ng_bpf.c revision 54214 
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@whistle.com>
38 *
39 * $FreeBSD: head/sys/netgraph/ng_bpf.c 54214 1999-12-06 18:43:32Z archie $
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#define OFFSETOF(s, e) ((char *)&((s *)0)->e - (char *)((s *)0))
71
72#define ERROUT(x)	do { error = (x); goto done; } while (0)
73
74/* Per hook private info */
75struct ng_bpf_hookinfo {
76	node_p			node;
77	hook_p			hook;
78	struct ng_bpf_hookprog	*prog;
79	struct ng_bpf_hookstat	stats;
80};
81typedef struct ng_bpf_hookinfo *hinfo_p;
82
83/* Netgraph methods */
84static ng_constructor_t	ng_bpf_constructor;
85static ng_rcvmsg_t	ng_bpf_rcvmsg;
86static ng_shutdown_t	ng_bpf_rmnode;
87static ng_newhook_t	ng_bpf_newhook;
88static ng_rcvdata_t	ng_bpf_rcvdata;
89static ng_disconnect_t	ng_bpf_disconnect;
90
91/* Internal helper functions */
92static int	ng_bpf_setprog(hook_p hook, const struct ng_bpf_hookprog *hp);
93
94/* Parse type for one struct bfp_insn */
95static const struct ng_parse_struct_info ng_bpf_insn_type_info = {
96    {
97	{ "code",	&ng_parse_int16_type	},
98	{ "jt",		&ng_parse_int8_type	},
99	{ "jf",		&ng_parse_int8_type	},
100	{ "k",		&ng_parse_int32_type	},
101	{ NULL }
102    }
103};
104static const struct ng_parse_type ng_bpf_insn_type = {
105	&ng_parse_struct_type,
106	&ng_bpf_insn_type_info
107};
108
109/* Parse type for the field 'bpf_prog' in struct ng_bpf_hookprog */
110static int
111ng_bpf_hookprogary_getLength(const struct ng_parse_type *type,
112	const u_char *start, const u_char *buf)
113{
114	const struct ng_bpf_hookprog *hp;
115
116	hp = (const struct ng_bpf_hookprog *)
117	    (buf - OFFSETOF(struct ng_bpf_hookprog, bpf_prog));
118	return hp->bpf_prog_len;
119}
120
121static const struct ng_parse_array_info ng_bpf_hookprogary_info = {
122	&ng_bpf_insn_type,
123	&ng_bpf_hookprogary_getLength,
124	NULL
125};
126static const struct ng_parse_type ng_bpf_hookprogary_type = {
127	&ng_parse_array_type,
128	&ng_bpf_hookprogary_info
129};
130
131/* Parse type for struct ng_bpf_hookprog */
132static const struct ng_parse_struct_info ng_bpf_hookprog_type_info
133	= NG_BPF_HOOKPROG_TYPE_INFO(&ng_bpf_hookprogary_type);
134static const struct ng_parse_type ng_bpf_hookprog_type = {
135	&ng_parse_struct_type,
136	&ng_bpf_hookprog_type_info
137};
138
139/* Parse type for struct ng_bpf_hookstat */
140static const struct ng_parse_struct_info
141	ng_bpf_hookstat_type_info = NG_BPF_HOOKSTAT_TYPE_INFO;
142static const struct ng_parse_type ng_bpf_hookstat_type = {
143	&ng_parse_struct_type,
144	&ng_bpf_hookstat_type_info
145};
146
147/* List of commands and how to convert arguments to/from ASCII */
148static const struct ng_cmdlist ng_bpf_cmdlist[] = {
149	{
150	  NGM_BPF_COOKIE,
151	  NGM_BPF_SET_PROGRAM,
152	  "setprogram",
153	  &ng_bpf_hookprog_type,
154	  NULL
155	},
156	{
157	  NGM_BPF_COOKIE,
158	  NGM_BPF_GET_PROGRAM,
159	  "getprogram",
160	  &ng_parse_hookbuf_type,
161	  &ng_bpf_hookprog_type
162	},
163	{
164	  NGM_BPF_COOKIE,
165	  NGM_BPF_GET_STATS,
166	  "getstats",
167	  &ng_parse_hookbuf_type,
168	  &ng_bpf_hookstat_type
169	},
170	{
171	  NGM_BPF_COOKIE,
172	  NGM_BPF_CLR_STATS,
173	  "clrstats",
174	  &ng_parse_hookbuf_type,
175	  NULL
176	},
177	{
178	  NGM_BPF_COOKIE,
179	  NGM_BPF_GETCLR_STATS,
180	  "getclrstats",
181	  &ng_parse_hookbuf_type,
182	  &ng_bpf_hookstat_type
183	},
184	{ 0 }
185};
186
187/* Netgraph type descriptor */
188static struct ng_type typestruct = {
189	NG_VERSION,
190	NG_BPF_NODE_TYPE,
191	NULL,
192	ng_bpf_constructor,
193	ng_bpf_rcvmsg,
194	ng_bpf_rmnode,
195	ng_bpf_newhook,
196	NULL,
197	NULL,
198	ng_bpf_rcvdata,
199	ng_bpf_rcvdata,
200	ng_bpf_disconnect,
201	ng_bpf_cmdlist
202};
203NETGRAPH_INIT(bpf, &typestruct);
204
205/* Default BPF program for a hook that matches nothing */
206static const struct ng_bpf_hookprog ng_bpf_default_prog = {
207	{ '\0' },		/* to be filled in at hook creation time */
208	{ '\0' },
209	{ '\0' },
210	1,
211	{ BPF_STMT(BPF_RET+BPF_K, 0) }
212};
213
214/*
215 * Node constructor
216 *
217 * We don't keep any per-node private data
218 */
219static int
220ng_bpf_constructor(node_p *nodep)
221{
222	int error = 0;
223
224	if ((error = ng_make_node_common(&typestruct, nodep)))
225		return (error);
226	(*nodep)->private = NULL;
227	return (0);
228}
229
230/*
231 * Add a hook
232 */
233static int
234ng_bpf_newhook(node_p node, hook_p hook, const char *name)
235{
236	hinfo_p hip;
237	int error;
238
239	/* Create hook private structure */
240	MALLOC(hip, hinfo_p, sizeof(*hip), M_NETGRAPH, M_WAITOK);
241	if (hip == NULL)
242		return (ENOMEM);
243	bzero(hip, sizeof(*hip));
244	hip->hook = hook;
245	hook->private = hip;
246	hip->node = node;
247
248	/* Attach the default BPF program */
249	if ((error = ng_bpf_setprog(hook, &ng_bpf_default_prog)) != 0) {
250		FREE(hip, M_NETGRAPH);
251		hook->private = NULL;
252		return (error);
253	}
254
255	/* Set hook name */
256	strncpy(hip->prog->thisHook, name, sizeof(hip->prog->thisHook) - 1);
257	hip->prog->thisHook[sizeof(hip->prog->thisHook) - 1] = '\0';
258	return (0);
259}
260
261/*
262 * Receive a control message
263 */
264static int
265ng_bpf_rcvmsg(node_p node, struct ng_mesg *msg, const char *retaddr,
266	   struct ng_mesg **rptr)
267{
268	struct ng_mesg *resp = NULL;
269	int error = 0;
270
271	switch (msg->header.typecookie) {
272	case NGM_BPF_COOKIE:
273		switch (msg->header.cmd) {
274		case NGM_BPF_SET_PROGRAM:
275		    {
276			struct ng_bpf_hookprog *const
277			    hp = (struct ng_bpf_hookprog *)msg->data;
278			hook_p hook;
279
280			/* Sanity check */
281			if (msg->header.arglen < sizeof(*hp)
282			    || msg->header.arglen
283			      != NG_BPF_HOOKPROG_SIZE(hp->bpf_prog_len))
284				ERROUT(EINVAL);
285
286			/* Find hook */
287			if ((hook = ng_findhook(node, hp->thisHook)) == NULL)
288				ERROUT(ENOENT);
289
290			/* Set new program */
291			if ((error = ng_bpf_setprog(hook, hp)) != 0)
292				ERROUT(error);
293			break;
294		    }
295
296		case NGM_BPF_GET_PROGRAM:
297		    {
298			struct ng_bpf_hookprog *hp;
299			hook_p hook;
300
301			/* Sanity check */
302			if (msg->header.arglen == 0)
303				ERROUT(EINVAL);
304			msg->data[msg->header.arglen - 1] = '\0';
305
306			/* Find hook */
307			if ((hook = ng_findhook(node, msg->data)) == NULL)
308				ERROUT(ENOENT);
309
310			/* Build response */
311			hp = ((hinfo_p)hook->private)->prog;
312			NG_MKRESPONSE(resp, msg,
313			    NG_BPF_HOOKPROG_SIZE(hp->bpf_prog_len), M_NOWAIT);
314			if (resp == NULL)
315				ERROUT(ENOMEM);
316			bcopy(hp, resp->data,
317			   NG_BPF_HOOKPROG_SIZE(hp->bpf_prog_len));
318			break;
319		    }
320
321		case NGM_BPF_GET_STATS:
322		case NGM_BPF_CLR_STATS:
323		case NGM_BPF_GETCLR_STATS:
324		    {
325			struct ng_bpf_hookstat *stats;
326			hook_p hook;
327
328			/* Sanity check */
329			if (msg->header.arglen == 0)
330				ERROUT(EINVAL);
331			msg->data[msg->header.arglen - 1] = '\0';
332
333			/* Find hook */
334			if ((hook = ng_findhook(node, msg->data)) == NULL)
335				ERROUT(ENOENT);
336			stats = &((hinfo_p)hook->private)->stats;
337
338			/* Build response (if desired) */
339			if (msg->header.cmd != NGM_BPF_CLR_STATS) {
340				NG_MKRESPONSE(resp,
341				    msg, sizeof(*stats), M_NOWAIT);
342				if (resp == NULL)
343					ERROUT(ENOMEM);
344				bcopy(stats, resp->data, sizeof(*stats));
345			}
346
347			/* Clear stats (if desired) */
348			if (msg->header.cmd != NGM_BPF_GET_STATS)
349				bzero(stats, sizeof(*stats));
350			break;
351		    }
352
353		default:
354			error = EINVAL;
355			break;
356		}
357		break;
358	default:
359		error = EINVAL;
360		break;
361	}
362	if (rptr)
363		*rptr = resp;
364	else if (resp)
365		FREE(resp, M_NETGRAPH);
366
367done:
368	FREE(msg, M_NETGRAPH);
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, struct mbuf *m, meta_p meta)
379{
380	const hinfo_p hip = hook->private;
381	int totlen = m->m_pkthdr.len;
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
388	/* Update stats on incoming hook */
389	hip->stats.recvFrames++;
390	hip->stats.recvOctets += totlen;
391
392	/* Need to put packet in contiguous memory for bpf */
393	if (m->m_next != NULL) {
394		if (totlen > sizeof(buf)) {
395			MALLOC(data, u_char *, totlen, M_NETGRAPH, M_NOWAIT);
396			if (data == NULL) {
397				NG_FREE_DATA(m, meta);
398				return (ENOMEM);
399			}
400			needfree = 1;
401		} else
402			data = buf;
403		m_copydata(m, 0, totlen, (caddr_t)data);
404	} else
405		data = mtod(m, u_char *);
406
407	/* Run packet through filter */
408	len = bpf_filter(hip->prog->bpf_prog, data, totlen, totlen);
409	if (needfree)
410		FREE(data, M_NETGRAPH);
411
412	/* See if we got a match and find destination hook */
413	if (len > 0) {
414
415		/* Update stats */
416		hip->stats.recvMatchFrames++;
417		hip->stats.recvMatchOctets += totlen;
418
419		/* Truncate packet length if required by the filter */
420		if (len < totlen) {
421			m_adj(m, -(totlen - len));
422			totlen -= len;
423		}
424		dest = ng_findhook(hip->node, hip->prog->ifMatch);
425	} else
426		dest = ng_findhook(hip->node, hip->prog->ifNotMatch);
427	if (dest == NULL) {
428		NG_FREE_DATA(m, meta);
429		return (0);
430	}
431
432	/* Deliver frame out destination hook */
433	dhip = (hinfo_p)dest->private;
434	dhip->stats.xmitOctets += totlen;
435	dhip->stats.xmitFrames++;
436	NG_SEND_DATA(error, dest, m, meta);
437	return (error);
438}
439
440/*
441 * Shutdown processing
442 */
443static int
444ng_bpf_rmnode(node_p node)
445{
446	node->flags |= NG_INVALID;
447	ng_cutlinks(node);
448	ng_unname(node);
449	ng_unref(node);
450	return (0);
451}
452
453/*
454 * Hook disconnection
455 */
456static int
457ng_bpf_disconnect(hook_p hook)
458{
459	const hinfo_p hip = hook->private;
460
461	KASSERT(hip != NULL, ("%s: null info", __FUNCTION__));
462	FREE(hip->prog, M_NETGRAPH);
463	bzero(hip, sizeof(*hip));
464	FREE(hip, M_NETGRAPH);
465	hook->private = NULL;			/* for good measure */
466	if (hook->node->numhooks == 0)
467		ng_rmnode(hook->node);
468	return (0);
469}
470
471/************************************************************************
472			HELPER STUFF
473 ************************************************************************/
474
475/*
476 * Set the BPF program associated with a hook
477 */
478static int
479ng_bpf_setprog(hook_p hook, const struct ng_bpf_hookprog *hp0)
480{
481	const hinfo_p hip = hook->private;
482	struct ng_bpf_hookprog *hp;
483	int size;
484
485	/* Check program for validity */
486	if (!bpf_validate(hp0->bpf_prog, hp0->bpf_prog_len))
487		return (EINVAL);
488
489	/* Make a copy of the program */
490	size = NG_BPF_HOOKPROG_SIZE(hp0->bpf_prog_len);
491	MALLOC(hp, struct ng_bpf_hookprog *, size, M_NETGRAPH, M_WAITOK);
492	if (hp == NULL)
493		return (ENOMEM);
494	bcopy(hp0, hp, size);
495
496	/* Free previous program, if any, and assign new one */
497	if (hip->prog != NULL)
498		FREE(hip->prog, M_NETGRAPH);
499	hip->prog = hp;
500	return (0);
501}
502
503