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079d3266c7
qemu-e2k/nbd/server.c
Vladimir Sementsov-Ogievskiy 46321d6b5f nbd/server: fix nbd_negotiate_handle_info 
namelen should be here, length is unrelated, and always 0 at this
point.  Broken in introduction in commit f37708f6, but mostly
harmless (replying with '' as the name does not violate protocol,
and does not confuse qemu as the nbd client since our implementation
does not ask for the name; but might confuse some other client that
does ask for the name especially if the default export is different
than the export name being queried).

Adding an assert makes it obvious that we are not skipping any bytes
in the client's message, as well as making it obvious that we were
using the wrong variable.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
CC: qemu-stable@nongnu.org
Message-Id: <20171101154204.27146-1-vsementsov@virtuozzo.com>
[eblake: improve commit message, squash in assert addition]
Signed-off-by: Eric Blake <eblake@redhat.com>
2017-11-08 16:32:26 -06:00

1649 lines
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/*
* 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 EOVERFLOW:
return NBD_EOVERFLOW;
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;
bool structured_reply;
};
/* 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, Error **errp)
{
NBDExport *exp;
/* 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;
}
}
assert(length == 0);
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, namelen, 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,
Error **errp)
{
QIOChannel *ioc;
QIOChannelTLS *tioc;
struct NBDTLSHandshakeData data = { 0 };
trace_nbd_negotiate_handle_starttls();
ioc = client->ioc;
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_reject_length: Handle any unexpected payload.
* @fatal requests that we quit talking to the client, even if we are able
* to successfully send an error to the guest.
* Return:
* -errno transmission error occurred or @fatal was requested, errp is set
* 0 error message successfully sent to client, errp is not set
*/
static int nbd_reject_length(NBDClient *client, uint32_t length,
uint32_t option, bool fatal, Error **errp)
{
int ret;
assert(length);
if (nbd_drop(client->ioc, length, errp) < 0) {
return -EIO;
}
ret = nbd_negotiate_send_rep_err(client->ioc, NBD_REP_ERR_INVALID,
option, errp,
"option '%s' should have zero length",
nbd_opt_lookup(option));
if (fatal && !ret) {
error_setg(errp, "option '%s' should have zero length",
nbd_opt_lookup(option));
return -EINVAL;
}
return ret;
}
/* 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:
if (length) {
/* Unconditionally drop the connection if the client
* can't start a TLS negotiation correctly */
return nbd_reject_length(client, length, option, true,
errp);
}
tioc = nbd_negotiate_handle_starttls(client, errp);
if (!tioc) {
return -EIO;
}
ret = 0;
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);
/* 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:
if (length) {
ret = nbd_reject_length(client, length, option, false,
errp);
} else {
ret = nbd_negotiate_handle_list(client, errp);
}
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;
}
break;
case NBD_OPT_STARTTLS:
if (length) {
ret = nbd_reject_length(client, length, option, false,
errp);
} else 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");
}
break;
case NBD_OPT_STRUCTURED_REPLY:
if (length) {
ret = nbd_reject_length(client, length, option, false,
errp);
} else if (client->structured_reply) {
ret = nbd_negotiate_send_rep_err(
client->ioc, NBD_REP_ERR_INVALID, option, errp,
"structured reply already negotiated");
} else {
ret = nbd_negotiate_send_rep(client->ioc, NBD_REP_ACK,
option, errp);
client->structured_reply = true;
myflags |= NBD_FLAG_SEND_DF;
}
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));
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;
}
}
if (ret < 0) {
return ret;
}
}
}
/* 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, nbd_err_lookup(nbd_err),
len);
set_be_simple_reply(&reply, nbd_err, handle);
return nbd_co_send_iov(client, iov, len ? 2 : 1, errp);
}
static inline void set_be_chunk(NBDStructuredReplyChunk *chunk, uint16_t flags,
uint16_t type, uint64_t handle, uint32_t length)
{
stl_be_p(&chunk->magic, NBD_STRUCTURED_REPLY_MAGIC);
stw_be_p(&chunk->flags, flags);
stw_be_p(&chunk->type, type);
stq_be_p(&chunk->handle, handle);
stl_be_p(&chunk->length, length);
}
static int coroutine_fn nbd_co_send_structured_read(NBDClient *client,
uint64_t handle,
uint64_t offset,
void *data,
size_t size,
Error **errp)
{
NBDStructuredRead chunk;
struct iovec iov[] = {
{.iov_base = &chunk, .iov_len = sizeof(chunk)},
{.iov_base = data, .iov_len = size}
};
trace_nbd_co_send_structured_read(handle, offset, data, size);
set_be_chunk(&chunk.h, NBD_REPLY_FLAG_DONE, NBD_REPLY_TYPE_OFFSET_DATA,
handle, sizeof(chunk) - sizeof(chunk.h) + size);
stq_be_p(&chunk.offset, offset);
return nbd_co_send_iov(client, iov, 2, errp);
}
static int coroutine_fn nbd_co_send_structured_error(NBDClient *client,
uint64_t handle,
uint32_t error,
const char *msg,
Error **errp)
{
NBDStructuredError chunk;
int nbd_err = system_errno_to_nbd_errno(error);
struct iovec iov[] = {
{.iov_base = &chunk, .iov_len = sizeof(chunk)},
{.iov_base = (char *)msg, .iov_len = msg ? strlen(msg) : 0},
};
assert(nbd_err);
trace_nbd_co_send_structured_error(handle, nbd_err,
nbd_err_lookup(nbd_err), msg ? msg : "");
set_be_chunk(&chunk.h, NBD_REPLY_FLAG_DONE, NBD_REPLY_TYPE_ERROR, handle,
sizeof(chunk) - sizeof(chunk.h) + iov[1].iov_len);
stl_be_p(&chunk.error, nbd_err);
stw_be_p(&chunk.message_length, iov[1].iov_len);
return nbd_co_send_iov(client, iov, 1 + !!iov[1].iov_len, 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;
int valid_flags;
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;
}
valid_flags = NBD_CMD_FLAG_FUA;
if (request->type == NBD_CMD_READ && client->structured_reply) {
valid_flags |= NBD_CMD_FLAG_DF;
} else if (request->type == NBD_CMD_WRITE_ZEROES) {
valid_flags |= NBD_CMD_FLAG_NO_HOLE;
}
if (request->flags & ~valid_flags) {
error_setg(errp, "unsupported flags for command %s (got 0x%x)",
nbd_cmd_lookup(request->type), 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;
char *msg = 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) {
error_setg(&local_err, "Export is 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, "Export is read-only");
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. */
assert(ret < 0);
msg = g_strdup(error_get_pretty(local_err));
error_report_err(local_err);
local_err = NULL;
}
if (client->structured_reply &&
(ret < 0 || request.type == NBD_CMD_READ)) {
if (ret < 0) {
ret = nbd_co_send_structured_error(req->client, request.handle,
-ret, msg, &local_err);
} else {
ret = nbd_co_send_structured_read(req->client, request.handle,
request.from, req->data,
reply_data_len, &local_err);
}
} else {
ret = nbd_co_send_simple_reply(req->client, request.handle,
ret < 0 ? -ret : 0,
req->data, reply_data_len, &local_err);
}
g_free(msg);
if (ret < 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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