ng_bpf.c revision 175776 
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: head/sys/netgraph/ng_bpf.c 175776 2008-01-28 22:37:17Z mav $
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
77MALLOC_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	node_p			node;
89	hook_p			hook;
90	struct ng_bpf_hookprog	*prog;
91#ifdef BPF_JITTER
92	bpf_jit_filter		*jit_prog;
93#endif
94	struct ng_bpf_hookstat	stats;
95};
96typedef struct ng_bpf_hookinfo *hinfo_p;
97
98/* Netgraph methods */
99static ng_constructor_t	ng_bpf_constructor;
100static ng_rcvmsg_t	ng_bpf_rcvmsg;
101static ng_shutdown_t	ng_bpf_shutdown;
102static ng_newhook_t	ng_bpf_newhook;
103static ng_rcvdata_t	ng_bpf_rcvdata;
104static ng_disconnect_t	ng_bpf_disconnect;
105
106/* Internal helper functions */
107static int	ng_bpf_setprog(hook_p hook, const struct ng_bpf_hookprog *hp);
108
109/* Parse type for one struct bfp_insn */
110static const struct ng_parse_struct_field ng_bpf_insn_type_fields[] = {
111	{ "code",	&ng_parse_hint16_type	},
112	{ "jt",		&ng_parse_uint8_type	},
113	{ "jf",		&ng_parse_uint8_type	},
114	{ "k",		&ng_parse_uint32_type	},
115	{ NULL }
116};
117static const struct ng_parse_type ng_bpf_insn_type = {
118	&ng_parse_struct_type,
119	&ng_bpf_insn_type_fields
120};
121
122/* Parse type for the field 'bpf_prog' in struct ng_bpf_hookprog */
123static int
124ng_bpf_hookprogary_getLength(const struct ng_parse_type *type,
125	const u_char *start, const u_char *buf)
126{
127	const struct ng_bpf_hookprog *hp;
128
129	hp = (const struct ng_bpf_hookprog *)
130	    (buf - OFFSETOF(struct ng_bpf_hookprog, bpf_prog));
131	return hp->bpf_prog_len;
132}
133
134static const struct ng_parse_array_info ng_bpf_hookprogary_info = {
135	&ng_bpf_insn_type,
136	&ng_bpf_hookprogary_getLength,
137	NULL
138};
139static const struct ng_parse_type ng_bpf_hookprogary_type = {
140	&ng_parse_array_type,
141	&ng_bpf_hookprogary_info
142};
143
144/* Parse type for struct ng_bpf_hookprog */
145static const struct ng_parse_struct_field ng_bpf_hookprog_type_fields[]
146	= NG_BPF_HOOKPROG_TYPE_INFO(&ng_bpf_hookprogary_type);
147static const struct ng_parse_type ng_bpf_hookprog_type = {
148	&ng_parse_struct_type,
149	&ng_bpf_hookprog_type_fields
150};
151
152/* Parse type for struct ng_bpf_hookstat */
153static const struct ng_parse_struct_field ng_bpf_hookstat_type_fields[]
154	= NG_BPF_HOOKSTAT_TYPE_INFO;
155static const struct ng_parse_type ng_bpf_hookstat_type = {
156	&ng_parse_struct_type,
157	&ng_bpf_hookstat_type_fields
158};
159
160/* List of commands and how to convert arguments to/from ASCII */
161static const struct ng_cmdlist ng_bpf_cmdlist[] = {
162	{
163	  NGM_BPF_COOKIE,
164	  NGM_BPF_SET_PROGRAM,
165	  "setprogram",
166	  &ng_bpf_hookprog_type,
167	  NULL
168	},
169	{
170	  NGM_BPF_COOKIE,
171	  NGM_BPF_GET_PROGRAM,
172	  "getprogram",
173	  &ng_parse_hookbuf_type,
174	  &ng_bpf_hookprog_type
175	},
176	{
177	  NGM_BPF_COOKIE,
178	  NGM_BPF_GET_STATS,
179	  "getstats",
180	  &ng_parse_hookbuf_type,
181	  &ng_bpf_hookstat_type
182	},
183	{
184	  NGM_BPF_COOKIE,
185	  NGM_BPF_CLR_STATS,
186	  "clrstats",
187	  &ng_parse_hookbuf_type,
188	  NULL
189	},
190	{
191	  NGM_BPF_COOKIE,
192	  NGM_BPF_GETCLR_STATS,
193	  "getclrstats",
194	  &ng_parse_hookbuf_type,
195	  &ng_bpf_hookstat_type
196	},
197	{ 0 }
198};
199
200/* Netgraph type descriptor */
201static struct ng_type typestruct = {
202	.version =	NG_ABI_VERSION,
203	.name =		NG_BPF_NODE_TYPE,
204	.constructor =	ng_bpf_constructor,
205	.rcvmsg =	ng_bpf_rcvmsg,
206	.shutdown =	ng_bpf_shutdown,
207	.newhook =	ng_bpf_newhook,
208	.rcvdata =	ng_bpf_rcvdata,
209	.disconnect =	ng_bpf_disconnect,
210	.cmdlist =	ng_bpf_cmdlist,
211};
212NETGRAPH_INIT(bpf, &typestruct);
213
214/* Default BPF program for a hook that matches nothing */
215static const struct ng_bpf_hookprog ng_bpf_default_prog = {
216	{ '\0' },		/* to be filled in at hook creation time */
217	{ '\0' },
218	{ '\0' },
219	1,
220	{ BPF_STMT(BPF_RET+BPF_K, 0) }
221};
222
223/*
224 * Node constructor
225 *
226 * We don't keep any per-node private data
227 * We go via the hooks.
228 */
229static int
230ng_bpf_constructor(node_p node)
231{
232	NG_NODE_SET_PRIVATE(node, NULL);
233	return (0);
234}
235
236/*
237 * Add a hook
238 */
239static int
240ng_bpf_newhook(node_p node, hook_p hook, const char *name)
241{
242	hinfo_p hip;
243	int error;
244
245	/* Create hook private structure */
246	MALLOC(hip, hinfo_p, sizeof(*hip), M_NETGRAPH_BPF, M_NOWAIT | M_ZERO);
247	if (hip == NULL)
248		return (ENOMEM);
249	hip->hook = hook;
250	NG_HOOK_SET_PRIVATE(hook, hip);
251	hip->node = node;
252
253	/* Attach the default BPF program */
254	if ((error = ng_bpf_setprog(hook, &ng_bpf_default_prog)) != 0) {
255		FREE(hip, M_NETGRAPH_BPF);
256		NG_HOOK_SET_PRIVATE(hook, NULL);
257		return (error);
258	}
259
260	/* Set hook name */
261	strncpy(hip->prog->thisHook, name, sizeof(hip->prog->thisHook) - 1);
262	hip->prog->thisHook[sizeof(hip->prog->thisHook) - 1] = '\0';
263	return (0);
264}
265
266/*
267 * Receive a control message
268 */
269static int
270ng_bpf_rcvmsg(node_p node, item_p item, hook_p lasthook)
271{
272	struct ng_mesg *msg;
273	struct ng_mesg *resp = NULL;
274	int error = 0;
275
276	NGI_GET_MSG(item, msg);
277	switch (msg->header.typecookie) {
278	case NGM_BPF_COOKIE:
279		switch (msg->header.cmd) {
280		case NGM_BPF_SET_PROGRAM:
281		    {
282			struct ng_bpf_hookprog *const
283			    hp = (struct ng_bpf_hookprog *)msg->data;
284			hook_p hook;
285
286			/* Sanity check */
287			if (msg->header.arglen < sizeof(*hp)
288			    || msg->header.arglen
289			      != NG_BPF_HOOKPROG_SIZE(hp->bpf_prog_len))
290				ERROUT(EINVAL);
291
292			/* Find hook */
293			if ((hook = ng_findhook(node, hp->thisHook)) == NULL)
294				ERROUT(ENOENT);
295
296			/* Set new program */
297			if ((error = ng_bpf_setprog(hook, hp)) != 0)
298				ERROUT(error);
299			break;
300		    }
301
302		case NGM_BPF_GET_PROGRAM:
303		    {
304			struct ng_bpf_hookprog *hp;
305			hook_p hook;
306
307			/* Sanity check */
308			if (msg->header.arglen == 0)
309				ERROUT(EINVAL);
310			msg->data[msg->header.arglen - 1] = '\0';
311
312			/* Find hook */
313			if ((hook = ng_findhook(node, msg->data)) == NULL)
314				ERROUT(ENOENT);
315
316			/* Build response */
317			hp = ((hinfo_p)NG_HOOK_PRIVATE(hook))->prog;
318			NG_MKRESPONSE(resp, msg,
319			    NG_BPF_HOOKPROG_SIZE(hp->bpf_prog_len), M_NOWAIT);
320			if (resp == NULL)
321				ERROUT(ENOMEM);
322			bcopy(hp, resp->data,
323			   NG_BPF_HOOKPROG_SIZE(hp->bpf_prog_len));
324			break;
325		    }
326
327		case NGM_BPF_GET_STATS:
328		case NGM_BPF_CLR_STATS:
329		case NGM_BPF_GETCLR_STATS:
330		    {
331			struct ng_bpf_hookstat *stats;
332			hook_p hook;
333
334			/* Sanity check */
335			if (msg->header.arglen == 0)
336				ERROUT(EINVAL);
337			msg->data[msg->header.arglen - 1] = '\0';
338
339			/* Find hook */
340			if ((hook = ng_findhook(node, msg->data)) == NULL)
341				ERROUT(ENOENT);
342			stats = &((hinfo_p)NG_HOOK_PRIVATE(hook))->stats;
343
344			/* Build response (if desired) */
345			if (msg->header.cmd != NGM_BPF_CLR_STATS) {
346				NG_MKRESPONSE(resp,
347				    msg, sizeof(*stats), M_NOWAIT);
348				if (resp == NULL)
349					ERROUT(ENOMEM);
350				bcopy(stats, resp->data, sizeof(*stats));
351			}
352
353			/* Clear stats (if desired) */
354			if (msg->header.cmd != NGM_BPF_GET_STATS)
355				bzero(stats, sizeof(*stats));
356			break;
357		    }
358
359		default:
360			error = EINVAL;
361			break;
362		}
363		break;
364	default:
365		error = EINVAL;
366		break;
367	}
368done:
369	NG_RESPOND_MSG(error, node, item, resp);
370	NG_FREE_MSG(msg);
371	return (error);
372}
373
374/*
375 * Receive data on a hook
376 *
377 * Apply the filter, and then drop or forward packet as appropriate.
378 */
379static int
380ng_bpf_rcvdata(hook_p hook, item_p item)
381{
382	const hinfo_p hip = NG_HOOK_PRIVATE(hook);
383	int totlen;
384	int needfree = 0, error = 0, usejit = 0;
385	u_char *data = NULL;
386	hinfo_p dhip;
387	hook_p dest;
388	u_int len;
389	struct mbuf *m;
390
391	m = NGI_M(item);	/* 'item' still owns it.. we are peeking */
392	totlen = m->m_pkthdr.len;
393	/* Update stats on incoming hook. XXX Can we do 64 bits atomically? */
394	/* atomic_add_int64(&hip->stats.recvFrames, 1); */
395	/* atomic_add_int64(&hip->stats.recvOctets, totlen); */
396	hip->stats.recvFrames++;
397	hip->stats.recvOctets += totlen;
398
399#ifdef BPF_JITTER
400	if (bpf_jitter_enable != 0 && hip->jit_prog != NULL)
401		usejit = 1;
402#endif
403
404	/* Need to put packet in contiguous memory for bpf */
405	if (m->m_next != NULL && totlen > MHLEN) {
406		if (usejit) {
407			MALLOC(data, u_char *, totlen, M_NETGRAPH_BPF, M_NOWAIT);
408			if (data == NULL) {
409				NG_FREE_ITEM(item);
410				return (ENOMEM);
411			}
412			needfree = 1;
413			m_copydata(m, 0, totlen, (caddr_t)data);
414		}
415	} else {
416		if (m->m_next != NULL) {
417			NGI_M(item) = m = m_pullup(m, totlen);
418			if (m == NULL) {
419				NG_FREE_ITEM(item);
420				return (ENOBUFS);
421			}
422		}
423		data = mtod(m, u_char *);
424	}
425
426	/* Run packet through filter */
427	if (totlen == 0)
428		len = 0;	/* don't call bpf_filter() with totlen == 0! */
429	else {
430#ifdef BPF_JITTER
431		if (usejit)
432			len = (*(hip->jit_prog->func))(data, totlen, totlen);
433		else
434#endif
435		if (data) {
436			len = bpf_filter(hip->prog->bpf_prog, data,
437			    totlen, totlen);
438		} else {
439			len = bpf_filter(hip->prog->bpf_prog, (u_char *) m,
440			    totlen, 0);
441		}
442	}
443	if (needfree)
444		FREE(data, M_NETGRAPH_BPF);
445
446	/* See if we got a match and find destination hook */
447	if (len > 0) {
448
449		/* Update stats */
450		/* XXX atomically? */
451		hip->stats.recvMatchFrames++;
452		hip->stats.recvMatchOctets += totlen;
453
454		/* Truncate packet length if required by the filter */
455		/* Assume this never changes m */
456		if (len < totlen) {
457			m_adj(m, -(totlen - len));
458			totlen -= len;
459		}
460		dest = ng_findhook(hip->node, hip->prog->ifMatch);
461	} else
462		dest = ng_findhook(hip->node, hip->prog->ifNotMatch);
463	if (dest == NULL) {
464		NG_FREE_ITEM(item);
465		return (0);
466	}
467
468	/* Deliver frame out destination hook */
469	dhip = NG_HOOK_PRIVATE(dest);
470	dhip->stats.xmitOctets += totlen;
471	dhip->stats.xmitFrames++;
472	NG_FWD_ITEM_HOOK(error, item, dest);
473	return (error);
474}
475
476/*
477 * Shutdown processing
478 */
479static int
480ng_bpf_shutdown(node_p node)
481{
482	NG_NODE_UNREF(node);
483	return (0);
484}
485
486/*
487 * Hook disconnection
488 */
489static int
490ng_bpf_disconnect(hook_p hook)
491{
492	const hinfo_p hip = NG_HOOK_PRIVATE(hook);
493
494	KASSERT(hip != NULL, ("%s: null info", __func__));
495	FREE(hip->prog, M_NETGRAPH_BPF);
496#ifdef BPF_JITTER
497	if (hip->jit_prog != NULL)
498		bpf_destroy_jit_filter(hip->jit_prog);
499#endif
500	bzero(hip, sizeof(*hip));
501	FREE(hip, M_NETGRAPH_BPF);
502	NG_HOOK_SET_PRIVATE(hook, NULL);			/* for good measure */
503	if ((NG_NODE_NUMHOOKS(NG_HOOK_NODE(hook)) == 0)
504	&& (NG_NODE_IS_VALID(NG_HOOK_NODE(hook)))) {
505		ng_rmnode_self(NG_HOOK_NODE(hook));
506	}
507	return (0);
508}
509
510/************************************************************************
511			HELPER STUFF
512 ************************************************************************/
513
514/*
515 * Set the BPF program associated with a hook
516 */
517static int
518ng_bpf_setprog(hook_p hook, const struct ng_bpf_hookprog *hp0)
519{
520	const hinfo_p hip = NG_HOOK_PRIVATE(hook);
521	struct ng_bpf_hookprog *hp;
522#ifdef BPF_JITTER
523	bpf_jit_filter *jit_prog;
524#endif
525	int size;
526
527	/* Check program for validity */
528	if (!bpf_validate(hp0->bpf_prog, hp0->bpf_prog_len))
529		return (EINVAL);
530
531	/* Make a copy of the program */
532	size = NG_BPF_HOOKPROG_SIZE(hp0->bpf_prog_len);
533	MALLOC(hp, struct ng_bpf_hookprog *, size, M_NETGRAPH_BPF, M_NOWAIT);
534	if (hp == NULL)
535		return (ENOMEM);
536	bcopy(hp0, hp, size);
537#ifdef BPF_JITTER
538	jit_prog = bpf_jitter(hp->bpf_prog, hp->bpf_prog_len);
539#endif
540
541	/* Free previous program, if any, and assign new one */
542	if (hip->prog != NULL)
543		FREE(hip->prog, M_NETGRAPH_BPF);
544	hip->prog = hp;
545#ifdef BPF_JITTER
546	if (hip->jit_prog != NULL)
547		bpf_destroy_jit_filter(hip->jit_prog);
548	hip->jit_prog = jit_prog;
549#endif
550	return (0);
551}
552