npf_alg.c revision 1.18 
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 1.18 2018/09/29 14:41:36 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/psref.h>
44#include <sys/mutex.h>
45#include <net/pfil.h>
46#include <sys/module.h>
47#endif
48
49#include "npf_impl.h"
50
51/*
52 * NAT ALG description structure.  For more compact use of cache,
53 * the functions are separated in their own arrays.  The number of
54 * ALGs is expected to be very small.
55 */
56
57struct npf_alg {
58	const char *	na_name;
59	u_int		na_slot;
60};
61
62struct npf_algset {
63	/* List of ALGs and the count. */
64	npf_alg_t	alg_list[NPF_MAX_ALGS];
65	u_int		alg_count;
66
67	/* Matching, inspection and translation functions. */
68	npfa_funcs_t	alg_funcs[NPF_MAX_ALGS];
69
70	/* Passive reference until we npf conn lookup is pserialize-safe. */
71	struct psref_target	alg_psref[NPF_MAX_ALGS];
72};
73
74static const char	alg_prefix[] = "npf_alg_";
75#define	NPF_EXT_PREFLEN	(sizeof(alg_prefix) - 1)
76
77__read_mostly static struct psref_class *	npf_alg_psref_class = NULL;
78
79void
80npf_alg_sysinit(void)
81{
82
83	npf_alg_psref_class = psref_class_create("npf_alg", IPL_SOFTNET);
84}
85
86void
87npf_alg_sysfini(void)
88{
89
90	psref_class_destroy(npf_alg_psref_class);
91	npf_alg_psref_class = NULL;
92}
93
94void
95npf_alg_init(npf_t *npf)
96{
97	npf_algset_t *aset;
98
99	aset = kmem_zalloc(sizeof(npf_algset_t), KM_SLEEP);
100	npf->algset = aset;
101}
102
103void
104npf_alg_fini(npf_t *npf)
105{
106	npf_algset_t *aset = npf->algset;
107
108	kmem_free(aset, sizeof(npf_algset_t));
109}
110
111static npf_alg_t *
112npf_alg_lookup(npf_t *npf, const char *name)
113{
114	npf_algset_t *aset = npf->algset;
115
116	KASSERT(npf_config_locked_p(npf));
117
118	for (u_int i = 0; i < aset->alg_count; i++) {
119		npf_alg_t *alg = &aset->alg_list[i];
120		const char *aname = alg->na_name;
121
122		if (aname && strcmp(aname, name) == 0)
123			return alg;
124	}
125	return NULL;
126}
127
128npf_alg_t *
129npf_alg_construct(npf_t *npf, const char *name)
130{
131	npf_alg_t *alg;
132
133	npf_config_enter(npf);
134	if ((alg = npf_alg_lookup(npf, name)) == NULL) {
135		char modname[NPF_EXT_PREFLEN + 64];
136
137		snprintf(modname, sizeof(modname), "%s%s", alg_prefix, name);
138		npf_config_exit(npf);
139
140		if (module_autoload(modname, MODULE_CLASS_MISC) != 0) {
141			return NULL;
142		}
143		npf_config_enter(npf);
144		alg = npf_alg_lookup(npf, name);
145	}
146	npf_config_exit(npf);
147	return alg;
148}
149
150/*
151 * npf_alg_register: register application-level gateway.
152 */
153npf_alg_t *
154npf_alg_register(npf_t *npf, const char *name, const npfa_funcs_t *funcs)
155{
156	npf_algset_t *aset = npf->algset;
157	npfa_funcs_t *afuncs;
158	npf_alg_t *alg;
159	u_int i;
160
161	npf_config_enter(npf);
162	if (npf_alg_lookup(npf, name) != NULL) {
163		npf_config_exit(npf);
164		return NULL;
165	}
166
167	/* Find a spare slot. */
168	for (i = 0; i < NPF_MAX_ALGS; i++) {
169		alg = &aset->alg_list[i];
170		if (alg->na_name == NULL) {
171			break;
172		}
173	}
174	if (i == NPF_MAX_ALGS) {
175		npf_config_exit(npf);
176		return NULL;
177	}
178
179	/* Register the ALG. */
180	alg->na_name = name;
181	alg->na_slot = i;
182
183	/* Prepare a psref target. */
184	psref_target_init(&aset->alg_psref[i], npf_alg_psref_class);
185	membar_producer();
186
187	/* Assign the functions. */
188	afuncs = &aset->alg_funcs[i];
189	afuncs->match = funcs->match;
190	afuncs->translate = funcs->translate;
191	afuncs->inspect = funcs->inspect;
192
193	aset->alg_count = MAX(aset->alg_count, i + 1);
194	npf_config_exit(npf);
195
196	return alg;
197}
198
199/*
200 * npf_alg_unregister: unregister application-level gateway.
201 */
202int
203npf_alg_unregister(npf_t *npf, npf_alg_t *alg)
204{
205	npf_algset_t *aset = npf->algset;
206	u_int i = alg->na_slot;
207	npfa_funcs_t *afuncs;
208
209	/* Deactivate the functions first. */
210	npf_config_enter(npf);
211	afuncs = &aset->alg_funcs[i];
212	afuncs->match = NULL;
213	afuncs->translate = NULL;
214	afuncs->inspect = NULL;
215	pserialize_perform(npf->qsbr);
216	psref_target_destroy(&aset->alg_psref[i], npf_alg_psref_class);
217
218	/* Finally, unregister the ALG. */
219	npf_ruleset_freealg(npf_config_natset(npf), alg);
220	alg->na_name = NULL;
221	npf_config_exit(npf);
222
223	return 0;
224}
225
226/*
227 * npf_alg_match: call ALG matching inspectors, determine if any ALG matches.
228 */
229bool
230npf_alg_match(npf_cache_t *npc, npf_nat_t *nt, int di)
231{
232	npf_algset_t *aset = npc->npc_ctx->algset;
233	bool match = false;
234	int s;
235
236	s = pserialize_read_enter();
237	for (u_int i = 0; i < aset->alg_count; i++) {
238		const npfa_funcs_t *f = &aset->alg_funcs[i];
239
240		if (f->match && f->match(npc, nt, di)) {
241			match = true;
242			break;
243		}
244	}
245	pserialize_read_exit(s);
246	return match;
247}
248
249/*
250 * npf_alg_exec: execute ALG hooks for translation.
251 */
252void
253npf_alg_exec(npf_cache_t *npc, npf_nat_t *nt, bool forw)
254{
255	npf_algset_t *aset = npc->npc_ctx->algset;
256	int s;
257
258	s = pserialize_read_enter();
259	for (u_int i = 0; i < aset->alg_count; i++) {
260		const npfa_funcs_t *f = &aset->alg_funcs[i];
261
262		if (f->translate) {
263			f->translate(npc, nt, forw);
264		}
265	}
266	pserialize_read_exit(s);
267}
268
269npf_conn_t *
270npf_alg_conn(npf_cache_t *npc, int di)
271{
272	npf_algset_t *aset = npc->npc_ctx->algset;
273	npf_conn_t *con = NULL;
274	struct psref psref;
275	int s;
276
277	s = pserialize_read_enter();
278	for (u_int i = 0; i < aset->alg_count; i++) {
279		const npfa_funcs_t *f = &aset->alg_funcs[i];
280		struct psref_target *psref_target = &aset->alg_psref[i];
281
282		if (!f->inspect)
283			continue;
284		membar_consumer();
285		psref_acquire(&psref, psref_target, npf_alg_psref_class);
286		pserialize_read_exit(s);
287		con = f->inspect(npc, di);
288		s = pserialize_read_enter();
289		psref_release(&psref, psref_target, npf_alg_psref_class);
290		if (con != NULL)
291			break;
292	}
293	pserialize_read_exit(s);
294	return con;
295}
296
297int
298npf_alg_export(npf_t *npf, nvlist_t *npf_dict)
299{
300	npf_algset_t *aset = npf->algset;
301
302	KASSERT(npf_config_locked_p(npf));
303
304	for (u_int i = 0; i < aset->alg_count; i++) {
305		const npf_alg_t *alg = &aset->alg_list[i];
306		nvlist_t *algdict;
307
308		if (alg->na_name == NULL) {
309			continue;
310		}
311		algdict = nvlist_create(0);
312		nvlist_add_string(algdict, "name", alg->na_name);
313		nvlist_append_nvlist_array(npf_dict, "algs", algdict);
314		nvlist_destroy(algdict);
315	}
316	return 0;
317}
318