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=-9.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,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 50D11C43381 for ; Mon, 25 Feb 2019 14:06:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0D6282146F for ; Mon, 25 Feb 2019 14:06:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1551103568; bh=izGoo4mpmQ1NSvjx+x5em9fJLcDQJIMtSqZj8d05Pps=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Onf/l2HJM79w9cij9+tZJfdJs/l59cC50CXFYPUZrKPTdZZvvJ5hTe6FDRyLTUupw JxWToTm1YW6CVrR+rtaEsE+IAdW8OUY+XYEGFZHtxSSGDoeiBn1Vaa2WnLFWHr1lX2 hmSo29dQv+Sq7Y9Uqc3KRzS3p8QCnByKVdb3JlWc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727403AbfBYOGG (ORCPT ); Mon, 25 Feb 2019 09:06:06 -0500 Received: from mail.kernel.org ([198.145.29.99]:51646 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726279AbfBYOGG (ORCPT ); Mon, 25 Feb 2019 09:06:06 -0500 Received: from localhost.localdomain (NE2965lan1.rev.em-net.ne.jp [210.141.244.193]) (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 E950B20663; Mon, 25 Feb 2019 14:06:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1551103564; bh=izGoo4mpmQ1NSvjx+x5em9fJLcDQJIMtSqZj8d05Pps=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=K+xv6DNtuA1FBKuSGfA1Q+ShnpaeokS8Hx3nGAenvL+TxJ82mzA4S17fLzPgZ/QeI 1aaJZFM+eypSWLzy6k7wljOkifjCYoqeWebv8f8Ra4wcG0T8hS3zF0IYom4p/wfiXx dUiLe+1gNNHQ5r2vWP5SIL1uLwjuHnEgDLGrYlJc= From: Masami Hiramatsu To: Steven Rostedt , Linus Torvalds Cc: mhiramat@kernel.org, linux-kernel@vger.kernel.org, Andy Lutomirski , Ingo Molnar , Andrew Morton , Changbin Du , Jann Horn , Kees Cook , Andy Lutomirski , Alexei Starovoitov , Nadav Amit , Peter Zijlstra Subject: [RFC PATCH 2/4] uaccess: Add non-pagefault user-space read functions Date: Mon, 25 Feb 2019 23:05:41 +0900 Message-Id: <155110354092.21156.13871336589042178985.stgit@devbox> X-Mailer: git-send-email 2.13.6 In-Reply-To: <155110348217.21156.3874419272673328527.stgit@devbox> References: <155110348217.21156.3874419272673328527.stgit@devbox> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add probe_user_read() and strncpy_from_unsafe_user() which will not involves mm_sem so we can use it for accessing user-space in irq-handler. Signed-off-by: Masami Hiramatsu --- include/linux/uaccess.h | 13 +++++ mm/maccess.c | 134 +++++++++++++++++++++++++++++++++++++++++------ 2 files changed, 131 insertions(+), 16 deletions(-) diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h index 37b226e8df13..906573b8f02c 100644 --- a/include/linux/uaccess.h +++ b/include/linux/uaccess.h @@ -240,6 +240,17 @@ extern long probe_kernel_read(void *dst, const void *src, size_t size); extern long __probe_kernel_read(void *dst, const void *src, size_t size); /* + * probe_user_read(): safely attempt to read from a location in user space + * @dst: pointer to the buffer that shall take the data + * @src: address to read from + * @size: size of the data chunk + * + * Safely read from address @src to the buffer at @dst. If a kernel fault + * happens, handle that and return -EFAULT. + */ +extern long probe_user_read(void *dst, const void __user *src, size_t size); + +/* * probe_kernel_write(): safely attempt to write to a location * @dst: address to write to * @src: pointer to the data that shall be written @@ -252,6 +263,8 @@ 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); 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); /** * probe_kernel_address(): safely attempt to read from a location diff --git a/mm/maccess.c b/mm/maccess.c index 7a9752d59587..7d38d783e0b1 100644 --- a/mm/maccess.c +++ b/mm/maccess.c @@ -5,8 +5,20 @@ #include #include +static __always_inline long +probe_read_common(void *dst, const void __user *src, size_t size) +{ + long ret; + + pagefault_disable(); + ret = __copy_from_user_inatomic(dst, src, size); + pagefault_enable(); + + return ret ? -EFAULT : 0; +} + /** - * probe_kernel_read(): safely attempt to read from a location + * probe_kernel_read(): safely attempt to read from a kernel-space location * @dst: pointer to the buffer that shall take the data * @src: address to read from * @size: size of the data chunk @@ -30,18 +42,53 @@ long __probe_kernel_read(void *dst, const void *src, size_t size) set_fs(KERNEL_DS); current->kernel_uaccess_faults_ok++; - pagefault_disable(); - ret = __copy_from_user_inatomic(dst, - (__force const void __user *)src, size); - pagefault_enable(); + ret = probe_read_common(dst, (__force const void __user *)src, size); current->kernel_uaccess_faults_ok--; set_fs(old_fs); - return ret ? -EFAULT : 0; + return ret; } EXPORT_SYMBOL_GPL(probe_kernel_read); /** + * probe_user_read(): safely attempt to read from a user-space location + * @dst: pointer to the buffer that shall take the data + * @src: address to read from. This must be a user address. + * @size: size of the data chunk + * + * Safely read from user address @src to the buffer at @dst. If a kernel fault + * happens, handle that and return -EFAULT. + */ + +long __weak probe_user_read(void *dst, const void __user *src, size_t size) + __attribute__((alias("__probe_user_read"))); + +static long __normal_probe_user_read(void *dst, const void __user *src, + size_t size) +{ + if (!access_ok(src, size)) + return -EFAULT; + + return probe_read_common(dst, src, size); +} + +long __probe_user_read(void *dst, const void __user *src, size_t size) +{ + long ret; + mm_segment_t old_fs = get_fs(); + + if (segment_eq(old_fs, USER_DS)) { + ret = __normal_probe_user_read(dst, src, size); + } else { + set_fs(USER_DS); + ret = __normal_probe_user_read(dst, src, size); + set_fs(old_fs); + } + return ret ? -EFAULT : 0; +} +EXPORT_SYMBOL_GPL(probe_user_read); + +/** * probe_kernel_write(): safely attempt to write to a location * @dst: address to write to * @src: pointer to the data that shall be written @@ -70,6 +117,22 @@ long __probe_kernel_write(void *dst, const void *src, size_t size) } EXPORT_SYMBOL_GPL(probe_kernel_write); + +static __always_inline long strncpy_from_unsafe_common(char *dst, + const char __user *unsafe_addr, long count) +{ + const char __user *src = unsafe_addr; + int ret; + + pagefault_disable(); + do { + ret = __get_user(*dst++, src++); + } while (dst[-1] && ret == 0 && src - unsafe_addr < count); + dst[-1] = '\0'; + pagefault_enable(); + + return ret ? -EFAULT : src - unsafe_addr; +} /** * strncpy_from_unsafe: - Copy a NUL terminated string from unsafe address. * @dst: Destination address, in kernel space. This buffer must be at @@ -90,7 +153,6 @@ EXPORT_SYMBOL_GPL(probe_kernel_write); long strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count) { mm_segment_t old_fs = get_fs(); - const void *src = unsafe_addr; long ret; if (unlikely(count <= 0)) @@ -98,16 +160,56 @@ long strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count) set_fs(KERNEL_DS); current->kernel_uaccess_faults_ok++; - pagefault_disable(); - - do { - ret = __get_user(*dst++, (const char __user __force *)src++); - } while (dst[-1] && ret == 0 && src - unsafe_addr < count); - - dst[-1] = '\0'; - pagefault_enable(); + ret = strncpy_from_unsafe_common(dst, + (const char __user __force *)unsafe_addr, count); current->kernel_uaccess_faults_ok--; set_fs(old_fs); - return ret ? -EFAULT : src - unsafe_addr; + return ret; +} + +static __always_inline long __strncpy_from_unsafe_user(char *dst, + const char __user *unsafe_addr, long count) +{ + if (!access_ok(unsafe_addr, count)) + return -EFAULT; + + return strncpy_from_unsafe_common(dst, unsafe_addr, count); +} + +/** + * strncpy_from_unsafe_user: - Copy a NUL terminated string from unsafe user + * address. + * @dst: Destination address, in kernel space. This buffer must be at + * least @count bytes long. + * @unsafe_addr: Unsafe user address. + * @count: Maximum number of bytes to copy, including the trailing NUL. + * + * Copies a NUL-terminated string from unsafe user address to kernel buffer. + * + * On success, returns the length of the string INCLUDING the trailing NUL. + * + * If access fails, returns -EFAULT (some data may have been copied + * and the trailing NUL added). + * + * If @count is smaller than the length of the string, copies @count-1 bytes, + * sets the last byte of @dst buffer to NUL and returns @count. + */ +long strncpy_from_unsafe_user(char *dst, const void __user *unsafe_addr, + long count) +{ + mm_segment_t old_fs = get_fs(); + long ret; + + if (unlikely(count <= 0)) + return 0; + + if (segment_eq(old_fs, USER_DS)) { + ret = __strncpy_from_unsafe_user(dst, unsafe_addr, count); + } else { + set_fs(USER_DS); + ret = __strncpy_from_unsafe_user(dst, unsafe_addr, count); + set_fs(old_fs); + } + return ret; }