How about just O_EXEC? (was Re: [PATCH v5 3/6] fs: Enable to enforce noexec mounts or file exec through O_MAYEXEC)

[Florian Weimer]

* Kees Cook:

> Maybe I've missed some earlier discussion that ruled this out, but I
> couldn't find it: let's just add O_EXEC and be done with it. It actually
> makes the execve() path more like openat2() and is much cleaner after
> a little refactoring. Here are the results, though I haven't emailed it
> yet since I still want to do some more testing:
> https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git/log/?h=kspp/o_exec/v1

I think POSIX specifies O_EXEC in such a way that it does not confer
read permissions.  This seems incompatible with what we are trying to
achieve here.

Thanks,
Florian