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  * $Whistle: ng_bpf.c,v 1.3 1999/12/03 20:30:23 archie Exp $
  41  */
  42
  43 /*
  44  * BPF NETGRAPH NODE TYPE
  45  *
  46  * This node type accepts any number of hook connections.  With each hook
  47  * is associated a bpf(4) filter program, and two hook names (each possibly
  48  * the empty string).  Incoming packets are compared against the filter;
  49  * matching packets are delivered out the first named hook (or dropped if
  50  * the empty string), and non-matching packets are delivered out the second
  51  * named hook (or dropped if the empty string).
  52  *
  53  * Each hook also keeps statistics about how many packets have matched, etc.
  54  */
  55
  56 #include <sys/param.h>
  57 #include <sys/systm.h>
  58 #include <sys/errno.h>
  59 #include <sys/kernel.h>
  60 #include <sys/malloc.h>
  61 #include <sys/mbuf.h>
  62
  63 #include <net/bpf.h>
  64
  65 #include <netgraph/ng_message.h>
  66 #include <netgraph/netgraph.h>
  67 #include <netgraph/ng_parse.h>
  68 #include "ng_bpf.h"
  69
  70 #define OFFSETOF(s, e) ((char *)&((s *)0)->e - (char *)((s *)0))
  71
  72 #define ERROUT(x)       do { error = (x); goto done; } while (0)
  73
  74 /* Per hook private info */
  75 struct ng_bpf_hookinfo {
  76         node_p                  node;
  77         hook_p                  hook;
  78         struct ng_bpf_hookprog  *prog;
  79         struct ng_bpf_hookstat  stats;
  80 };
  81 typedef struct ng_bpf_hookinfo *hinfo_p;
  82
  83 /* Netgraph methods */
  84 static ng_constructor_t ng_bpf_constructor;
  85 static ng_rcvmsg_t      ng_bpf_rcvmsg;
  86 static ng_shutdown_t    ng_bpf_rmnode;
  87 static ng_newhook_t     ng_bpf_newhook;
  88 static ng_rcvdata_t     ng_bpf_rcvdata;
  89 static ng_disconnect_t  ng_bpf_disconnect;
  90
  91 /* Internal helper functions */
  92 static int      ng_bpf_setprog(hook_p hook, const struct ng_bpf_hookprog *hp);
  93
  94 /* Parse type for one struct bfp_insn */
  95 static const struct ng_parse_struct_field ng_bpf_insn_type_fields[] = {
  96         { "code",       &ng_parse_hint16_type   },
  97         { "jt",         &ng_parse_uint8_type    },
  98         { "jf",         &ng_parse_uint8_type    },
  99         { "k",          &ng_parse_uint32_type   },
 100         { NULL }
 101 };
 102 static const struct ng_parse_type ng_bpf_insn_type = {
 103         &ng_parse_struct_type,
 104         &ng_bpf_insn_type_fields
 105 };
 106
 107 /* Parse type for the field 'bpf_prog' in struct ng_bpf_hookprog */
 108 static int
 109 ng_bpf_hookprogary_getLength(const struct ng_parse_type *type,
 110         const u_char *start, const u_char *buf)
 111 {
 112         const struct ng_bpf_hookprog *hp;
 113
 114         hp = (const struct ng_bpf_hookprog *)
 115             (buf - OFFSETOF(struct ng_bpf_hookprog, bpf_prog));
 116         return hp->bpf_prog_len;
 117 }
 118
 119 static const struct ng_parse_array_info ng_bpf_hookprogary_info = {
 120         &ng_bpf_insn_type,
 121         &ng_bpf_hookprogary_getLength,
 122         NULL
 123 };
 124 static const struct ng_parse_type ng_bpf_hookprogary_type = {
 125         &ng_parse_array_type,
 126         &ng_bpf_hookprogary_info
 127 };
 128
 129 /* Parse type for struct ng_bpf_hookprog */
 130 static const struct ng_parse_struct_field ng_bpf_hookprog_type_fields[]
 131         = NG_BPF_HOOKPROG_TYPE_INFO(&ng_bpf_hookprogary_type);
 132 static const struct ng_parse_type ng_bpf_hookprog_type = {
 133         &ng_parse_struct_type,
 134         &ng_bpf_hookprog_type_fields
 135 };
 136
 137 /* Parse type for struct ng_bpf_hookstat */
 138 static const struct ng_parse_struct_field ng_bpf_hookstat_type_fields[]
 139         = NG_BPF_HOOKSTAT_TYPE_INFO;
 140 static const struct ng_parse_type ng_bpf_hookstat_type = {
 141         &ng_parse_struct_type,
 142         &ng_bpf_hookstat_type_fields
 143 };
 144
 145 /* List of commands and how to convert arguments to/from ASCII */
 146 static const struct ng_cmdlist ng_bpf_cmdlist[] = {
 147         {
 148           NGM_BPF_COOKIE,
 149           NGM_BPF_SET_PROGRAM,
 150           "setprogram",
 151           &ng_bpf_hookprog_type,
 152           NULL
 153         },
 154         {
 155           NGM_BPF_COOKIE,
 156           NGM_BPF_GET_PROGRAM,
 157           "getprogram",
 158           &ng_parse_hookbuf_type,
 159           &ng_bpf_hookprog_type
 160         },
 161         {
 162           NGM_BPF_COOKIE,
 163           NGM_BPF_GET_STATS,
 164           "getstats",
 165           &ng_parse_hookbuf_type,
 166           &ng_bpf_hookstat_type
 167         },
 168         {
 169           NGM_BPF_COOKIE,
 170           NGM_BPF_CLR_STATS,
 171           "clrstats",
 172           &ng_parse_hookbuf_type,
 173           NULL
 174         },
 175         {
 176           NGM_BPF_COOKIE,
 177           NGM_BPF_GETCLR_STATS,
 178           "getclrstats",
 179           &ng_parse_hookbuf_type,
 180           &ng_bpf_hookstat_type
 181         },
 182         { 0 }
 183 };
 184
 185 /* Netgraph type descriptor */
 186 static struct ng_type typestruct = {
 187         NG_VERSION,
 188         NG_BPF_NODE_TYPE,
 189         NULL,
 190         ng_bpf_constructor,
 191         ng_bpf_rcvmsg,
 192         ng_bpf_rmnode,
 193         ng_bpf_newhook,
 194         NULL,
 195         NULL,
 196         ng_bpf_rcvdata,
 197         ng_bpf_rcvdata,
 198         ng_bpf_disconnect,
 199         ng_bpf_cmdlist
 200 };
 201 NETGRAPH_INIT(bpf, &typestruct);
 202
 203 /* Default BPF program for a hook that matches nothing */
 204 static const struct ng_bpf_hookprog ng_bpf_default_prog = {
 205         { '\0' },               /* to be filled in at hook creation time */
 206         { '\0' },
 207         { '\0' },
 208         1,
 209         { BPF_STMT(BPF_RET+BPF_K, 0) }
 210 };
 211
 212 /*
 213  * Node constructor
 214  *
 215  * We don't keep any per-node private data
 216  */
 217 static int
 218 ng_bpf_constructor(node_p *nodep)
 219 {
 220         int error = 0;
 221
 222         if ((error = ng_make_node_common(&typestruct, nodep)))
 223                 return (error);
 224         (*nodep)->private = NULL;
 225         return (0);
 226 }
 227
 228 /*
 229  * Add a hook
 230  */
 231 static int
 232 ng_bpf_newhook(node_p node, hook_p hook, const char *name)
 233 {
 234         hinfo_p hip;
 235         int error;
 236
 237         /* Create hook private structure */
 238         hip = kmalloc(sizeof(*hip), M_NETGRAPH, M_NOWAIT | M_ZERO);
 239         if (hip == NULL)
 240                 return (ENOMEM);
 241         hip->hook = hook;
 242         hook->private = hip;
 243         hip->node = node;
 244
 245         /* Attach the default BPF program */
 246         if ((error = ng_bpf_setprog(hook, &ng_bpf_default_prog)) != 0) {
 247                 kfree(hip, M_NETGRAPH);
 248                 hook->private = NULL;
 249                 return (error);
 250         }
 251
 252         /* Set hook name */
 253         strncpy(hip->prog->thisHook, name, sizeof(hip->prog->thisHook) - 1);
 254         hip->prog->thisHook[sizeof(hip->prog->thisHook) - 1] = '\0';
 255         return (0);
 256 }
 257
 258 /*
 259  * Receive a control message
 260  */
 261 static int
 262 ng_bpf_rcvmsg(node_p node, struct ng_mesg *msg, const char *retaddr,
 263            struct ng_mesg **rptr)
 264 {
 265         struct ng_mesg *resp = NULL;
 266         int error = 0;
 267
 268         switch (msg->header.typecookie) {
 269         case NGM_BPF_COOKIE:
 270                 switch (msg->header.cmd) {
 271                 case NGM_BPF_SET_PROGRAM:
 272                     {
 273                         struct ng_bpf_hookprog *const
 274                             hp = (struct ng_bpf_hookprog *)msg->data;
 275                         hook_p hook;
 276
 277                         /* Sanity check */
 278                         if (msg->header.arglen < sizeof(*hp)
 279                             || msg->header.arglen
 280                               != NG_BPF_HOOKPROG_SIZE(hp->bpf_prog_len))
 281                                 ERROUT(EINVAL);
 282
 283                         /* Find hook */
 284                         if ((hook = ng_findhook(node, hp->thisHook)) == NULL)
 285                                 ERROUT(ENOENT);
 286
 287                         /* Set new program */
 288                         if ((error = ng_bpf_setprog(hook, hp)) != 0)
 289                                 ERROUT(error);
 290                         break;
 291                     }
 292
 293                 case NGM_BPF_GET_PROGRAM:
 294                     {
 295                         struct ng_bpf_hookprog *hp;
 296                         hook_p hook;
 297
 298                         /* Sanity check */
 299                         if (msg->header.arglen == 0)
 300                                 ERROUT(EINVAL);
 301                         msg->data[msg->header.arglen - 1] = '\0';
 302
 303                         /* Find hook */
 304                         if ((hook = ng_findhook(node, msg->data)) == NULL)
 305                                 ERROUT(ENOENT);
 306
 307                         /* Build response */
 308                         hp = ((hinfo_p)hook->private)->prog;
 309                         NG_MKRESPONSE(resp, msg,
 310                             NG_BPF_HOOKPROG_SIZE(hp->bpf_prog_len), M_NOWAIT);
 311                         if (resp == NULL)
 312                                 ERROUT(ENOMEM);
 313                         bcopy(hp, resp->data,
 314                            NG_BPF_HOOKPROG_SIZE(hp->bpf_prog_len));
 315                         break;
 316                     }
 317
 318                 case NGM_BPF_GET_STATS:
 319                 case NGM_BPF_CLR_STATS:
 320                 case NGM_BPF_GETCLR_STATS:
 321                     {
 322                         struct ng_bpf_hookstat *stats;
 323                         hook_p hook;
 324
 325                         /* Sanity check */
 326                         if (msg->header.arglen == 0)
 327                                 ERROUT(EINVAL);
 328                         msg->data[msg->header.arglen - 1] = '\0';
 329
 330                         /* Find hook */
 331                         if ((hook = ng_findhook(node, msg->data)) == NULL)
 332                                 ERROUT(ENOENT);
 333                         stats = &((hinfo_p)hook->private)->stats;
 334
 335                         /* Build response (if desired) */
 336                         if (msg->header.cmd != NGM_BPF_CLR_STATS) {
 337                                 NG_MKRESPONSE(resp,
 338                                     msg, sizeof(*stats), M_NOWAIT);
 339                                 if (resp == NULL)
 340                                         ERROUT(ENOMEM);
 341                                 bcopy(stats, resp->data, sizeof(*stats));
 342                         }
 343
 344                         /* Clear stats (if desired) */
 345                         if (msg->header.cmd != NGM_BPF_GET_STATS)
 346                                 bzero(stats, sizeof(*stats));
 347                         break;
 348                     }
 349
 350                 default:
 351                         error = EINVAL;
 352                         break;
 353                 }
 354                 break;
 355         default:
 356                 error = EINVAL;
 357                 break;
 358         }
 359         if (rptr)
 360                 *rptr = resp;
 361         else if (resp)
 362                 kfree(resp, M_NETGRAPH);
 363
 364 done:
 365         kfree(msg, M_NETGRAPH);
 366         return (error);
 367 }
 368
 369 /*
 370  * Receive data on a hook
 371  *
 372  * Apply the filter, and then drop or forward packet as appropriate.
 373  */
 374 static int
 375 ng_bpf_rcvdata(hook_p hook, struct mbuf *m, meta_p meta)
 376 {
 377         const hinfo_p hip = hook->private;
 378         int totlen = m->m_pkthdr.len;
 379         int needfree = 0, error = 0;
 380         u_char *data, buf[256];
 381         hinfo_p dhip;
 382         hook_p dest;
 383         u_int len;
 384
 385         /* Update stats on incoming hook */
 386         hip->stats.recvFrames++;
 387         hip->stats.recvOctets += totlen;
 388
 389         /* Need to put packet in contiguous memory for bpf */
 390         if (m->m_next != NULL) {
 391                 if (totlen > sizeof(buf)) {
 392                         data = kmalloc(totlen, M_NETGRAPH, M_NOWAIT);
 393                         if (data == NULL) {
 394                                 NG_FREE_DATA(m, meta);
 395                                 return (ENOMEM);
 396                         }
 397                         needfree = 1;
 398                 } else
 399                         data = buf;
 400                 m_copydata(m, 0, totlen, (caddr_t)data);
 401         } else
 402                 data = mtod(m, u_char *);
 403
 404         /* Run packet through filter */
 405         len = bpf_filter(hip->prog->bpf_prog, data, totlen, totlen);
 406         if (needfree)
 407                 kfree(data, M_NETGRAPH);
 408
 409         /* See if we got a match and find destination hook */
 410         if (len > 0) {
 411
 412                 /* Update stats */
 413                 hip->stats.recvMatchFrames++;
 414                 hip->stats.recvMatchOctets += totlen;
 415
 416                 /* Truncate packet length if required by the filter */
 417                 if (len < totlen) {
 418                         m_adj(m, -(totlen - len));
 419                         totlen -= len;
 420                 }
 421                 dest = ng_findhook(hip->node, hip->prog->ifMatch);
 422         } else
 423                 dest = ng_findhook(hip->node, hip->prog->ifNotMatch);
 424         if (dest == NULL) {
 425                 NG_FREE_DATA(m, meta);
 426                 return (0);
 427         }
 428
 429         /* Deliver frame out destination hook */
 430         dhip = (hinfo_p)dest->private;
 431         dhip->stats.xmitOctets += totlen;
 432         dhip->stats.xmitFrames++;
 433         NG_SEND_DATA(error, dest, m, meta);
 434         return (error);
 435 }
 436
 437 /*
 438  * Shutdown processing
 439  */
 440 static int
 441 ng_bpf_rmnode(node_p node)
 442 {
 443         node->flags |= NG_INVALID;
 444         ng_cutlinks(node);
 445         ng_unname(node);
 446         ng_unref(node);
 447         return (0);
 448 }
 449
 450 /*
 451  * Hook disconnection
 452  */
 453 static int
 454 ng_bpf_disconnect(hook_p hook)
 455 {
 456         const hinfo_p hip = hook->private;
 457
 458         KASSERT(hip != NULL, ("%s: null info", __func__));
 459         kfree(hip->prog, M_NETGRAPH);
 460         bzero(hip, sizeof(*hip));
 461         kfree(hip, M_NETGRAPH);
 462         hook->private = NULL;                   /* for good measure */
 463         if (hook->node->numhooks == 0)
 464                 ng_rmnode(hook->node);
 465         return (0);
 466 }
 467
 468 /************************************************************************
 469                         HELPER STUFF
 470  ************************************************************************/
 471
 472 /*
 473  * Set the BPF program associated with a hook
 474  */
 475 static int
 476 ng_bpf_setprog(hook_p hook, const struct ng_bpf_hookprog *hp0)
 477 {
 478         const hinfo_p hip = hook->private;
 479         struct ng_bpf_hookprog *hp;
 480         int size;
 481
 482         /* Check program for validity */
 483         if (!bpf_validate(hp0->bpf_prog, hp0->bpf_prog_len))
 484                 return (EINVAL);
 485
 486         /* Make a copy of the program */
 487         size = NG_BPF_HOOKPROG_SIZE(hp0->bpf_prog_len);
 488         hp = kmalloc(size, M_NETGRAPH, M_NOWAIT);
 489         if (hp == NULL)
 490                 return (ENOMEM);
 491         bcopy(hp0, hp, size);
 492
 493         /* Free previous program, if any, and assign new one */
 494         if (hip->prog != NULL)
 495                 kfree(hip->prog, M_NETGRAPH);
 496         hip->prog = hp;
 497         return (0);
 498 }
 499