running 5.1-RELEASE with no procfs mounted (lockups?)

Pawel Jakub Dawidek nick at
Fri Jul 18 01:01:06 PDT 2003

On Thu, Jul 17, 2003 at 01:01:11PM -0400, Robert Watson wrote:
+> Most system functionality that relied on procfs has been rewritten to rely
+> on other mechanisms.  In general, I advise against running procfs--it's
+> interesting, but conceptually it's very risky.  If you look at the history
+> of security advisories on systems that supported procfs (FreeBSD, Linux,
+> Solaris), you'll get a sense of why: procfs represents processes as files,
+> and the semantics of processes and of files are very different.  For
+> example, with processes, there are notions of revoked access; processes
+> are reused to hold several programs often running with different
+> credentials.
+> The behavior I'm aware of that currently relies on procfs and has not yet
+> been adapted to use ptrace() or sysctl() are:
+> ps -e           Relies on groping around in the address space of each
+>                 process to display environmental variables.

I've prepare patch for this:

+> truss		Relies on the event model of procfs; there have been some
+> 		initial patches and discussion of migrating truss to ptrace() but
+> 		I don't think we have anything very usable yet.  I'd be happy to
+> 		be corrected on this. :-)

Hmm, why to change this behaviour? Is there any functionality that
ktrace(1) doesn't provide? IMHO made ugly hacks just to made truss(1)
(for years procfs-dependent) working without procfs is a bad idea.
It could only display some friendly message that procfs isn't mounted
instead of:

	truss: cannot open /proc/25217/mem: No such file or directory
	truss: cannot open /proc/curproc/mem: No such file or directory

Pawel Jakub Dawidek                       pawel at
UNIX Systems Programmer/Administrator
Am I Evil? Yes, I Am!           
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