/* * Copyright (C) 2016 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 "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 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); bool no_zeroes; 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; }; /* 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) { uint64_t magic; TRACE("Reply opt=%" PRIx32 " type=%" PRIx32 " len=%" PRIu32, type, opt, len); magic = cpu_to_be64(NBD_REP_MAGIC); if (nbd_write(ioc, &magic, sizeof(magic), NULL) < 0) { LOG("write failed (rep magic)"); return -EINVAL; } opt = cpu_to_be32(opt); if (nbd_write(ioc, &opt, sizeof(opt), NULL) < 0) { LOG("write failed (rep opt)"); return -EINVAL; } type = cpu_to_be32(type); if (nbd_write(ioc, &type, sizeof(type), NULL) < 0) { LOG("write failed (rep type)"); return -EINVAL; } len = cpu_to_be32(len); if (nbd_write(ioc, &len, sizeof(len), NULL) < 0) { LOG("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) { return nbd_negotiate_send_rep_len(ioc, type, opt, 0); } /* Send an error reply. * Return -errno on error, 0 on success. */ static int GCC_FMT_ATTR(4, 5) nbd_negotiate_send_rep_err(QIOChannel *ioc, uint32_t type, uint32_t opt, 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("sending error message \"%s\"", msg); ret = nbd_negotiate_send_rep_len(ioc, type, opt, len); if (ret < 0) { goto out; } if (nbd_write(ioc, msg, len, NULL) < 0) { LOG("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) { size_t name_len, desc_len; uint32_t len; const char *name = exp->name ? exp->name : ""; const char *desc = exp->description ? exp->description : ""; int rc; TRACE("Advertising export name '%s' description '%s'", name, desc); name_len = strlen(name); desc_len = strlen(desc); len = name_len + desc_len + sizeof(len); rc = nbd_negotiate_send_rep_len(ioc, NBD_REP_SERVER, NBD_OPT_LIST, len); if (rc < 0) { return rc; } len = cpu_to_be32(name_len); if (nbd_write(ioc, &len, sizeof(len), NULL) < 0) { LOG("write failed (name length)"); return -EINVAL; } if (nbd_write(ioc, name, name_len, NULL) < 0) { LOG("write failed (name buffer)"); return -EINVAL; } if (nbd_write(ioc, desc, desc_len, NULL) < 0) { LOG("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, uint32_t length) { NBDExport *exp; if (length) { if (nbd_drop(client->ioc, length, NULL) < 0) { return -EIO; } return nbd_negotiate_send_rep_err(client->ioc, NBD_REP_ERR_INVALID, NBD_OPT_LIST, "OPT_LIST should not have length"); } /* For each export, send a NBD_REP_SERVER reply. */ QTAILQ_FOREACH(exp, &exports, next) { if (nbd_negotiate_send_rep_list(client->ioc, exp)) { return -EINVAL; } } /* Finish with a NBD_REP_ACK. */ return nbd_negotiate_send_rep(client->ioc, NBD_REP_ACK, NBD_OPT_LIST); } static int nbd_negotiate_handle_export_name(NBDClient *client, uint32_t length) { char name[NBD_MAX_NAME_SIZE + 1]; /* Client sends: [20 .. xx] export name (length bytes) */ TRACE("Checking length"); if (length >= sizeof(name)) { LOG("Bad length received"); return -EINVAL; } if (nbd_read(client->ioc, name, length, NULL) < 0) { LOG("read failed"); return -EINVAL; } name[length] = '\0'; TRACE("Client requested export '%s'", name); client->exp = nbd_export_find(name); if (!client->exp) { LOG("export not found"); return -EINVAL; } QTAILQ_INSERT_TAIL(&client->exp->clients, client, next); nbd_export_get(client->exp); return 0; } /* 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, uint32_t length) { QIOChannel *ioc; QIOChannelTLS *tioc; struct NBDTLSHandshakeData data = { 0 }; TRACE("Setting up TLS"); ioc = client->ioc; if (length) { if (nbd_drop(ioc, length, NULL) < 0) { return NULL; } nbd_negotiate_send_rep_err(ioc, NBD_REP_ERR_INVALID, NBD_OPT_STARTTLS, "OPT_STARTTLS should not have length"); return NULL; } if (nbd_negotiate_send_rep(client->ioc, NBD_REP_ACK, NBD_OPT_STARTTLS) < 0) { return NULL; } tioc = qio_channel_tls_new_server(ioc, client->tlscreds, client->tlsaclname, NULL); if (!tioc) { return NULL; } qio_channel_set_name(QIO_CHANNEL(tioc), "nbd-server-tls"); TRACE("Starting TLS 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_free(data.error); return NULL; } return QIO_CHANNEL(tioc); } /* Process all NBD_OPT_* client option commands. * Return -errno on error, 0 on success. */ static int nbd_negotiate_options(NBDClient *client) { uint32_t flags; bool fixedNewstyle = false; /* Client sends: [ 0 .. 3] client flags [ 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), NULL) < 0) { LOG("read failed"); return -EIO; } TRACE("Checking client flags"); be32_to_cpus(&flags); if (flags & NBD_FLAG_C_FIXED_NEWSTYLE) { TRACE("Client supports fixed newstyle handshake"); fixedNewstyle = true; flags &= ~NBD_FLAG_C_FIXED_NEWSTYLE; } if (flags & NBD_FLAG_C_NO_ZEROES) { TRACE("Client supports no zeroes at handshake end"); client->no_zeroes = true; flags &= ~NBD_FLAG_C_NO_ZEROES; } if (flags != 0) { TRACE("Unknown client flags 0x%" PRIx32 " received", flags); return -EIO; } while (1) { int ret; uint32_t clientflags, length; uint64_t magic; if (nbd_read(client->ioc, &magic, sizeof(magic), NULL) < 0) { LOG("read failed"); return -EINVAL; } TRACE("Checking opts magic"); if (magic != be64_to_cpu(NBD_OPTS_MAGIC)) { LOG("Bad magic received"); return -EINVAL; } if (nbd_read(client->ioc, &clientflags, sizeof(clientflags), NULL) < 0) { LOG("read failed"); return -EINVAL; } clientflags = be32_to_cpu(clientflags); if (nbd_read(client->ioc, &length, sizeof(length), NULL) < 0) { LOG("read failed"); return -EINVAL; } length = be32_to_cpu(length); TRACE("Checking option 0x%" PRIx32, clientflags); if (client->tlscreds && client->ioc == (QIOChannel *)client->sioc) { QIOChannel *tioc; if (!fixedNewstyle) { TRACE("Unsupported option 0x%" PRIx32, clientflags); return -EINVAL; } switch (clientflags) { case NBD_OPT_STARTTLS: tioc = nbd_negotiate_handle_starttls(client, length); if (!tioc) { return -EIO; } 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 */ TRACE("Option 0x%x not permitted before TLS", clientflags); return -EINVAL; default: if (nbd_drop(client->ioc, length, NULL) < 0) { return -EIO; } ret = nbd_negotiate_send_rep_err(client->ioc, NBD_REP_ERR_TLS_REQD, clientflags, "Option 0x%" PRIx32 "not permitted before TLS", clientflags); if (ret < 0) { return ret; } /* Let the client keep trying, unless they asked to quit */ if (clientflags == NBD_OPT_ABORT) { return -EINVAL; } break; } } else if (fixedNewstyle) { switch (clientflags) { case NBD_OPT_LIST: ret = nbd_negotiate_handle_list(client, length); if (ret < 0) { return ret; } 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, clientflags); return -EINVAL; case NBD_OPT_EXPORT_NAME: return nbd_negotiate_handle_export_name(client, length); case NBD_OPT_STARTTLS: if (nbd_drop(client->ioc, length, NULL) < 0) { return -EIO; } if (client->tlscreds) { ret = nbd_negotiate_send_rep_err(client->ioc, NBD_REP_ERR_INVALID, clientflags, "TLS already enabled"); } else { ret = nbd_negotiate_send_rep_err(client->ioc, NBD_REP_ERR_POLICY, clientflags, "TLS not configured"); } if (ret < 0) { return ret; } break; default: if (nbd_drop(client->ioc, length, NULL) < 0) { return -EIO; } ret = nbd_negotiate_send_rep_err(client->ioc, NBD_REP_ERR_UNSUP, clientflags, "Unsupported option 0x%" PRIx32, clientflags); if (ret < 0) { return ret; } break; } } else { /* * If broken new-style we should drop the connection * for anything except NBD_OPT_EXPORT_NAME */ switch (clientflags) { case NBD_OPT_EXPORT_NAME: return nbd_negotiate_handle_export_name(client, length); default: TRACE("Unsupported option 0x%" PRIx32, clientflags); return -EINVAL; } } } } static coroutine_fn int nbd_negotiate(NBDClient *client) { char buf[8 + 8 + 8 + 128]; int rc; 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; size_t len; /* Old style negotiation header without options [ 0 .. 7] passwd ("NBDMAGIC") [ 8 .. 15] magic (NBD_CLIENT_MAGIC) [16 .. 23] size [24 .. 25] server flags (0) [26 .. 27] export flags [28 .. 151] reserved (0) New style negotiation header with options [ 0 .. 7] passwd ("NBDMAGIC") [ 8 .. 15] magic (NBD_OPTS_MAGIC) [16 .. 17] server flags (0) ....options sent.... [18 .. 25] size [26 .. 27] export flags [28 .. 151] reserved (0, omit if no_zeroes) */ qio_channel_set_blocking(client->ioc, false, NULL); TRACE("Beginning negotiation."); memset(buf, 0, sizeof(buf)); memcpy(buf, "NBDMAGIC", 8); oldStyle = client->exp != NULL && !client->tlscreds; if (oldStyle) { TRACE("advertising size %" PRIu64 " and flags %x", client->exp->size, client->exp->nbdflags | myflags); stq_be_p(buf + 8, NBD_CLIENT_MAGIC); stq_be_p(buf + 16, client->exp->size); stw_be_p(buf + 26, client->exp->nbdflags | myflags); } else { stq_be_p(buf + 8, NBD_OPTS_MAGIC); stw_be_p(buf + 16, NBD_FLAG_FIXED_NEWSTYLE | NBD_FLAG_NO_ZEROES); } if (oldStyle) { if (client->tlscreds) { TRACE("TLS cannot be enabled with oldstyle protocol"); return -EINVAL; } if (nbd_write(client->ioc, buf, sizeof(buf), NULL) < 0) { LOG("write failed"); return -EINVAL; } } else { if (nbd_write(client->ioc, buf, 18, NULL) < 0) { LOG("write failed"); return -EINVAL; } rc = nbd_negotiate_options(client); if (rc != 0) { LOG("option negotiation failed"); return rc; } TRACE("advertising size %" PRIu64 " and flags %x", client->exp->size, client->exp->nbdflags | myflags); stq_be_p(buf + 18, client->exp->size); stw_be_p(buf + 26, client->exp->nbdflags | myflags); len = client->no_zeroes ? 10 : sizeof(buf) - 18; rc = nbd_write(client->ioc, buf + 18, len, NULL); if (rc < 0) { LOG("write failed"); return rc; } } TRACE("Negotiation succeeded."); return 0; } static int nbd_receive_request(QIOChannel *ioc, NBDRequest *request) { uint8_t buf[NBD_REQUEST_SIZE]; uint32_t magic; int ret; ret = nbd_read(ioc, buf, sizeof(buf), NULL); 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("Got request: { magic = 0x%" PRIx32 ", .flags = %" PRIx16 ", .type = %" PRIx16 ", from = %" PRIu64 ", len = %" PRIu32 " }", magic, request->flags, request->type, request->from, request->len); if (magic != NBD_REQUEST_MAGIC) { LOG("invalid magic (got 0x%" PRIx32 ")", magic); return -EINVAL; } return 0; } static int nbd_send_reply(QIOChannel *ioc, NBDReply *reply) { uint8_t buf[NBD_REPLY_SIZE]; reply->error = system_errno_to_nbd_errno(reply->error); TRACE("Sending response to client: { .error = %" PRId32 ", handle = %" PRIu64 " }", reply->error, reply->handle); /* Reply [ 0 .. 3] magic (NBD_REPLY_MAGIC) [ 4 .. 7] error (0 == no error) [ 7 .. 15] handle */ stl_be_p(buf, NBD_REPLY_MAGIC); stl_be_p(buf + 4, reply->error); stq_be_p(buf + 8, reply->handle); return nbd_write(ioc, buf, sizeof(buf), NULL); } #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("Export %s: Attaching clients to AIO context %p\n", 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("Export %s: Detaching clients from AIO context %p\n", 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) { BlockBackend *blk; NBDExport *exp = g_malloc0(sizeof(NBDExport)); uint64_t perm; int ret; /* 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); } /* * 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. */ aio_context_acquire(exp->ctx); blk_invalidate_cache(blk, NULL); aio_context_release(exp->ctx); 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 nbd_co_send_reply(NBDRequestData *req, NBDReply *reply, int len) { NBDClient *client = req->client; int rc; g_assert(qemu_in_coroutine()); qemu_co_mutex_lock(&client->send_lock); client->send_coroutine = qemu_coroutine_self(); if (!len) { rc = nbd_send_reply(client->ioc, reply); } else { qio_channel_set_cork(client->ioc, true); rc = nbd_send_reply(client->ioc, reply); if (rc == 0) { rc = nbd_write(client->ioc, req->data, len, NULL); if (rc < 0) { rc = -EIO; } } qio_channel_set_cork(client->ioc, false); } client->send_coroutine = NULL; qemu_co_mutex_unlock(&client->send_lock); return rc; } /* 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) { NBDClient *client = req->client; g_assert(qemu_in_coroutine()); assert(client->recv_coroutine == qemu_coroutine_self()); if (nbd_receive_request(client->ioc, request) < 0) { return -EIO; } TRACE("Decoding 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 */ TRACE("Request type is DISCONNECT"); 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) { LOG("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) { LOG("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) { return -ENOMEM; } } if (request->type == NBD_CMD_WRITE) { TRACE("Reading %" PRIu32 " byte(s)", request->len); if (nbd_read(client->ioc, req->data, request->len, NULL) < 0) { LOG("reading from socket failed"); return -EIO; } req->complete = true; } /* Sanity checks, part 2. */ if (request->from + request->len > client->exp->size) { LOG("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; } if (request->flags & ~(NBD_CMD_FLAG_FUA | NBD_CMD_FLAG_NO_HOLE)) { LOG("unsupported flags (got 0x%x)", request->flags); return -EINVAL; } if (request->type != NBD_CMD_WRITE_ZEROES && (request->flags & NBD_CMD_FLAG_NO_HOLE)) { LOG("unexpected flags (got 0x%x)", 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 */ NBDReply reply; int ret; int flags; TRACE("Reading request."); if (client->closing) { nbd_client_put(client); return; } req = nbd_request_get(client); ret = nbd_co_receive_request(req, &request); client->recv_coroutine = NULL; nbd_client_receive_next_request(client); if (ret == -EIO) { goto out; } reply.handle = request.handle; reply.error = 0; if (ret < 0) { reply.error = -ret; goto error_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: TRACE("Request type is 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) { LOG("flush failed"); reply.error = -ret; goto error_reply; } } ret = blk_pread(exp->blk, request.from + exp->dev_offset, req->data, request.len); if (ret < 0) { LOG("reading from file failed"); reply.error = -ret; goto error_reply; } TRACE("Read %" PRIu32" byte(s)", request.len); if (nbd_co_send_reply(req, &reply, request.len) < 0) goto out; break; case NBD_CMD_WRITE: TRACE("Request type is WRITE"); if (exp->nbdflags & NBD_FLAG_READ_ONLY) { TRACE("Server is read-only, return error"); reply.error = EROFS; goto error_reply; } TRACE("Writing to device"); 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) { LOG("writing to file failed"); reply.error = -ret; goto error_reply; } if (nbd_co_send_reply(req, &reply, 0) < 0) { goto out; } break; case NBD_CMD_WRITE_ZEROES: TRACE("Request type is WRITE_ZEROES"); if (exp->nbdflags & NBD_FLAG_READ_ONLY) { TRACE("Server is read-only, return error"); reply.error = EROFS; goto error_reply; } TRACE("Writing to device"); 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) { LOG("writing to file failed"); reply.error = -ret; goto error_reply; } if (nbd_co_send_reply(req, &reply, 0) < 0) { goto out; } break; case NBD_CMD_DISC: /* unreachable, thanks to special case in nbd_co_receive_request() */ abort(); case NBD_CMD_FLUSH: TRACE("Request type is FLUSH"); ret = blk_co_flush(exp->blk); if (ret < 0) { LOG("flush failed"); reply.error = -ret; } if (nbd_co_send_reply(req, &reply, 0) < 0) { goto out; } break; case NBD_CMD_TRIM: TRACE("Request type is TRIM"); ret = blk_co_pdiscard(exp->blk, request.from + exp->dev_offset, request.len); if (ret < 0) { LOG("discard failed"); reply.error = -ret; } if (nbd_co_send_reply(req, &reply, 0) < 0) { goto out; } break; default: LOG("invalid request type (%" PRIu32 ") received", request.type); reply.error = EINVAL; error_reply: /* We must disconnect after NBD_CMD_WRITE if we did not * read the payload. */ if (nbd_co_send_reply(req, &reply, 0) < 0 || !req->complete) { goto out; } break; } TRACE("Request/Reply complete"); done: nbd_request_put(req); nbd_client_put(client); return; out: 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; if (exp) { nbd_export_get(exp); QTAILQ_INSERT_TAIL(&exp->clients, client, next); } qemu_co_mutex_init(&client->send_lock); if (nbd_negotiate(client)) { 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_malloc0(sizeof(NBDClient)); 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); }