The Design and Implementation of the FreeBSD Operating System, Second Edition
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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: releng/11.0/sys/netgraph/ng_etf.c 298813 2016-04-29 21:25:05Z pfg $
   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 static 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_rcvdata_t     ng_etf_rcvdata;  /* note these are both ng_rcvdata_t */
   71 static ng_disconnect_t  ng_etf_disconnect;
   72 
   73 /* Parse type for struct ng_etfstat */
   74 static const struct ng_parse_struct_field ng_etf_stat_type_fields[]
   75         = NG_ETF_STATS_TYPE_INFO;
   76 static const struct ng_parse_type ng_etf_stat_type = {
   77         &ng_parse_struct_type,
   78         &ng_etf_stat_type_fields
   79 };
   80 /* Parse type for struct ng_setfilter */
   81 static const struct ng_parse_struct_field ng_etf_filter_type_fields[]
   82         = NG_ETF_FILTER_TYPE_INFO;
   83 static const struct ng_parse_type ng_etf_filter_type = {
   84         &ng_parse_struct_type,
   85         &ng_etf_filter_type_fields
   86 };
   87 
   88 /* List of commands and how to convert arguments to/from ASCII */
   89 static const struct ng_cmdlist ng_etf_cmdlist[] = {
   90         {
   91           NGM_ETF_COOKIE,
   92           NGM_ETF_GET_STATUS,
   93           "getstatus",
   94           NULL,
   95           &ng_etf_stat_type,
   96         },
   97         {
   98           NGM_ETF_COOKIE,
   99           NGM_ETF_SET_FLAG,
  100           "setflag",
  101           &ng_parse_int32_type,
  102           NULL
  103         },
  104         {
  105           NGM_ETF_COOKIE,
  106           NGM_ETF_SET_FILTER,
  107           "setfilter",
  108           &ng_etf_filter_type,
  109           NULL
  110         },
  111         { 0 }
  112 };
  113 
  114 /* Netgraph node type descriptor */
  115 static struct ng_type typestruct = {
  116         .version =      NG_ABI_VERSION,
  117         .name =         NG_ETF_NODE_TYPE,
  118         .constructor =  ng_etf_constructor,
  119         .rcvmsg =       ng_etf_rcvmsg,
  120         .shutdown =     ng_etf_shutdown,
  121         .newhook =      ng_etf_newhook,
  122         .rcvdata =      ng_etf_rcvdata,
  123         .disconnect =   ng_etf_disconnect,
  124         .cmdlist =      ng_etf_cmdlist,
  125 };
  126 NETGRAPH_INIT(etf, &typestruct);
  127 
  128 /* Information we store for each hook on each node */
  129 struct ETF_hookinfo {
  130         hook_p  hook;
  131 };
  132 
  133 struct filter {
  134         LIST_ENTRY(filter) next;
  135         u_int16_t       ethertype;      /* network order ethertype */
  136         hook_p          match_hook;     /* Hook to use on a match */
  137 };
  138 
  139 #define HASHSIZE 16 /* Dont change this without changing HASH() */
  140 #define HASH(et) ((((et)>>12)+((et)>>8)+((et)>>4)+(et)) & 0x0f)
  141 LIST_HEAD(filterhead, filter);
  142 
  143 /* Information we store for each node */
  144 struct ETF {
  145         struct ETF_hookinfo downstream_hook;
  146         struct ETF_hookinfo nomatch_hook;
  147         node_p          node;           /* back pointer to node */
  148         u_int           packets_in;     /* packets in from downstream */
  149         u_int           packets_out;    /* packets out towards downstream */
  150         u_int32_t       flags;
  151         struct filterhead hashtable[HASHSIZE];
  152 };
  153 typedef struct ETF *etf_p;
  154 
  155 static struct filter *
  156 ng_etf_findentry(etf_p etfp, u_int16_t ethertype)
  157 {
  158         struct filterhead *chain = etfp->hashtable + HASH(ethertype);
  159         struct filter *fil;
  160         
  161 
  162         LIST_FOREACH(fil, chain, next) {
  163                 if (fil->ethertype == ethertype) {
  164                         return (fil);
  165                 }
  166         }
  167         return (NULL);
  168 }
  169 
  170 
  171 /*
  172  * Allocate the private data structure. The generic node has already
  173  * been created. Link them together. We arrive with a reference to the node
  174  * i.e. the reference count is incremented for us already.
  175  */
  176 static int
  177 ng_etf_constructor(node_p node)
  178 {
  179         etf_p privdata;
  180         int i;
  181 
  182         /* Initialize private descriptor */
  183         privdata = malloc(sizeof(*privdata), M_NETGRAPH_ETF, M_WAITOK | M_ZERO);
  184         for (i = 0; i < HASHSIZE; i++) {
  185                 LIST_INIT((privdata->hashtable + i));
  186         }
  187 
  188         /* Link structs together; this counts as our one reference to node */
  189         NG_NODE_SET_PRIVATE(node, privdata);
  190         privdata->node = node;
  191         return (0);
  192 }
  193 
  194 /*
  195  * Give our ok for a hook to be added...
  196  * All names are ok. Two names are special.
  197  */
  198 static int
  199 ng_etf_newhook(node_p node, hook_p hook, const char *name)
  200 {
  201         const etf_p etfp = NG_NODE_PRIVATE(node);
  202         struct ETF_hookinfo *hpriv;
  203 
  204         if (strcmp(name, NG_ETF_HOOK_DOWNSTREAM) == 0) {
  205                 etfp->downstream_hook.hook = hook;
  206                 NG_HOOK_SET_PRIVATE(hook, &etfp->downstream_hook);
  207                 etfp->packets_in = 0;
  208                 etfp->packets_out = 0;
  209         } else if (strcmp(name, NG_ETF_HOOK_NOMATCH) == 0) {
  210                 etfp->nomatch_hook.hook = hook;
  211                 NG_HOOK_SET_PRIVATE(hook, &etfp->nomatch_hook);
  212         } else {
  213                 /*
  214                  * Any other hook name is valid and can
  215                  * later be associated with a filter rule.
  216                  */
  217                 hpriv = malloc(sizeof(*hpriv),
  218                         M_NETGRAPH_ETF, M_NOWAIT | M_ZERO);
  219                 if (hpriv == NULL) {
  220                         return (ENOMEM);
  221                 }
  222 
  223                 NG_HOOK_SET_PRIVATE(hook, hpriv);
  224                 hpriv->hook = hook;
  225         }
  226         return(0);
  227 }
  228 
  229 /*
  230  * Get a netgraph control message.
  231  * We actually receive a queue item that has a pointer to the message.
  232  * If we free the item, the message will be freed too, unless we remove
  233  * it from the item using NGI_GET_MSG();
  234  * The return address is also stored in the item, as an ng_ID_t,
  235  * accessible as NGI_RETADDR(item);
  236  * Check it is one we understand. If needed, send a response.
  237  * We could save the address for an async action later, but don't here.
  238  * Always free the message.
  239  * The response should be in a malloc'd region that the caller can 'free'.
  240  * The NG_MKRESPONSE macro does all this for us.
  241  * A response is not required.
  242  * Theoretically you could respond defferently to old message types if
  243  * the cookie in the header didn't match what we consider to be current
  244  * (so that old userland programs could continue to work).
  245  */
  246 static int
  247 ng_etf_rcvmsg(node_p node, item_p item, hook_p lasthook)
  248 {
  249         const etf_p etfp = NG_NODE_PRIVATE(node);
  250         struct ng_mesg *resp = NULL;
  251         int error = 0;
  252         struct ng_mesg *msg;
  253 
  254         NGI_GET_MSG(item, msg);
  255         /* Deal with message according to cookie and command */
  256         switch (msg->header.typecookie) {
  257         case NGM_ETF_COOKIE: 
  258                 switch (msg->header.cmd) {
  259                 case NGM_ETF_GET_STATUS:
  260                     {
  261                         struct ng_etfstat *stats;
  262 
  263                         NG_MKRESPONSE(resp, msg, sizeof(*stats), M_NOWAIT);
  264                         if (!resp) {
  265                                 error = ENOMEM;
  266                                 break;
  267                         }
  268                         stats = (struct ng_etfstat *) resp->data;
  269                         stats->packets_in = etfp->packets_in;
  270                         stats->packets_out = etfp->packets_out;
  271                         break;
  272                     }
  273                 case NGM_ETF_SET_FLAG:
  274                         if (msg->header.arglen != sizeof(u_int32_t)) {
  275                                 error = EINVAL;
  276                                 break;
  277                         }
  278                         etfp->flags = *((u_int32_t *) msg->data);
  279                         break;
  280                 case NGM_ETF_SET_FILTER:
  281                         {
  282                                 struct ng_etffilter *f;
  283                                 struct filter *fil;
  284                                 hook_p  hook;
  285 
  286                                 /* Check message long enough for this command */
  287                                 if (msg->header.arglen != sizeof(*f)) {
  288                                         error = EINVAL;
  289                                         break;
  290                                 }
  291 
  292                                 /* Make sure hook referenced exists */
  293                                 f = (struct ng_etffilter *)msg->data;
  294                                 hook = ng_findhook(node, f->matchhook);
  295                                 if (hook == NULL) {
  296                                         error = ENOENT;
  297                                         break;
  298                                 }
  299 
  300                                 /* and is not the downstream hook */
  301                                 if (hook == etfp->downstream_hook.hook) {
  302                                         error = EINVAL;
  303                                         break;
  304                                 }
  305 
  306                                 /* Check we don't already trap this ethertype */
  307                                 if (ng_etf_findentry(etfp,
  308                                                 htons(f->ethertype))) {
  309                                         error = EEXIST;
  310                                         break;
  311                                 }
  312 
  313                                 /*
  314                                  * Ok, make the filter and put it in the 
  315                                  * hashtable ready for matching.
  316                                  */
  317                                 fil = malloc(sizeof(*fil),
  318                                         M_NETGRAPH_ETF, M_NOWAIT | M_ZERO);
  319                                 if (fil == NULL) {
  320                                         error = ENOMEM;
  321                                         break;
  322                                 }
  323 
  324                                 fil->match_hook = hook;
  325                                 fil->ethertype = htons(f->ethertype);
  326                                 LIST_INSERT_HEAD( etfp->hashtable
  327                                         + HASH(fil->ethertype),
  328                                                 fil, next);
  329                         }
  330                         break;
  331                 default:
  332                         error = EINVAL;         /* unknown command */
  333                         break;
  334                 }
  335                 break;
  336         default:
  337                 error = EINVAL;                 /* unknown cookie type */
  338                 break;
  339         }
  340 
  341         /* Take care of synchronous response, if any */
  342         NG_RESPOND_MSG(error, node, item, resp);
  343         /* Free the message and return */
  344         NG_FREE_MSG(msg);
  345         return(error);
  346 }
  347 
  348 /*
  349  * Receive data, and do something with it.
  350  * Actually we receive a queue item which holds the data.
  351  * If we free the item it will also free the data unless we have previously
  352  * disassociated it using the NGI_GET_etf() macro.
  353  * Possibly send it out on another link after processing.
  354  * Possibly do something different if it comes from different
  355  * hooks. The caller will never free m , so if we use up this data
  356  * or abort we must free it.
  357  *
  358  * If we want, we may decide to force this data to be queued and reprocessed
  359  * at the netgraph NETISR time.
  360  * We would do that by setting the HK_QUEUE flag on our hook. We would do that
  361  * in the connect() method. 
  362  */
  363 static int
  364 ng_etf_rcvdata(hook_p hook, item_p item )
  365 {
  366         const etf_p etfp = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
  367         struct ether_header *eh;
  368         int error = 0;
  369         struct mbuf *m;
  370         u_int16_t ethertype;
  371         struct filter *fil;
  372 
  373         if (NG_HOOK_PRIVATE(hook) == NULL) { /* Shouldn't happen but.. */
  374                 NG_FREE_ITEM(item);
  375         }
  376 
  377         /* 
  378          * Everything not from the downstream hook goes to the
  379          * downstream hook. But only if it matches the ethertype
  380          * of the source hook. Un matching must go to/from 'nomatch'.
  381          */
  382 
  383         /* Make sure we have an entire header */
  384         NGI_GET_M(item, m);
  385         if (m->m_len < sizeof(*eh) ) {
  386                 m = m_pullup(m, sizeof(*eh));
  387                 if (m == NULL) {
  388                         NG_FREE_ITEM(item);
  389                         return(EINVAL);
  390                 }
  391         }
  392 
  393         eh = mtod(m, struct ether_header *);
  394         ethertype = eh->ether_type;
  395         fil = ng_etf_findentry(etfp, ethertype);
  396 
  397         /*
  398          * if from downstream, select between a match hook or
  399          * the nomatch hook
  400          */
  401         if (hook == etfp->downstream_hook.hook) {
  402                 etfp->packets_in++;
  403                 if (fil && fil->match_hook) {
  404                         NG_FWD_NEW_DATA(error, item, fil->match_hook, m);
  405                 } else {
  406                         NG_FWD_NEW_DATA(error, item,etfp->nomatch_hook.hook, m);
  407                 }
  408         } else {
  409                 /* 
  410                  * It must be heading towards the downstream.
  411                  * Check that it's ethertype matches 
  412                  * the filters for it's input hook.
  413                  * If it doesn't have one, check it's from nomatch.
  414                  */
  415                 if ((fil && (fil->match_hook != hook))
  416                 || ((fil == NULL) && (hook != etfp->nomatch_hook.hook))) {
  417                         NG_FREE_ITEM(item);
  418                         NG_FREE_M(m);
  419                         return (EPROTOTYPE);
  420                 }
  421                 NG_FWD_NEW_DATA( error, item, etfp->downstream_hook.hook, m);
  422                 if (error == 0) {
  423                         etfp->packets_out++;
  424                 }
  425         }
  426         return (error);
  427 }
  428 
  429 /*
  430  * Do local shutdown processing..
  431  * All our links and the name have already been removed.
  432  */
  433 static int
  434 ng_etf_shutdown(node_p node)
  435 {
  436         const etf_p privdata = NG_NODE_PRIVATE(node);
  437 
  438         NG_NODE_SET_PRIVATE(node, NULL);
  439         NG_NODE_UNREF(privdata->node);
  440         free(privdata, M_NETGRAPH_ETF);
  441         return (0);
  442 }
  443 
  444 /*
  445  * Hook disconnection
  446  *
  447  * For this type, removal of the last link destroys the node
  448  */
  449 static int
  450 ng_etf_disconnect(hook_p hook)
  451 {
  452         const etf_p etfp = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
  453         int i;
  454         struct filter *fil1, *fil2;
  455 
  456         /* purge any rules that refer to this filter */
  457         for (i = 0; i < HASHSIZE; i++) {
  458                 fil1 = LIST_FIRST(&etfp->hashtable[i]);
  459                 while (fil1 != NULL) {
  460                         fil2 = LIST_NEXT(fil1, next);
  461                         if (fil1->match_hook == hook) {
  462                                 LIST_REMOVE(fil1, next);
  463                                 free(fil1, M_NETGRAPH_ETF);
  464                         }
  465                         fil1 = fil2;
  466                 }
  467         }
  468                 
  469         /* If it's not one of the special hooks, then free it */
  470         if (hook == etfp->downstream_hook.hook) {
  471                 etfp->downstream_hook.hook = NULL;
  472         } else if (hook == etfp->nomatch_hook.hook) {
  473                 etfp->nomatch_hook.hook = NULL;
  474         } else {
  475                 if (NG_HOOK_PRIVATE(hook)) /* Paranoia */
  476                         free(NG_HOOK_PRIVATE(hook), M_NETGRAPH_ETF);
  477         }
  478 
  479         NG_HOOK_SET_PRIVATE(hook, NULL);
  480 
  481         if ((NG_NODE_NUMHOOKS(NG_HOOK_NODE(hook)) == 0)
  482         && (NG_NODE_IS_VALID(NG_HOOK_NODE(hook)))) /* already shutting down? */
  483                 ng_rmnode_self(NG_HOOK_NODE(hook));
  484         return (0);
  485 }
  486 

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