Messages in this thread | | | Date | Thu, 26 Feb 1998 01:10:03 -0800 (PST) | From | Dean Gaudet <> | Subject | Re: PID sequences |
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On Thu, 26 Feb 1998, Chris Wedgwood wrote:
> Anyhow... I assume they are using rc4 so assuming the initial state is kept > secret these should be fairly hard to guess - only, it doesn't satisfy > Dean's desired criterion that no PID be re-used within a short amount of > time.
Yeah within 1s is my only concern. I think that we should have high confidance that time() concat getpid() will generate unique identifier on a single system... I think if you break that you're looking at trouble with many tools. In particular Message-ID creation, /tmp filename creation... qmail's maildir format.
> P.S. I can fork about 732 times/sec on my machine. This doesn't look good > for re-use if we only have 15 bits.
Although I'll admit, a system doing this many creations isn't really doing the right thing anyhow. But it'd suck if folks can devise a denial of service or exploit just because linux can do 16k creations per second on next year's hardware ;)
There was talk a few months back about a 32-bit pid_t/tid_t encoding which was useful for fixing some POSIX thread issues. Maybe that should be revisited?
Dean
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