npf_alg.c revision 1.19 
1/*-
2 * Copyright (c) 2010-2013 The NetBSD Foundation, Inc.
3 * All rights reserved.
4 *
5 * This material is based upon work partially supported by The
6 * NetBSD Foundation under a contract with Mindaugas Rasiukevicius.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
18 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
19 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
20 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
21 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
22 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
23 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
24 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
25 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
26 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
27 * POSSIBILITY OF SUCH DAMAGE.
28 */
29
30/*
31 * NPF interface for the Application Level Gateways (ALGs).
32 */
33
34#ifdef _KERNEL
35#include <sys/cdefs.h>
36__KERNEL_RCSID(0, "$NetBSD: npf_alg.c,v 1.19 2019/01/19 21:19:31 rmind Exp $");
37
38#include <sys/param.h>
39#include <sys/types.h>
40
41#include <sys/kmem.h>
42#include <sys/pserialize.h>
43#include <sys/mutex.h>
44#include <net/pfil.h>
45#include <sys/module.h>
46#endif
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
61struct npf_algset {
62	/* List of ALGs and the count. */
63	npf_alg_t	alg_list[NPF_MAX_ALGS];
64	u_int		alg_count;
65
66	/* Matching, inspection and translation functions. */
67	npfa_funcs_t	alg_funcs[NPF_MAX_ALGS];
68};
69
70static const char	alg_prefix[] = "npf_alg_";
71#define	NPF_EXT_PREFLEN	(sizeof(alg_prefix) - 1)
72
73void
74npf_alg_init(npf_t *npf)
75{
76	npf_algset_t *aset;
77
78	aset = kmem_zalloc(sizeof(npf_algset_t), KM_SLEEP);
79	npf->algset = aset;
80}
81
82void
83npf_alg_fini(npf_t *npf)
84{
85	npf_algset_t *aset = npf->algset;
86
87	kmem_free(aset, sizeof(npf_algset_t));
88}
89
90static npf_alg_t *
91npf_alg_lookup(npf_t *npf, const char *name)
92{
93	npf_algset_t *aset = npf->algset;
94
95	KASSERT(npf_config_locked_p(npf));
96
97	for (u_int i = 0; i < aset->alg_count; i++) {
98		npf_alg_t *alg = &aset->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(npf_t *npf, const char *name)
109{
110	npf_alg_t *alg;
111
112	npf_config_enter(npf);
113	if ((alg = npf_alg_lookup(npf, name)) == NULL) {
114		char modname[NPF_EXT_PREFLEN + 64];
115
116		snprintf(modname, sizeof(modname), "%s%s", alg_prefix, name);
117		npf_config_exit(npf);
118
119		if (module_autoload(modname, MODULE_CLASS_MISC) != 0) {
120			return NULL;
121		}
122		npf_config_enter(npf);
123		alg = npf_alg_lookup(npf, name);
124	}
125	npf_config_exit(npf);
126	return alg;
127}
128
129/*
130 * npf_alg_register: register application-level gateway.
131 */
132npf_alg_t *
133npf_alg_register(npf_t *npf, const char *name, const npfa_funcs_t *funcs)
134{
135	npf_algset_t *aset = npf->algset;
136	npfa_funcs_t *afuncs;
137	npf_alg_t *alg;
138	u_int i;
139
140	npf_config_enter(npf);
141	if (npf_alg_lookup(npf, name) != NULL) {
142		npf_config_exit(npf);
143		return NULL;
144	}
145
146	/* Find a spare slot. */
147	for (i = 0; i < NPF_MAX_ALGS; i++) {
148		alg = &aset->alg_list[i];
149		if (alg->na_name == NULL) {
150			break;
151		}
152	}
153	if (i == NPF_MAX_ALGS) {
154		npf_config_exit(npf);
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	afuncs = &aset->alg_funcs[i];
164	afuncs->match = funcs->match;
165	afuncs->translate = funcs->translate;
166	afuncs->inspect = funcs->inspect;
167
168	aset->alg_count = MAX(aset->alg_count, i + 1);
169	npf_config_exit(npf);
170
171	return alg;
172}
173
174/*
175 * npf_alg_unregister: unregister application-level gateway.
176 */
177int
178npf_alg_unregister(npf_t *npf, npf_alg_t *alg)
179{
180	npf_algset_t *aset = npf->algset;
181	u_int i = alg->na_slot;
182	npfa_funcs_t *afuncs;
183
184	/* Deactivate the functions first. */
185	npf_config_enter(npf);
186	afuncs = &aset->alg_funcs[i];
187	afuncs->match = NULL;
188	afuncs->translate = NULL;
189	afuncs->inspect = NULL;
190	pserialize_perform(npf->qsbr);
191
192	/* Finally, unregister the ALG. */
193	npf_ruleset_freealg(npf_config_natset(npf), alg);
194	alg->na_name = NULL;
195	npf_config_exit(npf);
196
197	return 0;
198}
199
200/*
201 * npf_alg_match: call ALG matching inspectors, determine if any ALG matches.
202 */
203bool
204npf_alg_match(npf_cache_t *npc, npf_nat_t *nt, int di)
205{
206	npf_algset_t *aset = npc->npc_ctx->algset;
207	bool match = false;
208	int s;
209
210	s = pserialize_read_enter();
211	for (u_int i = 0; i < aset->alg_count; i++) {
212		const npfa_funcs_t *f = &aset->alg_funcs[i];
213
214		if (f->match && f->match(npc, nt, di)) {
215			match = true;
216			break;
217		}
218	}
219	pserialize_read_exit(s);
220	return match;
221}
222
223/*
224 * npf_alg_exec: execute ALG hooks for translation.
225 */
226void
227npf_alg_exec(npf_cache_t *npc, npf_nat_t *nt, bool forw)
228{
229	npf_algset_t *aset = npc->npc_ctx->algset;
230	int s;
231
232	s = pserialize_read_enter();
233	for (u_int i = 0; i < aset->alg_count; i++) {
234		const npfa_funcs_t *f = &aset->alg_funcs[i];
235
236		if (f->translate) {
237			f->translate(npc, nt, forw);
238		}
239	}
240	pserialize_read_exit(s);
241}
242
243npf_conn_t *
244npf_alg_conn(npf_cache_t *npc, int di)
245{
246	npf_algset_t *aset = npc->npc_ctx->algset;
247	npf_conn_t *con = NULL;
248	int s;
249
250	s = pserialize_read_enter();
251	for (u_int i = 0; i < aset->alg_count; i++) {
252		const npfa_funcs_t *f = &aset->alg_funcs[i];
253
254		if (!f->inspect)
255			continue;
256		if ((con = f->inspect(npc, di)) != NULL)
257			break;
258	}
259	pserialize_read_exit(s);
260	return con;
261}
262
263int
264npf_alg_export(npf_t *npf, nvlist_t *npf_dict)
265{
266	npf_algset_t *aset = npf->algset;
267
268	KASSERT(npf_config_locked_p(npf));
269
270	for (u_int i = 0; i < aset->alg_count; i++) {
271		const npf_alg_t *alg = &aset->alg_list[i];
272		nvlist_t *algdict;
273
274		if (alg->na_name == NULL) {
275			continue;
276		}
277		algdict = nvlist_create(0);
278		nvlist_add_string(algdict, "name", alg->na_name);
279		nvlist_append_nvlist_array(npf_dict, "algs", algdict);
280		nvlist_destroy(algdict);
281	}
282	return 0;
283}
284