The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/kern/vfs_export.c

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    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  *      @(#)vfs_subr.c  8.31 (Berkeley) 5/26/95
   37  */
   38 
   39 #include <sys/cdefs.h>
   40 __FBSDID("$FreeBSD$");
   41 
   42 #include "opt_inet.h"
   43 #include "opt_inet6.h"
   44 
   45 #include <sys/param.h>
   46 #include <sys/systm.h>
   47 #include <sys/dirent.h>
   48 #include <sys/jail.h>
   49 #include <sys/kernel.h>
   50 #include <sys/lock.h>
   51 #include <sys/malloc.h>
   52 #include <sys/mbuf.h>
   53 #include <sys/mount.h>
   54 #include <sys/mutex.h>
   55 #include <sys/rmlock.h>
   56 #include <sys/refcount.h>
   57 #include <sys/signalvar.h>
   58 #include <sys/socket.h>
   59 #include <sys/vnode.h>
   60 
   61 #include <netinet/in.h>
   62 #include <net/radix.h>
   63 
   64 #include <rpc/types.h>
   65 #include <rpc/auth.h>
   66 
   67 static MALLOC_DEFINE(M_NETADDR, "export_host", "Export host address structure");
   68 
   69 #if defined(INET) || defined(INET6)
   70 static struct radix_node_head *vfs_create_addrlist_af(
   71                     struct radix_node_head **prnh, int off);
   72 #endif
   73 static void     vfs_free_addrlist(struct netexport *nep);
   74 static int      vfs_free_netcred(struct radix_node *rn, void *w);
   75 static void     vfs_free_addrlist_af(struct radix_node_head **prnh);
   76 static int      vfs_hang_addrlist(struct mount *mp, struct netexport *nep,
   77                     struct export_args *argp);
   78 static struct netcred *vfs_export_lookup(struct mount *, struct sockaddr *);
   79 
   80 /*
   81  * Network address lookup element
   82  */
   83 struct netcred {
   84         struct  radix_node netc_rnodes[2];
   85         int     netc_exflags;
   86         struct  ucred *netc_anon;
   87         int     netc_numsecflavors;
   88         int     netc_secflavors[MAXSECFLAVORS];
   89 };
   90 
   91 /*
   92  * Network export information
   93  */
   94 struct netexport {
   95         struct  netcred ne_defexported;               /* Default export */
   96         struct  radix_node_head *ne4;
   97         struct  radix_node_head *ne6;
   98 };
   99 
  100 /*
  101  * Build hash lists of net addresses and hang them off the mount point.
  102  * Called by vfs_export() to set up the lists of export addresses.
  103  */
  104 static int
  105 vfs_hang_addrlist(struct mount *mp, struct netexport *nep,
  106     struct export_args *argp)
  107 {
  108         struct netcred *np;
  109         struct radix_node_head *rnh;
  110         int i;
  111         struct radix_node *rn;
  112         struct sockaddr *saddr, *smask = NULL;
  113 #if defined(INET6) || defined(INET)
  114         int off;
  115 #endif
  116         int error;
  117 
  118         KASSERT(argp->ex_numsecflavors > 0,
  119             ("%s: numsecflavors <= 0", __func__));
  120         KASSERT(argp->ex_numsecflavors < MAXSECFLAVORS,
  121             ("%s: numsecflavors >= MAXSECFLAVORS", __func__));
  122 
  123         /*
  124          * XXX: This routine converts from a `struct xucred'
  125          * (argp->ex_anon) to a `struct ucred' (np->netc_anon).  This
  126          * operation is questionable; for example, what should be done
  127          * with fields like cr_uidinfo and cr_prison?  Currently, this
  128          * routine does not touch them (leaves them as NULL).
  129          */
  130         if (argp->ex_anon.cr_version != XUCRED_VERSION) {
  131                 vfs_mount_error(mp, "ex_anon.cr_version: %d != %d",
  132                     argp->ex_anon.cr_version, XUCRED_VERSION);
  133                 return (EINVAL);
  134         }
  135 
  136         if (argp->ex_addrlen == 0) {
  137                 if (mp->mnt_flag & MNT_DEFEXPORTED) {
  138                         vfs_mount_error(mp,
  139                             "MNT_DEFEXPORTED already set for mount %p", mp);
  140                         return (EPERM);
  141                 }
  142                 np = &nep->ne_defexported;
  143                 np->netc_exflags = argp->ex_flags;
  144                 np->netc_anon = crget();
  145                 np->netc_anon->cr_uid = argp->ex_anon.cr_uid;
  146                 crsetgroups(np->netc_anon, argp->ex_anon.cr_ngroups,
  147                     argp->ex_anon.cr_groups);
  148                 np->netc_anon->cr_prison = &prison0;
  149                 prison_hold(np->netc_anon->cr_prison);
  150                 np->netc_numsecflavors = argp->ex_numsecflavors;
  151                 bcopy(argp->ex_secflavors, np->netc_secflavors,
  152                     sizeof(np->netc_secflavors));
  153                 MNT_ILOCK(mp);
  154                 mp->mnt_flag |= MNT_DEFEXPORTED;
  155                 MNT_IUNLOCK(mp);
  156                 return (0);
  157         }
  158 
  159 #if MSIZE <= 256
  160         if (argp->ex_addrlen > MLEN) {
  161                 vfs_mount_error(mp, "ex_addrlen %d is greater than %d",
  162                     argp->ex_addrlen, MLEN);
  163                 return (EINVAL);
  164         }
  165 #endif
  166 
  167         i = sizeof(struct netcred) + argp->ex_addrlen + argp->ex_masklen;
  168         np = (struct netcred *) malloc(i, M_NETADDR, M_WAITOK | M_ZERO);
  169         saddr = (struct sockaddr *) (np + 1);
  170         if ((error = copyin(argp->ex_addr, saddr, argp->ex_addrlen)))
  171                 goto out;
  172         if (saddr->sa_family == AF_UNSPEC || saddr->sa_family > AF_MAX) {
  173                 error = EINVAL;
  174                 vfs_mount_error(mp, "Invalid saddr->sa_family: %d");
  175                 goto out;
  176         }
  177         if (saddr->sa_len > argp->ex_addrlen)
  178                 saddr->sa_len = argp->ex_addrlen;
  179         if (argp->ex_masklen) {
  180                 smask = (struct sockaddr *)((caddr_t)saddr + argp->ex_addrlen);
  181                 error = copyin(argp->ex_mask, smask, argp->ex_masklen);
  182                 if (error)
  183                         goto out;
  184                 if (smask->sa_len > argp->ex_masklen)
  185                         smask->sa_len = argp->ex_masklen;
  186         }
  187         rnh = NULL;
  188         switch (saddr->sa_family) {
  189 #ifdef INET
  190         case AF_INET:
  191                 if ((rnh = nep->ne4) == NULL) {
  192                         off = offsetof(struct sockaddr_in, sin_addr) << 3;
  193                         rnh = vfs_create_addrlist_af(&nep->ne4, off);
  194                 }
  195                 break;
  196 #endif
  197 #ifdef INET6
  198         case AF_INET6:
  199                 if ((rnh = nep->ne6) == NULL) {
  200                         off = offsetof(struct sockaddr_in6, sin6_addr) << 3;
  201                         rnh = vfs_create_addrlist_af(&nep->ne6, off);
  202                 }
  203                 break;
  204 #endif
  205         }
  206         if (rnh == NULL) {
  207                 error = ENOBUFS;
  208                 vfs_mount_error(mp, "%s %s %d",
  209                     "Unable to initialize radix node head ",
  210                     "for address family", saddr->sa_family);
  211                 goto out;
  212         }
  213         RADIX_NODE_HEAD_LOCK(rnh);
  214         rn = (*rnh->rnh_addaddr)(saddr, smask, &rnh->rh, np->netc_rnodes);
  215         RADIX_NODE_HEAD_UNLOCK(rnh);
  216         if (rn == NULL || np != (struct netcred *)rn) { /* already exists */
  217                 error = EPERM;
  218                 vfs_mount_error(mp,
  219                     "netcred already exists for given addr/mask");
  220                 goto out;
  221         }
  222         np->netc_exflags = argp->ex_flags;
  223         np->netc_anon = crget();
  224         np->netc_anon->cr_uid = argp->ex_anon.cr_uid;
  225         crsetgroups(np->netc_anon, argp->ex_anon.cr_ngroups,
  226             argp->ex_anon.cr_groups);
  227         np->netc_anon->cr_prison = &prison0;
  228         prison_hold(np->netc_anon->cr_prison);
  229         np->netc_numsecflavors = argp->ex_numsecflavors;
  230         bcopy(argp->ex_secflavors, np->netc_secflavors,
  231             sizeof(np->netc_secflavors));
  232         return (0);
  233 out:
  234         free(np, M_NETADDR);
  235         return (error);
  236 }
  237 
  238 /* Helper for vfs_free_addrlist. */
  239 /* ARGSUSED */
  240 static int
  241 vfs_free_netcred(struct radix_node *rn, void *w)
  242 {
  243         struct radix_node_head *rnh = (struct radix_node_head *) w;
  244         struct ucred *cred;
  245 
  246         (*rnh->rnh_deladdr) (rn->rn_key, rn->rn_mask, &rnh->rh);
  247         cred = ((struct netcred *)rn)->netc_anon;
  248         if (cred != NULL)
  249                 crfree(cred);
  250         free(rn, M_NETADDR);
  251         return (0);
  252 }
  253 
  254 #if defined(INET) || defined(INET6)
  255 static struct radix_node_head *
  256 vfs_create_addrlist_af(struct radix_node_head **prnh, int off)
  257 {
  258 
  259         if (rn_inithead((void **)prnh, off) == 0)
  260                 return (NULL);
  261         RADIX_NODE_HEAD_LOCK_INIT(*prnh);
  262         return (*prnh);
  263 }
  264 #endif
  265 
  266 static void
  267 vfs_free_addrlist_af(struct radix_node_head **prnh)
  268 {
  269         struct radix_node_head *rnh;
  270 
  271         rnh = *prnh;
  272         RADIX_NODE_HEAD_LOCK(rnh);
  273         (*rnh->rnh_walktree)(&rnh->rh, vfs_free_netcred, rnh);
  274         RADIX_NODE_HEAD_UNLOCK(rnh);
  275         RADIX_NODE_HEAD_DESTROY(rnh);
  276         rn_detachhead((void **)prnh);
  277         prnh = NULL;
  278 }
  279 
  280 /*
  281  * Free the net address hash lists that are hanging off the mount points.
  282  */
  283 static void
  284 vfs_free_addrlist(struct netexport *nep)
  285 {
  286         struct ucred *cred;
  287 
  288         if (nep->ne4 != NULL)
  289                 vfs_free_addrlist_af(&nep->ne4);
  290         if (nep->ne6 != NULL)
  291                 vfs_free_addrlist_af(&nep->ne6);
  292 
  293         cred = nep->ne_defexported.netc_anon;
  294         if (cred != NULL)
  295                 crfree(cred);
  296 
  297 }
  298 
  299 /*
  300  * High level function to manipulate export options on a mount point
  301  * and the passed in netexport.
  302  * Struct export_args *argp is the variable used to twiddle options,
  303  * the structure is described in sys/mount.h
  304  */
  305 int
  306 vfs_export(struct mount *mp, struct export_args *argp)
  307 {
  308         struct netexport *nep;
  309         int error;
  310 
  311         if ((argp->ex_flags & (MNT_DELEXPORT | MNT_EXPORTED)) == 0)
  312                 return (EINVAL);
  313 
  314         if ((argp->ex_flags & MNT_EXPORTED) != 0 &&
  315             (argp->ex_numsecflavors < 0
  316             || argp->ex_numsecflavors >= MAXSECFLAVORS))
  317                 return (EINVAL);
  318 
  319         error = 0;
  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                 if (mp->mnt_flag & MNT_EXPUBLIC) {
  328                         vfs_setpublicfs(NULL, NULL, NULL);
  329                         MNT_ILOCK(mp);
  330                         mp->mnt_flag &= ~MNT_EXPUBLIC;
  331                         MNT_IUNLOCK(mp);
  332                 }
  333                 vfs_free_addrlist(nep);
  334                 mp->mnt_export = NULL;
  335                 free(nep, M_MOUNT);
  336                 nep = NULL;
  337                 MNT_ILOCK(mp);
  338                 mp->mnt_flag &= ~(MNT_EXPORTED | MNT_DEFEXPORTED);
  339                 MNT_IUNLOCK(mp);
  340         }
  341         if (argp->ex_flags & MNT_EXPORTED) {
  342                 if (nep == NULL) {
  343                         nep = malloc(sizeof(struct netexport), M_MOUNT, M_WAITOK | M_ZERO);
  344                         mp->mnt_export = nep;
  345                 }
  346                 if (argp->ex_flags & MNT_EXPUBLIC) {
  347                         if ((error = vfs_setpublicfs(mp, nep, argp)) != 0)
  348                                 goto out;
  349                         MNT_ILOCK(mp);
  350                         mp->mnt_flag |= MNT_EXPUBLIC;
  351                         MNT_IUNLOCK(mp);
  352                 }
  353                 if (argp->ex_numsecflavors == 0) {
  354                         argp->ex_numsecflavors = 1;
  355                         argp->ex_secflavors[0] = AUTH_SYS;
  356                 }
  357                 if ((error = vfs_hang_addrlist(mp, nep, argp)))
  358                         goto out;
  359                 MNT_ILOCK(mp);
  360                 mp->mnt_flag |= MNT_EXPORTED;
  361                 MNT_IUNLOCK(mp);
  362         }
  363 
  364 out:
  365         lockmgr(&mp->mnt_explock, LK_RELEASE, NULL);
  366         /*
  367          * Once we have executed the vfs_export() command, we do
  368          * not want to keep the "export" option around in the
  369          * options list, since that will cause subsequent MNT_UPDATE
  370          * calls to fail.  The export information is saved in
  371          * mp->mnt_export, so we can safely delete the "export" mount option
  372          * here.
  373          */
  374         vfs_deleteopt(mp->mnt_optnew, "export");
  375         vfs_deleteopt(mp->mnt_opt, "export");
  376         return (error);
  377 }
  378 
  379 /*
  380  * Set the publicly exported filesystem (WebNFS). Currently, only
  381  * one public filesystem is possible in the spec (RFC 2054 and 2055)
  382  */
  383 int
  384 vfs_setpublicfs(struct mount *mp, struct netexport *nep,
  385     struct export_args *argp)
  386 {
  387         int error;
  388         struct vnode *rvp;
  389         char *cp;
  390 
  391         /*
  392          * mp == NULL -> invalidate the current info, the FS is
  393          * no longer exported. May be called from either vfs_export
  394          * or unmount, so check if it hasn't already been done.
  395          */
  396         if (mp == NULL) {
  397                 if (nfs_pub.np_valid) {
  398                         nfs_pub.np_valid = 0;
  399                         if (nfs_pub.np_index != NULL) {
  400                                 free(nfs_pub.np_index, M_TEMP);
  401                                 nfs_pub.np_index = NULL;
  402                         }
  403                 }
  404                 return (0);
  405         }
  406 
  407         /*
  408          * Only one allowed at a time.
  409          */
  410         if (nfs_pub.np_valid != 0 && mp != nfs_pub.np_mount)
  411                 return (EBUSY);
  412 
  413         /*
  414          * Get real filehandle for root of exported FS.
  415          */
  416         bzero(&nfs_pub.np_handle, sizeof(nfs_pub.np_handle));
  417         nfs_pub.np_handle.fh_fsid = mp->mnt_stat.f_fsid;
  418 
  419         if ((error = VFS_ROOT(mp, LK_EXCLUSIVE, &rvp)))
  420                 return (error);
  421 
  422         if ((error = VOP_VPTOFH(rvp, &nfs_pub.np_handle.fh_fid)))
  423                 return (error);
  424 
  425         vput(rvp);
  426 
  427         /*
  428          * If an indexfile was specified, pull it in.
  429          */
  430         if (argp->ex_indexfile != NULL) {
  431                 if (nfs_pub.np_index == NULL)
  432                         nfs_pub.np_index = malloc(MAXNAMLEN + 1, M_TEMP,
  433                             M_WAITOK);
  434                 error = copyinstr(argp->ex_indexfile, nfs_pub.np_index,
  435                     MAXNAMLEN, (size_t *)0);
  436                 if (!error) {
  437                         /*
  438                          * Check for illegal filenames.
  439                          */
  440                         for (cp = nfs_pub.np_index; *cp; cp++) {
  441                                 if (*cp == '/') {
  442                                         error = EINVAL;
  443                                         break;
  444                                 }
  445                         }
  446                 }
  447                 if (error) {
  448                         free(nfs_pub.np_index, M_TEMP);
  449                         nfs_pub.np_index = NULL;
  450                         return (error);
  451                 }
  452         }
  453 
  454         nfs_pub.np_mount = mp;
  455         nfs_pub.np_valid = 1;
  456         return (0);
  457 }
  458 
  459 /*
  460  * Used by the filesystems to determine if a given network address
  461  * (passed in 'nam') is present in their exports list, returns a pointer
  462  * to struct netcred so that the filesystem can examine it for
  463  * access rights (read/write/etc).
  464  */
  465 static struct netcred *
  466 vfs_export_lookup(struct mount *mp, struct sockaddr *nam)
  467 {
  468         RADIX_NODE_HEAD_RLOCK_TRACKER;
  469         struct netexport *nep;
  470         struct netcred *np = NULL;
  471         struct radix_node_head *rnh;
  472         struct sockaddr *saddr;
  473 
  474         nep = mp->mnt_export;
  475         if (nep == NULL)
  476                 return (NULL);
  477         if ((mp->mnt_flag & MNT_EXPORTED) == 0)
  478                 return (NULL);
  479 
  480         /*
  481          * Lookup in the export list
  482          */
  483         if (nam != NULL) {
  484                 saddr = nam;
  485                 rnh = NULL;
  486                 switch (saddr->sa_family) {
  487                 case AF_INET:
  488                         rnh = nep->ne4;
  489                         break;
  490                 case AF_INET6:
  491                         rnh = nep->ne6;
  492                         break;
  493                 }
  494                 if (rnh != NULL) {
  495                         RADIX_NODE_HEAD_RLOCK(rnh);
  496                         np = (struct netcred *) (*rnh->rnh_matchaddr)(saddr, &rnh->rh);
  497                         RADIX_NODE_HEAD_RUNLOCK(rnh);
  498                         if (np != NULL && (np->netc_rnodes->rn_flags & RNF_ROOT) != 0)
  499                                 return (NULL);
  500                 }
  501         }
  502 
  503         /*
  504          * If no address match, use the default if it exists.
  505          */
  506         if (np == NULL && (mp->mnt_flag & MNT_DEFEXPORTED) != 0)
  507                 return (&nep->ne_defexported);
  508 
  509         return (np);
  510 }
  511 
  512 /*
  513  * XXX: This comment comes from the deprecated ufs_check_export()
  514  * XXX: and may not entirely apply, but lacking something better:
  515  * This is the generic part of fhtovp called after the underlying
  516  * filesystem has validated the file handle.
  517  *
  518  * Verify that a host should have access to a filesystem.
  519  */
  520 
  521 int 
  522 vfs_stdcheckexp(struct mount *mp, struct sockaddr *nam, int *extflagsp,
  523     struct ucred **credanonp, int *numsecflavors, int **secflavors)
  524 {
  525         struct netcred *np;
  526 
  527         lockmgr(&mp->mnt_explock, LK_SHARED, NULL);
  528         np = vfs_export_lookup(mp, nam);
  529         if (np == NULL) {
  530                 lockmgr(&mp->mnt_explock, LK_RELEASE, NULL);
  531                 *credanonp = NULL;
  532                 return (EACCES);
  533         }
  534         *extflagsp = np->netc_exflags;
  535         if ((*credanonp = np->netc_anon) != NULL)
  536                 crhold(*credanonp);
  537         if (numsecflavors) {
  538                 *numsecflavors = np->netc_numsecflavors;
  539                 KASSERT(*numsecflavors > 0,
  540                     ("%s: numsecflavors <= 0", __func__));
  541                 KASSERT(*numsecflavors < MAXSECFLAVORS,
  542                     ("%s: numsecflavors >= MAXSECFLAVORS", __func__));
  543         }
  544         if (secflavors)
  545                 *secflavors = np->netc_secflavors;
  546         lockmgr(&mp->mnt_explock, LK_RELEASE, NULL);
  547         return (0);
  548 }
  549 

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