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From: Andrey Konovalov <andreyknvl@google.com>
To: 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
Cc: Catalin Marinas <catalin.marinas@arm.com>,
	Vincenzo Frascino <vincenzo.frascino@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Kees Cook <keescook@chromium.org>,
	Yishai Hadas <yishaih@mellanox.com>,
	Felix Kuehling <Felix.Kuehling@amd.com>,
	Alexander Deucher <Alexander.Deucher@amd.com>,
	Christian Koenig <Christian.Koenig@amd.com>,
	Mauro Carvalho Chehab <mchehab@kernel.org>,
	Jens Wiklander <jens.wiklander@linaro.org>,
	Alex Williamson <alex.williamson@redhat.com>,
	Leon Romanovsky <leon@kernel.org>,
	Luc Van Oostenryck <luc.vanoostenryck@gmail.com>,
	Dave Martin <Dave.Martin@arm.com>,
	Khalid Aziz <khalid.aziz@oracle.com>, enh <enh@google.com>,
	Jason Gunthorpe <jgg@ziepe.ca>,
	Christoph Hellwig <hch@infradead.org>,
	Dmitry Vyukov <dvyukov@google.com>,
	Kostya Serebryany <kcc@google.com>,
	Evgeniy Stepanov <eugenis@google.com>,
	Lee Smith <Lee.Smith@arm.com>,
	Ramana Radhakrishnan <Ramana.Radhakrishnan@arm.com>,
	Jacob Bramley <Jacob.Bramley@arm.com>,
	Ruben Ayrapetyan <Ruben.Ayrapetyan@arm.com>,
	Robin Murphy <robin.murphy@arm.com>,
	Kevin Brodsky <kevin.brodsky@arm.com>,
	Szabolcs Nagy <Szabolcs.Nagy@arm.com>,
	Andrey Konovalov <andreyknvl@google.com>
Subject: [PATCH v18 01/15] arm64: untag user pointers in access_ok and __uaccess_mask_ptr
Date: Mon, 24 Jun 2019 16:32:46 +0200
Message-ID: <98cbd89549395d372a4a20ab2ac536bf19d37e52.1561386715.git.andreyknvl@google.com> (raw)
In-Reply-To: <cover.1561386715.git.andreyknvl@google.com>

This patch is a part of a series that extends kernel ABI to allow to pass
tagged user pointers (with the top byte set to something else other than
0x00) as syscall arguments.

copy_from_user (and a few other similar functions) are used to copy data
from user memory into the kernel memory or vice versa. Since a user can
provided a tagged pointer to one of the syscalls that use copy_from_user,
we need to correctly handle such pointers.

Do this by untagging user pointers in access_ok and in __uaccess_mask_ptr,
before performing access validity checks.

Note, that this patch only temporarily untags the pointers to perform the
checks, but then passes them as is into the kernel internals.

Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
 arch/arm64/include/asm/uaccess.h | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
index 5a1c32260c1f..a138e3b4f717 100644
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -62,6 +62,8 @@ static inline unsigned long __range_ok(const void __user *addr, unsigned long si
 {
 	unsigned long ret, limit = current_thread_info()->addr_limit;
 
+	addr = untagged_addr(addr);
+
 	__chk_user_ptr(addr);
 	asm volatile(
 	// A + B <= C + 1 for all A,B,C, in four easy steps:
@@ -215,7 +217,8 @@ static inline void uaccess_enable_not_uao(void)
 
 /*
  * Sanitise a uaccess pointer such that it becomes NULL if above the
- * current addr_limit.
+ * current addr_limit. In case the pointer is tagged (has the top byte set),
+ * untag the pointer before checking.
  */
 #define uaccess_mask_ptr(ptr) (__typeof__(ptr))__uaccess_mask_ptr(ptr)
 static inline void __user *__uaccess_mask_ptr(const void __user *ptr)
@@ -223,10 +226,11 @@ static inline void __user *__uaccess_mask_ptr(const void __user *ptr)
 	void __user *safe_ptr;
 
 	asm volatile(
-	"	bics	xzr, %1, %2\n"
+	"	bics	xzr, %3, %2\n"
 	"	csel	%0, %1, xzr, eq\n"
 	: "=&r" (safe_ptr)
-	: "r" (ptr), "r" (current_thread_info()->addr_limit)
+	: "r" (ptr), "r" (current_thread_info()->addr_limit),
+	  "r" (untagged_addr(ptr))
 	: "cc");
 
 	csdb();
-- 
2.22.0.410.gd8fdbe21b5-goog


  reply index

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-24 14:32 [PATCH v18 00/15] arm64: untag user pointers passed to the kernel Andrey Konovalov
2019-06-24 14:32 ` Andrey Konovalov [this message]
2019-06-24 14:32 ` [PATCH v18 02/15] arm64: Introduce prctl() options to control the tagged user addresses ABI Andrey Konovalov
2019-06-24 15:04   ` Kees Cook
2019-06-24 14:32 ` [PATCH v18 03/15] lib: untag user pointers in strn*_user Andrey Konovalov
2019-06-24 14:32 ` [PATCH v18 04/15] mm: untag user pointers passed to memory syscalls Andrey Konovalov
2019-06-24 14:32 ` [PATCH v18 05/15] mm: untag user pointers in mm/gup.c Andrey Konovalov
2019-06-24 14:32 ` [PATCH v18 06/15] mm: untag user pointers in get_vaddr_frames Andrey Konovalov
2019-06-24 14:32 ` [PATCH v18 07/15] fs/namespace: untag user pointers in copy_mount_options Andrey Konovalov
2019-06-24 17:50   ` Catalin Marinas
2019-07-15 16:00     ` Andrey Konovalov
2019-07-22 16:46       ` Kees Cook
2019-06-24 14:32 ` [PATCH v18 08/15] userfaultfd: untag user pointers Andrey Konovalov
2019-06-24 17:51   ` Catalin Marinas
2019-07-15 16:00     ` Andrey Konovalov
2019-07-17 11:09     ` Mike Rapoport
2019-07-17 11:46       ` Andrey Konovalov
2019-06-24 14:32 ` [PATCH v18 09/15] drm/amdgpu: " Andrey Konovalov
2019-06-24 15:00   ` Kees Cook
2019-06-24 14:32 ` [PATCH v18 10/15] drm/radeon: untag user pointers in radeon_gem_userptr_ioctl Andrey Konovalov
2019-06-24 15:01   ` Kees Cook
2019-06-24 15:02   ` Kees Cook
2019-06-26 17:50   ` Khalid Aziz
2019-06-24 14:32 ` [PATCH v18 11/15] IB/mlx4: untag user pointers in mlx4_get_umem_mr Andrey Konovalov
2019-06-24 15:01   ` Kees Cook
2019-06-24 17:40   ` Catalin Marinas
2019-07-15 16:01     ` Andrey Konovalov
2019-07-15 18:05       ` Jason Gunthorpe
2019-07-16 10:42         ` Andrey Konovalov
2019-07-16 12:06           ` Jason Gunthorpe
2019-07-17 11:42             ` Andrey Konovalov
2019-07-17 11:44             ` Andrey Konovalov
2019-07-17 11:58               ` Jason Gunthorpe
2019-07-17 13:36                 ` Andrey Konovalov
2019-06-24 14:32 ` [PATCH v18 12/15] media/v4l2-core: untag user pointers in videobuf_dma_contig_user_get Andrey Konovalov
2019-06-24 14:32 ` [PATCH v18 13/15] tee/shm: untag user pointers in tee_shm_register Andrey Konovalov
2019-06-24 14:32 ` [PATCH v18 14/15] vfio/type1: untag user pointers in vaddr_get_pfn Andrey Konovalov
2019-06-24 14:33 ` [PATCH v18 15/15] selftests, arm64: add a selftest for passing tagged pointers to kernel Andrey Konovalov
2019-06-24 15:02   ` Kees Cook
2019-06-24 17:38   ` Catalin Marinas
2019-08-23 13:56   ` Cristian Marussi
2019-08-23 17:16     ` Andrey Konovalov
2019-08-23 17:49       ` Cristian Marussi
2019-09-04 14:52         ` Andrey Konovalov
2019-09-04 16:22           ` Cristian Marussi
2019-09-04 16:42             ` Andrey Konovalov
2019-06-26 17:18 ` [PATCH v18 00/15] arm64: untag user pointers passed to the kernel Catalin Marinas

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