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qemu/nbd/server.c
Eric Blake 1f4d6d18ed nbd: Implement NBD_CMD_WRITE_ZEROES on server 
Upstream NBD protocol recently added the ability to efficiently
write zeroes without having to send the zeroes over the wire,
along with a flag to control whether the client wants to allow
a hole.

Note that when it comes to requiring full allocation, vs.
permitting optimizations, the NBD spec intentionally picked a
different sense for the flag; the rules in qemu are:
MAY_UNMAP == 0: must write zeroes
MAY_UNMAP == 1: may use holes if reads will see zeroes

while in NBD, the rules are:
FLAG_NO_HOLE == 1: must write zeroes
FLAG_NO_HOLE == 0: may use holes if reads will see zeroes

In all cases, the 'may use holes' scenario is optional (the
server need not use a hole, and must not use a hole if
subsequent reads would not see zeroes).

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1476469998-28592-16-git-send-email-eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-11-02 09:28:56 +01:00

1450 lines
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/*
* Copyright (C) 2016 Red Hat, Inc.
* Copyright (C) 2005 Anthony Liguori <anthony@codemonkey.ws>
*
* Network Block Device Server Side
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; under version 2 of the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#include "qemu/osdep.h"
#include "qapi/error.h"
#include "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)(NBDClient *client);
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;
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);
static gboolean nbd_negotiate_continue(QIOChannel *ioc,
GIOCondition condition,
void *opaque)
{
qemu_coroutine_enter(opaque);
return TRUE;
}
static ssize_t nbd_negotiate_read(QIOChannel *ioc, void *buffer, size_t size)
{
ssize_t ret;
guint watch;
assert(qemu_in_coroutine());
/* Negotiation are always in main loop. */
watch = qio_channel_add_watch(ioc,
G_IO_IN,
nbd_negotiate_continue,
qemu_coroutine_self(),
NULL);
ret = read_sync(ioc, buffer, size);
g_source_remove(watch);
return ret;
}
static ssize_t nbd_negotiate_write(QIOChannel *ioc, const void *buffer,
size_t size)
{
ssize_t ret;
guint watch;
assert(qemu_in_coroutine());
/* Negotiation are always in main loop. */
watch = qio_channel_add_watch(ioc,
G_IO_OUT,
nbd_negotiate_continue,
qemu_coroutine_self(),
NULL);
ret = write_sync(ioc, buffer, size);
g_source_remove(watch);
return ret;
}
static ssize_t nbd_negotiate_drop_sync(QIOChannel *ioc, size_t size)
{
ssize_t ret, dropped = size;
uint8_t *buffer = g_malloc(MIN(65536, size));
while (size > 0) {
ret = nbd_negotiate_read(ioc, buffer, MIN(65536, size));
if (ret < 0) {
g_free(buffer);
return ret;
}
assert(ret <= size);
size -= ret;
}
g_free(buffer);
return dropped;
}
/* 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_negotiate_write(ioc, &magic, sizeof(magic)) != sizeof(magic)) {
LOG("write failed (rep magic)");
return -EINVAL;
}
opt = cpu_to_be32(opt);
if (nbd_negotiate_write(ioc, &opt, sizeof(opt)) != sizeof(opt)) {
LOG("write failed (rep opt)");
return -EINVAL;
}
type = cpu_to_be32(type);
if (nbd_negotiate_write(ioc, &type, sizeof(type)) != sizeof(type)) {
LOG("write failed (rep type)");
return -EINVAL;
}
len = cpu_to_be32(len);
if (nbd_negotiate_write(ioc, &len, sizeof(len)) != sizeof(len)) {
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_negotiate_write(ioc, msg, len) != len) {
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_negotiate_write(ioc, &len, sizeof(len)) != sizeof(len)) {
LOG("write failed (name length)");
return -EINVAL;
}
if (nbd_negotiate_write(ioc, name, name_len) != name_len) {
LOG("write failed (name buffer)");
return -EINVAL;
}
if (nbd_negotiate_write(ioc, desc, desc_len) != desc_len) {
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_negotiate_drop_sync(client->ioc, length) != length) {
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)
{
int rc = -EINVAL;
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");
goto fail;
}
if (nbd_negotiate_read(client->ioc, name, length) != length) {
LOG("read failed");
goto fail;
}
name[length] = '\0';
TRACE("Client requested export '%s'", name);
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;
}
/* 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_negotiate_drop_sync(ioc, length) != length) {
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_negotiate_read(client->ioc, &flags, sizeof(flags)) !=
sizeof(flags)) {
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_negotiate_read(client->ioc, &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 (nbd_negotiate_read(client->ioc, &clientflags,
sizeof(clientflags)) != sizeof(clientflags)) {
LOG("read failed");
return -EINVAL;
}
clientflags = be32_to_cpu(clientflags);
if (nbd_negotiate_read(client->ioc, &length, sizeof(length)) !=
sizeof(length)) {
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_negotiate_drop_sync(client->ioc, length) != length) {
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_negotiate_drop_sync(client->ioc, length) != length) {
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_negotiate_drop_sync(client->ioc, length) != length) {
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;
}
}
}
}
typedef struct {
NBDClient *client;
Coroutine *co;
} NBDClientNewData;
static coroutine_fn int nbd_negotiate(NBDClientNewData *data)
{
NBDClient *client = data->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);
rc = -EINVAL;
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");
goto fail;
}
if (nbd_negotiate_write(client->ioc, buf, sizeof(buf)) != sizeof(buf)) {
LOG("write failed");
goto fail;
}
} else {
if (nbd_negotiate_write(client->ioc, buf, 18) != 18) {
LOG("write failed");
goto fail;
}
rc = nbd_negotiate_options(client);
if (rc != 0) {
LOG("option negotiation failed");
goto fail;
}
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;
if (nbd_negotiate_write(client->ioc, buf + 18, len) != len) {
LOG("write failed");
goto fail;
}
}
TRACE("Negotiation succeeded.");
rc = 0;
fail:
return rc;
}
static ssize_t nbd_receive_request(QIOChannel *ioc, NBDRequest *request)
{
uint8_t buf[NBD_REQUEST_SIZE];
uint32_t magic;
ssize_t ret;
ret = read_sync(ioc, 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 .. 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 ssize_t nbd_send_reply(QIOChannel *ioc, NBDReply *reply)
{
uint8_t buf[NBD_REPLY_SIZE];
ssize_t ret;
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);
ret = write_sync(ioc, 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);
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)
{
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) {
client->close(client);
}
}
static NBDRequestData *nbd_request_get(NBDClient *client)
{
NBDRequestData *req;
assert(client->nb_requests <= MAX_NBD_REQUESTS - 1);
client->nb_requests++;
nbd_update_can_read(client);
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_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;
}
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));
blk = blk_new();
blk_insert_bs(blk, bs);
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);
}
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 ssize_t nbd_co_send_reply(NBDRequestData *req, NBDReply *reply,
int len)
{
NBDClient *client = req->client;
ssize_t rc, ret;
g_assert(qemu_in_coroutine());
qemu_co_mutex_lock(&client->send_lock);
client->send_coroutine = qemu_coroutine_self();
nbd_set_handlers(client);
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) {
ret = write_sync(client->ioc, req->data, len);
if (ret != len) {
rc = -EIO;
}
}
qio_channel_set_cork(client->ioc, false);
}
client->send_coroutine = NULL;
nbd_set_handlers(client);
qemu_co_mutex_unlock(&client->send_lock);
return rc;
}
/* Collect a client request. Return 0 if request looks valid, -EAGAIN
* to keep trying the collection, -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 ssize_t nbd_co_receive_request(NBDRequestData *req,
NBDRequest *request)
{
NBDClient *client = req->client;
ssize_t rc;
g_assert(qemu_in_coroutine());
client->recv_coroutine = qemu_coroutine_self();
nbd_update_can_read(client);
rc = nbd_receive_request(client->ioc, request);
if (rc < 0) {
if (rc != -EAGAIN) {
rc = -EIO;
}
goto out;
}
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");
rc = -EIO;
goto out;
}
/* 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");
rc = -EINVAL;
goto out;
}
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);
rc = -EINVAL;
goto out;
}
req->data = blk_try_blockalign(client->exp->blk, request->len);
if (req->data == NULL) {
rc = -ENOMEM;
goto out;
}
}
if (request->type == NBD_CMD_WRITE) {
TRACE("Reading %" PRIu32 " byte(s)", request->len);
if (read_sync(client->ioc, req->data, request->len) != request->len) {
LOG("reading from socket failed");
rc = -EIO;
goto out;
}
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);
rc = request->type == NBD_CMD_WRITE ? -ENOSPC : -EINVAL;
goto out;
}
if (request->flags & ~(NBD_CMD_FLAG_FUA | NBD_CMD_FLAG_NO_HOLE)) {
LOG("unsupported flags (got 0x%x)", request->flags);
rc = -EINVAL;
goto out;
}
if (request->type != NBD_CMD_WRITE_ZEROES &&
(request->flags & NBD_CMD_FLAG_NO_HOLE)) {
LOG("unexpected flags (got 0x%x)", request->flags);
rc = -EINVAL;
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;
NBDRequestData *req;
NBDRequest request;
NBDReply reply;
ssize_t ret;
int flags;
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;
}
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);
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);
} 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);
}
static void nbd_set_handlers(NBDClient *client)
{
if (client->exp && client->exp->ctx) {
aio_set_fd_handler(client->exp->ctx, client->sioc->fd,
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->sioc->fd,
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 */
}
}
static coroutine_fn void nbd_co_client_start(void *opaque)
{
NBDClientNewData *data = opaque;
NBDClient *client = data->client;
NBDExport *exp = client->exp;
if (exp) {
nbd_export_get(exp);
}
if (nbd_negotiate(data)) {
client_close(client);
goto out;
}
qemu_co_mutex_init(&client->send_lock);
nbd_set_handlers(client);
if (exp) {
QTAILQ_INSERT_TAIL(&exp->clients, client, next);
}
out:
g_free(data);
}
void nbd_client_new(NBDExport *exp,
QIOChannelSocket *sioc,
QCryptoTLSCreds *tlscreds,
const char *tlsaclname,
void (*close_fn)(NBDClient *))
{
NBDClient *client;
NBDClientNewData *data = g_new(NBDClientNewData, 1);
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->can_read = true;
client->close = close_fn;
data->client = client;
data->co = qemu_coroutine_create(nbd_co_client_start, data);
qemu_coroutine_enter(data->co);
}
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