1/* $NetBSD: uipc_accf.c,v 1.13 2014/02/25 18:30:11 pooka Exp $ */
2
3/*-
4 * Copyright (c) 2008 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software developed for The NetBSD Foundation
8 * by Andrew Doran.
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 * Copyright (c) 2000 Paycounter, Inc.
34 * Copyright (c) 2005 Robert N. M. Watson
35 * Author: Alfred Perlstein <alfred@paycounter.com>, <alfred@FreeBSD.org>
36 * All rights reserved.
37 *
38 * Redistribution and use in source and binary forms, with or without
39 * modification, are permitted provided that the following conditions
40 * are met:
41 * 1. Redistributions of source code must retain the above copyright
42 * notice, this list of conditions and the following disclaimer.
43 * 2. Redistributions in binary form must reproduce the above copyright
44 * notice, this list of conditions and the following disclaimer in the
45 * documentation and/or other materials provided with the distribution.
46 *
47 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
48 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
49 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
50 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
51 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
52 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
53 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
54 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
55 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
56 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
57 * SUCH DAMAGE.
58 */
59
60#include <sys/cdefs.h>
61__KERNEL_RCSID(0, "$NetBSD: uipc_accf.c,v 1.13 2014/02/25 18:30:11 pooka Exp $");
62
63#define ACCEPT_FILTER_MOD
64
65#include <sys/param.h>
66#include <sys/systm.h>
67#include <sys/domain.h>
68#include <sys/kernel.h>
69#include <sys/lock.h>
70#include <sys/kmem.h>
71#include <sys/mbuf.h>
72#include <sys/rwlock.h>
73#include <sys/protosw.h>
74#include <sys/sysctl.h>
75#include <sys/socket.h>
76#include <sys/socketvar.h>
77#include <sys/queue.h>
78#include <sys/once.h>
79#include <sys/atomic.h>
80#include <sys/module.h>
81
82static krwlock_t accept_filter_lock;
83
84static LIST_HEAD(, accept_filter) accept_filtlsthd =
85 LIST_HEAD_INITIALIZER(&accept_filtlsthd);
86
87/*
88 * Names of Accept filter sysctl objects
89 */
90static struct sysctllog *ctllog;
91static void
92sysctl_net_inet_accf_setup(void)
93{
94
95 sysctl_createv(&ctllog, 0, NULL, NULL,
96 CTLFLAG_PERMANENT,
97 CTLTYPE_NODE, "inet", NULL,
98 NULL, 0, NULL, 0,
99 CTL_NET, PF_INET, CTL_EOL);
100 sysctl_createv(&ctllog, 0, NULL, NULL,
101 CTLFLAG_PERMANENT,
102 CTLTYPE_NODE, "accf",
103 SYSCTL_DESCR("Accept filters"),
104 NULL, 0, NULL, 0,
105 CTL_NET, PF_INET, SO_ACCEPTFILTER, CTL_EOL);
106}
107
108int
109accept_filt_add(struct accept_filter *filt)
110{
111 struct accept_filter *p;
112
113 accept_filter_init();
114
115 rw_enter(&accept_filter_lock, RW_WRITER);
116 LIST_FOREACH(p, &accept_filtlsthd, accf_next) {
117 if (strcmp(p->accf_name, filt->accf_name) == 0) {
118 rw_exit(&accept_filter_lock);
119 return EEXIST;
120 }
121 }
122 LIST_INSERT_HEAD(&accept_filtlsthd, filt, accf_next);
123 rw_exit(&accept_filter_lock);
124
125 return 0;
126}
127
128int
129accept_filt_del(struct accept_filter *p)
130{
131
132 rw_enter(&accept_filter_lock, RW_WRITER);
133 if (p->accf_refcnt != 0) {
134 rw_exit(&accept_filter_lock);
135 return EBUSY;
136 }
137 LIST_REMOVE(p, accf_next);
138 rw_exit(&accept_filter_lock);
139
140 return 0;
141}
142
143struct accept_filter *
144accept_filt_get(char *name)
145{
146 struct accept_filter *p;
147 char buf[32];
148 u_int gen;
149
150 do {
151 rw_enter(&accept_filter_lock, RW_READER);
152 LIST_FOREACH(p, &accept_filtlsthd, accf_next) {
153 if (strcmp(p->accf_name, name) == 0) {
154 atomic_inc_uint(&p->accf_refcnt);
155 break;
156 }
157 }
158 rw_exit(&accept_filter_lock);
159 if (p != NULL) {
160 break;
161 }
162 /* Try to autoload a module to satisfy the request. */
163 strcpy(buf, "accf_");
164 strlcat(buf, name, sizeof(buf));
165 gen = module_gen;
166 (void)module_autoload(buf, MODULE_CLASS_ANY);
167 } while (gen != module_gen);
168
169 return p;
170}
171
172/*
173 * Accept filter initialization routine.
174 * This should be called only once.
175 */
176
177static int
178accept_filter_init0(void)
179{
180
181 rw_init(&accept_filter_lock);
182 sysctl_net_inet_accf_setup();
183
184 return 0;
185}
186
187/*
188 * Initialization routine: This can also be replaced with
189 * accept_filt_generic_mod_event for attaching new accept filter.
190 */
191
192void
193accept_filter_init(void)
194{
195 static ONCE_DECL(accept_filter_init_once);
196
197 RUN_ONCE(&accept_filter_init_once, accept_filter_init0);
198}
199
200int
201accept_filt_getopt(struct socket *so, struct sockopt *sopt)
202{
203 struct accept_filter_arg afa;
204 int error;
205
206 KASSERT(solocked(so));
207
208 if ((so->so_options & SO_ACCEPTCONN) == 0) {
209 error = EINVAL;
210 goto out;
211 }
212 if ((so->so_options & SO_ACCEPTFILTER) == 0) {
213 error = EINVAL;
214 goto out;
215 }
216
217 memset(&afa, 0, sizeof(afa));
218 strcpy(afa.af_name, so->so_accf->so_accept_filter->accf_name);
219 if (so->so_accf->so_accept_filter_str != NULL)
220 strcpy(afa.af_arg, so->so_accf->so_accept_filter_str);
221 error = sockopt_set(sopt, &afa, sizeof(afa));
222out:
223 return error;
224}
225
226/*
227 * Simple delete case, with socket locked.
228 */
229int
230accept_filt_clear(struct socket *so)
231{
232 struct accept_filter_arg afa;
233 struct accept_filter *afp;
234 struct socket *so2, *next;
235 struct so_accf *af;
236
237 KASSERT(solocked(so));
238
239 if ((so->so_options & SO_ACCEPTCONN) == 0) {
240 return EINVAL;
241 }
242 if (so->so_accf != NULL) {
243 /* Break in-flight processing. */
244 for (so2 = TAILQ_FIRST(&so->so_q0); so2 != NULL; so2 = next) {
245 next = TAILQ_NEXT(so2, so_qe);
246 if (so2->so_upcall == NULL) {
247 continue;
248 }
249 so2->so_upcall = NULL;
250 so2->so_upcallarg = NULL;
251 so2->so_options &= ~SO_ACCEPTFILTER;
252 so2->so_rcv.sb_flags &= ~SB_UPCALL;
253 soisconnected(so2);
254 }
255 af = so->so_accf;
256 afp = af->so_accept_filter;
257 if (afp != NULL && afp->accf_destroy != NULL) {
258 (*afp->accf_destroy)(so);
259 }
260 if (af->so_accept_filter_str != NULL) {
261 kmem_free(af->so_accept_filter_str,
262 sizeof(afa.af_name));
263 }
264 kmem_free(af, sizeof(*af));
265 so->so_accf = NULL;
266 atomic_dec_uint(&afp->accf_refcnt);
267 }
268 so->so_options &= ~SO_ACCEPTFILTER;
269 return 0;
270}
271
272/*
273 * setsockopt() for accept filters. Called with the socket unlocked,
274 * will always return it locked.
275 */
276int
277accept_filt_setopt(struct socket *so, const struct sockopt *sopt)
278{
279 struct accept_filter_arg afa;
280 struct accept_filter *afp;
281 struct so_accf *newaf;
282 int error;
283
284 accept_filter_init();
285
286 if (sopt == NULL || sopt->sopt_size == 0) {
287 solock(so);
288 return accept_filt_clear(so);
289 }
290
291 /*
292 * Pre-allocate any memory we may need later to avoid blocking at
293 * untimely moments. This does not optimize for invalid arguments.
294 */
295 error = sockopt_get(sopt, &afa, sizeof(afa));
296 if (error) {
297 solock(so);
298 return error;
299 }
300 afa.af_name[sizeof(afa.af_name)-1] = '\0';
301 afa.af_arg[sizeof(afa.af_arg)-1] = '\0';
302 afp = accept_filt_get(afa.af_name);
303 if (afp == NULL) {
304 solock(so);
305 return ENOENT;
306 }
307 /*
308 * Allocate the new accept filter instance storage. We may
309 * have to free it again later if we fail to attach it. If
310 * attached properly, 'newaf' is NULLed to avoid a free()
311 * while in use.
312 */
313 newaf = kmem_zalloc(sizeof(*newaf), KM_SLEEP);
314 if (afp->accf_create != NULL && afa.af_name[0] != '\0') {
315 /*
316 * FreeBSD did a variable-size allocation here
317 * with the actual string length from afa.af_name
318 * but it is so short, why bother tracking it?
319 * XXX as others have noted, this is an API mistake;
320 * XXX accept_filter_arg should have a mandatory namelen.
321 * XXX (but it's a bit too late to fix that now)
322 */
323 newaf->so_accept_filter_str =
324 kmem_alloc(sizeof(afa.af_name), KM_SLEEP);
325 strcpy(newaf->so_accept_filter_str, afa.af_name);
326 }
327
328 /*
329 * Require a listen socket; don't try to replace an existing filter
330 * without first removing it.
331 */
332 solock(so);
333 if ((so->so_options & SO_ACCEPTCONN) == 0 || so->so_accf != NULL) {
334 error = EINVAL;
335 goto out;
336 }
337
338 /*
339 * Invoke the accf_create() method of the filter if required. The
340 * socket lock is held over this call, so create methods for filters
341 * shouldn't block.
342 */
343 if (afp->accf_create != NULL) {
344 newaf->so_accept_filter_arg =
345 (*afp->accf_create)(so, afa.af_arg);
346 if (newaf->so_accept_filter_arg == NULL) {
347 error = EINVAL;
348 goto out;
349 }
350 }
351 newaf->so_accept_filter = afp;
352 so->so_accf = newaf;
353 so->so_options |= SO_ACCEPTFILTER;
354 newaf = NULL;
355out:
356 if (newaf != NULL) {
357 if (newaf->so_accept_filter_str != NULL)
358 kmem_free(newaf->so_accept_filter_str,
359 sizeof(afa.af_name));
360 kmem_free(newaf, sizeof(*newaf));
361 atomic_dec_uint(&afp->accf_refcnt);
362 }
363 return error;
364}
365