FreeBSD/Linux Kernel Cross Reference
sys/kern/uipc_accf.c
1 /*-
2 * Copyright (c) 2000 Paycounter, Inc.
3 * Copyright (c) 2005 Robert N. M. Watson
4 * Author: Alfred Perlstein <alfred@paycounter.com>, <alfred@FreeBSD.org>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD: releng/10.2/sys/kern/uipc_accf.c 201145 2009-12-28 22:56:30Z antoine $");
31
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_DECL(_net_inet); /* XXX: some header should do this for me */
64 SYSCTL_NODE(_net_inet, OID_AUTO, accf, CTLFLAG_RW, 0, "Accept filters");
65 SYSCTL_INT(_net_inet_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
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
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 *
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
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,
135 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 do_getopt_accept_filter(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,
173 M_WAITOK | M_ZERO);
174 SOCK_LOCK(so);
175 if ((so->so_options & SO_ACCEPTCONN) == 0) {
176 error = EINVAL;
177 goto out;
178 }
179 if ((so->so_options & SO_ACCEPTFILTER) == 0) {
180 error = EINVAL;
181 goto out;
182 }
183 strcpy(afap->af_name, so->so_accf->so_accept_filter->accf_name);
184 if (so->so_accf->so_accept_filter_str != NULL)
185 strcpy(afap->af_arg, so->so_accf->so_accept_filter_str);
186 out:
187 SOCK_UNLOCK(so);
188 if (error == 0)
189 error = sooptcopyout(sopt, afap, sizeof(*afap));
190 free(afap, M_TEMP);
191 return (error);
192 }
193
194 int
195 do_setopt_accept_filter(struct socket *so, struct sockopt *sopt)
196 {
197 struct accept_filter_arg *afap;
198 struct accept_filter *afp;
199 struct so_accf *newaf;
200 int error = 0;
201
202 /*
203 * Handle the simple delete case first.
204 */
205 if (sopt == NULL || sopt->sopt_val == NULL) {
206 SOCK_LOCK(so);
207 if ((so->so_options & SO_ACCEPTCONN) == 0) {
208 SOCK_UNLOCK(so);
209 return (EINVAL);
210 }
211 if (so->so_accf != NULL) {
212 struct so_accf *af = so->so_accf;
213 if (af->so_accept_filter != NULL &&
214 af->so_accept_filter->accf_destroy != NULL) {
215 af->so_accept_filter->accf_destroy(so);
216 }
217 if (af->so_accept_filter_str != NULL)
218 free(af->so_accept_filter_str, M_ACCF);
219 free(af, M_ACCF);
220 so->so_accf = NULL;
221 }
222 so->so_options &= ~SO_ACCEPTFILTER;
223 SOCK_UNLOCK(so);
224 return (0);
225 }
226
227 /*
228 * Pre-allocate any memory we may need later to avoid blocking at
229 * untimely moments. This does not optimize for invalid arguments.
230 */
231 afap = malloc(sizeof(*afap), M_TEMP,
232 M_WAITOK);
233 error = sooptcopyin(sopt, afap, sizeof *afap, sizeof *afap);
234 afap->af_name[sizeof(afap->af_name)-1] = '\0';
235 afap->af_arg[sizeof(afap->af_arg)-1] = '\0';
236 if (error) {
237 free(afap, M_TEMP);
238 return (error);
239 }
240 afp = accept_filt_get(afap->af_name);
241 if (afp == NULL) {
242 free(afap, M_TEMP);
243 return (ENOENT);
244 }
245 /*
246 * Allocate the new accept filter instance storage. We may
247 * have to free it again later if we fail to attach it. If
248 * attached properly, 'newaf' is NULLed to avoid a free()
249 * while in use.
250 */
251 newaf = malloc(sizeof(*newaf), M_ACCF, M_WAITOK |
252 M_ZERO);
253 if (afp->accf_create != NULL && afap->af_name[0] != '\0') {
254 int len = strlen(afap->af_name) + 1;
255 newaf->so_accept_filter_str = malloc(len, M_ACCF,
256 M_WAITOK);
257 strcpy(newaf->so_accept_filter_str, afap->af_name);
258 }
259
260 /*
261 * Require a listen socket; don't try to replace an existing filter
262 * without first removing it.
263 */
264 SOCK_LOCK(so);
265 if (((so->so_options & SO_ACCEPTCONN) == 0) ||
266 (so->so_accf != NULL)) {
267 error = EINVAL;
268 goto out;
269 }
270
271 /*
272 * Invoke the accf_create() method of the filter if required. The
273 * socket mutex is held over this call, so create methods for filters
274 * can't block.
275 */
276 if (afp->accf_create != NULL) {
277 newaf->so_accept_filter_arg =
278 afp->accf_create(so, afap->af_arg);
279 if (newaf->so_accept_filter_arg == NULL) {
280 error = EINVAL;
281 goto out;
282 }
283 }
284 newaf->so_accept_filter = afp;
285 so->so_accf = newaf;
286 so->so_options |= SO_ACCEPTFILTER;
287 newaf = NULL;
288 out:
289 SOCK_UNLOCK(so);
290 if (newaf != NULL) {
291 if (newaf->so_accept_filter_str != NULL)
292 free(newaf->so_accept_filter_str, M_ACCF);
293 free(newaf, M_ACCF);
294 }
295 if (afap != NULL)
296 free(afap, M_TEMP);
297 return (error);
298 }
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