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freebsd-dev/sys/kern/vfs_vnops.c
Poul-Henning Kamp 75c1354190 This Implements the mumbled about "Jail" feature. 
This is a seriously beefed up chroot kind of thing.  The process
is jailed along the same lines as a chroot does it, but with
additional tough restrictions imposed on what the superuser can do.

For all I know, it is safe to hand over the root bit inside a
prison to the customer living in that prison, this is what
it was developed for in fact:  "real virtual servers".

Each prison has an ip number associated with it, which all IP
communications will be coerced to use and each prison has its own
hostname.

Needless to say, you need more RAM this way, but the advantage is
that each customer can run their own particular version of apache
and not stomp on the toes of their neighbors.

It generally does what one would expect, but setting up a jail
still takes a little knowledge.

A few notes:

   I have no scripts for setting up a jail, don't ask me for them.

   The IP number should be an alias on one of the interfaces.

   mount a /proc in each jail, it will make ps more useable.

   /proc/<pid>/status tells the hostname of the prison for
   jailed processes.

   Quotas are only sensible if you have a mountpoint per prison.

   There are no privisions for stopping resource-hogging.

   Some "#ifdef INET" and similar may be missing (send patches!)

If somebody wants to take it from here and develop it into
more of a "virtual machine" they should be most welcome!

Tools, comments, patches & documentation most welcome.

Have fun...

Sponsored by:   http://www.rndassociates.com/
Run for almost a year by:       http://www.servetheweb.com/
1999-04-28 11:38:52 +00:00

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/*
* Copyright (c) 1982, 1986, 1989, 1993
* The Regents of the University of California. All rights reserved.
* (c) UNIX System Laboratories, Inc.
* All or some portions of this file are derived from material licensed
* to the University of California by American Telephone and Telegraph
* Co. or Unix System Laboratories, Inc. and are reproduced herein with
* the permission of UNIX System Laboratories, Inc.
*
* 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.
*
* @(#)vfs_vnops.c 8.2 (Berkeley) 1/21/94
* $Id: vfs_vnops.c,v 1.67 1999/04/27 11:16:27 phk Exp $
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/fcntl.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <sys/proc.h>
#include <sys/mount.h>
#include <sys/namei.h>
#include <sys/vnode.h>
#include <sys/filio.h>
#include <sys/ttycom.h>
static int vn_closefile __P((struct file *fp, struct proc *p));
static int vn_ioctl __P((struct file *fp, u_long com, caddr_t data,
struct proc *p));
static int vn_read __P((struct file *fp, struct uio *uio,
struct ucred *cred, int flags));
static int vn_poll __P((struct file *fp, int events, struct ucred *cred,
struct proc *p));
static int vn_write __P((struct file *fp, struct uio *uio,
struct ucred *cred, int flags));
struct fileops vnops =
{ vn_read, vn_write, vn_ioctl, vn_poll, vn_closefile };
/*
* Common code for vnode open operations.
* Check permissions, and call the VOP_OPEN or VOP_CREATE routine.
*/
int
vn_open(ndp, fmode, cmode)
register struct nameidata *ndp;
int fmode, cmode;
{
register struct vnode *vp;
register struct proc *p = ndp->ni_cnd.cn_proc;
register struct ucred *cred = p->p_ucred;
struct vattr vat;
struct vattr *vap = &vat;
int mode, error;
if (fmode & O_CREAT) {
ndp->ni_cnd.cn_nameiop = CREATE;
ndp->ni_cnd.cn_flags = LOCKPARENT | LOCKLEAF;
if ((fmode & O_EXCL) == 0 && (fmode & O_NOFOLLOW) == 0)
ndp->ni_cnd.cn_flags |= FOLLOW;
error = namei(ndp);
if (error)
return (error);
if (ndp->ni_vp == NULL) {
VATTR_NULL(vap);
vap->va_type = VREG;
vap->va_mode = cmode;
if (fmode & O_EXCL)
vap->va_vaflags |= VA_EXCLUSIVE;
VOP_LEASE(ndp->ni_dvp, p, cred, LEASE_WRITE);
error = VOP_CREATE(ndp->ni_dvp, &ndp->ni_vp,
&ndp->ni_cnd, vap);
vput(ndp->ni_dvp);
if (error)
return (error);
ASSERT_VOP_UNLOCKED(ndp->ni_dvp, "create");
ASSERT_VOP_LOCKED(ndp->ni_vp, "create");
fmode &= ~O_TRUNC;
vp = ndp->ni_vp;
} else {
VOP_ABORTOP(ndp->ni_dvp, &ndp->ni_cnd);
if (ndp->ni_dvp == ndp->ni_vp)
vrele(ndp->ni_dvp);
else
vput(ndp->ni_dvp);
ndp->ni_dvp = NULL;
vp = ndp->ni_vp;
if (fmode & O_EXCL) {
error = EEXIST;
goto bad;
}
fmode &= ~O_CREAT;
}
} else {
ndp->ni_cnd.cn_nameiop = LOOKUP;
ndp->ni_cnd.cn_flags =
((fmode & O_NOFOLLOW) ? NOFOLLOW : FOLLOW) | LOCKLEAF;
error = namei(ndp);
if (error)
return (error);
vp = ndp->ni_vp;
}
if (vp->v_type == VLNK) {
error = EMLINK;
goto bad;
}
if (vp->v_type == VSOCK) {
error = EOPNOTSUPP;
goto bad;
}
if ((fmode & O_CREAT) == 0) {
mode = 0;
if (fmode & (FWRITE | O_TRUNC)) {
if (vp->v_type == VDIR) {
error = EISDIR;
goto bad;
}
error = vn_writechk(vp);
if (error)
goto bad;
mode |= VWRITE;
}
if (fmode & FREAD)
mode |= VREAD;
if (mode) {
error = VOP_ACCESS(vp, mode, cred, p);
if (error)
goto bad;
}
}
if (fmode & O_TRUNC) {
VOP_UNLOCK(vp, 0, p); /* XXX */
VOP_LEASE(vp, p, cred, LEASE_WRITE);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, p); /* XXX */
VATTR_NULL(vap);
vap->va_size = 0;
error = VOP_SETATTR(vp, vap, cred, p);
if (error)
goto bad;
}
error = VOP_OPEN(vp, fmode, cred, p);
if (error)
goto bad;
/*
* Make sure that a VM object is created for VMIO support.
*/
if (vp->v_type == VREG) {
if ((error = vfs_object_create(vp, p, cred)) != 0)
goto bad;
}
if (fmode & FWRITE)
vp->v_writecount++;
return (0);
bad:
vput(vp);
return (error);
}
/*
* Check for write permissions on the specified vnode.
* Prototype text segments cannot be written.
*/
int
vn_writechk(vp)
register struct vnode *vp;
{
/*
* If there's shared text associated with
* the vnode, try to free it up once. If
* we fail, we can't allow writing.
*/
if (vp->v_flag & VTEXT)
return (ETXTBSY);
return (0);
}
/*
* Vnode close call
*/
int
vn_close(vp, flags, cred, p)
register struct vnode *vp;
int flags;
struct ucred *cred;
struct proc *p;
{
int error;
if (flags & FWRITE)
vp->v_writecount--;
error = VOP_CLOSE(vp, flags, cred, p);
vrele(vp);
return (error);
}
/*
* Package up an I/O request on a vnode into a uio and do it.
*/
int
vn_rdwr(rw, vp, base, len, offset, segflg, ioflg, cred, aresid, p)
enum uio_rw rw;
struct vnode *vp;
caddr_t base;
int len;
off_t offset;
enum uio_seg segflg;
int ioflg;
struct ucred *cred;
int *aresid;
struct proc *p;
{
struct uio auio;
struct iovec aiov;
int error;
if ((ioflg & IO_NODELOCKED) == 0)
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, p);
auio.uio_iov = &aiov;
auio.uio_iovcnt = 1;
aiov.iov_base = base;
aiov.iov_len = len;
auio.uio_resid = len;
auio.uio_offset = offset;
auio.uio_segflg = segflg;
auio.uio_rw = rw;
auio.uio_procp = p;
if (rw == UIO_READ) {
error = VOP_READ(vp, &auio, ioflg, cred);
} else {
error = VOP_WRITE(vp, &auio, ioflg, cred);
}
if (aresid)
*aresid = auio.uio_resid;
else
if (auio.uio_resid && error == 0)
error = EIO;
if ((ioflg & IO_NODELOCKED) == 0)
VOP_UNLOCK(vp, 0, p);
return (error);
}
/*
* File table vnode read routine.
*/
static int
vn_read(fp, uio, cred, flags)
struct file *fp;
struct uio *uio;
struct ucred *cred;
int flags;
{
struct vnode *vp = (struct vnode *)fp->f_data;
struct proc *p = uio->uio_procp;
int error, ioflag;
ioflag = 0;
if (fp->f_flag & FNONBLOCK)
ioflag |= IO_NDELAY;
VOP_LEASE(vp, p, cred, LEASE_READ);
vn_lock(vp, LK_SHARED | LK_NOPAUSE | LK_RETRY, p);
if ((flags & FOF_OFFSET) == 0)
uio->uio_offset = fp->f_offset;
/*
* Sequential read heuristic.
* If we have been doing sequential input,
* a rewind operation doesn't turn off
* sequential input mode.
*/
if ((uio->uio_offset == 0 && fp->f_seqcount > 0) ||
uio->uio_offset == fp->f_nextread) {
int tmpseq = fp->f_seqcount;
/*
* XXX we assume that the filesystem block size is
* the default. Not true, but still gives us a pretty
* good indicator of how sequential the read operations
* are.
*/
tmpseq += (uio->uio_resid + BKVASIZE - 1) / BKVASIZE;
if (tmpseq >= 127)
tmpseq = 127;
fp->f_seqcount = tmpseq;
ioflag |= fp->f_seqcount << 16;
} else {
if (fp->f_seqcount > 1)
fp->f_seqcount = 1;
else
fp->f_seqcount = 0;
}
error = VOP_READ(vp, uio, ioflag, cred);
if ((flags & FOF_OFFSET) == 0)
fp->f_offset = uio->uio_offset;
fp->f_nextread = uio->uio_offset;
VOP_UNLOCK(vp, 0, p);
return (error);
}
/*
* File table vnode write routine.
*/
static int
vn_write(fp, uio, cred, flags)
struct file *fp;
struct uio *uio;
struct ucred *cred;
int flags;
{
struct vnode *vp = (struct vnode *)fp->f_data;
struct proc *p = uio->uio_procp;
int error, ioflag;
ioflag = IO_UNIT;
if (vp->v_type == VREG && (fp->f_flag & O_APPEND))
ioflag |= IO_APPEND;
if (fp->f_flag & FNONBLOCK)
ioflag |= IO_NDELAY;
if ((fp->f_flag & O_FSYNC) ||
(vp->v_mount && (vp->v_mount->mnt_flag & MNT_SYNCHRONOUS)))
ioflag |= IO_SYNC;
VOP_LEASE(vp, p, cred, LEASE_WRITE);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, p);
if ((flags & FOF_OFFSET) == 0)
uio->uio_offset = fp->f_offset;
error = VOP_WRITE(vp, uio, ioflag, cred);
if ((flags & FOF_OFFSET) == 0)
fp->f_offset = uio->uio_offset;
VOP_UNLOCK(vp, 0, p);
return (error);
}
/*
* File table vnode stat routine.
*/
int
vn_stat(vp, sb, p)
struct vnode *vp;
register struct stat *sb;
struct proc *p;
{
struct vattr vattr;
register struct vattr *vap;
int error;
u_short mode;
vap = &vattr;
error = VOP_GETATTR(vp, vap, p->p_ucred, p);
if (error)
return (error);
/*
* Copy from vattr table
*/
sb->st_dev = vap->va_fsid;
sb->st_ino = vap->va_fileid;
mode = vap->va_mode;
switch (vap->va_type) {
case VREG:
mode |= S_IFREG;
break;
case VDIR:
mode |= S_IFDIR;
break;
case VBLK:
mode |= S_IFBLK;
break;
case VCHR:
mode |= S_IFCHR;
break;
case VLNK:
mode |= S_IFLNK;
/* This is a cosmetic change, symlinks do not have a mode. */
if (vp->v_mount->mnt_flag & MNT_NOSYMFOLLOW)
sb->st_mode &= ~ACCESSPERMS; /* 0000 */
else
sb->st_mode |= ACCESSPERMS; /* 0777 */
break;
case VSOCK:
mode |= S_IFSOCK;
break;
case VFIFO:
mode |= S_IFIFO;
break;
default:
return (EBADF);
};
sb->st_mode = mode;
sb->st_nlink = vap->va_nlink;
sb->st_uid = vap->va_uid;
sb->st_gid = vap->va_gid;
sb->st_rdev = vap->va_rdev;
sb->st_size = vap->va_size;
sb->st_atimespec = vap->va_atime;
sb->st_mtimespec = vap->va_mtime;
sb->st_ctimespec = vap->va_ctime;
sb->st_blksize = vap->va_blocksize;
sb->st_flags = vap->va_flags;
if (suser_xxx(p->p_ucred, 0, 0))
sb->st_gen = 0;
else
sb->st_gen = vap->va_gen;
#if (S_BLKSIZE == 512)
/* Optimize this case */
sb->st_blocks = vap->va_bytes >> 9;
#else
sb->st_blocks = vap->va_bytes / S_BLKSIZE;
#endif
return (0);
}
/*
* File table vnode ioctl routine.
*/
static int
vn_ioctl(fp, com, data, p)
struct file *fp;
u_long com;
caddr_t data;
struct proc *p;
{
register struct vnode *vp = ((struct vnode *)fp->f_data);
struct vattr vattr;
int error;
switch (vp->v_type) {
case VREG:
case VDIR:
if (com == FIONREAD) {
error = VOP_GETATTR(vp, &vattr, p->p_ucred, p);
if (error)
return (error);
*(int *)data = vattr.va_size - fp->f_offset;
return (0);
}
if (com == FIONBIO || com == FIOASYNC) /* XXX */
return (0); /* XXX */
/* fall into ... */
default:
#if 0
return (ENOTTY);
#endif
case VFIFO:
case VCHR:
case VBLK:
error = VOP_IOCTL(vp, com, data, fp->f_flag, p->p_ucred, p);
if (error == 0 && com == TIOCSCTTY) {
/* Do nothing if reassigning same control tty */
if (p->p_session->s_ttyvp == vp)
return (0);
/* Get rid of reference to old control tty */
if (p->p_session->s_ttyvp)
vrele(p->p_session->s_ttyvp);
p->p_session->s_ttyvp = vp;
VREF(vp);
}
return (error);
}
}
/*
* File table vnode poll routine.
*/
static int
vn_poll(fp, events, cred, p)
struct file *fp;
int events;
struct ucred *cred;
struct proc *p;
{
return (VOP_POLL(((struct vnode *)fp->f_data), events, cred, p));
}
/*
* Check that the vnode is still valid, and if so
* acquire requested lock.
*/
int
#ifndef DEBUG_LOCKS
vn_lock(vp, flags, p)
#else
debug_vn_lock(vp, flags, p, filename, line)
#endif
struct vnode *vp;
int flags;
struct proc *p;
#ifdef DEBUG_LOCKS
const char *filename;
int line;
#endif
{
int error;
do {
if ((flags & LK_INTERLOCK) == 0)
simple_lock(&vp->v_interlock);
if (vp->v_flag & VXLOCK) {
vp->v_flag |= VXWANT;
simple_unlock(&vp->v_interlock);
tsleep((caddr_t)vp, PINOD, "vn_lock", 0);
error = ENOENT;
} else {
#ifdef DEBUG_LOCKS
vp->filename = filename;
vp->line = line;
#endif
error = VOP_LOCK(vp,
flags | LK_NOPAUSE | LK_INTERLOCK, p);
if (error == 0)
return (error);
}
flags &= ~LK_INTERLOCK;
} while (flags & LK_RETRY);
return (error);
}
/*
* File table vnode close routine.
*/
static int
vn_closefile(fp, p)
struct file *fp;
struct proc *p;
{
return (vn_close(((struct vnode *)fp->f_data), fp->f_flag,
fp->f_cred, p));
}
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