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/10.0/sys/netinet/tcp_subr.c 254889 2013-08-25 21:54:41Z markj $");
   34 
   35 #include "opt_compat.h"
   36 #include "opt_inet.h"
   37 #include "opt_inet6.h"
   38 #include "opt_ipsec.h"
   39 #include "opt_kdtrace.h"
   40 #include "opt_tcpdebug.h"
   41 
   42 #include <sys/param.h>
   43 #include <sys/systm.h>
   44 #include <sys/callout.h>
   45 #include <sys/hhook.h>
   46 #include <sys/kernel.h>
   47 #include <sys/khelp.h>
   48 #include <sys/sysctl.h>
   49 #include <sys/jail.h>
   50 #include <sys/malloc.h>
   51 #include <sys/mbuf.h>
   52 #ifdef INET6
   53 #include <sys/domain.h>
   54 #endif
   55 #include <sys/priv.h>
   56 #include <sys/proc.h>
   57 #include <sys/sdt.h>
   58 #include <sys/socket.h>
   59 #include <sys/socketvar.h>
   60 #include <sys/protosw.h>
   61 #include <sys/random.h>
   62 
   63 #include <vm/uma.h>
   64 
   65 #include <net/route.h>
   66 #include <net/if.h>
   67 #include <net/vnet.h>
   68 
   69 #include <netinet/cc.h>
   70 #include <netinet/in.h>
   71 #include <netinet/in_kdtrace.h>
   72 #include <netinet/in_pcb.h>
   73 #include <netinet/in_systm.h>
   74 #include <netinet/in_var.h>
   75 #include <netinet/ip.h>
   76 #include <netinet/ip_icmp.h>
   77 #include <netinet/ip_var.h>
   78 #ifdef INET6
   79 #include <netinet/ip6.h>
   80 #include <netinet6/in6_pcb.h>
   81 #include <netinet6/ip6_var.h>
   82 #include <netinet6/scope6_var.h>
   83 #include <netinet6/nd6.h>
   84 #endif
   85 
   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 #ifdef INET6
   92 #include <netinet6/tcp6_var.h>
   93 #endif
   94 #include <netinet/tcpip.h>
   95 #ifdef TCPDEBUG
   96 #include <netinet/tcp_debug.h>
   97 #endif
   98 #ifdef INET6
   99 #include <netinet6/ip6protosw.h>
  100 #endif
  101 #ifdef TCP_OFFLOAD
  102 #include <netinet/tcp_offload.h>
  103 #endif
  104 
  105 #ifdef IPSEC
  106 #include <netipsec/ipsec.h>
  107 #include <netipsec/xform.h>
  108 #ifdef INET6
  109 #include <netipsec/ipsec6.h>
  110 #endif
  111 #include <netipsec/key.h>
  112 #include <sys/syslog.h>
  113 #endif /*IPSEC*/
  114 
  115 #include <machine/in_cksum.h>
  116 #include <sys/md5.h>
  117 
  118 #include <security/mac/mac_framework.h>
  119 
  120 VNET_DEFINE(int, tcp_mssdflt) = TCP_MSS;
  121 #ifdef INET6
  122 VNET_DEFINE(int, tcp_v6mssdflt) = TCP6_MSS;
  123 #endif
  124 
  125 static int
  126 sysctl_net_inet_tcp_mss_check(SYSCTL_HANDLER_ARGS)
  127 {
  128         int error, new;
  129 
  130         new = V_tcp_mssdflt;
  131         error = sysctl_handle_int(oidp, &new, 0, req);
  132         if (error == 0 && req->newptr) {
  133                 if (new < TCP_MINMSS)
  134                         error = EINVAL;
  135                 else
  136                         V_tcp_mssdflt = new;
  137         }
  138         return (error);
  139 }
  140 
  141 SYSCTL_VNET_PROC(_net_inet_tcp, TCPCTL_MSSDFLT, mssdflt,
  142     CTLTYPE_INT|CTLFLAG_RW, &VNET_NAME(tcp_mssdflt), 0,
  143     &sysctl_net_inet_tcp_mss_check, "I",
  144     "Default TCP Maximum Segment Size");
  145 
  146 #ifdef INET6
  147 static int
  148 sysctl_net_inet_tcp_mss_v6_check(SYSCTL_HANDLER_ARGS)
  149 {
  150         int error, new;
  151 
  152         new = V_tcp_v6mssdflt;
  153         error = sysctl_handle_int(oidp, &new, 0, req);
  154         if (error == 0 && req->newptr) {
  155                 if (new < TCP_MINMSS)
  156                         error = EINVAL;
  157                 else
  158                         V_tcp_v6mssdflt = new;
  159         }
  160         return (error);
  161 }
  162 
  163 SYSCTL_VNET_PROC(_net_inet_tcp, TCPCTL_V6MSSDFLT, v6mssdflt,
  164     CTLTYPE_INT|CTLFLAG_RW, &VNET_NAME(tcp_v6mssdflt), 0,
  165     &sysctl_net_inet_tcp_mss_v6_check, "I",
  166    "Default TCP Maximum Segment Size for IPv6");
  167 #endif /* INET6 */
  168 
  169 /*
  170  * Minimum MSS we accept and use. This prevents DoS attacks where
  171  * we are forced to a ridiculous low MSS like 20 and send hundreds
  172  * of packets instead of one. The effect scales with the available
  173  * bandwidth and quickly saturates the CPU and network interface
  174  * with packet generation and sending. Set to zero to disable MINMSS
  175  * checking. This setting prevents us from sending too small packets.
  176  */
  177 VNET_DEFINE(int, tcp_minmss) = TCP_MINMSS;
  178 SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, minmss, CTLFLAG_RW,
  179      &VNET_NAME(tcp_minmss), 0,
  180     "Minimum TCP Maximum Segment Size");
  181 
  182 VNET_DEFINE(int, tcp_do_rfc1323) = 1;
  183 SYSCTL_VNET_INT(_net_inet_tcp, TCPCTL_DO_RFC1323, rfc1323, CTLFLAG_RW,
  184     &VNET_NAME(tcp_do_rfc1323), 0,
  185     "Enable rfc1323 (high performance TCP) extensions");
  186 
  187 static int      tcp_log_debug = 0;
  188 SYSCTL_INT(_net_inet_tcp, OID_AUTO, log_debug, CTLFLAG_RW,
  189     &tcp_log_debug, 0, "Log errors caused by incoming TCP segments");
  190 
  191 static int      tcp_tcbhashsize = 0;
  192 SYSCTL_INT(_net_inet_tcp, OID_AUTO, tcbhashsize, CTLFLAG_RDTUN,
  193     &tcp_tcbhashsize, 0, "Size of TCP control-block hashtable");
  194 
  195 static int      do_tcpdrain = 1;
  196 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_tcpdrain, CTLFLAG_RW, &do_tcpdrain, 0,
  197     "Enable tcp_drain routine for extra help when low on mbufs");
  198 
  199 SYSCTL_VNET_UINT(_net_inet_tcp, OID_AUTO, pcbcount, CTLFLAG_RD,
  200     &VNET_NAME(tcbinfo.ipi_count), 0, "Number of active PCBs");
  201 
  202 static VNET_DEFINE(int, icmp_may_rst) = 1;
  203 #define V_icmp_may_rst                  VNET(icmp_may_rst)
  204 SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, icmp_may_rst, CTLFLAG_RW,
  205     &VNET_NAME(icmp_may_rst), 0,
  206     "Certain ICMP unreachable messages may abort connections in SYN_SENT");
  207 
  208 static VNET_DEFINE(int, tcp_isn_reseed_interval) = 0;
  209 #define V_tcp_isn_reseed_interval       VNET(tcp_isn_reseed_interval)
  210 SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, isn_reseed_interval, CTLFLAG_RW,
  211     &VNET_NAME(tcp_isn_reseed_interval), 0,
  212     "Seconds between reseeding of ISN secret");
  213 
  214 static int      tcp_soreceive_stream = 0;
  215 SYSCTL_INT(_net_inet_tcp, OID_AUTO, soreceive_stream, CTLFLAG_RDTUN,
  216     &tcp_soreceive_stream, 0, "Using soreceive_stream for TCP sockets");
  217 
  218 #ifdef TCP_SIGNATURE
  219 static int      tcp_sig_checksigs = 1;
  220 SYSCTL_INT(_net_inet_tcp, OID_AUTO, signature_verify_input, CTLFLAG_RW,
  221     &tcp_sig_checksigs, 0, "Verify RFC2385 digests on inbound traffic");
  222 #endif
  223 
  224 VNET_DEFINE(uma_zone_t, sack_hole_zone);
  225 #define V_sack_hole_zone                VNET(sack_hole_zone)
  226 
  227 VNET_DEFINE(struct hhook_head *, tcp_hhh[HHOOK_TCP_LAST+1]);
  228 
  229 static struct inpcb *tcp_notify(struct inpcb *, int);
  230 static struct inpcb *tcp_mtudisc_notify(struct inpcb *, int);
  231 static char *   tcp_log_addr(struct in_conninfo *inc, struct tcphdr *th,
  232                     void *ip4hdr, const void *ip6hdr);
  233 
  234 /*
  235  * Target size of TCP PCB hash tables. Must be a power of two.
  236  *
  237  * Note that this can be overridden by the kernel environment
  238  * variable net.inet.tcp.tcbhashsize
  239  */
  240 #ifndef TCBHASHSIZE
  241 #define TCBHASHSIZE     0
  242 #endif
  243 
  244 /*
  245  * XXX
  246  * Callouts should be moved into struct tcp directly.  They are currently
  247  * separate because the tcpcb structure is exported to userland for sysctl
  248  * parsing purposes, which do not know about callouts.
  249  */
  250 struct tcpcb_mem {
  251         struct  tcpcb           tcb;
  252         struct  tcp_timer       tt;
  253         struct  cc_var          ccv;
  254         struct  osd             osd;
  255 };
  256 
  257 static VNET_DEFINE(uma_zone_t, tcpcb_zone);
  258 #define V_tcpcb_zone                    VNET(tcpcb_zone)
  259 
  260 MALLOC_DEFINE(M_TCPLOG, "tcplog", "TCP address and flags print buffers");
  261 static struct mtx isn_mtx;
  262 
  263 #define ISN_LOCK_INIT() mtx_init(&isn_mtx, "isn_mtx", NULL, MTX_DEF)
  264 #define ISN_LOCK()      mtx_lock(&isn_mtx)
  265 #define ISN_UNLOCK()    mtx_unlock(&isn_mtx)
  266 
  267 /*
  268  * TCP initialization.
  269  */
  270 static void
  271 tcp_zone_change(void *tag)
  272 {
  273 
  274         uma_zone_set_max(V_tcbinfo.ipi_zone, maxsockets);
  275         uma_zone_set_max(V_tcpcb_zone, maxsockets);
  276         tcp_tw_zone_change();
  277 }
  278 
  279 static int
  280 tcp_inpcb_init(void *mem, int size, int flags)
  281 {
  282         struct inpcb *inp = mem;
  283 
  284         INP_LOCK_INIT(inp, "inp", "tcpinp");
  285         return (0);
  286 }
  287 
  288 /*
  289  * Take a value and get the next power of 2 that doesn't overflow.
  290  * Used to size the tcp_inpcb hash buckets.
  291  */
  292 static int
  293 maketcp_hashsize(int size)
  294 {
  295         int hashsize;
  296 
  297         /*
  298          * auto tune.
  299          * get the next power of 2 higher than maxsockets.
  300          */
  301         hashsize = 1 << fls(size);
  302         /* catch overflow, and just go one power of 2 smaller */
  303         if (hashsize < size) {
  304                 hashsize = 1 << (fls(size) - 1);
  305         }
  306         return (hashsize);
  307 }
  308 
  309 void
  310 tcp_init(void)
  311 {
  312         const char *tcbhash_tuneable;
  313         int hashsize;
  314 
  315         tcbhash_tuneable = "net.inet.tcp.tcbhashsize";
  316 
  317         if (hhook_head_register(HHOOK_TYPE_TCP, HHOOK_TCP_EST_IN,
  318             &V_tcp_hhh[HHOOK_TCP_EST_IN], HHOOK_NOWAIT|HHOOK_HEADISINVNET) != 0)
  319                 printf("%s: WARNING: unable to register helper hook\n", __func__);
  320         if (hhook_head_register(HHOOK_TYPE_TCP, HHOOK_TCP_EST_OUT,
  321             &V_tcp_hhh[HHOOK_TCP_EST_OUT], HHOOK_NOWAIT|HHOOK_HEADISINVNET) != 0)
  322                 printf("%s: WARNING: unable to register helper hook\n", __func__);
  323 
  324         hashsize = TCBHASHSIZE;
  325         TUNABLE_INT_FETCH(tcbhash_tuneable, &hashsize);
  326         if (hashsize == 0) {
  327                 /*
  328                  * Auto tune the hash size based on maxsockets.
  329                  * A perfect hash would have a 1:1 mapping
  330                  * (hashsize = maxsockets) however it's been
  331                  * suggested that O(2) average is better.
  332                  */
  333                 hashsize = maketcp_hashsize(maxsockets / 4);
  334                 /*
  335                  * Our historical default is 512,
  336                  * do not autotune lower than this.
  337                  */
  338                 if (hashsize < 512)
  339                         hashsize = 512;
  340                 if (bootverbose)
  341                         printf("%s: %s auto tuned to %d\n", __func__,
  342                             tcbhash_tuneable, hashsize);
  343         }
  344         /*
  345          * We require a hashsize to be a power of two.
  346          * Previously if it was not a power of two we would just reset it
  347          * back to 512, which could be a nasty surprise if you did not notice
  348          * the error message.
  349          * Instead what we do is clip it to the closest power of two lower
  350          * than the specified hash value.
  351          */
  352         if (!powerof2(hashsize)) {
  353                 int oldhashsize = hashsize;
  354 
  355                 hashsize = maketcp_hashsize(hashsize);
  356                 /* prevent absurdly low value */
  357                 if (hashsize < 16)
  358                         hashsize = 16;
  359                 printf("%s: WARNING: TCB hash size not a power of 2, "
  360                     "clipped from %d to %d.\n", __func__, oldhashsize,
  361                     hashsize);
  362         }
  363         in_pcbinfo_init(&V_tcbinfo, "tcp", &V_tcb, hashsize, hashsize,
  364             "tcp_inpcb", tcp_inpcb_init, NULL, UMA_ZONE_NOFREE,
  365             IPI_HASHFIELDS_4TUPLE);
  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         uma_zone_set_warning(V_tcpcb_zone, "kern.ipc.maxsockets limit reached");
  374 
  375         tcp_tw_init();
  376         syncache_init();
  377         tcp_hc_init();
  378         tcp_reass_init();
  379 
  380         TUNABLE_INT_FETCH("net.inet.tcp.sack.enable", &V_tcp_do_sack);
  381         V_sack_hole_zone = uma_zcreate("sackhole", sizeof(struct sackhole),
  382             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
  383 
  384         /* Skip initialization of globals for non-default instances. */
  385         if (!IS_DEFAULT_VNET(curvnet))
  386                 return;
  387 
  388         /* XXX virtualize those bellow? */
  389         tcp_delacktime = TCPTV_DELACK;
  390         tcp_keepinit = TCPTV_KEEP_INIT;
  391         tcp_keepidle = TCPTV_KEEP_IDLE;
  392         tcp_keepintvl = TCPTV_KEEPINTVL;
  393         tcp_maxpersistidle = TCPTV_KEEP_IDLE;
  394         tcp_msl = TCPTV_MSL;
  395         tcp_rexmit_min = TCPTV_MIN;
  396         if (tcp_rexmit_min < 1)
  397                 tcp_rexmit_min = 1;
  398         tcp_rexmit_slop = TCPTV_CPU_VAR;
  399         tcp_finwait2_timeout = TCPTV_FINWAIT2_TIMEOUT;
  400         tcp_tcbhashsize = hashsize;
  401 
  402         TUNABLE_INT_FETCH("net.inet.tcp.soreceive_stream", &tcp_soreceive_stream);
  403         if (tcp_soreceive_stream) {
  404 #ifdef INET
  405                 tcp_usrreqs.pru_soreceive = soreceive_stream;
  406 #endif
  407 #ifdef INET6
  408                 tcp6_usrreqs.pru_soreceive = soreceive_stream;
  409 #endif /* INET6 */
  410         }
  411 
  412 #ifdef INET6
  413 #define TCP_MINPROTOHDR (sizeof(struct ip6_hdr) + sizeof(struct tcphdr))
  414 #else /* INET6 */
  415 #define TCP_MINPROTOHDR (sizeof(struct tcpiphdr))
  416 #endif /* INET6 */
  417         if (max_protohdr < TCP_MINPROTOHDR)
  418                 max_protohdr = TCP_MINPROTOHDR;
  419         if (max_linkhdr + TCP_MINPROTOHDR > MHLEN)
  420                 panic("tcp_init");
  421 #undef TCP_MINPROTOHDR
  422 
  423         ISN_LOCK_INIT();
  424         EVENTHANDLER_REGISTER(shutdown_pre_sync, tcp_fini, NULL,
  425                 SHUTDOWN_PRI_DEFAULT);
  426         EVENTHANDLER_REGISTER(maxsockets_change, tcp_zone_change, NULL,
  427                 EVENTHANDLER_PRI_ANY);
  428 }
  429 
  430 #ifdef VIMAGE
  431 void
  432 tcp_destroy(void)
  433 {
  434 
  435         tcp_reass_destroy();
  436         tcp_hc_destroy();
  437         syncache_destroy();
  438         tcp_tw_destroy();
  439         in_pcbinfo_destroy(&V_tcbinfo);
  440         uma_zdestroy(V_sack_hole_zone);
  441         uma_zdestroy(V_tcpcb_zone);
  442 }
  443 #endif
  444 
  445 void
  446 tcp_fini(void *xtp)
  447 {
  448 
  449 }
  450 
  451 /*
  452  * Fill in the IP and TCP headers for an outgoing packet, given the tcpcb.
  453  * tcp_template used to store this data in mbufs, but we now recopy it out
  454  * of the tcpcb each time to conserve mbufs.
  455  */
  456 void
  457 tcpip_fillheaders(struct inpcb *inp, void *ip_ptr, void *tcp_ptr)
  458 {
  459         struct tcphdr *th = (struct tcphdr *)tcp_ptr;
  460 
  461         INP_WLOCK_ASSERT(inp);
  462 
  463 #ifdef INET6
  464         if ((inp->inp_vflag & INP_IPV6) != 0) {
  465                 struct ip6_hdr *ip6;
  466 
  467                 ip6 = (struct ip6_hdr *)ip_ptr;
  468                 ip6->ip6_flow = (ip6->ip6_flow & ~IPV6_FLOWINFO_MASK) |
  469                         (inp->inp_flow & IPV6_FLOWINFO_MASK);
  470                 ip6->ip6_vfc = (ip6->ip6_vfc & ~IPV6_VERSION_MASK) |
  471                         (IPV6_VERSION & IPV6_VERSION_MASK);
  472                 ip6->ip6_nxt = IPPROTO_TCP;
  473                 ip6->ip6_plen = htons(sizeof(struct tcphdr));
  474                 ip6->ip6_src = inp->in6p_laddr;
  475                 ip6->ip6_dst = inp->in6p_faddr;
  476         }
  477 #endif /* INET6 */
  478 #if defined(INET6) && defined(INET)
  479         else
  480 #endif
  481 #ifdef INET
  482         {
  483                 struct ip *ip;
  484 
  485                 ip = (struct ip *)ip_ptr;
  486                 ip->ip_v = IPVERSION;
  487                 ip->ip_hl = 5;
  488                 ip->ip_tos = inp->inp_ip_tos;
  489                 ip->ip_len = 0;
  490                 ip->ip_id = 0;
  491                 ip->ip_off = 0;
  492                 ip->ip_ttl = inp->inp_ip_ttl;
  493                 ip->ip_sum = 0;
  494                 ip->ip_p = IPPROTO_TCP;
  495                 ip->ip_src = inp->inp_laddr;
  496                 ip->ip_dst = inp->inp_faddr;
  497         }
  498 #endif /* INET */
  499         th->th_sport = inp->inp_lport;
  500         th->th_dport = inp->inp_fport;
  501         th->th_seq = 0;
  502         th->th_ack = 0;
  503         th->th_x2 = 0;
  504         th->th_off = 5;
  505         th->th_flags = 0;
  506         th->th_win = 0;
  507         th->th_urp = 0;
  508         th->th_sum = 0;         /* in_pseudo() is called later for ipv4 */
  509 }
  510 
  511 /*
  512  * Create template to be used to send tcp packets on a connection.
  513  * Allocates an mbuf and fills in a skeletal tcp/ip header.  The only
  514  * use for this function is in keepalives, which use tcp_respond.
  515  */
  516 struct tcptemp *
  517 tcpip_maketemplate(struct inpcb *inp)
  518 {
  519         struct tcptemp *t;
  520 
  521         t = malloc(sizeof(*t), M_TEMP, M_NOWAIT);
  522         if (t == NULL)
  523                 return (NULL);
  524         tcpip_fillheaders(inp, (void *)&t->tt_ipgen, (void *)&t->tt_t);
  525         return (t);
  526 }
  527 
  528 /*
  529  * Send a single message to the TCP at address specified by
  530  * the given TCP/IP header.  If m == NULL, then we make a copy
  531  * of the tcpiphdr at ti and send directly to the addressed host.
  532  * This is used to force keep alive messages out using the TCP
  533  * template for a connection.  If flags are given then we send
  534  * a message back to the TCP which originated the * segment ti,
  535  * and discard the mbuf containing it and any other attached mbufs.
  536  *
  537  * In any case the ack and sequence number of the transmitted
  538  * segment are as specified by the parameters.
  539  *
  540  * NOTE: If m != NULL, then ti must point to *inside* the mbuf.
  541  */
  542 void
  543 tcp_respond(struct tcpcb *tp, void *ipgen, struct tcphdr *th, struct mbuf *m,
  544     tcp_seq ack, tcp_seq seq, int flags)
  545 {
  546         int tlen;
  547         int win = 0;
  548         struct ip *ip;
  549         struct tcphdr *nth;
  550 #ifdef INET6
  551         struct ip6_hdr *ip6;
  552         int isipv6;
  553 #endif /* INET6 */
  554         int ipflags = 0;
  555         struct inpcb *inp;
  556 
  557         KASSERT(tp != NULL || m != NULL, ("tcp_respond: tp and m both NULL"));
  558 
  559 #ifdef INET6
  560         isipv6 = ((struct ip *)ipgen)->ip_v == (IPV6_VERSION >> 4);
  561         ip6 = ipgen;
  562 #endif /* INET6 */
  563         ip = ipgen;
  564 
  565         if (tp != NULL) {
  566                 inp = tp->t_inpcb;
  567                 KASSERT(inp != NULL, ("tcp control block w/o inpcb"));
  568                 INP_WLOCK_ASSERT(inp);
  569         } else
  570                 inp = NULL;
  571 
  572         if (tp != NULL) {
  573                 if (!(flags & TH_RST)) {
  574                         win = sbspace(&inp->inp_socket->so_rcv);
  575                         if (win > (long)TCP_MAXWIN << tp->rcv_scale)
  576                                 win = (long)TCP_MAXWIN << tp->rcv_scale;
  577                 }
  578         }
  579         if (m == NULL) {
  580                 m = m_gethdr(M_NOWAIT, MT_DATA);
  581                 if (m == NULL)
  582                         return;
  583                 tlen = 0;
  584                 m->m_data += max_linkhdr;
  585 #ifdef INET6
  586                 if (isipv6) {
  587                         bcopy((caddr_t)ip6, mtod(m, caddr_t),
  588                               sizeof(struct ip6_hdr));
  589                         ip6 = mtod(m, struct ip6_hdr *);
  590                         nth = (struct tcphdr *)(ip6 + 1);
  591                 } else
  592 #endif /* INET6 */
  593                 {
  594                         bcopy((caddr_t)ip, mtod(m, caddr_t), sizeof(struct ip));
  595                         ip = mtod(m, struct ip *);
  596                         nth = (struct tcphdr *)(ip + 1);
  597                 }
  598                 bcopy((caddr_t)th, (caddr_t)nth, sizeof(struct tcphdr));
  599                 flags = TH_ACK;
  600         } else {
  601                 /*
  602                  *  reuse the mbuf. 
  603                  * XXX MRT We inherrit the FIB, which is lucky.
  604                  */
  605                 m_freem(m->m_next);
  606                 m->m_next = NULL;
  607                 m->m_data = (caddr_t)ipgen;
  608                 /* m_len is set later */
  609                 tlen = 0;
  610 #define xchg(a,b,type) { type t; t=a; a=b; b=t; }
  611 #ifdef INET6
  612                 if (isipv6) {
  613                         xchg(ip6->ip6_dst, ip6->ip6_src, struct in6_addr);
  614                         nth = (struct tcphdr *)(ip6 + 1);
  615                 } else
  616 #endif /* INET6 */
  617                 {
  618                         xchg(ip->ip_dst.s_addr, ip->ip_src.s_addr, uint32_t);
  619                         nth = (struct tcphdr *)(ip + 1);
  620                 }
  621                 if (th != nth) {
  622                         /*
  623                          * this is usually a case when an extension header
  624                          * exists between the IPv6 header and the
  625                          * TCP header.
  626                          */
  627                         nth->th_sport = th->th_sport;
  628                         nth->th_dport = th->th_dport;
  629                 }
  630                 xchg(nth->th_dport, nth->th_sport, uint16_t);
  631 #undef xchg
  632         }
  633 #ifdef INET6
  634         if (isipv6) {
  635                 ip6->ip6_flow = 0;
  636                 ip6->ip6_vfc = IPV6_VERSION;
  637                 ip6->ip6_nxt = IPPROTO_TCP;
  638                 tlen += sizeof (struct ip6_hdr) + sizeof (struct tcphdr);
  639                 ip6->ip6_plen = htons(tlen - sizeof(*ip6));
  640         }
  641 #endif
  642 #if defined(INET) && defined(INET6)
  643         else
  644 #endif
  645 #ifdef INET
  646         {
  647                 tlen += sizeof (struct tcpiphdr);
  648                 ip->ip_len = htons(tlen);
  649                 ip->ip_ttl = V_ip_defttl;
  650                 if (V_path_mtu_discovery)
  651                         ip->ip_off |= htons(IP_DF);
  652         }
  653 #endif
  654         m->m_len = tlen;
  655         m->m_pkthdr.len = tlen;
  656         m->m_pkthdr.rcvif = NULL;
  657 #ifdef MAC
  658         if (inp != NULL) {
  659                 /*
  660                  * Packet is associated with a socket, so allow the
  661                  * label of the response to reflect the socket label.
  662                  */
  663                 INP_WLOCK_ASSERT(inp);
  664                 mac_inpcb_create_mbuf(inp, m);
  665         } else {
  666                 /*
  667                  * Packet is not associated with a socket, so possibly
  668                  * update the label in place.
  669                  */
  670                 mac_netinet_tcp_reply(m);
  671         }
  672 #endif
  673         nth->th_seq = htonl(seq);
  674         nth->th_ack = htonl(ack);
  675         nth->th_x2 = 0;
  676         nth->th_off = sizeof (struct tcphdr) >> 2;
  677         nth->th_flags = flags;
  678         if (tp != NULL)
  679                 nth->th_win = htons((u_short) (win >> tp->rcv_scale));
  680         else
  681                 nth->th_win = htons((u_short)win);
  682         nth->th_urp = 0;
  683 
  684         m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum);
  685 #ifdef INET6
  686         if (isipv6) {
  687                 m->m_pkthdr.csum_flags = CSUM_TCP_IPV6;
  688                 nth->th_sum = in6_cksum_pseudo(ip6,
  689                     tlen - sizeof(struct ip6_hdr), IPPROTO_TCP, 0);
  690                 ip6->ip6_hlim = in6_selecthlim(tp != NULL ? tp->t_inpcb :
  691                     NULL, NULL);
  692         }
  693 #endif /* INET6 */
  694 #if defined(INET6) && defined(INET)
  695         else
  696 #endif
  697 #ifdef INET
  698         {
  699                 m->m_pkthdr.csum_flags = CSUM_TCP;
  700                 nth->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr,
  701                     htons((u_short)(tlen - sizeof(struct ip) + ip->ip_p)));
  702         }
  703 #endif /* INET */
  704 #ifdef TCPDEBUG
  705         if (tp == NULL || (inp->inp_socket->so_options & SO_DEBUG))
  706                 tcp_trace(TA_OUTPUT, 0, tp, mtod(m, void *), th, 0);
  707 #endif
  708         if (flags & TH_RST)
  709                 TCP_PROBE5(accept_refused, NULL, NULL, m->m_data, tp, nth);
  710 
  711         TCP_PROBE5(send, NULL, tp, m->m_data, tp, nth);
  712 #ifdef INET6
  713         if (isipv6)
  714                 (void) ip6_output(m, NULL, NULL, ipflags, NULL, NULL, inp);
  715 #endif /* INET6 */
  716 #if defined(INET) && defined(INET6)
  717         else
  718 #endif
  719 #ifdef INET
  720                 (void) ip_output(m, NULL, NULL, ipflags, NULL, inp);
  721 #endif
  722 }
  723 
  724 /*
  725  * Create a new TCP control block, making an
  726  * empty reassembly queue and hooking it to the argument
  727  * protocol control block.  The `inp' parameter must have
  728  * come from the zone allocator set up in tcp_init().
  729  */
  730 struct tcpcb *
  731 tcp_newtcpcb(struct inpcb *inp)
  732 {
  733         struct tcpcb_mem *tm;
  734         struct tcpcb *tp;
  735 #ifdef INET6
  736         int isipv6 = (inp->inp_vflag & INP_IPV6) != 0;
  737 #endif /* INET6 */
  738 
  739         tm = uma_zalloc(V_tcpcb_zone, M_NOWAIT | M_ZERO);
  740         if (tm == NULL)
  741                 return (NULL);
  742         tp = &tm->tcb;
  743 
  744         /* Initialise cc_var struct for this tcpcb. */
  745         tp->ccv = &tm->ccv;
  746         tp->ccv->type = IPPROTO_TCP;
  747         tp->ccv->ccvc.tcp = tp;
  748 
  749         /*
  750          * Use the current system default CC algorithm.
  751          */
  752         CC_LIST_RLOCK();
  753         KASSERT(!STAILQ_EMPTY(&cc_list), ("cc_list is empty!"));
  754         CC_ALGO(tp) = CC_DEFAULT();
  755         CC_LIST_RUNLOCK();
  756 
  757         if (CC_ALGO(tp)->cb_init != NULL)
  758                 if (CC_ALGO(tp)->cb_init(tp->ccv) > 0) {
  759                         uma_zfree(V_tcpcb_zone, tm);
  760                         return (NULL);
  761                 }
  762 
  763         tp->osd = &tm->osd;
  764         if (khelp_init_osd(HELPER_CLASS_TCP, tp->osd)) {
  765                 uma_zfree(V_tcpcb_zone, tm);
  766                 return (NULL);
  767         }
  768 
  769 #ifdef VIMAGE
  770         tp->t_vnet = inp->inp_vnet;
  771 #endif
  772         tp->t_timers = &tm->tt;
  773         /*      LIST_INIT(&tp->t_segq); */      /* XXX covered by M_ZERO */
  774         tp->t_maxseg = tp->t_maxopd =
  775 #ifdef INET6
  776                 isipv6 ? V_tcp_v6mssdflt :
  777 #endif /* INET6 */
  778                 V_tcp_mssdflt;
  779 
  780         /* Set up our timeouts. */
  781         callout_init(&tp->t_timers->tt_rexmt, CALLOUT_MPSAFE);
  782         callout_init(&tp->t_timers->tt_persist, CALLOUT_MPSAFE);
  783         callout_init(&tp->t_timers->tt_keep, CALLOUT_MPSAFE);
  784         callout_init(&tp->t_timers->tt_2msl, CALLOUT_MPSAFE);
  785         callout_init(&tp->t_timers->tt_delack, CALLOUT_MPSAFE);
  786 
  787         if (V_tcp_do_rfc1323)
  788                 tp->t_flags = (TF_REQ_SCALE|TF_REQ_TSTMP);
  789         if (V_tcp_do_sack)
  790                 tp->t_flags |= TF_SACK_PERMIT;
  791         TAILQ_INIT(&tp->snd_holes);
  792         tp->t_inpcb = inp;      /* XXX */
  793         /*
  794          * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no
  795          * rtt estimate.  Set rttvar so that srtt + 4 * rttvar gives
  796          * reasonable initial retransmit time.
  797          */
  798         tp->t_srtt = TCPTV_SRTTBASE;
  799         tp->t_rttvar = ((TCPTV_RTOBASE - TCPTV_SRTTBASE) << TCP_RTTVAR_SHIFT) / 4;
  800         tp->t_rttmin = tcp_rexmit_min;
  801         tp->t_rxtcur = TCPTV_RTOBASE;
  802         tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
  803         tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT;
  804         tp->t_rcvtime = ticks;
  805         /*
  806          * IPv4 TTL initialization is necessary for an IPv6 socket as well,
  807          * because the socket may be bound to an IPv6 wildcard address,
  808          * which may match an IPv4-mapped IPv6 address.
  809          */
  810         inp->inp_ip_ttl = V_ip_defttl;
  811         inp->inp_ppcb = tp;
  812         return (tp);            /* XXX */
  813 }
  814 
  815 /*
  816  * Switch the congestion control algorithm back to NewReno for any active
  817  * control blocks using an algorithm which is about to go away.
  818  * This ensures the CC framework can allow the unload to proceed without leaving
  819  * any dangling pointers which would trigger a panic.
  820  * Returning non-zero would inform the CC framework that something went wrong
  821  * and it would be unsafe to allow the unload to proceed. However, there is no
  822  * way for this to occur with this implementation so we always return zero.
  823  */
  824 int
  825 tcp_ccalgounload(struct cc_algo *unload_algo)
  826 {
  827         struct cc_algo *tmpalgo;
  828         struct inpcb *inp;
  829         struct tcpcb *tp;
  830         VNET_ITERATOR_DECL(vnet_iter);
  831 
  832         /*
  833          * Check all active control blocks across all network stacks and change
  834          * any that are using "unload_algo" back to NewReno. If "unload_algo"
  835          * requires cleanup code to be run, call it.
  836          */
  837         VNET_LIST_RLOCK();
  838         VNET_FOREACH(vnet_iter) {
  839                 CURVNET_SET(vnet_iter);
  840                 INP_INFO_RLOCK(&V_tcbinfo);
  841                 /*
  842                  * New connections already part way through being initialised
  843                  * with the CC algo we're removing will not race with this code
  844                  * because the INP_INFO_WLOCK is held during initialisation. We
  845                  * therefore don't enter the loop below until the connection
  846                  * list has stabilised.
  847                  */
  848                 LIST_FOREACH(inp, &V_tcb, inp_list) {
  849                         INP_WLOCK(inp);
  850                         /* Important to skip tcptw structs. */
  851                         if (!(inp->inp_flags & INP_TIMEWAIT) &&
  852                             (tp = intotcpcb(inp)) != NULL) {
  853                                 /*
  854                                  * By holding INP_WLOCK here, we are assured
  855                                  * that the connection is not currently
  856                                  * executing inside the CC module's functions
  857                                  * i.e. it is safe to make the switch back to
  858                                  * NewReno.
  859                                  */
  860                                 if (CC_ALGO(tp) == unload_algo) {
  861                                         tmpalgo = CC_ALGO(tp);
  862                                         /* NewReno does not require any init. */
  863                                         CC_ALGO(tp) = &newreno_cc_algo;
  864                                         if (tmpalgo->cb_destroy != NULL)
  865                                                 tmpalgo->cb_destroy(tp->ccv);
  866                                 }
  867                         }
  868                         INP_WUNLOCK(inp);
  869                 }
  870                 INP_INFO_RUNLOCK(&V_tcbinfo);
  871                 CURVNET_RESTORE();
  872         }
  873         VNET_LIST_RUNLOCK();
  874 
  875         return (0);
  876 }
  877 
  878 /*
  879  * Drop a TCP connection, reporting
  880  * the specified error.  If connection is synchronized,
  881  * then send a RST to peer.
  882  */
  883 struct tcpcb *
  884 tcp_drop(struct tcpcb *tp, int errno)
  885 {
  886         struct socket *so = tp->t_inpcb->inp_socket;
  887 
  888         INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
  889         INP_WLOCK_ASSERT(tp->t_inpcb);
  890 
  891         if (TCPS_HAVERCVDSYN(tp->t_state)) {
  892                 tcp_state_change(tp, TCPS_CLOSED);
  893                 (void) tcp_output(tp);
  894                 TCPSTAT_INC(tcps_drops);
  895         } else
  896                 TCPSTAT_INC(tcps_conndrops);
  897         if (errno == ETIMEDOUT && tp->t_softerror)
  898                 errno = tp->t_softerror;
  899         so->so_error = errno;
  900         return (tcp_close(tp));
  901 }
  902 
  903 void
  904 tcp_discardcb(struct tcpcb *tp)
  905 {
  906         struct inpcb *inp = tp->t_inpcb;
  907         struct socket *so = inp->inp_socket;
  908 #ifdef INET6
  909         int isipv6 = (inp->inp_vflag & INP_IPV6) != 0;
  910 #endif /* INET6 */
  911 
  912         INP_WLOCK_ASSERT(inp);
  913 
  914         /*
  915          * Make sure that all of our timers are stopped before we delete the
  916          * PCB.
  917          *
  918          * XXXRW: Really, we would like to use callout_drain() here in order
  919          * to avoid races experienced in tcp_timer.c where a timer is already
  920          * executing at this point.  However, we can't, both because we're
  921          * running in a context where we can't sleep, and also because we
  922          * hold locks required by the timers.  What we instead need to do is
  923          * test to see if callout_drain() is required, and if so, defer some
  924          * portion of the remainder of tcp_discardcb() to an asynchronous
  925          * context that can callout_drain() and then continue.  Some care
  926          * will be required to ensure that no further processing takes place
  927          * on the tcpcb, even though it hasn't been freed (a flag?).
  928          */
  929         callout_stop(&tp->t_timers->tt_rexmt);
  930         callout_stop(&tp->t_timers->tt_persist);
  931         callout_stop(&tp->t_timers->tt_keep);
  932         callout_stop(&tp->t_timers->tt_2msl);
  933         callout_stop(&tp->t_timers->tt_delack);
  934 
  935         /*
  936          * If we got enough samples through the srtt filter,
  937          * save the rtt and rttvar in the routing entry.
  938          * 'Enough' is arbitrarily defined as 4 rtt samples.
  939          * 4 samples is enough for the srtt filter to converge
  940          * to within enough % of the correct value; fewer samples
  941          * and we could save a bogus rtt. The danger is not high
  942          * as tcp quickly recovers from everything.
  943          * XXX: Works very well but needs some more statistics!
  944          */
  945         if (tp->t_rttupdated >= 4) {
  946                 struct hc_metrics_lite metrics;
  947                 u_long ssthresh;
  948 
  949                 bzero(&metrics, sizeof(metrics));
  950                 /*
  951                  * Update the ssthresh always when the conditions below
  952                  * are satisfied. This gives us better new start value
  953                  * for the congestion avoidance for new connections.
  954                  * ssthresh is only set if packet loss occured on a session.
  955                  *
  956                  * XXXRW: 'so' may be NULL here, and/or socket buffer may be
  957                  * being torn down.  Ideally this code would not use 'so'.
  958                  */
  959                 ssthresh = tp->snd_ssthresh;
  960                 if (ssthresh != 0 && ssthresh < so->so_snd.sb_hiwat / 2) {
  961                         /*
  962                          * convert the limit from user data bytes to
  963                          * packets then to packet data bytes.
  964                          */
  965                         ssthresh = (ssthresh + tp->t_maxseg / 2) / tp->t_maxseg;
  966                         if (ssthresh < 2)
  967                                 ssthresh = 2;
  968                         ssthresh *= (u_long)(tp->t_maxseg +
  969 #ifdef INET6
  970                             (isipv6 ? sizeof (struct ip6_hdr) +
  971                                 sizeof (struct tcphdr) :
  972 #endif
  973                                 sizeof (struct tcpiphdr)
  974 #ifdef INET6
  975                             )
  976 #endif
  977                             );
  978                 } else
  979                         ssthresh = 0;
  980                 metrics.rmx_ssthresh = ssthresh;
  981 
  982                 metrics.rmx_rtt = tp->t_srtt;
  983                 metrics.rmx_rttvar = tp->t_rttvar;
  984                 metrics.rmx_cwnd = tp->snd_cwnd;
  985                 metrics.rmx_sendpipe = 0;
  986                 metrics.rmx_recvpipe = 0;
  987 
  988                 tcp_hc_update(&inp->inp_inc, &metrics);
  989         }
  990 
  991         /* free the reassembly queue, if any */
  992         tcp_reass_flush(tp);
  993 
  994 #ifdef TCP_OFFLOAD
  995         /* Disconnect offload device, if any. */
  996         if (tp->t_flags & TF_TOE)
  997                 tcp_offload_detach(tp);
  998 #endif
  999                 
 1000         tcp_free_sackholes(tp);
 1001 
 1002         /* Allow the CC algorithm to clean up after itself. */
 1003         if (CC_ALGO(tp)->cb_destroy != NULL)
 1004                 CC_ALGO(tp)->cb_destroy(tp->ccv);
 1005 
 1006         khelp_destroy_osd(tp->osd);
 1007 
 1008         CC_ALGO(tp) = NULL;
 1009         inp->inp_ppcb = NULL;
 1010         tp->t_inpcb = NULL;
 1011         uma_zfree(V_tcpcb_zone, tp);
 1012 }
 1013 
 1014 /*
 1015  * Attempt to close a TCP control block, marking it as dropped, and freeing
 1016  * the socket if we hold the only reference.
 1017  */
 1018 struct tcpcb *
 1019 tcp_close(struct tcpcb *tp)
 1020 {
 1021         struct inpcb *inp = tp->t_inpcb;
 1022         struct socket *so;
 1023 
 1024         INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
 1025         INP_WLOCK_ASSERT(inp);
 1026 
 1027 #ifdef TCP_OFFLOAD
 1028         if (tp->t_state == TCPS_LISTEN)
 1029                 tcp_offload_listen_stop(tp);
 1030 #endif
 1031         in_pcbdrop(inp);
 1032         TCPSTAT_INC(tcps_closed);
 1033         KASSERT(inp->inp_socket != NULL, ("tcp_close: inp_socket NULL"));
 1034         so = inp->inp_socket;
 1035         soisdisconnected(so);
 1036         if (inp->inp_flags & INP_SOCKREF) {
 1037                 KASSERT(so->so_state & SS_PROTOREF,
 1038                     ("tcp_close: !SS_PROTOREF"));
 1039                 inp->inp_flags &= ~INP_SOCKREF;
 1040                 INP_WUNLOCK(inp);
 1041                 ACCEPT_LOCK();
 1042                 SOCK_LOCK(so);
 1043                 so->so_state &= ~SS_PROTOREF;
 1044                 sofree(so);
 1045                 return (NULL);
 1046         }
 1047         return (tp);
 1048 }
 1049 
 1050 void
 1051 tcp_drain(void)
 1052 {
 1053         VNET_ITERATOR_DECL(vnet_iter);
 1054 
 1055         if (!do_tcpdrain)
 1056                 return;
 1057 
 1058         VNET_LIST_RLOCK_NOSLEEP();
 1059         VNET_FOREACH(vnet_iter) {
 1060                 CURVNET_SET(vnet_iter);
 1061                 struct inpcb *inpb;
 1062                 struct tcpcb *tcpb;
 1063 
 1064         /*
 1065          * Walk the tcpbs, if existing, and flush the reassembly queue,
 1066          * if there is one...
 1067          * XXX: The "Net/3" implementation doesn't imply that the TCP
 1068          *      reassembly queue should be flushed, but in a situation
 1069          *      where we're really low on mbufs, this is potentially
 1070          *      useful.
 1071          */
 1072                 INP_INFO_RLOCK(&V_tcbinfo);
 1073                 LIST_FOREACH(inpb, V_tcbinfo.ipi_listhead, inp_list) {
 1074                         if (inpb->inp_flags & INP_TIMEWAIT)
 1075                                 continue;
 1076                         INP_WLOCK(inpb);
 1077                         if ((tcpb = intotcpcb(inpb)) != NULL) {
 1078                                 tcp_reass_flush(tcpb);
 1079                                 tcp_clean_sackreport(tcpb);
 1080                         }
 1081                         INP_WUNLOCK(inpb);
 1082                 }
 1083                 INP_INFO_RUNLOCK(&V_tcbinfo);
 1084                 CURVNET_RESTORE();
 1085         }
 1086         VNET_LIST_RUNLOCK_NOSLEEP();
 1087 }
 1088 
 1089 /*
 1090  * Notify a tcp user of an asynchronous error;
 1091  * store error as soft error, but wake up user
 1092  * (for now, won't do anything until can select for soft error).
 1093  *
 1094  * Do not wake up user since there currently is no mechanism for
 1095  * reporting soft errors (yet - a kqueue filter may be added).
 1096  */
 1097 static struct inpcb *
 1098 tcp_notify(struct inpcb *inp, int error)
 1099 {
 1100         struct tcpcb *tp;
 1101 
 1102         INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
 1103         INP_WLOCK_ASSERT(inp);
 1104 
 1105         if ((inp->inp_flags & INP_TIMEWAIT) ||
 1106             (inp->inp_flags & INP_DROPPED))
 1107                 return (inp);
 1108 
 1109         tp = intotcpcb(inp);
 1110         KASSERT(tp != NULL, ("tcp_notify: tp == NULL"));
 1111 
 1112         /*
 1113          * Ignore some errors if we are hooked up.
 1114          * If connection hasn't completed, has retransmitted several times,
 1115          * and receives a second error, give up now.  This is better
 1116          * than waiting a long time to establish a connection that
 1117          * can never complete.
 1118          */
 1119         if (tp->t_state == TCPS_ESTABLISHED &&
 1120             (error == EHOSTUNREACH || error == ENETUNREACH ||
 1121              error == EHOSTDOWN)) {
 1122                 return (inp);
 1123         } else if (tp->t_state < TCPS_ESTABLISHED && tp->t_rxtshift > 3 &&
 1124             tp->t_softerror) {
 1125                 tp = tcp_drop(tp, error);
 1126                 if (tp != NULL)
 1127                         return (inp);
 1128                 else
 1129                         return (NULL);
 1130         } else {
 1131                 tp->t_softerror = error;
 1132                 return (inp);
 1133         }
 1134 #if 0
 1135         wakeup( &so->so_timeo);
 1136         sorwakeup(so);
 1137         sowwakeup(so);
 1138 #endif
 1139 }
 1140 
 1141 static int
 1142 tcp_pcblist(SYSCTL_HANDLER_ARGS)
 1143 {
 1144         int error, i, m, n, pcb_count;
 1145         struct inpcb *inp, **inp_list;
 1146         inp_gen_t gencnt;
 1147         struct xinpgen xig;
 1148 
 1149         /*
 1150          * The process of preparing the TCB list is too time-consuming and
 1151          * resource-intensive to repeat twice on every request.
 1152          */
 1153         if (req->oldptr == NULL) {
 1154                 n = V_tcbinfo.ipi_count + syncache_pcbcount();
 1155                 n += imax(n / 8, 10);
 1156                 req->oldidx = 2 * (sizeof xig) + n * sizeof(struct xtcpcb);
 1157                 return (0);
 1158         }
 1159 
 1160         if (req->newptr != NULL)
 1161                 return (EPERM);
 1162 
 1163         /*
 1164          * OK, now we're committed to doing something.
 1165          */
 1166         INP_INFO_RLOCK(&V_tcbinfo);
 1167         gencnt = V_tcbinfo.ipi_gencnt;
 1168         n = V_tcbinfo.ipi_count;
 1169         INP_INFO_RUNLOCK(&V_tcbinfo);
 1170 
 1171         m = syncache_pcbcount();
 1172 
 1173         error = sysctl_wire_old_buffer(req, 2 * (sizeof xig)
 1174                 + (n + m) * sizeof(struct xtcpcb));
 1175         if (error != 0)
 1176                 return (error);
 1177 
 1178         xig.xig_len = sizeof xig;
 1179         xig.xig_count = n + m;
 1180         xig.xig_gen = gencnt;
 1181         xig.xig_sogen = so_gencnt;
 1182         error = SYSCTL_OUT(req, &xig, sizeof xig);
 1183         if (error)
 1184                 return (error);
 1185 
 1186         error = syncache_pcblist(req, m, &pcb_count);
 1187         if (error)
 1188                 return (error);
 1189 
 1190         inp_list = malloc(n * sizeof *inp_list, M_TEMP, M_WAITOK);
 1191         if (inp_list == NULL)
 1192                 return (ENOMEM);
 1193 
 1194         INP_INFO_RLOCK(&V_tcbinfo);
 1195         for (inp = LIST_FIRST(V_tcbinfo.ipi_listhead), i = 0;
 1196             inp != NULL && i < n; inp = LIST_NEXT(inp, inp_list)) {
 1197                 INP_WLOCK(inp);
 1198                 if (inp->inp_gencnt <= gencnt) {
 1199                         /*
 1200                          * XXX: This use of cr_cansee(), introduced with
 1201                          * TCP state changes, is not quite right, but for
 1202                          * now, better than nothing.
 1203                          */
 1204                         if (inp->inp_flags & INP_TIMEWAIT) {
 1205                                 if (intotw(inp) != NULL)
 1206                                         error = cr_cansee(req->td->td_ucred,
 1207                                             intotw(inp)->tw_cred);
 1208                                 else
 1209                                         error = EINVAL; /* Skip this inp. */
 1210                         } else
 1211                                 error = cr_canseeinpcb(req->td->td_ucred, inp);
 1212                         if (error == 0) {
 1213                                 in_pcbref(inp);
 1214                                 inp_list[i++] = inp;
 1215                         }
 1216                 }
 1217                 INP_WUNLOCK(inp);
 1218         }
 1219         INP_INFO_RUNLOCK(&V_tcbinfo);
 1220         n = i;
 1221 
 1222         error = 0;
 1223         for (i = 0; i < n; i++) {
 1224                 inp = inp_list[i];
 1225                 INP_RLOCK(inp);
 1226                 if (inp->inp_gencnt <= gencnt) {
 1227                         struct xtcpcb xt;
 1228                         void *inp_ppcb;
 1229 
 1230                         bzero(&xt, sizeof(xt));
 1231                         xt.xt_len = sizeof xt;
 1232                         /* XXX should avoid extra copy */
 1233                         bcopy(inp, &xt.xt_inp, sizeof *inp);
 1234                         inp_ppcb = inp->inp_ppcb;
 1235                         if (inp_ppcb == NULL)
 1236                                 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp);
 1237                         else if (inp->inp_flags & INP_TIMEWAIT) {
 1238                                 bzero((char *) &xt.xt_tp, sizeof xt.xt_tp);
 1239                                 xt.xt_tp.t_state = TCPS_TIME_WAIT;
 1240                         } else {
 1241                                 bcopy(inp_ppcb, &xt.xt_tp, sizeof xt.xt_tp);
 1242                                 if (xt.xt_tp.t_timers)
 1243                                         tcp_timer_to_xtimer(&xt.xt_tp, xt.xt_tp.t_timers, &xt.xt_timer);
 1244                         }
 1245                         if (inp->inp_socket != NULL)
 1246                                 sotoxsocket(inp->inp_socket, &xt.xt_socket);
 1247                         else {
 1248                                 bzero(&xt.xt_socket, sizeof xt.xt_socket);
 1249                                 xt.xt_socket.xso_protocol = IPPROTO_TCP;
 1250                         }
 1251                         xt.xt_inp.inp_gencnt = inp->inp_gencnt;
 1252                         INP_RUNLOCK(inp);
 1253                         error = SYSCTL_OUT(req, &xt, sizeof xt);
 1254                 } else
 1255                         INP_RUNLOCK(inp);
 1256         }
 1257         INP_INFO_WLOCK(&V_tcbinfo);
 1258         for (i = 0; i < n; i++) {
 1259                 inp = inp_list[i];
 1260                 INP_RLOCK(inp);
 1261                 if (!in_pcbrele_rlocked(inp))
 1262                         INP_RUNLOCK(inp);
 1263         }
 1264         INP_INFO_WUNLOCK(&V_tcbinfo);
 1265 
 1266         if (!error) {
 1267                 /*
 1268                  * Give the user an updated idea of our state.
 1269                  * If the generation differs from what we told
 1270                  * her before, she knows that something happened
 1271                  * while we were processing this request, and it
 1272                  * might be necessary to retry.
 1273                  */
 1274                 INP_INFO_RLOCK(&V_tcbinfo);
 1275                 xig.xig_gen = V_tcbinfo.ipi_gencnt;
 1276                 xig.xig_sogen = so_gencnt;
 1277                 xig.xig_count = V_tcbinfo.ipi_count + pcb_count;
 1278                 INP_INFO_RUNLOCK(&V_tcbinfo);
 1279                 error = SYSCTL_OUT(req, &xig, sizeof xig);
 1280         }
 1281         free(inp_list, M_TEMP);
 1282         return (error);
 1283 }
 1284 
 1285 SYSCTL_PROC(_net_inet_tcp, TCPCTL_PCBLIST, pcblist,
 1286     CTLTYPE_OPAQUE | CTLFLAG_RD, NULL, 0,
 1287     tcp_pcblist, "S,xtcpcb", "List of active TCP connections");
 1288 
 1289 #ifdef INET
 1290 static int
 1291 tcp_getcred(SYSCTL_HANDLER_ARGS)
 1292 {
 1293         struct xucred xuc;
 1294         struct sockaddr_in addrs[2];
 1295         struct inpcb *inp;
 1296         int error;
 1297 
 1298         error = priv_check(req->td, PRIV_NETINET_GETCRED);
 1299         if (error)
 1300                 return (error);
 1301         error = SYSCTL_IN(req, addrs, sizeof(addrs));
 1302         if (error)
 1303                 return (error);
 1304         inp = in_pcblookup(&V_tcbinfo, addrs[1].sin_addr, addrs[1].sin_port,
 1305             addrs[0].sin_addr, addrs[0].sin_port, INPLOOKUP_RLOCKPCB, NULL);
 1306         if (inp != NULL) {
 1307                 if (inp->inp_socket == NULL)
 1308                         error = ENOENT;
 1309                 if (error == 0)
 1310                         error = cr_canseeinpcb(req->td->td_ucred, inp);
 1311                 if (error == 0)
 1312                         cru2x(inp->inp_cred, &xuc);
 1313                 INP_RUNLOCK(inp);
 1314         } else
 1315                 error = ENOENT;
 1316         if (error == 0)
 1317                 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred));
 1318         return (error);
 1319 }
 1320 
 1321 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, getcred,
 1322     CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0,
 1323     tcp_getcred, "S,xucred", "Get the xucred of a TCP connection");
 1324 #endif /* INET */
 1325 
 1326 #ifdef INET6
 1327 static int
 1328 tcp6_getcred(SYSCTL_HANDLER_ARGS)
 1329 {
 1330         struct xucred xuc;
 1331         struct sockaddr_in6 addrs[2];
 1332         struct inpcb *inp;
 1333         int error;
 1334 #ifdef INET
 1335         int mapped = 0;
 1336 #endif
 1337 
 1338         error = priv_check(req->td, PRIV_NETINET_GETCRED);
 1339         if (error)
 1340                 return (error);
 1341         error = SYSCTL_IN(req, addrs, sizeof(addrs));
 1342         if (error)
 1343                 return (error);
 1344         if ((error = sa6_embedscope(&addrs[0], V_ip6_use_defzone)) != 0 ||
 1345             (error = sa6_embedscope(&addrs[1], V_ip6_use_defzone)) != 0) {
 1346                 return (error);
 1347         }
 1348         if (IN6_IS_ADDR_V4MAPPED(&addrs[0].sin6_addr)) {
 1349 #ifdef INET
 1350                 if (IN6_IS_ADDR_V4MAPPED(&addrs[1].sin6_addr))
 1351                         mapped = 1;
 1352                 else
 1353 #endif
 1354                         return (EINVAL);
 1355         }
 1356 
 1357 #ifdef INET
 1358         if (mapped == 1)
 1359                 inp = in_pcblookup(&V_tcbinfo,
 1360                         *(struct in_addr *)&addrs[1].sin6_addr.s6_addr[12],
 1361                         addrs[1].sin6_port,
 1362                         *(struct in_addr *)&addrs[0].sin6_addr.s6_addr[12],
 1363                         addrs[0].sin6_port, INPLOOKUP_RLOCKPCB, NULL);
 1364         else
 1365 #endif
 1366                 inp = in6_pcblookup(&V_tcbinfo,
 1367                         &addrs[1].sin6_addr, addrs[1].sin6_port,
 1368                         &addrs[0].sin6_addr, addrs[0].sin6_port,
 1369                         INPLOOKUP_RLOCKPCB, NULL);
 1370         if (inp != NULL) {
 1371                 if (inp->inp_socket == NULL)
 1372                         error = ENOENT;
 1373                 if (error == 0)
 1374                         error = cr_canseeinpcb(req->td->td_ucred, inp);
 1375                 if (error == 0)
 1376                         cru2x(inp->inp_cred, &xuc);
 1377                 INP_RUNLOCK(inp);
 1378         } else
 1379                 error = ENOENT;
 1380         if (error == 0)
 1381                 error = SYSCTL_OUT(req, &xuc, sizeof(struct xucred));
 1382         return (error);
 1383 }
 1384 
 1385 SYSCTL_PROC(_net_inet6_tcp6, OID_AUTO, getcred,
 1386     CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_PRISON, 0, 0,
 1387     tcp6_getcred, "S,xucred", "Get the xucred of a TCP6 connection");
 1388 #endif /* INET6 */
 1389 
 1390 
 1391 #ifdef INET
 1392 void
 1393 tcp_ctlinput(int cmd, struct sockaddr *sa, void *vip)
 1394 {
 1395         struct ip *ip = vip;
 1396         struct tcphdr *th;
 1397         struct in_addr faddr;
 1398         struct inpcb *inp;
 1399         struct tcpcb *tp;
 1400         struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify;
 1401         struct icmp *icp;
 1402         struct in_conninfo inc;
 1403         tcp_seq icmp_tcp_seq;
 1404         int mtu;
 1405 
 1406         faddr = ((struct sockaddr_in *)sa)->sin_addr;
 1407         if (sa->sa_family != AF_INET || faddr.s_addr == INADDR_ANY)
 1408                 return;
 1409 
 1410         if (cmd == PRC_MSGSIZE)
 1411                 notify = tcp_mtudisc_notify;
 1412         else if (V_icmp_may_rst && (cmd == PRC_UNREACH_ADMIN_PROHIB ||
 1413                 cmd == PRC_UNREACH_PORT || cmd == PRC_TIMXCEED_INTRANS) && ip)
 1414                 notify = tcp_drop_syn_sent;
 1415         /*
 1416          * Redirects don't need to be handled up here.
 1417          */
 1418         else if (PRC_IS_REDIRECT(cmd))
 1419                 return;
 1420         /*
 1421          * Source quench is depreciated.
 1422          */
 1423         else if (cmd == PRC_QUENCH)
 1424                 return;
 1425         /*
 1426          * Hostdead is ugly because it goes linearly through all PCBs.
 1427          * XXX: We never get this from ICMP, otherwise it makes an
 1428          * excellent DoS attack on machines with many connections.
 1429          */
 1430         else if (cmd == PRC_HOSTDEAD)
 1431                 ip = NULL;
 1432         else if ((unsigned)cmd >= PRC_NCMDS || inetctlerrmap[cmd] == 0)
 1433                 return;
 1434         if (ip != NULL) {
 1435                 icp = (struct icmp *)((caddr_t)ip
 1436                                       - offsetof(struct icmp, icmp_ip));
 1437                 th = (struct tcphdr *)((caddr_t)ip
 1438                                        + (ip->ip_hl << 2));
 1439                 INP_INFO_WLOCK(&V_tcbinfo);
 1440                 inp = in_pcblookup(&V_tcbinfo, faddr, th->th_dport,
 1441                     ip->ip_src, th->th_sport, INPLOOKUP_WLOCKPCB, NULL);
 1442                 if (inp != NULL)  {
 1443                         if (!(inp->inp_flags & INP_TIMEWAIT) &&
 1444                             !(inp->inp_flags & INP_DROPPED) &&
 1445                             !(inp->inp_socket == NULL)) {
 1446                                 icmp_tcp_seq = htonl(th->th_seq);
 1447                                 tp = intotcpcb(inp);
 1448                                 if (SEQ_GEQ(icmp_tcp_seq, tp->snd_una) &&
 1449                                     SEQ_LT(icmp_tcp_seq, tp->snd_max)) {
 1450                                         if (cmd == PRC_MSGSIZE) {
 1451                                             /*
 1452                                              * MTU discovery:
 1453                                              * If we got a needfrag set the MTU
 1454                                              * in the route to the suggested new
 1455                                              * value (if given) and then notify.
 1456                                              */
 1457                                             bzero(&inc, sizeof(inc));
 1458                                             inc.inc_faddr = faddr;
 1459                                             inc.inc_fibnum =
 1460                                                 inp->inp_inc.inc_fibnum;
 1461 
 1462                                             mtu = ntohs(icp->icmp_nextmtu);
 1463                                             /*
 1464                                              * If no alternative MTU was
 1465                                              * proposed, try the next smaller
 1466                                              * one.
 1467                                              */
 1468                                             if (!mtu)
 1469                                                 mtu = ip_next_mtu(
 1470                                                  ntohs(ip->ip_len), 1);
 1471                                             if (mtu < V_tcp_minmss
 1472                                                  + sizeof(struct tcpiphdr))
 1473                                                 mtu = V_tcp_minmss
 1474                                                  + sizeof(struct tcpiphdr);
 1475                                             /*
 1476                                              * Only cache the MTU if it
 1477                                              * is smaller than the interface
 1478                                              * or route MTU.  tcp_mtudisc()
 1479                                              * will do right thing by itself.
 1480                                              */
 1481                                             if (mtu <= tcp_maxmtu(&inc, NULL))
 1482                                                 tcp_hc_updatemtu(&inc, mtu);
 1483                                             tcp_mtudisc(inp, mtu);
 1484                                         } else
 1485                                                 inp = (*notify)(inp,
 1486                                                     inetctlerrmap[cmd]);
 1487                                 }
 1488                         }
 1489                         if (inp != NULL)
 1490                                 INP_WUNLOCK(inp);
 1491                 } else {
 1492                         bzero(&inc, sizeof(inc));
 1493                         inc.inc_fport = th->th_dport;
 1494                         inc.inc_lport = th->th_sport;
 1495                         inc.inc_faddr = faddr;
 1496                         inc.inc_laddr = ip->ip_src;
 1497                         syncache_unreach(&inc, th);
 1498                 }
 1499                 INP_INFO_WUNLOCK(&V_tcbinfo);
 1500         } else
 1501                 in_pcbnotifyall(&V_tcbinfo, faddr, inetctlerrmap[cmd], notify);
 1502 }
 1503 #endif /* INET */
 1504 
 1505 #ifdef INET6
 1506 void
 1507 tcp6_ctlinput(int cmd, struct sockaddr *sa, void *d)
 1508 {
 1509         struct tcphdr th;
 1510         struct inpcb *(*notify)(struct inpcb *, int) = tcp_notify;
 1511         struct ip6_hdr *ip6;
 1512         struct mbuf *m;
 1513         struct ip6ctlparam *ip6cp = NULL;
 1514         const struct sockaddr_in6 *sa6_src = NULL;
 1515         int off;
 1516         struct tcp_portonly {
 1517                 u_int16_t th_sport;
 1518                 u_int16_t th_dport;
 1519         } *thp;
 1520 
 1521         if (sa->sa_family != AF_INET6 ||
 1522             sa->sa_len != sizeof(struct sockaddr_in6))
 1523                 return;
 1524 
 1525         if (cmd == PRC_MSGSIZE)
 1526                 notify = tcp_mtudisc_notify;
 1527         else if (!PRC_IS_REDIRECT(cmd) &&
 1528                  ((unsigned)cmd >= PRC_NCMDS || inet6ctlerrmap[cmd] == 0))
 1529                 return;
 1530         /* Source quench is depreciated. */
 1531         else if (cmd == PRC_QUENCH)
 1532                 return;
 1533 
 1534         /* if the parameter is from icmp6, decode it. */
 1535         if (d != NULL) {
 1536                 ip6cp = (struct ip6ctlparam *)d;
 1537                 m = ip6cp->ip6c_m;
 1538                 ip6 = ip6cp->ip6c_ip6;
 1539                 off = ip6cp->ip6c_off;
 1540                 sa6_src = ip6cp->ip6c_src;
 1541         } else {
 1542                 m = NULL;
 1543                 ip6 = NULL;
 1544                 off = 0;        /* fool gcc */
 1545                 sa6_src = &sa6_any;
 1546         }
 1547 
 1548         if (ip6 != NULL) {
 1549                 struct in_conninfo inc;
 1550                 /*
 1551                  * XXX: We assume that when IPV6 is non NULL,
 1552                  * M and OFF are valid.
 1553                  */
 1554 
 1555                 /* check if we can safely examine src and dst ports */
 1556                 if (m->m_pkthdr.len < off + sizeof(*thp))
 1557                         return;
 1558 
 1559                 bzero(&th, sizeof(th));
 1560                 m_copydata(m, off, sizeof(*thp), (caddr_t)&th);
 1561 
 1562                 in6_pcbnotify(&V_tcbinfo, sa, th.th_dport,
 1563                     (struct sockaddr *)ip6cp->ip6c_src,
 1564                     th.th_sport, cmd, NULL, notify);
 1565 
 1566                 bzero(&inc, sizeof(inc));
 1567                 inc.inc_fport = th.th_dport;
 1568                 inc.inc_lport = th.th_sport;
 1569                 inc.inc6_faddr = ((struct sockaddr_in6 *)sa)->sin6_addr;
 1570                 inc.inc6_laddr = ip6cp->ip6c_src->sin6_addr;
 1571                 inc.inc_flags |= INC_ISIPV6;
 1572                 INP_INFO_WLOCK(&V_tcbinfo);
 1573                 syncache_unreach(&inc, &th);
 1574                 INP_INFO_WUNLOCK(&V_tcbinfo);
 1575         } else
 1576                 in6_pcbnotify(&V_tcbinfo, sa, 0, (const struct sockaddr *)sa6_src,
 1577                               0, cmd, NULL, notify);
 1578 }
 1579 #endif /* INET6 */
 1580 
 1581 
 1582 /*
 1583  * Following is where TCP initial sequence number generation occurs.
 1584  *
 1585  * There are two places where we must use initial sequence numbers:
 1586  * 1.  In SYN-ACK packets.
 1587  * 2.  In SYN packets.
 1588  *
 1589  * All ISNs for SYN-ACK packets are generated by the syncache.  See
 1590  * tcp_syncache.c for details.
 1591  *
 1592  * The ISNs in SYN packets must be monotonic; TIME_WAIT recycling
 1593  * depends on this property.  In addition, these ISNs should be
 1594  * unguessable so as to prevent connection hijacking.  To satisfy
 1595  * the requirements of this situation, the algorithm outlined in
 1596  * RFC 1948 is used, with only small modifications.
 1597  *
 1598  * Implementation details:
 1599  *
 1600  * Time is based off the system timer, and is corrected so that it
 1601  * increases by one megabyte per second.  This allows for proper
 1602  * recycling on high speed LANs while still leaving over an hour
 1603  * before rollover.
 1604  *
 1605  * As reading the *exact* system time is too expensive to be done
 1606  * whenever setting up a TCP connection, we increment the time
 1607  * offset in two ways.  First, a small random positive increment
 1608  * is added to isn_offset for each connection that is set up.
 1609  * Second, the function tcp_isn_tick fires once per clock tick
 1610  * and increments isn_offset as necessary so that sequence numbers
 1611  * are incremented at approximately ISN_BYTES_PER_SECOND.  The
 1612  * random positive increments serve only to ensure that the same
 1613  * exact sequence number is never sent out twice (as could otherwise
 1614  * happen when a port is recycled in less than the system tick
 1615  * interval.)
 1616  *
 1617  * net.inet.tcp.isn_reseed_interval controls the number of seconds
 1618  * between seeding of isn_secret.  This is normally set to zero,
 1619  * as reseeding should not be necessary.
 1620  *
 1621  * Locking of the global variables isn_secret, isn_last_reseed, isn_offset,
 1622  * isn_offset_old, and isn_ctx is performed using the TCP pcbinfo lock.  In
 1623  * general, this means holding an exclusive (write) lock.
 1624  */
 1625 
 1626 #define ISN_BYTES_PER_SECOND 1048576
 1627 #define ISN_STATIC_INCREMENT 4096
 1628 #define ISN_RANDOM_INCREMENT (4096 - 1)
 1629 
 1630 static VNET_DEFINE(u_char, isn_secret[32]);
 1631 static VNET_DEFINE(int, isn_last);
 1632 static VNET_DEFINE(int, isn_last_reseed);
 1633 static VNET_DEFINE(u_int32_t, isn_offset);
 1634 static VNET_DEFINE(u_int32_t, isn_offset_old);
 1635 
 1636 #define V_isn_secret                    VNET(isn_secret)
 1637 #define V_isn_last                      VNET(isn_last)
 1638 #define V_isn_last_reseed               VNET(isn_last_reseed)
 1639 #define V_isn_offset                    VNET(isn_offset)
 1640 #define V_isn_offset_old                VNET(isn_offset_old)
 1641 
 1642 tcp_seq
 1643 tcp_new_isn(struct tcpcb *tp)
 1644 {
 1645         MD5_CTX isn_ctx;
 1646         u_int32_t md5_buffer[4];
 1647         tcp_seq new_isn;
 1648         u_int32_t projected_offset;
 1649 
 1650         INP_WLOCK_ASSERT(tp->t_inpcb);
 1651 
 1652         ISN_LOCK();
 1653         /* Seed if this is the first use, reseed if requested. */
 1654         if ((V_isn_last_reseed == 0) || ((V_tcp_isn_reseed_interval > 0) &&
 1655              (((u_int)V_isn_last_reseed + (u_int)V_tcp_isn_reseed_interval*hz)
 1656                 < (u_int)ticks))) {
 1657                 read_random(&V_isn_secret, sizeof(V_isn_secret));
 1658                 V_isn_last_reseed = ticks;
 1659         }
 1660 
 1661         /* Compute the md5 hash and return the ISN. */
 1662         MD5Init(&isn_ctx);
 1663         MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_fport, sizeof(u_short));
 1664         MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_lport, sizeof(u_short));
 1665 #ifdef INET6
 1666         if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) {
 1667                 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_faddr,
 1668                           sizeof(struct in6_addr));
 1669                 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->in6p_laddr,
 1670                           sizeof(struct in6_addr));
 1671         } else
 1672 #endif
 1673         {
 1674                 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_faddr,
 1675                           sizeof(struct in_addr));
 1676                 MD5Update(&isn_ctx, (u_char *) &tp->t_inpcb->inp_laddr,
 1677                           sizeof(struct in_addr));
 1678         }
 1679         MD5Update(&isn_ctx, (u_char *) &V_isn_secret, sizeof(V_isn_secret));
 1680         MD5Final((u_char *) &md5_buffer, &isn_ctx);
 1681         new_isn = (tcp_seq) md5_buffer[0];
 1682         V_isn_offset += ISN_STATIC_INCREMENT +
 1683                 (arc4random() & ISN_RANDOM_INCREMENT);
 1684         if (ticks != V_isn_last) {
 1685                 projected_offset = V_isn_offset_old +
 1686                     ISN_BYTES_PER_SECOND / hz * (ticks - V_isn_last);
 1687                 if (SEQ_GT(projected_offset, V_isn_offset))
 1688                         V_isn_offset = projected_offset;
 1689                 V_isn_offset_old = V_isn_offset;
 1690                 V_isn_last = ticks;
 1691         }
 1692         new_isn += V_isn_offset;
 1693         ISN_UNLOCK();
 1694         return (new_isn);
 1695 }
 1696 
 1697 /*
 1698  * When a specific ICMP unreachable message is received and the
 1699  * connection state is SYN-SENT, drop the connection.  This behavior
 1700  * is controlled by the icmp_may_rst sysctl.
 1701  */
 1702 struct inpcb *
 1703 tcp_drop_syn_sent(struct inpcb *inp, int errno)
 1704 {
 1705         struct tcpcb *tp;
 1706 
 1707         INP_INFO_WLOCK_ASSERT(&V_tcbinfo);
 1708         INP_WLOCK_ASSERT(inp);
 1709 
 1710         if ((inp->inp_flags & INP_TIMEWAIT) ||
 1711             (inp->inp_flags & INP_DROPPED))
 1712                 return (inp);
 1713 
 1714         tp = intotcpcb(inp);
 1715         if (tp->t_state != TCPS_SYN_SENT)
 1716                 return (inp);
 1717 
 1718         tp = tcp_drop(tp, errno);
 1719         if (tp != NULL)
 1720                 return (inp);
 1721         else
 1722                 return (NULL);
 1723 }
 1724 
 1725 /*
 1726  * When `need fragmentation' ICMP is received, update our idea of the MSS
 1727  * based on the new value. Also nudge TCP to send something, since we
 1728  * know the packet we just sent was dropped.
 1729  * This duplicates some code in the tcp_mss() function in tcp_input.c.
 1730  */
 1731 static struct inpcb *
 1732 tcp_mtudisc_notify(struct inpcb *inp, int error)
 1733 {
 1734 
 1735         return (tcp_mtudisc(inp, -1));
 1736 }
 1737 
 1738 struct inpcb *
 1739 tcp_mtudisc(struct inpcb *inp, int mtuoffer)
 1740 {
 1741         struct tcpcb *tp;
 1742         struct socket *so;
 1743 
 1744         INP_WLOCK_ASSERT(inp);
 1745         if ((inp->inp_flags & INP_TIMEWAIT) ||
 1746             (inp->inp_flags & INP_DROPPED))
 1747                 return (inp);
 1748 
 1749         tp = intotcpcb(inp);
 1750         KASSERT(tp != NULL, ("tcp_mtudisc: tp == NULL"));
 1751 
 1752         tcp_mss_update(tp, -1, mtuoffer, NULL, NULL);
 1753   
 1754         so = inp->inp_socket;
 1755         SOCKBUF_LOCK(&so->so_snd);
 1756         /* If the mss is larger than the socket buffer, decrease the mss. */
 1757         if (so->so_snd.sb_hiwat < tp->t_maxseg)
 1758                 tp->t_maxseg = so->so_snd.sb_hiwat;
 1759         SOCKBUF_UNLOCK(&so->so_snd);
 1760 
 1761         TCPSTAT_INC(tcps_mturesent);
 1762         tp->t_rtttime = 0;
 1763         tp->snd_nxt = tp->snd_una;
 1764         tcp_free_sackholes(tp);
 1765         tp->snd_recover = tp->snd_max;
 1766         if (tp->t_flags & TF_SACK_PERMIT)
 1767                 EXIT_FASTRECOVERY(tp->t_flags);
 1768         tcp_output(tp);
 1769         return (inp);
 1770 }
 1771 
 1772 #ifdef INET
 1773 /*
 1774  * Look-up the routing entry to the peer of this inpcb.  If no route
 1775  * is found and it cannot be allocated, then return 0.  This routine
 1776  * is called by TCP routines that access the rmx structure and by
 1777  * tcp_mss_update to get the peer/interface MTU.
 1778  */
 1779 u_long
 1780 tcp_maxmtu(struct in_conninfo *inc, struct tcp_ifcap *cap)
 1781 {
 1782         struct route sro;
 1783         struct sockaddr_in *dst;
 1784         struct ifnet *ifp;
 1785         u_long maxmtu = 0;
 1786 
 1787         KASSERT(inc != NULL, ("tcp_maxmtu with NULL in_conninfo pointer"));
 1788 
 1789         bzero(&sro, sizeof(sro));
 1790         if (inc->inc_faddr.s_addr != INADDR_ANY) {
 1791                 dst = (struct sockaddr_in *)&sro.ro_dst;
 1792                 dst->sin_family = AF_INET;
 1793                 dst->sin_len = sizeof(*dst);
 1794                 dst->sin_addr = inc->inc_faddr;
 1795                 in_rtalloc_ign(&sro, 0, inc->inc_fibnum);
 1796         }
 1797         if (sro.ro_rt != NULL) {
 1798                 ifp = sro.ro_rt->rt_ifp;
 1799                 if (sro.ro_rt->rt_rmx.rmx_mtu == 0)
 1800                         maxmtu = ifp->if_mtu;
 1801                 else
 1802                         maxmtu = min(sro.ro_rt->rt_rmx.rmx_mtu, ifp->if_mtu);
 1803 
 1804                 /* Report additional interface capabilities. */
 1805                 if (cap != NULL) {
 1806                         if (ifp->if_capenable & IFCAP_TSO4 &&
 1807                             ifp->if_hwassist & CSUM_TSO)
 1808                                 cap->ifcap |= CSUM_TSO;
 1809                                 cap->tsomax = ifp->if_hw_tsomax;
 1810                 }
 1811                 RTFREE(sro.ro_rt);
 1812         }
 1813         return (maxmtu);
 1814 }
 1815 #endif /* INET */
 1816 
 1817 #ifdef INET6
 1818 u_long
 1819 tcp_maxmtu6(struct in_conninfo *inc, struct tcp_ifcap *cap)
 1820 {
 1821         struct route_in6 sro6;
 1822         struct ifnet *ifp;
 1823         u_long maxmtu = 0;
 1824 
 1825         KASSERT(inc != NULL, ("tcp_maxmtu6 with NULL in_conninfo pointer"));
 1826 
 1827         bzero(&sro6, sizeof(sro6));
 1828         if (!IN6_IS_ADDR_UNSPECIFIED(&inc->inc6_faddr)) {
 1829                 sro6.ro_dst.sin6_family = AF_INET6;
 1830                 sro6.ro_dst.sin6_len = sizeof(struct sockaddr_in6);
 1831                 sro6.ro_dst.sin6_addr = inc->inc6_faddr;
 1832                 in6_rtalloc_ign(&sro6, 0, inc->inc_fibnum);
 1833         }
 1834         if (sro6.ro_rt != NULL) {
 1835                 ifp = sro6.ro_rt->rt_ifp;
 1836                 if (sro6.ro_rt->rt_rmx.rmx_mtu == 0)
 1837                         maxmtu = IN6_LINKMTU(sro6.ro_rt->rt_ifp);
 1838                 else
 1839                         maxmtu = min(sro6.ro_rt->rt_rmx.rmx_mtu,
 1840                                      IN6_LINKMTU(sro6.ro_rt->rt_ifp));
 1841 
 1842                 /* Report additional interface capabilities. */
 1843                 if (cap != NULL) {
 1844                         if (ifp->if_capenable & IFCAP_TSO6 &&
 1845                             ifp->if_hwassist & CSUM_TSO)
 1846                                 cap->ifcap |= CSUM_TSO;
 1847                                 cap->tsomax = ifp->if_hw_tsomax;
 1848                 }
 1849                 RTFREE(sro6.ro_rt);
 1850         }
 1851 
 1852         return (maxmtu);
 1853 }
 1854 #endif /* INET6 */
 1855 
 1856 #ifdef IPSEC
 1857 /* compute ESP/AH header size for TCP, including outer IP header. */
 1858 size_t
 1859 ipsec_hdrsiz_tcp(struct tcpcb *tp)
 1860 {
 1861         struct inpcb *inp;
 1862         struct mbuf *m;
 1863         size_t hdrsiz;
 1864         struct ip *ip;
 1865 #ifdef INET6
 1866         struct ip6_hdr *ip6;
 1867 #endif
 1868         struct tcphdr *th;
 1869 
 1870         if ((tp == NULL) || ((inp = tp->t_inpcb) == NULL))
 1871                 return (0);
 1872         m = m_gethdr(M_NOWAIT, MT_DATA);
 1873         if (!m)
 1874                 return (0);
 1875 
 1876 #ifdef INET6
 1877         if ((inp->inp_vflag & INP_IPV6) != 0) {
 1878                 ip6 = mtod(m, struct ip6_hdr *);
 1879                 th = (struct tcphdr *)(ip6 + 1);
 1880                 m->m_pkthdr.len = m->m_len =
 1881                         sizeof(struct ip6_hdr) + sizeof(struct tcphdr);
 1882                 tcpip_fillheaders(inp, ip6, th);
 1883                 hdrsiz = ipsec_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp);
 1884         } else
 1885 #endif /* INET6 */
 1886         {
 1887                 ip = mtod(m, struct ip *);
 1888                 th = (struct tcphdr *)(ip + 1);
 1889                 m->m_pkthdr.len = m->m_len = sizeof(struct tcpiphdr);
 1890                 tcpip_fillheaders(inp, ip, th);
 1891                 hdrsiz = ipsec_hdrsiz(m, IPSEC_DIR_OUTBOUND, inp);
 1892         }
 1893 
 1894         m_free(m);
 1895         return (hdrsiz);
 1896 }
 1897 #endif /* IPSEC */
 1898 
 1899 #ifdef TCP_SIGNATURE
 1900 /*
 1901  * Callback function invoked by m_apply() to digest TCP segment data
 1902  * contained within an mbuf chain.
 1903  */
 1904 static int
 1905 tcp_signature_apply(void *fstate, void *data, u_int len)
 1906 {
 1907 
 1908         MD5Update(fstate, (u_char *)data, len);
 1909         return (0);
 1910 }
 1911 
 1912 /*
 1913  * Compute TCP-MD5 hash of a TCP segment. (RFC2385)
 1914  *
 1915  * Parameters:
 1916  * m            pointer to head of mbuf chain
 1917  * _unused      
 1918  * len          length of TCP segment data, excluding options
 1919  * optlen       length of TCP segment options
 1920  * buf          pointer to storage for computed MD5 digest
 1921  * direction    direction of flow (IPSEC_DIR_INBOUND or OUTBOUND)
 1922  *
 1923  * We do this over ip, tcphdr, segment data, and the key in the SADB.
 1924  * When called from tcp_input(), we can be sure that th_sum has been
 1925  * zeroed out and verified already.
 1926  *
 1927  * Return 0 if successful, otherwise return -1.
 1928  *
 1929  * XXX The key is retrieved from the system's PF_KEY SADB, by keying a
 1930  * search with the destination IP address, and a 'magic SPI' to be
 1931  * determined by the application. This is hardcoded elsewhere to 1179
 1932  * right now. Another branch of this code exists which uses the SPD to
 1933  * specify per-application flows but it is unstable.
 1934  */
 1935 int
 1936 tcp_signature_compute(struct mbuf *m, int _unused, int len, int optlen,
 1937     u_char *buf, u_int direction)
 1938 {
 1939         union sockaddr_union dst;
 1940 #ifdef INET
 1941         struct ippseudo ippseudo;
 1942 #endif
 1943         MD5_CTX ctx;
 1944         int doff;
 1945         struct ip *ip;
 1946 #ifdef INET
 1947         struct ipovly *ipovly;
 1948 #endif
 1949         struct secasvar *sav;
 1950         struct tcphdr *th;
 1951 #ifdef INET6
 1952         struct ip6_hdr *ip6;
 1953         struct in6_addr in6;
 1954         char ip6buf[INET6_ADDRSTRLEN];
 1955         uint32_t plen;
 1956         uint16_t nhdr;
 1957 #endif
 1958         u_short savecsum;
 1959 
 1960         KASSERT(m != NULL, ("NULL mbuf chain"));
 1961         KASSERT(buf != NULL, ("NULL signature pointer"));
 1962 
 1963         /* Extract the destination from the IP header in the mbuf. */
 1964         bzero(&dst, sizeof(union sockaddr_union));
 1965         ip = mtod(m, struct ip *);
 1966 #ifdef INET6
 1967         ip6 = NULL;     /* Make the compiler happy. */
 1968 #endif
 1969         switch (ip->ip_v) {
 1970 #ifdef INET
 1971         case IPVERSION:
 1972                 dst.sa.sa_len = sizeof(struct sockaddr_in);
 1973                 dst.sa.sa_family = AF_INET;
 1974                 dst.sin.sin_addr = (direction == IPSEC_DIR_INBOUND) ?
 1975                     ip->ip_src : ip->ip_dst;
 1976                 break;
 1977 #endif
 1978 #ifdef INET6
 1979         case (IPV6_VERSION >> 4):
 1980                 ip6 = mtod(m, struct ip6_hdr *);
 1981                 dst.sa.sa_len = sizeof(struct sockaddr_in6);
 1982                 dst.sa.sa_family = AF_INET6;
 1983                 dst.sin6.sin6_addr = (direction == IPSEC_DIR_INBOUND) ?
 1984                     ip6->ip6_src : ip6->ip6_dst;
 1985                 break;
 1986 #endif
 1987         default:
 1988                 return (EINVAL);
 1989                 /* NOTREACHED */
 1990                 break;
 1991         }
 1992 
 1993         /* Look up an SADB entry which matches the address of the peer. */
 1994         sav = KEY_ALLOCSA(&dst, IPPROTO_TCP, htonl(TCP_SIG_SPI));
 1995         if (sav == NULL) {
 1996                 ipseclog((LOG_ERR, "%s: SADB lookup failed for %s\n", __func__,
 1997                     (ip->ip_v == IPVERSION) ? inet_ntoa(dst.sin.sin_addr) :
 1998 #ifdef INET6
 1999                         (ip->ip_v == (IPV6_VERSION >> 4)) ?
 2000                             ip6_sprintf(ip6buf, &dst.sin6.sin6_addr) :
 2001 #endif
 2002                         "(unsupported)"));
 2003                 return (EINVAL);
 2004         }
 2005 
 2006         MD5Init(&ctx);
 2007         /*
 2008          * Step 1: Update MD5 hash with IP(v6) pseudo-header.
 2009          *
 2010          * XXX The ippseudo header MUST be digested in network byte order,
 2011          * or else we'll fail the regression test. Assume all fields we've
 2012          * been doing arithmetic on have been in host byte order.
 2013          * XXX One cannot depend on ipovly->ih_len here. When called from
 2014          * tcp_output(), the underlying ip_len member has not yet been set.
 2015          */
 2016         switch (ip->ip_v) {
 2017 #ifdef INET
 2018         case IPVERSION:
 2019                 ipovly = (struct ipovly *)ip;
 2020                 ippseudo.ippseudo_src = ipovly->ih_src;
 2021                 ippseudo.ippseudo_dst = ipovly->ih_dst;
 2022                 ippseudo.ippseudo_pad = 0;
 2023                 ippseudo.ippseudo_p = IPPROTO_TCP;
 2024                 ippseudo.ippseudo_len = htons(len + sizeof(struct tcphdr) +
 2025                     optlen);
 2026                 MD5Update(&ctx, (char *)&ippseudo, sizeof(struct ippseudo));
 2027 
 2028                 th = (struct tcphdr *)((u_char *)ip + sizeof(struct ip));
 2029                 doff = sizeof(struct ip) + sizeof(struct tcphdr) + optlen;
 2030                 break;
 2031 #endif
 2032 #ifdef INET6
 2033         /*
 2034          * RFC 2385, 2.0  Proposal
 2035          * For IPv6, the pseudo-header is as described in RFC 2460, namely the
 2036          * 128-bit source IPv6 address, 128-bit destination IPv6 address, zero-
 2037          * extended next header value (to form 32 bits), and 32-bit segment
 2038          * length.
 2039          * Note: Upper-Layer Packet Length comes before Next Header.
 2040          */
 2041         case (IPV6_VERSION >> 4):
 2042                 in6 = ip6->ip6_src;
 2043                 in6_clearscope(&in6);
 2044                 MD5Update(&ctx, (char *)&in6, sizeof(struct in6_addr));
 2045                 in6 = ip6->ip6_dst;
 2046                 in6_clearscope(&in6);
 2047                 MD5Update(&ctx, (char *)&in6, sizeof(struct in6_addr));
 2048                 plen = htonl(len + sizeof(struct tcphdr) + optlen);
 2049                 MD5Update(&ctx, (char *)&plen, sizeof(uint32_t));
 2050                 nhdr = 0;
 2051                 MD5Update(&ctx, (char *)&nhdr, sizeof(uint8_t));
 2052                 MD5Update(&ctx, (char *)&nhdr, sizeof(uint8_t));
 2053                 MD5Update(&ctx, (char *)&nhdr, sizeof(uint8_t));
 2054                 nhdr = IPPROTO_TCP;
 2055                 MD5Update(&ctx, (char *)&nhdr, sizeof(uint8_t));
 2056 
 2057                 th = (struct tcphdr *)((u_char *)ip6 + sizeof(struct ip6_hdr));
 2058                 doff = sizeof(struct ip6_hdr) + sizeof(struct tcphdr) + optlen;
 2059                 break;
 2060 #endif
 2061         default:
 2062                 return (EINVAL);
 2063                 /* NOTREACHED */
 2064                 break;
 2065         }
 2066 
 2067 
 2068         /*
 2069          * Step 2: Update MD5 hash with TCP header, excluding options.
 2070          * The TCP checksum must be set to zero.
 2071          */
 2072         savecsum = th->th_sum;
 2073         th->th_sum = 0;
 2074         MD5Update(&ctx, (char *)th, sizeof(struct tcphdr));
 2075         th->th_sum = savecsum;
 2076 
 2077         /*
 2078          * Step 3: Update MD5 hash with TCP segment data.
 2079          *         Use m_apply() to avoid an early m_pullup().
 2080          */
 2081         if (len > 0)
 2082                 m_apply(m, doff, len, tcp_signature_apply, &ctx);
 2083 
 2084         /*
 2085          * Step 4: Update MD5 hash with shared secret.
 2086          */
 2087         MD5Update(&ctx, sav->key_auth->key_data, _KEYLEN(sav->key_auth));
 2088         MD5Final(buf, &ctx);
 2089 
 2090         key_sa_recordxfer(sav, m);
 2091         KEY_FREESAV(&sav);
 2092         return (0);
 2093 }
 2094 
 2095 /*
 2096  * Verify the TCP-MD5 hash of a TCP segment. (RFC2385)
 2097  *
 2098  * Parameters:
 2099  * m            pointer to head of mbuf chain
 2100  * len          length of TCP segment data, excluding options
 2101  * optlen       length of TCP segment options
 2102  * buf          pointer to storage for computed MD5 digest
 2103  * direction    direction of flow (IPSEC_DIR_INBOUND or OUTBOUND)
 2104  *
 2105  * Return 1 if successful, otherwise return 0.
 2106  */
 2107 int
 2108 tcp_signature_verify(struct mbuf *m, int off0, int tlen, int optlen,
 2109     struct tcpopt *to, struct tcphdr *th, u_int tcpbflag)
 2110 {
 2111         char tmpdigest[TCP_SIGLEN];
 2112 
 2113         if (tcp_sig_checksigs == 0)
 2114                 return (1);
 2115         if ((tcpbflag & TF_SIGNATURE) == 0) {
 2116                 if ((to->to_flags & TOF_SIGNATURE) != 0) {
 2117 
 2118                         /*
 2119                          * If this socket is not expecting signature but
 2120                          * the segment contains signature just fail.
 2121                          */
 2122                         TCPSTAT_INC(tcps_sig_err_sigopt);
 2123                         TCPSTAT_INC(tcps_sig_rcvbadsig);
 2124                         return (0);
 2125                 }
 2126 
 2127                 /* Signature is not expected, and not present in segment. */
 2128                 return (1);
 2129         }
 2130 
 2131         /*
 2132          * If this socket is expecting signature but the segment does not
 2133          * contain any just fail.
 2134          */
 2135         if ((to->to_flags & TOF_SIGNATURE) == 0) {
 2136                 TCPSTAT_INC(tcps_sig_err_nosigopt);
 2137                 TCPSTAT_INC(tcps_sig_rcvbadsig);
 2138                 return (0);
 2139         }
 2140         if (tcp_signature_compute(m, off0, tlen, optlen, &tmpdigest[0],
 2141             IPSEC_DIR_INBOUND) == -1) {
 2142                 TCPSTAT_INC(tcps_sig_err_buildsig);
 2143                 TCPSTAT_INC(tcps_sig_rcvbadsig);
 2144                 return (0);
 2145         }
 2146         
 2147         if (bcmp(to->to_signature, &tmpdigest[0], TCP_SIGLEN) != 0) {
 2148                 TCPSTAT_INC(tcps_sig_rcvbadsig);
 2149                 return (0);
 2150         }
 2151         TCPSTAT_INC(tcps_sig_rcvgoodsig);
 2152         return (1);
 2153 }
 2154 #endif /* TCP_SIGNATURE */
 2155 
 2156 static int
 2157 sysctl_drop(SYSCTL_HANDLER_ARGS)
 2158 {
 2159         /* addrs[0] is a foreign socket, addrs[1] is a local one. */
 2160         struct sockaddr_storage addrs[2];
 2161         struct inpcb *inp;
 2162         struct tcpcb *tp;
 2163         struct tcptw *tw;
 2164         struct sockaddr_in *fin, *lin;
 2165 #ifdef INET6
 2166         struct sockaddr_in6 *fin6, *lin6;
 2167 #endif
 2168         int error;
 2169 
 2170         inp = NULL;
 2171         fin = lin = NULL;
 2172 #ifdef INET6
 2173         fin6 = lin6 = NULL;
 2174 #endif
 2175         error = 0;
 2176 
 2177         if (req->oldptr != NULL || req->oldlen != 0)
 2178                 return (EINVAL);
 2179         if (req->newptr == NULL)
 2180                 return (EPERM);
 2181         if (req->newlen < sizeof(addrs))
 2182                 return (ENOMEM);
 2183         error = SYSCTL_IN(req, &addrs, sizeof(addrs));
 2184         if (error)
 2185                 return (error);
 2186 
 2187         switch (addrs[0].ss_family) {
 2188 #ifdef INET6
 2189         case AF_INET6:
 2190                 fin6 = (struct sockaddr_in6 *)&addrs[0];
 2191                 lin6 = (struct sockaddr_in6 *)&addrs[1];
 2192                 if (fin6->sin6_len != sizeof(struct sockaddr_in6) ||
 2193                     lin6->sin6_len != sizeof(struct sockaddr_in6))
 2194                         return (EINVAL);
 2195                 if (IN6_IS_ADDR_V4MAPPED(&fin6->sin6_addr)) {
 2196                         if (!IN6_IS_ADDR_V4MAPPED(&lin6->sin6_addr))
 2197                                 return (EINVAL);
 2198                         in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[0]);
 2199                         in6_sin6_2_sin_in_sock((struct sockaddr *)&addrs[1]);
 2200                         fin = (struct sockaddr_in *)&addrs[0];
 2201                         lin = (struct sockaddr_in *)&addrs[1];
 2202                         break;
 2203                 }
 2204                 error = sa6_embedscope(fin6, V_ip6_use_defzone);
 2205                 if (error)
 2206                         return (error);
 2207                 error = sa6_embedscope(lin6, V_ip6_use_defzone);
 2208                 if (error)
 2209                         return (error);
 2210                 break;
 2211 #endif
 2212 #ifdef INET
 2213         case AF_INET:
 2214                 fin = (struct sockaddr_in *)&addrs[0];
 2215                 lin = (struct sockaddr_in *)&addrs[1];
 2216                 if (fin->sin_len != sizeof(struct sockaddr_in) ||
 2217                     lin->sin_len != sizeof(struct sockaddr_in))
 2218                         return (EINVAL);
 2219                 break;
 2220 #endif
 2221         default:
 2222                 return (EINVAL);
 2223         }
 2224         INP_INFO_WLOCK(&V_tcbinfo);
 2225         switch (addrs[0].ss_family) {
 2226 #ifdef INET6
 2227         case AF_INET6:
 2228                 inp = in6_pcblookup(&V_tcbinfo, &fin6->sin6_addr,
 2229                     fin6->sin6_port, &lin6->sin6_addr, lin6->sin6_port,
 2230                     INPLOOKUP_WLOCKPCB, NULL);
 2231                 break;
 2232 #endif
 2233 #ifdef INET
 2234         case AF_INET:
 2235                 inp = in_pcblookup(&V_tcbinfo, fin->sin_addr, fin->sin_port,
 2236                     lin->sin_addr, lin->sin_port, INPLOOKUP_WLOCKPCB, NULL);
 2237                 break;
 2238 #endif
 2239         }
 2240         if (inp != NULL) {
 2241                 if (inp->inp_flags & INP_TIMEWAIT) {
 2242                         /*
 2243                          * XXXRW: There currently exists a state where an
 2244                          * inpcb is present, but its timewait state has been
 2245                          * discarded.  For now, don't allow dropping of this
 2246                          * type of inpcb.
 2247                          */
 2248                         tw = intotw(inp);
 2249                         if (tw != NULL)
 2250                                 tcp_twclose(tw, 0);
 2251                         else
 2252                                 INP_WUNLOCK(inp);
 2253                 } else if (!(inp->inp_flags & INP_DROPPED) &&
 2254                            !(inp->inp_socket->so_options & SO_ACCEPTCONN)) {
 2255                         tp = intotcpcb(inp);
 2256                         tp = tcp_drop(tp, ECONNABORTED);
 2257                         if (tp != NULL)
 2258                                 INP_WUNLOCK(inp);
 2259                 } else
 2260                         INP_WUNLOCK(inp);
 2261         } else
 2262                 error = ESRCH;
 2263         INP_INFO_WUNLOCK(&V_tcbinfo);
 2264         return (error);
 2265 }
 2266 
 2267 SYSCTL_VNET_PROC(_net_inet_tcp, TCPCTL_DROP, drop,
 2268     CTLTYPE_STRUCT|CTLFLAG_WR|CTLFLAG_SKIP, NULL,
 2269     0, sysctl_drop, "", "Drop TCP connection");
 2270 
 2271 /*
 2272  * Generate a standardized TCP log line for use throughout the
 2273  * tcp subsystem.  Memory allocation is done with M_NOWAIT to
 2274  * allow use in the interrupt context.
 2275  *
 2276  * NB: The caller MUST free(s, M_TCPLOG) the returned string.
 2277  * NB: The function may return NULL if memory allocation failed.
 2278  *
 2279  * Due to header inclusion and ordering limitations the struct ip
 2280  * and ip6_hdr pointers have to be passed as void pointers.
 2281  */
 2282 char *
 2283 tcp_log_vain(struct in_conninfo *inc, struct tcphdr *th, void *ip4hdr,
 2284     const void *ip6hdr)
 2285 {
 2286 
 2287         /* Is logging enabled? */
 2288         if (tcp_log_in_vain == 0)
 2289                 return (NULL);
 2290 
 2291         return (tcp_log_addr(inc, th, ip4hdr, ip6hdr));
 2292 }
 2293 
 2294 char *
 2295 tcp_log_addrs(struct in_conninfo *inc, struct tcphdr *th, void *ip4hdr,
 2296     const void *ip6hdr)
 2297 {
 2298 
 2299         /* Is logging enabled? */
 2300         if (tcp_log_debug == 0)
 2301                 return (NULL);
 2302 
 2303         return (tcp_log_addr(inc, th, ip4hdr, ip6hdr));
 2304 }
 2305 
 2306 static char *
 2307 tcp_log_addr(struct in_conninfo *inc, struct tcphdr *th, void *ip4hdr,
 2308     const void *ip6hdr)
 2309 {
 2310         char *s, *sp;
 2311         size_t size;
 2312         struct ip *ip;
 2313 #ifdef INET6
 2314         const struct ip6_hdr *ip6;
 2315 
 2316         ip6 = (const struct ip6_hdr *)ip6hdr;
 2317 #endif /* INET6 */
 2318         ip = (struct ip *)ip4hdr;
 2319 
 2320         /*
 2321          * The log line looks like this:
 2322          * "TCP: [1.2.3.4]:50332 to [1.2.3.4]:80 tcpflags 0x2<SYN>"
 2323          */
 2324         size = sizeof("TCP: []:12345 to []:12345 tcpflags 0x2<>") +
 2325             sizeof(PRINT_TH_FLAGS) + 1 +
 2326 #ifdef INET6
 2327             2 * INET6_ADDRSTRLEN;
 2328 #else
 2329             2 * INET_ADDRSTRLEN;
 2330 #endif /* INET6 */
 2331 
 2332         s = malloc(size, M_TCPLOG, M_ZERO|M_NOWAIT);
 2333         if (s == NULL)
 2334                 return (NULL);
 2335 
 2336         strcat(s, "TCP: [");
 2337         sp = s + strlen(s);
 2338 
 2339         if (inc && ((inc->inc_flags & INC_ISIPV6) == 0)) {
 2340                 inet_ntoa_r(inc->inc_faddr, sp);
 2341                 sp = s + strlen(s);
 2342                 sprintf(sp, "]:%i to [", ntohs(inc->inc_fport));
 2343                 sp = s + strlen(s);
 2344                 inet_ntoa_r(inc->inc_laddr, sp);
 2345                 sp = s + strlen(s);
 2346                 sprintf(sp, "]:%i", ntohs(inc->inc_lport));
 2347 #ifdef INET6
 2348         } else if (inc) {
 2349                 ip6_sprintf(sp, &inc->inc6_faddr);
 2350                 sp = s + strlen(s);
 2351                 sprintf(sp, "]:%i to [", ntohs(inc->inc_fport));
 2352                 sp = s + strlen(s);
 2353                 ip6_sprintf(sp, &inc->inc6_laddr);
 2354                 sp = s + strlen(s);
 2355                 sprintf(sp, "]:%i", ntohs(inc->inc_lport));
 2356         } else if (ip6 && th) {
 2357                 ip6_sprintf(sp, &ip6->ip6_src);
 2358                 sp = s + strlen(s);
 2359                 sprintf(sp, "]:%i to [", ntohs(th->th_sport));
 2360                 sp = s + strlen(s);
 2361                 ip6_sprintf(sp, &ip6->ip6_dst);
 2362                 sp = s + strlen(s);
 2363                 sprintf(sp, "]:%i", ntohs(th->th_dport));
 2364 #endif /* INET6 */
 2365 #ifdef INET
 2366         } else if (ip && th) {
 2367                 inet_ntoa_r(ip->ip_src, sp);
 2368                 sp = s + strlen(s);
 2369                 sprintf(sp, "]:%i to [", ntohs(th->th_sport));
 2370                 sp = s + strlen(s);
 2371                 inet_ntoa_r(ip->ip_dst, sp);
 2372                 sp = s + strlen(s);
 2373                 sprintf(sp, "]:%i", ntohs(th->th_dport));
 2374 #endif /* INET */
 2375         } else {
 2376                 free(s, M_TCPLOG);
 2377                 return (NULL);
 2378         }
 2379         sp = s + strlen(s);
 2380         if (th)
 2381                 sprintf(sp, " tcpflags 0x%b", th->th_flags, PRINT_TH_FLAGS);
 2382         if (*(s + size - 1) != '\0')
 2383                 panic("%s: string too long", __func__);
 2384         return (s);
 2385 }
 2386 
 2387 /*
 2388  * A subroutine which makes it easy to track TCP state changes with DTrace.
 2389  * This function shouldn't be called for t_state initializations that don't
 2390  * correspond to actual TCP state transitions.
 2391  */
 2392 void
 2393 tcp_state_change(struct tcpcb *tp, int newstate)
 2394 {
 2395 #if defined(KDTRACE_HOOKS)
 2396         int pstate = tp->t_state;
 2397 #endif
 2398 
 2399         tp->t_state = newstate;
 2400         TCP_PROBE6(state_change, NULL, tp, NULL, tp, NULL, pstate);
 2401 }

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