nfsfh.c

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/*
 * NFS server file handle treatment.
 *
 * Copyright (C) 1995, 1996 Olaf Kirch <[email protected]>
 * Portions Copyright (C) 1999 G. Allen Morris III <[email protected]>
 * Extensive rewrite by Neil Brown <[email protected]> Southern-Spring 1999
 * ... and again Southern-Winter 2001 to support export_operations
 */

#include <linux/exportfs.h>

#include <linux/sunrpc/svcauth_gss.h>
#include "nfsd.h"
#include "vfs.h"
#include "auth.h"

#define NFSDDBG_FACILITY        NFSDDBG_FH


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

    if (requested == 0) /* the caller doesn't care */
        return nfs_ok;
    if (mode == requested)
        return nfs_ok;
    /*
     * v4 has an error more specific than err_notdir which we should
     * return in preference to err_notdir:
     */
    if (rqstp->rq_vers == 4 && mode == S_IFLNK)
        return nfserr_symlink;
    if (requested == S_IFDIR)
        return nfserr_notdir;
    if (mode == S_IFDIR)
        return nfserr_isdir;
    return nfserr_inval;
}

static __be32 nfsd_setuser_and_check_port(struct svc_rqst *rqstp,
                      struct svc_export *exp)
{
    int flags = nfsexp_flags(rqstp, exp);

    /* Check if the request originated from a secure port. */
    if (!rqstp->rq_secure && !(flags & NFSEXP_INSECURE_PORT)) {
        RPC_IFDEBUG(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));
}

static inline __be32 check_pseudo_root(struct svc_rqst *rqstp,
    struct dentry *dentry, struct svc_export *exp)
{
    if (!(exp->ex_flags & NFSEXP_V4ROOT))
        return nfs_ok;
    /*
     * v2/v3 clients have no need for the V4ROOT export--they use
     * the mount protocl instead; also, further V4ROOT checks may be
     * in v4-specific code, in which case v2/v3 clients could bypass
     * them.
     */
    if (!nfsd_v4client(rqstp))
        return nfserr_stale;
    /*
     * We're exposing only the directories and symlinks that have to be
     * traversed on the way to real exports:
     */
    if (unlikely(!S_ISDIR(dentry->d_inode->i_mode) &&
             !S_ISLNK(dentry->d_inode->i_mode)))
        return nfserr_stale;
    /*
     * A pseudoroot export gives permission to access only one
     * single directory; the kernel has to make another upcall
     * before granting access to anything else under it:
     */
    if (unlikely(dentry != exp->ex_path.dentry))
        return nfserr_stale;
    return nfs_ok;
}

/*
 * Use the given filehandle to look up the corresponding export and
 * dentry.  On success, the results are used to set fh_export and
 * fh_dentry.
 */
static __be32 nfsd_set_fh_dentry(struct svc_rqst *rqstp, struct svc_fh *fhp)
{
    struct knfsd_fh *fh = &fhp->fh_handle;
    struct fid *fid = NULL, sfid;
    struct svc_export *exp;
    struct dentry *dentry;
    int fileid_type;
    int data_left = fh->fh_size/4;
    __be32 error;

    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)
            return error;
        if (fh->fh_auth_type != 0)
            return error;
        len = key_len(fh->fh_fsid_type) / 4;
        if (len == 0)
            return error;
        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];
        }
        data_left -= len;
        if (data_left < 0)
            return error;
        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)
            return error;
        /* 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)
        return error;

    if (IS_ERR(exp))
        return nfserrno(PTR_ERR(exp));

    if (exp->ex_flags & NFSEXP_NOSUBTREECHECK) {
        /* Elevate privileges so that the lack of 'r' or 'x'
         * permission on some parent directory will
         * not stop exportfs_decode_fh from being able
         * to reconnect a directory into the dentry cache.
         * The same problem can affect "SUBTREECHECK" exports,
         * but as nfsd_acceptable depends on correct
         * access control settings being in effect, we cannot
         * fix that case easily.
         */
        struct cred *new = prepare_creds();
        if (!new)
            return nfserrno(-ENOMEM);
        new->cap_effective =
            cap_raise_nfsd_set(new->cap_effective,
                       new->cap_permitted);
        put_cred(override_creds(new));
        put_cred(new);
    } else {
        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_path.dentry);
    else {
        dentry = exportfs_decode_fh(exp->ex_path.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;
    return 0;
out:
    exp_put(exp);
    return error;
}

__be32
fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type, int access)
{
    struct svc_export *exp;
    struct dentry   *dentry;
    __be32      error;

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

    if (!fhp->fh_dentry) {
        error = nfsd_set_fh_dentry(rqstp, fhp);
        if (error)
            goto out;
    }
    dentry = fhp->fh_dentry;
    exp = fhp->fh_export;
    /*
     * We still have to do all these permission checks, even when
     * fh_dentry is already set:
     *  - fh_verify may be called multiple times with different
     *    "access" arguments (e.g. nfsd_proc_create calls
     *    fh_verify(...,NFSD_MAY_EXEC) first, then later (in
     *    nfsd_create) calls fh_verify(...,NFSD_MAY_CREATE).
     *  - in the NFSv4 case, the filehandle may have been filled
     *    in by fh_compose, and given a dentry, but further
     *    compound operations performed with that filehandle
     *    still need permissions checks.  In the worst case, a
     *    mountpoint crossing may have changed the export
     *    options, and we may now need to use a different uid
     *    (for example, if different id-squashing options are in
     *    effect on the new filesystem).
     */
    error = check_pseudo_root(rqstp, dentry, exp);
    if (error)
        goto out;

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

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

    /*
     * pseudoflavor restrictions are not enforced on NLM,
     * which clients virtually always use auth_sys for,
     * even while using RPCSEC_GSS for NFS.
     */
    if (access & NFSD_MAY_LOCK || access & NFSD_MAY_BYPASS_GSS)
        goto skip_pseudoflavor_check;
    /*
     * Clients may expect to be able to use auth_sys during mount,
     * even if they use gss for everything else; see section 2.3.2
     * of rfc 2623.
     */
    if (access & NFSD_MAY_BYPASS_GSS_ON_ROOT
            && exp->ex_path.dentry == dentry)
        goto skip_pseudoflavor_check;

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

skip_pseudoflavor_check:
    /* 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 (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_path.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;
}

static bool is_root_export(struct svc_export *exp)
{
    return exp->ex_path.dentry == exp->ex_path.dentry->d_sb->s_root;
}

static struct super_block *exp_sb(struct svc_export *exp)
{
    return exp->ex_path.dentry->d_inode->i_sb;
}

static bool fsid_type_ok_for_exp(u8 fsid_type, struct svc_export *exp)
{
    switch (fsid_type) {
    case FSID_DEV:
        if (!old_valid_dev(exp_sb(exp)->s_dev))
            return 0;
        /* FALL THROUGH */
    case FSID_MAJOR_MINOR:
    case FSID_ENCODE_DEV:
        return exp_sb(exp)->s_type->fs_flags & FS_REQUIRES_DEV;
    case FSID_NUM:
        return exp->ex_flags & NFSEXP_FSID;
    case FSID_UUID8:
    case FSID_UUID16:
        if (!is_root_export(exp))
            return 0;
        /* fall through */
    case FSID_UUID4_INUM:
    case FSID_UUID16_INUM:
        return exp->ex_uuid != NULL;
    }
    return 1;
}


static void set_version_and_fsid_type(struct svc_fh *fhp, struct svc_export *exp, struct svc_fh *ref_fh)
{
    u8 version;
    u8 fsid_type;
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;

        ref_fh = NULL;

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

        /*
         * 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.
         */
        if (!fsid_type_ok_for_exp(fsid_type, exp))
            goto retry;
    } else if (exp->ex_flags & NFSEXP_FSID) {
        fsid_type = FSID_NUM;
    } else if (exp->ex_uuid) {
        if (fhp->fh_maxsize >= 64) {
            if (is_root_export(exp))
                fsid_type = FSID_UUID16;
            else
                fsid_type = FSID_UUID16_INUM;
        } else {
            if (is_root_export(exp))
                fsid_type = FSID_UUID8;
            else
                fsid_type = FSID_UUID4_INUM;
        }
    } else if (!old_valid_dev(exp_sb(exp)->s_dev))
        /* for newer device numbers, we must use a newer fsid format */
        fsid_type = FSID_ENCODE_DEV;
    else
        fsid_type = FSID_DEV;
    fhp->fh_handle.fh_version = version;
    if (version)
        fhp->fh_handle.fh_fsid_type = fsid_type;
}

__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
     *
     */

    struct inode * inode = dentry->d_inode;
    struct dentry *parent = dentry->d_parent;
    __u32 *datap;
    dev_t ex_dev = exp_sb(exp)->s_dev;

    dprintk("nfsd: fh_compose(exp %02x:%02x/%ld %s/%s, ino=%ld)\n",
        MAJOR(ex_dev), MINOR(ex_dev),
        (long) exp->ex_path.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.
     */
     set_version_and_fsid_type(fhp, exp, ref_fh);

    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 (fhp->fh_handle.fh_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_path.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_auth_type = 0;
        datap = fhp->fh_handle.fh_auth+0;
        mk_fsid(fhp->fh_handle.fh_fsid_type, datap, ex_dev,
            exp->ex_path.dentry->d_inode->i_ino,
            exp->ex_fsid, exp->ex_uuid);

        len = key_len(fhp->fh_handle.fh_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) {
            fh_put(fhp);
            return nfserr_opnotsupp;
        }
    }

    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
    }
    fh_drop_write(fhp);
    if (exp) {
        exp_put(exp);
        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 (exp_sb(fhp->fh_export)->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;
}