FreeBSD/Linux Kernel Cross Reference
sys/net/if_tap.c
1 /* $NetBSD: if_tap.c,v 1.128 2023/01/06 01:54:22 ozaki-r Exp $ */
2
3 /*
4 * Copyright (c) 2003, 2004, 2008, 2009 The NetBSD Foundation.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
17 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
18 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
19 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
20 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26 * POSSIBILITY OF SUCH DAMAGE.
27 */
28
29 /*
30 * tap(4) is a virtual Ethernet interface. It appears as a real Ethernet
31 * device to the system, but can also be accessed by userland through a
32 * character device interface, which allows reading and injecting frames.
33 */
34
35 #include <sys/cdefs.h>
36 __KERNEL_RCSID(0, "$NetBSD: if_tap.c,v 1.128 2023/01/06 01:54:22 ozaki-r Exp $");
37
38 #if defined(_KERNEL_OPT)
39
40 #include "opt_modular.h"
41 #endif
42
43 #include <sys/param.h>
44 #include <sys/atomic.h>
45 #include <sys/conf.h>
46 #include <sys/cprng.h>
47 #include <sys/device.h>
48 #include <sys/file.h>
49 #include <sys/filedesc.h>
50 #include <sys/intr.h>
51 #include <sys/kauth.h>
52 #include <sys/kernel.h>
53 #include <sys/kmem.h>
54 #include <sys/module.h>
55 #include <sys/mutex.h>
56 #include <sys/condvar.h>
57 #include <sys/poll.h>
58 #include <sys/proc.h>
59 #include <sys/select.h>
60 #include <sys/sockio.h>
61 #include <sys/stat.h>
62 #include <sys/sysctl.h>
63 #include <sys/systm.h>
64
65 #include <net/if.h>
66 #include <net/if_dl.h>
67 #include <net/if_ether.h>
68 #include <net/if_tap.h>
69 #include <net/bpf.h>
70
71 #include "ioconf.h"
72
73 /*
74 * sysctl node management
75 *
76 * It's not really possible to use a SYSCTL_SETUP block with
77 * current module implementation, so it is easier to just define
78 * our own function.
79 *
80 * The handler function is a "helper" in Andrew Brown's sysctl
81 * framework terminology. It is used as a gateway for sysctl
82 * requests over the nodes.
83 *
84 * tap_log allows the module to log creations of nodes and
85 * destroy them all at once using sysctl_teardown.
86 */
87 static int tap_node;
88 static int tap_sysctl_handler(SYSCTLFN_PROTO);
89 static void sysctl_tap_setup(struct sysctllog **);
90
91 struct tap_softc {
92 device_t sc_dev;
93 struct ethercom sc_ec;
94 int sc_flags;
95 #define TAP_INUSE 0x00000001 /* tap device can only be opened once */
96 #define TAP_ASYNCIO 0x00000002 /* user is using async I/O (SIGIO) on the device */
97 #define TAP_NBIO 0x00000004 /* user wants calls to avoid blocking */
98 #define TAP_GOING 0x00000008 /* interface is being destroyed */
99 struct selinfo sc_rsel;
100 pid_t sc_pgid; /* For async. IO */
101 kmutex_t sc_lock;
102 kcondvar_t sc_cv;
103 void *sc_sih;
104 struct timespec sc_atime;
105 struct timespec sc_mtime;
106 struct timespec sc_btime;
107 };
108
109 /* autoconf(9) glue */
110
111 static int tap_match(device_t, cfdata_t, void *);
112 static void tap_attach(device_t, device_t, void *);
113 static int tap_detach(device_t, int);
114
115 CFATTACH_DECL_NEW(tap, sizeof(struct tap_softc),
116 tap_match, tap_attach, tap_detach, NULL);
117 extern struct cfdriver tap_cd;
118
119 /* Real device access routines */
120 static int tap_dev_close(struct tap_softc *);
121 static int tap_dev_read(int, struct uio *, int);
122 static int tap_dev_write(int, struct uio *, int);
123 static int tap_dev_ioctl(int, u_long, void *, struct lwp *);
124 static int tap_dev_poll(int, int, struct lwp *);
125 static int tap_dev_kqfilter(int, struct knote *);
126
127 /* Fileops access routines */
128 static int tap_fops_close(file_t *);
129 static int tap_fops_read(file_t *, off_t *, struct uio *,
130 kauth_cred_t, int);
131 static int tap_fops_write(file_t *, off_t *, struct uio *,
132 kauth_cred_t, int);
133 static int tap_fops_ioctl(file_t *, u_long, void *);
134 static int tap_fops_poll(file_t *, int);
135 static int tap_fops_stat(file_t *, struct stat *);
136 static int tap_fops_kqfilter(file_t *, struct knote *);
137
138 static const struct fileops tap_fileops = {
139 .fo_name = "tap",
140 .fo_read = tap_fops_read,
141 .fo_write = tap_fops_write,
142 .fo_ioctl = tap_fops_ioctl,
143 .fo_fcntl = fnullop_fcntl,
144 .fo_poll = tap_fops_poll,
145 .fo_stat = tap_fops_stat,
146 .fo_close = tap_fops_close,
147 .fo_kqfilter = tap_fops_kqfilter,
148 .fo_restart = fnullop_restart,
149 };
150
151 /* Helper for cloning open() */
152 static int tap_dev_cloner(struct lwp *);
153
154 /* Character device routines */
155 static int tap_cdev_open(dev_t, int, int, struct lwp *);
156 static int tap_cdev_close(dev_t, int, int, struct lwp *);
157 static int tap_cdev_read(dev_t, struct uio *, int);
158 static int tap_cdev_write(dev_t, struct uio *, int);
159 static int tap_cdev_ioctl(dev_t, u_long, void *, int, struct lwp *);
160 static int tap_cdev_poll(dev_t, int, struct lwp *);
161 static int tap_cdev_kqfilter(dev_t, struct knote *);
162
163 const struct cdevsw tap_cdevsw = {
164 .d_open = tap_cdev_open,
165 .d_close = tap_cdev_close,
166 .d_read = tap_cdev_read,
167 .d_write = tap_cdev_write,
168 .d_ioctl = tap_cdev_ioctl,
169 .d_stop = nostop,
170 .d_tty = notty,
171 .d_poll = tap_cdev_poll,
172 .d_mmap = nommap,
173 .d_kqfilter = tap_cdev_kqfilter,
174 .d_discard = nodiscard,
175 .d_flag = D_OTHER | D_MPSAFE
176 };
177
178 #define TAP_CLONER 0xfffff /* Maximal minor value */
179
180 /* kqueue-related routines */
181 static void tap_kqdetach(struct knote *);
182 static int tap_kqread(struct knote *, long);
183
184 /*
185 * Those are needed by the ifnet interface, and would typically be
186 * there for any network interface driver.
187 * Some other routines are optional: watchdog and drain.
188 */
189 static void tap_start(struct ifnet *);
190 static void tap_stop(struct ifnet *, int);
191 static int tap_init(struct ifnet *);
192 static int tap_ioctl(struct ifnet *, u_long, void *);
193
194 /* Internal functions */
195 static int tap_lifaddr(struct ifnet *, u_long, struct ifaliasreq *);
196 static void tap_softintr(void *);
197
198 /*
199 * tap is a clonable interface, although it is highly unrealistic for
200 * an Ethernet device.
201 *
202 * Here are the bits needed for a clonable interface.
203 */
204 static int tap_clone_create(struct if_clone *, int);
205 static int tap_clone_destroy(struct ifnet *);
206
207 struct if_clone tap_cloners = IF_CLONE_INITIALIZER("tap",
208 tap_clone_create,
209 tap_clone_destroy);
210
211 /* Helper functions shared by the two cloning code paths */
212 static struct tap_softc * tap_clone_creator(int);
213 int tap_clone_destroyer(device_t);
214
215 static struct sysctllog *tap_sysctl_clog;
216
217 #ifdef _MODULE
218 devmajor_t tap_bmajor = -1, tap_cmajor = -1;
219 #endif
220
221 static u_int tap_count;
222
223 void
224 tapattach(int n)
225 {
226
227 /*
228 * Nothing to do here, initialization is handled by the
229 * module initialization code in tapinit() below).
230 */
231 }
232
233 static void
234 tapinit(void)
235 {
236 int error;
237
238 #ifdef _MODULE
239 devsw_attach("tap", NULL, &tap_bmajor, &tap_cdevsw, &tap_cmajor);
240 #endif
241 error = config_cfattach_attach(tap_cd.cd_name, &tap_ca);
242
243 if (error) {
244 aprint_error("%s: unable to register cfattach\n",
245 tap_cd.cd_name);
246 (void)config_cfdriver_detach(&tap_cd);
247 return;
248 }
249
250 if_clone_attach(&tap_cloners);
251 sysctl_tap_setup(&tap_sysctl_clog);
252 }
253
254 static int
255 tapdetach(void)
256 {
257 int error = 0;
258
259 if_clone_detach(&tap_cloners);
260
261 if (tap_count != 0) {
262 if_clone_attach(&tap_cloners);
263 return EBUSY;
264 }
265
266 error = config_cfattach_detach(tap_cd.cd_name, &tap_ca);
267 if (error == 0) {
268 #ifdef _MODULE
269 devsw_detach(NULL, &tap_cdevsw);
270 #endif
271 sysctl_teardown(&tap_sysctl_clog);
272 } else
273 if_clone_attach(&tap_cloners);
274
275 return error;
276 }
277
278 /* Pretty much useless for a pseudo-device */
279 static int
280 tap_match(device_t parent, cfdata_t cfdata, void *arg)
281 {
282
283 return 1;
284 }
285
286 void
287 tap_attach(device_t parent, device_t self, void *aux)
288 {
289 struct tap_softc *sc = device_private(self);
290 struct ifnet *ifp;
291 const struct sysctlnode *node;
292 int error;
293 uint8_t enaddr[ETHER_ADDR_LEN] =
294 { 0xf2, 0x0b, 0xa4, 0xff, 0xff, 0xff };
295 char enaddrstr[3 * ETHER_ADDR_LEN];
296
297 sc->sc_dev = self;
298 sc->sc_sih = NULL;
299 getnanotime(&sc->sc_btime);
300 sc->sc_atime = sc->sc_mtime = sc->sc_btime;
301 sc->sc_flags = 0;
302 selinit(&sc->sc_rsel);
303
304 cv_init(&sc->sc_cv, "tapread");
305 mutex_init(&sc->sc_lock, MUTEX_DEFAULT, IPL_NET);
306
307 if (!pmf_device_register(self, NULL, NULL))
308 aprint_error_dev(self, "couldn't establish power handler\n");
309
310 /*
311 * In order to obtain unique initial Ethernet address on a host,
312 * do some randomisation. It's not meant for anything but avoiding
313 * hard-coding an address.
314 */
315 cprng_fast(&enaddr[3], 3);
316
317 aprint_verbose_dev(self, "Ethernet address %s\n",
318 ether_snprintf(enaddrstr, sizeof(enaddrstr), enaddr));
319
320 /*
321 * One should note that an interface must do multicast in order
322 * to support IPv6.
323 */
324 ifp = &sc->sc_ec.ec_if;
325 strcpy(ifp->if_xname, device_xname(self));
326 ifp->if_softc = sc;
327 ifp->if_flags = IFF_BROADCAST | IFF_SIMPLEX | IFF_MULTICAST;
328 #ifdef NET_MPSAFE
329 ifp->if_extflags = IFEF_MPSAFE;
330 #endif
331 ifp->if_ioctl = tap_ioctl;
332 ifp->if_start = tap_start;
333 ifp->if_stop = tap_stop;
334 ifp->if_init = tap_init;
335 IFQ_SET_READY(&ifp->if_snd);
336
337 sc->sc_ec.ec_capabilities = ETHERCAP_VLAN_MTU | ETHERCAP_JUMBO_MTU;
338
339 /* Those steps are mandatory for an Ethernet driver. */
340 if_initialize(ifp);
341 ifp->if_percpuq = if_percpuq_create(ifp);
342 ether_ifattach(ifp, enaddr);
343 /* Opening the device will bring the link state up. */
344 ifp->if_link_state = LINK_STATE_DOWN;
345 if_register(ifp);
346
347 /*
348 * Add a sysctl node for that interface.
349 *
350 * The pointer transmitted is not a string, but instead a pointer to
351 * the softc structure, which we can use to build the string value on
352 * the fly in the helper function of the node. See the comments for
353 * tap_sysctl_handler for details.
354 *
355 * Usually sysctl_createv is called with CTL_CREATE as the before-last
356 * component. However, we can allocate a number ourselves, as we are
357 * the only consumer of the net.link.<iface> node. In this case, the
358 * unit number is conveniently used to number the node. CTL_CREATE
359 * would just work, too.
360 */
361 if ((error = sysctl_createv(NULL, 0, NULL,
362 &node, CTLFLAG_READWRITE,
363 CTLTYPE_STRING, device_xname(self), NULL,
364 tap_sysctl_handler, 0, (void *)sc, 18,
365 CTL_NET, AF_LINK, tap_node, device_unit(sc->sc_dev),
366 CTL_EOL)) != 0)
367 aprint_error_dev(self,
368 "sysctl_createv returned %d, ignoring\n", error);
369 }
370
371 /*
372 * When detaching, we do the inverse of what is done in the attach
373 * routine, in reversed order.
374 */
375 static int
376 tap_detach(device_t self, int flags)
377 {
378 struct tap_softc *sc = device_private(self);
379 struct ifnet *ifp = &sc->sc_ec.ec_if;
380 int error;
381
382 sc->sc_flags |= TAP_GOING;
383 tap_stop(ifp, 1);
384 if_down(ifp);
385
386 if (sc->sc_sih != NULL) {
387 softint_disestablish(sc->sc_sih);
388 sc->sc_sih = NULL;
389 }
390
391 /*
392 * Destroying a single leaf is a very straightforward operation using
393 * sysctl_destroyv. One should be sure to always end the path with
394 * CTL_EOL.
395 */
396 if ((error = sysctl_destroyv(NULL, CTL_NET, AF_LINK, tap_node,
397 device_unit(sc->sc_dev), CTL_EOL)) != 0)
398 aprint_error_dev(self,
399 "sysctl_destroyv returned %d, ignoring\n", error);
400 ether_ifdetach(ifp);
401 if_detach(ifp);
402 seldestroy(&sc->sc_rsel);
403 mutex_destroy(&sc->sc_lock);
404 cv_destroy(&sc->sc_cv);
405
406 pmf_device_deregister(self);
407
408 return 0;
409 }
410
411 /*
412 * This is the function where we SEND packets.
413 *
414 * There is no 'receive' equivalent. A typical driver will get
415 * interrupts from the hardware, and from there will inject new packets
416 * into the network stack.
417 *
418 * Once handled, a packet must be freed. A real driver might not be able
419 * to fit all the pending packets into the hardware, and is allowed to
420 * return before having sent all the packets. It should then use the
421 * if_flags flag IFF_OACTIVE to notify the upper layer.
422 *
423 * There are also other flags one should check, such as IFF_PAUSE.
424 *
425 * It is our duty to make packets available to BPF listeners.
426 *
427 * You should be aware that this function is called by the Ethernet layer
428 * at splnet().
429 *
430 * When the device is opened, we have to pass the packet(s) to the
431 * userland. For that we stay in OACTIVE mode while the userland gets
432 * the packets, and we send a signal to the processes waiting to read.
433 *
434 * wakeup(sc) is the counterpart to the tsleep call in
435 * tap_dev_read, while selnotify() is used for kevent(2) and
436 * poll(2) (which includes select(2)) listeners.
437 */
438 static void
439 tap_start(struct ifnet *ifp)
440 {
441 struct tap_softc *sc = (struct tap_softc *)ifp->if_softc;
442 struct mbuf *m0;
443
444 mutex_enter(&sc->sc_lock);
445 if ((sc->sc_flags & TAP_INUSE) == 0) {
446 /* Simply drop packets */
447 for (;;) {
448 IFQ_DEQUEUE(&ifp->if_snd, m0);
449 if (m0 == NULL)
450 goto done;
451
452 if_statadd2(ifp, if_opackets, 1, if_obytes, m0->m_len);
453 bpf_mtap(ifp, m0, BPF_D_OUT);
454
455 m_freem(m0);
456 }
457 } else if (!IFQ_IS_EMPTY(&ifp->if_snd)) {
458 ifp->if_flags |= IFF_OACTIVE;
459 cv_broadcast(&sc->sc_cv);
460 selnotify(&sc->sc_rsel, 0, 1);
461 if (sc->sc_flags & TAP_ASYNCIO) {
462 kpreempt_disable();
463 softint_schedule(sc->sc_sih);
464 kpreempt_enable();
465 }
466 }
467 done:
468 mutex_exit(&sc->sc_lock);
469 }
470
471 static void
472 tap_softintr(void *cookie)
473 {
474 struct tap_softc *sc;
475 struct ifnet *ifp;
476 int a, b;
477
478 sc = cookie;
479
480 if (sc->sc_flags & TAP_ASYNCIO) {
481 ifp = &sc->sc_ec.ec_if;
482 if (ifp->if_flags & IFF_RUNNING) {
483 a = POLL_IN;
484 b = POLLIN | POLLRDNORM;
485 } else {
486 a = POLL_HUP;
487 b = 0;
488 }
489 fownsignal(sc->sc_pgid, SIGIO, a, b, NULL);
490 }
491 }
492
493 /*
494 * A typical driver will only contain the following handlers for
495 * ioctl calls, except SIOCSIFPHYADDR.
496 * The latter is a hack I used to set the Ethernet address of the
497 * faked device.
498 *
499 * Note that ether_ioctl() has to be called under splnet().
500 */
501 static int
502 tap_ioctl(struct ifnet *ifp, u_long cmd, void *data)
503 {
504 int s, error;
505
506 s = splnet();
507
508 switch (cmd) {
509 case SIOCSIFPHYADDR:
510 error = tap_lifaddr(ifp, cmd, (struct ifaliasreq *)data);
511 break;
512 default:
513 error = ether_ioctl(ifp, cmd, data);
514 if (error == ENETRESET)
515 error = 0;
516 break;
517 }
518
519 splx(s);
520
521 return error;
522 }
523
524 /*
525 * Helper function to set Ethernet address. This has been replaced by
526 * the generic SIOCALIFADDR ioctl on a PF_LINK socket.
527 */
528 static int
529 tap_lifaddr(struct ifnet *ifp, u_long cmd, struct ifaliasreq *ifra)
530 {
531 const struct sockaddr *sa = &ifra->ifra_addr;
532
533 if (sa->sa_family != AF_LINK)
534 return EINVAL;
535
536 if_set_sadl(ifp, sa->sa_data, ETHER_ADDR_LEN, false);
537
538 return 0;
539 }
540
541 /*
542 * _init() would typically be called when an interface goes up,
543 * meaning it should configure itself into the state in which it
544 * can send packets.
545 */
546 static int
547 tap_init(struct ifnet *ifp)
548 {
549 ifp->if_flags |= IFF_RUNNING;
550
551 tap_start(ifp);
552
553 return 0;
554 }
555
556 /*
557 * _stop() is called when an interface goes down. It is our
558 * responsibility to validate that state by clearing the
559 * IFF_RUNNING flag.
560 *
561 * We have to wake up all the sleeping processes to have the pending
562 * read requests cancelled.
563 */
564 static void
565 tap_stop(struct ifnet *ifp, int disable)
566 {
567 struct tap_softc *sc = (struct tap_softc *)ifp->if_softc;
568
569 mutex_enter(&sc->sc_lock);
570 ifp->if_flags &= ~IFF_RUNNING;
571 cv_broadcast(&sc->sc_cv);
572 selnotify(&sc->sc_rsel, 0, 1);
573 if (sc->sc_flags & TAP_ASYNCIO) {
574 kpreempt_disable();
575 softint_schedule(sc->sc_sih);
576 kpreempt_enable();
577 }
578 mutex_exit(&sc->sc_lock);
579 }
580
581 /*
582 * The 'create' command of ifconfig can be used to create
583 * any numbered instance of a given device. Thus we have to
584 * make sure we have enough room in cd_devs to create the
585 * user-specified instance. config_attach_pseudo will do this
586 * for us.
587 */
588 static int
589 tap_clone_create(struct if_clone *ifc, int unit)
590 {
591
592 if (tap_clone_creator(unit) == NULL) {
593 aprint_error("%s%d: unable to attach an instance\n",
594 tap_cd.cd_name, unit);
595 return ENXIO;
596 }
597 atomic_inc_uint(&tap_count);
598 return 0;
599 }
600
601 /*
602 * tap(4) can be cloned by two ways:
603 * using 'ifconfig tap0 create', which will use the network
604 * interface cloning API, and call tap_clone_create above.
605 * opening the cloning device node, whose minor number is TAP_CLONER.
606 * See below for an explanation on how this part work.
607 */
608 static struct tap_softc *
609 tap_clone_creator(int unit)
610 {
611 cfdata_t cf;
612
613 cf = kmem_alloc(sizeof(*cf), KM_SLEEP);
614 cf->cf_name = tap_cd.cd_name;
615 cf->cf_atname = tap_ca.ca_name;
616 if (unit == -1) {
617 /* let autoconf find the first free one */
618 cf->cf_unit = 0;
619 cf->cf_fstate = FSTATE_STAR;
620 } else {
621 cf->cf_unit = unit;
622 cf->cf_fstate = FSTATE_NOTFOUND;
623 }
624
625 return device_private(config_attach_pseudo(cf));
626 }
627
628 /*
629 * The clean design of if_clone and autoconf(9) makes that part
630 * really straightforward. The second argument of config_detach
631 * means neither QUIET nor FORCED.
632 */
633 static int
634 tap_clone_destroy(struct ifnet *ifp)
635 {
636 struct tap_softc *sc = ifp->if_softc;
637 int error = tap_clone_destroyer(sc->sc_dev);
638
639 if (error == 0)
640 atomic_dec_uint(&tap_count);
641 return error;
642 }
643
644 int
645 tap_clone_destroyer(device_t dev)
646 {
647 cfdata_t cf = device_cfdata(dev);
648 int error;
649
650 if ((error = config_detach(dev, 0)) != 0)
651 aprint_error_dev(dev, "unable to detach instance\n");
652 kmem_free(cf, sizeof(*cf));
653
654 return error;
655 }
656
657 /*
658 * tap(4) is a bit of an hybrid device. It can be used in two different
659 * ways:
660 * 1. ifconfig tapN create, then use /dev/tapN to read/write off it.
661 * 2. open /dev/tap, get a new interface created and read/write off it.
662 * That interface is destroyed when the process that had it created exits.
663 *
664 * The first way is managed by the cdevsw structure, and you access interfaces
665 * through a (major, minor) mapping: tap4 is obtained by the minor number
666 * 4. The entry points for the cdevsw interface are prefixed by tap_cdev_.
667 *
668 * The second way is the so-called "cloning" device. It's a special minor
669 * number (chosen as the maximal number, to allow as much tap devices as
670 * possible). The user first opens the cloner (e.g., /dev/tap), and that
671 * call ends in tap_cdev_open. The actual place where it is handled is
672 * tap_dev_cloner.
673 *
674 * An tap device cannot be opened more than once at a time, so the cdevsw
675 * part of open() does nothing but noting that the interface is being used and
676 * hence ready to actually handle packets.
677 */
678
679 static int
680 tap_cdev_open(dev_t dev, int flags, int fmt, struct lwp *l)
681 {
682 struct tap_softc *sc;
683
684 if (minor(dev) == TAP_CLONER)
685 return tap_dev_cloner(l);
686
687 sc = device_lookup_private(&tap_cd, minor(dev));
688 if (sc == NULL)
689 return ENXIO;
690
691 /* The device can only be opened once */
692 if (sc->sc_flags & TAP_INUSE)
693 return EBUSY;
694 sc->sc_flags |= TAP_INUSE;
695 if_link_state_change(&sc->sc_ec.ec_if, LINK_STATE_UP);
696
697 return 0;
698 }
699
700 /*
701 * There are several kinds of cloning devices, and the most simple is the one
702 * tap(4) uses. What it does is change the file descriptor with a new one,
703 * with its own fileops structure (which maps to the various read, write,
704 * ioctl functions). It starts allocating a new file descriptor with falloc,
705 * then actually creates the new tap devices.
706 *
707 * Once those two steps are successful, we can re-wire the existing file
708 * descriptor to its new self. This is done with fdclone(): it fills the fp
709 * structure as needed (notably f_devunit gets filled with the fifth parameter
710 * passed, the unit of the tap device which will allows us identifying the
711 * device later), and returns EMOVEFD.
712 *
713 * That magic value is interpreted by sys_open() which then replaces the
714 * current file descriptor by the new one (through a magic member of struct
715 * lwp, l_dupfd).
716 *
717 * The tap device is flagged as being busy since it otherwise could be
718 * externally accessed through the corresponding device node with the cdevsw
719 * interface.
720 */
721
722 static int
723 tap_dev_cloner(struct lwp *l)
724 {
725 struct tap_softc *sc;
726 file_t *fp;
727 int error, fd;
728
729 if ((error = fd_allocfile(&fp, &fd)) != 0)
730 return error;
731
732 if ((sc = tap_clone_creator(-1)) == NULL) {
733 fd_abort(curproc, fp, fd);
734 return ENXIO;
735 }
736
737 sc->sc_flags |= TAP_INUSE;
738 if_link_state_change(&sc->sc_ec.ec_if, LINK_STATE_UP);
739
740 return fd_clone(fp, fd, FREAD | FWRITE, &tap_fileops,
741 (void *)(intptr_t)device_unit(sc->sc_dev));
742 }
743
744 /*
745 * While all other operations (read, write, ioctl, poll and kqfilter) are
746 * really the same whether we are in cdevsw or fileops mode, the close()
747 * function is slightly different in the two cases.
748 *
749 * As for the other, the core of it is shared in tap_dev_close. What
750 * it does is sufficient for the cdevsw interface, but the cloning interface
751 * needs another thing: the interface is destroyed when the processes that
752 * created it closes it.
753 */
754 static int
755 tap_cdev_close(dev_t dev, int flags, int fmt, struct lwp *l)
756 {
757 struct tap_softc *sc = device_lookup_private(&tap_cd, minor(dev));
758
759 if (sc == NULL)
760 return ENXIO;
761
762 return tap_dev_close(sc);
763 }
764
765 /*
766 * It might happen that the administrator used ifconfig to externally destroy
767 * the interface. In that case, tap_fops_close will be called while
768 * tap_detach is already happening. If we called it again from here, we
769 * would dead lock. TAP_GOING ensures that this situation doesn't happen.
770 */
771 static int
772 tap_fops_close(file_t *fp)
773 {
774 struct tap_softc *sc;
775 int unit = fp->f_devunit;
776 int error;
777
778 sc = device_lookup_private(&tap_cd, unit);
779 if (sc == NULL)
780 return ENXIO;
781
782 /* tap_dev_close currently always succeeds, but it might not
783 * always be the case. */
784 KERNEL_LOCK(1, NULL);
785 if ((error = tap_dev_close(sc)) != 0) {
786 KERNEL_UNLOCK_ONE(NULL);
787 return error;
788 }
789
790 /* Destroy the device now that it is no longer useful,
791 * unless it's already being destroyed. */
792 if ((sc->sc_flags & TAP_GOING) != 0) {
793 KERNEL_UNLOCK_ONE(NULL);
794 return 0;
795 }
796
797 error = tap_clone_destroyer(sc->sc_dev);
798 KERNEL_UNLOCK_ONE(NULL);
799 return error;
800 }
801
802 static int
803 tap_dev_close(struct tap_softc *sc)
804 {
805 struct ifnet *ifp;
806 int s;
807
808 s = splnet();
809 /* Let tap_start handle packets again */
810 ifp = &sc->sc_ec.ec_if;
811 ifp->if_flags &= ~IFF_OACTIVE;
812
813 /* Purge output queue */
814 if (!(IFQ_IS_EMPTY(&ifp->if_snd))) {
815 struct mbuf *m;
816
817 for (;;) {
818 IFQ_DEQUEUE(&ifp->if_snd, m);
819 if (m == NULL)
820 break;
821
822 if_statadd2(ifp, if_opackets, 1, if_obytes, m->m_len);
823 bpf_mtap(ifp, m, BPF_D_OUT);
824 m_freem(m);
825 }
826 }
827 splx(s);
828
829 if (sc->sc_sih != NULL) {
830 softint_disestablish(sc->sc_sih);
831 sc->sc_sih = NULL;
832 }
833 sc->sc_flags &= ~(TAP_INUSE | TAP_ASYNCIO);
834 if_link_state_change(ifp, LINK_STATE_DOWN);
835
836 return 0;
837 }
838
839 static int
840 tap_cdev_read(dev_t dev, struct uio *uio, int flags)
841 {
842
843 return tap_dev_read(minor(dev), uio, flags);
844 }
845
846 static int
847 tap_fops_read(file_t *fp, off_t *offp, struct uio *uio,
848 kauth_cred_t cred, int flags)
849 {
850 int error;
851
852 KERNEL_LOCK(1, NULL);
853 error = tap_dev_read(fp->f_devunit, uio, flags);
854 KERNEL_UNLOCK_ONE(NULL);
855 return error;
856 }
857
858 static int
859 tap_dev_read(int unit, struct uio *uio, int flags)
860 {
861 struct tap_softc *sc = device_lookup_private(&tap_cd, unit);
862 struct ifnet *ifp;
863 struct mbuf *m, *n;
864 int error = 0;
865
866 if (sc == NULL)
867 return ENXIO;
868
869 getnanotime(&sc->sc_atime);
870
871 ifp = &sc->sc_ec.ec_if;
872 if ((ifp->if_flags & IFF_UP) == 0)
873 return EHOSTDOWN;
874
875 /* In the TAP_NBIO case, we have to make sure we won't be sleeping */
876 if ((sc->sc_flags & TAP_NBIO) != 0) {
877 if (!mutex_tryenter(&sc->sc_lock))
878 return EWOULDBLOCK;
879 } else
880 mutex_enter(&sc->sc_lock);
881
882 if (IFQ_IS_EMPTY(&ifp->if_snd)) {
883 ifp->if_flags &= ~IFF_OACTIVE;
884 if (sc->sc_flags & TAP_NBIO)
885 error = EWOULDBLOCK;
886 else
887 error = cv_wait_sig(&sc->sc_cv, &sc->sc_lock);
888
889 if (error != 0) {
890 mutex_exit(&sc->sc_lock);
891 return error;
892 }
893 /* The device might have been downed */
894 if ((ifp->if_flags & IFF_UP) == 0) {
895 mutex_exit(&sc->sc_lock);
896 return EHOSTDOWN;
897 }
898 }
899
900 IFQ_DEQUEUE(&ifp->if_snd, m);
901 mutex_exit(&sc->sc_lock);
902
903 ifp->if_flags &= ~IFF_OACTIVE;
904 if (m == NULL) {
905 error = 0;
906 goto out;
907 }
908
909 if_statadd2(ifp, if_opackets, 1,
910 if_obytes, m->m_len); /* XXX only first in chain */
911 bpf_mtap(ifp, m, BPF_D_OUT);
912 if ((error = pfil_run_hooks(ifp->if_pfil, &m, ifp, PFIL_OUT)) != 0)
913 goto out;
914 if (m == NULL)
915 goto out;
916
917 /*
918 * One read is one packet.
919 */
920 do {
921 error = uiomove(mtod(m, void *),
922 uimin(m->m_len, uio->uio_resid), uio);
923 m = n = m_free(m);
924 } while (m != NULL && uio->uio_resid > 0 && error == 0);
925
926 if (m != NULL)
927 m_freem(m);
928
929 out:
930 return error;
931 }
932
933 static int
934 tap_fops_stat(file_t *fp, struct stat *st)
935 {
936 int error = 0;
937 struct tap_softc *sc;
938 int unit = fp->f_devunit;
939
940 (void)memset(st, 0, sizeof(*st));
941
942 KERNEL_LOCK(1, NULL);
943 sc = device_lookup_private(&tap_cd, unit);
944 if (sc == NULL) {
945 error = ENXIO;
946 goto out;
947 }
948
949 st->st_dev = makedev(cdevsw_lookup_major(&tap_cdevsw), unit);
950 st->st_atimespec = sc->sc_atime;
951 st->st_mtimespec = sc->sc_mtime;
952 st->st_ctimespec = st->st_birthtimespec = sc->sc_btime;
953 st->st_uid = kauth_cred_geteuid(fp->f_cred);
954 st->st_gid = kauth_cred_getegid(fp->f_cred);
955 out:
956 KERNEL_UNLOCK_ONE(NULL);
957 return error;
958 }
959
960 static int
961 tap_cdev_write(dev_t dev, struct uio *uio, int flags)
962 {
963
964 return tap_dev_write(minor(dev), uio, flags);
965 }
966
967 static int
968 tap_fops_write(file_t *fp, off_t *offp, struct uio *uio,
969 kauth_cred_t cred, int flags)
970 {
971 int error;
972
973 KERNEL_LOCK(1, NULL);
974 error = tap_dev_write(fp->f_devunit, uio, flags);
975 KERNEL_UNLOCK_ONE(NULL);
976 return error;
977 }
978
979 static int
980 tap_dev_write(int unit, struct uio *uio, int flags)
981 {
982 struct tap_softc *sc =
983 device_lookup_private(&tap_cd, unit);
984 struct ifnet *ifp;
985 struct mbuf *m, **mp;
986 size_t len = 0;
987 int error = 0;
988
989 if (sc == NULL)
990 return ENXIO;
991
992 getnanotime(&sc->sc_mtime);
993 ifp = &sc->sc_ec.ec_if;
994
995 /* One write, one packet, that's the rule */
996 MGETHDR(m, M_DONTWAIT, MT_DATA);
997 if (m == NULL) {
998 if_statinc(ifp, if_ierrors);
999 return ENOBUFS;
1000 }
1001 m->m_pkthdr.len = uio->uio_resid;
1002
1003 mp = &m;
1004 while (error == 0 && uio->uio_resid > 0) {
1005 if (*mp != m) {
1006 MGET(*mp, M_DONTWAIT, MT_DATA);
1007 if (*mp == NULL) {
1008 error = ENOBUFS;
1009 break;
1010 }
1011 }
1012 (*mp)->m_len = uimin(MHLEN, uio->uio_resid);
1013 len += (*mp)->m_len;
1014 error = uiomove(mtod(*mp, void *), (*mp)->m_len, uio);
1015 mp = &(*mp)->m_next;
1016 }
1017 if (error) {
1018 if_statinc(ifp, if_ierrors);
1019 m_freem(m);
1020 return error;
1021 }
1022
1023 m_set_rcvif(m, ifp);
1024
1025 if_statadd2(ifp, if_ipackets, 1, if_ibytes, len);
1026 bpf_mtap(ifp, m, BPF_D_IN);
1027 if ((error = pfil_run_hooks(ifp->if_pfil, &m, ifp, PFIL_IN)) != 0)
1028 return error;
1029 if (m == NULL)
1030 return 0;
1031
1032 if_percpuq_enqueue(ifp->if_percpuq, m);
1033
1034 return 0;
1035 }
1036
1037 static int
1038 tap_cdev_ioctl(dev_t dev, u_long cmd, void *data, int flags, struct lwp *l)
1039 {
1040
1041 return tap_dev_ioctl(minor(dev), cmd, data, l);
1042 }
1043
1044 static int
1045 tap_fops_ioctl(file_t *fp, u_long cmd, void *data)
1046 {
1047
1048 return tap_dev_ioctl(fp->f_devunit, cmd, data, curlwp);
1049 }
1050
1051 static int
1052 tap_dev_ioctl(int unit, u_long cmd, void *data, struct lwp *l)
1053 {
1054 struct tap_softc *sc = device_lookup_private(&tap_cd, unit);
1055
1056 if (sc == NULL)
1057 return ENXIO;
1058
1059 switch (cmd) {
1060 case FIONREAD:
1061 {
1062 struct ifnet *ifp = &sc->sc_ec.ec_if;
1063 struct mbuf *m;
1064 int s;
1065
1066 s = splnet();
1067 IFQ_POLL(&ifp->if_snd, m);
1068
1069 if (m == NULL)
1070 *(int *)data = 0;
1071 else
1072 *(int *)data = m->m_pkthdr.len;
1073 splx(s);
1074 return 0;
1075 }
1076 case TIOCSPGRP:
1077 case FIOSETOWN:
1078 return fsetown(&sc->sc_pgid, cmd, data);
1079 case TIOCGPGRP:
1080 case FIOGETOWN:
1081 return fgetown(sc->sc_pgid, cmd, data);
1082 case FIOASYNC:
1083 if (*(int *)data) {
1084 if (sc->sc_sih == NULL) {
1085 sc->sc_sih = softint_establish(SOFTINT_CLOCK,
1086 tap_softintr, sc);
1087 if (sc->sc_sih == NULL)
1088 return EBUSY; /* XXX */
1089 }
1090 sc->sc_flags |= TAP_ASYNCIO;
1091 } else {
1092 sc->sc_flags &= ~TAP_ASYNCIO;
1093 if (sc->sc_sih != NULL) {
1094 softint_disestablish(sc->sc_sih);
1095 sc->sc_sih = NULL;
1096 }
1097 }
1098 return 0;
1099 case FIONBIO:
1100 if (*(int *)data)
1101 sc->sc_flags |= TAP_NBIO;
1102 else
1103 sc->sc_flags &= ~TAP_NBIO;
1104 return 0;
1105 case TAPGIFNAME:
1106 {
1107 struct ifreq *ifr = (struct ifreq *)data;
1108 struct ifnet *ifp = &sc->sc_ec.ec_if;
1109
1110 strlcpy(ifr->ifr_name, ifp->if_xname, IFNAMSIZ);
1111 return 0;
1112 }
1113 default:
1114 return ENOTTY;
1115 }
1116 }
1117
1118 static int
1119 tap_cdev_poll(dev_t dev, int events, struct lwp *l)
1120 {
1121
1122 return tap_dev_poll(minor(dev), events, l);
1123 }
1124
1125 static int
1126 tap_fops_poll(file_t *fp, int events)
1127 {
1128
1129 return tap_dev_poll(fp->f_devunit, events, curlwp);
1130 }
1131
1132 static int
1133 tap_dev_poll(int unit, int events, struct lwp *l)
1134 {
1135 struct tap_softc *sc = device_lookup_private(&tap_cd, unit);
1136 int revents = 0;
1137
1138 if (sc == NULL)
1139 return POLLERR;
1140
1141 if (events & (POLLIN | POLLRDNORM)) {
1142 struct ifnet *ifp = &sc->sc_ec.ec_if;
1143 struct mbuf *m;
1144 int s;
1145
1146 s = splnet();
1147 IFQ_POLL(&ifp->if_snd, m);
1148
1149 if (m != NULL)
1150 revents |= events & (POLLIN | POLLRDNORM);
1151 else {
1152 mutex_spin_enter(&sc->sc_lock);
1153 selrecord(l, &sc->sc_rsel);
1154 mutex_spin_exit(&sc->sc_lock);
1155 }
1156 splx(s);
1157 }
1158 revents |= events & (POLLOUT | POLLWRNORM);
1159
1160 return revents;
1161 }
1162
1163 static struct filterops tap_read_filterops = {
1164 .f_flags = FILTEROP_ISFD,
1165 .f_attach = NULL,
1166 .f_detach = tap_kqdetach,
1167 .f_event = tap_kqread,
1168 };
1169
1170 static int
1171 tap_cdev_kqfilter(dev_t dev, struct knote *kn)
1172 {
1173
1174 return tap_dev_kqfilter(minor(dev), kn);
1175 }
1176
1177 static int
1178 tap_fops_kqfilter(file_t *fp, struct knote *kn)
1179 {
1180
1181 return tap_dev_kqfilter(fp->f_devunit, kn);
1182 }
1183
1184 static int
1185 tap_dev_kqfilter(int unit, struct knote *kn)
1186 {
1187 struct tap_softc *sc = device_lookup_private(&tap_cd, unit);
1188
1189 if (sc == NULL)
1190 return ENXIO;
1191
1192 switch(kn->kn_filter) {
1193 case EVFILT_READ:
1194 kn->kn_fop = &tap_read_filterops;
1195 kn->kn_hook = sc;
1196 KERNEL_LOCK(1, NULL);
1197 mutex_spin_enter(&sc->sc_lock);
1198 selrecord_knote(&sc->sc_rsel, kn);
1199 mutex_spin_exit(&sc->sc_lock);
1200 KERNEL_UNLOCK_ONE(NULL);
1201 break;
1202
1203 case EVFILT_WRITE:
1204 kn->kn_fop = &seltrue_filtops;
1205 break;
1206
1207 default:
1208 return EINVAL;
1209 }
1210
1211 return 0;
1212 }
1213
1214 static void
1215 tap_kqdetach(struct knote *kn)
1216 {
1217 struct tap_softc *sc = (struct tap_softc *)kn->kn_hook;
1218
1219 KERNEL_LOCK(1, NULL);
1220 mutex_spin_enter(&sc->sc_lock);
1221 selremove_knote(&sc->sc_rsel, kn);
1222 mutex_spin_exit(&sc->sc_lock);
1223 KERNEL_UNLOCK_ONE(NULL);
1224 }
1225
1226 static int
1227 tap_kqread(struct knote *kn, long hint)
1228 {
1229 struct tap_softc *sc = (struct tap_softc *)kn->kn_hook;
1230 struct ifnet *ifp = &sc->sc_ec.ec_if;
1231 struct mbuf *m;
1232 int s, rv;
1233
1234 KERNEL_LOCK(1, NULL);
1235 s = splnet();
1236 IFQ_POLL(&ifp->if_snd, m);
1237
1238 if (m == NULL)
1239 kn->kn_data = 0;
1240 else
1241 kn->kn_data = m->m_pkthdr.len;
1242 splx(s);
1243 rv = (kn->kn_data != 0 ? 1 : 0);
1244 KERNEL_UNLOCK_ONE(NULL);
1245 return rv;
1246 }
1247
1248 /*
1249 * sysctl management routines
1250 * You can set the address of an interface through:
1251 * net.link.tap.tap<number>
1252 *
1253 * Note the consistent use of tap_log in order to use
1254 * sysctl_teardown at unload time.
1255 *
1256 * In the kernel you will find a lot of SYSCTL_SETUP blocks. Those
1257 * blocks register a function in a special section of the kernel
1258 * (called a link set) which is used at init_sysctl() time to cycle
1259 * through all those functions to create the kernel's sysctl tree.
1260 *
1261 * It is not possible to use link sets in a module, so the
1262 * easiest is to simply call our own setup routine at load time.
1263 *
1264 * In the SYSCTL_SETUP blocks you find in the kernel, nodes have the
1265 * CTLFLAG_PERMANENT flag, meaning they cannot be removed. Once the
1266 * whole kernel sysctl tree is built, it is not possible to add any
1267 * permanent node.
1268 *
1269 * It should be noted that we're not saving the sysctlnode pointer
1270 * we are returned when creating the "tap" node. That structure
1271 * cannot be trusted once out of the calling function, as it might
1272 * get reused. So we just save the MIB number, and always give the
1273 * full path starting from the root for later calls to sysctl_createv
1274 * and sysctl_destroyv.
1275 */
1276 static void
1277 sysctl_tap_setup(struct sysctllog **clog)
1278 {
1279 const struct sysctlnode *node;
1280 int error = 0;
1281
1282 if ((error = sysctl_createv(clog, 0, NULL, NULL,
1283 CTLFLAG_PERMANENT,
1284 CTLTYPE_NODE, "link", NULL,
1285 NULL, 0, NULL, 0,
1286 CTL_NET, AF_LINK, CTL_EOL)) != 0)
1287 return;
1288
1289 /*
1290 * The first four parameters of sysctl_createv are for management.
1291 *
1292 * The four that follows, here starting with a '' for the flags,
1293 * describe the node.
1294 *
1295 * The next series of four set its value, through various possible
1296 * means.
1297 *
1298 * Last but not least, the path to the node is described. That path
1299 * is relative to the given root (third argument). Here we're
1300 * starting from the root.
1301 */
1302 if ((error = sysctl_createv(clog, 0, NULL, &node,
1303 CTLFLAG_PERMANENT,
1304 CTLTYPE_NODE, "tap", NULL,
1305 NULL, 0, NULL, 0,
1306 CTL_NET, AF_LINK, CTL_CREATE, CTL_EOL)) != 0)
1307 return;
1308 tap_node = node->sysctl_num;
1309 }
1310
1311 /*
1312 * The helper functions make Andrew Brown's interface really
1313 * shine. It makes possible to create value on the fly whether
1314 * the sysctl value is read or written.
1315 *
1316 * As shown as an example in the man page, the first step is to
1317 * create a copy of the node to have sysctl_lookup work on it.
1318 *
1319 * Here, we have more work to do than just a copy, since we have
1320 * to create the string. The first step is to collect the actual
1321 * value of the node, which is a convenient pointer to the softc
1322 * of the interface. From there we create the string and use it
1323 * as the value, but only for the *copy* of the node.
1324 *
1325 * Then we let sysctl_lookup do the magic, which consists in
1326 * setting oldp and newp as required by the operation. When the
1327 * value is read, that means that the string will be copied to
1328 * the user, and when it is written, the new value will be copied
1329 * over in the addr array.
1330 *
1331 * If newp is NULL, the user was reading the value, so we don't
1332 * have anything else to do. If a new value was written, we
1333 * have to check it.
1334 *
1335 * If it is incorrect, we can return an error and leave 'node' as
1336 * it is: since it is a copy of the actual node, the change will
1337 * be forgotten.
1338 *
1339 * Upon a correct input, we commit the change to the ifnet
1340 * structure of our interface.
1341 */
1342 static int
1343 tap_sysctl_handler(SYSCTLFN_ARGS)
1344 {
1345 struct sysctlnode node;
1346 struct tap_softc *sc;
1347 struct ifnet *ifp;
1348 int error;
1349 size_t len;
1350 char addr[3 * ETHER_ADDR_LEN];
1351 uint8_t enaddr[ETHER_ADDR_LEN];
1352
1353 node = *rnode;
1354 sc = node.sysctl_data;
1355 ifp = &sc->sc_ec.ec_if;
1356 (void)ether_snprintf(addr, sizeof(addr), CLLADDR(ifp->if_sadl));
1357 node.sysctl_data = addr;
1358 error = sysctl_lookup(SYSCTLFN_CALL(&node));
1359 if (error || newp == NULL)
1360 return error;
1361
1362 len = strlen(addr);
1363 if (len < 11 || len > 17)
1364 return EINVAL;
1365
1366 /* Commit change */
1367 if (ether_aton_r(enaddr, sizeof(enaddr), addr) != 0)
1368 return EINVAL;
1369 if_set_sadl(ifp, enaddr, ETHER_ADDR_LEN, false);
1370 return error;
1371 }
1372
1373 /*
1374 * Module infrastructure
1375 */
1376 #include "if_module.h"
1377
1378 IF_MODULE(MODULE_CLASS_DRIVER, tap, NULL)
Cache object: 5033c24bde49e6b5f38f683ff905154b
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