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[217.140.110.172]) by mx.google.com with ESMTP id c55si8756269edc.323.2019.06.10.11.53.38 for ; Mon, 10 Jun 2019 11:53:38 -0700 (PDT) Received-SPF: pass (google.com: domain of catalin.marinas@arm.com designates 217.140.110.172 as permitted sender) client-ip=217.140.110.172; Authentication-Results: mx.google.com; spf=pass (google.com: domain of catalin.marinas@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=catalin.marinas@arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 822ED337; Mon, 10 Jun 2019 11:53:37 -0700 (PDT) Received: from mbp (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 631F83F246; Mon, 10 Jun 2019 11:53:32 -0700 (PDT) Date: Mon, 10 Jun 2019 19:53:30 +0100 From: Catalin Marinas To: Kees Cook Cc: Andrey Konovalov , linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-rdma@vger.kernel.org, linux-media@vger.kernel.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org, Vincenzo Frascino , Will Deacon , Mark Rutland , Andrew Morton , Greg Kroah-Hartman , Yishai Hadas , Felix Kuehling , Alexander Deucher , Christian Koenig , Mauro Carvalho Chehab , Jens Wiklander , Alex Williamson , Leon Romanovsky , Luc Van Oostenryck , Dave Martin , Khalid Aziz , enh , Jason Gunthorpe , Christoph Hellwig , Dmitry Vyukov , Kostya Serebryany , Evgeniy Stepanov , Lee Smith , Ramana Radhakrishnan , Jacob Bramley , Ruben Ayrapetyan , Robin Murphy , Kevin Brodsky , Szabolcs Nagy Subject: Re: [PATCH v16 02/16] arm64: untag user pointers in access_ok and __uaccess_mask_ptr Message-ID: <20190610185329.xhjawzfy4uddrkrj@mbp> References: <4327b260fb17c4776a1e3c844f388e4948cfb747.1559580831.git.andreyknvl@google.com> <20190610175326.GC25803@arrakis.emea.arm.com> <201906101106.3CA50745E3@keescook> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201906101106.3CA50745E3@keescook> User-Agent: NeoMutt/20170113 (1.7.2) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Jun 10, 2019 at 11:07:03AM -0700, Kees Cook 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) [...] > > diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c > > index 3767fb21a5b8..fd191c5b92aa 100644 > > --- a/arch/arm64/kernel/process.c > > +++ b/arch/arm64/kernel/process.c > > @@ -552,3 +552,18 @@ void arch_setup_new_exec(void) > > > > ptrauth_thread_init_user(current); > > } > > + > > +/* > > + * Enable the relaxed ABI allowing tagged user addresses into the kernel. > > + */ > > +int untagged_uaddr_set_mode(unsigned long arg) > > +{ > > + if (is_compat_task()) > > + return -ENOTSUPP; > > + if (arg) > > + return -EINVAL; > > + > > + set_thread_flag(TIF_UNTAGGED_UADDR); > > + > > + return 0; > > +} > > I think this should be paired with a flag clearing in copy_thread(), > yes? (i.e. each binary needs to opt in) It indeed needs clearing though not in copy_thread() as that's used on clone/fork but rather in flush_thread(), called on the execve() path. And a note to myself: I think PR_UNTAGGED_ADDR (not UADDR) looks better in a uapi header, the user doesn't differentiate between uaddr and kaddr. -- Catalin