diff options
Diffstat (limited to 'src/nbd.c')
| -rw-r--r-- | src/nbd.c | 1500 |
1 files changed, 1500 insertions, 0 deletions
diff --git a/src/nbd.c b/src/nbd.c new file mode 100644 index 0000000..b3d9654 --- /dev/null +++ b/src/nbd.c @@ -0,0 +1,1500 @@ +/* + * 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; +} |
