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=-9.8 required=3.0 tests=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 0C0E5CA9ED1 for ; Fri, 1 Nov 2019 23:19:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E1FEB20679 for ; Fri, 1 Nov 2019 23:19:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727180AbfKAXS7 (ORCPT ); Fri, 1 Nov 2019 19:18:59 -0400 Received: from www62.your-server.de ([213.133.104.62]:50448 "EHLO www62.your-server.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725989AbfKAXS7 (ORCPT ); Fri, 1 Nov 2019 19:18:59 -0400 Received: from 38.249.197.178.dynamic.dsl-lte-bonding.lssmb00p-msn.res.cust.swisscom.ch ([178.197.249.38] helo=localhost) by www62.your-server.de with esmtpsa (TLSv1.2:DHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89_1) (envelope-from ) id 1iQgBz-0000SS-1z; Sat, 02 Nov 2019 00:18:55 +0100 From: Daniel Borkmann To: bpf@vger.kernel.org Cc: netdev@vger.kernel.org, ast@kernel.org, andrii.nakryiko@gmail.com, john.fastabend@gmail.com, Daniel Borkmann , Andrii Nakryiko , Masami Hiramatsu Subject: [PATCH bpf-next v3 1/8] uaccess: Add non-pagefault user-space write function Date: Sat, 2 Nov 2019 00:17:56 +0100 Message-Id: <9df2542e68141bfa3addde631441ee45503856a8.1572649915.git.daniel@iogearbox.net> X-Mailer: git-send-email 2.21.0 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Authenticated-Sender: daniel@iogearbox.net X-Virus-Scanned: Clear (ClamAV 0.101.4/25620/Fri Nov 1 10:04:15 2019) Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org 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 Acked-by: Andrii Nakryiko Cc: Masami Hiramatsu --- 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 d4ee6e942562..38555435a64a 100644 --- a/include/linux/uaccess.h +++ b/include/linux/uaccess.h @@ -337,6 +337,18 @@ 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 d065736f6b87..2d3c3d01064c 100644 --- a/mm/maccess.c +++ b/mm/maccess.c @@ -18,6 +18,18 @@ 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 @@ -85,6 +97,7 @@ 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"))); @@ -94,15 +107,39 @@ 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(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. -- 2.21.0