/* Return -1 on failure, 0 if wantname is an available export. */
static int nbd_receive_query_exports(QIOChannel *ioc,
const char *wantname,
Error **errp)
{
bool foundExport = false;
trace_nbd_receive_query_exports_start(wantname);
if (nbd_send_option_request(ioc, NBD_OPT_LIST, 0, NULL, errp) < 0) {
return -1;
}
while (1) {
int ret = nbd_receive_list(ioc, wantname, &foundExport, errp);
if (ret < 0) {
/* Server gave unexpected reply */
return -1;
} else if (ret == 0) {
/* Done iterating. */
if (!foundExport) {
error_setg(errp, "No export with name '%s' available",
wantname);
nbd_send_opt_abort(ioc);
return -1;
}
trace_nbd_receive_query_exports_success(wantname);
return 0;
}
}
}
/* nbd_request_simple_option: Send an option request, and parse the reply
* return 1 for successful negotiation,
* 0 if operation is unsupported,
* -1 with errp set for any other error
*/
static int nbd_request_simple_option(QIOChannel *ioc, int opt, Error **errp)
{
NBDOptionReply reply;
int error;
if (nbd_send_option_request(ioc, opt, 0, NULL, errp) < 0) {
return -1;
}
if (nbd_receive_option_reply(ioc, opt, &reply, errp) < 0) {
return -1;
}
error = nbd_handle_reply_err(ioc, &reply, errp);
if (error <= 0) {
return error;
}
if (reply.type != NBD_REP_ACK) {
error_setg(errp, "Server answered option %d (%s) with unexpected "
"reply %" PRIu32 " (%s)", opt, nbd_opt_lookup(opt),
reply.type, nbd_rep_lookup(reply.type));
nbd_send_opt_abort(ioc);
return -1;
}
if (reply.length != 0) {
error_setg(errp, "Option %d ('%s') response length is %" PRIu32
" (it should be zero)", opt, nbd_opt_lookup(opt),
reply.length);
nbd_send_opt_abort(ioc);
return -1;
}
return 1;
}
static QIOChannel *nbd_receive_starttls(QIOChannel *ioc,
QCryptoTLSCreds *tlscreds,
const char *hostname, Error **errp)
{
nbd_opt_reply reply;
QIOChannelTLS *tioc;
struct NBDTLSHandshakeData data = { 0 };
trace_nbd_receive_starttls_request();
if (nbd_send_option_request(ioc, NBD_OPT_STARTTLS, 0, NULL, errp) < 0) {
return NULL;
}
trace_nbd_receive_starttls_reply();
if (nbd_receive_option_reply(ioc, NBD_OPT_STARTTLS, &reply, errp) < 0) {
return NULL;
}
if (reply.type != NBD_REP_ACK) {
error_setg(errp, "Server rejected request to start TLS %" PRIx32,
reply.type);
nbd_send_opt_abort(ioc);
return NULL;
}
if (reply.length != 0) {
error_setg(errp, "Start TLS response was not zero %" PRIu32,
reply.length);
nbd_send_opt_abort(ioc);
return NULL;
}
trace_nbd_receive_starttls_new_client();
tioc = qio_channel_tls_new_client(ioc, tlscreds, hostname, errp);
if (!tioc) {
return NULL;
}
qio_channel_set_name(QIO_CHANNEL(tioc), "nbd-client-tls");
data.loop = g_main_loop_new(g_main_context_default(), FALSE);
trace_nbd_receive_starttls_tls_handshake();
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);
}
/* Send NBD_OPT_ABORT as a courtesy to let the server know that we are
* not going to attempt further negotiation. */
static void nbd_send_opt_abort(QIOChannel *ioc)
{
/* Technically, a compliant server is supposed to reply to us; but
* older servers disconnected instead. At any rate, we're allowed
* to disconnect without waiting for the server reply, so we don't
* even care if the request makes it to the server, let alone
* waiting around for whether the server replies. */
nbd_send_option_request(ioc, NBD_OPT_ABORT, 0, NULL, NULL);
}
int nbd_receive_negotiate(QIOChannel *ioc, const char *name,
QCryptoTLSCreds *tlscreds, const char *hostname,
QIOChannel **outioc, NBDExportInfo *info,
Error **errp)
{
char buf[256];
uint64_t magic;
int rc;
bool zeroes = true;
trace_nbd_receive_negotiate(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 (nbd_read(ioc, buf, 8, errp) < 0) {
error_prepend(errp, "Failed to read data");
goto fail;
}
buf[8] = '\0';
if (strlen(buf) == 0) {
error_setg(errp, "Server connection closed unexpectedly");
goto fail;
}
magic = ldq_be_p(buf);
trace_nbd_receive_negotiate_magic(magic);
if (memcmp(buf, "NBDMAGIC", 8) != 0) {
error_setg(errp, "Invalid magic received");
goto fail;
}
if (nbd_read(ioc, &magic, sizeof(magic), errp) < 0) {
error_prepend(errp, "Failed to read magic");
goto fail;
}
magic = be64_to_cpu(magic);
trace_nbd_receive_negotiate_magic(magic);
if (magic == NBD_OPTS_MAGIC) {
uint32_t clientflags = 0;
uint16_t globalflags;
bool fixedNewStyle = false;
if (nbd_read(ioc, &globalflags, sizeof(globalflags), errp) < 0) {
error_prepend(errp, "Failed to read server flags");
goto fail;
}
globalflags = be16_to_cpu(globalflags);
trace_nbd_receive_negotiate_server_flags(globalflags);
if (globalflags & NBD_FLAG_FIXED_NEWSTYLE) {
fixedNewStyle = true;
clientflags |= NBD_FLAG_C_FIXED_NEWSTYLE;
}
if (globalflags & NBD_FLAG_NO_ZEROES) {
zeroes = false;
clientflags |= NBD_FLAG_C_NO_ZEROES;
}
/* client requested flags */
clientflags = cpu_to_be32(clientflags);
if (nbd_write(ioc, &clientflags, sizeof(clientflags), errp) < 0) {
error_prepend(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_nbd_receive_negotiate_default_name();
name = "";
}
if (fixedNewStyle) {
int result;
/* Try NBD_OPT_GO first - if it works, we are done (it
* also gives us a good message if the server requires
* TLS). If it is not available, fall back to
* NBD_OPT_LIST for nicer error messages about a missing
* export, then use NBD_OPT_EXPORT_NAME. */
result = nbd_opt_go(ioc, name, info, errp);
if (result < 0) {
goto fail;
}
if (result > 0) {
return 0;
}
/* Check our desired export is present in the
* server export list. Since NBD_OPT_EXPORT_NAME
* cannot return an error message, running this
* query gives us better error reporting if the
* export name is not available.
*/
if (nbd_receive_query_exports(ioc, name, errp) < 0) {
goto fail;
}
}
/* write the export name request */
if (nbd_send_option_request(ioc, NBD_OPT_EXPORT_NAME, -1, name,
errp) < 0) {
goto fail;
}
/* Read the response */
if (nbd_read(ioc, &info->size, sizeof(info->size), errp) < 0) {
error_prepend(errp, "Failed to read export length");
goto fail;
}
be64_to_cpus(&info->size);
if (nbd_read(ioc, &info->flags, sizeof(info->flags), errp) < 0) {
error_prepend(errp, "Failed to read export flags");
goto fail;
}
be16_to_cpus(&info->flags);
} else if (magic == NBD_CLIENT_MAGIC) {
uint32_t oldflags;
if (name) {
error_setg(errp, "Server does not support export names");
goto fail;
}
if (tlscreds) {
error_setg(errp, "Server does not support STARTTLS");
goto fail;
}
if (nbd_read(ioc, &info->size, sizeof(info->size), errp) < 0) {
error_prepend(errp, "Failed to read export length");
goto fail;
}
be64_to_cpus(&info->size);
if (nbd_read(ioc, &oldflags, sizeof(oldflags), errp) < 0) {
error_prepend(errp, "Failed to read export flags");
goto fail;
}
be32_to_cpus(&oldflags);
if (oldflags & ~0xffff) {
error_setg(errp, "Unexpected export flags %0x" PRIx32, oldflags);
goto fail;
}
info->flags = oldflags;
} else {
error_setg(errp, "Bad magic received");
goto fail;
}
trace_nbd_receive_negotiate_size_flags(info->size, info->flags);
if (zeroes && nbd_drop(ioc, 124, errp) < 0) {
error_prepend(errp, "Failed to read reserved block");
goto fail;
}
rc = 0;
fail:
return rc;
}
/* Returns -1 if NBD_OPT_GO proves the export @wantname cannot be
* used, 0 if NBD_OPT_GO is unsupported (fall back to NBD_OPT_LIST and
* NBD_OPT_EXPORT_NAME in that case), and > 0 if the export is good to
* go (with @info populated). */
static int nbd_opt_go(QIOChannel *ioc, const char *wantname,
NBDExportInfo *info, Error **errp)
{
nbd_opt_reply reply;
uint32_t len = strlen(wantname);
uint16_t type;
int error;
char *buf;
/* The protocol requires that the server send NBD_INFO_EXPORT with
* a non-zero flags (at least NBD_FLAG_HAS_FLAGS must be set); so
* flags still 0 is a witness of a broken server. */
info->flags = 0;
trace_nbd_opt_go_start(wantname);
buf = g_malloc(4 + len + 2 + 2 * info->request_sizes + 1);
stl_be_p(buf, len);
memcpy(buf + 4, wantname, len);
/* At most one request, everything else up to server */
stw_be_p(buf + 4 + len, info->request_sizes);
if (info->request_sizes) {
stw_be_p(buf + 4 + len + 2, NBD_INFO_BLOCK_SIZE);
}
error = nbd_send_option_request(ioc, NBD_OPT_GO,
4 + len + 2 + 2 * info->request_sizes,
buf, errp);
g_free(buf);
if (error < 0) {
return -1;
}
while (1) {
if (nbd_receive_option_reply(ioc, NBD_OPT_GO, &reply, errp) < 0) {
return -1;
}
error = nbd_handle_reply_err(ioc, &reply, errp);
if (error <= 0) {
return error;
}
len = reply.length;
if (reply.type == NBD_REP_ACK) {
/* Server is done sending info and moved into transmission
phase, but make sure it sent flags */
if (len) {
error_setg(errp, "server sent invalid NBD_REP_ACK");
return -1;
}
if (!info->flags) {
error_setg(errp, "broken server omitted NBD_INFO_EXPORT");
return -1;
}
trace_nbd_opt_go_success();
return 1;
}
if (reply.type != NBD_REP_INFO) {
error_setg(errp, "unexpected reply type %" PRIx32
" (%s), expected %x",
reply.type, nbd_rep_lookup(reply.type), NBD_REP_INFO);
nbd_send_opt_abort(ioc);
return -1;
}
if (len < sizeof(type)) {
error_setg(errp, "NBD_REP_INFO length %" PRIu32 " is too short",
len);
nbd_send_opt_abort(ioc);
return -1;
}
if (nbd_read(ioc, &type, sizeof(type), errp) < 0) {
error_prepend(errp, "failed to read info type");
nbd_send_opt_abort(ioc);
return -1;
}
len -= sizeof(type);
be16_to_cpus(&type);
switch (type) {
case NBD_INFO_EXPORT:
if (len != sizeof(info->size) + sizeof(info->flags)) {
error_setg(errp, "remaining export info len %" PRIu32
" is unexpected size", len);
nbd_send_opt_abort(ioc);
return -1;
}
if (nbd_read(ioc, &info->size, sizeof(info->size), errp) < 0) {
error_prepend(errp, "failed to read info size");
nbd_send_opt_abort(ioc);
return -1;
}
be64_to_cpus(&info->size);
if (nbd_read(ioc, &info->flags, sizeof(info->flags), errp) < 0) {
error_prepend(errp, "failed to read info flags");
nbd_send_opt_abort(ioc);
return -1;
}
be16_to_cpus(&info->flags);
trace_nbd_receive_negotiate_size_flags(info->size, info->flags);
break;
case NBD_INFO_BLOCK_SIZE:
if (len != sizeof(info->min_block) * 3) {
error_setg(errp, "remaining export info len %" PRIu32
" is unexpected size", len);
nbd_send_opt_abort(ioc);
return -1;
}
if (nbd_read(ioc, &info->min_block, sizeof(info->min_block),
errp) < 0) {
error_prepend(errp, "failed to read info minimum block size");
nbd_send_opt_abort(ioc);
return -1;
}
be32_to_cpus(&info->min_block);
if (!is_power_of_2(info->min_block)) {
error_setg(errp, "server minimum block size %" PRId32
"is not a power of two", info->min_block);
nbd_send_opt_abort(ioc);
return -1;
}
if (nbd_read(ioc, &info->opt_block, sizeof(info->opt_block),
errp) < 0) {
error_prepend(errp, "failed to read info preferred block size");
nbd_send_opt_abort(ioc);
return -1;
}
be32_to_cpus(&info->opt_block);
if (!is_power_of_2(info->opt_block) ||
info->opt_block < info->min_block) {
error_setg(errp, "server preferred block size %" PRId32
"is not valid", info->opt_block);
nbd_send_opt_abort(ioc);
return -1;
}
if (nbd_read(ioc, &info->max_block, sizeof(info->max_block),
errp) < 0) {
error_prepend(errp, "failed to read info maximum block size");
nbd_send_opt_abort(ioc);
return -1;
}
be32_to_cpus(&info->max_block);
trace_nbd_opt_go_info_block_size(info->min_block, info->opt_block,
info->max_block);
break;
default:
trace_nbd_opt_go_info_unknown(type, nbd_info_lookup(type));
if (nbd_drop(ioc, len, errp) < 0) {
error_prepend(errp, "Failed to read info payload");
nbd_send_opt_abort(ioc);
return -1;
}
break;
}
}
}
