/* * Copyright Red Hat * Copyright (C) 2005 Anthony Liguori * * 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 . */ #include "qemu/osdep.h" #include "qapi/error.h" #include "qemu/queue.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) { ERRP_GUARD(); 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), where @strict determines if only * ERR_UNSUP or all errors fit that category, or -1 with errp set for * other errors. */ static int nbd_handle_reply_err(QIOChannel *ioc, NBDOptionReply *reply, bool strict, Error **errp) { ERRP_GUARD(); g_autofree char *msg = NULL; 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 err; } 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 err; } msg[reply->length] = '\0'; trace_nbd_server_error_msg(reply->type, nbd_reply_type_lookup(reply->type), msg); } if (reply->type == NBD_REP_ERR_UNSUP || !strict) { trace_nbd_reply_err_ignored(reply->option, nbd_opt_lookup(reply->option), reply->type, nbd_rep_lookup(reply->type)); return 0; } switch (reply->type) { 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)); error_append_hint(errp, "Did you forget a valid tls-creds?\n"); 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); } err: nbd_send_opt_abort(ioc); return -1; } /* 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) { NBDOptionReply reply; uint32_t len; uint32_t namelen; g_autofree char *local_name = NULL; g_autofree 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, true, 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 || namelen > NBD_MAX_STRING_SIZE) { error_setg(errp, "incorrect name length in server's list response"); 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); return -1; } local_name[namelen] = '\0'; len -= namelen; if (len) { if (len > NBD_MAX_STRING_SIZE) { error_setg(errp, "incorrect description length in server's " "list response"); nbd_send_opt_abort(ioc); return -1; } local_desc = g_malloc(len + 1); if (nbd_read(ioc, local_desc, len, "export description", errp) < 0) { nbd_send_opt_abort(ioc); return -1; } local_desc[len] = '\0'; } trace_nbd_receive_list(local_name, local_desc ?: ""); *name = g_steal_pointer(&local_name); if (description) { *description = g_steal_pointer(&local_desc); } return 1; } /* * 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) { ERRP_GUARD(); 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, true, 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: /* * Not worth the bother to check if NBD_INFO_NAME or * NBD_INFO_DESCRIPTION exceed NBD_MAX_STRING_SIZE. */ 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. * @strict controls whether ERR_UNSUP or all errors produce 0 status. * 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, bool strict, 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, strict, 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, true, 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; uint32_t queries = !!query; uint32_t query_len = 0; uint32_t data_len; char *data; char *p; assert(strnlen(export, NBD_MAX_STRING_SIZE + 1) <= NBD_MAX_STRING_SIZE); export_len = strlen(export); data_len = sizeof(export_len) + export_len + sizeof(queries); if (query) { assert(strnlen(query, NBD_MAX_STRING_SIZE + 1) <= NBD_MAX_STRING_SIZE); 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, false, 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(AioContext *aio_context, QIOChannel *ioc, QCryptoTLSCreds *tlscreds, const char *hostname, QIOChannel **outioc, bool structured_reply, bool *zeroes, Error **errp) { ERRP_GUARD(); uint64_t magic; trace_nbd_start_negotiate(tlscreds, hostname ? hostname : ""); 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; if (aio_context) { qio_channel_set_blocking(ioc, false, NULL); qio_channel_attach_aio_context(ioc, aio_context); } } 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, false, 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(AioContext *aio_context, QIOChannel *ioc, QCryptoTLSCreds *tlscreds, const char *hostname, QIOChannel **outioc, NBDExportInfo *info, Error **errp) { ERRP_GUARD(); int result; bool zeroes; bool base_allocation = info->base_allocation; assert(info->name && strlen(info->name) <= NBD_MAX_STRING_SIZE); trace_nbd_receive_negotiate_name(info->name); result = nbd_start_negotiate(aio_context, 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(NULL, 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->cookie, 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->cookie); 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->cookie = be64_to_cpu(reply->cookie); 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->cookie = be64_to_cpu(chunk->cookie); 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) { qio_channel_yield(ioc, G_IO_IN); 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->cookie); 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.cookie, reply->structured.length); break; default: error_setg(errp, "invalid magic (got 0x%" PRIx32 ")", reply->magic); return -EINVAL; } if (ret < 0) { return ret; } return 1; }