ip_flow.c

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    1 /*      $NetBSD: ip_flow.c,v 1.56 2008/04/28 20:24:09 martin Exp $      */
    2 
    3 /*-
    4  * Copyright (c) 1998 The NetBSD Foundation, Inc.
    5  * All rights reserved.
    6  *
    7  * This code is derived from software contributed to The NetBSD Foundation
    8  * by the 3am Software Foundry ("3am").  It was developed by Matt Thomas.
    9  *
   10  * Redistribution and use in source and binary forms, with or without
   11  * modification, are permitted provided that the following conditions
   12  * are met:
   13  * 1. Redistributions of source code must retain the above copyright
   14  *    notice, this list of conditions and the following disclaimer.
   15  * 2. Redistributions in binary form must reproduce the above copyright
   16  *    notice, this list of conditions and the following disclaimer in the
   17  *    documentation and/or other materials provided with the distribution.
   18  *
   19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
   20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
   21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
   23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   29  * POSSIBILITY OF SUCH DAMAGE.
   30  */
   31 
   32 #include <sys/cdefs.h>
   33 __KERNEL_RCSID(0, "$NetBSD: ip_flow.c,v 1.56 2008/04/28 20:24:09 martin Exp $");
   34 
   35 #include <sys/param.h>
   36 #include <sys/systm.h>
   37 #include <sys/malloc.h>
   38 #include <sys/mbuf.h>
   39 #include <sys/domain.h>
   40 #include <sys/protosw.h>
   41 #include <sys/socket.h>
   42 #include <sys/socketvar.h>
   43 #include <sys/errno.h>
   44 #include <sys/time.h>
   45 #include <sys/kernel.h>
   46 #include <sys/pool.h>
   47 #include <sys/sysctl.h>
   48 
   49 #include <net/if.h>
   50 #include <net/if_dl.h>
   51 #include <net/route.h>
   52 #include <net/pfil.h>
   53 
   54 #include <netinet/in.h>
   55 #include <netinet/in_systm.h>
   56 #include <netinet/ip.h>
   57 #include <netinet/in_pcb.h>
   58 #include <netinet/in_var.h>
   59 #include <netinet/ip_var.h>
   60 #include <netinet/ip_private.h>
   61 
   62 /*
   63  * Similar code is very well commented in netinet6/ip6_flow.c
   64  */ 
   65 
   66 struct ipflow {
   67         LIST_ENTRY(ipflow) ipf_list;    /* next in active list */
   68         LIST_ENTRY(ipflow) ipf_hash;    /* next ipflow in bucket */
   69         struct in_addr ipf_dst;         /* destination address */
   70         struct in_addr ipf_src;         /* source address */
   71         uint8_t ipf_tos;                /* type-of-service */
   72         struct route ipf_ro;            /* associated route entry */
   73         u_long ipf_uses;                /* number of uses in this period */
   74         u_long ipf_last_uses;           /* number of uses in last period */
   75         u_long ipf_dropped;             /* ENOBUFS retured by if_output */
   76         u_long ipf_errors;              /* other errors returned by if_output */
   77         u_int ipf_timer;                /* lifetime timer */
   78         time_t ipf_start;               /* creation time */
   79 };
   80 
   81 #define IPFLOW_HASHBITS         6       /* should not be a multiple of 8 */
   82 
   83 POOL_INIT(ipflow_pool, sizeof(struct ipflow), 0, 0, 0, "ipflowpl", NULL,
   84     IPL_NET);
   85 
   86 LIST_HEAD(ipflowhead, ipflow);
   87 
   88 #define IPFLOW_TIMER            (5 * PR_SLOWHZ)
   89 #define IPFLOW_DEFAULT_HASHSIZE (1 << IPFLOW_HASHBITS)
   90 
   91 static struct ipflowhead *ipflowtable = NULL;
   92 static struct ipflowhead ipflowlist;
   93 static int ipflow_inuse;
   94 
   95 #define IPFLOW_INSERT(bucket, ipf) \
   96 do { \
   97         LIST_INSERT_HEAD((bucket), (ipf), ipf_hash); \
   98         LIST_INSERT_HEAD(&ipflowlist, (ipf), ipf_list); \
   99 } while (/*CONSTCOND*/ 0)
  100 
  101 #define IPFLOW_REMOVE(ipf) \
  102 do { \
  103         LIST_REMOVE((ipf), ipf_hash); \
  104         LIST_REMOVE((ipf), ipf_list); \
  105 } while (/*CONSTCOND*/ 0)
  106 
  107 #ifndef IPFLOW_MAX
  108 #define IPFLOW_MAX              256
  109 #endif
  110 int ip_maxflows = IPFLOW_MAX;
  111 int ip_hashsize = IPFLOW_DEFAULT_HASHSIZE;
  112 
  113 static size_t 
  114 ipflow_hash(const struct ip *ip)
  115 {
  116         size_t hash = ip->ip_tos;
  117         size_t idx;
  118 
  119         for (idx = 0; idx < 32; idx += IPFLOW_HASHBITS) {
  120                 hash += (ip->ip_dst.s_addr >> (32 - idx)) +
  121                     (ip->ip_src.s_addr >> idx);
  122         }
  123 
  124         return hash & (ip_hashsize-1);
  125 }
  126 
  127 static struct ipflow *
  128 ipflow_lookup(const struct ip *ip)
  129 {
  130         size_t hash;
  131         struct ipflow *ipf;
  132 
  133         hash = ipflow_hash(ip);
  134 
  135         LIST_FOREACH(ipf, &ipflowtable[hash], ipf_hash) {
  136                 if (ip->ip_dst.s_addr == ipf->ipf_dst.s_addr
  137                     && ip->ip_src.s_addr == ipf->ipf_src.s_addr
  138                     && ip->ip_tos == ipf->ipf_tos)
  139                         break;
  140         }
  141         return ipf;
  142 }
  143 
  144 int
  145 ipflow_init(int table_size)
  146 {
  147         struct ipflowhead *new_table;
  148         size_t i;
  149 
  150         new_table = (struct ipflowhead *)malloc(sizeof(struct ipflowhead) *
  151             table_size, M_RTABLE, M_NOWAIT);
  152 
  153         if (new_table == NULL)
  154                 return 1;
  155 
  156         if (ipflowtable != NULL)
  157                 free(ipflowtable, M_RTABLE);
  158 
  159         ipflowtable = new_table;
  160         ip_hashsize = table_size;
  161 
  162         LIST_INIT(&ipflowlist);
  163         for (i = 0; i < ip_hashsize; i++)
  164                 LIST_INIT(&ipflowtable[i]);
  165 
  166         return 0;
  167 }
  168 
  169 int
  170 ipflow_fastforward(struct mbuf *m)
  171 {
  172         struct ip *ip;
  173         struct ip ip_store;
  174         struct ipflow *ipf;
  175         struct rtentry *rt;
  176         const struct sockaddr *dst;
  177         int error;
  178         int iplen;
  179 
  180         /*
  181          * Are we forwarding packets?  Big enough for an IP packet?
  182          */
  183         if (!ipforwarding || ipflow_inuse == 0 || m->m_len < sizeof(struct ip))
  184                 return 0;
  185 
  186         /*
  187          * Was packet received as a link-level multicast or broadcast?
  188          * If so, don't try to fast forward..
  189          */
  190         if ((m->m_flags & (M_BCAST|M_MCAST)) != 0)
  191                 return 0;
  192 
  193         /*
  194          * IP header with no option and valid version and length
  195          */
  196         if (IP_HDR_ALIGNED_P(mtod(m, const void *)))
  197                 ip = mtod(m, struct ip *);
  198         else {
  199                 memcpy(&ip_store, mtod(m, const void *), sizeof(ip_store));
  200                 ip = &ip_store;
  201         }
  202         iplen = ntohs(ip->ip_len);
  203         if (ip->ip_v != IPVERSION || ip->ip_hl != (sizeof(struct ip) >> 2) ||
  204             iplen < sizeof(struct ip) || iplen > m->m_pkthdr.len)
  205                 return 0;
  206         /*
  207          * Find a flow.
  208          */
  209         if ((ipf = ipflow_lookup(ip)) == NULL)
  210                 return 0;
  211 
  212         /*
  213          * Verify the IP header checksum.
  214          */
  215         switch (m->m_pkthdr.csum_flags &
  216                 ((m->m_pkthdr.rcvif->if_csum_flags_rx & M_CSUM_IPv4) |
  217                  M_CSUM_IPv4_BAD)) {
  218         case M_CSUM_IPv4|M_CSUM_IPv4_BAD:
  219                 return (0);
  220 
  221         case M_CSUM_IPv4:
  222                 /* Checksum was okay. */
  223                 break;
  224 
  225         default:
  226                 /* Must compute it ourselves. */
  227                 if (in_cksum(m, sizeof(struct ip)) != 0)
  228                         return (0);
  229                 break;
  230         }
  231 
  232         /*
  233          * Route and interface still up?
  234          */
  235         if ((rt = rtcache_validate(&ipf->ipf_ro)) == NULL ||
  236             (rt->rt_ifp->if_flags & IFF_UP) == 0)
  237                 return 0;
  238 
  239         /*
  240          * Packet size OK?  TTL?
  241          */
  242         if (m->m_pkthdr.len > rt->rt_ifp->if_mtu || ip->ip_ttl <= IPTTLDEC)
  243                 return 0;
  244 
  245         /*
  246          * Clear any in-bound checksum flags for this packet.
  247          */
  248         m->m_pkthdr.csum_flags = 0;
  249 
  250         /*
  251          * Everything checks out and so we can forward this packet.
  252          * Modify the TTL and incrementally change the checksum.
  253          *
  254          * This method of adding the checksum works on either endian CPU.
  255          * If htons() is inlined, all the arithmetic is folded; otherwise
  256          * the htons()s are combined by CSE due to the const attribute.
  257          *
  258          * Don't bother using HW checksumming here -- the incremental
  259          * update is pretty fast.
  260          */
  261         ip->ip_ttl -= IPTTLDEC;
  262         if (ip->ip_sum >= (u_int16_t) ~htons(IPTTLDEC << 8))
  263                 ip->ip_sum -= ~htons(IPTTLDEC << 8);
  264         else
  265                 ip->ip_sum += htons(IPTTLDEC << 8);
  266 
  267         /*
  268          * Done modifying the header; copy it back, if necessary.
  269          *
  270          * XXX Use m_copyback_cow(9) here? --dyoung
  271          */
  272         if (IP_HDR_ALIGNED_P(mtod(m, void *)) == 0)
  273                 memcpy(mtod(m, void *), &ip_store, sizeof(ip_store));
  274 
  275         /*
  276          * Trim the packet in case it's too long..
  277          */
  278         if (m->m_pkthdr.len > iplen) {
  279                 if (m->m_len == m->m_pkthdr.len) {
  280                         m->m_len = iplen;
  281                         m->m_pkthdr.len = iplen;
  282                 } else
  283                         m_adj(m, iplen - m->m_pkthdr.len);
  284         }
  285 
  286         /*
  287          * Send the packet on it's way.  All we can get back is ENOBUFS
  288          */
  289         ipf->ipf_uses++;
  290         PRT_SLOW_ARM(ipf->ipf_timer, IPFLOW_TIMER);
  291 
  292         if (rt->rt_flags & RTF_GATEWAY)
  293                 dst = rt->rt_gateway;
  294         else
  295                 dst = rtcache_getdst(&ipf->ipf_ro);
  296 
  297         if ((error = (*rt->rt_ifp->if_output)(rt->rt_ifp, m, dst, rt)) != 0) {
  298                 if (error == ENOBUFS)
  299                         ipf->ipf_dropped++;
  300                 else
  301                         ipf->ipf_errors++;
  302         }
  303         return 1;
  304 }
  305 
  306 static void
  307 ipflow_addstats(struct ipflow *ipf)
  308 {
  309         struct rtentry *rt;
  310         uint64_t *ips;
  311 
  312         if ((rt = rtcache_validate(&ipf->ipf_ro)) != NULL)
  313                 rt->rt_use += ipf->ipf_uses;
  314         
  315         ips = IP_STAT_GETREF();
  316         ips[IP_STAT_CANTFORWARD] += ipf->ipf_errors + ipf->ipf_dropped;
  317         ips[IP_STAT_TOTAL] += ipf->ipf_uses;
  318         ips[IP_STAT_FORWARD] += ipf->ipf_uses;
  319         ips[IP_STAT_FASTFORWARD] += ipf->ipf_uses;
  320         IP_STAT_PUTREF();
  321 }
  322 
  323 static void
  324 ipflow_free(struct ipflow *ipf)
  325 {
  326         int s;
  327         /*
  328          * Remove the flow from the hash table (at elevated IPL).
  329          * Once it's off the list, we can deal with it at normal
  330          * network IPL.
  331          */
  332         s = splnet();
  333         IPFLOW_REMOVE(ipf);
  334         splx(s);
  335         ipflow_addstats(ipf);
  336         rtcache_free(&ipf->ipf_ro);
  337         ipflow_inuse--;
  338         s = splnet();
  339         pool_put(&ipflow_pool, ipf);
  340         splx(s);
  341 }
  342 
  343 static struct ipflow *
  344 ipflow_reap(bool just_one)
  345 {
  346         while (just_one || ipflow_inuse > ip_maxflows) {
  347                 struct ipflow *ipf, *maybe_ipf = NULL;
  348                 int s;
  349 
  350                 ipf = LIST_FIRST(&ipflowlist);
  351                 while (ipf != NULL) {
  352                         /*
  353                          * If this no longer points to a valid route
  354                          * reclaim it.
  355                          */
  356                         if (rtcache_validate(&ipf->ipf_ro) == NULL)
  357                                 goto done;
  358                         /*
  359                          * choose the one that's been least recently
  360                          * used or has had the least uses in the
  361                          * last 1.5 intervals.
  362                          */
  363                         if (maybe_ipf == NULL ||
  364                             ipf->ipf_timer < maybe_ipf->ipf_timer ||
  365                             (ipf->ipf_timer == maybe_ipf->ipf_timer &&
  366                              ipf->ipf_last_uses + ipf->ipf_uses <
  367                                  maybe_ipf->ipf_last_uses +
  368                                  maybe_ipf->ipf_uses))
  369                                 maybe_ipf = ipf;
  370                         ipf = LIST_NEXT(ipf, ipf_list);
  371                 }
  372                 ipf = maybe_ipf;
  373             done:
  374                 /*
  375                  * Remove the entry from the flow table.
  376                  */
  377                 s = splnet();
  378                 IPFLOW_REMOVE(ipf);
  379                 splx(s);
  380                 ipflow_addstats(ipf);
  381                 rtcache_free(&ipf->ipf_ro);
  382                 if (just_one)
  383                         return ipf;
  384                 pool_put(&ipflow_pool, ipf);
  385                 ipflow_inuse--;
  386         }
  387         return NULL;
  388 }
  389 
  390 void
  391 ipflow_prune(void)
  392 {
  393 
  394         (void) ipflow_reap(false);
  395 }
  396 
  397 void
  398 ipflow_slowtimo(void)
  399 {
  400         struct rtentry *rt;
  401         struct ipflow *ipf, *next_ipf;
  402         uint64_t *ips;
  403 
  404         mutex_enter(softnet_lock);
  405         KERNEL_LOCK(1, NULL);
  406         for (ipf = LIST_FIRST(&ipflowlist); ipf != NULL; ipf = next_ipf) {
  407                 next_ipf = LIST_NEXT(ipf, ipf_list);
  408                 if (PRT_SLOW_ISEXPIRED(ipf->ipf_timer) ||
  409                     (rt = rtcache_validate(&ipf->ipf_ro)) == NULL) {
  410                         ipflow_free(ipf);
  411                 } else {
  412                         ipf->ipf_last_uses = ipf->ipf_uses;
  413                         rt->rt_use += ipf->ipf_uses;
  414                         ips = IP_STAT_GETREF();
  415                         ips[IP_STAT_TOTAL] += ipf->ipf_uses;
  416                         ips[IP_STAT_FORWARD] += ipf->ipf_uses;
  417                         ips[IP_STAT_FASTFORWARD] += ipf->ipf_uses;
  418                         IP_STAT_PUTREF();
  419                         ipf->ipf_uses = 0;
  420                 }
  421         }
  422         KERNEL_UNLOCK_ONE(NULL);
  423         mutex_exit(softnet_lock);
  424 }
  425 
  426 void
  427 ipflow_create(const struct route *ro, struct mbuf *m)
  428 {
  429         const struct ip *const ip = mtod(m, const struct ip *);
  430         struct ipflow *ipf;
  431         size_t hash;
  432         int s;
  433 
  434         /*
  435          * Don't create cache entries for ICMP messages.
  436          */
  437         if (ip_maxflows == 0 || ip->ip_p == IPPROTO_ICMP)
  438                 return;
  439         /*
  440          * See if an existing flow struct exists.  If so remove it from it's
  441          * list and free the old route.  If not, try to malloc a new one
  442          * (if we aren't at our limit).
  443          */
  444         ipf = ipflow_lookup(ip);
  445         if (ipf == NULL) {
  446                 if (ipflow_inuse >= ip_maxflows) {
  447                         ipf = ipflow_reap(true);
  448                 } else {
  449                         s = splnet();
  450                         ipf = pool_get(&ipflow_pool, PR_NOWAIT);
  451                         splx(s);
  452                         if (ipf == NULL)
  453                                 return;
  454                         ipflow_inuse++;
  455                 }
  456                 memset(ipf, 0, sizeof(*ipf));
  457         } else {
  458                 s = splnet();
  459                 IPFLOW_REMOVE(ipf);
  460                 splx(s);
  461                 ipflow_addstats(ipf);
  462                 rtcache_free(&ipf->ipf_ro);
  463                 ipf->ipf_uses = ipf->ipf_last_uses = 0;
  464                 ipf->ipf_errors = ipf->ipf_dropped = 0;
  465         }
  466 
  467         /*
  468          * Fill in the updated information.
  469          */
  470         rtcache_copy(&ipf->ipf_ro, ro);
  471         ipf->ipf_dst = ip->ip_dst;
  472         ipf->ipf_src = ip->ip_src;
  473         ipf->ipf_tos = ip->ip_tos;
  474         PRT_SLOW_ARM(ipf->ipf_timer, IPFLOW_TIMER);
  475         ipf->ipf_start = time_uptime;
  476         /*
  477          * Insert into the approriate bucket of the flow table.
  478          */
  479         hash = ipflow_hash(ip);
  480         s = splnet();
  481         IPFLOW_INSERT(&ipflowtable[hash], ipf);
  482         splx(s);
  483 }
  484 
  485 int
  486 ipflow_invalidate_all(int new_size)
  487 {
  488         struct ipflow *ipf, *next_ipf;
  489         int s, error;
  490 
  491         error = 0;
  492         s = splnet();
  493         for (ipf = LIST_FIRST(&ipflowlist); ipf != NULL; ipf = next_ipf) {
  494                 next_ipf = LIST_NEXT(ipf, ipf_list);
  495                 ipflow_free(ipf);
  496         }
  497 
  498         if (new_size)
  499                 error = ipflow_init(new_size);
  500         splx(s);
  501 
  502         return error;
  503 }
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FreeBSD/Linux Kernel Cross Reference sys/netinet/ip_flow.c

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