/*      $NetBSD: umap_vfsops.c,v 1.105 2025/02/16 18:38:58 joe Exp $    */

/*
 * Copyright (c) 1992, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software donated to Berkeley by
 * the UCLA Ficus project.
 *
 * 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.
 *
 *      from: @(#)null_vfsops.c       1.5 (Berkeley) 7/10/92
 *      @(#)umap_vfsops.c       8.8 (Berkeley) 5/14/95
 */

/*
 * Umap Layer
 * (See mount_umap(8) for a description of this layer.)
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: umap_vfsops.c,v 1.105 2025/02/16 18:38:58 joe Exp $");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/sysctl.h>
#include <sys/proc.h>
#include <sys/time.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/namei.h>
#include <sys/syslog.h>
#include <sys/kauth.h>
#include <sys/module.h>

#include <miscfs/umapfs/umap.h>
#include <miscfs/genfs/layer_extern.h>

MODULE(MODULE_CLASS_VFS, umap, "layerfs");

VFS_PROTOS(umapfs);

/*
 * Mount umap layer
 */
int
umapfs_mount(struct mount *mp, const char *path, void *data, size_t *data_len)
{
        struct lwp *l = curlwp;
        struct pathbuf *pb;
        struct nameidata nd;
        struct umap_args *args = data;
        struct vnode *lowerrootvp, *vp;
        struct umap_mount *amp;
        int error;
#ifdef UMAPFS_DIAGNOSTIC
        int i;
#endif
        fsid_t tfsid;

        if (args == NULL)
                return EINVAL;
        if (*data_len < sizeof *args) {
#ifdef UMAPFS_DIAGNOSTIC
                printf("mount_umap: data len %d < args %d\n",
                        (int)*data_len, (int)(sizeof *args));
#endif
                return EINVAL;
        }

        if (mp->mnt_flag & MNT_GETARGS) {
                amp = MOUNTTOUMAPMOUNT(mp);
                if (amp == NULL)
                        return EIO;
                args->la.target = NULL;
                args->nentries = amp->info_nentries;
                args->gnentries = amp->info_gnentries;
                *data_len = sizeof *args;
                return 0;
        }

        /* only for root */
        error = kauth_authorize_system(l->l_cred, KAUTH_SYSTEM_MOUNT,
            KAUTH_REQ_SYSTEM_MOUNT_UMAP, NULL, NULL, NULL);
        if (error)
                return error;

#ifdef UMAPFS_DIAGNOSTIC
        printf("umapfs_mount(mp = %p)\n", mp);
#endif

        /*
         * Update is not supported
         */
        if (mp->mnt_flag & MNT_UPDATE)
                return EOPNOTSUPP;

        /*
         * Find lower node
         */
        error = pathbuf_copyin(args->umap_target, &pb);
        if (error) {
                return error;
        }
        NDINIT(&nd, LOOKUP, FOLLOW|LOCKLEAF, pb);
        if ((error = namei(&nd)) != 0) {
                pathbuf_destroy(pb);
                return error;
        }

        /*
         * Sanity check on lower vnode
         */
        lowerrootvp = nd.ni_vp;
        pathbuf_destroy(pb);
#ifdef UMAPFS_DIAGNOSTIC
        printf("vp = %p, check for VDIR...\n", lowerrootvp);
#endif

        if (lowerrootvp->v_type != VDIR) {
                vput(lowerrootvp);
                return (EINVAL);
        }

#ifdef UMAPFS_DIAGNOSTIC
        printf("mp = %p\n", mp);
#endif

        amp = kmem_zalloc(sizeof(struct umap_mount), KM_SLEEP);
        mp->mnt_data = amp;

        /*
         * Now copy in the number of entries and maps for umap mapping.
         */
        if (args->nentries < 0 || args->nentries > MAPFILEENTRIES ||
            args->gnentries < 0 || args->gnentries > GMAPFILEENTRIES) {
                vput(lowerrootvp);
                return (EINVAL);
        }

        amp->info_nentries = args->nentries;
        amp->info_gnentries = args->gnentries;
        error = copyin(args->mapdata, amp->info_mapdata,
            2*sizeof(u_long)*args->nentries);
        if (error) {
                vput(lowerrootvp);
                return (error);
        }

#ifdef UMAPFS_DIAGNOSTIC
        printf("umap_mount:nentries %d\n",args->nentries);
        for (i = 0; i < args->nentries; i++)
                printf("   %ld maps to %ld\n", amp->info_mapdata[i][0],
                    amp->info_mapdata[i][1]);
#endif

        error = copyin(args->gmapdata, amp->info_gmapdata,
            2*sizeof(u_long)*args->gnentries);
        if (error) {
                vput(lowerrootvp);
                return (error);
        }

#ifdef UMAPFS_DIAGNOSTIC
        printf("umap_mount:gnentries %d\n",args->gnentries);
        for (i = 0; i < args->gnentries; i++)
                printf("\tgroup %ld maps to %ld\n",
                    amp->info_gmapdata[i][0],
                    amp->info_gmapdata[i][1]);
#endif

        /*
         * Make sure the mount point's sufficiently initialized
         * that the node create call will work.
         */
        tfsid.__fsid_val[0] = (int32_t)args->fsid;
        tfsid.__fsid_val[1] = makefstype(MOUNT_UMAP);
        if (tfsid.__fsid_val[0] == 0) {
                log(LOG_WARNING, "umapfs: fsid given as 0, ignoring\n");
                vfs_getnewfsid(mp);
        } else if (vfs_getvfs(&tfsid)) {
                log(LOG_WARNING, "umapfs: fsid %x already mounted\n",
                        tfsid.__fsid_val[0]);
                vfs_getnewfsid(mp);
        } else {
                mp->mnt_stat.f_fsidx.__fsid_val[0] = tfsid.__fsid_val[0];
                mp->mnt_stat.f_fsidx.__fsid_val[1] = tfsid.__fsid_val[1];
                mp->mnt_stat.f_fsid = tfsid.__fsid_val[0];
        }
        log(LOG_DEBUG, "umapfs: using fsid %x/%x\n",
                mp->mnt_stat.f_fsidx.__fsid_val[0],
                mp->mnt_stat.f_fsidx.__fsid_val[1]);
        error = vfs_set_lowermount(mp, lowerrootvp->v_mount);
        if (error) {
                vput(lowerrootvp);
                kmem_free(amp, sizeof(struct umap_mount));
                return error;
        }

        amp->umapm_size = sizeof(struct umap_node);
        amp->umapm_tag = VT_UMAP;
        amp->umapm_bypass = umap_bypass;
        amp->umapm_vnodeop_p = umap_vnodeop_p;

        /*
         * fix up umap node for root vnode.
         */
        VOP_UNLOCK(lowerrootvp);
        error = layer_node_create(mp, lowerrootvp, &vp);
        /*
         * Make sure the node alias worked
         */
        if (error) {
                vrele(lowerrootvp);
                kmem_free(amp, sizeof(struct umap_mount));
                return error;
        }

        /*
         * Keep a held reference to the root vnode.
         * It is vrele'd in umapfs_unmount.
         */
        vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
        vp->v_vflag |= VV_ROOT;
        amp->umapm_rootvp = vp;
        VOP_UNLOCK(vp);

        error = set_statvfs_info(path, UIO_USERSPACE, args->umap_target,
            UIO_USERSPACE, mp->mnt_op->vfs_name, mp, l);
        if (error)
                return error;

        if (mp->mnt_lower->mnt_flag & MNT_LOCAL)
                mp->mnt_flag |= MNT_LOCAL;
#ifdef UMAPFS_DIAGNOSTIC
        printf("umapfs_mount: lower %s, alias at %s\n",
                mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname);
#endif
        return 0;
}

/*
 * Free reference to umap layer
 */
int
umapfs_unmount(struct mount *mp, int mntflags)
{
        struct umap_mount *amp = MOUNTTOUMAPMOUNT(mp);
        struct vnode *rtvp = amp->umapm_rootvp;
        int error;
        int flags = 0;

#ifdef UMAPFS_DIAGNOSTIC
        printf("umapfs_unmount(mp = %p)\n", mp);
#endif

        if (mntflags & MNT_FORCE)
                flags |= FORCECLOSE;

        if (vrefcnt(rtvp) > 1 && (mntflags & MNT_FORCE) == 0)
                return (EBUSY);
        if ((error = vflush(mp, rtvp, flags)) != 0)
                return (error);

#ifdef UMAPFS_DIAGNOSTIC
        vprint("alias root of lower", rtvp);
#endif
        /*
         * Blow it away for future re-use
         */
        vgone(rtvp);
        /*
         * Finally, throw away the umap_mount structure
         */
        kmem_free(amp, sizeof(struct umap_mount));
        mp->mnt_data = NULL;
        return 0;
}

extern const struct vnodeopv_desc umapfs_vnodeop_opv_desc;

const struct vnodeopv_desc * const umapfs_vnodeopv_descs[] = {
        &umapfs_vnodeop_opv_desc,
        NULL,
};

struct vfsops umapfs_vfsops = {
        .vfs_name = MOUNT_UMAP,
        .vfs_min_mount_data = sizeof (struct umap_args),
        .vfs_mount = umapfs_mount,
        .vfs_start = layerfs_start,
        .vfs_unmount = umapfs_unmount,
        .vfs_root = layerfs_root,
        .vfs_quotactl = layerfs_quotactl,
        .vfs_statvfs = layerfs_statvfs,
        .vfs_sync = layerfs_sync,
        .vfs_loadvnode = layerfs_loadvnode,
        .vfs_vget = layerfs_vget,
        .vfs_fhtovp = layerfs_fhtovp,
        .vfs_vptofh = layerfs_vptofh,
        .vfs_init = layerfs_init,
        .vfs_done = layerfs_done,
        .vfs_snapshot = layerfs_snapshot,
        .vfs_extattrctl = vfs_stdextattrctl,
        .vfs_suspendctl = layerfs_suspendctl,
        .vfs_renamelock_enter = layerfs_renamelock_enter,
        .vfs_renamelock_exit = layerfs_renamelock_exit,
        .vfs_fsync = (void *)eopnotsupp,
        .vfs_opv_descs = umapfs_vnodeopv_descs
};

SYSCTL_SETUP(umapfs_sysctl_setup, "umapfs sysctl")
{

        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT,
                       CTLTYPE_NODE, "umap",
                       SYSCTL_DESCR("UID/GID remapping file system"),
                       NULL, 0, NULL, 0,
                       CTL_VFS, 10, CTL_EOL);
        /*
         * XXX the "10" above could be dynamic, thereby eliminating
         * one more instance of the "number to vfs" mapping problem,
         * but "10" is the order as taken from sys/mount.h
         */
}

static int
umap_modcmd(modcmd_t cmd, void *arg)
{
        int error;

        switch (cmd) {
        case MODULE_CMD_INIT:
                error = vfs_attach(&umapfs_vfsops);
                break;
        case MODULE_CMD_FINI:
                error = vfs_detach(&umapfs_vfsops);
                break;
        default:
                error = ENOTTY;
                break;
        }

        return (error);
}