Messages in this thread | | | Subject | Re: [PATCH 7/9] Pmalloc Rare Write: modify selected pools | From | Igor Stoppa <> | Date | Tue, 24 Apr 2018 16:39:11 +0400 |
| |
On 24/04/18 16:32, lazytyped wrote: > > > On 4/24/18 1:50 PM, Matthew Wilcox wrote: >> struct modifiable_data { >> struct immutable_data *d; >> ... >> }; >> >> Then allocate a new pool, change d and destroy the old pool. > > With the above, you have just shifted the target of the arbitrary write > from the immutable data itself to the pointer to the immutable data, so > got no security benefit. > > The goal of the patch is to reduce the window when stuff is writeable, > so that an arbitrary write is likely to hit the time when data is read-only.
Indeed, that was my - poorly explained, I admit it - idea.
For example, that's the reason why I am remapping one page at a time in a loop, instead of doing the whole array, to limit exposure and increase randomness.
WRT the implementation, I'm sure there are bugs that need squashing.
But if I have overlooked some aspect in the overall design, I need guidance, because i still do not see what I am missing :-(
-- igor
| |