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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CB8A1C433F5 for ; Wed, 29 Sep 2021 10:54:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B06B761390 for ; Wed, 29 Sep 2021 10:54:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245620AbhI2K4S (ORCPT ); Wed, 29 Sep 2021 06:56:18 -0400 Received: from bhuna.collabora.co.uk ([46.235.227.227]:47820 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245599AbhI2K4N (ORCPT ); Wed, 29 Sep 2021 06:56:13 -0400 Received: from localhost.localdomain (unknown [IPv6:2401:4900:1c20:3124:6d32:b2f4:daed:4666]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: shreeya) by bhuna.collabora.co.uk (Postfix) with ESMTPSA id 126401F43FB5; Wed, 29 Sep 2021 11:54:29 +0100 (BST) From: Shreeya Patel To: tytso@mit.edu, viro@zeniv.linux.org.uk, adilger.kernel@dilger.ca, krisman@collabora.com Cc: linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, kernel@collabora.com, Shreeya Patel Subject: [PATCH 2/2] fs: ext4: Fix the inconsistent name exposed by /proc/self/cwd Date: Wed, 29 Sep 2021 16:23:39 +0530 Message-Id: <8402d1c99877a4fcb152de71005fa9cfb25d86a8.1632909358.git.shreeya.patel@collabora.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org /proc/self/cwd is a symlink created by the kernel that uses whatever name the dentry has in the dcache. Since the dcache is populated only on the first lookup, with the string used in that lookup, cwd will have an unexpected case, depending on how the data was first looked-up in a case-insesitive filesystem. Steps to reproduce :- root@test-box:/src# mkdir insensitive/foo root@test-box:/src# cd insensitive/FOO root@test-box:/src/insensitive/FOO# ls -l /proc/self/cwd lrwxrwxrwx 1 root root /proc/self/cwd -> /src/insensitive/FOO root@test-box:/src/insensitive/FOO# cd ../fOo root@test-box:/src/insensitive/fOo# ls -l /proc/self/cwd lrwxrwxrwx 1 root root /proc/self/cwd -> /src/insensitive/FOO Above example shows that 'FOO' was the name used on first lookup here and it is stored in dcache instead of the original name 'foo'. This results in inconsistent name exposed by /proc/self/cwd since it uses the name stored in dcache. To avoid the above inconsistent name issue, handle the inexact-match string ( a string which is not a byte to byte match, but is an equivalent unicode string ) case in ext4_lookup which would store the original name in dcache using d_add_ci instead of the inexact-match string name. Signed-off-by: Shreeya Patel --- fs/ext4/namei.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c index da7698341d7d..3598f0e47067 100644 --- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -1801,6 +1801,19 @@ static struct dentry *ext4_lookup(struct inode *dir, struct dentry *dentry, unsi } #ifdef CONFIG_UNICODE + if (inode && IS_CASEFOLDED(dir)) + if (dentry && strcmp(dentry->d_name.name, de->name)) { + struct dentry *new; + struct qstr ciname; + + ciname.len = de->name_len; + ciname.name = kstrndup(de->name, ciname.len, GFP_NOFS); + if (!ciname.name) + return ERR_PTR(-ENOMEM); + new = d_add_ci(dentry, inode, &ciname); + kfree(ciname.name); + return new; + } if (!inode && IS_CASEFOLDED(dir)) { /* Eventually we want to call d_add_ci(dentry, NULL) * for negative dentries in the encoding case as -- 2.30.2