crypto: Implement TLS Pre-Shared Keys (PSK).

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 <rjones@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/crypto/trace-events b/crypto/trace-events
index e589990..597389b 100644
--- a/crypto/trace-events
+++ b/crypto/trace-events
@@ -7,6 +7,9 @@ qcrypto_tls_creds_get_path(void *creds, const char *filename, const char *path)
 # crypto/tlscredsanon.c
 qcrypto_tls_creds_anon_load(void *creds, const char *dir) "TLS creds anon load creds=%p dir=%s"
 
+# crypto/tlscredspsk.c
+qcrypto_tls_creds_psk_load(void *creds, const char *dir) "TLS creds psk load creds=%p dir=%s"
+
 # crypto/tlscredsx509.c
 qcrypto_tls_creds_x509_load(void *creds, const char *dir) "TLS creds x509 load creds=%p dir=%s"
 qcrypto_tls_creds_x509_check_basic_constraints(void *creds, const char *file, int status) "TLS creds x509 check basic constraints creds=%p file=%s status=%d"