sys/netgraph/ng_bpf.c

   1 /*
   2  * ng_bpf.c
   3  */
   4
   5 /*-
   6  * Copyright (c) 1999 Whistle Communications, Inc.
   7  * All rights reserved.
   8  *
   9  * Subject to the following obligations and disclaimer of warranty, use and
  10  * redistribution of this software, in source or object code forms, with or
  11  * without modifications are expressly permitted by Whistle Communications;
  12  * provided, however, that:
  13  * 1. Any and all reproductions of the source or object code must include the
  14  *    copyright notice above and the following disclaimer of warranties; and
  15  * 2. No rights are granted, in any manner or form, to use Whistle
  16  *    Communications, Inc. trademarks, including the mark "WHISTLE
  17  *    COMMUNICATIONS" on advertising, endorsements, or otherwise except as
  18  *    such appears in the above copyright notice or in the software.
  19  *
  20  * THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
  21  * TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
  22  * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
  23  * INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
  24  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
  25  * WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY
  26  * REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
  27  * SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
  28  * IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
  29  * RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
  30  * WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
  31  * PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
  32  * SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY
  33  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  34  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  35  * THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
  36  * OF SUCH DAMAGE.
  37  *
  38  * Author: Archie Cobbs <archie@freebsd.org>
  39  * $Whistle: ng_bpf.c,v 1.3 1999/12/03 20:30:23 archie Exp $
  40  */
  41
  42 /*
  43  * BPF NETGRAPH NODE TYPE
  44  *
  45  * This node type accepts any number of hook connections.  With each hook
  46  * is associated a bpf(4) filter program, and two hook names (each possibly
  47  * the empty string).  Incoming packets are compared against the filter;
  48  * matching packets are delivered out the first named hook (or dropped if
  49  * the empty string), and non-matching packets are delivered out the second
  50  * named hook (or dropped if the empty string).
  51  *
  52  * Each hook also keeps statistics about how many packets have matched, etc.
  53  */
  54
  55 #include "opt_bpf.h"
  56
  57 #include <sys/param.h>
  58 #include <sys/systm.h>
  59 #include <sys/errno.h>
  60 #include <sys/kernel.h>
  61 #include <sys/malloc.h>
  62 #include <sys/mbuf.h>
  63
  64 #include <net/bpf.h>
  65 #ifdef BPF_JITTER
  66 #include <net/bpf_jitter.h>
  67 #endif
  68
  69 #include <netgraph/ng_message.h>
  70 #include <netgraph/netgraph.h>
  71 #include <netgraph/ng_parse.h>
  72 #include <netgraph/ng_bpf.h>
  73
  74 #ifdef NG_SEPARATE_MALLOC
  75 static MALLOC_DEFINE(M_NETGRAPH_BPF, "netgraph_bpf", "netgraph bpf node");
  76 #else
  77 #define M_NETGRAPH_BPF M_NETGRAPH
  78 #endif
  79
  80 #define OFFSETOF(s, e) ((char *)&((s *)0)->e - (char *)((s *)0))
  81
  82 #define ERROUT(x)       do { error = (x); goto done; } while (0)
  83
  84 /* Per hook private info */
  85 struct ng_bpf_hookinfo {
  86         hook_p                  hook;
  87         hook_p                  match;
  88         hook_p                  nomatch;
  89         struct ng_bpf_hookprog  *prog;
  90 #ifdef BPF_JITTER
  91         bpf_jit_filter          *jit_prog;
  92 #endif
  93         struct ng_bpf_hookstat  stats;
  94 };
  95 typedef struct ng_bpf_hookinfo *hinfo_p;
  96
  97 /* Netgraph methods */
  98 static ng_constructor_t ng_bpf_constructor;
  99 static ng_rcvmsg_t      ng_bpf_rcvmsg;
 100 static ng_shutdown_t    ng_bpf_shutdown;
 101 static ng_newhook_t     ng_bpf_newhook;
 102 static ng_rcvdata_t     ng_bpf_rcvdata;
 103 static ng_disconnect_t  ng_bpf_disconnect;
 104
 105 /* Maximum bpf program instructions */
 106 extern int      bpf_maxinsns;
 107
 108 /* Internal helper functions */
 109 static int      ng_bpf_setprog(hook_p hook, const struct ng_bpf_hookprog *hp);
 110
 111 /* Parse type for one struct bfp_insn */
 112 static const struct ng_parse_struct_field ng_bpf_insn_type_fields[] = {
 113         { "code",       &ng_parse_hint16_type   },
 114         { "jt",         &ng_parse_uint8_type    },
 115         { "jf",         &ng_parse_uint8_type    },
 116         { "k",          &ng_parse_uint32_type   },
 117         { NULL }
 118 };
 119 static const struct ng_parse_type ng_bpf_insn_type = {
 120         &ng_parse_struct_type,
 121         &ng_bpf_insn_type_fields
 122 };
 123
 124 /* Parse type for the field 'bpf_prog' in struct ng_bpf_hookprog */
 125 static int
 126 ng_bpf_hookprogary_getLength(const struct ng_parse_type *type,
 127         const u_char *start, const u_char *buf)
 128 {
 129         const struct ng_bpf_hookprog *hp;
 130
 131         hp = (const struct ng_bpf_hookprog *)
 132             (buf - OFFSETOF(struct ng_bpf_hookprog, bpf_prog));
 133         return hp->bpf_prog_len;
 134 }
 135
 136 static const struct ng_parse_array_info ng_bpf_hookprogary_info = {
 137         &ng_bpf_insn_type,
 138         &ng_bpf_hookprogary_getLength,
 139         NULL
 140 };
 141 static const struct ng_parse_type ng_bpf_hookprogary_type = {
 142         &ng_parse_array_type,
 143         &ng_bpf_hookprogary_info
 144 };
 145
 146 /* Parse type for struct ng_bpf_hookprog */
 147 static const struct ng_parse_struct_field ng_bpf_hookprog_type_fields[]
 148         = NG_BPF_HOOKPROG_TYPE_INFO(&ng_bpf_hookprogary_type);
 149 static const struct ng_parse_type ng_bpf_hookprog_type = {
 150         &ng_parse_struct_type,
 151         &ng_bpf_hookprog_type_fields
 152 };
 153
 154 /* Parse type for struct ng_bpf_hookstat */
 155 static const struct ng_parse_struct_field ng_bpf_hookstat_type_fields[]
 156         = NG_BPF_HOOKSTAT_TYPE_INFO;
 157 static const struct ng_parse_type ng_bpf_hookstat_type = {
 158         &ng_parse_struct_type,
 159         &ng_bpf_hookstat_type_fields
 160 };
 161
 162 /* List of commands and how to convert arguments to/from ASCII */
 163 static const struct ng_cmdlist ng_bpf_cmdlist[] = {
 164         {
 165           NGM_BPF_COOKIE,
 166           NGM_BPF_SET_PROGRAM,
 167           "setprogram",
 168           &ng_bpf_hookprog_type,
 169           NULL
 170         },
 171         {
 172           NGM_BPF_COOKIE,
 173           NGM_BPF_GET_PROGRAM,
 174           "getprogram",
 175           &ng_parse_hookbuf_type,
 176           &ng_bpf_hookprog_type
 177         },
 178         {
 179           NGM_BPF_COOKIE,
 180           NGM_BPF_GET_STATS,
 181           "getstats",
 182           &ng_parse_hookbuf_type,
 183           &ng_bpf_hookstat_type
 184         },
 185         {
 186           NGM_BPF_COOKIE,
 187           NGM_BPF_CLR_STATS,
 188           "clrstats",
 189           &ng_parse_hookbuf_type,
 190           NULL
 191         },
 192         {
 193           NGM_BPF_COOKIE,
 194           NGM_BPF_GETCLR_STATS,
 195           "getclrstats",
 196           &ng_parse_hookbuf_type,
 197           &ng_bpf_hookstat_type
 198         },
 199         { 0 }
 200 };
 201
 202 /* Netgraph type descriptor */
 203 static struct ng_type typestruct = {
 204         .version =      NG_ABI_VERSION,
 205         .name =         NG_BPF_NODE_TYPE,
 206         .constructor =  ng_bpf_constructor,
 207         .rcvmsg =       ng_bpf_rcvmsg,
 208         .shutdown =     ng_bpf_shutdown,
 209         .newhook =      ng_bpf_newhook,
 210         .rcvdata =      ng_bpf_rcvdata,
 211         .disconnect =   ng_bpf_disconnect,
 212         .cmdlist =      ng_bpf_cmdlist,
 213 };
 214 NETGRAPH_INIT(bpf, &typestruct);
 215
 216 /* Default BPF program for a hook that matches nothing */
 217 static const struct ng_bpf_hookprog ng_bpf_default_prog = {
 218         { '\0' },               /* to be filled in at hook creation time */
 219         { '\0' },
 220         { '\0' },
 221         1,
 222         { BPF_STMT(BPF_RET+BPF_K, 0) }
 223 };
 224
 225 /*
 226  * Node constructor
 227  *
 228  * We don't keep any per-node private data
 229  * We go via the hooks.
 230  */
 231 static int
 232 ng_bpf_constructor(node_p node)
 233 {
 234         NG_NODE_SET_PRIVATE(node, NULL);
 235         return (0);
 236 }
 237
 238 /*
 239  * Callback functions to be used by NG_NODE_FOREACH_HOOK() macro.
 240  */
 241 static int
 242 ng_bpf_addrefs(hook_p hook, void* arg)
 243 {
 244         hinfo_p hip = NG_HOOK_PRIVATE(hook);
 245         hook_p h = (hook_p)arg;
 246
 247         if (strcmp(hip->prog->ifMatch, NG_HOOK_NAME(h)) == 0)
 248             hip->match = h;
 249         if (strcmp(hip->prog->ifNotMatch, NG_HOOK_NAME(h)) == 0)
 250             hip->nomatch = h;
 251         return (1);
 252 }
 253
 254 static int
 255 ng_bpf_remrefs(hook_p hook, void* arg)
 256 {
 257         hinfo_p hip = NG_HOOK_PRIVATE(hook);
 258         hook_p h = (hook_p)arg;
 259
 260         if (hip->match == h)
 261             hip->match = NULL;
 262         if (hip->nomatch == h)
 263             hip->nomatch = NULL;
 264         return (1);
 265 }
 266
 267 /*
 268  * Add a hook
 269  */
 270 static int
 271 ng_bpf_newhook(node_p node, hook_p hook, const char *name)
 272 {
 273         hinfo_p hip;
 274         int error;
 275
 276         /* Create hook private structure */
 277         hip = malloc(sizeof(*hip), M_NETGRAPH_BPF, M_NOWAIT | M_ZERO);
 278         if (hip == NULL)
 279                 return (ENOMEM);
 280         hip->hook = hook;
 281         NG_HOOK_SET_PRIVATE(hook, hip);
 282
 283         /* Add our reference into other hooks data. */
 284         NG_NODE_FOREACH_HOOK(node, ng_bpf_addrefs, hook);
 285
 286         /* Attach the default BPF program */
 287         if ((error = ng_bpf_setprog(hook, &ng_bpf_default_prog)) != 0) {
 288                 free(hip, M_NETGRAPH_BPF);
 289                 NG_HOOK_SET_PRIVATE(hook, NULL);
 290                 return (error);
 291         }
 292
 293         /* Set hook name */
 294         strlcpy(hip->prog->thisHook, name, sizeof(hip->prog->thisHook));
 295         return (0);
 296 }
 297
 298 /*
 299  * Receive a control message
 300  */
 301 static int
 302 ng_bpf_rcvmsg(node_p node, item_p item, hook_p lasthook)
 303 {
 304         struct ng_mesg *msg;
 305         struct ng_mesg *resp = NULL;
 306         int error = 0;
 307
 308         NGI_GET_MSG(item, msg);
 309         switch (msg->header.typecookie) {
 310         case NGM_BPF_COOKIE:
 311                 switch (msg->header.cmd) {
 312                 case NGM_BPF_SET_PROGRAM:
 313                     {
 314                         struct ng_bpf_hookprog *const
 315                             hp = (struct ng_bpf_hookprog *)msg->data;
 316                         hook_p hook;
 317
 318                         /* Sanity check */
 319                         if (msg->header.arglen < sizeof(*hp)
 320                             || msg->header.arglen
 321                               != NG_BPF_HOOKPROG_SIZE(hp->bpf_prog_len))
 322                                 ERROUT(EINVAL);
 323
 324                         /* Find hook */
 325                         if ((hook = ng_findhook(node, hp->thisHook)) == NULL)
 326                                 ERROUT(ENOENT);
 327
 328                         /* Set new program */
 329                         if ((error = ng_bpf_setprog(hook, hp)) != 0)
 330                                 ERROUT(error);
 331                         break;
 332                     }
 333
 334                 case NGM_BPF_GET_PROGRAM:
 335                     {
 336                         struct ng_bpf_hookprog *hp;
 337                         hook_p hook;
 338
 339                         /* Sanity check */
 340                         if (msg->header.arglen == 0)
 341                                 ERROUT(EINVAL);
 342                         msg->data[msg->header.arglen - 1] = '\0';
 343
 344                         /* Find hook */
 345                         if ((hook = ng_findhook(node, msg->data)) == NULL)
 346                                 ERROUT(ENOENT);
 347
 348                         /* Build response */
 349                         hp = ((hinfo_p)NG_HOOK_PRIVATE(hook))->prog;
 350                         NG_MKRESPONSE(resp, msg,
 351                             NG_BPF_HOOKPROG_SIZE(hp->bpf_prog_len), M_NOWAIT);
 352                         if (resp == NULL)
 353                                 ERROUT(ENOMEM);
 354                         bcopy(hp, resp->data,
 355                            NG_BPF_HOOKPROG_SIZE(hp->bpf_prog_len));
 356                         break;
 357                     }
 358
 359                 case NGM_BPF_GET_STATS:
 360                 case NGM_BPF_CLR_STATS:
 361                 case NGM_BPF_GETCLR_STATS:
 362                     {
 363                         struct ng_bpf_hookstat *stats;
 364                         hook_p hook;
 365
 366                         /* Sanity check */
 367                         if (msg->header.arglen == 0)
 368                                 ERROUT(EINVAL);
 369                         msg->data[msg->header.arglen - 1] = '\0';
 370
 371                         /* Find hook */
 372                         if ((hook = ng_findhook(node, msg->data)) == NULL)
 373                                 ERROUT(ENOENT);
 374                         stats = &((hinfo_p)NG_HOOK_PRIVATE(hook))->stats;
 375
 376                         /* Build response (if desired) */
 377                         if (msg->header.cmd != NGM_BPF_CLR_STATS) {
 378                                 NG_MKRESPONSE(resp,
 379                                     msg, sizeof(*stats), M_NOWAIT);
 380                                 if (resp == NULL)
 381                                         ERROUT(ENOMEM);
 382                                 bcopy(stats, resp->data, sizeof(*stats));
 383                         }
 384
 385                         /* Clear stats (if desired) */
 386                         if (msg->header.cmd != NGM_BPF_GET_STATS)
 387                                 bzero(stats, sizeof(*stats));
 388                         break;
 389                     }
 390
 391                 default:
 392                         error = EINVAL;
 393                         break;
 394                 }
 395                 break;
 396         default:
 397                 error = EINVAL;
 398                 break;
 399         }
 400 done:
 401         NG_RESPOND_MSG(error, node, item, resp);
 402         NG_FREE_MSG(msg);
 403         return (error);
 404 }
 405
 406 /*
 407  * Receive data on a hook
 408  *
 409  * Apply the filter, and then drop or forward packet as appropriate.
 410  */
 411 static int
 412 ng_bpf_rcvdata(hook_p hook, item_p item)
 413 {
 414         const hinfo_p hip = NG_HOOK_PRIVATE(hook);
 415         int totlen;
 416         int needfree = 0, error = 0, usejit = 0;
 417         u_char *data = NULL;
 418         hinfo_p dhip;
 419         hook_p dest;
 420         u_int len;
 421         struct mbuf *m;
 422
 423         m = NGI_M(item);        /* 'item' still owns it.. we are peeking */
 424         totlen = m->m_pkthdr.len;
 425         /* Update stats on incoming hook. XXX Can we do 64 bits atomically? */
 426         /* atomic_add_int64(&hip->stats.recvFrames, 1); */
 427         /* atomic_add_int64(&hip->stats.recvOctets, totlen); */
 428         hip->stats.recvFrames++;
 429         hip->stats.recvOctets += totlen;
 430
 431         /* Don't call bpf_filter() with totlen == 0! */
 432         if (totlen == 0) {
 433                 len = 0;
 434                 goto ready;
 435         }
 436
 437 #ifdef BPF_JITTER
 438         if (bpf_jitter_enable != 0 && hip->jit_prog != NULL)
 439                 usejit = 1;
 440 #endif
 441
 442         /* Need to put packet in contiguous memory for bpf */
 443         if (m->m_next != NULL && totlen > MHLEN) {
 444                 if (usejit) {
 445                         data = malloc(totlen, M_NETGRAPH_BPF, M_NOWAIT);
 446                         if (data == NULL) {
 447                                 NG_FREE_ITEM(item);
 448                                 return (ENOMEM);
 449                         }
 450                         needfree = 1;
 451                         m_copydata(m, 0, totlen, (caddr_t)data);
 452                 }
 453         } else {
 454                 if (m->m_next != NULL) {
 455                         NGI_M(item) = m = m_pullup(m, totlen);
 456                         if (m == NULL) {
 457                                 NG_FREE_ITEM(item);
 458                                 return (ENOBUFS);
 459                         }
 460                 }
 461                 data = mtod(m, u_char *);
 462         }
 463
 464         /* Run packet through filter */
 465 #ifdef BPF_JITTER
 466         if (usejit)
 467                 len = (*(hip->jit_prog->func))(data, totlen, totlen);
 468         else
 469 #endif
 470         if (data)
 471                 len = bpf_filter(hip->prog->bpf_prog, data, totlen, totlen);
 472         else
 473                 len = bpf_filter(hip->prog->bpf_prog, (u_char *)m, totlen, 0);
 474         if (needfree)
 475                 free(data, M_NETGRAPH_BPF);
 476 ready:
 477         /* See if we got a match and find destination hook */
 478         if (len > 0) {
 479                 /* Update stats */
 480                 /* XXX atomically? */
 481                 hip->stats.recvMatchFrames++;
 482                 hip->stats.recvMatchOctets += totlen;
 483
 484                 /* Truncate packet length if required by the filter */
 485                 /* Assume this never changes m */
 486                 if (len < totlen) {
 487                         m_adj(m, -(totlen - len));
 488                         totlen = len;
 489                 }
 490                 dest = hip->match;
 491         } else
 492                 dest = hip->nomatch;
 493         if (dest == NULL) {
 494                 NG_FREE_ITEM(item);
 495                 return (0);
 496         }
 497
 498         /* Deliver frame out destination hook */
 499         dhip = NG_HOOK_PRIVATE(dest);
 500         dhip->stats.xmitOctets += totlen;
 501         dhip->stats.xmitFrames++;
 502         NG_FWD_ITEM_HOOK(error, item, dest);
 503         return (error);
 504 }
 505
 506 /*
 507  * Shutdown processing
 508  */
 509 static int
 510 ng_bpf_shutdown(node_p node)
 511 {
 512         NG_NODE_UNREF(node);
 513         return (0);
 514 }
 515
 516 /*
 517  * Hook disconnection
 518  */
 519 static int
 520 ng_bpf_disconnect(hook_p hook)
 521 {
 522         const node_p node = NG_HOOK_NODE(hook);
 523         const hinfo_p hip = NG_HOOK_PRIVATE(hook);
 524
 525         KASSERT(hip != NULL, ("%s: null info", __func__));
 526
 527         /* Remove our reference from other hooks data. */
 528         NG_NODE_FOREACH_HOOK(node, ng_bpf_remrefs, hook);
 529
 530         free(hip->prog, M_NETGRAPH_BPF);
 531 #ifdef BPF_JITTER
 532         if (hip->jit_prog != NULL)
 533                 bpf_destroy_jit_filter(hip->jit_prog);
 534 #endif
 535         free(hip, M_NETGRAPH_BPF);
 536         if ((NG_NODE_NUMHOOKS(node) == 0) &&
 537             (NG_NODE_IS_VALID(node))) {
 538                 ng_rmnode_self(node);
 539         }
 540         return (0);
 541 }
 542
 543 /************************************************************************
 544                         HELPER STUFF
 545  ************************************************************************/
 546
 547 /*
 548  * Set the BPF program associated with a hook
 549  */
 550 static int
 551 ng_bpf_setprog(hook_p hook, const struct ng_bpf_hookprog *hp0)
 552 {
 553         const hinfo_p hip = NG_HOOK_PRIVATE(hook);
 554         struct ng_bpf_hookprog *hp;
 555 #ifdef BPF_JITTER
 556         bpf_jit_filter *jit_prog;
 557 #endif
 558         int size;
 559
 560         /* Check program for validity */
 561         if (hp0->bpf_prog_len > bpf_maxinsns ||
 562             !bpf_validate(hp0->bpf_prog, hp0->bpf_prog_len))
 563                 return (EINVAL);
 564
 565         /* Make a copy of the program */
 566         size = NG_BPF_HOOKPROG_SIZE(hp0->bpf_prog_len);
 567         hp = malloc(size, M_NETGRAPH_BPF, M_NOWAIT);
 568         if (hp == NULL)
 569                 return (ENOMEM);
 570         bcopy(hp0, hp, size);
 571 #ifdef BPF_JITTER
 572         jit_prog = bpf_jitter(hp->bpf_prog, hp->bpf_prog_len);
 573 #endif
 574
 575         /* Free previous program, if any, and assign new one */
 576         if (hip->prog != NULL)
 577                 free(hip->prog, M_NETGRAPH_BPF);
 578         hip->prog = hp;
 579 #ifdef BPF_JITTER
 580         if (hip->jit_prog != NULL)
 581                 bpf_destroy_jit_filter(hip->jit_prog);
 582         hip->jit_prog = jit_prog;
 583 #endif
 584
 585         /* Prepare direct references on target hooks. */
 586         hip->match = ng_findhook(NG_HOOK_NODE(hook), hip->prog->ifMatch);
 587         hip->nomatch = ng_findhook(NG_HOOK_NODE(hook), hip->prog->ifNotMatch);
 588         return (0);
 589 }