ng_bpf.c revision 70870 
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: head/sys/netgraph/ng_bpf.c 70870 2001-01-10 07:13:58Z julian $
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 <netgraph/ng_bpf.h>
69
70#ifdef NG_SEPARATE_MALLOC
71MALLOC_DEFINE(M_NETGRAPH_BPF, "netgraph_bpf", "netgraph bpf node ");
72#else
73#define M_NETGRAPH_BPF M_NETGRAPH
74#endif
75
76#define OFFSETOF(s, e) ((char *)&((s *)0)->e - (char *)((s *)0))
77
78#define ERROUT(x)	do { error = (x); goto done; } while (0)
79
80/* Per hook private info */
81struct ng_bpf_hookinfo {
82	node_p			node;
83	hook_p			hook;
84	struct ng_bpf_hookprog	*prog;
85	struct ng_bpf_hookstat	stats;
86};
87typedef struct ng_bpf_hookinfo *hinfo_p;
88
89/* Netgraph methods */
90static ng_constructor_t	ng_bpf_constructor;
91static ng_rcvmsg_t	ng_bpf_rcvmsg;
92static ng_shutdown_t	ng_bpf_shutdown;
93static ng_newhook_t	ng_bpf_newhook;
94static ng_rcvdata_t	ng_bpf_rcvdata;
95static ng_disconnect_t	ng_bpf_disconnect;
96
97/* Internal helper functions */
98static int	ng_bpf_setprog(hook_p hook, const struct ng_bpf_hookprog *hp);
99
100/* Parse type for one struct bfp_insn */
101static const struct ng_parse_struct_info ng_bpf_insn_type_info = {
102    {
103	{ "code",	&ng_parse_hint16_type	},
104	{ "jt",		&ng_parse_uint8_type	},
105	{ "jf",		&ng_parse_uint8_type	},
106	{ "k",		&ng_parse_uint32_type	},
107	{ NULL }
108    }
109};
110static const struct ng_parse_type ng_bpf_insn_type = {
111	&ng_parse_struct_type,
112	&ng_bpf_insn_type_info
113};
114
115/* Parse type for the field 'bpf_prog' in struct ng_bpf_hookprog */
116static int
117ng_bpf_hookprogary_getLength(const struct ng_parse_type *type,
118	const u_char *start, const u_char *buf)
119{
120	const struct ng_bpf_hookprog *hp;
121
122	hp = (const struct ng_bpf_hookprog *)
123	    (buf - OFFSETOF(struct ng_bpf_hookprog, bpf_prog));
124	return hp->bpf_prog_len;
125}
126
127static const struct ng_parse_array_info ng_bpf_hookprogary_info = {
128	&ng_bpf_insn_type,
129	&ng_bpf_hookprogary_getLength,
130	NULL
131};
132static const struct ng_parse_type ng_bpf_hookprogary_type = {
133	&ng_parse_array_type,
134	&ng_bpf_hookprogary_info
135};
136
137/* Parse type for struct ng_bpf_hookprog */
138static const struct ng_parse_struct_info ng_bpf_hookprog_type_info
139	= NG_BPF_HOOKPROG_TYPE_INFO(&ng_bpf_hookprogary_type);
140static const struct ng_parse_type ng_bpf_hookprog_type = {
141	&ng_parse_struct_type,
142	&ng_bpf_hookprog_type_info
143};
144
145/* Parse type for struct ng_bpf_hookstat */
146static const struct ng_parse_struct_info
147	ng_bpf_hookstat_type_info = NG_BPF_HOOKSTAT_TYPE_INFO;
148static const struct ng_parse_type ng_bpf_hookstat_type = {
149	&ng_parse_struct_type,
150	&ng_bpf_hookstat_type_info
151};
152
153/* List of commands and how to convert arguments to/from ASCII */
154static const struct ng_cmdlist ng_bpf_cmdlist[] = {
155	{
156	  NGM_BPF_COOKIE,
157	  NGM_BPF_SET_PROGRAM,
158	  "setprogram",
159	  &ng_bpf_hookprog_type,
160	  NULL
161	},
162	{
163	  NGM_BPF_COOKIE,
164	  NGM_BPF_GET_PROGRAM,
165	  "getprogram",
166	  &ng_parse_hookbuf_type,
167	  &ng_bpf_hookprog_type
168	},
169	{
170	  NGM_BPF_COOKIE,
171	  NGM_BPF_GET_STATS,
172	  "getstats",
173	  &ng_parse_hookbuf_type,
174	  &ng_bpf_hookstat_type
175	},
176	{
177	  NGM_BPF_COOKIE,
178	  NGM_BPF_CLR_STATS,
179	  "clrstats",
180	  &ng_parse_hookbuf_type,
181	  NULL
182	},
183	{
184	  NGM_BPF_COOKIE,
185	  NGM_BPF_GETCLR_STATS,
186	  "getclrstats",
187	  &ng_parse_hookbuf_type,
188	  &ng_bpf_hookstat_type
189	},
190	{ 0 }
191};
192
193/* Netgraph type descriptor */
194static struct ng_type typestruct = {
195	NG_ABI_VERSION,
196	NG_BPF_NODE_TYPE,
197	NULL,
198	ng_bpf_constructor,
199	ng_bpf_rcvmsg,
200	ng_bpf_shutdown,
201	ng_bpf_newhook,
202	NULL,
203	NULL,
204	ng_bpf_rcvdata,
205	ng_bpf_disconnect,
206	ng_bpf_cmdlist
207};
208NETGRAPH_INIT(bpf, &typestruct);
209
210/* Default BPF program for a hook that matches nothing */
211static const struct ng_bpf_hookprog ng_bpf_default_prog = {
212	{ '\0' },		/* to be filled in at hook creation time */
213	{ '\0' },
214	{ '\0' },
215	1,
216	{ BPF_STMT(BPF_RET+BPF_K, 0) }
217};
218
219/*
220 * Node constructor
221 *
222 * We don't keep any per-node private data
223 * We go via the hooks.
224 */
225static int
226ng_bpf_constructor(node_p node)
227{
228	NG_NODE_SET_PRIVATE(node, NULL);
229	return (0);
230}
231
232/*
233 * Add a hook
234 */
235static int
236ng_bpf_newhook(node_p node, hook_p hook, const char *name)
237{
238	hinfo_p hip;
239	int error;
240
241	/* Create hook private structure */
242	MALLOC(hip, hinfo_p, sizeof(*hip), M_NETGRAPH_BPF, M_NOWAIT | M_ZERO);
243	if (hip == NULL)
244		return (ENOMEM);
245	hip->hook = hook;
246	NG_HOOK_SET_PRIVATE(hook, hip);
247	hip->node = node;
248
249	/* Attach the default BPF program */
250	if ((error = ng_bpf_setprog(hook, &ng_bpf_default_prog)) != 0) {
251		FREE(hip, M_NETGRAPH_BPF);
252		NG_HOOK_SET_PRIVATE(hook, NULL);
253		return (error);
254	}
255
256	/* Set hook name */
257	strncpy(hip->prog->thisHook, name, sizeof(hip->prog->thisHook) - 1);
258	hip->prog->thisHook[sizeof(hip->prog->thisHook) - 1] = '\0';
259	return (0);
260}
261
262/*
263 * Receive a control message
264 */
265static int
266ng_bpf_rcvmsg(node_p node, item_p item, hook_p lasthook)
267{
268	struct ng_mesg *msg;
269	struct ng_mesg *resp = NULL;
270	int error = 0;
271
272	NGI_GET_MSG(item, msg);
273	switch (msg->header.typecookie) {
274	case NGM_BPF_COOKIE:
275		switch (msg->header.cmd) {
276		case NGM_BPF_SET_PROGRAM:
277		    {
278			struct ng_bpf_hookprog *const
279			    hp = (struct ng_bpf_hookprog *)msg->data;
280			hook_p hook;
281
282			/* Sanity check */
283			if (msg->header.arglen < sizeof(*hp)
284			    || msg->header.arglen
285			      != NG_BPF_HOOKPROG_SIZE(hp->bpf_prog_len))
286				ERROUT(EINVAL);
287
288			/* Find hook */
289			if ((hook = ng_findhook(node, hp->thisHook)) == NULL)
290				ERROUT(ENOENT);
291
292			/* Set new program */
293			if ((error = ng_bpf_setprog(hook, hp)) != 0)
294				ERROUT(error);
295			break;
296		    }
297
298		case NGM_BPF_GET_PROGRAM:
299		    {
300			struct ng_bpf_hookprog *hp;
301			hook_p hook;
302
303			/* Sanity check */
304			if (msg->header.arglen == 0)
305				ERROUT(EINVAL);
306			msg->data[msg->header.arglen - 1] = '\0';
307
308			/* Find hook */
309			if ((hook = ng_findhook(node, msg->data)) == NULL)
310				ERROUT(ENOENT);
311
312			/* Build response */
313			hp = ((hinfo_p)NG_HOOK_PRIVATE(hook))->prog;
314			NG_MKRESPONSE(resp, msg,
315			    NG_BPF_HOOKPROG_SIZE(hp->bpf_prog_len), M_NOWAIT);
316			if (resp == NULL)
317				ERROUT(ENOMEM);
318			bcopy(hp, resp->data,
319			   NG_BPF_HOOKPROG_SIZE(hp->bpf_prog_len));
320			break;
321		    }
322
323		case NGM_BPF_GET_STATS:
324		case NGM_BPF_CLR_STATS:
325		case NGM_BPF_GETCLR_STATS:
326		    {
327			struct ng_bpf_hookstat *stats;
328			hook_p hook;
329
330			/* Sanity check */
331			if (msg->header.arglen == 0)
332				ERROUT(EINVAL);
333			msg->data[msg->header.arglen - 1] = '\0';
334
335			/* Find hook */
336			if ((hook = ng_findhook(node, msg->data)) == NULL)
337				ERROUT(ENOENT);
338			stats = &((hinfo_p)NG_HOOK_PRIVATE(hook))->stats;
339
340			/* Build response (if desired) */
341			if (msg->header.cmd != NGM_BPF_CLR_STATS) {
342				NG_MKRESPONSE(resp,
343				    msg, sizeof(*stats), M_NOWAIT);
344				if (resp == NULL)
345					ERROUT(ENOMEM);
346				bcopy(stats, resp->data, sizeof(*stats));
347			}
348
349			/* Clear stats (if desired) */
350			if (msg->header.cmd != NGM_BPF_GET_STATS)
351				bzero(stats, sizeof(*stats));
352			break;
353		    }
354
355		default:
356			error = EINVAL;
357			break;
358		}
359		break;
360	default:
361		error = EINVAL;
362		break;
363	}
364	NG_RESPOND_MSG(error, node, item, resp);
365done:
366	if (item)
367		NG_FREE_ITEM(item);
368	NG_FREE_MSG(msg);
369	return (error);
370}
371
372/*
373 * Receive data on a hook
374 *
375 * Apply the filter, and then drop or forward packet as appropriate.
376 */
377static int
378ng_bpf_rcvdata(hook_p hook, item_p item)
379{
380	const hinfo_p hip = NG_HOOK_PRIVATE(hook);
381	int totlen;
382	int needfree = 0, error = 0;
383	u_char *data, buf[256];
384	hinfo_p dhip;
385	hook_p dest;
386	u_int len;
387	struct mbuf *m;
388
389	m = NGI_M(item);	/* 'item' still owns it.. we are peeking */
390	totlen = m->m_pkthdr.len;
391	/* Update stats on incoming hook. XXX Can we do 64 bits atomically? */
392	/* atomic_add_int64(&hip->stats.recvFrames, 1); */
393	/* atomic_add_int64(&hip->stats.recvOctets, totlen); */
394	hip->stats.recvFrames++;
395	hip->stats.recvOctets += totlen;
396
397	/* Need to put packet in contiguous memory for bpf */
398	if (m->m_next != NULL) {
399		if (totlen > sizeof(buf)) {
400			MALLOC(data, u_char *, totlen, M_NETGRAPH_BPF, M_NOWAIT);
401			if (data == NULL) {
402				NG_FREE_ITEM(item);
403				return (ENOMEM);
404			}
405			needfree = 1;
406		} else
407			data = buf;
408		m_copydata(m, 0, totlen, (caddr_t)data);
409	} else
410		data = mtod(m, u_char *);
411
412	/* Run packet through filter */
413	len = bpf_filter(hip->prog->bpf_prog, data, totlen, totlen);
414	if (needfree)
415		FREE(data, M_NETGRAPH_BPF);
416
417	/* See if we got a match and find destination hook */
418	if (len > 0) {
419
420		/* Update stats */
421		/* XXX atomically? */
422		hip->stats.recvMatchFrames++;
423		hip->stats.recvMatchOctets += totlen;
424
425		/* Truncate packet length if required by the filter */
426		/* Assume this never changes m */
427		if (len < totlen) {
428			m_adj(m, -(totlen - len));
429			totlen -= len;
430		}
431		dest = ng_findhook(hip->node, hip->prog->ifMatch);
432	} else
433		dest = ng_findhook(hip->node, hip->prog->ifNotMatch);
434	if (dest == NULL) {
435		NG_FREE_ITEM(item);
436		return (0);
437	}
438
439	/* Deliver frame out destination hook */
440	dhip = NG_HOOK_PRIVATE(dest);
441	dhip->stats.xmitOctets += totlen;
442	dhip->stats.xmitFrames++;
443	NG_FWD_ITEM_HOOK(error, item, dest);
444	return (error);
445}
446
447/*
448 * Shutdown processing
449 */
450static int
451ng_bpf_shutdown(node_p node)
452{
453	NG_NODE_UNREF(node);
454	return (0);
455}
456
457/*
458 * Hook disconnection
459 */
460static int
461ng_bpf_disconnect(hook_p hook)
462{
463	const hinfo_p hip = NG_HOOK_PRIVATE(hook);
464
465	KASSERT(hip != NULL, ("%s: null info", __FUNCTION__));
466	FREE(hip->prog, M_NETGRAPH_BPF);
467	bzero(hip, sizeof(*hip));
468	FREE(hip, M_NETGRAPH_BPF);
469	NG_HOOK_SET_PRIVATE(hook, NULL);			/* for good measure */
470	if ((NG_NODE_NUMHOOKS(NG_HOOK_NODE(hook)) == 0)
471	&& (NG_NODE_IS_VALID(NG_HOOK_NODE(hook)))) {
472		ng_rmnode_self(NG_HOOK_NODE(hook));
473	}
474	return (0);
475}
476
477/************************************************************************
478			HELPER STUFF
479 ************************************************************************/
480
481/*
482 * Set the BPF program associated with a hook
483 */
484static int
485ng_bpf_setprog(hook_p hook, const struct ng_bpf_hookprog *hp0)
486{
487	const hinfo_p hip = NG_HOOK_PRIVATE(hook);
488	struct ng_bpf_hookprog *hp;
489	int size;
490
491	/* Check program for validity */
492	if (!bpf_validate(hp0->bpf_prog, hp0->bpf_prog_len))
493		return (EINVAL);
494
495	/* Make a copy of the program */
496	size = NG_BPF_HOOKPROG_SIZE(hp0->bpf_prog_len);
497	MALLOC(hp, struct ng_bpf_hookprog *, size, M_NETGRAPH_BPF, M_NOWAIT);
498	if (hp == NULL)
499		return (ENOMEM);
500	bcopy(hp0, hp, size);
501
502	/* Free previous program, if any, and assign new one */
503	if (hip->prog != NULL)
504		FREE(hip->prog, M_NETGRAPH_BPF);
505	hip->prog = hp;
506	return (0);
507}
508
509