xref: /freebsd/sys/netgraph/ng_ipfw.c (revision 1e413cf93298b5b97441a21d9a50fdcd0ee9945e)
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/mbuf.h>
33 #include <sys/malloc.h>
34 #include <sys/ctype.h>
35 #include <sys/errno.h>
36 #include <sys/socket.h>
37 #include <sys/syslog.h>
38 
39 #include <net/if.h>
40 
41 #include <netinet/in.h>
42 #include <netinet/in_systm.h>
43 #include <netinet/in_var.h>
44 #include <netinet/ip_fw.h>
45 #include <netinet/ip.h>
46 #include <netinet/ip_var.h>
47 
48 #include <netgraph/ng_message.h>
49 #include <netgraph/ng_parse.h>
50 #include <netgraph/ng_ipfw.h>
51 #include <netgraph/netgraph.h>
52 
53 static int		ng_ipfw_mod_event(module_t mod, int event, void *data);
54 static ng_constructor_t	ng_ipfw_constructor;
55 static ng_shutdown_t	ng_ipfw_shutdown;
56 static ng_newhook_t	ng_ipfw_newhook;
57 static ng_connect_t	ng_ipfw_connect;
58 static ng_findhook_t	ng_ipfw_findhook;
59 static ng_rcvdata_t	ng_ipfw_rcvdata;
60 static ng_disconnect_t	ng_ipfw_disconnect;
61 
62 static hook_p		ng_ipfw_findhook1(node_p, u_int16_t );
63 static int		ng_ipfw_input(struct mbuf **, int, struct ip_fw_args *,
64 			    int);
65 
66 /* We have only one node */
67 static node_p	fw_node;
68 
69 /* Netgraph node type descriptor */
70 static struct ng_type ng_ipfw_typestruct = {
71 	.version =	NG_ABI_VERSION,
72 	.name =		NG_IPFW_NODE_TYPE,
73 	.mod_event =	ng_ipfw_mod_event,
74 	.constructor =	ng_ipfw_constructor,
75 	.shutdown =	ng_ipfw_shutdown,
76 	.newhook =	ng_ipfw_newhook,
77 	.connect =	ng_ipfw_connect,
78 	.findhook =	ng_ipfw_findhook,
79 	.rcvdata =	ng_ipfw_rcvdata,
80 	.disconnect =	ng_ipfw_disconnect,
81 };
82 NETGRAPH_INIT(ipfw, &ng_ipfw_typestruct);
83 MODULE_DEPEND(ng_ipfw, ipfw, 2, 2, 2);
84 
85 /* Information we store for each hook */
86 struct ng_ipfw_hook_priv {
87         hook_p		hook;
88 	u_int16_t	rulenum;
89 };
90 typedef struct ng_ipfw_hook_priv *hpriv_p;
91 
92 static int
93 ng_ipfw_mod_event(module_t mod, int event, void *data)
94 {
95 	int error = 0;
96 
97 	switch (event) {
98 	case MOD_LOAD:
99 
100 		if (ng_ipfw_input_p != NULL) {
101 			error = EEXIST;
102 			break;
103 		}
104 
105 		/* Setup node without any private data */
106 		if ((error = ng_make_node_common(&ng_ipfw_typestruct, &fw_node))
107 		    != 0) {
108 			log(LOG_ERR, "%s: can't create ng_ipfw node", __func__);
109                 	break;
110 		};
111 
112 		/* Try to name node */
113 		if (ng_name_node(fw_node, "ipfw") != 0)
114 			log(LOG_WARNING, "%s: failed to name node \"ipfw\"",
115 			    __func__);
116 
117 		/* Register hook */
118 		ng_ipfw_input_p = ng_ipfw_input;
119 		break;
120 
121 	case MOD_UNLOAD:
122 		 /*
123 		  * This won't happen if a node exists.
124 		  * ng_ipfw_input_p is already cleared.
125 		  */
126 		break;
127 
128 	default:
129 		error = EOPNOTSUPP;
130 		break;
131 	}
132 
133 	return (error);
134 }
135 
136 static int
137 ng_ipfw_constructor(node_p node)
138 {
139 	return (EINVAL);	/* Only one node */
140 }
141 
142 static int
143 ng_ipfw_newhook(node_p node, hook_p hook, const char *name)
144 {
145 	hpriv_p	hpriv;
146 	u_int16_t rulenum;
147 	const char *cp;
148 	char *endptr;
149 
150 	/* Protect from leading zero */
151 	if (name[0] == '0' && name[1] != '\0')
152 		return (EINVAL);
153 
154 	/* Check that name contains only digits */
155 	for (cp = name; *cp != '\0'; cp++)
156 		if (!isdigit(*cp))
157 			return (EINVAL);
158 
159 	/* Convert it to integer */
160 	rulenum = (u_int16_t)strtol(name, &endptr, 10);
161 	if (*endptr != '\0')
162 		return (EINVAL);
163 
164 	/* Allocate memory for this hook's private data */
165 	MALLOC(hpriv, hpriv_p, sizeof(*hpriv), M_NETGRAPH, M_NOWAIT | M_ZERO);
166 	if (hpriv== NULL)
167 		return (ENOMEM);
168 
169 	hpriv->hook = hook;
170 	hpriv->rulenum = rulenum;
171 
172 	NG_HOOK_SET_PRIVATE(hook, hpriv);
173 
174 	return(0);
175 }
176 
177 /*
178  * Set hooks into queueing mode, to avoid recursion between
179  * netgraph layer and ip_{input,output}.
180  */
181 static int
182 ng_ipfw_connect(hook_p hook)
183 {
184 	NG_HOOK_FORCE_QUEUE(hook);
185 	return (0);
186 }
187 
188 /* Look up hook by name */
189 hook_p
190 ng_ipfw_findhook(node_p node, const char *name)
191 {
192 	u_int16_t n;	/* numeric representation of hook */
193 	char *endptr;
194 
195 	n = (u_int16_t)strtol(name, &endptr, 10);
196 	if (*endptr != '\0')
197 		return NULL;
198 	return ng_ipfw_findhook1(node, n);
199 }
200 
201 /* Look up hook by rule number */
202 static hook_p
203 ng_ipfw_findhook1(node_p node, u_int16_t rulenum)
204 {
205 	hook_p	hook;
206 	hpriv_p	hpriv;
207 
208 	LIST_FOREACH(hook, &node->nd_hooks, hk_hooks) {
209 		hpriv = NG_HOOK_PRIVATE(hook);
210 		if (NG_HOOK_IS_VALID(hook) && (hpriv->rulenum == rulenum))
211                         return (hook);
212 	}
213 
214 	return (NULL);
215 }
216 
217 
218 static int
219 ng_ipfw_rcvdata(hook_p hook, item_p item)
220 {
221 	struct ng_ipfw_tag	*ngit;
222 	struct mbuf *m;
223 
224 	NGI_GET_M(item, m);
225 	NG_FREE_ITEM(item);
226 
227 	if ((ngit = (struct ng_ipfw_tag *)m_tag_locate(m, NGM_IPFW_COOKIE, 0,
228 	    NULL)) == NULL) {
229 		NG_FREE_M(m);
230 		return (EINVAL);	/* XXX: find smth better */
231 	};
232 
233 	switch (ngit->dir) {
234 	case NG_IPFW_OUT:
235 	    {
236 		struct ip *ip;
237 
238 		if (m->m_len < sizeof(struct ip) &&
239 		    (m = m_pullup(m, sizeof(struct ip))) == NULL)
240 			return (EINVAL);
241 
242 		ip = mtod(m, struct ip *);
243 
244 		ip->ip_len = ntohs(ip->ip_len);
245 		ip->ip_off = ntohs(ip->ip_off);
246 
247 		return ip_output(m, NULL, NULL, IP_FORWARDING, NULL, NULL);
248 	    }
249 	case NG_IPFW_IN:
250 		ip_input(m);
251 		return (0);
252 	default:
253 		panic("ng_ipfw_rcvdata: bad dir %u", ngit->dir);
254 	}
255 
256 	/* not reached */
257 	return (0);
258 }
259 
260 static int
261 ng_ipfw_input(struct mbuf **m0, int dir, struct ip_fw_args *fwa, int tee)
262 {
263 	struct mbuf *m;
264 	struct ng_ipfw_tag *ngit;
265 	struct ip *ip;
266 	hook_p	hook;
267 	int error = 0;
268 
269 	/*
270 	 * Node must be loaded and corresponding hook must be present.
271 	 */
272 	if (fw_node == NULL ||
273 	   (hook = ng_ipfw_findhook1(fw_node, fwa->cookie)) == NULL) {
274 		if (tee == 0)
275 			m_freem(*m0);
276 		return (ESRCH);		/* no hook associated with this rule */
277 	}
278 
279 	/*
280 	 * We have two modes: in normal mode we add a tag to packet, which is
281 	 * important to return packet back to IP stack. In tee mode we make
282 	 * a copy of a packet and forward it into netgraph without a tag.
283 	 */
284 	if (tee == 0) {
285 		m = *m0;
286 		*m0 = NULL;	/* it belongs now to netgraph */
287 
288 		if ((ngit = (struct ng_ipfw_tag *)m_tag_alloc(NGM_IPFW_COOKIE,
289 		    0, TAGSIZ, M_NOWAIT|M_ZERO)) == NULL) {
290 			m_freem(m);
291 			return (ENOMEM);
292 		}
293 		ngit->rule = fwa->rule;
294 		ngit->dir = dir;
295 		ngit->ifp = fwa->oif;
296 		m_tag_prepend(m, &ngit->mt);
297 
298 	} else
299 		if ((m = m_dup(*m0, M_DONTWAIT)) == NULL)
300 			return (ENOMEM);	/* which is ignored */
301 
302 	if (m->m_len < sizeof(struct ip) &&
303 	    (m = m_pullup(m, sizeof(struct ip))) == NULL)
304 		return (EINVAL);
305 
306 	ip = mtod(m, struct ip *);
307 	ip->ip_len = htons(ip->ip_len);
308 	ip->ip_off = htons(ip->ip_off);
309 
310 	NG_SEND_DATA_ONLY(error, hook, m);
311 
312 	return (error);
313 }
314 
315 static int
316 ng_ipfw_shutdown(node_p node)
317 {
318 
319 	/*
320 	 * After our single node has been removed,
321 	 * the only thing that can be done is
322 	 * 'kldunload ng_ipfw.ko'
323 	 */
324 	ng_ipfw_input_p = NULL;
325 	NG_NODE_UNREF(node);
326 	return (0);
327 }
328 
329 static int
330 ng_ipfw_disconnect(hook_p hook)
331 {
332 	const hpriv_p hpriv = NG_HOOK_PRIVATE(hook);
333 
334 	FREE(hpriv, M_NETGRAPH);
335 	NG_HOOK_SET_PRIVATE(hook, NULL);
336 
337 	return (0);
338 }
339