ip_proxy.c revision 80482 
1/*
2 * Copyright (C) 1997-2001 by Darren Reed.
3 *
4 * See the IPFILTER.LICENCE file for details on licencing.
5 */
6
7#if defined(__FreeBSD__) && defined(KERNEL) && !defined(_KERNEL)
8# define	_KERNEL
9#endif
10
11#include <sys/errno.h>
12#include <sys/types.h>
13#include <sys/param.h>
14#include <sys/time.h>
15#include <sys/file.h>
16#if !defined(__FreeBSD_version)
17# include <sys/ioctl.h>
18#endif
19#include <sys/fcntl.h>
20#include <sys/uio.h>
21#if !defined(_KERNEL) && !defined(KERNEL)
22# include <stdio.h>
23# include <string.h>
24# include <stdlib.h>
25#endif
26#ifndef	linux
27# include <sys/protosw.h>
28#endif
29#include <sys/socket.h>
30#if defined(_KERNEL)
31# if !defined(linux)
32#  include <sys/systm.h>
33# else
34#  include <linux/string.h>
35# endif
36#endif
37#if !defined(__SVR4) && !defined(__svr4__)
38# ifndef linux
39#  include <sys/mbuf.h>
40# endif
41#else
42# include <sys/byteorder.h>
43# ifdef _KERNEL
44#  include <sys/dditypes.h>
45# endif
46# include <sys/stream.h>
47# include <sys/kmem.h>
48#endif
49#if __FreeBSD__ > 2
50# include <sys/queue.h>
51#endif
52#include <net/if.h>
53#ifdef sun
54# include <net/af.h>
55#endif
56#include <net/route.h>
57#include <netinet/in.h>
58#include <netinet/in_systm.h>
59#include <netinet/ip.h>
60#ifndef linux
61# include <netinet/ip_var.h>
62#endif
63#include <netinet/tcp.h>
64#include <netinet/udp.h>
65#include <netinet/ip_icmp.h>
66#include "netinet/ip_compat.h"
67#include <netinet/tcpip.h>
68#include "netinet/ip_fil.h"
69#include "netinet/ip_proxy.h"
70#include "netinet/ip_nat.h"
71#include "netinet/ip_state.h"
72#if (__FreeBSD_version >= 300000)
73# include <sys/malloc.h>
74#endif
75
76#if !defined(lint)
77/* static const char rcsid[] = "@(#)$Id: ip_proxy.c,v 2.9.2.6 2001/07/15 22:06:15 darrenr Exp $"; */
78static const char rcsid[] = "@(#)$FreeBSD: head/sys/contrib/ipfilter/netinet/ip_proxy.c 80482 2001-07-28 11:58:26Z darrenr $";
79#endif
80
81
82#ifndef MIN
83#define MIN(a,b)        (((a)<(b))?(a):(b))
84#endif
85
86static ap_session_t *appr_new_session __P((aproxy_t *, ip_t *,
87					   fr_info_t *, nat_t *));
88static int appr_fixseqack __P((fr_info_t *, ip_t *, ap_session_t *, int ));
89
90
91#define	AP_SESS_SIZE	53
92
93#if defined(_KERNEL) && !defined(linux)
94#include "netinet/ip_ftp_pxy.c"
95#include "netinet/ip_rcmd_pxy.c"
96#include "netinet/ip_raudio_pxy.c"
97#endif
98
99ap_session_t	*ap_sess_tab[AP_SESS_SIZE];
100ap_session_t	*ap_sess_list = NULL;
101aproxy_t	*ap_proxylist = NULL;
102aproxy_t	ap_proxies[] = {
103#ifdef	IPF_FTP_PROXY
104	{ NULL, "ftp", (char)IPPROTO_TCP, 0, 0, ippr_ftp_init, NULL,
105	  ippr_ftp_new, ippr_ftp_in, ippr_ftp_out },
106#endif
107#ifdef	IPF_RCMD_PROXY
108	{ NULL, "rcmd", (char)IPPROTO_TCP, 0, 0, ippr_rcmd_init, NULL,
109	  ippr_rcmd_new, NULL, ippr_rcmd_out },
110#endif
111#ifdef	IPF_RAUDIO_PROXY
112	{ NULL, "raudio", (char)IPPROTO_TCP, 0, 0, ippr_raudio_init, NULL,
113	  ippr_raudio_new, ippr_raudio_in, ippr_raudio_out },
114#endif
115	{ NULL, "", '\0', 0, 0, NULL, NULL }
116};
117
118
119int appr_add(ap)
120aproxy_t *ap;
121{
122	aproxy_t *a;
123
124	for (a = ap_proxies; a->apr_p; a++)
125		if ((a->apr_p == ap->apr_p) &&
126		    !strncmp(a->apr_label, ap->apr_label,
127			     sizeof(ap->apr_label)))
128			return -1;
129
130	for (a = ap_proxylist; a->apr_p; a = a->apr_next)
131		if ((a->apr_p == ap->apr_p) &&
132		    !strncmp(a->apr_label, ap->apr_label,
133			     sizeof(ap->apr_label)))
134			return -1;
135	ap->apr_next = ap_proxylist;
136	ap_proxylist = ap;
137	return (*ap->apr_init)();
138}
139
140
141int appr_del(ap)
142aproxy_t *ap;
143{
144	aproxy_t *a, **app;
145
146	for (app = &ap_proxylist; (a = *app); app = &a->apr_next)
147		if (a == ap) {
148			if (ap->apr_ref != 0)
149				return 1;
150			*app = a->apr_next;
151			return 0;
152		}
153	return -1;
154}
155
156
157int appr_ok(ip, tcp, nat)
158ip_t *ip;
159tcphdr_t *tcp;
160ipnat_t *nat;
161{
162	aproxy_t *apr = nat->in_apr;
163	u_short dport = nat->in_dport;
164
165	if (!apr || (apr->apr_flags & APR_DELETE) ||
166	    (ip->ip_p != apr->apr_p))
167		return 0;
168	if ((tcp && (tcp->th_dport != dport)) || (!tcp && dport))
169		return 0;
170	return 1;
171}
172
173
174/*
175 * Allocate a new application proxy structure and fill it in with the
176 * relevant details.  call the init function once complete, prior to
177 * returning.
178 */
179static ap_session_t *appr_new_session(apr, ip, fin, nat)
180aproxy_t *apr;
181ip_t *ip;
182fr_info_t *fin;
183nat_t *nat;
184{
185	register ap_session_t *aps;
186
187	if (!apr || (apr->apr_flags & APR_DELETE) || (ip->ip_p != apr->apr_p))
188		return NULL;
189
190	KMALLOC(aps, ap_session_t *);
191	if (!aps)
192		return NULL;
193	bzero((char *)aps, sizeof(*aps));
194	aps->aps_p = ip->ip_p;
195	aps->aps_data = NULL;
196	aps->aps_apr = apr;
197	aps->aps_psiz = 0;
198	if (apr->apr_new != NULL)
199		if ((*apr->apr_new)(fin, ip, aps, nat) == -1) {
200			KFREE(aps);
201			return NULL;
202		}
203	aps->aps_nat = nat;
204	aps->aps_next = ap_sess_list;
205	ap_sess_list = aps;
206	return aps;
207}
208
209
210/*
211 * check to see if a packet should be passed through an active proxy routine
212 * if one has been setup for it.
213 */
214int appr_check(ip, fin, nat)
215ip_t *ip;
216fr_info_t *fin;
217nat_t *nat;
218{
219#if SOLARIS && defined(_KERNEL) && (SOLARIS2 >= 6)
220	mb_t *m = fin->fin_qfm;
221	int dosum = 1;
222#endif
223	tcphdr_t *tcp = NULL;
224	ap_session_t *aps;
225	aproxy_t *apr;
226	u_32_t sum;
227	short rv;
228	int err;
229
230	if (nat->nat_aps == NULL)
231		nat->nat_aps = appr_new_session(nat->nat_ptr->in_apr, ip,
232						fin, nat);
233	aps = nat->nat_aps;
234	if ((aps != NULL) && (aps->aps_p == ip->ip_p)) {
235		if (ip->ip_p == IPPROTO_TCP) {
236			tcp = (tcphdr_t *)fin->fin_dp;
237			/*
238			 * verify that the checksum is correct.  If not, then
239			 * don't do anything with this packet.
240			 */
241#if SOLARIS && defined(_KERNEL) && (SOLARIS2 >= 6)
242			if (dohwcksum && (m->b_ick_flag == ICK_VALID)) {
243				sum = tcp->th_sum;
244				dosum = 0;
245			}
246			if (dosum)
247				sum = fr_tcpsum(fin->fin_qfm, ip, tcp);
248#else
249			sum = fr_tcpsum(*(mb_t **)fin->fin_mp, ip, tcp);
250#endif
251			if (sum != tcp->th_sum) {
252				frstats[fin->fin_out].fr_tcpbad++;
253				return -1;
254			}
255		}
256
257		apr = aps->aps_apr;
258		err = 0;
259		if (fin->fin_out != 0) {
260			if (apr->apr_outpkt != NULL)
261				err = (*apr->apr_outpkt)(fin, ip, aps, nat);
262		} else {
263			if (apr->apr_inpkt != NULL)
264				err = (*apr->apr_inpkt)(fin, ip, aps, nat);
265		}
266
267		rv = APR_EXIT(err);
268		if (rv == -1)
269			return rv;
270
271		if (tcp != NULL) {
272			err = appr_fixseqack(fin, ip, aps, APR_INC(err));
273#if SOLARIS && defined(_KERNEL) && (SOLARIS2 >= 6)
274			if (dosum)
275				tcp->th_sum = fr_tcpsum(fin->fin_qfm, ip, tcp);
276#else
277			tcp->th_sum = fr_tcpsum(*(mb_t **)fin->fin_mp, ip, tcp);
278#endif
279		}
280		aps->aps_bytes += ip->ip_len;
281		aps->aps_pkts++;
282		return 1;
283	}
284	return 0;
285}
286
287
288aproxy_t *appr_match(pr, name)
289u_int pr;
290char *name;
291{
292	aproxy_t *ap;
293
294	for (ap = ap_proxies; ap->apr_p; ap++)
295		if ((ap->apr_p == pr) &&
296		    !strncmp(name, ap->apr_label, sizeof(ap->apr_label))) {
297			ap->apr_ref++;
298			return ap;
299		}
300
301	for (ap = ap_proxylist; ap; ap = ap->apr_next)
302		if ((ap->apr_p == pr) &&
303		    !strncmp(name, ap->apr_label, sizeof(ap->apr_label))) {
304			ap->apr_ref++;
305			return ap;
306		}
307	return NULL;
308}
309
310
311void appr_free(ap)
312aproxy_t *ap;
313{
314	ap->apr_ref--;
315}
316
317
318void aps_free(aps)
319ap_session_t *aps;
320{
321	ap_session_t *a, **ap;
322
323	if (!aps)
324		return;
325
326	for (ap = &ap_sess_list; (a = *ap); ap = &a->aps_next)
327		if (a == aps) {
328			*ap = a->aps_next;
329			break;
330		}
331
332	if ((aps->aps_data != NULL) && (aps->aps_psiz != 0))
333		KFREES(aps->aps_data, aps->aps_psiz);
334	KFREE(aps);
335}
336
337
338static int appr_fixseqack(fin, ip, aps, inc)
339fr_info_t *fin;
340ip_t *ip;
341ap_session_t *aps;
342int inc;
343{
344	int sel, ch = 0, out, nlen;
345	u_32_t seq1, seq2;
346	tcphdr_t *tcp;
347
348	tcp = (tcphdr_t *)fin->fin_dp;
349	out = fin->fin_out;
350	nlen = ip->ip_len;
351	nlen -= (ip->ip_hl << 2) + (tcp->th_off << 2);
352
353	if (out != 0) {
354		seq1 = (u_32_t)ntohl(tcp->th_seq);
355		sel = aps->aps_sel[out];
356
357		/* switch to other set ? */
358		if ((aps->aps_seqmin[!sel] > aps->aps_seqmin[sel]) &&
359		    (seq1 > aps->aps_seqmin[!sel]))
360			sel = aps->aps_sel[out] = !sel;
361
362		if (aps->aps_seqoff[sel]) {
363			seq2 = aps->aps_seqmin[sel] - aps->aps_seqoff[sel];
364			if (seq1 > seq2) {
365				seq2 = aps->aps_seqoff[sel];
366				seq1 += seq2;
367				tcp->th_seq = htonl(seq1);
368				ch = 1;
369			}
370		}
371
372		if (inc && (seq1 > aps->aps_seqmin[!sel])) {
373			aps->aps_seqmin[!sel] = seq1 + nlen - 1;
374			aps->aps_seqoff[!sel] = aps->aps_seqoff[sel] + inc;
375		}
376
377		/***/
378
379		seq1 = ntohl(tcp->th_ack);
380		sel = aps->aps_sel[1 - out];
381
382		/* switch to other set ? */
383		if ((aps->aps_ackmin[!sel] > aps->aps_ackmin[sel]) &&
384		    (seq1 > aps->aps_ackmin[!sel]))
385			sel = aps->aps_sel[1 - out] = !sel;
386
387		if (aps->aps_ackoff[sel] && (seq1 > aps->aps_ackmin[sel])) {
388			seq2 = aps->aps_ackoff[sel];
389			tcp->th_ack = htonl(seq1 - seq2);
390			ch = 1;
391		}
392	} else {
393		seq1 = ntohl(tcp->th_seq);
394		sel = aps->aps_sel[out];
395
396		/* switch to other set ? */
397		if ((aps->aps_ackmin[!sel] > aps->aps_ackmin[sel]) &&
398		    (seq1 > aps->aps_ackmin[!sel]))
399			sel = aps->aps_sel[out] = !sel;
400
401		if (aps->aps_ackoff[sel]) {
402			seq2 = aps->aps_ackmin[sel] -
403			       aps->aps_ackoff[sel];
404			if (seq1 > seq2) {
405				seq2 = aps->aps_ackoff[sel];
406				seq1 += seq2;
407				tcp->th_seq = htonl(seq1);
408				ch = 1;
409			}
410		}
411
412		if (inc && (seq1 > aps->aps_ackmin[!sel])) {
413			aps->aps_ackmin[!sel] = seq1 + nlen - 1;
414			aps->aps_ackoff[!sel] = aps->aps_ackoff[sel] + inc;
415		}
416
417		/***/
418
419		seq1 = ntohl(tcp->th_ack);
420		sel = aps->aps_sel[1 - out];
421
422		/* switch to other set ? */
423		if ((aps->aps_seqmin[!sel] > aps->aps_seqmin[sel]) &&
424		    (seq1 > aps->aps_seqmin[!sel]))
425			sel = aps->aps_sel[1 - out] = !sel;
426
427		if (aps->aps_seqoff[sel] && (seq1 > aps->aps_seqmin[sel])) {
428			seq2 = aps->aps_seqoff[sel];
429			tcp->th_ack = htonl(seq1 - seq2);
430			ch = 1;
431		}
432	}
433	return ch ? 2 : 0;
434}
435
436
437int appr_init()
438{
439	aproxy_t *ap;
440	int err = 0;
441
442	for (ap = ap_proxies; ap->apr_p; ap++) {
443		err = (*ap->apr_init)();
444		if (err != 0)
445			break;
446	}
447	return err;
448}
449
450
451void appr_unload()
452{
453	aproxy_t *ap;
454
455	for (ap = ap_proxies; ap->apr_p; ap++)
456		if (ap->apr_fini)
457			(*ap->apr_fini)();
458	for (ap = ap_proxylist; ap; ap = ap->apr_next)
459		if (ap->apr_fini)
460			(*ap->apr_fini)();
461}
462