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Date: Mon, 21 Nov 2016 08:33:13 +1100
From: Dave Chinner <david@...morbit.com>
To: Eric Biggers <ebiggers@...gle.com>
Cc: fstests@...r.kernel.org, linux-ext4@...r.kernel.org,
linux-f2fs@...r.kernel.org, "Theodore Y . Ts'o" <tytso@....edu>,
Jaegeuk Kim <jaegeuk@...nel.org>,
Richard Weinberger <richard@....at>,
David Gstir <david@...ma-star.at>
Subject: Re: [PATCH 1/4] generic: add utilities for testing filesystem
encryption
On Thu, Nov 17, 2016 at 11:47:04AM -0800, Eric Biggers wrote:
> Add utilities for testing the filesystem-level encryption feature
> currently supported by ext4 and f2fs. Tests will be able to source
> common/encrypt and call _begin_encryption_test to set up an
> encryption-capable filesystem on the scratch device, or skip the test
> when not supported.
>
> A program fscrypt_util is also added to expose filesystem
> encryption-related commands to shell scripts.
>
> Signed-off-by: Eric Biggers <ebiggers@...gle.com>
> ---
> .gitignore | 1 +
> common/encrypt | 89 ++++++++++++++++
> src/Makefile | 2 +-
> src/fscrypt_util.c | 306 +++++++++++++++++++++++++++++++++++++++++++++++++++++
> 4 files changed, 397 insertions(+), 1 deletion(-)
> create mode 100755 common/encrypt
> create mode 100644 src/fscrypt_util.c
>
> diff --git a/.gitignore b/.gitignore
> index 915d2d8..7040f67 100644
> --- a/.gitignore
> +++ b/.gitignore
> @@ -54,6 +54,7 @@
> /src/fill
> /src/fill2
> /src/fs_perms
> +/src/fscrypt_util
> /src/fssum
> /src/fstest
> /src/fsync-tester
> diff --git a/common/encrypt b/common/encrypt
> new file mode 100755
> index 0000000..599d16f
> --- /dev/null
> +++ b/common/encrypt
> @@ -0,0 +1,89 @@
> +#!/bin/bash
> +#
> +# Common functions for testing filesystem-level encryption
> +#
> +#-----------------------------------------------------------------------
> +# Copyright (C) 2016 Google, Inc.
> +#
> +# Author: Eric Biggers <ebiggers@...gle.com>
> +#
> +# This program is free software; you can redistribute it and/or modify
> +# it under the terms of the GNU General Public License as published by
> +# the Free Software Foundation; either version 2 of the License, or
> +# (at your option) any later version.
> +#
> +# This program is distributed in the hope that it will be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> +# GNU General Public License for more details.
> +#
> +# You should have received a copy of the GNU General Public License
> +# along with this program; if not, see <http://www.gnu.org/licenses/>.
> +#-----------------------------------------------------------------------
> +
> +. ./common/rc
Tests will already have included common/rc before this file, so we
do not source it here.
> +
> +# Begin an encryption test. This creates the scratch filesystem with encryption
> +# enabled and mounts it, or skips the test if encryption isn't supported.
> +_begin_encryption_test() {
> +
> + _supported_os Linux
> + _supported_fs ext4 f2fs
These go in the tests, not here.
> +
> + # We use a dedicated test program 'fscrypt_util' for making API calls
> + # related to encryption. We aren't using 'e4crypt' because 'e4crypt' is
> + # currently ext4-specific, and with a test program we can easily include
> + # test-only commands and other functionality or behavior that wouldn't
> + # make sense in a real program.
> + _require_test_program fscrypt_util
> +
> + # The 'test_dummy_encryption' mount option interferes with trying to use
> + # encryption for real. So skip the real encryption tests if the
> + # 'test_dummy_encryption' mount option was specified.
> + if echo "$MOUNT_OPTIONS" | grep -q "test_dummy_encryption"; then
> + _notrun "Dummy encryption is on; skipping real encryption tests"
> + fi
_requires_real_encryption()
In each test.
> +
> + # Make a filesystem on the scratch device with the encryption feature
> + # enabled. If this fails then probably the userspace tools (e.g.
> + # e2fsprogs or f2fs-tools) are too old to understand encryption.
> + _require_scratch
> + if ! _scratch_mkfs_encrypted >/dev/null; then
> + _notrun "$FSTYP userspace tools do not support encryption"
> + fi
> +
> + # Try to mount the filesystem. If this fails then probably the kernel
> + # isn't aware of encryption.
> + if ! _scratch_mount &> /dev/null; then
> + _notrun "kernel is unaware of $FSTYP encryption feature"
> + fi
> +
> + # The kernel may be aware of encryption without supporting it. For
> + # example, for ext4 this is the case with kernels configured with
> + # CONFIG_EXT4_FS_ENCRYPTION=n. Detect support for encryption by trying
> + # to set an encryption policy. (For ext4 we could instead check for the
> + # presence of /sys/fs/ext4/features/encryption, but this is broken on
> + # some older kernels and is ext4-specific anyway.)
> + mkdir $SCRATCH_MNT/tmpdir
> + if src/fscrypt_util set_policy 0000111122223333 $SCRATCH_MNT/tmpdir \
> + 2>&1 >/dev/null |
> + egrep -q 'Inappropriate ioctl for device|Operation not supported'
> + then
> + _notrun "kernel does not support $FSTYP encryption"
> + fi
> + rmdir $SCRATCH_MNT/tmpdir
And this should all be in a _requires_encryption() function.
> +}
> +
> +_scratch_mkfs_encrypted() {
> + case $FSTYP in
> + ext4)
> + # ext4 encryption requires block size = PAGE_SIZE.
> + MKFS_OPTIONS="-O encrypt -b $(getconf PAGE_SIZE)" _scratch_mkfs
> + ;;
> + *)
> + MKFS_OPTIONS="-O encrypt" _scratch_mkfs
> + ;;
> + esac
> +}
THis completely overrides any user supplied mkfs options, which we
try to avoid doing. Instead, this should simply be
_scratch_mkfs -O encrypt
so that _scratch_mkfs_encrypted() fails if there are conflicting
mkfs options specified. This means _requires_encryption() will
not_run the test when this occurrs...
> +FSCRYPT_UTIL=`pwd`/src/fscrypt_util
_require_test_program fscrypt_util
FSCRYPT_UTIL=src/fscrypt_util
> diff --git a/src/fscrypt_util.c b/src/fscrypt_util.c
> new file mode 100644
> index 0000000..de63667
> --- /dev/null
> +++ b/src/fscrypt_util.c
....
Ok, can we get this added to xfs_io rather than a stand-alone
fstests helper? There are three clear commands here:
{"gen_key", gen_key},
{"rm_key", rm_key},
{"set_policy", set_policy},
So it should plug straight into the xfs_io command parsing
infrastructure without much change at all.
Cheers,
Dave.
--
Dave Chinner
david@...morbit.com
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