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_DECL(_net_inet);	/* XXX: some header should do this for me */
64SYSCTL_NODE(_net_inet, OID_AUTO, accf, CTLFLAG_RW, 0, "Accept filters");
65SYSCTL_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 */
73int
74accept_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
98int
99accept_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
111struct accept_filter *
112accept_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
125int
126accept_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
165int
166do_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);
186out:
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
194int
195do_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;
288out:
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}
299