can't exec /usr/sbin/named-xfer: Permission denied

[Kevin Darcy]

Brian Elliott Finley wrote:

> Thus spake Kevin Darcy (kcd at daimlerchrysler.com):
>
> >
> > Linux has a system-call tracer, doesn't it? "strace" or something like that? Fire that up to
> > determine *exactly* what named is trying to execute.
>
> I have run it (and named-xfer) successfully by hand.  The problem is
> trying to get named to invoke strace when it automatically invokes
> named-xfer.

Doesn't strace have a "follow" option, like Solaris truss'es "-f" option, i.e. follow child
processes?

> This is actually a very interesting point:
> o named-xfer by hand works
> o named-xfer invoked by named does not
>
> What could be different about how named-xfer is invoked automatically?
> The arguments I'm using when running it manually (yes chrooted in the
> same way) are arguments I've taken from a properly running named-xfer
> invoked by named (as seen through ps -auxwww).

The only thing that comes to mind right now is to replace named-xfer with a "wrapper" that just,
say, writes its argv[] to a file. This would at least tell you that named-xfer is being invoked.

By the way, you indicated that you're running an exploitable version (8.2.2-p7). It's conceivable
that what you are encountering is an aborted or incomplete attempt to create a trojan horse. To be
on the safe side, I'd wipe out and reconstruct the chroot jail completely and run a secure version
of BIND in it. Then see if you still have the problem.


- Kevin

> > By the way, can you run that named-xfer binary while *manually* chroot()'ed?
> >
> >
> > - Kevin
> >
> > Brian Elliott Finley wrote:
> >
> > > Still having the same issues.  Any one have another suggestion?
> > >
> > > -Brian
> > >
> > > Thus spake Brian Finley (Home) (brian at thefinleys.com):
> > >
> > > > Thus spake Jim Reid (jim at rfc1035.com):
> > > >
> > > > > >>>>> "Brian" == Brian Elliott Finley <brian at thefinleys.com> writes:
> > > > >
> > > > >     Brian> named works fine, but named-xfer consistently farts with
> > > > >     Brian> this message:
> > > > >
> > > > >     Brian>  "can't exec /usr/sbin/named-xfer: Permission denied"
> > > > >
> > > > >
> > > > >     Brian> named is started with this command:
> > > > >
> > > > >     Brian>  "/usr/sbin/named -d 3 -u bind -g bind -t /chrootd/bind"
> > > > >
> > > > >     Brian> What am I missing?
> > > > >
> > > > > Try making sure /usr/bin/named-xfer lives in you chroot jail
> > > >
> > > > $ ls -l /chrootd/bind/usr/sbin/named-xfer
> > > > -rwxr-xr-x    1 root     root       203004 Nov 11 17:11 /chrootd/bind/usr/sbin/named-xfer
> > > >
> > > > > and has
> > > > > sufficient execute permission for the uid bind.
> > > >
> > > > Yup.
> > > >
> > > > > And make sure that
> > > > > named-xfer has proper access permissions to write any zone files it
> > > > > transfers into the chroot jail.
> > > >
> > > > I've even tried doing a "chown -R bind.bind /chrootd/bind/*" to be
> > > > sure...
> > > >
> > > > Same error.
> > > >
> > > > -Brian
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > --
> > > > -------------------------------------------------------
> > > >  Brian Elliott Finley     VA Linux http://valinux.com/
> > > >  http://thefinleys.com/            phone: 972.447.9563
> > > >  http://systemimager.org/           phax: 801.912.6057
> > > >  CSA, C2000, CNE, CLSE, MCP, and Certifiable Linux Nut
> > > > -------------------------------------------------------
> > >
> > > --
> > > -------------------------------------------------------
> > >  Brian Elliott Finley     VA Linux http://valinux.com/
> > >  http://thefinleys.com/            phone: 972.447.9563
> > >  http://systemimager.org/           phax: 801.912.6057
> > >  CSA, C2000, CNE, CLSE, MCP, and Certifiable Linux Nut
> > > -------------------------------------------------------
> >
> >
> >
>
> --
> -------------------------------------------------------
>  Brian Elliott Finley     VA Linux http://valinux.com/
>  http://thefinleys.com/            phone: 972.447.9563
>  http://systemimager.org/           phax: 801.912.6057
>  CSA, C2000, CNE, CLSE, MCP, and Certifiable Linux Nut
> -------------------------------------------------------