Re: ext3 and undeletion

Richard B. Johnson
2002-02-26T18:34:35Z

On Tue, 26 Feb 2002, Mike Fedyk wrote:

> On Tue, Feb 26, 2002 at 06:07:49PM +0100, Martin Dalecki wrote:
[SNIPPED...]

> > >group) to get around the quota issue.
> >
> > Welcome to my kill-file. This just shows that you don't even have basic
> > background.
>
> Thank you.
>
> Now, if I'm talking out of my ass, can someone sane say so?
>
> It would only call chown/chgrp on the files *inside* the undelete dir, and
> user,group,etc would have to be accounted for in another way. Am I going in
> the wrong direction?
>
> Mike

No SUID, no nothing special to accomplish the following:

johnson[1]$ pwd
/home/users/johnson

johnson[2]$ rm -r *

johnson[3]$ ls -la
total 8
drwxr-xr-x 2 rjohnson guru 4096 Feb 26 13:03 .
drwxr-xr-x 54 root root 4096 Feb 26 13:04 ..

johnson[4]$ ls -laR /home/users/lost+found/rjohnson
total 5428
drwxr-xr-x 17 rjohnson guru 4096 Feb 13 16:54 .
drwxrwxrwx 21 root root 4096 Feb 26 05:34 ..
-rw-r--r-- 1 rjohnson guru 6 Oct 15 1998 .XF86_S3
-rw------- 1 rjohnson guru 0 Aug 10 1998 .Xauthority
-rw-r--r-- 1 rjohnson guru 1557 Dec 31 1997 .acrorc
-rw-r--r-- 1 rjohnson guru 273 May 13 1998 .addressbook
-rw-r--r-- 1 rjohnson guru 2684 May 13 1998 .addressbook.lu
-rw-r--r-- 1 rjohnson guru 0 Feb 13 16:54 .bash_history
-rwxr-xr-x 1 rjohnson guru 343 May 17 1999 .bashrc
-rw-r--r-- 1 rjohnson guru 2938 Sep 26 1994 .emacs
-rw-r--r-- 1 rjohnson guru 47 Aug 5 1996 .forward.SAVED
-rw-r--r-- 1 rjohnson guru 92 Feb 26 1997 .gopherrc
-rw-r--r-- 1 rjohnson guru 130 Nov 2 1998 .ispell_english
-rw-r--r-- 1 rjohnson guru 164 Sep 26 1994 .kermrc
-rw-r--r-- 1 rjohnson guru 34 Sep 26 1994 .less
-rw-r--r-- 1 rjohnson guru 114 Sep 26 1994 .lessrc
-rw-r--r-- 1 rjohnson guru 8 Feb 12 1999 .mosaic-cc-2.7b5
-rw-r--r-- 1 rjohnson guru 1349 Feb 12 1999 .mosaic-hot.html
-rw-r--r-- 1 rjohnson guru 1413 Feb 12 1999 .mosaic-hot.html.backup
-rw-r--r-- 1 rjohnson guru 282 Oct 20 1995 .mosaic-hotlist-default
-rw-r--r-- 1 rjohnson guru 854 Aug 22 1996 .mosaic-hotlist-default.html
drwx------ 2 rjohnson guru 4096 Jan 27 1997 .mosaic-personal-annotations
-rw-r--r-- 1 rjohnson guru 1718 Feb 12 1999 .mosaic-x-history
-rw-r--r-- 1 rjohnson guru 39706 Feb 12 1999 .mosaic-x-history.backup
-rw-r--r-- 1 rjohnson guru 5 Feb 12 1999 .mosaicpid
-rw-r--r-- 1 rjohnson guru 204 Oct 10 1995 .mymail
-rw-r--r-- 1 rjohnson guru 9236 Dec 30 1999 .pine-debug1
-rw-r--r-- 1 rjohnson guru 8978 Feb 19 1999 .pine-debug2
-rw-r--r-- 1 rjohnson guru 8978 Feb 19 1999 .pine-debug3
-rw-r--r-- 1 rjohnson guru 9237 Feb 19 1999 .pine-debug4
-rw-r--r-- 1 rjohnson guru 10682 Dec 30 1999 .pinerc
-rw-r--r-- 1 rjohnson guru 90 Jul 15 1995 .plan
-rw-r--r-- 1 rjohnson guru 625 Oct 15 1998 .procmailrc
-rw-r--r-- 1 rjohnson guru 17 Dec 6 1994 .profile
-rw-r--r-- 1 rjohnson guru 454 Jul 15 1995 .project
-rw-r--r-- 1 rjohnson guru 35 May 16 1995 .rhosts
drwxr-xr-x 2 rjohnson guru 4096 Jan 26 1997 .seyon
-rw-r--r-- 1 rjohnson guru 209 Feb 13 16:54 .signature
-rw-r--r-- 1 rjohnson guru 532 Nov 19 1996 .signature.SAVED
-rw-r--r-- 1 rjohnson guru 275 Sep 10 1997 .signature.bak
-rw-r--r-- 1 rjohnson guru 50 Feb 19 1999 .sversionrc
drwx------ 2 rjohnson guru 4096 Jan 26 1997 .term
-rw-r--r-- 2 rjohnson guru 12288 Sep 11 1996 .vacation.dir
-rw-r--r-- 1 rjohnson guru 247 Sep 11 1996 .vacation.msg
-rw-r--r-- 2 rjohnson guru 12288 Sep 11 1996 .vacation.pag
-rwxr-xr-x 1 rjohnson guru 443 Sep 4 1997 .xinitrc
-rw-r--r-- 1 rjohnson guru 1117 Sep 2 1998 BOMBER.CREW
-rw-r--r-- 1 rjohnson guru 7697 Jul 27 1998 BusLogic.html
-rw-r--r-- 1 rjohnson guru 21 Apr 17 1998 CHECK.KERNEL
-rw-r--r-- 1 rjohnson guru 6519 Mar 30 1998 Computers
-rw-r--r-- 1 rjohnson guru 442 Sep 28 1998 DELAY.PATCH
-rw-r--r-- 1 rjohnson guru 4349 Nov 2 1998 Flying_saucers
-rw-r--r-- 1 rjohnson guru 4349 Mar 17 1998 Flying_saucers.bak
-rw-r--r-- 1 rjohnson guru 576 May 15 1998 IRQ.PATCH
-rw-r--r-- 1 rjohnson guru 69 Apr 24 1998 ME.TXT
-rwxr-xr-x 1 rjohnson guru 131 Aug 3 1998 MIT
drwx--x--x 2 rjohnson guru 4096 Oct 21 1998 Mail
-rw-r--r-- 1 rjohnson guru 135 Jul 11 1998 PATENT
-rw-r--r-- 1 rjohnson guru 625 Jun 3 1998 _procmail
drwxr-xr-x 2 rjohnson guru 4096 Dec 1 1998 asm
-rwxr-xr-x 1 rjohnson guru 1358 Sep 16 1997 backup
-rw-r--r-- 1 rjohnson guru 230454 Jun 5 1998 baldie.bmp
drwxr-xr-x 3 rjohnson guru 4096 Jun 1 1998 bomb
-rwxr-xr-x 1 rjohnson guru 2993 Oct 9 16:06 c.c
drwxr-xr-x 2 rjohnson guru 4096 Sep 28 1998 callback
-rw-r--r-- 1 rjohnson guru 12900 May 18 1998 chaos.txt
-rwxr-xr-x 1 rjohnson guru 57276 Dec 9 1997 chkdev.c
-rw-r--r-- 1 rjohnson guru 5276 Nov 17 1998 cpu.speed
-rw-r--r-- 1 rjohnson guru 895 Sep 29 1998 delay.c
-rw-r--r-- 1 rjohnson guru 964 Sep 30 1998 delay.patch
-rwxr-xr-x 1 rjohnson guru 5414 Mar 9 1998 diskio
-rw-r--r-- 1 rjohnson guru 3364 Nov 22 1998 evil.IDE
-rwxr-xr-x 1 rjohnson guru 5061 Nov 11 1998 fastchk.asm
-rw-r--r-- 1 rjohnson guru 957 Oct 31 1997 firewall.sh
-rwxr-xr-x 1 rjohnson guru 4717 Oct 1 15:09 fpu
-rw-r--r-- 1 rjohnson guru 499 Oct 30 1997 fpu.c
-rw-r--r-- 1 rjohnson guru 257507 Jan 28 08:47 friday.ps
-rw-r--r-- 1 rjohnson guru 5363 Aug 20 1997 ftp.txt
-rwxr-xr-x 1 rjohnson guru 345 Sep 15 1998 get_bomb
-rwxr-xr-x 1 rjohnson guru 219539 Dec 6 1994 gwm
drwxr-xr-x 2 rjohnson guru 4096 Nov 14 1997 homepage
-rwxr-xr-x 1 rjohnson guru 84 Jan 28 1998 hostfile
-rw-r--r-- 1 rjohnson guru 86994 Jan 28 1998 hosts.tmp
-rwxr-xr-x 1 rjohnson guru 22261 Sep 10 1998 iiclink.asm
-rw-r--r-- 1 rjohnson guru 1522 May 25 1998 info.bak
-rw-r--r-- 1 rjohnson guru 392 Aug 17 1998 ioapic-2.1.115-A
-rw-r--r-- 1 rjohnson guru 30547 May 14 1998 irq.c
drwxr-xr-x 2 rjohnson guru 4096 Jan 26 1997 jboot
-rw-r--r-- 1 rjohnson guru 675 Nov 29 1995 jboot-1.13.lsm
-rw-r--r-- 1 rjohnson guru 8263 Oct 4 1998 jitter.c
-rwxr-xr-x 1 rjohnson guru 79 Jun 26 1998 keepalive.sh
-rw-r--r-- 1 rjohnson guru 24348 Dec 10 1997 latierra.c
-rw-r--r-- 1 rjohnson guru 267 Aug 11 1997 lawsuit
drwxr-xr-x 2 rjohnson guru 4096 Mar 19 1997 logs
-rwxr-xr-x 1 rjohnson guru 5904 Nov 9 1998 lookups
-rw-r--r-- 1 rjohnson guru 1533 Nov 9 1998 lookups.c
-rw-r--r-- 1 rjohnson guru 1339467 Aug 31 1998 ls-lR
-rw-r--r-- 1 rjohnson guru 1239040 Jul 28 1998 m4-1.4.tar
drwx------ 2 rjohnson guru 4096 Oct 5 1999 mail
-rwxr-xr-x 1 rjohnson guru 411945 Nov 14 1997 main
-rwxr-xr-x 1 rjohnson guru 469 Dec 16 1996 make_bfloppy
-rwxr-xr-x 1 rjohnson guru 474 Sep 16 1996 make_boot
-rwxr-xr-x 1 rjohnson guru 460 Jun 19 1998 make_floppy
-rw-r--r-- 1 rjohnson guru 1175 Mar 20 1998 mem.c
-rw-r--r-- 1 rjohnson guru 5835 Nov 9 1998 messages
-rwxr-xr-x 1 rjohnson guru 36 Sep 12 1996 modem
-rw-r--r-- 1 rjohnson guru 28084 Oct 3 1998 mptable.c
-rw-r--r-- 1 rjohnson guru 5715 Aug 22 1996 mwmrc
-rwxr-xr-x 1 rjohnson guru 1312 Jan 28 1997 new_backup
-rw-r--r-- 1 rjohnson guru 2343 Apr 21 1998 operating.systems
-rwxr-xr-x 1 rjohnson guru 718 Jan 2 1996 plot
drwxr-xr-x 3 rjohnson guru 4096 Jan 26 1997 pppdc
drwxr-xr-x 2 rjohnson guru 4096 Jan 26 1997 ptools
-rw-r--r-- 1 rjohnson guru 3955 Jun 18 1998 reboot.c
-rwxr-xr-x 1 rjohnson guru 214 Nov 6 1997 restore
-rwxr-xr-x 1 rjohnson guru 2185 Jan 6 1997 rights.h
-rwxr-xr-x 1 rjohnson guru 7293 Dec 26 1996 showserv
-rw-r--r-- 1 rjohnson guru 1765 Aug 13 2001 smile.sh
drwxr-xr-x 19 rjohnson guru 4096 Apr 17 1998 test
-rw-r--r-- 1 rjohnson guru 788903 Jul 22 1998 test.cdcolor
-rwxr-xr-x 1 rjohnson guru 5019 May 25 1998 timer
-rw-r--r-- 1 rjohnson guru 1247 Oct 3 1998 timer.c
drwxr-xr-x 10 rjohnson guru 4096 Nov 18 1998 tools
-rw-r--r-- 1 rjohnson guru 471 Oct 9 16:09 typescript
-rw-r--r-- 1 rjohnson guru 426 Jun 24 1998 udelay.patch
-rwxr-xr-x 1 rjohnson guru 4137 Dec 5 1996 unix2world
-rwxr-xr-x 1 rjohnson guru 171 Jan 27 1998 update_host
-rwxr-xr-x 1 rjohnson guru 84707 Jul 10 1998 utility.asm
-rwxr-xr-x 1 rjohnson guru 16819 Sep 25 1998 vl12ct.asm
-rwxr-xr-x 1 rjohnson guru 3845 Dec 5 1996 world2unix
-rwxr-xr-x 1 rjohnson guru 8141 Oct 9 16:08 xxx

All the deleted files, with the correct path(s), are now in the
top directory file the file-system ../lost+found directory. They
are still owned by the original user, still subject to the same
quota. The disk space can't run out because you have simply moved
files that didn't exceed the disk space before they were moved.

All one needs is a compile-time switch to enable the following:

If the lost+found directory is writable by the current user, blindly
create any paths that may already exist, using the ../lost+found/~
directory as the root, and rename() the file you think you are
unlink()ing unless the file exists in /tmp, or is a sym-link,
special file, pipe, socket or device.

To enable such a function (after modifing the C library), just make
lost+found world-writable. The permissions of its contents remain
unchanged as does the owner. If the owner didn't want others in
the universe to read his resume.txt, or porno.jpg, they still can't
read it and they can't overwrite it.

The sysadmin deletes the contents (probably via crond), every time it
has been backed up.

There are lots of advantages to this scheme. The most notable being
that it is transparent to normal users. Database programs that do
a lot of deleting temporary files that don't exist in /tmp, need to
be have their default directory on a file-system with lost+found
not world writable.

Cheers,
Dick Johnson

Penguin : Linux version 2.4.1 on an i686 machine (797.90 BogoMips).

111,111,111 * 111,111,111 = 12,345,678,987,654,321