Messages in this thread | | | Subject | Re: [RFC PATCH tip 0/5] tracing filters with BPF | From | (Frank Ch. Eigler) | Date | Thu, 05 Dec 2013 11:31:18 -0500 |
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Andi Kleen <andi@firstfloor.org> writes:
> [...] While it sounds interesting, I would strongly advise to make > this capability only available to root. Traditionally lots of > complex byte code languages which were designed to be "safe" and > verifiable weren't really. e.g. i managed to crash things with > "safe" systemtap multiple times. [...]
Note that systemtap has never been a byte code language, that avenue being considered lkml-futile at the time, but instead pure C. Its safety comes from a mix of compiled-in checks (which you can inspect via "stap -p3") and script-to-C translation checks (which are self-explanatory). Its risks come from bugs in the checks (quite rare), problems in the runtime library (rare), and problems in underlying kernel facilities (rare or frequent - consider kprobes).
> So the likelyhood of this having some hole somewhere (either in > the byte code or in some library function) is high.
Very true!
- FChE
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