On Fri, Aug 28, 2020 at 02:16:02PM +0100, Boyan Karatotev wrote: > Pointer Authentication (PAuth) is a security feature introduced in ARMv8.3. > It introduces instructions to sign addresses and later check for potential > corruption using a second modifier value and one of a set of keys. The > signature, in the form of the Pointer Authentication Code (PAC), is stored > in some of the top unused bits of the virtual address (e.g. [54: 49] if > TBID0 is enabled and TnSZ is set to use a 48 bit VA space). A set of > controls are present to enable/disable groups of instructions (which use > certain keys) for compatibility with libraries that do not utilize the > feature. PAuth is used to verify the integrity of return addresses on the > stack with less memory than the stack canary. > > This patchset adds kselftests to verify the kernel's configuration of the > feature and its runtime behaviour. There are 7 tests which verify that: > * an authentication failure leads to a SIGSEGV > * the data/instruction instruction groups are enabled > * the generic instructions are enabled > * all 5 keys are unique for a single thread > * exec() changes all keys to new unique ones > * context switching preserves the 4 data/instruction keys > * context switching preserves the generic keys > > The tests have been verified to work on qemu without a working PAUTH > Implementation and on ARM's FVP with a full or partial PAuth > implementation. > > Note: This patchset is only verified for ARMv8.3 and there will be some > changes required for ARMv8.6. More details can be found here [1]. Once > ARMv8.6 PAuth is merged the first test in this series will required to be > updated. Nit: is it worth running checkpatch over this series? Although this is not kernel code, there are a number of formatting weirdnesses and surplus blank lines etc. that checkpatch would probably warn about. [...] Cheers ---Dave
