From patchwork Thu Nov 19 23:57:42 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Axtens X-Patchwork-Id: 329103 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-18.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 751ACC388F9 for ; Thu, 19 Nov 2020 23:58:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 230B422249 for ; Thu, 19 Nov 2020 23:58:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=axtens.net header.i=@axtens.net header.b="lDbQpZ9N" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726983AbgKSX6O (ORCPT ); Thu, 19 Nov 2020 18:58:14 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38872 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727470AbgKSX6N (ORCPT ); Thu, 19 Nov 2020 18:58:13 -0500 Received: from mail-pg1-x542.google.com (mail-pg1-x542.google.com [IPv6:2607:f8b0:4864:20::542]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 66F3EC0613CF for ; Thu, 19 Nov 2020 15:58:13 -0800 (PST) Received: by mail-pg1-x542.google.com with SMTP id t37so5629055pga.7 for ; Thu, 19 Nov 2020 15:58:13 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=axtens.net; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=WRTxiPO0ok1vI94GoN4Oz3ukryy2f2qIAh0OFz41j/M=; b=lDbQpZ9NOs4B4Kwzvc6vYlpu3+u2iBoVMZlr0irTqGe/3zajN0eB9ZSQAyhmCw9kMJ XxJo+i/YV9g6PPqbNlbjzvmgZzkVqoxVrbXW9q5gbJ9iTElj4iR32mlE17yMUz3b6Hrx dl5eYp5HvcMy8PFFDxCTyMzsLapyHnXq5cG8c= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=WRTxiPO0ok1vI94GoN4Oz3ukryy2f2qIAh0OFz41j/M=; b=p4phWxu0Uph6/Ph6R2VY0Li8GRGoMG4j44+ZIypvBiB32xD5CqOAcDkYAv5/Lj/Hb3 Bgr17g5EqnuvmorrwGO7MGzQKQrC32QYKmkwVgk2uLJDlnfrCxtJr5vBGqGjiQaSD5Na DeBD6F3y90njweWnR1QOHa9tf/8IN1S1dHEaoLVAjsYUtVW4eZkzKm/vEJZScHsh3qnw U7lxpy5aWzy9ba1rBpcwFDu+Asj3fx7C+TcURMrXTZFuF/UgzW2xrxhxgonALnR/ntzd 1ms1lx4gSDri+l6eFWAspLRrfN9V/BTKVpPOc8PJfkH2zaR/FkdoSgTTCPJH067BTwI5 4lrQ== X-Gm-Message-State: AOAM532fY7j9bMK5kHbX03eV2g1Y3SFBzJlnMt0P4whYMWu0acQR6gci llYLll+7rUXphJJy8S0muWwAmz83+dPSyg== X-Google-Smtp-Source: ABdhPJwax8n3Tgj0lU40jYBIp/Jf+ZCnOxt1Z5kPkMFYPMfQr3ofWXdxNBd1WnfvQtxGxYVkHPqaqA== X-Received: by 2002:a65:6649:: with SMTP id z9mr14368753pgv.156.1605830292776; Thu, 19 Nov 2020 15:58:12 -0800 (PST) Received: from localhost (2001-44b8-1113-6700-4d44-522c-3789-8f33.static.ipv6.internode.on.net. [2001:44b8:1113:6700:4d44:522c:3789:8f33]) by smtp.gmail.com with ESMTPSA id x2sm1176706pfp.13.2020.11.19.15.58.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 19 Nov 2020 15:58:12 -0800 (PST) From: Daniel Axtens To: stable@vger.kernel.org Cc: dja@axtens.net Subject: [PATCH 4.9 7/8] powerpc/uaccess: Evaluate macro arguments once, before user access is allowed Date: Fri, 20 Nov 2020 10:57:42 +1100 Message-Id: <20201119235743.373635-8-dja@axtens.net> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20201119235743.373635-1-dja@axtens.net> References: <20201119235743.373635-1-dja@axtens.net> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Nicholas Piggin commit d02f6b7dab8228487268298ea1f21081c0b4b3eb upstream. get/put_user() can be called with nontrivial arguments. fs/proc/page.c has a good example: if (put_user(stable_page_flags(ppage), out)) { stable_page_flags() is quite a lot of code, including spin locks in the page allocator. Ensure these arguments are evaluated before user access is allowed. This improves security by reducing code with access to userspace, but it also fixes a PREEMPT bug with KUAP on powerpc/64s: stable_page_flags() is currently called with AMR set to allow writes, it ends up calling spin_unlock(), which can call preempt_schedule. But the task switch code can not be called with AMR set (it relies on interrupts saving the register), so this blows up. It's fine if the code inside allow_user_access() is preemptible, because a timer or IPI will save the AMR, but it's not okay to explicitly cause a reschedule. Fixes: de78a9c42a79 ("powerpc: Add a framework for Kernel Userspace Access Protection") Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20200407041245.600651-1-npiggin@gmail.com Signed-off-by: Daniel Axtens --- arch/powerpc/include/asm/uaccess.h | 49 +++++++++++++++++++++--------- 1 file changed, 35 insertions(+), 14 deletions(-) diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h index 5fc6a9f410f2..fde865a4e2cb 100644 --- a/arch/powerpc/include/asm/uaccess.h +++ b/arch/powerpc/include/asm/uaccess.h @@ -190,13 +190,17 @@ do { \ ({ \ long __pu_err; \ __typeof__(*(ptr)) __user *__pu_addr = (ptr); \ + __typeof__(*(ptr)) __pu_val = (x); \ + __typeof__(size) __pu_size = (size); \ + \ if (!is_kernel_addr((unsigned long)__pu_addr)) \ might_fault(); \ - __chk_user_ptr(ptr); \ + __chk_user_ptr(__pu_addr); \ if (do_allow) \ - __put_user_size((x), __pu_addr, (size), __pu_err); \ + __put_user_size(__pu_val, __pu_addr, __pu_size, __pu_err); \ else \ - __put_user_size_allowed((x), __pu_addr, (size), __pu_err); \ + __put_user_size_allowed(__pu_val, __pu_addr, __pu_size, __pu_err); \ + \ __pu_err; \ }) @@ -204,9 +208,13 @@ do { \ ({ \ long __pu_err = -EFAULT; \ __typeof__(*(ptr)) __user *__pu_addr = (ptr); \ + __typeof__(*(ptr)) __pu_val = (x); \ + __typeof__(size) __pu_size = (size); \ + \ might_fault(); \ - if (access_ok(VERIFY_WRITE, __pu_addr, size)) \ - __put_user_size((x), __pu_addr, (size), __pu_err); \ + if (access_ok(VERIFY_WRITE, __pu_addr, __pu_size)) \ + __put_user_size(__pu_val, __pu_addr, __pu_size, __pu_err); \ + \ __pu_err; \ }) @@ -214,8 +222,12 @@ do { \ ({ \ long __pu_err; \ __typeof__(*(ptr)) __user *__pu_addr = (ptr); \ - __chk_user_ptr(ptr); \ - __put_user_size((x), __pu_addr, (size), __pu_err); \ + __typeof__(*(ptr)) __pu_val = (x); \ + __typeof__(size) __pu_size = (size); \ + \ + __chk_user_ptr(__pu_addr); \ + __put_user_size(__pu_val, __pu_addr, __pu_size, __pu_err); \ + \ __pu_err; \ }) @@ -289,15 +301,18 @@ do { \ long __gu_err; \ unsigned long __gu_val; \ __typeof__(*(ptr)) __user *__gu_addr = (ptr); \ - __chk_user_ptr(ptr); \ + __typeof__(size) __gu_size = (size); \ + \ + __chk_user_ptr(__gu_addr); \ if (!is_kernel_addr((unsigned long)__gu_addr)) \ might_fault(); \ barrier_nospec(); \ if (do_allow) \ - __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \ + __get_user_size(__gu_val, __gu_addr, __gu_size, __gu_err); \ else \ - __get_user_size_allowed(__gu_val, __gu_addr, (size), __gu_err); \ + __get_user_size_allowed(__gu_val, __gu_addr, __gu_size, __gu_err); \ (x) = (__typeof__(*(ptr)))__gu_val; \ + \ __gu_err; \ }) @@ -306,12 +321,15 @@ do { \ long __gu_err = -EFAULT; \ unsigned long __gu_val = 0; \ __typeof__(*(ptr)) __user *__gu_addr = (ptr); \ + __typeof__(size) __gu_size = (size); \ + \ might_fault(); \ - if (access_ok(VERIFY_READ, __gu_addr, (size))) { \ + if (access_ok(VERIFY_READ, __gu_addr, __gu_size)) { \ barrier_nospec(); \ - __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \ + __get_user_size(__gu_val, __gu_addr, __gu_size, __gu_err); \ } \ (x) = (__force __typeof__(*(ptr)))__gu_val; \ + \ __gu_err; \ }) @@ -320,10 +338,13 @@ do { \ long __gu_err; \ unsigned long __gu_val; \ __typeof__(*(ptr)) __user *__gu_addr = (ptr); \ - __chk_user_ptr(ptr); \ + __typeof__(size) __gu_size = (size); \ + \ + __chk_user_ptr(__gu_addr); \ barrier_nospec(); \ - __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \ + __get_user_size(__gu_val, __gu_addr, __gu_size, __gu_err); \ (x) = (__force __typeof__(*(ptr)))__gu_val; \ + \ __gu_err; \ })