Re: [PATCH v5 0/6] seccomp: add PR_SECCOMP_EXT and SECCOMP_EXT_ACT_TSYNC

On Mon, Jun 2, 2014 at 4:05 PM, Kees Cook [off-list ref] wrote:

On Mon, Jun 2, 2014 at 2:17 PM, Andy Lutomirski [off-list ref] wrote:

quoted

On Mon, Jun 2, 2014 at 1:06 PM, Kees Cook [off-list ref] wrote:

quoted

On Mon, Jun 2, 2014 at 12:59 PM, Andy Lutomirski [off-list ref] wrote:

quoted

On Mon, Jun 2, 2014 at 12:47 PM, Kees Cook [off-list ref] wrote:

quoted

Hi Andrew,

Would you be willing to carry this series? Andy Lutomirski appears
happy with it now. (Thanks again for all the feedback Andy!) If so, it
has a relatively small merge conflict with the bpf changes living in
net-next. Would you prefer I rebase against net-next, let sfr handle
it, get carried in net-next, or some other option?

Well, I'm still not entirely convinced that we want to have this much
multiplexing in a prctl, and I'm still a bit unconvinced that the code

I don't want to get caught without interface argument flexibility
again, so that's why the prctl interface is being set up that way.

I was thinking that a syscall might be a lot prettier.  It may pay to
cc linux-api, too.

I'll offer you a deal: if you try to come up with a nice, clean
syscall, I'll try to write a fast(er) path for x86_64 to reduce
overhead.  I bet I can save 90-100ns per syscall. :)

Now added to the Cc.

Which path do you mean to improve? Neither the prctl nor a syscall for
this would need to be fast at all.

Non-seccomp-related syscalls when seccomp is enabled.

I don't want to go in circles on this. I've been there before on my
VFS link hardening series, and my module restriction series. I would
like consensus from more than just one person. :)

I can't offer you anyone else's review, unfortunately :-/

I'd like to hear from other folks on this (akpm?). My instinct is to
continue using prctl since that is already where mediation for seccomp
happens. I don't see why prctl vs a new syscall makes a difference
here, frankly.

Aesthetics?  There's a tendency for people to get annoyed at big
multiplexed APIs, and your patches will be doubly multiplexed.

TBH, I care more about the atomicity thing than about the actual form
of the API.

--Andy

-Kees

--
Kees Cook
Chrome OS Security

-- 
Andy Lutomirski
AMA Capital Management, LLC