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

Browse Source 
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>
This commit is contained in:
Richard W.M. Jones
2018-07-03 09:03:03 +01:00
committed by Daniel P. Berrangé
parent 9b75dcb15f
commit e1a6dc91dd
11 changed files with 774 additions and 23 deletions
Download Patch File Download Diff File Expand all files Collapse all files

56
crypto/tlssession.c
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@@ -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"
@@ -88,6 +89,14 @@ qcrypto_tls_session_pull(void *opaque, void *buf, size_t len)
return session->readFunc(buf, len, session->opaque);
}
#define TLS_PRIORITY_ADDITIONAL_ANON "+ANON-DH"
#if GNUTLS_VERSION_MAJOR >= 3
#define TLS_ECDHE_PSK "+ECDHE-PSK:"
#else
#define TLS_ECDHE_PSK ""
#endif
#define TLS_PRIORITY_ADDITIONAL_PSK TLS_ECDHE_PSK "+DHE-PSK:+PSK"
QCryptoTLSSession *
qcrypto_tls_session_new(QCryptoTLSCreds *creds,
@@ -135,9 +144,12 @@ qcrypto_tls_session_new(QCryptoTLSCreds *creds,
char *prio;
if (creds->priority != NULL) {
prio = g_strdup_printf("%s:+ANON-DH", creds->priority);
prio = g_strdup_printf("%s:%s",
creds->priority,
TLS_PRIORITY_ADDITIONAL_ANON);
} else {
prio = g_strdup(CONFIG_TLS_PRIORITY ":+ANON-DH");
prio = g_strdup(CONFIG_TLS_PRIORITY ":"
TLS_PRIORITY_ADDITIONAL_ANON);
}
ret = gnutls_priority_set_direct(session->handle, prio, NULL);
@@ -162,6 +174,42 @@ 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:%s",
creds->priority,
TLS_PRIORITY_ADDITIONAL_PSK);
} else {
prio = g_strdup(CONFIG_TLS_PRIORITY ":"
TLS_PRIORITY_ADDITIONAL_PSK);
}
ret = gnutls_priority_set_direct(session->handle, prio, NULL);
if (ret < 0) {
error_setg(errp, "Unable to set TLS session priority %s: %s",
prio, gnutls_strerror(ret));
g_free(prio);
goto error;
}
g_free(prio);
if (creds->endpoint == QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) {
ret = gnutls_credentials_set(session->handle,
GNUTLS_CRD_PSK,
pcreds->data.server);
} else {
ret = gnutls_credentials_set(session->handle,
GNUTLS_CRD_PSK,
pcreds->data.client);
}
if (ret < 0) {
error_setg(errp, "Cannot set session credentials: %s",
gnutls_strerror(ret));
goto error;
}
} else if (object_dynamic_cast(OBJECT(creds),
TYPE_QCRYPTO_TLS_CREDS_X509)) {
QCryptoTLSCredsX509 *tcreds = QCRYPTO_TLS_CREDS_X509(creds);
@@ -353,6 +401,10 @@ qcrypto_tls_session_check_credentials(QCryptoTLSSession *session,
TYPE_QCRYPTO_TLS_CREDS_ANON)) {
trace_qcrypto_tls_session_check_creds(session, "nop");
return 0;
} else if (object_dynamic_cast(OBJECT(session->creds),
TYPE_QCRYPTO_TLS_CREDS_PSK)) {
trace_qcrypto_tls_session_check_creds(session, "nop");
return 0;
} else if (object_dynamic_cast(OBJECT(session->creds),
TYPE_QCRYPTO_TLS_CREDS_X509)) {
if (session->creds->verifyPeer) {