npf_alg.c revision 1.10 
1/*	$NetBSD: npf_alg.c,v 1.10 2013/12/06 01:33:37 rmind Exp $	*/
2
3/*-
4 * Copyright (c) 2010-2013 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This material is based upon work partially supported by The
8 * NetBSD Foundation under a contract with Mindaugas Rasiukevicius.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32/*
33 * NPF interface for the Application Level Gateways (ALGs).
34 */
35
36#include <sys/cdefs.h>
37__KERNEL_RCSID(0, "$NetBSD: npf_alg.c,v 1.10 2013/12/06 01:33:37 rmind Exp $");
38
39#include <sys/param.h>
40#include <sys/types.h>
41
42#include <sys/kmem.h>
43#include <sys/pserialize.h>
44#include <sys/mutex.h>
45#include <net/pfil.h>
46#include <sys/module.h>
47
48#include "npf_impl.h"
49
50/*
51 * NAT ALG description structure.  For more compact use of cache,
52 * the functions are separated in their own arrays.  The number of
53 * ALGs is expected to be very small.
54 */
55
56struct npf_alg {
57	const char *	na_name;
58	u_int		na_slot;
59};
60
61/* List of ALGs and the count. */
62static pserialize_t	alg_psz			__cacheline_aligned;
63static npf_alg_t	alg_list[NPF_MAX_ALGS]	__read_mostly;
64static u_int		alg_count		__read_mostly;
65
66/* Session, matching and translation functions. */
67static npf_alg_sfunc_t	alg_sfunc[NPF_MAX_ALGS]	__read_mostly;
68static npf_alg_func_t	alg_mfunc[NPF_MAX_ALGS]	__read_mostly;
69static npf_alg_func_t	alg_tfunc[NPF_MAX_ALGS]	__read_mostly;
70
71static const char	alg_prefix[] = "npf_alg_";
72#define	NPF_EXT_PREFLEN	(sizeof(alg_prefix) - 1)
73
74void
75npf_alg_sysinit(void)
76{
77	alg_psz = pserialize_create();
78	memset(&alg_list, 0, sizeof(alg_list));
79	alg_count = 0;
80
81	memset(&alg_mfunc, 0, sizeof(alg_mfunc));
82	memset(&alg_tfunc, 0, sizeof(alg_tfunc));
83	memset(&alg_sfunc, 0, sizeof(alg_sfunc));
84}
85
86void
87npf_alg_sysfini(void)
88{
89	pserialize_destroy(alg_psz);
90}
91
92static npf_alg_t *
93npf_alg_lookup(const char *name)
94{
95	KASSERT(npf_config_locked_p());
96
97	for (u_int i = 0; i < alg_count; i++) {
98		npf_alg_t *alg = &alg_list[i];
99		const char *aname = alg->na_name;
100
101		if (aname && strcmp(aname, name) == 0)
102			return alg;
103	}
104	return NULL;
105}
106
107npf_alg_t *
108npf_alg_construct(const char *name)
109{
110	npf_alg_t *alg;
111
112	npf_config_enter();
113	if ((alg = npf_alg_lookup(name)) == NULL) {
114		char modname[NPF_EXT_PREFLEN + 64];
115		snprintf(modname, sizeof(modname), "%s%s", alg_prefix, name);
116		npf_config_exit();
117
118		if (module_autoload(modname, MODULE_CLASS_MISC) != 0) {
119			return NULL;
120		}
121		npf_config_enter();
122		alg = npf_alg_lookup(name);
123	}
124	npf_config_exit();
125	return alg;
126}
127
128/*
129 * npf_alg_register: register application-level gateway.
130 */
131npf_alg_t *
132npf_alg_register(const char *name, npf_alg_func_t mfunc, npf_alg_func_t tfunc,
133    npf_alg_sfunc_t sfunc)
134{
135	npf_alg_t *alg;
136	u_int i;
137
138	npf_config_enter();
139	if (npf_alg_lookup(name) != NULL) {
140		npf_config_exit();
141		return NULL;
142	}
143
144	/* Find a spare slot. */
145	for (i = 0; i < NPF_MAX_ALGS; i++) {
146		alg = &alg_list[i];
147		if (alg->na_name == NULL) {
148			break;
149		}
150	}
151	if (i == NPF_MAX_ALGS) {
152		npf_config_exit();
153		return NULL;
154	}
155
156	/* Register the ALG. */
157	alg->na_name = name;
158	alg->na_slot = i;
159
160	/* Assign the functions. */
161	alg_mfunc[i] = mfunc;
162	alg_tfunc[i] = tfunc;
163	alg_sfunc[i] = sfunc;
164
165	alg_count = MAX(alg_count, i + 1);
166	npf_config_exit();
167	return alg;
168}
169
170/*
171 * npf_alg_unregister: unregister application-level gateway.
172 */
173int
174npf_alg_unregister(npf_alg_t *alg)
175{
176	u_int i = alg->na_slot;
177
178	/* Deactivate the functions first. */
179	npf_config_enter();
180	alg_mfunc[i] = NULL;
181	alg_tfunc[i] = NULL;
182	alg_sfunc[i] = NULL;
183	pserialize_perform(alg_psz);
184
185	/* Finally, unregister the ALG. */
186	npf_ruleset_freealg(npf_config_natset(), alg);
187	alg->na_name = NULL;
188	npf_config_exit();
189
190	return 0;
191}
192
193/*
194 * npf_alg_match: call ALG matching inspectors, determine if any ALG matches.
195 */
196bool
197npf_alg_match(npf_cache_t *npc, nbuf_t *nbuf, npf_nat_t *nt, int di)
198{
199	bool match = false;
200	int s;
201
202	s = pserialize_read_enter();
203	for (u_int i = 0; i < alg_count; i++) {
204		npf_alg_func_t func = alg_mfunc[i];
205
206		if (func && func(npc, nbuf, nt, di)) {
207			match = true;
208			break;
209		}
210	}
211	pserialize_read_exit(s);
212	return match;
213}
214
215/*
216 * npf_alg_exec: execute ALG hooks for translation.
217 */
218void
219npf_alg_exec(npf_cache_t *npc, nbuf_t *nbuf, npf_nat_t *nt, bool forw)
220{
221	int s;
222
223	s = pserialize_read_enter();
224	for (u_int i = 0; i < alg_count; i++) {
225		npf_alg_func_t func;
226
227		if ((func = alg_tfunc[i]) != NULL) {
228			func(npc, nbuf, nt, (int)forw);
229		}
230	}
231	pserialize_read_exit(s);
232}
233
234npf_session_t *
235npf_alg_session(npf_cache_t *npc, nbuf_t *nbuf, int di)
236{
237	npf_session_t *se = NULL;
238	int s;
239
240	s = pserialize_read_enter();
241	for (u_int i = 0; i < alg_count; i++) {
242		npf_alg_sfunc_t func = alg_sfunc[i];
243
244		if (func && (se = func(npc, nbuf, di)) != NULL) {
245			break;
246		}
247	}
248	pserialize_read_exit(s);
249	return se;
250}
251