/*      $NetBSD: nfs_srvsubs.c,v 1.17 2023/03/23 19:52:42 riastradh Exp $       */

/*
 * Copyright (c) 1989, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Rick Macklem at The University of Guelph.
 *
 * 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.
 *
 *      @(#)nfs_subs.c  8.8 (Berkeley) 5/22/95
 */

/*
 * Copyright 2000 Wasabi Systems, Inc.
 * All rights reserved.
 *
 * Written by Frank van der Linden for Wasabi Systems, 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed for the NetBSD Project by
 *      Wasabi Systems, Inc.
 * 4. The name of Wasabi Systems, Inc. may not be used to endorse
 *    or promote products derived from this software without specific prior
 *    written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY WASABI SYSTEMS, INC. ``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 WASABI SYSTEMS, INC
 * 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.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: nfs_srvsubs.c,v 1.17 2023/03/23 19:52:42 riastradh Exp $");

#include <sys/param.h>
#include <sys/proc.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/kmem.h>
#include <sys/mount.h>
#include <sys/vnode.h>
#include <sys/namei.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/filedesc.h>
#include <sys/time.h>
#include <sys/dirent.h>
#include <sys/once.h>
#include <sys/kauth.h>
#include <sys/atomic.h>

#include <uvm/uvm_extern.h>

#include <nfs/rpcv2.h>
#include <nfs/nfsproto.h>
#include <nfs/nfsnode.h>
#include <nfs/nfs.h>
#include <nfs/xdr_subs.h>
#include <nfs/nfsm_subs.h>
#include <nfs/nfsmount.h>
#include <nfs/nfsrtt.h>
#include <nfs/nfs_var.h>

#include <miscfs/specfs/specdev.h>

#include <netinet/in.h>

/*
 * Set up nameidata for a lookup() call and do it.
 *
 * If pubflag is set, this call is done for a lookup operation on the
 * public filehandle. In that case we allow crossing mountpoints and
 * absolute pathnames. However, the caller is expected to check that
 * the lookup result is within the public fs, and deny access if
 * it is not.
 */
int
nfs_namei(struct nameidata *ndp, nfsrvfh_t *nsfh, uint32_t len, struct nfssvc_sock *slp, struct mbuf *nam, struct mbuf **mdp, char **dposp, struct vnode **retdirp, int *dirattr_retp, struct vattr *dirattrp, struct lwp *l, int kerbflag, int pubflag)
{
        int i, rem;
        struct mbuf *md;
        char *fromcp, *tocp, *cp, *path;
        struct vnode *dp;
        int error, rdonly;
        int neverfollow;
        struct componentname *cnp = &ndp->ni_cnd;

        *retdirp = NULL;
        ndp->ni_pathbuf = NULL;

        if (len > NFS_MAXPATHLEN - 1)
                return (ENAMETOOLONG);
        if (len == 0)
                return (EACCES);

        /*
         * Copy the name from the mbuf list to ndp->ni_pathbuf
         * and set the various ndp fields appropriately.
         */
        path = PNBUF_GET();
        fromcp = *dposp;
        tocp = path;
        md = *mdp;
        rem = mtod(md, char *) + md->m_len - fromcp;
        for (i = 0; i < len; i++) {
                while (rem == 0) {
                        md = md->m_next;
                        if (md == NULL) {
                                error = EBADRPC;
                                goto out;
                        }
                        fromcp = mtod(md, void *);
                        rem = md->m_len;
                }
                if (*fromcp == '\0' || (!pubflag && *fromcp == '/')) {
                        error = EACCES;
                        goto out;
                }
                *tocp++ = *fromcp++;
                rem--;
        }
        *tocp = '\0';
        *mdp = md;
        *dposp = fromcp;
        len = nfsm_rndup(len)-len;
        if (len > 0) {
                if (rem >= len)
                        *dposp += len;
                else if ((error = nfs_adv(mdp, dposp, len, rem)) != 0)
                        goto out;
        }

        /*
         * Extract and set starting directory.
         */
        error = nfsrv_fhtovp(nsfh, false, &dp, ndp->ni_cnd.cn_cred, slp,
            nam, &rdonly, kerbflag, pubflag);
        if (error)
                goto out;
        if (dp->v_type != VDIR) {
                vrele(dp);
                error = ENOTDIR;
                goto out;
        }

        if (rdonly)
                cnp->cn_flags |= RDONLY;

        *retdirp = dp;
        if (dirattr_retp != NULL) {
                vn_lock(dp, LK_SHARED | LK_RETRY);
                *dirattr_retp = VOP_GETATTR(dp, dirattrp, ndp->ni_cnd.cn_cred);
                VOP_UNLOCK(dp);
        }

        if (pubflag) {
                /*
                 * Oh joy. For WebNFS, handle those pesky '%' escapes,
                 * and the 'native path' indicator.
                 */
                cp = PNBUF_GET();
                fromcp = path;
                tocp = cp;
                if ((unsigned char)*fromcp >= WEBNFS_SPECCHAR_START) {
                        switch ((unsigned char)*fromcp) {
                        case WEBNFS_NATIVE_CHAR:
                                /*
                                 * 'Native' path for us is the same
                                 * as a path according to the NFS spec,
                                 * just skip the escape char.
                                 */
                                fromcp++;
                                break;
                        /*
                         * More may be added in the future, range 0x80-0xff
                         */
                        default:
                                error = EIO;
                                vrele(dp);
                                PNBUF_PUT(cp);
                                goto out;
                        }
                }
                /*
                 * Translate the '%' escapes, URL-style.
                 */
                while (*fromcp != '\0') {
                        if (*fromcp == WEBNFS_ESC_CHAR) {
                                if (fromcp[1] != '\0' && fromcp[2] != '\0') {
                                        fromcp++;
                                        *tocp++ = HEXSTRTOI(fromcp);
                                        fromcp += 2;
                                        continue;
                                } else {
                                        error = ENOENT;
                                        vrele(dp);
                                        PNBUF_PUT(cp);
                                        goto out;
                                }
                        } else
                                *tocp++ = *fromcp++;
                }
                *tocp = '\0';
                PNBUF_PUT(path);
                path = cp;
        }

        ndp->ni_atdir = NULL;
        ndp->ni_pathbuf = pathbuf_assimilate(path);
        if (ndp->ni_pathbuf == NULL) {
                error = ENOMEM;
                goto out;
        }

        if (pubflag) {
                if (path[0] == '/')
                        dp = rootvnode;
        } else {
                cnp->cn_flags |= NOCROSSMOUNT;
        }

        neverfollow = !pubflag;

        /*
         * And call lookup() to do the real work
         *
         * Note: ndp->ni_pathbuf is left undestroyed on success;
         * caller must clean it up.
         */
        error = lookup_for_nfsd(ndp, dp, neverfollow);
        if (error) {
                goto out;
        }
        return 0;

out:
        if (ndp->ni_pathbuf != NULL) {
                pathbuf_destroy(ndp->ni_pathbuf);
                ndp->ni_pathbuf = NULL;
        } else {
                PNBUF_PUT(path);
        }
        return (error);
}

/*
 * nfsrv_fhtovp() - convert a fh to a vnode ptr (optionally locked)
 *      - look up fsid in mount list (if not found ret error)
 *      - get vp and export rights by calling VFS_FHTOVP()
 *      - if cred->cr_uid == 0 or MNT_EXPORTANON set it to credanon
 *      - if not lockflag unlock it with VOP_UNLOCK()
 */
int
nfsrv_fhtovp(nfsrvfh_t *nsfh, int lockflag, struct vnode **vpp,
    kauth_cred_t cred, struct nfssvc_sock *slp, struct mbuf *nam, int *rdonlyp,
    int kerbflag, int pubflag)
{
        struct mount *mp;
        kauth_cred_t credanon;
        int error, exflags;
        struct sockaddr_in *saddr;
        fhandle_t *fhp;

        fhp = NFSRVFH_FHANDLE(nsfh);
        *vpp = (struct vnode *)0;

        if (nfs_ispublicfh(nsfh)) {
                if (!pubflag || !nfs_pub.np_valid)
                        return (ESTALE);
                fhp = nfs_pub.np_handle;
        }

        error = netexport_check(&fhp->fh_fsid, nam, &mp, &exflags, &credanon);
        if (error) {
                return error;
        }

        error = VFS_FHTOVP(mp, &fhp->fh_fid, LK_EXCLUSIVE, vpp);
        if (error)
                return (error);

        if (!(exflags & (MNT_EXNORESPORT|MNT_EXPUBLIC))) {
                saddr = mtod(nam, struct sockaddr_in *);
                if ((saddr->sin_family == AF_INET) &&
                    ntohs(saddr->sin_port) >= IPPORT_RESERVED) {
                        vput(*vpp);
                        return (NFSERR_AUTHERR | AUTH_TOOWEAK);
                }
                if ((saddr->sin_family == AF_INET6) &&
                    ntohs(saddr->sin_port) >= IPV6PORT_RESERVED) {
                        vput(*vpp);
                        return (NFSERR_AUTHERR | AUTH_TOOWEAK);
                }
        }
        /*
         * Check/setup credentials.
         */
        if (exflags & MNT_EXKERB) {
                if (!kerbflag) {
                        vput(*vpp);
                        return (NFSERR_AUTHERR | AUTH_TOOWEAK);
                }
        } else if (kerbflag) {
                vput(*vpp);
                return (NFSERR_AUTHERR | AUTH_TOOWEAK);
        } else if (kauth_cred_geteuid(cred) == 0 || /* NFS maproot, see below */
            (exflags & MNT_EXPORTANON)) {
                /*
                 * This is used by the NFS maproot option. While we can change
                 * the secmodel on our own host, we can't change it on the
                 * clients. As means of least surprise, we're doing the
                 * traditional thing here.
                 * Should look into adding a "mapprivileged" or similar where
                 * the users can be explicitly specified...
                 * [elad, yamt 2008-03-05]
                 */
                kauth_cred_clone(credanon, cred);
        }
        if (exflags & MNT_EXRDONLY)
                *rdonlyp = 1;
        else
                *rdonlyp = 0;
        if (!lockflag)
                VOP_UNLOCK(*vpp);
        return (0);
}

/*
 * WebNFS: check if a filehandle is a public filehandle. For v3, this
 * means a length of 0, for v2 it means all zeroes.
 */
int
nfs_ispublicfh(const nfsrvfh_t *nsfh)
{
        const char *cp = (const void *)(NFSRVFH_DATA(nsfh));
        int i;

        if (NFSRVFH_SIZE(nsfh) == 0) {
                return true;
        }
        if (NFSRVFH_SIZE(nsfh) != NFSX_V2FH) {
                return false;
        }
        for (i = 0; i < NFSX_V2FH; i++)
                if (*cp++ != 0)
                        return false;
        return true;
}

int
nfsrv_composefh(struct vnode *vp, nfsrvfh_t *nsfh, bool v3)
{
        int error;
        size_t fhsize;

        fhsize = NFSD_MAXFHSIZE;
        error = vfs_composefh(vp, (void *)NFSRVFH_DATA(nsfh), &fhsize);
        if (NFSX_FHTOOBIG_P(fhsize, v3)) {
                error = EOPNOTSUPP;
        }
        if (error != 0) {
                return error;
        }
        if (!v3 && fhsize < NFSX_V2FH) {
                memset((char *)NFSRVFH_DATA(nsfh) + fhsize, 0,
                    NFSX_V2FH - fhsize);
                fhsize = NFSX_V2FH;
        }
        if ((fhsize % NFSX_UNSIGNED) != 0) {
                return EOPNOTSUPP;
        }
        nsfh->nsfh_size = fhsize;
        return 0;
}

int
nfsrv_comparefh(const nfsrvfh_t *fh1, const nfsrvfh_t *fh2)
{

        if (NFSRVFH_SIZE(fh1) != NFSRVFH_SIZE(fh2)) {
                return NFSRVFH_SIZE(fh2) - NFSRVFH_SIZE(fh1);
        }
        return memcmp(NFSRVFH_DATA(fh1), NFSRVFH_DATA(fh2), NFSRVFH_SIZE(fh1));
}

void
nfsrv_copyfh(nfsrvfh_t *fh1, const nfsrvfh_t *fh2)
{
        size_t size;

        fh1->nsfh_size = size = NFSRVFH_SIZE(fh2);
        memcpy(NFSRVFH_DATA(fh1), NFSRVFH_DATA(fh2), size);
}