freebsd-dev/sys/fs/unionfs/union_vfsops.c

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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
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* $Id: union_vfsops.c,v 1.9 1995/03/16 20:23:44 wollman Exp $
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*/
/*
* Union Layer
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
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#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>
int union_root __P((struct mount *, struct vnode **));
int union_statfs __P((struct mount *, struct statfs *, struct proc *));
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/*
* 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 = 0;
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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;
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if ((va.va_uid != cred->cr_uid) &&
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(cred->cr_uid != 0)) {
error = EACCES;
goto bad;
}
error = VOP_ACCESS(mp->mnt_vnodecovered, VWRITE, cred, p);
if (error)
goto bad;
/*
* Get argument
*/
error = copyin(data, (caddr_t)&args, sizeof(struct union_args));
if (error)
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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;
error = namei(ndp);
if (error)
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goto bad;
upperrootvp = ndp->ni_vp;
vrele(ndp->ni_dvp);
ndp->ni_dvp = NULL;
if (upperrootvp->v_type != VDIR) {
error = EINVAL;
goto bad;
}
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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);
(void)union_statfs(mp, &mp->mnt_stat, p);
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#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;
#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;
}
error = union_root(mp, &um_rootvp);
if (error)
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return (error);
if (um_rootvp->v_usecount > 1) {
vput(um_rootvp);
return (EBUSY);
}
error = vflush(mp, um_rootvp, flags);
if (error) {
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vput(um_rootvp);
return (error);
}
#ifdef UNION_DIAGNOSTIC
vprint("alias root of lower", um_rootvp);
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#endif
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/*
* 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;
{
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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,
};
VFS_SET(union_vfsops, union, MOUNT_UNION, VFCF_LOOPBACK);