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+/*
+ * Copyright (c) 1994 The Regents of the University of California.
+ * Copyright (c) 1994 Jan-Simon Pendry.
+ * All rights reserved.
+ *
+ * This code is derived from software donated to Berkeley by
+ * Jan-Simon Pendry.
+ *
+ * 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. All advertising materials mentioning features or use of this software
+ * must display the following acknowledgement:
+ * This product includes software developed by the University of
+ * California, Berkeley and its contributors.
+ * 4. 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.
+ *
+ * @(#)union_vfsops.c 8.7 (Berkeley) 3/5/94
+ */
+
+/*
+ * Union Layer
+ */
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <sys/proc.h>
+#include <sys/vnode.h>
+#include <sys/mount.h>
+#include <sys/namei.h>
+#include <sys/malloc.h>
+#include <sys/filedesc.h>
+#include <sys/queue.h>
+#include <miscfs/union/union.h>
+
+/*
+ * Mount union filesystem
+ */
+int
+union_mount(mp, path, data, ndp, p)
+ struct mount *mp;
+ char *path;
+ caddr_t data;
+ struct nameidata *ndp;
+ struct proc *p;
+{
+ int error = 0;
+ struct union_args args;
+ struct vnode *lowerrootvp = NULLVP;
+ struct vnode *upperrootvp = NULLVP;
+ struct union_mount *um;
+ struct ucred *cred = 0;
+ struct ucred *scred;
+ struct vattr va;
+ char *cp;
+ int len;
+ u_int size;
+
+#ifdef UNION_DIAGNOSTIC
+ printf("union_mount(mp = %x)\n", mp);
+#endif
+
+ /*
+ * Update is a no-op
+ */
+ if (mp->mnt_flag & MNT_UPDATE) {
+ /*
+ * Need to provide.
+ * 1. a way to convert between rdonly and rdwr mounts.
+ * 2. support for nfs exports.
+ */
+ error = EOPNOTSUPP;
+ goto bad;
+ }
+
+ /*
+ * Take a copy of the process's credentials. This isn't
+ * quite right since the euid will always be zero and we
+ * want to get the "real" users credentials. So fix up
+ * the uid field after taking the copy.
+ */
+ cred = crdup(p->p_ucred);
+ cred->cr_uid = p->p_cred->p_ruid;
+
+ /*
+ * Ensure the *real* user has write permission on the
+ * mounted-on directory. This allows the mount_union
+ * command to be made setuid root so allowing anyone
+ * to do union mounts onto any directory on which they
+ * have write permission and which they also own.
+ */
+ error = VOP_GETATTR(mp->mnt_vnodecovered, &va, cred, p);
+ if (error)
+ goto bad;
+ if ((va.va_uid != cred->cr_uid) &&
+ (cred->cr_uid != 0)) {
+ error = EACCES;
+ goto bad;
+ }
+ error = VOP_ACCESS(mp->mnt_vnodecovered, VWRITE, cred, p);
+ if (error)
+ goto bad;
+
+ /*
+ * Get argument
+ */
+ if (error = copyin(data, (caddr_t)&args, sizeof(struct union_args)))
+ goto bad;
+
+ lowerrootvp = mp->mnt_vnodecovered;
+ VREF(lowerrootvp);
+
+ /*
+ * Find upper node. Use the real process credentials,
+ * not the effective ones since this will have come
+ * through a setuid process (mount_union). All this
+ * messing around with permissions is entirely bogus
+ * and should be removed by allowing any user straight
+ * past the mount system call.
+ */
+ scred = p->p_ucred;
+ p->p_ucred = cred;
+ NDINIT(ndp, LOOKUP, FOLLOW|WANTPARENT,
+ UIO_USERSPACE, args.target, p);
+ p->p_ucred = scred;
+
+ if (error = namei(ndp))
+ goto bad;
+
+ upperrootvp = ndp->ni_vp;
+ vrele(ndp->ni_dvp);
+ ndp->ni_dvp = NULL;
+
+ if (upperrootvp->v_type != VDIR) {
+ error = EINVAL;
+ goto bad;
+ }
+
+ um = (struct union_mount *) malloc(sizeof(struct union_mount),
+ M_UFSMNT, M_WAITOK); /* XXX */
+
+ /*
+ * Keep a held reference to the target vnodes.
+ * They are vrele'd in union_unmount.
+ *
+ * Depending on the _BELOW flag, the filesystems are
+ * viewed in a different order. In effect, this is the
+ * same as providing a mount under option to the mount syscall.
+ */
+
+ um->um_op = args.mntflags & UNMNT_OPMASK;
+ switch (um->um_op) {
+ case UNMNT_ABOVE:
+ um->um_lowervp = lowerrootvp;
+ um->um_uppervp = upperrootvp;
+ break;
+
+ case UNMNT_BELOW:
+ um->um_lowervp = upperrootvp;
+ um->um_uppervp = lowerrootvp;
+ break;
+
+ case UNMNT_REPLACE:
+ vrele(lowerrootvp);
+ lowerrootvp = NULLVP;
+ um->um_uppervp = upperrootvp;
+ um->um_lowervp = lowerrootvp;
+ break;
+
+ default:
+ error = EINVAL;
+ goto bad;
+ }
+
+ um->um_cred = cred;
+ um->um_cmode = UN_DIRMODE &~ p->p_fd->fd_cmask;
+
+ /*
+ * Depending on what you think the MNT_LOCAL flag might mean,
+ * you may want the && to be || on the conditional below.
+ * At the moment it has been defined that the filesystem is
+ * only local if it is all local, ie the MNT_LOCAL flag implies
+ * that the entire namespace is local. If you think the MNT_LOCAL
+ * flag implies that some of the files might be stored locally
+ * then you will want to change the conditional.
+ */
+ if (um->um_op == UNMNT_ABOVE) {
+ if (((um->um_lowervp == NULLVP) ||
+ (um->um_lowervp->v_mount->mnt_flag & MNT_LOCAL)) &&
+ (um->um_uppervp->v_mount->mnt_flag & MNT_LOCAL))
+ mp->mnt_flag |= MNT_LOCAL;
+ }
+
+ /*
+ * Copy in the upper layer's RDONLY flag. This is for the benefit
+ * of lookup() which explicitly checks the flag, rather than asking
+ * the filesystem for it's own opinion. This means, that an update
+ * mount of the underlying filesystem to go from rdonly to rdwr
+ * will leave the unioned view as read-only.
+ */
+ mp->mnt_flag |= (um->um_uppervp->v_mount->mnt_flag & MNT_RDONLY);
+
+ /*
+ * This is a user mount. Privilege check for unmount
+ * will be done in union_unmount.
+ */
+ mp->mnt_flag |= MNT_USER;
+
+ mp->mnt_data = (qaddr_t) um;
+ getnewfsid(mp, MOUNT_UNION);
+
+ (void) copyinstr(path, mp->mnt_stat.f_mntonname, MNAMELEN - 1, &size);
+ bzero(mp->mnt_stat.f_mntonname + size, MNAMELEN - size);
+
+ switch (um->um_op) {
+ case UNMNT_ABOVE:
+ cp = "<above>";
+ break;
+ case UNMNT_BELOW:
+ cp = "<below>";
+ break;
+ case UNMNT_REPLACE:
+ cp = "";
+ break;
+ }
+ len = strlen(cp);
+ bcopy(cp, mp->mnt_stat.f_mntfromname, len);
+
+ cp = mp->mnt_stat.f_mntfromname + len;
+ len = MNAMELEN - len;
+
+ (void) copyinstr(args.target, cp, len - 1, &size);
+ bzero(cp + size, len - size);
+
+#ifdef UNION_DIAGNOSTIC
+ printf("union_mount: from %s, on %s\n",
+ mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname);
+#endif
+ return (0);
+
+bad:
+ if (cred)
+ crfree(cred);
+ if (upperrootvp)
+ vrele(upperrootvp);
+ if (lowerrootvp)
+ vrele(lowerrootvp);
+ return (error);
+}
+
+/*
+ * VFS start. Nothing needed here - the start routine
+ * on the underlying filesystem(s) will have been called
+ * when that filesystem was mounted.
+ */
+int
+union_start(mp, flags, p)
+ struct mount *mp;
+ int flags;
+ struct proc *p;
+{
+
+ return (0);
+}
+
+/*
+ * Free reference to union layer
+ */
+int
+union_unmount(mp, mntflags, p)
+ struct mount *mp;
+ int mntflags;
+ struct proc *p;
+{
+ struct union_mount *um = MOUNTTOUNIONMOUNT(mp);
+ struct vnode *um_rootvp;
+ int error;
+ int flags = 0;
+ extern int doforce;
+
+#ifdef UNION_DIAGNOSTIC
+ printf("union_unmount(mp = %x)\n", mp);
+#endif
+
+ /* only the mounter, or superuser can unmount */
+ if ((p->p_cred->p_ruid != um->um_cred->cr_uid) &&
+ (error = suser(p->p_ucred, &p->p_acflag)))
+ return (error);
+
+ if (mntflags & MNT_FORCE) {
+ /* union can never be rootfs so don't check for it */
+ if (!doforce)
+ return (EINVAL);
+ flags |= FORCECLOSE;
+ }
+
+ if (error = union_root(mp, &um_rootvp))
+ return (error);
+ if (um_rootvp->v_usecount > 1) {
+ vput(um_rootvp);
+ return (EBUSY);
+ }
+ if (error = vflush(mp, um_rootvp, flags)) {
+ vput(um_rootvp);
+ return (error);
+ }
+
+#ifdef UNION_DIAGNOSTIC
+ vprint("alias root of lower", um_rootvp);
+#endif
+ /*
+ * Discard references to upper and lower target vnodes.
+ */
+ if (um->um_lowervp)
+ vrele(um->um_lowervp);
+ vrele(um->um_uppervp);
+ crfree(um->um_cred);
+ /*
+ * Release reference on underlying root vnode
+ */
+ vput(um_rootvp);
+ /*
+ * And blow it away for future re-use
+ */
+ vgone(um_rootvp);
+ /*
+ * Finally, throw away the union_mount structure
+ */
+ free(mp->mnt_data, M_UFSMNT); /* XXX */
+ mp->mnt_data = 0;
+ return (0);
+}
+
+int
+union_root(mp, vpp)
+ struct mount *mp;
+ struct vnode **vpp;
+{
+ struct union_mount *um = MOUNTTOUNIONMOUNT(mp);
+ int error;
+ int loselock;
+
+#ifdef UNION_DIAGNOSTIC
+ printf("union_root(mp = %x, lvp = %x, uvp = %x)\n", mp,
+ um->um_lowervp,
+ um->um_uppervp);
+#endif
+
+ /*
+ * Return locked reference to root.
+ */
+ VREF(um->um_uppervp);
+ if ((um->um_op == UNMNT_BELOW) &&
+ VOP_ISLOCKED(um->um_uppervp)) {
+ loselock = 1;
+ } else {
+ VOP_LOCK(um->um_uppervp);
+ loselock = 0;
+ }
+ if (um->um_lowervp)
+ VREF(um->um_lowervp);
+ error = union_allocvp(vpp, mp,
+ (struct vnode *) 0,
+ (struct vnode *) 0,
+ (struct componentname *) 0,
+ um->um_uppervp,
+ um->um_lowervp);
+
+ if (error) {
+ if (!loselock)
+ VOP_UNLOCK(um->um_uppervp);
+ vrele(um->um_uppervp);
+ if (um->um_lowervp)
+ vrele(um->um_lowervp);
+ } else {
+ (*vpp)->v_flag |= VROOT;
+ if (loselock)
+ VTOUNION(*vpp)->un_flags &= ~UN_ULOCK;
+ }
+
+ return (error);
+}
+
+int
+union_quotactl(mp, cmd, uid, arg, p)
+ struct mount *mp;
+ int cmd;
+ uid_t uid;
+ caddr_t arg;
+ struct proc *p;
+{
+
+ return (EOPNOTSUPP);
+}
+
+int
+union_statfs(mp, sbp, p)
+ struct mount *mp;
+ struct statfs *sbp;
+ struct proc *p;
+{
+ int error;
+ struct union_mount *um = MOUNTTOUNIONMOUNT(mp);
+ struct statfs mstat;
+ int lbsize;
+
+#ifdef UNION_DIAGNOSTIC
+ printf("union_statfs(mp = %x, lvp = %x, uvp = %x)\n", mp,
+ um->um_lowervp,
+ um->um_uppervp);
+#endif
+
+ bzero(&mstat, sizeof(mstat));
+
+ if (um->um_lowervp) {
+ error = VFS_STATFS(um->um_lowervp->v_mount, &mstat, p);
+ if (error)
+ return (error);
+ }
+
+ /* now copy across the "interesting" information and fake the rest */
+#if 0
+ sbp->f_type = mstat.f_type;
+ sbp->f_flags = mstat.f_flags;
+ sbp->f_bsize = mstat.f_bsize;
+ sbp->f_iosize = mstat.f_iosize;
+#endif
+ lbsize = mstat.f_bsize;
+ sbp->f_blocks = mstat.f_blocks;
+ sbp->f_bfree = mstat.f_bfree;
+ sbp->f_bavail = mstat.f_bavail;
+ sbp->f_files = mstat.f_files;
+ sbp->f_ffree = mstat.f_ffree;
+
+ error = VFS_STATFS(um->um_uppervp->v_mount, &mstat, p);
+ if (error)
+ return (error);
+
+ sbp->f_type = MOUNT_UNION;
+ sbp->f_flags = mstat.f_flags;
+ sbp->f_bsize = mstat.f_bsize;
+ sbp->f_iosize = mstat.f_iosize;
+
+ /*
+ * if the lower and upper blocksizes differ, then frig the
+ * block counts so that the sizes reported by df make some
+ * kind of sense. none of this makes sense though.
+ */
+
+ if (mstat.f_bsize != lbsize) {
+ sbp->f_blocks = sbp->f_blocks * lbsize / mstat.f_bsize;
+ sbp->f_bfree = sbp->f_bfree * lbsize / mstat.f_bsize;
+ sbp->f_bavail = sbp->f_bavail * lbsize / mstat.f_bsize;
+ }
+ sbp->f_blocks += mstat.f_blocks;
+ sbp->f_bfree += mstat.f_bfree;
+ sbp->f_bavail += mstat.f_bavail;
+ sbp->f_files += mstat.f_files;
+ sbp->f_ffree += mstat.f_ffree;
+
+ if (sbp != &mp->mnt_stat) {
+ bcopy(&mp->mnt_stat.f_fsid, &sbp->f_fsid, sizeof(sbp->f_fsid));
+ bcopy(mp->mnt_stat.f_mntonname, sbp->f_mntonname, MNAMELEN);
+ bcopy(mp->mnt_stat.f_mntfromname, sbp->f_mntfromname, MNAMELEN);
+ }
+ return (0);
+}
+
+int
+union_sync(mp, waitfor, cred, p)
+ struct mount *mp;
+ int waitfor;
+ struct ucred *cred;
+ struct proc *p;
+{
+
+ /*
+ * XXX - Assumes no data cached at union layer.
+ */
+ return (0);
+}
+
+int
+union_vget(mp, ino, vpp)
+ struct mount *mp;
+ ino_t ino;
+ struct vnode **vpp;
+{
+
+ return (EOPNOTSUPP);
+}
+
+int
+union_fhtovp(mp, fidp, nam, vpp, exflagsp, credanonp)
+ struct mount *mp;
+ struct fid *fidp;
+ struct mbuf *nam;
+ struct vnode **vpp;
+ int *exflagsp;
+ struct ucred **credanonp;
+{
+
+ return (EOPNOTSUPP);
+}
+
+int
+union_vptofh(vp, fhp)
+ struct vnode *vp;
+ struct fid *fhp;
+{
+
+ return (EOPNOTSUPP);
+}
+
+int union_init __P((void));
+
+struct vfsops union_vfsops = {
+ union_mount,
+ union_start,
+ union_unmount,
+ union_root,
+ union_quotactl,
+ union_statfs,
+ union_sync,
+ union_vget,
+ union_fhtovp,
+ union_vptofh,
+ union_init,
+};
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