On Mon, Feb 12, 2018 at 4:40 PM, Laura Abbott <labbott@xxxxxxxxxx> wrote: > On 02/12/2018 03:27 PM, Kees Cook wrote: >> >> On Sun, Feb 4, 2018 at 7:05 AM, Igor Stoppa <igor.stoppa@xxxxxxxxxx> >> wrote: >>> >>> On 04/02/18 00:29, Boris Lukashev wrote: >>>> >>>> On Sat, Feb 3, 2018 at 3:32 PM, Igor Stoppa <igor.stoppa@xxxxxxxxxx> >>>> wrote: >>> >>> >>> [...] >>> >>>>> What you are suggesting, if I have understood it correctly, is that, >>>>> when the pool is protected, the addresses already given out, will >>>>> become >>>>> traps that get resolved through a lookup table that is built based on >>>>> the content of each allocation. >>>>> >>>>> That seems to generate a lot of overhead, not to mention the fact that >>>>> it might not play very well with the MMU. >>>> >>>> >>>> That is effectively what i'm suggesting - as a form of protection for >>>> consumers against direct reads of data which may have been corrupted >>>> by some irrelevant means. In the context of pmalloc, it would probably >>>> be a separate type of ro+verified pool >>> >>> ok, that seems more like an extension though. >>> >>> ATM I am having problems gaining traction to get even the basic merged >>> :-) >>> >>> I would consider this as a possibility for future work, unless it is >>> said that it's necessary for pmalloc to be accepted ... >> >> >> I would agree: let's get basic functionality in first. Both >> verification and the physmap part can be done separately, IMO. > > > Skipping over physmap leaves a pretty big area of exposure that could > be difficult to solve later. I appreciate this might block basic > functionality but I don't think we should just gloss over it without > at least some idea of what we would do. What's our exposure on physmap for other regions? e.g. things that are executable, or made read-only later (like __ro_after_init)? -Kees -- Kees Cook Pixel Security -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
