Preventing ptrace()

From: Timo Sirainen (tssat_private)
Date: Sun Dec 29 2002 - 07:43:47 PST

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    While trying to prevent potentially flawed SSL libraries from causing
    much harm to my whole server, I've used a proxy process to handle it,
    chrooted to non-writable empty directory and running with a special UID.
    
    But this still allows it to ptrace() to other proxy processes handling
    other connections and causing damage with them. Are there any reasonable
    ways to prevent this? Are there any other problems than ptrace with it?
    
    Best I can think of now is to use a different UID for each process, but
    I don't really like it. This can't be done in default configuration and
    there's no easy way to keep track of allocated UID ranges especially if
    more programs started to use this method..
    
    grsecurity seems to disallow ptrace()ing processes outside it's chroot,
    but even that wouldn't help me unless I created a separate chroot
    directory for each process. Well, maybe that would be useful as an
    option..
    



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