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("$FreeBSD$");
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
50static struct mtx accept_filter_mtx;
51MTX_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
56static SLIST_HEAD(, accept_filter) accept_filtlsthd =
57	SLIST_HEAD_INITIALIZER(accept_filtlsthd);
58
59MALLOC_DEFINE(M_ACCF, "accf", "accept filter data");
60
61static int unloadable = 0;
62
63SYSCTL_NODE(_net, OID_AUTO, accf, CTLFLAG_RW, 0, "Accept filters");
64SYSCTL_INT(_net_accf, OID_AUTO, unloadable, CTLFLAG_RW, &unloadable, 0,
65	"Allow unload of accept filters (not recommended)");
66
67/*
68 * Must be passed a malloc'd structure so we don't explode if the kld is
69 * unloaded, we leak the struct on deallocation to deal with this, but if a
70 * filter is loaded with the same name as a leaked one we re-use the entry.
71 */
72int
73accept_filt_add(struct accept_filter *filt)
74{
75	struct accept_filter *p;
76
77	ACCEPT_FILTER_LOCK();
78	SLIST_FOREACH(p, &accept_filtlsthd, accf_next)
79		if (strcmp(p->accf_name, filt->accf_name) == 0)  {
80			if (p->accf_callback != NULL) {
81				ACCEPT_FILTER_UNLOCK();
82				return (EEXIST);
83			} else {
84				p->accf_callback = filt->accf_callback;
85				ACCEPT_FILTER_UNLOCK();
86				free(filt, M_ACCF);
87				return (0);
88			}
89		}
90
91	if (p == NULL)
92		SLIST_INSERT_HEAD(&accept_filtlsthd, filt, accf_next);
93	ACCEPT_FILTER_UNLOCK();
94	return (0);
95}
96
97int
98accept_filt_del(char *name)
99{
100	struct accept_filter *p;
101
102	p = accept_filt_get(name);
103	if (p == NULL)
104		return (ENOENT);
105
106	p->accf_callback = NULL;
107	return (0);
108}
109
110struct accept_filter *
111accept_filt_get(char *name)
112{
113	struct accept_filter *p;
114
115	ACCEPT_FILTER_LOCK();
116	SLIST_FOREACH(p, &accept_filtlsthd, accf_next)
117		if (strcmp(p->accf_name, name) == 0)
118			break;
119	ACCEPT_FILTER_UNLOCK();
120
121	return (p);
122}
123
124int
125accept_filt_generic_mod_event(module_t mod, int event, void *data)
126{
127	struct accept_filter *p;
128	struct accept_filter *accfp = (struct accept_filter *) data;
129	int error;
130
131	switch (event) {
132	case MOD_LOAD:
133		p = malloc(sizeof(*p), M_ACCF,
134		    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
164int
165do_getopt_accept_filter(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,
172	    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->so_options & SO_ACCEPTFILTER) == 0) {
179		error = EINVAL;
180		goto out;
181	}
182	strcpy(afap->af_name, so->so_accf->so_accept_filter->accf_name);
183	if (so->so_accf->so_accept_filter_str != NULL)
184		strcpy(afap->af_arg, so->so_accf->so_accept_filter_str);
185out:
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
193int
194do_setopt_accept_filter(struct socket *so, struct sockopt *sopt)
195{
196	struct accept_filter_arg *afap;
197	struct accept_filter *afp;
198	struct so_accf *newaf;
199	int error = 0;
200
201	/*
202	 * Handle the simple delete case first.
203	 */
204	if (sopt == NULL || sopt->sopt_val == NULL) {
205		SOCK_LOCK(so);
206		if ((so->so_options & SO_ACCEPTCONN) == 0) {
207			SOCK_UNLOCK(so);
208			return (EINVAL);
209		}
210		if (so->so_accf != NULL) {
211			struct so_accf *af = so->so_accf;
212			if (af->so_accept_filter != NULL &&
213				af->so_accept_filter->accf_destroy != NULL) {
214				af->so_accept_filter->accf_destroy(so);
215			}
216			if (af->so_accept_filter_str != NULL)
217				free(af->so_accept_filter_str, M_ACCF);
218			free(af, M_ACCF);
219			so->so_accf = NULL;
220		}
221		so->so_options &= ~SO_ACCEPTFILTER;
222		SOCK_UNLOCK(so);
223		return (0);
224	}
225
226	/*
227	 * Pre-allocate any memory we may need later to avoid blocking at
228	 * untimely moments.  This does not optimize for invalid arguments.
229	 */
230	afap = malloc(sizeof(*afap), M_TEMP,
231	    M_WAITOK);
232	error = sooptcopyin(sopt, afap, sizeof *afap, sizeof *afap);
233	afap->af_name[sizeof(afap->af_name)-1] = '\0';
234	afap->af_arg[sizeof(afap->af_arg)-1] = '\0';
235	if (error) {
236		free(afap, M_TEMP);
237		return (error);
238	}
239	afp = accept_filt_get(afap->af_name);
240	if (afp == NULL) {
241		free(afap, M_TEMP);
242		return (ENOENT);
243	}
244	/*
245	 * Allocate the new accept filter instance storage.  We may
246	 * have to free it again later if we fail to attach it.  If
247	 * attached properly, 'newaf' is NULLed to avoid a free()
248	 * while in use.
249	 */
250	newaf = malloc(sizeof(*newaf), M_ACCF, M_WAITOK |
251	    M_ZERO);
252	if (afp->accf_create != NULL && afap->af_name[0] != '\0') {
253		int len = strlen(afap->af_name) + 1;
254		newaf->so_accept_filter_str = malloc(len, M_ACCF,
255		    M_WAITOK);
256		strcpy(newaf->so_accept_filter_str, afap->af_name);
257	}
258
259	/*
260	 * Require a listen socket; don't try to replace an existing filter
261	 * without first removing it.
262	 */
263	SOCK_LOCK(so);
264	if (((so->so_options & SO_ACCEPTCONN) == 0) ||
265	    (so->so_accf != NULL)) {
266		error = EINVAL;
267		goto out;
268	}
269
270	/*
271	 * Invoke the accf_create() method of the filter if required.  The
272	 * socket mutex is held over this call, so create methods for filters
273	 * can't block.
274	 */
275	if (afp->accf_create != NULL) {
276		newaf->so_accept_filter_arg =
277		    afp->accf_create(so, afap->af_arg);
278		if (newaf->so_accept_filter_arg == NULL) {
279			error = EINVAL;
280			goto out;
281		}
282	}
283	newaf->so_accept_filter = afp;
284	so->so_accf = newaf;
285	so->so_options |= SO_ACCEPTFILTER;
286	newaf = NULL;
287out:
288	SOCK_UNLOCK(so);
289	if (newaf != NULL) {
290		if (newaf->so_accept_filter_str != NULL)
291			free(newaf->so_accept_filter_str, M_ACCF);
292		free(newaf, M_ACCF);
293	}
294	if (afap != NULL)
295		free(afap, M_TEMP);
296	return (error);
297}
298