/* * Copyright (C) 2005 Anthony Liguori <anthony@codemonkey.ws> * * Network Block Device * * 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 "block/nbd.h" #include "sysemu/block-backend.h" #include "qemu/coroutine.h" #include <errno.h> #include <string.h> #ifndef _WIN32 #include <sys/ioctl.h> #endif #if defined(__sun__) || defined(__HAIKU__) #include <sys/ioccom.h> #endif #include <ctype.h> #include <inttypes.h> #ifdef __linux__ #include <linux/fs.h> #endif #include "qemu/sockets.h" #include "qemu/queue.h" #include "qemu/main-loop.h" //#define DEBUG_NBD #ifdef DEBUG_NBD #define TRACE(msg, ...) do { \ LOG(msg, ## __VA_ARGS__); \ } while(0) #else #define TRACE(msg, ...) \ do { } while (0) #endif #define LOG(msg, ...) do { \ fprintf(stderr, "%s:%s():L%d: " msg "\n", \ __FILE__, __FUNCTION__, __LINE__, ## __VA_ARGS__); \ } while(0) /* This is all part of the "official" NBD API. * * The most up-to-date documentation is available at: * https://github.com/yoe/nbd/blob/master/doc/proto.txt */ #define NBD_REQUEST_SIZE (4 + 4 + 8 + 8 + 4) #define NBD_REPLY_SIZE (4 + 4 + 8) #define NBD_REQUEST_MAGIC 0x25609513 #define NBD_REPLY_MAGIC 0x67446698 #define NBD_OPTS_MAGIC 0x49484156454F5054LL #define NBD_CLIENT_MAGIC 0x0000420281861253LL #define NBD_REP_MAGIC 0x3e889045565a9LL #define NBD_SET_SOCK _IO(0xab, 0) #define NBD_SET_BLKSIZE _IO(0xab, 1) #define NBD_SET_SIZE _IO(0xab, 2) #define NBD_DO_IT _IO(0xab, 3) #define NBD_CLEAR_SOCK _IO(0xab, 4) #define NBD_CLEAR_QUE _IO(0xab, 5) #define NBD_PRINT_DEBUG _IO(0xab, 6) #define NBD_SET_SIZE_BLOCKS _IO(0xab, 7) #define NBD_DISCONNECT _IO(0xab, 8) #define NBD_SET_TIMEOUT _IO(0xab, 9) #define NBD_SET_FLAGS _IO(0xab, 10) #define NBD_OPT_EXPORT_NAME (1) #define NBD_OPT_ABORT (2) #define NBD_OPT_LIST (3) /* NBD errors are based on errno numbers, so there is a 1:1 mapping, * but only a limited set of errno values is specified in the protocol. * Everything else is squashed to EINVAL. */ #define NBD_SUCCESS 0 #define NBD_EPERM 1 #define NBD_EIO 5 #define NBD_ENOMEM 12 #define NBD_EINVAL 22 #define NBD_ENOSPC 28 static int system_errno_to_nbd_errno(int err) { switch (err) { case 0: return NBD_SUCCESS; case EPERM: 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 EINVAL: default: return NBD_EINVAL; } } static int nbd_errno_to_system_errno(int err) { switch (err) { case NBD_SUCCESS: return 0; case NBD_EPERM: return EPERM; case NBD_EIO: return EIO; case NBD_ENOMEM: return ENOMEM; case NBD_ENOSPC: return ENOSPC; case NBD_EINVAL: default: return EINVAL; } } /* Definitions for opaque data types */ typedef struct NBDRequest NBDRequest; struct NBDRequest { QSIMPLEQ_ENTRY(NBDRequest) entry; NBDClient *client; uint8_t *data; }; struct NBDExport { int refcount; void (*close)(NBDExport *exp); BlockBackend *blk; char *name; off_t dev_offset; off_t size; uint32_t nbdflags; QTAILQ_HEAD(, NBDClient) clients; QTAILQ_ENTRY(NBDExport) next; AioContext *ctx; }; static QTAILQ_HEAD(, NBDExport) exports = QTAILQ_HEAD_INITIALIZER(exports); struct NBDClient { int refcount; void (*close)(NBDClient *client); NBDExport *exp; int sock; Coroutine *recv_coroutine; CoMutex send_lock; Coroutine *send_coroutine; bool can_read; QTAILQ_ENTRY(NBDClient) next; int nb_requests; bool closing; }; /* That's all folks */ static void nbd_set_handlers(NBDClient *client); static void nbd_unset_handlers(NBDClient *client); static void nbd_update_can_read(NBDClient *client); ssize_t nbd_wr_sync(int fd, void *buffer, size_t size, bool do_read) { size_t offset = 0; int err; if (qemu_in_coroutine()) { if (do_read) { return qemu_co_recv(fd, buffer, size); } else { return qemu_co_send(fd, buffer, size); } } while (offset < size) { ssize_t len; if (do_read) { len = qemu_recv(fd, buffer + offset, size - offset, 0); } else { len = send(fd, buffer + offset, size - offset, 0); } if (len < 0) { err = socket_error(); /* recoverable error */ if (err == EINTR || (offset > 0 && (err == EAGAIN || err == EWOULDBLOCK))) { continue; } /* unrecoverable error */ return -err; } /* eof */ if (len == 0) { break; } offset += len; } return offset; } static ssize_t read_sync(int fd, void *buffer, size_t size) { /* Sockets are kept in blocking mode in the negotiation phase. After * that, a non-readable socket simply means that another thread stole * our request/reply. Synchronization is done with recv_coroutine, so * that this is coroutine-safe. */ return nbd_wr_sync(fd, buffer, size, true); } static ssize_t drop_sync(int fd, size_t size) { ssize_t ret, dropped = size; uint8_t *buffer = g_malloc(MIN(65536, size)); while (size > 0) { ret = read_sync(fd, buffer, MIN(65536, size)); if (ret < 0) { g_free(buffer); return ret; } assert(ret <= size); size -= ret; } g_free(buffer); return dropped; } static ssize_t write_sync(int fd, void *buffer, size_t size) { int ret; do { /* For writes, we do expect the socket to be writable. */ ret = nbd_wr_sync(fd, buffer, size, false); } while (ret == -EAGAIN); return ret; } /* 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 int nbd_send_rep(int csock, uint32_t type, uint32_t opt) { uint64_t magic; uint32_t len; magic = cpu_to_be64(NBD_REP_MAGIC); if (write_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) { LOG("write failed (rep magic)"); return -EINVAL; } opt = cpu_to_be32(opt); if (write_sync(csock, &opt, sizeof(opt)) != sizeof(opt)) { LOG("write failed (rep opt)"); return -EINVAL; } type = cpu_to_be32(type); if (write_sync(csock, &type, sizeof(type)) != sizeof(type)) { LOG("write failed (rep type)"); return -EINVAL; } len = cpu_to_be32(0); if (write_sync(csock, &len, sizeof(len)) != sizeof(len)) { LOG("write failed (rep data length)"); return -EINVAL; } return 0; } static int nbd_send_rep_list(int csock, NBDExport *exp) { uint64_t magic, name_len; uint32_t opt, type, len; name_len = strlen(exp->name); magic = cpu_to_be64(NBD_REP_MAGIC); if (write_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) { LOG("write failed (magic)"); return -EINVAL; } opt = cpu_to_be32(NBD_OPT_LIST); if (write_sync(csock, &opt, sizeof(opt)) != sizeof(opt)) { LOG("write failed (opt)"); return -EINVAL; } type = cpu_to_be32(NBD_REP_SERVER); if (write_sync(csock, &type, sizeof(type)) != sizeof(type)) { LOG("write failed (reply type)"); return -EINVAL; } len = cpu_to_be32(name_len + sizeof(len)); if (write_sync(csock, &len, sizeof(len)) != sizeof(len)) { LOG("write failed (length)"); return -EINVAL; } len = cpu_to_be32(name_len); if (write_sync(csock, &len, sizeof(len)) != sizeof(len)) { LOG("write failed (length)"); return -EINVAL; } if (write_sync(csock, exp->name, name_len) != name_len) { LOG("write failed (buffer)"); return -EINVAL; } return 0; } static int nbd_handle_list(NBDClient *client, uint32_t length) { int csock; NBDExport *exp; csock = client->sock; if (length) { if (drop_sync(csock, length) != length) { return -EIO; } return nbd_send_rep(csock, NBD_REP_ERR_INVALID, NBD_OPT_LIST); } /* For each export, send a NBD_REP_SERVER reply. */ QTAILQ_FOREACH(exp, &exports, next) { if (nbd_send_rep_list(csock, exp)) { return -EINVAL; } } /* Finish with a NBD_REP_ACK. */ return nbd_send_rep(csock, NBD_REP_ACK, NBD_OPT_LIST); } static int nbd_handle_export_name(NBDClient *client, uint32_t length) { int rc = -EINVAL, csock = client->sock; char name[256]; /* Client sends: [20 .. xx] export name (length bytes) */ TRACE("Checking length"); if (length > 255) { LOG("Bad length received"); goto fail; } if (read_sync(csock, name, length) != length) { LOG("read failed"); goto fail; } name[length] = '\0'; client->exp = nbd_export_find(name); if (!client->exp) { LOG("export not found"); goto fail; } QTAILQ_INSERT_TAIL(&client->exp->clients, client, next); nbd_export_get(client->exp); rc = 0; fail: return rc; } static int nbd_receive_options(NBDClient *client) { int csock = client->sock; uint32_t flags; /* 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 (read_sync(csock, &flags, sizeof(flags)) != sizeof(flags)) { LOG("read failed"); return -EIO; } TRACE("Checking client flags"); be32_to_cpus(&flags); if (flags != 0 && flags != NBD_FLAG_C_FIXED_NEWSTYLE) { LOG("Bad client flags received"); return -EIO; } while (1) { int ret; uint32_t tmp, length; uint64_t magic; if (read_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) { LOG("read failed"); return -EINVAL; } TRACE("Checking opts magic"); if (magic != be64_to_cpu(NBD_OPTS_MAGIC)) { LOG("Bad magic received"); return -EINVAL; } if (read_sync(csock, &tmp, sizeof(tmp)) != sizeof(tmp)) { LOG("read failed"); return -EINVAL; } if (read_sync(csock, &length, sizeof(length)) != sizeof(length)) { LOG("read failed"); return -EINVAL; } length = be32_to_cpu(length); TRACE("Checking option"); switch (be32_to_cpu(tmp)) { case NBD_OPT_LIST: ret = nbd_handle_list(client, length); if (ret < 0) { return ret; } break; case NBD_OPT_ABORT: return -EINVAL; case NBD_OPT_EXPORT_NAME: return nbd_handle_export_name(client, length); default: tmp = be32_to_cpu(tmp); LOG("Unsupported option 0x%x", tmp); nbd_send_rep(client->sock, NBD_REP_ERR_UNSUP, tmp); return -EINVAL; } } } static int nbd_send_negotiate(NBDClient *client) { int csock = client->sock; char buf[8 + 8 + 8 + 128]; int rc; const int myflags = (NBD_FLAG_HAS_FLAGS | NBD_FLAG_SEND_TRIM | NBD_FLAG_SEND_FLUSH | NBD_FLAG_SEND_FUA); /* 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) Negotiation header with options, part 1: [ 0 .. 7] passwd ("NBDMAGIC") [ 8 .. 15] magic (NBD_OPTS_MAGIC) [16 .. 17] server flags (0) part 2 (after options are sent): [18 .. 25] size [26 .. 27] export flags [28 .. 151] reserved (0) */ qemu_set_block(csock); rc = -EINVAL; TRACE("Beginning negotiation."); memset(buf, 0, sizeof(buf)); memcpy(buf, "NBDMAGIC", 8); if (client->exp) { assert ((client->exp->nbdflags & ~65535) == 0); cpu_to_be64w((uint64_t*)(buf + 8), NBD_CLIENT_MAGIC); cpu_to_be64w((uint64_t*)(buf + 16), client->exp->size); cpu_to_be16w((uint16_t*)(buf + 26), client->exp->nbdflags | myflags); } else { cpu_to_be64w((uint64_t*)(buf + 8), NBD_OPTS_MAGIC); cpu_to_be16w((uint16_t *)(buf + 16), NBD_FLAG_FIXED_NEWSTYLE); } if (client->exp) { if (write_sync(csock, buf, sizeof(buf)) != sizeof(buf)) { LOG("write failed"); goto fail; } } else { if (write_sync(csock, buf, 18) != 18) { LOG("write failed"); goto fail; } rc = nbd_receive_options(client); if (rc != 0) { LOG("option negotiation failed"); goto fail; } assert ((client->exp->nbdflags & ~65535) == 0); cpu_to_be64w((uint64_t*)(buf + 18), client->exp->size); cpu_to_be16w((uint16_t*)(buf + 26), client->exp->nbdflags | myflags); if (write_sync(csock, buf + 18, sizeof(buf) - 18) != sizeof(buf) - 18) { LOG("write failed"); goto fail; } } TRACE("Negotiation succeeded."); rc = 0; fail: qemu_set_nonblock(csock); return rc; } int nbd_receive_negotiate(int csock, const char *name, uint32_t *flags, off_t *size, Error **errp) { char buf[256]; uint64_t magic, s; uint16_t tmp; int rc; TRACE("Receiving negotiation."); rc = -EINVAL; if (read_sync(csock, buf, 8) != 8) { error_setg(errp, "Failed to read data"); goto fail; } buf[8] = '\0'; if (strlen(buf) == 0) { error_setg(errp, "Server connection closed unexpectedly"); goto fail; } TRACE("Magic is %c%c%c%c%c%c%c%c", qemu_isprint(buf[0]) ? buf[0] : '.', qemu_isprint(buf[1]) ? buf[1] : '.', qemu_isprint(buf[2]) ? buf[2] : '.', qemu_isprint(buf[3]) ? buf[3] : '.', qemu_isprint(buf[4]) ? buf[4] : '.', qemu_isprint(buf[5]) ? buf[5] : '.', qemu_isprint(buf[6]) ? buf[6] : '.', qemu_isprint(buf[7]) ? buf[7] : '.'); if (memcmp(buf, "NBDMAGIC", 8) != 0) { error_setg(errp, "Invalid magic received"); goto fail; } if (read_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) { error_setg(errp, "Failed to read magic"); goto fail; } magic = be64_to_cpu(magic); TRACE("Magic is 0x%" PRIx64, magic); if (name) { uint32_t reserved = 0; uint32_t opt; uint32_t namesize; TRACE("Checking magic (opts_magic)"); if (magic != NBD_OPTS_MAGIC) { if (magic == NBD_CLIENT_MAGIC) { error_setg(errp, "Server does not support export names"); } else { error_setg(errp, "Bad magic received"); } goto fail; } if (read_sync(csock, &tmp, sizeof(tmp)) != sizeof(tmp)) { error_setg(errp, "Failed to read server flags"); goto fail; } *flags = be16_to_cpu(tmp) << 16; /* reserved for future use */ if (write_sync(csock, &reserved, sizeof(reserved)) != sizeof(reserved)) { error_setg(errp, "Failed to read reserved field"); goto fail; } /* write the export name */ magic = cpu_to_be64(magic); if (write_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) { error_setg(errp, "Failed to send export name magic"); goto fail; } opt = cpu_to_be32(NBD_OPT_EXPORT_NAME); if (write_sync(csock, &opt, sizeof(opt)) != sizeof(opt)) { error_setg(errp, "Failed to send export name option number"); goto fail; } namesize = cpu_to_be32(strlen(name)); if (write_sync(csock, &namesize, sizeof(namesize)) != sizeof(namesize)) { error_setg(errp, "Failed to send export name length"); goto fail; } if (write_sync(csock, (char*)name, strlen(name)) != strlen(name)) { error_setg(errp, "Failed to send export name"); goto fail; } } else { TRACE("Checking magic (cli_magic)"); if (magic != NBD_CLIENT_MAGIC) { if (magic == NBD_OPTS_MAGIC) { error_setg(errp, "Server requires an export name"); } else { error_setg(errp, "Bad magic received"); } goto fail; } } if (read_sync(csock, &s, sizeof(s)) != sizeof(s)) { error_setg(errp, "Failed to read export length"); goto fail; } *size = be64_to_cpu(s); TRACE("Size is %" PRIu64, *size); if (!name) { if (read_sync(csock, flags, sizeof(*flags)) != sizeof(*flags)) { error_setg(errp, "Failed to read export flags"); goto fail; } *flags = be32_to_cpup(flags); } else { if (read_sync(csock, &tmp, sizeof(tmp)) != sizeof(tmp)) { error_setg(errp, "Failed to read export flags"); goto fail; } *flags |= be16_to_cpu(tmp); } if (read_sync(csock, &buf, 124) != 124) { error_setg(errp, "Failed to read reserved block"); goto fail; } rc = 0; fail: return rc; } #ifdef __linux__ int nbd_init(int fd, int csock, uint32_t flags, off_t size) { TRACE("Setting NBD socket"); if (ioctl(fd, NBD_SET_SOCK, csock) < 0) { int serrno = errno; LOG("Failed to set NBD socket"); return -serrno; } TRACE("Setting block size to %lu", (unsigned long)BDRV_SECTOR_SIZE); if (ioctl(fd, NBD_SET_BLKSIZE, (size_t)BDRV_SECTOR_SIZE) < 0) { int serrno = errno; LOG("Failed setting NBD block size"); return -serrno; } TRACE("Setting size to %zd block(s)", (size_t)(size / BDRV_SECTOR_SIZE)); if (ioctl(fd, NBD_SET_SIZE_BLOCKS, (size_t)(size / BDRV_SECTOR_SIZE)) < 0) { int serrno = errno; LOG("Failed setting size (in blocks)"); return -serrno; } if (ioctl(fd, NBD_SET_FLAGS, flags) < 0) { if (errno == ENOTTY) { int read_only = (flags & NBD_FLAG_READ_ONLY) != 0; TRACE("Setting readonly attribute"); if (ioctl(fd, BLKROSET, (unsigned long) &read_only) < 0) { int serrno = errno; LOG("Failed setting read-only attribute"); return -serrno; } } else { int serrno = errno; LOG("Failed setting flags"); return -serrno; } } TRACE("Negotiation ended"); return 0; } int nbd_disconnect(int fd) { ioctl(fd, NBD_CLEAR_QUE); ioctl(fd, NBD_DISCONNECT); ioctl(fd, NBD_CLEAR_SOCK); return 0; } int nbd_client(int fd) { int ret; int serrno; TRACE("Doing NBD loop"); ret = ioctl(fd, NBD_DO_IT); if (ret < 0 && errno == EPIPE) { /* NBD_DO_IT normally returns EPIPE when someone has disconnected * the socket via NBD_DISCONNECT. We do not want to return 1 in * that case. */ ret = 0; } serrno = errno; TRACE("NBD loop returned %d: %s", ret, strerror(serrno)); TRACE("Clearing NBD queue"); ioctl(fd, NBD_CLEAR_QUE); TRACE("Clearing NBD socket"); ioctl(fd, NBD_CLEAR_SOCK); errno = serrno; return ret; } #else int nbd_init(int fd, int csock, uint32_t flags, off_t size) { return -ENOTSUP; } int nbd_disconnect(int fd) { return -ENOTSUP; } int nbd_client(int fd) { return -ENOTSUP; } #endif ssize_t nbd_send_request(int csock, struct nbd_request *request) { uint8_t buf[NBD_REQUEST_SIZE]; ssize_t ret; cpu_to_be32w((uint32_t*)buf, NBD_REQUEST_MAGIC); cpu_to_be32w((uint32_t*)(buf + 4), request->type); cpu_to_be64w((uint64_t*)(buf + 8), request->handle); cpu_to_be64w((uint64_t*)(buf + 16), request->from); cpu_to_be32w((uint32_t*)(buf + 24), request->len); TRACE("Sending request to client: " "{ .from = %" PRIu64", .len = %u, .handle = %" PRIu64", .type=%i}", request->from, request->len, request->handle, request->type); ret = write_sync(csock, buf, sizeof(buf)); if (ret < 0) { return ret; } if (ret != sizeof(buf)) { LOG("writing to socket failed"); return -EINVAL; } return 0; } static ssize_t nbd_receive_request(int csock, struct nbd_request *request) { uint8_t buf[NBD_REQUEST_SIZE]; uint32_t magic; ssize_t ret; ret = read_sync(csock, buf, sizeof(buf)); if (ret < 0) { return ret; } if (ret != sizeof(buf)) { LOG("read failed"); return -EINVAL; } /* Request [ 0 .. 3] magic (NBD_REQUEST_MAGIC) [ 4 .. 7] type (0 == READ, 1 == WRITE) [ 8 .. 15] handle [16 .. 23] from [24 .. 27] len */ magic = be32_to_cpup((uint32_t*)buf); request->type = be32_to_cpup((uint32_t*)(buf + 4)); request->handle = be64_to_cpup((uint64_t*)(buf + 8)); request->from = be64_to_cpup((uint64_t*)(buf + 16)); request->len = be32_to_cpup((uint32_t*)(buf + 24)); TRACE("Got request: " "{ magic = 0x%x, .type = %d, from = %" PRIu64" , len = %u }", magic, request->type, request->from, request->len); if (magic != NBD_REQUEST_MAGIC) { LOG("invalid magic (got 0x%x)", magic); return -EINVAL; } return 0; } ssize_t nbd_receive_reply(int csock, struct nbd_reply *reply) { uint8_t buf[NBD_REPLY_SIZE]; uint32_t magic; ssize_t ret; ret = read_sync(csock, buf, sizeof(buf)); if (ret < 0) { return ret; } if (ret != sizeof(buf)) { LOG("read failed"); return -EINVAL; } /* Reply [ 0 .. 3] magic (NBD_REPLY_MAGIC) [ 4 .. 7] error (0 == no error) [ 7 .. 15] handle */ magic = be32_to_cpup((uint32_t*)buf); reply->error = be32_to_cpup((uint32_t*)(buf + 4)); reply->handle = be64_to_cpup((uint64_t*)(buf + 8)); reply->error = nbd_errno_to_system_errno(reply->error); TRACE("Got reply: " "{ magic = 0x%x, .error = %d, handle = %" PRIu64" }", magic, reply->error, reply->handle); if (magic != NBD_REPLY_MAGIC) { LOG("invalid magic (got 0x%x)", magic); return -EINVAL; } return 0; } static ssize_t nbd_send_reply(int csock, struct nbd_reply *reply) { uint8_t buf[NBD_REPLY_SIZE]; ssize_t ret; reply->error = system_errno_to_nbd_errno(reply->error); /* Reply [ 0 .. 3] magic (NBD_REPLY_MAGIC) [ 4 .. 7] error (0 == no error) [ 7 .. 15] handle */ cpu_to_be32w((uint32_t*)buf, NBD_REPLY_MAGIC); cpu_to_be32w((uint32_t*)(buf + 4), reply->error); cpu_to_be64w((uint64_t*)(buf + 8), reply->handle); TRACE("Sending response to client"); ret = write_sync(csock, buf, sizeof(buf)); if (ret < 0) { return ret; } if (ret != sizeof(buf)) { LOG("writing to socket failed"); 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); nbd_unset_handlers(client); close(client->sock); client->sock = -1; if (client->exp) { QTAILQ_REMOVE(&client->exp->clients, client, next); nbd_export_put(client->exp); } g_free(client); } } static void client_close(NBDClient *client) { 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. */ shutdown(client->sock, 2); /* Also tell the client, so that they release their reference. */ if (client->close) { client->close(client); } } static NBDRequest *nbd_request_get(NBDClient *client) { NBDRequest *req; assert(client->nb_requests <= MAX_NBD_REQUESTS - 1); client->nb_requests++; nbd_update_can_read(client); req = g_new0(NBDRequest, 1); nbd_client_get(client); req->client = client; return req; } static void nbd_request_put(NBDRequest *req) { NBDClient *client = req->client; if (req->data) { qemu_vfree(req->data); } g_free(req); client->nb_requests--; nbd_update_can_read(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) { nbd_set_handlers(client); } } 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) { nbd_unset_handlers(client); } exp->ctx = NULL; } NBDExport *nbd_export_new(BlockBackend *blk, off_t dev_offset, off_t size, uint32_t nbdflags, void (*close)(NBDExport *), Error **errp) { NBDExport *exp = g_malloc0(sizeof(NBDExport)); 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_ref(blk); blk_add_aio_context_notifier(blk, blk_aio_attached, blk_aio_detach, exp); /* * NBD exports are used for non-shared storage migration. Make sure * that BDRV_O_INCOMING is cleared and the image is ready for write * access since the export could be available before migration handover. */ blk_invalidate_cache(blk, NULL); return exp; fail: 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_close(NBDExport *exp) { NBDClient *client, *next; nbd_export_get(exp); QTAILQ_FOREACH_SAFE(client, &exp->clients, next, next) { client_close(client); } nbd_export_set_name(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); if (exp->close) { exp->close(exp); } if (exp->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 ssize_t nbd_co_send_reply(NBDRequest *req, struct nbd_reply *reply, int len) { NBDClient *client = req->client; int csock = client->sock; ssize_t rc, ret; qemu_co_mutex_lock(&client->send_lock); client->send_coroutine = qemu_coroutine_self(); nbd_set_handlers(client); if (!len) { rc = nbd_send_reply(csock, reply); } else { socket_set_cork(csock, 1); rc = nbd_send_reply(csock, reply); if (rc >= 0) { ret = qemu_co_send(csock, req->data, len); if (ret != len) { rc = -EIO; } } socket_set_cork(csock, 0); } client->send_coroutine = NULL; nbd_set_handlers(client); qemu_co_mutex_unlock(&client->send_lock); return rc; } static ssize_t nbd_co_receive_request(NBDRequest *req, struct nbd_request *request) { NBDClient *client = req->client; int csock = client->sock; uint32_t command; ssize_t rc; client->recv_coroutine = qemu_coroutine_self(); nbd_update_can_read(client); rc = nbd_receive_request(csock, request); if (rc < 0) { if (rc != -EAGAIN) { rc = -EIO; } goto out; } if (request->len > NBD_MAX_BUFFER_SIZE) { LOG("len (%u) is larger than max len (%u)", request->len, NBD_MAX_BUFFER_SIZE); rc = -EINVAL; goto out; } if ((request->from + request->len) < request->from) { LOG("integer overflow detected! " "you're probably being attacked"); rc = -EINVAL; goto out; } TRACE("Decoding type"); command = request->type & NBD_CMD_MASK_COMMAND; if (command == NBD_CMD_READ || command == NBD_CMD_WRITE) { req->data = blk_blockalign(client->exp->blk, request->len); } if (command == NBD_CMD_WRITE) { TRACE("Reading %u byte(s)", request->len); if (qemu_co_recv(csock, req->data, request->len) != request->len) { LOG("reading from socket failed"); rc = -EIO; goto out; } } rc = 0; out: client->recv_coroutine = NULL; nbd_update_can_read(client); return rc; } static void nbd_trip(void *opaque) { NBDClient *client = opaque; NBDExport *exp = client->exp; NBDRequest *req; struct nbd_request request; struct nbd_reply reply; ssize_t ret; uint32_t command; TRACE("Reading request."); if (client->closing) { return; } req = nbd_request_get(client); ret = nbd_co_receive_request(req, &request); if (ret == -EAGAIN) { goto done; } if (ret == -EIO) { goto out; } reply.handle = request.handle; reply.error = 0; if (ret < 0) { reply.error = -ret; goto error_reply; } command = request.type & NBD_CMD_MASK_COMMAND; if (command != NBD_CMD_DISC && (request.from + request.len) > exp->size) { LOG("From: %" PRIu64 ", Len: %u, Size: %" PRIu64 ", Offset: %" PRIu64 "\n", request.from, request.len, (uint64_t)exp->size, (uint64_t)exp->dev_offset); LOG("requested operation past EOF--bad client?"); goto invalid_request; } if (client->closing) { /* * The client may be closed when we are blocked in * nbd_co_receive_request() */ goto done; } switch (command) { case NBD_CMD_READ: TRACE("Request type is READ"); if (request.type & NBD_CMD_FLAG_FUA) { ret = blk_co_flush(exp->blk); if (ret < 0) { LOG("flush failed"); reply.error = -ret; goto error_reply; } } ret = blk_read(exp->blk, (request.from + exp->dev_offset) / BDRV_SECTOR_SIZE, req->data, request.len / BDRV_SECTOR_SIZE); if (ret < 0) { LOG("reading from file failed"); reply.error = -ret; goto error_reply; } TRACE("Read %u 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"); ret = blk_write(exp->blk, (request.from + exp->dev_offset) / BDRV_SECTOR_SIZE, req->data, request.len / BDRV_SECTOR_SIZE); if (ret < 0) { LOG("writing to file failed"); reply.error = -ret; goto error_reply; } if (request.type & NBD_CMD_FLAG_FUA) { ret = blk_co_flush(exp->blk); if (ret < 0) { LOG("flush failed"); reply.error = -ret; goto error_reply; } } if (nbd_co_send_reply(req, &reply, 0) < 0) { goto out; } break; case NBD_CMD_DISC: TRACE("Request type is DISCONNECT"); errno = 0; goto out; 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_discard(exp->blk, (request.from + exp->dev_offset) / BDRV_SECTOR_SIZE, request.len / BDRV_SECTOR_SIZE); 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 (%u) received", request.type); invalid_request: reply.error = EINVAL; error_reply: if (nbd_co_send_reply(req, &reply, 0) < 0) { goto out; } break; } TRACE("Request/Reply complete"); done: nbd_request_put(req); return; out: nbd_request_put(req); client_close(client); } static void nbd_read(void *opaque) { NBDClient *client = opaque; if (client->recv_coroutine) { qemu_coroutine_enter(client->recv_coroutine, NULL); } else { qemu_coroutine_enter(qemu_coroutine_create(nbd_trip), client); } } static void nbd_restart_write(void *opaque) { NBDClient *client = opaque; qemu_coroutine_enter(client->send_coroutine, NULL); } static void nbd_set_handlers(NBDClient *client) { if (client->exp && client->exp->ctx) { aio_set_fd_handler(client->exp->ctx, client->sock, true, client->can_read ? nbd_read : NULL, client->send_coroutine ? nbd_restart_write : NULL, client); } } static void nbd_unset_handlers(NBDClient *client) { if (client->exp && client->exp->ctx) { aio_set_fd_handler(client->exp->ctx, client->sock, true, NULL, NULL, NULL); } } static void nbd_update_can_read(NBDClient *client) { bool can_read = client->recv_coroutine || client->nb_requests < MAX_NBD_REQUESTS; if (can_read != client->can_read) { client->can_read = can_read; nbd_set_handlers(client); /* There is no need to invoke aio_notify(), since aio_set_fd_handler() * in nbd_set_handlers() will have taken care of that */ } } NBDClient *nbd_client_new(NBDExport *exp, int csock, void (*close)(NBDClient *)) { NBDClient *client; client = g_malloc0(sizeof(NBDClient)); client->refcount = 1; client->exp = exp; client->sock = csock; client->can_read = true; if (nbd_send_negotiate(client)) { g_free(client); return NULL; } client->close = close; qemu_co_mutex_init(&client->send_lock); nbd_set_handlers(client); if (exp) { QTAILQ_INSERT_TAIL(&exp->clients, client, next); nbd_export_get(exp); } return client; }