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=unavailable 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 2A61BC433E0 for ; Thu, 28 Jan 2021 01:14:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CAEA364DDC for ; Thu, 28 Jan 2021 01:14:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231751AbhA1BOO (ORCPT ); Wed, 27 Jan 2021 20:14:14 -0500 Received: from mail.kernel.org ([198.145.29.99]:36494 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231268AbhA1BMt (ORCPT ); Wed, 27 Jan 2021 20:12:49 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id C716E64DDF; Thu, 28 Jan 2021 01:11:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1611796290; bh=3FKSeGnFSwLkGexruEOmwHRIKSYHxicnwpAlMSpiAT4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=h/ERDr1EtOYI56UIZB9j2JNHozqDhWyX+bjnXABK2JTnrz8WrPrA2NdNmR0S9Vwr9 lCeyOi7twFAPbik55xmmPhKyASSD6zfxImNaOv48LzamOPI5XseRZvAgrmHnbUyhJS a2ds6MwGuxgOJRvJMdqSRxff+ar+YatPn0QgEzuJ6NbH87qnMp1L5myO7J0pNt4LXm wSnzuUHTIWHRh6N5cKhi/twUilgk4nPUTj5KxVVW2mkmCXZlkr8V4hFmuhLnpb4tSn VA4e39wM1WfUKoBlSW3DsRlxU0/jt+jFHv7xTXzUR9SdZVZXnqazqZCy/SMpOmbsQY 3N/OLFEoH0yqw== Date: Wed, 27 Jan 2021 17:11:28 -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 6/6] fs-verity: support reading signature with ioctl Message-ID: References: <20210115181819.34732-1-ebiggers@kernel.org> <20210115181819.34732-7-ebiggers@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210115181819.34732-7-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_SIGNATURE to > FS_IOC_READ_VERITY_METADATA. This allows a userspace server program to > retrieve the built-in signature (if present) of a verity 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. > > The ability for userspace to read the built-in signatures is also useful > because it allows a system that is using the in-kernel signature > verification to migrate to userspace signature verification. > > 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 | 9 +++++++- > fs/verity/read_metadata.c | 30 ++++++++++++++++++++++++++ > include/uapi/linux/fsverity.h | 1 + > 3 files changed, 39 insertions(+), 1 deletion(-) > > diff --git a/Documentation/filesystems/fsverity.rst b/Documentation/filesystems/fsverity.rst > index 6dc5772037ef9..1d831e3cbcb33 100644 > --- a/Documentation/filesystems/fsverity.rst > +++ b/Documentation/filesystems/fsverity.rst > @@ -236,6 +236,7 @@ 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 > + #define FS_VERITY_METADATA_TYPE_SIGNATURE 3 > > struct fsverity_read_metadata_arg { > __u64 metadata_type; > @@ -256,6 +257,10 @@ This ioctl takes in a pointer to the following structure:: > - ``FS_VERITY_METADATA_TYPE_DESCRIPTOR`` reads the fs-verity > descriptor. See `fs-verity descriptor`_. > > +- ``FS_VERITY_METADATA_TYPE_SIGNATURE`` reads the signature which was > + passed to FS_IOC_ENABLE_VERITY, if any. See `Built-in signature > + verification`_. > + > 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 > @@ -279,7 +284,9 @@ FS_IOC_READ_VERITY_METADATA can fail with the following errors: > - ``EINTR``: the ioctl was interrupted before any data was read > - ``EINVAL``: reserved fields were set, or ``offset + length`` > overflowed > -- ``ENODATA``: the file is not a verity file > +- ``ENODATA``: the file is not a verity file, or > + FS_VERITY_METADATA_TYPE_SIGNATURE was requested but the file doesn't > + have a built-in signature > - ``ENOTTY``: this type of filesystem does not implement fs-verity, or > this ioctl is not yet implemented on it > - ``EOPNOTSUPP``: the kernel was not configured with fs-verity > diff --git a/fs/verity/read_metadata.c b/fs/verity/read_metadata.c > index 2dea6dd3bb05a..7e2d0c7bdf0de 100644 > --- a/fs/verity/read_metadata.c > +++ b/fs/verity/read_metadata.c > @@ -114,6 +114,34 @@ static int fsverity_read_descriptor(struct inode *inode, > kfree(desc); > return res; > } > + > +static int fsverity_read_signature(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; > + > + if (desc->sig_size == 0) { > + res = -ENODATA; > + goto out; > + } > + > + /* > + * Include only the signature. Note that fsverity_get_descriptor() > + * already verified that sig_size is in-bounds. > + */ > + res = fsverity_read_buffer(buf, offset, length, desc->signature, > + le32_to_cpu(desc->sig_size)); > +out: > + kfree(desc); > + return res; > +} > + > /** > * fsverity_ioctl_read_metadata() - read verity metadata from a file > * @filp: file to read the metadata from > @@ -158,6 +186,8 @@ int fsverity_ioctl_read_metadata(struct file *filp, const void __user *uarg) > length); > case FS_VERITY_METADATA_TYPE_DESCRIPTOR: > return fsverity_read_descriptor(inode, buf, arg.offset, length); > + case FS_VERITY_METADATA_TYPE_SIGNATURE: > + return fsverity_read_signature(inode, buf, arg.offset, length); > default: > return -EINVAL; > } > diff --git a/include/uapi/linux/fsverity.h b/include/uapi/linux/fsverity.h > index 41abc283dbccb..15384e22e331e 100644 > --- a/include/uapi/linux/fsverity.h > +++ b/include/uapi/linux/fsverity.h > @@ -85,6 +85,7 @@ struct fsverity_formatted_digest { > > #define FS_VERITY_METADATA_TYPE_MERKLE_TREE 1 > #define FS_VERITY_METADATA_TYPE_DESCRIPTOR 2 > +#define FS_VERITY_METADATA_TYPE_SIGNATURE 3 > > struct fsverity_read_metadata_arg { > __u64 metadata_type; > -- > 2.30.0