From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:60302 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1423834AbeBOPk6 (ORCPT ); Thu, 15 Feb 2018 10:40:58 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Robin Murphy , Will Deacon , Catalin Marinas Subject: [PATCH 4.15 055/202] [Variant 1/Spectre-v1] arm64: uaccess: Dont bother eliding access_ok checks in __{get, put}_user Date: Thu, 15 Feb 2018 16:15:55 +0100 Message-Id: <20180215151716.130434875@linuxfoundation.org> In-Reply-To: <20180215151712.768794354@linuxfoundation.org> References: <20180215151712.768794354@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Will Deacon Commit 84624087dd7e upstream. access_ok isn't an expensive operation once the addr_limit for the current thread has been loaded into the cache. Given that the initial access_ok check preceding a sequence of __{get,put}_user operations will take the brunt of the miss, we can make the __* variants identical to the full-fat versions, which brings with it the benefits of address masking. The likely cost in these sequences will be from toggling PAN/UAO, which we can address later by implementing the *_unsafe versions. Reviewed-by: Robin Murphy Signed-off-by: Will Deacon Signed-off-by: Catalin Marinas Signed-off-by: Greg Kroah-Hartman --- arch/arm64/include/asm/uaccess.h | 54 +++++++++++++++++++++++---------------- 1 file changed, 32 insertions(+), 22 deletions(-) --- a/arch/arm64/include/asm/uaccess.h +++ b/arch/arm64/include/asm/uaccess.h @@ -294,28 +294,33 @@ do { \ (x) = (__force __typeof__(*(ptr)))__gu_val; \ } while (0) -#define __get_user(x, ptr) \ +#define __get_user_check(x, ptr, err) \ ({ \ - int __gu_err = 0; \ - __get_user_err((x), (ptr), __gu_err); \ - __gu_err; \ + __typeof__(*(ptr)) __user *__p = (ptr); \ + might_fault(); \ + if (access_ok(VERIFY_READ, __p, sizeof(*__p))) { \ + __p = uaccess_mask_ptr(__p); \ + __get_user_err((x), __p, (err)); \ + } else { \ + (x) = 0; (err) = -EFAULT; \ + } \ }) #define __get_user_error(x, ptr, err) \ ({ \ - __get_user_err((x), (ptr), (err)); \ + __get_user_check((x), (ptr), (err)); \ (void)0; \ }) -#define get_user(x, ptr) \ +#define __get_user(x, ptr) \ ({ \ - __typeof__(*(ptr)) __user *__p = (ptr); \ - might_fault(); \ - access_ok(VERIFY_READ, __p, sizeof(*__p)) ? \ - __p = uaccess_mask_ptr(__p), __get_user((x), __p) : \ - ((x) = 0, -EFAULT); \ + int __gu_err = 0; \ + __get_user_check((x), (ptr), __gu_err); \ + __gu_err; \ }) +#define get_user __get_user + #define __put_user_asm(instr, alt_instr, reg, x, addr, err, feature) \ asm volatile( \ "1:"ALTERNATIVE(instr " " reg "1, [%2]\n", \ @@ -358,28 +363,33 @@ do { \ uaccess_disable_not_uao(); \ } while (0) -#define __put_user(x, ptr) \ +#define __put_user_check(x, ptr, err) \ ({ \ - int __pu_err = 0; \ - __put_user_err((x), (ptr), __pu_err); \ - __pu_err; \ + __typeof__(*(ptr)) __user *__p = (ptr); \ + might_fault(); \ + if (access_ok(VERIFY_WRITE, __p, sizeof(*__p))) { \ + __p = uaccess_mask_ptr(__p); \ + __put_user_err((x), __p, (err)); \ + } else { \ + (err) = -EFAULT; \ + } \ }) #define __put_user_error(x, ptr, err) \ ({ \ - __put_user_err((x), (ptr), (err)); \ + __put_user_check((x), (ptr), (err)); \ (void)0; \ }) -#define put_user(x, ptr) \ +#define __put_user(x, ptr) \ ({ \ - __typeof__(*(ptr)) __user *__p = (ptr); \ - might_fault(); \ - access_ok(VERIFY_WRITE, __p, sizeof(*__p)) ? \ - __p = uaccess_mask_ptr(__p), __put_user((x), __p) : \ - -EFAULT; \ + int __pu_err = 0; \ + __put_user_check((x), (ptr), __pu_err); \ + __pu_err; \ }) +#define put_user __put_user + extern unsigned long __must_check __arch_copy_from_user(void *to, const void __user *from, unsigned long n); #define raw_copy_from_user __arch_copy_from_user extern unsigned long __must_check __arch_copy_to_user(void __user *to, const void *from, unsigned long n);