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