sys/netgraph/bpf/ng_bpf.c

   1
   2 /*
   3  * ng_bpf.c
   4  *
   5  * Copyright (c) 1999 Whistle Communications, Inc.
   6  * All rights reserved.
   7  *
   8  * Subject to the following obligations and disclaimer of warranty, use and
   9  * redistribution of this software, in source or object code forms, with or
  10  * without modifications are expressly permitted by Whistle Communications;
  11  * provided, however, that:
  12  * 1. Any and all reproductions of the source or object code must include the
  13  *    copyright notice above and the following disclaimer of warranties; and
  14  * 2. No rights are granted, in any manner or form, to use Whistle
  15  *    Communications, Inc. trademarks, including the mark "WHISTLE
  16  *    COMMUNICATIONS" on advertising, endorsements, or otherwise except as
  17  *    such appears in the above copyright notice or in the software.
  18  *
  19  * THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
  20  * TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
  21  * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
  22  * INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
  23  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
  24  * WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANBPF, OR MAKE ANY
  25  * REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
  26  * SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
  27  * IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
  28  * RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
  29  * WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
  30  * PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
  31  * SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY
  32  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  33  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  34  * THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
  35  * OF SUCH DAMAGE.
  36  *
  37  * Author: Archie Cobbs <archie@freebsd.org>
  38  *
  39  * $FreeBSD: src/sys/netgraph/ng_bpf.c,v 1.2.4.4 2002/07/02 23:44:02 archie Exp $
  40  * $DragonFly: src/sys/netgraph/bpf/ng_bpf.c,v 1.5 2008/01/05 14:02:39 swildner Exp $
  41  * $Whistle: ng_bpf.c,v 1.3 1999/12/03 20:30:23 archie Exp $
  42  */
  43
  44 /*
  45  * BPF NETGRAPH NODE TYPE
  46  *
  47  * This node type accepts any number of hook connections.  With each hook
  48  * is associated a bpf(4) filter program, and two hook names (each possibly
  49  * the empty string).  Incoming packets are compared against the filter;
  50  * matching packets are delivered out the first named hook (or dropped if
  51  * the empty string), and non-matching packets are delivered out the second
  52  * named hook (or dropped if the empty string).
  53  *
  54  * Each hook also keeps statistics about how many packets have matched, etc.
  55  */
  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
  66 #include <netgraph/ng_message.h>
  67 #include <netgraph/netgraph.h>
  68 #include <netgraph/ng_parse.h>
  69 #include "ng_bpf.h"
  70
  71 #define OFFSETOF(s, e) ((char *)&((s *)0)->e - (char *)((s *)0))
  72
  73 #define ERROUT(x)       do { error = (x); goto done; } while (0)
  74
  75 /* Per hook private info */
  76 struct ng_bpf_hookinfo {
  77         node_p                  node;
  78         hook_p                  hook;
  79         struct ng_bpf_hookprog  *prog;
  80         struct ng_bpf_hookstat  stats;
  81 };
  82 typedef struct ng_bpf_hookinfo *hinfo_p;
  83
  84 /* Netgraph methods */
  85 static ng_constructor_t ng_bpf_constructor;
  86 static ng_rcvmsg_t      ng_bpf_rcvmsg;
  87 static ng_shutdown_t    ng_bpf_rmnode;
  88 static ng_newhook_t     ng_bpf_newhook;
  89 static ng_rcvdata_t     ng_bpf_rcvdata;
  90 static ng_disconnect_t  ng_bpf_disconnect;
  91
  92 /* Internal helper functions */
  93 static int      ng_bpf_setprog(hook_p hook, const struct ng_bpf_hookprog *hp);
  94
  95 /* Parse type for one struct bfp_insn */
  96 static const struct ng_parse_struct_field ng_bpf_insn_type_fields[] = {
  97         { "code",       &ng_parse_hint16_type   },
  98         { "jt",         &ng_parse_uint8_type    },
  99         { "jf",         &ng_parse_uint8_type    },
 100         { "k",          &ng_parse_uint32_type   },
 101         { NULL }
 102 };
 103 static const struct ng_parse_type ng_bpf_insn_type = {
 104         &ng_parse_struct_type,
 105         &ng_bpf_insn_type_fields
 106 };
 107
 108 /* Parse type for the field 'bpf_prog' in struct ng_bpf_hookprog */
 109 static int
 110 ng_bpf_hookprogary_getLength(const struct ng_parse_type *type,
 111         const u_char *start, const u_char *buf)
 112 {
 113         const struct ng_bpf_hookprog *hp;
 114
 115         hp = (const struct ng_bpf_hookprog *)
 116             (buf - OFFSETOF(struct ng_bpf_hookprog, bpf_prog));
 117         return hp->bpf_prog_len;
 118 }
 119
 120 static const struct ng_parse_array_info ng_bpf_hookprogary_info = {
 121         &ng_bpf_insn_type,
 122         &ng_bpf_hookprogary_getLength,
 123         NULL
 124 };
 125 static const struct ng_parse_type ng_bpf_hookprogary_type = {
 126         &ng_parse_array_type,
 127         &ng_bpf_hookprogary_info
 128 };
 129
 130 /* Parse type for struct ng_bpf_hookprog */
 131 static const struct ng_parse_struct_field ng_bpf_hookprog_type_fields[]
 132         = NG_BPF_HOOKPROG_TYPE_INFO(&ng_bpf_hookprogary_type);
 133 static const struct ng_parse_type ng_bpf_hookprog_type = {
 134         &ng_parse_struct_type,
 135         &ng_bpf_hookprog_type_fields
 136 };
 137
 138 /* Parse type for struct ng_bpf_hookstat */
 139 static const struct ng_parse_struct_field ng_bpf_hookstat_type_fields[]
 140         = NG_BPF_HOOKSTAT_TYPE_INFO;
 141 static const struct ng_parse_type ng_bpf_hookstat_type = {
 142         &ng_parse_struct_type,
 143         &ng_bpf_hookstat_type_fields
 144 };
 145
 146 /* List of commands and how to convert arguments to/from ASCII */
 147 static const struct ng_cmdlist ng_bpf_cmdlist[] = {
 148         {
 149           NGM_BPF_COOKIE,
 150           NGM_BPF_SET_PROGRAM,
 151           "setprogram",
 152           &ng_bpf_hookprog_type,
 153           NULL
 154         },
 155         {
 156           NGM_BPF_COOKIE,
 157           NGM_BPF_GET_PROGRAM,
 158           "getprogram",
 159           &ng_parse_hookbuf_type,
 160           &ng_bpf_hookprog_type
 161         },
 162         {
 163           NGM_BPF_COOKIE,
 164           NGM_BPF_GET_STATS,
 165           "getstats",
 166           &ng_parse_hookbuf_type,
 167           &ng_bpf_hookstat_type
 168         },
 169         {
 170           NGM_BPF_COOKIE,
 171           NGM_BPF_CLR_STATS,
 172           "clrstats",
 173           &ng_parse_hookbuf_type,
 174           NULL
 175         },
 176         {
 177           NGM_BPF_COOKIE,
 178           NGM_BPF_GETCLR_STATS,
 179           "getclrstats",
 180           &ng_parse_hookbuf_type,
 181           &ng_bpf_hookstat_type
 182         },
 183         { 0 }
 184 };
 185
 186 /* Netgraph type descriptor */
 187 static struct ng_type typestruct = {
 188         NG_VERSION,
 189         NG_BPF_NODE_TYPE,
 190         NULL,
 191         ng_bpf_constructor,
 192         ng_bpf_rcvmsg,
 193         ng_bpf_rmnode,
 194         ng_bpf_newhook,
 195         NULL,
 196         NULL,
 197         ng_bpf_rcvdata,
 198         ng_bpf_rcvdata,
 199         ng_bpf_disconnect,
 200         ng_bpf_cmdlist
 201 };
 202 NETGRAPH_INIT(bpf, &typestruct);
 203
 204 /* Default BPF program for a hook that matches nothing */
 205 static const struct ng_bpf_hookprog ng_bpf_default_prog = {
 206         { '\0' },               /* to be filled in at hook creation time */
 207         { '\0' },
 208         { '\0' },
 209         1,
 210         { BPF_STMT(BPF_RET+BPF_K, 0) }
 211 };
 212
 213 /*
 214  * Node constructor
 215  *
 216  * We don't keep any per-node private data
 217  */
 218 static int
 219 ng_bpf_constructor(node_p *nodep)
 220 {
 221         int error = 0;
 222
 223         if ((error = ng_make_node_common(&typestruct, nodep)))
 224                 return (error);
 225         (*nodep)->private = NULL;
 226         return (0);
 227 }
 228
 229 /*
 230  * Add a hook
 231  */
 232 static int
 233 ng_bpf_newhook(node_p node, hook_p hook, const char *name)
 234 {
 235         hinfo_p hip;
 236         int error;
 237
 238         /* Create hook private structure */
 239         MALLOC(hip, hinfo_p, sizeof(*hip), M_NETGRAPH, M_NOWAIT | M_ZERO);
 240         if (hip == NULL)
 241                 return (ENOMEM);
 242         hip->hook = hook;
 243         hook->private = hip;
 244         hip->node = node;
 245
 246         /* Attach the default BPF program */
 247         if ((error = ng_bpf_setprog(hook, &ng_bpf_default_prog)) != 0) {
 248                 FREE(hip, M_NETGRAPH);
 249                 hook->private = NULL;
 250                 return (error);
 251         }
 252
 253         /* Set hook name */
 254         strncpy(hip->prog->thisHook, name, sizeof(hip->prog->thisHook) - 1);
 255         hip->prog->thisHook[sizeof(hip->prog->thisHook) - 1] = '\0';
 256         return (0);
 257 }
 258
 259 /*
 260  * Receive a control message
 261  */
 262 static int
 263 ng_bpf_rcvmsg(node_p node, struct ng_mesg *msg, const char *retaddr,
 264            struct ng_mesg **rptr)
 265 {
 266         struct ng_mesg *resp = NULL;
 267         int error = 0;
 268
 269         switch (msg->header.typecookie) {
 270         case NGM_BPF_COOKIE:
 271                 switch (msg->header.cmd) {
 272                 case NGM_BPF_SET_PROGRAM:
 273                     {
 274                         struct ng_bpf_hookprog *const
 275                             hp = (struct ng_bpf_hookprog *)msg->data;
 276                         hook_p hook;
 277
 278                         /* Sanity check */
 279                         if (msg->header.arglen < sizeof(*hp)
 280                             || msg->header.arglen
 281                               != NG_BPF_HOOKPROG_SIZE(hp->bpf_prog_len))
 282                                 ERROUT(EINVAL);
 283
 284                         /* Find hook */
 285                         if ((hook = ng_findhook(node, hp->thisHook)) == NULL)
 286                                 ERROUT(ENOENT);
 287
 288                         /* Set new program */
 289                         if ((error = ng_bpf_setprog(hook, hp)) != 0)
 290                                 ERROUT(error);
 291                         break;
 292                     }
 293
 294                 case NGM_BPF_GET_PROGRAM:
 295                     {
 296                         struct ng_bpf_hookprog *hp;
 297                         hook_p hook;
 298
 299                         /* Sanity check */
 300                         if (msg->header.arglen == 0)
 301                                 ERROUT(EINVAL);
 302                         msg->data[msg->header.arglen - 1] = '\0';
 303
 304                         /* Find hook */
 305                         if ((hook = ng_findhook(node, msg->data)) == NULL)
 306                                 ERROUT(ENOENT);
 307
 308                         /* Build response */
 309                         hp = ((hinfo_p)hook->private)->prog;
 310                         NG_MKRESPONSE(resp, msg,
 311                             NG_BPF_HOOKPROG_SIZE(hp->bpf_prog_len), M_NOWAIT);
 312                         if (resp == NULL)
 313                                 ERROUT(ENOMEM);
 314                         bcopy(hp, resp->data,
 315                            NG_BPF_HOOKPROG_SIZE(hp->bpf_prog_len));
 316                         break;
 317                     }
 318
 319                 case NGM_BPF_GET_STATS:
 320                 case NGM_BPF_CLR_STATS:
 321                 case NGM_BPF_GETCLR_STATS:
 322                     {
 323                         struct ng_bpf_hookstat *stats;
 324                         hook_p hook;
 325
 326                         /* Sanity check */
 327                         if (msg->header.arglen == 0)
 328                                 ERROUT(EINVAL);
 329                         msg->data[msg->header.arglen - 1] = '\0';
 330
 331                         /* Find hook */
 332                         if ((hook = ng_findhook(node, msg->data)) == NULL)
 333                                 ERROUT(ENOENT);
 334                         stats = &((hinfo_p)hook->private)->stats;
 335
 336                         /* Build response (if desired) */
 337                         if (msg->header.cmd != NGM_BPF_CLR_STATS) {
 338                                 NG_MKRESPONSE(resp,
 339                                     msg, sizeof(*stats), M_NOWAIT);
 340                                 if (resp == NULL)
 341                                         ERROUT(ENOMEM);
 342                                 bcopy(stats, resp->data, sizeof(*stats));
 343                         }
 344
 345                         /* Clear stats (if desired) */
 346                         if (msg->header.cmd != NGM_BPF_GET_STATS)
 347                                 bzero(stats, sizeof(*stats));
 348                         break;
 349                     }
 350
 351                 default:
 352                         error = EINVAL;
 353                         break;
 354                 }
 355                 break;
 356         default:
 357                 error = EINVAL;
 358                 break;
 359         }
 360         if (rptr)
 361                 *rptr = resp;
 362         else if (resp)
 363                 FREE(resp, M_NETGRAPH);
 364
 365 done:
 366         FREE(msg, M_NETGRAPH);
 367         return (error);
 368 }
 369
 370 /*
 371  * Receive data on a hook
 372  *
 373  * Apply the filter, and then drop or forward packet as appropriate.
 374  */
 375 static int
 376 ng_bpf_rcvdata(hook_p hook, struct mbuf *m, meta_p meta)
 377 {
 378         const hinfo_p hip = hook->private;
 379         int totlen = m->m_pkthdr.len;
 380         int needfree = 0, error = 0;
 381         u_char *data, buf[256];
 382         hinfo_p dhip;
 383         hook_p dest;
 384         u_int len;
 385
 386         /* Update stats on incoming hook */
 387         hip->stats.recvFrames++;
 388         hip->stats.recvOctets += totlen;
 389
 390         /* Need to put packet in contiguous memory for bpf */
 391         if (m->m_next != NULL) {
 392                 if (totlen > sizeof(buf)) {
 393                         MALLOC(data, u_char *, totlen, M_NETGRAPH, M_NOWAIT);
 394                         if (data == NULL) {
 395                                 NG_FREE_DATA(m, meta);
 396                                 return (ENOMEM);
 397                         }
 398                         needfree = 1;
 399                 } else
 400                         data = buf;
 401                 m_copydata(m, 0, totlen, (caddr_t)data);
 402         } else
 403                 data = mtod(m, u_char *);
 404
 405         /* Run packet through filter */
 406         len = bpf_filter(hip->prog->bpf_prog, data, totlen, totlen);
 407         if (needfree)
 408                 FREE(data, M_NETGRAPH);
 409
 410         /* See if we got a match and find destination hook */
 411         if (len > 0) {
 412
 413                 /* Update stats */
 414                 hip->stats.recvMatchFrames++;
 415                 hip->stats.recvMatchOctets += totlen;
 416
 417                 /* Truncate packet length if required by the filter */
 418                 if (len < totlen) {
 419                         m_adj(m, -(totlen - len));
 420                         totlen -= len;
 421                 }
 422                 dest = ng_findhook(hip->node, hip->prog->ifMatch);
 423         } else
 424                 dest = ng_findhook(hip->node, hip->prog->ifNotMatch);
 425         if (dest == NULL) {
 426                 NG_FREE_DATA(m, meta);
 427                 return (0);
 428         }
 429
 430         /* Deliver frame out destination hook */
 431         dhip = (hinfo_p)dest->private;
 432         dhip->stats.xmitOctets += totlen;
 433         dhip->stats.xmitFrames++;
 434         NG_SEND_DATA(error, dest, m, meta);
 435         return (error);
 436 }
 437
 438 /*
 439  * Shutdown processing
 440  */
 441 static int
 442 ng_bpf_rmnode(node_p node)
 443 {
 444         node->flags |= NG_INVALID;
 445         ng_cutlinks(node);
 446         ng_unname(node);
 447         ng_unref(node);
 448         return (0);
 449 }
 450
 451 /*
 452  * Hook disconnection
 453  */
 454 static int
 455 ng_bpf_disconnect(hook_p hook)
 456 {
 457         const hinfo_p hip = hook->private;
 458
 459         KASSERT(hip != NULL, ("%s: null info", __func__));
 460         FREE(hip->prog, M_NETGRAPH);
 461         bzero(hip, sizeof(*hip));
 462         FREE(hip, M_NETGRAPH);
 463         hook->private = NULL;                   /* for good measure */
 464         if (hook->node->numhooks == 0)
 465                 ng_rmnode(hook->node);
 466         return (0);
 467 }
 468
 469 /************************************************************************
 470                         HELPER STUFF
 471  ************************************************************************/
 472
 473 /*
 474  * Set the BPF program associated with a hook
 475  */
 476 static int
 477 ng_bpf_setprog(hook_p hook, const struct ng_bpf_hookprog *hp0)
 478 {
 479         const hinfo_p hip = hook->private;
 480         struct ng_bpf_hookprog *hp;
 481         int size;
 482
 483         /* Check program for validity */
 484         if (!bpf_validate(hp0->bpf_prog, hp0->bpf_prog_len))
 485                 return (EINVAL);
 486
 487         /* Make a copy of the program */
 488         size = NG_BPF_HOOKPROG_SIZE(hp0->bpf_prog_len);
 489         MALLOC(hp, struct ng_bpf_hookprog *, size, M_NETGRAPH, M_NOWAIT);
 490         if (hp == NULL)
 491                 return (ENOMEM);
 492         bcopy(hp0, hp, size);
 493
 494         /* Free previous program, if any, and assign new one */
 495         if (hip->prog != NULL)
 496                 FREE(hip->prog, M_NETGRAPH);
 497         hip->prog = hp;
 498         return (0);
 499 }
 500