From: Chandan Rajendra Subject: [RFC PATCH V2 11/11] ext4: Enable encryption for blocksize less than page size Date: Mon, 12 Feb 2018 15:13:47 +0530 Message-ID: <20180212094347.22071-12-chandan@linux.vnet.ibm.com> References: <20180212094347.22071-1-chandan@linux.vnet.ibm.com> Cc: Chandan Rajendra , linux-fsdevel@vger.kernel.org, ebiggers3@gmail.com, linux-fscrypt@vger.kernel.org, tytso@mit.edu To: linux-ext4@vger.kernel.org Return-path: Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:40030 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933313AbeBLJnJ (ORCPT ); Mon, 12 Feb 2018 04:43:09 -0500 Received: from pps.filterd (m0098394.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w1C9eRFO017198 for ; Mon, 12 Feb 2018 04:43:08 -0500 Received: from e37.co.us.ibm.com (e37.co.us.ibm.com [32.97.110.158]) by mx0a-001b2d01.pphosted.com with ESMTP id 2g377ak61j-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Mon, 12 Feb 2018 04:43:08 -0500 Received: from localhost by e37.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 12 Feb 2018 02:43:07 -0700 In-Reply-To: <20180212094347.22071-1-chandan@linux.vnet.ibm.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: Now that we have all the code to support encryption for block size less than page size scenario, this commit removes the conditional check in filesystem mount code. The commit also changes the support statement in Documentation/filesystems/fscrypt.rst to reflect the fact that encryption of filesystems with blocksize less than page size now works. Signed-off-by: Chandan Rajendra --- Documentation/filesystems/fscrypt.rst | 14 +++++++------- fs/ext4/super.c | 7 ------- 2 files changed, 7 insertions(+), 14 deletions(-) diff --git a/Documentation/filesystems/fscrypt.rst b/Documentation/filesystems/fscrypt.rst index 776ddc6..2147e53 100644 --- a/Documentation/filesystems/fscrypt.rst +++ b/Documentation/filesystems/fscrypt.rst @@ -202,13 +202,13 @@ modes are not currently supported because of the difficulty of dealing with ciphertext expansion. For file contents, each filesystem block is encrypted independently. -Currently, only the case where the filesystem block size is equal to -the system's page size (usually 4096 bytes) is supported. With the -XTS mode of operation (recommended), the logical block number within -the file is used as the IV. With the CBC mode of operation (not -recommended), ESSIV is used; specifically, the IV for CBC is the -logical block number encrypted with AES-256, where the AES-256 key is -the SHA-256 hash of the inode's data encryption key. +Starting from Linux kernel 4.17, encryption of filesystems with block +size less than system's page size is supported. With the XTS mode of +operation (recommended), the logical block number within the file is +used as the IV. With the CBC mode of operation (not recommended), +ESSIV is used; specifically, the IV for CBC is the logical block +number encrypted with AES-256, where the AES-256 key is the SHA-256 +hash of the inode's data encryption key. For filenames, the full filename is encrypted at once. Because of the requirements to retain support for efficient directory lookups and diff --git a/fs/ext4/super.c b/fs/ext4/super.c index ebb7edb..3ec04cc 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -4138,13 +4138,6 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) } } - if ((DUMMY_ENCRYPTION_ENABLED(sbi) || ext4_has_feature_encrypt(sb)) && - (blocksize != PAGE_SIZE)) { - ext4_msg(sb, KERN_ERR, - "Unsupported blocksize for fs encryption"); - goto failed_mount_wq; - }