nbd: implement TLS support in the protocol negotiation

This extends the NBD protocol handling code so that it is capable
of negotiating TLS support during the connection setup. This involves
requesting the STARTTLS protocol option before any other NBD options.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-Id: <1455129674-17255-14-git-send-email-berrange@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 135 insertions, 1 deletions

diff --git a/nbd/client.c b/nbd/client.c
index 5e47ac7..9e5b651 100644
--- a/nbd/client.c
+++ b/nbd/client.c
@@ -83,10 +83,18 @@ static int nbd_handle_reply_err(uint32_t opt, uint32_t type, Error **errp)
         error_setg(errp, "Unsupported option type %x", opt);
         break;
 
+    case NBD_REP_ERR_POLICY:
+        error_setg(errp, "Denied by server for option %x", opt);
+        break;
+
     case NBD_REP_ERR_INVALID:
         error_setg(errp, "Invalid data length for option %x", opt);
         break;
 
+    case NBD_REP_ERR_TLS_REQD:
+        error_setg(errp, "TLS negotiation required before option %x", opt);
+        break;
+
     default:
         error_setg(errp, "Unknown error code when asking for option %x", opt);
         break;
@@ -242,17 +250,127 @@ static int nbd_receive_query_exports(QIOChannel *ioc,
     return 0;
 }
 
+static QIOChannel *nbd_receive_starttls(QIOChannel *ioc,
+                                        QCryptoTLSCreds *tlscreds,
+                                        const char *hostname, Error **errp)
+{
+    uint64_t magic = cpu_to_be64(NBD_OPTS_MAGIC);
+    uint32_t opt = cpu_to_be32(NBD_OPT_STARTTLS);
+    uint32_t length = 0;
+    uint32_t type;
+    QIOChannelTLS *tioc;
+    struct NBDTLSHandshakeData data = { 0 };
+
+    TRACE("Requesting TLS from server");
+    if (write_sync(ioc, &magic, sizeof(magic)) != sizeof(magic)) {
+        error_setg(errp, "Failed to send option magic");
+        return NULL;
+    }
+
+    if (write_sync(ioc, &opt, sizeof(opt)) != sizeof(opt)) {
+        error_setg(errp, "Failed to send option number");
+        return NULL;
+    }
+
+    if (write_sync(ioc, &length, sizeof(length)) != sizeof(length)) {
+        error_setg(errp, "Failed to send option length");
+        return NULL;
+    }
+
+    TRACE("Getting TLS reply from server1");
+    if (read_sync(ioc, &magic, sizeof(magic)) != sizeof(magic)) {
+        error_setg(errp, "failed to read option magic");
+        return NULL;
+    }
+    magic = be64_to_cpu(magic);
+    if (magic != NBD_REP_MAGIC) {
+        error_setg(errp, "Unexpected option magic");
+        return NULL;
+    }
+    TRACE("Getting TLS reply from server2");
+    if (read_sync(ioc, &opt, sizeof(opt)) != sizeof(opt)) {
+        error_setg(errp, "failed to read option");
+        return NULL;
+    }
+    opt = be32_to_cpu(opt);
+    if (opt != NBD_OPT_STARTTLS) {
+        error_setg(errp, "Unexpected option type %x expected %x",
+                   opt, NBD_OPT_STARTTLS);
+        return NULL;
+    }
+
+    TRACE("Getting TLS reply from server");
+    if (read_sync(ioc, &type, sizeof(type)) != sizeof(type)) {
+        error_setg(errp, "failed to read option type");
+        return NULL;
+    }
+    type = be32_to_cpu(type);
+    if (type != NBD_REP_ACK) {
+        error_setg(errp, "Server rejected request to start TLS %x",
+                   type);
+        return NULL;
+    }
+
+    TRACE("Getting TLS reply from server");
+    if (read_sync(ioc, &length, sizeof(length)) != sizeof(length)) {
+        error_setg(errp, "failed to read option length");
+        return NULL;
+    }
+    length = be32_to_cpu(length);
+    if (length != 0) {
+        error_setg(errp, "Start TLS reponse was not zero %x",
+                   length);
+        return NULL;
+    }
+
+    TRACE("TLS request approved, setting up TLS");
+    tioc = qio_channel_tls_new_client(ioc, tlscreds, hostname, errp);
+    if (!tioc) {
+        return NULL;
+    }
+    data.loop = g_main_loop_new(g_main_context_default(), FALSE);
+    TRACE("Starting TLS hanshake");
+    qio_channel_tls_handshake(tioc,
+                              nbd_tls_handshake,
+                              &data,
+                              NULL);
+
+    if (!data.complete) {
+        g_main_loop_run(data.loop);
+    }
+    g_main_loop_unref(data.loop);
+    if (data.error) {
+        error_propagate(errp, data.error);
+        object_unref(OBJECT(tioc));
+        return NULL;
+    }
+
+    return QIO_CHANNEL(tioc);
+}
+
+
 int nbd_receive_negotiate(QIOChannel *ioc, const char *name, uint32_t *flags,
+                          QCryptoTLSCreds *tlscreds, const char *hostname,
+                          QIOChannel **outioc,
                           off_t *size, Error **errp)
 {
     char buf[256];
     uint64_t magic, s;
     int rc;
 
-    TRACE("Receiving negotiation.");
+    TRACE("Receiving negotiation tlscreds=%p hostname=%s.",
+          tlscreds, hostname ? hostname : "<null>");
 
     rc = -EINVAL;
 
+    if (outioc) {
+        *outioc = NULL;
+    }
+    if (tlscreds && !outioc) {
+        error_setg(errp, "Output I/O channel required for TLS");
+        goto fail;
+    }
+
     if (read_sync(ioc, buf, 8) != 8) {
         error_setg(errp, "Failed to read data");
         goto fail;
@@ -314,6 +432,18 @@ int nbd_receive_negotiate(QIOChannel *ioc, const char *name, uint32_t *flags,
             error_setg(errp, "Failed to send clientflags field");
             goto fail;
         }
+        if (tlscreds) {
+            if (fixedNewStyle) {
+                *outioc = nbd_receive_starttls(ioc, tlscreds, hostname, errp);
+                if (!*outioc) {
+                    goto fail;
+                }
+                ioc = *outioc;
+            } else {
+                error_setg(errp, "Server does not support STARTTLS");
+                goto fail;
+            }
+        }
         if (!name) {
             TRACE("Using default NBD export name \"\"");
             name = "";
@@ -371,6 +501,10 @@ int nbd_receive_negotiate(QIOChannel *ioc, const char *name, uint32_t *flags,
             error_setg(errp, "Server does not support export names");
             goto fail;
         }
+        if (tlscreds) {
+            error_setg(errp, "Server does not support STARTTLS");
+            goto fail;
+        }
 
         if (read_sync(ioc, &s, sizeof(s)) != sizeof(s)) {
             error_setg(errp, "Failed to read export length");