npf_alg.c revision 1.11 
1/*	$NetBSD: npf_alg.c,v 1.11 2014/02/16 22:10:40 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 1.11 2014/02/16 22:10:40 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/* Matching, inspection and translation functions. */
67static npfa_funcs_t	alg_funcs[NPF_MAX_ALGS]	__read_mostly;
68
69static const char	alg_prefix[] = "npf_alg_";
70#define	NPF_EXT_PREFLEN	(sizeof(alg_prefix) - 1)
71
72void
73npf_alg_sysinit(void)
74{
75	alg_psz = pserialize_create();
76	memset(alg_list, 0, sizeof(alg_list));
77	memset(alg_funcs, 0, sizeof(alg_funcs));
78	alg_count = 0;
79}
80
81void
82npf_alg_sysfini(void)
83{
84	pserialize_destroy(alg_psz);
85}
86
87static npf_alg_t *
88npf_alg_lookup(const char *name)
89{
90	KASSERT(npf_config_locked_p());
91
92	for (u_int i = 0; i < alg_count; i++) {
93		npf_alg_t *alg = &alg_list[i];
94		const char *aname = alg->na_name;
95
96		if (aname && strcmp(aname, name) == 0)
97			return alg;
98	}
99	return NULL;
100}
101
102npf_alg_t *
103npf_alg_construct(const char *name)
104{
105	npf_alg_t *alg;
106
107	npf_config_enter();
108	if ((alg = npf_alg_lookup(name)) == NULL) {
109		char modname[NPF_EXT_PREFLEN + 64];
110		snprintf(modname, sizeof(modname), "%s%s", alg_prefix, name);
111		npf_config_exit();
112
113		if (module_autoload(modname, MODULE_CLASS_MISC) != 0) {
114			return NULL;
115		}
116		npf_config_enter();
117		alg = npf_alg_lookup(name);
118	}
119	npf_config_exit();
120	return alg;
121}
122
123/*
124 * npf_alg_register: register application-level gateway.
125 */
126npf_alg_t *
127npf_alg_register(const char *name, const npfa_funcs_t *funcs)
128{
129	npf_alg_t *alg;
130	u_int i;
131
132	npf_config_enter();
133	if (npf_alg_lookup(name) != NULL) {
134		npf_config_exit();
135		return NULL;
136	}
137
138	/* Find a spare slot. */
139	for (i = 0; i < NPF_MAX_ALGS; i++) {
140		alg = &alg_list[i];
141		if (alg->na_name == NULL) {
142			break;
143		}
144	}
145	if (i == NPF_MAX_ALGS) {
146		npf_config_exit();
147		return NULL;
148	}
149
150	/* Register the ALG. */
151	alg->na_name = name;
152	alg->na_slot = i;
153
154	/* Assign the functions. */
155	alg_funcs[i].match = funcs->match;
156	alg_funcs[i].translate = funcs->translate;
157	alg_funcs[i].inspect = funcs->inspect;
158
159	alg_count = MAX(alg_count, i + 1);
160	npf_config_exit();
161
162	return alg;
163}
164
165/*
166 * npf_alg_unregister: unregister application-level gateway.
167 */
168int
169npf_alg_unregister(npf_alg_t *alg)
170{
171	u_int i = alg->na_slot;
172
173	/* Deactivate the functions first. */
174	npf_config_enter();
175	alg_funcs[i].match = NULL;
176	alg_funcs[i].translate = NULL;
177	alg_funcs[i].inspect = NULL;
178	pserialize_perform(alg_psz);
179
180	/* Finally, unregister the ALG. */
181	npf_ruleset_freealg(npf_config_natset(), alg);
182	alg->na_name = NULL;
183	npf_config_exit();
184
185	return 0;
186}
187
188/*
189 * npf_alg_match: call ALG matching inspectors, determine if any ALG matches.
190 */
191bool
192npf_alg_match(npf_cache_t *npc, nbuf_t *nbuf, npf_nat_t *nt, int di)
193{
194	bool match = false;
195	int s;
196
197	s = pserialize_read_enter();
198	for (u_int i = 0; i < alg_count; i++) {
199		const npfa_funcs_t *f = &alg_funcs[i];
200
201		if (f->match && f->match(npc, nbuf, nt, di)) {
202			match = true;
203			break;
204		}
205	}
206	pserialize_read_exit(s);
207	return match;
208}
209
210/*
211 * npf_alg_exec: execute ALG hooks for translation.
212 */
213void
214npf_alg_exec(npf_cache_t *npc, nbuf_t *nbuf, npf_nat_t *nt, bool forw)
215{
216	int s;
217
218	s = pserialize_read_enter();
219	for (u_int i = 0; i < alg_count; i++) {
220		const npfa_funcs_t *f = &alg_funcs[i];
221
222		if (f->translate) {
223			f->translate(npc, nbuf, nt, forw);
224		}
225	}
226	pserialize_read_exit(s);
227}
228
229npf_session_t *
230npf_alg_session(npf_cache_t *npc, nbuf_t *nbuf, int di)
231{
232	npf_session_t *se = NULL;
233	int s;
234
235	s = pserialize_read_enter();
236	for (u_int i = 0; i < alg_count; i++) {
237		const npfa_funcs_t *f = &alg_funcs[i];
238
239		if (f->inspect)
240			continue;
241		if ((se = f->inspect(npc, nbuf, di)) != NULL)
242			break;
243	}
244	pserialize_read_exit(s);
245	return se;
246}
247