vfs_export.c

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/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1989, 1993
 *      The Regents of the University of California.  All rights reserved.
 * (c) UNIX System Laboratories, Inc.
 * All or some portions of this file are derived from material licensed
 * to the University of California by American Telephone and Telegraph
 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
 * the permission of UNIX System Laboratories, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      @(#)vfs_subr.c  8.31 (Berkeley) 5/26/95
 */
 
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
 
#include "opt_inet.h"
#include "opt_inet6.h"
 
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/dirent.h>
#include <sys/jail.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/mount.h>
#include <sys/mutex.h>
#include <sys/rmlock.h>
#include <sys/refcount.h>
#include <sys/signalvar.h>
#include <sys/socket.h>
#include <sys/vnode.h>
 
#include <netinet/in.h>
#include <net/radix.h>
 
#include <rpc/types.h>
#include <rpc/auth.h>
 
static MALLOC_DEFINE(M_NETADDR, "export_host", "Export host address structure");
 
#if defined(INET) || defined(INET6)
static struct radix_node_head *vfs_create_addrlist_af(
                    struct radix_node_head **prnh, int off);
#endif
static void     vfs_free_addrlist(struct netexport *nep);
static int      vfs_free_netcred(struct radix_node *rn, void *w);
static void     vfs_free_addrlist_af(struct radix_node_head **prnh);
static int      vfs_hang_addrlist(struct mount *mp, struct netexport *nep,
                    struct export_args *argp);
static struct netcred *vfs_export_lookup(struct mount *, struct sockaddr *);
 
/*
 * Network address lookup element
 */
struct netcred {
        struct  radix_node netc_rnodes[2];
        uint64_t netc_exflags;
        struct  ucred *netc_anon;
        int     netc_numsecflavors;
        int     netc_secflavors[MAXSECFLAVORS];
};
 
/*
 * Network export information
 */
struct netexport {
        struct  netcred ne_defexported;               /* Default export */
        struct  radix_node_head *ne4;
        struct  radix_node_head *ne6;
};
 
/*
 * Build hash lists of net addresses and hang them off the mount point.
 * Called by vfs_export() to set up the lists of export addresses.
 */
static int
vfs_hang_addrlist(struct mount *mp, struct netexport *nep,
    struct export_args *argp)
{
        struct netcred *np;
        struct radix_node_head *rnh;
        int i;
        struct radix_node *rn;
        struct sockaddr *saddr, *smask = NULL;
#if defined(INET6) || defined(INET)
        int off;
#endif
        int error;
 
        KASSERT(argp->ex_numsecflavors > 0,
            ("%s: numsecflavors <= 0", __func__));
        KASSERT(argp->ex_numsecflavors < MAXSECFLAVORS,
            ("%s: numsecflavors >= MAXSECFLAVORS", __func__));
 
        /*
         * XXX: This routine converts from a uid plus gid list
         * to a `struct ucred' (np->netc_anon).  This
         * operation is questionable; for example, what should be done
         * with fields like cr_uidinfo and cr_prison?  Currently, this
         * routine does not touch them (leaves them as NULL).
         */
        if (argp->ex_addrlen == 0) {
                if (mp->mnt_flag & MNT_DEFEXPORTED) {
                        vfs_mount_error(mp,
                            "MNT_DEFEXPORTED already set for mount %p", mp);
                        return (EPERM);
                }
                np = &nep->ne_defexported;
                np->netc_exflags = argp->ex_flags;
                np->netc_anon = crget();
                np->netc_anon->cr_uid = argp->ex_uid;
                crsetgroups(np->netc_anon, argp->ex_ngroups,
                    argp->ex_groups);
                np->netc_anon->cr_prison = &prison0;
                prison_hold(np->netc_anon->cr_prison);
                np->netc_numsecflavors = argp->ex_numsecflavors;
                bcopy(argp->ex_secflavors, np->netc_secflavors,
                    sizeof(np->netc_secflavors));
                MNT_ILOCK(mp);
                mp->mnt_flag |= MNT_DEFEXPORTED;
                MNT_IUNLOCK(mp);
                return (0);
        }
 
#if MSIZE <= 256
        if (argp->ex_addrlen > MLEN) {
                vfs_mount_error(mp, "ex_addrlen %d is greater than %d",
                    argp->ex_addrlen, MLEN);
                return (EINVAL);
        }
#endif
 
        i = sizeof(struct netcred) + argp->ex_addrlen + argp->ex_masklen;
        np = (struct netcred *) malloc(i, M_NETADDR, M_WAITOK | M_ZERO);
        saddr = (struct sockaddr *) (np + 1);
        if ((error = copyin(argp->ex_addr, saddr, argp->ex_addrlen)))
                goto out;
        if (saddr->sa_family == AF_UNSPEC || saddr->sa_family > AF_MAX) {
                error = EINVAL;
                vfs_mount_error(mp, "Invalid saddr->sa_family: %d");
                goto out;
        }
        if (saddr->sa_len > argp->ex_addrlen)
                saddr->sa_len = argp->ex_addrlen;
        if (argp->ex_masklen) {
                smask = (struct sockaddr *)((caddr_t)saddr + argp->ex_addrlen);
                error = copyin(argp->ex_mask, smask, argp->ex_masklen);
                if (error)
                        goto out;
                if (smask->sa_len > argp->ex_masklen)
                        smask->sa_len = argp->ex_masklen;
        }
        rnh = NULL;
        switch (saddr->sa_family) {
#ifdef INET
        case AF_INET:
                if ((rnh = nep->ne4) == NULL) {
                        off = offsetof(struct sockaddr_in, sin_addr) << 3;
                        rnh = vfs_create_addrlist_af(&nep->ne4, off);
                }
                break;
#endif
#ifdef INET6
        case AF_INET6:
                if ((rnh = nep->ne6) == NULL) {
                        off = offsetof(struct sockaddr_in6, sin6_addr) << 3;
                        rnh = vfs_create_addrlist_af(&nep->ne6, off);
                }
                break;
#endif
        }
        if (rnh == NULL) {
                error = ENOBUFS;
                vfs_mount_error(mp, "%s %s %d",
                    "Unable to initialize radix node head ",
                    "for address family", saddr->sa_family);
                goto out;
        }
        RADIX_NODE_HEAD_LOCK(rnh);
        rn = (*rnh->rnh_addaddr)(saddr, smask, &rnh->rh, np->netc_rnodes);
        RADIX_NODE_HEAD_UNLOCK(rnh);
        if (rn == NULL || np != (struct netcred *)rn) { /* already exists */
                error = EPERM;
                vfs_mount_error(mp,
                    "netcred already exists for given addr/mask");
                goto out;
        }
        np->netc_exflags = argp->ex_flags;
        np->netc_anon = crget();
        np->netc_anon->cr_uid = argp->ex_uid;
        crsetgroups(np->netc_anon, argp->ex_ngroups,
            argp->ex_groups);
        np->netc_anon->cr_prison = &prison0;
        prison_hold(np->netc_anon->cr_prison);
        np->netc_numsecflavors = argp->ex_numsecflavors;
        bcopy(argp->ex_secflavors, np->netc_secflavors,
            sizeof(np->netc_secflavors));
        return (0);
out:
        free(np, M_NETADDR);
        return (error);
}
 
/* Helper for vfs_free_addrlist. */
/* ARGSUSED */
static int
vfs_free_netcred(struct radix_node *rn, void *w)
{
        struct radix_node_head *rnh = (struct radix_node_head *) w;
        struct ucred *cred;
 
        (*rnh->rnh_deladdr) (rn->rn_key, rn->rn_mask, &rnh->rh);
        cred = ((struct netcred *)rn)->netc_anon;
        if (cred != NULL)
                crfree(cred);
        free(rn, M_NETADDR);
        return (0);
}
 
#if defined(INET) || defined(INET6)
static struct radix_node_head *
vfs_create_addrlist_af(struct radix_node_head **prnh, int off)
{
 
        if (rn_inithead((void **)prnh, off) == 0)
                return (NULL);
        RADIX_NODE_HEAD_LOCK_INIT(*prnh);
        return (*prnh);
}
#endif
 
static void
vfs_free_addrlist_af(struct radix_node_head **prnh)
{
        struct radix_node_head *rnh;
 
        rnh = *prnh;
        RADIX_NODE_HEAD_LOCK(rnh);
        (*rnh->rnh_walktree)(&rnh->rh, vfs_free_netcred, rnh);
        RADIX_NODE_HEAD_UNLOCK(rnh);
        RADIX_NODE_HEAD_DESTROY(rnh);
        rn_detachhead((void **)prnh);
        prnh = NULL;
}
 
/*
 * Free the net address hash lists that are hanging off the mount points.
 */
static void
vfs_free_addrlist(struct netexport *nep)
{
        struct ucred *cred;
 
        if (nep->ne4 != NULL)
                vfs_free_addrlist_af(&nep->ne4);
        if (nep->ne6 != NULL)
                vfs_free_addrlist_af(&nep->ne6);
 
        cred = nep->ne_defexported.netc_anon;
        if (cred != NULL)
                crfree(cred);
 
}
 
/*
 * High level function to manipulate export options on a mount point
 * and the passed in netexport.
 * Struct export_args *argp is the variable used to twiddle options,
 * the structure is described in sys/mount.h
 */
int
vfs_export(struct mount *mp, struct export_args *argp)
{
        struct netexport *nep;
        int error;
 
        if ((argp->ex_flags & (MNT_DELEXPORT | MNT_EXPORTED)) == 0)
                return (EINVAL);
 
        if ((argp->ex_flags & MNT_EXPORTED) != 0 &&
            (argp->ex_numsecflavors < 0
            || argp->ex_numsecflavors >= MAXSECFLAVORS))
                return (EINVAL);
 
        error = 0;
        lockmgr(&mp->mnt_explock, LK_EXCLUSIVE, NULL);
        nep = mp->mnt_export;
        if (argp->ex_flags & MNT_DELEXPORT) {
                if (nep == NULL) {
                        error = ENOENT;
                        goto out;
                }
                if (mp->mnt_flag & MNT_EXPUBLIC) {
                        vfs_setpublicfs(NULL, NULL, NULL);
                        MNT_ILOCK(mp);
                        mp->mnt_flag &= ~MNT_EXPUBLIC;
                        MNT_IUNLOCK(mp);
                }
                vfs_free_addrlist(nep);
                mp->mnt_export = NULL;
                free(nep, M_MOUNT);
                nep = NULL;
                MNT_ILOCK(mp);
                mp->mnt_flag &= ~(MNT_EXPORTED | MNT_DEFEXPORTED);
                MNT_IUNLOCK(mp);
        }
        if (argp->ex_flags & MNT_EXPORTED) {
                if (nep == NULL) {
                        nep = malloc(sizeof(struct netexport), M_MOUNT, M_WAITOK | M_ZERO);
                        mp->mnt_export = nep;
                }
                if (argp->ex_flags & MNT_EXPUBLIC) {
                        if ((error = vfs_setpublicfs(mp, nep, argp)) != 0)
                                goto out;
                        MNT_ILOCK(mp);
                        mp->mnt_flag |= MNT_EXPUBLIC;
                        MNT_IUNLOCK(mp);
                }
                if (argp->ex_numsecflavors == 0) {
                        argp->ex_numsecflavors = 1;
                        argp->ex_secflavors[0] = AUTH_SYS;
                }
                if ((error = vfs_hang_addrlist(mp, nep, argp)))
                        goto out;
                MNT_ILOCK(mp);
                mp->mnt_flag |= MNT_EXPORTED;
                MNT_IUNLOCK(mp);
        }
 
out:
        lockmgr(&mp->mnt_explock, LK_RELEASE, NULL);
        /*
         * Once we have executed the vfs_export() command, we do
         * not want to keep the "export" option around in the
         * options list, since that will cause subsequent MNT_UPDATE
         * calls to fail.  The export information is saved in
         * mp->mnt_export, so we can safely delete the "export" mount option
         * here.
         */
        vfs_deleteopt(mp->mnt_optnew, "export");
        vfs_deleteopt(mp->mnt_opt, "export");
        return (error);
}
 
/*
 * Set the publicly exported filesystem (WebNFS). Currently, only
 * one public filesystem is possible in the spec (RFC 2054 and 2055)
 */
int
vfs_setpublicfs(struct mount *mp, struct netexport *nep,
    struct export_args *argp)
{
        int error;
        struct vnode *rvp;
        char *cp;
 
        /*
         * mp == NULL -> invalidate the current info, the FS is
         * no longer exported. May be called from either vfs_export
         * or unmount, so check if it hasn't already been done.
         */
        if (mp == NULL) {
                if (nfs_pub.np_valid) {
                        nfs_pub.np_valid = 0;
                        if (nfs_pub.np_index != NULL) {
                                free(nfs_pub.np_index, M_TEMP);
                                nfs_pub.np_index = NULL;
                        }
                }
                return (0);
        }
 
        /*
         * Only one allowed at a time.
         */
        if (nfs_pub.np_valid != 0 && mp != nfs_pub.np_mount)
                return (EBUSY);
 
        /*
         * Get real filehandle for root of exported FS.
         */
        bzero(&nfs_pub.np_handle, sizeof(nfs_pub.np_handle));
        nfs_pub.np_handle.fh_fsid = mp->mnt_stat.f_fsid;
 
        if ((error = VFS_ROOT(mp, LK_EXCLUSIVE, &rvp)))
                return (error);
 
        if ((error = VOP_VPTOFH(rvp, &nfs_pub.np_handle.fh_fid)))
                return (error);
 
        vput(rvp);
 
        /*
         * If an indexfile was specified, pull it in.
         */
        if (argp->ex_indexfile != NULL) {
                if (nfs_pub.np_index == NULL)
                        nfs_pub.np_index = malloc(MAXNAMLEN + 1, M_TEMP,
                            M_WAITOK);
                error = copyinstr(argp->ex_indexfile, nfs_pub.np_index,
                    MAXNAMLEN, (size_t *)0);
                if (!error) {
                        /*
                         * Check for illegal filenames.
                         */
                        for (cp = nfs_pub.np_index; *cp; cp++) {
                                if (*cp == '/') {
                                        error = EINVAL;
                                        break;
                                }
                        }
                }
                if (error) {
                        free(nfs_pub.np_index, M_TEMP);
                        nfs_pub.np_index = NULL;
                        return (error);
                }
        }
 
        nfs_pub.np_mount = mp;
        nfs_pub.np_valid = 1;
        return (0);
}
 
/*
 * Used by the filesystems to determine if a given network address
 * (passed in 'nam') is present in their exports list, returns a pointer
 * to struct netcred so that the filesystem can examine it for
 * access rights (read/write/etc).
 */
static struct netcred *
vfs_export_lookup(struct mount *mp, struct sockaddr *nam)
{
        RADIX_NODE_HEAD_RLOCK_TRACKER;
        struct netexport *nep;
        struct netcred *np = NULL;
        struct radix_node_head *rnh;
        struct sockaddr *saddr;
 
        nep = mp->mnt_export;
        if (nep == NULL)
                return (NULL);
        if ((mp->mnt_flag & MNT_EXPORTED) == 0)
                return (NULL);
 
        /*
         * Lookup in the export list
         */
        if (nam != NULL) {
                saddr = nam;
                rnh = NULL;
                switch (saddr->sa_family) {
                case AF_INET:
                        rnh = nep->ne4;
                        break;
                case AF_INET6:
                        rnh = nep->ne6;
                        break;
                }
                if (rnh != NULL) {
                        RADIX_NODE_HEAD_RLOCK(rnh);
                        np = (struct netcred *) (*rnh->rnh_matchaddr)(saddr, &rnh->rh);
                        RADIX_NODE_HEAD_RUNLOCK(rnh);
                        if (np != NULL && (np->netc_rnodes->rn_flags & RNF_ROOT) != 0)
                                return (NULL);
                }
        }
 
        /*
         * If no address match, use the default if it exists.
         */
        if (np == NULL && (mp->mnt_flag & MNT_DEFEXPORTED) != 0)
                return (&nep->ne_defexported);
 
        return (np);
}
 
/*
 * XXX: This comment comes from the deprecated ufs_check_export()
 * XXX: and may not entirely apply, but lacking something better:
 * This is the generic part of fhtovp called after the underlying
 * filesystem has validated the file handle.
 *
 * Verify that a host should have access to a filesystem.
 */
 
int
vfs_stdcheckexp(struct mount *mp, struct sockaddr *nam, uint64_t *extflagsp,
    struct ucred **credanonp, int *numsecflavors, int *secflavors)
{
        struct netcred *np;
 
        lockmgr(&mp->mnt_explock, LK_SHARED, NULL);
        np = vfs_export_lookup(mp, nam);
        if (np == NULL) {
                lockmgr(&mp->mnt_explock, LK_RELEASE, NULL);
                *credanonp = NULL;
                return (EACCES);
        }
        *extflagsp = np->netc_exflags;
        if ((*credanonp = np->netc_anon) != NULL)
                crhold(*credanonp);
        if (numsecflavors) {
                *numsecflavors = np->netc_numsecflavors;
                KASSERT(*numsecflavors > 0,
                    ("%s: numsecflavors <= 0", __func__));
                KASSERT(*numsecflavors < MAXSECFLAVORS,
                    ("%s: numsecflavors >= MAXSECFLAVORS", __func__));
        }
        if (secflavors && np->netc_numsecflavors > 0)
                memcpy(secflavors, np->netc_secflavors, np->netc_numsecflavors *
                    sizeof(int));
        lockmgr(&mp->mnt_explock, LK_RELEASE, NULL);
        return (0);
}