On Sat, Jun 23, 2018 at 12:27:43AM +0200, Jann Horn wrote: > On Fri, Jun 22, 2018 at 11:51 PM Kees Cook <keescook@xxxxxxxxxxxx> wrote: > > > > On Fri, Jun 22, 2018 at 11:09 AM, Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote: > > > One possible extra issue: IIRC /proc/.../mem uses FOLL_FORCE, which is not what we want here. > > Uuugh, I forgot about that. > > > > How about just adding an explicit “read/write the seccomp-trapped task’s memory” primitive? That should be easier than a “open mem fd” primitive. > > > > Uuugh. Can we avoid adding another "read/write remote process memory" > > interface? The point of this series was to provide a lightweight > > approach to what should normally be possible via the existing > > seccomp+ptrace interface. I do like Jann's context idea, but I agree > > with Andy: it can't be a handle to /proc/$pid/mem, since it's > > FOLL_FORCE. Is there any other kind of process context id we can use > > for this instead of pid? There was once an idea of pid-fd but it never > > landed... This would let us get rid of the "id" in the structure too. > > And if that existed, we could make process_vm_*v() safer too (taking a > > pid-fd instead of a pid). > > Or make a duplicate of /proc/$pid/mem that only differs in whether it > sets FOLL_FORCE? The code is basically already there... something like > this: But we want more than just memory access, I think. rootfs access, ns fds, etc. all seem like they might be useful, and racy to open. I guess I see two options: use the existing id and add something to seccomp() to ask if it's still valid or independent of this patchset add some kind of pid id :\ Tycho -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
