iirc I think that the BPF JIT is disabled by default? Your kernel might be compiled with `CONFIG_BPF_JIT`, but I think the sysctl knob (`bpf_jit_enable`) is set to 0 by default.
Also there's a sysctl for unprivileged BPF called `unprivileged_bpf_disabled`. On my system it seems to default to 0.
Thanks for the clarification, although I recall messing with eBPF and kprobes before - pretty sure you can dereference pointers?
editx2: Oh, guess seccomp doesn't use eBPF yet? Suppose that raises a bunch of questions about permissions necessary for specifying programs that might dereference kernel pointers and such by emitting `bpf()` calls.
I was under the impression that seccomp was a bit more flexible (via ptrace() and BPF fanciness) - although I guess you'd need other co-operating processes in userspace? I've only played around with it a tiny bit.
Also, both kinds of policy are resident in files. I don't understand your point there.
There's some kind of bind here between "putting burden on end-users" and "putting burden on application developers."
Either you (a) ship $LSM with some defaults that are necessarily general (so as to avoid breaking applications) and let the user fit filters to their circumstances, or; (b) push for developers to write/maintain filters baked into their applications (ie. using some kernel features like `seccomp` and what-have-you).
Love Graphviz, been using it for some time now. It's kind of painful rendering large graphs. Does anyone know the particular reason why `dot` and friends only seem to take advantage of one CPU core when drawing graphs? Multi-threading unimplemented? - or impossible to implement for some reason?
I've only dealt with this on Intel chipset HDMI - if I'm remembering correctly there's some part of the snd_hda_intel kernel modules you can blacklist in order to disable this.
>The problem of looking at human consciousness is similar to someone that knows little about computer processors pulling apart an I7 and trying to figure meaningful things about what is going on inside. Without knowing the history of processor design, there will be huge information gaps on why some parts work the way they do.
I don't think the analogy is adequate. A processor is an object - it "objects" to all of us. It appears to have an existence independent of the thing that recognizes it as such. When we embark on an empirical investigation of something, we make a distinction between the scientific observer and the scientific object. We come to an agreement about the boundaries of the object. This does not appear to be the case if you want to call consciousness "that special [condition, or process, or property, or pattern, etc.] of being a scientific observer" (which we would ideally want because it seems to encapsulate all those special things that distinguish human beings from other organisms with nervous systems).
In that domain, we cannot make a distinction between subject and object. In order to even speak intelligibly about things, we must all draw the boundary of the thing we're talking about - but we are in the peculiar position of being the very act of drawing the boundary.
> .. that perhaps 'our ability to think about the issue is constrained by our language' and '[consciousness] workings being inaccessible to introspection' are the same thing.
I like to think about it that way, but it makes the problem feel intractable.
The problem is that we want to describe consciousness as "that thing that allows an organism to describe consciousness as 'that thing that allows an organism to describe consciousness as ´that thing that allows an organism to describe consciousness as [...]´'"
> But our consciousness goes beyond simple self-awareness: having a theory of mind is a step beyond (and is realizing that others have a theory of mind a step beyond that?)
That [and this] whole space [of considerations, here] appears to be fraught with circularities like this:
Step 1. Draw a distinction between consciousness and meta-consciousness.
Step 2. "From what vantage point, and with what 'machinery' do we make a distinction?"
Step 3. Go back to Step 1.
> .. that our ability to think about the issue is constrained by our language.
I think I agree, otherwise I'm tempted to think that we would have already arrived, trivially, at some clearer kind of agreement about it.
Blade Runner means so much to me. I'm very glad that this is a thing, although, like with all sequels and re-interpretations of experiences that are near-and-dear to me, I'm struggling through "trying not to have too many expectations."
I'd like to see the way that this is re-interpreted - but there's a very particular aesthetic and air about the original that I'd love to see kept around.
I think DirtyCOW (CVE-2016-5195) had been dormant in the kernel for a long time. If I remember correctly the PoC demonstrated writing on root-owned files. Might be relevant.
https://elixir.free-electrons.com/linux/v4.15-rc6/source/ker...