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/
1:
s/suser/suser_xxx/
2:
Add new function: suser(struct proc *), prototyped in <sys/proc.h>.
3:
s/suser_xxx(\([a-zA-Z0-9_]*\)->p_ucred, \&\1->p_acflag)/suser(\1)/
The remaining suser_xxx() calls will be scrutinized and dealt with
later.
There may be some unneeded #include <sys/cred.h>, but they are left
as an exercise for Bruce.
More changes to the suser() API will come along with the "jail" code.
lives in ext2_vnops.c for ext2fs. Also remove cast from comparision.
Bruce pointed out that it was bogus since we'd force a signed
comparision when we really wanted an unsigned comparison.
MNT_WAIT when we mean boolean `true' or check for that value not being
passed. There was no problem in practice because MNT_WAIT had the
magic value of 1.
They checked for the magic major number for the "device" behind mfs
mount points. Use a more obvious check for this device.
Debugged by: Andrew Gallatin <gallatin@cs.duke.edu>
but when i_effnlink was added to support soft updates, there was only
room for 4 spares. The number of spares was not reduced, so the inode
size became 260 (on i386's), or 512 after rounding up by malloc().
Use one spare field in `struct dinode' instead of the 5th spare field
in the inode and reduced to 4 spares in the inode so that the size is
256 again.
Changed the types of the spares in the inode from int to u_int32_t
so that the inode size has more chance of being <= 256 under other
arches, and downdated ext2fs to match (it was broken to use ints
before rev.1.1).
an ext2fs file system is mounted. The soft update changes added
a check for B_DELWRI buffers. This exposed the complete brokenness
of the previous quick fix for failing syncs (PR 3571, committed on
1997/08/04). Use a new buffer flag B_DIRTY and don't abuse B_DELWRI.
B_DIRTY buffers are still written too late, as broken in the previous
fix. This is fairly harmless, because B_DIRTY is only used for
bitmap buffers and fsck.ext2 can fix up the bitmaps perfectly.
Fixed a race in ULCK_BUF() (bremfree() was outside of the splbio()
section).
syncs weren't optimized properly (they probably still aren't, but are bug
for bug compatible with ffs). These fixes are mostly academic, since
ext2fs is too broken to mount read-write (it apparently doesn't clear
indirect blocks).
Obtained from: mostly from Lite2
Fixes for bugs not shared with ffs:
- don't mount unclean filesystems rw unless forced to.
- accept EXT2_ERROR_FS (treat it like !EXT2_VALID_FS). We still don't set
this or honour the maximal mount count.
- don't attempt to print the name of the mount point when mounting an
unclean file system, since the name of the previous mount point is
unknown and the name of the current mount point is still "".
Fixes for bugs shared with ffs until recently:
- don't set the clean flag on unmount of an initially-unclean filesystem
that was (forcibly) mounted rw.
- set the clean flag on rw -> ro update of a mounted initially-clean
filesystem.
- fixed some style bugs (mostly long lines).
The fixes are slightly simpler than for ffs, because the relevant on-disk
state is not a simple boolean variable, and the superblock has a core-only
extension.
Obtained from: parts from ffs_vfsops.c, parts from NetBSD
surprisingly few problems. Most fields were initialized to the
correct values by bzero(), but lk_prio was 0 instead of PINOD (=8),
the lk_wmsg was NULL instead of "ext2in", and lk_lockholder was 0
instead of -1.
Obtained from: Lite2 via the -current ffs_vfsops.c
references to them.
The change a couple of days ago to ignore these numbers in statically
configured vfsconf structs was slightly premature because the cd9660,
cfs, devfs, ext2fs, nfs vfs's still used MOUNT_* instead of the number
in their vfsconf struct.
clustering is obsolescent technology so hardly anyone noticed. On
a DORS 32160 SCSI drive with 4 tags, read clustering makes very
little difference even for huge sequential reads. However, on a
ZIP SCSI drive with 0 tags, the minimum overhead per block is about
40 msec, so very large clusters must be used to get anywhere near
the maximum transfer rate. Using clusters consisting of 1 8K block
reduces the transfer rate to about 250K/sec. Under msdosfs, missing
read clustering is normal and a cluster size of 1 512 byte block
reduces the transfer rate to about 25K/sec.
Broken in: rev.1.18
as the value in b_vp is often not really what you want.
(and needs to be frobbed). more cleanups will follow this.
Reviewed by: Bruce Evans <bde@freebsd.org>
as possible (when the inode is reclaimed). Temporarily only do
this if option UFS_LAZYMOD configured and softupdates aren't enabled.
UFS_LAZYMOD is intentionally left out of /sys/conf/options.
This is mainly to avoid almost useless disk i/o on battery powered
machines. It's silly to write to disk (on the next sync or when the
inode becomes inactive) just because someone hit a key or something
wrote to the screen or /dev/null.
PR: 5577
Previous version reviewed by: phk
in ufs_setattr() so that there is no need to pass timestamps to
UFS_UPDATE() (everything else just needs the current time). Ignore
the passed-in timestamps in UFS_UPDATE() and always call ufs_itimes()
(was: itimes()) to do the update. The timestamps are still passed
so that all the callers don't need to be changed yet.
by hacking on locked buffers without getblk()ing them, and we didn't
even use splbio() to prevent biodone() changing the buffer underneath
use when a write completes. I think there was no problem in practice
on i386's because the operations on b_flags and numdirtybufs happen to
be atomic. We still depend on biodone()'s operations on b_flags not
interfering with ours. I think there is only interference for B_ERROR,
and this is harmless because errors for async writes are ignored anyway.
Don't use mark_buffer_dirty() except for superblock-related metadata.
It was used in just one case where ordinary BSD buffering is more
natural.
to not using splbio(), and has rotted a little. The races were
probably harmless in practice because this function was only used
for superblock updates, and separate superblock updates are probably
prevented from running into each other by doing part of the update
synchronously.
Don't forget to clear the inode hash lock before returning from ext2_vget()
after getnewvnode() fails. Obtained from: rev.1.24 of ffs_vfsops.c (the
original patch for the getnewvnode() race). Forgotten in: rev.1.4 here.
Removed a duplicate comment. Duplicated in: rev.1.4 here.
Fixed the MALLOC() vs getnewvnode() race in ext2_vget(). Obtained from:
rev.1.39 of ffs_vfsops.c.
---------
Make callers of namei() responsible for releasing references or locks
instead of having the underlying filesystems do it. This eliminates
redundancy in all terminal filesystems and makes it possible for stacked
transport layers such as umapfs or nullfs to operate correctly.
Quality testing was done with testvn, and lat_fs from the lmbench suite.
Some NFS client testing courtesy of Patrik Kudo.
vop_mknod and vop_symlink still release the returned vpp. vop_rename
still releases 4 vnode arguments before it returns. These remaining cases
will be corrected in the next set of patches.
---------
Submitted by: Michael Hancock <michaelh@cet.co.jp>
Reverse the VFS_VRELE patch. Reference counting of vnodes does not need
to be done per-fs. I noticed this while fixing vfs layering violations.
Doing reference counting in generic code is also the preference cited by
John Heidemann in recent discussions with him.
The implementation of alternative vnode management per-fs is still a valid
requirement for some filesystems but will be revisited sometime later,
most likely using a different framework.
Submitted by: Michael Hancock <michaelh@cet.co.jp>
