From patchwork Tue Mar 14 10:39:00 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Luis Henriques X-Patchwork-Id: 13174025 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 9C5FDC6FD1D for ; Tue, 14 Mar 2023 10:40:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229633AbjCNKks (ORCPT ); Tue, 14 Mar 2023 06:40:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37144 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229482AbjCNKkr (ORCPT ); Tue, 14 Mar 2023 06:40:47 -0400 Received: from smtp-out1.suse.de (smtp-out1.suse.de [IPv6:2001:67c:2178:6::1c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 75FCE12F1A; Tue, 14 Mar 2023 03:40:20 -0700 (PDT) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 1E93D21A77; Tue, 14 Mar 2023 10:39:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1678790345; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=TPaFgIn5XsBkfQryStFIW5OHbcwX6REOoz2u1qCHyXU=; b=RsljtV6Se2Ekyu7uWAYBBLNav53UimNGlJqxQQ/In2Q95zc1u8c5VyMnpzl+CwaqEwOlLP k1dhXhrsbz90sVw6J8i3uI7xF5NBAoBkrv81P0p4PFTEDbTUhPTnd7PPbEdSb9DLGpYnCb 6L8zwrdVgsfTpKPnkgqpCKkV5S27kUQ= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1678790345; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=TPaFgIn5XsBkfQryStFIW5OHbcwX6REOoz2u1qCHyXU=; b=kl8uGVRQrmkfk7omxzCcHdZ+51KsLEPSp7wm+DOnDVI7dzHrWs/q5mRw0VwGXIlqEIV0F9 ZN7GODppyMSfLjAQ== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 7B9D013A1B; Tue, 14 Mar 2023 10:39:04 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id jR35GshOEGS4FQAAMHmgww (envelope-from ); Tue, 14 Mar 2023 10:39:04 +0000 Received: from localhost (brahms.olymp [local]) by brahms.olymp (OpenSMTPD) with ESMTPA id ab8d290f; Tue, 14 Mar 2023 10:39:03 +0000 (UTC) From: =?utf-8?q?Lu=C3=ADs_Henriques?= To: Eric Biggers , Xiubo Li , Jeff Layton Cc: "Theodore Y. Ts'o" , Jaegeuk Kim , Ilya Dryomov , linux-fscrypt@vger.kernel.org, ceph-devel@vger.kernel.org, linux-kernel@vger.kernel.org, =?utf-8?q?Lu?= =?utf-8?q?=C3=ADs_Henriques?= Subject: [PATCH v2 0/2] ceph: fscrypt: fix atomic open bug for encrypted directories Date: Tue, 14 Mar 2023 10:39:00 +0000 Message-Id: <20230314103902.32592-1-lhenriques@suse.de> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fscrypt@vger.kernel.org Hi! I started seeing fstest generic/123 failing in ceph fscrypt, when running it with 'test_dummy_encryption'. This test is quite simple: 1. Creates a directory with write permissions for root only 2. Writes into a file in that directory 3. Uses 'su' to try to modify that file as a different user, and gets -EPERM All the test steps succeed, but the test fails to cleanup: 'rm -rf ' will fail with -ENOTEMPTY. 'strace' shows that calling unlinkat() to remove the file got a -ENOENT and then -ENOTEMPTY for the directory. This is because 'su' does a drop_caches ('su (874): drop_caches: 2' in dmesg), and ceph's atomic open will do: if (IS_ENCRYPTED(dir)) { set_bit(CEPH_MDS_R_FSCRYPT_FILE, &req->r_req_flags); if (!fscrypt_has_encryption_key(dir)) { spin_lock(&dentry->d_lock); dentry->d_flags |= DCACHE_NOKEY_NAME; spin_unlock(&dentry->d_lock); } } Although 'dir' has the encryption key available, fscrypt_has_encryption_key() will return 'false' because fscrypt info isn't yet set after the cache cleanup. The first patch will add a new helper for the atomic_open that will force the fscrypt info to be loaded into an inode that has been evicted recently but for which the key is still available. The second patch switches ceph atomic_open to use the new fscrypt helper. Cheers, --- Luís Changes since v1: - Dropped IS_ENCRYPTED() from helper function because kerneldoc says already that it applies to encrypted directories and, most importantly, because it would introduce a different behaviour for CONFIG_FS_ENCRYPTION and !CONFIG_FS_ENCRYPTION. - Rephrased helper kerneldoc Changes since initial RFC (after Eric's review): - Added kerneldoc comments to the new fscrypt helper - Dropped '__' from helper name (now fscrypt_prepare_atomic_open()) - Added IS_ENCRYPTED() check in helper - DCACHE_NOKEY_NAME is not set if fscrypt_get_encryption_info() returns an error - Fixed helper for !CONFIG_FS_ENCRYPTION (now defined 'static inline') Luís Henriques (2): fscrypt: new helper function - fscrypt_prepare_atomic_open() ceph: switch atomic open to use new fscrypt helper fs/ceph/file.c | 8 +++----- fs/crypto/hooks.c | 33 +++++++++++++++++++++++++++++++++ include/linux/fscrypt.h | 7 +++++++ 3 files changed, 43 insertions(+), 5 deletions(-)