xref: /freebsd/sys/net/if_clone.c (revision 396c556d77189a5c474d35cec6f44a762e310b7d)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (c) 2012 Gleb Smirnoff <glebius@FreeBSD.org>
5  * Copyright (c) 1980, 1986, 1993
6  *	The Regents of the University of California.  All rights reserved.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 3. Neither the name of the University nor the names of its contributors
17  *    may be used to endorse or promote products derived from this software
18  *    without specific prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30  * SUCH DAMAGE.
31  *
32  *	@(#)if.c	8.5 (Berkeley) 1/9/95
33  * $FreeBSD$
34  */
35 
36 #include <sys/param.h>
37 #include <sys/eventhandler.h>
38 #include <sys/malloc.h>
39 #include <sys/limits.h>
40 #include <sys/lock.h>
41 #include <sys/mutex.h>
42 #include <sys/kernel.h>
43 #include <sys/systm.h>
44 #include <sys/types.h>
45 #include <sys/socket.h>
46 
47 #include <net/if.h>
48 #include <net/if_var.h>
49 #include <net/if_clone.h>
50 #include <net/radix.h>
51 #include <net/route.h>
52 #include <net/vnet.h>
53 
54 /* Current IF_MAXUNIT expands maximum to 5 characters. */
55 #define	IFCLOSIZ	(IFNAMSIZ - 5)
56 
57 /*
58  * Structure describing a `cloning' interface.
59  *
60  * List of locks
61  * (c)		const until freeing
62  * (d)		driver specific data, may need external protection.
63  * (e)		locked by if_cloners_mtx
64  * (i)		locked by ifc_mtx mtx
65  */
66 struct if_clone {
67 	char ifc_name[IFCLOSIZ];	/* (c) Name of device, e.g. `gif' */
68 	struct unrhdr *ifc_unrhdr;	/* (c) alloc_unr(9) header */
69 	int ifc_maxunit;		/* (c) maximum unit number */
70 	long ifc_refcnt;		/* (i) Reference count. */
71 	LIST_HEAD(, ifnet) ifc_iflist;	/* (i) List of cloned interfaces */
72 	struct mtx ifc_mtx;		/* Mutex to protect members. */
73 
74 	enum { SIMPLE, ADVANCED } ifc_type; /* (c) */
75 
76 	/* (c) Driver specific cloning functions.  Called with no locks held. */
77 	union {
78 		struct {	/* advanced cloner */
79 			ifc_match_t	*_ifc_match;
80 			ifc_create_t	*_ifc_create;
81 			ifc_destroy_t	*_ifc_destroy;
82 		} A;
83 		struct {	/* simple cloner */
84 			ifcs_create_t	*_ifcs_create;
85 			ifcs_destroy_t	*_ifcs_destroy;
86 			int		_ifcs_minifs;	/* minimum ifs */
87 
88 		} S;
89 	} U;
90 #define	ifc_match	U.A._ifc_match
91 #define	ifc_create	U.A._ifc_create
92 #define	ifc_destroy	U.A._ifc_destroy
93 #define	ifcs_create	U.S._ifcs_create
94 #define	ifcs_destroy	U.S._ifcs_destroy
95 #define	ifcs_minifs	U.S._ifcs_minifs
96 
97 	LIST_ENTRY(if_clone) ifc_list;	/* (e) On list of cloners */
98 };
99 
100 static void	if_clone_free(struct if_clone *ifc);
101 static int	if_clone_createif(struct if_clone *ifc, char *name, size_t len,
102 		    caddr_t params);
103 
104 static int     ifc_simple_match(struct if_clone *, const char *);
105 static int     ifc_simple_create(struct if_clone *, char *, size_t, caddr_t);
106 static int     ifc_simple_destroy(struct if_clone *, struct ifnet *);
107 
108 static struct mtx if_cloners_mtx;
109 MTX_SYSINIT(if_cloners_lock, &if_cloners_mtx, "if_cloners lock", MTX_DEF);
110 static VNET_DEFINE(int, if_cloners_count);
111 VNET_DEFINE(LIST_HEAD(, if_clone), if_cloners);
112 
113 #define	V_if_cloners_count	VNET(if_cloners_count)
114 #define	V_if_cloners		VNET(if_cloners)
115 
116 #define IF_CLONERS_LOCK_ASSERT()	mtx_assert(&if_cloners_mtx, MA_OWNED)
117 #define IF_CLONERS_LOCK()		mtx_lock(&if_cloners_mtx)
118 #define IF_CLONERS_UNLOCK()		mtx_unlock(&if_cloners_mtx)
119 
120 #define IF_CLONE_LOCK_INIT(ifc)		\
121     mtx_init(&(ifc)->ifc_mtx, "if_clone lock", NULL, MTX_DEF)
122 #define IF_CLONE_LOCK_DESTROY(ifc)	mtx_destroy(&(ifc)->ifc_mtx)
123 #define IF_CLONE_LOCK_ASSERT(ifc)	mtx_assert(&(ifc)->ifc_mtx, MA_OWNED)
124 #define IF_CLONE_LOCK(ifc)		mtx_lock(&(ifc)->ifc_mtx)
125 #define IF_CLONE_UNLOCK(ifc)		mtx_unlock(&(ifc)->ifc_mtx)
126 
127 #define IF_CLONE_ADDREF(ifc)						\
128 	do {								\
129 		IF_CLONE_LOCK(ifc);					\
130 		IF_CLONE_ADDREF_LOCKED(ifc);				\
131 		IF_CLONE_UNLOCK(ifc);					\
132 	} while (0)
133 #define IF_CLONE_ADDREF_LOCKED(ifc)					\
134 	do {								\
135 		IF_CLONE_LOCK_ASSERT(ifc);				\
136 		KASSERT((ifc)->ifc_refcnt >= 0,				\
137 		    ("negative refcnt %ld", (ifc)->ifc_refcnt));	\
138 		(ifc)->ifc_refcnt++;					\
139 	} while (0)
140 #define IF_CLONE_REMREF(ifc)						\
141 	do {								\
142 		IF_CLONE_LOCK(ifc);					\
143 		IF_CLONE_REMREF_LOCKED(ifc);				\
144 	} while (0)
145 #define IF_CLONE_REMREF_LOCKED(ifc)					\
146 	do {								\
147 		IF_CLONE_LOCK_ASSERT(ifc);				\
148 		KASSERT((ifc)->ifc_refcnt > 0,				\
149 		    ("bogus refcnt %ld", (ifc)->ifc_refcnt));		\
150 		if (--(ifc)->ifc_refcnt == 0) {				\
151 			IF_CLONE_UNLOCK(ifc);				\
152 			if_clone_free(ifc);				\
153 		} else {						\
154 			/* silently free the lock */			\
155 			IF_CLONE_UNLOCK(ifc);				\
156 		}							\
157 	} while (0)
158 
159 #define IFC_IFLIST_INSERT(_ifc, _ifp)					\
160 	LIST_INSERT_HEAD(&_ifc->ifc_iflist, _ifp, if_clones)
161 #define IFC_IFLIST_REMOVE(_ifc, _ifp)					\
162 	LIST_REMOVE(_ifp, if_clones)
163 
164 static MALLOC_DEFINE(M_CLONE, "clone", "interface cloning framework");
165 
166 void
167 vnet_if_clone_init(void)
168 {
169 
170 	LIST_INIT(&V_if_cloners);
171 }
172 
173 /*
174  * Lookup and create a clone network interface.
175  */
176 int
177 if_clone_create(char *name, size_t len, caddr_t params)
178 {
179 	struct if_clone *ifc;
180 
181 	/* Try to find an applicable cloner for this request */
182 	IF_CLONERS_LOCK();
183 	LIST_FOREACH(ifc, &V_if_cloners, ifc_list)
184 		if (ifc->ifc_type == SIMPLE) {
185 			if (ifc_simple_match(ifc, name))
186 				break;
187 		} else {
188 			if (ifc->ifc_match(ifc, name))
189 				break;
190 		}
191 #ifdef VIMAGE
192 	if (ifc == NULL && !IS_DEFAULT_VNET(curvnet)) {
193 		CURVNET_SET_QUIET(vnet0);
194 		LIST_FOREACH(ifc, &V_if_cloners, ifc_list)
195 			if (ifc->ifc_type == SIMPLE) {
196 				if (ifc_simple_match(ifc, name))
197 					break;
198 			} else {
199 				if (ifc->ifc_match(ifc, name))
200 					break;
201 			}
202 		CURVNET_RESTORE();
203 	}
204 #endif
205 	IF_CLONERS_UNLOCK();
206 
207 	if (ifc == NULL)
208 		return (EINVAL);
209 
210 	return (if_clone_createif(ifc, name, len, params));
211 }
212 
213 /*
214  * Create a clone network interface.
215  */
216 static int
217 if_clone_createif(struct if_clone *ifc, char *name, size_t len, caddr_t params)
218 {
219 	int err;
220 	struct ifnet *ifp;
221 
222 	if (ifunit(name) != NULL)
223 		return (EEXIST);
224 
225 	if (ifc->ifc_type == SIMPLE)
226 		err = ifc_simple_create(ifc, name, len, params);
227 	else
228 		err = (*ifc->ifc_create)(ifc, name, len, params);
229 
230 	if (!err) {
231 		ifp = ifunit(name);
232 		if (ifp == NULL)
233 			panic("%s: lookup failed for %s", __func__, name);
234 
235 		if_addgroup(ifp, ifc->ifc_name);
236 
237 		IF_CLONE_LOCK(ifc);
238 		IFC_IFLIST_INSERT(ifc, ifp);
239 		IF_CLONE_UNLOCK(ifc);
240 	}
241 
242 	return (err);
243 }
244 
245 /*
246  * Lookup and destroy a clone network interface.
247  */
248 int
249 if_clone_destroy(const char *name)
250 {
251 	int err;
252 	struct if_clone *ifc;
253 	struct ifnet *ifp;
254 
255 	ifp = ifunit_ref(name);
256 	if (ifp == NULL)
257 		return (ENXIO);
258 
259 	/* Find the cloner for this interface */
260 	IF_CLONERS_LOCK();
261 	LIST_FOREACH(ifc, &V_if_cloners, ifc_list) {
262 		if (strcmp(ifc->ifc_name, ifp->if_dname) == 0) {
263 			break;
264 		}
265 	}
266 #ifdef VIMAGE
267 	if (ifc == NULL && !IS_DEFAULT_VNET(curvnet)) {
268 		CURVNET_SET_QUIET(vnet0);
269 		LIST_FOREACH(ifc, &V_if_cloners, ifc_list)
270 			if (ifc->ifc_type == SIMPLE) {
271 				if (ifc_simple_match(ifc, name))
272 					break;
273 			} else {
274 				if (ifc->ifc_match(ifc, name))
275 					break;
276 			}
277 		CURVNET_RESTORE();
278 	}
279 #endif
280 	IF_CLONERS_UNLOCK();
281 	if (ifc == NULL) {
282 		if_rele(ifp);
283 		return (EINVAL);
284 	}
285 
286 	err = if_clone_destroyif(ifc, ifp);
287 	if_rele(ifp);
288 	return err;
289 }
290 
291 /*
292  * Destroy a clone network interface.
293  */
294 int
295 if_clone_destroyif(struct if_clone *ifc, struct ifnet *ifp)
296 {
297 	int err;
298 	struct ifnet *ifcifp;
299 
300 	if (ifc->ifc_type == ADVANCED && ifc->ifc_destroy == NULL)
301 		return(EOPNOTSUPP);
302 
303 	/*
304 	 * Given that the cloned ifnet might be attached to a different
305 	 * vnet from where its cloner was registered, we have to
306 	 * switch to the vnet context of the target vnet.
307 	 */
308 	CURVNET_SET_QUIET(ifp->if_vnet);
309 
310 	IF_CLONE_LOCK(ifc);
311 	LIST_FOREACH(ifcifp, &ifc->ifc_iflist, if_clones) {
312 		if (ifcifp == ifp) {
313 			IFC_IFLIST_REMOVE(ifc, ifp);
314 			break;
315 		}
316 	}
317 	IF_CLONE_UNLOCK(ifc);
318 	if (ifcifp == NULL) {
319 		CURVNET_RESTORE();
320 		return (ENXIO);		/* ifp is not on the list. */
321 	}
322 
323 	if_delgroup(ifp, ifc->ifc_name);
324 
325 	if (ifc->ifc_type == SIMPLE)
326 		err = ifc_simple_destroy(ifc, ifp);
327 	else
328 		err = (*ifc->ifc_destroy)(ifc, ifp);
329 
330 	if (err != 0) {
331 		if_addgroup(ifp, ifc->ifc_name);
332 
333 		IF_CLONE_LOCK(ifc);
334 		IFC_IFLIST_INSERT(ifc, ifp);
335 		IF_CLONE_UNLOCK(ifc);
336 	}
337 	CURVNET_RESTORE();
338 	return (err);
339 }
340 
341 static struct if_clone *
342 if_clone_alloc(const char *name, int maxunit)
343 {
344 	struct if_clone *ifc;
345 
346 	KASSERT(name != NULL, ("%s: no name\n", __func__));
347 
348 	ifc = malloc(sizeof(struct if_clone), M_CLONE, M_WAITOK | M_ZERO);
349 	strncpy(ifc->ifc_name, name, IFCLOSIZ-1);
350 	IF_CLONE_LOCK_INIT(ifc);
351 	IF_CLONE_ADDREF(ifc);
352 	ifc->ifc_maxunit = maxunit ? maxunit : IF_MAXUNIT;
353 	ifc->ifc_unrhdr = new_unrhdr(0, ifc->ifc_maxunit, &ifc->ifc_mtx);
354 	LIST_INIT(&ifc->ifc_iflist);
355 
356 	return (ifc);
357 }
358 
359 static int
360 if_clone_attach(struct if_clone *ifc)
361 {
362 	struct if_clone *ifc1;
363 
364 	IF_CLONERS_LOCK();
365 	LIST_FOREACH(ifc1, &V_if_cloners, ifc_list)
366 		if (strcmp(ifc->ifc_name, ifc1->ifc_name) == 0) {
367 			IF_CLONERS_UNLOCK();
368 			IF_CLONE_REMREF(ifc);
369 			return (EEXIST);
370 		}
371 	LIST_INSERT_HEAD(&V_if_cloners, ifc, ifc_list);
372 	V_if_cloners_count++;
373 	IF_CLONERS_UNLOCK();
374 
375 	return (0);
376 }
377 
378 struct if_clone *
379 if_clone_advanced(const char *name, u_int maxunit, ifc_match_t match,
380 	ifc_create_t create, ifc_destroy_t destroy)
381 {
382 	struct if_clone *ifc;
383 
384 	ifc = if_clone_alloc(name, maxunit);
385 	ifc->ifc_type = ADVANCED;
386 	ifc->ifc_match = match;
387 	ifc->ifc_create = create;
388 	ifc->ifc_destroy = destroy;
389 
390 	if (if_clone_attach(ifc) != 0) {
391 		if_clone_free(ifc);
392 		return (NULL);
393 	}
394 
395 	EVENTHANDLER_INVOKE(if_clone_event, ifc);
396 
397 	return (ifc);
398 }
399 
400 struct if_clone *
401 if_clone_simple(const char *name, ifcs_create_t create, ifcs_destroy_t destroy,
402 	u_int minifs)
403 {
404 	struct if_clone *ifc;
405 	u_int unit;
406 
407 	ifc = if_clone_alloc(name, 0);
408 	ifc->ifc_type = SIMPLE;
409 	ifc->ifcs_create = create;
410 	ifc->ifcs_destroy = destroy;
411 	ifc->ifcs_minifs = minifs;
412 
413 	if (if_clone_attach(ifc) != 0) {
414 		if_clone_free(ifc);
415 		return (NULL);
416 	}
417 
418 	for (unit = 0; unit < minifs; unit++) {
419 		char name[IFNAMSIZ];
420 		int error;
421 
422 		snprintf(name, IFNAMSIZ, "%s%d", ifc->ifc_name, unit);
423 		error = if_clone_createif(ifc, name, IFNAMSIZ, NULL);
424 		KASSERT(error == 0,
425 		    ("%s: failed to create required interface %s",
426 		    __func__, name));
427 	}
428 
429 	EVENTHANDLER_INVOKE(if_clone_event, ifc);
430 
431 	return (ifc);
432 }
433 
434 /*
435  * Unregister a network interface cloner.
436  */
437 void
438 if_clone_detach(struct if_clone *ifc)
439 {
440 
441 	IF_CLONERS_LOCK();
442 	LIST_REMOVE(ifc, ifc_list);
443 	V_if_cloners_count--;
444 	IF_CLONERS_UNLOCK();
445 
446 	/* Allow all simples to be destroyed */
447 	if (ifc->ifc_type == SIMPLE)
448 		ifc->ifcs_minifs = 0;
449 
450 	/* destroy all interfaces for this cloner */
451 	while (!LIST_EMPTY(&ifc->ifc_iflist))
452 		if_clone_destroyif(ifc, LIST_FIRST(&ifc->ifc_iflist));
453 
454 	IF_CLONE_REMREF(ifc);
455 }
456 
457 static void
458 if_clone_free(struct if_clone *ifc)
459 {
460 
461 	KASSERT(LIST_EMPTY(&ifc->ifc_iflist),
462 	    ("%s: ifc_iflist not empty", __func__));
463 
464 	IF_CLONE_LOCK_DESTROY(ifc);
465 	delete_unrhdr(ifc->ifc_unrhdr);
466 	free(ifc, M_CLONE);
467 }
468 
469 /*
470  * Provide list of interface cloners to userspace.
471  */
472 int
473 if_clone_list(struct if_clonereq *ifcr)
474 {
475 	char *buf, *dst, *outbuf = NULL;
476 	struct if_clone *ifc;
477 	int buf_count, count, err = 0;
478 
479 	if (ifcr->ifcr_count < 0)
480 		return (EINVAL);
481 
482 	IF_CLONERS_LOCK();
483 	/*
484 	 * Set our internal output buffer size.  We could end up not
485 	 * reporting a cloner that is added between the unlock and lock
486 	 * below, but that's not a major problem.  Not caping our
487 	 * allocation to the number of cloners actually in the system
488 	 * could be because that would let arbitrary users cause us to
489 	 * allocate arbitrary amounts of kernel memory.
490 	 */
491 	buf_count = (V_if_cloners_count < ifcr->ifcr_count) ?
492 	    V_if_cloners_count : ifcr->ifcr_count;
493 	IF_CLONERS_UNLOCK();
494 
495 	outbuf = malloc(IFNAMSIZ*buf_count, M_CLONE, M_WAITOK | M_ZERO);
496 
497 	IF_CLONERS_LOCK();
498 
499 	ifcr->ifcr_total = V_if_cloners_count;
500 	if ((dst = ifcr->ifcr_buffer) == NULL) {
501 		/* Just asking how many there are. */
502 		goto done;
503 	}
504 	count = (V_if_cloners_count < buf_count) ?
505 	    V_if_cloners_count : buf_count;
506 
507 	for (ifc = LIST_FIRST(&V_if_cloners), buf = outbuf;
508 	    ifc != NULL && count != 0;
509 	    ifc = LIST_NEXT(ifc, ifc_list), count--, buf += IFNAMSIZ) {
510 		strlcpy(buf, ifc->ifc_name, IFNAMSIZ);
511 	}
512 
513 done:
514 	IF_CLONERS_UNLOCK();
515 	if (err == 0)
516 		err = copyout(outbuf, dst, buf_count*IFNAMSIZ);
517 	if (outbuf != NULL)
518 		free(outbuf, M_CLONE);
519 	return (err);
520 }
521 
522 /*
523  * if_clone_findifc() looks up ifnet from the current
524  * cloner list, and returns ifc if found.  Note that ifc_refcnt
525  * is incremented.
526  */
527 struct if_clone *
528 if_clone_findifc(struct ifnet *ifp)
529 {
530 	struct if_clone *ifc, *ifc0;
531 	struct ifnet *ifcifp;
532 
533 	ifc0 = NULL;
534 	IF_CLONERS_LOCK();
535 	LIST_FOREACH(ifc, &V_if_cloners, ifc_list) {
536 		IF_CLONE_LOCK(ifc);
537 		LIST_FOREACH(ifcifp, &ifc->ifc_iflist, if_clones) {
538 			if (ifp == ifcifp) {
539 				ifc0 = ifc;
540 				IF_CLONE_ADDREF_LOCKED(ifc);
541 				break;
542 			}
543 		}
544 		IF_CLONE_UNLOCK(ifc);
545 		if (ifc0 != NULL)
546 			break;
547 	}
548 	IF_CLONERS_UNLOCK();
549 
550 	return (ifc0);
551 }
552 
553 /*
554  * if_clone_addgroup() decrements ifc_refcnt because it is called after
555  * if_clone_findifc().
556  */
557 void
558 if_clone_addgroup(struct ifnet *ifp, struct if_clone *ifc)
559 {
560 
561 	if_addgroup(ifp, ifc->ifc_name);
562 	IF_CLONE_REMREF(ifc);
563 }
564 
565 /*
566  * A utility function to extract unit numbers from interface names of
567  * the form name###.
568  *
569  * Returns 0 on success and an error on failure.
570  */
571 int
572 ifc_name2unit(const char *name, int *unit)
573 {
574 	const char	*cp;
575 	int		cutoff = INT_MAX / 10;
576 	int		cutlim = INT_MAX % 10;
577 
578 	for (cp = name; *cp != '\0' && (*cp < '0' || *cp > '9'); cp++);
579 	if (*cp == '\0') {
580 		*unit = -1;
581 	} else if (cp[0] == '0' && cp[1] != '\0') {
582 		/* Disallow leading zeroes. */
583 		return (EINVAL);
584 	} else {
585 		for (*unit = 0; *cp != '\0'; cp++) {
586 			if (*cp < '0' || *cp > '9') {
587 				/* Bogus unit number. */
588 				return (EINVAL);
589 			}
590 			if (*unit > cutoff ||
591 			    (*unit == cutoff && *cp - '0' > cutlim))
592 				return (EINVAL);
593 			*unit = (*unit * 10) + (*cp - '0');
594 		}
595 	}
596 
597 	return (0);
598 }
599 
600 static int
601 ifc_alloc_unit_specific(struct if_clone *ifc, int *unit)
602 {
603 	char name[IFNAMSIZ];
604 
605 	if (*unit > ifc->ifc_maxunit)
606 		return (ENOSPC);
607 
608 	if (alloc_unr_specific(ifc->ifc_unrhdr, *unit) == -1)
609 		return (EEXIST);
610 
611 	snprintf(name, IFNAMSIZ, "%s%d", ifc->ifc_name, *unit);
612 	if (ifunit(name) != NULL) {
613 		free_unr(ifc->ifc_unrhdr, *unit);
614 		return (EEXIST);
615 	}
616 
617 	IF_CLONE_ADDREF(ifc);
618 
619 	return (0);
620 }
621 
622 static int
623 ifc_alloc_unit_next(struct if_clone *ifc, int *unit)
624 {
625 	int error;
626 
627 	*unit = alloc_unr(ifc->ifc_unrhdr);
628 	if (*unit == -1)
629 		return (ENOSPC);
630 
631 	free_unr(ifc->ifc_unrhdr, *unit);
632 	for (;;) {
633 		error = ifc_alloc_unit_specific(ifc, unit);
634 		if (error != EEXIST)
635 			break;
636 
637 		(*unit)++;
638 	}
639 
640 	return (error);
641 }
642 
643 int
644 ifc_alloc_unit(struct if_clone *ifc, int *unit)
645 {
646 	if (*unit < 0)
647 		return (ifc_alloc_unit_next(ifc, unit));
648 	else
649 		return (ifc_alloc_unit_specific(ifc, unit));
650 }
651 
652 void
653 ifc_free_unit(struct if_clone *ifc, int unit)
654 {
655 
656 	free_unr(ifc->ifc_unrhdr, unit);
657 	IF_CLONE_REMREF(ifc);
658 }
659 
660 static int
661 ifc_simple_match(struct if_clone *ifc, const char *name)
662 {
663 	const char *cp;
664 	int i;
665 
666 	/* Match the name */
667 	for (cp = name, i = 0; i < strlen(ifc->ifc_name); i++, cp++) {
668 		if (ifc->ifc_name[i] != *cp)
669 			return (0);
670 	}
671 
672 	/* Make sure there's a unit number or nothing after the name */
673 	for (; *cp != '\0'; cp++) {
674 		if (*cp < '0' || *cp > '9')
675 			return (0);
676 	}
677 
678 	return (1);
679 }
680 
681 static int
682 ifc_simple_create(struct if_clone *ifc, char *name, size_t len, caddr_t params)
683 {
684 	char *dp;
685 	int wildcard;
686 	int unit;
687 	int err;
688 
689 	err = ifc_name2unit(name, &unit);
690 	if (err != 0)
691 		return (err);
692 
693 	wildcard = (unit < 0);
694 
695 	err = ifc_alloc_unit(ifc, &unit);
696 	if (err != 0)
697 		return (err);
698 
699 	err = ifc->ifcs_create(ifc, unit, params);
700 	if (err != 0) {
701 		ifc_free_unit(ifc, unit);
702 		return (err);
703 	}
704 
705 	/* In the wildcard case, we need to update the name. */
706 	if (wildcard) {
707 		for (dp = name; *dp != '\0'; dp++);
708 		if (snprintf(dp, len - (dp-name), "%d", unit) >
709 		    len - (dp-name) - 1) {
710 			/*
711 			 * This can only be a programmer error and
712 			 * there's no straightforward way to recover if
713 			 * it happens.
714 			 */
715 			panic("if_clone_create(): interface name too long");
716 		}
717 
718 	}
719 
720 	return (0);
721 }
722 
723 static int
724 ifc_simple_destroy(struct if_clone *ifc, struct ifnet *ifp)
725 {
726 	int unit;
727 
728 	unit = ifp->if_dunit;
729 
730 	if (unit < ifc->ifcs_minifs)
731 		return (EINVAL);
732 
733 	ifc->ifcs_destroy(ifp);
734 
735 	ifc_free_unit(ifc, unit);
736 
737 	return (0);
738 }
739