/*      $NetBSD: autofs_vnops.c,v 1.10 2024/12/15 21:40:05 andvar Exp $ */
/*-
 * Copyright (c) 2017 The NetBSD Foundation, Inc.
 * Copyright (c) 2016 The DragonFly Project
 * Copyright (c) 2014 The FreeBSD Foundation
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Tomohiro Kusumi <kusumi.tomohiro@gmail.com>.
 *
 * This software was developed by Edward Tomasz Napierala under sponsorship
 * from the FreeBSD Foundation.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
 *
 */
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: autofs_vnops.c,v 1.10 2024/12/15 21:40:05 andvar Exp $");

#include "autofs.h"

#include <sys/stat.h>
#include <sys/dirent.h>
#include <sys/namei.h>
#include <miscfs/genfs/genfs.h>

static int      autofs_trigger_vn(struct vnode *vp, const char *path,
                    int pathlen, struct vnode **newvp);

static int
autofs_access(void *v)
{
        struct vop_access_args /* {
                struct vnode    *a_vp;
                int             a_mode;
                kauth_cred_t    a_cred;
        } */ *ap = v;
        struct vnode *vp __diagused = ap->a_vp;

        KASSERT(VOP_ISLOCKED(vp));
        /*
         * Nothing to do here; the only kind of access control
         * needed is in autofs_mkdir().
         */
        return 0;
}

static int
autofs_getattr(void *v)
{
        struct vop_getattr_args /* {
                struct vnode    *a_vp;
                struct vattr    *a_vap;
                kauth_cred_t    a_cred;
        } */ *ap = v;
        struct vnode *vp = ap->a_vp;
        struct vattr *vap = ap->a_vap;
        struct autofs_node *anp = VTOI(vp);

        KASSERT(vp->v_type == VDIR);

        /*
         * The reason we must do this is that some tree-walking software,
         * namely fts(3), assumes that stat(".") results will not change
         * between chdir("subdir") and chdir(".."), and fails with ENOENT
         * otherwise.
         */
        if (autofs_mount_on_stat &&
            autofs_cached(anp, NULL, 0) == false &&
            autofs_ignore_thread() == false) {
                struct vnode *newvp = NULLVP;
                int error = autofs_trigger_vn(vp, "", 0, &newvp);
                if (error)
                        return error;
                /*
                 * Already mounted here.
                 */
                if (newvp) {
                        error = VOP_GETATTR(newvp, vap, ap->a_cred);
                        vput(newvp);
                        return error;
                }
        }

        vattr_null(vap);

        vap->va_type = VDIR;
        vap->va_mode = 0755;
        vap->va_nlink = 3;
        vap->va_uid = 0;
        vap->va_gid = 0;
        vap->va_fsid = vp->v_mount->mnt_stat.f_fsidx.__fsid_val[0];
        vap->va_fileid = anp->an_ino;
        vap->va_size = S_BLKSIZE;
        vap->va_blocksize = S_BLKSIZE;
        vap->va_mtime = anp->an_ctime;
        vap->va_atime = anp->an_ctime;
        vap->va_ctime = anp->an_ctime;
        vap->va_birthtime = anp->an_ctime;
        vap->va_gen = 0;
        vap->va_flags = 0;
        vap->va_rdev = 0;
        vap->va_bytes = S_BLKSIZE;
        vap->va_filerev = 0;
        vap->va_vaflags = 0;
        vap->va_spare = 0;

        return 0;
}

/*
 * Unlock the vnode, request automountd(8) action, and then lock it back.
 * If anything got mounted on top of the vnode, return the new filesystem's
 * root vnode in 'newvp', locked.  A caller needs to vput() the 'newvp'.
 */
static int
autofs_trigger_vn(struct vnode *vp, const char *path, int pathlen,
    struct vnode **newvp)
{
        struct autofs_node *anp;
        int error, lock_flags;

        anp = vp->v_data;

        /*
         * Release the vnode lock, so that other operations, in particular
         * mounting a filesystem on top of it, can proceed.  Increase use
         * count, to prevent the vnode from being deallocated and to prevent
         * filesystem from being unmounted.
         */
        lock_flags = VOP_ISLOCKED(vp);
        vref(vp);
        VOP_UNLOCK(vp);

        mutex_enter(&autofs_softc->sc_lock);

        /*
         * Workaround for mounting the same thing multiple times; revisit.
         */
        if (vp->v_mountedhere) {
                error = 0;
                goto mounted;
        }

        error = autofs_trigger(anp, path, pathlen);
mounted:
        mutex_exit(&autofs_softc->sc_lock);
        vn_lock(vp, lock_flags | LK_RETRY);
        vrele(vp);

        if (error)
                return error;

        if (!vp->v_mountedhere) {
                *newvp = NULLVP;
                return 0;
        } else {
                /*
                 * If the operation that succeeded was mount, then mark
                 * the node as non-cached.  Otherwise, if someone unmounts
                 * the filesystem before the cache times out, we will fail
                 * to trigger.
                 */
                autofs_node_uncache(anp);
        }

        error = VFS_ROOT(vp->v_mountedhere, LK_EXCLUSIVE, newvp);
        if (error) {
                AUTOFS_WARN("VFS_ROOT() failed with error %d", error);
                return error;
        }

        return 0;
}

static int
autofs_lookup(void *v)
{
        struct vop_lookup_v2_args /* {
                struct vnode *a_dvp;
                struct vnode **a_vpp;
                struct componentname *a_cnp;
        } */ *ap = v;
        struct vnode *dvp = ap->a_dvp;
        struct vnode **vpp = ap->a_vpp;
        struct componentname *cnp = ap->a_cnp;
        struct autofs_mount *amp = VFSTOAUTOFS(dvp->v_mount);
        struct autofs_node *anp, *child;
        int cachefound;
        int error;
        const bool lastcn __diagused = (cnp->cn_flags & ISLASTCN) != 0;

        KASSERT(VOP_ISLOCKED(dvp));

        anp = VTOI(dvp);
        *vpp = NULLVP;

        /* Check accessibility of directory. */
        KASSERT(!VOP_ACCESS(dvp, VEXEC, cnp->cn_cred));

        /*
         * Avoid doing a linear scan of the directory if the requested
         * directory/name couple is already in the cache.
         */
        cachefound = cache_lookup(dvp, cnp->cn_nameptr, cnp->cn_namelen,
            cnp->cn_nameiop, cnp->cn_flags, NULL, vpp);
        if (cachefound && *vpp == NULLVP) {
                /* Negative cache hit. */
                error = ENOENT;
                goto out;
        } else if (cachefound) {
                error = 0;
                goto out;
        }

        if (cnp->cn_flags & ISDOTDOT) {
                struct autofs_node *parent;
                /*
                 * Lookup of ".." case.
                 */
                KASSERT(!(lastcn && cnp->cn_nameiop == RENAME));
                parent = anp->an_parent;
                if (!parent) {
                        error = ENOENT;
                        goto out;
                }

                error = vcache_get(dvp->v_mount, &parent, sizeof(parent), vpp);
                goto out;
        } else if (cnp->cn_namelen == 1 && cnp->cn_nameptr[0] == '.') {
                /*
                 * Lookup of "." case.
                 */
                KASSERT(!(lastcn && cnp->cn_nameiop == RENAME));
                vref(dvp);
                *vpp = dvp;
                error = 0;
                goto done;
        }

        if (autofs_cached(anp, cnp->cn_nameptr, cnp->cn_namelen) == false &&
            autofs_ignore_thread() == false) {
                struct vnode *newvp = NULLVP;
                error = autofs_trigger_vn(dvp, cnp->cn_nameptr, cnp->cn_namelen,
                    &newvp);
                if (error)
                        return error;
                /*
                 * Already mounted here.
                 */
                if (newvp) {
                        error = VOP_LOOKUP(newvp, vpp, cnp);
                        vput(newvp);
                        return error;
                }
        }

        mutex_enter(&amp->am_lock);
        error = autofs_node_find(anp, cnp->cn_nameptr, cnp->cn_namelen, &child);
        if (error) {
                if ((cnp->cn_flags & ISLASTCN) && cnp->cn_nameiop == CREATE) {
                        mutex_exit(&amp->am_lock);
                        error = EJUSTRETURN;
                        goto done;
                }

                mutex_exit(&amp->am_lock);
                error = ENOENT;
                goto done;
        }

        /*
         * Dropping the node here is ok, because we never remove nodes.
         */
        mutex_exit(&amp->am_lock);

        /* Get a vnode for the matching entry. */
        error = vcache_get(dvp->v_mount, &child, sizeof(child), vpp);
done:
        /*
         * Cache the result, unless request was for creation (as it does
         * not improve the performance).
         */
        if (cnp->cn_nameiop != CREATE) {
                cache_enter(dvp, *vpp, cnp->cn_nameptr, cnp->cn_namelen,
                            cnp->cn_flags);
        }
out:
        KASSERT(VOP_ISLOCKED(dvp));

        return error;
}

static int
autofs_open(void *v)
{
        struct vop_open_args /* {
                struct vnode    *a_vp;
                int             a_mode;
                kauth_cred_t    a_cred;
        } */ *ap = v;
        struct vnode *vp __diagused = ap->a_vp;

        KASSERT(VOP_ISLOCKED(vp));
        return 0;
}

static int
autofs_close(void *v)
{
        struct vop_close_args /* {
                struct vnode    *a_vp;
                int             a_fflag;
                kauth_cred_t    a_cred;
        } */ *ap = v;
        struct vnode *vp __diagused = ap->a_vp;

        KASSERT(VOP_ISLOCKED(vp));
        return 0;
}

static int
autofs_fsync(void *v)
{
        struct vop_fsync_args /* {
                struct vnode *a_vp;
                kauth_cred_t a_cred;
                int a_flags;
                off_t a_offlo;
                off_t a_offhi;
                struct lwp *a_l;
        } */ *ap = v;
        struct vnode *vp __diagused = ap->a_vp;

        /* Nothing to do.  Should be up to date. */
        KASSERT(VOP_ISLOCKED(vp));
        return 0;
}

static int
autofs_mkdir(void *v)
{
        struct vop_mkdir_v3_args /* {
                struct vnode            *a_dvp;
                struct vnode            **a_vpp;
                struct componentname    *a_cnp;
                struct vattr            *a_vap;
        } */ *ap = v;
        struct vnode *dvp = ap->a_dvp;
        struct vnode **vpp = ap->a_vpp;
        struct componentname *cnp = ap->a_cnp;
        struct autofs_mount *amp = VFSTOAUTOFS(dvp->v_mount);
        struct autofs_node *anp = VTOI(dvp);
        struct autofs_node *child = NULL;
        int error;

        KASSERT(ap->a_vap->va_type == VDIR);

        /*
         * Do not allow mkdir() if the calling thread is not
         * automountd(8) descendant.
         */
        if (autofs_ignore_thread() == false)
                return EPERM;

        mutex_enter(&amp->am_lock);
        error = autofs_node_new(anp, amp, cnp->cn_nameptr, cnp->cn_namelen,
            &child);
        if (error) {
                mutex_exit(&amp->am_lock);
                return error;
        }
        mutex_exit(&amp->am_lock);

        return vcache_get(amp->am_mp, &child, sizeof(child), vpp);
}

static int
autofs_print(void *v)
{
        struct vop_print_args /* {
                struct vnode    *a_vp;
        } */ *ap = v;
        struct vnode *vp = ap->a_vp;
        struct autofs_node *anp = VTOI(vp);

        printf("tag VT_AUTOFS, node %p, ino %jd, name %s, cached %d, "
            "retries %d, wildcards %d",
            anp, (intmax_t)anp->an_ino, anp->an_name, anp->an_cached,
            anp->an_retries, anp->an_wildcards);
        printf("\n");

        return 0;
}

static int
autofs_readdir_one(struct uio *uio, const char *name, ino_t ino)
{
        struct dirent dirent;

        dirent.d_fileno = ino;
        dirent.d_type = DT_DIR;
        strlcpy(dirent.d_name, name, sizeof(dirent.d_name));
        dirent.d_namlen = strlen(dirent.d_name);
        dirent.d_reclen = _DIRENT_SIZE(&dirent);

        if (!uio)
                return 0;

        if (uio->uio_resid < dirent.d_reclen)
                return EINVAL;

        return uiomove(&dirent, dirent.d_reclen, uio);
}

static size_t
autofs_dirent_reclen(const char *name)
{
        struct dirent dirent;

        strlcpy(dirent.d_name, name, sizeof(dirent.d_name));
        dirent.d_namlen = strlen(dirent.d_name);

        return _DIRENT_SIZE(&dirent);
}

static int
autofs_readdir(void *v)
{
        struct vop_readdir_args /* {
                struct vnode    *a_vp;
                struct uio      *a_uio;
                kauth_cred_t    a_cred;
                int             *a_eofflag;
                off_t           **a_cookies;
                int             *ncookies;
        } */ *ap = v;
        struct vnode *vp = ap->a_vp;
        struct uio *uio = ap->a_uio;
        size_t initial_resid = ap->a_uio->uio_resid;
        struct autofs_mount *amp = VFSTOAUTOFS(vp->v_mount);
        struct autofs_node *anp = VTOI(vp);
        struct autofs_node *child;
        size_t reclens;
        int error;

        if (vp->v_type != VDIR)
                return ENOTDIR;

        if (autofs_cached(anp, NULL, 0) == false &&
            autofs_ignore_thread() == false) {
                struct vnode *newvp = NULLVP;
                error = autofs_trigger_vn(vp, "", 0, &newvp);
                if (error)
                        return error;
                /*
                 * Already mounted here.
                 */
                if (newvp) {
                        error = VOP_READDIR(newvp, ap->a_uio, ap->a_cred,
                            ap->a_eofflag, ap->a_cookies, ap->a_ncookies);
                        vput(newvp);
                        return error;
                }
        }

        if (uio->uio_offset < 0)
                return EINVAL;

        if (ap->a_eofflag)
                *ap->a_eofflag = FALSE;

        /*
         * Write out the directory entry for ".".
         */
        if (uio->uio_offset == 0) {
                error = autofs_readdir_one(uio, ".", anp->an_ino);
                if (error)
                        goto out;
        }
        reclens = autofs_dirent_reclen(".");

        /*
         * Write out the directory entry for "..".
         */
        if (uio->uio_offset <= reclens) {
                if (uio->uio_offset != reclens)
                        return EINVAL;
                error = autofs_readdir_one(uio, "..",
                    anp->an_parent ? anp->an_parent->an_ino : anp->an_ino);
                if (error)
                        goto out;
        }
        reclens += autofs_dirent_reclen("..");

        /*
         * Write out the directory entries for subdirectories.
         */
        mutex_enter(&amp->am_lock);
        RB_FOREACH(child, autofs_node_tree, &anp->an_children) {
                /*
                 * Check the offset to skip entries returned by previous
                 * calls to getdents().
                 */
                if (uio->uio_offset > reclens) {
                        reclens += autofs_dirent_reclen(child->an_name);
                        continue;
                }

                /*
                 * Prevent seeking into the middle of dirent.
                 */
                if (uio->uio_offset != reclens) {
                        mutex_exit(&amp->am_lock);
                        return EINVAL;
                }

                error = autofs_readdir_one(uio, child->an_name, child->an_ino);
                reclens += autofs_dirent_reclen(child->an_name);
                if (error) {
                        mutex_exit(&amp->am_lock);
                        goto out;
                }
        }
        mutex_exit(&amp->am_lock);

        if (ap->a_eofflag)
                *ap->a_eofflag = TRUE;

        return 0;
out:
        /*
         * Return error if the initial buffer was too small to do anything.
         */
        if (uio->uio_resid == initial_resid)
                return error;

        /*
         * Don't return an error if we managed to copy out some entries.
         */
        if (uio->uio_resid < initial_resid)
                return 0;

        return error;
}

static int
autofs_reclaim(void *v)
{
        struct vop_reclaim_v2_args /* {
                struct vnode *a_vp;
        } */ *ap = v;
        struct vnode *vp = ap->a_vp;
        struct autofs_node *anp = VTOI(vp);

        VOP_UNLOCK(vp);

        /*
         * We do not free autofs_node here; instead we are
         * destroying them in autofs_node_delete().
         */
        anp->an_vnode = NULLVP;
        vp->v_data = NULL;

        return 0;
}

int (**autofs_vnodeop_p)(void *);
static const struct vnodeopv_entry_desc autofs_vnodeop_entries[] = {
        { &vop_default_desc,    vn_default_error },
        { &vop_parsepath_desc,  genfs_parsepath },
        { &vop_lookup_desc,     autofs_lookup },
        { &vop_open_desc,       autofs_open },
        { &vop_close_desc,      autofs_close },
        { &vop_access_desc,     autofs_access },
        { &vop_accessx_desc,    genfs_accessx },
        { &vop_getattr_desc,    autofs_getattr },
        { &vop_fsync_desc,      autofs_fsync },
        { &vop_seek_desc,       genfs_seek },
        { &vop_mkdir_desc,      autofs_mkdir },
        { &vop_readdir_desc,    autofs_readdir },
        { &vop_reclaim_desc,    autofs_reclaim },
        { &vop_lock_desc,       genfs_lock },
        { &vop_unlock_desc,     genfs_unlock },
        { &vop_print_desc,      autofs_print },
        { &vop_islocked_desc,   genfs_islocked },
        { &vop_getpages_desc,   genfs_getpages },
        { &vop_putpages_desc,   genfs_putpages },
        { &vop_pathconf_desc,   genfs_pathconf },
        { NULL, NULL }
};

const struct vnodeopv_desc autofs_vnodeop_opv_desc = {
        &autofs_vnodeop_p, autofs_vnodeop_entries
};

int
autofs_node_new(struct autofs_node *parent, struct autofs_mount *amp,
    const char *name, int namelen, struct autofs_node **anpp)
{
        struct autofs_node *anp;

        KASSERT(mutex_owned(&amp->am_lock));

        if (parent) {
                KASSERT(mutex_owned(&parent->an_mount->am_lock));
                KASSERT(autofs_node_find(parent, name, namelen, NULL) ==
                    ENOENT);
        }

        anp = pool_get(&autofs_node_pool, PR_WAITOK);
        anp->an_name = autofs_strndup(name, namelen, KM_SLEEP);
        anp->an_ino = amp->am_last_ino++;
        callout_init(&anp->an_callout, 0);
        getnanotime(&anp->an_ctime);
        anp->an_parent = parent;
        anp->an_mount = amp;
        anp->an_vnode = NULLVP;
        anp->an_cached = false;
        anp->an_wildcards = false;
        anp->an_retries = 0;
        if (parent)
                RB_INSERT(autofs_node_tree, &parent->an_children, anp);
        RB_INIT(&anp->an_children);

        *anpp = anp;
        return 0;
}

int
autofs_node_find(struct autofs_node *parent, const char *name,
    int namelen, struct autofs_node **anpp)
{
        struct autofs_node *anp, find;
        int error;

        KASSERT(mutex_owned(&parent->an_mount->am_lock));

        find.an_name = autofs_strndup(name, namelen, KM_SLEEP);
        anp = RB_FIND(autofs_node_tree, &parent->an_children, &find);
        if (anp) {
                error = 0;
                if (anpp)
                        *anpp = anp;
        } else {
                error = ENOENT;
        }

        kmem_strfree(find.an_name);

        return error;
}

void
autofs_node_delete(struct autofs_node *anp)
{

        KASSERT(mutex_owned(&anp->an_mount->am_lock));
        KASSERT(RB_EMPTY(&anp->an_children));

        callout_halt(&anp->an_callout, NULL);

        if (anp->an_parent)
                RB_REMOVE(autofs_node_tree, &anp->an_parent->an_children, anp);

        kmem_strfree(anp->an_name);
        pool_put(&autofs_node_pool, anp);
}