Unreadable binaries

Richard W.M. Jones rjones at redhat.com
Thu Oct 22 10:04:36 UTC 2009


$ ll /usr/libexec/pt_chown 
-rws--x--x 1 root root 28418 2009-09-28 13:42 /usr/libexec/pt_chown
$ ll /usr/bin/chsh 
-rws--x--x 1 root root 18072 2009-10-05 16:28 /usr/bin/chsh

What is the purpose of making binaries like these unreadable?

Originally I thought it was something to do with them being setuid,
but there are counterexamples:

$ ll /usr/bin/passwd 
-rwsr-xr-x 1 root root 25336 2009-09-14 13:14 /usr/bin/passwd

Surely there is no possible secret in those binaries, since an
attacker could just as easily download the binary RPMs on another
machine in order to find out what is inside them.

There's a genuine reason for me asking about this.  When we build the
libguestfs supermin appliance[1] we would like to be able to read
these binaries as non-root.

Rich.

[1] http://libguestfs.org/README.txt section "Supermin appliance"

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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