The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/netgraph/ng_etf.c

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    1 /*-
    2  * ng_etf.c  Ethertype filter
    3  */
    4 
    5 /*-
    6  * Copyright (c) 2001, FreeBSD Incorporated 
    7  * All rights reserved.
    8  *
    9  * Redistribution and use in source and binary forms, with or without
   10  * modification, are permitted provided that the following conditions
   11  * are met:
   12  * 1. Redistributions of source code must retain the above copyright
   13  *    notice unmodified, this list of conditions, and the following
   14  *    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 AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   29  * SUCH DAMAGE.
   30  *
   31  * Author: Julian Elischer <julian@freebsd.org>
   32  *
   33  * $FreeBSD: src/sys/netgraph/ng_etf.c,v 1.6.2.1 2005/01/31 23:26:28 imp Exp $
   34  */
   35 
   36 #include <sys/param.h>
   37 #include <sys/systm.h>
   38 #include <sys/kernel.h>
   39 #include <sys/mbuf.h>
   40 #include <sys/malloc.h>
   41 #include <sys/ctype.h>
   42 #include <sys/errno.h>
   43 #include <sys/queue.h>
   44 #include <sys/syslog.h>
   45 
   46 #include <net/ethernet.h>
   47 
   48 #include <netgraph/ng_message.h>
   49 #include <netgraph/ng_parse.h>
   50 #include <netgraph/ng_etf.h>
   51 #include <netgraph/netgraph.h>
   52 
   53 /* If you do complicated mallocs you may want to do this */
   54 /* and use it for your mallocs */
   55 #ifdef NG_SEPARATE_MALLOC
   56 MALLOC_DEFINE(M_NETGRAPH_ETF, "netgraph_etf", "netgraph etf node ");
   57 #else
   58 #define M_NETGRAPH_ETF M_NETGRAPH
   59 #endif
   60 
   61 /*
   62  * This section contains the netgraph method declarations for the
   63  * etf node. These methods define the netgraph 'type'.
   64  */
   65 
   66 static ng_constructor_t ng_etf_constructor;
   67 static ng_rcvmsg_t      ng_etf_rcvmsg;
   68 static ng_shutdown_t    ng_etf_shutdown;
   69 static ng_newhook_t     ng_etf_newhook;
   70 static ng_connect_t     ng_etf_connect;
   71 static ng_rcvdata_t     ng_etf_rcvdata;  /* note these are both ng_rcvdata_t */
   72 static ng_disconnect_t  ng_etf_disconnect;
   73 
   74 /* Parse type for struct ng_etfstat */
   75 static const struct ng_parse_struct_field ng_etf_stat_type_fields[]
   76         = NG_ETF_STATS_TYPE_INFO;
   77 static const struct ng_parse_type ng_etf_stat_type = {
   78         &ng_parse_struct_type,
   79         &ng_etf_stat_type_fields
   80 };
   81 /* Parse type for struct ng_setfilter */
   82 static const struct ng_parse_struct_field ng_etf_filter_type_fields[]
   83         = NG_ETF_FILTER_TYPE_INFO;
   84 static const struct ng_parse_type ng_etf_filter_type = {
   85         &ng_parse_struct_type,
   86         &ng_etf_filter_type_fields
   87 };
   88 
   89 /* List of commands and how to convert arguments to/from ASCII */
   90 static const struct ng_cmdlist ng_etf_cmdlist[] = {
   91         {
   92           NGM_ETF_COOKIE,
   93           NGM_ETF_GET_STATUS,
   94           "getstatus",
   95           NULL,
   96           &ng_etf_stat_type,
   97         },
   98         {
   99           NGM_ETF_COOKIE,
  100           NGM_ETF_SET_FLAG,
  101           "setflag",
  102           &ng_parse_int32_type,
  103           NULL
  104         },
  105         {
  106           NGM_ETF_COOKIE,
  107           NGM_ETF_SET_FILTER,
  108           "setfilter",
  109           &ng_etf_filter_type,
  110           NULL
  111         },
  112         { 0 }
  113 };
  114 
  115 /* Netgraph node type descriptor */
  116 static struct ng_type typestruct = {
  117         .version =      NG_ABI_VERSION,
  118         .name =         NG_ETF_NODE_TYPE,
  119         .constructor =  ng_etf_constructor,
  120         .rcvmsg =       ng_etf_rcvmsg,
  121         .shutdown =     ng_etf_shutdown,
  122         .newhook =      ng_etf_newhook,
  123         .connect =      ng_etf_connect,
  124         .rcvdata =      ng_etf_rcvdata,
  125         .disconnect =   ng_etf_disconnect,
  126         .cmdlist =      ng_etf_cmdlist,
  127 };
  128 NETGRAPH_INIT(etf, &typestruct);
  129 
  130 /* Information we store for each hook on each node */
  131 struct ETF_hookinfo {
  132         hook_p  hook;
  133 };
  134 
  135 struct filter {
  136         LIST_ENTRY(filter) next;
  137         u_int16_t       ethertype;      /* network order ethertype */
  138         hook_p          match_hook;     /* Hook to use on a match */
  139 };
  140 
  141 #define HASHSIZE 16 /* Dont change this without changing HASH() */
  142 #define HASH(et) ((((et)>>12)+((et)>>8)+((et)>>4)+(et)) & 0x0f)
  143 LIST_HEAD(filterhead, filter);
  144 
  145 /* Information we store for each node */
  146 struct ETF {
  147         struct ETF_hookinfo downstream_hook;
  148         struct ETF_hookinfo nomatch_hook;
  149         node_p          node;           /* back pointer to node */
  150         u_int           packets_in;     /* packets in from downstream */
  151         u_int           packets_out;    /* packets out towards downstream */
  152         u_int32_t       flags;
  153         struct filterhead hashtable[HASHSIZE];
  154 };
  155 typedef struct ETF *etf_p;
  156 
  157 static struct filter *
  158 ng_etf_findentry(etf_p etfp, u_int16_t ethertype)
  159 {
  160         struct filterhead *chain = etfp->hashtable + HASH(ethertype);
  161         struct filter *fil;
  162         
  163 
  164         LIST_FOREACH(fil, chain, next) {
  165                 if (fil->ethertype == ethertype) {
  166                         return (fil);
  167                 }
  168         }
  169         return (NULL);
  170 }
  171 
  172 
  173 /*
  174  * Allocate the private data structure. The generic node has already
  175  * been created. Link them together. We arrive with a reference to the node
  176  * i.e. the reference count is incremented for us already.
  177  */
  178 static int
  179 ng_etf_constructor(node_p node)
  180 {
  181         etf_p privdata;
  182         int i;
  183 
  184         /* Initialize private descriptor */
  185         MALLOC(privdata, etf_p, sizeof(*privdata), M_NETGRAPH_ETF,
  186                 M_NOWAIT | M_ZERO);
  187         if (privdata == NULL)
  188                 return (ENOMEM);
  189         for (i = 0; i < HASHSIZE; i++) {
  190                 LIST_INIT((privdata->hashtable + i));
  191         }
  192 
  193         /* Link structs together; this counts as our one reference to node */
  194         NG_NODE_SET_PRIVATE(node, privdata);
  195         privdata->node = node;
  196         return (0);
  197 }
  198 
  199 /*
  200  * Give our ok for a hook to be added...
  201  * All names are ok. Two names are special.
  202  */
  203 static int
  204 ng_etf_newhook(node_p node, hook_p hook, const char *name)
  205 {
  206         const etf_p etfp = NG_NODE_PRIVATE(node);
  207         struct ETF_hookinfo *hpriv;
  208 
  209         if (strcmp(name, NG_ETF_HOOK_DOWNSTREAM) == 0) {
  210                 etfp->downstream_hook.hook = hook;
  211                 NG_HOOK_SET_PRIVATE(hook, &etfp->downstream_hook);
  212                 etfp->packets_in = 0;
  213                 etfp->packets_out = 0;
  214         } else if (strcmp(name, NG_ETF_HOOK_NOMATCH) == 0) {
  215                 etfp->nomatch_hook.hook = hook;
  216                 NG_HOOK_SET_PRIVATE(hook, &etfp->nomatch_hook);
  217         } else {
  218                 /*
  219                  * Any other hook name is valid and can
  220                  * later be associated with a filter rule.
  221                  */
  222                 MALLOC(hpriv, struct ETF_hookinfo *, sizeof(*hpriv),
  223                         M_NETGRAPH_ETF, M_NOWAIT | M_ZERO);
  224                 if (hpriv == NULL) {
  225                         return (ENOMEM);
  226                 }
  227 
  228                 NG_HOOK_SET_PRIVATE(hook, hpriv);
  229                 hpriv->hook = hook;
  230         }
  231         return(0);
  232 }
  233 
  234 /*
  235  * Get a netgraph control message.
  236  * We actually recieve a queue item that has a pointer to the message.
  237  * If we free the item, the message will be freed too, unless we remove
  238  * it from the item using NGI_GET_MSG();
  239  * The return address is also stored in the item, as an ng_ID_t,
  240  * accessible as NGI_RETADDR(item);
  241  * Check it is one we understand. If needed, send a response.
  242  * We could save the address for an async action later, but don't here.
  243  * Always free the message.
  244  * The response should be in a malloc'd region that the caller can 'free'.
  245  * The NG_MKRESPONSE macro does all this for us.
  246  * A response is not required.
  247  * Theoretically you could respond defferently to old message types if
  248  * the cookie in the header didn't match what we consider to be current
  249  * (so that old userland programs could continue to work).
  250  */
  251 static int
  252 ng_etf_rcvmsg(node_p node, item_p item, hook_p lasthook)
  253 {
  254         const etf_p etfp = NG_NODE_PRIVATE(node);
  255         struct ng_mesg *resp = NULL;
  256         int error = 0;
  257         struct ng_mesg *msg;
  258 
  259         NGI_GET_MSG(item, msg);
  260         /* Deal with message according to cookie and command */
  261         switch (msg->header.typecookie) {
  262         case NGM_ETF_COOKIE: 
  263                 switch (msg->header.cmd) {
  264                 case NGM_ETF_GET_STATUS:
  265                     {
  266                         struct ng_etfstat *stats;
  267 
  268                         NG_MKRESPONSE(resp, msg, sizeof(*stats), M_NOWAIT);
  269                         if (!resp) {
  270                                 error = ENOMEM;
  271                                 break;
  272                         }
  273                         stats = (struct ng_etfstat *) resp->data;
  274                         stats->packets_in = etfp->packets_in;
  275                         stats->packets_out = etfp->packets_out;
  276                         break;
  277                     }
  278                 case NGM_ETF_SET_FLAG:
  279                         if (msg->header.arglen != sizeof(u_int32_t)) {
  280                                 error = EINVAL;
  281                                 break;
  282                         }
  283                         etfp->flags = *((u_int32_t *) msg->data);
  284                         break;
  285                 case NGM_ETF_SET_FILTER:
  286                         {
  287                                 struct ng_etffilter *f;
  288                                 struct filter *fil;
  289                                 hook_p  hook;
  290 
  291                                 /* Check message long enough for this command */
  292                                 if (msg->header.arglen != sizeof(*f)) {
  293                                         error = EINVAL;
  294                                         break;
  295                                 }
  296 
  297                                 /* Make sure hook referenced exists */
  298                                 f = (struct ng_etffilter *)msg->data;
  299                                 hook = ng_findhook(node, f->matchhook);
  300                                 if (hook == NULL) {
  301                                         error = ENOENT;
  302                                         break;
  303                                 }
  304 
  305                                 /* and is not the downstream hook */
  306                                 if (hook == etfp->downstream_hook.hook) {
  307                                         error = EINVAL;
  308                                         break;
  309                                 }
  310 
  311                                 /* Check we don't already trap this ethertype */
  312                                 if (ng_etf_findentry(etfp,
  313                                                 htons(f->ethertype))) {
  314                                         error = EEXIST;
  315                                         break;
  316                                 }
  317 
  318                                 /*
  319                                  * Ok, make the filter and put it in the 
  320                                  * hashtable ready for matching.
  321                                  */
  322                                 MALLOC(fil, struct filter *, sizeof(*fil),
  323                                         M_NETGRAPH_ETF, M_NOWAIT | M_ZERO);
  324                                 if (fil == NULL) {
  325                                         error = ENOMEM;
  326                                         break;
  327                                 }
  328 
  329                                 fil->match_hook = hook;
  330                                 fil->ethertype = htons(f->ethertype);
  331                                 LIST_INSERT_HEAD( etfp->hashtable
  332                                         + HASH(fil->ethertype),
  333                                                 fil, next);
  334                         }
  335                         break;
  336                 default:
  337                         error = EINVAL;         /* unknown command */
  338                         break;
  339                 }
  340                 break;
  341         default:
  342                 error = EINVAL;                 /* unknown cookie type */
  343                 break;
  344         }
  345 
  346         /* Take care of synchronous response, if any */
  347         NG_RESPOND_MSG(error, node, item, resp);
  348         /* Free the message and return */
  349         NG_FREE_MSG(msg);
  350         return(error);
  351 }
  352 
  353 /*
  354  * Receive data, and do something with it.
  355  * Actually we receive a queue item which holds the data.
  356  * If we free the item it will also free the data unless we have previously
  357  * disassociated it using the NGI_GET_etf() macro.
  358  * Possibly send it out on another link after processing.
  359  * Possibly do something different if it comes from different
  360  * hooks. The caller will never free m , so if we use up this data
  361  * or abort we must free it.
  362  *
  363  * If we want, we may decide to force this data to be queued and reprocessed
  364  * at the netgraph NETISR time.
  365  * We would do that by setting the HK_QUEUE flag on our hook. We would do that
  366  * in the connect() method. 
  367  */
  368 static int
  369 ng_etf_rcvdata(hook_p hook, item_p item )
  370 {
  371         const etf_p etfp = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
  372         struct ether_header *eh;
  373         int error = 0;
  374         struct mbuf *m;
  375         u_int16_t ethertype;
  376         struct filter *fil;
  377 
  378         if (NG_HOOK_PRIVATE(hook) == NULL) { /* Shouldn't happen but.. */
  379                 NG_FREE_ITEM(item);
  380         }
  381 
  382         /* 
  383          * Everything not from the downstream hook goes to the
  384          * downstream hook. But only if it matches the ethertype
  385          * of the source hook. Un matching must go to/from 'nomatch'.
  386          */
  387 
  388         /* Make sure we have an entire header */
  389         NGI_GET_M(item, m);
  390         if (m->m_len < sizeof(*eh) ) {
  391                 m = m_pullup(m, sizeof(*eh));
  392                 if (m == NULL) {
  393                         NG_FREE_ITEM(item);
  394                         return(EINVAL);
  395                 }
  396         }
  397 
  398         eh = mtod(m, struct ether_header *);
  399         ethertype = eh->ether_type;
  400         fil = ng_etf_findentry(etfp, ethertype);
  401 
  402         /*
  403          * if from downstream, select between a match hook or
  404          * the nomatch hook
  405          */
  406         if (hook == etfp->downstream_hook.hook) {
  407                 etfp->packets_in++;
  408                 if (fil && fil->match_hook) {
  409                         NG_FWD_NEW_DATA(error, item, fil->match_hook, m);
  410                 } else {
  411                         NG_FWD_NEW_DATA(error, item,etfp->nomatch_hook.hook, m);
  412                 }
  413         } else {
  414                 /* 
  415                  * It must be heading towards the downstream.
  416                  * Check that it's ethertype matches 
  417                  * the filters for it's input hook.
  418                  * If it doesn't have one, check it's from nomatch.
  419                  */
  420                 if ((fil && (fil->match_hook != hook))
  421                 || ((fil == NULL) && (hook != etfp->nomatch_hook.hook))) {
  422                         NG_FREE_ITEM(item);
  423                         NG_FREE_M(m);
  424                         return (EPROTOTYPE);
  425                 }
  426                 NG_FWD_NEW_DATA( error, item, etfp->downstream_hook.hook, m);
  427                 if (error == 0) {
  428                         etfp->packets_out++;
  429                 }
  430         }
  431         return (error);
  432 }
  433 
  434 /*
  435  * Do local shutdown processing..
  436  * All our links and the name have already been removed.
  437  */
  438 static int
  439 ng_etf_shutdown(node_p node)
  440 {
  441         const etf_p privdata = NG_NODE_PRIVATE(node);
  442 
  443         NG_NODE_SET_PRIVATE(node, NULL);
  444         NG_NODE_UNREF(privdata->node);
  445         FREE(privdata, M_NETGRAPH_ETF);
  446         return (0);
  447 }
  448 
  449 /*
  450  * This is called once we've already connected a new hook to the other node.
  451  * It gives us a chance to balk at the last minute.
  452  */
  453 static int
  454 ng_etf_connect(hook_p hook)
  455 {
  456         return (0);
  457 }
  458 
  459 /*
  460  * Hook disconnection
  461  *
  462  * For this type, removal of the last link destroys the node
  463  */
  464 static int
  465 ng_etf_disconnect(hook_p hook)
  466 {
  467         const etf_p etfp = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
  468         int i;
  469         struct filter *fil1, *fil2;
  470 
  471         /* purge any rules that refer to this filter */
  472         for (i = 0; i < HASHSIZE; i++) {
  473                 fil1 = LIST_FIRST(&etfp->hashtable[i]);
  474                 while (fil1 != NULL) {
  475                         fil2 = LIST_NEXT(fil1, next);
  476                         if (fil1->match_hook == hook) {
  477                                 LIST_REMOVE(fil1, next);
  478                                 FREE(fil1, M_NETGRAPH_ETF);
  479                         }
  480                         fil1 = fil2;
  481                 }
  482         }
  483                 
  484         /* If it's not one of the special hooks, then free it */
  485         if (hook == etfp->downstream_hook.hook) {
  486                 etfp->downstream_hook.hook = NULL;
  487         } else if (hook == etfp->nomatch_hook.hook) {
  488                 etfp->nomatch_hook.hook = NULL;
  489         } else {
  490                 if (NG_HOOK_PRIVATE(hook)) /* Paranoia */
  491                         FREE(NG_HOOK_PRIVATE(hook), M_NETGRAPH_ETF);
  492         }
  493 
  494         NG_HOOK_SET_PRIVATE(hook, NULL);
  495 
  496         if ((NG_NODE_NUMHOOKS(NG_HOOK_NODE(hook)) == 0)
  497         && (NG_NODE_IS_VALID(NG_HOOK_NODE(hook)))) /* already shutting down? */
  498                 ng_rmnode_self(NG_HOOK_NODE(hook));
  499         return (0);
  500 }
  501 

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