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 * 4. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * $FreeBSD: releng/5.4/sys/netinet/ip_divert.c 145955 2005-05-06 02:51:10Z cperciva $
30 */
31
32 #include "opt_inet.h"
33 #include "opt_ipfw.h"
34 #include "opt_ipdivert.h"
35 #include "opt_ipsec.h"
36 #include "opt_mac.h"
37
38 #ifndef INET
39 #error "IPDIVERT requires INET."
40 #endif
41
42 #include <sys/param.h>
43 #include <sys/kernel.h>
44 #include <sys/lock.h>
45 #include <sys/malloc.h>
46 #include <sys/mac.h>
47 #include <sys/mbuf.h>
48 #include <sys/proc.h>
49 #include <sys/protosw.h>
50 #include <sys/signalvar.h>
51 #include <sys/socket.h>
52 #include <sys/socketvar.h>
53 #include <sys/sx.h>
54 #include <sys/sysctl.h>
55 #include <sys/systm.h>
56
57 #include <vm/uma.h>
58
59 #include <net/if.h>
60 #include <net/route.h>
61
62 #include <netinet/in.h>
63 #include <netinet/in_pcb.h>
64 #include <netinet/in_systm.h>
65 #include <netinet/in_var.h>
66 #include <netinet/ip.h>
67 #include <netinet/ip_divert.h>
68 #include <netinet/ip_var.h>
69
70 /*
71 * Divert sockets
72 */
73
74 /*
75 * Allocate enough space to hold a full IP packet
76 */
77 #define DIVSNDQ (65536 + 100)
78 #define DIVRCVQ (65536 + 100)
79
80 /*
81 * Divert sockets work in conjunction with ipfw, see the divert(4)
82 * manpage for features.
83 * Internally, packets selected by ipfw in ip_input() or ip_output(),
84 * and never diverted before, are passed to the input queue of the
85 * divert socket with a given 'divert_port' number (as specified in
86 * the matching ipfw rule), and they are tagged with a 16 bit cookie
87 * (representing the rule number of the matching ipfw rule), which
88 * is passed to process reading from the socket.
89 *
90 * Packets written to the divert socket are again tagged with a cookie
91 * (usually the same as above) and a destination address.
92 * If the destination address is INADDR_ANY then the packet is
93 * treated as outgoing and sent to ip_output(), otherwise it is
94 * treated as incoming and sent to ip_input().
95 * In both cases, the packet is tagged with the cookie.
96 *
97 * On reinjection, processing in ip_input() and ip_output()
98 * will be exactly the same as for the original packet, except that
99 * ipfw processing will start at the rule number after the one
100 * written in the cookie (so, tagging a packet with a cookie of 0
101 * will cause it to be effectively considered as a standard packet).
102 */
103
104 /* Internal variables */
105 static struct inpcbhead divcb;
106 static struct inpcbinfo divcbinfo;
107
108 static u_long div_sendspace = DIVSNDQ; /* XXX sysctl ? */
109 static u_long div_recvspace = DIVRCVQ; /* XXX sysctl ? */
110
111 /*
112 * Initialize divert connection block queue.
113 */
114 void
115 div_init(void)
116 {
117 INP_INFO_LOCK_INIT(&divcbinfo, "div");
118 LIST_INIT(&divcb);
119 divcbinfo.listhead = &divcb;
120 /*
121 * XXX We don't use the hash list for divert IP, but it's easier
122 * to allocate a one entry hash list than it is to check all
123 * over the place for hashbase == NULL.
124 */
125 divcbinfo.hashbase = hashinit(1, M_PCB, &divcbinfo.hashmask);
126 divcbinfo.porthashbase = hashinit(1, M_PCB, &divcbinfo.porthashmask);
127 divcbinfo.ipi_zone = uma_zcreate("divcb", sizeof(struct inpcb),
128 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
129 uma_zone_set_max(divcbinfo.ipi_zone, maxsockets);
130 }
131
132 /*
133 * IPPROTO_DIVERT is not in the real IP protocol number space; this
134 * function should never be called. Just in case, drop any packets.
135 */
136 void
137 div_input(struct mbuf *m, int off)
138 {
139 ipstat.ips_noproto++;
140 m_freem(m);
141 }
142
143 /*
144 * Divert a packet by passing it up to the divert socket at port 'port'.
145 *
146 * Setup generic address and protocol structures for div_input routine,
147 * then pass them along with mbuf chain.
148 */
149 void
150 divert_packet(struct mbuf *m, int incoming)
151 {
152 struct ip *ip;
153 struct inpcb *inp;
154 struct socket *sa;
155 u_int16_t nport;
156 struct sockaddr_in divsrc;
157 struct m_tag *mtag;
158
159 mtag = m_tag_find(m, PACKET_TAG_DIVERT, NULL);
160 if (mtag == NULL) {
161 printf("%s: no divert tag\n", __func__);
162 m_freem(m);
163 return;
164 }
165 /* Assure header */
166 if (m->m_len < sizeof(struct ip) &&
167 (m = m_pullup(m, sizeof(struct ip))) == 0)
168 return;
169 ip = mtod(m, struct ip *);
170
171 /* Delayed checksums are currently not compatible with divert. */
172 if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
173 ip->ip_len = ntohs(ip->ip_len);
174 in_delayed_cksum(m);
175 m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
176 ip->ip_len = htons(ip->ip_len);
177 }
178
179 /*
180 * Record receive interface address, if any.
181 * But only for incoming packets.
182 */
183 bzero(&divsrc, sizeof(divsrc));
184 divsrc.sin_len = sizeof(divsrc);
185 divsrc.sin_family = AF_INET;
186 divsrc.sin_port = divert_cookie(mtag); /* record matching rule */
187 if (incoming) {
188 struct ifaddr *ifa;
189
190 /* Sanity check */
191 M_ASSERTPKTHDR(m);
192
193 /* Find IP address for receive interface */
194 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) {
195 if (ifa->ifa_addr == NULL)
196 continue;
197 if (ifa->ifa_addr->sa_family != AF_INET)
198 continue;
199 divsrc.sin_addr =
200 ((struct sockaddr_in *) ifa->ifa_addr)->sin_addr;
201 break;
202 }
203 }
204 /*
205 * Record the incoming interface name whenever we have one.
206 */
207 if (m->m_pkthdr.rcvif) {
208 /*
209 * Hide the actual interface name in there in the
210 * sin_zero array. XXX This needs to be moved to a
211 * different sockaddr type for divert, e.g.
212 * sockaddr_div with multiple fields like
213 * sockaddr_dl. Presently we have only 7 bytes
214 * but that will do for now as most interfaces
215 * are 4 or less + 2 or less bytes for unit.
216 * There is probably a faster way of doing this,
217 * possibly taking it from the sockaddr_dl on the iface.
218 * This solves the problem of a P2P link and a LAN interface
219 * having the same address, which can result in the wrong
220 * interface being assigned to the packet when fed back
221 * into the divert socket. Theoretically if the daemon saves
222 * and re-uses the sockaddr_in as suggested in the man pages,
223 * this iface name will come along for the ride.
224 * (see div_output for the other half of this.)
225 */
226 strlcpy(divsrc.sin_zero, m->m_pkthdr.rcvif->if_xname,
227 sizeof(divsrc.sin_zero));
228 }
229
230 /* Put packet on socket queue, if any */
231 sa = NULL;
232 nport = htons((u_int16_t)divert_info(mtag));
233 INP_INFO_RLOCK(&divcbinfo);
234 LIST_FOREACH(inp, &divcb, inp_list) {
235 INP_LOCK(inp);
236 /* XXX why does only one socket match? */
237 if (inp->inp_lport == nport) {
238 sa = inp->inp_socket;
239 SOCKBUF_LOCK(&sa->so_rcv);
240 if (sbappendaddr_locked(&sa->so_rcv,
241 (struct sockaddr *)&divsrc, m,
242 (struct mbuf *)0) == 0) {
243 SOCKBUF_UNLOCK(&sa->so_rcv);
244 sa = NULL; /* force mbuf reclaim below */
245 } else
246 sorwakeup_locked(sa);
247 INP_UNLOCK(inp);
248 break;
249 }
250 INP_UNLOCK(inp);
251 }
252 INP_INFO_RUNLOCK(&divcbinfo);
253 if (sa == NULL) {
254 m_freem(m);
255 ipstat.ips_noproto++;
256 ipstat.ips_delivered--;
257 }
258 }
259
260 /*
261 * Deliver packet back into the IP processing machinery.
262 *
263 * If no address specified, or address is 0.0.0.0, send to ip_output();
264 * otherwise, send to ip_input() and mark as having been received on
265 * the interface with that address.
266 */
267 static int
268 div_output(struct socket *so, struct mbuf *m,
269 struct sockaddr_in *sin, struct mbuf *control)
270 {
271 int error = 0;
272
273 m->m_pkthdr.rcvif = NULL;
274
275 if (control)
276 m_freem(control); /* XXX */
277
278 /* Loopback avoidance and state recovery */
279 if (sin) {
280 struct m_tag *mtag;
281 struct divert_tag *dt;
282 int i;
283
284 mtag = m_tag_get(PACKET_TAG_DIVERT,
285 sizeof(struct divert_tag), M_NOWAIT);
286 if (mtag == NULL) {
287 error = ENOBUFS;
288 goto cantsend;
289 }
290 dt = (struct divert_tag *)(mtag+1);
291 dt->info = 0;
292 dt->cookie = sin->sin_port;
293 m_tag_prepend(m, mtag);
294
295 /*
296 * Find receive interface with the given name, stuffed
297 * (if it exists) in the sin_zero[] field.
298 * The name is user supplied data so don't trust its size
299 * or that it is zero terminated.
300 */
301 for (i = 0; i < sizeof(sin->sin_zero) && sin->sin_zero[i]; i++)
302 ;
303 if ( i > 0 && i < sizeof(sin->sin_zero))
304 m->m_pkthdr.rcvif = ifunit(sin->sin_zero);
305 }
306
307 /* Reinject packet into the system as incoming or outgoing */
308 if (!sin || sin->sin_addr.s_addr == 0) {
309 struct ip *const ip = mtod(m, struct ip *);
310 struct inpcb *inp;
311
312 INP_INFO_WLOCK(&divcbinfo);
313 inp = sotoinpcb(so);
314 INP_LOCK(inp);
315 /*
316 * Don't allow both user specified and setsockopt options,
317 * and don't allow packet length sizes that will crash
318 */
319 if (((ip->ip_hl != (sizeof (*ip) >> 2)) && inp->inp_options) ||
320 ((u_short)ntohs(ip->ip_len) > m->m_pkthdr.len)) {
321 error = EINVAL;
322 m_freem(m);
323 } else {
324 /* Convert fields to host order for ip_output() */
325 ip->ip_len = ntohs(ip->ip_len);
326 ip->ip_off = ntohs(ip->ip_off);
327
328 /* Send packet to output processing */
329 ipstat.ips_rawout++; /* XXX */
330
331 #ifdef MAC
332 mac_create_mbuf_from_inpcb(inp, m);
333 #endif
334 error = ip_output(m,
335 inp->inp_options, NULL,
336 (so->so_options & SO_DONTROUTE) |
337 IP_ALLOWBROADCAST | IP_RAWOUTPUT,
338 inp->inp_moptions, NULL);
339 }
340 INP_UNLOCK(inp);
341 INP_INFO_WUNLOCK(&divcbinfo);
342 } else {
343 if (m->m_pkthdr.rcvif == NULL) {
344 /*
345 * No luck with the name, check by IP address.
346 * Clear the port and the ifname to make sure
347 * there are no distractions for ifa_ifwithaddr.
348 */
349 struct ifaddr *ifa;
350
351 bzero(sin->sin_zero, sizeof(sin->sin_zero));
352 sin->sin_port = 0;
353 ifa = ifa_ifwithaddr((struct sockaddr *) sin);
354 if (ifa == NULL) {
355 error = EADDRNOTAVAIL;
356 goto cantsend;
357 }
358 m->m_pkthdr.rcvif = ifa->ifa_ifp;
359 }
360 #ifdef MAC
361 SOCK_LOCK(so);
362 mac_create_mbuf_from_socket(so, m);
363 SOCK_UNLOCK(so);
364 #endif
365 /* Send packet to input processing */
366 ip_input(m);
367 }
368
369 return error;
370
371 cantsend:
372 m_freem(m);
373 return error;
374 }
375
376 static int
377 div_attach(struct socket *so, int proto, struct thread *td)
378 {
379 struct inpcb *inp;
380 int error;
381
382 INP_INFO_WLOCK(&divcbinfo);
383 inp = sotoinpcb(so);
384 if (inp != 0) {
385 INP_INFO_WUNLOCK(&divcbinfo);
386 return EINVAL;
387 }
388 if (td && (error = suser(td)) != 0) {
389 INP_INFO_WUNLOCK(&divcbinfo);
390 return error;
391 }
392 error = soreserve(so, div_sendspace, div_recvspace);
393 if (error) {
394 INP_INFO_WUNLOCK(&divcbinfo);
395 return error;
396 }
397 error = in_pcballoc(so, &divcbinfo, "divinp");
398 if (error) {
399 INP_INFO_WUNLOCK(&divcbinfo);
400 return error;
401 }
402 inp = (struct inpcb *)so->so_pcb;
403 INP_LOCK(inp);
404 INP_INFO_WUNLOCK(&divcbinfo);
405 inp->inp_ip_p = proto;
406 inp->inp_vflag |= INP_IPV4;
407 inp->inp_flags |= INP_HDRINCL;
408 INP_UNLOCK(inp);
409 return 0;
410 }
411
412 static int
413 div_detach(struct socket *so)
414 {
415 struct inpcb *inp;
416
417 INP_INFO_WLOCK(&divcbinfo);
418 inp = sotoinpcb(so);
419 if (inp == 0) {
420 INP_INFO_WUNLOCK(&divcbinfo);
421 return EINVAL;
422 }
423 INP_LOCK(inp);
424 in_pcbdetach(inp);
425 INP_INFO_WUNLOCK(&divcbinfo);
426 return 0;
427 }
428
429 static int
430 div_bind(struct socket *so, struct sockaddr *nam, struct thread *td)
431 {
432 struct inpcb *inp;
433 int error;
434
435 INP_INFO_WLOCK(&divcbinfo);
436 inp = sotoinpcb(so);
437 if (inp == 0) {
438 INP_INFO_WUNLOCK(&divcbinfo);
439 return EINVAL;
440 }
441 /* in_pcbbind assumes that nam is a sockaddr_in
442 * and in_pcbbind requires a valid address. Since divert
443 * sockets don't we need to make sure the address is
444 * filled in properly.
445 * XXX -- divert should not be abusing in_pcbind
446 * and should probably have its own family.
447 */
448 if (nam->sa_family != AF_INET)
449 error = EAFNOSUPPORT;
450 else {
451 ((struct sockaddr_in *)nam)->sin_addr.s_addr = INADDR_ANY;
452 INP_LOCK(inp);
453 error = in_pcbbind(inp, nam, td->td_ucred);
454 INP_UNLOCK(inp);
455 }
456 INP_INFO_WUNLOCK(&divcbinfo);
457 return error;
458 }
459
460 static int
461 div_shutdown(struct socket *so)
462 {
463 struct inpcb *inp;
464
465 INP_INFO_RLOCK(&divcbinfo);
466 inp = sotoinpcb(so);
467 if (inp == 0) {
468 INP_INFO_RUNLOCK(&divcbinfo);
469 return EINVAL;
470 }
471 INP_LOCK(inp);
472 INP_INFO_RUNLOCK(&divcbinfo);
473 socantsendmore(so);
474 INP_UNLOCK(inp);
475 return 0;
476 }
477
478 static int
479 div_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *nam,
480 struct mbuf *control, struct thread *td)
481 {
482 /* Packet must have a header (but that's about it) */
483 if (m->m_len < sizeof (struct ip) &&
484 (m = m_pullup(m, sizeof (struct ip))) == 0) {
485 ipstat.ips_toosmall++;
486 m_freem(m);
487 return EINVAL;
488 }
489
490 /* Send packet */
491 return div_output(so, m, (struct sockaddr_in *)nam, control);
492 }
493
494 void
495 div_ctlinput(int cmd, struct sockaddr *sa, void *vip)
496 {
497 struct in_addr faddr;
498
499 faddr = ((struct sockaddr_in *)sa)->sin_addr;
500 if (sa->sa_family != AF_INET || faddr.s_addr == INADDR_ANY)
501 return;
502 if (PRC_IS_REDIRECT(cmd))
503 return;
504 }
505
506 static int
507 div_pcblist(SYSCTL_HANDLER_ARGS)
508 {
509 int error, i, n;
510 struct inpcb *inp, **inp_list;
511 inp_gen_t gencnt;
512 struct xinpgen xig;
513
514 /*
515 * The process of preparing the TCB list is too time-consuming and
516 * resource-intensive to repeat twice on every request.
517 */
518 if (req->oldptr == 0) {
519 n = divcbinfo.ipi_count;
520 req->oldidx = 2 * (sizeof xig)
521 + (n + n/8) * sizeof(struct xinpcb);
522 return 0;
523 }
524
525 if (req->newptr != 0)
526 return EPERM;
527
528 /*
529 * OK, now we're committed to doing something.
530 */
531 INP_INFO_RLOCK(&divcbinfo);
532 gencnt = divcbinfo.ipi_gencnt;
533 n = divcbinfo.ipi_count;
534 INP_INFO_RUNLOCK(&divcbinfo);
535
536 error = sysctl_wire_old_buffer(req,
537 2 * sizeof(xig) + n*sizeof(struct xinpcb));
538 if (error != 0)
539 return (error);
540
541 xig.xig_len = sizeof xig;
542 xig.xig_count = n;
543 xig.xig_gen = gencnt;
544 xig.xig_sogen = so_gencnt;
545 error = SYSCTL_OUT(req, &xig, sizeof xig);
546 if (error)
547 return error;
548
549 inp_list = malloc(n * sizeof *inp_list, M_TEMP, M_WAITOK);
550 if (inp_list == 0)
551 return ENOMEM;
552
553 INP_INFO_RLOCK(&divcbinfo);
554 for (inp = LIST_FIRST(divcbinfo.listhead), i = 0; inp && i < n;
555 inp = LIST_NEXT(inp, inp_list)) {
556 INP_LOCK(inp);
557 if (inp->inp_gencnt <= gencnt &&
558 cr_canseesocket(req->td->td_ucred, inp->inp_socket) == 0)
559 inp_list[i++] = inp;
560 INP_UNLOCK(inp);
561 }
562 INP_INFO_RUNLOCK(&divcbinfo);
563 n = i;
564
565 error = 0;
566 for (i = 0; i < n; i++) {
567 inp = inp_list[i];
568 if (inp->inp_gencnt <= gencnt) {
569 struct xinpcb xi;
570 bzero(&xi, sizeof(xi));
571 xi.xi_len = sizeof xi;
572 /* XXX should avoid extra copy */
573 bcopy(inp, &xi.xi_inp, sizeof *inp);
574 if (inp->inp_socket)
575 sotoxsocket(inp->inp_socket, &xi.xi_socket);
576 error = SYSCTL_OUT(req, &xi, sizeof xi);
577 }
578 }
579 if (!error) {
580 /*
581 * Give the user an updated idea of our state.
582 * If the generation differs from what we told
583 * her before, she knows that something happened
584 * while we were processing this request, and it
585 * might be necessary to retry.
586 */
587 INP_INFO_RLOCK(&divcbinfo);
588 xig.xig_gen = divcbinfo.ipi_gencnt;
589 xig.xig_sogen = so_gencnt;
590 xig.xig_count = divcbinfo.ipi_count;
591 INP_INFO_RUNLOCK(&divcbinfo);
592 error = SYSCTL_OUT(req, &xig, sizeof xig);
593 }
594 free(inp_list, M_TEMP);
595 return error;
596 }
597
598 /*
599 * This is the wrapper function for in_setsockaddr. We just pass down
600 * the pcbinfo for in_setpeeraddr to lock.
601 */
602 static int
603 div_sockaddr(struct socket *so, struct sockaddr **nam)
604 {
605 return (in_setsockaddr(so, nam, &divcbinfo));
606 }
607
608 /*
609 * This is the wrapper function for in_setpeeraddr. We just pass down
610 * the pcbinfo for in_setpeeraddr to lock.
611 */
612 static int
613 div_peeraddr(struct socket *so, struct sockaddr **nam)
614 {
615 return (in_setpeeraddr(so, nam, &divcbinfo));
616 }
617
618
619 SYSCTL_DECL(_net_inet_divert);
620 SYSCTL_PROC(_net_inet_divert, OID_AUTO, pcblist, CTLFLAG_RD, 0, 0,
621 div_pcblist, "S,xinpcb", "List of active divert sockets");
622
623 struct pr_usrreqs div_usrreqs = {
624 NULL, pru_accept_notsupp, div_attach, div_bind,
625 pru_connect_notsupp, pru_connect2_notsupp, in_control, div_detach,
626 NULL, pru_listen_notsupp, div_peeraddr, pru_rcvd_notsupp,
627 pru_rcvoob_notsupp, div_send, pru_sense_null, div_shutdown,
628 div_sockaddr, sosend, soreceive, sopoll, in_pcbsosetlabel
629 };
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