1 /*
2 * Copyright (c) 1982, 1986, 1988, 1993
3 * The Regents of the University of California. 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 * 3. All advertising materials mentioning features or use of this software
14 * must display the following acknowledgement:
15 * This product includes software developed by the University of
16 * California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 *
33 * $FreeBSD: releng/5.1/sys/netinet/ip_divert.c 113255 2003-04-08 14:25:47Z des $
34 */
35
36 #include "opt_inet.h"
37 #include "opt_ipfw.h"
38 #include "opt_ipdivert.h"
39 #include "opt_ipsec.h"
40 #include "opt_mac.h"
41
42 #ifndef INET
43 #error "IPDIVERT requires INET."
44 #endif
45
46 #include <sys/param.h>
47 #include <sys/kernel.h>
48 #include <sys/lock.h>
49 #include <sys/malloc.h>
50 #include <sys/mac.h>
51 #include <sys/mbuf.h>
52 #include <sys/proc.h>
53 #include <sys/protosw.h>
54 #include <sys/signalvar.h>
55 #include <sys/socket.h>
56 #include <sys/socketvar.h>
57 #include <sys/sx.h>
58 #include <sys/sysctl.h>
59 #include <sys/systm.h>
60
61 #include <vm/uma.h>
62
63 #include <net/if.h>
64 #include <net/route.h>
65
66 #include <netinet/in.h>
67 #include <netinet/in_pcb.h>
68 #include <netinet/in_systm.h>
69 #include <netinet/in_var.h>
70 #include <netinet/ip.h>
71 #include <netinet/ip_var.h>
72
73 /*
74 * Divert sockets
75 */
76
77 /*
78 * Allocate enough space to hold a full IP packet
79 */
80 #define DIVSNDQ (65536 + 100)
81 #define DIVRCVQ (65536 + 100)
82
83 /*
84 * Divert sockets work in conjunction with ipfw, see the divert(4)
85 * manpage for features.
86 * Internally, packets selected by ipfw in ip_input() or ip_output(),
87 * and never diverted before, are passed to the input queue of the
88 * divert socket with a given 'divert_port' number (as specified in
89 * the matching ipfw rule), and they are tagged with a 16 bit cookie
90 * (representing the rule number of the matching ipfw rule), which
91 * is passed to process reading from the socket.
92 *
93 * Packets written to the divert socket are again tagged with a cookie
94 * (usually the same as above) and a destination address.
95 * If the destination address is INADDR_ANY then the packet is
96 * treated as outgoing and sent to ip_output(), otherwise it is
97 * treated as incoming and sent to ip_input().
98 * In both cases, the packet is tagged with the cookie.
99 *
100 * On reinjection, processing in ip_input() and ip_output()
101 * will be exactly the same as for the original packet, except that
102 * ipfw processing will start at the rule number after the one
103 * written in the cookie (so, tagging a packet with a cookie of 0
104 * will cause it to be effectively considered as a standard packet).
105 */
106
107 /* Internal variables */
108 static struct inpcbhead divcb;
109 static struct inpcbinfo divcbinfo;
110
111 static u_long div_sendspace = DIVSNDQ; /* XXX sysctl ? */
112 static u_long div_recvspace = DIVRCVQ; /* XXX sysctl ? */
113
114 /* Optimization: have this preinitialized */
115 static struct sockaddr_in divsrc = { sizeof(divsrc), AF_INET };
116
117 /*
118 * Initialize divert connection block queue.
119 */
120 void
121 div_init(void)
122 {
123 INP_INFO_LOCK_INIT(&divcbinfo, "div");
124 LIST_INIT(&divcb);
125 divcbinfo.listhead = &divcb;
126 /*
127 * XXX We don't use the hash list for divert IP, but it's easier
128 * to allocate a one entry hash list than it is to check all
129 * over the place for hashbase == NULL.
130 */
131 divcbinfo.hashbase = hashinit(1, M_PCB, &divcbinfo.hashmask);
132 divcbinfo.porthashbase = hashinit(1, M_PCB, &divcbinfo.porthashmask);
133 divcbinfo.ipi_zone = uma_zcreate("divcb", sizeof(struct inpcb),
134 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
135 uma_zone_set_max(divcbinfo.ipi_zone, maxsockets);
136 }
137
138 /*
139 * IPPROTO_DIVERT is not in the real IP protocol number space; this
140 * function should never be called. Just in case, drop any packets.
141 */
142 void
143 div_input(struct mbuf *m, int off)
144 {
145 ipstat.ips_noproto++;
146 m_freem(m);
147 }
148
149 /*
150 * Divert a packet by passing it up to the divert socket at port 'port'.
151 *
152 * Setup generic address and protocol structures for div_input routine,
153 * then pass them along with mbuf chain.
154 */
155 void
156 divert_packet(struct mbuf *m, int incoming, int port, int rule)
157 {
158 struct ip *ip;
159 struct inpcb *inp;
160 struct socket *sa;
161 u_int16_t nport;
162
163 /* Sanity check */
164 KASSERT(port != 0, ("%s: port=0", __func__));
165
166 divsrc.sin_port = rule; /* record matching rule */
167
168 /* Assure header */
169 if (m->m_len < sizeof(struct ip) &&
170 (m = m_pullup(m, sizeof(struct ip))) == 0)
171 return;
172 ip = mtod(m, struct ip *);
173
174 /*
175 * Record receive interface address, if any.
176 * But only for incoming packets.
177 */
178 divsrc.sin_addr.s_addr = 0;
179 if (incoming) {
180 struct ifaddr *ifa;
181
182 /* Sanity check */
183 M_ASSERTPKTHDR(m);
184
185 /* Find IP address for receive interface */
186 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) {
187 if (ifa->ifa_addr == NULL)
188 continue;
189 if (ifa->ifa_addr->sa_family != AF_INET)
190 continue;
191 divsrc.sin_addr =
192 ((struct sockaddr_in *) ifa->ifa_addr)->sin_addr;
193 break;
194 }
195 }
196 /*
197 * Record the incoming interface name whenever we have one.
198 */
199 bzero(&divsrc.sin_zero, sizeof(divsrc.sin_zero));
200 if (m->m_pkthdr.rcvif) {
201 /*
202 * Hide the actual interface name in there in the
203 * sin_zero array. XXX This needs to be moved to a
204 * different sockaddr type for divert, e.g.
205 * sockaddr_div with multiple fields like
206 * sockaddr_dl. Presently we have only 7 bytes
207 * but that will do for now as most interfaces
208 * are 4 or less + 2 or less bytes for unit.
209 * There is probably a faster way of doing this,
210 * possibly taking it from the sockaddr_dl on the iface.
211 * This solves the problem of a P2P link and a LAN interface
212 * having the same address, which can result in the wrong
213 * interface being assigned to the packet when fed back
214 * into the divert socket. Theoretically if the daemon saves
215 * and re-uses the sockaddr_in as suggested in the man pages,
216 * this iface name will come along for the ride.
217 * (see div_output for the other half of this.)
218 */
219 snprintf(divsrc.sin_zero, sizeof(divsrc.sin_zero),
220 "%s%d", m->m_pkthdr.rcvif->if_name,
221 m->m_pkthdr.rcvif->if_unit);
222 }
223
224 /* Put packet on socket queue, if any */
225 sa = NULL;
226 nport = htons((u_int16_t)port);
227 LIST_FOREACH(inp, &divcb, inp_list) {
228 if (inp->inp_lport == nport)
229 sa = inp->inp_socket;
230 }
231 if (sa) {
232 if (sbappendaddr(&sa->so_rcv, (struct sockaddr *)&divsrc,
233 m, (struct mbuf *)0) == 0)
234 m_freem(m);
235 else
236 sorwakeup(sa);
237 } else {
238 m_freem(m);
239 ipstat.ips_noproto++;
240 ipstat.ips_delivered--;
241 }
242 }
243
244 /*
245 * Deliver packet back into the IP processing machinery.
246 *
247 * If no address specified, or address is 0.0.0.0, send to ip_output();
248 * otherwise, send to ip_input() and mark as having been received on
249 * the interface with that address.
250 */
251 static int
252 div_output(struct socket *so, struct mbuf *m,
253 struct sockaddr_in *sin, struct mbuf *control)
254 {
255 int error = 0;
256 struct m_hdr divert_tag;
257
258 /*
259 * Prepare the tag for divert info. Note that a packet
260 * with a 0 tag in mh_data is effectively untagged,
261 * so we could optimize that case.
262 */
263 divert_tag.mh_type = MT_TAG;
264 divert_tag.mh_flags = PACKET_TAG_DIVERT;
265 divert_tag.mh_next = m;
266 divert_tag.mh_data = 0; /* the matching rule # */
267 m->m_pkthdr.rcvif = NULL; /* XXX is it necessary ? */
268
269 #ifdef MAC
270 mac_create_mbuf_from_socket(so, m);
271 #endif
272
273 if (control)
274 m_freem(control); /* XXX */
275
276 /* Loopback avoidance and state recovery */
277 if (sin) {
278 int i;
279
280 divert_tag.mh_data = (caddr_t)(uintptr_t)sin->sin_port;
281 /*
282 * Find receive interface with the given name, stuffed
283 * (if it exists) in the sin_zero[] field.
284 * The name is user supplied data so don't trust its size
285 * or that it is zero terminated.
286 */
287 for (i = 0; i < sizeof(sin->sin_zero) && sin->sin_zero[i]; i++)
288 ;
289 if ( i > 0 && i < sizeof(sin->sin_zero))
290 m->m_pkthdr.rcvif = ifunit(sin->sin_zero);
291 }
292
293 /* Reinject packet into the system as incoming or outgoing */
294 if (!sin || sin->sin_addr.s_addr == 0) {
295 struct inpcb *const inp = sotoinpcb(so);
296 struct ip *const ip = mtod(m, struct ip *);
297
298 /*
299 * Don't allow both user specified and setsockopt options,
300 * and don't allow packet length sizes that will crash
301 */
302 if (((ip->ip_hl != (sizeof (*ip) >> 2)) && inp->inp_options) ||
303 ((u_short)ntohs(ip->ip_len) > m->m_pkthdr.len)) {
304 error = EINVAL;
305 goto cantsend;
306 }
307
308 /* Convert fields to host order for ip_output() */
309 ip->ip_len = ntohs(ip->ip_len);
310 ip->ip_off = ntohs(ip->ip_off);
311
312 /* Send packet to output processing */
313 ipstat.ips_rawout++; /* XXX */
314 error = ip_output((struct mbuf *)&divert_tag,
315 inp->inp_options, &inp->inp_route,
316 (so->so_options & SO_DONTROUTE) |
317 IP_ALLOWBROADCAST | IP_RAWOUTPUT,
318 inp->inp_moptions, NULL);
319 } else {
320 if (m->m_pkthdr.rcvif == NULL) {
321 /*
322 * No luck with the name, check by IP address.
323 * Clear the port and the ifname to make sure
324 * there are no distractions for ifa_ifwithaddr.
325 */
326 struct ifaddr *ifa;
327
328 bzero(sin->sin_zero, sizeof(sin->sin_zero));
329 sin->sin_port = 0;
330 ifa = ifa_ifwithaddr((struct sockaddr *) sin);
331 if (ifa == NULL) {
332 error = EADDRNOTAVAIL;
333 goto cantsend;
334 }
335 m->m_pkthdr.rcvif = ifa->ifa_ifp;
336 }
337 /* Send packet to input processing */
338 ip_input((struct mbuf *)&divert_tag);
339 }
340
341 return error;
342
343 cantsend:
344 m_freem(m);
345 return error;
346 }
347
348 static int
349 div_attach(struct socket *so, int proto, struct thread *td)
350 {
351 struct inpcb *inp;
352 int error, s;
353
354 inp = sotoinpcb(so);
355 if (inp)
356 panic("div_attach");
357 if (td && (error = suser(td)) != 0)
358 return error;
359
360 error = soreserve(so, div_sendspace, div_recvspace);
361 if (error)
362 return error;
363 s = splnet();
364 error = in_pcballoc(so, &divcbinfo, td);
365 splx(s);
366 if (error)
367 return error;
368 inp = (struct inpcb *)so->so_pcb;
369 inp->inp_ip_p = proto;
370 inp->inp_vflag |= INP_IPV4;
371 inp->inp_flags |= INP_HDRINCL;
372 /* The socket is always "connected" because
373 we always know "where" to send the packet */
374 so->so_state |= SS_ISCONNECTED;
375 return 0;
376 }
377
378 static int
379 div_detach(struct socket *so)
380 {
381 struct inpcb *inp;
382
383 inp = sotoinpcb(so);
384 if (inp == 0)
385 panic("div_detach");
386 in_pcbdetach(inp);
387 return 0;
388 }
389
390 static int
391 div_abort(struct socket *so)
392 {
393 soisdisconnected(so);
394 return div_detach(so);
395 }
396
397 static int
398 div_disconnect(struct socket *so)
399 {
400 if ((so->so_state & SS_ISCONNECTED) == 0)
401 return ENOTCONN;
402 return div_abort(so);
403 }
404
405 static int
406 div_bind(struct socket *so, struct sockaddr *nam, struct thread *td)
407 {
408 struct inpcb *inp;
409 int s;
410 int error;
411
412 s = splnet();
413 inp = sotoinpcb(so);
414 /* in_pcbbind assumes that nam is a sockaddr_in
415 * and in_pcbbind requires a valid address. Since divert
416 * sockets don't we need to make sure the address is
417 * filled in properly.
418 * XXX -- divert should not be abusing in_pcbind
419 * and should probably have its own family.
420 */
421 if (nam->sa_family != AF_INET)
422 error = EAFNOSUPPORT;
423 else {
424 ((struct sockaddr_in *)nam)->sin_addr.s_addr = INADDR_ANY;
425 error = in_pcbbind(inp, nam, td);
426 }
427 splx(s);
428 return error;
429 }
430
431 static int
432 div_shutdown(struct socket *so)
433 {
434 socantsendmore(so);
435 return 0;
436 }
437
438 static int
439 div_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *nam,
440 struct mbuf *control, struct thread *td)
441 {
442 /* Packet must have a header (but that's about it) */
443 if (m->m_len < sizeof (struct ip) &&
444 (m = m_pullup(m, sizeof (struct ip))) == 0) {
445 ipstat.ips_toosmall++;
446 m_freem(m);
447 return EINVAL;
448 }
449
450 /* Send packet */
451 return div_output(so, m, (struct sockaddr_in *)nam, control);
452 }
453
454 static int
455 div_pcblist(SYSCTL_HANDLER_ARGS)
456 {
457 int error, i, n, s;
458 struct inpcb *inp, **inp_list;
459 inp_gen_t gencnt;
460 struct xinpgen xig;
461
462 /*
463 * The process of preparing the TCB list is too time-consuming and
464 * resource-intensive to repeat twice on every request.
465 */
466 if (req->oldptr == 0) {
467 n = divcbinfo.ipi_count;
468 req->oldidx = 2 * (sizeof xig)
469 + (n + n/8) * sizeof(struct xinpcb);
470 return 0;
471 }
472
473 if (req->newptr != 0)
474 return EPERM;
475
476 /*
477 * OK, now we're committed to doing something.
478 */
479 s = splnet();
480 gencnt = divcbinfo.ipi_gencnt;
481 n = divcbinfo.ipi_count;
482 splx(s);
483
484 xig.xig_len = sizeof xig;
485 xig.xig_count = n;
486 xig.xig_gen = gencnt;
487 xig.xig_sogen = so_gencnt;
488 error = SYSCTL_OUT(req, &xig, sizeof xig);
489 if (error)
490 return error;
491
492 inp_list = malloc(n * sizeof *inp_list, M_TEMP, M_WAITOK);
493 if (inp_list == 0)
494 return ENOMEM;
495
496 s = splnet();
497 for (inp = LIST_FIRST(divcbinfo.listhead), i = 0; inp && i < n;
498 inp = LIST_NEXT(inp, inp_list)) {
499 if (inp->inp_gencnt <= gencnt && !prison_xinpcb(req->td, inp))
500 inp_list[i++] = inp;
501 }
502 splx(s);
503 n = i;
504
505 error = 0;
506 for (i = 0; i < n; i++) {
507 inp = inp_list[i];
508 if (inp->inp_gencnt <= gencnt) {
509 struct xinpcb xi;
510 xi.xi_len = sizeof xi;
511 /* XXX should avoid extra copy */
512 bcopy(inp, &xi.xi_inp, sizeof *inp);
513 if (inp->inp_socket)
514 sotoxsocket(inp->inp_socket, &xi.xi_socket);
515 error = SYSCTL_OUT(req, &xi, sizeof xi);
516 }
517 }
518 if (!error) {
519 /*
520 * Give the user an updated idea of our state.
521 * If the generation differs from what we told
522 * her before, she knows that something happened
523 * while we were processing this request, and it
524 * might be necessary to retry.
525 */
526 s = splnet();
527 xig.xig_gen = divcbinfo.ipi_gencnt;
528 xig.xig_sogen = so_gencnt;
529 xig.xig_count = divcbinfo.ipi_count;
530 splx(s);
531 error = SYSCTL_OUT(req, &xig, sizeof xig);
532 }
533 free(inp_list, M_TEMP);
534 return error;
535 }
536
537 /*
538 * This is the wrapper function for in_setsockaddr. We just pass down
539 * the pcbinfo for in_setpeeraddr to lock.
540 */
541 static int
542 div_sockaddr(struct socket *so, struct sockaddr **nam)
543 {
544 return (in_setsockaddr(so, nam, &divcbinfo));
545 }
546
547 /*
548 * This is the wrapper function for in_setpeeraddr. We just pass down
549 * the pcbinfo for in_setpeeraddr to lock.
550 */
551 static int
552 div_peeraddr(struct socket *so, struct sockaddr **nam)
553 {
554 return (in_setpeeraddr(so, nam, &divcbinfo));
555 }
556
557
558 SYSCTL_DECL(_net_inet_divert);
559 SYSCTL_PROC(_net_inet_divert, OID_AUTO, pcblist, CTLFLAG_RD, 0, 0,
560 div_pcblist, "S,xinpcb", "List of active divert sockets");
561
562 struct pr_usrreqs div_usrreqs = {
563 div_abort, pru_accept_notsupp, div_attach, div_bind,
564 pru_connect_notsupp, pru_connect2_notsupp, in_control, div_detach,
565 div_disconnect, pru_listen_notsupp, div_peeraddr, pru_rcvd_notsupp,
566 pru_rcvoob_notsupp, div_send, pru_sense_null, div_shutdown,
567 div_sockaddr, sosend, soreceive, sopoll
568 };
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