FreeBSD/Linux Kernel Cross Reference
sys/kern/uipc_accf.c
1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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 __FBSDID("$FreeBSD$");
33
34 #define ACCEPT_FILTER_MOD
35
36 #include "opt_param.h"
37 #include <sys/param.h>
38 #include <sys/systm.h>
39 #include <sys/domain.h>
40 #include <sys/kernel.h>
41 #include <sys/lock.h>
42 #include <sys/malloc.h>
43 #include <sys/mbuf.h>
44 #include <sys/module.h>
45 #include <sys/mutex.h>
46 #include <sys/protosw.h>
47 #include <sys/sysctl.h>
48 #include <sys/socket.h>
49 #include <sys/socketvar.h>
50 #include <sys/queue.h>
51
52 static struct mtx accept_filter_mtx;
53 MTX_SYSINIT(accept_filter, &accept_filter_mtx, "accept_filter_mtx",
54 MTX_DEF);
55 #define ACCEPT_FILTER_LOCK() mtx_lock(&accept_filter_mtx)
56 #define ACCEPT_FILTER_UNLOCK() mtx_unlock(&accept_filter_mtx)
57
58 static SLIST_HEAD(, accept_filter) accept_filtlsthd =
59 SLIST_HEAD_INITIALIZER(accept_filtlsthd);
60
61 MALLOC_DEFINE(M_ACCF, "accf", "accept filter data");
62
63 static int unloadable = 0;
64
65 SYSCTL_NODE(_net, OID_AUTO, accf, CTLFLAG_RW, 0, "Accept filters");
66 SYSCTL_INT(_net_accf, OID_AUTO, unloadable, CTLFLAG_RW, &unloadable, 0,
67 "Allow unload of accept filters (not recommended)");
68
69 /*
70 * Must be passed a malloc'd structure so we don't explode if the kld is
71 * unloaded, we leak the struct on deallocation to deal with this, but if a
72 * filter is loaded with the same name as a leaked one we re-use the entry.
73 */
74 int
75 accept_filt_add(struct accept_filter *filt)
76 {
77 struct accept_filter *p;
78
79 ACCEPT_FILTER_LOCK();
80 SLIST_FOREACH(p, &accept_filtlsthd, accf_next)
81 if (strcmp(p->accf_name, filt->accf_name) == 0) {
82 if (p->accf_callback != NULL) {
83 ACCEPT_FILTER_UNLOCK();
84 return (EEXIST);
85 } else {
86 p->accf_callback = filt->accf_callback;
87 ACCEPT_FILTER_UNLOCK();
88 free(filt, M_ACCF);
89 return (0);
90 }
91 }
92
93 if (p == NULL)
94 SLIST_INSERT_HEAD(&accept_filtlsthd, filt, accf_next);
95 ACCEPT_FILTER_UNLOCK();
96 return (0);
97 }
98
99 int
100 accept_filt_del(char *name)
101 {
102 struct accept_filter *p;
103
104 p = accept_filt_get(name);
105 if (p == NULL)
106 return (ENOENT);
107
108 p->accf_callback = NULL;
109 return (0);
110 }
111
112 struct accept_filter *
113 accept_filt_get(char *name)
114 {
115 struct accept_filter *p;
116
117 ACCEPT_FILTER_LOCK();
118 SLIST_FOREACH(p, &accept_filtlsthd, accf_next)
119 if (strcmp(p->accf_name, name) == 0)
120 break;
121 ACCEPT_FILTER_UNLOCK();
122
123 return (p);
124 }
125
126 int
127 accept_filt_generic_mod_event(module_t mod, int event, void *data)
128 {
129 struct accept_filter *p;
130 struct accept_filter *accfp = (struct accept_filter *) data;
131 int error;
132
133 switch (event) {
134 case MOD_LOAD:
135 p = malloc(sizeof(*p), M_ACCF, M_WAITOK);
136 bcopy(accfp, p, sizeof(*p));
137 error = accept_filt_add(p);
138 break;
139
140 case MOD_UNLOAD:
141 /*
142 * Do not support unloading yet. we don't keep track of
143 * refcounts and unloading an accept filter callback and then
144 * having it called is a bad thing. A simple fix would be to
145 * track the refcount in the struct accept_filter.
146 */
147 if (unloadable != 0) {
148 error = accept_filt_del(accfp->accf_name);
149 } else
150 error = EOPNOTSUPP;
151 break;
152
153 case MOD_SHUTDOWN:
154 error = 0;
155 break;
156
157 default:
158 error = EOPNOTSUPP;
159 break;
160 }
161
162 return (error);
163 }
164
165 int
166 accept_filt_getopt(struct socket *so, struct sockopt *sopt)
167 {
168 struct accept_filter_arg *afap;
169 int error;
170
171 error = 0;
172 afap = malloc(sizeof(*afap), M_TEMP, M_WAITOK | M_ZERO);
173 SOCK_LOCK(so);
174 if ((so->so_options & SO_ACCEPTCONN) == 0) {
175 error = EINVAL;
176 goto out;
177 }
178 if (so->sol_accept_filter == NULL) {
179 error = EINVAL;
180 goto out;
181 }
182 strcpy(afap->af_name, so->sol_accept_filter->accf_name);
183 if (so->sol_accept_filter_str != NULL)
184 strcpy(afap->af_arg, so->sol_accept_filter_str);
185 out:
186 SOCK_UNLOCK(so);
187 if (error == 0)
188 error = sooptcopyout(sopt, afap, sizeof(*afap));
189 free(afap, M_TEMP);
190 return (error);
191 }
192
193 int
194 accept_filt_setopt(struct socket *so, struct sockopt *sopt)
195 {
196 struct accept_filter_arg *afap;
197 struct accept_filter *afp;
198 char *accept_filter_str = NULL;
199 void *accept_filter_arg = NULL;
200 int error;
201
202 /*
203 * Handle the simple delete case first.
204 */
205 if (sopt == NULL || sopt->sopt_val == NULL) {
206 struct socket *sp, *sp1;
207 int wakeup;
208
209 SOCK_LOCK(so);
210 if ((so->so_options & SO_ACCEPTCONN) == 0) {
211 SOCK_UNLOCK(so);
212 return (EINVAL);
213 }
214 if (so->sol_accept_filter == NULL) {
215 SOCK_UNLOCK(so);
216 return (0);
217 }
218 if (so->sol_accept_filter->accf_destroy != NULL)
219 so->sol_accept_filter->accf_destroy(so);
220 if (so->sol_accept_filter_str != NULL)
221 free(so->sol_accept_filter_str, M_ACCF);
222 so->sol_accept_filter = NULL;
223 so->sol_accept_filter_arg = NULL;
224 so->sol_accept_filter_str = NULL;
225 so->so_options &= ~SO_ACCEPTFILTER;
226
227 /*
228 * Move from incomplete queue to complete only those
229 * connections, that are blocked by us.
230 */
231 wakeup = 0;
232 TAILQ_FOREACH_SAFE(sp, &so->sol_incomp, so_list, sp1) {
233 SOCK_LOCK(sp);
234 if (sp->so_options & SO_ACCEPTFILTER) {
235 TAILQ_REMOVE(&so->sol_incomp, sp, so_list);
236 TAILQ_INSERT_TAIL(&so->sol_comp, sp, so_list);
237 sp->so_qstate = SQ_COMP;
238 sp->so_options &= ~SO_ACCEPTFILTER;
239 so->sol_incqlen--;
240 so->sol_qlen++;
241 wakeup = 1;
242 }
243 SOCK_UNLOCK(sp);
244 }
245 if (wakeup)
246 solisten_wakeup(so); /* unlocks */
247 else
248 SOLISTEN_UNLOCK(so);
249 return (0);
250 }
251
252 /*
253 * Pre-allocate any memory we may need later to avoid blocking at
254 * untimely moments. This does not optimize for invalid arguments.
255 */
256 afap = malloc(sizeof(*afap), M_TEMP, M_WAITOK);
257 error = sooptcopyin(sopt, afap, sizeof *afap, sizeof *afap);
258 afap->af_name[sizeof(afap->af_name)-1] = '\0';
259 afap->af_arg[sizeof(afap->af_arg)-1] = '\0';
260 if (error) {
261 free(afap, M_TEMP);
262 return (error);
263 }
264 afp = accept_filt_get(afap->af_name);
265 if (afp == NULL) {
266 free(afap, M_TEMP);
267 return (ENOENT);
268 }
269 if (afp->accf_create != NULL && afap->af_name[0] != '\0') {
270 size_t len = strlen(afap->af_name) + 1;
271 accept_filter_str = malloc(len, M_ACCF, M_WAITOK);
272 strcpy(accept_filter_str, afap->af_name);
273 }
274
275 /*
276 * Require a listen socket; don't try to replace an existing filter
277 * without first removing it.
278 */
279 SOCK_LOCK(so);
280 if ((so->so_options & SO_ACCEPTCONN) == 0 ||
281 so->sol_accept_filter != NULL) {
282 error = EINVAL;
283 goto out;
284 }
285
286 /*
287 * Invoke the accf_create() method of the filter if required. The
288 * socket mutex is held over this call, so create methods for filters
289 * can't block.
290 */
291 if (afp->accf_create != NULL) {
292 accept_filter_arg = afp->accf_create(so, afap->af_arg);
293 if (accept_filter_arg == NULL) {
294 error = EINVAL;
295 goto out;
296 }
297 }
298 so->sol_accept_filter = afp;
299 so->sol_accept_filter_arg = accept_filter_arg;
300 so->sol_accept_filter_str = accept_filter_str;
301 accept_filter_str = NULL;
302 so->so_options |= SO_ACCEPTFILTER;
303 out:
304 SOCK_UNLOCK(so);
305 if (accept_filter_str != NULL)
306 free(accept_filter_str, M_ACCF);
307 free(afap, M_TEMP);
308 return (error);
309 }
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