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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9FA75C54EAA for ; Tue, 24 Jan 2023 13:45:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234557AbjAXNpu (ORCPT ); Tue, 24 Jan 2023 08:45:50 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34380 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234554AbjAXNo6 (ORCPT ); Tue, 24 Jan 2023 08:44:58 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1C2CA474E1; Tue, 24 Jan 2023 05:43:45 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 02B6F6122C; Tue, 24 Jan 2023 13:43:45 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 32240C433A0; Tue, 24 Jan 2023 13:43:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1674567824; bh=XfP2IiKF7/wVyeJMoIQrb3iku1W5wz1+jDgU4ERaZPk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=I46xNkQ4GTYKOV9RTzqr9tQO3A2bTmIx8a/2K28G1BA7qVDmjQBfpc6dKjW/2kaMz LrR2sRSS2Uqt70wnFL7OUtO8tfaQo2lGr1+zaiIWIR+8zwSg5MggwWE+GI4Ez6mamq Eqqu5hGk+EsOUbPBWPncBCwmeHz40pnvL2bNwjY2WIajTDQZZYsb00JoNG8DUGhj0v 7Z5DoLxdn6LpzeSneRbzsZpsEt311CqFTpMGPlCtI04atmYiec2oyyhuXYSY53Vr5s JZGDoUIHhQ3a5N7s7Vy+YMQ/wzFgzJmzg0r+6N1Ahx+aLduSRfcUpGb4AV1L2ljzh+ yDy/0yfNgsrBA== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Linus Torvalds , kernel test robot , Eric Biggers , Andreas Dilger , Theodore Ts'o , Jason Donenfeld , Masahiro Yamada , Sasha Levin , adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org Subject: [PATCH AUTOSEL 5.10 8/8] ext4: deal with legacy signed xattr name hash values Date: Tue, 24 Jan 2023 08:43:28 -0500 Message-Id: <20230124134328.637707-8-sashal@kernel.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230124134328.637707-1-sashal@kernel.org> References: <20230124134328.637707-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org From: Linus Torvalds [ Upstream commit f3bbac32475b27f49be201f896d98d4009de1562 ] We potentially have old hashes of the xattr names generated on systems with signed 'char' types. Now that everybody uses '-funsigned-char', those hashes will no longer match. This only happens if you use xattrs names that have the high bit set, which probably doesn't happen in practice, but the xfstest generic/454 shows it. Instead of adding a new "signed xattr hash filesystem" bit and having to deal with all the possible combinations, just calculate the hash both ways if the first one fails, and always generate new hashes with the proper unsigned char version. Reported-by: kernel test robot Link: https://lore.kernel.org/oe-lkp/202212291509.704a11c9-oliver.sang@intel.com Link: https://lore.kernel.org/all/CAHk-=whUNjwqZXa-MH9KMmc_CpQpoFKFjAB9ZKHuu=TbsouT4A@mail.gmail.com/ Exposed-by: 3bc753c06dd0 ("kbuild: treat char as always unsigned") Cc: Eric Biggers Cc: Andreas Dilger Cc: Theodore Ts'o , Cc: Jason Donenfeld Cc: Masahiro Yamada Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- fs/ext4/xattr.c | 41 +++++++++++++++++++++++++++++++++++++++-- 1 file changed, 39 insertions(+), 2 deletions(-) diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c index 6bf1c62eff04..9e5331eb1871 100644 --- a/fs/ext4/xattr.c +++ b/fs/ext4/xattr.c @@ -81,6 +81,8 @@ ext4_xattr_block_cache_find(struct inode *, struct ext4_xattr_header *, struct mb_cache_entry **); static __le32 ext4_xattr_hash_entry(char *name, size_t name_len, __le32 *value, size_t value_count); +static __le32 ext4_xattr_hash_entry_signed(char *name, size_t name_len, __le32 *value, + size_t value_count); static void ext4_xattr_rehash(struct ext4_xattr_header *); static const struct xattr_handler * const ext4_xattr_handler_map[] = { @@ -470,8 +472,21 @@ ext4_xattr_inode_verify_hashes(struct inode *ea_inode, tmp_data = cpu_to_le32(hash); e_hash = ext4_xattr_hash_entry(entry->e_name, entry->e_name_len, &tmp_data, 1); - if (e_hash != entry->e_hash) - return -EFSCORRUPTED; + /* All good? */ + if (e_hash == entry->e_hash) + return 0; + + /* + * Not good. Maybe the entry hash was calculated + * using the buggy signed char version? + */ + e_hash = ext4_xattr_hash_entry_signed(entry->e_name, entry->e_name_len, + &tmp_data, 1); + if (e_hash == entry->e_hash) + return 0; + + /* Still no match - bad */ + return -EFSCORRUPTED; } return 0; } @@ -3103,6 +3118,28 @@ static __le32 ext4_xattr_hash_entry(char *name, size_t name_len, __le32 *value, return cpu_to_le32(hash); } +/* + * ext4_xattr_hash_entry_signed() + * + * Compute the hash of an extended attribute incorrectly. + */ +static __le32 ext4_xattr_hash_entry_signed(char *name, size_t name_len, __le32 *value, size_t value_count) +{ + __u32 hash = 0; + + while (name_len--) { + hash = (hash << NAME_HASH_SHIFT) ^ + (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^ + (signed char)*name++; + } + while (value_count--) { + hash = (hash << VALUE_HASH_SHIFT) ^ + (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^ + le32_to_cpu(*value++); + } + return cpu_to_le32(hash); +} + #undef NAME_HASH_SHIFT #undef VALUE_HASH_SHIFT -- 2.39.0