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SubjectRe: [RFC PATCH tip 0/5] tracing filters with BPF
Andi Kleen <> 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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