From mboxrd@z Thu Jan 1 00:00:00 1970 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=-12.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable 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 8FB62C43461 for ; Fri, 11 Sep 2020 13:36:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4F8A822273 for ; Fri, 11 Sep 2020 13:36:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1599831379; bh=GcPcT6ETLYMF7heGJRJWA/mT7h2gNr1A77XOoaOPukc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Ev7ippy0h5oxDKtuP91+gEXjCG5+DY8ZI/fTz2gcAqz4yWz12hXfB5Z0W2IxtQ4Zy ZGhCGRCXpYRDDo/ePsBdUUhv9dff7MatGIliHPLKFiWA7jKA7aoUXIrq2mllTxzaq7 bVAQhDMxjIt6yWd1UNaV8SUfBwkKhd0dVBTMgW88= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726149AbgIKNgM (ORCPT ); Fri, 11 Sep 2020 09:36:12 -0400 Received: from mail.kernel.org ([198.145.29.99]:52822 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726211AbgIKNFo (ORCPT ); Fri, 11 Sep 2020 09:05:44 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D471C22227; Fri, 11 Sep 2020 12:58:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1599829092; bh=GcPcT6ETLYMF7heGJRJWA/mT7h2gNr1A77XOoaOPukc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=R9ptLvq5yYijeW301GE9A/H9IhUcVAKebkI1l9UK+y2PZE8AahsNooj+jcR6AiYJz vchCqonEKiWi5oCvWX9Zo2seufmExIzRXCG/+72qA53vRpGh8M3D9AuH/QO5t8Mr2v 55C34kIvuDpTMyBoWDrMZXLeMzxV0vU3IoZH4xUM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Daniel Borkmann , Alexei Starovoitov , Andrii Nakryiko , Masami Hiramatsu , Sasha Levin Subject: [PATCH 4.9 34/71] uaccess: Add non-pagefault user-space write function Date: Fri, 11 Sep 2020 14:46:18 +0200 Message-Id: <20200911122506.630411755@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200911122504.928931589@linuxfoundation.org> References: <20200911122504.928931589@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Daniel Borkmann [ Upstream commit 1d1585ca0f48fe7ed95c3571f3e4a82b2b5045dc ] Commit 3d7081822f7f ("uaccess: Add non-pagefault user-space read functions") missed to add probe write function, therefore factor out a probe_write_common() helper with most logic of probe_kernel_write() except setting KERNEL_DS, and add a new probe_user_write() helper so it can be used from BPF side. Again, on some archs, the user address space and kernel address space can co-exist and be overlapping, so in such case, setting KERNEL_DS would mean that the given address is treated as being in kernel address space. Signed-off-by: Daniel Borkmann Signed-off-by: Alexei Starovoitov Acked-by: Andrii Nakryiko Cc: Masami Hiramatsu Link: https://lore.kernel.org/bpf/9df2542e68141bfa3addde631441ee45503856a8.1572649915.git.daniel@iogearbox.net Signed-off-by: Sasha Levin --- include/linux/uaccess.h | 12 +++++++++++ mm/maccess.c | 45 +++++++++++++++++++++++++++++++++++++---- 2 files changed, 53 insertions(+), 4 deletions(-) diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h index 6d27d58ca4e04..cc5ba47062e87 100644 --- a/include/linux/uaccess.h +++ b/include/linux/uaccess.h @@ -113,6 +113,18 @@ extern long probe_user_read(void *dst, const void __user *src, size_t size); extern long notrace probe_kernel_write(void *dst, const void *src, size_t size); extern long notrace __probe_kernel_write(void *dst, const void *src, size_t size); +/* + * probe_user_write(): safely attempt to write to a location in user space + * @dst: address to write to + * @src: pointer to the data that shall be written + * @size: size of the data chunk + * + * Safely write to address @dst from the buffer at @src. If a kernel fault + * happens, handle that and return -EFAULT. + */ +extern long notrace probe_user_write(void __user *dst, const void *src, size_t size); +extern long notrace __probe_user_write(void __user *dst, const void *src, size_t size); + extern long strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count); extern long strncpy_from_unsafe_user(char *dst, const void __user *unsafe_addr, long count); diff --git a/mm/maccess.c b/mm/maccess.c index 5ebf9a3ca3674..03ea550f5a743 100644 --- a/mm/maccess.c +++ b/mm/maccess.c @@ -17,6 +17,18 @@ probe_read_common(void *dst, const void __user *src, size_t size) return ret ? -EFAULT : 0; } +static __always_inline long +probe_write_common(void __user *dst, const void *src, size_t size) +{ + long ret; + + pagefault_disable(); + ret = __copy_to_user_inatomic(dst, src, size); + pagefault_enable(); + + return ret ? -EFAULT : 0; +} + /** * probe_kernel_read(): safely attempt to read from a kernel-space location * @dst: pointer to the buffer that shall take the data @@ -84,6 +96,7 @@ EXPORT_SYMBOL_GPL(probe_user_read); * Safely write to address @dst from the buffer at @src. If a kernel fault * happens, handle that and return -EFAULT. */ + long __weak probe_kernel_write(void *dst, const void *src, size_t size) __attribute__((alias("__probe_kernel_write"))); @@ -93,15 +106,39 @@ long __probe_kernel_write(void *dst, const void *src, size_t size) mm_segment_t old_fs = get_fs(); set_fs(KERNEL_DS); - pagefault_disable(); - ret = __copy_to_user_inatomic((__force void __user *)dst, src, size); - pagefault_enable(); + ret = probe_write_common((__force void __user *)dst, src, size); set_fs(old_fs); - return ret ? -EFAULT : 0; + return ret; } EXPORT_SYMBOL_GPL(probe_kernel_write); +/** + * probe_user_write(): safely attempt to write to a user-space location + * @dst: address to write to + * @src: pointer to the data that shall be written + * @size: size of the data chunk + * + * Safely write to address @dst from the buffer at @src. If a kernel fault + * happens, handle that and return -EFAULT. + */ + +long __weak probe_user_write(void __user *dst, const void *src, size_t size) + __attribute__((alias("__probe_user_write"))); + +long __probe_user_write(void __user *dst, const void *src, size_t size) +{ + long ret = -EFAULT; + mm_segment_t old_fs = get_fs(); + + set_fs(USER_DS); + if (access_ok(VERIFY_WRITE, dst, size)) + ret = probe_write_common(dst, src, size); + set_fs(old_fs); + + return ret; +} +EXPORT_SYMBOL_GPL(probe_user_write); /** * strncpy_from_unsafe: - Copy a NUL terminated string from unsafe address. -- 2.25.1