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
75static 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 */
85struct 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};
95typedef struct ng_bpf_hookinfo *hinfo_p;
96
97/* Netgraph methods */
98static ng_constructor_t	ng_bpf_constructor;
99static ng_rcvmsg_t	ng_bpf_rcvmsg;
100static ng_shutdown_t	ng_bpf_shutdown;
101static ng_newhook_t	ng_bpf_newhook;
102static ng_rcvdata_t	ng_bpf_rcvdata;
103static ng_disconnect_t	ng_bpf_disconnect;
104
105/* Maximum bpf program instructions */
106extern int	bpf_maxinsns;
107
108/* Internal helper functions */
109static int	ng_bpf_setprog(hook_p hook, const struct ng_bpf_hookprog *hp);
110
111/* Parse type for one struct bfp_insn */
112static 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};
119static 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 */
125static int
126ng_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
136static const struct ng_parse_array_info ng_bpf_hookprogary_info = {
137	&ng_bpf_insn_type,
138	&ng_bpf_hookprogary_getLength,
139	NULL
140};
141static 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 */
147static const struct ng_parse_struct_field ng_bpf_hookprog_type_fields[]
148	= NG_BPF_HOOKPROG_TYPE_INFO(&ng_bpf_hookprogary_type);
149static 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 */
155static const struct ng_parse_struct_field ng_bpf_hookstat_type_fields[]
156	= NG_BPF_HOOKSTAT_TYPE_INFO;
157static 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 */
163static 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 */
203static 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};
214NETGRAPH_INIT(bpf, &typestruct);
215
216/* Default BPF program for a hook that matches nothing */
217static 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 */
231static int
232ng_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 */
241static int
242ng_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
254static int
255ng_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 */
270static int
271ng_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 */
301static int
302ng_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	}
400done:
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 */
411static int
412ng_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);
476ready:
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 */
509static int
510ng_bpf_shutdown(node_p node)
511{
512	NG_NODE_UNREF(node);
513	return (0);
514}
515
516/*
517 * Hook disconnection
518 */
519static int
520ng_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 */
550static int
551ng_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}
590