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  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
    7  *
    8  * Copyright (c) 2001, FreeBSD Incorporated 
    9  * All rights reserved.
   10  *
   11  * Redistribution and use in source and binary forms, with or without
   12  * modification, are permitted provided that the following conditions
   13  * are met:
   14  * 1. Redistributions of source code must retain the above copyright
   15  *    notice unmodified, this list of conditions, and the following
   16  *    disclaimer.
   17  * 2. Redistributions in binary form must reproduce the above copyright
   18  *    notice, this list of conditions and the following disclaimer in the
   19  *    documentation and/or other materials provided with the distribution.
   20  *
   21  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   31  * SUCH DAMAGE.
   32  *
   33  * Author: Julian Elischer <julian@freebsd.org>
   34  *
   35  * $FreeBSD: stable/12/sys/netgraph/ng_etf.c 326272 2017-11-27 15:23:17Z pfg $
   36  */
   37 
   38 #include <sys/param.h>
   39 #include <sys/systm.h>
   40 #include <sys/kernel.h>
   41 #include <sys/mbuf.h>
   42 #include <sys/malloc.h>
   43 #include <sys/ctype.h>
   44 #include <sys/errno.h>
   45 #include <sys/queue.h>
   46 #include <sys/syslog.h>
   47 
   48 #include <net/ethernet.h>
   49 
   50 #include <netgraph/ng_message.h>
   51 #include <netgraph/ng_parse.h>
   52 #include <netgraph/ng_etf.h>
   53 #include <netgraph/netgraph.h>
   54 
   55 /* If you do complicated mallocs you may want to do this */
   56 /* and use it for your mallocs */
   57 #ifdef NG_SEPARATE_MALLOC
   58 static MALLOC_DEFINE(M_NETGRAPH_ETF, "netgraph_etf", "netgraph etf node ");
   59 #else
   60 #define M_NETGRAPH_ETF M_NETGRAPH
   61 #endif
   62 
   63 /*
   64  * This section contains the netgraph method declarations for the
   65  * etf node. These methods define the netgraph 'type'.
   66  */
   67 
   68 static ng_constructor_t ng_etf_constructor;
   69 static ng_rcvmsg_t      ng_etf_rcvmsg;
   70 static ng_shutdown_t    ng_etf_shutdown;
   71 static ng_newhook_t     ng_etf_newhook;
   72 static ng_rcvdata_t     ng_etf_rcvdata;  /* note these are both ng_rcvdata_t */
   73 static ng_disconnect_t  ng_etf_disconnect;
   74 
   75 /* Parse type for struct ng_etfstat */
   76 static const struct ng_parse_struct_field ng_etf_stat_type_fields[]
   77         = NG_ETF_STATS_TYPE_INFO;
   78 static const struct ng_parse_type ng_etf_stat_type = {
   79         &ng_parse_struct_type,
   80         &ng_etf_stat_type_fields
   81 };
   82 /* Parse type for struct ng_setfilter */
   83 static const struct ng_parse_struct_field ng_etf_filter_type_fields[]
   84         = NG_ETF_FILTER_TYPE_INFO;
   85 static const struct ng_parse_type ng_etf_filter_type = {
   86         &ng_parse_struct_type,
   87         &ng_etf_filter_type_fields
   88 };
   89 
   90 /* List of commands and how to convert arguments to/from ASCII */
   91 static const struct ng_cmdlist ng_etf_cmdlist[] = {
   92         {
   93           NGM_ETF_COOKIE,
   94           NGM_ETF_GET_STATUS,
   95           "getstatus",
   96           NULL,
   97           &ng_etf_stat_type,
   98         },
   99         {
  100           NGM_ETF_COOKIE,
  101           NGM_ETF_SET_FLAG,
  102           "setflag",
  103           &ng_parse_int32_type,
  104           NULL
  105         },
  106         {
  107           NGM_ETF_COOKIE,
  108           NGM_ETF_SET_FILTER,
  109           "setfilter",
  110           &ng_etf_filter_type,
  111           NULL
  112         },
  113         { 0 }
  114 };
  115 
  116 /* Netgraph node type descriptor */
  117 static struct ng_type typestruct = {
  118         .version =      NG_ABI_VERSION,
  119         .name =         NG_ETF_NODE_TYPE,
  120         .constructor =  ng_etf_constructor,
  121         .rcvmsg =       ng_etf_rcvmsg,
  122         .shutdown =     ng_etf_shutdown,
  123         .newhook =      ng_etf_newhook,
  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         privdata = malloc(sizeof(*privdata), M_NETGRAPH_ETF, M_WAITOK | M_ZERO);
  186         for (i = 0; i < HASHSIZE; i++) {
  187                 LIST_INIT((privdata->hashtable + i));
  188         }
  189 
  190         /* Link structs together; this counts as our one reference to node */
  191         NG_NODE_SET_PRIVATE(node, privdata);
  192         privdata->node = node;
  193         return (0);
  194 }
  195 
  196 /*
  197  * Give our ok for a hook to be added...
  198  * All names are ok. Two names are special.
  199  */
  200 static int
  201 ng_etf_newhook(node_p node, hook_p hook, const char *name)
  202 {
  203         const etf_p etfp = NG_NODE_PRIVATE(node);
  204         struct ETF_hookinfo *hpriv;
  205 
  206         if (strcmp(name, NG_ETF_HOOK_DOWNSTREAM) == 0) {
  207                 etfp->downstream_hook.hook = hook;
  208                 NG_HOOK_SET_PRIVATE(hook, &etfp->downstream_hook);
  209                 etfp->packets_in = 0;
  210                 etfp->packets_out = 0;
  211         } else if (strcmp(name, NG_ETF_HOOK_NOMATCH) == 0) {
  212                 etfp->nomatch_hook.hook = hook;
  213                 NG_HOOK_SET_PRIVATE(hook, &etfp->nomatch_hook);
  214         } else {
  215                 /*
  216                  * Any other hook name is valid and can
  217                  * later be associated with a filter rule.
  218                  */
  219                 hpriv = malloc(sizeof(*hpriv),
  220                         M_NETGRAPH_ETF, M_NOWAIT | M_ZERO);
  221                 if (hpriv == NULL) {
  222                         return (ENOMEM);
  223                 }
  224 
  225                 NG_HOOK_SET_PRIVATE(hook, hpriv);
  226                 hpriv->hook = hook;
  227         }
  228         return(0);
  229 }
  230 
  231 /*
  232  * Get a netgraph control message.
  233  * We actually receive a queue item that has a pointer to the message.
  234  * If we free the item, the message will be freed too, unless we remove
  235  * it from the item using NGI_GET_MSG();
  236  * The return address is also stored in the item, as an ng_ID_t,
  237  * accessible as NGI_RETADDR(item);
  238  * Check it is one we understand. If needed, send a response.
  239  * We could save the address for an async action later, but don't here.
  240  * Always free the message.
  241  * The response should be in a malloc'd region that the caller can 'free'.
  242  * The NG_MKRESPONSE macro does all this for us.
  243  * A response is not required.
  244  * Theoretically you could respond defferently to old message types if
  245  * the cookie in the header didn't match what we consider to be current
  246  * (so that old userland programs could continue to work).
  247  */
  248 static int
  249 ng_etf_rcvmsg(node_p node, item_p item, hook_p lasthook)
  250 {
  251         const etf_p etfp = NG_NODE_PRIVATE(node);
  252         struct ng_mesg *resp = NULL;
  253         int error = 0;
  254         struct ng_mesg *msg;
  255 
  256         NGI_GET_MSG(item, msg);
  257         /* Deal with message according to cookie and command */
  258         switch (msg->header.typecookie) {
  259         case NGM_ETF_COOKIE: 
  260                 switch (msg->header.cmd) {
  261                 case NGM_ETF_GET_STATUS:
  262                     {
  263                         struct ng_etfstat *stats;
  264 
  265                         NG_MKRESPONSE(resp, msg, sizeof(*stats), M_NOWAIT);
  266                         if (!resp) {
  267                                 error = ENOMEM;
  268                                 break;
  269                         }
  270                         stats = (struct ng_etfstat *) resp->data;
  271                         stats->packets_in = etfp->packets_in;
  272                         stats->packets_out = etfp->packets_out;
  273                         break;
  274                     }
  275                 case NGM_ETF_SET_FLAG:
  276                         if (msg->header.arglen != sizeof(u_int32_t)) {
  277                                 error = EINVAL;
  278                                 break;
  279                         }
  280                         etfp->flags = *((u_int32_t *) msg->data);
  281                         break;
  282                 case NGM_ETF_SET_FILTER:
  283                         {
  284                                 struct ng_etffilter *f;
  285                                 struct filter *fil;
  286                                 hook_p  hook;
  287 
  288                                 /* Check message long enough for this command */
  289                                 if (msg->header.arglen != sizeof(*f)) {
  290                                         error = EINVAL;
  291                                         break;
  292                                 }
  293 
  294                                 /* Make sure hook referenced exists */
  295                                 f = (struct ng_etffilter *)msg->data;
  296                                 hook = ng_findhook(node, f->matchhook);
  297                                 if (hook == NULL) {
  298                                         error = ENOENT;
  299                                         break;
  300                                 }
  301 
  302                                 /* and is not the downstream hook */
  303                                 if (hook == etfp->downstream_hook.hook) {
  304                                         error = EINVAL;
  305                                         break;
  306                                 }
  307 
  308                                 /* Check we don't already trap this ethertype */
  309                                 if (ng_etf_findentry(etfp,
  310                                                 htons(f->ethertype))) {
  311                                         error = EEXIST;
  312                                         break;
  313                                 }
  314 
  315                                 /*
  316                                  * Ok, make the filter and put it in the 
  317                                  * hashtable ready for matching.
  318                                  */
  319                                 fil = malloc(sizeof(*fil),
  320                                         M_NETGRAPH_ETF, M_NOWAIT | M_ZERO);
  321                                 if (fil == NULL) {
  322                                         error = ENOMEM;
  323                                         break;
  324                                 }
  325 
  326                                 fil->match_hook = hook;
  327                                 fil->ethertype = htons(f->ethertype);
  328                                 LIST_INSERT_HEAD( etfp->hashtable
  329                                         + HASH(fil->ethertype),
  330                                                 fil, next);
  331                         }
  332                         break;
  333                 default:
  334                         error = EINVAL;         /* unknown command */
  335                         break;
  336                 }
  337                 break;
  338         default:
  339                 error = EINVAL;                 /* unknown cookie type */
  340                 break;
  341         }
  342 
  343         /* Take care of synchronous response, if any */
  344         NG_RESPOND_MSG(error, node, item, resp);
  345         /* Free the message and return */
  346         NG_FREE_MSG(msg);
  347         return(error);
  348 }
  349 
  350 /*
  351  * Receive data, and do something with it.
  352  * Actually we receive a queue item which holds the data.
  353  * If we free the item it will also free the data unless we have previously
  354  * disassociated it using the NGI_GET_etf() macro.
  355  * Possibly send it out on another link after processing.
  356  * Possibly do something different if it comes from different
  357  * hooks. The caller will never free m , so if we use up this data
  358  * or abort we must free it.
  359  *
  360  * If we want, we may decide to force this data to be queued and reprocessed
  361  * at the netgraph NETISR time.
  362  * We would do that by setting the HK_QUEUE flag on our hook. We would do that
  363  * in the connect() method. 
  364  */
  365 static int
  366 ng_etf_rcvdata(hook_p hook, item_p item )
  367 {
  368         const etf_p etfp = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
  369         struct ether_header *eh;
  370         int error = 0;
  371         struct mbuf *m;
  372         u_int16_t ethertype;
  373         struct filter *fil;
  374 
  375         if (NG_HOOK_PRIVATE(hook) == NULL) { /* Shouldn't happen but.. */
  376                 NG_FREE_ITEM(item);
  377         }
  378 
  379         /* 
  380          * Everything not from the downstream hook goes to the
  381          * downstream hook. But only if it matches the ethertype
  382          * of the source hook. Un matching must go to/from 'nomatch'.
  383          */
  384 
  385         /* Make sure we have an entire header */
  386         NGI_GET_M(item, m);
  387         if (m->m_len < sizeof(*eh) ) {
  388                 m = m_pullup(m, sizeof(*eh));
  389                 if (m == NULL) {
  390                         NG_FREE_ITEM(item);
  391                         return(EINVAL);
  392                 }
  393         }
  394 
  395         eh = mtod(m, struct ether_header *);
  396         ethertype = eh->ether_type;
  397         fil = ng_etf_findentry(etfp, ethertype);
  398 
  399         /*
  400          * if from downstream, select between a match hook or
  401          * the nomatch hook
  402          */
  403         if (hook == etfp->downstream_hook.hook) {
  404                 etfp->packets_in++;
  405                 if (fil && fil->match_hook) {
  406                         NG_FWD_NEW_DATA(error, item, fil->match_hook, m);
  407                 } else {
  408                         NG_FWD_NEW_DATA(error, item,etfp->nomatch_hook.hook, m);
  409                 }
  410         } else {
  411                 /* 
  412                  * It must be heading towards the downstream.
  413                  * Check that it's ethertype matches 
  414                  * the filters for it's input hook.
  415                  * If it doesn't have one, check it's from nomatch.
  416                  */
  417                 if ((fil && (fil->match_hook != hook))
  418                 || ((fil == NULL) && (hook != etfp->nomatch_hook.hook))) {
  419                         NG_FREE_ITEM(item);
  420                         NG_FREE_M(m);
  421                         return (EPROTOTYPE);
  422                 }
  423                 NG_FWD_NEW_DATA( error, item, etfp->downstream_hook.hook, m);
  424                 if (error == 0) {
  425                         etfp->packets_out++;
  426                 }
  427         }
  428         return (error);
  429 }
  430 
  431 /*
  432  * Do local shutdown processing..
  433  * All our links and the name have already been removed.
  434  */
  435 static int
  436 ng_etf_shutdown(node_p node)
  437 {
  438         const etf_p privdata = NG_NODE_PRIVATE(node);
  439 
  440         NG_NODE_SET_PRIVATE(node, NULL);
  441         NG_NODE_UNREF(privdata->node);
  442         free(privdata, M_NETGRAPH_ETF);
  443         return (0);
  444 }
  445 
  446 /*
  447  * Hook disconnection
  448  *
  449  * For this type, removal of the last link destroys the node
  450  */
  451 static int
  452 ng_etf_disconnect(hook_p hook)
  453 {
  454         const etf_p etfp = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
  455         int i;
  456         struct filter *fil1, *fil2;
  457 
  458         /* purge any rules that refer to this filter */
  459         for (i = 0; i < HASHSIZE; i++) {
  460                 fil1 = LIST_FIRST(&etfp->hashtable[i]);
  461                 while (fil1 != NULL) {
  462                         fil2 = LIST_NEXT(fil1, next);
  463                         if (fil1->match_hook == hook) {
  464                                 LIST_REMOVE(fil1, next);
  465                                 free(fil1, M_NETGRAPH_ETF);
  466                         }
  467                         fil1 = fil2;
  468                 }
  469         }
  470                 
  471         /* If it's not one of the special hooks, then free it */
  472         if (hook == etfp->downstream_hook.hook) {
  473                 etfp->downstream_hook.hook = NULL;
  474         } else if (hook == etfp->nomatch_hook.hook) {
  475                 etfp->nomatch_hook.hook = NULL;
  476         } else {
  477                 if (NG_HOOK_PRIVATE(hook)) /* Paranoia */
  478                         free(NG_HOOK_PRIVATE(hook), M_NETGRAPH_ETF);
  479         }
  480 
  481         NG_HOOK_SET_PRIVATE(hook, NULL);
  482 
  483         if ((NG_NODE_NUMHOOKS(NG_HOOK_NODE(hook)) == 0)
  484         && (NG_NODE_IS_VALID(NG_HOOK_NODE(hook)))) /* already shutting down? */
  485                 ng_rmnode_self(NG_HOOK_NODE(hook));
  486         return (0);
  487 }
  488 

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