/* * Copyright (C) 2016-2017 Red Hat, Inc. * Copyright (C) 2005 Anthony Liguori * * 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 . */ #include "qemu/osdep.h" #include "qapi/error.h" #include "trace.h" #include "nbd-internal.h" 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; off_t dev_offset; off_t size; uint16_t nbdflags; QTAILQ_HEAD(, NBDClient) clients; QTAILQ_ENTRY(NBDExport) next; AioContext *ctx; BlockBackend *eject_notifier_blk; Notifier eject_notifier; }; static QTAILQ_HEAD(, NBDExport) exports = QTAILQ_HEAD_INITIALIZER(exports); struct NBDClient { int refcount; void (*close_fn)(NBDClient *client, bool negotiated); NBDExport *exp; QCryptoTLSCreds *tlscreds; char *tlsaclname; 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; bool structured_reply; }; /* That's all folks */ 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) */ /* Send a reply header, including length, but no payload. * Return -errno on error, 0 on success. */ static int nbd_negotiate_send_rep_len(QIOChannel *ioc, uint32_t type, uint32_t opt, uint32_t len, Error **errp) { uint64_t magic; trace_nbd_negotiate_send_rep_len(opt, nbd_opt_lookup(opt), type, nbd_rep_lookup(type), len); assert(len < NBD_MAX_BUFFER_SIZE); magic = cpu_to_be64(NBD_REP_MAGIC); if (nbd_write(ioc, &magic, sizeof(magic), errp) < 0) { error_prepend(errp, "write failed (rep magic): "); return -EINVAL; } opt = cpu_to_be32(opt); if (nbd_write(ioc, &opt, sizeof(opt), errp) < 0) { error_prepend(errp, "write failed (rep opt): "); return -EINVAL; } type = cpu_to_be32(type); if (nbd_write(ioc, &type, sizeof(type), errp) < 0) { error_prepend(errp, "write failed (rep type): "); return -EINVAL; } len = cpu_to_be32(len); if (nbd_write(ioc, &len, sizeof(len), errp) < 0) { error_prepend(errp, "write failed (rep data length): "); return -EINVAL; } return 0; } /* Send a reply header with default 0 length. * Return -errno on error, 0 on success. */ static int nbd_negotiate_send_rep(QIOChannel *ioc, uint32_t type, uint32_t opt, Error **errp) { return nbd_negotiate_send_rep_len(ioc, type, opt, 0, errp); } /* Send an error reply. * Return -errno on error, 0 on success. */ static int GCC_FMT_ATTR(5, 6) nbd_negotiate_send_rep_err(QIOChannel *ioc, uint32_t type, uint32_t opt, Error **errp, const char *fmt, ...) { va_list va; char *msg; int ret; size_t len; va_start(va, fmt); msg = g_strdup_vprintf(fmt, va); va_end(va); len = strlen(msg); assert(len < 4096); trace_nbd_negotiate_send_rep_err(msg); ret = nbd_negotiate_send_rep_len(ioc, type, opt, len, errp); if (ret < 0) { goto out; } if (nbd_write(ioc, msg, len, errp) < 0) { error_prepend(errp, "write failed (error message): "); ret = -EIO; } else { ret = 0; } out: g_free(msg); return ret; } /* 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(QIOChannel *ioc, 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 : ""; 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(ioc, NBD_REP_SERVER, NBD_OPT_LIST, 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; /* For each export, send a NBD_REP_SERVER reply. */ QTAILQ_FOREACH(exp, &exports, next) { if (nbd_negotiate_send_rep_list(client->ioc, exp, errp)) { return -EINVAL; } } /* Finish with a NBD_REP_ACK. */ return nbd_negotiate_send_rep(client->ioc, NBD_REP_ACK, NBD_OPT_LIST, errp); } /* Send a reply to NBD_OPT_EXPORT_NAME. * Return -errno on error, 0 on success. */ static int nbd_negotiate_handle_export_name(NBDClient *client, uint32_t length, 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 (length >= sizeof(name)) { error_setg(errp, "Bad length received"); return -EINVAL; } if (nbd_read(client->ioc, name, length, errp) < 0) { error_prepend(errp, "read failed: "); return -EINVAL; } name[length] = '\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); 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, uint32_t opt, 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->ioc, NBD_REP_INFO, opt, sizeof(info) + length, errp); if (rc < 0) { return rc; } cpu_to_be16s(&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; } /* 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, uint32_t length, uint32_t opt, 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)]; const char *msg; /* 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 */ if (length < sizeof(namelen) + sizeof(requests)) { msg = "overall request too short"; goto invalid; } if (nbd_read(client->ioc, &namelen, sizeof(namelen), errp) < 0) { return -EIO; } be32_to_cpus(&namelen); length -= sizeof(namelen); if (namelen > length - sizeof(requests) || (length - namelen) % 2) { msg = "name length is incorrect"; goto invalid; } if (nbd_read(client->ioc, name, namelen, errp) < 0) { return -EIO; } name[namelen] = '\0'; length -= namelen; trace_nbd_negotiate_handle_export_name_request(name); if (nbd_read(client->ioc, &requests, sizeof(requests), errp) < 0) { return -EIO; } be16_to_cpus(&requests); length -= sizeof(requests); trace_nbd_negotiate_handle_info_requests(requests); if (requests != length / sizeof(request)) { msg = "incorrect number of requests for overall length"; goto invalid; } while (requests--) { if (nbd_read(client->ioc, &request, sizeof(request), errp) < 0) { return -EIO; } be16_to_cpus(&request); length -= sizeof(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; } } assert(length == 0); exp = nbd_export_find(name); if (!exp) { return nbd_negotiate_send_rep_err(client->ioc, NBD_REP_ERR_UNKNOWN, opt, 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, opt, 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, opt, 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 512 if client is new enough. * TODO: consult blk_bs(blk)->bl.request_alignment? */ sizes[0] = (opt == NBD_OPT_INFO || blocksize) ? BDRV_SECTOR_SIZE : 1; /* preferred - Hard-code to 4096 for now. * TODO: is blk_bs(blk)->bl.opt_transfer appropriate? */ sizes[1] = 4096; /* 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]); cpu_to_be32s(&sizes[0]); cpu_to_be32s(&sizes[1]); cpu_to_be32s(&sizes[2]); rc = nbd_negotiate_send_info(client, opt, 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, opt, 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, return an error. * TODO: consult blk_bs(blk)->request_align, and only error if it * is not 1? */ if (opt == NBD_OPT_INFO && !blocksize) { return nbd_negotiate_send_rep_err(client->ioc, NBD_REP_ERR_BLOCK_SIZE_REQD, opt, errp, "request NBD_INFO_BLOCK_SIZE to " "use this export"); } /* Final reply */ rc = nbd_negotiate_send_rep(client->ioc, NBD_REP_ACK, opt, errp); if (rc < 0) { return rc; } if (opt == NBD_OPT_GO) { client->exp = exp; QTAILQ_INSERT_TAIL(&client->exp->clients, client, next); nbd_export_get(client->exp); rc = 1; } return rc; invalid: if (nbd_drop(client->ioc, length, errp) < 0) { return -EIO; } return nbd_negotiate_send_rep_err(client->ioc, NBD_REP_ERR_INVALID, opt, errp, "%s", msg); } /* 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 }; trace_nbd_negotiate_handle_starttls(); ioc = client->ioc; if (nbd_negotiate_send_rep(client->ioc, NBD_REP_ACK, NBD_OPT_STARTTLS, errp) < 0) { return NULL; } tioc = qio_channel_tls_new_server(ioc, client->tlscreds, client->tlsaclname, 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); 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_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 to the guest. * 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, uint32_t length, uint32_t option, bool fatal, Error **errp) { int ret; assert(length); if (nbd_drop(client->ioc, length, errp) < 0) { return -EIO; } ret = nbd_negotiate_send_rep_err(client->ioc, NBD_REP_ERR_INVALID, option, errp, "option '%s' should have zero length", nbd_opt_lookup(option)); if (fatal && !ret) { error_setg(errp, "option '%s' should have zero length", nbd_opt_lookup(option)); return -EINVAL; } 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_read(client->ioc, &flags, sizeof(flags), errp) < 0) { error_prepend(errp, "read failed: "); return -EIO; } be32_to_cpus(&flags); 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_read(client->ioc, &magic, sizeof(magic), errp) < 0) { error_prepend(errp, "read failed: "); return -EINVAL; } magic = be64_to_cpu(magic); trace_nbd_negotiate_options_check_magic(magic); if (magic != NBD_OPTS_MAGIC) { error_setg(errp, "Bad magic received"); return -EINVAL; } if (nbd_read(client->ioc, &option, sizeof(option), errp) < 0) { error_prepend(errp, "read failed: "); return -EINVAL; } option = be32_to_cpu(option); if (nbd_read(client->ioc, &length, sizeof(length), errp) < 0) { error_prepend(errp, "read failed: "); return -EINVAL; } length = be32_to_cpu(length); 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, length, option, 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: if (nbd_drop(client->ioc, length, errp) < 0) { return -EIO; } ret = nbd_negotiate_send_rep_err(client->ioc, NBD_REP_ERR_TLS_REQD, option, errp, "Option 0x%" PRIx32 "not permitted before TLS", option); /* Let the client keep trying, unless they asked to * quit. In this mode, we've already sent an error, so * we can't ack the abort. */ if (option == NBD_OPT_ABORT) { return 1; } break; } } else if (fixedNewstyle) { switch (option) { case NBD_OPT_LIST: if (length) { ret = nbd_reject_length(client, length, option, 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->ioc, NBD_REP_ACK, option, NULL); return 1; case NBD_OPT_EXPORT_NAME: return nbd_negotiate_handle_export_name(client, length, myflags, no_zeroes, errp); case NBD_OPT_INFO: case NBD_OPT_GO: ret = nbd_negotiate_handle_info(client, length, option, myflags, errp); if (ret == 1) { assert(option == NBD_OPT_GO); return 0; } break; case NBD_OPT_STARTTLS: if (length) { ret = nbd_reject_length(client, length, option, false, errp); } else if (client->tlscreds) { ret = nbd_negotiate_send_rep_err(client->ioc, NBD_REP_ERR_INVALID, option, errp, "TLS already enabled"); } else { ret = nbd_negotiate_send_rep_err(client->ioc, NBD_REP_ERR_POLICY, option, errp, "TLS not configured"); } break; case NBD_OPT_STRUCTURED_REPLY: if (length) { ret = nbd_reject_length(client, length, option, false, errp); } else if (client->structured_reply) { ret = nbd_negotiate_send_rep_err( client->ioc, NBD_REP_ERR_INVALID, option, errp, "structured reply already negotiated"); } else { ret = nbd_negotiate_send_rep(client->ioc, NBD_REP_ACK, option, errp); client->structured_reply = true; myflags |= NBD_FLAG_SEND_DF; } break; default: if (nbd_drop(client->ioc, length, errp) < 0) { return -EIO; } ret = nbd_negotiate_send_rep_err(client->ioc, NBD_REP_ERR_UNSUP, option, errp, "Unsupported option 0x%" PRIx32 " (%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, length, myflags, no_zeroes, errp); default: error_setg(errp, "Unsupported option 0x%" PRIx32 " (%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); bool oldStyle; /* 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); oldStyle = client->exp != NULL && !client->tlscreds; if (oldStyle) { trace_nbd_negotiate_old_style(client->exp->size, client->exp->nbdflags | myflags); stq_be_p(buf + 8, NBD_CLIENT_MAGIC); stq_be_p(buf + 16, client->exp->size); stl_be_p(buf + 24, client->exp->nbdflags | myflags); if (nbd_write(client->ioc, buf, sizeof(buf), errp) < 0) { error_prepend(errp, "write failed: "); return -EINVAL; } } else { 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; } } 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), 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->tlsaclname); 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, off_t dev_offset, off_t size, 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. */ 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; exp->dev_offset = dev_offset; exp->nbdflags = nbdflags; exp->size = size < 0 ? blk_getlength(blk) : size; if (exp->size < 0) { error_setg_errno(errp, -exp->size, "Failed to determine the NBD export's length"); goto fail; } exp->size -= exp->size % BDRV_SECTOR_SIZE; 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); } return exp; fail: blk_unref(blk); 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_set_name(NBDExport *exp, const char *name) { if (exp->name == name) { return; } nbd_export_get(exp); if (exp->name != NULL) { g_free(exp->name); exp->name = NULL; QTAILQ_REMOVE(&exports, exp, next); nbd_export_put(exp); } if (name != NULL) { nbd_export_get(exp); exp->name = g_strdup(name); QTAILQ_INSERT_TAIL(&exports, exp, next); } nbd_export_put(exp); } void nbd_export_set_description(NBDExport *exp, const char *description) { g_free(exp->description); exp->description = g_strdup(description); } void nbd_export_close(NBDExport *exp) { NBDClient *client, *next; nbd_export_get(exp); QTAILQ_FOREACH_SAFE(client, &exp->clients, next, next) { client_close(client, true); } nbd_export_set_name(exp, NULL); nbd_export_set_description(exp, NULL); nbd_export_put(exp); } 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); } 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; } 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, 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, NBD_REPLY_FLAG_DONE, 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); } /* 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; } /* Check for sanity in the parameters, part 1. Defer as many * checks as possible until after reading any NBD_CMD_WRITE * payload, so we can try and keep the connection alive. */ if ((request->from + request->len) < request->from) { error_setg(errp, "integer overflow detected, you're probably being attacked"); return -EINVAL; } if (request->type == NBD_CMD_READ || request->type == NBD_CMD_WRITE) { 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, errp) < 0) { error_prepend(errp, "reading from socket failed: "); return -EIO; } req->complete = true; trace_nbd_co_receive_request_payload_received(request->handle, request->len); } /* Sanity checks, part 2. */ if (request->from + request->len > client->exp->size) { error_setg(errp, "operation past EOF; From: %" PRIu64 ", Len: %" PRIu32 ", Size: %" PRIu64, request->from, request->len, (uint64_t)client->exp->size); return request->type == NBD_CMD_WRITE ? -ENOSPC : -EINVAL; } 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; } 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; } /* Owns a reference to the NBDClient passed as opaque. */ static coroutine_fn void nbd_trip(void *opaque) { NBDClient *client = opaque; NBDExport *exp = client->exp; NBDRequestData *req; NBDRequest request = { 0 }; /* GCC thinks it can be used uninitialized */ int ret; int flags; int reply_data_len = 0; Error *local_err = NULL; char *msg = 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; nbd_client_receive_next_request(client); if (ret == -EIO) { goto disconnect; } if (ret < 0) { goto reply; } if (client->closing) { /* * The client may be closed when we are blocked in * nbd_co_receive_request() */ goto done; } switch (request.type) { case NBD_CMD_READ: /* 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) { error_setg_errno(&local_err, -ret, "flush failed"); break; } } ret = blk_pread(exp->blk, request.from + exp->dev_offset, req->data, request.len); if (ret < 0) { error_setg_errno(&local_err, -ret, "reading from file failed"); break; } reply_data_len = request.len; break; case NBD_CMD_WRITE: if (exp->nbdflags & NBD_FLAG_READ_ONLY) { error_setg(&local_err, "Export is read-only"); ret = -EROFS; break; } flags = 0; if (request.flags & NBD_CMD_FLAG_FUA) { flags |= BDRV_REQ_FUA; } ret = blk_pwrite(exp->blk, request.from + exp->dev_offset, req->data, request.len, flags); if (ret < 0) { error_setg_errno(&local_err, -ret, "writing to file failed"); } break; case NBD_CMD_WRITE_ZEROES: if (exp->nbdflags & NBD_FLAG_READ_ONLY) { error_setg(&local_err, "Export is read-only"); ret = -EROFS; break; } 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); if (ret < 0) { error_setg_errno(&local_err, -ret, "writing to file failed"); } break; 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); if (ret < 0) { error_setg_errno(&local_err, -ret, "flush failed"); } break; case NBD_CMD_TRIM: ret = blk_co_pdiscard(exp->blk, request.from + exp->dev_offset, request.len); if (ret < 0) { error_setg_errno(&local_err, -ret, "discard failed"); } break; default: error_setg(&local_err, "invalid request type (%" PRIu32 ") received", request.type); ret = -EINVAL; } reply: if (local_err) { /* If we get here, local_err was not a fatal error, and should be sent * to the client. */ assert(ret < 0); msg = g_strdup(error_get_pretty(local_err)); error_report_err(local_err); local_err = NULL; } if (client->structured_reply && (ret < 0 || request.type == NBD_CMD_READ)) { if (ret < 0) { ret = nbd_co_send_structured_error(req->client, request.handle, -ret, msg, &local_err); } else if (reply_data_len) { ret = nbd_co_send_structured_read(req->client, request.handle, request.from, req->data, reply_data_len, &local_err); } else { ret = nbd_co_send_structured_done(req->client, request.handle, &local_err); } } else { ret = nbd_co_send_simple_reply(req->client, request.handle, ret < 0 ? -ret : 0, req->data, reply_data_len, &local_err); } g_free(msg); 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; NBDExport *exp = client->exp; Error *local_err = NULL; if (exp) { nbd_export_get(exp); QTAILQ_INSERT_TAIL(&exp->clients, client, next); } 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 on the given export @exp, 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(NBDExport *exp, QIOChannelSocket *sioc, QCryptoTLSCreds *tlscreds, const char *tlsaclname, void (*close_fn)(NBDClient *, bool)) { NBDClient *client; Coroutine *co; client = g_new0(NBDClient, 1); client->refcount = 1; client->exp = exp; client->tlscreds = tlscreds; if (tlscreds) { object_ref(OBJECT(client->tlscreds)); } client->tlsaclname = g_strdup(tlsaclname); 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); }