On Tue, Jun 26, 2018 at 11:25:54AM +0100, Richard W.M. Jones wrote:
> Pre-Shared Keys (PSK) is a simpler mechanism for enabling TLS
> connections than using certificates. It requires only a simple secret
> key:
>
> $ mkdir -m 0700 /tmp/keys
> $ psktool -u rjones -p /tmp/keys/keys.psk
> $ cat /tmp/keys/keys.psk
> rjones:d543770c15ad93d76443fb56f501a31969235f47e999720ae8d2336f6a13fcbc
>
> The key can be secretly shared between clients and servers. Clients
> must specify the directory containing the "keys.psk" file and a
> username (defaults to "qemu"). Servers must specify only the
> directory.
>
> Example NBD client:
>
> $ qemu-img info \
> --object
> tls-creds-psk,id=tls0,dir=/tmp/keys,username=rjones,endpoint=client \
> --image-opts \
>
> file.driver=nbd,file.host=localhost,file.port=10809,file.tls-creds=tls0,file.export=/
>
> Example NBD server using qemu-nbd:
>
> $ qemu-nbd -t -x / \
> --object tls-creds-psk,id=tls0,endpoint=server,dir=/tmp/keys \
> --tls-creds tls0 \
> image.qcow2
>
> Example NBD server using nbdkit:
>
> $ nbdkit -n -e / -fv \
> --tls=on --tls-psk=/tmp/keys/keys.psk \
> file file=disk.img
>
> Signed-off-by: Richard W.M. Jones <rjo...@redhat.com>
> ---
> crypto/Makefile.objs | 1 +
> crypto/tlscredspsk.c | 300
> +++++++++++++++++++++++++++++++++++++++++++
> crypto/tlssession.c | 38 ++++++
> crypto/trace-events | 3 +
> include/crypto/tlscredspsk.h | 106 +++++++++++++++
> qemu-doc.texi | 37 ++++++
> qemu-options.hx | 24 ++++
> 7 files changed, 509 insertions(+)
> diff --git a/crypto/tlssession.c b/crypto/tlssession.c
> index 96a02deb69..aed754bb83 100644
> --- a/crypto/tlssession.c
> +++ b/crypto/tlssession.c
> @@ -21,6 +21,7 @@
> #include "qemu/osdep.h"
> #include "crypto/tlssession.h"
> #include "crypto/tlscredsanon.h"
> +#include "crypto/tlscredspsk.h"
> #include "crypto/tlscredsx509.h"
> #include "qapi/error.h"
> #include "qemu/acl.h"
> @@ -162,6 +163,39 @@ qcrypto_tls_session_new(QCryptoTLSCreds *creds,
> gnutls_strerror(ret));
> goto error;
> }
> + } else if (object_dynamic_cast(OBJECT(creds),
> + TYPE_QCRYPTO_TLS_CREDS_PSK)) {
> + QCryptoTLSCredsPSK *pcreds = QCRYPTO_TLS_CREDS_PSK(creds);
> + char *prio;
> +
> + if (creds->priority != NULL) {
> + prio = g_strdup_printf("%s:+PSK:+DHE-PSK", creds->priority);
> + } else {
> + prio = g_strdup(CONFIG_TLS_PRIORITY ":+PSK:+DHE-PSK");
GNUTLS maintainer recommended that we list DHE-PSK as that provides
forward secrecy, and in fact list ECDHE-PSK first. So I think we need
:+ECDHE-PSK,+DHE-PSK,+PSK
Regards,
Daniel
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