sys/netgraph/ng_nat.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
   3  *
   4  * Copyright 2005, Gleb Smirnoff <glebius@FreeBSD.org>
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  26  * SUCH DAMAGE.
  27  *
  28  * $FreeBSD$
  29  */
  30
  31 #include <sys/param.h>
  32 #include <sys/systm.h>
  33 #include <sys/kernel.h>
  34 #include <sys/mbuf.h>
  35 #include <sys/malloc.h>
  36 #include <sys/ctype.h>
  37 #include <sys/errno.h>
  38 #include <sys/syslog.h>
  39
  40 #include <netinet/in_systm.h>
  41 #include <netinet/in.h>
  42 #include <netinet/ip.h>
  43 #include <netinet/ip_var.h>
  44 #include <netinet/tcp.h>
  45 #include <machine/in_cksum.h>
  46
  47 #include <net/dlt.h>
  48 #include <net/ethernet.h>
  49
  50 #include <netinet/libalias/alias.h>
  51 #include <netinet/libalias/alias_local.h>
  52
  53 #include <netgraph/ng_message.h>
  54 #include <netgraph/ng_parse.h>
  55 #include <netgraph/ng_nat.h>
  56 #include <netgraph/netgraph.h>
  57
  58 static ng_constructor_t ng_nat_constructor;
  59 static ng_rcvmsg_t      ng_nat_rcvmsg;
  60 static ng_shutdown_t    ng_nat_shutdown;
  61 static ng_newhook_t     ng_nat_newhook;
  62 static ng_rcvdata_t     ng_nat_rcvdata;
  63 static ng_disconnect_t  ng_nat_disconnect;
  64
  65 static unsigned int     ng_nat_translate_flags(unsigned int x);
  66
  67 /* Parse type for struct ng_nat_mode. */
  68 static const struct ng_parse_struct_field ng_nat_mode_fields[]
  69         = NG_NAT_MODE_INFO;
  70 static const struct ng_parse_type ng_nat_mode_type = {
  71         &ng_parse_struct_type,
  72         &ng_nat_mode_fields
  73 };
  74
  75 /* Parse type for 'description' field in structs. */
  76 static const struct ng_parse_fixedstring_info ng_nat_description_info
  77         = { NG_NAT_DESC_LENGTH };
  78 static const struct ng_parse_type ng_nat_description_type = {
  79         &ng_parse_fixedstring_type,
  80         &ng_nat_description_info
  81 };
  82
  83 /* Parse type for struct ng_nat_redirect_port. */
  84 static const struct ng_parse_struct_field ng_nat_redirect_port_fields[]
  85         = NG_NAT_REDIRECT_PORT_TYPE_INFO(&ng_nat_description_type);
  86 static const struct ng_parse_type ng_nat_redirect_port_type = {
  87         &ng_parse_struct_type,
  88         &ng_nat_redirect_port_fields
  89 };
  90
  91 /* Parse type for struct ng_nat_redirect_addr. */
  92 static const struct ng_parse_struct_field ng_nat_redirect_addr_fields[]
  93         = NG_NAT_REDIRECT_ADDR_TYPE_INFO(&ng_nat_description_type);
  94 static const struct ng_parse_type ng_nat_redirect_addr_type = {
  95         &ng_parse_struct_type,
  96         &ng_nat_redirect_addr_fields
  97 };
  98
  99 /* Parse type for struct ng_nat_redirect_proto. */
 100 static const struct ng_parse_struct_field ng_nat_redirect_proto_fields[]
 101         = NG_NAT_REDIRECT_PROTO_TYPE_INFO(&ng_nat_description_type);
 102 static const struct ng_parse_type ng_nat_redirect_proto_type = {
 103         &ng_parse_struct_type,
 104         &ng_nat_redirect_proto_fields
 105 };
 106
 107 /* Parse type for struct ng_nat_add_server. */
 108 static const struct ng_parse_struct_field ng_nat_add_server_fields[]
 109         = NG_NAT_ADD_SERVER_TYPE_INFO;
 110 static const struct ng_parse_type ng_nat_add_server_type = {
 111         &ng_parse_struct_type,
 112         &ng_nat_add_server_fields
 113 };
 114
 115 /* Parse type for one struct ng_nat_listrdrs_entry. */
 116 static const struct ng_parse_struct_field ng_nat_listrdrs_entry_fields[]
 117         = NG_NAT_LISTRDRS_ENTRY_TYPE_INFO(&ng_nat_description_type);
 118 static const struct ng_parse_type ng_nat_listrdrs_entry_type = {
 119         &ng_parse_struct_type,
 120         &ng_nat_listrdrs_entry_fields
 121 };
 122
 123 /* Parse type for 'redirects' array in struct ng_nat_list_redirects. */
 124 static int
 125 ng_nat_listrdrs_ary_getLength(const struct ng_parse_type *type,
 126         const u_char *start, const u_char *buf)
 127 {
 128         const struct ng_nat_list_redirects *lr;
 129
 130         lr = (const struct ng_nat_list_redirects *)
 131             (buf - offsetof(struct ng_nat_list_redirects, redirects));
 132         return lr->total_count;
 133 }
 134
 135 static const struct ng_parse_array_info ng_nat_listrdrs_ary_info = {
 136         &ng_nat_listrdrs_entry_type,
 137         &ng_nat_listrdrs_ary_getLength,
 138         NULL
 139 };
 140 static const struct ng_parse_type ng_nat_listrdrs_ary_type = {
 141         &ng_parse_array_type,
 142         &ng_nat_listrdrs_ary_info
 143 };
 144
 145 /* Parse type for struct ng_nat_list_redirects. */
 146 static const struct ng_parse_struct_field ng_nat_list_redirects_fields[]
 147         = NG_NAT_LIST_REDIRECTS_TYPE_INFO(&ng_nat_listrdrs_ary_type);
 148 static const struct ng_parse_type ng_nat_list_redirects_type = {
 149         &ng_parse_struct_type,
 150         &ng_nat_list_redirects_fields
 151 };
 152
 153 /* Parse type for struct ng_nat_libalias_info. */
 154 static const struct ng_parse_struct_field ng_nat_libalias_info_fields[]
 155         = NG_NAT_LIBALIAS_INFO;
 156 static const struct ng_parse_type ng_nat_libalias_info_type = {
 157         &ng_parse_struct_type,
 158         &ng_nat_libalias_info_fields
 159 };
 160
 161 /* List of commands and how to convert arguments to/from ASCII. */
 162 static const struct ng_cmdlist ng_nat_cmdlist[] = {
 163         {
 164           NGM_NAT_COOKIE,
 165           NGM_NAT_SET_IPADDR,
 166           "setaliasaddr",
 167           &ng_parse_ipaddr_type,
 168           NULL
 169         },
 170         {
 171           NGM_NAT_COOKIE,
 172           NGM_NAT_SET_MODE,
 173           "setmode",
 174           &ng_nat_mode_type,
 175           NULL
 176         },
 177         {
 178           NGM_NAT_COOKIE,
 179           NGM_NAT_SET_TARGET,
 180           "settarget",
 181           &ng_parse_ipaddr_type,
 182           NULL
 183         },
 184         {
 185           NGM_NAT_COOKIE,
 186           NGM_NAT_REDIRECT_PORT,
 187           "redirectport",
 188           &ng_nat_redirect_port_type,
 189           &ng_parse_uint32_type
 190         },
 191         {
 192           NGM_NAT_COOKIE,
 193           NGM_NAT_REDIRECT_ADDR,
 194           "redirectaddr",
 195           &ng_nat_redirect_addr_type,
 196           &ng_parse_uint32_type
 197         },
 198         {
 199           NGM_NAT_COOKIE,
 200           NGM_NAT_REDIRECT_PROTO,
 201           "redirectproto",
 202           &ng_nat_redirect_proto_type,
 203           &ng_parse_uint32_type
 204         },
 205         {
 206           NGM_NAT_COOKIE,
 207           NGM_NAT_REDIRECT_DYNAMIC,
 208           "redirectdynamic",
 209           &ng_parse_uint32_type,
 210           NULL
 211         },
 212         {
 213           NGM_NAT_COOKIE,
 214           NGM_NAT_REDIRECT_DELETE,
 215           "redirectdelete",
 216           &ng_parse_uint32_type,
 217           NULL
 218         },
 219         {
 220           NGM_NAT_COOKIE,
 221           NGM_NAT_ADD_SERVER,
 222           "addserver",
 223           &ng_nat_add_server_type,
 224           NULL
 225         },
 226         {
 227           NGM_NAT_COOKIE,
 228           NGM_NAT_LIST_REDIRECTS,
 229           "listredirects",
 230           NULL,
 231           &ng_nat_list_redirects_type
 232         },
 233         {
 234           NGM_NAT_COOKIE,
 235           NGM_NAT_PROXY_RULE,
 236           "proxyrule",
 237           &ng_parse_string_type,
 238           NULL
 239         },
 240         {
 241           NGM_NAT_COOKIE,
 242           NGM_NAT_LIBALIAS_INFO,
 243           "libaliasinfo",
 244           NULL,
 245           &ng_nat_libalias_info_type
 246         },
 247         {
 248           NGM_NAT_COOKIE,
 249           NGM_NAT_SET_DLT,
 250           "setdlt",
 251           &ng_parse_uint8_type,
 252           NULL
 253         },
 254         {
 255           NGM_NAT_COOKIE,
 256           NGM_NAT_GET_DLT,
 257           "getdlt",
 258           NULL,
 259           &ng_parse_uint8_type
 260         },
 261         { 0 }
 262 };
 263
 264 /* Netgraph node type descriptor. */
 265 static struct ng_type typestruct = {
 266         .version =      NG_ABI_VERSION,
 267         .name =         NG_NAT_NODE_TYPE,
 268         .constructor =  ng_nat_constructor,
 269         .rcvmsg =       ng_nat_rcvmsg,
 270         .shutdown =     ng_nat_shutdown,
 271         .newhook =      ng_nat_newhook,
 272         .rcvdata =      ng_nat_rcvdata,
 273         .disconnect =   ng_nat_disconnect,
 274         .cmdlist =      ng_nat_cmdlist,
 275 };
 276 NETGRAPH_INIT(nat, &typestruct);
 277 MODULE_DEPEND(ng_nat, libalias, 1, 1, 1);
 278
 279 /* Element for list of redirects. */
 280 struct ng_nat_rdr_lst {
 281         STAILQ_ENTRY(ng_nat_rdr_lst) entries;
 282         struct alias_link       *lnk;
 283         struct ng_nat_listrdrs_entry rdr;
 284 };
 285 STAILQ_HEAD(rdrhead, ng_nat_rdr_lst);
 286
 287 /* Information we store for each node. */
 288 struct ng_nat_priv {
 289         node_p          node;           /* back pointer to node */
 290         hook_p          in;             /* hook for demasquerading */
 291         hook_p          out;            /* hook for masquerading */
 292         struct libalias *lib;           /* libalias handler */
 293         uint32_t        flags;          /* status flags */
 294         uint32_t        rdrcount;       /* number or redirects in list */
 295         uint32_t        nextid;         /* for next in turn in list */
 296         struct rdrhead  redirhead;      /* redirect list header */
 297         uint8_t         dlt;            /* DLT_XXX from bpf.h */
 298 };
 299 typedef struct ng_nat_priv *priv_p;
 300
 301 /* Values of flags */
 302 #define NGNAT_CONNECTED         0x1     /* We have both hooks connected */
 303 #define NGNAT_ADDR_DEFINED      0x2     /* NGM_NAT_SET_IPADDR happened */
 304
 305 static int
 306 ng_nat_constructor(node_p node)
 307 {
 308         priv_p priv;
 309
 310         /* Initialize private descriptor. */
 311         priv = malloc(sizeof(*priv), M_NETGRAPH, M_WAITOK | M_ZERO);
 312
 313         /* Init aliasing engine. */
 314         priv->lib = LibAliasInit(NULL);
 315
 316         /* Set same ports on. */
 317         (void )LibAliasSetMode(priv->lib, PKT_ALIAS_SAME_PORTS,
 318             PKT_ALIAS_SAME_PORTS);
 319
 320         /* Init redirects housekeeping. */
 321         priv->rdrcount = 0;
 322         priv->nextid = 1;
 323         priv->dlt = DLT_RAW;
 324         STAILQ_INIT(&priv->redirhead);
 325
 326         /* Link structs together. */
 327         NG_NODE_SET_PRIVATE(node, priv);
 328         priv->node = node;
 329
 330         /*
 331          * libalias is not thread safe, so our node
 332          * must be single threaded.
 333          */
 334         NG_NODE_FORCE_WRITER(node);
 335
 336         return (0);
 337 }
 338
 339 static int
 340 ng_nat_newhook(node_p node, hook_p hook, const char *name)
 341 {
 342         const priv_p priv = NG_NODE_PRIVATE(node);
 343
 344         if (strcmp(name, NG_NAT_HOOK_IN) == 0) {
 345                 priv->in = hook;
 346         } else if (strcmp(name, NG_NAT_HOOK_OUT) == 0) {
 347                 priv->out = hook;
 348         } else
 349                 return (EINVAL);
 350
 351         if (priv->out != NULL &&
 352             priv->in != NULL)
 353                 priv->flags |= NGNAT_CONNECTED;
 354
 355         return(0);
 356 }
 357
 358 static int
 359 ng_nat_rcvmsg(node_p node, item_p item, hook_p lasthook)
 360 {
 361         const priv_p priv = NG_NODE_PRIVATE(node);
 362         struct ng_mesg *resp = NULL;
 363         struct ng_mesg *msg;
 364         int error = 0;
 365
 366         NGI_GET_MSG(item, msg);
 367
 368         switch (msg->header.typecookie) {
 369         case NGM_NAT_COOKIE:
 370                 switch (msg->header.cmd) {
 371                 case NGM_NAT_SET_IPADDR:
 372                     {
 373                         struct in_addr *const ia = (struct in_addr *)msg->data;
 374
 375                         if (msg->header.arglen < sizeof(*ia)) {
 376                                 error = EINVAL;
 377                                 break;
 378                         }
 379
 380                         LibAliasSetAddress(priv->lib, *ia);
 381
 382                         priv->flags |= NGNAT_ADDR_DEFINED;
 383                     }
 384                         break;
 385                 case NGM_NAT_SET_MODE:
 386                     {
 387                         struct ng_nat_mode *const mode =
 388                             (struct ng_nat_mode *)msg->data;
 389
 390                         if (msg->header.arglen < sizeof(*mode)) {
 391                                 error = EINVAL;
 392                                 break;
 393                         }
 394
 395                         if (LibAliasSetMode(priv->lib,
 396                             ng_nat_translate_flags(mode->flags),
 397                             ng_nat_translate_flags(mode->mask)) < 0) {
 398                                 error = ENOMEM;
 399                                 break;
 400                         }
 401                     }
 402                         break;
 403                 case NGM_NAT_SET_TARGET:
 404                     {
 405                         struct in_addr *const ia = (struct in_addr *)msg->data;
 406
 407                         if (msg->header.arglen < sizeof(*ia)) {
 408                                 error = EINVAL;
 409                                 break;
 410                         }
 411
 412                         LibAliasSetTarget(priv->lib, *ia);
 413                     }
 414                         break;
 415                 case NGM_NAT_REDIRECT_PORT:
 416                     {
 417                         struct ng_nat_rdr_lst *entry;
 418                         struct ng_nat_redirect_port *const rp =
 419                             (struct ng_nat_redirect_port *)msg->data;
 420
 421                         if (msg->header.arglen < sizeof(*rp)) {
 422                                 error = EINVAL;
 423                                 break;
 424                         }
 425
 426                         if ((entry = malloc(sizeof(struct ng_nat_rdr_lst),
 427                             M_NETGRAPH, M_NOWAIT | M_ZERO)) == NULL) {
 428                                 error = ENOMEM;
 429                                 break;
 430                         }
 431
 432                         /* Try actual redirect. */
 433                         entry->lnk = LibAliasRedirectPort(priv->lib,
 434                                 rp->local_addr, htons(rp->local_port),
 435                                 rp->remote_addr, htons(rp->remote_port),
 436                                 rp->alias_addr, htons(rp->alias_port),
 437                                 rp->proto);
 438
 439                         if (entry->lnk == NULL) {
 440                                 error = ENOMEM;
 441                                 free(entry, M_NETGRAPH);
 442                                 break;
 443                         }
 444
 445                         /* Successful, save info in our internal list. */
 446                         entry->rdr.local_addr = rp->local_addr;
 447                         entry->rdr.alias_addr = rp->alias_addr;
 448                         entry->rdr.remote_addr = rp->remote_addr;
 449                         entry->rdr.local_port = rp->local_port;
 450                         entry->rdr.alias_port = rp->alias_port;
 451                         entry->rdr.remote_port = rp->remote_port;
 452                         entry->rdr.proto = rp->proto;
 453                         bcopy(rp->description, entry->rdr.description,
 454                             NG_NAT_DESC_LENGTH);
 455
 456                         /* Safety precaution. */
 457                         entry->rdr.description[NG_NAT_DESC_LENGTH-1] = '\0';
 458
 459                         entry->rdr.id = priv->nextid++;
 460                         priv->rdrcount++;
 461
 462                         /* Link to list of redirects. */
 463                         STAILQ_INSERT_TAIL(&priv->redirhead, entry, entries);
 464
 465                         /* Response with id of newly added entry. */
 466                         NG_MKRESPONSE(resp, msg, sizeof(entry->rdr.id), M_NOWAIT);
 467                         if (resp == NULL) {
 468                                 error = ENOMEM;
 469                                 break;
 470                         }
 471                         bcopy(&entry->rdr.id, resp->data, sizeof(entry->rdr.id));
 472                     }
 473                         break;
 474                 case NGM_NAT_REDIRECT_ADDR:
 475                     {
 476                         struct ng_nat_rdr_lst *entry;
 477                         struct ng_nat_redirect_addr *const ra =
 478                             (struct ng_nat_redirect_addr *)msg->data;
 479
 480                         if (msg->header.arglen < sizeof(*ra)) {
 481                                 error = EINVAL;
 482                                 break;
 483                         }
 484
 485                         if ((entry = malloc(sizeof(struct ng_nat_rdr_lst),
 486                             M_NETGRAPH, M_NOWAIT | M_ZERO)) == NULL) {
 487                                 error = ENOMEM;
 488                                 break;
 489                         }
 490
 491                         /* Try actual redirect. */
 492                         entry->lnk = LibAliasRedirectAddr(priv->lib,
 493                                 ra->local_addr, ra->alias_addr);
 494
 495                         if (entry->lnk == NULL) {
 496                                 error = ENOMEM;
 497                                 free(entry, M_NETGRAPH);
 498                                 break;
 499                         }
 500
 501                         /* Successful, save info in our internal list. */
 502                         entry->rdr.local_addr = ra->local_addr;
 503                         entry->rdr.alias_addr = ra->alias_addr;
 504                         entry->rdr.proto = NG_NAT_REDIRPROTO_ADDR;
 505                         bcopy(ra->description, entry->rdr.description,
 506                             NG_NAT_DESC_LENGTH);
 507
 508                         /* Safety precaution. */
 509                         entry->rdr.description[NG_NAT_DESC_LENGTH-1] = '\0';
 510
 511                         entry->rdr.id = priv->nextid++;
 512                         priv->rdrcount++;
 513
 514                         /* Link to list of redirects. */
 515                         STAILQ_INSERT_TAIL(&priv->redirhead, entry, entries);
 516
 517                         /* Response with id of newly added entry. */
 518                         NG_MKRESPONSE(resp, msg, sizeof(entry->rdr.id), M_NOWAIT);
 519                         if (resp == NULL) {
 520                                 error = ENOMEM;
 521                                 break;
 522                         }
 523                         bcopy(&entry->rdr.id, resp->data, sizeof(entry->rdr.id));
 524                     }
 525                         break;
 526                 case NGM_NAT_REDIRECT_PROTO:
 527                     {
 528                         struct ng_nat_rdr_lst *entry;
 529                         struct ng_nat_redirect_proto *const rp =
 530                             (struct ng_nat_redirect_proto *)msg->data;
 531
 532                         if (msg->header.arglen < sizeof(*rp)) {
 533                                 error = EINVAL;
 534                                 break;
 535                         }
 536
 537                         if ((entry = malloc(sizeof(struct ng_nat_rdr_lst),
 538                             M_NETGRAPH, M_NOWAIT | M_ZERO)) == NULL) {
 539                                 error = ENOMEM;
 540                                 break;
 541                         }
 542
 543                         /* Try actual redirect. */
 544                         entry->lnk = LibAliasRedirectProto(priv->lib,
 545                                 rp->local_addr, rp->remote_addr,
 546                                 rp->alias_addr, rp->proto);
 547
 548                         if (entry->lnk == NULL) {
 549                                 error = ENOMEM;
 550                                 free(entry, M_NETGRAPH);
 551                                 break;
 552                         }
 553
 554                         /* Successful, save info in our internal list. */
 555                         entry->rdr.local_addr = rp->local_addr;
 556                         entry->rdr.alias_addr = rp->alias_addr;
 557                         entry->rdr.remote_addr = rp->remote_addr;
 558                         entry->rdr.proto = rp->proto;
 559                         bcopy(rp->description, entry->rdr.description,
 560                             NG_NAT_DESC_LENGTH);
 561
 562                         /* Safety precaution. */
 563                         entry->rdr.description[NG_NAT_DESC_LENGTH-1] = '\0';
 564
 565                         entry->rdr.id = priv->nextid++;
 566                         priv->rdrcount++;
 567
 568                         /* Link to list of redirects. */
 569                         STAILQ_INSERT_TAIL(&priv->redirhead, entry, entries);
 570
 571                         /* Response with id of newly added entry. */
 572                         NG_MKRESPONSE(resp, msg, sizeof(entry->rdr.id), M_NOWAIT);
 573                         if (resp == NULL) {
 574                                 error = ENOMEM;
 575                                 break;
 576                         }
 577                         bcopy(&entry->rdr.id, resp->data, sizeof(entry->rdr.id));
 578                     }
 579                         break;
 580                 case NGM_NAT_REDIRECT_DYNAMIC:
 581                 case NGM_NAT_REDIRECT_DELETE:
 582                     {
 583                         struct ng_nat_rdr_lst *entry;
 584                         uint32_t *const id = (uint32_t *)msg->data;
 585
 586                         if (msg->header.arglen < sizeof(*id)) {
 587                                 error = EINVAL;
 588                                 break;
 589                         }
 590
 591                         /* Find entry with supplied id. */
 592                         STAILQ_FOREACH(entry, &priv->redirhead, entries) {
 593                                 if (entry->rdr.id == *id)
 594                                         break;
 595                         }
 596
 597                         /* Not found. */
 598                         if (entry == NULL) {
 599                                 error = ENOENT;
 600                                 break;
 601                         }
 602
 603                         if (msg->header.cmd == NGM_NAT_REDIRECT_DYNAMIC) {
 604                                 if (LibAliasRedirectDynamic(priv->lib,
 605                                     entry->lnk) == -1) {
 606                                         error = ENOTTY; /* XXX Something better? */
 607                                         break;
 608                                 }
 609                         } else {        /* NGM_NAT_REDIRECT_DELETE */
 610                                 LibAliasRedirectDelete(priv->lib, entry->lnk);
 611                         }
 612
 613                         /* Delete entry from our internal list. */
 614                         priv->rdrcount--;
 615                         STAILQ_REMOVE(&priv->redirhead, entry, ng_nat_rdr_lst, entries);
 616                         free(entry, M_NETGRAPH);
 617                     }
 618                         break;
 619                 case NGM_NAT_ADD_SERVER:
 620                     {
 621                         struct ng_nat_rdr_lst *entry;
 622                         struct ng_nat_add_server *const as =
 623                             (struct ng_nat_add_server *)msg->data;
 624
 625                         if (msg->header.arglen < sizeof(*as)) {
 626                                 error = EINVAL;
 627                                 break;
 628                         }
 629
 630                         /* Find entry with supplied id. */
 631                         STAILQ_FOREACH(entry, &priv->redirhead, entries) {
 632                                 if (entry->rdr.id == as->id)
 633                                         break;
 634                         }
 635
 636                         /* Not found. */
 637                         if (entry == NULL) {
 638                                 error = ENOENT;
 639                                 break;
 640                         }
 641
 642                         if (LibAliasAddServer(priv->lib, entry->lnk,
 643                             as->addr, htons(as->port)) == -1) {
 644                                 error = ENOMEM;
 645                                 break;
 646                         }
 647
 648                         entry->rdr.lsnat++;
 649                     }
 650                         break;
 651                 case NGM_NAT_LIST_REDIRECTS:
 652                     {
 653                         struct ng_nat_rdr_lst *entry;
 654                         struct ng_nat_list_redirects *ary;
 655                         int i = 0;
 656
 657                         NG_MKRESPONSE(resp, msg, sizeof(*ary) +
 658                             (priv->rdrcount) * sizeof(*entry), M_NOWAIT);
 659                         if (resp == NULL) {
 660                                 error = ENOMEM;
 661                                 break;
 662                         }
 663
 664                         ary = (struct ng_nat_list_redirects *)resp->data;
 665                         ary->total_count = priv->rdrcount;
 666
 667                         STAILQ_FOREACH(entry, &priv->redirhead, entries) {
 668                                 bcopy(&entry->rdr, &ary->redirects[i++],
 669                                     sizeof(struct ng_nat_listrdrs_entry));
 670                         }
 671                     }
 672                         break;
 673                 case NGM_NAT_PROXY_RULE:
 674                     {
 675                         char *cmd = (char *)msg->data;
 676
 677                         if (msg->header.arglen < 6) {
 678                                 error = EINVAL;
 679                                 break;
 680                         }
 681
 682                         if (LibAliasProxyRule(priv->lib, cmd) != 0)
 683                                 error = ENOMEM;
 684                     }
 685                         break;
 686                 case NGM_NAT_LIBALIAS_INFO:
 687                     {
 688                         struct ng_nat_libalias_info *i;
 689
 690                         NG_MKRESPONSE(resp, msg,
 691                             sizeof(struct ng_nat_libalias_info), M_NOWAIT);
 692                         if (resp == NULL) {
 693                                 error = ENOMEM;
 694                                 break;
 695                         }
 696                         i = (struct ng_nat_libalias_info *)resp->data;
 697 #define COPY(F) do {                                            \
 698         if (priv->lib->F >= 0 && priv->lib->F < UINT32_MAX)     \
 699                 i->F = priv->lib->F;                            \
 700         else                                                    \
 701                 i->F = UINT32_MAX;                              \
 702 } while (0)
 703
 704                         COPY(icmpLinkCount);
 705                         COPY(udpLinkCount);
 706                         COPY(tcpLinkCount);
 707                         COPY(pptpLinkCount);
 708                         COPY(sctpLinkCount);
 709                         COPY(protoLinkCount);
 710                         COPY(fragmentIdLinkCount);
 711                         COPY(fragmentPtrLinkCount);
 712                         COPY(sockCount);
 713 #undef COPY
 714                     }
 715                         break;
 716                 case NGM_NAT_SET_DLT:
 717                         if (msg->header.arglen != sizeof(uint8_t)) {
 718                                 error = EINVAL;
 719                                 break;
 720                         }
 721                         switch (*(uint8_t *) msg->data) {
 722                         case DLT_EN10MB:
 723                         case DLT_RAW:
 724                                 priv->dlt = *(uint8_t *) msg->data;
 725                                 break;
 726                         default:
 727                                 error = EINVAL;
 728                                 break;
 729                         }
 730                         break;
 731                 default:
 732                         error = EINVAL;         /* unknown command */
 733                         break;
 734                 }
 735                 break;
 736                 case NGM_NAT_GET_DLT:
 737                         NG_MKRESPONSE(resp, msg, sizeof(uint8_t), M_WAITOK);
 738                         if (resp == NULL) {
 739                                 error = ENOMEM;
 740                                 break;
 741                         }
 742                         *((uint8_t *) resp->data) = priv->dlt;
 743                         break;
 744         default:
 745                 error = EINVAL;                 /* unknown cookie type */
 746                 break;
 747         }
 748
 749         NG_RESPOND_MSG(error, node, item, resp);
 750         NG_FREE_MSG(msg);
 751         return (error);
 752 }
 753
 754 static int
 755 ng_nat_rcvdata(hook_p hook, item_p item )
 756 {
 757         const priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
 758         struct mbuf     *m;
 759         struct ip       *ip;
 760         int rval, ipofs, error = 0;
 761         char *c;
 762
 763         /* We have no required hooks. */
 764         if (!(priv->flags & NGNAT_CONNECTED)) {
 765                 NG_FREE_ITEM(item);
 766                 return (ENXIO);
 767         }
 768
 769         /* We have no alias address yet to do anything. */
 770         if (!(priv->flags & NGNAT_ADDR_DEFINED))
 771                 goto send;
 772
 773         m = NGI_M(item);
 774
 775         if ((m = m_megapullup(m, m->m_pkthdr.len)) == NULL) {
 776                 NGI_M(item) = NULL;     /* avoid double free */
 777                 NG_FREE_ITEM(item);
 778                 return (ENOBUFS);
 779         }
 780
 781         NGI_M(item) = m;
 782
 783         switch (priv->dlt) {
 784         case DLT_RAW:
 785                 ipofs = 0;
 786                 break;
 787         case DLT_EN10MB:
 788             {
 789                 struct ether_header *eh;
 790
 791                 if (m->m_pkthdr.len < sizeof(struct ether_header)) {
 792                         NG_FREE_ITEM(item);
 793                         return (ENXIO);
 794                 }
 795                 eh = mtod(m, struct ether_header *);
 796                 switch (ntohs(eh->ether_type)) {
 797                 case ETHERTYPE_IP:
 798                 case ETHERTYPE_IPV6:
 799                         ipofs = sizeof(struct ether_header);
 800                         break;
 801                 default:
 802                         goto send;
 803                 }
 804                 break;
 805             }
 806         default:
 807                 panic("Corrupted priv->dlt: %u", priv->dlt);
 808         }
 809
 810         c = (char *)mtodo(m, ipofs);
 811         ip = (struct ip *)mtodo(m, ipofs);
 812
 813         KASSERT(m->m_pkthdr.len == ipofs + ntohs(ip->ip_len),
 814             ("ng_nat: ip_len != m_pkthdr.len"));
 815
 816         /*
 817          * We drop packet when:
 818          * 1. libalias returns PKT_ALIAS_ERROR;
 819          * 2. For incoming packets:
 820          *      a) for unresolved fragments;
 821          *      b) libalias returns PKT_ALIAS_IGNORED and
 822          *              PKT_ALIAS_DENY_INCOMING flag is set.
 823          */
 824         if (hook == priv->in) {
 825                 rval = LibAliasIn(priv->lib, c, m->m_len - ipofs +
 826                     M_TRAILINGSPACE(m));
 827                 if (rval == PKT_ALIAS_ERROR ||
 828                     rval == PKT_ALIAS_UNRESOLVED_FRAGMENT ||
 829                     (rval == PKT_ALIAS_IGNORED &&
 830                      (priv->lib->packetAliasMode &
 831                       PKT_ALIAS_DENY_INCOMING) != 0)) {
 832                         NG_FREE_ITEM(item);
 833                         return (EINVAL);
 834                 }
 835         } else if (hook == priv->out) {
 836                 rval = LibAliasOut(priv->lib, c, m->m_len - ipofs +
 837                     M_TRAILINGSPACE(m));
 838                 if (rval == PKT_ALIAS_ERROR) {
 839                         NG_FREE_ITEM(item);
 840                         return (EINVAL);
 841                 }
 842         } else
 843                 panic("ng_nat: unknown hook!\n");
 844
 845         if (rval == PKT_ALIAS_RESPOND)
 846                 m->m_flags |= M_SKIP_FIREWALL;
 847         m->m_pkthdr.len = m->m_len = ntohs(ip->ip_len) + ipofs;
 848
 849         if ((ip->ip_off & htons(IP_OFFMASK)) == 0 &&
 850             ip->ip_p == IPPROTO_TCP) {
 851                 struct tcphdr *th = (struct tcphdr *)((caddr_t)ip +
 852                     (ip->ip_hl << 2));
 853
 854                 /*
 855                  * Here is our terrible HACK.
 856                  *
 857                  * Sometimes LibAlias edits contents of TCP packet.
 858                  * In this case it needs to recompute full TCP
 859                  * checksum. However, the problem is that LibAlias
 860                  * doesn't have any idea about checksum offloading
 861                  * in kernel. To workaround this, we do not do
 862                  * checksumming in LibAlias, but only mark the
 863                  * packets in th_x2 field. If we receive a marked
 864                  * packet, we calculate correct checksum for it
 865                  * aware of offloading.
 866                  *
 867                  * Why do I do such a terrible hack instead of
 868                  * recalculating checksum for each packet?
 869                  * Because the previous checksum was not checked!
 870                  * Recalculating checksums for EVERY packet will
 871                  * hide ALL transmission errors. Yes, marked packets
 872                  * still suffer from this problem. But, sigh, natd(8)
 873                  * has this problem, too.
 874                  */
 875
 876                 if (th->th_x2) {
 877                         uint16_t ip_len = ntohs(ip->ip_len);
 878
 879                         th->th_x2 = 0;
 880                         th->th_sum = in_pseudo(ip->ip_src.s_addr,
 881                             ip->ip_dst.s_addr, htons(IPPROTO_TCP +
 882                             ip_len - (ip->ip_hl << 2)));
 883
 884                         if ((m->m_pkthdr.csum_flags & CSUM_TCP) == 0) {
 885                                 m->m_pkthdr.csum_data = offsetof(struct tcphdr,
 886                                     th_sum);
 887                                 in_delayed_cksum(m);
 888                         }
 889                 }
 890         }
 891
 892 send:
 893         if (hook == priv->in)
 894                 NG_FWD_ITEM_HOOK(error, item, priv->out);
 895         else
 896                 NG_FWD_ITEM_HOOK(error, item, priv->in);
 897
 898         return (error);
 899 }
 900
 901 static int
 902 ng_nat_shutdown(node_p node)
 903 {
 904         const priv_p priv = NG_NODE_PRIVATE(node);
 905
 906         NG_NODE_SET_PRIVATE(node, NULL);
 907         NG_NODE_UNREF(node);
 908
 909         /* Free redirects list. */
 910         while (!STAILQ_EMPTY(&priv->redirhead)) {
 911                 struct ng_nat_rdr_lst *entry = STAILQ_FIRST(&priv->redirhead);
 912                 STAILQ_REMOVE_HEAD(&priv->redirhead, entries);
 913                 free(entry, M_NETGRAPH);
 914         }
 915
 916         /* Final free. */
 917         LibAliasUninit(priv->lib);
 918         free(priv, M_NETGRAPH);
 919
 920         return (0);
 921 }
 922
 923 static int
 924 ng_nat_disconnect(hook_p hook)
 925 {
 926         const priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
 927
 928         priv->flags &= ~NGNAT_CONNECTED;
 929
 930         if (hook == priv->out)
 931                 priv->out = NULL;
 932         if (hook == priv->in)
 933                 priv->in = NULL;
 934
 935         if (priv->out == NULL && priv->in == NULL)
 936                 ng_rmnode_self(NG_HOOK_NODE(hook));
 937
 938         return (0);
 939 }
 940
 941 static unsigned int
 942 ng_nat_translate_flags(unsigned int x)
 943 {
 944         unsigned int    res = 0;
 945
 946         if (x & NG_NAT_LOG)
 947                 res |= PKT_ALIAS_LOG;
 948         if (x & NG_NAT_DENY_INCOMING)
 949                 res |= PKT_ALIAS_DENY_INCOMING;
 950         if (x & NG_NAT_SAME_PORTS)
 951                 res |= PKT_ALIAS_SAME_PORTS;
 952         if (x & NG_NAT_UNREGISTERED_ONLY)
 953                 res |= PKT_ALIAS_UNREGISTERED_ONLY;
 954         if (x & NG_NAT_RESET_ON_ADDR_CHANGE)
 955                 res |= PKT_ALIAS_RESET_ON_ADDR_CHANGE;
 956         if (x & NG_NAT_PROXY_ONLY)
 957                 res |= PKT_ALIAS_PROXY_ONLY;
 958         if (x & NG_NAT_REVERSE)
 959                 res |= PKT_ALIAS_REVERSE;
 960
 961         return (res);
 962 }