1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2000 Paycounter, Inc.
5 * Copyright (c) 2005 Robert N. M. Watson
6 * Author: Alfred Perlstein <alfred@paycounter.com>, <alfred@FreeBSD.org>
7 * All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 */
30
31 #include <sys/cdefs.h>
32 #define ACCEPT_FILTER_MOD
33
34 #include "opt_param.h"
35 #include <sys/param.h>
36 #include <sys/systm.h>
37 #include <sys/domain.h>
38 #include <sys/kernel.h>
39 #include <sys/lock.h>
40 #include <sys/malloc.h>
41 #include <sys/mbuf.h>
42 #include <sys/module.h>
43 #include <sys/mutex.h>
44 #include <sys/protosw.h>
45 #include <sys/sysctl.h>
46 #include <sys/socket.h>
47 #include <sys/socketvar.h>
48 #include <sys/queue.h>
49
50 static struct mtx accept_filter_mtx;
51 MTX_SYSINIT(accept_filter, &accept_filter_mtx, "accept_filter_mtx",
52 MTX_DEF);
53 #define ACCEPT_FILTER_LOCK() mtx_lock(&accept_filter_mtx)
54 #define ACCEPT_FILTER_UNLOCK() mtx_unlock(&accept_filter_mtx)
55
56 static SLIST_HEAD(, accept_filter) accept_filtlsthd =
57 SLIST_HEAD_INITIALIZER(accept_filtlsthd);
58
59 MALLOC_DEFINE(M_ACCF, "accf", "accept filter data");
60
61 static int unloadable = 0;
62
63 SYSCTL_NODE(_net, OID_AUTO, accf, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
64 "Accept filters");
65 SYSCTL_INT(_net_accf, OID_AUTO, unloadable, CTLFLAG_RW, &unloadable, 0,
66 "Allow unload of accept filters (not recommended)");
67
68 /*
69 * Must be passed a malloc'd structure so we don't explode if the kld is
70 * unloaded, we leak the struct on deallocation to deal with this, but if a
71 * filter is loaded with the same name as a leaked one we re-use the entry.
72 */
73 int
accept_filt_add(struct accept_filter * filt)74 accept_filt_add(struct accept_filter *filt)
75 {
76 struct accept_filter *p;
77
78 ACCEPT_FILTER_LOCK();
79 SLIST_FOREACH(p, &accept_filtlsthd, accf_next)
80 if (strcmp(p->accf_name, filt->accf_name) == 0) {
81 if (p->accf_callback != NULL) {
82 ACCEPT_FILTER_UNLOCK();
83 return (EEXIST);
84 } else {
85 p->accf_callback = filt->accf_callback;
86 ACCEPT_FILTER_UNLOCK();
87 free(filt, M_ACCF);
88 return (0);
89 }
90 }
91
92 if (p == NULL)
93 SLIST_INSERT_HEAD(&accept_filtlsthd, filt, accf_next);
94 ACCEPT_FILTER_UNLOCK();
95 return (0);
96 }
97
98 int
accept_filt_del(char * name)99 accept_filt_del(char *name)
100 {
101 struct accept_filter *p;
102
103 p = accept_filt_get(name);
104 if (p == NULL)
105 return (ENOENT);
106
107 p->accf_callback = NULL;
108 return (0);
109 }
110
111 struct accept_filter *
accept_filt_get(char * name)112 accept_filt_get(char *name)
113 {
114 struct accept_filter *p;
115
116 ACCEPT_FILTER_LOCK();
117 SLIST_FOREACH(p, &accept_filtlsthd, accf_next)
118 if (strcmp(p->accf_name, name) == 0)
119 break;
120 ACCEPT_FILTER_UNLOCK();
121
122 return (p);
123 }
124
125 int
accept_filt_generic_mod_event(module_t mod,int event,void * data)126 accept_filt_generic_mod_event(module_t mod, int event, void *data)
127 {
128 struct accept_filter *p;
129 struct accept_filter *accfp = (struct accept_filter *) data;
130 int error;
131
132 switch (event) {
133 case MOD_LOAD:
134 p = malloc(sizeof(*p), M_ACCF, M_WAITOK);
135 bcopy(accfp, p, sizeof(*p));
136 error = accept_filt_add(p);
137 break;
138
139 case MOD_UNLOAD:
140 /*
141 * Do not support unloading yet. we don't keep track of
142 * refcounts and unloading an accept filter callback and then
143 * having it called is a bad thing. A simple fix would be to
144 * track the refcount in the struct accept_filter.
145 */
146 if (unloadable != 0) {
147 error = accept_filt_del(accfp->accf_name);
148 } else
149 error = EOPNOTSUPP;
150 break;
151
152 case MOD_SHUTDOWN:
153 error = 0;
154 break;
155
156 default:
157 error = EOPNOTSUPP;
158 break;
159 }
160
161 return (error);
162 }
163
164 int
accept_filt_getopt(struct socket * so,struct sockopt * sopt)165 accept_filt_getopt(struct socket *so, struct sockopt *sopt)
166 {
167 struct accept_filter_arg *afap;
168 int error;
169
170 error = 0;
171 afap = malloc(sizeof(*afap), M_TEMP, M_WAITOK | M_ZERO);
172 SOCK_LOCK(so);
173 if (!SOLISTENING(so)) {
174 error = EINVAL;
175 goto out;
176 }
177 if (so->sol_accept_filter == NULL) {
178 error = EINVAL;
179 goto out;
180 }
181 strcpy(afap->af_name, so->sol_accept_filter->accf_name);
182 if (so->sol_accept_filter_str != NULL)
183 strcpy(afap->af_arg, so->sol_accept_filter_str);
184 out:
185 SOCK_UNLOCK(so);
186 if (error == 0)
187 error = sooptcopyout(sopt, afap, sizeof(*afap));
188 free(afap, M_TEMP);
189 return (error);
190 }
191
192 int
accept_filt_setopt(struct socket * so,struct sockopt * sopt)193 accept_filt_setopt(struct socket *so, struct sockopt *sopt)
194 {
195 struct accept_filter_arg *afap;
196 struct accept_filter *afp;
197 char *accept_filter_str = NULL;
198 void *accept_filter_arg = NULL;
199 int error;
200
201 /*
202 * Handle the simple delete case first.
203 */
204 if (sopt == NULL || sopt->sopt_val == NULL) {
205 struct socket *sp, *sp1;
206 int wakeup;
207
208 SOCK_LOCK(so);
209 if (!SOLISTENING(so)) {
210 SOCK_UNLOCK(so);
211 return (EINVAL);
212 }
213 if (so->sol_accept_filter == NULL) {
214 SOCK_UNLOCK(so);
215 return (0);
216 }
217 if (so->sol_accept_filter->accf_destroy != NULL)
218 so->sol_accept_filter->accf_destroy(so);
219 if (so->sol_accept_filter_str != NULL)
220 free(so->sol_accept_filter_str, M_ACCF);
221 so->sol_accept_filter = NULL;
222 so->sol_accept_filter_arg = NULL;
223 so->sol_accept_filter_str = NULL;
224 so->so_options &= ~SO_ACCEPTFILTER;
225
226 /*
227 * Move from incomplete queue to complete only those
228 * connections, that are blocked by us.
229 */
230 wakeup = 0;
231 TAILQ_FOREACH_SAFE(sp, &so->sol_incomp, so_list, sp1) {
232 SOCK_LOCK(sp);
233 if (sp->so_options & SO_ACCEPTFILTER) {
234 TAILQ_REMOVE(&so->sol_incomp, sp, so_list);
235 TAILQ_INSERT_TAIL(&so->sol_comp, sp, so_list);
236 sp->so_qstate = SQ_COMP;
237 sp->so_options &= ~SO_ACCEPTFILTER;
238 so->sol_incqlen--;
239 so->sol_qlen++;
240 wakeup = 1;
241 }
242 SOCK_UNLOCK(sp);
243 }
244 if (wakeup)
245 solisten_wakeup(so); /* unlocks */
246 else
247 SOLISTEN_UNLOCK(so);
248 return (0);
249 }
250
251 /*
252 * Pre-allocate any memory we may need later to avoid blocking at
253 * untimely moments. This does not optimize for invalid arguments.
254 */
255 afap = malloc(sizeof(*afap), M_TEMP, M_WAITOK);
256 error = sooptcopyin(sopt, afap, sizeof *afap, sizeof *afap);
257 afap->af_name[sizeof(afap->af_name)-1] = '\0';
258 afap->af_arg[sizeof(afap->af_arg)-1] = '\0';
259 if (error) {
260 free(afap, M_TEMP);
261 return (error);
262 }
263 afp = accept_filt_get(afap->af_name);
264 if (afp == NULL) {
265 free(afap, M_TEMP);
266 return (ENOENT);
267 }
268 if (afp->accf_create != NULL && afap->af_name[0] != '\0') {
269 size_t len = strlen(afap->af_name) + 1;
270 accept_filter_str = malloc(len, M_ACCF, M_WAITOK);
271 strcpy(accept_filter_str, afap->af_name);
272 }
273
274 /*
275 * Require a listen socket; don't try to replace an existing filter
276 * without first removing it.
277 */
278 SOCK_LOCK(so);
279 if (__predict_false(!SOLISTENING(so))) {
280 error = EINVAL;
281 goto out;
282 }
283 if (__predict_false(so->sol_accept_filter != NULL)) {
284 error = EBUSY;
285 goto out;
286 }
287
288 /*
289 * Invoke the accf_create() method of the filter if required. The
290 * socket mutex is held over this call, so create methods for filters
291 * can't block.
292 */
293 if (afp->accf_create != NULL) {
294 accept_filter_arg = afp->accf_create(so, afap->af_arg);
295 if (accept_filter_arg == NULL) {
296 error = EINVAL;
297 goto out;
298 }
299 }
300 so->sol_accept_filter = afp;
301 so->sol_accept_filter_arg = accept_filter_arg;
302 so->sol_accept_filter_str = accept_filter_str;
303 accept_filter_str = NULL;
304 so->so_options |= SO_ACCEPTFILTER;
305 out:
306 SOCK_UNLOCK(so);
307 if (accept_filter_str != NULL)
308 free(accept_filter_str, M_ACCF);
309 free(afap, M_TEMP);
310 return (error);
311 }
312