/* * Copyright (C) 2016-2018 Red Hat, Inc. * Copyright (C) 2005 Anthony Liguori <anthony@codemonkey.ws> * * Network Block Device Server 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" #define NBD_META_ID_BASE_ALLOCATION 0 #define NBD_META_ID_DIRTY_BITMAP 1 /* NBD_MAX_BITMAP_EXTENTS: 1 mb of extents data. An empirical * constant. If an increase is needed, note that the NBD protocol * recommends no larger than 32 mb, so that the client won't consider * the reply as a denial of service attack. */ #define NBD_MAX_BITMAP_EXTENTS (0x100000 / 8) static int system_errno_to_nbd_errno(int err) { switch (err) { case 0: return NBD_SUCCESS; case EPERM: case EROFS: return NBD_EPERM; case EIO: return NBD_EIO; case ENOMEM: return NBD_ENOMEM; #ifdef EDQUOT case EDQUOT: #endif case EFBIG: case ENOSPC: return NBD_ENOSPC; case EOVERFLOW: return NBD_EOVERFLOW; case ESHUTDOWN: return NBD_ESHUTDOWN; case EINVAL: default: return NBD_EINVAL; } } /* Definitions for opaque data types */ typedef struct NBDRequestData NBDRequestData; struct NBDRequestData { QSIMPLEQ_ENTRY(NBDRequestData) entry; NBDClient *client; uint8_t *data; bool complete; }; struct NBDExport { int refcount; void (*close)(NBDExport *exp); BlockBackend *blk; char *name; char *description; uint64_t dev_offset; uint64_t size; uint16_t nbdflags; QTAILQ_HEAD(, NBDClient) clients; QTAILQ_ENTRY(NBDExport) next; AioContext *ctx; BlockBackend *eject_notifier_blk; Notifier eject_notifier; BdrvDirtyBitmap *export_bitmap; char *export_bitmap_context; }; static QTAILQ_HEAD(, NBDExport) exports = QTAILQ_HEAD_INITIALIZER(exports); /* NBDExportMetaContexts represents a list of contexts to be exported, * as selected by NBD_OPT_SET_META_CONTEXT. Also used for * NBD_OPT_LIST_META_CONTEXT. */ typedef struct NBDExportMetaContexts { NBDExport *exp; bool valid; /* means that negotiation of the option finished without errors */ bool base_allocation; /* export base:allocation context (block status) */ bool bitmap; /* export qemu:dirty-bitmap:<export bitmap name> */ } NBDExportMetaContexts; struct NBDClient { int refcount; void (*close_fn)(NBDClient *client, bool negotiated); NBDExport *exp; QCryptoTLSCreds *tlscreds; char *tlsauthz; QIOChannelSocket *sioc; /* The underlying data channel */ QIOChannel *ioc; /* The current I/O channel which may differ (eg TLS) */ Coroutine *recv_coroutine; CoMutex send_lock; Coroutine *send_coroutine; QTAILQ_ENTRY(NBDClient) next; int nb_requests; bool closing; uint32_t check_align; /* If non-zero, check for aligned client requests */ bool structured_reply; NBDExportMetaContexts export_meta; uint32_t opt; /* Current option being negotiated */ uint32_t optlen; /* remaining length of data in ioc for the option being negotiated now */ }; static void nbd_client_receive_next_request(NBDClient *client); /* 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) */ static inline void set_be_option_rep(NBDOptionReply *rep, uint32_t option, uint32_t type, uint32_t length) { stq_be_p(&rep->magic, NBD_REP_MAGIC); stl_be_p(&rep->option, option); stl_be_p(&rep->type, type); stl_be_p(&rep->length, length); } /* Send a reply header, including length, but no payload. * Return -errno on error, 0 on success. */ static int nbd_negotiate_send_rep_len(NBDClient *client, uint32_t type, uint32_t len, Error **errp) { NBDOptionReply rep; trace_nbd_negotiate_send_rep_len(client->opt, nbd_opt_lookup(client->opt), type, nbd_rep_lookup(type), len); assert(len < NBD_MAX_BUFFER_SIZE); set_be_option_rep(&rep, client->opt, type, len); return nbd_write(client->ioc, &rep, sizeof(rep), errp); } /* Send a reply header with default 0 length. * Return -errno on error, 0 on success. */ static int nbd_negotiate_send_rep(NBDClient *client, uint32_t type, Error **errp) { return nbd_negotiate_send_rep_len(client, type, 0, errp); } /* Send an error reply. * Return -errno on error, 0 on success. */ static int GCC_FMT_ATTR(4, 0) nbd_negotiate_send_rep_verr(NBDClient *client, uint32_t type, Error **errp, const char *fmt, va_list va) { char *msg; int ret; size_t len; msg = g_strdup_vprintf(fmt, va); len = strlen(msg); assert(len < 4096); trace_nbd_negotiate_send_rep_err(msg); ret = nbd_negotiate_send_rep_len(client, type, len, errp); if (ret < 0) { goto out; } if (nbd_write(client->ioc, msg, len, errp) < 0) { error_prepend(errp, "write failed (error message): "); ret = -EIO; } else { ret = 0; } out: g_free(msg); return ret; } /* Send an error reply. * Return -errno on error, 0 on success. */ static int GCC_FMT_ATTR(4, 5) nbd_negotiate_send_rep_err(NBDClient *client, uint32_t type, Error **errp, const char *fmt, ...) { va_list va; int ret; va_start(va, fmt); ret = nbd_negotiate_send_rep_verr(client, type, errp, fmt, va); va_end(va); return ret; } /* Drop remainder of the current option, and send a reply with the * given error type and message. Return -errno on read or write * failure; or 0 if connection is still live. */ static int GCC_FMT_ATTR(4, 0) nbd_opt_vdrop(NBDClient *client, uint32_t type, Error **errp, const char *fmt, va_list va) { int ret = nbd_drop(client->ioc, client->optlen, errp); client->optlen = 0; if (!ret) { ret = nbd_negotiate_send_rep_verr(client, type, errp, fmt, va); } return ret; } static int GCC_FMT_ATTR(4, 5) nbd_opt_drop(NBDClient *client, uint32_t type, Error **errp, const char *fmt, ...) { int ret; va_list va; va_start(va, fmt); ret = nbd_opt_vdrop(client, type, errp, fmt, va); va_end(va); return ret; } static int GCC_FMT_ATTR(3, 4) nbd_opt_invalid(NBDClient *client, Error **errp, const char *fmt, ...) { int ret; va_list va; va_start(va, fmt); ret = nbd_opt_vdrop(client, NBD_REP_ERR_INVALID, errp, fmt, va); va_end(va); return ret; } /* Read size bytes from the unparsed payload of the current option. * Return -errno on I/O error, 0 if option was completely handled by * sending a reply about inconsistent lengths, or 1 on success. */ static int nbd_opt_read(NBDClient *client, void *buffer, size_t size, Error **errp) { if (size > client->optlen) { return nbd_opt_invalid(client, errp, "Inconsistent lengths in option %s", nbd_opt_lookup(client->opt)); } client->optlen -= size; return qio_channel_read_all(client->ioc, buffer, size, errp) < 0 ? -EIO : 1; } /* Drop size bytes from the unparsed payload of the current option. * Return -errno on I/O error, 0 if option was completely handled by * sending a reply about inconsistent lengths, or 1 on success. */ static int nbd_opt_skip(NBDClient *client, size_t size, Error **errp) { if (size > client->optlen) { return nbd_opt_invalid(client, errp, "Inconsistent lengths in option %s", nbd_opt_lookup(client->opt)); } client->optlen -= size; return nbd_drop(client->ioc, size, errp) < 0 ? -EIO : 1; } /* nbd_opt_read_name * * Read a string with the format: * uint32_t len (<= NBD_MAX_NAME_SIZE) * len bytes string (not 0-terminated) * * @name should be enough to store NBD_MAX_NAME_SIZE+1. * If @length is non-null, it will be set to the actual string length. * * Return -errno on I/O error, 0 if option was completely handled by * sending a reply about inconsistent lengths, or 1 on success. */ static int nbd_opt_read_name(NBDClient *client, char *name, uint32_t *length, Error **errp) { int ret; uint32_t len; ret = nbd_opt_read(client, &len, sizeof(len), errp); if (ret <= 0) { return ret; } len = cpu_to_be32(len); if (len > NBD_MAX_NAME_SIZE) { return nbd_opt_invalid(client, errp, "Invalid name length: %" PRIu32, len); } ret = nbd_opt_read(client, name, len, errp); if (ret <= 0) { return ret; } name[len] = '\0'; if (length) { *length = len; } return 1; } /* Send a single NBD_REP_SERVER reply to NBD_OPT_LIST, including payload. * Return -errno on error, 0 on success. */ static int nbd_negotiate_send_rep_list(NBDClient *client, NBDExport *exp, Error **errp) { size_t name_len, desc_len; uint32_t len; const char *name = exp->name ? exp->name : ""; const char *desc = exp->description ? exp->description : ""; QIOChannel *ioc = client->ioc; int ret; trace_nbd_negotiate_send_rep_list(name, desc); name_len = strlen(name); desc_len = strlen(desc); len = name_len + desc_len + sizeof(len); ret = nbd_negotiate_send_rep_len(client, NBD_REP_SERVER, len, errp); if (ret < 0) { return ret; } len = cpu_to_be32(name_len); if (nbd_write(ioc, &len, sizeof(len), errp) < 0) { error_prepend(errp, "write failed (name length): "); return -EINVAL; } if (nbd_write(ioc, name, name_len, errp) < 0) { error_prepend(errp, "write failed (name buffer): "); return -EINVAL; } if (nbd_write(ioc, desc, desc_len, errp) < 0) { error_prepend(errp, "write failed (description buffer): "); return -EINVAL; } return 0; } /* Process the NBD_OPT_LIST command, with a potential series of replies. * Return -errno on error, 0 on success. */ static int nbd_negotiate_handle_list(NBDClient *client, Error **errp) { NBDExport *exp; assert(client->opt == NBD_OPT_LIST); /* For each export, send a NBD_REP_SERVER reply. */ QTAILQ_FOREACH(exp, &exports, next) { if (nbd_negotiate_send_rep_list(client, exp, errp)) { return -EINVAL; } } /* Finish with a NBD_REP_ACK. */ return nbd_negotiate_send_rep(client, NBD_REP_ACK, errp); } static void nbd_check_meta_export(NBDClient *client) { client->export_meta.valid &= client->exp == client->export_meta.exp; } /* Send a reply to NBD_OPT_EXPORT_NAME. * Return -errno on error, 0 on success. */ static int nbd_negotiate_handle_export_name(NBDClient *client, uint16_t myflags, bool no_zeroes, Error **errp) { char name[NBD_MAX_NAME_SIZE + 1]; char buf[NBD_REPLY_EXPORT_NAME_SIZE] = ""; size_t len; int ret; /* Client sends: [20 .. xx] export name (length bytes) Server replies: [ 0 .. 7] size [ 8 .. 9] export flags [10 .. 133] reserved (0) [unless no_zeroes] */ trace_nbd_negotiate_handle_export_name(); if (client->optlen >= sizeof(name)) { error_setg(errp, "Bad length received"); return -EINVAL; } if (nbd_read(client->ioc, name, client->optlen, "export name", errp) < 0) { return -EIO; } name[client->optlen] = '\0'; client->optlen = 0; trace_nbd_negotiate_handle_export_name_request(name); client->exp = nbd_export_find(name); if (!client->exp) { error_setg(errp, "export not found"); return -EINVAL; } trace_nbd_negotiate_new_style_size_flags(client->exp->size, client->exp->nbdflags | myflags); stq_be_p(buf, client->exp->size); stw_be_p(buf + 8, client->exp->nbdflags | myflags); len = no_zeroes ? 10 : sizeof(buf); ret = nbd_write(client->ioc, buf, len, errp); if (ret < 0) { error_prepend(errp, "write failed: "); return ret; } QTAILQ_INSERT_TAIL(&client->exp->clients, client, next); nbd_export_get(client->exp); nbd_check_meta_export(client); return 0; } /* Send a single NBD_REP_INFO, with a buffer @buf of @length bytes. * The buffer does NOT include the info type prefix. * Return -errno on error, 0 if ready to send more. */ static int nbd_negotiate_send_info(NBDClient *client, uint16_t info, uint32_t length, void *buf, Error **errp) { int rc; trace_nbd_negotiate_send_info(info, nbd_info_lookup(info), length); rc = nbd_negotiate_send_rep_len(client, NBD_REP_INFO, sizeof(info) + length, errp); if (rc < 0) { return rc; } info = cpu_to_be16(info); if (nbd_write(client->ioc, &info, sizeof(info), errp) < 0) { return -EIO; } if (nbd_write(client->ioc, buf, length, errp) < 0) { return -EIO; } return 0; } /* nbd_reject_length: Handle any unexpected payload. * @fatal requests that we quit talking to the client, even if we are able * to successfully send an error reply. * Return: * -errno transmission error occurred or @fatal was requested, errp is set * 0 error message successfully sent to client, errp is not set */ static int nbd_reject_length(NBDClient *client, bool fatal, Error **errp) { int ret; assert(client->optlen); ret = nbd_opt_invalid(client, errp, "option '%s' has unexpected length", nbd_opt_lookup(client->opt)); if (fatal && !ret) { error_setg(errp, "option '%s' has unexpected length", nbd_opt_lookup(client->opt)); return -EINVAL; } return ret; } /* Handle NBD_OPT_INFO and NBD_OPT_GO. * Return -errno on error, 0 if ready for next option, and 1 to move * into transmission phase. */ static int nbd_negotiate_handle_info(NBDClient *client, uint16_t myflags, Error **errp) { int rc; char name[NBD_MAX_NAME_SIZE + 1]; NBDExport *exp; uint16_t requests; uint16_t request; uint32_t namelen; bool sendname = false; bool blocksize = false; uint32_t sizes[3]; char buf[sizeof(uint64_t) + sizeof(uint16_t)]; uint32_t check_align = 0; /* Client sends: 4 bytes: L, name length (can be 0) L bytes: export name 2 bytes: N, number of requests (can be 0) N * 2 bytes: N requests */ rc = nbd_opt_read_name(client, name, &namelen, errp); if (rc <= 0) { return rc; } trace_nbd_negotiate_handle_export_name_request(name); rc = nbd_opt_read(client, &requests, sizeof(requests), errp); if (rc <= 0) { return rc; } requests = be16_to_cpu(requests); trace_nbd_negotiate_handle_info_requests(requests); while (requests--) { rc = nbd_opt_read(client, &request, sizeof(request), errp); if (rc <= 0) { return rc; } request = be16_to_cpu(request); trace_nbd_negotiate_handle_info_request(request, nbd_info_lookup(request)); /* We care about NBD_INFO_NAME and NBD_INFO_BLOCK_SIZE; * everything else is either a request we don't know or * something we send regardless of request */ switch (request) { case NBD_INFO_NAME: sendname = true; break; case NBD_INFO_BLOCK_SIZE: blocksize = true; break; } } if (client->optlen) { return nbd_reject_length(client, false, errp); } exp = nbd_export_find(name); if (!exp) { return nbd_negotiate_send_rep_err(client, NBD_REP_ERR_UNKNOWN, errp, "export '%s' not present", name); } /* Don't bother sending NBD_INFO_NAME unless client requested it */ if (sendname) { rc = nbd_negotiate_send_info(client, NBD_INFO_NAME, namelen, name, errp); if (rc < 0) { return rc; } } /* Send NBD_INFO_DESCRIPTION only if available, regardless of * client request */ if (exp->description) { size_t len = strlen(exp->description); rc = nbd_negotiate_send_info(client, NBD_INFO_DESCRIPTION, len, exp->description, errp); if (rc < 0) { return rc; } } /* Send NBD_INFO_BLOCK_SIZE always, but tweak the minimum size * according to whether the client requested it, and according to * whether this is OPT_INFO or OPT_GO. */ /* minimum - 1 for back-compat, or actual if client will obey it. */ if (client->opt == NBD_OPT_INFO || blocksize) { check_align = sizes[0] = blk_get_request_alignment(exp->blk); } else { sizes[0] = 1; } assert(sizes[0] <= NBD_MAX_BUFFER_SIZE); /* preferred - Hard-code to 4096 for now. * TODO: is blk_bs(blk)->bl.opt_transfer appropriate? */ sizes[1] = MAX(4096, sizes[0]); /* maximum - At most 32M, but smaller as appropriate. */ sizes[2] = MIN(blk_get_max_transfer(exp->blk), NBD_MAX_BUFFER_SIZE); trace_nbd_negotiate_handle_info_block_size(sizes[0], sizes[1], sizes[2]); sizes[0] = cpu_to_be32(sizes[0]); sizes[1] = cpu_to_be32(sizes[1]); sizes[2] = cpu_to_be32(sizes[2]); rc = nbd_negotiate_send_info(client, NBD_INFO_BLOCK_SIZE, sizeof(sizes), sizes, errp); if (rc < 0) { return rc; } /* Send NBD_INFO_EXPORT always */ trace_nbd_negotiate_new_style_size_flags(exp->size, exp->nbdflags | myflags); stq_be_p(buf, exp->size); stw_be_p(buf + 8, exp->nbdflags | myflags); rc = nbd_negotiate_send_info(client, NBD_INFO_EXPORT, sizeof(buf), buf, errp); if (rc < 0) { return rc; } /* * If the client is just asking for NBD_OPT_INFO, but forgot to * request block sizes in a situation that would impact * performance, then return an error. But for NBD_OPT_GO, we * tolerate all clients, regardless of alignments. */ if (client->opt == NBD_OPT_INFO && !blocksize && blk_get_request_alignment(exp->blk) > 1) { return nbd_negotiate_send_rep_err(client, NBD_REP_ERR_BLOCK_SIZE_REQD, errp, "request NBD_INFO_BLOCK_SIZE to " "use this export"); } /* Final reply */ rc = nbd_negotiate_send_rep(client, NBD_REP_ACK, errp); if (rc < 0) { return rc; } if (client->opt == NBD_OPT_GO) { client->exp = exp; client->check_align = check_align; QTAILQ_INSERT_TAIL(&client->exp->clients, client, next); nbd_export_get(client->exp); nbd_check_meta_export(client); rc = 1; } return rc; } /* Handle NBD_OPT_STARTTLS. Return NULL to drop connection, or else the * new channel for all further (now-encrypted) communication. */ static QIOChannel *nbd_negotiate_handle_starttls(NBDClient *client, Error **errp) { QIOChannel *ioc; QIOChannelTLS *tioc; struct NBDTLSHandshakeData data = { 0 }; assert(client->opt == NBD_OPT_STARTTLS); trace_nbd_negotiate_handle_starttls(); ioc = client->ioc; if (nbd_negotiate_send_rep(client, NBD_REP_ACK, errp) < 0) { return NULL; } tioc = qio_channel_tls_new_server(ioc, client->tlscreds, client->tlsauthz, errp); if (!tioc) { return NULL; } qio_channel_set_name(QIO_CHANNEL(tioc), "nbd-server-tls"); trace_nbd_negotiate_handle_starttls_handshake(); data.loop = g_main_loop_new(g_main_context_default(), FALSE); 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) { object_unref(OBJECT(tioc)); error_propagate(errp, data.error); return NULL; } return QIO_CHANNEL(tioc); } /* nbd_negotiate_send_meta_context * * Send one chunk of reply to NBD_OPT_{LIST,SET}_META_CONTEXT * * For NBD_OPT_LIST_META_CONTEXT @context_id is ignored, 0 is used instead. */ static int nbd_negotiate_send_meta_context(NBDClient *client, const char *context, uint32_t context_id, Error **errp) { NBDOptionReplyMetaContext opt; struct iovec iov[] = { {.iov_base = &opt, .iov_len = sizeof(opt)}, {.iov_base = (void *)context, .iov_len = strlen(context)} }; if (client->opt == NBD_OPT_LIST_META_CONTEXT) { context_id = 0; } trace_nbd_negotiate_meta_query_reply(context, context_id); set_be_option_rep(&opt.h, client->opt, NBD_REP_META_CONTEXT, sizeof(opt) - sizeof(opt.h) + iov[1].iov_len); stl_be_p(&opt.context_id, context_id); return qio_channel_writev_all(client->ioc, iov, 2, errp) < 0 ? -EIO : 0; } /* Read strlen(@pattern) bytes, and set @match to true if they match @pattern. * @match is never set to false. * * Return -errno on I/O error, 0 if option was completely handled by * sending a reply about inconsistent lengths, or 1 on success. * * Note: return code = 1 doesn't mean that we've read exactly @pattern. * It only means that there are no errors. */ static int nbd_meta_pattern(NBDClient *client, const char *pattern, bool *match, Error **errp) { int ret; char *query; size_t len = strlen(pattern); assert(len); query = g_malloc(len); ret = nbd_opt_read(client, query, len, errp); if (ret <= 0) { g_free(query); return ret; } if (strncmp(query, pattern, len) == 0) { trace_nbd_negotiate_meta_query_parse(pattern); *match = true; } else { trace_nbd_negotiate_meta_query_skip("pattern not matched"); } g_free(query); return 1; } /* * Read @len bytes, and set @match to true if they match @pattern, or if @len * is 0 and the client is performing _LIST_. @match is never set to false. * * Return -errno on I/O error, 0 if option was completely handled by * sending a reply about inconsistent lengths, or 1 on success. * * Note: return code = 1 doesn't mean that we've read exactly @pattern. * It only means that there are no errors. */ static int nbd_meta_empty_or_pattern(NBDClient *client, const char *pattern, uint32_t len, bool *match, Error **errp) { if (len == 0) { if (client->opt == NBD_OPT_LIST_META_CONTEXT) { *match = true; } trace_nbd_negotiate_meta_query_parse("empty"); return 1; } if (len != strlen(pattern)) { trace_nbd_negotiate_meta_query_skip("different lengths"); return nbd_opt_skip(client, len, errp); } return nbd_meta_pattern(client, pattern, match, errp); } /* nbd_meta_base_query * * Handle queries to 'base' namespace. For now, only the base:allocation * context is available. 'len' is the amount of text remaining to be read from * the current name, after the 'base:' portion has been stripped. * * Return -errno on I/O error, 0 if option was completely handled by * sending a reply about inconsistent lengths, or 1 on success. */ static int nbd_meta_base_query(NBDClient *client, NBDExportMetaContexts *meta, uint32_t len, Error **errp) { return nbd_meta_empty_or_pattern(client, "allocation", len, &meta->base_allocation, errp); } /* nbd_meta_bitmap_query * * Handle query to 'qemu:' namespace. * @len is the amount of text remaining to be read from the current name, after * the 'qemu:' portion has been stripped. * * Return -errno on I/O error, 0 if option was completely handled by * sending a reply about inconsistent lengths, or 1 on success. */ static int nbd_meta_qemu_query(NBDClient *client, NBDExportMetaContexts *meta, uint32_t len, Error **errp) { bool dirty_bitmap = false; size_t dirty_bitmap_len = strlen("dirty-bitmap:"); int ret; if (!meta->exp->export_bitmap) { trace_nbd_negotiate_meta_query_skip("no dirty-bitmap exported"); return nbd_opt_skip(client, len, errp); } if (len == 0) { if (client->opt == NBD_OPT_LIST_META_CONTEXT) { meta->bitmap = true; } trace_nbd_negotiate_meta_query_parse("empty"); return 1; } if (len < dirty_bitmap_len) { trace_nbd_negotiate_meta_query_skip("not dirty-bitmap:"); return nbd_opt_skip(client, len, errp); } len -= dirty_bitmap_len; ret = nbd_meta_pattern(client, "dirty-bitmap:", &dirty_bitmap, errp); if (ret <= 0) { return ret; } if (!dirty_bitmap) { trace_nbd_negotiate_meta_query_skip("not dirty-bitmap:"); return nbd_opt_skip(client, len, errp); } trace_nbd_negotiate_meta_query_parse("dirty-bitmap:"); return nbd_meta_empty_or_pattern( client, meta->exp->export_bitmap_context + strlen("qemu:dirty_bitmap:"), len, &meta->bitmap, errp); } /* nbd_negotiate_meta_query * * Parse namespace name and call corresponding function to parse body of the * query. * * The only supported namespace now is 'base'. * * The function aims not wasting time and memory to read long unknown namespace * names. * * Return -errno on I/O error, 0 if option was completely handled by * sending a reply about inconsistent lengths, or 1 on success. */ static int nbd_negotiate_meta_query(NBDClient *client, NBDExportMetaContexts *meta, Error **errp) { /* * Both 'qemu' and 'base' namespaces have length = 5 including a * colon. If another length namespace is later introduced, this * should certainly be refactored. */ int ret; size_t ns_len = 5; char ns[5]; uint32_t len; ret = nbd_opt_read(client, &len, sizeof(len), errp); if (ret <= 0) { return ret; } len = cpu_to_be32(len); if (len < ns_len) { trace_nbd_negotiate_meta_query_skip("length too short"); return nbd_opt_skip(client, len, errp); } len -= ns_len; ret = nbd_opt_read(client, ns, ns_len, errp); if (ret <= 0) { return ret; } if (!strncmp(ns, "base:", ns_len)) { trace_nbd_negotiate_meta_query_parse("base:"); return nbd_meta_base_query(client, meta, len, errp); } else if (!strncmp(ns, "qemu:", ns_len)) { trace_nbd_negotiate_meta_query_parse("qemu:"); return nbd_meta_qemu_query(client, meta, len, errp); } trace_nbd_negotiate_meta_query_skip("unknown namespace"); return nbd_opt_skip(client, len, errp); } /* nbd_negotiate_meta_queries * Handle NBD_OPT_LIST_META_CONTEXT and NBD_OPT_SET_META_CONTEXT * * Return -errno on I/O error, or 0 if option was completely handled. */ static int nbd_negotiate_meta_queries(NBDClient *client, NBDExportMetaContexts *meta, Error **errp) { int ret; char export_name[NBD_MAX_NAME_SIZE + 1]; NBDExportMetaContexts local_meta; uint32_t nb_queries; int i; if (!client->structured_reply) { return nbd_opt_invalid(client, errp, "request option '%s' when structured reply " "is not negotiated", nbd_opt_lookup(client->opt)); } if (client->opt == NBD_OPT_LIST_META_CONTEXT) { /* Only change the caller's meta on SET. */ meta = &local_meta; } memset(meta, 0, sizeof(*meta)); ret = nbd_opt_read_name(client, export_name, NULL, errp); if (ret <= 0) { return ret; } meta->exp = nbd_export_find(export_name); if (meta->exp == NULL) { return nbd_opt_drop(client, NBD_REP_ERR_UNKNOWN, errp, "export '%s' not present", export_name); } ret = nbd_opt_read(client, &nb_queries, sizeof(nb_queries), errp); if (ret <= 0) { return ret; } nb_queries = cpu_to_be32(nb_queries); trace_nbd_negotiate_meta_context(nbd_opt_lookup(client->opt), export_name, nb_queries); if (client->opt == NBD_OPT_LIST_META_CONTEXT && !nb_queries) { /* enable all known contexts */ meta->base_allocation = true; meta->bitmap = !!meta->exp->export_bitmap; } else { for (i = 0; i < nb_queries; ++i) { ret = nbd_negotiate_meta_query(client, meta, errp); if (ret <= 0) { return ret; } } } if (meta->base_allocation) { ret = nbd_negotiate_send_meta_context(client, "base:allocation", NBD_META_ID_BASE_ALLOCATION, errp); if (ret < 0) { return ret; } } if (meta->bitmap) { ret = nbd_negotiate_send_meta_context(client, meta->exp->export_bitmap_context, NBD_META_ID_DIRTY_BITMAP, errp); if (ret < 0) { return ret; } } ret = nbd_negotiate_send_rep(client, NBD_REP_ACK, errp); if (ret == 0) { meta->valid = true; } return ret; } /* nbd_negotiate_options * Process all NBD_OPT_* client option commands, during fixed newstyle * negotiation. * Return: * -errno on error, errp is set * 0 on successful negotiation, errp is not set * 1 if client sent NBD_OPT_ABORT, i.e. on valid disconnect, * errp is not set */ static int nbd_negotiate_options(NBDClient *client, uint16_t myflags, Error **errp) { uint32_t flags; bool fixedNewstyle = false; bool no_zeroes = false; /* Client sends: [ 0 .. 3] client flags Then we loop until NBD_OPT_EXPORT_NAME or NBD_OPT_GO: [ 0 .. 7] NBD_OPTS_MAGIC [ 8 .. 11] NBD option [12 .. 15] Data length ... Rest of request [ 0 .. 7] NBD_OPTS_MAGIC [ 8 .. 11] Second NBD option [12 .. 15] Data length ... Rest of request */ if (nbd_read32(client->ioc, &flags, "flags", errp) < 0) { return -EIO; } trace_nbd_negotiate_options_flags(flags); if (flags & NBD_FLAG_C_FIXED_NEWSTYLE) { fixedNewstyle = true; flags &= ~NBD_FLAG_C_FIXED_NEWSTYLE; } if (flags & NBD_FLAG_C_NO_ZEROES) { no_zeroes = true; flags &= ~NBD_FLAG_C_NO_ZEROES; } if (flags != 0) { error_setg(errp, "Unknown client flags 0x%" PRIx32 " received", flags); return -EINVAL; } while (1) { int ret; uint32_t option, length; uint64_t magic; if (nbd_read64(client->ioc, &magic, "opts magic", errp) < 0) { return -EINVAL; } trace_nbd_negotiate_options_check_magic(magic); if (magic != NBD_OPTS_MAGIC) { error_setg(errp, "Bad magic received"); return -EINVAL; } if (nbd_read32(client->ioc, &option, "option", errp) < 0) { return -EINVAL; } client->opt = option; if (nbd_read32(client->ioc, &length, "option length", errp) < 0) { return -EINVAL; } assert(!client->optlen); client->optlen = length; if (length > NBD_MAX_BUFFER_SIZE) { error_setg(errp, "len (%" PRIu32" ) is larger than max len (%u)", length, NBD_MAX_BUFFER_SIZE); return -EINVAL; } trace_nbd_negotiate_options_check_option(option, nbd_opt_lookup(option)); if (client->tlscreds && client->ioc == (QIOChannel *)client->sioc) { QIOChannel *tioc; if (!fixedNewstyle) { error_setg(errp, "Unsupported option 0x%" PRIx32, option); return -EINVAL; } switch (option) { case NBD_OPT_STARTTLS: if (length) { /* Unconditionally drop the connection if the client * can't start a TLS negotiation correctly */ return nbd_reject_length(client, true, errp); } tioc = nbd_negotiate_handle_starttls(client, errp); if (!tioc) { return -EIO; } ret = 0; object_unref(OBJECT(client->ioc)); client->ioc = QIO_CHANNEL(tioc); break; case NBD_OPT_EXPORT_NAME: /* No way to return an error to client, so drop connection */ error_setg(errp, "Option 0x%x not permitted before TLS", option); return -EINVAL; default: /* Let the client keep trying, unless they asked to * quit. Always try to give an error back to the * client; but when replying to OPT_ABORT, be aware * that the client may hang up before receiving the * error, in which case we are fine ignoring the * resulting EPIPE. */ ret = nbd_opt_drop(client, NBD_REP_ERR_TLS_REQD, option == NBD_OPT_ABORT ? NULL : errp, "Option 0x%" PRIx32 " not permitted before TLS", option); if (option == NBD_OPT_ABORT) { return 1; } break; } } else if (fixedNewstyle) { switch (option) { case NBD_OPT_LIST: if (length) { ret = nbd_reject_length(client, false, errp); } else { ret = nbd_negotiate_handle_list(client, errp); } break; case NBD_OPT_ABORT: /* NBD spec says we must try to reply before * disconnecting, but that we must also tolerate * guests that don't wait for our reply. */ nbd_negotiate_send_rep(client, NBD_REP_ACK, NULL); return 1; case NBD_OPT_EXPORT_NAME: return nbd_negotiate_handle_export_name(client, myflags, no_zeroes, errp); case NBD_OPT_INFO: case NBD_OPT_GO: ret = nbd_negotiate_handle_info(client, myflags, errp); if (ret == 1) { assert(option == NBD_OPT_GO); return 0; } break; case NBD_OPT_STARTTLS: if (length) { ret = nbd_reject_length(client, false, errp); } else if (client->tlscreds) { ret = nbd_negotiate_send_rep_err(client, NBD_REP_ERR_INVALID, errp, "TLS already enabled"); } else { ret = nbd_negotiate_send_rep_err(client, NBD_REP_ERR_POLICY, errp, "TLS not configured"); } break; case NBD_OPT_STRUCTURED_REPLY: if (length) { ret = nbd_reject_length(client, false, errp); } else if (client->structured_reply) { ret = nbd_negotiate_send_rep_err( client, NBD_REP_ERR_INVALID, errp, "structured reply already negotiated"); } else { ret = nbd_negotiate_send_rep(client, NBD_REP_ACK, errp); client->structured_reply = true; myflags |= NBD_FLAG_SEND_DF; } break; case NBD_OPT_LIST_META_CONTEXT: case NBD_OPT_SET_META_CONTEXT: ret = nbd_negotiate_meta_queries(client, &client->export_meta, errp); break; default: ret = nbd_opt_drop(client, NBD_REP_ERR_UNSUP, errp, "Unsupported option %" PRIu32 " (%s)", option, nbd_opt_lookup(option)); break; } } else { /* * If broken new-style we should drop the connection * for anything except NBD_OPT_EXPORT_NAME */ switch (option) { case NBD_OPT_EXPORT_NAME: return nbd_negotiate_handle_export_name(client, myflags, no_zeroes, errp); default: error_setg(errp, "Unsupported option %" PRIu32 " (%s)", option, nbd_opt_lookup(option)); return -EINVAL; } } if (ret < 0) { return ret; } } } /* nbd_negotiate * Return: * -errno on error, errp is set * 0 on successful negotiation, errp is not set * 1 if client sent NBD_OPT_ABORT, i.e. on valid disconnect, * errp is not set */ static coroutine_fn int nbd_negotiate(NBDClient *client, Error **errp) { char buf[NBD_OLDSTYLE_NEGOTIATE_SIZE] = ""; int ret; const uint16_t myflags = (NBD_FLAG_HAS_FLAGS | NBD_FLAG_SEND_TRIM | NBD_FLAG_SEND_FLUSH | NBD_FLAG_SEND_FUA | NBD_FLAG_SEND_WRITE_ZEROES | NBD_FLAG_SEND_CACHE); /* Old style negotiation header, no room for options [ 0 .. 7] passwd ("NBDMAGIC") [ 8 .. 15] magic (NBD_CLIENT_MAGIC) [16 .. 23] size [24 .. 27] export flags (zero-extended) [28 .. 151] reserved (0) New style negotiation header, client can send options [ 0 .. 7] passwd ("NBDMAGIC") [ 8 .. 15] magic (NBD_OPTS_MAGIC) [16 .. 17] server flags (0) ....options sent, ending in NBD_OPT_EXPORT_NAME or NBD_OPT_GO.... */ qio_channel_set_blocking(client->ioc, false, NULL); trace_nbd_negotiate_begin(); memcpy(buf, "NBDMAGIC", 8); stq_be_p(buf + 8, NBD_OPTS_MAGIC); stw_be_p(buf + 16, NBD_FLAG_FIXED_NEWSTYLE | NBD_FLAG_NO_ZEROES); if (nbd_write(client->ioc, buf, 18, errp) < 0) { error_prepend(errp, "write failed: "); return -EINVAL; } ret = nbd_negotiate_options(client, myflags, errp); if (ret != 0) { if (ret < 0) { error_prepend(errp, "option negotiation failed: "); } return ret; } assert(!client->optlen); trace_nbd_negotiate_success(); return 0; } static int nbd_receive_request(QIOChannel *ioc, NBDRequest *request, Error **errp) { uint8_t buf[NBD_REQUEST_SIZE]; uint32_t magic; int ret; ret = nbd_read(ioc, buf, sizeof(buf), "request", errp); if (ret < 0) { return ret; } /* Request [ 0 .. 3] magic (NBD_REQUEST_MAGIC) [ 4 .. 5] flags (NBD_CMD_FLAG_FUA, ...) [ 6 .. 7] type (NBD_CMD_READ, ...) [ 8 .. 15] handle [16 .. 23] from [24 .. 27] len */ magic = ldl_be_p(buf); request->flags = lduw_be_p(buf + 4); request->type = lduw_be_p(buf + 6); request->handle = ldq_be_p(buf + 8); request->from = ldq_be_p(buf + 16); request->len = ldl_be_p(buf + 24); trace_nbd_receive_request(magic, request->flags, request->type, request->from, request->len); if (magic != NBD_REQUEST_MAGIC) { error_setg(errp, "invalid magic (got 0x%" PRIx32 ")", magic); return -EINVAL; } return 0; } #define MAX_NBD_REQUESTS 16 void nbd_client_get(NBDClient *client) { client->refcount++; } void nbd_client_put(NBDClient *client) { if (--client->refcount == 0) { /* The last reference should be dropped by client->close, * which is called by client_close. */ assert(client->closing); qio_channel_detach_aio_context(client->ioc); object_unref(OBJECT(client->sioc)); object_unref(OBJECT(client->ioc)); if (client->tlscreds) { object_unref(OBJECT(client->tlscreds)); } g_free(client->tlsauthz); if (client->exp) { QTAILQ_REMOVE(&client->exp->clients, client, next); nbd_export_put(client->exp); } g_free(client); } } static void client_close(NBDClient *client, bool negotiated) { if (client->closing) { return; } client->closing = true; /* Force requests to finish. They will drop their own references, * then we'll close the socket and free the NBDClient. */ qio_channel_shutdown(client->ioc, QIO_CHANNEL_SHUTDOWN_BOTH, NULL); /* Also tell the client, so that they release their reference. */ if (client->close_fn) { client->close_fn(client, negotiated); } } static NBDRequestData *nbd_request_get(NBDClient *client) { NBDRequestData *req; assert(client->nb_requests <= MAX_NBD_REQUESTS - 1); client->nb_requests++; req = g_new0(NBDRequestData, 1); nbd_client_get(client); req->client = client; return req; } static void nbd_request_put(NBDRequestData *req) { NBDClient *client = req->client; if (req->data) { qemu_vfree(req->data); } g_free(req); client->nb_requests--; nbd_client_receive_next_request(client); nbd_client_put(client); } static void blk_aio_attached(AioContext *ctx, void *opaque) { NBDExport *exp = opaque; NBDClient *client; trace_nbd_blk_aio_attached(exp->name, ctx); exp->ctx = ctx; QTAILQ_FOREACH(client, &exp->clients, next) { qio_channel_attach_aio_context(client->ioc, ctx); if (client->recv_coroutine) { aio_co_schedule(ctx, client->recv_coroutine); } if (client->send_coroutine) { aio_co_schedule(ctx, client->send_coroutine); } } } static void blk_aio_detach(void *opaque) { NBDExport *exp = opaque; NBDClient *client; trace_nbd_blk_aio_detach(exp->name, exp->ctx); QTAILQ_FOREACH(client, &exp->clients, next) { qio_channel_detach_aio_context(client->ioc); } exp->ctx = NULL; } static void nbd_eject_notifier(Notifier *n, void *data) { NBDExport *exp = container_of(n, NBDExport, eject_notifier); nbd_export_close(exp); } NBDExport *nbd_export_new(BlockDriverState *bs, uint64_t dev_offset, uint64_t size, const char *name, const char *desc, const char *bitmap, uint16_t nbdflags, void (*close)(NBDExport *), bool writethrough, BlockBackend *on_eject_blk, Error **errp) { AioContext *ctx; BlockBackend *blk; NBDExport *exp = g_new0(NBDExport, 1); uint64_t perm; int ret; /* * NBD exports are used for non-shared storage migration. Make sure * that BDRV_O_INACTIVE is cleared and the image is ready for write * access since the export could be available before migration handover. */ assert(name); ctx = bdrv_get_aio_context(bs); aio_context_acquire(ctx); bdrv_invalidate_cache(bs, NULL); aio_context_release(ctx); /* Don't allow resize while the NBD server is running, otherwise we don't * care what happens with the node. */ perm = BLK_PERM_CONSISTENT_READ; if ((nbdflags & NBD_FLAG_READ_ONLY) == 0) { perm |= BLK_PERM_WRITE; } blk = blk_new(perm, BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE | BLK_PERM_GRAPH_MOD); ret = blk_insert_bs(blk, bs, errp); if (ret < 0) { goto fail; } blk_set_enable_write_cache(blk, !writethrough); exp->refcount = 1; QTAILQ_INIT(&exp->clients); exp->blk = blk; assert(dev_offset <= INT64_MAX); exp->dev_offset = dev_offset; exp->name = g_strdup(name); exp->description = g_strdup(desc); exp->nbdflags = nbdflags; assert(size <= INT64_MAX - dev_offset); exp->size = QEMU_ALIGN_DOWN(size, BDRV_SECTOR_SIZE); if (bitmap) { BdrvDirtyBitmap *bm = NULL; while (true) { bm = bdrv_find_dirty_bitmap(bs, bitmap); if (bm != NULL || bs->backing == NULL) { break; } bs = bs->backing->bs; } if (bm == NULL) { error_setg(errp, "Bitmap '%s' is not found", bitmap); goto fail; } if (bdrv_dirty_bitmap_check(bm, BDRV_BITMAP_ALLOW_RO, errp)) { goto fail; } if ((nbdflags & NBD_FLAG_READ_ONLY) && bdrv_is_writable(bs) && bdrv_dirty_bitmap_enabled(bm)) { error_setg(errp, "Enabled bitmap '%s' incompatible with readonly export", bitmap); goto fail; } bdrv_dirty_bitmap_set_busy(bm, true); exp->export_bitmap = bm; exp->export_bitmap_context = g_strdup_printf("qemu:dirty-bitmap:%s", bitmap); } exp->close = close; exp->ctx = blk_get_aio_context(blk); blk_add_aio_context_notifier(blk, blk_aio_attached, blk_aio_detach, exp); if (on_eject_blk) { blk_ref(on_eject_blk); exp->eject_notifier_blk = on_eject_blk; exp->eject_notifier.notify = nbd_eject_notifier; blk_add_remove_bs_notifier(on_eject_blk, &exp->eject_notifier); } QTAILQ_INSERT_TAIL(&exports, exp, next); nbd_export_get(exp); return exp; fail: blk_unref(blk); g_free(exp->name); g_free(exp->description); g_free(exp); return NULL; } NBDExport *nbd_export_find(const char *name) { NBDExport *exp; QTAILQ_FOREACH(exp, &exports, next) { if (strcmp(name, exp->name) == 0) { return exp; } } return NULL; } void nbd_export_close(NBDExport *exp) { NBDClient *client, *next; nbd_export_get(exp); /* * TODO: Should we expand QMP NbdServerRemoveNode enum to allow a * close mode that stops advertising the export to new clients but * still permits existing clients to run to completion? Because of * that possibility, nbd_export_close() can be called more than * once on an export. */ QTAILQ_FOREACH_SAFE(client, &exp->clients, next, next) { client_close(client, true); } if (exp->name) { nbd_export_put(exp); g_free(exp->name); exp->name = NULL; QTAILQ_REMOVE(&exports, exp, next); } g_free(exp->description); exp->description = NULL; nbd_export_put(exp); } void nbd_export_remove(NBDExport *exp, NbdServerRemoveMode mode, Error **errp) { if (mode == NBD_SERVER_REMOVE_MODE_HARD || QTAILQ_EMPTY(&exp->clients)) { nbd_export_close(exp); return; } assert(mode == NBD_SERVER_REMOVE_MODE_SAFE); error_setg(errp, "export '%s' still in use", exp->name); error_append_hint(errp, "Use mode='hard' to force client disconnect\n"); } void nbd_export_get(NBDExport *exp) { assert(exp->refcount > 0); exp->refcount++; } void nbd_export_put(NBDExport *exp) { assert(exp->refcount > 0); if (exp->refcount == 1) { nbd_export_close(exp); } /* nbd_export_close() may theoretically reduce refcount to 0. It may happen * if someone calls nbd_export_put() on named export not through * nbd_export_set_name() when refcount is 1. So, let's assert that * it is > 0. */ assert(exp->refcount > 0); if (--exp->refcount == 0) { assert(exp->name == NULL); assert(exp->description == NULL); if (exp->close) { exp->close(exp); } if (exp->blk) { if (exp->eject_notifier_blk) { notifier_remove(&exp->eject_notifier); blk_unref(exp->eject_notifier_blk); } blk_remove_aio_context_notifier(exp->blk, blk_aio_attached, blk_aio_detach, exp); blk_unref(exp->blk); exp->blk = NULL; } if (exp->export_bitmap) { bdrv_dirty_bitmap_set_busy(exp->export_bitmap, false); g_free(exp->export_bitmap_context); } g_free(exp); } } BlockBackend *nbd_export_get_blockdev(NBDExport *exp) { return exp->blk; } void nbd_export_close_all(void) { NBDExport *exp, *next; QTAILQ_FOREACH_SAFE(exp, &exports, next, next) { nbd_export_close(exp); } } static int coroutine_fn nbd_co_send_iov(NBDClient *client, struct iovec *iov, unsigned niov, Error **errp) { int ret; g_assert(qemu_in_coroutine()); qemu_co_mutex_lock(&client->send_lock); client->send_coroutine = qemu_coroutine_self(); ret = qio_channel_writev_all(client->ioc, iov, niov, errp) < 0 ? -EIO : 0; client->send_coroutine = NULL; qemu_co_mutex_unlock(&client->send_lock); return ret; } static inline void set_be_simple_reply(NBDSimpleReply *reply, uint64_t error, uint64_t handle) { stl_be_p(&reply->magic, NBD_SIMPLE_REPLY_MAGIC); stl_be_p(&reply->error, error); stq_be_p(&reply->handle, handle); } static int nbd_co_send_simple_reply(NBDClient *client, uint64_t handle, uint32_t error, void *data, size_t len, Error **errp) { NBDSimpleReply reply; int nbd_err = system_errno_to_nbd_errno(error); struct iovec iov[] = { {.iov_base = &reply, .iov_len = sizeof(reply)}, {.iov_base = data, .iov_len = len} }; trace_nbd_co_send_simple_reply(handle, nbd_err, nbd_err_lookup(nbd_err), len); set_be_simple_reply(&reply, nbd_err, handle); return nbd_co_send_iov(client, iov, len ? 2 : 1, errp); } static inline void set_be_chunk(NBDStructuredReplyChunk *chunk, uint16_t flags, uint16_t type, uint64_t handle, uint32_t length) { stl_be_p(&chunk->magic, NBD_STRUCTURED_REPLY_MAGIC); stw_be_p(&chunk->flags, flags); stw_be_p(&chunk->type, type); stq_be_p(&chunk->handle, handle); stl_be_p(&chunk->length, length); } static int coroutine_fn nbd_co_send_structured_done(NBDClient *client, uint64_t handle, Error **errp) { NBDStructuredReplyChunk chunk; struct iovec iov[] = { {.iov_base = &chunk, .iov_len = sizeof(chunk)}, }; trace_nbd_co_send_structured_done(handle); set_be_chunk(&chunk, NBD_REPLY_FLAG_DONE, NBD_REPLY_TYPE_NONE, handle, 0); return nbd_co_send_iov(client, iov, 1, errp); } static int coroutine_fn nbd_co_send_structured_read(NBDClient *client, uint64_t handle, uint64_t offset, void *data, size_t size, bool final, Error **errp) { NBDStructuredReadData chunk; struct iovec iov[] = { {.iov_base = &chunk, .iov_len = sizeof(chunk)}, {.iov_base = data, .iov_len = size} }; assert(size); trace_nbd_co_send_structured_read(handle, offset, data, size); set_be_chunk(&chunk.h, final ? NBD_REPLY_FLAG_DONE : 0, NBD_REPLY_TYPE_OFFSET_DATA, handle, sizeof(chunk) - sizeof(chunk.h) + size); stq_be_p(&chunk.offset, offset); return nbd_co_send_iov(client, iov, 2, errp); } static int coroutine_fn nbd_co_send_structured_error(NBDClient *client, uint64_t handle, uint32_t error, const char *msg, Error **errp) { NBDStructuredError chunk; int nbd_err = system_errno_to_nbd_errno(error); struct iovec iov[] = { {.iov_base = &chunk, .iov_len = sizeof(chunk)}, {.iov_base = (char *)msg, .iov_len = msg ? strlen(msg) : 0}, }; assert(nbd_err); trace_nbd_co_send_structured_error(handle, nbd_err, nbd_err_lookup(nbd_err), msg ? msg : ""); set_be_chunk(&chunk.h, NBD_REPLY_FLAG_DONE, NBD_REPLY_TYPE_ERROR, handle, sizeof(chunk) - sizeof(chunk.h) + iov[1].iov_len); stl_be_p(&chunk.error, nbd_err); stw_be_p(&chunk.message_length, iov[1].iov_len); return nbd_co_send_iov(client, iov, 1 + !!iov[1].iov_len, errp); } /* Do a sparse read and send the structured reply to the client. * Returns -errno if sending fails. bdrv_block_status_above() failure is * reported to the client, at which point this function succeeds. */ static int coroutine_fn nbd_co_send_sparse_read(NBDClient *client, uint64_t handle, uint64_t offset, uint8_t *data, size_t size, Error **errp) { int ret = 0; NBDExport *exp = client->exp; size_t progress = 0; while (progress < size) { int64_t pnum; int status = bdrv_block_status_above(blk_bs(exp->blk), NULL, offset + progress, size - progress, &pnum, NULL, NULL); bool final; if (status < 0) { char *msg = g_strdup_printf("unable to check for holes: %s", strerror(-status)); ret = nbd_co_send_structured_error(client, handle, -status, msg, errp); g_free(msg); return ret; } assert(pnum && pnum <= size - progress); final = progress + pnum == size; if (status & BDRV_BLOCK_ZERO) { NBDStructuredReadHole chunk; struct iovec iov[] = { {.iov_base = &chunk, .iov_len = sizeof(chunk)}, }; trace_nbd_co_send_structured_read_hole(handle, offset + progress, pnum); set_be_chunk(&chunk.h, final ? NBD_REPLY_FLAG_DONE : 0, NBD_REPLY_TYPE_OFFSET_HOLE, handle, sizeof(chunk) - sizeof(chunk.h)); stq_be_p(&chunk.offset, offset + progress); stl_be_p(&chunk.length, pnum); ret = nbd_co_send_iov(client, iov, 1, errp); } else { ret = blk_pread(exp->blk, offset + progress + exp->dev_offset, data + progress, pnum); if (ret < 0) { error_setg_errno(errp, -ret, "reading from file failed"); break; } ret = nbd_co_send_structured_read(client, handle, offset + progress, data + progress, pnum, final, errp); } if (ret < 0) { break; } progress += pnum; } return ret; } /* * Populate @extents from block status. Update @bytes to be the actual * length encoded (which may be smaller than the original), and update * @nb_extents to the number of extents used. * * Returns zero on success and -errno on bdrv_block_status_above failure. */ static int blockstatus_to_extents(BlockDriverState *bs, uint64_t offset, uint64_t *bytes, NBDExtent *extents, unsigned int *nb_extents) { uint64_t remaining_bytes = *bytes; NBDExtent *extent = extents, *extents_end = extents + *nb_extents; bool first_extent = true; assert(*nb_extents); while (remaining_bytes) { uint32_t flags; int64_t num; int ret = bdrv_block_status_above(bs, NULL, offset, remaining_bytes, &num, NULL, NULL); if (ret < 0) { return ret; } flags = (ret & BDRV_BLOCK_ALLOCATED ? 0 : NBD_STATE_HOLE) | (ret & BDRV_BLOCK_ZERO ? NBD_STATE_ZERO : 0); if (first_extent) { extent->flags = flags; extent->length = num; first_extent = false; } else if (flags == extent->flags) { /* extend current extent */ extent->length += num; } else { if (extent + 1 == extents_end) { break; } /* start new extent */ extent++; extent->flags = flags; extent->length = num; } offset += num; remaining_bytes -= num; } extents_end = extent + 1; for (extent = extents; extent < extents_end; extent++) { extent->flags = cpu_to_be32(extent->flags); extent->length = cpu_to_be32(extent->length); } *bytes -= remaining_bytes; *nb_extents = extents_end - extents; return 0; } /* nbd_co_send_extents * * @length is only for tracing purposes (and may be smaller or larger * than the client's original request). @last controls whether * NBD_REPLY_FLAG_DONE is sent. @extents should already be in * big-endian format. */ static int nbd_co_send_extents(NBDClient *client, uint64_t handle, NBDExtent *extents, unsigned int nb_extents, uint64_t length, bool last, uint32_t context_id, Error **errp) { NBDStructuredMeta chunk; struct iovec iov[] = { {.iov_base = &chunk, .iov_len = sizeof(chunk)}, {.iov_base = extents, .iov_len = nb_extents * sizeof(extents[0])} }; trace_nbd_co_send_extents(handle, nb_extents, context_id, length, last); set_be_chunk(&chunk.h, last ? NBD_REPLY_FLAG_DONE : 0, NBD_REPLY_TYPE_BLOCK_STATUS, handle, sizeof(chunk) - sizeof(chunk.h) + iov[1].iov_len); stl_be_p(&chunk.context_id, context_id); return nbd_co_send_iov(client, iov, 2, errp); } /* Get block status from the exported device and send it to the client */ static int nbd_co_send_block_status(NBDClient *client, uint64_t handle, BlockDriverState *bs, uint64_t offset, uint32_t length, bool dont_fragment, bool last, uint32_t context_id, Error **errp) { int ret; unsigned int nb_extents = dont_fragment ? 1 : NBD_MAX_BITMAP_EXTENTS; NBDExtent *extents = g_new(NBDExtent, nb_extents); uint64_t final_length = length; ret = blockstatus_to_extents(bs, offset, &final_length, extents, &nb_extents); if (ret < 0) { g_free(extents); return nbd_co_send_structured_error( client, handle, -ret, "can't get block status", errp); } ret = nbd_co_send_extents(client, handle, extents, nb_extents, final_length, last, context_id, errp); g_free(extents); return ret; } /* * Populate @extents from a dirty bitmap. Unless @dont_fragment, the * final extent may exceed the original @length. Store in @length the * byte length encoded (which may be smaller or larger than the * original), and return the number of extents used. */ static unsigned int bitmap_to_extents(BdrvDirtyBitmap *bitmap, uint64_t offset, uint64_t *length, NBDExtent *extents, unsigned int nb_extents, bool dont_fragment) { uint64_t begin = offset, end = offset; uint64_t overall_end = offset + *length; unsigned int i = 0; BdrvDirtyBitmapIter *it; bool dirty; bdrv_dirty_bitmap_lock(bitmap); it = bdrv_dirty_iter_new(bitmap); dirty = bdrv_get_dirty_locked(NULL, bitmap, offset); assert(begin < overall_end && nb_extents); while (begin < overall_end && i < nb_extents) { bool next_dirty = !dirty; if (dirty) { end = bdrv_dirty_bitmap_next_zero(bitmap, begin, UINT64_MAX); } else { bdrv_set_dirty_iter(it, begin); end = bdrv_dirty_iter_next(it); } if (end == -1 || end - begin > UINT32_MAX) { /* Cap to an aligned value < 4G beyond begin. */ end = MIN(bdrv_dirty_bitmap_size(bitmap), begin + UINT32_MAX + 1 - bdrv_dirty_bitmap_granularity(bitmap)); next_dirty = dirty; } if (dont_fragment && end > overall_end) { end = overall_end; } extents[i].length = cpu_to_be32(end - begin); extents[i].flags = cpu_to_be32(dirty ? NBD_STATE_DIRTY : 0); i++; begin = end; dirty = next_dirty; } bdrv_dirty_iter_free(it); bdrv_dirty_bitmap_unlock(bitmap); assert(offset < end); *length = end - offset; return i; } static int nbd_co_send_bitmap(NBDClient *client, uint64_t handle, BdrvDirtyBitmap *bitmap, uint64_t offset, uint32_t length, bool dont_fragment, bool last, uint32_t context_id, Error **errp) { int ret; unsigned int nb_extents = dont_fragment ? 1 : NBD_MAX_BITMAP_EXTENTS; NBDExtent *extents = g_new(NBDExtent, nb_extents); uint64_t final_length = length; nb_extents = bitmap_to_extents(bitmap, offset, &final_length, extents, nb_extents, dont_fragment); ret = nbd_co_send_extents(client, handle, extents, nb_extents, final_length, last, context_id, errp); g_free(extents); return ret; } /* nbd_co_receive_request * Collect a client request. Return 0 if request looks valid, -EIO to drop * connection right away, and any other negative value to report an error to * the client (although the caller may still need to disconnect after reporting * the error). */ static int nbd_co_receive_request(NBDRequestData *req, NBDRequest *request, Error **errp) { NBDClient *client = req->client; int valid_flags; g_assert(qemu_in_coroutine()); assert(client->recv_coroutine == qemu_coroutine_self()); if (nbd_receive_request(client->ioc, request, errp) < 0) { return -EIO; } trace_nbd_co_receive_request_decode_type(request->handle, request->type, nbd_cmd_lookup(request->type)); if (request->type != NBD_CMD_WRITE) { /* No payload, we are ready to read the next request. */ req->complete = true; } if (request->type == NBD_CMD_DISC) { /* Special case: we're going to disconnect without a reply, * whether or not flags, from, or len are bogus */ return -EIO; } if (request->type == NBD_CMD_READ || request->type == NBD_CMD_WRITE || request->type == NBD_CMD_CACHE) { if (request->len > NBD_MAX_BUFFER_SIZE) { error_setg(errp, "len (%" PRIu32" ) is larger than max len (%u)", request->len, NBD_MAX_BUFFER_SIZE); return -EINVAL; } req->data = blk_try_blockalign(client->exp->blk, request->len); if (req->data == NULL) { error_setg(errp, "No memory"); return -ENOMEM; } } if (request->type == NBD_CMD_WRITE) { if (nbd_read(client->ioc, req->data, request->len, "CMD_WRITE data", errp) < 0) { return -EIO; } req->complete = true; trace_nbd_co_receive_request_payload_received(request->handle, request->len); } /* Sanity checks. */ if (client->exp->nbdflags & NBD_FLAG_READ_ONLY && (request->type == NBD_CMD_WRITE || request->type == NBD_CMD_WRITE_ZEROES || request->type == NBD_CMD_TRIM)) { error_setg(errp, "Export is read-only"); return -EROFS; } if (request->from > client->exp->size || request->len > client->exp->size - request->from) { error_setg(errp, "operation past EOF; From: %" PRIu64 ", Len: %" PRIu32 ", Size: %" PRIu64, request->from, request->len, client->exp->size); return (request->type == NBD_CMD_WRITE || request->type == NBD_CMD_WRITE_ZEROES) ? -ENOSPC : -EINVAL; } if (client->check_align && !QEMU_IS_ALIGNED(request->from | request->len, client->check_align)) { /* * The block layer gracefully handles unaligned requests, but * it's still worth tracing client non-compliance */ trace_nbd_co_receive_align_compliance(nbd_cmd_lookup(request->type), request->from, request->len, client->check_align); } valid_flags = NBD_CMD_FLAG_FUA; if (request->type == NBD_CMD_READ && client->structured_reply) { valid_flags |= NBD_CMD_FLAG_DF; } else if (request->type == NBD_CMD_WRITE_ZEROES) { valid_flags |= NBD_CMD_FLAG_NO_HOLE; } else if (request->type == NBD_CMD_BLOCK_STATUS) { valid_flags |= NBD_CMD_FLAG_REQ_ONE; } if (request->flags & ~valid_flags) { error_setg(errp, "unsupported flags for command %s (got 0x%x)", nbd_cmd_lookup(request->type), request->flags); return -EINVAL; } return 0; } /* Send simple reply without a payload, or a structured error * @error_msg is ignored if @ret >= 0 * Returns 0 if connection is still live, -errno on failure to talk to client */ static coroutine_fn int nbd_send_generic_reply(NBDClient *client, uint64_t handle, int ret, const char *error_msg, Error **errp) { if (client->structured_reply && ret < 0) { return nbd_co_send_structured_error(client, handle, -ret, error_msg, errp); } else { return nbd_co_send_simple_reply(client, handle, ret < 0 ? -ret : 0, NULL, 0, errp); } } /* Handle NBD_CMD_READ request. * Return -errno if sending fails. Other errors are reported directly to the * client as an error reply. */ static coroutine_fn int nbd_do_cmd_read(NBDClient *client, NBDRequest *request, uint8_t *data, Error **errp) { int ret; NBDExport *exp = client->exp; assert(request->type == NBD_CMD_READ || request->type == NBD_CMD_CACHE); /* XXX: NBD Protocol only documents use of FUA with WRITE */ if (request->flags & NBD_CMD_FLAG_FUA) { ret = blk_co_flush(exp->blk); if (ret < 0) { return nbd_send_generic_reply(client, request->handle, ret, "flush failed", errp); } } if (client->structured_reply && !(request->flags & NBD_CMD_FLAG_DF) && request->len && request->type != NBD_CMD_CACHE) { return nbd_co_send_sparse_read(client, request->handle, request->from, data, request->len, errp); } ret = blk_pread(exp->blk, request->from + exp->dev_offset, data, request->len); if (ret < 0 || request->type == NBD_CMD_CACHE) { return nbd_send_generic_reply(client, request->handle, ret, "reading from file failed", errp); } if (client->structured_reply) { if (request->len) { return nbd_co_send_structured_read(client, request->handle, request->from, data, request->len, true, errp); } else { return nbd_co_send_structured_done(client, request->handle, errp); } } else { return nbd_co_send_simple_reply(client, request->handle, 0, data, request->len, errp); } } /* Handle NBD request. * Return -errno if sending fails. Other errors are reported directly to the * client as an error reply. */ static coroutine_fn int nbd_handle_request(NBDClient *client, NBDRequest *request, uint8_t *data, Error **errp) { int ret; int flags; NBDExport *exp = client->exp; char *msg; switch (request->type) { case NBD_CMD_READ: case NBD_CMD_CACHE: return nbd_do_cmd_read(client, request, data, errp); case NBD_CMD_WRITE: flags = 0; if (request->flags & NBD_CMD_FLAG_FUA) { flags |= BDRV_REQ_FUA; } ret = blk_pwrite(exp->blk, request->from + exp->dev_offset, data, request->len, flags); return nbd_send_generic_reply(client, request->handle, ret, "writing to file failed", errp); case NBD_CMD_WRITE_ZEROES: flags = 0; if (request->flags & NBD_CMD_FLAG_FUA) { flags |= BDRV_REQ_FUA; } if (!(request->flags & NBD_CMD_FLAG_NO_HOLE)) { flags |= BDRV_REQ_MAY_UNMAP; } ret = blk_pwrite_zeroes(exp->blk, request->from + exp->dev_offset, request->len, flags); return nbd_send_generic_reply(client, request->handle, ret, "writing to file failed", errp); case NBD_CMD_DISC: /* unreachable, thanks to special case in nbd_co_receive_request() */ abort(); case NBD_CMD_FLUSH: ret = blk_co_flush(exp->blk); return nbd_send_generic_reply(client, request->handle, ret, "flush failed", errp); case NBD_CMD_TRIM: ret = blk_co_pdiscard(exp->blk, request->from + exp->dev_offset, request->len); if (ret == 0 && request->flags & NBD_CMD_FLAG_FUA) { ret = blk_co_flush(exp->blk); } return nbd_send_generic_reply(client, request->handle, ret, "discard failed", errp); case NBD_CMD_BLOCK_STATUS: if (!request->len) { return nbd_send_generic_reply(client, request->handle, -EINVAL, "need non-zero length", errp); } if (client->export_meta.valid && (client->export_meta.base_allocation || client->export_meta.bitmap)) { bool dont_fragment = request->flags & NBD_CMD_FLAG_REQ_ONE; if (client->export_meta.base_allocation) { ret = nbd_co_send_block_status(client, request->handle, blk_bs(exp->blk), request->from, request->len, dont_fragment, !client->export_meta.bitmap, NBD_META_ID_BASE_ALLOCATION, errp); if (ret < 0) { return ret; } } if (client->export_meta.bitmap) { ret = nbd_co_send_bitmap(client, request->handle, client->exp->export_bitmap, request->from, request->len, dont_fragment, true, NBD_META_ID_DIRTY_BITMAP, errp); if (ret < 0) { return ret; } } return ret; } else { return nbd_send_generic_reply(client, request->handle, -EINVAL, "CMD_BLOCK_STATUS not negotiated", errp); } default: msg = g_strdup_printf("invalid request type (%" PRIu32 ") received", request->type); ret = nbd_send_generic_reply(client, request->handle, -EINVAL, msg, errp); g_free(msg); return ret; } } /* Owns a reference to the NBDClient passed as opaque. */ static coroutine_fn void nbd_trip(void *opaque) { NBDClient *client = opaque; NBDRequestData *req; NBDRequest request = { 0 }; /* GCC thinks it can be used uninitialized */ int ret; Error *local_err = NULL; trace_nbd_trip(); if (client->closing) { nbd_client_put(client); return; } req = nbd_request_get(client); ret = nbd_co_receive_request(req, &request, &local_err); client->recv_coroutine = NULL; if (client->closing) { /* * The client may be closed when we are blocked in * nbd_co_receive_request() */ goto done; } nbd_client_receive_next_request(client); if (ret == -EIO) { goto disconnect; } if (ret < 0) { /* It wans't -EIO, so, according to nbd_co_receive_request() * semantics, we should return the error to the client. */ Error *export_err = local_err; local_err = NULL; ret = nbd_send_generic_reply(client, request.handle, -EINVAL, error_get_pretty(export_err), &local_err); error_free(export_err); } else { ret = nbd_handle_request(client, &request, req->data, &local_err); } if (ret < 0) { error_prepend(&local_err, "Failed to send reply: "); goto disconnect; } /* We must disconnect after NBD_CMD_WRITE if we did not * read the payload. */ if (!req->complete) { error_setg(&local_err, "Request handling failed in intermediate state"); goto disconnect; } done: nbd_request_put(req); nbd_client_put(client); return; disconnect: if (local_err) { error_reportf_err(local_err, "Disconnect client, due to: "); } nbd_request_put(req); client_close(client, true); nbd_client_put(client); } static void nbd_client_receive_next_request(NBDClient *client) { if (!client->recv_coroutine && client->nb_requests < MAX_NBD_REQUESTS) { nbd_client_get(client); client->recv_coroutine = qemu_coroutine_create(nbd_trip, client); aio_co_schedule(client->exp->ctx, client->recv_coroutine); } } static coroutine_fn void nbd_co_client_start(void *opaque) { NBDClient *client = opaque; Error *local_err = NULL; qemu_co_mutex_init(&client->send_lock); if (nbd_negotiate(client, &local_err)) { if (local_err) { error_report_err(local_err); } client_close(client, false); return; } nbd_client_receive_next_request(client); } /* * Create a new client listener using the given channel @sioc. * Begin servicing it in a coroutine. When the connection closes, call * @close_fn with an indication of whether the client completed negotiation. */ void nbd_client_new(QIOChannelSocket *sioc, QCryptoTLSCreds *tlscreds, const char *tlsauthz, void (*close_fn)(NBDClient *, bool)) { NBDClient *client; Coroutine *co; client = g_new0(NBDClient, 1); client->refcount = 1; client->tlscreds = tlscreds; if (tlscreds) { object_ref(OBJECT(client->tlscreds)); } client->tlsauthz = g_strdup(tlsauthz); client->sioc = sioc; object_ref(OBJECT(client->sioc)); client->ioc = QIO_CHANNEL(sioc); object_ref(OBJECT(client->ioc)); client->close_fn = close_fn; co = qemu_coroutine_create(nbd_co_client_start, client); qemu_coroutine_enter(co); }