Messages in this thread |  | | Date | Wed, 3 Oct 2001 07:49:39 -0500 (CDT) | From | Jesse Pollard <> | Subject | Re: Security question: "Text file busy" overwriting executables but not shared libraries? |
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Alexander Viro <viro@math.psu.edu>: > On Tue, 2 Oct 2001, Rob Landley wrote: > > > Anybody want to venture an opinion why overwriting executable files that are > > currently in use gives you a "text file busy" error, but overwriting shared > > libraries that are in use apparently works just fine (modulo a core dump if > > you aren't subtle about your run-time patching)? > > > > Permissions are still enforced, but it seems to me somebody who cracks root > > on a system could potentially modify the behavior of important system daemons > > without changing their process ID numbers. > > > > Did I miss something somewhere? > > Somebody who cracks root can attach gdb to a daemon, modify the contents of > its text segment and detach. No need to change any files...
True, but the original problem still appears to be a bug.
Even the owner of the file should not be able to write to a busy executable, whether it is a shared library, or an executable image. Remove it, yes. Create a new one (in a different inode) - yes.
But not modify a busy executable.
------------------------------------------------------------------------- Jesse I Pollard, II Email: pollard@navo.hpc.mil
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