On Wed, Aug 29, 2018 at 03:59:36PM -0700, Rick Edgecombe wrote: > Hi, > > This is v4 of the "KASLR feature to randomize each loadable module" patchset. > The purpose is to increase the randomization and also to make the modules > randomized in relation to each other instead of just the base, so that if one > module leaks the location of the others can't be inferred. It is enabled for > x86_64 for now. > > V4 is a few small fixes. I humbly think this is in pretty good shape at this > point, unless anyone has any comments. The only other big change I was > considering was moving the new randomization algorithm into vmalloc so it could > be re-used for other architectures or possibly other vmalloc usages. > > A few words on how this was tested - As previously mentioned, the entropy > estimates were done using extracted module text sizes from the in-tree modules. > These were also used to run 100,000's of simulated module allocations by calling > module_alloc from a test module, including testing until allocation failure. The > simulations kept track of every allocation address to make sure there were no > collisions, and verified memory was actually mapped. > > In addition the __vmalloc_node_try_addr function has a suite of unit tests that > verify for a bunch of edge cases that it: > - Allows for allocations when it should > - Reports the right error code if it collides with a lazy-free area or real > allocation > - Verifies it frees a lazy free area when it should > > These synthetic tests were also how the performance metrics were gathered. > > Changes for V4: > - Fix issue caused by KASAN, kmemleak being provided different allocation > lengths (padding). > - Avoid kmalloc until sure its needed in __vmalloc_node_try_addr. > - Fix for debug file hang when the last VA is a lazy purge area > - Fixed issues reported by 0-day build system. > > Changes for V3: > - Code cleanup based on internal feedback. (thanks to Dave Hansen and Andriy > Shevchenko) > - Slight refactor of existing algorithm to more cleanly live along side new > one. > - BPF synthetic benchmark I don't see this benchmark in this patch set. Could you prepare it as a test in tools/testing/selftests/bpf/ ? so we can double check what is being tested and run it regularly like we do for all other tests in there.
