/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*      Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
/*        All Rights Reserved   */


/*
 * Copyright (c) 1989, 2010, Oracle and/or its affiliates. All rights reserved.
 * Copyright (c) 2016, 2017 by Delphix. All rights reserved.
 */

/*
 * This file defines the vnode operations for mounted file descriptors.
 * The routines in this file act as a layer between the NAMEFS file
 * system and SPECFS/FIFOFS.  With the exception of nm_open(), nm_setattr(),
 * nm_getattr() and nm_access(), the routines simply apply the VOP operation
 * to the vnode representing the file descriptor.  This switches control
 * to the underlying file system to which the file descriptor belongs.
 */
#include <sys/types.h>
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/cred.h>
#include <sys/errno.h>
#include <sys/time.h>
#include <sys/file.h>
#include <sys/fcntl.h>
#include <sys/flock.h>
#include <sys/kmem.h>
#include <sys/uio.h>
#include <sys/vfs.h>
#include <sys/vfs_opreg.h>
#include <sys/vnode.h>
#include <sys/pcb.h>
#include <sys/signal.h>
#include <sys/user.h>
#include <sys/proc.h>
#include <sys/conf.h>
#include <sys/debug.h>
#include <vm/seg.h>
#include <sys/fs/namenode.h>
#include <sys/stream.h>
#include <fs/fs_subr.h>
#include <sys/policy.h>

/*
 * Create a reference to the vnode representing the file descriptor.
 * Then, apply the VOP_OPEN operation to that vnode.
 *
 * The vnode for the file descriptor may be switched under you.
 * If it is, search the hash list for an nodep - nodep->nm_filevp
 * pair. If it exists, return that nodep to the user.
 * If it does not exist, create a new namenode to attach
 * to the nodep->nm_filevp then place the pair on the hash list.
 *
 * Newly created objects are like children/nodes in the mounted
 * file system, with the parent being the initial mount.
 */
int
nm_open(vnode_t **vpp, int flag, cred_t *crp, caller_context_t *ct)
{
        struct namenode *nodep = VTONM(*vpp);
        int error = 0;
        struct namenode *newnamep;
        struct vnode *newvp;
        struct vnode *infilevp;
        struct vnode *outfilevp;

        /*
         * If the vnode is switched under us, the corresponding
         * VN_RELE for this VN_HOLD will be done by the file system
         * performing the switch. Otherwise, the corresponding
         * VN_RELE will be done by nm_close().
         */
        infilevp = outfilevp = nodep->nm_filevp;
        VN_HOLD(outfilevp);

        if ((error = VOP_OPEN(&outfilevp, flag, crp, ct)) != 0) {
                VN_RELE(outfilevp);
                return (error);
        }
        if (infilevp != outfilevp) {
                /*
                 * See if the new filevp (outfilevp) is already associated
                 * with the mount point. If it is, then it already has a
                 * namenode associated with it.
                 */
                mutex_enter(&ntable_lock);
                if ((newnamep =
                    namefind(outfilevp, nodep->nm_mountpt)) != NULL) {
                        struct vnode *vp = NMTOV(newnamep);

                        VN_HOLD(vp);
                        goto gotit;
                }

                newnamep = kmem_zalloc(sizeof (struct namenode), KM_SLEEP);
                newvp = vn_alloc(KM_SLEEP);
                newnamep->nm_vnode = newvp;

                mutex_init(&newnamep->nm_lock, NULL, MUTEX_DEFAULT, NULL);

                mutex_enter(&nodep->nm_lock);
                newvp->v_flag = ((*vpp)->v_flag | VNOMAP | VNOSWAP) & ~VROOT;
                vn_setops(newvp, vn_getops(*vpp));
                newvp->v_vfsp = &namevfs;
                newvp->v_stream = outfilevp->v_stream;
                newvp->v_type = outfilevp->v_type;
                newvp->v_rdev = outfilevp->v_rdev;
                newvp->v_data = (caddr_t)newnamep;
                vn_exists(newvp);
                bcopy(&nodep->nm_vattr, &newnamep->nm_vattr, sizeof (vattr_t));
                newnamep->nm_vattr.va_type = outfilevp->v_type;
                newnamep->nm_vattr.va_nodeid = namenodeno_alloc();
                newnamep->nm_vattr.va_size = (u_offset_t)0;
                newnamep->nm_vattr.va_rdev = outfilevp->v_rdev;
                newnamep->nm_flag = NMNMNT;
                newnamep->nm_filevp = outfilevp;
                newnamep->nm_filep = nodep->nm_filep;
                newnamep->nm_mountpt = nodep->nm_mountpt;
                mutex_exit(&nodep->nm_lock);

                /*
                 * Insert the new namenode into the hash list.
                 */
                nameinsert(newnamep);
gotit:
                mutex_exit(&ntable_lock);
                /*
                 * Release the above reference to the infilevp, the reference
                 * to the NAMEFS vnode, create a reference to the new vnode
                 * and return the new vnode to the user.
                 */
                VN_RELE(*vpp);
                *vpp = NMTOV(newnamep);
        }
        return (0);
}

/*
 * Close a mounted file descriptor.
 * Remove any locks and apply the VOP_CLOSE operation to the vnode for
 * the file descriptor.
 */
static int
nm_close(vnode_t *vp, int flag, int count, offset_t offset, cred_t *crp,
    caller_context_t *ct)
{
        struct namenode *nodep = VTONM(vp);
        int error = 0;

        (void) cleanlocks(vp, ttoproc(curthread)->p_pid, 0);
        cleanshares(vp, ttoproc(curthread)->p_pid);
        error = VOP_CLOSE(nodep->nm_filevp, flag, count, offset, crp, ct);
        if (count == 1) {
                (void) VOP_FSYNC(nodep->nm_filevp, FSYNC, crp, ct);
                /*
                 * Before VN_RELE() we need to remove the vnode from
                 * the hash table.  We should only do so in the  NMNMNT case.
                 * In other cases, nodep->nm_filep keeps a reference
                 * to nm_filevp and the entry in the hash table doesn't
                 * hurt.
                 */
                if ((nodep->nm_flag & NMNMNT) != 0) {
                        mutex_enter(&ntable_lock);
                        nameremove(nodep);
                        mutex_exit(&ntable_lock);
                }
                VN_RELE(nodep->nm_filevp);
        }
        return (error);
}

static int
nm_read(vnode_t *vp, struct uio *uiop, int ioflag, cred_t *crp,
    caller_context_t *ct)
{
        return (VOP_READ(VTONM(vp)->nm_filevp, uiop, ioflag, crp, ct));
}

static int
nm_write(vnode_t *vp, struct uio *uiop, int ioflag, cred_t *crp,
    caller_context_t *ct)
{
        return (VOP_WRITE(VTONM(vp)->nm_filevp, uiop, ioflag, crp, ct));
}

static int
nm_ioctl(vnode_t *vp, int cmd, intptr_t arg, int mode, cred_t *cr, int *rvalp,
    caller_context_t *ct)
{
        return (VOP_IOCTL(VTONM(vp)->nm_filevp, cmd, arg, mode, cr, rvalp, ct));
}

/*
 * Return in vap the attributes that are stored in the namenode
 * structure.  Only the size is taken from the mounted object.
 */
/* ARGSUSED */
static int
nm_getattr(vnode_t *vp, vattr_t *vap, int flags, cred_t *crp,
    caller_context_t *ct)
{
        struct namenode *nodep = VTONM(vp);
        struct vattr va;
        int error;

        mutex_enter(&nodep->nm_lock);
        bcopy(&nodep->nm_vattr, vap, sizeof (vattr_t));
        mutex_exit(&nodep->nm_lock);

        if ((va.va_mask = vap->va_mask & AT_SIZE) != 0) {
                if (error = VOP_GETATTR(nodep->nm_filevp, &va, flags, crp, ct))
                        return (error);
                vap->va_size = va.va_size;
        }

        return (0);
}

/*
 * Standard access() like check.  Figure out which mode bits apply
 * to the caller then pass the missing mode bits to the secpolicy function.
 */
static int
nm_access_unlocked(void *vnp, int mode, cred_t *crp)
{
        struct namenode *nodep = vnp;
        int shift = 0;

        if (crgetuid(crp) != nodep->nm_vattr.va_uid) {
                shift += 3;
                if (!groupmember(nodep->nm_vattr.va_gid, crp))
                        shift += 3;
        }

        return (secpolicy_vnode_access2(crp, NMTOV(nodep),
            nodep->nm_vattr.va_uid, nodep->nm_vattr.va_mode << shift,
            mode));
}
/*
 * Set the attributes of the namenode from the attributes in vap.
 */
/* ARGSUSED */
static int
nm_setattr(vnode_t *vp, vattr_t *vap, int flags, cred_t *crp,
    caller_context_t *ctp)
{
        struct namenode *nodep = VTONM(vp);
        struct vattr *nmvap = &nodep->nm_vattr;
        long mask = vap->va_mask;
        int error = 0;

        /*
         * Cannot set these attributes.
         */
        if (mask & (AT_NOSET|AT_SIZE))
                return (EINVAL);

        (void) VOP_RWLOCK(nodep->nm_filevp, V_WRITELOCK_TRUE, ctp);
        mutex_enter(&nodep->nm_lock);

        /*
         * Change ownership/group/time/access mode of mounted file
         * descriptor.
         */

        error = secpolicy_vnode_setattr(crp, vp, vap, nmvap, flags,
            nm_access_unlocked, nodep);
        if (error)
                goto out;

        mask = vap->va_mask;
        /*
         * If request to change mode, copy new
         * mode into existing attribute structure.
         */
        if (mask & AT_MODE)
                nmvap->va_mode = vap->va_mode & ~VSVTX;

        /*
         * If request was to change user or group, turn off suid and sgid
         * bits.
         * If the system was configured with the "rstchown" option, the
         * owner is not permitted to give away the file, and can change
         * the group id only to a group of which they are a member.
         */
        if (mask & AT_UID)
                nmvap->va_uid = vap->va_uid;
        if (mask & AT_GID)
                nmvap->va_gid = vap->va_gid;
        /*
         * If request is to modify times, make sure user has write
         * permissions on the file.
         */
        if (mask & AT_ATIME)
                nmvap->va_atime = vap->va_atime;
        if (mask & AT_MTIME) {
                nmvap->va_mtime = vap->va_mtime;
                gethrestime(&nmvap->va_ctime);
        }
out:
        mutex_exit(&nodep->nm_lock);
        VOP_RWUNLOCK(nodep->nm_filevp, V_WRITELOCK_TRUE, ctp);
        return (error);
}

/*
 * Check mode permission on the namenode.  First nm_access_unlocked()
 * checks the bits on the name node, then an access check is performed
 * on the underlying file.
 */
/* ARGSUSED */
static int
nm_access(vnode_t *vp, int mode, int flags, cred_t *crp, caller_context_t *ct)
{
        struct namenode *nodep = VTONM(vp);
        int error;

        mutex_enter(&nodep->nm_lock);
        error = nm_access_unlocked(nodep, mode, crp);
        mutex_exit(&nodep->nm_lock);
        if (error == 0)
                return (VOP_ACCESS(nodep->nm_filevp, mode, flags, crp, ct));
        else
                return (error);
}

/*
 * We can get here if a creat or open with O_CREAT is done on a namefs
 * mount point, for example, as the object of a shell output redirection to
 * the mount point.
 */
/*ARGSUSED*/
static int
nm_create(vnode_t *dvp, char *name, vattr_t *vap, enum vcexcl excl, int mode,
    vnode_t **vpp, cred_t *cr, int flag, caller_context_t *ct,
    vsecattr_t *vsecp)
{
        int error;

        ASSERT(dvp && *name == '\0');
        if (excl == NONEXCL) {
                if (mode && (error = nm_access(dvp, mode, 0, cr, ct)) != 0)
                        return (error);
                VN_HOLD(dvp);
                return (0);
        }
        return (EEXIST);
}

/*
 * Links are not allowed on mounted file descriptors.
 */
/*ARGSUSED*/
static int
nm_link(vnode_t *tdvp, vnode_t *vp, char *tnm, cred_t *crp,
    caller_context_t *ct, int flags)
{
        return (EXDEV);
}

static int
nm_fsync(vnode_t *vp, int syncflag, cred_t *crp, caller_context_t *ct)
{
        return (VOP_FSYNC(VTONM(vp)->nm_filevp, syncflag, crp, ct));
}

/* Free the namenode */
/* ARGSUSED */
static void
nm_inactive(vnode_t *vp, cred_t *crp, caller_context_t *ct)
{
        struct namenode *nodep = VTONM(vp);
        vfs_t *vfsp = vp->v_vfsp;

        mutex_enter(&vp->v_lock);
        ASSERT(vp->v_count >= 1);
        VN_RELE_LOCKED(vp);
        if (vp->v_count != 0) {
                mutex_exit(&vp->v_lock);
                return;
        }
        mutex_exit(&vp->v_lock);
        if (!(nodep->nm_flag & NMNMNT)) {
                ASSERT(nodep->nm_filep->f_vnode == nodep->nm_filevp);
                (void) closef(nodep->nm_filep);
        }
        vn_invalid(vp);
        vn_free(vp);
        if (vfsp != &namevfs)
                VFS_RELE(vfsp);
        namenodeno_free(nodep->nm_vattr.va_nodeid);
        kmem_free(nodep, sizeof (struct namenode));
}

static int
nm_fid(vnode_t *vp, struct fid *fidnodep, caller_context_t *ct)
{
        return (VOP_FID(VTONM(vp)->nm_filevp, fidnodep, ct));
}

static int
nm_rwlock(vnode_t *vp, int write, caller_context_t *ctp)
{
        return (VOP_RWLOCK(VTONM(vp)->nm_filevp, write, ctp));
}

static void
nm_rwunlock(vnode_t *vp, int write, caller_context_t *ctp)
{
        VOP_RWUNLOCK(VTONM(vp)->nm_filevp, write, ctp);
}

static int
nm_seek(vnode_t *vp, offset_t ooff, offset_t *noffp, caller_context_t *ct)
{
        return (VOP_SEEK(VTONM(vp)->nm_filevp, ooff, noffp, ct));
}

/*
 * Return the vnode representing the file descriptor in vpp.
 */
static int
nm_realvp(vnode_t *vp, vnode_t **vpp, caller_context_t *ct)
{
        struct vnode *rvp;

        vp = VTONM(vp)->nm_filevp;
        if (VOP_REALVP(vp, &rvp, ct) == 0)
                vp = rvp;
        *vpp = vp;
        return (0);
}

static int
nm_poll(vnode_t *vp, short events, int anyyet, short *reventsp,
    pollhead_t **phpp, caller_context_t *ct)
{
        return (VOP_POLL(VTONM(vp)->nm_filevp, events, anyyet, reventsp,
            phpp, ct));
}

struct vnodeops *nm_vnodeops;

const fs_operation_def_t nm_vnodeops_template[] = {
        VOPNAME_OPEN,           { .vop_open = nm_open },
        VOPNAME_CLOSE,          { .vop_close = nm_close },
        VOPNAME_READ,           { .vop_read = nm_read },
        VOPNAME_WRITE,          { .vop_write = nm_write },
        VOPNAME_IOCTL,          { .vop_ioctl = nm_ioctl },
        VOPNAME_GETATTR,        { .vop_getattr = nm_getattr },
        VOPNAME_SETATTR,        { .vop_setattr = nm_setattr },
        VOPNAME_ACCESS,         { .vop_access = nm_access },
        VOPNAME_CREATE,         { .vop_create = nm_create },
        VOPNAME_LINK,           { .vop_link = nm_link },
        VOPNAME_FSYNC,          { .vop_fsync = nm_fsync },
        VOPNAME_INACTIVE,       { .vop_inactive = nm_inactive },
        VOPNAME_FID,            { .vop_fid = nm_fid },
        VOPNAME_RWLOCK,         { .vop_rwlock = nm_rwlock },
        VOPNAME_RWUNLOCK,       { .vop_rwunlock = nm_rwunlock },
        VOPNAME_SEEK,           { .vop_seek = nm_seek },
        VOPNAME_REALVP,         { .vop_realvp = nm_realvp },
        VOPNAME_POLL,           { .vop_poll = nm_poll },
        VOPNAME_DISPOSE,        { .error = fs_error },
        NULL,                   NULL
};