xref: /freebsd/sys/kern/vfs_export.c (revision d686ce931cab72612a9e1ada9fe99d65e11a32a3)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (c) 1989, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  * (c) UNIX System Laboratories, Inc.
7  * All or some portions of this file are derived from material licensed
8  * to the University of California by American Telephone and Telegraph
9  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
10  * the permission of UNIX System Laboratories, Inc.
11  *
12  * Redistribution and use in source and binary forms, with or without
13  * modification, are permitted provided that the following conditions
14  * are met:
15  * 1. Redistributions of source code must retain the above copyright
16  *    notice, this list of conditions and the following disclaimer.
17  * 2. Redistributions in binary form must reproduce the above copyright
18  *    notice, this list of conditions and the following disclaimer in the
19  *    documentation and/or other materials provided with the distribution.
20  * 3. Neither the name of the University nor the names of its contributors
21  *    may be used to endorse or promote products derived from this software
22  *    without specific prior written permission.
23  *
24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34  * SUCH DAMAGE.
35  */
36 
37 #include <sys/cdefs.h>
38 #include "opt_inet.h"
39 #include "opt_inet6.h"
40 
41 #include <sys/param.h>
42 #include <sys/systm.h>
43 #include <sys/conf.h>
44 #include <sys/dirent.h>
45 #include <sys/jail.h>
46 #include <sys/kernel.h>
47 #include <sys/lock.h>
48 #include <sys/malloc.h>
49 #include <sys/mbuf.h>
50 #include <sys/mount.h>
51 #include <sys/mutex.h>
52 #include <sys/proc.h>
53 #include <sys/rmlock.h>
54 #include <sys/refcount.h>
55 #include <sys/signalvar.h>
56 #include <sys/socket.h>
57 #include <sys/vnode.h>
58 
59 #include <netinet/in.h>
60 #include <net/radix.h>
61 
62 #include <rpc/types.h>
63 #include <rpc/auth.h>
64 
65 static MALLOC_DEFINE(M_NETADDR, "export_host", "Export host address structure");
66 
67 #if defined(INET) || defined(INET6)
68 static struct radix_node_head *vfs_create_addrlist_af(
69 		    struct radix_node_head **prnh, int off);
70 #endif
71 static int	vfs_free_netcred(struct radix_node *rn, void *w);
72 static void	vfs_free_addrlist_af(struct radix_node_head **prnh);
73 static int	vfs_hang_addrlist(struct mount *mp, struct netexport *nep,
74 		    struct export_args *argp);
75 static struct netcred *vfs_export_lookup(struct mount *, struct sockaddr *);
76 
77 /*
78  * Network address lookup element
79  */
80 struct netcred {
81 	struct	radix_node netc_rnodes[2];
82 	uint64_t netc_exflags;
83 	struct	ucred *netc_anon;
84 	int	netc_numsecflavors;
85 	int	netc_secflavors[MAXSECFLAVORS];
86 };
87 
88 /*
89  * Network export information
90  */
91 struct netexport {
92 	struct	netcred ne_defexported;		      /* Default export */
93 	struct 	radix_node_head	*ne4;
94 	struct 	radix_node_head	*ne6;
95 };
96 
97 /*
98  * Build hash lists of net addresses and hang them off the mount point.
99  * Called by vfs_export() to set up the lists of export addresses.
100  */
101 static int
102 vfs_hang_addrlist(struct mount *mp, struct netexport *nep,
103     struct export_args *argp)
104 {
105 	struct netcred *np;
106 	struct radix_node_head *rnh;
107 	int i;
108 	struct radix_node *rn;
109 	struct sockaddr *saddr, *smask = NULL;
110 #if defined(INET6) || defined(INET)
111 	int off;
112 #endif
113 	int error;
114 
115 	KASSERT(argp->ex_numsecflavors > 0,
116 	    ("%s: numsecflavors <= 0", __func__));
117 	KASSERT(argp->ex_numsecflavors < MAXSECFLAVORS,
118 	    ("%s: numsecflavors >= MAXSECFLAVORS", __func__));
119 
120 	/*
121 	 * XXX: This routine converts from a uid plus gid list
122 	 * to a `struct ucred' (np->netc_anon).  This
123 	 * operation is questionable; for example, what should be done
124 	 * with fields like cr_uidinfo and cr_prison?  Currently, this
125 	 * routine does not touch them (leaves them as NULL).
126 	 */
127 	if (argp->ex_addrlen == 0) {
128 		if (mp->mnt_flag & MNT_DEFEXPORTED) {
129 			vfs_mount_error(mp,
130 			    "MNT_DEFEXPORTED already set for mount %p", mp);
131 			return (EPERM);
132 		}
133 		np = &nep->ne_defexported;
134 		np->netc_exflags = argp->ex_flags;
135 		np->netc_anon = crget();
136 		np->netc_anon->cr_uid = argp->ex_uid;
137 		crsetgroups_fallback(np->netc_anon, argp->ex_ngroups,
138 		    argp->ex_groups, GID_NOGROUP);
139 		np->netc_anon->cr_prison = &prison0;
140 		prison_hold(np->netc_anon->cr_prison);
141 		np->netc_numsecflavors = argp->ex_numsecflavors;
142 		bcopy(argp->ex_secflavors, np->netc_secflavors,
143 		    sizeof(np->netc_secflavors));
144 		MNT_ILOCK(mp);
145 		mp->mnt_flag |= MNT_DEFEXPORTED;
146 		MNT_IUNLOCK(mp);
147 		return (0);
148 	}
149 
150 #if MSIZE <= 256
151 	if (argp->ex_addrlen > MLEN) {
152 		vfs_mount_error(mp, "ex_addrlen %d is greater than %d",
153 		    argp->ex_addrlen, MLEN);
154 		return (EINVAL);
155 	}
156 #endif
157 
158 	i = sizeof(struct netcred) + argp->ex_addrlen + argp->ex_masklen;
159 	np = (struct netcred *) malloc(i, M_NETADDR, M_WAITOK | M_ZERO);
160 	saddr = (struct sockaddr *) (np + 1);
161 	if ((error = copyin(argp->ex_addr, saddr, argp->ex_addrlen)))
162 		goto out;
163 	if (saddr->sa_family == AF_UNSPEC || saddr->sa_family > AF_MAX) {
164 		error = EINVAL;
165 		vfs_mount_error(mp, "Invalid saddr->sa_family: %d");
166 		goto out;
167 	}
168 	if (saddr->sa_len > argp->ex_addrlen)
169 		saddr->sa_len = argp->ex_addrlen;
170 	if (argp->ex_masklen) {
171 		smask = (struct sockaddr *)((caddr_t)saddr + argp->ex_addrlen);
172 		error = copyin(argp->ex_mask, smask, argp->ex_masklen);
173 		if (error)
174 			goto out;
175 		if (smask->sa_len > argp->ex_masklen)
176 			smask->sa_len = argp->ex_masklen;
177 	}
178 	rnh = NULL;
179 	switch (saddr->sa_family) {
180 #ifdef INET
181 	case AF_INET:
182 		if ((rnh = nep->ne4) == NULL) {
183 			off = offsetof(struct sockaddr_in, sin_addr) << 3;
184 			rnh = vfs_create_addrlist_af(&nep->ne4, off);
185 		}
186 		break;
187 #endif
188 #ifdef INET6
189 	case AF_INET6:
190 		if ((rnh = nep->ne6) == NULL) {
191 			off = offsetof(struct sockaddr_in6, sin6_addr) << 3;
192 			rnh = vfs_create_addrlist_af(&nep->ne6, off);
193 		}
194 		break;
195 #endif
196 	}
197 	if (rnh == NULL) {
198 		error = ENOBUFS;
199 		vfs_mount_error(mp, "%s %s %d",
200 		    "Unable to initialize radix node head ",
201 		    "for address family", saddr->sa_family);
202 		goto out;
203 	}
204 	RADIX_NODE_HEAD_LOCK(rnh);
205 	rn = (*rnh->rnh_addaddr)(saddr, smask, &rnh->rh, np->netc_rnodes);
206 	RADIX_NODE_HEAD_UNLOCK(rnh);
207 	if (rn == NULL || np != (struct netcred *)rn) {	/* already exists */
208 		error = EPERM;
209 		vfs_mount_error(mp,
210 		    "netcred already exists for given addr/mask");
211 		goto out;
212 	}
213 	np->netc_exflags = argp->ex_flags;
214 	np->netc_anon = crget();
215 	np->netc_anon->cr_uid = argp->ex_uid;
216 	crsetgroups_fallback(np->netc_anon, argp->ex_ngroups, argp->ex_groups,
217 	    GID_NOGROUP);
218 	np->netc_anon->cr_prison = &prison0;
219 	prison_hold(np->netc_anon->cr_prison);
220 	np->netc_numsecflavors = argp->ex_numsecflavors;
221 	bcopy(argp->ex_secflavors, np->netc_secflavors,
222 	    sizeof(np->netc_secflavors));
223 	return (0);
224 out:
225 	free(np, M_NETADDR);
226 	return (error);
227 }
228 
229 /* Helper for vfs_free_addrlist. */
230 /* ARGSUSED */
231 static int
232 vfs_free_netcred(struct radix_node *rn, void *w)
233 {
234 	struct radix_node_head *rnh = (struct radix_node_head *) w;
235 	struct ucred *cred;
236 
237 	(*rnh->rnh_deladdr) (rn->rn_key, rn->rn_mask, &rnh->rh);
238 	cred = ((struct netcred *)rn)->netc_anon;
239 	if (cred != NULL)
240 		crfree(cred);
241 	free(rn, M_NETADDR);
242 	return (0);
243 }
244 
245 #if defined(INET) || defined(INET6)
246 static struct radix_node_head *
247 vfs_create_addrlist_af(struct radix_node_head **prnh, int off)
248 {
249 
250 	if (rn_inithead((void **)prnh, off) == 0)
251 		return (NULL);
252 	RADIX_NODE_HEAD_LOCK_INIT(*prnh);
253 	return (*prnh);
254 }
255 #endif
256 
257 static void
258 vfs_free_addrlist_af(struct radix_node_head **prnh)
259 {
260 	struct radix_node_head *rnh;
261 
262 	rnh = *prnh;
263 	RADIX_NODE_HEAD_LOCK(rnh);
264 	(*rnh->rnh_walktree)(&rnh->rh, vfs_free_netcred, rnh);
265 	RADIX_NODE_HEAD_UNLOCK(rnh);
266 	RADIX_NODE_HEAD_DESTROY(rnh);
267 	rn_detachhead((void **)prnh);
268 	prnh = NULL;
269 }
270 
271 /*
272  * Free the net address hash lists that are hanging off the mount points.
273  */
274 void
275 vfs_free_addrlist(struct netexport *nep)
276 {
277 	struct ucred *cred;
278 
279 	if (nep->ne4 != NULL)
280 		vfs_free_addrlist_af(&nep->ne4);
281 	if (nep->ne6 != NULL)
282 		vfs_free_addrlist_af(&nep->ne6);
283 
284 	cred = nep->ne_defexported.netc_anon;
285 	if (cred != NULL) {
286 		crfree(cred);
287 		nep->ne_defexported.netc_anon = NULL;
288 	}
289 
290 }
291 
292 /*
293  * High level function to manipulate export options on a mount point
294  * and the passed in netexport.
295  * Struct export_args *argp is the variable used to twiddle options,
296  * the structure is described in sys/mount.h
297  * The do_exjail argument should be true if *mp is in the mountlist
298  * and false if not.  It is not in the mountlist for the NFSv4 rootfs
299  * fake mount point just used for exports.
300  */
301 int
302 vfs_export(struct mount *mp, struct export_args *argp, bool do_exjail)
303 {
304 	struct netexport *nep;
305 	struct ucred *cr;
306 	struct prison *pr;
307 	int error;
308 	bool new_nep;
309 
310 	if ((argp->ex_flags & (MNT_DELEXPORT | MNT_EXPORTED)) == 0)
311 		return (EINVAL);
312 
313 	if ((argp->ex_flags & MNT_EXPORTED) != 0 &&
314 	    (argp->ex_numsecflavors < 0
315 	    || argp->ex_numsecflavors >= MAXSECFLAVORS))
316 		return (EINVAL);
317 
318 	error = 0;
319 	pr = curthread->td_ucred->cr_prison;
320 	lockmgr(&mp->mnt_explock, LK_EXCLUSIVE, NULL);
321 	nep = mp->mnt_export;
322 	if (argp->ex_flags & MNT_DELEXPORT) {
323 		if (nep == NULL) {
324 			error = ENOENT;
325 			goto out;
326 		}
327 		MNT_ILOCK(mp);
328 		if (mp->mnt_exjail != NULL && mp->mnt_exjail->cr_prison != pr &&
329 		    pr == &prison0) {
330 			MNT_IUNLOCK(mp);
331 			/* EXDEV will not get logged by mountd(8). */
332 			error = EXDEV;
333 			goto out;
334 		} else if (mp->mnt_exjail != NULL &&
335 		    mp->mnt_exjail->cr_prison != pr) {
336 			MNT_IUNLOCK(mp);
337 			/* EPERM will get logged by mountd(8). */
338 			error = EPERM;
339 			goto out;
340 		}
341 		MNT_IUNLOCK(mp);
342 		if (mp->mnt_flag & MNT_EXPUBLIC) {
343 			vfs_setpublicfs(NULL, NULL, NULL);
344 			MNT_ILOCK(mp);
345 			mp->mnt_flag &= ~MNT_EXPUBLIC;
346 			MNT_IUNLOCK(mp);
347 		}
348 		vfs_free_addrlist(nep);
349 		mp->mnt_export = NULL;
350 		free(nep, M_MOUNT);
351 		nep = NULL;
352 		MNT_ILOCK(mp);
353 		cr = mp->mnt_exjail;
354 		mp->mnt_exjail = NULL;
355 		mp->mnt_flag &= ~(MNT_EXPORTED | MNT_DEFEXPORTED);
356 		MNT_IUNLOCK(mp);
357 		if (cr != NULL) {
358 			atomic_subtract_int(&pr->pr_exportcnt, 1);
359 			crfree(cr);
360 		}
361 	}
362 	if (argp->ex_flags & MNT_EXPORTED) {
363 		new_nep = false;
364 		MNT_ILOCK(mp);
365 		if (mp->mnt_exjail == NULL) {
366 			MNT_IUNLOCK(mp);
367 			if (do_exjail && nep != NULL) {
368 				vfs_free_addrlist(nep);
369 				memset(nep, 0, sizeof(*nep));
370 				new_nep = true;
371 			}
372 		} else if (mp->mnt_exjail->cr_prison != pr) {
373 			MNT_IUNLOCK(mp);
374 			error = EPERM;
375 			goto out;
376 		} else
377 			MNT_IUNLOCK(mp);
378 		if (nep == NULL) {
379 			nep = malloc(sizeof(struct netexport), M_MOUNT,
380 			    M_WAITOK | M_ZERO);
381 			mp->mnt_export = nep;
382 			new_nep = true;
383 		}
384 		if (argp->ex_flags & MNT_EXPUBLIC) {
385 			if ((error = vfs_setpublicfs(mp, nep, argp)) != 0) {
386 				if (new_nep) {
387 					mp->mnt_export = NULL;
388 					free(nep, M_MOUNT);
389 				}
390 				goto out;
391 			}
392 			new_nep = false;
393 			MNT_ILOCK(mp);
394 			if (do_exjail && mp->mnt_exjail == NULL) {
395 				mp->mnt_exjail = crhold(curthread->td_ucred);
396 				atomic_add_int(&pr->pr_exportcnt, 1);
397 			}
398 			mp->mnt_flag |= MNT_EXPUBLIC;
399 			MNT_IUNLOCK(mp);
400 		}
401 		if (argp->ex_numsecflavors == 0) {
402 			argp->ex_numsecflavors = 1;
403 			argp->ex_secflavors[0] = AUTH_SYS;
404 		}
405 		if ((error = vfs_hang_addrlist(mp, nep, argp))) {
406 			if (new_nep) {
407 				mp->mnt_export = NULL;
408 				free(nep, M_MOUNT);
409 			}
410 			goto out;
411 		}
412 		MNT_ILOCK(mp);
413 		if (do_exjail && mp->mnt_exjail == NULL) {
414 			mp->mnt_exjail = crhold(curthread->td_ucred);
415 			atomic_add_int(&pr->pr_exportcnt, 1);
416 		}
417 		mp->mnt_flag |= MNT_EXPORTED;
418 		MNT_IUNLOCK(mp);
419 	}
420 
421 out:
422 	lockmgr(&mp->mnt_explock, LK_RELEASE, NULL);
423 	/*
424 	 * Once we have executed the vfs_export() command, we do
425 	 * not want to keep the "export" option around in the
426 	 * options list, since that will cause subsequent MNT_UPDATE
427 	 * calls to fail.  The export information is saved in
428 	 * mp->mnt_export, so we can safely delete the "export" mount option
429 	 * here.
430 	 */
431 	vfs_deleteopt(mp->mnt_optnew, "export");
432 	vfs_deleteopt(mp->mnt_opt, "export");
433 	return (error);
434 }
435 
436 /*
437  * Get rid of credential references for this prison.
438  */
439 void
440 vfs_exjail_delete(struct prison *pr)
441 {
442 	struct mount *mp;
443 	struct ucred *cr;
444 	int error, i;
445 
446 	/*
447 	 * Since this function is called from prison_cleanup() after
448 	 * all processes in the prison have exited, the value of
449 	 * pr_exportcnt can no longer increase.  It is possible for
450 	 * a dismount of a file system exported within this prison
451 	 * to be in progress.  In this case, the file system is no
452 	 * longer in the mountlist and the mnt_exjail will be free'd
453 	 * by vfs_mount_destroy() at some time.  As such, pr_exportcnt
454 	 * and, therefore "i", is the upper bound on the number of
455 	 * mnt_exjail entries to be found by this function.
456 	 */
457 	i = atomic_load_int(&pr->pr_exportcnt);
458 	KASSERT(i >= 0, ("vfs_exjail_delete: pr_exportcnt negative"));
459 	if (i == 0)
460 		return;
461 	mtx_lock(&mountlist_mtx);
462 tryagain:
463 	TAILQ_FOREACH(mp, &mountlist, mnt_list) {
464 		MNT_ILOCK(mp);
465 		if (mp->mnt_exjail != NULL &&
466 		    mp->mnt_exjail->cr_prison == pr) {
467 			MNT_IUNLOCK(mp);
468 			error = vfs_busy(mp, MBF_MNTLSTLOCK | MBF_NOWAIT);
469 			if (error != 0) {
470 				/*
471 				 * If the vfs_busy() fails, we still want to
472 				 * get rid of mnt_exjail for two reasons:
473 				 * - a credential reference will result in
474 				 *   a prison not being removed
475 				 * - setting mnt_exjail NULL indicates that
476 				 *   the exports are no longer valid
477 				 * The now invalid exports will be deleted
478 				 * when the file system is dismounted or
479 				 * the file system is re-exported by mountd.
480 				 */
481 				cr = NULL;
482 				MNT_ILOCK(mp);
483 				if (mp->mnt_exjail != NULL &&
484 				    mp->mnt_exjail->cr_prison == pr) {
485 					cr = mp->mnt_exjail;
486 					mp->mnt_exjail = NULL;
487 				}
488 				MNT_IUNLOCK(mp);
489 				if (cr != NULL) {
490 					crfree(cr);
491 					i--;
492 				}
493 				if (i == 0)
494 					break;
495 				continue;
496 			}
497 			cr = NULL;
498 			lockmgr(&mp->mnt_explock, LK_EXCLUSIVE, NULL);
499 			MNT_ILOCK(mp);
500 			if (mp->mnt_exjail != NULL &&
501 			    mp->mnt_exjail->cr_prison == pr) {
502 				cr = mp->mnt_exjail;
503 				mp->mnt_exjail = NULL;
504 				mp->mnt_flag &= ~(MNT_EXPORTED | MNT_DEFEXPORTED);
505 				MNT_IUNLOCK(mp);
506 				vfs_free_addrlist(mp->mnt_export);
507 				free(mp->mnt_export, M_MOUNT);
508 				mp->mnt_export = NULL;
509 			} else
510 				MNT_IUNLOCK(mp);
511 			lockmgr(&mp->mnt_explock, LK_RELEASE, NULL);
512 			if (cr != NULL) {
513 				crfree(cr);
514 				i--;
515 			}
516 			mtx_lock(&mountlist_mtx);
517 			vfs_unbusy(mp);
518 			if (i == 0)
519 				break;
520 			goto tryagain;
521 		}
522 		MNT_IUNLOCK(mp);
523 	}
524 	mtx_unlock(&mountlist_mtx);
525 }
526 
527 /*
528  * Set the publicly exported filesystem (WebNFS). Currently, only
529  * one public filesystem is possible in the spec (RFC 2054 and 2055)
530  */
531 int
532 vfs_setpublicfs(struct mount *mp, struct netexport *nep,
533     struct export_args *argp)
534 {
535 	int error;
536 	struct vnode *rvp;
537 	char *cp;
538 
539 	/*
540 	 * mp == NULL -> invalidate the current info, the FS is
541 	 * no longer exported. May be called from either vfs_export
542 	 * or unmount, so check if it hasn't already been done.
543 	 */
544 	if (mp == NULL) {
545 		if (nfs_pub.np_valid) {
546 			nfs_pub.np_valid = 0;
547 			if (nfs_pub.np_index != NULL) {
548 				free(nfs_pub.np_index, M_TEMP);
549 				nfs_pub.np_index = NULL;
550 			}
551 		}
552 		return (0);
553 	}
554 
555 	/*
556 	 * Only one allowed at a time.
557 	 */
558 	if (nfs_pub.np_valid != 0 && mp != nfs_pub.np_mount)
559 		return (EBUSY);
560 
561 	/*
562 	 * Get real filehandle for root of exported FS.
563 	 */
564 	bzero(&nfs_pub.np_handle, sizeof(nfs_pub.np_handle));
565 	nfs_pub.np_handle.fh_fsid = mp->mnt_stat.f_fsid;
566 
567 	if ((error = VFS_ROOT(mp, LK_EXCLUSIVE, &rvp)))
568 		return (error);
569 
570 	if ((error = VOP_VPTOFH(rvp, &nfs_pub.np_handle.fh_fid)))
571 		return (error);
572 
573 	vput(rvp);
574 
575 	/*
576 	 * If an indexfile was specified, pull it in.
577 	 */
578 	if (argp->ex_indexfile != NULL) {
579 		if (nfs_pub.np_index == NULL)
580 			nfs_pub.np_index = malloc(MAXNAMLEN + 1, M_TEMP,
581 			    M_WAITOK);
582 		error = copyinstr(argp->ex_indexfile, nfs_pub.np_index,
583 		    MAXNAMLEN, (size_t *)0);
584 		if (!error) {
585 			/*
586 			 * Check for illegal filenames.
587 			 */
588 			for (cp = nfs_pub.np_index; *cp; cp++) {
589 				if (*cp == '/') {
590 					error = EINVAL;
591 					break;
592 				}
593 			}
594 		}
595 		if (error) {
596 			free(nfs_pub.np_index, M_TEMP);
597 			nfs_pub.np_index = NULL;
598 			return (error);
599 		}
600 	}
601 
602 	nfs_pub.np_mount = mp;
603 	nfs_pub.np_valid = 1;
604 	return (0);
605 }
606 
607 /*
608  * Used by the filesystems to determine if a given network address
609  * (passed in 'nam') is present in their exports list, returns a pointer
610  * to struct netcred so that the filesystem can examine it for
611  * access rights (read/write/etc).
612  */
613 static struct netcred *
614 vfs_export_lookup(struct mount *mp, struct sockaddr *nam)
615 {
616 	RADIX_NODE_HEAD_RLOCK_TRACKER;
617 	struct netexport *nep;
618 	struct netcred *np = NULL;
619 	struct radix_node_head *rnh;
620 	struct sockaddr *saddr;
621 
622 	nep = mp->mnt_export;
623 	if (nep == NULL)
624 		return (NULL);
625 	if ((mp->mnt_flag & MNT_EXPORTED) == 0)
626 		return (NULL);
627 
628 	/*
629 	 * Lookup in the export list
630 	 */
631 	if (nam != NULL) {
632 		saddr = nam;
633 		rnh = NULL;
634 		switch (saddr->sa_family) {
635 		case AF_INET:
636 			rnh = nep->ne4;
637 			break;
638 		case AF_INET6:
639 			rnh = nep->ne6;
640 			break;
641 		}
642 		if (rnh != NULL) {
643 			RADIX_NODE_HEAD_RLOCK(rnh);
644 			np = (struct netcred *) (*rnh->rnh_matchaddr)(saddr, &rnh->rh);
645 			RADIX_NODE_HEAD_RUNLOCK(rnh);
646 			if (np != NULL && (np->netc_rnodes->rn_flags & RNF_ROOT) != 0)
647 				return (NULL);
648 		}
649 	}
650 
651 	/*
652 	 * If no address match, use the default if it exists.
653 	 */
654 	if (np == NULL && (mp->mnt_flag & MNT_DEFEXPORTED) != 0)
655 		return (&nep->ne_defexported);
656 
657 	return (np);
658 }
659 
660 /*
661  * XXX: This comment comes from the deprecated ufs_check_export()
662  * XXX: and may not entirely apply, but lacking something better:
663  * This is the generic part of fhtovp called after the underlying
664  * filesystem has validated the file handle.
665  *
666  * Verify that a host should have access to a filesystem.
667  */
668 
669 int
670 vfs_stdcheckexp(struct mount *mp, struct sockaddr *nam, uint64_t *extflagsp,
671     struct ucred **credanonp, int *numsecflavors, int *secflavors)
672 {
673 	struct netcred *np;
674 
675 	lockmgr(&mp->mnt_explock, LK_SHARED, NULL);
676 	np = vfs_export_lookup(mp, nam);
677 	if (np == NULL) {
678 		lockmgr(&mp->mnt_explock, LK_RELEASE, NULL);
679 		*credanonp = NULL;
680 		return (EACCES);
681 	}
682 	*extflagsp = np->netc_exflags;
683 	if ((*credanonp = np->netc_anon) != NULL)
684 		crhold(*credanonp);
685 	if (numsecflavors) {
686 		*numsecflavors = np->netc_numsecflavors;
687 		KASSERT(*numsecflavors > 0,
688 		    ("%s: numsecflavors <= 0", __func__));
689 		KASSERT(*numsecflavors < MAXSECFLAVORS,
690 		    ("%s: numsecflavors >= MAXSECFLAVORS", __func__));
691 	}
692 	if (secflavors && np->netc_numsecflavors > 0)
693 		memcpy(secflavors, np->netc_secflavors, np->netc_numsecflavors *
694 		    sizeof(int));
695 	lockmgr(&mp->mnt_explock, LK_RELEASE, NULL);
696 	return (0);
697 }
698