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 *
40 * $FreeBSD$
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 "opt_bpf.h"
58
59#include <sys/param.h>
60#include <sys/systm.h>
61#include <sys/errno.h>
62#include <sys/kernel.h>
63#include <sys/malloc.h>
64#include <sys/mbuf.h>
65
66#include <net/bpf.h>
67#ifdef BPF_JITTER
68#include <net/bpf_jitter.h>
69#endif
70
71#include <netgraph/ng_message.h>
72#include <netgraph/netgraph.h>
73#include <netgraph/ng_parse.h>
74#include <netgraph/ng_bpf.h>
75
76#ifdef NG_SEPARATE_MALLOC
77static MALLOC_DEFINE(M_NETGRAPH_BPF, "netgraph_bpf", "netgraph bpf node");
78#else
79#define M_NETGRAPH_BPF M_NETGRAPH
80#endif
81
82#define OFFSETOF(s, e) ((char *)&((s *)0)->e - (char *)((s *)0))
83
84#define ERROUT(x)	do { error = (x); goto done; } while (0)
85
86/* Per hook private info */
87struct ng_bpf_hookinfo {
88	hook_p			hook;
89	hook_p			match;
90	hook_p			nomatch;
91	struct ng_bpf_hookprog	*prog;
92#ifdef BPF_JITTER
93	bpf_jit_filter		*jit_prog;
94#endif
95	struct ng_bpf_hookstat	stats;
96};
97typedef struct ng_bpf_hookinfo *hinfo_p;
98
99/* Netgraph methods */
100static ng_constructor_t	ng_bpf_constructor;
101static ng_rcvmsg_t	ng_bpf_rcvmsg;
102static ng_shutdown_t	ng_bpf_shutdown;
103static ng_newhook_t	ng_bpf_newhook;
104static ng_rcvdata_t	ng_bpf_rcvdata;
105static ng_disconnect_t	ng_bpf_disconnect;
106
107/* Maximum bpf program instructions */
108extern int	bpf_maxinsns;
109
110/* Internal helper functions */
111static int	ng_bpf_setprog(hook_p hook, const struct ng_bpf_hookprog *hp);
112
113/* Parse type for one struct bfp_insn */
114static const struct ng_parse_struct_field ng_bpf_insn_type_fields[] = {
115	{ "code",	&ng_parse_hint16_type	},
116	{ "jt",		&ng_parse_uint8_type	},
117	{ "jf",		&ng_parse_uint8_type	},
118	{ "k",		&ng_parse_uint32_type	},
119	{ NULL }
120};
121static const struct ng_parse_type ng_bpf_insn_type = {
122	&ng_parse_struct_type,
123	&ng_bpf_insn_type_fields
124};
125
126/* Parse type for the field 'bpf_prog' in struct ng_bpf_hookprog */
127static int
128ng_bpf_hookprogary_getLength(const struct ng_parse_type *type,
129	const u_char *start, const u_char *buf)
130{
131	const struct ng_bpf_hookprog *hp;
132
133	hp = (const struct ng_bpf_hookprog *)
134	    (buf - OFFSETOF(struct ng_bpf_hookprog, bpf_prog));
135	return hp->bpf_prog_len;
136}
137
138static const struct ng_parse_array_info ng_bpf_hookprogary_info = {
139	&ng_bpf_insn_type,
140	&ng_bpf_hookprogary_getLength,
141	NULL
142};
143static const struct ng_parse_type ng_bpf_hookprogary_type = {
144	&ng_parse_array_type,
145	&ng_bpf_hookprogary_info
146};
147
148/* Parse type for struct ng_bpf_hookprog */
149static const struct ng_parse_struct_field ng_bpf_hookprog_type_fields[]
150	= NG_BPF_HOOKPROG_TYPE_INFO(&ng_bpf_hookprogary_type);
151static const struct ng_parse_type ng_bpf_hookprog_type = {
152	&ng_parse_struct_type,
153	&ng_bpf_hookprog_type_fields
154};
155
156/* Parse type for struct ng_bpf_hookstat */
157static const struct ng_parse_struct_field ng_bpf_hookstat_type_fields[]
158	= NG_BPF_HOOKSTAT_TYPE_INFO;
159static const struct ng_parse_type ng_bpf_hookstat_type = {
160	&ng_parse_struct_type,
161	&ng_bpf_hookstat_type_fields
162};
163
164/* List of commands and how to convert arguments to/from ASCII */
165static const struct ng_cmdlist ng_bpf_cmdlist[] = {
166	{
167	  NGM_BPF_COOKIE,
168	  NGM_BPF_SET_PROGRAM,
169	  "setprogram",
170	  &ng_bpf_hookprog_type,
171	  NULL
172	},
173	{
174	  NGM_BPF_COOKIE,
175	  NGM_BPF_GET_PROGRAM,
176	  "getprogram",
177	  &ng_parse_hookbuf_type,
178	  &ng_bpf_hookprog_type
179	},
180	{
181	  NGM_BPF_COOKIE,
182	  NGM_BPF_GET_STATS,
183	  "getstats",
184	  &ng_parse_hookbuf_type,
185	  &ng_bpf_hookstat_type
186	},
187	{
188	  NGM_BPF_COOKIE,
189	  NGM_BPF_CLR_STATS,
190	  "clrstats",
191	  &ng_parse_hookbuf_type,
192	  NULL
193	},
194	{
195	  NGM_BPF_COOKIE,
196	  NGM_BPF_GETCLR_STATS,
197	  "getclrstats",
198	  &ng_parse_hookbuf_type,
199	  &ng_bpf_hookstat_type
200	},
201	{ 0 }
202};
203
204/* Netgraph type descriptor */
205static struct ng_type typestruct = {
206	.version =	NG_ABI_VERSION,
207	.name =		NG_BPF_NODE_TYPE,
208	.constructor =	ng_bpf_constructor,
209	.rcvmsg =	ng_bpf_rcvmsg,
210	.shutdown =	ng_bpf_shutdown,
211	.newhook =	ng_bpf_newhook,
212	.rcvdata =	ng_bpf_rcvdata,
213	.disconnect =	ng_bpf_disconnect,
214	.cmdlist =	ng_bpf_cmdlist,
215};
216NETGRAPH_INIT(bpf, &typestruct);
217
218/* Default BPF program for a hook that matches nothing */
219static const struct ng_bpf_hookprog ng_bpf_default_prog = {
220	{ '\0' },		/* to be filled in at hook creation time */
221	{ '\0' },
222	{ '\0' },
223	1,
224	{ BPF_STMT(BPF_RET+BPF_K, 0) }
225};
226
227/*
228 * Node constructor
229 *
230 * We don't keep any per-node private data
231 * We go via the hooks.
232 */
233static int
234ng_bpf_constructor(node_p node)
235{
236	NG_NODE_SET_PRIVATE(node, NULL);
237	return (0);
238}
239
240/*
241 * Callback functions to be used by NG_NODE_FOREACH_HOOK() macro.
242 */
243static int
244ng_bpf_addrefs(hook_p hook, void* arg)
245{
246	hinfo_p hip = NG_HOOK_PRIVATE(hook);
247	hook_p h = (hook_p)arg;
248
249	if (strcmp(hip->prog->ifMatch, NG_HOOK_NAME(h)) == 0)
250	    hip->match = h;
251	if (strcmp(hip->prog->ifNotMatch, NG_HOOK_NAME(h)) == 0)
252	    hip->nomatch = h;
253	return (1);
254}
255
256static int
257ng_bpf_remrefs(hook_p hook, void* arg)
258{
259	hinfo_p hip = NG_HOOK_PRIVATE(hook);
260	hook_p h = (hook_p)arg;
261
262	if (hip->match == h)
263	    hip->match = NULL;
264	if (hip->nomatch == h)
265	    hip->nomatch = NULL;
266	return (1);
267}
268
269/*
270 * Add a hook
271 */
272static int
273ng_bpf_newhook(node_p node, hook_p hook, const char *name)
274{
275	hinfo_p hip;
276	hook_p tmp;
277	int error;
278
279	/* Create hook private structure */
280	hip = malloc(sizeof(*hip), M_NETGRAPH_BPF, M_NOWAIT | M_ZERO);
281	if (hip == NULL)
282		return (ENOMEM);
283	hip->hook = hook;
284	NG_HOOK_SET_PRIVATE(hook, hip);
285
286	/* Add our reference into other hooks data. */
287	NG_NODE_FOREACH_HOOK(node, ng_bpf_addrefs, hook, tmp);
288
289	/* Attach the default BPF program */
290	if ((error = ng_bpf_setprog(hook, &ng_bpf_default_prog)) != 0) {
291		free(hip, M_NETGRAPH_BPF);
292		NG_HOOK_SET_PRIVATE(hook, NULL);
293		return (error);
294	}
295
296	/* Set hook name */
297	strlcpy(hip->prog->thisHook, name, sizeof(hip->prog->thisHook));
298	return (0);
299}
300
301/*
302 * Receive a control message
303 */
304static int
305ng_bpf_rcvmsg(node_p node, item_p item, hook_p lasthook)
306{
307	struct ng_mesg *msg;
308	struct ng_mesg *resp = NULL;
309	int error = 0;
310
311	NGI_GET_MSG(item, msg);
312	switch (msg->header.typecookie) {
313	case NGM_BPF_COOKIE:
314		switch (msg->header.cmd) {
315		case NGM_BPF_SET_PROGRAM:
316		    {
317			struct ng_bpf_hookprog *const
318			    hp = (struct ng_bpf_hookprog *)msg->data;
319			hook_p hook;
320
321			/* Sanity check */
322			if (msg->header.arglen < sizeof(*hp)
323			    || msg->header.arglen
324			      != NG_BPF_HOOKPROG_SIZE(hp->bpf_prog_len))
325				ERROUT(EINVAL);
326
327			/* Find hook */
328			if ((hook = ng_findhook(node, hp->thisHook)) == NULL)
329				ERROUT(ENOENT);
330
331			/* Set new program */
332			if ((error = ng_bpf_setprog(hook, hp)) != 0)
333				ERROUT(error);
334			break;
335		    }
336
337		case NGM_BPF_GET_PROGRAM:
338		    {
339			struct ng_bpf_hookprog *hp;
340			hook_p hook;
341
342			/* Sanity check */
343			if (msg->header.arglen == 0)
344				ERROUT(EINVAL);
345			msg->data[msg->header.arglen - 1] = '\0';
346
347			/* Find hook */
348			if ((hook = ng_findhook(node, msg->data)) == NULL)
349				ERROUT(ENOENT);
350
351			/* Build response */
352			hp = ((hinfo_p)NG_HOOK_PRIVATE(hook))->prog;
353			NG_MKRESPONSE(resp, msg,
354			    NG_BPF_HOOKPROG_SIZE(hp->bpf_prog_len), M_NOWAIT);
355			if (resp == NULL)
356				ERROUT(ENOMEM);
357			bcopy(hp, resp->data,
358			   NG_BPF_HOOKPROG_SIZE(hp->bpf_prog_len));
359			break;
360		    }
361
362		case NGM_BPF_GET_STATS:
363		case NGM_BPF_CLR_STATS:
364		case NGM_BPF_GETCLR_STATS:
365		    {
366			struct ng_bpf_hookstat *stats;
367			hook_p hook;
368
369			/* Sanity check */
370			if (msg->header.arglen == 0)
371				ERROUT(EINVAL);
372			msg->data[msg->header.arglen - 1] = '\0';
373
374			/* Find hook */
375			if ((hook = ng_findhook(node, msg->data)) == NULL)
376				ERROUT(ENOENT);
377			stats = &((hinfo_p)NG_HOOK_PRIVATE(hook))->stats;
378
379			/* Build response (if desired) */
380			if (msg->header.cmd != NGM_BPF_CLR_STATS) {
381				NG_MKRESPONSE(resp,
382				    msg, sizeof(*stats), M_NOWAIT);
383				if (resp == NULL)
384					ERROUT(ENOMEM);
385				bcopy(stats, resp->data, sizeof(*stats));
386			}
387
388			/* Clear stats (if desired) */
389			if (msg->header.cmd != NGM_BPF_GET_STATS)
390				bzero(stats, sizeof(*stats));
391			break;
392		    }
393
394		default:
395			error = EINVAL;
396			break;
397		}
398		break;
399	default:
400		error = EINVAL;
401		break;
402	}
403done:
404	NG_RESPOND_MSG(error, node, item, resp);
405	NG_FREE_MSG(msg);
406	return (error);
407}
408
409/*
410 * Receive data on a hook
411 *
412 * Apply the filter, and then drop or forward packet as appropriate.
413 */
414static int
415ng_bpf_rcvdata(hook_p hook, item_p item)
416{
417	const hinfo_p hip = NG_HOOK_PRIVATE(hook);
418	int totlen;
419	int needfree = 0, error = 0, usejit = 0;
420	u_char *data = NULL;
421	hinfo_p dhip;
422	hook_p dest;
423	u_int len;
424	struct mbuf *m;
425
426	m = NGI_M(item);	/* 'item' still owns it.. we are peeking */
427	totlen = m->m_pkthdr.len;
428	/* Update stats on incoming hook. XXX Can we do 64 bits atomically? */
429	/* atomic_add_int64(&hip->stats.recvFrames, 1); */
430	/* atomic_add_int64(&hip->stats.recvOctets, totlen); */
431	hip->stats.recvFrames++;
432	hip->stats.recvOctets += totlen;
433
434	/* Don't call bpf_filter() with totlen == 0! */
435	if (totlen == 0) {
436		len = 0;
437		goto ready;
438	}
439
440#ifdef BPF_JITTER
441	if (bpf_jitter_enable != 0 && hip->jit_prog != NULL)
442		usejit = 1;
443#endif
444
445	/* Need to put packet in contiguous memory for bpf */
446	if (m->m_next != NULL && totlen > MHLEN) {
447		if (usejit) {
448			data = malloc(totlen, M_NETGRAPH_BPF, M_NOWAIT);
449			if (data == NULL) {
450				NG_FREE_ITEM(item);
451				return (ENOMEM);
452			}
453			needfree = 1;
454			m_copydata(m, 0, totlen, (caddr_t)data);
455		}
456	} else {
457		if (m->m_next != NULL) {
458			NGI_M(item) = m = m_pullup(m, totlen);
459			if (m == NULL) {
460				NG_FREE_ITEM(item);
461				return (ENOBUFS);
462			}
463		}
464		data = mtod(m, u_char *);
465	}
466
467	/* Run packet through filter */
468#ifdef BPF_JITTER
469	if (usejit)
470		len = (*(hip->jit_prog->func))(data, totlen, totlen);
471	else
472#endif
473	if (data)
474		len = bpf_filter(hip->prog->bpf_prog, data, totlen, totlen);
475	else
476		len = bpf_filter(hip->prog->bpf_prog, (u_char *)m, totlen, 0);
477	if (needfree)
478		free(data, M_NETGRAPH_BPF);
479ready:
480	/* See if we got a match and find destination hook */
481	if (len > 0) {
482
483		/* Update stats */
484		/* XXX atomically? */
485		hip->stats.recvMatchFrames++;
486		hip->stats.recvMatchOctets += totlen;
487
488		/* Truncate packet length if required by the filter */
489		/* Assume this never changes m */
490		if (len < totlen) {
491			m_adj(m, -(totlen - len));
492			totlen = len;
493		}
494		dest = hip->match;
495	} else
496		dest = hip->nomatch;
497	if (dest == NULL) {
498		NG_FREE_ITEM(item);
499		return (0);
500	}
501
502	/* Deliver frame out destination hook */
503	dhip = NG_HOOK_PRIVATE(dest);
504	dhip->stats.xmitOctets += totlen;
505	dhip->stats.xmitFrames++;
506	NG_FWD_ITEM_HOOK(error, item, dest);
507	return (error);
508}
509
510/*
511 * Shutdown processing
512 */
513static int
514ng_bpf_shutdown(node_p node)
515{
516	NG_NODE_UNREF(node);
517	return (0);
518}
519
520/*
521 * Hook disconnection
522 */
523static int
524ng_bpf_disconnect(hook_p hook)
525{
526	const node_p node = NG_HOOK_NODE(hook);
527	const hinfo_p hip = NG_HOOK_PRIVATE(hook);
528	hook_p tmp;
529
530	KASSERT(hip != NULL, ("%s: null info", __func__));
531
532	/* Remove our reference from other hooks data. */
533	NG_NODE_FOREACH_HOOK(node, ng_bpf_remrefs, hook, tmp);
534
535	free(hip->prog, M_NETGRAPH_BPF);
536#ifdef BPF_JITTER
537	if (hip->jit_prog != NULL)
538		bpf_destroy_jit_filter(hip->jit_prog);
539#endif
540	free(hip, M_NETGRAPH_BPF);
541	if ((NG_NODE_NUMHOOKS(node) == 0) &&
542	    (NG_NODE_IS_VALID(node))) {
543		ng_rmnode_self(node);
544	}
545	return (0);
546}
547
548/************************************************************************
549			HELPER STUFF
550 ************************************************************************/
551
552/*
553 * Set the BPF program associated with a hook
554 */
555static int
556ng_bpf_setprog(hook_p hook, const struct ng_bpf_hookprog *hp0)
557{
558	const hinfo_p hip = NG_HOOK_PRIVATE(hook);
559	struct ng_bpf_hookprog *hp;
560#ifdef BPF_JITTER
561	bpf_jit_filter *jit_prog;
562#endif
563	int size;
564
565	/* Check program for validity */
566	if (hp0->bpf_prog_len > bpf_maxinsns ||
567	    !bpf_validate(hp0->bpf_prog, hp0->bpf_prog_len))
568		return (EINVAL);
569
570	/* Make a copy of the program */
571	size = NG_BPF_HOOKPROG_SIZE(hp0->bpf_prog_len);
572	hp = malloc(size, M_NETGRAPH_BPF, M_NOWAIT);
573	if (hp == NULL)
574		return (ENOMEM);
575	bcopy(hp0, hp, size);
576#ifdef BPF_JITTER
577	jit_prog = bpf_jitter(hp->bpf_prog, hp->bpf_prog_len);
578#endif
579
580	/* Free previous program, if any, and assign new one */
581	if (hip->prog != NULL)
582		free(hip->prog, M_NETGRAPH_BPF);
583	hip->prog = hp;
584#ifdef BPF_JITTER
585	if (hip->jit_prog != NULL)
586		bpf_destroy_jit_filter(hip->jit_prog);
587	hip->jit_prog = jit_prog;
588#endif
589
590	/* Prepare direct references on target hooks. */
591	hip->match = ng_findhook(NG_HOOK_NODE(hook), hip->prog->ifMatch);
592	hip->nomatch = ng_findhook(NG_HOOK_NODE(hook), hip->prog->ifNotMatch);
593	return (0);
594}
595