Re: [RFC PATCH 3/9] common/encrypt: support checking for v2 encryption policy support

Eryu Guan
2019-09-01T12:08:06Z

On Mon, Aug 12, 2019 at 10:58:03AM -0700, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
>
> Allow passing '-v 2' to _require_scratch_encryption() to check for v2
> encryption policy support on the scratch device, and for xfs_io support
> for setting and getting v2 encryption policies.
>
> Signed-off-by: Eric Biggers <ebiggers@google.com>
> ---
> common/encrypt | 41 +++++++++++++++++++++++++++++++----------
> 1 file changed, 31 insertions(+), 10 deletions(-)
>
> diff --git a/common/encrypt b/common/encrypt
> index a086e80f..fa6e2672 100644
> --- a/common/encrypt
> +++ b/common/encrypt
> @@ -6,12 +6,13 @@
>
> #
> # _require_scratch_encryption [-c CONTENTS_MODE] [-n FILENAMES_MODE]
> +# [-v POLICY_VERSION]
> #
> # Require encryption support on the scratch device.
> #
> -# This checks for support for the default type of encryption policy (AES-256-XTS
> -# and AES-256-CTS). Options can be specified to also require support for a
> -# different type of encryption policy.
> +# This checks for support for the default type of encryption policy (v1 with
> +# AES-256-XTS and AES-256-CTS). Options can be specified to also require
> +# support for a different type of encryption policy.
> #
> _require_scratch_encryption()
> {
> @@ -68,13 +69,15 @@ _require_encryption_policy_support()
> local mnt=$1
> local dir=$mnt/tmpdir
> local set_encpolicy_args=""
> + local policy_version=1
> local c
>
> OPTIND=2
> - while getopts "c:n:" c; do
> + while getopts "c:n:v:" c; do
> case $c in
> - c|n)
> + c|n|v)
> set_encpolicy_args+=" -$c $OPTARG"
> + [ $c = v ] && policy_version=$OPTARG

Why not checking 'v' in a separate case?

> ;;
> *)
> _fail "Unrecognized option '$c'"
> @@ -87,10 +90,26 @@ _require_encryption_policy_support()
> >> $seqres.full
>
> mkdir $dir
> - _require_command "$KEYCTL_PROG" keyctl
> - _new_session_keyring
> - local keydesc=$(_generate_session_encryption_key)
> - if _set_encpolicy $dir $keydesc $set_encpolicy_args \
> + if (( policy_version > 1 )); then
> + _require_xfs_io_command "get_encpolicy" "-t"
> + local output=$(_get_encpolicy $dir -t)
> + if [ "$output" != "supported" ]; then
> + if [ "$output" = "unsupported" ]; then
> + _notrun "kernel does not support $FSTYP encryption v2 API"
> + fi
> + _fail "Unexpected output from 'get_encpolicy -t'"

Print $output in the _fail message as well?

Thanks,
Eryu

> + fi
> + # Both the kernel and xfs_io support v2 encryption policies, and
> + # therefore also filesystem-level keys -- since that's the only
> + # way to provide keys for v2 policies.
> + local raw_key=$(_generate_raw_encryption_key)
> + local keyspec=$(_add_enckey $mnt "$raw_key" | awk '{print $NF}')
> + else
> + _require_command "$KEYCTL_PROG" keyctl
> + _new_session_keyring
> + local keyspec=$(_generate_session_encryption_key)
> + fi
> + if _set_encpolicy $dir $keyspec $set_encpolicy_args \
> 2>&1 >>$seqres.full | egrep -q 'Invalid argument'; then
> _notrun "kernel does not support encryption policy: '$set_encpolicy_args'"
> fi
> @@ -103,7 +122,9 @@ _require_encryption_policy_support()
> if ! echo foo > $dir/file; then
> _notrun "encryption policy '$set_encpolicy_args' is unusable; probably missing kernel crypto API support"
> fi
> - $KEYCTL_PROG clear @s
> + if (( policy_version <= 1 )); then
> + $KEYCTL_PROG clear @s
> + fi
> rm -r $dir
> }
>
> --
> 2.23.0.rc1.153.gdeed80330f-goog
>