Re: siginfo pid not populated from ptrace?

[Tycho Andersen]

On Thu, Dec 06, 2018 at 10:48:39AM -0800, Linus Torvalds wrote:
> On Thu, Dec 6, 2018 at 6:40 AM Eric W. Biederman <ebiederm@xxxxxxxxxxxx> wrote:
> >
> > We have in the past had ptrace users that weren't just about debugging
> > so I don't know that it is fair to just dismiss it as debugging
> > infrastructure.
> 
> Absolutely.
> 
> Some uses are more than just debug. People occasionally use ptrace
> because it's the only way to do what they want, so you'll find people
> who do it for sandboxing, for example. It's not necessarily designed
> for that, or particularly fast or well-suited for it, but I've
> definitely seen it used that way.
> 
> So I don't think the behavioral test breakage like this is necessarily
> a huge deal, and until some "real use" actually shows that it cares it
> might be something we dismiss as "just test", but it very much has the
> potential to hit real uses.
> 
> The fact that a behavioral test broke is definitely interesting.
> 
> And maybe some of the siginfo allocations could depend on whether the
> signal is actually ever caught or not.
> 
> For example, a terminal signal (or one that is ignored) might not need
> siginfo. But if the process is ptraced, maybe that terminal signal
> isn't actually terminal? So we might have situations where we want to
> simply check "is the signal target being ptraced"..

Yes, something like this, I suppose? It works for me.

Tycho