/*
 * linux/fs/nfsd/nfsfh.c
 *
 * NFS server file handle treatment.
 *
 * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
 * Portions Copyright (C) 1999 G. Allen Morris III <gam3@acm.org>
 * Extensive rewrite by Neil Brown <neilb@cse.unsw.edu.au> Southern-Spring 1999
 * ... and again Southern-Winter 2001 to support export_operations
 */

#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/unistd.h>
#include <linux/string.h>
#include <linux/stat.h>
#include <linux/dcache.h>
#include <linux/exportfs.h>
#include <linux/mount.h>

#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/svc.h>
#include <linux/sunrpc/svcauth_gss.h>
#include <linux/nfsd/nfsd.h>

#define NFSDDBG_FACILITY                NFSDDBG_FH


static int nfsd_nr_verified;
static int nfsd_nr_put;

/*
 * our acceptability function.
 * if NOSUBTREECHECK, accept anything
 * if not, require that we can walk up to exp->ex_dentry
 * doing some checks on the 'x' bits
 */
static int nfsd_acceptable(void *expv, struct dentry *dentry)
{
        struct svc_export *exp = expv;
        int rv;
        struct dentry *tdentry;
        struct dentry *parent;

        if (exp->ex_flags & NFSEXP_NOSUBTREECHECK)
                return 1;

        tdentry = dget(dentry);
        while (tdentry != exp->ex_dentry && ! IS_ROOT(tdentry)) {
                /* make sure parents give x permission to user */
                int err;
                parent = dget_parent(tdentry);
                err = permission(parent->d_inode, MAY_EXEC, NULL);
                if (err < 0) {
                        dput(parent);
                        break;
                }
                dput(tdentry);
                tdentry = parent;
        }
        if (tdentry != exp->ex_dentry)
                dprintk("nfsd_acceptable failed at %p %s\n", tdentry, tdentry->d_name.name);
        rv = (tdentry == exp->ex_dentry);
        dput(tdentry);
        return rv;
}

/* Type check. The correct error return for type mismatches does not seem to be
 * generally agreed upon. SunOS seems to use EISDIR if file isn't S_IFREG; a
 * comment in the NFSv3 spec says this is incorrect (implementation notes for
 * the write call).
 */
static inline __be32
nfsd_mode_check(struct svc_rqst *rqstp, umode_t mode, int type)
{
        /* Type can be negative when creating hardlinks - not to a dir */
        if (type > 0 && (mode & S_IFMT) != type) {
                if (rqstp->rq_vers == 4 && (mode & S_IFMT) == S_IFLNK)
                        return nfserr_symlink;
                else if (type == S_IFDIR)
                        return nfserr_notdir;
                else if ((mode & S_IFMT) == S_IFDIR)
                        return nfserr_isdir;
                else
                        return nfserr_inval;
        }
        if (type < 0 && (mode & S_IFMT) == -type) {
                if (rqstp->rq_vers == 4 && (mode & S_IFMT) == S_IFLNK)
                        return nfserr_symlink;
                else if (type == -S_IFDIR)
                        return nfserr_isdir;
                else
                        return nfserr_notdir;
        }
        return 0;
}

static __be32 nfsd_setuser_and_check_port(struct svc_rqst *rqstp,
                                          struct svc_export *exp)
{
        /* Check if the request originated from a secure port. */
        if (!rqstp->rq_secure && EX_SECURE(exp)) {
                char buf[RPC_MAX_ADDRBUFLEN];
                dprintk(KERN_WARNING
                       "nfsd: request from insecure port %s!\n",
                       svc_print_addr(rqstp, buf, sizeof(buf)));
                return nfserr_perm;
        }

        /* Set user creds for this exportpoint */
        return nfserrno(nfsd_setuser(rqstp, exp));
}

/*
 * Perform sanity checks on the dentry in a client's file handle.
 *
 * Note that the file handle dentry may need to be freed even after
 * an error return.
 *
 * This is only called at the start of an nfsproc call, so fhp points to
 * a svc_fh which is all 0 except for the over-the-wire file handle.
 */
__be32
fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, int type, int access)
{
        struct knfsd_fh *fh = &fhp->fh_handle;
        struct svc_export *exp = NULL;
        struct dentry   *dentry;
        __be32          error = 0;

        dprintk("nfsd: fh_verify(%s)\n", SVCFH_fmt(fhp));

        if (!fhp->fh_dentry) {
                struct fid *fid = NULL, sfid;
                int fileid_type;
                int data_left = fh->fh_size/4;

                error = nfserr_stale;
                if (rqstp->rq_vers > 2)
                        error = nfserr_badhandle;
                if (rqstp->rq_vers == 4 && fh->fh_size == 0)
                        return nfserr_nofilehandle;

                if (fh->fh_version == 1) {
                        int len;
                        if (--data_left<0) goto out;
                        switch (fh->fh_auth_type) {
                        case 0: break;
                        default: goto out;
                        }
                        len = key_len(fh->fh_fsid_type) / 4;
                        if (len == 0) goto out;
                        if  (fh->fh_fsid_type == FSID_MAJOR_MINOR) {
                                /* deprecated, convert to type 3 */
                                len = key_len(FSID_ENCODE_DEV)/4;
                                fh->fh_fsid_type = FSID_ENCODE_DEV;
                                fh->fh_fsid[0] = new_encode_dev(MKDEV(ntohl(fh->fh_fsid[0]), ntohl(fh->fh_fsid[1])));
                                fh->fh_fsid[1] = fh->fh_fsid[2];
                        }
                        if ((data_left -= len)<0) goto out;
                        exp = rqst_exp_find(rqstp, fh->fh_fsid_type,
                                            fh->fh_auth);
                        fid = (struct fid *)(fh->fh_auth + len);
                } else {
                        __u32 tfh[2];
                        dev_t xdev;
                        ino_t xino;
                        if (fh->fh_size != NFS_FHSIZE)
                                goto out;
                        /* assume old filehandle format */
                        xdev = old_decode_dev(fh->ofh_xdev);
                        xino = u32_to_ino_t(fh->ofh_xino);
                        mk_fsid(FSID_DEV, tfh, xdev, xino, 0, NULL);
                        exp = rqst_exp_find(rqstp, FSID_DEV, tfh);
                }

                error = nfserr_stale;
                if (PTR_ERR(exp) == -ENOENT)
                        goto out;

                if (IS_ERR(exp)) {
                        error = nfserrno(PTR_ERR(exp));
                        goto out;
                }

                error = nfsd_setuser_and_check_port(rqstp, exp);
                if (error)
                        goto out;

                /*
                 * Look up the dentry using the NFS file handle.
                 */
                error = nfserr_stale;
                if (rqstp->rq_vers > 2)
                        error = nfserr_badhandle;

                if (fh->fh_version != 1) {
                        sfid.i32.ino = fh->ofh_ino;
                        sfid.i32.gen = fh->ofh_generation;
                        sfid.i32.parent_ino = fh->ofh_dirino;
                        fid = &sfid;
                        data_left = 3;
                        if (fh->ofh_dirino == 0)
                                fileid_type = FILEID_INO32_GEN;
                        else
                                fileid_type = FILEID_INO32_GEN_PARENT;
                } else
                        fileid_type = fh->fh_fileid_type;

                if (fileid_type == FILEID_ROOT)
                        dentry = dget(exp->ex_dentry);
                else {
                        dentry = exportfs_decode_fh(exp->ex_mnt, fid,
                                        data_left, fileid_type,
                                        nfsd_acceptable, exp);
                }
                if (dentry == NULL)
                        goto out;
                if (IS_ERR(dentry)) {
                        if (PTR_ERR(dentry) != -EINVAL)
                                error = nfserrno(PTR_ERR(dentry));
                        goto out;
                }

                if (S_ISDIR(dentry->d_inode->i_mode) &&
                    (dentry->d_flags & DCACHE_DISCONNECTED)) {
                        printk("nfsd: find_fh_dentry returned a DISCONNECTED directory: %s/%s\n",
                               dentry->d_parent->d_name.name, dentry->d_name.name);
                }

                fhp->fh_dentry = dentry;
                fhp->fh_export = exp;
                nfsd_nr_verified++;
        } else {
                /*
                 * just rechecking permissions
                 * (e.g. nfsproc_create calls fh_verify, then nfsd_create
                 * does as well)
                 */
                dprintk("nfsd: fh_verify - just checking\n");
                dentry = fhp->fh_dentry;
                exp = fhp->fh_export;
                /*
                 * Set user creds for this exportpoint; necessary even
                 * in the "just checking" case because this may be a
                 * filehandle that was created by fh_compose, and that
                 * is about to be used in another nfsv4 compound
                 * operation.
                 */
                error = nfsd_setuser_and_check_port(rqstp, exp);
                if (error)
                        goto out;
        }
        cache_get(&exp->h);


        error = nfsd_mode_check(rqstp, dentry->d_inode->i_mode, type);
        if (error)
                goto out;

        if (!(access & MAY_LOCK)) {
                /*
                 * pseudoflavor restrictions are not enforced on NLM,
                 * which clients virtually always use auth_sys for,
                 * even while using RPCSEC_GSS for NFS.
                 */
                error = check_nfsd_access(exp, rqstp);
                if (error)
                        goto out;
        }

        /* Finally, check access permissions. */
        error = nfsd_permission(rqstp, exp, dentry, access);

        if (error) {
                dprintk("fh_verify: %s/%s permission failure, "
                        "acc=%x, error=%d\n",
                        dentry->d_parent->d_name.name,
                        dentry->d_name.name,
                        access, ntohl(error));
        }
out:
        if (exp && !IS_ERR(exp))
                exp_put(exp);
        if (error == nfserr_stale)
                nfsdstats.fh_stale++;
        return error;
}


/*
 * Compose a file handle for an NFS reply.
 *
 * Note that when first composed, the dentry may not yet have
 * an inode.  In this case a call to fh_update should be made
 * before the fh goes out on the wire ...
 */
static void _fh_update(struct svc_fh *fhp, struct svc_export *exp,
                struct dentry *dentry)
{
        if (dentry != exp->ex_dentry) {
                struct fid *fid = (struct fid *)
                        (fhp->fh_handle.fh_auth + fhp->fh_handle.fh_size/4 - 1);
                int maxsize = (fhp->fh_maxsize - fhp->fh_handle.fh_size)/4;
                int subtreecheck = !(exp->ex_flags & NFSEXP_NOSUBTREECHECK);

                fhp->fh_handle.fh_fileid_type =
                        exportfs_encode_fh(dentry, fid, &maxsize, subtreecheck);
                fhp->fh_handle.fh_size += maxsize * 4;
        } else {
                fhp->fh_handle.fh_fileid_type = FILEID_ROOT;
        }
}

/*
 * for composing old style file handles
 */
static inline void _fh_update_old(struct dentry *dentry,
                                  struct svc_export *exp,
                                  struct knfsd_fh *fh)
{
        fh->ofh_ino = ino_t_to_u32(dentry->d_inode->i_ino);
        fh->ofh_generation = dentry->d_inode->i_generation;
        if (S_ISDIR(dentry->d_inode->i_mode) ||
            (exp->ex_flags & NFSEXP_NOSUBTREECHECK))
                fh->ofh_dirino = 0;
}

__be32
fh_compose(struct svc_fh *fhp, struct svc_export *exp, struct dentry *dentry,
           struct svc_fh *ref_fh)
{
        /* ref_fh is a reference file handle.
         * if it is non-null and for the same filesystem, then we should compose
         * a filehandle which is of the same version, where possible.
         * Currently, that means that if ref_fh->fh_handle.fh_version == 0xca
         * Then create a 32byte filehandle using nfs_fhbase_old
         *
         */

        u8 version;
        u8 fsid_type = 0;
        struct inode * inode = dentry->d_inode;
        struct dentry *parent = dentry->d_parent;
        __u32 *datap;
        dev_t ex_dev = exp->ex_dentry->d_inode->i_sb->s_dev;
        int root_export = (exp->ex_dentry == exp->ex_dentry->d_sb->s_root);

        dprintk("nfsd: fh_compose(exp %02x:%02x/%ld %s/%s, ino=%ld)\n",
                MAJOR(ex_dev), MINOR(ex_dev),
                (long) exp->ex_dentry->d_inode->i_ino,
                parent->d_name.name, dentry->d_name.name,
                (inode ? inode->i_ino : 0));

        /* Choose filehandle version and fsid type based on
         * the reference filehandle (if it is in the same export)
         * or the export options.
         */
 retry:
        version = 1;
        if (ref_fh && ref_fh->fh_export == exp) {
                version = ref_fh->fh_handle.fh_version;
                fsid_type = ref_fh->fh_handle.fh_fsid_type;

                if (ref_fh == fhp)
                        fh_put(ref_fh);
                ref_fh = NULL;

                switch (version) {
                case 0xca:
                        fsid_type = FSID_DEV;
                        break;
                case 1:
                        break;
                default:
                        goto retry;
                }

                /* Need to check that this type works for this
                 * export point.  As the fsid -> filesystem mapping
                 * was guided by user-space, there is no guarantee
                 * that the filesystem actually supports that fsid
                 * type. If it doesn't we loop around again without
                 * ref_fh set.
                 */
                switch(fsid_type) {
                case FSID_DEV:
                        if (!old_valid_dev(ex_dev))
                                goto retry;
                        /* FALL THROUGH */
                case FSID_MAJOR_MINOR:
                case FSID_ENCODE_DEV:
                        if (!(exp->ex_dentry->d_inode->i_sb->s_type->fs_flags
                              & FS_REQUIRES_DEV))
                                goto retry;
                        break;
                case FSID_NUM:
                        if (! (exp->ex_flags & NFSEXP_FSID))
                                goto retry;
                        break;
                case FSID_UUID8:
                case FSID_UUID16:
                        if (!root_export)
                                goto retry;
                        /* fall through */
                case FSID_UUID4_INUM:
                case FSID_UUID16_INUM:
                        if (exp->ex_uuid == NULL)
                                goto retry;
                        break;
                }
        } else if (exp->ex_uuid) {
                if (fhp->fh_maxsize >= 64) {
                        if (root_export)
                                fsid_type = FSID_UUID16;
                        else
                                fsid_type = FSID_UUID16_INUM;
                } else {
                        if (root_export)
                                fsid_type = FSID_UUID8;
                        else
                                fsid_type = FSID_UUID4_INUM;
                }
        } else if (exp->ex_flags & NFSEXP_FSID)
                fsid_type = FSID_NUM;
        else if (!old_valid_dev(ex_dev))
                /* for newer device numbers, we must use a newer fsid format */
                fsid_type = FSID_ENCODE_DEV;
        else
                fsid_type = FSID_DEV;

        if (ref_fh == fhp)
                fh_put(ref_fh);

        if (fhp->fh_locked || fhp->fh_dentry) {
                printk(KERN_ERR "fh_compose: fh %s/%s not initialized!\n",
                       parent->d_name.name, dentry->d_name.name);
        }
        if (fhp->fh_maxsize < NFS_FHSIZE)
                printk(KERN_ERR "fh_compose: called with maxsize %d! %s/%s\n",
                       fhp->fh_maxsize,
                       parent->d_name.name, dentry->d_name.name);

        fhp->fh_dentry = dget(dentry); /* our internal copy */
        fhp->fh_export = exp;
        cache_get(&exp->h);

        if (version == 0xca) {
                /* old style filehandle please */
                memset(&fhp->fh_handle.fh_base, 0, NFS_FHSIZE);
                fhp->fh_handle.fh_size = NFS_FHSIZE;
                fhp->fh_handle.ofh_dcookie = 0xfeebbaca;
                fhp->fh_handle.ofh_dev =  old_encode_dev(ex_dev);
                fhp->fh_handle.ofh_xdev = fhp->fh_handle.ofh_dev;
                fhp->fh_handle.ofh_xino =
                        ino_t_to_u32(exp->ex_dentry->d_inode->i_ino);
                fhp->fh_handle.ofh_dirino = ino_t_to_u32(parent_ino(dentry));
                if (inode)
                        _fh_update_old(dentry, exp, &fhp->fh_handle);
        } else {
                int len;
                fhp->fh_handle.fh_version = 1;
                fhp->fh_handle.fh_auth_type = 0;
                datap = fhp->fh_handle.fh_auth+0;
                fhp->fh_handle.fh_fsid_type = fsid_type;
                mk_fsid(fsid_type, datap, ex_dev,
                        exp->ex_dentry->d_inode->i_ino,
                        exp->ex_fsid, exp->ex_uuid);

                len = key_len(fsid_type);
                datap += len/4;
                fhp->fh_handle.fh_size = 4 + len;

                if (inode)
                        _fh_update(fhp, exp, dentry);
                if (fhp->fh_handle.fh_fileid_type == 255)
                        return nfserr_opnotsupp;
        }

        nfsd_nr_verified++;
        return 0;
}

/*
 * Update file handle information after changing a dentry.
 * This is only called by nfsd_create, nfsd_create_v3 and nfsd_proc_create
 */
__be32
fh_update(struct svc_fh *fhp)
{
        struct dentry *dentry;

        if (!fhp->fh_dentry)
                goto out_bad;

        dentry = fhp->fh_dentry;
        if (!dentry->d_inode)
                goto out_negative;
        if (fhp->fh_handle.fh_version != 1) {
                _fh_update_old(dentry, fhp->fh_export, &fhp->fh_handle);
        } else {
                if (fhp->fh_handle.fh_fileid_type != FILEID_ROOT)
                        goto out;

                _fh_update(fhp, fhp->fh_export, dentry);
                if (fhp->fh_handle.fh_fileid_type == 255)
                        return nfserr_opnotsupp;
        }
out:
        return 0;

out_bad:
        printk(KERN_ERR "fh_update: fh not verified!\n");
        goto out;
out_negative:
        printk(KERN_ERR "fh_update: %s/%s still negative!\n",
                dentry->d_parent->d_name.name, dentry->d_name.name);
        goto out;
}

/*
 * Release a file handle.
 */
void
fh_put(struct svc_fh *fhp)
{
        struct dentry * dentry = fhp->fh_dentry;
        struct svc_export * exp = fhp->fh_export;
        if (dentry) {
                fh_unlock(fhp);
                fhp->fh_dentry = NULL;
                dput(dentry);
#ifdef CONFIG_NFSD_V3
                fhp->fh_pre_saved = 0;
                fhp->fh_post_saved = 0;
#endif
                nfsd_nr_put++;
        }
        if (exp) {
                cache_put(&exp->h, &svc_export_cache);
                fhp->fh_export = NULL;
        }
        return;
}

/*
 * Shorthand for dprintk()'s
 */
char * SVCFH_fmt(struct svc_fh *fhp)
{
        struct knfsd_fh *fh = &fhp->fh_handle;

        static char buf[80];
        sprintf(buf, "%d: %08x %08x %08x %08x %08x %08x",
                fh->fh_size,
                fh->fh_base.fh_pad[0],
                fh->fh_base.fh_pad[1],
                fh->fh_base.fh_pad[2],
                fh->fh_base.fh_pad[3],
                fh->fh_base.fh_pad[4],
                fh->fh_base.fh_pad[5]);
        return buf;
}

enum fsid_source fsid_source(struct svc_fh *fhp)
{
        if (fhp->fh_handle.fh_version != 1)
                return FSIDSOURCE_DEV;
        switch(fhp->fh_handle.fh_fsid_type) {
        case FSID_DEV:
        case FSID_ENCODE_DEV:
        case FSID_MAJOR_MINOR:
                if (fhp->fh_export->ex_dentry->d_inode->i_sb->s_type->fs_flags
                    & FS_REQUIRES_DEV)
                        return FSIDSOURCE_DEV;
                break;
        case FSID_NUM:
                if (fhp->fh_export->ex_flags & NFSEXP_FSID)
                        return FSIDSOURCE_FSID;
                break;
        default:
                break;
        }
        /* either a UUID type filehandle, or the filehandle doesn't
         * match the export.
         */
        if (fhp->fh_export->ex_flags & NFSEXP_FSID)
                return FSIDSOURCE_FSID;
        if (fhp->fh_export->ex_uuid)
                return FSIDSOURCE_UUID;
        return FSIDSOURCE_DEV;
}