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From: David Long <dave.long@linaro.org>
To: stable@vger.kernel.org,
	Russell King - ARM Linux <linux@armlinux.org.uk>,
	Florian Fainelli <f.fainelli@gmail.com>,
	Julien Thierry <julien.thierry@arm.com>,
	Tony Lindgren <tony@atomide.com>,
	Marc Zyngier <marc.zyngier@arm.com>,
	Greg KH <gregkh@linuxfoundation.org>,
	Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>,
	Mark Brown <broonie@kernel.org>,
	linux-kernel@vger.kernel.org
Subject: [PATCH 4.19 08/17] ARM: 8796/1: spectre-v1,v1.1: provide helpers for address sanitization
Date: Wed, 13 Feb 2019 16:32:14 -0500	[thread overview]
Message-ID: <20190213213223.916-9-dave.long@linaro.org> (raw)
In-Reply-To: <20190213213223.916-1-dave.long@linaro.org>

From: Julien Thierry <julien.thierry@arm.com>

Commit afaf6838f4bc896a711180b702b388b8cfa638fc upstream.

Introduce C and asm helpers to sanitize user address, taking the
address range they target into account.

Use asm helper for existing sanitization in __copy_from_user().

Signed-off-by: Julien Thierry <julien.thierry@arm.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David A. Long <dave.long@linaro.org>
---
 arch/arm/include/asm/assembler.h | 11 +++++++++++
 arch/arm/include/asm/uaccess.h   | 26 ++++++++++++++++++++++++++
 arch/arm/lib/copy_from_user.S    |  6 +-----
 3 files changed, 38 insertions(+), 5 deletions(-)

diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h
index b17ee03d280b..88286dd483ff 100644
--- a/arch/arm/include/asm/assembler.h
+++ b/arch/arm/include/asm/assembler.h
@@ -467,6 +467,17 @@ THUMB(	orr	\reg , \reg , #PSR_T_BIT	)
 #endif
 	.endm
 
+	.macro uaccess_mask_range_ptr, addr:req, size:req, limit:req, tmp:req
+#ifdef CONFIG_CPU_SPECTRE
+	sub	\tmp, \limit, #1
+	subs	\tmp, \tmp, \addr	@ tmp = limit - 1 - addr
+	addhs	\tmp, \tmp, #1		@ if (tmp >= 0) {
+	subhss	\tmp, \tmp, \size	@ tmp = limit - (addr + size) }
+	movlo	\addr, #0		@ if (tmp < 0) addr = NULL
+	csdb
+#endif
+	.endm
+
 	.macro	uaccess_disable, tmp, isb=1
 #ifdef CONFIG_CPU_SW_DOMAIN_PAN
 	/*
diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h
index 1191e7da8fab..c136eef8f690 100644
--- a/arch/arm/include/asm/uaccess.h
+++ b/arch/arm/include/asm/uaccess.h
@@ -99,6 +99,32 @@ static inline void set_fs(mm_segment_t fs)
 #define __inttype(x) \
 	__typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
 
+/*
+ * Sanitise a uaccess pointer such that it becomes NULL if addr+size
+ * is above the current addr_limit.
+ */
+#define uaccess_mask_range_ptr(ptr, size)			\
+	((__typeof__(ptr))__uaccess_mask_range_ptr(ptr, size))
+static inline void __user *__uaccess_mask_range_ptr(const void __user *ptr,
+						    size_t size)
+{
+	void __user *safe_ptr = (void __user *)ptr;
+	unsigned long tmp;
+
+	asm volatile(
+	"	sub	%1, %3, #1\n"
+	"	subs	%1, %1, %0\n"
+	"	addhs	%1, %1, #1\n"
+	"	subhss	%1, %1, %2\n"
+	"	movlo	%0, #0\n"
+	: "+r" (safe_ptr), "=&r" (tmp)
+	: "r" (size), "r" (current_thread_info()->addr_limit)
+	: "cc");
+
+	csdb();
+	return safe_ptr;
+}
+
 /*
  * Single-value transfer routines.  They automatically use the right
  * size if we just have the right pointer type.  Note that the functions
diff --git a/arch/arm/lib/copy_from_user.S b/arch/arm/lib/copy_from_user.S
index a826df3d3814..6709a8d33963 100644
--- a/arch/arm/lib/copy_from_user.S
+++ b/arch/arm/lib/copy_from_user.S
@@ -93,11 +93,7 @@ ENTRY(arm_copy_from_user)
 #ifdef CONFIG_CPU_SPECTRE
 	get_thread_info r3
 	ldr	r3, [r3, #TI_ADDR_LIMIT]
-	adds	ip, r1, r2	@ ip=addr+size
-	sub	r3, r3, #1	@ addr_limit - 1
-	cmpcc	ip, r3		@ if (addr+size > addr_limit - 1)
-	movcs	r1, #0		@ addr = NULL
-	csdb
+	uaccess_mask_range_ptr r1, r2, r3, ip
 #endif
 
 #include "copy_template.S"
-- 
2.17.1


  parent reply	other threads:[~2019-02-13 21:32 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-13 21:32 [PATCH 4.19 00/17] V4.19 backport of more 32-bit arm spectre patches David Long
2019-02-13 21:32 ` [PATCH 4.19 01/17] ARM: 8789/1: signal: copy registers using __copy_to_user() David Long
2019-02-13 21:32 ` [PATCH 4.19 02/17] ARM: 8790/1: signal: always use __copy_to_user to save iwmmxt context David Long
2019-02-13 21:32 ` [PATCH 4.19 03/17] ARM: 8791/1: vfp: use __copy_to_user() when saving VFP state David Long
2019-02-13 21:32 ` [PATCH 4.19 04/17] ARM: 8792/1: oabi-compat: copy oabi events using __copy_to_user() David Long
2019-02-13 21:32 ` [PATCH 4.19 05/17] ARM: 8793/1: signal: replace __put_user_error with __put_user David Long
2019-02-13 21:32 ` [PATCH 4.19 06/17] ARM: 8794/1: uaccess: Prevent speculative use of the current addr_limit David Long
2019-02-13 21:32 ` [PATCH 4.19 07/17] ARM: 8795/1: spectre-v1.1: use put_user() for __put_user() David Long
2019-02-13 21:32 ` David Long [this message]
2019-02-13 21:32 ` [PATCH 4.19 09/17] ARM: 8797/1: spectre-v1.1: harden __copy_to_user David Long
2019-02-13 21:32 ` [PATCH 4.19 10/17] ARM: 8810/1: vfp: Fix wrong assignement to ufp_exc David Long
2019-02-13 21:32 ` [PATCH 4.19 11/17] ARM: make lookup_processor_type() non-__init David Long
2019-02-13 21:32 ` [PATCH 4.19 12/17] ARM: split out processor lookup David Long
2019-02-13 21:32 ` [PATCH 4.19 13/17] ARM: clean up per-processor check_bugs method call David Long
2019-02-13 21:32 ` [PATCH 4.19 14/17] ARM: add PROC_VTABLE and PROC_TABLE macros David Long
2019-02-13 21:32 ` [PATCH 4.19 15/17] ARM: spectre-v2: per-CPU vtables to work around big.Little systems David Long
2019-02-13 21:32 ` [PATCH 4.19 16/17] ARM: ensure that processor vtables is not lost after boot David Long
2019-02-13 21:32 ` [PATCH 4.19 17/17] ARM: fix the cockup in the previous patch David Long
2019-02-14  8:50 ` [PATCH 4.19 00/17] V4.19 backport of more 32-bit arm spectre patches Julien Thierry
2019-02-17 19:20 ` Sasha Levin

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