The Design and Implementation of the FreeBSD Operating System, Second Edition
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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: releng/8.3/sys/netinet/tcp_subr.c 231391 2012-02-10 17:49:14Z tuexen $");
   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_INT(_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 void     tcp_isn_tick(void *);
  275 static char *   tcp_log_addr(struct in_conninfo *inc, struct tcphdr *th,
  276                     void *ip4hdr, const void *ip6hdr);
  277 
  278 /*
  279  * Target size of TCP PCB hash tables. Must be a power of two.
  280  *
  281  * Note that this can be overridden by the kernel environment
  282  * variable net.inet.tcp.tcbhashsize
  283  */
  284 #ifndef TCBHASHSIZE
  285 #define TCBHASHSIZE     512
  286 #endif
  287 
  288 /*
  289  * XXX
  290  * Callouts should be moved into struct tcp directly.  They are currently
  291  * separate because the tcpcb structure is exported to userland for sysctl
  292  * parsing purposes, which do not know about callouts.
  293  */
  294 struct tcpcb_mem {
  295         struct  tcpcb           tcb;
  296         struct  tcp_timer       tt;
  297         struct  cc_var          ccv;
  298         struct  osd             osd;
  299 };
  300 
  301 static VNET_DEFINE(uma_zone_t, tcpcb_zone);
  302 #define V_tcpcb_zone                    VNET(tcpcb_zone)
  303 
  304 MALLOC_DEFINE(M_TCPLOG, "tcplog", "TCP address and flags print buffers");
  305 struct callout isn_callout;
  306 static struct mtx isn_mtx;
  307 
  308 #define ISN_LOCK_INIT() mtx_init(&isn_mtx, "isn_mtx", NULL, MTX_DEF)
  309 #define ISN_LOCK()      mtx_lock(&isn_mtx)
  310 #define ISN_UNLOCK()    mtx_unlock(&isn_mtx)
  311 
  312 /*
  313  * TCP initialization.
  314  */
  315 static void
  316 tcp_zone_change(void *tag)
  317 {
  318 
  319         uma_zone_set_max(V_tcbinfo.ipi_zone, maxsockets);
  320         uma_zone_set_max(V_tcpcb_zone, maxsockets);
  321         tcp_tw_zone_change();
  322 }
  323 
  324 static int
  325 tcp_inpcb_init(void *mem, int size, int flags)
  326 {
  327         struct inpcb *inp = mem;
  328 
  329         INP_LOCK_INIT(inp, "inp", "tcpinp");
  330         return (0);
  331 }
  332 
  333 void
  334 tcp_init(void)
  335 {
  336         int hashsize;
  337 
  338         INP_INFO_LOCK_INIT(&V_tcbinfo, "tcp");
  339         LIST_INIT(&V_tcb);
  340 #ifdef VIMAGE
  341         V_tcbinfo.ipi_vnet = curvnet;
  342 #endif
  343         V_tcbinfo.ipi_listhead = &V_tcb;
  344 
  345         if (hhook_head_register(HHOOK_TYPE_TCP, HHOOK_TCP_EST_IN,
  346             &V_tcp_hhh[HHOOK_TCP_EST_IN], HHOOK_NOWAIT|HHOOK_HEADISINVNET) != 0)
  347                 printf("%s: WARNING: unable to register helper hook\n", __func__);
  348         if (hhook_head_register(HHOOK_TYPE_TCP, HHOOK_TCP_EST_OUT,
  349             &V_tcp_hhh[HHOOK_TCP_EST_OUT], HHOOK_NOWAIT|HHOOK_HEADISINVNET) != 0)
  350                 printf("%s: WARNING: unable to register helper hook\n", __func__);
  351 
  352         hashsize = TCBHASHSIZE;
  353         TUNABLE_INT_FETCH("net.inet.tcp.tcbhashsize", &hashsize);
  354         if (!powerof2(hashsize)) {
  355                 printf("WARNING: TCB hash size not a power of 2\n");
  356                 hashsize = 512; /* safe default */
  357         }
  358         V_tcbinfo.ipi_hashbase = hashinit(hashsize, M_PCB,
  359             &V_tcbinfo.ipi_hashmask);
  360         V_tcbinfo.ipi_porthashbase = hashinit(hashsize, M_PCB,
  361             &V_tcbinfo.ipi_porthashmask);
  362         V_tcbinfo.ipi_zone = uma_zcreate("tcp_inpcb", sizeof(struct inpcb),
  363             NULL, NULL, tcp_inpcb_init, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
  364         uma_zone_set_max(V_tcbinfo.ipi_zone, maxsockets);
  365         V_tcp_inflight_rttthresh = TCPTV_INFLIGHT_RTTTHRESH;
  366 
  367         /*
  368          * These have to be type stable for the benefit of the timers.
  369          */
  370         V_tcpcb_zone = uma_zcreate("tcpcb", sizeof(struct tcpcb_mem),
  371             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
  372         uma_zone_set_max(V_tcpcb_zone, maxsockets);
  373 
  374         tcp_tw_init();
  375         syncache_init();
  376         tcp_hc_init();
  377         tcp_reass_init();
  378 
  379         TUNABLE_INT_FETCH("net.inet.tcp.sack.enable", &V_tcp_do_sack);
  380         V_sack_hole_zone = uma_zcreate("sackhole", sizeof(struct sackhole),
  381             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
  382 
  383         /* Skip initialization of globals for non-default instances. */
  384         if (!IS_DEFAULT_VNET(curvnet))
  385                 return;
  386 
  387         /* XXX virtualize those bellow? */
  388         tcp_delacktime = TCPTV_DELACK;
  389         tcp_keepinit = TCPTV_KEEP_INIT;
  390         tcp_keepidle = TCPTV_KEEP_IDLE;
  391         tcp_keepintvl = TCPTV_KEEPINTVL;
  392         tcp_maxpersistidle = TCPTV_KEEP_IDLE;
  393         tcp_msl = TCPTV_MSL;
  394         tcp_rexmit_min = TCPTV_MIN;
  395         if (tcp_rexmit_min < 1)
  396                 tcp_rexmit_min = 1;
  397         tcp_rexmit_slop = TCPTV_CPU_VAR;
  398         tcp_finwait2_timeout = TCPTV_FINWAIT2_TIMEOUT;
  399         tcp_tcbhashsize = hashsize;
  400 
  401 #ifdef INET6
  402 #define TCP_MINPROTOHDR (sizeof(struct ip6_hdr) + sizeof(struct tcphdr))
  403 #else /* INET6 */
  404 #define TCP_MINPROTOHDR (sizeof(struct tcpiphdr))
  405 #endif /* INET6 */
  406         if (max_protohdr < TCP_MINPROTOHDR)
  407                 max_protohdr = TCP_MINPROTOHDR;
  408         if (max_linkhdr + TCP_MINPROTOHDR > MHLEN)
  409                 panic("tcp_init");
  410 #undef TCP_MINPROTOHDR
  411 
  412         ISN_LOCK_INIT();
  413         callout_init(&isn_callout, CALLOUT_MPSAFE);
  414         callout_reset(&isn_callout, hz/100, tcp_isn_tick, NULL);
  415         EVENTHANDLER_REGISTER(shutdown_pre_sync, tcp_fini, NULL,
  416                 SHUTDOWN_PRI_DEFAULT);
  417         EVENTHANDLER_REGISTER(maxsockets_change, tcp_zone_change, NULL,
  418                 EVENTHANDLER_PRI_ANY);
  419 }
  420 
  421 #ifdef VIMAGE
  422 void
  423 tcp_destroy(void)
  424 {
  425 
  426         tcp_reass_destroy();
  427         tcp_hc_destroy();
  428         syncache_destroy();
  429         tcp_tw_destroy();
  430 
  431         /* XXX check that hashes are empty! */
  432         hashdestroy(V_tcbinfo.ipi_hashbase, M_PCB,
  433             V_tcbinfo.ipi_hashmask);
  434         hashdestroy(V_tcbinfo.ipi_porthashbase, M_PCB,
  435             V_tcbinfo.ipi_porthashmask);
  436 
  437         uma_zdestroy(V_sack_hole_zone);
  438         uma_zdestroy(V_tcpcb_zone);
  439         uma_zdestroy(V_tcbinfo.ipi_zone);
  440 
  441         INP_INFO_LOCK_DESTROY(&V_tcbinfo);
  442 }
  443 #endif
  444 
  445 void
  446 tcp_fini(void *xtp)
  447 {
  448 
  449         callout_stop(&isn_callout);
  450 }
  451 
  452 /*
  453  * Fill in the IP and TCP headers for an outgoing packet, given the tcpcb.
  454  * tcp_template used to store this data in mbufs, but we now recopy it out
  455  * of the tcpcb each time to conserve mbufs.
  456  */
  457 void
  458 tcpip_fillheaders(struct inpcb *inp, void *ip_ptr, void *tcp_ptr)
  459 {
  460         struct tcphdr *th = (struct tcphdr *)tcp_ptr;
  461 
  462         INP_WLOCK_ASSERT(inp);
  463 
  464 #ifdef INET6
  465         if ((inp->inp_vflag & INP_IPV6) != 0) {
  466                 struct ip6_hdr *ip6;
  467 
  468                 ip6 = (struct ip6_hdr *)ip_ptr;
  469                 ip6->ip6_flow = (ip6->ip6_flow & ~IPV6_FLOWINFO_MASK) |
  470                         (inp->inp_flow & IPV6_FLOWINFO_MASK);
  471                 ip6->ip6_vfc = (ip6->ip6_vfc & ~IPV6_VERSION_MASK) |
  472                         (IPV6_VERSION & IPV6_VERSION_MASK);
  473                 ip6->ip6_nxt = IPPROTO_TCP;
  474                 ip6->ip6_plen = htons(sizeof(struct tcphdr));
  475                 ip6->ip6_src = inp->in6p_laddr;
  476                 ip6->ip6_dst = inp->in6p_faddr;
  477         } else
  478 #endif
  479         {
  480                 struct ip *ip;
  481 
  482                 ip = (struct ip *)ip_ptr;
  483                 ip->ip_v = IPVERSION;
  484                 ip->ip_hl = 5;
  485                 ip->ip_tos = inp->inp_ip_tos;
  486                 ip->ip_len = 0;
  487                 ip->ip_id = 0;
  488                 ip->ip_off = 0;
  489                 ip->ip_ttl = inp->inp_ip_ttl;
  490                 ip->ip_sum = 0;
  491                 ip->ip_p = IPPROTO_TCP;
  492                 ip->ip_src = inp->inp_laddr;
  493                 ip->ip_dst = inp->inp_faddr;
  494         }
  495         th->th_sport = inp->inp_lport;
  496         th->th_dport = inp->inp_fport;
  497         th->th_seq = 0;
  498         th->th_ack = 0;
  499         th->th_x2 = 0;
  500         th->th_off = 5;
  501         th->th_flags = 0;
  502         th->th_win = 0;
  503         th->th_urp = 0;
  504         th->th_sum = 0;         /* in_pseudo() is called later for ipv4 */
  505 }
  506 
  507 /*
  508  * Create template to be used to send tcp packets on a connection.
  509  * Allocates an mbuf and fills in a skeletal tcp/ip header.  The only
  510  * use for this function is in keepalives, which use tcp_respond.
  511  */
  512 struct tcptemp *
  513 tcpip_maketemplate(struct inpcb *inp)
  514 {
  515         struct tcptemp *t;
  516 
  517         t = malloc(sizeof(*t), M_TEMP, M_NOWAIT);
  518         if (t == NULL)
  519                 return (NULL);
  520         tcpip_fillheaders(inp, (void *)&t->tt_ipgen, (void *)&t->tt_t);
  521         return (t);
  522 }
  523 
  524 /*
  525  * Send a single message to the TCP at address specified by
  526  * the given TCP/IP header.  If m == NULL, then we make a copy
  527  * of the tcpiphdr at ti and send directly to the addressed host.
  528  * This is used to force keep alive messages out using the TCP
  529  * template for a connection.  If flags are given then we send
  530  * a message back to the TCP which originated the * segment ti,
  531  * and discard the mbuf containing it and any other attached mbufs.
  532  *
  533  * In any case the ack and sequence number of the transmitted
  534  * segment are as specified by the parameters.
  535  *
  536  * NOTE: If m != NULL, then ti must point to *inside* the mbuf.
  537  */
  538 void
  539 tcp_respond(struct tcpcb *tp, void *ipgen, struct tcphdr *th, struct mbuf *m,
  540     tcp_seq ack, tcp_seq seq, int flags)
  541 {
  542         int tlen;
  543         int win = 0;
  544         struct ip *ip;
  545         struct tcphdr *nth;
  546 #ifdef INET6
  547         struct ip6_hdr *ip6;
  548         int isipv6;
  549 #endif /* INET6 */
  550         int ipflags = 0;
  551         struct inpcb *inp;
  552 
  553         KASSERT(tp != NULL || m != NULL, ("tcp_respond: tp and m both NULL"));
  554 
  555 #ifdef INET6
  556         isipv6 = ((struct ip *)ipgen)->ip_v == 6;
  557         ip6 = ipgen;
  558 #endif /* INET6 */
  559         ip = ipgen;
  560 
  561         if (tp != NULL) {
  562                 inp = tp->t_inpcb;
  563                 KASSERT(inp != NULL, ("tcp control block w/o inpcb"));
  564                 INP_WLOCK_ASSERT(inp);
  565         } else
  566                 inp = NULL;
  567 
  568         if (tp != NULL) {
  569                 if (!(flags & TH_RST)) {
  570                         win = sbspace(&inp->inp_socket->so_rcv);
  571                         if (win > (long)TCP_MAXWIN << tp->rcv_scale)
  572                                 win = (long)TCP_MAXWIN << tp->rcv_scale;
  573                 }
  574         }
  575         if (m == NULL) {
  576                 m = m_gethdr(M_DONTWAIT, MT_DATA);
  577                 if (m == NULL)
  578                         return;
  579                 tlen = 0;
  580                 m->m_data += max_linkhdr;
  581 #ifdef INET6
  582                 if (isipv6) {
  583                         bcopy((caddr_t)ip6, mtod(m, caddr_t),
  584                               sizeof(struct ip6_hdr));
  585                         ip6 = mtod(m, struct ip6_hdr *);
  586                         nth = (struct tcphdr *)(ip6 + 1);
  587                 } else
  588 #endif /* INET6 */
  589               {
  590                 bcopy((caddr_t)ip, mtod(m, caddr_t), sizeof(struct ip));
  591                 ip = mtod(m, struct ip *);
  592                 nth = (struct tcphdr *)(ip + 1);
  593               }
  594                 bcopy((caddr_t)th, (caddr_t)nth, sizeof(struct tcphdr));
  595                 flags = TH_ACK;
  596         } else {
  597                 /*
  598                  *  reuse the mbuf. 
  599                  * XXX MRT We inherrit the FIB, which is lucky.
  600                  */
  601                 m_freem(m->m_next);
  602                 m->m_next = NULL;
  603                 m->m_data = (caddr_t)ipgen;
  604                 /* m_len is set later */
  605                 tlen = 0;
  606 #define xchg(a,b,type) { type t; t=a; a=b; b=t; }
  607 #ifdef INET6
  608                 if (isipv6) {
  609                         xchg(ip6->ip6_dst, ip6->ip6_src, struct in6_addr);
  610                         nth = (struct tcphdr *)(ip6 + 1);
  611                 } else
  612 #endif /* INET6 */
  613               {
  614                 xchg(ip->ip_dst.s_addr, ip->ip_src.s_addr, uint32_t);
  615                 nth = (struct tcphdr *)(ip + 1);
  616               }
  617                 if (th != nth) {
  618                         /*
  619                          * this is usually a case when an extension header
  620                          * exists between the IPv6 header and the
  621                          * TCP header.
  622                          */
  623                         nth->th_sport = th->th_sport;
  624                         nth->th_dport = th->th_dport;
  625                 }
  626                 xchg(nth->th_dport, nth->th_sport, uint16_t);
  627 #undef xchg
  628         }
  629 #ifdef INET6
  630         if (isipv6) {
  631                 ip6->ip6_flow = 0;
  632                 ip6->ip6_vfc = IPV6_VERSION;
  633                 ip6->ip6_nxt = IPPROTO_TCP;
  634                 ip6->ip6_plen = htons((u_short)(sizeof (struct tcphdr) +
  635                                                 tlen));
  636                 tlen += sizeof (struct ip6_hdr) + sizeof (struct tcphdr);
  637         } else
  638 #endif
  639         {
  640                 tlen += sizeof (struct tcpiphdr);
  641                 ip->ip_len = tlen;
  642                 ip->ip_ttl = V_ip_defttl;
  643                 if (V_path_mtu_discovery)
  644                         ip->ip_off |= IP_DF;
  645         }
  646         m->m_len = tlen;
  647         m->m_pkthdr.len = tlen;
  648         m->m_pkthdr.rcvif = NULL;
  649 #ifdef MAC
  650         if (inp != NULL) {
  651                 /*
  652                  * Packet is associated with a socket, so allow the
  653                  * label of the response to reflect the socket label.
  654                  */
  655                 INP_WLOCK_ASSERT(inp);
  656                 mac_inpcb_create_mbuf(inp, m);
  657         } else {
  658                 /*
  659                  * Packet is not associated with a socket, so possibly
  660                  * update the label in place.
  661                  */
  662                 mac_netinet_tcp_reply(m);
  663         }
  664 #endif
  665         nth->th_seq = htonl(seq);
  666         nth->th_ack = htonl(ack);
  667         nth->th_x2 = 0;
  668         nth->th_off = sizeof (struct tcphdr) >> 2;
  669         nth->th_flags = flags;
  670         if (tp != NULL)
  671                 nth->th_win = htons((u_short) (win >> tp->rcv_scale));
  672         else
  673                 nth->th_win = htons((u_short)win);
  674         nth->th_urp = 0;
  675 #ifdef INET6
  676         if (isipv6) {
  677                 nth->th_sum = 0;
  678                 nth->th_sum = in6_cksum(m, IPPROTO_TCP,
  679                                         sizeof(struct ip6_hdr),
  680                                         tlen - sizeof(struct ip6_hdr));
  681                 ip6->ip6_hlim = in6_selecthlim(tp != NULL ? tp->t_inpcb :
  682                     NULL, NULL);
  683         } else
  684 #endif /* INET6 */
  685         {
  686                 nth->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr,
  687                     htons((u_short)(tlen - sizeof(struct ip) + ip->ip_p)));
  688                 m->m_pkthdr.csum_flags = CSUM_TCP;
  689                 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum);
  690         }
  691 #ifdef TCPDEBUG
  692         if (tp == NULL || (inp->inp_socket->so_options & SO_DEBUG))
  693                 tcp_trace(TA_OUTPUT, 0, tp, mtod(m, void *), th, 0);
  694 #endif
  695 #ifdef INET6
  696         if (isipv6)
  697                 (void) ip6_output(m, NULL, NULL, ipflags, NULL, NULL, inp);
  698         else
  699 #endif /* INET6 */
  700         (void) ip_output(m, NULL, NULL, ipflags, NULL, inp);
  701 }
  702 
  703 /*
  704  * Create a new TCP control block, making an
  705  * empty reassembly queue and hooking it to the argument
  706  * protocol control block.  The `inp' parameter must have
  707  * come from the zone allocator set up in tcp_init().
  708  */
  709 struct tcpcb *
  710 tcp_newtcpcb(struct inpcb *inp)
  711 {
  712         struct tcpcb_mem *tm;
  713         struct tcpcb *tp;
  714 #ifdef INET6
  715         int isipv6 = (inp->inp_vflag & INP_IPV6) != 0;
  716 #endif /* INET6 */
  717 
  718         tm = uma_zalloc(V_tcpcb_zone, M_NOWAIT | M_ZERO);
  719         if (tm == NULL)
  720                 return (NULL);
  721         tp = &tm->tcb;
  722 
  723         /* Initialise cc_var struct for this tcpcb. */
  724         tp->ccv = &tm->ccv;
  725         tp->ccv->type = IPPROTO_TCP;
  726         tp->ccv->ccvc.tcp = tp;
  727 
  728         /*
  729          * Use the current system default CC algorithm.
  730          */
  731         CC_LIST_RLOCK();
  732         KASSERT(!STAILQ_EMPTY(&cc_list), ("cc_list is empty!"));
  733         CC_ALGO(tp) = CC_DEFAULT();
  734         CC_LIST_RUNLOCK();
  735 
  736         if (CC_ALGO(tp)->cb_init != NULL)
  737                 if (CC_ALGO(tp)->cb_init(tp->ccv) > 0) {
  738                         uma_zfree(V_tcpcb_zone, tm);
  739                         return (NULL);
  740                 }
  741 
  742         tp->osd = &tm->osd;
  743         if (khelp_init_osd(HELPER_CLASS_TCP, tp->osd)) {
  744                 uma_zfree(V_tcpcb_zone, tm);
  745                 return (NULL);
  746         }
  747 
  748 #ifdef VIMAGE
  749         tp->t_vnet = inp->inp_vnet;
  750 #endif
  751         tp->t_timers = &tm->tt;
  752         /*      LIST_INIT(&tp->t_segq); */      /* XXX covered by M_ZERO */
  753         tp->t_maxseg = tp->t_maxopd =
  754 #ifdef INET6
  755                 isipv6 ? V_tcp_v6mssdflt :
  756 #endif /* INET6 */
  757                 V_tcp_mssdflt;
  758 
  759         /* Set up our timeouts. */
  760         callout_init(&tp->t_timers->tt_rexmt, CALLOUT_MPSAFE);
  761         callout_init(&tp->t_timers->tt_persist, CALLOUT_MPSAFE);
  762         callout_init(&tp->t_timers->tt_keep, CALLOUT_MPSAFE);
  763         callout_init(&tp->t_timers->tt_2msl, CALLOUT_MPSAFE);
  764         callout_init(&tp->t_timers->tt_delack, CALLOUT_MPSAFE);
  765 
  766         if (V_tcp_do_rfc1323)
  767                 tp->t_flags = (TF_REQ_SCALE|TF_REQ_TSTMP);
  768         if (V_tcp_do_sack)
  769                 tp->t_flags |= TF_SACK_PERMIT;
  770         TAILQ_INIT(&tp->snd_holes);
  771         tp->t_inpcb = inp;      /* XXX */
  772         /*
  773          * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no
  774          * rtt estimate.  Set rttvar so that srtt + 4 * rttvar gives
  775          * reasonable initial retransmit time.
  776          */
  777         tp->t_srtt = TCPTV_SRTTBASE;
  778         tp->t_rttvar = ((TCPTV_RTOBASE - TCPTV_SRTTBASE) << TCP_RTTVAR_SHIFT) / 4;
  779         tp->t_rttmin = tcp_rexmit_min;
  780         tp->t_rxtcur = TCPTV_RTOBASE;
  781         tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
  782         tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
  783         tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT;
  784         tp->t_rcvtime = ticks;
  785         tp->t_bw_rtttime = ticks;
  786         /*
  787          * IPv4 TTL initialization is necessary for an IPv6 socket as well,
  788          * because the socket may be bound to an IPv6 wildcard address,
  789          * which may match an IPv4-mapped IPv6 address.
  790          */
  791         inp->inp_ip_ttl = V_ip_defttl;
  792         inp->inp_ppcb = tp;
  793         return (tp);            /* XXX */
  794 }
  795 
  796 /*
  797  * Switch the congestion control algorithm back to NewReno for any active
  798  * control blocks using an algorithm which is about to go away.
  799  * This ensures the CC framework can allow the unload to proceed without leaving
  800  * any dangling pointers which would trigger a panic.
  801  * Returning non-zero would inform the CC framework that something went wrong
  802  * and it would be unsafe to allow the unload to proceed. However, there is no
  803  * way for this to occur with this implementation so we always return zero.
  804  */
  805 int
  806 tcp_ccalgounload(struct cc_algo *unload_algo)
  807 {
  808         struct cc_algo *tmpalgo;
  809         struct inpcb *inp;
  810         struct tcpcb *tp;
  811         VNET_ITERATOR_DECL(vnet_iter);
  812 
  813         /*
  814          * Check all active control blocks across all network stacks and change
  815          * any that are using "unload_algo" back to NewReno. If "unload_algo"
  816          * requires cleanup code to be run, call it.
  817          */
  818         VNET_LIST_RLOCK();
  819         VNET_FOREACH(vnet_iter) {
  820                 CURVNET_SET(vnet_iter);
  821                 INP_INFO_RLOCK(&V_tcbinfo);
  822                 /*
  823                  * New connections already part way through being initialised
  824                  * with the CC algo we're removing will not race with this code
  825                  * because the INP_INFO_WLOCK is held during initialisation. We
  826                  * therefore don't enter the loop below until the connection
  827                  * list has stabilised.
  828                  */
  829                 LIST_FOREACH(inp, &V_tcb, inp_list) {
  830                         INP_WLOCK(inp);
  831                         /* Important to skip tcptw structs. */
  832                         if (!(inp->inp_flags & INP_TIMEWAIT) &&
  833                             (tp = intotcpcb(inp)) != NULL) {
  834                                 /*
  835                                  * By holding INP_WLOCK here, we are assured
  836                                  * that the connection is not currently
  837                                  * executing inside the CC module's functions
  838                                  * i.e. it is safe to make the switch back to
  839                                  * NewReno.
  840                                  */
  841                                 if (CC_ALGO(tp) == unload_algo) {
  842                                         tmpalgo = CC_ALGO(tp);
  843                                         /* NewReno does not require any init. */
  844                                         CC_ALGO(tp) = &newreno_cc_algo;
  845                                         if (tmpalgo->cb_destroy != NULL)
  846                                                 tmpalgo->cb_destroy(tp->ccv);
  847                                 }
  848                         }
  849                         INP_WUNLOCK(inp);
  850                 }
  851                 INP_INFO_RUNLOCK(&V_tcbinfo);
  852                 CURVNET_RESTORE();
  853         }
  854         VNET_LIST_RUNLOCK();
  855 
  856         return (0);
  857 }
  858 
  859 /*
  860  * Drop a TCP connection, reporting
  861  * the specified error.  If connection is synchronized,
  862  * then send a RST to peer.
  863  */
  864 struct tcpcb *
  865 tcp_drop(struct tcpcb *tp, int errno)
  866 {
  867         struct socket *so = tp->t_inpcb->inp_socket;
  868 
  869         INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
  870         INP_WLOCK_ASSERT(tp->t_inpcb);
  871 
  872         if (TCPS_HAVERCVDSYN(tp->t_state)) {
  873                 tp->t_state = TCPS_CLOSED;
  874                 (void) tcp_output_reset(tp);
  875                 TCPSTAT_INC(tcps_drops);
  876         } else
  877                 TCPSTAT_INC(tcps_conndrops);
  878         if (errno == ETIMEDOUT && tp->t_softerror)
  879                 errno = tp->t_softerror;
  880         so->so_error = errno;
  881         return (tcp_close(tp));
  882 }
  883 
  884 void
  885 tcp_discardcb(struct tcpcb *tp)
  886 {
  887         struct inpcb *inp = tp->t_inpcb;
  888         struct socket *so = inp->inp_socket;
  889 #ifdef INET6
  890         int isipv6 = (inp->inp_vflag & INP_IPV6) != 0;
  891 #endif /* INET6 */
  892 
  893         INP_WLOCK_ASSERT(inp);
  894 
  895         /*
  896          * Make sure that all of our timers are stopped before we
  897          * delete the PCB.
  898          */
  899         callout_stop(&tp->t_timers->tt_rexmt);
  900         callout_stop(&tp->t_timers->tt_persist);
  901         callout_stop(&tp->t_timers->tt_keep);
  902         callout_stop(&tp->t_timers->tt_2msl);
  903         callout_stop(&tp->t_timers->tt_delack);
  904 
  905         /*
  906          * If we got enough samples through the srtt filter,
  907          * save the rtt and rttvar in the routing entry.
  908          * 'Enough' is arbitrarily defined as 4 rtt samples.
  909          * 4 samples is enough for the srtt filter to converge
  910          * to within enough % of the correct value; fewer samples
  911          * and we could save a bogus rtt. The danger is not high
  912          * as tcp quickly recovers from everything.
  913          * XXX: Works very well but needs some more statistics!
  914          */
  915         if (tp->t_rttupdated >= 4) {
  916                 struct hc_metrics_lite metrics;
  917                 u_long ssthresh;
  918 
  919                 bzero(&metrics, sizeof(metrics));
  920                 /*
  921                  * Update the ssthresh always when the conditions below
  922                  * are satisfied. This gives us better new start value
  923                  * for the congestion avoidance for new connections.
  924                  * ssthresh is only set if packet loss occured on a session.
  925                  *
  926                  * XXXRW: 'so' may be NULL here, and/or socket buffer may be
  927                  * being torn down.  Ideally this code would not use 'so'.
  928                  */
  929                 ssthresh = tp->snd_ssthresh;
  930                 if (ssthresh != 0 && ssthresh < so->so_snd.sb_hiwat / 2) {
  931                         /*
  932                          * convert the limit from user data bytes to
  933                          * packets then to packet data bytes.
  934                          */
  935                         ssthresh = (ssthresh + tp->t_maxseg / 2) / tp->t_maxseg;
  936                         if (ssthresh < 2)
  937                                 ssthresh = 2;
  938                         ssthresh *= (u_long)(tp->t_maxseg +
  939 #ifdef INET6
  940                                       (isipv6 ? sizeof (struct ip6_hdr) +
  941                                                sizeof (struct tcphdr) :
  942 #endif
  943                                        sizeof (struct tcpiphdr)
  944 #ifdef INET6
  945                                        )
  946 #endif
  947                                       );
  948                 } else
  949                         ssthresh = 0;
  950                 metrics.rmx_ssthresh = ssthresh;
  951 
  952                 metrics.rmx_rtt = tp->t_srtt;
  953                 metrics.rmx_rttvar = tp->t_rttvar;
  954                 /* XXX: This wraps if the pipe is more than 4 Gbit per second */
  955                 metrics.rmx_bandwidth = tp->snd_bandwidth;
  956                 metrics.rmx_cwnd = tp->snd_cwnd;
  957                 metrics.rmx_sendpipe = 0;
  958                 metrics.rmx_recvpipe = 0;
  959 
  960                 tcp_hc_update(&inp->inp_inc, &metrics);
  961         }
  962 
  963         /* free the reassembly queue, if any */
  964         tcp_reass_flush(tp);
  965         /* Disconnect offload device, if any. */
  966         tcp_offload_detach(tp);
  967                 
  968         tcp_free_sackholes(tp);
  969 
  970         /* Allow the CC algorithm to clean up after itself. */
  971         if (CC_ALGO(tp)->cb_destroy != NULL)
  972                 CC_ALGO(tp)->cb_destroy(tp->ccv);
  973 
  974         khelp_destroy_osd(tp->osd);
  975 
  976         CC_ALGO(tp) = NULL;
  977         inp->inp_ppcb = NULL;
  978         tp->t_inpcb = NULL;
  979         uma_zfree(V_tcpcb_zone, tp);
  980 }
  981 
  982 /*
  983  * Attempt to close a TCP control block, marking it as dropped, and freeing
  984  * the socket if we hold the only reference.
  985  */
  986 struct tcpcb *
  987 tcp_close(struct tcpcb *tp)
  988 {
  989         struct inpcb *inp = tp->t_inpcb;
  990         struct socket *so;
  991 
  992         INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
  993         INP_WLOCK_ASSERT(inp);
  994 
  995         /* Notify any offload devices of listener close */
  996         if (tp->t_state == TCPS_LISTEN)
  997                 tcp_offload_listen_close(tp);
  998         in_pcbdrop(inp);
  999         TCPSTAT_INC(tcps_closed);
 1000         KASSERT(inp->inp_socket != NULL, ("tcp_close: inp_socket NULL"));
 1001         so = inp->inp_socket;
 1002         soisdisconnected(so);
 1003         if (inp->inp_flags & INP_SOCKREF) {
 1004                 KASSERT(so->so_state & SS_PROTOREF,
 1005                     ("tcp_close: !SS_PROTOREF"));
 1006                 inp->inp_flags &= ~INP_SOCKREF;
 1007                 INP_WUNLOCK(inp);
 1008                 ACCEPT_LOCK();
 1009                 SOCK_LOCK(so);
 1010                 so->so_state &= ~SS_PROTOREF;
 1011                 sofree(so);
 1012                 return (NULL);
 1013         }
 1014         return (tp);
 1015 }
 1016 
 1017 void
 1018 tcp_drain(void)
 1019 {
 1020         VNET_ITERATOR_DECL(vnet_iter);
 1021 
 1022         if (!do_tcpdrain)
 1023                 return;
 1024 
 1025         VNET_LIST_RLOCK_NOSLEEP();
 1026         VNET_FOREACH(vnet_iter) {
 1027                 CURVNET_SET(vnet_iter);
 1028                 struct inpcb *inpb;
 1029                 struct tcpcb *tcpb;
 1030 
 1031         /*
 1032          * Walk the tcpbs, if existing, and flush the reassembly queue,
 1033          * if there is one...
 1034          * XXX: The "Net/3" implementation doesn't imply that the TCP
 1035          *      reassembly queue should be flushed, but in a situation
 1036          *      where we're really low on mbufs, this is potentially
 1037          *      usefull.
 1038          */
 1039                 INP_INFO_RLOCK(&V_tcbinfo);
 1040                 LIST_FOREACH(inpb, V_tcbinfo.ipi_listhead, inp_list) {
 1041                         if (inpb->inp_flags & INP_TIMEWAIT)
 1042                                 continue;
 1043                         INP_WLOCK(inpb);
 1044                         if ((tcpb = intotcpcb(inpb)) != NULL) {
 1045                                 tcp_reass_flush(tcpb);
 1046                                 tcp_clean_sackreport(tcpb);
 1047                         }
 1048                         INP_WUNLOCK(inpb);
 1049                 }
 1050                 INP_INFO_RUNLOCK(&V_tcbinfo);
 1051                 CURVNET_RESTORE();
 1052         }
 1053         VNET_LIST_RUNLOCK_NOSLEEP();
 1054 }
 1055 
 1056 /*
 1057  * Notify a tcp user of an asynchronous error;
 1058  * store error as soft error, but wake up user
 1059  * (for now, won't do anything until can select for soft error).
 1060  *
 1061  * Do not wake up user since there currently is no mechanism for
 1062  * reporting soft errors (yet - a kqueue filter may be added).
 1063  */
 1064 static struct inpcb *
 1065 tcp_notify(struct inpcb *inp, int error)
 1066 {
 1067         struct tcpcb *tp;
 1068 
 1069         INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
 1070         INP_WLOCK_ASSERT(inp);
 1071 
 1072         if ((inp->inp_flags & INP_TIMEWAIT) ||
 1073             (inp->inp_flags & INP_DROPPED))
 1074                 return (inp);
 1075 
 1076         tp = intotcpcb(inp);
 1077         KASSERT(tp != NULL, ("tcp_notify: tp == NULL"));
 1078 
 1079         /*
 1080          * Ignore some errors if we are hooked up.
 1081          * If connection hasn't completed, has retransmitted several times,
 1082          * and receives a second error, give up now.  This is better
 1083          * than waiting a long time to establish a connection that
 1084          * can never complete.
 1085          */
 1086         if (tp->t_state == TCPS_ESTABLISHED &&
 1087             (error == EHOSTUNREACH || error == ENETUNREACH ||
 1088              error == EHOSTDOWN)) {
 1089                 return (inp);
 1090         } else if (tp->t_state < TCPS_ESTABLISHED && tp->t_rxtshift > 3 &&
 1091             tp->t_softerror) {
 1092                 tp = tcp_drop(tp, error);
 1093                 if (tp != NULL)
 1094                         return (inp);
 1095                 else
 1096                         return (NULL);
 1097         } else {
 1098                 tp->t_softerror = error;
 1099                 return (inp);
 1100         }
 1101 #if 0
 1102         wakeup( &so->so_timeo);
 1103         sorwakeup(so);
 1104         sowwakeup(so);
 1105 #endif
 1106 }
 1107 
 1108 static int
 1109 tcp_pcblist(SYSCTL_HANDLER_ARGS)
 1110 {
 1111         int error, i, m, n, pcb_count;
 1112         struct inpcb *inp, **inp_list;
 1113         inp_gen_t gencnt;
 1114         struct xinpgen xig;
 1115 
 1116         /*
 1117          * The process of preparing the TCB list is too time-consuming and
 1118          * resource-intensive to repeat twice on every request.
 1119          */
 1120         if (req->oldptr == NULL) {
 1121                 n = V_tcbinfo.ipi_count + syncache_pcbcount();
 1122                 n += imax(n / 8, 10);
 1123                 req->oldidx = 2 * (sizeof xig) + n * sizeof(struct xtcpcb);
 1124                 return (0);
 1125         }
 1126 
 1127         if (req->newptr != NULL)
 1128                 return (EPERM);
 1129 
 1130         /*
 1131          * OK, now we're committed to doing something.
 1132          */
 1133         INP_INFO_RLOCK(&V_tcbinfo);
 1134         gencnt = V_tcbinfo.ipi_gencnt;
 1135         n = V_tcbinfo.ipi_count;
 1136         INP_INFO_RUNLOCK(&V_tcbinfo);
 1137 
 1138         m = syncache_pcbcount();
 1139 
 1140         error = sysctl_wire_old_buffer(req, 2 * (sizeof xig)
 1141                 + (n + m) * sizeof(struct xtcpcb));
 1142         if (error != 0)
 1143                 return (error);
 1144 
 1145         xig.xig_len = sizeof xig;
 1146         xig.xig_count = n + m;
 1147         xig.xig_gen = gencnt;
 1148         xig.xig_sogen = so_gencnt;
 1149         error = SYSCTL_OUT(req, &xig, sizeof xig);
 1150         if (error)
 1151                 return (error);
 1152 
 1153         error = syncache_pcblist(req, m, &pcb_count);
 1154         if (error)
 1155                 return (error);
 1156 
 1157         inp_list = malloc(n * sizeof *inp_list, M_TEMP, M_WAITOK);
 1158         if (inp_list == NULL)
 1159                 return (ENOMEM);
 1160 
 1161         INP_INFO_RLOCK(&V_tcbinfo);
 1162         for (inp = LIST_FIRST(V_tcbinfo.ipi_listhead), i = 0;
 1163             inp != NULL && i < n; inp = LIST_NEXT(inp, inp_list)) {
 1164                 INP_WLOCK(inp);
 1165                 if (inp->inp_gencnt <= gencnt) {
 1166                         /*
 1167                          * XXX: This use of cr_cansee(), introduced with
 1168                          * TCP state changes, is not quite right, but for
 1169                          * now, better than nothing.
 1170                          */
 1171                         if (inp->inp_flags & INP_TIMEWAIT) {
 1172                                 if (intotw(inp) != NULL)
 1173                                         error = cr_cansee(req->td->td_ucred,
 1174                                             intotw(inp)->tw_cred);
 1175                                 else
 1176                                         error = EINVAL; /* Skip this inp. */
 1177                         } else
 1178                                 error = cr_canseeinpcb(req->td->td_ucred, inp);
 1179                         if (error == 0) {
 1180                                 in_pcbref(inp);
 1181                                 inp_list[i++] = inp;
 1182                         }
 1183                 }
 1184                 INP_WUNLOCK(inp);
 1185         }
 1186         INP_INFO_RUNLOCK(&V_tcbinfo);
 1187         n = i;
 1188 
 1189         error = 0;
 1190         for (i = 0; i < n; i++) {
 1191                 inp = inp_list[i];
 1192                 INP_RLOCK(inp);
 1193                 if (inp->inp_gencnt <= gencnt) {
 1194                         struct xtcpcb xt;
 1195                         void *inp_ppcb;
 1196 
 1197                         bzero(&xt, sizeof(xt));
 1198                         xt.xt_len = sizeof xt;
 1199                         /* XXX should avoid extra copy */
 1200                         bcopy(inp, &xt.xt_inp, sizeof *inp);
 1201                         inp_ppcb = inp->inp_ppcb;
 1202                         if (inp_ppcb == NULL)
 1203                                 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp);
 1204                         else if (inp->inp_flags & INP_TIMEWAIT) {
 1205                                 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp);
 1206                                 xt.xt_tp.t_state = TCPS_TIME_WAIT;
 1207                         } else
 1208                                 bcopy(inp_ppcb, &xt.xt_tp, sizeof xt.xt_tp);
 1209                         if (inp->inp_socket != NULL)
 1210                                 sotoxsocket(inp->inp_socket, &xt.xt_socket);
 1211                         else {
 1212                                 bzero(&xt.xt_socket, sizeof xt.xt_socket);
 1213                                 xt.xt_socket.xso_protocol = IPPROTO_TCP;
 1214                         }
 1215                         xt.xt_inp.inp_gencnt = inp->inp_gencnt;
 1216                         INP_RUNLOCK(inp);
 1217                         error = SYSCTL_OUT(req, &xt, sizeof xt);
 1218                 } else
 1219                         INP_RUNLOCK(inp);
 1220         }
 1221         INP_INFO_WLOCK(&V_tcbinfo);
 1222         for (i = 0; i < n; i++) {
 1223                 inp = inp_list[i];
 1224                 INP_WLOCK(inp);
 1225                 if (!in_pcbrele(inp))
 1226                         INP_WUNLOCK(inp);
 1227         }
 1228         INP_INFO_WUNLOCK(&V_tcbinfo);
 1229 
 1230         if (!error) {
 1231                 /*
 1232                  * Give the user an updated idea of our state.
 1233                  * If the generation differs from what we told
 1234                  * her before, she knows that something happened
 1235                  * while we were processing this request, and it
 1236                  * might be necessary to retry.
 1237                  */
 1238                 INP_INFO_RLOCK(&V_tcbinfo);
 1239                 xig.xig_gen = V_tcbinfo.ipi_gencnt;
 1240                 xig.xig_sogen = so_gencnt;
 1241                 xig.xig_count = V_tcbinfo.ipi_count + pcb_count;
 1242                 INP_INFO_RUNLOCK(&V_tcbinfo);
 1243                 error = SYSCTL_OUT(req, &xig, sizeof xig);
 1244         }
 1245         free(inp_list, M_TEMP);
 1246         return (error);
 1247 }
 1248 
 1249 SYSCTL_PROC(_net_inet_tcp, TCPCTL_PCBLIST, pcblist,
 1250     CTLTYPE_OPAQUE | CTLFLAG_RD, NULL, 0,
 1251     tcp_pcblist, "S,xtcpcb", "List of active TCP connections");
 1252 
 1253 static int
 1254 tcp_getcred(SYSCTL_HANDLER_ARGS)
 1255 {
 1256         struct xucred xuc;
 1257         struct sockaddr_in addrs[2];
 1258         struct inpcb *inp;
 1259         int error;
 1260 
 1261         error = priv_check(req->td, PRIV_NETINET_GETCRED);
 1262         if (error)
 1263                 return (error);
 1264         error = SYSCTL_IN(req, addrs, sizeof(addrs));
 1265         if (error)
 1266                 return (error);
 1267         INP_INFO_RLOCK(&V_tcbinfo);
 1268         inp = in_pcblookup_hash(&V_tcbinfo, addrs[1].sin_addr,
 1269             addrs[1].sin_port, addrs[0].sin_addr, addrs[0].sin_port, 0, NULL);
 1270         if (inp != NULL) {
 1271                 INP_RLOCK(inp);
 1272                 INP_INFO_RUNLOCK(&V_tcbinfo);
 1273                 if (inp->inp_socket == NULL)
 1274                         error = ENOENT;
 1275                 if (error == 0)
 1276                         error = cr_canseeinpcb(req->td->td_ucred, inp);
 1277                 if (error == 0)
 1278                         cru2x(inp->inp_cred, &xuc);
 1279                 INP_RUNLOCK(inp);
 1280         } else {
 1281                 INP_INFO_RUNLOCK(&V_tcbinfo);
 1282                 error = ENOENT;
 1283         }
 1284         if (error == 0)
 1285                 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred));
 1286         return (error);
 1287 }
 1288 
 1289 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, getcred,
 1290     CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0,
 1291     tcp_getcred, "S,xucred", "Get the xucred of a TCP connection");
 1292 
 1293 #ifdef INET6
 1294 static int
 1295 tcp6_getcred(SYSCTL_HANDLER_ARGS)
 1296 {
 1297         struct xucred xuc;
 1298         struct sockaddr_in6 addrs[2];
 1299         struct inpcb *inp;
 1300         int error, mapped = 0;
 1301 
 1302         error = priv_check(req->td, PRIV_NETINET_GETCRED);
 1303         if (error)
 1304                 return (error);
 1305         error = SYSCTL_IN(req, addrs, sizeof(addrs));
 1306         if (error)
 1307                 return (error);
 1308         if ((error = sa6_embedscope(&addrs[0], V_ip6_use_defzone)) != 0 ||
 1309             (error = sa6_embedscope(&addrs[1], V_ip6_use_defzone)) != 0) {
 1310                 return (error);
 1311         }
 1312         if (IN6_IS_ADDR_V4MAPPED(&addrs[0].sin6_addr)) {
 1313                 if (IN6_IS_ADDR_V4MAPPED(&addrs[1].sin6_addr))
 1314                         mapped = 1;
 1315                 else
 1316                         return (EINVAL);
 1317         }
 1318 
 1319         INP_INFO_RLOCK(&V_tcbinfo);
 1320         if (mapped == 1)
 1321                 inp = in_pcblookup_hash(&V_tcbinfo,
 1322                         *(struct in_addr *)&addrs[1].sin6_addr.s6_addr[12],
 1323                         addrs[1].sin6_port,
 1324                         *(struct in_addr *)&addrs[0].sin6_addr.s6_addr[12],
 1325                         addrs[0].sin6_port,
 1326                         0, NULL);
 1327         else
 1328                 inp = in6_pcblookup_hash(&V_tcbinfo,
 1329                         &addrs[1].sin6_addr, addrs[1].sin6_port,
 1330                         &addrs[0].sin6_addr, addrs[0].sin6_port, 0, NULL);
 1331         if (inp != NULL) {
 1332                 INP_RLOCK(inp);
 1333                 INP_INFO_RUNLOCK(&V_tcbinfo);
 1334                 if (inp->inp_socket == NULL)
 1335                         error = ENOENT;
 1336                 if (error == 0)
 1337                         error = cr_canseeinpcb(req->td->td_ucred, inp);
 1338                 if (error == 0)
 1339                         cru2x(inp->inp_cred, &xuc);
 1340                 INP_RUNLOCK(inp);
 1341         } else {
 1342                 INP_INFO_RUNLOCK(&V_tcbinfo);
 1343                 error = ENOENT;
 1344         }
 1345         if (error == 0)
 1346                 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred));
 1347         return (error);
 1348 }
 1349 
 1350 SYSCTL_PROC(_net_inet6_tcp6, OID_AUTO, getcred,
 1351     CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0,
 1352     tcp6_getcred, "S,xucred", "Get the xucred of a TCP6 connection");
 1353 #endif
 1354 
 1355 
 1356 void
 1357 tcp_ctlinput(int cmd, struct sockaddr *sa, void *vip)
 1358 {
 1359         struct ip *ip = vip;
 1360         struct tcphdr *th;
 1361         struct in_addr faddr;
 1362         struct inpcb *inp;
 1363         struct tcpcb *tp;
 1364         struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify;
 1365         struct icmp *icp;
 1366         struct in_conninfo inc;
 1367         tcp_seq icmp_tcp_seq;
 1368         int mtu;
 1369 
 1370         faddr = ((struct sockaddr_in *)sa)->sin_addr;
 1371         if (sa->sa_family != AF_INET || faddr.s_addr == INADDR_ANY)
 1372                 return;
 1373 
 1374         if (cmd == PRC_MSGSIZE)
 1375                 notify = tcp_mtudisc;
 1376         else if (V_icmp_may_rst && (cmd == PRC_UNREACH_ADMIN_PROHIB ||
 1377                 cmd == PRC_UNREACH_PORT || cmd == PRC_TIMXCEED_INTRANS) && ip)
 1378                 notify = tcp_drop_syn_sent;
 1379         /*
 1380          * Redirects don't need to be handled up here.
 1381          */
 1382         else if (PRC_IS_REDIRECT(cmd))
 1383                 return;
 1384         /*
 1385          * Source quench is depreciated.
 1386          */
 1387         else if (cmd == PRC_QUENCH)
 1388                 return;
 1389         /*
 1390          * Hostdead is ugly because it goes linearly through all PCBs.
 1391          * XXX: We never get this from ICMP, otherwise it makes an
 1392          * excellent DoS attack on machines with many connections.
 1393          */
 1394         else if (cmd == PRC_HOSTDEAD)
 1395                 ip = NULL;
 1396         else if ((unsigned)cmd >= PRC_NCMDS || inetctlerrmap[cmd] == 0)
 1397                 return;
 1398         if (ip != NULL) {
 1399                 icp = (struct icmp *)((caddr_t)ip
 1400                                       - offsetof(struct icmp, icmp_ip));
 1401                 th = (struct tcphdr *)((caddr_t)ip
 1402                                        + (ip->ip_hl << 2));
 1403                 INP_INFO_WLOCK(&V_tcbinfo);
 1404                 inp = in_pcblookup_hash(&V_tcbinfo, faddr, th->th_dport,
 1405                     ip->ip_src, th->th_sport, 0, NULL);
 1406                 if (inp != NULL)  {
 1407                         INP_WLOCK(inp);
 1408                         if (!(inp->inp_flags & INP_TIMEWAIT) &&
 1409                             !(inp->inp_flags & INP_DROPPED) &&
 1410                             !(inp->inp_socket == NULL)) {
 1411                                 icmp_tcp_seq = htonl(th->th_seq);
 1412                                 tp = intotcpcb(inp);
 1413                                 if (SEQ_GEQ(icmp_tcp_seq, tp->snd_una) &&
 1414                                     SEQ_LT(icmp_tcp_seq, tp->snd_max)) {
 1415                                         if (cmd == PRC_MSGSIZE) {
 1416                                             /*
 1417                                              * MTU discovery:
 1418                                              * If we got a needfrag set the MTU
 1419                                              * in the route to the suggested new
 1420                                              * value (if given) and then notify.
 1421                                              */
 1422                                             bzero(&inc, sizeof(inc));
 1423                                             inc.inc_faddr = faddr;
 1424                                             inc.inc_fibnum =
 1425                                                 inp->inp_inc.inc_fibnum;
 1426 
 1427                                             mtu = ntohs(icp->icmp_nextmtu);
 1428                                             /*
 1429                                              * If no alternative MTU was
 1430                                              * proposed, try the next smaller
 1431                                              * one.  ip->ip_len has already
 1432                                              * been swapped in icmp_input().
 1433                                              */
 1434                                             if (!mtu)
 1435                                                 mtu = ip_next_mtu(ip->ip_len,
 1436                                                  1);
 1437                                             if (mtu < V_tcp_minmss
 1438                                                  + sizeof(struct tcpiphdr))
 1439                                                 mtu = V_tcp_minmss
 1440                                                  + sizeof(struct tcpiphdr);
 1441                                             /*
 1442                                              * Only cache the MTU if it
 1443                                              * is smaller than the interface
 1444                                              * or route MTU.  tcp_mtudisc()
 1445                                              * will do right thing by itself.
 1446                                              */
 1447                                             if (mtu <= tcp_maxmtu(&inc, NULL))
 1448                                                 tcp_hc_updatemtu(&inc, mtu);
 1449                                         }
 1450 
 1451                                         inp = (*notify)(inp, inetctlerrmap[cmd]);
 1452                                 }
 1453                         }
 1454                         if (inp != NULL)
 1455                                 INP_WUNLOCK(inp);
 1456                 } else {
 1457                         bzero(&inc, sizeof(inc));
 1458                         inc.inc_fport = th->th_dport;
 1459                         inc.inc_lport = th->th_sport;
 1460                         inc.inc_faddr = faddr;
 1461                         inc.inc_laddr = ip->ip_src;
 1462                         syncache_unreach(&inc, th);
 1463                 }
 1464                 INP_INFO_WUNLOCK(&V_tcbinfo);
 1465         } else
 1466                 in_pcbnotifyall(&V_tcbinfo, faddr, inetctlerrmap[cmd], notify);
 1467 }
 1468 
 1469 #ifdef INET6
 1470 void
 1471 tcp6_ctlinput(int cmd, struct sockaddr *sa, void *d)
 1472 {
 1473         struct tcphdr th;
 1474         struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify;
 1475         struct ip6_hdr *ip6;
 1476         struct mbuf *m;
 1477         struct ip6ctlparam *ip6cp = NULL;
 1478         const struct sockaddr_in6 *sa6_src = NULL;
 1479         int off;
 1480         struct tcp_portonly {
 1481                 u_int16_t th_sport;
 1482                 u_int16_t th_dport;
 1483         } *thp;
 1484 
 1485         if (sa->sa_family != AF_INET6 ||
 1486             sa->sa_len != sizeof(struct sockaddr_in6))
 1487                 return;
 1488 
 1489         if (cmd == PRC_MSGSIZE)
 1490                 notify = tcp_mtudisc;
 1491         else if (!PRC_IS_REDIRECT(cmd) &&
 1492                  ((unsigned)cmd >= PRC_NCMDS || inet6ctlerrmap[cmd] == 0))
 1493                 return;
 1494         /* Source quench is depreciated. */
 1495         else if (cmd == PRC_QUENCH)
 1496                 return;
 1497 
 1498         /* if the parameter is from icmp6, decode it. */
 1499         if (d != NULL) {
 1500                 ip6cp = (struct ip6ctlparam *)d;
 1501                 m = ip6cp->ip6c_m;
 1502                 ip6 = ip6cp->ip6c_ip6;
 1503                 off = ip6cp->ip6c_off;
 1504                 sa6_src = ip6cp->ip6c_src;
 1505         } else {
 1506                 m = NULL;
 1507                 ip6 = NULL;
 1508                 off = 0;        /* fool gcc */
 1509                 sa6_src = &sa6_any;
 1510         }
 1511 
 1512         if (ip6 != NULL) {
 1513                 struct in_conninfo inc;
 1514                 /*
 1515                  * XXX: We assume that when IPV6 is non NULL,
 1516                  * M and OFF are valid.
 1517                  */
 1518 
 1519                 /* check if we can safely examine src and dst ports */
 1520                 if (m->m_pkthdr.len < off + sizeof(*thp))
 1521                         return;
 1522 
 1523                 bzero(&th, sizeof(th));
 1524                 m_copydata(m, off, sizeof(*thp), (caddr_t)&th);
 1525 
 1526                 in6_pcbnotify(&V_tcbinfo, sa, th.th_dport,
 1527                     (struct sockaddr *)ip6cp->ip6c_src,
 1528                     th.th_sport, cmd, NULL, notify);
 1529 
 1530                 bzero(&inc, sizeof(inc));
 1531                 inc.inc_fport = th.th_dport;
 1532                 inc.inc_lport = th.th_sport;
 1533                 inc.inc6_faddr = ((struct sockaddr_in6 *)sa)->sin6_addr;
 1534                 inc.inc6_laddr = ip6cp->ip6c_src->sin6_addr;
 1535                 inc.inc_flags |= INC_ISIPV6;
 1536                 INP_INFO_WLOCK(&V_tcbinfo);
 1537                 syncache_unreach(&inc, &th);
 1538                 INP_INFO_WUNLOCK(&V_tcbinfo);
 1539         } else
 1540                 in6_pcbnotify(&V_tcbinfo, sa, 0, (const struct sockaddr *)sa6_src,
 1541                               0, cmd, NULL, notify);
 1542 }
 1543 #endif /* INET6 */
 1544 
 1545 
 1546 /*
 1547  * Following is where TCP initial sequence number generation occurs.
 1548  *
 1549  * There are two places where we must use initial sequence numbers:
 1550  * 1.  In SYN-ACK packets.
 1551  * 2.  In SYN packets.
 1552  *
 1553  * All ISNs for SYN-ACK packets are generated by the syncache.  See
 1554  * tcp_syncache.c for details.
 1555  *
 1556  * The ISNs in SYN packets must be monotonic; TIME_WAIT recycling
 1557  * depends on this property.  In addition, these ISNs should be
 1558  * unguessable so as to prevent connection hijacking.  To satisfy
 1559  * the requirements of this situation, the algorithm outlined in
 1560  * RFC 1948 is used, with only small modifications.
 1561  *
 1562  * Implementation details:
 1563  *
 1564  * Time is based off the system timer, and is corrected so that it
 1565  * increases by one megabyte per second.  This allows for proper
 1566  * recycling on high speed LANs while still leaving over an hour
 1567  * before rollover.
 1568  *
 1569  * As reading the *exact* system time is too expensive to be done
 1570  * whenever setting up a TCP connection, we increment the time
 1571  * offset in two ways.  First, a small random positive increment
 1572  * is added to isn_offset for each connection that is set up.
 1573  * Second, the function tcp_isn_tick fires once per clock tick
 1574  * and increments isn_offset as necessary so that sequence numbers
 1575  * are incremented at approximately ISN_BYTES_PER_SECOND.  The
 1576  * random positive increments serve only to ensure that the same
 1577  * exact sequence number is never sent out twice (as could otherwise
 1578  * happen when a port is recycled in less than the system tick
 1579  * interval.)
 1580  *
 1581  * net.inet.tcp.isn_reseed_interval controls the number of seconds
 1582  * between seeding of isn_secret.  This is normally set to zero,
 1583  * as reseeding should not be necessary.
 1584  *
 1585  * Locking of the global variables isn_secret, isn_last_reseed, isn_offset,
 1586  * isn_offset_old, and isn_ctx is performed using the TCP pcbinfo lock.  In
 1587  * general, this means holding an exclusive (write) lock.
 1588  */
 1589 
 1590 #define ISN_BYTES_PER_SECOND 1048576
 1591 #define ISN_STATIC_INCREMENT 4096
 1592 #define ISN_RANDOM_INCREMENT (4096 - 1)
 1593 
 1594 static VNET_DEFINE(u_char, isn_secret[32]);
 1595 static VNET_DEFINE(int, isn_last_reseed);
 1596 static VNET_DEFINE(u_int32_t, isn_offset);
 1597 static VNET_DEFINE(u_int32_t, isn_offset_old);
 1598 
 1599 #define V_isn_secret                    VNET(isn_secret)
 1600 #define V_isn_last_reseed               VNET(isn_last_reseed)
 1601 #define V_isn_offset                    VNET(isn_offset)
 1602 #define V_isn_offset_old                VNET(isn_offset_old)
 1603 
 1604 tcp_seq
 1605 tcp_new_isn(struct tcpcb *tp)
 1606 {
 1607         MD5_CTX isn_ctx;
 1608         u_int32_t md5_buffer[4];
 1609         tcp_seq new_isn;
 1610 
 1611         INP_WLOCK_ASSERT(tp->t_inpcb);
 1612 
 1613         ISN_LOCK();
 1614         /* Seed if this is the first use, reseed if requested. */
 1615         if ((V_isn_last_reseed == 0) || ((V_tcp_isn_reseed_interval > 0) &&
 1616              (((u_int)V_isn_last_reseed + (u_int)V_tcp_isn_reseed_interval*hz)
 1617                 < (u_int)ticks))) {
 1618                 read_random(&V_isn_secret, sizeof(V_isn_secret));
 1619                 V_isn_last_reseed = ticks;
 1620         }
 1621 
 1622         /* Compute the md5 hash and return the ISN. */
 1623         MD5Init(&isn_ctx);
 1624         MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_fport, sizeof(u_short));
 1625         MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_lport, sizeof(u_short));
 1626 #ifdef INET6
 1627         if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) {
 1628                 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_faddr,
 1629                           sizeof(struct in6_addr));
 1630                 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_laddr,
 1631                           sizeof(struct in6_addr));
 1632         } else
 1633 #endif
 1634         {
 1635                 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_faddr,
 1636                           sizeof(struct in_addr));
 1637                 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_laddr,
 1638                           sizeof(struct in_addr));
 1639         }
 1640         MD5Update(&isn_ctx, (u_char *) &V_isn_secret, sizeof(V_isn_secret));
 1641         MD5Final((u_char *) &md5_buffer, &isn_ctx);
 1642         new_isn = (tcp_seq) md5_buffer[0];
 1643         V_isn_offset += ISN_STATIC_INCREMENT +
 1644                 (arc4random() & ISN_RANDOM_INCREMENT);
 1645         new_isn += V_isn_offset;
 1646         ISN_UNLOCK();
 1647         return (new_isn);
 1648 }
 1649 
 1650 /*
 1651  * Increment the offset to the next ISN_BYTES_PER_SECOND / 100 boundary
 1652  * to keep time flowing at a relatively constant rate.  If the random
 1653  * increments have already pushed us past the projected offset, do nothing.
 1654  */
 1655 static void
 1656 tcp_isn_tick(void *xtp)
 1657 {
 1658         VNET_ITERATOR_DECL(vnet_iter);
 1659         u_int32_t projected_offset;
 1660 
 1661         VNET_LIST_RLOCK_NOSLEEP();
 1662         ISN_LOCK();
 1663         VNET_FOREACH(vnet_iter) {
 1664                 CURVNET_SET(vnet_iter); /* XXX appease INVARIANTS */
 1665                 projected_offset =
 1666                     V_isn_offset_old + ISN_BYTES_PER_SECOND / 100;
 1667 
 1668                 if (SEQ_GT(projected_offset, V_isn_offset))
 1669                         V_isn_offset = projected_offset;
 1670 
 1671                 V_isn_offset_old = V_isn_offset;
 1672                 CURVNET_RESTORE();
 1673         }
 1674         ISN_UNLOCK();
 1675         VNET_LIST_RUNLOCK_NOSLEEP();
 1676         callout_reset(&isn_callout, hz/100, tcp_isn_tick, NULL);
 1677 }
 1678 
 1679 /*
 1680  * When a specific ICMP unreachable message is received and the
 1681  * connection state is SYN-SENT, drop the connection.  This behavior
 1682  * is controlled by the icmp_may_rst sysctl.
 1683  */
 1684 struct inpcb *
 1685 tcp_drop_syn_sent(struct inpcb *inp, int errno)
 1686 {
 1687         struct tcpcb *tp;
 1688 
 1689         INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
 1690         INP_WLOCK_ASSERT(inp);
 1691 
 1692         if ((inp->inp_flags & INP_TIMEWAIT) ||
 1693             (inp->inp_flags & INP_DROPPED))
 1694                 return (inp);
 1695 
 1696         tp = intotcpcb(inp);
 1697         if (tp->t_state != TCPS_SYN_SENT)
 1698                 return (inp);
 1699 
 1700         tp = tcp_drop(tp, errno);
 1701         if (tp != NULL)
 1702                 return (inp);
 1703         else
 1704                 return (NULL);
 1705 }
 1706 
 1707 /*
 1708  * When `need fragmentation' ICMP is received, update our idea of the MSS
 1709  * based on the new value in the route.  Also nudge TCP to send something,
 1710  * since we know the packet we just sent was dropped.
 1711  * This duplicates some code in the tcp_mss() function in tcp_input.c.
 1712  */
 1713 struct inpcb *
 1714 tcp_mtudisc(struct inpcb *inp, int errno)
 1715 {
 1716         struct tcpcb *tp;
 1717         struct socket *so;
 1718 
 1719         INP_WLOCK_ASSERT(inp);
 1720         if ((inp->inp_flags & INP_TIMEWAIT) ||
 1721             (inp->inp_flags & INP_DROPPED))
 1722                 return (inp);
 1723 
 1724         tp = intotcpcb(inp);
 1725         KASSERT(tp != NULL, ("tcp_mtudisc: tp == NULL"));
 1726 
 1727         tcp_mss_update(tp, -1, NULL, NULL);
 1728   
 1729         so = inp->inp_socket;
 1730         SOCKBUF_LOCK(&so->so_snd);
 1731         /* If the mss is larger than the socket buffer, decrease the mss. */
 1732         if (so->so_snd.sb_hiwat < tp->t_maxseg)
 1733                 tp->t_maxseg = so->so_snd.sb_hiwat;
 1734         SOCKBUF_UNLOCK(&so->so_snd);
 1735 
 1736         TCPSTAT_INC(tcps_mturesent);
 1737         tp->t_rtttime = 0;
 1738         tp->snd_nxt = tp->snd_una;
 1739         tcp_free_sackholes(tp);
 1740         tp->snd_recover = tp->snd_max;
 1741         if (tp->t_flags & TF_SACK_PERMIT)
 1742                 EXIT_FASTRECOVERY(tp->t_flags);
 1743         tcp_output_send(tp);
 1744         return (inp);
 1745 }
 1746 
 1747 /*
 1748  * Look-up the routing entry to the peer of this inpcb.  If no route
 1749  * is found and it cannot be allocated, then return 0.  This routine
 1750  * is called by TCP routines that access the rmx structure and by
 1751  * tcp_mss_update to get the peer/interface MTU.
 1752  */
 1753 u_long
 1754 tcp_maxmtu(struct in_conninfo *inc, int *flags)
 1755 {
 1756         struct route sro;
 1757         struct sockaddr_in *dst;
 1758         struct ifnet *ifp;
 1759         u_long maxmtu = 0;
 1760 
 1761         KASSERT(inc != NULL, ("tcp_maxmtu with NULL in_conninfo pointer"));
 1762 
 1763         bzero(&sro, sizeof(sro));
 1764         if (inc->inc_faddr.s_addr != INADDR_ANY) {
 1765                 dst = (struct sockaddr_in *)&sro.ro_dst;
 1766                 dst->sin_family = AF_INET;
 1767                 dst->sin_len = sizeof(*dst);
 1768                 dst->sin_addr = inc->inc_faddr;
 1769                 in_rtalloc_ign(&sro, 0, inc->inc_fibnum);
 1770         }
 1771         if (sro.ro_rt != NULL) {
 1772                 ifp = sro.ro_rt->rt_ifp;
 1773                 if (sro.ro_rt->rt_rmx.rmx_mtu == 0)
 1774                         maxmtu = ifp->if_mtu;
 1775                 else
 1776                         maxmtu = min(sro.ro_rt->rt_rmx.rmx_mtu, ifp->if_mtu);
 1777 
 1778                 /* Report additional interface capabilities. */
 1779                 if (flags != NULL) {
 1780                         if (ifp->if_capenable & IFCAP_TSO4 &&
 1781                             ifp->if_hwassist & CSUM_TSO)
 1782                                 *flags |= CSUM_TSO;
 1783                 }
 1784                 RTFREE(sro.ro_rt);
 1785         }
 1786         return (maxmtu);
 1787 }
 1788 
 1789 #ifdef INET6
 1790 u_long
 1791 tcp_maxmtu6(struct in_conninfo *inc, int *flags)
 1792 {
 1793         struct route_in6 sro6;
 1794         struct ifnet *ifp;
 1795         u_long maxmtu = 0;
 1796 
 1797         KASSERT(inc != NULL, ("tcp_maxmtu6 with NULL in_conninfo pointer"));
 1798 
 1799         bzero(&sro6, sizeof(sro6));
 1800         if (!IN6_IS_ADDR_UNSPECIFIED(&inc->inc6_faddr)) {
 1801                 sro6.ro_dst.sin6_family = AF_INET6;
 1802                 sro6.ro_dst.sin6_len = sizeof(struct sockaddr_in6);
 1803                 sro6.ro_dst.sin6_addr = inc->inc6_faddr;
 1804                 rtalloc_ign((struct route *)&sro6, 0);
 1805         }
 1806         if (sro6.ro_rt != NULL) {
 1807                 ifp = sro6.ro_rt->rt_ifp;
 1808                 if (sro6.ro_rt->rt_rmx.rmx_mtu == 0)
 1809                         maxmtu = IN6_LINKMTU(sro6.ro_rt->rt_ifp);
 1810                 else
 1811                         maxmtu = min(sro6.ro_rt->rt_rmx.rmx_mtu,
 1812                                      IN6_LINKMTU(sro6.ro_rt->rt_ifp));
 1813 
 1814                 /* Report additional interface capabilities. */
 1815                 if (flags != NULL) {
 1816                         if (ifp->if_capenable & IFCAP_TSO6 &&
 1817                             ifp->if_hwassist & CSUM_TSO)
 1818                                 *flags |= CSUM_TSO;
 1819                 }
 1820                 RTFREE(sro6.ro_rt);
 1821         }
 1822 
 1823         return (maxmtu);
 1824 }
 1825 #endif /* INET6 */
 1826 
 1827 #ifdef IPSEC
 1828 /* compute ESP/AH header size for TCP, including outer IP header. */
 1829 size_t
 1830 ipsec_hdrsiz_tcp(struct tcpcb *tp)
 1831 {
 1832         struct inpcb *inp;
 1833         struct mbuf *m;
 1834         size_t hdrsiz;
 1835         struct ip *ip;
 1836 #ifdef INET6
 1837         struct ip6_hdr *ip6;
 1838 #endif
 1839         struct tcphdr *th;
 1840 
 1841         if ((tp == NULL) || ((inp = tp->t_inpcb) == NULL))
 1842                 return (0);
 1843         MGETHDR(m, M_DONTWAIT, MT_DATA);
 1844         if (!m)
 1845                 return (0);
 1846 
 1847 #ifdef INET6
 1848         if ((inp->inp_vflag & INP_IPV6) != 0) {
 1849                 ip6 = mtod(m, struct ip6_hdr *);
 1850                 th = (struct tcphdr *)(ip6 + 1);
 1851                 m->m_pkthdr.len = m->m_len =
 1852                         sizeof(struct ip6_hdr) + sizeof(struct tcphdr);
 1853                 tcpip_fillheaders(inp, ip6, th);
 1854                 hdrsiz = ipsec_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp);
 1855         } else
 1856 #endif /* INET6 */
 1857         {
 1858                 ip = mtod(m, struct ip *);
 1859                 th = (struct tcphdr *)(ip + 1);
 1860                 m->m_pkthdr.len = m->m_len = sizeof(struct tcpiphdr);
 1861                 tcpip_fillheaders(inp, ip, th);
 1862                 hdrsiz = ipsec_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp);
 1863         }
 1864 
 1865         m_free(m);
 1866         return (hdrsiz);
 1867 }
 1868 #endif /* IPSEC */
 1869 
 1870 /*
 1871  * TCP BANDWIDTH DELAY PRODUCT WINDOW LIMITING
 1872  *
 1873  * This code attempts to calculate the bandwidth-delay product as a
 1874  * means of determining the optimal window size to maximize bandwidth,
 1875  * minimize RTT, and avoid the over-allocation of buffers on interfaces and
 1876  * routers.  This code also does a fairly good job keeping RTTs in check
 1877  * across slow links like modems.  We implement an algorithm which is very
 1878  * similar (but not meant to be) TCP/Vegas.  The code operates on the
 1879  * transmitter side of a TCP connection and so only effects the transmit
 1880  * side of the connection.
 1881  *
 1882  * BACKGROUND:  TCP makes no provision for the management of buffer space
 1883  * at the end points or at the intermediate routers and switches.  A TCP
 1884  * stream, whether using NewReno or not, will eventually buffer as
 1885  * many packets as it is able and the only reason this typically works is
 1886  * due to the fairly small default buffers made available for a connection
 1887  * (typicaly 16K or 32K).  As machines use larger windows and/or window
 1888  * scaling it is now fairly easy for even a single TCP connection to blow-out
 1889  * all available buffer space not only on the local interface, but on
 1890  * intermediate routers and switches as well.  NewReno makes a misguided
 1891  * attempt to 'solve' this problem by waiting for an actual failure to occur,
 1892  * then backing off, then steadily increasing the window again until another
 1893  * failure occurs, ad-infinitum.  This results in terrible oscillation that
 1894  * is only made worse as network loads increase and the idea of intentionally
 1895  * blowing out network buffers is, frankly, a terrible way to manage network
 1896  * resources.
 1897  *
 1898  * It is far better to limit the transmit window prior to the failure
 1899  * condition being achieved.  There are two general ways to do this:  First
 1900  * you can 'scan' through different transmit window sizes and locate the
 1901  * point where the RTT stops increasing, indicating that you have filled the
 1902  * pipe, then scan backwards until you note that RTT stops decreasing, then
 1903  * repeat ad-infinitum.  This method works in principle but has severe
 1904  * implementation issues due to RTT variances, timer granularity, and
 1905  * instability in the algorithm which can lead to many false positives and
 1906  * create oscillations as well as interact badly with other TCP streams
 1907  * implementing the same algorithm.
 1908  *
 1909  * The second method is to limit the window to the bandwidth delay product
 1910  * of the link.  This is the method we implement.  RTT variances and our
 1911  * own manipulation of the congestion window, bwnd, can potentially
 1912  * destabilize the algorithm.  For this reason we have to stabilize the
 1913  * elements used to calculate the window.  We do this by using the minimum
 1914  * observed RTT, the long term average of the observed bandwidth, and
 1915  * by adding two segments worth of slop.  It isn't perfect but it is able
 1916  * to react to changing conditions and gives us a very stable basis on
 1917  * which to extend the algorithm.
 1918  */
 1919 void
 1920 tcp_xmit_bandwidth_limit(struct tcpcb *tp, tcp_seq ack_seq)
 1921 {
 1922         u_long bw;
 1923         u_long bwnd;
 1924         int save_ticks;
 1925 
 1926         INP_WLOCK_ASSERT(tp->t_inpcb);
 1927 
 1928         /*
 1929          * If inflight_enable is disabled in the middle of a tcp connection,
 1930          * make sure snd_bwnd is effectively disabled.
 1931          */
 1932         if (V_tcp_inflight_enable == 0 ||
 1933             tp->t_rttlow < V_tcp_inflight_rttthresh) {
 1934                 tp->snd_bwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
 1935                 tp->snd_bandwidth = 0;
 1936                 return;
 1937         }
 1938 
 1939         /*
 1940          * Figure out the bandwidth.  Due to the tick granularity this
 1941          * is a very rough number and it MUST be averaged over a fairly
 1942          * long period of time.  XXX we need to take into account a link
 1943          * that is not using all available bandwidth, but for now our
 1944          * slop will ramp us up if this case occurs and the bandwidth later
 1945          * increases.
 1946          *
 1947          * Note: if ticks rollover 'bw' may wind up negative.  We must
 1948          * effectively reset t_bw_rtttime for this case.
 1949          */
 1950         save_ticks = ticks;
 1951         if ((u_int)(save_ticks - tp->t_bw_rtttime) < 1)
 1952                 return;
 1953 
 1954         bw = (int64_t)(ack_seq - tp->t_bw_rtseq) * hz /
 1955             (save_ticks - tp->t_bw_rtttime);
 1956         tp->t_bw_rtttime = save_ticks;
 1957         tp->t_bw_rtseq = ack_seq;
 1958         if (tp->t_bw_rtttime == 0 || (int)bw < 0)
 1959                 return;
 1960         bw = ((int64_t)tp->snd_bandwidth * 15 + bw) >> 4;
 1961 
 1962         tp->snd_bandwidth = bw;
 1963 
 1964         /*
 1965          * Calculate the semi-static bandwidth delay product, plus two maximal
 1966          * segments.  The additional slop puts us squarely in the sweet
 1967          * spot and also handles the bandwidth run-up case and stabilization.
 1968          * Without the slop we could be locking ourselves into a lower
 1969          * bandwidth.
 1970          *
 1971          * Situations Handled:
 1972          *      (1) Prevents over-queueing of packets on LANs, especially on
 1973          *          high speed LANs, allowing larger TCP buffers to be
 1974          *          specified, and also does a good job preventing
 1975          *          over-queueing of packets over choke points like modems
 1976          *          (at least for the transmit side).
 1977          *
 1978          *      (2) Is able to handle changing network loads (bandwidth
 1979          *          drops so bwnd drops, bandwidth increases so bwnd
 1980          *          increases).
 1981          *
 1982          *      (3) Theoretically should stabilize in the face of multiple
 1983          *          connections implementing the same algorithm (this may need
 1984          *          a little work).
 1985          *
 1986          *      (4) Stability value (defaults to 20 = 2 maximal packets) can
 1987          *          be adjusted with a sysctl but typically only needs to be
 1988          *          on very slow connections.  A value no smaller then 5
 1989          *          should be used, but only reduce this default if you have
 1990          *          no other choice.
 1991          */
 1992 #define USERTT  ((tp->t_srtt + tp->t_rttbest) / 2)
 1993         bwnd = (int64_t)bw * USERTT / (hz << TCP_RTT_SHIFT) + V_tcp_inflight_stab * tp->t_maxseg / 10;
 1994 #undef USERTT
 1995 
 1996         if (tcp_inflight_debug > 0) {
 1997                 static int ltime;
 1998                 if ((u_int)(ticks - ltime) >= hz / tcp_inflight_debug) {
 1999                         ltime = ticks;
 2000                         printf("%p bw %ld rttbest %d srtt %d bwnd %ld\n",
 2001                             tp,
 2002                             bw,
 2003                             tp->t_rttbest,
 2004                             tp->t_srtt,
 2005                             bwnd
 2006                         );
 2007                 }
 2008         }
 2009         if ((long)bwnd < V_tcp_inflight_min)
 2010                 bwnd = V_tcp_inflight_min;
 2011         if (bwnd > V_tcp_inflight_max)
 2012                 bwnd = V_tcp_inflight_max;
 2013         if ((long)bwnd < tp->t_maxseg * 2)
 2014                 bwnd = tp->t_maxseg * 2;
 2015         tp->snd_bwnd = bwnd;
 2016 }
 2017 
 2018 #ifdef TCP_SIGNATURE
 2019 /*
 2020  * Callback function invoked by m_apply() to digest TCP segment data
 2021  * contained within an mbuf chain.
 2022  */
 2023 static int
 2024 tcp_signature_apply(void *fstate, void *data, u_int len)
 2025 {
 2026 
 2027         MD5Update(fstate, (u_char *)data, len);
 2028         return (0);
 2029 }
 2030 
 2031 /*
 2032  * Compute TCP-MD5 hash of a TCP segment. (RFC2385)
 2033  *
 2034  * Parameters:
 2035  * m            pointer to head of mbuf chain
 2036  * _unused      
 2037  * len          length of TCP segment data, excluding options
 2038  * optlen       length of TCP segment options
 2039  * buf          pointer to storage for computed MD5 digest
 2040  * direction    direction of flow (IPSEC_DIR_INBOUND or OUTBOUND)
 2041  *
 2042  * We do this over ip, tcphdr, segment data, and the key in the SADB.
 2043  * When called from tcp_input(), we can be sure that th_sum has been
 2044  * zeroed out and verified already.
 2045  *
 2046  * Return 0 if successful, otherwise return -1.
 2047  *
 2048  * XXX The key is retrieved from the system's PF_KEY SADB, by keying a
 2049  * search with the destination IP address, and a 'magic SPI' to be
 2050  * determined by the application. This is hardcoded elsewhere to 1179
 2051  * right now. Another branch of this code exists which uses the SPD to
 2052  * specify per-application flows but it is unstable.
 2053  */
 2054 int
 2055 tcp_signature_compute(struct mbuf *m, int _unused, int len, int optlen,
 2056     u_char *buf, u_int direction)
 2057 {
 2058         union sockaddr_union dst;
 2059         struct ippseudo ippseudo;
 2060         MD5_CTX ctx;
 2061         int doff;
 2062         struct ip *ip;
 2063         struct ipovly *ipovly;
 2064         struct secasvar *sav;
 2065         struct tcphdr *th;
 2066 #ifdef INET6
 2067         struct ip6_hdr *ip6;
 2068         struct in6_addr in6;
 2069         char ip6buf[INET6_ADDRSTRLEN];
 2070         uint32_t plen;
 2071         uint16_t nhdr;
 2072 #endif
 2073         u_short savecsum;
 2074 
 2075         KASSERT(m != NULL, ("NULL mbuf chain"));
 2076         KASSERT(buf != NULL, ("NULL signature pointer"));
 2077 
 2078         /* Extract the destination from the IP header in the mbuf. */
 2079         bzero(&dst, sizeof(union sockaddr_union));
 2080         ip = mtod(m, struct ip *);
 2081 #ifdef INET6
 2082         ip6 = NULL;     /* Make the compiler happy. */
 2083 #endif
 2084         switch (ip->ip_v) {
 2085         case IPVERSION:
 2086                 dst.sa.sa_len = sizeof(struct sockaddr_in);
 2087                 dst.sa.sa_family = AF_INET;
 2088                 dst.sin.sin_addr = (direction == IPSEC_DIR_INBOUND) ?
 2089                     ip->ip_src : ip->ip_dst;
 2090                 break;
 2091 #ifdef INET6
 2092         case (IPV6_VERSION >> 4):
 2093                 ip6 = mtod(m, struct ip6_hdr *);
 2094                 dst.sa.sa_len = sizeof(struct sockaddr_in6);
 2095                 dst.sa.sa_family = AF_INET6;
 2096                 dst.sin6.sin6_addr = (direction == IPSEC_DIR_INBOUND) ?
 2097                     ip6->ip6_src : ip6->ip6_dst;
 2098                 break;
 2099 #endif
 2100         default:
 2101                 return (EINVAL);
 2102                 /* NOTREACHED */
 2103                 break;
 2104         }
 2105 
 2106         /* Look up an SADB entry which matches the address of the peer. */
 2107         sav = KEY_ALLOCSA(&dst, IPPROTO_TCP, htonl(TCP_SIG_SPI));
 2108         if (sav == NULL) {
 2109                 ipseclog((LOG_ERR, "%s: SADB lookup failed for %s\n", __func__,
 2110                     (ip->ip_v == IPVERSION) ? inet_ntoa(dst.sin.sin_addr) :
 2111 #ifdef INET6
 2112                         (ip->ip_v == (IPV6_VERSION >> 4)) ?
 2113                             ip6_sprintf(ip6buf, &dst.sin6.sin6_addr) :
 2114 #endif
 2115                         "(unsupported)"));
 2116                 return (EINVAL);
 2117         }
 2118 
 2119         MD5Init(&ctx);
 2120         /*
 2121          * Step 1: Update MD5 hash with IP(v6) pseudo-header.
 2122          *
 2123          * XXX The ippseudo header MUST be digested in network byte order,
 2124          * or else we'll fail the regression test. Assume all fields we've
 2125          * been doing arithmetic on have been in host byte order.
 2126          * XXX One cannot depend on ipovly->ih_len here. When called from
 2127          * tcp_output(), the underlying ip_len member has not yet been set.
 2128          */
 2129         switch (ip->ip_v) {
 2130         case IPVERSION:
 2131                 ipovly = (struct ipovly *)ip;
 2132                 ippseudo.ippseudo_src = ipovly->ih_src;
 2133                 ippseudo.ippseudo_dst = ipovly->ih_dst;
 2134                 ippseudo.ippseudo_pad = 0;
 2135                 ippseudo.ippseudo_p = IPPROTO_TCP;
 2136                 ippseudo.ippseudo_len = htons(len + sizeof(struct tcphdr) +
 2137                     optlen);
 2138                 MD5Update(&ctx, (char *)&ippseudo, sizeof(struct ippseudo));
 2139 
 2140                 th = (struct tcphdr *)((u_char *)ip + sizeof(struct ip));
 2141                 doff = sizeof(struct ip) + sizeof(struct tcphdr) + optlen;
 2142                 break;
 2143 #ifdef INET6
 2144         /*
 2145          * RFC 2385, 2.0  Proposal
 2146          * For IPv6, the pseudo-header is as described in RFC 2460, namely the
 2147          * 128-bit source IPv6 address, 128-bit destination IPv6 address, zero-
 2148          * extended next header value (to form 32 bits), and 32-bit segment
 2149          * length.
 2150          * Note: Upper-Layer Packet Length comes before Next Header.
 2151          */
 2152         case (IPV6_VERSION >> 4):
 2153                 in6 = ip6->ip6_src;
 2154                 in6_clearscope(&in6);
 2155                 MD5Update(&ctx, (char *)&in6, sizeof(struct in6_addr));
 2156                 in6 = ip6->ip6_dst;
 2157                 in6_clearscope(&in6);
 2158                 MD5Update(&ctx, (char *)&in6, sizeof(struct in6_addr));
 2159                 plen = htonl(len + sizeof(struct tcphdr) + optlen);
 2160                 MD5Update(&ctx, (char *)&plen, sizeof(uint32_t));
 2161                 nhdr = 0;
 2162                 MD5Update(&ctx, (char *)&nhdr, sizeof(uint8_t));
 2163                 MD5Update(&ctx, (char *)&nhdr, sizeof(uint8_t));
 2164                 MD5Update(&ctx, (char *)&nhdr, sizeof(uint8_t));
 2165                 nhdr = IPPROTO_TCP;
 2166                 MD5Update(&ctx, (char *)&nhdr, sizeof(uint8_t));
 2167 
 2168                 th = (struct tcphdr *)((u_char *)ip6 + sizeof(struct ip6_hdr));
 2169                 doff = sizeof(struct ip6_hdr) + sizeof(struct tcphdr) + optlen;
 2170                 break;
 2171 #endif
 2172         default:
 2173                 return (EINVAL);
 2174                 /* NOTREACHED */
 2175                 break;
 2176         }
 2177 
 2178 
 2179         /*
 2180          * Step 2: Update MD5 hash with TCP header, excluding options.
 2181          * The TCP checksum must be set to zero.
 2182          */
 2183         savecsum = th->th_sum;
 2184         th->th_sum = 0;
 2185         MD5Update(&ctx, (char *)th, sizeof(struct tcphdr));
 2186         th->th_sum = savecsum;
 2187 
 2188         /*
 2189          * Step 3: Update MD5 hash with TCP segment data.
 2190          *         Use m_apply() to avoid an early m_pullup().
 2191          */
 2192         if (len > 0)
 2193                 m_apply(m, doff, len, tcp_signature_apply, &ctx);
 2194 
 2195         /*
 2196          * Step 4: Update MD5 hash with shared secret.
 2197          */
 2198         MD5Update(&ctx, sav->key_auth->key_data, _KEYLEN(sav->key_auth));
 2199         MD5Final(buf, &ctx);
 2200 
 2201         key_sa_recordxfer(sav, m);
 2202         KEY_FREESAV(&sav);
 2203         return (0);
 2204 }
 2205 
 2206 /*
 2207  * Verify the TCP-MD5 hash of a TCP segment. (RFC2385)
 2208  *
 2209  * Parameters:
 2210  * m            pointer to head of mbuf chain
 2211  * len          length of TCP segment data, excluding options
 2212  * optlen       length of TCP segment options
 2213  * buf          pointer to storage for computed MD5 digest
 2214  * direction    direction of flow (IPSEC_DIR_INBOUND or OUTBOUND)
 2215  *
 2216  * Return 1 if successful, otherwise return 0.
 2217  */
 2218 int
 2219 tcp_signature_verify(struct mbuf *m, int off0, int tlen, int optlen,
 2220     struct tcpopt *to, struct tcphdr *th, u_int tcpbflag)
 2221 {
 2222         char tmpdigest[TCP_SIGLEN];
 2223 
 2224         if (tcp_sig_checksigs == 0)
 2225                 return (1);
 2226         if ((tcpbflag & TF_SIGNATURE) == 0) {
 2227                 if ((to->to_flags & TOF_SIGNATURE) != 0) {
 2228 
 2229                         /*
 2230                          * If this socket is not expecting signature but
 2231                          * the segment contains signature just fail.
 2232                          */
 2233                         TCPSTAT_INC(tcps_sig_err_sigopt);
 2234                         TCPSTAT_INC(tcps_sig_rcvbadsig);
 2235                         return (0);
 2236                 }
 2237 
 2238                 /* Signature is not expected, and not present in segment. */
 2239                 return (1);
 2240         }
 2241 
 2242         /*
 2243          * If this socket is expecting signature but the segment does not
 2244          * contain any just fail.
 2245          */
 2246         if ((to->to_flags & TOF_SIGNATURE) == 0) {
 2247                 TCPSTAT_INC(tcps_sig_err_nosigopt);
 2248                 TCPSTAT_INC(tcps_sig_rcvbadsig);
 2249                 return (0);
 2250         }
 2251         if (tcp_signature_compute(m, off0, tlen, optlen, &tmpdigest[0],
 2252             IPSEC_DIR_INBOUND) == -1) {
 2253                 TCPSTAT_INC(tcps_sig_err_buildsig);
 2254                 TCPSTAT_INC(tcps_sig_rcvbadsig);
 2255                 return (0);
 2256         }
 2257         
 2258         if (bcmp(to->to_signature, &tmpdigest[0], TCP_SIGLEN) != 0) {
 2259                 TCPSTAT_INC(tcps_sig_rcvbadsig);
 2260                 return (0);
 2261         }
 2262         TCPSTAT_INC(tcps_sig_rcvgoodsig);
 2263         return (1);
 2264 }
 2265 #endif /* TCP_SIGNATURE */
 2266 
 2267 static int
 2268 sysctl_drop(SYSCTL_HANDLER_ARGS)
 2269 {
 2270         /* addrs[0] is a foreign socket, addrs[1] is a local one. */
 2271         struct sockaddr_storage addrs[2];
 2272         struct inpcb *inp;
 2273         struct tcpcb *tp;
 2274         struct tcptw *tw;
 2275         struct sockaddr_in *fin, *lin;
 2276 #ifdef INET6
 2277         struct sockaddr_in6 *fin6, *lin6;
 2278 #endif
 2279         int error;
 2280 
 2281         inp = NULL;
 2282         fin = lin = NULL;
 2283 #ifdef INET6
 2284         fin6 = lin6 = NULL;
 2285 #endif
 2286         error = 0;
 2287 
 2288         if (req->oldptr != NULL || req->oldlen != 0)
 2289                 return (EINVAL);
 2290         if (req->newptr == NULL)
 2291                 return (EPERM);
 2292         if (req->newlen < sizeof(addrs))
 2293                 return (ENOMEM);
 2294         error = SYSCTL_IN(req, &addrs, sizeof(addrs));
 2295         if (error)
 2296                 return (error);
 2297 
 2298         switch (addrs[0].ss_family) {
 2299 #ifdef INET6
 2300         case AF_INET6:
 2301                 fin6 = (struct sockaddr_in6 *)&addrs[0];
 2302                 lin6 = (struct sockaddr_in6 *)&addrs[1];
 2303                 if (fin6->sin6_len != sizeof(struct sockaddr_in6) ||
 2304                     lin6->sin6_len != sizeof(struct sockaddr_in6))
 2305                         return (EINVAL);
 2306                 if (IN6_IS_ADDR_V4MAPPED(&fin6->sin6_addr)) {
 2307                         if (!IN6_IS_ADDR_V4MAPPED(&lin6->sin6_addr))
 2308                                 return (EINVAL);
 2309                         in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[0]);
 2310                         in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[1]);
 2311                         fin = (struct sockaddr_in *)&addrs[0];
 2312                         lin = (struct sockaddr_in *)&addrs[1];
 2313                         break;
 2314                 }
 2315                 error = sa6_embedscope(fin6, V_ip6_use_defzone);
 2316                 if (error)
 2317                         return (error);
 2318                 error = sa6_embedscope(lin6, V_ip6_use_defzone);
 2319                 if (error)
 2320                         return (error);
 2321                 break;
 2322 #endif
 2323         case AF_INET:
 2324                 fin = (struct sockaddr_in *)&addrs[0];
 2325                 lin = (struct sockaddr_in *)&addrs[1];
 2326                 if (fin->sin_len != sizeof(struct sockaddr_in) ||
 2327                     lin->sin_len != sizeof(struct sockaddr_in))
 2328                         return (EINVAL);
 2329                 break;
 2330         default:
 2331                 return (EINVAL);
 2332         }
 2333         INP_INFO_WLOCK(&V_tcbinfo);
 2334         switch (addrs[0].ss_family) {
 2335 #ifdef INET6
 2336         case AF_INET6:
 2337                 inp = in6_pcblookup_hash(&V_tcbinfo, &fin6->sin6_addr,
 2338                     fin6->sin6_port, &lin6->sin6_addr, lin6->sin6_port, 0,
 2339                     NULL);
 2340                 break;
 2341 #endif
 2342         case AF_INET:
 2343                 inp = in_pcblookup_hash(&V_tcbinfo, fin->sin_addr,
 2344                     fin->sin_port, lin->sin_addr, lin->sin_port, 0, NULL);
 2345                 break;
 2346         }
 2347         if (inp != NULL) {
 2348                 INP_WLOCK(inp);
 2349                 if (inp->inp_flags & INP_TIMEWAIT) {
 2350                         /*
 2351                          * XXXRW: There currently exists a state where an
 2352                          * inpcb is present, but its timewait state has been
 2353                          * discarded.  For now, don't allow dropping of this
 2354                          * type of inpcb.
 2355                          */
 2356                         tw = intotw(inp);
 2357                         if (tw != NULL)
 2358                                 tcp_twclose(tw, 0);
 2359                         else
 2360                                 INP_WUNLOCK(inp);
 2361                 } else if (!(inp->inp_flags & INP_DROPPED) &&
 2362                            !(inp->inp_socket->so_options & SO_ACCEPTCONN)) {
 2363                         tp = intotcpcb(inp);
 2364                         tp = tcp_drop(tp, ECONNABORTED);
 2365                         if (tp != NULL)
 2366                                 INP_WUNLOCK(inp);
 2367                 } else
 2368                         INP_WUNLOCK(inp);
 2369         } else
 2370                 error = ESRCH;
 2371         INP_INFO_WUNLOCK(&V_tcbinfo);
 2372         return (error);
 2373 }
 2374 
 2375 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DROP, drop,
 2376     CTLTYPE_STRUCT|CTLFLAG_WR|CTLFLAG_SKIP, NULL,
 2377     0, sysctl_drop, "", "Drop TCP connection");
 2378 
 2379 /*
 2380  * Generate a standardized TCP log line for use throughout the
 2381  * tcp subsystem.  Memory allocation is done with M_NOWAIT to
 2382  * allow use in the interrupt context.
 2383  *
 2384  * NB: The caller MUST free(s, M_TCPLOG) the returned string.
 2385  * NB: The function may return NULL if memory allocation failed.
 2386  *
 2387  * Due to header inclusion and ordering limitations the struct ip
 2388  * and ip6_hdr pointers have to be passed as void pointers.
 2389  */
 2390 char *
 2391 tcp_log_vain(struct in_conninfo *inc, struct tcphdr *th, void *ip4hdr,
 2392     const void *ip6hdr)
 2393 {
 2394 
 2395         /* Is logging enabled? */
 2396         if (tcp_log_in_vain == 0)
 2397                 return (NULL);
 2398 
 2399         return (tcp_log_addr(inc, th, ip4hdr, ip6hdr));
 2400 }
 2401 
 2402 char *
 2403 tcp_log_addrs(struct in_conninfo *inc, struct tcphdr *th, void *ip4hdr,
 2404     const void *ip6hdr)
 2405 {
 2406 
 2407         /* Is logging enabled? */
 2408         if (tcp_log_debug == 0)
 2409                 return (NULL);
 2410 
 2411         return (tcp_log_addr(inc, th, ip4hdr, ip6hdr));
 2412 }
 2413 
 2414 static char *
 2415 tcp_log_addr(struct in_conninfo *inc, struct tcphdr *th, void *ip4hdr,
 2416     const void *ip6hdr)
 2417 {
 2418         char *s, *sp;
 2419         size_t size;
 2420         struct ip *ip;
 2421 #ifdef INET6
 2422         const struct ip6_hdr *ip6;
 2423 
 2424         ip6 = (const struct ip6_hdr *)ip6hdr;
 2425 #endif /* INET6 */
 2426         ip = (struct ip *)ip4hdr;
 2427 
 2428         /*
 2429          * The log line looks like this:
 2430          * "TCP: [1.2.3.4]:50332 to [1.2.3.4]:80 tcpflags 0x2<SYN>"
 2431          */
 2432         size = sizeof("TCP: []:12345 to []:12345 tcpflags 0x2<>") +
 2433             sizeof(PRINT_TH_FLAGS) + 1 +
 2434 #ifdef INET6
 2435             2 * INET6_ADDRSTRLEN;
 2436 #else
 2437             2 * INET_ADDRSTRLEN;
 2438 #endif /* INET6 */
 2439 
 2440         s = malloc(size, M_TCPLOG, M_ZERO|M_NOWAIT);
 2441         if (s == NULL)
 2442                 return (NULL);
 2443 
 2444         strcat(s, "TCP: [");
 2445         sp = s + strlen(s);
 2446 
 2447         if (inc && ((inc->inc_flags & INC_ISIPV6) == 0)) {
 2448                 inet_ntoa_r(inc->inc_faddr, sp);
 2449                 sp = s + strlen(s);
 2450                 sprintf(sp, "]:%i to [", ntohs(inc->inc_fport));
 2451                 sp = s + strlen(s);
 2452                 inet_ntoa_r(inc->inc_laddr, sp);
 2453                 sp = s + strlen(s);
 2454                 sprintf(sp, "]:%i", ntohs(inc->inc_lport));
 2455 #ifdef INET6
 2456         } else if (inc) {
 2457                 ip6_sprintf(sp, &inc->inc6_faddr);
 2458                 sp = s + strlen(s);
 2459                 sprintf(sp, "]:%i to [", ntohs(inc->inc_fport));
 2460                 sp = s + strlen(s);
 2461                 ip6_sprintf(sp, &inc->inc6_laddr);
 2462                 sp = s + strlen(s);
 2463                 sprintf(sp, "]:%i", ntohs(inc->inc_lport));
 2464         } else if (ip6 && th) {
 2465                 ip6_sprintf(sp, &ip6->ip6_src);
 2466                 sp = s + strlen(s);
 2467                 sprintf(sp, "]:%i to [", ntohs(th->th_sport));
 2468                 sp = s + strlen(s);
 2469                 ip6_sprintf(sp, &ip6->ip6_dst);
 2470                 sp = s + strlen(s);
 2471                 sprintf(sp, "]:%i", ntohs(th->th_dport));
 2472 #endif /* INET6 */
 2473         } else if (ip && th) {
 2474                 inet_ntoa_r(ip->ip_src, sp);
 2475                 sp = s + strlen(s);
 2476                 sprintf(sp, "]:%i to [", ntohs(th->th_sport));
 2477                 sp = s + strlen(s);
 2478                 inet_ntoa_r(ip->ip_dst, sp);
 2479                 sp = s + strlen(s);
 2480                 sprintf(sp, "]:%i", ntohs(th->th_dport));
 2481         } else {
 2482                 free(s, M_TCPLOG);
 2483                 return (NULL);
 2484         }
 2485         sp = s + strlen(s);
 2486         if (th)
 2487                 sprintf(sp, " tcpflags 0x%b", th->th_flags, PRINT_TH_FLAGS);
 2488         if (*(s + size - 1) != '\0')
 2489                 panic("%s: string too long", __func__);
 2490         return (s);
 2491 }

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