On 11/01/2010 11:37 PM, Christopher Yeoh wrote:
> > You could have each process open /proc/self/mem and pass the fd using > SCM_RIGHTS. > > That eliminates a race; with copy_to_process(), by the time the pid > is looked up it might designate a different process. Just to revive an old thread (I've been on holidays), but this doesn't work either. the ptrace check is done by mem_read (eg on each read) so even if you do pass the fd using SCM_RIGHTS, reads on the fd still fail. So unless there's good reason to believe that the ptrace permission check is no longer needed, the /proc/pid/mem interface doesn't seem to be an option for what we want to do.
Perhaps move the check to open(). I can understand the desire to avoid letting random processes peek each other's memory, but once a process has opened its own /proc/self/mem and explicitly passed it to another, we should allow it.
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