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 * $FreeBSD$
34 */
35
36 #include "opt_inet.h"
37 #include "opt_ipfw.h"
38 #include "opt_ipdivert.h"
39 #include "opt_ipsec.h"
40
41 #ifndef INET
42 #error "IPDIVERT requires INET."
43 #endif
44
45 #include <sys/param.h>
46 #include <sys/kernel.h>
47 #include <sys/malloc.h>
48 #include <sys/mbuf.h>
49 #include <sys/socket.h>
50 #include <sys/protosw.h>
51 #include <sys/socketvar.h>
52 #include <sys/sysctl.h>
53 #include <sys/systm.h>
54 #include <sys/proc.h>
55
56 #include <vm/vm_zone.h>
57
58 #include <net/if.h>
59 #include <net/route.h>
60
61 #include <netinet/in.h>
62 #include <netinet/in_systm.h>
63 #include <netinet/ip.h>
64 #include <netinet/in_pcb.h>
65 #include <netinet/in_var.h>
66 #include <netinet/ip_var.h>
67
68 /*
69 * Divert sockets
70 */
71
72 /*
73 * Allocate enough space to hold a full IP packet
74 */
75 #define DIVSNDQ (65536 + 100)
76 #define DIVRCVQ (65536 + 100)
77
78 /*
79 * Divert sockets work in conjunction with ipfw, see the divert(4)
80 * manpage for features.
81 * Internally, packets selected by ipfw in ip_input() or ip_output(),
82 * and never diverted before, are passed to the input queue of the
83 * divert socket with a given 'divert_port' number (as specified in
84 * the matching ipfw rule), and they are tagged with a 16 bit cookie
85 * (representing the rule number of the matching ipfw rule), which
86 * is passed to process reading from the socket.
87 *
88 * Packets written to the divert socket are again tagged with a cookie
89 * (usually the same as above) and a destination address.
90 * If the destination address is INADDR_ANY then the packet is
91 * treated as outgoing and sent to ip_output(), otherwise it is
92 * treated as incoming and sent to ip_input().
93 * In both cases, the packet is tagged with the cookie.
94 *
95 * On reinjection, processing in ip_input() and ip_output()
96 * will be exactly the same as for the original packet, except that
97 * ipfw processing will start at the rule number after the one
98 * written in the cookie (so, tagging a packet with a cookie of 0
99 * will cause it to be effectively considered as a standard packet).
100 */
101
102 /* Internal variables */
103 static struct inpcbhead divcb;
104 static struct inpcbinfo divcbinfo;
105
106 static u_long div_sendspace = DIVSNDQ; /* XXX sysctl ? */
107 static u_long div_recvspace = DIVRCVQ; /* XXX sysctl ? */
108
109 /* Optimization: have this preinitialized */
110 static struct sockaddr_in divsrc = { sizeof(divsrc), AF_INET };
111
112 /*
113 * Initialize divert connection block queue.
114 */
115 void
116 div_init(void)
117 {
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 = zinit("divcb", sizeof(struct inpcb),
128 maxsockets, ZONE_INTERRUPT, 0);
129 }
130
131 /*
132 * IPPROTO_DIVERT is not a real IP protocol; don't allow any packets
133 * with that protocol number to enter the system from the outside.
134 */
135 void
136 div_input(struct mbuf *m, int off, int proto)
137 {
138 ipstat.ips_noproto++;
139 m_freem(m);
140 }
141
142 /*
143 * Divert a packet by passing it up to the divert socket at port 'port'.
144 *
145 * Setup generic address and protocol structures for div_input routine,
146 * then pass them along with mbuf chain.
147 */
148 void
149 divert_packet(struct mbuf *m, int incoming, int port, int rule)
150 {
151 struct ip *ip;
152 struct inpcb *inp;
153 struct socket *sa;
154 u_int16_t nport;
155
156 /* Sanity check */
157 KASSERT(port != 0, ("%s: port=0", __FUNCTION__));
158
159 divsrc.sin_port = rule; /* record matching rule */
160
161 /* Assure header */
162 if (m->m_len < sizeof(struct ip) &&
163 (m = m_pullup(m, sizeof(struct ip))) == 0)
164 return;
165 ip = mtod(m, struct ip *);
166
167 /*
168 * Record receive interface address, if any.
169 * But only for incoming packets.
170 */
171 divsrc.sin_addr.s_addr = 0;
172 if (incoming) {
173 struct ifaddr *ifa;
174
175 /* Sanity check */
176 KASSERT((m->m_flags & M_PKTHDR), ("%s: !PKTHDR", __FUNCTION__));
177
178 /* Find IP address for receive interface */
179 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) {
180 if (ifa->ifa_addr == NULL)
181 continue;
182 if (ifa->ifa_addr->sa_family != AF_INET)
183 continue;
184 divsrc.sin_addr =
185 ((struct sockaddr_in *) ifa->ifa_addr)->sin_addr;
186 break;
187 }
188 }
189 /*
190 * Record the incoming interface name whenever we have one.
191 */
192 bzero(&divsrc.sin_zero, sizeof(divsrc.sin_zero));
193 if (m->m_pkthdr.rcvif) {
194 /*
195 * Hide the actual interface name in there in the
196 * sin_zero array. XXX This needs to be moved to a
197 * different sockaddr type for divert, e.g.
198 * sockaddr_div with multiple fields like
199 * sockaddr_dl. Presently we have only 7 bytes
200 * but that will do for now as most interfaces
201 * are 4 or less + 2 or less bytes for unit.
202 * There is probably a faster way of doing this,
203 * possibly taking it from the sockaddr_dl on the iface.
204 * This solves the problem of a P2P link and a LAN interface
205 * having the same address, which can result in the wrong
206 * interface being assigned to the packet when fed back
207 * into the divert socket. Theoretically if the daemon saves
208 * and re-uses the sockaddr_in as suggested in the man pages,
209 * this iface name will come along for the ride.
210 * (see div_output for the other half of this.)
211 */
212 snprintf(divsrc.sin_zero, sizeof(divsrc.sin_zero),
213 "%s%d", m->m_pkthdr.rcvif->if_name,
214 m->m_pkthdr.rcvif->if_unit);
215 }
216
217 /* Put packet on socket queue, if any */
218 sa = NULL;
219 nport = htons((u_int16_t)port);
220 LIST_FOREACH(inp, &divcb, inp_list) {
221 if (inp->inp_lport == nport)
222 sa = inp->inp_socket;
223 }
224 if (sa) {
225 if (sbappendaddr(&sa->so_rcv, (struct sockaddr *)&divsrc,
226 m, (struct mbuf *)0) == 0)
227 m_freem(m);
228 else
229 sorwakeup(sa);
230 } else {
231 m_freem(m);
232 ipstat.ips_noproto++;
233 ipstat.ips_delivered--;
234 }
235 }
236
237 /*
238 * Deliver packet back into the IP processing machinery.
239 *
240 * If no address specified, or address is 0.0.0.0, send to ip_output();
241 * otherwise, send to ip_input() and mark as having been received on
242 * the interface with that address.
243 */
244 static int
245 div_output(struct socket *so, struct mbuf *m,
246 struct sockaddr_in *sin, struct mbuf *control)
247 {
248 int error = 0;
249 struct m_hdr divert_tag;
250
251 /*
252 * Prepare the tag for divert info. Note that a packet
253 * with a 0 tag in mh_data is effectively untagged,
254 * so we could optimize that case.
255 */
256 divert_tag.mh_type = MT_TAG;
257 divert_tag.mh_flags = PACKET_TAG_DIVERT;
258 divert_tag.mh_next = m;
259 divert_tag.mh_data = 0; /* the matching rule # */
260 m->m_pkthdr.rcvif = NULL; /* XXX is it necessary ? */
261
262 if (control)
263 m_freem(control); /* XXX */
264
265 /* Loopback avoidance and state recovery */
266 if (sin) {
267 int i;
268
269 divert_tag.mh_data = (caddr_t)(int)sin->sin_port;
270 /*
271 * Find receive interface with the given name, stuffed
272 * (if it exists) in the sin_zero[] field.
273 * The name is user supplied data so don't trust its size
274 * or that it is zero terminated.
275 */
276 for (i = 0; sin->sin_zero[i] && i < sizeof(sin->sin_zero); i++)
277 ;
278 if ( i > 0 && i < sizeof(sin->sin_zero))
279 m->m_pkthdr.rcvif = ifunit(sin->sin_zero);
280 }
281
282 /* Reinject packet into the system as incoming or outgoing */
283 if (!sin || sin->sin_addr.s_addr == 0) {
284 struct inpcb *const inp = sotoinpcb(so);
285 struct ip *const ip = mtod(m, struct ip *);
286
287 /*
288 * Don't allow both user specified and setsockopt options,
289 * and don't allow packet length sizes that will crash
290 */
291 if (((ip->ip_hl != (sizeof (*ip) >> 2)) && inp->inp_options) ||
292 ((u_short)ntohs(ip->ip_len) > m->m_pkthdr.len)) {
293 error = EINVAL;
294 goto cantsend;
295 }
296
297 /* Convert fields to host order for ip_output() */
298 ip->ip_len = ntohs(ip->ip_len);
299 ip->ip_off = ntohs(ip->ip_off);
300
301 /* Send packet to output processing */
302 ipstat.ips_rawout++; /* XXX */
303 error = ip_output((struct mbuf *)&divert_tag,
304 inp->inp_options, &inp->inp_route,
305 (so->so_options & SO_DONTROUTE) |
306 IP_ALLOWBROADCAST | IP_RAWOUTPUT,
307 inp->inp_moptions, NULL);
308 } else {
309 if (m->m_pkthdr.rcvif == NULL) {
310 /*
311 * No luck with the name, check by IP address.
312 * Clear the port and the ifname to make sure
313 * there are no distractions for ifa_ifwithaddr.
314 */
315 struct ifaddr *ifa;
316
317 bzero(sin->sin_zero, sizeof(sin->sin_zero));
318 sin->sin_port = 0;
319 ifa = ifa_ifwithaddr((struct sockaddr *) sin);
320 if (ifa == NULL) {
321 error = EADDRNOTAVAIL;
322 goto cantsend;
323 }
324 m->m_pkthdr.rcvif = ifa->ifa_ifp;
325 }
326 /* Send packet to input processing */
327 ip_input((struct mbuf *)&divert_tag);
328 }
329
330 return error;
331
332 cantsend:
333 m_freem(m);
334 return error;
335 }
336
337 static int
338 div_attach(struct socket *so, int proto, struct proc *p)
339 {
340 struct inpcb *inp;
341 int error, s;
342
343 inp = sotoinpcb(so);
344 if (inp)
345 panic("div_attach");
346 if (p && (error = suser(p)) != 0)
347 return error;
348
349 error = soreserve(so, div_sendspace, div_recvspace);
350 if (error)
351 return error;
352 s = splnet();
353 error = in_pcballoc(so, &divcbinfo, p);
354 splx(s);
355 if (error)
356 return error;
357 inp = (struct inpcb *)so->so_pcb;
358 inp->inp_ip_p = proto;
359 inp->inp_vflag |= INP_IPV4;
360 inp->inp_flags |= INP_HDRINCL;
361 return 0;
362 }
363
364 static int
365 div_detach(struct socket *so)
366 {
367 struct inpcb *inp;
368
369 inp = sotoinpcb(so);
370 if (inp == 0)
371 panic("div_detach");
372 in_pcbdetach(inp);
373 return 0;
374 }
375
376 static int
377 div_bind(struct socket *so, struct sockaddr *nam, struct proc *p)
378 {
379 struct inpcb *inp;
380 int s;
381 int error;
382
383 s = splnet();
384 inp = sotoinpcb(so);
385 /* in_pcbbind assumes that nam is a sockaddr_in
386 * and in_pcbbind requires a valid address. Since divert
387 * sockets don't we need to make sure the address is
388 * filled in properly.
389 * XXX -- divert should not be abusing in_pcbind
390 * and should probably have its own family.
391 */
392 if (nam->sa_family != AF_INET)
393 error = EAFNOSUPPORT;
394 else {
395 ((struct sockaddr_in *)nam)->sin_addr.s_addr = INADDR_ANY;
396 error = in_pcbbind(inp, nam, p);
397 }
398 splx(s);
399 return error;
400 }
401
402 static int
403 div_shutdown(struct socket *so)
404 {
405 socantsendmore(so);
406 return 0;
407 }
408
409 static int
410 div_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *nam,
411 struct mbuf *control, struct proc *p)
412 {
413 /* Packet must have a header (but that's about it) */
414 if (m->m_len < sizeof (struct ip) &&
415 (m = m_pullup(m, sizeof (struct ip))) == 0) {
416 ipstat.ips_toosmall++;
417 m_freem(m);
418 return EINVAL;
419 }
420
421 /* Send packet */
422 return div_output(so, m, (struct sockaddr_in *)nam, control);
423 }
424
425 static int
426 div_pcblist(SYSCTL_HANDLER_ARGS)
427 {
428 int error, i, n, s;
429 struct inpcb *inp, **inp_list;
430 inp_gen_t gencnt;
431 struct xinpgen xig;
432
433 /*
434 * The process of preparing the TCB list is too time-consuming and
435 * resource-intensive to repeat twice on every request.
436 */
437 if (req->oldptr == 0) {
438 n = divcbinfo.ipi_count;
439 req->oldidx = 2 * (sizeof xig)
440 + (n + n/8) * sizeof(struct xinpcb);
441 return 0;
442 }
443
444 if (req->newptr != 0)
445 return EPERM;
446
447 /*
448 * OK, now we're committed to doing something.
449 */
450 s = splnet();
451 gencnt = divcbinfo.ipi_gencnt;
452 n = divcbinfo.ipi_count;
453 splx(s);
454
455 xig.xig_len = sizeof xig;
456 xig.xig_count = n;
457 xig.xig_gen = gencnt;
458 xig.xig_sogen = so_gencnt;
459 error = SYSCTL_OUT(req, &xig, sizeof xig);
460 if (error)
461 return error;
462
463 inp_list = malloc(n * sizeof *inp_list, M_TEMP, M_WAITOK);
464 if (inp_list == 0)
465 return ENOMEM;
466
467 s = splnet();
468 for (inp = LIST_FIRST(divcbinfo.listhead), i = 0; inp && i < n;
469 inp = LIST_NEXT(inp, inp_list)) {
470 if (inp->inp_gencnt <= gencnt && !prison_xinpcb(req->p, inp))
471 inp_list[i++] = inp;
472 }
473 splx(s);
474 n = i;
475
476 error = 0;
477 for (i = 0; i < n; i++) {
478 inp = inp_list[i];
479 if (inp->inp_gencnt <= gencnt) {
480 struct xinpcb xi;
481 bzero(&xi, sizeof(xi));
482 xi.xi_len = sizeof xi;
483 /* XXX should avoid extra copy */
484 bcopy(inp, &xi.xi_inp, sizeof *inp);
485 if (inp->inp_socket)
486 sotoxsocket(inp->inp_socket, &xi.xi_socket);
487 error = SYSCTL_OUT(req, &xi, sizeof xi);
488 }
489 }
490 if (!error) {
491 /*
492 * Give the user an updated idea of our state.
493 * If the generation differs from what we told
494 * her before, she knows that something happened
495 * while we were processing this request, and it
496 * might be necessary to retry.
497 */
498 s = splnet();
499 xig.xig_gen = divcbinfo.ipi_gencnt;
500 xig.xig_sogen = so_gencnt;
501 xig.xig_count = divcbinfo.ipi_count;
502 splx(s);
503 error = SYSCTL_OUT(req, &xig, sizeof xig);
504 }
505 free(inp_list, M_TEMP);
506 return error;
507 }
508
509 SYSCTL_DECL(_net_inet_divert);
510 SYSCTL_PROC(_net_inet_divert, OID_AUTO, pcblist, CTLFLAG_RD, 0, 0,
511 div_pcblist, "S,xinpcb", "List of active divert sockets");
512
513 struct pr_usrreqs div_usrreqs = {
514 NULL, pru_accept_notsupp, div_attach, div_bind,
515 pru_connect_notsupp, pru_connect2_notsupp, in_control, div_detach,
516 NULL, pru_listen_notsupp, in_setpeeraddr, pru_rcvd_notsupp,
517 pru_rcvoob_notsupp, div_send, pru_sense_null, div_shutdown,
518 in_setsockaddr, sosend, soreceive, sopoll
519 };
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