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qemu/nbd/client.c
Eric Blake 7c6f5ddca6 nbd/client: Work around 3.0 bug for listing meta contexts 
Commit 3d068aff forgot to advertise available qemu: contexts
when the client requests a list with 0 queries. Furthermore,
3.0 shipped with a qemu-img hack of x-dirty-bitmap (commit
216ee365) that _silently_ acts as though the entire image is
clean if a requested bitmap is not present.  Both bugs have
been recently fixed, so that a modern qemu server gives full
context output right away, and the client refuses a
connection if a requested x-dirty-bitmap was not found.

Still, it is likely that there will be users that have to
work with a mix of old and new qemu versions, depending on
which features get backported where, at which point being
able to rely on 'qemu-img --list' output to know for sure
whether a given NBD export has the desired dirty bitmap is
much nicer than blindly connecting and risking that the
entire image may appear clean.  We can make our --list code
smart enough to work around buggy servers by tracking
whether we've seen any qemu: replies in the original 0-query
list; if not, repeat with a single query on "qemu:" (which
may still have no replies, but then we know for sure we
didn't trip up on the server bug).

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20190117193658.16413-21-eblake@redhat.com>
2019-01-21 15:49:52 -06:00

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/*
* Copyright (C) 2016-2018 Red Hat, Inc.
* Copyright (C) 2005 Anthony Liguori <anthony@codemonkey.ws>
*
* Network Block Device Client Side
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; under version 2 of the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#include "qemu/osdep.h"
#include "qapi/error.h"
#include "trace.h"
#include "nbd-internal.h"
#include "qemu/cutils.h"
/* Definitions for opaque data types */
static QTAILQ_HEAD(, NBDExport) exports = QTAILQ_HEAD_INITIALIZER(exports);
/* That's all folks */
/* Basic flow for negotiation
Server Client
Negotiate
or
Server Client
Negotiate #1
Option
Negotiate #2
----
followed by
Server Client
Request
Response
Request
Response
...
...
Request (type == 2)
*/
/* Send an option request.
*
* The request is for option @opt, with @data containing @len bytes of
* additional payload for the request (@len may be -1 to treat @data as
* a C string; and @data may be NULL if @len is 0).
* Return 0 if successful, -1 with errp set if it is impossible to
* continue. */
static int nbd_send_option_request(QIOChannel *ioc, uint32_t opt,
uint32_t len, const char *data,
Error **errp)
{
NBDOption req;
QEMU_BUILD_BUG_ON(sizeof(req) != 16);
if (len == -1) {
req.length = len = strlen(data);
}
trace_nbd_send_option_request(opt, nbd_opt_lookup(opt), len);
stq_be_p(&req.magic, NBD_OPTS_MAGIC);
stl_be_p(&req.option, opt);
stl_be_p(&req.length, len);
if (nbd_write(ioc, &req, sizeof(req), errp) < 0) {
error_prepend(errp, "Failed to send option request header: ");
return -1;
}
if (len && nbd_write(ioc, (char *) data, len, errp) < 0) {
error_prepend(errp, "Failed to send option request data: ");
return -1;
}
return 0;
}
/* 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);
}
/* Receive the header of an option reply, which should match the given
* opt. Read through the length field, but NOT the length bytes of
* payload. Return 0 if successful, -1 with errp set if it is
* impossible to continue. */
static int nbd_receive_option_reply(QIOChannel *ioc, uint32_t opt,
NBDOptionReply *reply, Error **errp)
{
QEMU_BUILD_BUG_ON(sizeof(*reply) != 20);
if (nbd_read(ioc, reply, sizeof(*reply), errp) < 0) {
error_prepend(errp, "failed to read option reply: ");
nbd_send_opt_abort(ioc);
return -1;
}
reply->magic = be64_to_cpu(reply->magic);
reply->option = be32_to_cpu(reply->option);
reply->type = be32_to_cpu(reply->type);
reply->length = be32_to_cpu(reply->length);
trace_nbd_receive_option_reply(reply->option, nbd_opt_lookup(reply->option),
reply->type, nbd_rep_lookup(reply->type),
reply->length);
if (reply->magic != NBD_REP_MAGIC) {
error_setg(errp, "Unexpected option reply magic");
nbd_send_opt_abort(ioc);
return -1;
}
if (reply->option != opt) {
error_setg(errp, "Unexpected option type %u (%s), expected %u (%s)",
reply->option, nbd_opt_lookup(reply->option),
opt, nbd_opt_lookup(opt));
nbd_send_opt_abort(ioc);
return -1;
}
return 0;
}
/* If reply represents success, return 1 without further action.
* If reply represents an error, consume the optional payload of
* the packet on ioc. Then return 0 for unsupported (so the client
* can fall back to other approaches), or -1 with errp set for other
* errors.
*/
static int nbd_handle_reply_err(QIOChannel *ioc, NBDOptionReply *reply,
Error **errp)
{
char *msg = NULL;
int result = -1;
if (!(reply->type & (1 << 31))) {
return 1;
}
if (reply->length) {
if (reply->length > NBD_MAX_BUFFER_SIZE) {
error_setg(errp, "server error %" PRIu32
" (%s) message is too long",
reply->type, nbd_rep_lookup(reply->type));
goto cleanup;
}
msg = g_malloc(reply->length + 1);
if (nbd_read(ioc, msg, reply->length, errp) < 0) {
error_prepend(errp, "failed to read option error %" PRIu32
" (%s) message: ",
reply->type, nbd_rep_lookup(reply->type));
goto cleanup;
}
msg[reply->length] = '\0';
trace_nbd_server_error_msg(reply->type,
nbd_reply_type_lookup(reply->type), msg);
}
switch (reply->type) {
case NBD_REP_ERR_UNSUP:
trace_nbd_reply_err_unsup(reply->option, nbd_opt_lookup(reply->option));
result = 0;
goto cleanup;
case NBD_REP_ERR_POLICY:
error_setg(errp, "Denied by server for option %" PRIu32 " (%s)",
reply->option, nbd_opt_lookup(reply->option));
break;
case NBD_REP_ERR_INVALID:
error_setg(errp, "Invalid parameters for option %" PRIu32 " (%s)",
reply->option, nbd_opt_lookup(reply->option));
break;
case NBD_REP_ERR_PLATFORM:
error_setg(errp, "Server lacks support for option %" PRIu32 " (%s)",
reply->option, nbd_opt_lookup(reply->option));
break;
case NBD_REP_ERR_TLS_REQD:
error_setg(errp, "TLS negotiation required before option %" PRIu32
" (%s)", reply->option, nbd_opt_lookup(reply->option));
break;
case NBD_REP_ERR_UNKNOWN:
error_setg(errp, "Requested export not available");
break;
case NBD_REP_ERR_SHUTDOWN:
error_setg(errp, "Server shutting down before option %" PRIu32 " (%s)",
reply->option, nbd_opt_lookup(reply->option));
break;
case NBD_REP_ERR_BLOCK_SIZE_REQD:
error_setg(errp, "Server requires INFO_BLOCK_SIZE for option %" PRIu32
" (%s)", reply->option, nbd_opt_lookup(reply->option));
break;
default:
error_setg(errp, "Unknown error code when asking for option %" PRIu32
" (%s)", reply->option, nbd_opt_lookup(reply->option));
break;
}
if (msg) {
error_append_hint(errp, "server reported: %s\n", msg);
}
cleanup:
g_free(msg);
if (result < 0) {
nbd_send_opt_abort(ioc);
}
return result;
}
/* nbd_receive_list:
* Process another portion of the NBD_OPT_LIST reply, populating any
* name received into *@name. If @description is non-NULL, and the
* server provided a description, that is also populated. The caller
* must eventually call g_free() on success.
* Returns 1 if name and description were set and iteration must continue,
* 0 if iteration is complete (including if OPT_LIST unsupported),
* -1 with @errp set if an unrecoverable error occurred.
*/
static int nbd_receive_list(QIOChannel *ioc, char **name, char **description,
Error **errp)
{
int ret = -1;
NBDOptionReply reply;
uint32_t len;
uint32_t namelen;
char *local_name = NULL;
char *local_desc = NULL;
int error;
if (nbd_receive_option_reply(ioc, NBD_OPT_LIST, &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) {
if (len != 0) {
error_setg(errp, "length too long for option end");
nbd_send_opt_abort(ioc);
return -1;
}
return 0;
} else if (reply.type != NBD_REP_SERVER) {
error_setg(errp, "Unexpected reply type %u (%s), expected %u (%s)",
reply.type, nbd_rep_lookup(reply.type),
NBD_REP_SERVER, nbd_rep_lookup(NBD_REP_SERVER));
nbd_send_opt_abort(ioc);
return -1;
}
if (len < sizeof(namelen) || len > NBD_MAX_BUFFER_SIZE) {
error_setg(errp, "incorrect option length %" PRIu32, len);
nbd_send_opt_abort(ioc);
return -1;
}
if (nbd_read(ioc, &namelen, sizeof(namelen), errp) < 0) {
error_prepend(errp, "failed to read option name length: ");
nbd_send_opt_abort(ioc);
return -1;
}
namelen = be32_to_cpu(namelen);
len -= sizeof(namelen);
if (len < namelen) {
error_setg(errp, "incorrect option name length");
nbd_send_opt_abort(ioc);
return -1;
}
local_name = g_malloc(namelen + 1);
if (nbd_read(ioc, local_name, namelen, errp) < 0) {
error_prepend(errp, "failed to read export name: ");
nbd_send_opt_abort(ioc);
goto out;
}
local_name[namelen] = '\0';
len -= namelen;
if (len) {
local_desc = g_malloc(len + 1);
if (nbd_read(ioc, local_desc, len, errp) < 0) {
error_prepend(errp, "failed to read export description: ");
nbd_send_opt_abort(ioc);
goto out;
}
local_desc[len] = '\0';
}
trace_nbd_receive_list(local_name, local_desc ?: "");
*name = local_name;
local_name = NULL;
if (description) {
*description = local_desc;
local_desc = NULL;
}
ret = 1;
out:
g_free(local_name);
g_free(local_desc);
return ret;
}
/*
* nbd_opt_info_or_go:
* Send option for NBD_OPT_INFO or NBD_OPT_GO and parse the reply.
* Returns -1 if the option proves the export @info->name cannot be
* used, 0 if the option 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 the rest of @info populated).
*/
static int nbd_opt_info_or_go(QIOChannel *ioc, uint32_t opt,
NBDExportInfo *info, Error **errp)
{
NBDOptionReply reply;
uint32_t len = strlen(info->name);
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;
assert(opt == NBD_OPT_GO || opt == NBD_OPT_INFO);
trace_nbd_opt_info_go_start(nbd_opt_lookup(opt), info->name);
buf = g_malloc(4 + len + 2 + 2 * info->request_sizes + 1);
stl_be_p(buf, len);
memcpy(buf + 4, info->name, 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, opt,
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, opt, &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 for NBD_OPT_GO, 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_info_go_success(nbd_opt_lookup(opt));
return 1;
}
if (reply.type != NBD_REP_INFO) {
error_setg(errp, "unexpected reply type %u (%s), expected %u (%s)",
reply.type, nbd_rep_lookup(reply.type),
NBD_REP_INFO, nbd_rep_lookup(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);
type = be16_to_cpu(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;
}
info->size = be64_to_cpu(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;
}
info->flags = be16_to_cpu(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;
}
info->min_block = be32_to_cpu(info->min_block);
if (!is_power_of_2(info->min_block)) {
error_setg(errp, "server minimum block size %" PRIu32
" 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;
}
info->opt_block = be32_to_cpu(info->opt_block);
if (!is_power_of_2(info->opt_block) ||
info->opt_block < info->min_block) {
error_setg(errp, "server preferred block size %" PRIu32
" 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;
}
info->max_block = be32_to_cpu(info->max_block);
if (info->max_block < info->min_block) {
error_setg(errp, "server maximum block size %" PRIu32
" is not valid", info->max_block);
nbd_send_opt_abort(ioc);
return -1;
}
trace_nbd_opt_info_block_size(info->min_block, info->opt_block,
info->max_block);
break;
default:
trace_nbd_opt_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;
}
}
}
/* 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 list_empty = true;
bool found_export = 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) {
char *name;
int ret = nbd_receive_list(ioc, &name, NULL, errp);
if (ret < 0) {
/* Server gave unexpected reply */
return -1;
} else if (ret == 0) {
/* Done iterating. */
if (list_empty) {
/*
* We don't have enough context to tell a server that
* sent an empty list apart from a server that does
* not support the list command; but as this function
* is just used to trigger a nicer error message
* before trying NBD_OPT_EXPORT_NAME, assume the
* export is available.
*/
return 0;
} else if (!found_export) {
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;
}
list_empty = false;
if (!strcmp(name, wantname)) {
found_export = true;
}
g_free(name);
}
}
/* 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)
{
int ret;
QIOChannelTLS *tioc;
struct NBDTLSHandshakeData data = { 0 };
ret = nbd_request_simple_option(ioc, NBD_OPT_STARTTLS, errp);
if (ret <= 0) {
if (ret == 0) {
error_setg(errp, "Server don't support STARTTLS option");
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,
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);
}
/*
* nbd_send_meta_query:
* Send 0 or 1 set/list meta context queries.
* Return 0 on success, -1 with errp set for any error
*/
static int nbd_send_meta_query(QIOChannel *ioc, uint32_t opt,
const char *export, const char *query,
Error **errp)
{
int ret;
uint32_t export_len = strlen(export);
uint32_t queries = !!query;
uint32_t query_len = 0;
uint32_t data_len;
char *data;
char *p;
data_len = sizeof(export_len) + export_len + sizeof(queries);
if (query) {
query_len = strlen(query);
data_len += sizeof(query_len) + query_len;
} else {
assert(opt == NBD_OPT_LIST_META_CONTEXT);
}
p = data = g_malloc(data_len);
trace_nbd_opt_meta_request(nbd_opt_lookup(opt), query ?: "(all)", export);
stl_be_p(p, export_len);
memcpy(p += sizeof(export_len), export, export_len);
stl_be_p(p += export_len, queries);
if (query) {
stl_be_p(p += sizeof(queries), query_len);
memcpy(p += sizeof(query_len), query, query_len);
}
ret = nbd_send_option_request(ioc, opt, data_len, data, errp);
g_free(data);
return ret;
}
/*
* nbd_receive_one_meta_context:
* Called in a loop to receive and trace one set/list meta context reply.
* Pass non-NULL @name or @id to collect results back to the caller, which
* must eventually call g_free().
* return 1 if name is set and iteration must continue,
* 0 if iteration is complete (including if option is unsupported),
* -1 with errp set for any error
*/
static int nbd_receive_one_meta_context(QIOChannel *ioc,
uint32_t opt,
char **name,
uint32_t *id,
Error **errp)
{
int ret;
NBDOptionReply reply;
char *local_name = NULL;
uint32_t local_id;
if (nbd_receive_option_reply(ioc, opt, &reply, errp) < 0) {
return -1;
}
ret = nbd_handle_reply_err(ioc, &reply, errp);
if (ret <= 0) {
return ret;
}
if (reply.type == NBD_REP_ACK) {
if (reply.length != 0) {
error_setg(errp, "Unexpected length to ACK response");
nbd_send_opt_abort(ioc);
return -1;
}
return 0;
} else if (reply.type != NBD_REP_META_CONTEXT) {
error_setg(errp, "Unexpected reply type %u (%s), expected %u (%s)",
reply.type, nbd_rep_lookup(reply.type),
NBD_REP_META_CONTEXT, nbd_rep_lookup(NBD_REP_META_CONTEXT));
nbd_send_opt_abort(ioc);
return -1;
}
if (reply.length <= sizeof(local_id) ||
reply.length > NBD_MAX_BUFFER_SIZE) {
error_setg(errp, "Failed to negotiate meta context, server "
"answered with unexpected length %" PRIu32,
reply.length);
nbd_send_opt_abort(ioc);
return -1;
}
if (nbd_read(ioc, &local_id, sizeof(local_id), errp) < 0) {
return -1;
}
local_id = be32_to_cpu(local_id);
reply.length -= sizeof(local_id);
local_name = g_malloc(reply.length + 1);
if (nbd_read(ioc, local_name, reply.length, errp) < 0) {
g_free(local_name);
return -1;
}
local_name[reply.length] = '\0';
trace_nbd_opt_meta_reply(nbd_opt_lookup(opt), local_name, local_id);
if (name) {
*name = local_name;
} else {
g_free(local_name);
}
if (id) {
*id = local_id;
}
return 1;
}
/*
* nbd_negotiate_simple_meta_context:
* Request the server to set the meta context for export @info->name
* using @info->x_dirty_bitmap with a fallback to "base:allocation",
* setting @info->context_id to the resulting id. Fail if the server
* responds with more than one context or with a context different
* than the query.
* return 1 for successful negotiation,
* 0 if operation is unsupported,
* -1 with errp set for any other error
*/
static int nbd_negotiate_simple_meta_context(QIOChannel *ioc,
NBDExportInfo *info,
Error **errp)
{
/*
* TODO: Removing the x_dirty_bitmap hack will mean refactoring
* this function to request and store ids for multiple contexts
* (both base:allocation and a dirty bitmap), at which point this
* function should lose the term _simple.
*/
int ret;
const char *context = info->x_dirty_bitmap ?: "base:allocation";
bool received = false;
char *name = NULL;
if (nbd_send_meta_query(ioc, NBD_OPT_SET_META_CONTEXT,
info->name, context, errp) < 0) {
return -1;
}
ret = nbd_receive_one_meta_context(ioc, NBD_OPT_SET_META_CONTEXT,
&name, &info->context_id, errp);
if (ret < 0) {
return -1;
}
if (ret == 1) {
if (strcmp(context, name)) {
error_setg(errp, "Failed to negotiate meta context '%s', server "
"answered with different context '%s'", context,
name);
g_free(name);
nbd_send_opt_abort(ioc);
return -1;
}
g_free(name);
received = true;
ret = nbd_receive_one_meta_context(ioc, NBD_OPT_SET_META_CONTEXT,
NULL, NULL, errp);
if (ret < 0) {
return -1;
}
}
if (ret != 0) {
error_setg(errp, "Server answered with more than one context");
nbd_send_opt_abort(ioc);
return -1;
}
return received;
}
/*
* nbd_list_meta_contexts:
* Request the server to list all meta contexts for export @info->name.
* return 0 if list is complete (even if empty),
* -1 with errp set for any error
*/
static int nbd_list_meta_contexts(QIOChannel *ioc,
NBDExportInfo *info,
Error **errp)
{
int ret;
int seen_any = false;
int seen_qemu = false;
if (nbd_send_meta_query(ioc, NBD_OPT_LIST_META_CONTEXT,
info->name, NULL, errp) < 0) {
return -1;
}
while (1) {
char *context;
ret = nbd_receive_one_meta_context(ioc, NBD_OPT_LIST_META_CONTEXT,
&context, NULL, errp);
if (ret == 0 && seen_any && !seen_qemu) {
/*
* Work around qemu 3.0 bug: the server forgot to send
* "qemu:" replies to 0 queries. If we saw at least one
* reply (probably base:allocation), but none of them were
* qemu:, then run a more specific query to make sure.
*/
seen_qemu = true;
if (nbd_send_meta_query(ioc, NBD_OPT_LIST_META_CONTEXT,
info->name, "qemu:", errp) < 0) {
return -1;
}
continue;
}
if (ret <= 0) {
return ret;
}
seen_any = true;
seen_qemu |= strstart(context, "qemu:", NULL);
info->contexts = g_renew(char *, info->contexts, ++info->n_contexts);
info->contexts[info->n_contexts - 1] = context;
}
}
/*
* nbd_start_negotiate:
* Start the handshake to the server. After a positive return, the server
* is ready to accept additional NBD_OPT requests.
* Returns: negative errno: failure talking to server
* 0: server is oldstyle, must call nbd_negotiate_finish_oldstyle
* 1: server is newstyle, but can only accept EXPORT_NAME
* 2: server is newstyle, but lacks structured replies
* 3: server is newstyle and set up for structured replies
*/
static int nbd_start_negotiate(QIOChannel *ioc, QCryptoTLSCreds *tlscreds,
const char *hostname, QIOChannel **outioc,
bool structured_reply, bool *zeroes,
Error **errp)
{
uint64_t magic;
trace_nbd_start_negotiate(tlscreds, hostname ? hostname : "<null>");
if (zeroes) {
*zeroes = true;
}
if (outioc) {
*outioc = NULL;
}
if (tlscreds && !outioc) {
error_setg(errp, "Output I/O channel required for TLS");
return -EINVAL;
}
if (nbd_read(ioc, &magic, sizeof(magic), errp) < 0) {
error_prepend(errp, "Failed to read initial magic: ");
return -EINVAL;
}
magic = be64_to_cpu(magic);
trace_nbd_receive_negotiate_magic(magic);
if (magic != NBD_INIT_MAGIC) {
error_setg(errp, "Bad initial magic received: 0x%" PRIx64, magic);
return -EINVAL;
}
if (nbd_read(ioc, &magic, sizeof(magic), errp) < 0) {
error_prepend(errp, "Failed to read server magic: ");
return -EINVAL;
}
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: ");
return -EINVAL;
}
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) {
if (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: ");
return -EINVAL;
}
if (tlscreds) {
if (fixedNewStyle) {
*outioc = nbd_receive_starttls(ioc, tlscreds, hostname, errp);
if (!*outioc) {
return -EINVAL;
}
ioc = *outioc;
} else {
error_setg(errp, "Server does not support STARTTLS");
return -EINVAL;
}
}
if (fixedNewStyle) {
int result = 0;
if (structured_reply) {
result = nbd_request_simple_option(ioc,
NBD_OPT_STRUCTURED_REPLY,
errp);
if (result < 0) {
return -EINVAL;
}
}
return 2 + result;
} else {
return 1;
}
} else if (magic == NBD_CLIENT_MAGIC) {
if (tlscreds) {
error_setg(errp, "Server does not support STARTTLS");
return -EINVAL;
}
return 0;
} else {
error_setg(errp, "Bad server magic received: 0x%" PRIx64, magic);
return -EINVAL;
}
}
/*
* nbd_negotiate_finish_oldstyle:
* Populate @info with the size and export flags from an oldstyle server,
* but does not consume 124 bytes of reserved zero padding.
* Returns 0 on success, -1 with @errp set on failure
*/
static int nbd_negotiate_finish_oldstyle(QIOChannel *ioc, NBDExportInfo *info,
Error **errp)
{
uint32_t oldflags;
if (nbd_read(ioc, &info->size, sizeof(info->size), errp) < 0) {
error_prepend(errp, "Failed to read export length: ");
return -EINVAL;
}
info->size = be64_to_cpu(info->size);
if (nbd_read(ioc, &oldflags, sizeof(oldflags), errp) < 0) {
error_prepend(errp, "Failed to read export flags: ");
return -EINVAL;
}
oldflags = be32_to_cpu(oldflags);
if (oldflags & ~0xffff) {
error_setg(errp, "Unexpected export flags %0x" PRIx32, oldflags);
return -EINVAL;
}
info->flags = oldflags;
return 0;
}
/*
* nbd_receive_negotiate:
* Connect to server, complete negotiation, and move into transmission phase.
* Returns: negative errno: failure talking to server
* 0: server is connected
*/
int nbd_receive_negotiate(QIOChannel *ioc, QCryptoTLSCreds *tlscreds,
const char *hostname, QIOChannel **outioc,
NBDExportInfo *info, Error **errp)
{
int result;
bool zeroes;
bool base_allocation = info->base_allocation;
assert(info->name);
trace_nbd_receive_negotiate_name(info->name);
result = nbd_start_negotiate(ioc, tlscreds, hostname, outioc,
info->structured_reply, &zeroes, errp);
info->structured_reply = false;
info->base_allocation = false;
if (tlscreds && *outioc) {
ioc = *outioc;
}
switch (result) {
case 3: /* newstyle, with structured replies */
info->structured_reply = true;
if (base_allocation) {
result = nbd_negotiate_simple_meta_context(ioc, info, errp);
if (result < 0) {
return -EINVAL;
}
info->base_allocation = result == 1;
}
/* fall through */
case 2: /* newstyle, try OPT_GO */
/* 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_info_or_go(ioc, NBD_OPT_GO, info, errp);
if (result < 0) {
return -EINVAL;
}
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, info->name, errp) < 0) {
return -EINVAL;
}
/* fall through */
case 1: /* newstyle, but limited to EXPORT_NAME */
/* write the export name request */
if (nbd_send_option_request(ioc, NBD_OPT_EXPORT_NAME, -1, info->name,
errp) < 0) {
return -EINVAL;
}
/* Read the response */
if (nbd_read(ioc, &info->size, sizeof(info->size), errp) < 0) {
error_prepend(errp, "Failed to read export length: ");
return -EINVAL;
}
info->size = be64_to_cpu(info->size);
if (nbd_read(ioc, &info->flags, sizeof(info->flags), errp) < 0) {
error_prepend(errp, "Failed to read export flags: ");
return -EINVAL;
}
info->flags = be16_to_cpu(info->flags);
break;
case 0: /* oldstyle, parse length and flags */
if (*info->name) {
error_setg(errp, "Server does not support non-empty export names");
return -EINVAL;
}
if (nbd_negotiate_finish_oldstyle(ioc, info, errp) < 0) {
return -EINVAL;
}
break;
default:
return result;
}
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: ");
return -EINVAL;
}
return 0;
}
/* Clean up result of nbd_receive_export_list */
void nbd_free_export_list(NBDExportInfo *info, int count)
{
int i, j;
if (!info) {
return;
}
for (i = 0; i < count; i++) {
g_free(info[i].name);
g_free(info[i].description);
for (j = 0; j < info[i].n_contexts; j++) {
g_free(info[i].contexts[j]);
}
g_free(info[i].contexts);
}
g_free(info);
}
/*
* nbd_receive_export_list:
* Query details about a server's exports, then disconnect without
* going into transmission phase. Return a count of the exports listed
* in @info by the server, or -1 on error. Caller must free @info using
* nbd_free_export_list().
*/
int nbd_receive_export_list(QIOChannel *ioc, QCryptoTLSCreds *tlscreds,
const char *hostname, NBDExportInfo **info,
Error **errp)
{
int result;
int count = 0;
int i;
int rc;
int ret = -1;
NBDExportInfo *array = NULL;
QIOChannel *sioc = NULL;
*info = NULL;
result = nbd_start_negotiate(ioc, tlscreds, hostname, &sioc, true, NULL,
errp);
if (tlscreds && sioc) {
ioc = sioc;
}
switch (result) {
case 2:
case 3:
/* newstyle - use NBD_OPT_LIST to populate array, then try
* NBD_OPT_INFO on each array member. If structured replies
* are enabled, also try NBD_OPT_LIST_META_CONTEXT. */
if (nbd_send_option_request(ioc, NBD_OPT_LIST, 0, NULL, errp) < 0) {
goto out;
}
while (1) {
char *name;
char *desc;
rc = nbd_receive_list(ioc, &name, &desc, errp);
if (rc < 0) {
goto out;
} else if (rc == 0) {
break;
}
array = g_renew(NBDExportInfo, array, ++count);
memset(&array[count - 1], 0, sizeof(*array));
array[count - 1].name = name;
array[count - 1].description = desc;
array[count - 1].structured_reply = result == 3;
}
for (i = 0; i < count; i++) {
array[i].request_sizes = true;
rc = nbd_opt_info_or_go(ioc, NBD_OPT_INFO, &array[i], errp);
if (rc < 0) {
goto out;
} else if (rc == 0) {
/*
* Pointless to try rest of loop. If OPT_INFO doesn't work,
* it's unlikely that meta contexts work either
*/
break;
}
if (result == 3 &&
nbd_list_meta_contexts(ioc, &array[i], errp) < 0) {
goto out;
}
}
/* Send NBD_OPT_ABORT as a courtesy before hanging up */
nbd_send_opt_abort(ioc);
break;
case 1: /* newstyle, but limited to EXPORT_NAME */
error_setg(errp, "Server does not support export lists");
/* We can't even send NBD_OPT_ABORT, so merely hang up */
goto out;
case 0: /* oldstyle, parse length and flags */
array = g_new0(NBDExportInfo, 1);
array->name = g_strdup("");
count = 1;
if (nbd_negotiate_finish_oldstyle(ioc, array, errp) < 0) {
goto out;
}
/* Send NBD_CMD_DISC as a courtesy to the server, but ignore all
* errors now that we have the information we wanted. */
if (nbd_drop(ioc, 124, NULL) == 0) {
NBDRequest request = { .type = NBD_CMD_DISC };
nbd_send_request(ioc, &request);
}
break;
default:
goto out;
}
*info = array;
array = NULL;
ret = count;
out:
qio_channel_shutdown(ioc, QIO_CHANNEL_SHUTDOWN_BOTH, NULL);
qio_channel_close(ioc, NULL);
object_unref(OBJECT(sioc));
nbd_free_export_list(array, count);
return ret;
}
#ifdef __linux__
int nbd_init(int fd, QIOChannelSocket *sioc, NBDExportInfo *info,
Error **errp)
{
unsigned long sector_size = MAX(BDRV_SECTOR_SIZE, info->min_block);
unsigned long sectors = info->size / sector_size;
/* FIXME: Once the kernel module is patched to honor block sizes,
* and to advertise that fact to user space, we should update the
* hand-off to the kernel to use any block sizes we learned. */
assert(!info->request_sizes);
if (info->size / sector_size != sectors) {
error_setg(errp, "Export size %" PRIu64 " too large for 32-bit kernel",
info->size);
return -E2BIG;
}
trace_nbd_init_set_socket();
if (ioctl(fd, NBD_SET_SOCK, (unsigned long) sioc->fd) < 0) {
int serrno = errno;
error_setg(errp, "Failed to set NBD socket");
return -serrno;
}
trace_nbd_init_set_block_size(sector_size);
if (ioctl(fd, NBD_SET_BLKSIZE, sector_size) < 0) {
int serrno = errno;
error_setg(errp, "Failed setting NBD block size");
return -serrno;
}
trace_nbd_init_set_size(sectors);
if (info->size % sector_size) {
trace_nbd_init_trailing_bytes(info->size % sector_size);
}
if (ioctl(fd, NBD_SET_SIZE_BLOCKS, sectors) < 0) {
int serrno = errno;
error_setg(errp, "Failed setting size (in blocks)");
return -serrno;
}
if (ioctl(fd, NBD_SET_FLAGS, (unsigned long) info->flags) < 0) {
if (errno == ENOTTY) {
int read_only = (info->flags & NBD_FLAG_READ_ONLY) != 0;
trace_nbd_init_set_readonly();
if (ioctl(fd, BLKROSET, (unsigned long) &read_only) < 0) {
int serrno = errno;
error_setg(errp, "Failed setting read-only attribute");
return -serrno;
}
} else {
int serrno = errno;
error_setg(errp, "Failed setting flags");
return -serrno;
}
}
trace_nbd_init_finish();
return 0;
}
int nbd_client(int fd)
{
int ret;
int serrno;
trace_nbd_client_loop();
ret = ioctl(fd, NBD_DO_IT);
if (ret < 0 && errno == EPIPE) {
/* NBD_DO_IT normally returns EPIPE when someone has disconnected
* the socket via NBD_DISCONNECT. We do not want to return 1 in
* that case.
*/
ret = 0;
}
serrno = errno;
trace_nbd_client_loop_ret(ret, strerror(serrno));
trace_nbd_client_clear_queue();
ioctl(fd, NBD_CLEAR_QUE);
trace_nbd_client_clear_socket();
ioctl(fd, NBD_CLEAR_SOCK);
errno = serrno;
return ret;
}
int nbd_disconnect(int fd)
{
ioctl(fd, NBD_CLEAR_QUE);
ioctl(fd, NBD_DISCONNECT);
ioctl(fd, NBD_CLEAR_SOCK);
return 0;
}
#endif /* __linux__ */
int nbd_send_request(QIOChannel *ioc, NBDRequest *request)
{
uint8_t buf[NBD_REQUEST_SIZE];
trace_nbd_send_request(request->from, request->len, request->handle,
request->flags, request->type,
nbd_cmd_lookup(request->type));
stl_be_p(buf, NBD_REQUEST_MAGIC);
stw_be_p(buf + 4, request->flags);
stw_be_p(buf + 6, request->type);
stq_be_p(buf + 8, request->handle);
stq_be_p(buf + 16, request->from);
stl_be_p(buf + 24, request->len);
return nbd_write(ioc, buf, sizeof(buf), NULL);
}
/* nbd_receive_simple_reply
* Read simple reply except magic field (which should be already read).
* Payload is not read (payload is possible for CMD_READ, but here we even
* don't know whether it take place or not).
*/
static int nbd_receive_simple_reply(QIOChannel *ioc, NBDSimpleReply *reply,
Error **errp)
{
int ret;
assert(reply->magic == NBD_SIMPLE_REPLY_MAGIC);
ret = nbd_read(ioc, (uint8_t *)reply + sizeof(reply->magic),
sizeof(*reply) - sizeof(reply->magic), errp);
if (ret < 0) {
return ret;
}
reply->error = be32_to_cpu(reply->error);
reply->handle = be64_to_cpu(reply->handle);
return 0;
}
/* nbd_receive_structured_reply_chunk
* Read structured reply chunk except magic field (which should be already
* read).
* Payload is not read.
*/
static int nbd_receive_structured_reply_chunk(QIOChannel *ioc,
NBDStructuredReplyChunk *chunk,
Error **errp)
{
int ret;
assert(chunk->magic == NBD_STRUCTURED_REPLY_MAGIC);
ret = nbd_read(ioc, (uint8_t *)chunk + sizeof(chunk->magic),
sizeof(*chunk) - sizeof(chunk->magic), errp);
if (ret < 0) {
return ret;
}
chunk->flags = be16_to_cpu(chunk->flags);
chunk->type = be16_to_cpu(chunk->type);
chunk->handle = be64_to_cpu(chunk->handle);
chunk->length = be32_to_cpu(chunk->length);
return 0;
}
/* nbd_receive_reply
* Returns 1 on success
* 0 on eof, when no data was read (errp is not set)
* negative errno on failure (errp is set)
*/
int nbd_receive_reply(QIOChannel *ioc, NBDReply *reply, Error **errp)
{
int ret;
const char *type;
ret = nbd_read_eof(ioc, &reply->magic, sizeof(reply->magic), errp);
if (ret <= 0) {
return ret;
}
reply->magic = be32_to_cpu(reply->magic);
switch (reply->magic) {
case NBD_SIMPLE_REPLY_MAGIC:
ret = nbd_receive_simple_reply(ioc, &reply->simple, errp);
if (ret < 0) {
break;
}
trace_nbd_receive_simple_reply(reply->simple.error,
nbd_err_lookup(reply->simple.error),
reply->handle);
break;
case NBD_STRUCTURED_REPLY_MAGIC:
ret = nbd_receive_structured_reply_chunk(ioc, &reply->structured, errp);
if (ret < 0) {
break;
}
type = nbd_reply_type_lookup(reply->structured.type);
trace_nbd_receive_structured_reply_chunk(reply->structured.flags,
reply->structured.type, type,
reply->structured.handle,
reply->structured.length);
break;
default:
error_setg(errp, "invalid magic (got 0x%" PRIx32 ")", reply->magic);
return -EINVAL;
}
if (ret < 0) {
return ret;
}
return 1;
}
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