Re: Compat 32-bit syscall entry from 64-bit task!? [was: Re:[RFC,PATCH 1/2] seccomp_filters: system call filtering using BPF]

[Linus Torvalds]

On Thu, Jan 19, 2012 at 4:21 PM, Indan Zupancic <indan@xxxxxx> wrote:
>
> With current ptrace you can do exactly that. It's just very slow, because
> you have to copy the data word by word via PTRACE_PEEKDATA. But if Linux
> would support something like BSD's PT_IO ptrace request, then it could be
> limited to one extra ptrace command. (PTRACE_STRNCPY would be handy.)

Actually, you could use the new "process_vm_readv/writev()" system
calls. No need to do the crazy slow ptrace stuff.

I dunno. It got merged through Andrew, and the code looks sane, but
I've never actually seen anybody *use* it. So maybe there is something
wrong there. And no, it doesn't have a "strncpy" interface, I'm
afraid.

                   Linus
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/