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  * Copyright (c) 1989, 1993
    3  *      The Regents of the University of California.  All rights reserved.
    4  * (c) UNIX System Laboratories, Inc.
    5  * All or some portions of this file are derived from material licensed
    6  * to the University of California by American Telephone and Telegraph
    7  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
    8  * the permission of UNIX System Laboratories, Inc.
    9  *
   10  * Redistribution and use in source and binary forms, with or without
   11  * modification, are permitted provided that the following conditions
   12  * are met:
   13  * 1. Redistributions of source code must retain the above copyright
   14  *    notice, this list of conditions and the following disclaimer.
   15  * 2. Redistributions in binary form must reproduce the above copyright
   16  *    notice, this list of conditions and the following disclaimer in the
   17  *    documentation and/or other materials provided with the distribution.
   18  * 4. Neither the name of the University nor the names of its contributors
   19  *    may be used to endorse or promote products derived from this software
   20  *    without specific prior written permission.
   21  *
   22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   32  * SUCH DAMAGE.
   33  *
   34  *      @(#)vfs_subr.c  8.31 (Berkeley) 5/26/95
   35  */
   36 
   37 #include <sys/cdefs.h>
   38 __FBSDID("$FreeBSD: stable/10/sys/kern/vfs_export.c 247116 2013-02-21 19:02:50Z jhb $");
   39 
   40 #include <sys/param.h>
   41 #include <sys/dirent.h>
   42 #include <sys/domain.h>
   43 #include <sys/jail.h>
   44 #include <sys/kernel.h>
   45 #include <sys/lock.h>
   46 #include <sys/malloc.h>
   47 #include <sys/mbuf.h>
   48 #include <sys/mount.h>
   49 #include <sys/mutex.h>
   50 #include <sys/rwlock.h>
   51 #include <sys/refcount.h>
   52 #include <sys/signalvar.h>
   53 #include <sys/socket.h>
   54 #include <sys/systm.h>
   55 #include <sys/vnode.h>
   56 
   57 #include <net/radix.h>
   58 
   59 static MALLOC_DEFINE(M_NETADDR, "export_host", "Export host address structure");
   60 
   61 static void     vfs_free_addrlist(struct netexport *nep);
   62 static int      vfs_free_netcred(struct radix_node *rn, void *w);
   63 static int      vfs_hang_addrlist(struct mount *mp, struct netexport *nep,
   64                     struct export_args *argp);
   65 static struct netcred *vfs_export_lookup(struct mount *, struct sockaddr *);
   66 
   67 /*
   68  * Network address lookup element
   69  */
   70 struct netcred {
   71         struct  radix_node netc_rnodes[2];
   72         int     netc_exflags;
   73         struct  ucred *netc_anon;
   74         int     netc_numsecflavors;
   75         int     netc_secflavors[MAXSECFLAVORS];
   76 };
   77 
   78 /*
   79  * Network export information
   80  */
   81 struct netexport {
   82         struct  netcred ne_defexported;               /* Default export */
   83         struct  radix_node_head *ne_rtable[AF_MAX+1]; /* Individual exports */
   84 };
   85 
   86 /*
   87  * Build hash lists of net addresses and hang them off the mount point.
   88  * Called by vfs_export() to set up the lists of export addresses.
   89  */
   90 static int
   91 vfs_hang_addrlist(struct mount *mp, struct netexport *nep,
   92     struct export_args *argp)
   93 {
   94         register struct netcred *np;
   95         register struct radix_node_head *rnh;
   96         register int i;
   97         struct radix_node *rn;
   98         struct sockaddr *saddr, *smask = 0;
   99         struct domain *dom;
  100         int error;
  101 
  102         /*
  103          * XXX: This routine converts from a `struct xucred'
  104          * (argp->ex_anon) to a `struct ucred' (np->netc_anon).  This
  105          * operation is questionable; for example, what should be done
  106          * with fields like cr_uidinfo and cr_prison?  Currently, this
  107          * routine does not touch them (leaves them as NULL).
  108          */
  109         if (argp->ex_anon.cr_version != XUCRED_VERSION) {
  110                 vfs_mount_error(mp, "ex_anon.cr_version: %d != %d",
  111                     argp->ex_anon.cr_version, XUCRED_VERSION);
  112                 return (EINVAL);
  113         }
  114 
  115         if (argp->ex_addrlen == 0) {
  116                 if (mp->mnt_flag & MNT_DEFEXPORTED) {
  117                         vfs_mount_error(mp,
  118                             "MNT_DEFEXPORTED already set for mount %p", mp);
  119                         return (EPERM);
  120                 }
  121                 np = &nep->ne_defexported;
  122                 np->netc_exflags = argp->ex_flags;
  123                 np->netc_anon = crget();
  124                 np->netc_anon->cr_uid = argp->ex_anon.cr_uid;
  125                 crsetgroups(np->netc_anon, argp->ex_anon.cr_ngroups,
  126                     argp->ex_anon.cr_groups);
  127                 np->netc_anon->cr_prison = &prison0;
  128                 prison_hold(np->netc_anon->cr_prison);
  129                 np->netc_numsecflavors = argp->ex_numsecflavors;
  130                 bcopy(argp->ex_secflavors, np->netc_secflavors,
  131                     sizeof(np->netc_secflavors));
  132                 MNT_ILOCK(mp);
  133                 mp->mnt_flag |= MNT_DEFEXPORTED;
  134                 MNT_IUNLOCK(mp);
  135                 return (0);
  136         }
  137 
  138 #if MSIZE <= 256
  139         if (argp->ex_addrlen > MLEN) {
  140                 vfs_mount_error(mp, "ex_addrlen %d is greater than %d",
  141                     argp->ex_addrlen, MLEN);
  142                 return (EINVAL);
  143         }
  144 #endif
  145 
  146         i = sizeof(struct netcred) + argp->ex_addrlen + argp->ex_masklen;
  147         np = (struct netcred *) malloc(i, M_NETADDR, M_WAITOK | M_ZERO);
  148         saddr = (struct sockaddr *) (np + 1);
  149         if ((error = copyin(argp->ex_addr, saddr, argp->ex_addrlen)))
  150                 goto out;
  151         if (saddr->sa_family == AF_UNSPEC || saddr->sa_family > AF_MAX) {
  152                 error = EINVAL;
  153                 vfs_mount_error(mp, "Invalid saddr->sa_family: %d");
  154                 goto out;
  155         }
  156         if (saddr->sa_len > argp->ex_addrlen)
  157                 saddr->sa_len = argp->ex_addrlen;
  158         if (argp->ex_masklen) {
  159                 smask = (struct sockaddr *)((caddr_t)saddr + argp->ex_addrlen);
  160                 error = copyin(argp->ex_mask, smask, argp->ex_masklen);
  161                 if (error)
  162                         goto out;
  163                 if (smask->sa_len > argp->ex_masklen)
  164                         smask->sa_len = argp->ex_masklen;
  165         }
  166         i = saddr->sa_family;
  167         if ((rnh = nep->ne_rtable[i]) == NULL) {
  168                 /*
  169                  * Seems silly to initialize every AF when most are not used,
  170                  * do so on demand here
  171                  */
  172                 for (dom = domains; dom; dom = dom->dom_next) {
  173                         KASSERT(((i == AF_INET) || (i == AF_INET6)), 
  174                             ("unexpected protocol in vfs_hang_addrlist"));
  175                         if (dom->dom_family == i && dom->dom_rtattach) {
  176                                 /*
  177                                  * XXX MRT 
  178                                  * The INET and INET6 domains know the
  179                                  * offset already. We don't need to send it
  180                                  * So we just use it as a flag to say that
  181                                  * we are or are not setting up a real routing
  182                                  * table. Only IP and IPV6 need have this
  183                                  * be 0 so all other protocols can stay the 
  184                                  * same (ABI compatible).
  185                                  */ 
  186                                 dom->dom_rtattach(
  187                                     (void **) &nep->ne_rtable[i], 0);
  188                                 break;
  189                         }
  190                 }
  191                 if ((rnh = nep->ne_rtable[i]) == NULL) {
  192                         error = ENOBUFS;
  193                         vfs_mount_error(mp, "%s %s %d",
  194                             "Unable to initialize radix node head ",
  195                             "for address family", i);
  196                         goto out;
  197                 }
  198         }
  199         RADIX_NODE_HEAD_LOCK(rnh);
  200         rn = (*rnh->rnh_addaddr)(saddr, smask, rnh, np->netc_rnodes);
  201         RADIX_NODE_HEAD_UNLOCK(rnh);
  202         if (rn == NULL || np != (struct netcred *)rn) { /* already exists */
  203                 error = EPERM;
  204                 vfs_mount_error(mp, "Invalid radix node head, rn: %p %p",
  205                     rn, np);
  206                 goto out;
  207         }
  208         np->netc_exflags = argp->ex_flags;
  209         np->netc_anon = crget();
  210         np->netc_anon->cr_uid = argp->ex_anon.cr_uid;
  211         crsetgroups(np->netc_anon, argp->ex_anon.cr_ngroups,
  212             argp->ex_anon.cr_groups);
  213         np->netc_anon->cr_prison = &prison0;
  214         prison_hold(np->netc_anon->cr_prison);
  215         np->netc_numsecflavors = argp->ex_numsecflavors;
  216         bcopy(argp->ex_secflavors, np->netc_secflavors,
  217             sizeof(np->netc_secflavors));
  218         return (0);
  219 out:
  220         free(np, M_NETADDR);
  221         return (error);
  222 }
  223 
  224 /* Helper for vfs_free_addrlist. */
  225 /* ARGSUSED */
  226 static int
  227 vfs_free_netcred(struct radix_node *rn, void *w)
  228 {
  229         struct radix_node_head *rnh = (struct radix_node_head *) w;
  230         struct ucred *cred;
  231 
  232         (*rnh->rnh_deladdr) (rn->rn_key, rn->rn_mask, rnh);
  233         cred = ((struct netcred *)rn)->netc_anon;
  234         if (cred != NULL)
  235                 crfree(cred);
  236         free(rn, M_NETADDR);
  237         return (0);
  238 }
  239 
  240 /*
  241  * Free the net address hash lists that are hanging off the mount points.
  242  */
  243 static void
  244 vfs_free_addrlist(struct netexport *nep)
  245 {
  246         int i;
  247         struct radix_node_head *rnh;
  248         struct ucred *cred;
  249 
  250         for (i = 0; i <= AF_MAX; i++) {
  251                 if ((rnh = nep->ne_rtable[i])) {
  252                         RADIX_NODE_HEAD_LOCK(rnh);
  253                         (*rnh->rnh_walktree) (rnh, vfs_free_netcred, rnh);
  254                         RADIX_NODE_HEAD_UNLOCK(rnh);
  255                         RADIX_NODE_HEAD_DESTROY(rnh);
  256                         free(rnh, M_RTABLE);
  257                         nep->ne_rtable[i] = NULL;       /* not SMP safe XXX */
  258                 }
  259         }
  260         cred = nep->ne_defexported.netc_anon;
  261         if (cred != NULL)
  262                 crfree(cred);
  263 
  264 }
  265 
  266 /*
  267  * High level function to manipulate export options on a mount point
  268  * and the passed in netexport.
  269  * Struct export_args *argp is the variable used to twiddle options,
  270  * the structure is described in sys/mount.h
  271  */
  272 int
  273 vfs_export(struct mount *mp, struct export_args *argp)
  274 {
  275         struct netexport *nep;
  276         int error;
  277 
  278         if (argp->ex_numsecflavors < 0
  279             || argp->ex_numsecflavors >= MAXSECFLAVORS)
  280                 return (EINVAL);
  281 
  282         error = 0;
  283         lockmgr(&mp->mnt_explock, LK_EXCLUSIVE, NULL);
  284         nep = mp->mnt_export;
  285         if (argp->ex_flags & MNT_DELEXPORT) {
  286                 if (nep == NULL) {
  287                         error = ENOENT;
  288                         goto out;
  289                 }
  290                 if (mp->mnt_flag & MNT_EXPUBLIC) {
  291                         vfs_setpublicfs(NULL, NULL, NULL);
  292                         MNT_ILOCK(mp);
  293                         mp->mnt_flag &= ~MNT_EXPUBLIC;
  294                         MNT_IUNLOCK(mp);
  295                 }
  296                 vfs_free_addrlist(nep);
  297                 mp->mnt_export = NULL;
  298                 free(nep, M_MOUNT);
  299                 nep = NULL;
  300                 MNT_ILOCK(mp);
  301                 mp->mnt_flag &= ~(MNT_EXPORTED | MNT_DEFEXPORTED);
  302                 MNT_IUNLOCK(mp);
  303         }
  304         if (argp->ex_flags & MNT_EXPORTED) {
  305                 if (nep == NULL) {
  306                         nep = malloc(sizeof(struct netexport), M_MOUNT, M_WAITOK | M_ZERO);
  307                         mp->mnt_export = nep;
  308                 }
  309                 if (argp->ex_flags & MNT_EXPUBLIC) {
  310                         if ((error = vfs_setpublicfs(mp, nep, argp)) != 0)
  311                                 goto out;
  312                         MNT_ILOCK(mp);
  313                         mp->mnt_flag |= MNT_EXPUBLIC;
  314                         MNT_IUNLOCK(mp);
  315                 }
  316                 if ((error = vfs_hang_addrlist(mp, nep, argp)))
  317                         goto out;
  318                 MNT_ILOCK(mp);
  319                 mp->mnt_flag |= MNT_EXPORTED;
  320                 MNT_IUNLOCK(mp);
  321         }
  322 
  323 out:
  324         lockmgr(&mp->mnt_explock, LK_RELEASE, NULL);
  325         /*
  326          * Once we have executed the vfs_export() command, we do
  327          * not want to keep the "export" option around in the
  328          * options list, since that will cause subsequent MNT_UPDATE
  329          * calls to fail.  The export information is saved in
  330          * mp->mnt_export, so we can safely delete the "export" mount option
  331          * here.
  332          */
  333         vfs_deleteopt(mp->mnt_optnew, "export");
  334         vfs_deleteopt(mp->mnt_opt, "export");
  335         return (error);
  336 }
  337 
  338 /*
  339  * Set the publicly exported filesystem (WebNFS). Currently, only
  340  * one public filesystem is possible in the spec (RFC 2054 and 2055)
  341  */
  342 int
  343 vfs_setpublicfs(struct mount *mp, struct netexport *nep,
  344     struct export_args *argp)
  345 {
  346         int error;
  347         struct vnode *rvp;
  348         char *cp;
  349 
  350         /*
  351          * mp == NULL -> invalidate the current info, the FS is
  352          * no longer exported. May be called from either vfs_export
  353          * or unmount, so check if it hasn't already been done.
  354          */
  355         if (mp == NULL) {
  356                 if (nfs_pub.np_valid) {
  357                         nfs_pub.np_valid = 0;
  358                         if (nfs_pub.np_index != NULL) {
  359                                 free(nfs_pub.np_index, M_TEMP);
  360                                 nfs_pub.np_index = NULL;
  361                         }
  362                 }
  363                 return (0);
  364         }
  365 
  366         /*
  367          * Only one allowed at a time.
  368          */
  369         if (nfs_pub.np_valid != 0 && mp != nfs_pub.np_mount)
  370                 return (EBUSY);
  371 
  372         /*
  373          * Get real filehandle for root of exported FS.
  374          */
  375         bzero(&nfs_pub.np_handle, sizeof(nfs_pub.np_handle));
  376         nfs_pub.np_handle.fh_fsid = mp->mnt_stat.f_fsid;
  377 
  378         if ((error = VFS_ROOT(mp, LK_EXCLUSIVE, &rvp)))
  379                 return (error);
  380 
  381         if ((error = VOP_VPTOFH(rvp, &nfs_pub.np_handle.fh_fid)))
  382                 return (error);
  383 
  384         vput(rvp);
  385 
  386         /*
  387          * If an indexfile was specified, pull it in.
  388          */
  389         if (argp->ex_indexfile != NULL) {
  390                 if (nfs_pub.np_index != NULL)
  391                         nfs_pub.np_index = malloc(MAXNAMLEN + 1, M_TEMP,
  392                             M_WAITOK);
  393                 error = copyinstr(argp->ex_indexfile, nfs_pub.np_index,
  394                     MAXNAMLEN, (size_t *)0);
  395                 if (!error) {
  396                         /*
  397                          * Check for illegal filenames.
  398                          */
  399                         for (cp = nfs_pub.np_index; *cp; cp++) {
  400                                 if (*cp == '/') {
  401                                         error = EINVAL;
  402                                         break;
  403                                 }
  404                         }
  405                 }
  406                 if (error) {
  407                         free(nfs_pub.np_index, M_TEMP);
  408                         nfs_pub.np_index = NULL;
  409                         return (error);
  410                 }
  411         }
  412 
  413         nfs_pub.np_mount = mp;
  414         nfs_pub.np_valid = 1;
  415         return (0);
  416 }
  417 
  418 /*
  419  * Used by the filesystems to determine if a given network address
  420  * (passed in 'nam') is present in their exports list, returns a pointer
  421  * to struct netcred so that the filesystem can examine it for
  422  * access rights (read/write/etc).
  423  */
  424 static struct netcred *
  425 vfs_export_lookup(struct mount *mp, struct sockaddr *nam)
  426 {
  427         struct netexport *nep;
  428         register struct netcred *np;
  429         register struct radix_node_head *rnh;
  430         struct sockaddr *saddr;
  431 
  432         nep = mp->mnt_export;
  433         if (nep == NULL)
  434                 return (NULL);
  435         np = NULL;
  436         if (mp->mnt_flag & MNT_EXPORTED) {
  437                 /*
  438                  * Lookup in the export list first.
  439                  */
  440                 if (nam != NULL) {
  441                         saddr = nam;
  442                         rnh = nep->ne_rtable[saddr->sa_family];
  443                         if (rnh != NULL) {
  444                                 RADIX_NODE_HEAD_RLOCK(rnh);
  445                                 np = (struct netcred *)
  446                                     (*rnh->rnh_matchaddr)(saddr, rnh);
  447                                 RADIX_NODE_HEAD_RUNLOCK(rnh);
  448                                 if (np && np->netc_rnodes->rn_flags & RNF_ROOT)
  449                                         np = NULL;
  450                         }
  451                 }
  452                 /*
  453                  * If no address match, use the default if it exists.
  454                  */
  455                 if (np == NULL && mp->mnt_flag & MNT_DEFEXPORTED)
  456                         np = &nep->ne_defexported;
  457         }
  458         return (np);
  459 }
  460 
  461 /*
  462  * XXX: This comment comes from the deprecated ufs_check_export()
  463  * XXX: and may not entirely apply, but lacking something better:
  464  * This is the generic part of fhtovp called after the underlying
  465  * filesystem has validated the file handle.
  466  *
  467  * Verify that a host should have access to a filesystem.
  468  */
  469 
  470 int 
  471 vfs_stdcheckexp(struct mount *mp, struct sockaddr *nam, int *extflagsp,
  472     struct ucred **credanonp, int *numsecflavors, int **secflavors)
  473 {
  474         struct netcred *np;
  475 
  476         lockmgr(&mp->mnt_explock, LK_SHARED, NULL);
  477         np = vfs_export_lookup(mp, nam);
  478         if (np == NULL) {
  479                 lockmgr(&mp->mnt_explock, LK_RELEASE, NULL);
  480                 *credanonp = NULL;
  481                 return (EACCES);
  482         }
  483         *extflagsp = np->netc_exflags;
  484         if ((*credanonp = np->netc_anon) != NULL)
  485                 crhold(*credanonp);
  486         if (numsecflavors)
  487                 *numsecflavors = np->netc_numsecflavors;
  488         if (secflavors)
  489                 *secflavors = np->netc_secflavors;
  490         lockmgr(&mp->mnt_explock, LK_RELEASE, NULL);
  491         return (0);
  492 }
  493 

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