xref: /freebsd/sys/netgraph/ng_ipfw.c (revision 39beb93c3f8bdbf72a61fda42300b5ebed7390c8)
1 /*-
2  * Copyright 2005, Gleb Smirnoff <glebius@FreeBSD.org>
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  *
14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24  * SUCH DAMAGE.
25  *
26  * $FreeBSD$
27  */
28 
29 #include <sys/param.h>
30 #include <sys/systm.h>
31 #include <sys/kernel.h>
32 #include <sys/lock.h>
33 #include <sys/mbuf.h>
34 #include <sys/malloc.h>
35 #include <sys/ctype.h>
36 #include <sys/errno.h>
37 #include <sys/rwlock.h>
38 #include <sys/socket.h>
39 #include <sys/syslog.h>
40 
41 #include <net/if.h>
42 
43 #include <netinet/in.h>
44 #include <netinet/in_systm.h>
45 #include <netinet/in_var.h>
46 #include <netinet/ip_fw.h>
47 #include <netinet/ip.h>
48 #include <netinet/ip_var.h>
49 
50 #include <netgraph/ng_message.h>
51 #include <netgraph/ng_parse.h>
52 #include <netgraph/ng_ipfw.h>
53 #include <netgraph/netgraph.h>
54 
55 static int		ng_ipfw_mod_event(module_t mod, int event, void *data);
56 static ng_constructor_t	ng_ipfw_constructor;
57 static ng_shutdown_t	ng_ipfw_shutdown;
58 static ng_newhook_t	ng_ipfw_newhook;
59 static ng_connect_t	ng_ipfw_connect;
60 static ng_findhook_t	ng_ipfw_findhook;
61 static ng_rcvdata_t	ng_ipfw_rcvdata;
62 static ng_disconnect_t	ng_ipfw_disconnect;
63 
64 static hook_p		ng_ipfw_findhook1(node_p, u_int16_t );
65 static int		ng_ipfw_input(struct mbuf **, int, struct ip_fw_args *,
66 			    int);
67 
68 /* We have only one node */
69 static node_p	fw_node;
70 
71 /* Netgraph node type descriptor */
72 static struct ng_type ng_ipfw_typestruct = {
73 	.version =	NG_ABI_VERSION,
74 	.name =		NG_IPFW_NODE_TYPE,
75 	.mod_event =	ng_ipfw_mod_event,
76 	.constructor =	ng_ipfw_constructor,
77 	.shutdown =	ng_ipfw_shutdown,
78 	.newhook =	ng_ipfw_newhook,
79 	.connect =	ng_ipfw_connect,
80 	.findhook =	ng_ipfw_findhook,
81 	.rcvdata =	ng_ipfw_rcvdata,
82 	.disconnect =	ng_ipfw_disconnect,
83 };
84 NETGRAPH_INIT(ipfw, &ng_ipfw_typestruct);
85 MODULE_DEPEND(ng_ipfw, ipfw, 2, 2, 2);
86 
87 /* Information we store for each hook */
88 struct ng_ipfw_hook_priv {
89         hook_p		hook;
90 	u_int16_t	rulenum;
91 };
92 typedef struct ng_ipfw_hook_priv *hpriv_p;
93 
94 static int
95 ng_ipfw_mod_event(module_t mod, int event, void *data)
96 {
97 	int error = 0;
98 
99 	switch (event) {
100 	case MOD_LOAD:
101 
102 		if (ng_ipfw_input_p != NULL) {
103 			error = EEXIST;
104 			break;
105 		}
106 
107 		/* Setup node without any private data */
108 		if ((error = ng_make_node_common(&ng_ipfw_typestruct, &fw_node))
109 		    != 0) {
110 			log(LOG_ERR, "%s: can't create ng_ipfw node", __func__);
111                 	break;
112 		};
113 
114 		/* Try to name node */
115 		if (ng_name_node(fw_node, "ipfw") != 0)
116 			log(LOG_WARNING, "%s: failed to name node \"ipfw\"",
117 			    __func__);
118 
119 		/* Register hook */
120 		ng_ipfw_input_p = ng_ipfw_input;
121 		break;
122 
123 	case MOD_UNLOAD:
124 		 /*
125 		  * This won't happen if a node exists.
126 		  * ng_ipfw_input_p is already cleared.
127 		  */
128 		break;
129 
130 	default:
131 		error = EOPNOTSUPP;
132 		break;
133 	}
134 
135 	return (error);
136 }
137 
138 static int
139 ng_ipfw_constructor(node_p node)
140 {
141 	return (EINVAL);	/* Only one node */
142 }
143 
144 static int
145 ng_ipfw_newhook(node_p node, hook_p hook, const char *name)
146 {
147 	hpriv_p	hpriv;
148 	u_int16_t rulenum;
149 	const char *cp;
150 	char *endptr;
151 
152 	/* Protect from leading zero */
153 	if (name[0] == '0' && name[1] != '\0')
154 		return (EINVAL);
155 
156 	/* Check that name contains only digits */
157 	for (cp = name; *cp != '\0'; cp++)
158 		if (!isdigit(*cp))
159 			return (EINVAL);
160 
161 	/* Convert it to integer */
162 	rulenum = (u_int16_t)strtol(name, &endptr, 10);
163 	if (*endptr != '\0')
164 		return (EINVAL);
165 
166 	/* Allocate memory for this hook's private data */
167 	hpriv = malloc(sizeof(*hpriv), M_NETGRAPH, M_NOWAIT | M_ZERO);
168 	if (hpriv== NULL)
169 		return (ENOMEM);
170 
171 	hpriv->hook = hook;
172 	hpriv->rulenum = rulenum;
173 
174 	NG_HOOK_SET_PRIVATE(hook, hpriv);
175 
176 	return(0);
177 }
178 
179 /*
180  * Set hooks into queueing mode, to avoid recursion between
181  * netgraph layer and ip_{input,output}.
182  */
183 static int
184 ng_ipfw_connect(hook_p hook)
185 {
186 	NG_HOOK_FORCE_QUEUE(hook);
187 	return (0);
188 }
189 
190 /* Look up hook by name */
191 hook_p
192 ng_ipfw_findhook(node_p node, const char *name)
193 {
194 	u_int16_t n;	/* numeric representation of hook */
195 	char *endptr;
196 
197 	n = (u_int16_t)strtol(name, &endptr, 10);
198 	if (*endptr != '\0')
199 		return NULL;
200 	return ng_ipfw_findhook1(node, n);
201 }
202 
203 /* Look up hook by rule number */
204 static hook_p
205 ng_ipfw_findhook1(node_p node, u_int16_t rulenum)
206 {
207 	hook_p	hook;
208 	hpriv_p	hpriv;
209 
210 	LIST_FOREACH(hook, &node->nd_hooks, hk_hooks) {
211 		hpriv = NG_HOOK_PRIVATE(hook);
212 		if (NG_HOOK_IS_VALID(hook) && (hpriv->rulenum == rulenum))
213                         return (hook);
214 	}
215 
216 	return (NULL);
217 }
218 
219 
220 static int
221 ng_ipfw_rcvdata(hook_p hook, item_p item)
222 {
223 	struct ng_ipfw_tag	*ngit;
224 	struct mbuf *m;
225 
226 	NGI_GET_M(item, m);
227 	NG_FREE_ITEM(item);
228 
229 	if ((ngit = (struct ng_ipfw_tag *)m_tag_locate(m, NGM_IPFW_COOKIE, 0,
230 	    NULL)) == NULL) {
231 		NG_FREE_M(m);
232 		return (EINVAL);	/* XXX: find smth better */
233 	};
234 
235 	switch (ngit->dir) {
236 	case NG_IPFW_OUT:
237 	    {
238 		struct ip *ip;
239 
240 		if (m->m_len < sizeof(struct ip) &&
241 		    (m = m_pullup(m, sizeof(struct ip))) == NULL)
242 			return (EINVAL);
243 
244 		ip = mtod(m, struct ip *);
245 
246 		ip->ip_len = ntohs(ip->ip_len);
247 		ip->ip_off = ntohs(ip->ip_off);
248 
249 		return ip_output(m, NULL, NULL, IP_FORWARDING, NULL, NULL);
250 	    }
251 	case NG_IPFW_IN:
252 		ip_input(m);
253 		return (0);
254 	default:
255 		panic("ng_ipfw_rcvdata: bad dir %u", ngit->dir);
256 	}
257 
258 	/* not reached */
259 	return (0);
260 }
261 
262 static int
263 ng_ipfw_input(struct mbuf **m0, int dir, struct ip_fw_args *fwa, int tee)
264 {
265 	struct mbuf *m;
266 	struct ng_ipfw_tag *ngit;
267 	struct ip *ip;
268 	hook_p	hook;
269 	int error = 0;
270 
271 	/*
272 	 * Node must be loaded and corresponding hook must be present.
273 	 */
274 	if (fw_node == NULL ||
275 	   (hook = ng_ipfw_findhook1(fw_node, fwa->cookie)) == NULL) {
276 		if (tee == 0)
277 			m_freem(*m0);
278 		return (ESRCH);		/* no hook associated with this rule */
279 	}
280 
281 	/*
282 	 * We have two modes: in normal mode we add a tag to packet, which is
283 	 * important to return packet back to IP stack. In tee mode we make
284 	 * a copy of a packet and forward it into netgraph without a tag.
285 	 */
286 	if (tee == 0) {
287 		m = *m0;
288 		*m0 = NULL;	/* it belongs now to netgraph */
289 
290 		if ((ngit = (struct ng_ipfw_tag *)m_tag_alloc(NGM_IPFW_COOKIE,
291 		    0, TAGSIZ, M_NOWAIT|M_ZERO)) == NULL) {
292 			m_freem(m);
293 			return (ENOMEM);
294 		}
295 		ngit->rule = fwa->rule;
296 		ngit->dir = dir;
297 		ngit->ifp = fwa->oif;
298 		m_tag_prepend(m, &ngit->mt);
299 
300 	} else
301 		if ((m = m_dup(*m0, M_DONTWAIT)) == NULL)
302 			return (ENOMEM);	/* which is ignored */
303 
304 	if (m->m_len < sizeof(struct ip) &&
305 	    (m = m_pullup(m, sizeof(struct ip))) == NULL)
306 		return (EINVAL);
307 
308 	ip = mtod(m, struct ip *);
309 	ip->ip_len = htons(ip->ip_len);
310 	ip->ip_off = htons(ip->ip_off);
311 
312 	NG_SEND_DATA_ONLY(error, hook, m);
313 
314 	return (error);
315 }
316 
317 static int
318 ng_ipfw_shutdown(node_p node)
319 {
320 
321 	/*
322 	 * After our single node has been removed,
323 	 * the only thing that can be done is
324 	 * 'kldunload ng_ipfw.ko'
325 	 */
326 	ng_ipfw_input_p = NULL;
327 	NG_NODE_UNREF(node);
328 	return (0);
329 }
330 
331 static int
332 ng_ipfw_disconnect(hook_p hook)
333 {
334 	const hpriv_p hpriv = NG_HOOK_PRIVATE(hook);
335 
336 	free(hpriv, M_NETGRAPH);
337 	NG_HOOK_SET_PRIVATE(hook, NULL);
338 
339 	return (0);
340 }
341