sys/netgraph7/ng_ipfw.c

   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: src/sys/netgraph/ng_ipfw.c,v 1.9 2006/02/14 15:22:24 ru Exp $
  27  */
  28
  29 #include <sys/param.h>
  30 #include <sys/systm.h>
  31 #include <sys/kernel.h>
  32 #include <sys/mbuf.h>
  33 #include <sys/malloc.h>
  34 #include <sys/ctype.h>
  35 #include <sys/errno.h>
  36 #include <sys/socket.h>
  37 #include <sys/syslog.h>
  38
  39 #include <net/if.h>
  40
  41 #include <netinet/in.h>
  42 #include <netinet/in_systm.h>
  43 #include <netinet/in_var.h>
  44 #include <netinet/ip_fw.h>
  45 #include <netinet/ip.h>
  46 #include <netinet/ip_var.h>
  47
  48 #include <netgraph/ng_message.h>
  49 #include <netgraph/ng_parse.h>
  50 #include <netgraph/ng_ipfw.h>
  51 #include <netgraph/netgraph.h>
  52
  53 static int              ng_ipfw_mod_event(module_t mod, int event, void *data);
  54 static ng_constructor_t ng_ipfw_constructor;
  55 static ng_shutdown_t    ng_ipfw_shutdown;
  56 static ng_newhook_t     ng_ipfw_newhook;
  57 static ng_connect_t     ng_ipfw_connect;
  58 static ng_findhook_t    ng_ipfw_findhook;
  59 static ng_rcvdata_t     ng_ipfw_rcvdata;
  60 static ng_disconnect_t  ng_ipfw_disconnect;
  61
  62 static hook_p           ng_ipfw_findhook1(node_p, u_int16_t );
  63 static int              ng_ipfw_input(struct mbuf **, int, struct ip_fw_args *,
  64                             int);
  65
  66 /* We have only one node */
  67 static node_p   fw_node;
  68
  69 /* Netgraph node type descriptor */
  70 static struct ng_type ng_ipfw_typestruct = {
  71         .version =      NG_ABI_VERSION,
  72         .name =         NG_IPFW_NODE_TYPE,
  73         .mod_event =    ng_ipfw_mod_event,
  74         .constructor =  ng_ipfw_constructor,
  75         .shutdown =     ng_ipfw_shutdown,
  76         .newhook =      ng_ipfw_newhook,
  77         .connect =      ng_ipfw_connect,
  78         .findhook =     ng_ipfw_findhook,
  79         .rcvdata =      ng_ipfw_rcvdata,
  80         .disconnect =   ng_ipfw_disconnect,
  81 };
  82 NETGRAPH_INIT(ipfw, &ng_ipfw_typestruct);
  83 MODULE_DEPEND(ng_ipfw, ipfw, 2, 2, 2);
  84
  85 /* Information we store for each hook */
  86 struct ng_ipfw_hook_priv {
  87         hook_p          hook;
  88         u_int16_t       rulenum;
  89 };
  90 typedef struct ng_ipfw_hook_priv *hpriv_p;
  91
  92 static int
  93 ng_ipfw_mod_event(module_t mod, int event, void *data)
  94 {
  95         int error = 0;
  96
  97         switch (event) {
  98         case MOD_LOAD:
  99
 100                 if (ng_ipfw_input_p != NULL) {
 101                         error = EEXIST;
 102                         break;
 103                 }
 104
 105                 /* Setup node without any private data */
 106                 if ((error = ng_make_node_common(&ng_ipfw_typestruct, &fw_node))
 107                     != 0) {
 108                         log(LOG_ERR, "%s: can't create ng_ipfw node", __func__);
 109                         break;
 110                 };
 111
 112                 /* Try to name node */
 113                 if (ng_name_node(fw_node, "ipfw") != 0)
 114                         log(LOG_WARNING, "%s: failed to name node \"ipfw\"",
 115                             __func__);
 116
 117                 /* Register hook */
 118                 ng_ipfw_input_p = ng_ipfw_input;
 119                 break;
 120
 121         case MOD_UNLOAD:
 122                  /*
 123                   * This won't happen if a node exists.
 124                   * ng_ipfw_input_p is already cleared.
 125                   */
 126                 break;
 127
 128         default:
 129                 error = EOPNOTSUPP;
 130                 break;
 131         }
 132
 133         return (error);
 134 }
 135
 136 static int
 137 ng_ipfw_constructor(node_p node)
 138 {
 139         return (EINVAL);        /* Only one node */
 140 }
 141
 142 static int
 143 ng_ipfw_newhook(node_p node, hook_p hook, const char *name)
 144 {
 145         hpriv_p hpriv;
 146         u_int16_t rulenum;
 147         const char *cp;
 148         char *endptr;
 149
 150         /* Protect from leading zero */
 151         if (name[0] == '0' && name[1] != '\0')
 152                 return (EINVAL);
 153
 154         /* Check that name contains only digits */
 155         for (cp = name; *cp != '\0'; cp++)
 156                 if (!isdigit(*cp))
 157                         return (EINVAL);
 158
 159         /* Convert it to integer */
 160         rulenum = (u_int16_t)strtol(name, &endptr, 10);
 161         if (*endptr != '\0')
 162                 return (EINVAL);
 163
 164         /* Allocate memory for this hook's private data */
 165         MALLOC(hpriv, hpriv_p, sizeof(*hpriv), M_NETGRAPH, M_NOWAIT | M_ZERO);
 166         if (hpriv== NULL)
 167                 return (ENOMEM);
 168
 169         hpriv->hook = hook;
 170         hpriv->rulenum = rulenum;
 171
 172         NG_HOOK_SET_PRIVATE(hook, hpriv);
 173
 174         return(0);
 175 }
 176
 177 /*
 178  * Set hooks into queueing mode, to avoid recursion between
 179  * netgraph layer and ip_{input,output}.
 180  */
 181 static int
 182 ng_ipfw_connect(hook_p hook)
 183 {
 184         NG_HOOK_FORCE_QUEUE(hook);
 185         return (0);
 186 }
 187
 188 /* Look up hook by name */
 189 hook_p
 190 ng_ipfw_findhook(node_p node, const char *name)
 191 {
 192         u_int16_t n;    /* numeric representation of hook */
 193         char *endptr;
 194
 195         n = (u_int16_t)strtol(name, &endptr, 10);
 196         if (*endptr != '\0')
 197                 return NULL;
 198         return ng_ipfw_findhook1(node, n);
 199 }
 200
 201 /* Look up hook by rule number */
 202 static hook_p
 203 ng_ipfw_findhook1(node_p node, u_int16_t rulenum)
 204 {
 205         hook_p  hook;
 206         hpriv_p hpriv;
 207
 208         LIST_FOREACH(hook, &node->nd_hooks, hk_hooks) {
 209                 hpriv = NG_HOOK_PRIVATE(hook);
 210                 if (NG_HOOK_IS_VALID(hook) && (hpriv->rulenum == rulenum))
 211                         return (hook);
 212         }
 213
 214         return (NULL);
 215 }
 216
 217
 218 static int
 219 ng_ipfw_rcvdata(hook_p hook, item_p item)
 220 {
 221         struct ng_ipfw_tag      *ngit;
 222         struct mbuf *m;
 223
 224         NGI_GET_M(item, m);
 225         NG_FREE_ITEM(item);
 226
 227         if ((ngit = (struct ng_ipfw_tag *)m_tag_locate(m, NGM_IPFW_COOKIE, 0,
 228             NULL)) == NULL) {
 229                 NG_FREE_M(m);
 230                 return (EINVAL);        /* XXX: find smth better */
 231         };
 232
 233         switch (ngit->dir) {
 234         case NG_IPFW_OUT:
 235             {
 236                 struct ip *ip;
 237
 238                 if (m->m_len < sizeof(struct ip) &&
 239                     (m = m_pullup(m, sizeof(struct ip))) == NULL)
 240                         return (EINVAL);
 241
 242                 ip = mtod(m, struct ip *);
 243
 244                 ip->ip_len = ntohs(ip->ip_len);
 245                 ip->ip_off = ntohs(ip->ip_off);
 246
 247                 return ip_output(m, NULL, NULL, IP_FORWARDING, NULL, NULL);
 248             }
 249         case NG_IPFW_IN:
 250                 ip_input(m);
 251                 return (0);
 252         default:
 253                 panic("ng_ipfw_rcvdata: bad dir %u", ngit->dir);
 254         }
 255
 256         /* not reached */
 257         return (0);
 258 }
 259
 260 static int
 261 ng_ipfw_input(struct mbuf **m0, int dir, struct ip_fw_args *fwa, int tee)
 262 {
 263         struct mbuf *m;
 264         struct ng_ipfw_tag *ngit;
 265         struct ip *ip;
 266         hook_p  hook;
 267         int error = 0;
 268
 269         /*
 270          * Node must be loaded and corresponding hook must be present.
 271          */
 272         if (fw_node == NULL ||
 273            (hook = ng_ipfw_findhook1(fw_node, fwa->cookie)) == NULL) {
 274                 if (tee == 0)
 275                         m_freem(*m0);
 276                 return (ESRCH);         /* no hook associated with this rule */
 277         }
 278
 279         /*
 280          * We have two modes: in normal mode we add a tag to packet, which is
 281          * important to return packet back to IP stack. In tee mode we make
 282          * a copy of a packet and forward it into netgraph without a tag.
 283          */
 284         if (tee == 0) {
 285                 m = *m0;
 286                 *m0 = NULL;     /* it belongs now to netgraph */
 287
 288                 if ((ngit = (struct ng_ipfw_tag *)m_tag_alloc(NGM_IPFW_COOKIE,
 289                     0, TAGSIZ, M_NOWAIT|M_ZERO)) == NULL) {
 290                         m_freem(m);
 291                         return (ENOMEM);
 292                 }
 293                 ngit->rule = fwa->rule;
 294                 ngit->dir = dir;
 295                 ngit->ifp = fwa->oif;
 296                 m_tag_prepend(m, &ngit->mt);
 297
 298         } else
 299                 if ((m = m_dup(*m0, M_DONTWAIT)) == NULL)
 300                         return (ENOMEM);        /* which is ignored */
 301
 302         if (m->m_len < sizeof(struct ip) &&
 303             (m = m_pullup(m, sizeof(struct ip))) == NULL)
 304                 return (EINVAL);
 305
 306         ip = mtod(m, struct ip *);
 307         ip->ip_len = htons(ip->ip_len);
 308         ip->ip_off = htons(ip->ip_off);
 309
 310         NG_SEND_DATA_ONLY(error, hook, m);
 311
 312         return (error);
 313 }
 314
 315 static int
 316 ng_ipfw_shutdown(node_p node)
 317 {
 318
 319         /*
 320          * After our single node has been removed,
 321          * the only thing that can be done is
 322          * 'kldunload ng_ipfw.ko'
 323          */
 324         ng_ipfw_input_p = NULL;
 325         NG_NODE_UNREF(node);
 326         return (0);
 327 }
 328
 329 static int
 330 ng_ipfw_disconnect(hook_p hook)
 331 {
 332         const hpriv_p hpriv = NG_HOOK_PRIVATE(hook);
 333
 334         FREE(hpriv, M_NETGRAPH);
 335         NG_HOOK_SET_PRIVATE(hook, NULL);
 336
 337         return (0);
 338 }