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=-16.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 A8381C433E0 for ; Thu, 28 Jan 2021 01:14:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5B4FD64DDA for ; Thu, 28 Jan 2021 01:14:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231329AbhA1BOh (ORCPT ); Wed, 27 Jan 2021 20:14:37 -0500 Received: from mail.kernel.org ([198.145.29.99]:36428 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231794AbhA1BL5 (ORCPT ); Wed, 27 Jan 2021 20:11:57 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 16B9F64DBD; Thu, 28 Jan 2021 01:11:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1611796276; bh=/Oilbb/ZZgtI9SkGEjwZzZmBkyn7LM79p8zwItCMxtc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=K41HnkPDh/xwHbUR9OrfWQtouLDVZAsS0qFXYGJycfwFM1vxZ5fc+CAZxG1Bifigw 0aHGw7RWaecdeAhDIg8IGmPQL1fRYzhfrBDI52nI0W3LroqedZGNIkRomC7em1gYdz MtVwl1aDA+k+T58788eXVA3CINl75CKl3ZDkPhk071i23c0W/7ydsnWIrfoS45pAik uX33yfGFCI+dHcxAtFKBULxSK67iOtJlqAqX/9ce/JAdDgLcVi86ijrvKy9YqJyjl4 qD/G0oHfRCyeW8d32chpwoGmY5N6VFcWgXuliJQa2edUUVcsR6Zqui9FYYgt/thoOW Lw41gGul7ee4w== Date: Wed, 27 Jan 2021 17:11:14 -0800 From: Jaegeuk Kim To: Eric Biggers Cc: linux-fscrypt@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-api@vger.kernel.org, Theodore Ts'o , Victor Hsieh Subject: Re: [PATCH 5/6] fs-verity: support reading descriptor with ioctl Message-ID: References: <20210115181819.34732-1-ebiggers@kernel.org> <20210115181819.34732-6-ebiggers@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210115181819.34732-6-ebiggers@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 01/15, Eric Biggers wrote: > From: Eric Biggers > > Add support for FS_VERITY_METADATA_TYPE_DESCRIPTOR to > FS_IOC_READ_VERITY_METADATA. This allows a userspace server program to > retrieve the fs-verity descriptor of a file for serving to a client > which implements fs-verity compatible verification. See the patch which > introduced FS_IOC_READ_VERITY_METADATA for more details. > > "fs-verity descriptor" here means only the part that userspace cares > about because it is hashed to produce the file digest. It doesn't > include the signature which ext4 and f2fs append to the > fsverity_descriptor struct when storing it on-disk, since that way of > storing the signature is an implementation detail. The next patch adds > a separate metadata_type value for retrieving the signature separately. > > This has been tested using a new xfstest which calls this ioctl via a > new subcommand for the 'fsverity' program from fsverity-utils. > > Signed-off-by: Eric Biggers Reviewed-by: Jaegeuk Kim > --- > Documentation/filesystems/fsverity.rst | 4 +++ > fs/verity/read_metadata.c | 40 ++++++++++++++++++++++++++ > include/uapi/linux/fsverity.h | 1 + > 3 files changed, 45 insertions(+) > > diff --git a/Documentation/filesystems/fsverity.rst b/Documentation/filesystems/fsverity.rst > index 50b47a6d9ea11..6dc5772037ef9 100644 > --- a/Documentation/filesystems/fsverity.rst > +++ b/Documentation/filesystems/fsverity.rst > @@ -235,6 +235,7 @@ need this ioctl. > This ioctl takes in a pointer to the following structure:: > > #define FS_VERITY_METADATA_TYPE_MERKLE_TREE 1 > + #define FS_VERITY_METADATA_TYPE_DESCRIPTOR 2 > > struct fsverity_read_metadata_arg { > __u64 metadata_type; > @@ -252,6 +253,9 @@ This ioctl takes in a pointer to the following structure:: > the same order that their hashes are themselves hashed. > See `Merkle tree`_ for more information. > > +- ``FS_VERITY_METADATA_TYPE_DESCRIPTOR`` reads the fs-verity > + descriptor. See `fs-verity descriptor`_. > + > The semantics are similar to those of ``pread()``. ``offset`` > specifies the offset in bytes into the metadata item to read from, and > ``length`` specifies the maximum number of bytes to read from the > diff --git a/fs/verity/read_metadata.c b/fs/verity/read_metadata.c > index 0f8ad2991cf90..2dea6dd3bb05a 100644 > --- a/fs/verity/read_metadata.c > +++ b/fs/verity/read_metadata.c > @@ -76,6 +76,44 @@ static int fsverity_read_merkle_tree(struct inode *inode, > } > return retval ? retval : err; > } > + > +/* Copy the requested portion of the buffer to userspace. */ > +static int fsverity_read_buffer(void __user *dst, u64 offset, int length, > + const void *src, size_t src_length) > +{ > + if (offset >= src_length) > + return 0; > + src += offset; > + src_length -= offset; > + > + length = min_t(size_t, length, src_length); > + > + if (copy_to_user(dst, src, length)) > + return -EFAULT; > + > + return length; > +} > + > +static int fsverity_read_descriptor(struct inode *inode, > + void __user *buf, u64 offset, int length) > +{ > + struct fsverity_descriptor *desc; > + size_t desc_size; > + int res; > + > + res = fsverity_get_descriptor(inode, &desc, &desc_size); > + if (res) > + return res; > + > + /* don't include the signature */ > + desc_size = offsetof(struct fsverity_descriptor, signature); > + desc->sig_size = 0; > + > + res = fsverity_read_buffer(buf, offset, length, desc, desc_size); > + > + kfree(desc); > + return res; > +} > /** > * fsverity_ioctl_read_metadata() - read verity metadata from a file > * @filp: file to read the metadata from > @@ -118,6 +156,8 @@ int fsverity_ioctl_read_metadata(struct file *filp, const void __user *uarg) > case FS_VERITY_METADATA_TYPE_MERKLE_TREE: > return fsverity_read_merkle_tree(inode, vi, buf, arg.offset, > length); > + case FS_VERITY_METADATA_TYPE_DESCRIPTOR: > + return fsverity_read_descriptor(inode, buf, arg.offset, length); > default: > return -EINVAL; > } > diff --git a/include/uapi/linux/fsverity.h b/include/uapi/linux/fsverity.h > index 94003b153cb3d..41abc283dbccb 100644 > --- a/include/uapi/linux/fsverity.h > +++ b/include/uapi/linux/fsverity.h > @@ -84,6 +84,7 @@ struct fsverity_formatted_digest { > }; > > #define FS_VERITY_METADATA_TYPE_MERKLE_TREE 1 > +#define FS_VERITY_METADATA_TYPE_DESCRIPTOR 2 > > struct fsverity_read_metadata_arg { > __u64 metadata_type; > -- > 2.30.0