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qemu-e2k/nbd/server.c
Vladimir Sementsov-Ogievskiy de79bfc36f nbd/server: simplify reply transmission 
Send qiov via qio_channel_writev_all instead of calling nbd_write twice
with a cork.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20171012095319.136610-8-vsementsov@virtuozzo.com>
[eblake: rebase to tweaks earlier in series]
Signed-off-by: Eric Blake <eblake@redhat.com>
2017-10-13 08:05:16 -05:00

1544 lines
46 KiB
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Raw Blame History

/*
* Copyright (C) 2016-2017 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 "trace.h"
#include "nbd-internal.h"
static int system_errno_to_nbd_errno(int err)
{
switch (err) {
case 0:
return NBD_SUCCESS;
case EPERM:
case EROFS:
return NBD_EPERM;
case EIO:
return NBD_EIO;
case ENOMEM:
return NBD_ENOMEM;
#ifdef EDQUOT
case EDQUOT:
#endif
case EFBIG:
case ENOSPC:
return NBD_ENOSPC;
case ESHUTDOWN:
return NBD_ESHUTDOWN;
case EINVAL:
default:
return NBD_EINVAL;
}
}
/* Definitions for opaque data types */
typedef struct NBDRequestData NBDRequestData;
struct NBDRequestData {
QSIMPLEQ_ENTRY(NBDRequestData) entry;
NBDClient *client;
uint8_t *data;
bool complete;
};
struct NBDExport {
int refcount;
void (*close)(NBDExport *exp);
BlockBackend *blk;
char *name;
char *description;
off_t dev_offset;
off_t size;
uint16_t nbdflags;
QTAILQ_HEAD(, NBDClient) clients;
QTAILQ_ENTRY(NBDExport) next;
AioContext *ctx;
BlockBackend *eject_notifier_blk;
Notifier eject_notifier;
};
static QTAILQ_HEAD(, NBDExport) exports = QTAILQ_HEAD_INITIALIZER(exports);
struct NBDClient {
int refcount;
void (*close_fn)(NBDClient *client, bool negotiated);
NBDExport *exp;
QCryptoTLSCreds *tlscreds;
char *tlsaclname;
QIOChannelSocket *sioc; /* The underlying data channel */
QIOChannel *ioc; /* The current I/O channel which may differ (eg TLS) */
Coroutine *recv_coroutine;
CoMutex send_lock;
Coroutine *send_coroutine;
QTAILQ_ENTRY(NBDClient) next;
int nb_requests;
bool closing;
};
/* That's all folks */
static void nbd_client_receive_next_request(NBDClient *client);
/* Basic flow for negotiation
Server Client
Negotiate
or
Server Client
Negotiate #1
Option
Negotiate #2
----
followed by
Server Client
Request
Response
Request
Response
...
...
Request (type == 2)
*/
/* Send a reply header, including length, but no payload.
* Return -errno on error, 0 on success. */
static int nbd_negotiate_send_rep_len(QIOChannel *ioc, uint32_t type,
uint32_t opt, uint32_t len, Error **errp)
{
uint64_t magic;
trace_nbd_negotiate_send_rep_len(opt, nbd_opt_lookup(opt),
type, nbd_rep_lookup(type), len);
assert(len < NBD_MAX_BUFFER_SIZE);
magic = cpu_to_be64(NBD_REP_MAGIC);
if (nbd_write(ioc, &magic, sizeof(magic), errp) < 0) {
error_prepend(errp, "write failed (rep magic): ");
return -EINVAL;
}
opt = cpu_to_be32(opt);
if (nbd_write(ioc, &opt, sizeof(opt), errp) < 0) {
error_prepend(errp, "write failed (rep opt): ");
return -EINVAL;
}
type = cpu_to_be32(type);
if (nbd_write(ioc, &type, sizeof(type), errp) < 0) {
error_prepend(errp, "write failed (rep type): ");
return -EINVAL;
}
len = cpu_to_be32(len);
if (nbd_write(ioc, &len, sizeof(len), errp) < 0) {
error_prepend(errp, "write failed (rep data length): ");
return -EINVAL;
}
return 0;
}
/* Send a reply header with default 0 length.
* Return -errno on error, 0 on success. */
static int nbd_negotiate_send_rep(QIOChannel *ioc, uint32_t type, uint32_t opt,
Error **errp)
{
return nbd_negotiate_send_rep_len(ioc, type, opt, 0, errp);
}
/* Send an error reply.
* Return -errno on error, 0 on success. */
static int GCC_FMT_ATTR(5, 6)
nbd_negotiate_send_rep_err(QIOChannel *ioc, uint32_t type,
uint32_t opt, Error **errp, const char *fmt, ...)
{
va_list va;
char *msg;
int ret;
size_t len;
va_start(va, fmt);
msg = g_strdup_vprintf(fmt, va);
va_end(va);
len = strlen(msg);
assert(len < 4096);
trace_nbd_negotiate_send_rep_err(msg);
ret = nbd_negotiate_send_rep_len(ioc, type, opt, len, errp);
if (ret < 0) {
goto out;
}
if (nbd_write(ioc, msg, len, errp) < 0) {
error_prepend(errp, "write failed (error message): ");
ret = -EIO;
} else {
ret = 0;
}
out:
g_free(msg);
return ret;
}
/* Send a single NBD_REP_SERVER reply to NBD_OPT_LIST, including payload.
* Return -errno on error, 0 on success. */
static int nbd_negotiate_send_rep_list(QIOChannel *ioc, NBDExport *exp,
Error **errp)
{
size_t name_len, desc_len;
uint32_t len;
const char *name = exp->name ? exp->name : "";
const char *desc = exp->description ? exp->description : "";
int ret;
trace_nbd_negotiate_send_rep_list(name, desc);
name_len = strlen(name);
desc_len = strlen(desc);
len = name_len + desc_len + sizeof(len);
ret = nbd_negotiate_send_rep_len(ioc, NBD_REP_SERVER, NBD_OPT_LIST, len,
errp);
if (ret < 0) {
return ret;
}
len = cpu_to_be32(name_len);
if (nbd_write(ioc, &len, sizeof(len), errp) < 0) {
error_prepend(errp, "write failed (name length): ");
return -EINVAL;
}
if (nbd_write(ioc, name, name_len, errp) < 0) {
error_prepend(errp, "write failed (name buffer): ");
return -EINVAL;
}
if (nbd_write(ioc, desc, desc_len, errp) < 0) {
error_prepend(errp, "write failed (description buffer): ");
return -EINVAL;
}
return 0;
}
/* Process the NBD_OPT_LIST command, with a potential series of replies.
* Return -errno on error, 0 on success. */
static int nbd_negotiate_handle_list(NBDClient *client, uint32_t length,
Error **errp)
{
NBDExport *exp;
if (length) {
if (nbd_drop(client->ioc, length, errp) < 0) {
return -EIO;
}
return nbd_negotiate_send_rep_err(client->ioc,
NBD_REP_ERR_INVALID, NBD_OPT_LIST,
errp,
"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, errp)) {
return -EINVAL;
}
}
/* Finish with a NBD_REP_ACK. */
return nbd_negotiate_send_rep(client->ioc, NBD_REP_ACK, NBD_OPT_LIST, errp);
}
/* Send a reply to NBD_OPT_EXPORT_NAME.
* Return -errno on error, 0 on success. */
static int nbd_negotiate_handle_export_name(NBDClient *client, uint32_t length,
uint16_t myflags, bool no_zeroes,
Error **errp)
{
char name[NBD_MAX_NAME_SIZE + 1];
char buf[NBD_REPLY_EXPORT_NAME_SIZE] = "";
size_t len;
int ret;
/* Client sends:
[20 .. xx] export name (length bytes)
Server replies:
[ 0 .. 7] size
[ 8 .. 9] export flags
[10 .. 133] reserved (0) [unless no_zeroes]
*/
trace_nbd_negotiate_handle_export_name();
if (length >= sizeof(name)) {
error_setg(errp, "Bad length received");
return -EINVAL;
}
if (nbd_read(client->ioc, name, length, errp) < 0) {
error_prepend(errp, "read failed: ");
return -EINVAL;
}
name[length] = '\0';
trace_nbd_negotiate_handle_export_name_request(name);
client->exp = nbd_export_find(name);
if (!client->exp) {
error_setg(errp, "export not found");
return -EINVAL;
}
trace_nbd_negotiate_new_style_size_flags(client->exp->size,
client->exp->nbdflags | myflags);
stq_be_p(buf, client->exp->size);
stw_be_p(buf + 8, client->exp->nbdflags | myflags);
len = no_zeroes ? 10 : sizeof(buf);
ret = nbd_write(client->ioc, buf, len, errp);
if (ret < 0) {
error_prepend(errp, "write failed: ");
return ret;
}
QTAILQ_INSERT_TAIL(&client->exp->clients, client, next);
nbd_export_get(client->exp);
return 0;
}
/* Send a single NBD_REP_INFO, with a buffer @buf of @length bytes.
* The buffer does NOT include the info type prefix.
* Return -errno on error, 0 if ready to send more. */
static int nbd_negotiate_send_info(NBDClient *client, uint32_t opt,
uint16_t info, uint32_t length, void *buf,
Error **errp)
{
int rc;
trace_nbd_negotiate_send_info(info, nbd_info_lookup(info), length);
rc = nbd_negotiate_send_rep_len(client->ioc, NBD_REP_INFO, opt,
sizeof(info) + length, errp);
if (rc < 0) {
return rc;
}
cpu_to_be16s(&info);
if (nbd_write(client->ioc, &info, sizeof(info), errp) < 0) {
return -EIO;
}
if (nbd_write(client->ioc, buf, length, errp) < 0) {
return -EIO;
}
return 0;
}
/* Handle NBD_OPT_INFO and NBD_OPT_GO.
* Return -errno on error, 0 if ready for next option, and 1 to move
* into transmission phase. */
static int nbd_negotiate_handle_info(NBDClient *client, uint32_t length,
uint32_t opt, uint16_t myflags,
Error **errp)
{
int rc;
char name[NBD_MAX_NAME_SIZE + 1];
NBDExport *exp;
uint16_t requests;
uint16_t request;
uint32_t namelen;
bool sendname = false;
bool blocksize = false;
uint32_t sizes[3];
char buf[sizeof(uint64_t) + sizeof(uint16_t)];
const char *msg;
/* Client sends:
4 bytes: L, name length (can be 0)
L bytes: export name
2 bytes: N, number of requests (can be 0)
N * 2 bytes: N requests
*/
if (length < sizeof(namelen) + sizeof(requests)) {
msg = "overall request too short";
goto invalid;
}
if (nbd_read(client->ioc, &namelen, sizeof(namelen), errp) < 0) {
return -EIO;
}
be32_to_cpus(&namelen);
length -= sizeof(namelen);
if (namelen > length - sizeof(requests) || (length - namelen) % 2) {
msg = "name length is incorrect";
goto invalid;
}
if (nbd_read(client->ioc, name, namelen, errp) < 0) {
return -EIO;
}
name[namelen] = '\0';
length -= namelen;
trace_nbd_negotiate_handle_export_name_request(name);
if (nbd_read(client->ioc, &requests, sizeof(requests), errp) < 0) {
return -EIO;
}
be16_to_cpus(&requests);
length -= sizeof(requests);
trace_nbd_negotiate_handle_info_requests(requests);
if (requests != length / sizeof(request)) {
msg = "incorrect number of requests for overall length";
goto invalid;
}
while (requests--) {
if (nbd_read(client->ioc, &request, sizeof(request), errp) < 0) {
return -EIO;
}
be16_to_cpus(&request);
length -= sizeof(request);
trace_nbd_negotiate_handle_info_request(request,
nbd_info_lookup(request));
/* We care about NBD_INFO_NAME and NBD_INFO_BLOCK_SIZE;
* everything else is either a request we don't know or
* something we send regardless of request */
switch (request) {
case NBD_INFO_NAME:
sendname = true;
break;
case NBD_INFO_BLOCK_SIZE:
blocksize = true;
break;
}
}
exp = nbd_export_find(name);
if (!exp) {
return nbd_negotiate_send_rep_err(client->ioc, NBD_REP_ERR_UNKNOWN,
opt, errp, "export '%s' not present",
name);
}
/* Don't bother sending NBD_INFO_NAME unless client requested it */
if (sendname) {
rc = nbd_negotiate_send_info(client, opt, NBD_INFO_NAME, length, name,
errp);
if (rc < 0) {
return rc;
}
}
/* Send NBD_INFO_DESCRIPTION only if available, regardless of
* client request */
if (exp->description) {
size_t len = strlen(exp->description);
rc = nbd_negotiate_send_info(client, opt, NBD_INFO_DESCRIPTION,
len, exp->description, errp);
if (rc < 0) {
return rc;
}
}
/* Send NBD_INFO_BLOCK_SIZE always, but tweak the minimum size
* according to whether the client requested it, and according to
* whether this is OPT_INFO or OPT_GO. */
/* minimum - 1 for back-compat, or 512 if client is new enough.
* TODO: consult blk_bs(blk)->bl.request_alignment? */
sizes[0] = (opt == NBD_OPT_INFO || blocksize) ? BDRV_SECTOR_SIZE : 1;
/* preferred - Hard-code to 4096 for now.
* TODO: is blk_bs(blk)->bl.opt_transfer appropriate? */
sizes[1] = 4096;
/* maximum - At most 32M, but smaller as appropriate. */
sizes[2] = MIN(blk_get_max_transfer(exp->blk), NBD_MAX_BUFFER_SIZE);
trace_nbd_negotiate_handle_info_block_size(sizes[0], sizes[1], sizes[2]);
cpu_to_be32s(&sizes[0]);
cpu_to_be32s(&sizes[1]);
cpu_to_be32s(&sizes[2]);
rc = nbd_negotiate_send_info(client, opt, NBD_INFO_BLOCK_SIZE,
sizeof(sizes), sizes, errp);
if (rc < 0) {
return rc;
}
/* Send NBD_INFO_EXPORT always */
trace_nbd_negotiate_new_style_size_flags(exp->size,
exp->nbdflags | myflags);
stq_be_p(buf, exp->size);
stw_be_p(buf + 8, exp->nbdflags | myflags);
rc = nbd_negotiate_send_info(client, opt, NBD_INFO_EXPORT,
sizeof(buf), buf, errp);
if (rc < 0) {
return rc;
}
/* If the client is just asking for NBD_OPT_INFO, but forgot to
* request block sizes, return an error.
* TODO: consult blk_bs(blk)->request_align, and only error if it
* is not 1? */
if (opt == NBD_OPT_INFO && !blocksize) {
return nbd_negotiate_send_rep_err(client->ioc,
NBD_REP_ERR_BLOCK_SIZE_REQD, opt,
errp,
"request NBD_INFO_BLOCK_SIZE to "
"use this export");
}
/* Final reply */
rc = nbd_negotiate_send_rep(client->ioc, NBD_REP_ACK, opt, errp);
if (rc < 0) {
return rc;
}
if (opt == NBD_OPT_GO) {
client->exp = exp;
QTAILQ_INSERT_TAIL(&client->exp->clients, client, next);
nbd_export_get(client->exp);
rc = 1;
}
return rc;
invalid:
if (nbd_drop(client->ioc, length, errp) < 0) {
return -EIO;
}
return nbd_negotiate_send_rep_err(client->ioc, NBD_REP_ERR_INVALID, opt,
errp, "%s", msg);
}
/* Handle NBD_OPT_STARTTLS. Return NULL to drop connection, or else the
* new channel for all further (now-encrypted) communication. */
static QIOChannel *nbd_negotiate_handle_starttls(NBDClient *client,
uint32_t length,
Error **errp)
{
QIOChannel *ioc;
QIOChannelTLS *tioc;
struct NBDTLSHandshakeData data = { 0 };
trace_nbd_negotiate_handle_starttls();
ioc = client->ioc;
if (length) {
if (nbd_drop(ioc, length, errp) < 0) {
return NULL;
}
nbd_negotiate_send_rep_err(ioc, NBD_REP_ERR_INVALID, NBD_OPT_STARTTLS,
errp,
"OPT_STARTTLS should not have length");
return NULL;
}
if (nbd_negotiate_send_rep(client->ioc, NBD_REP_ACK,
NBD_OPT_STARTTLS, errp) < 0) {
return NULL;
}
tioc = qio_channel_tls_new_server(ioc,
client->tlscreds,
client->tlsaclname,
errp);
if (!tioc) {
return NULL;
}
qio_channel_set_name(QIO_CHANNEL(tioc), "nbd-server-tls");
trace_nbd_negotiate_handle_starttls_handshake();
data.loop = g_main_loop_new(g_main_context_default(), FALSE);
qio_channel_tls_handshake(tioc,
nbd_tls_handshake,
&data,
NULL);
if (!data.complete) {
g_main_loop_run(data.loop);
}
g_main_loop_unref(data.loop);
if (data.error) {
object_unref(OBJECT(tioc));
error_propagate(errp, data.error);
return NULL;
}
return QIO_CHANNEL(tioc);
}
/* nbd_negotiate_options
* Process all NBD_OPT_* client option commands, during fixed newstyle
* negotiation.
* Return:
* -errno on error, errp is set
* 0 on successful negotiation, errp is not set
* 1 if client sent NBD_OPT_ABORT, i.e. on valid disconnect,
* errp is not set
*/
static int nbd_negotiate_options(NBDClient *client, uint16_t myflags,
Error **errp)
{
uint32_t flags;
bool fixedNewstyle = false;
bool no_zeroes = false;
/* Client sends:
[ 0 .. 3] client flags
Then we loop until NBD_OPT_EXPORT_NAME or NBD_OPT_GO:
[ 0 .. 7] NBD_OPTS_MAGIC
[ 8 .. 11] NBD option
[12 .. 15] Data length
... Rest of request
[ 0 .. 7] NBD_OPTS_MAGIC
[ 8 .. 11] Second NBD option
[12 .. 15] Data length
... Rest of request
*/
if (nbd_read(client->ioc, &flags, sizeof(flags), errp) < 0) {
error_prepend(errp, "read failed: ");
return -EIO;
}
be32_to_cpus(&flags);
trace_nbd_negotiate_options_flags(flags);
if (flags & NBD_FLAG_C_FIXED_NEWSTYLE) {
fixedNewstyle = true;
flags &= ~NBD_FLAG_C_FIXED_NEWSTYLE;
}
if (flags & NBD_FLAG_C_NO_ZEROES) {
no_zeroes = true;
flags &= ~NBD_FLAG_C_NO_ZEROES;
}
if (flags != 0) {
error_setg(errp, "Unknown client flags 0x%" PRIx32 " received", flags);
return -EINVAL;
}
while (1) {
int ret;
uint32_t option, length;
uint64_t magic;
if (nbd_read(client->ioc, &magic, sizeof(magic), errp) < 0) {
error_prepend(errp, "read failed: ");
return -EINVAL;
}
magic = be64_to_cpu(magic);
trace_nbd_negotiate_options_check_magic(magic);
if (magic != NBD_OPTS_MAGIC) {
error_setg(errp, "Bad magic received");
return -EINVAL;
}
if (nbd_read(client->ioc, &option,
sizeof(option), errp) < 0) {
error_prepend(errp, "read failed: ");
return -EINVAL;
}
option = be32_to_cpu(option);
if (nbd_read(client->ioc, &length, sizeof(length), errp) < 0) {
error_prepend(errp, "read failed: ");
return -EINVAL;
}
length = be32_to_cpu(length);
trace_nbd_negotiate_options_check_option(option,
nbd_opt_lookup(option));
if (client->tlscreds &&
client->ioc == (QIOChannel *)client->sioc) {
QIOChannel *tioc;
if (!fixedNewstyle) {
error_setg(errp, "Unsupported option 0x%" PRIx32, option);
return -EINVAL;
}
switch (option) {
case NBD_OPT_STARTTLS:
tioc = nbd_negotiate_handle_starttls(client, length, errp);
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 */
error_setg(errp, "Option 0x%x not permitted before TLS",
option);
return -EINVAL;
default:
if (nbd_drop(client->ioc, length, errp) < 0) {
return -EIO;
}
ret = nbd_negotiate_send_rep_err(client->ioc,
NBD_REP_ERR_TLS_REQD,
option, errp,
"Option 0x%" PRIx32
"not permitted before TLS",
option);
if (ret < 0) {
return ret;
}
/* Let the client keep trying, unless they asked to
* quit. In this mode, we've already sent an error, so
* we can't ack the abort. */
if (option == NBD_OPT_ABORT) {
return 1;
}
break;
}
} else if (fixedNewstyle) {
switch (option) {
case NBD_OPT_LIST:
ret = nbd_negotiate_handle_list(client, length, errp);
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, option, NULL);
return 1;
case NBD_OPT_EXPORT_NAME:
return nbd_negotiate_handle_export_name(client, length,
myflags, no_zeroes,
errp);
case NBD_OPT_INFO:
case NBD_OPT_GO:
ret = nbd_negotiate_handle_info(client, length, option,
myflags, errp);
if (ret == 1) {
assert(option == NBD_OPT_GO);
return 0;
}
if (ret) {
return ret;
}
break;
case NBD_OPT_STARTTLS:
if (nbd_drop(client->ioc, length, errp) < 0) {
return -EIO;
}
if (client->tlscreds) {
ret = nbd_negotiate_send_rep_err(client->ioc,
NBD_REP_ERR_INVALID,
option, errp,
"TLS already enabled");
} else {
ret = nbd_negotiate_send_rep_err(client->ioc,
NBD_REP_ERR_POLICY,
option, errp,
"TLS not configured");
}
if (ret < 0) {
return ret;
}
break;
default:
if (nbd_drop(client->ioc, length, errp) < 0) {
return -EIO;
}
ret = nbd_negotiate_send_rep_err(client->ioc,
NBD_REP_ERR_UNSUP,
option, errp,
"Unsupported option 0x%"
PRIx32 " (%s)", option,
nbd_opt_lookup(option));
if (ret < 0) {
return ret;
}
break;
}
} else {
/*
* If broken new-style we should drop the connection
* for anything except NBD_OPT_EXPORT_NAME
*/
switch (option) {
case NBD_OPT_EXPORT_NAME:
return nbd_negotiate_handle_export_name(client, length,
myflags, no_zeroes,
errp);
default:
error_setg(errp, "Unsupported option 0x%" PRIx32 " (%s)",
option, nbd_opt_lookup(option));
return -EINVAL;
}
}
}
}
/* nbd_negotiate
* Return:
* -errno on error, errp is set
* 0 on successful negotiation, errp is not set
* 1 if client sent NBD_OPT_ABORT, i.e. on valid disconnect,
* errp is not set
*/
static coroutine_fn int nbd_negotiate(NBDClient *client, Error **errp)
{
char buf[NBD_OLDSTYLE_NEGOTIATE_SIZE] = "";
int ret;
const uint16_t myflags = (NBD_FLAG_HAS_FLAGS | NBD_FLAG_SEND_TRIM |
NBD_FLAG_SEND_FLUSH | NBD_FLAG_SEND_FUA |
NBD_FLAG_SEND_WRITE_ZEROES);
bool oldStyle;
/* Old style negotiation header, no room for options
[ 0 .. 7] passwd ("NBDMAGIC")
[ 8 .. 15] magic (NBD_CLIENT_MAGIC)
[16 .. 23] size
[24 .. 27] export flags (zero-extended)
[28 .. 151] reserved (0)
New style negotiation header, client can send options
[ 0 .. 7] passwd ("NBDMAGIC")
[ 8 .. 15] magic (NBD_OPTS_MAGIC)
[16 .. 17] server flags (0)
....options sent, ending in NBD_OPT_EXPORT_NAME or NBD_OPT_GO....
*/
qio_channel_set_blocking(client->ioc, false, NULL);
trace_nbd_negotiate_begin();
memcpy(buf, "NBDMAGIC", 8);
oldStyle = client->exp != NULL && !client->tlscreds;
if (oldStyle) {
trace_nbd_negotiate_old_style(client->exp->size,
client->exp->nbdflags | myflags);
stq_be_p(buf + 8, NBD_CLIENT_MAGIC);
stq_be_p(buf + 16, client->exp->size);
stl_be_p(buf + 24, client->exp->nbdflags | myflags);
if (nbd_write(client->ioc, buf, sizeof(buf), errp) < 0) {
error_prepend(errp, "write failed: ");
return -EINVAL;
}
} else {
stq_be_p(buf + 8, NBD_OPTS_MAGIC);
stw_be_p(buf + 16, NBD_FLAG_FIXED_NEWSTYLE | NBD_FLAG_NO_ZEROES);
if (nbd_write(client->ioc, buf, 18, errp) < 0) {
error_prepend(errp, "write failed: ");
return -EINVAL;
}
ret = nbd_negotiate_options(client, myflags, errp);
if (ret != 0) {
if (ret < 0) {
error_prepend(errp, "option negotiation failed: ");
}
return ret;
}
}
trace_nbd_negotiate_success();
return 0;
}
static int nbd_receive_request(QIOChannel *ioc, NBDRequest *request,
Error **errp)
{
uint8_t buf[NBD_REQUEST_SIZE];
uint32_t magic;
int ret;
ret = nbd_read(ioc, buf, sizeof(buf), errp);
if (ret < 0) {
return ret;
}
/* Request
[ 0 .. 3] magic (NBD_REQUEST_MAGIC)
[ 4 .. 5] flags (NBD_CMD_FLAG_FUA, ...)
[ 6 .. 7] type (NBD_CMD_READ, ...)
[ 8 .. 15] handle
[16 .. 23] from
[24 .. 27] len
*/
magic = ldl_be_p(buf);
request->flags = lduw_be_p(buf + 4);
request->type = lduw_be_p(buf + 6);
request->handle = ldq_be_p(buf + 8);
request->from = ldq_be_p(buf + 16);
request->len = ldl_be_p(buf + 24);
trace_nbd_receive_request(magic, request->flags, request->type,
request->from, request->len);
if (magic != NBD_REQUEST_MAGIC) {
error_setg(errp, "invalid magic (got 0x%" PRIx32 ")", magic);
return -EINVAL;
}
return 0;
}
#define MAX_NBD_REQUESTS 16
void nbd_client_get(NBDClient *client)
{
client->refcount++;
}
void nbd_client_put(NBDClient *client)
{
if (--client->refcount == 0) {
/* The last reference should be dropped by client->close,
* which is called by client_close.
*/
assert(client->closing);
qio_channel_detach_aio_context(client->ioc);
object_unref(OBJECT(client->sioc));
object_unref(OBJECT(client->ioc));
if (client->tlscreds) {
object_unref(OBJECT(client->tlscreds));
}
g_free(client->tlsaclname);
if (client->exp) {
QTAILQ_REMOVE(&client->exp->clients, client, next);
nbd_export_put(client->exp);
}
g_free(client);
}
}
static void client_close(NBDClient *client, bool negotiated)
{
if (client->closing) {
return;
}
client->closing = true;
/* Force requests to finish. They will drop their own references,
* then we'll close the socket and free the NBDClient.
*/
qio_channel_shutdown(client->ioc, QIO_CHANNEL_SHUTDOWN_BOTH,
NULL);
/* Also tell the client, so that they release their reference. */
if (client->close_fn) {
client->close_fn(client, negotiated);
}
}
static NBDRequestData *nbd_request_get(NBDClient *client)
{
NBDRequestData *req;
assert(client->nb_requests <= MAX_NBD_REQUESTS - 1);
client->nb_requests++;
req = g_new0(NBDRequestData, 1);
nbd_client_get(client);
req->client = client;
return req;
}
static void nbd_request_put(NBDRequestData *req)
{
NBDClient *client = req->client;
if (req->data) {
qemu_vfree(req->data);
}
g_free(req);
client->nb_requests--;
nbd_client_receive_next_request(client);
nbd_client_put(client);
}
static void blk_aio_attached(AioContext *ctx, void *opaque)
{
NBDExport *exp = opaque;
NBDClient *client;
trace_nbd_blk_aio_attached(exp->name, ctx);
exp->ctx = ctx;
QTAILQ_FOREACH(client, &exp->clients, next) {
qio_channel_attach_aio_context(client->ioc, ctx);
if (client->recv_coroutine) {
aio_co_schedule(ctx, client->recv_coroutine);
}
if (client->send_coroutine) {
aio_co_schedule(ctx, client->send_coroutine);
}
}
}
static void blk_aio_detach(void *opaque)
{
NBDExport *exp = opaque;
NBDClient *client;
trace_nbd_blk_aio_detach(exp->name, exp->ctx);
QTAILQ_FOREACH(client, &exp->clients, next) {
qio_channel_detach_aio_context(client->ioc);
}
exp->ctx = NULL;
}
static void nbd_eject_notifier(Notifier *n, void *data)
{
NBDExport *exp = container_of(n, NBDExport, eject_notifier);
nbd_export_close(exp);
}
NBDExport *nbd_export_new(BlockDriverState *bs, off_t dev_offset, off_t size,
uint16_t nbdflags, void (*close)(NBDExport *),
bool writethrough, BlockBackend *on_eject_blk,
Error **errp)
{
AioContext *ctx;
BlockBackend *blk;
NBDExport *exp = g_new0(NBDExport, 1);
uint64_t perm;
int ret;
/*
* NBD exports are used for non-shared storage migration. Make sure
* that BDRV_O_INACTIVE is cleared and the image is ready for write
* access since the export could be available before migration handover.
*/
ctx = bdrv_get_aio_context(bs);
aio_context_acquire(ctx);
bdrv_invalidate_cache(bs, NULL);
aio_context_release(ctx);
/* Don't allow resize while the NBD server is running, otherwise we don't
* care what happens with the node. */
perm = BLK_PERM_CONSISTENT_READ;
if ((nbdflags & NBD_FLAG_READ_ONLY) == 0) {
perm |= BLK_PERM_WRITE;
}
blk = blk_new(perm, BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED |
BLK_PERM_WRITE | BLK_PERM_GRAPH_MOD);
ret = blk_insert_bs(blk, bs, errp);
if (ret < 0) {
goto fail;
}
blk_set_enable_write_cache(blk, !writethrough);
exp->refcount = 1;
QTAILQ_INIT(&exp->clients);
exp->blk = blk;
exp->dev_offset = dev_offset;
exp->nbdflags = nbdflags;
exp->size = size < 0 ? blk_getlength(blk) : size;
if (exp->size < 0) {
error_setg_errno(errp, -exp->size,
"Failed to determine the NBD export's length");
goto fail;
}
exp->size -= exp->size % BDRV_SECTOR_SIZE;
exp->close = close;
exp->ctx = blk_get_aio_context(blk);
blk_add_aio_context_notifier(blk, blk_aio_attached, blk_aio_detach, exp);
if (on_eject_blk) {
blk_ref(on_eject_blk);
exp->eject_notifier_blk = on_eject_blk;
exp->eject_notifier.notify = nbd_eject_notifier;
blk_add_remove_bs_notifier(on_eject_blk, &exp->eject_notifier);
}
return exp;
fail:
blk_unref(blk);
g_free(exp);
return NULL;
}
NBDExport *nbd_export_find(const char *name)
{
NBDExport *exp;
QTAILQ_FOREACH(exp, &exports, next) {
if (strcmp(name, exp->name) == 0) {
return exp;
}
}
return NULL;
}
void nbd_export_set_name(NBDExport *exp, const char *name)
{
if (exp->name == name) {
return;
}
nbd_export_get(exp);
if (exp->name != NULL) {
g_free(exp->name);
exp->name = NULL;
QTAILQ_REMOVE(&exports, exp, next);
nbd_export_put(exp);
}
if (name != NULL) {
nbd_export_get(exp);
exp->name = g_strdup(name);
QTAILQ_INSERT_TAIL(&exports, exp, next);
}
nbd_export_put(exp);
}
void nbd_export_set_description(NBDExport *exp, const char *description)
{
g_free(exp->description);
exp->description = g_strdup(description);
}
void nbd_export_close(NBDExport *exp)
{
NBDClient *client, *next;
nbd_export_get(exp);
QTAILQ_FOREACH_SAFE(client, &exp->clients, next, next) {
client_close(client, true);
}
nbd_export_set_name(exp, NULL);
nbd_export_set_description(exp, NULL);
nbd_export_put(exp);
}
void nbd_export_get(NBDExport *exp)
{
assert(exp->refcount > 0);
exp->refcount++;
}
void nbd_export_put(NBDExport *exp)
{
assert(exp->refcount > 0);
if (exp->refcount == 1) {
nbd_export_close(exp);
}
if (--exp->refcount == 0) {
assert(exp->name == NULL);
assert(exp->description == NULL);
if (exp->close) {
exp->close(exp);
}
if (exp->blk) {
if (exp->eject_notifier_blk) {
notifier_remove(&exp->eject_notifier);
blk_unref(exp->eject_notifier_blk);
}
blk_remove_aio_context_notifier(exp->blk, blk_aio_attached,
blk_aio_detach, exp);
blk_unref(exp->blk);
exp->blk = NULL;
}
g_free(exp);
}
}
BlockBackend *nbd_export_get_blockdev(NBDExport *exp)
{
return exp->blk;
}
void nbd_export_close_all(void)
{
NBDExport *exp, *next;
QTAILQ_FOREACH_SAFE(exp, &exports, next, next) {
nbd_export_close(exp);
}
}
static int coroutine_fn nbd_co_send_iov(NBDClient *client, struct iovec *iov,
unsigned niov, Error **errp)
{
int ret;
g_assert(qemu_in_coroutine());
qemu_co_mutex_lock(&client->send_lock);
client->send_coroutine = qemu_coroutine_self();
ret = qio_channel_writev_all(client->ioc, iov, niov, errp) < 0 ? -EIO : 0;
client->send_coroutine = NULL;
qemu_co_mutex_unlock(&client->send_lock);
return ret;
}
static inline void set_be_simple_reply(NBDSimpleReply *reply, uint64_t error,
uint64_t handle)
{
stl_be_p(&reply->magic, NBD_SIMPLE_REPLY_MAGIC);
stl_be_p(&reply->error, error);
stq_be_p(&reply->handle, handle);
}
static int nbd_co_send_simple_reply(NBDClient *client,
uint64_t handle,
uint32_t error,
void *data,
size_t len,
Error **errp)
{
NBDSimpleReply reply;
int nbd_err = system_errno_to_nbd_errno(error);
struct iovec iov[] = {
{.iov_base = &reply, .iov_len = sizeof(reply)},
{.iov_base = data, .iov_len = len}
};
trace_nbd_co_send_simple_reply(handle, nbd_err, len);
set_be_simple_reply(&reply, nbd_err, handle);
return nbd_co_send_iov(client, iov, len ? 2 : 1, errp);
}
/* nbd_co_receive_request
* Collect a client request. Return 0 if request looks valid, -EIO to drop
* connection right away, and any other negative value to report an error to
* the client (although the caller may still need to disconnect after reporting
* the error).
*/
static int nbd_co_receive_request(NBDRequestData *req, NBDRequest *request,
Error **errp)
{
NBDClient *client = req->client;
g_assert(qemu_in_coroutine());
assert(client->recv_coroutine == qemu_coroutine_self());
if (nbd_receive_request(client->ioc, request, errp) < 0) {
return -EIO;
}
trace_nbd_co_receive_request_decode_type(request->handle, request->type,
nbd_cmd_lookup(request->type));
if (request->type != NBD_CMD_WRITE) {
/* No payload, we are ready to read the next request. */
req->complete = true;
}
if (request->type == NBD_CMD_DISC) {
/* Special case: we're going to disconnect without a reply,
* whether or not flags, from, or len are bogus */
return -EIO;
}
/* Check for sanity in the parameters, part 1. Defer as many
* checks as possible until after reading any NBD_CMD_WRITE
* payload, so we can try and keep the connection alive. */
if ((request->from + request->len) < request->from) {
error_setg(errp,
"integer overflow detected, you're probably being attacked");
return -EINVAL;
}
if (request->type == NBD_CMD_READ || request->type == NBD_CMD_WRITE) {
if (request->len > NBD_MAX_BUFFER_SIZE) {
error_setg(errp, "len (%" PRIu32" ) is larger than max len (%u)",
request->len, NBD_MAX_BUFFER_SIZE);
return -EINVAL;
}
req->data = blk_try_blockalign(client->exp->blk, request->len);
if (req->data == NULL) {
error_setg(errp, "No memory");
return -ENOMEM;
}
}
if (request->type == NBD_CMD_WRITE) {
if (nbd_read(client->ioc, req->data, request->len, errp) < 0) {
error_prepend(errp, "reading from socket failed: ");
return -EIO;
}
req->complete = true;
trace_nbd_co_receive_request_payload_received(request->handle,
request->len);
}
/* Sanity checks, part 2. */
if (request->from + request->len > client->exp->size) {
error_setg(errp, "operation past EOF; From: %" PRIu64 ", Len: %" PRIu32
", Size: %" PRIu64, request->from, request->len,
(uint64_t)client->exp->size);
return request->type == NBD_CMD_WRITE ? -ENOSPC : -EINVAL;
}
if (request->flags & ~(NBD_CMD_FLAG_FUA | NBD_CMD_FLAG_NO_HOLE)) {
error_setg(errp, "unsupported flags (got 0x%x)", request->flags);
return -EINVAL;
}
if (request->type != NBD_CMD_WRITE_ZEROES &&
(request->flags & NBD_CMD_FLAG_NO_HOLE)) {
error_setg(errp, "unexpected flags (got 0x%x)", request->flags);
return -EINVAL;
}
return 0;
}
/* Owns a reference to the NBDClient passed as opaque. */
static coroutine_fn void nbd_trip(void *opaque)
{
NBDClient *client = opaque;
NBDExport *exp = client->exp;
NBDRequestData *req;
NBDRequest request = { 0 }; /* GCC thinks it can be used uninitialized */
int ret;
int flags;
int reply_data_len = 0;
Error *local_err = NULL;
trace_nbd_trip();
if (client->closing) {
nbd_client_put(client);
return;
}
req = nbd_request_get(client);
ret = nbd_co_receive_request(req, &request, &local_err);
client->recv_coroutine = NULL;
nbd_client_receive_next_request(client);
if (ret == -EIO) {
goto disconnect;
}
if (ret < 0) {
goto reply;
}
if (client->closing) {
/*
* The client may be closed when we are blocked in
* nbd_co_receive_request()
*/
goto done;
}
switch (request.type) {
case NBD_CMD_READ:
/* XXX: NBD Protocol only documents use of FUA with WRITE */
if (request.flags & NBD_CMD_FLAG_FUA) {
ret = blk_co_flush(exp->blk);
if (ret < 0) {
error_setg_errno(&local_err, -ret, "flush failed");
break;
}
}
ret = blk_pread(exp->blk, request.from + exp->dev_offset,
req->data, request.len);
if (ret < 0) {
error_setg_errno(&local_err, -ret, "reading from file failed");
break;
}
reply_data_len = request.len;
break;
case NBD_CMD_WRITE:
if (exp->nbdflags & NBD_FLAG_READ_ONLY) {
ret = -EROFS;
break;
}
flags = 0;
if (request.flags & NBD_CMD_FLAG_FUA) {
flags |= BDRV_REQ_FUA;
}
ret = blk_pwrite(exp->blk, request.from + exp->dev_offset,
req->data, request.len, flags);
if (ret < 0) {
error_setg_errno(&local_err, -ret, "writing to file failed");
}
break;
case NBD_CMD_WRITE_ZEROES:
if (exp->nbdflags & NBD_FLAG_READ_ONLY) {
error_setg(&local_err, "Server is read-only, return error");
ret = -EROFS;
break;
}
flags = 0;
if (request.flags & NBD_CMD_FLAG_FUA) {
flags |= BDRV_REQ_FUA;
}
if (!(request.flags & NBD_CMD_FLAG_NO_HOLE)) {
flags |= BDRV_REQ_MAY_UNMAP;
}
ret = blk_pwrite_zeroes(exp->blk, request.from + exp->dev_offset,
request.len, flags);
if (ret < 0) {
error_setg_errno(&local_err, -ret, "writing to file failed");
}
break;
case NBD_CMD_DISC:
/* unreachable, thanks to special case in nbd_co_receive_request() */
abort();
case NBD_CMD_FLUSH:
ret = blk_co_flush(exp->blk);
if (ret < 0) {
error_setg_errno(&local_err, -ret, "flush failed");
}
break;
case NBD_CMD_TRIM:
ret = blk_co_pdiscard(exp->blk, request.from + exp->dev_offset,
request.len);
if (ret < 0) {
error_setg_errno(&local_err, -ret, "discard failed");
}
break;
default:
error_setg(&local_err, "invalid request type (%" PRIu32 ") received",
request.type);
ret = -EINVAL;
}
reply:
if (local_err) {
/* If we get here, local_err was not a fatal error, and should be sent
* to the client. */
error_report_err(local_err);
local_err = NULL;
}
if (nbd_co_send_simple_reply(req->client, request.handle,
ret < 0 ? -ret : 0,
req->data, reply_data_len, &local_err) < 0)
{
error_prepend(&local_err, "Failed to send reply: ");
goto disconnect;
}
/* We must disconnect after NBD_CMD_WRITE if we did not
* read the payload.
*/
if (!req->complete) {
error_setg(&local_err, "Request handling failed in intermediate state");
goto disconnect;
}
done:
nbd_request_put(req);
nbd_client_put(client);
return;
disconnect:
if (local_err) {
error_reportf_err(local_err, "Disconnect client, due to: ");
}
nbd_request_put(req);
client_close(client, true);
nbd_client_put(client);
}
static void nbd_client_receive_next_request(NBDClient *client)
{
if (!client->recv_coroutine && client->nb_requests < MAX_NBD_REQUESTS) {
nbd_client_get(client);
client->recv_coroutine = qemu_coroutine_create(nbd_trip, client);
aio_co_schedule(client->exp->ctx, client->recv_coroutine);
}
}
static coroutine_fn void nbd_co_client_start(void *opaque)
{
NBDClient *client = opaque;
NBDExport *exp = client->exp;
Error *local_err = NULL;
if (exp) {
nbd_export_get(exp);
QTAILQ_INSERT_TAIL(&exp->clients, client, next);
}
qemu_co_mutex_init(&client->send_lock);
if (nbd_negotiate(client, &local_err)) {
if (local_err) {
error_report_err(local_err);
}
client_close(client, false);
return;
}
nbd_client_receive_next_request(client);
}
/*
* Create a new client listener on the given export @exp, using the
* given channel @sioc. Begin servicing it in a coroutine. When the
* connection closes, call @close_fn with an indication of whether the
* client completed negotiation.
*/
void nbd_client_new(NBDExport *exp,
QIOChannelSocket *sioc,
QCryptoTLSCreds *tlscreds,
const char *tlsaclname,
void (*close_fn)(NBDClient *, bool))
{
NBDClient *client;
Coroutine *co;
client = g_new0(NBDClient, 1);
client->refcount = 1;
client->exp = exp;
client->tlscreds = tlscreds;
if (tlscreds) {
object_ref(OBJECT(client->tlscreds));
}
client->tlsaclname = g_strdup(tlsaclname);
client->sioc = sioc;
object_ref(OBJECT(client->sioc));
client->ioc = QIO_CHANNEL(sioc);
object_ref(OBJECT(client->ioc));
client->close_fn = close_fn;
co = qemu_coroutine_create(nbd_co_client_start, client);
qemu_coroutine_enter(co);
}
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