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qemu/nbd/client.c
Eric Blake 3add3ab782 nbd/client: Reject inaccessible tail of inconsistent server 
The NBD spec suggests that a server should never advertise a size
inconsistent with its minimum block alignment, as that tail is
effectively inaccessible to a compliant client obeying those block
constraints. Since we have a habit of rounding up rather than
truncating, to avoid losing the last few bytes of user input, and we
cannot access the tail when the server advertises bogus block sizing,
abort the connection to alert the server to fix their bug.  And
rejecting such servers matches what we already did for a min_block
that was not a power of 2 or which was larger than max_block.

Does not impact either qemu (which always sends properly aligned
sizes) or nbdkit (which does not send minimum block requirements yet);
so this is mostly aimed at new NBD server implementations, and ensures
that the rest of our code can assume the size is aligned.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20190330155704.24191-1-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
2019-04-01 08:31:16 -05:00

1495 lines
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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), "option reply", errp) < 0) {
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, NULL, 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_read32(ioc, &namelen, "option name length", errp) < 0) {
nbd_send_opt_abort(ioc);
return -1;
}
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, "export name", errp) < 0) {
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, "export description", errp) < 0) {
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_read16(ioc, &type, "info type", errp) < 0) {
nbd_send_opt_abort(ioc);
return -1;
}
len -= sizeof(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_read64(ioc, &info->size, "info size", errp) < 0) {
nbd_send_opt_abort(ioc);
return -1;
}
if (nbd_read16(ioc, &info->flags, "info flags", errp) < 0) {
nbd_send_opt_abort(ioc);
return -1;
}
if (info->min_block &&
!QEMU_IS_ALIGNED(info->size, info->min_block)) {
error_setg(errp, "export size %" PRIu64 "is not multiple of "
"minimum block size %" PRIu32, info->size,
info->min_block);
nbd_send_opt_abort(ioc);
return -1;
}
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_read32(ioc, &info->min_block, "info minimum block size",
errp) < 0) {
nbd_send_opt_abort(ioc);
return -1;
}
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_read32(ioc, &info->opt_block, "info preferred block size",
errp) < 0)
{
nbd_send_opt_abort(ioc);
return -1;
}
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_read32(ioc, &info->max_block, "info maximum block size",
errp) < 0)
{
nbd_send_opt_abort(ioc);
return -1;
}
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_read32(ioc, &local_id, "context id", errp) < 0) {
return -1;
}
reply.length -= sizeof(local_id);
local_name = g_malloc(reply.length + 1);
if (nbd_read(ioc, local_name, reply.length, "context name", 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_read64(ioc, &magic, "initial magic", errp) < 0) {
return -EINVAL;
}
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_read64(ioc, &magic, "server magic", errp) < 0) {
return -EINVAL;
}
trace_nbd_receive_negotiate_magic(magic);
if (magic == NBD_OPTS_MAGIC) {
uint32_t clientflags = 0;
uint16_t globalflags;
bool fixedNewStyle = false;
if (nbd_read16(ioc, &globalflags, "server flags", errp) < 0) {
return -EINVAL;
}
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_read64(ioc, &info->size, "export length", errp) < 0) {
return -EINVAL;
}
if (nbd_read32(ioc, &oldflags, "export flags", errp) < 0) {
return -EINVAL;
}
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_read64(ioc, &info->size, "export length", errp) < 0) {
return -EINVAL;
}
if (nbd_read16(ioc, &info->flags, "export flags", errp) < 0) {
return -EINVAL;
}
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), "reply", 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), "structured chunk",
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_read_eof
* Tries to read @size bytes from @ioc.
* Returns 1 on success
* 0 on eof, when no data was read (errp is not set)
* negative errno on failure (errp is set)
*/
static inline int coroutine_fn
nbd_read_eof(BlockDriverState *bs, QIOChannel *ioc, void *buffer, size_t size,
Error **errp)
{
bool partial = false;
assert(size);
while (size > 0) {
struct iovec iov = { .iov_base = buffer, .iov_len = size };
ssize_t len;
len = qio_channel_readv(ioc, &iov, 1, errp);
if (len == QIO_CHANNEL_ERR_BLOCK) {
bdrv_dec_in_flight(bs);
qio_channel_yield(ioc, G_IO_IN);
bdrv_inc_in_flight(bs);
continue;
} else if (len < 0) {
return -EIO;
} else if (len == 0) {
if (partial) {
error_setg(errp,
"Unexpected end-of-file before all bytes were read");
return -EIO;
} else {
return 0;
}
}
partial = true;
size -= len;
buffer = (uint8_t*) buffer + len;
}
return 1;
}
/* nbd_receive_reply
*
* Decreases bs->in_flight while waiting for a new reply. This yield is where
* we wait indefinitely and the coroutine must be able to be safely reentered
* for nbd_client_attach_aio_context().
*
* Returns 1 on success
* 0 on eof, when no data was read (errp is not set)
* negative errno on failure (errp is set)
*/
int coroutine_fn nbd_receive_reply(BlockDriverState *bs, QIOChannel *ioc,
NBDReply *reply, Error **errp)
{
int ret;
const char *type;
ret = nbd_read_eof(bs, 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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