chmod -R only files or only directories?

[SpreadTooThin]

This question started when I wasn't able to tar up a directory because the permissions where set in such a way that tar wasn't able to read some things, even as root,

brute force chmod -R +x on the directory and everything under it helps, but might open up some vulnerabilities.

Can you tell chmod -R +x to only effect directories or conversely only to effect 'actual' files?

Many thanks in advance.

[hymie!]

In our last episode, the evil Dr. Lacto had captured our hero,

SpreadTooThin <bjobr...@gmail.com>, who said:

>Can you tell chmod -R +x to only effect directories

find . -type d -exec chmod +x {} \;

>or conversely only to effect 'actual' files?

find . -type f -exec chmod +x {} \;

--hymie! http://lactose.homelinux.net/~hymie hy...@lactose.homelinux.net

[Barry Margolin]

In article <170fa773-1be3-44b4...@googlegroups.com>,

If root can't read the files, it probably won't be able to chmod them,
either.

--
Barry Margolin, bar...@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***

[Casper H.S. Dik]

There's often an option in chmod to "change the executable bits only if other
executable bits or if the file is a directory":

chmod -R +X ...

(not exactly what you wanted but it comes close)

Casper

[Gerard H. Pille]

Barry Margolin wrote:
>
> If root can't read the files, it probably won't be able to chmod them,
> either.
>

Remind me, pray, how does one prevent root from reading a file?

[Barry Margolin]

In article <4fbe8a04$0$3119$ba62...@news.skynet.be>,

There are some security-enhanced versions of Unix that have
finer-grained access control, which even root can't get around.

[John Dow]

Gerard H. Pille the Monkey was never naughty:

rm -f $filename :)

J
--
John Dow <j...@nelefa.org.invalid>
... Blog : http://www.nelefa.org Writing : http://www.johnmdow.co.uk
/|\ Constructed using slrn and vi.
/ | \ Zomoniac is Wrong. Fact.

[Barry Margolin]

In article <vilain-01473E....@news.individual.net>,
Michael Vilain <vil...@NOspamcop.net> wrote:

> In article <jnmsf9-...@bague.nelefa.org>,

> John Dow <j...@nelefa.org.invalid> wrote:
>
> > Gerard H. Pille the Monkey was never naughty:
> > > Barry Margolin wrote:
> > >>
> > >> If root can't read the files, it probably won't be able to chmod them,
> > >> either.
> > >>
> > >
> > > Remind me, pray, how does one prevent root from reading a file?
> >
> > rm -f $filename :)
> >
> > J
>

> On Linux and Solaris, you can't AFAIK. Unless the file is encrypted,
> root can read it. Some other OSs implement ACLs that might prevent root
> from having access to a file, but that would break a lot of stuff. The
> basic assumption in UNIX is that root has unencumbered access to all
> files. The file permissions check in the OS is bypassed if the process'
> ID is 0 (root).
>
> So, encrypt the file and root will still be able to read it. But they
> won't be able to do much with it.

The OP said that he couldn't tar a directory because of permissions
problems, even as root. Encryption is irrelevant. rm would certainly
prevent you from tarring the file, although it won't cause a permissions
error.

My guess is he's on a flavor of Unix with security extensions that
override root's super powers.

[Gerard H. Pille]

Barry Margolin wrote:
>
> My guess is he's on a flavor of Unix with security extensions that
> override root's super powers.
>

/tmp
# ls -ld testposi2_files
d-w------- 3 ghp ghp 4096 Aug 16 18:55 testposi2_files
/tmp
# ls -l /bin/tar
-rwxr-xr-x 1 root root 311832 Dec 31 2011 /bin/tar
/tmp
# cp /bin/tar /bin/tar_ghp
/tmp
# chown ghp:ghp /bin/tar_ghp
/tmp
# chmod u+s /bin/tar_ghp
/tmp
# tar_ghp cvf /tmp/test.tar testposi2_files
tar_ghp: testposi2_files: Cannot open: Permission denied
tar_ghp: Exiting with failure status due to previous errors

[hymie!]

In our last episode, the evil Dr. Lacto had captured our hero,

"Gerard H. Pille" <g...@skynet.be>, who said:

># ls -ld testposi2_files
>d-w------- 3 ghp ghp 4096 Aug 16 18:55 testposi2_files

># cp /bin/tar /bin/tar_ghp

># chown ghp:ghp /bin/tar_ghp

># chmod u+s /bin/tar_ghp

># tar_ghp cvf /tmp/test.tar testposi2_files
>tar_ghp: testposi2_files: Cannot open: Permission denied
>tar_ghp: Exiting with failure status due to previous errors

What's your point here? That you can specifically decline to use your
rootly powers, and then be upset that your rootly powers don't work?

--hymie! http://lactose.homelinux.net/~hymie hy...@lactose.homelinux.net
-------------------------------------------------------------------------------

[Gerard H. Pille]

In case you're being serious, hymie: that was not my point.