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From: Catalin Marinas <catalin.marinas@arm.com>
To: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Cc: Mark Rutland <Mark.Rutland@arm.com>,
	Kate Stewart <kstewart@linuxfoundation.org>,
	"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
	Will Deacon <Will.Deacon@arm.com>,
	Kostya Serebryany <kcc@google.com>,
	"linux-kselftest@vger.kernel.org"
	<linux-kselftest@vger.kernel.org>,
	Chintan Pandya <cpandya@codeaurora.org>,
	Shuah Khan <shuah@kernel.org>, Ingo Molnar <mingo@kernel.org>,
	"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
	Jacob Bramley <Jacob.Bramley@arm.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	Evgeniy Stepanov <eugenis@google.com>,
	Kees Cook <keescook@chromium.org>,
	Ruben Ayrapetyan <Ruben.Ayrapetyan@arm.com>,
	Andrey Konovalov <andreyknvl@google.com>,
	Lee Smith <Lee.Smith@arm.com>, Al Viro <viro@zeniv.linux.org.uk>,
	nd <nd@arm.com>, Linux ARM <linux-arm-kernel@lists.infradead.org>,
	Linux Memory Management List <linux-mm@kvack.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Ramana Radhakrishnan <ramana.radhakrishnan@arm.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Robin Murphy <Robin.Murphy@arm.com>,
	"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Subject: Re: [PATCH v4 0/7] arm64: untag user pointers passed to the kernel
Date: Thu, 28 Jun 2018 11:27:42 +0100	[thread overview]
Message-ID: <20180628102741.vk6vphfinlj3lvhv@armageddon.cambridge.arm.com> (raw)
In-Reply-To: <20180628061758.j6bytsaj5jk4aocg@ltop.local>

On Thu, Jun 28, 2018 at 08:17:59AM +0200, Luc Van Oostenryck wrote:
> On Wed, Jun 27, 2018 at 06:17:58PM +0100, Catalin Marinas wrote:
> > sparse is indeed an option. The current implementation doesn't warn on
> > an explicit cast from (void __user *) to (unsigned long) since that's a
> > valid thing in the kernel. I couldn't figure out if there's any other
> > __attribute__ that could be used to warn of such conversion.
> 
> sparse doesn't have such attribute but would an new option that would warn
> on such cast be a solution for your case?

I can't tell for sure whether such sparse option would be the full
solution but detecting explicit __user pointer casts to long is a good
starting point. So far this patchset pretty much relies on detecting
a syscall failure and trying to figure out why, patching the kernel. It
doesn't really scale.

As a side note, we have cases in the user-kernel ABI where the user
address type is "unsigned long": mmap() and friends. My feedback on an
early version of this patchset was to always require untagged pointers
coming from user space on such syscalls, so no need for explicit
untagging.

-- 
Catalin

  reply	other threads:[~2018-06-28 10:27 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-20 15:24 [PATCH v4 0/7] arm64: untag user pointers passed to the kernel Andrey Konovalov
2018-06-20 15:24 ` [PATCH v4 1/7] arm64: add type casts to untagged_addr macro Andrey Konovalov
2018-06-20 15:24 ` [PATCH v4 2/7] uaccess: add untagged_addr definition for other arches Andrey Konovalov
2018-06-20 15:24 ` [PATCH v4 3/7] arm64: untag user addresses in access_ok and __uaccess_mask_ptr Andrey Konovalov
2018-06-20 15:24 ` [PATCH v4 4/7] mm, arm64: untag user addresses in mm/gup.c Andrey Konovalov
2018-06-20 15:24 ` [PATCH v4 5/7] lib, arm64: untag addrs passed to strncpy_from_user and strnlen_user Andrey Konovalov
2018-06-20 15:24 ` [PATCH v4 6/7] arm64: update Documentation/arm64/tagged-pointers.txt Andrey Konovalov
2018-06-20 15:24 ` [PATCH v4 7/7] selftests, arm64: add a selftest for passing tagged pointers to kernel Andrey Konovalov
2018-06-26 12:47 ` [PATCH v4 0/7] arm64: untag user pointers passed to the kernel Andrey Konovalov
2018-06-26 17:29   ` Catalin Marinas
2018-06-27 15:05     ` Andrey Konovalov
2018-06-27 15:08       ` Ramana Radhakrishnan
2018-06-27 17:17         ` Catalin Marinas
2018-06-28  6:17           ` Luc Van Oostenryck
2018-06-28 10:27             ` Catalin Marinas [this message]
2018-06-28 10:46               ` Luc Van Oostenryck
2018-06-28 14:48                 ` Catalin Marinas
2018-06-28 15:28                   ` Luc Van Oostenryck
2018-06-29 15:27                   ` David Laight
2018-06-28 23:21               ` [PATCH] sparse: stricter warning for explicit cast to ulong Luc Van Oostenryck
2018-06-28 19:30       ` [PATCH v4 0/7] arm64: untag user pointers passed to the kernel Andrey Konovalov
2018-06-29 15:19         ` Andrey Konovalov
2018-06-29 15:20           ` Andrey Konovalov
2018-07-16 11:25         ` Andrey Konovalov
2018-07-31 13:23           ` Andrey Konovalov
2018-08-01 17:42           ` Catalin Marinas
2018-08-02 15:00             ` Andrey Konovalov
2018-08-03 14:59               ` Andrey Konovalov
2018-08-03 15:09                 ` Greg Kroah-Hartman
2018-08-03 16:43                   ` Matthew Wilcox
2018-08-03 16:54                     ` Andrey Konovalov
2018-08-06 19:12                   ` Luc Van Oostenryck

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