On Tue, Jun 11, 2019 at 07:09:46PM +0200, Andrey Konovalov wrote: > On Tue, Jun 11, 2019 at 4:57 PM Catalin Marinas <catalin.marinas@xxxxxxx> wrote: > > > > On Mon, Jun 10, 2019 at 06:53:27PM +0100, Catalin Marinas wrote: > > > On Mon, Jun 03, 2019 at 06:55:04PM +0200, Andrey Konovalov wrote: > > > > diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h > > > > index e5d5f31c6d36..9164ecb5feca 100644 > > > > --- a/arch/arm64/include/asm/uaccess.h > > > > +++ b/arch/arm64/include/asm/uaccess.h > > > > @@ -94,7 +94,7 @@ static inline unsigned long __range_ok(const void __user *addr, unsigned long si > > > > return ret; > > > > } > > > > > > > > -#define access_ok(addr, size) __range_ok(addr, size) > > > > +#define access_ok(addr, size) __range_ok(untagged_addr(addr), size) > > > > > > I'm going to propose an opt-in method here (RFC for now). We can't have > > > a check in untagged_addr() since this is already used throughout the > > > kernel for both user and kernel addresses (khwasan) but we can add one > > > in __range_ok(). The same prctl() option will be used for controlling > > > the precise/imprecise mode of MTE later on. We can use a TIF_ flag here > > > assuming that this will be called early on and any cloned thread will > > > inherit this. > > > > Updated patch, inlining it below. Once we agreed on the approach, I > > think Andrey can insert in in this series, probably after patch 2. The > > differences from the one I posted yesterday: > > > > - renamed PR_* macros together with get/set variants and the possibility > > to disable the relaxed ABI > > > > - sysctl option - /proc/sys/abi/tagged_addr to disable the ABI globally > > (just the prctl() opt-in, tasks already using it won't be affected) > > > > And, of course, it needs more testing. > > Sure, I'll add it to the series. > > Should I drop access_ok() change from my patch, since yours just reverts it? Not necessary, your patch just relaxes the ABI for all apps, mine tightens it. You could instead move the untagging to __range_ok() and rebase my patch accordingly. -- Catalin
