The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/netgraph/ng_ipfw.c

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    1 /*-
    2  * Copyright 2005, Gleb Smirnoff <glebius@FreeBSD.org>
    3  * 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  *
   14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   24  * SUCH DAMAGE.
   25  *
   26  * $FreeBSD: releng/11.0/sys/netgraph/ng_ipfw.c 297793 2016-04-10 23:07:00Z pfg $
   27  */
   28 
   29 #include "opt_inet.h"
   30 #include "opt_inet6.h"
   31 
   32 #include <sys/param.h>
   33 #include <sys/systm.h>
   34 #include <sys/kernel.h>
   35 #include <sys/lock.h>
   36 #include <sys/mbuf.h>
   37 #include <sys/malloc.h>
   38 #include <sys/ctype.h>
   39 #include <sys/errno.h>
   40 #include <sys/rwlock.h>
   41 #include <sys/socket.h>
   42 #include <sys/syslog.h>
   43 
   44 #include <net/if.h>
   45 #include <net/if_var.h>
   46 
   47 #include <netinet/in.h>
   48 #include <netinet/in_systm.h>
   49 #include <netinet/in_var.h>
   50 #include <netinet/ip_var.h>
   51 #include <netinet/ip_fw.h>
   52 #include <netinet/ip.h>
   53 #include <netinet/ip6.h>
   54 #include <netinet6/ip6_var.h>
   55 
   56 #include <netpfil/ipfw/ip_fw_private.h>
   57 
   58 #include <netgraph/ng_message.h>
   59 #include <netgraph/ng_parse.h>
   60 #include <netgraph/ng_ipfw.h>
   61 #include <netgraph/netgraph.h>
   62 
   63 static int              ng_ipfw_mod_event(module_t mod, int event, void *data);
   64 static ng_constructor_t ng_ipfw_constructor;
   65 static ng_shutdown_t    ng_ipfw_shutdown;
   66 static ng_newhook_t     ng_ipfw_newhook;
   67 static ng_connect_t     ng_ipfw_connect;
   68 static ng_findhook_t    ng_ipfw_findhook;
   69 static ng_rcvdata_t     ng_ipfw_rcvdata;
   70 static ng_disconnect_t  ng_ipfw_disconnect;
   71 
   72 static hook_p           ng_ipfw_findhook1(node_p, u_int16_t );
   73 static int              ng_ipfw_input(struct mbuf **, int, struct ip_fw_args *,
   74                             int);
   75 
   76 /* We have only one node */
   77 static node_p   fw_node;
   78 
   79 /* Netgraph node type descriptor */
   80 static struct ng_type ng_ipfw_typestruct = {
   81         .version =      NG_ABI_VERSION,
   82         .name =         NG_IPFW_NODE_TYPE,
   83         .mod_event =    ng_ipfw_mod_event,
   84         .constructor =  ng_ipfw_constructor,
   85         .shutdown =     ng_ipfw_shutdown,
   86         .newhook =      ng_ipfw_newhook,
   87         .connect =      ng_ipfw_connect,
   88         .findhook =     ng_ipfw_findhook,
   89         .rcvdata =      ng_ipfw_rcvdata,
   90         .disconnect =   ng_ipfw_disconnect,
   91 };
   92 NETGRAPH_INIT(ipfw, &ng_ipfw_typestruct);
   93 MODULE_DEPEND(ng_ipfw, ipfw, 3, 3, 3);
   94 
   95 /* Information we store for each hook */
   96 struct ng_ipfw_hook_priv {
   97         hook_p          hook;
   98         u_int16_t       rulenum;
   99 };
  100 typedef struct ng_ipfw_hook_priv *hpriv_p;
  101 
  102 static int
  103 ng_ipfw_mod_event(module_t mod, int event, void *data)
  104 {
  105         int error = 0;
  106 
  107         switch (event) {
  108         case MOD_LOAD:
  109 
  110                 if (ng_ipfw_input_p != NULL) {
  111                         error = EEXIST;
  112                         break;
  113                 }
  114 
  115                 /* Setup node without any private data */
  116                 if ((error = ng_make_node_common(&ng_ipfw_typestruct, &fw_node))
  117                     != 0) {
  118                         log(LOG_ERR, "%s: can't create ng_ipfw node", __func__);
  119                         break;
  120                 }
  121 
  122                 /* Try to name node */
  123                 if (ng_name_node(fw_node, "ipfw") != 0)
  124                         log(LOG_WARNING, "%s: failed to name node \"ipfw\"",
  125                             __func__);
  126 
  127                 /* Register hook */
  128                 ng_ipfw_input_p = ng_ipfw_input;
  129                 break;
  130 
  131         case MOD_UNLOAD:
  132                  /*
  133                   * This won't happen if a node exists.
  134                   * ng_ipfw_input_p is already cleared.
  135                   */
  136                 break;
  137 
  138         default:
  139                 error = EOPNOTSUPP;
  140                 break;
  141         }
  142 
  143         return (error);
  144 }
  145 
  146 static int
  147 ng_ipfw_constructor(node_p node)
  148 {
  149         return (EINVAL);        /* Only one node */
  150 }
  151 
  152 static int
  153 ng_ipfw_newhook(node_p node, hook_p hook, const char *name)
  154 {
  155         hpriv_p hpriv;
  156         u_int16_t rulenum;
  157         const char *cp;
  158         char *endptr;
  159 
  160         /* Protect from leading zero */
  161         if (name[0] == '' && name[1] != '\0')
  162                 return (EINVAL);
  163 
  164         /* Check that name contains only digits */
  165         for (cp = name; *cp != '\0'; cp++)
  166                 if (!isdigit(*cp))
  167                         return (EINVAL);
  168 
  169         /* Convert it to integer */
  170         rulenum = (u_int16_t)strtol(name, &endptr, 10);
  171         if (*endptr != '\0')
  172                 return (EINVAL);
  173 
  174         /* Allocate memory for this hook's private data */
  175         hpriv = malloc(sizeof(*hpriv), M_NETGRAPH, M_NOWAIT | M_ZERO);
  176         if (hpriv== NULL)
  177                 return (ENOMEM);
  178 
  179         hpriv->hook = hook;
  180         hpriv->rulenum = rulenum;
  181 
  182         NG_HOOK_SET_PRIVATE(hook, hpriv);
  183 
  184         return(0);
  185 }
  186 
  187 /*
  188  * Set hooks into queueing mode, to avoid recursion between
  189  * netgraph layer and ip_{input,output}.
  190  */
  191 static int
  192 ng_ipfw_connect(hook_p hook)
  193 {
  194         NG_HOOK_FORCE_QUEUE(hook);
  195         return (0);
  196 }
  197 
  198 /* Look up hook by name */
  199 static hook_p
  200 ng_ipfw_findhook(node_p node, const char *name)
  201 {
  202         u_int16_t n;    /* numeric representation of hook */
  203         char *endptr;
  204 
  205         n = (u_int16_t)strtol(name, &endptr, 10);
  206         if (*endptr != '\0')
  207                 return NULL;
  208         return ng_ipfw_findhook1(node, n);
  209 }
  210 
  211 /* Look up hook by rule number */
  212 static hook_p
  213 ng_ipfw_findhook1(node_p node, u_int16_t rulenum)
  214 {
  215         hook_p  hook;
  216         hpriv_p hpriv;
  217 
  218         LIST_FOREACH(hook, &node->nd_hooks, hk_hooks) {
  219                 hpriv = NG_HOOK_PRIVATE(hook);
  220                 if (NG_HOOK_IS_VALID(hook) && (hpriv->rulenum == rulenum))
  221                         return (hook);
  222         }
  223 
  224         return (NULL);
  225 }
  226 
  227 
  228 static int
  229 ng_ipfw_rcvdata(hook_p hook, item_p item)
  230 {
  231         struct m_tag *tag;
  232         struct ipfw_rule_ref *r;
  233         struct mbuf *m;
  234         struct ip *ip;
  235 
  236         NGI_GET_M(item, m);
  237         NG_FREE_ITEM(item);
  238 
  239         tag = m_tag_locate(m, MTAG_IPFW_RULE, 0, NULL);
  240         if (tag == NULL) {
  241                 NG_FREE_M(m);
  242                 return (EINVAL);        /* XXX: find smth better */
  243         }
  244 
  245         if (m->m_len < sizeof(struct ip) &&
  246             (m = m_pullup(m, sizeof(struct ip))) == NULL)
  247                 return (ENOBUFS);
  248 
  249         ip = mtod(m, struct ip *);
  250 
  251         r = (struct ipfw_rule_ref *)(tag + 1);
  252         if (r->info & IPFW_INFO_IN) {
  253                 switch (ip->ip_v) {
  254 #ifdef INET
  255                 case IPVERSION:
  256                         ip_input(m);
  257                         return (0);
  258 #endif
  259 #ifdef INET6
  260                 case IPV6_VERSION >> 4:
  261                         ip6_input(m);
  262                         return (0);
  263 #endif
  264                 }
  265         } else {
  266                 switch (ip->ip_v) {
  267 #ifdef INET
  268                 case IPVERSION:
  269                         return (ip_output(m, NULL, NULL, IP_FORWARDING,
  270                             NULL, NULL));
  271 #endif
  272 #ifdef INET6
  273                 case IPV6_VERSION >> 4:
  274                         return (ip6_output(m, NULL, NULL, 0, NULL,
  275                             NULL, NULL));
  276 #endif
  277                 }
  278         }
  279 
  280         /* unknown IP protocol version */
  281         NG_FREE_M(m);
  282         return (EPROTONOSUPPORT);
  283 }
  284 
  285 static int
  286 ng_ipfw_input(struct mbuf **m0, int dir, struct ip_fw_args *fwa, int tee)
  287 {
  288         struct mbuf *m;
  289         struct ip *ip;
  290         hook_p  hook;
  291         int error = 0;
  292 
  293         /*
  294          * Node must be loaded and corresponding hook must be present.
  295          */
  296         if (fw_node == NULL || 
  297            (hook = ng_ipfw_findhook1(fw_node, fwa->rule.info)) == NULL)
  298                 return (ESRCH);         /* no hook associated with this rule */
  299 
  300         /*
  301          * We have two modes: in normal mode we add a tag to packet, which is
  302          * important to return packet back to IP stack. In tee mode we make
  303          * a copy of a packet and forward it into netgraph without a tag.
  304          */
  305         if (tee == 0) {
  306                 struct m_tag *tag;
  307                 struct ipfw_rule_ref *r;
  308                 m = *m0;
  309                 *m0 = NULL;     /* it belongs now to netgraph */
  310 
  311                 tag = m_tag_alloc(MTAG_IPFW_RULE, 0, sizeof(*r),
  312                         M_NOWAIT|M_ZERO);
  313                 if (tag == NULL) {
  314                         m_freem(m);
  315                         return (ENOMEM);
  316                 }
  317                 r = (struct ipfw_rule_ref *)(tag + 1);
  318                 *r = fwa->rule;
  319                 r->info &= IPFW_ONEPASS;  /* keep this info */
  320                 r->info |= dir ? IPFW_INFO_IN : IPFW_INFO_OUT;
  321                 m_tag_prepend(m, tag);
  322 
  323         } else
  324                 if ((m = m_dup(*m0, M_NOWAIT)) == NULL)
  325                         return (ENOMEM);        /* which is ignored */
  326 
  327         if (m->m_len < sizeof(struct ip) &&
  328             (m = m_pullup(m, sizeof(struct ip))) == NULL)
  329                 return (EINVAL);
  330 
  331         ip = mtod(m, struct ip *);
  332 
  333         NG_SEND_DATA_ONLY(error, hook, m);
  334 
  335         return (error);
  336 }
  337 
  338 static int
  339 ng_ipfw_shutdown(node_p node)
  340 {
  341 
  342         /*
  343          * After our single node has been removed,
  344          * the only thing that can be done is
  345          * 'kldunload ng_ipfw.ko'
  346          */
  347         ng_ipfw_input_p = NULL;
  348         NG_NODE_UNREF(node);
  349         return (0);
  350 }
  351 
  352 static int
  353 ng_ipfw_disconnect(hook_p hook)
  354 {
  355         const hpriv_p hpriv = NG_HOOK_PRIVATE(hook);
  356 
  357         free(hpriv, M_NETGRAPH);
  358         NG_HOOK_SET_PRIVATE(hook, NULL);
  359 
  360         return (0);
  361 }

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