npf_alg.c revision 1.9 
1/*	$NetBSD: npf_alg.c,v 1.9 2013/06/02 02:20:04 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 1.9 2013/06/02 02:20:04 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#define	NPF_MAX_ALGS	8
62
63/* List of ALGs and the count. */
64static pserialize_t	alg_psz			__cacheline_aligned;
65static npf_alg_t	alg_list[NPF_MAX_ALGS]	__read_mostly;
66static u_int		alg_count		__read_mostly;
67
68/* Session, matching and translation functions. */
69static npf_alg_sfunc_t	alg_sfunc[NPF_MAX_ALGS]	__read_mostly;
70static npf_alg_func_t	alg_mfunc[NPF_MAX_ALGS]	__read_mostly;
71static npf_alg_func_t	alg_tfunc[NPF_MAX_ALGS]	__read_mostly;
72
73static const char	alg_prefix[] = "npf_alg_";
74#define	NPF_EXT_PREFLEN	(sizeof(alg_prefix) - 1)
75
76void
77npf_alg_sysinit(void)
78{
79	alg_psz = pserialize_create();
80	memset(&alg_list, 0, sizeof(alg_list));
81	alg_count = 0;
82
83	memset(&alg_mfunc, 0, sizeof(alg_mfunc));
84	memset(&alg_tfunc, 0, sizeof(alg_tfunc));
85	memset(&alg_sfunc, 0, sizeof(alg_sfunc));
86}
87
88void
89npf_alg_sysfini(void)
90{
91	pserialize_destroy(alg_psz);
92}
93
94static npf_alg_t *
95npf_alg_lookup(const char *name)
96{
97	KASSERT(npf_config_locked_p());
98
99	for (u_int i = 0; i < alg_count; i++) {
100		npf_alg_t *alg = &alg_list[i];
101		const char *aname = alg->na_name;
102
103		if (aname && strcmp(aname, name) == 0)
104			return alg;
105	}
106	return NULL;
107}
108
109npf_alg_t *
110npf_alg_construct(const char *name)
111{
112	npf_alg_t *alg;
113
114	npf_config_enter();
115	if ((alg = npf_alg_lookup(name)) == NULL) {
116		char modname[NPF_EXT_PREFLEN + 64];
117		snprintf(modname, sizeof(modname), "%s%s", alg_prefix, name);
118		npf_config_exit();
119
120		if (module_autoload(modname, MODULE_CLASS_MISC) != 0) {
121			return NULL;
122		}
123		npf_config_enter();
124		alg = npf_alg_lookup(name);
125	}
126	npf_config_exit();
127	return alg;
128}
129
130/*
131 * npf_alg_register: register application-level gateway.
132 */
133npf_alg_t *
134npf_alg_register(const char *name, npf_alg_func_t mfunc, npf_alg_func_t tfunc,
135    npf_alg_sfunc_t sfunc)
136{
137	npf_alg_t *alg;
138	u_int i;
139
140	npf_config_enter();
141	if (npf_alg_lookup(name) != NULL) {
142		npf_config_exit();
143		return NULL;
144	}
145
146	/* Find a spare slot. */
147	for (i = 0; i < NPF_MAX_ALGS; i++) {
148		alg = &alg_list[i];
149		if (alg->na_name == NULL) {
150			break;
151		}
152	}
153	if (i == NPF_MAX_ALGS) {
154		npf_config_exit();
155		return NULL;
156	}
157
158	/* Register the ALG. */
159	alg->na_name = name;
160	alg->na_slot = i;
161
162	/* Assign the functions. */
163	alg_mfunc[i] = mfunc;
164	alg_tfunc[i] = tfunc;
165	alg_sfunc[i] = sfunc;
166
167	alg_count = MAX(alg_count, i + 1);
168	npf_config_exit();
169	return alg;
170}
171
172/*
173 * npf_alg_unregister: unregister application-level gateway.
174 */
175int
176npf_alg_unregister(npf_alg_t *alg)
177{
178	u_int i = alg->na_slot;
179
180	/* Deactivate the functions first. */
181	npf_config_enter();
182	alg_mfunc[i] = NULL;
183	alg_tfunc[i] = NULL;
184	alg_sfunc[i] = NULL;
185	pserialize_perform(alg_psz);
186
187	/* Finally, unregister the ALG. */
188	npf_ruleset_freealg(npf_config_natset(), alg);
189	alg->na_name = NULL;
190	npf_config_exit();
191
192	return 0;
193}
194
195/*
196 * npf_alg_match: call ALG matching inspectors, determine if any ALG matches.
197 */
198bool
199npf_alg_match(npf_cache_t *npc, nbuf_t *nbuf, npf_nat_t *nt, int di)
200{
201	bool match = false;
202	int s;
203
204	s = pserialize_read_enter();
205	for (u_int i = 0; i < alg_count; i++) {
206		npf_alg_func_t func = alg_mfunc[i];
207
208		if (func && func(npc, nbuf, nt, di)) {
209			match = true;
210			break;
211		}
212	}
213	pserialize_read_exit(s);
214	return match;
215}
216
217/*
218 * npf_alg_exec: execute ALG hooks for translation.
219 */
220void
221npf_alg_exec(npf_cache_t *npc, nbuf_t *nbuf, npf_nat_t *nt, int di)
222{
223	int s;
224
225	s = pserialize_read_enter();
226	for (u_int i = 0; i < alg_count; i++) {
227		npf_alg_func_t func;
228
229		if ((func = alg_tfunc[i]) != NULL) {
230			func(npc, nbuf, nt, di);
231		}
232	}
233	pserialize_read_exit(s);
234}
235
236npf_session_t *
237npf_alg_session(npf_cache_t *npc, nbuf_t *nbuf, int di)
238{
239	npf_session_t *se = NULL;
240	int s;
241
242	s = pserialize_read_enter();
243	for (u_int i = 0; i < alg_count; i++) {
244		npf_alg_sfunc_t func = alg_sfunc[i];
245
246		if (func && (se = func(npc, nbuf, di)) != NULL) {
247			break;
248		}
249	}
250	pserialize_read_exit(s);
251	return se;
252}
253