo_p = IPPROTO_TCP;
 2145                 ippseudo.ippseudo_len = htons(len + sizeof(struct tcphdr) +
 2146                     optlen);
 2147                 MD5Update(&ctx, (char *)&ippseudo, sizeof(struct ippseudo));
 2148 
 2149                 th = (struct tcphdr *)((u_char *)ip + sizeof(struct ip));
 2150                 doff = sizeof(struct ip) + sizeof(struct tcphdr) + optlen;
 2151                 break;
 2152 #ifdef INET6
 2153         /*
 2154          * RFC 2385, 2.0  Proposal
 2155          * For IPv6, the pseudo-header is as described in RFC 2460, namely the
 2156          * 128-bit source IPv6 address, 128-bit destination IPv6 address, zero-
 2157          * extended next header value (to form 32 bits), and 32-bit segment
 2158          * length.
 2159          * Note: Upper-Layer Packet Length comes before Next Header.
 2160          */
 2161         case (IPV6_VERSION >> 4):
 2162                 in6 = ip6->ip6_src;
 2163                 in6_clearscope(&in6);
 2164                 MD5Update(&ctx, (char *)&in6, sizeof(struct in6_addr));
 2165                 in6 = ip6->ip6_dst;
 2166                 in6_clearscope(&in6);
 2167                 MD5Update(&ctx, (char *)&in6, sizeof(struct in6_addr));
 2168                 plen = htonl(len + sizeof(struct tcphdr) + optlen);
 2169                 MD5Update(&ctx, (char *)&plen, sizeof(uint32_t));
 2170                 nhdr = 0;
 2171                 MD5Update(&ctx, (char *)&nhdr, sizeof(uint8_t));
 2172                 MD5Update(&ctx, (char *)&nhdr, sizeof(uint8_t));
 2173                 MD5Update(&ctx, (char *)&nhdr, sizeof(uint8_t));
 2174                 nhdr = IPPROTO_TCP;
 2175                 MD5Update(&ctx, (char *)&nhdr, sizeof(uint8_t));
 2176 
 2177                 th = (struct tcphdr *)((u_char *)ip6 + sizeof(struct ip6_hdr));
 2178                 doff = sizeof(struct ip6_hdr) + sizeof(struct tcphdr) + optlen;
 2179                 break;
 2180 #endif
 2181         default:
 2182                 return (EINVAL);
 2183                 /* NOTREACHED */
 2184                 break;
 2185         }
 2186 
 2187 
 2188         /*
 2189          * Step 2: Update MD5 hash with TCP header, excluding options.
 2190          * The TCP checksum must be set to zero.
 2191          */
 2192         savecsum = th->th_sum;
 2193         th->th_sum = 0;
 2194         MD5Update(&ctx, (char *)th, sizeof(struct tcphdr));
 2195         th->th_sum = savecsum;
 2196 
 2197         /*
 2198          * Step 3: Update MD5 hash with TCP segment data.
 2199          *         Use m_apply() to avoid an early m_pullup().
 2200          */
 2201         if (len > 0)
 2202                 m_apply(m, doff, len, tcp_signature_apply, &ctx);
 2203 
 2204         /*
 2205          * Step 4: Update MD5 hash with shared secret.
 2206          */
 2207         MD5Update(&ctx, sav->key_auth->key_data, _KEYLEN(sav->key_auth));
 2208         MD5Final(buf, &ctx);
 2209 
 2210         key_sa_recordxfer(sav, m);
 2211         KEY_FREESAV(&sav);
 2212         return (0);
 2213 }
 2214 
 2215 /*
 2216  * Verify the TCP-MD5 hash of a TCP segment. (RFC2385)
 2217  *
 2218  * Parameters:
 2219  * m            pointer to head of mbuf chain
 2220  * len          length of TCP segment data, excluding options
 2221  * optlen       length of TCP segment options
 2222  * buf          pointer to storage for computed MD5 digest
 2223  * direction    direction of flow (IPSEC_DIR_INBOUND or OUTBOUND)
 2224  *
 2225  * Return 1 if successful, otherwise return 0.
 2226  */
 2227 int
 2228 tcp_signature_verify(struct mbuf *m, int off0, int tlen, int optlen,
 2229     struct tcpopt *to, struct tcphdr *th, u_int tcpbflag)
 2230 {
 2231         char tmpdigest[TCP_SIGLEN];
 2232 
 2233         if (tcp_sig_checksigs == 0)
 2234                 return (1);
 2235         if ((tcpbflag & TF_SIGNATURE) == 0) {
 2236                 if ((to->to_flags & TOF_SIGNATURE) != 0) {
 2237 
 2238                         /*
 2239                          * If this socket is not expecting signature but
 2240                          * the segment contains signature just fail.
 2241                          */
 2242                         TCPSTAT_INC(tcps_sig_err_sigopt);
 2243                         TCPSTAT_INC(tcps_sig_rcvbadsig);
 2244                         return (0);
 2245                 }
 2246 
 2247                 /* Signature is not expected, and not present in segment. */
 2248                 return (1);
 2249         }
 2250 
 2251         /*
 2252          * If this socket is expecting signature but the segment does not
 2253          * contain any just fail.
 2254          */
 2255         if ((to->to_flags & TOF_SIGNATURE) == 0) {
 2256                 TCPSTAT_INC(tcps_sig_err_nosigopt);
 2257                 TCPSTAT_INC(tcps_sig_rcvbadsig);
 2258                 return (0);
 2259         }
 2260         if (tcp_signature_compute(m, off0, tlen, optlen, &tmpdigest[0],
 2261             IPSEC_DIR_INBOUND) == -1) {
 2262                 TCPSTAT_INC(tcps_sig_err_buildsig);
 2263                 TCPSTAT_INC(tcps_sig_rcvbadsig);
 2264                 return (0);
 2265         }
 2266         
 2267         if (bcmp(to->to_signature, &tmpdigest[0], TCP_SIGLEN) != 0) {
 2268                 TCPSTAT_INC(tcps_sig_rcvbadsig);
 2269                 return (0);
 2270         }
 2271         TCPSTAT_INC(tcps_sig_rcvgoodsig);
 2272         return (1);
 2273 }
 2274 #endif /* TCP_SIGNATURE */
 2275 
 2276 static int
 2277 sysctl_drop(SYSCTL_HANDLER_ARGS)
 2278 {
 2279         /* addrs[0] is a foreign socket, addrs[1] is a local one. */
 2280         struct sockaddr_storage addrs[2];
 2281         struct inpcb *inp;
 2282         struct tcpcb *tp;
 2283         struct tcptw *tw;
 2284         struct sockaddr_in *fin, *lin;
 2285 #ifdef INET6
 2286         struct sockaddr_in6 *fin6, *lin6;
 2287 #endif
 2288         int error;
 2289 
 2290         inp = NULL;
 2291         fin = lin = NULL;
 2292 #ifdef INET6
 2293         fin6 = lin6 = NULL;
 2294 #endif
 2295         error = 0;
 2296 
 2297         if (req->oldptr != NULL || req->oldlen != 0)
 2298                 return (EINVAL);
 2299         if (req->newptr == NULL)
 2300                 return (EPERM);
 2301         if (req->newlen < sizeof(addrs))
 2302                 return (ENOMEM);
 2303         error = SYSCTL_IN(req, &addrs, sizeof(addrs));
 2304         if (error)
 2305                 return (error);
 2306 
 2307         switch (addrs[0].ss_family) {
 2308 #ifdef INET6
 2309         case AF_INET6:
 2310                 fin6 = (struct sockaddr_in6 *)&addrs[0];
 2311                 lin6 = (struct sockaddr_in6 *)&addrs[1];
 2312                 if (fin6->sin6_len != sizeof(struct sockaddr_in6) ||
 2313                     lin6->sin6_len != sizeof(struct sockaddr_in6))
 2314                         return (EINVAL);
 2315                 if (IN6_IS_ADDR_V4MAPPED(&fin6->sin6_addr)) {
 2316                         if (!IN6_IS_ADDR_V4MAPPED(&lin6->sin6_addr))
 2317                                 return (EINVAL);
 2318                         in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[0]);
 2319                         in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[1]);
 2320                         fin = (struct sockaddr_in *)&addrs[0];
 2321                         lin = (struct sockaddr_in *)&addrs[1];
 2322                         break;
 2323                 }
 2324                 error = sa6_embedscope(fin6, V_ip6_use_defzone);
 2325                 if (error)
 2326                         return (error);
 2327                 error = sa6_embedscope(lin6, V_ip6_use_defzone);
 2328                 if (error)
 2329                         return (error);
 2330                 break;
 2331 #endif
 2332         case AF_INET:
 2333                 fin = (struct sockaddr_in *)&addrs[0];
 2334                 lin = (struct sockaddr_in *)&addrs[1];
 2335                 if (fin->sin_len != sizeof(struct sockaddr_in) ||
 2336                     lin->sin_len != sizeof(struct sockaddr_in))
 2337                         return (EINVAL);
 2338                 break;
 2339         default:
 2340                 return (EINVAL);
 2341         }
 2342         INP_INFO_WLOCK(&V_tcbinfo);
 2343         switch (addrs[0].ss_family) {
 2344 #ifdef INET6
 2345         case AF_INET6:
 2346                 inp = in6_pcblookup_hash(&V_tcbinfo, &fin6->sin6_addr,
 2347                     fin6->sin6_port, &lin6->sin6_addr, lin6->sin6_port, 0,
 2348                     NULL);
 2349                 break;
 2350 #endif
 2351         case AF_INET:
 2352                 inp = in_pcblookup_hash(&V_tcbinfo, fin->sin_addr,
 2353                     fin->sin_port, lin->sin_addr, lin->sin_port, 0, NULL);
 2354                 break;
 2355         }
 2356         if (inp != NULL) {
 2357                 INP_WLOCK(inp);
 2358                 if (inp->inp_flags & INP_TIMEWAIT) {
 2359                         /*
 2360                          * XXXRW: There currently exists a state where an
 2361                          * inpcb is present, but its timewait state has been
 2362                          * discarded.  For now, don't allow dropping of this
 2363                          * type of inpcb.
 2364                          */
 2365                         tw = intotw(inp);
 2366                         if (tw != NULL)
 2367                                 tcp_twclose(tw, 0);
 2368                         else
 2369                                 INP_WUNLOCK(inp);
 2370                 } else if (!(inp->inp_flags & INP_DROPPED) &&
 2371                            !(inp->inp_socket->so_options & SO_ACCEPTCONN)) {
 2372                         tp = intotcpcb(inp);
 2373                         tp = tcp_drop(tp, ECONNABORTED);
 2374                         if (tp != NULL)
 2375                                 INP_WUNLOCK(inp);
 2376                 } else
 2377                         INP_WUNLOCK(inp);
 2378         } else
 2379                 error = ESRCH;
 2380         INP_INFO_WUNLOCK(&V_tcbinfo);
 2381         return (error);
 2382 }
 2383 
 2384 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DROP, drop,
 2385     CTLTYPE_STRUCT|CTLFLAG_WR|CTLFLAG_SKIP, NULL,
 2386     0, sysctl_drop, "", "Drop TCP connection");
 2387 
 2388 /*
 2389  * Generate a standardized TCP log line for use throughout the
 2390  * tcp subsystem.  Memory allocation is done with M_NOWAIT to
 2391  * allow use in the interrupt context.
 2392  *
 2393  * NB: The caller MUST free(s, M_TCPLOG) the returned string.
 2394  * NB: The function may return NULL if memory allocation failed.
 2395  *
 2396  * Due to header inclusion and ordering limitations the struct ip
 2397  * and ip6_hdr pointers have to be passed as void pointers.
 2398  */
 2399 char *
 2400 tcp_log_vain(struct in_conninfo *inc, struct tcphdr *th, void *ip4hdr,
 2401     const void *ip6hdr)
 2402 {
 2403 
 2404         /* Is logging enabled? */
 2405         if (tcp_log_in_vain == 0)
 2406                 return (NULL);
 2407 
 2408         return (tcp_log_addr(inc, th, ip4hdr, ip6hdr));
 2409 }
 2410 
 2411 char *
 2412 tcp_log_addrs(struct in_conninfo *inc, struct tcphdr *th, void *ip4hdr,
 2413     const void *ip6hdr)
 2414 {
 2415 
 2416         /* Is logging enabled? */
 2417         if (tcp_log_debug == 0)
 2418                 return (NULL);
 2419 
 2420         return (tcp_log_addr(inc, th, ip4hdr, ip6hdr));
 2421 }
 2422 
 2423 static char *
 2424 tcp_log_addr(struct in_conninfo *inc, struct tcphdr *th, void *ip4hdr,
 2425     const void *ip6hdr)
 2426 {
 2427         char *s, *sp;
 2428         size_t size;
 2429         struct ip *ip;
 2430 #ifdef INET6
 2431         const struct ip6_hdr *ip6;
 2432 
 2433         ip6 = (const struct ip6_hdr *)ip6hdr;
 2434 #endif /* INET6 */
 2435         ip = (struct ip *)ip4hdr;
 2436 
 2437         /*
 2438          * The log line looks like this:
 2439          * "TCP: [1.2.3.4]:50332 to [1.2.3.4]:80 tcpflags 0x2<SYN>"
 2440          */
 2441         size = sizeof("TCP: []:12345 to []:12345 tcpflags 0x2<>") +
 2442             sizeof(PRINT_TH_FLAGS) + 1 +
 2443 #ifdef INET6
 2444             2 * INET6_ADDRSTRLEN;
 2445 #else
 2446             2 * INET_ADDRSTRLEN;
 2447 #endif /* INET6 */
 2448 
 2449         s = malloc(size, M_TCPLOG, M_ZERO|M_NOWAIT);
 2450         if (s == NULL)
 2451                 return (NULL);
 2452 
 2453         strcat(s, "TCP: [");
 2454         sp = s + strlen(s);
 2455 
 2456         if (inc && ((inc->inc_flags & INC_ISIPV6) == 0)) {
 2457                 inet_ntoa_r(inc->inc_faddr, sp);
 2458                 sp = s + strlen(s);
 2459                 sprintf(sp, "]:%i to [", ntohs(inc->inc_fport));
 2460                 sp = s + strlen(s);
 2461                 inet_ntoa_r(inc->inc_laddr, sp);
 2462                 sp = s + strlen(s);
 2463                 sprintf(sp, "]:%i", ntohs(inc->inc_lport));
 2464 #ifdef INET6
 2465         } else if (inc) {
 2466                 ip6_sprintf(sp, &inc->inc6_faddr);
 2467                 sp = s + strlen(s);
 2468                 sprintf(sp, "]:%i to [", ntohs(inc->inc_fport));
 2469                 sp = s + strlen(s);
 2470                 ip6_sprintf(sp, &inc->inc6_laddr);
 2471                 sp = s + strlen(s);
 2472                 sprintf(sp, "]:%i", ntohs(inc->inc_lport));
 2473         } else if (ip6 && th) {
 2474                 ip6_sprintf(sp, &ip6->ip6_src);
 2475                 sp = s + strlen(s);
 2476                 sprintf(sp, "]:%i to [", ntohs(th->th_sport));
 2477                 sp = s + strlen(s);
 2478                 ip6_sprintf(sp, &ip6->ip6_dst);
 2479                 sp = s + strlen(s);
 2480                 sprintf(sp, "]:%i", ntohs(th->th_dport));
 2481 #endif /* INET6 */
 2482         } else if (ip && th) {
 2483                 inet_ntoa_r(ip->ip_src, sp);
 2484                 sp = s + strlen(s);
 2485                 sprintf(sp, "]:%i to [", ntohs(th->th_sport));
 2486                 sp = s + strlen(s);
 2487                 inet_ntoa_r(ip->ip_dst, sp);
 2488                 sp = s + strlen(s);
 2489                 sprintf(sp, "]:%i", ntohs(th->th_dport));
 2490         } else {
 2491                 free(s, M_TCPLOG);
 2492                 return (NULL);
 2493         }
 2494         sp = s + strlen(s);
 2495         if (th)
 2496                 sprintf(sp, " tcpflags 0x%b", th->th_flags, PRINT_TH_FLAGS);
 2497         if (*(s + size - 1) != '\0')
 2498                 panic("%s: string too long", __func__);
 2499         return (s);
 2500 }

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