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be9c9404db
qemu/block/ssh.c
Eric Blake be9c9404db ssh: Support BDRV_REQ_ZERO_WRITE for truncate 
Our .bdrv_has_zero_init_truncate can detect when the remote side
always zero fills; we can reuse that same knowledge to implement
BDRV_REQ_ZERO_WRITE by ignoring it when the server gives it to us for
free.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200428202905.770727-7-eblake@redhat.com>
Reviewed-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2020-05-08 13:26:35 +02:00

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/*
* Secure Shell (ssh) backend for QEMU.
*
* Copyright (C) 2013 Red Hat Inc., Richard W.M. Jones <rjones@redhat.com>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "qemu/osdep.h"
#include <libssh/libssh.h>
#include <libssh/sftp.h>
#include "block/block_int.h"
#include "block/qdict.h"
#include "qapi/error.h"
#include "qemu/error-report.h"
#include "qemu/module.h"
#include "qemu/option.h"
#include "qemu/ctype.h"
#include "qemu/cutils.h"
#include "qemu/sockets.h"
#include "qemu/uri.h"
#include "qapi/qapi-visit-sockets.h"
#include "qapi/qapi-visit-block-core.h"
#include "qapi/qmp/qdict.h"
#include "qapi/qmp/qstring.h"
#include "qapi/qobject-input-visitor.h"
#include "qapi/qobject-output-visitor.h"
#include "trace.h"
/*
* TRACE_LIBSSH=<level> enables tracing in libssh itself.
* The meaning of <level> is described here:
* http://api.libssh.org/master/group__libssh__log.html
*/
#define TRACE_LIBSSH 0 /* see: SSH_LOG_* */
typedef struct BDRVSSHState {
/* Coroutine. */
CoMutex lock;
/* SSH connection. */
int sock; /* socket */
ssh_session session; /* ssh session */
sftp_session sftp; /* sftp session */
sftp_file sftp_handle; /* sftp remote file handle */
/*
* File attributes at open. We try to keep the .size field
* updated if it changes (eg by writing at the end of the file).
*/
sftp_attributes attrs;
InetSocketAddress *inet;
/* Used to warn if 'flush' is not supported. */
bool unsafe_flush_warning;
/*
* Store the user name for ssh_refresh_filename() because the
* default depends on the system you are on -- therefore, when we
* generate a filename, it should always contain the user name we
* are actually using.
*/
char *user;
} BDRVSSHState;
static void ssh_state_init(BDRVSSHState *s)
{
memset(s, 0, sizeof *s);
s->sock = -1;
qemu_co_mutex_init(&s->lock);
}
static void ssh_state_free(BDRVSSHState *s)
{
g_free(s->user);
if (s->attrs) {
sftp_attributes_free(s->attrs);
}
if (s->sftp_handle) {
sftp_close(s->sftp_handle);
}
if (s->sftp) {
sftp_free(s->sftp);
}
if (s->session) {
ssh_disconnect(s->session);
ssh_free(s->session); /* This frees s->sock */
}
}
static void GCC_FMT_ATTR(3, 4)
session_error_setg(Error **errp, BDRVSSHState *s, const char *fs, ...)
{
va_list args;
char *msg;
va_start(args, fs);
msg = g_strdup_vprintf(fs, args);
va_end(args);
if (s->session) {
const char *ssh_err;
int ssh_err_code;
/* This is not an errno. See <libssh/libssh.h>. */
ssh_err = ssh_get_error(s->session);
ssh_err_code = ssh_get_error_code(s->session);
error_setg(errp, "%s: %s (libssh error code: %d)",
msg, ssh_err, ssh_err_code);
} else {
error_setg(errp, "%s", msg);
}
g_free(msg);
}
static void GCC_FMT_ATTR(3, 4)
sftp_error_setg(Error **errp, BDRVSSHState *s, const char *fs, ...)
{
va_list args;
char *msg;
va_start(args, fs);
msg = g_strdup_vprintf(fs, args);
va_end(args);
if (s->sftp) {
const char *ssh_err;
int ssh_err_code;
int sftp_err_code;
/* This is not an errno. See <libssh/libssh.h>. */
ssh_err = ssh_get_error(s->session);
ssh_err_code = ssh_get_error_code(s->session);
/* See <libssh/sftp.h>. */
sftp_err_code = sftp_get_error(s->sftp);
error_setg(errp,
"%s: %s (libssh error code: %d, sftp error code: %d)",
msg, ssh_err, ssh_err_code, sftp_err_code);
} else {
error_setg(errp, "%s", msg);
}
g_free(msg);
}
static void sftp_error_trace(BDRVSSHState *s, const char *op)
{
const char *ssh_err;
int ssh_err_code;
int sftp_err_code;
/* This is not an errno. See <libssh/libssh.h>. */
ssh_err = ssh_get_error(s->session);
ssh_err_code = ssh_get_error_code(s->session);
/* See <libssh/sftp.h>. */
sftp_err_code = sftp_get_error(s->sftp);
trace_sftp_error(op, ssh_err, ssh_err_code, sftp_err_code);
}
static int parse_uri(const char *filename, QDict *options, Error **errp)
{
URI *uri = NULL;
QueryParams *qp;
char *port_str;
int i;
uri = uri_parse(filename);
if (!uri) {
return -EINVAL;
}
if (g_strcmp0(uri->scheme, "ssh") != 0) {
error_setg(errp, "URI scheme must be 'ssh'");
goto err;
}
if (!uri->server || strcmp(uri->server, "") == 0) {
error_setg(errp, "missing hostname in URI");
goto err;
}
if (!uri->path || strcmp(uri->path, "") == 0) {
error_setg(errp, "missing remote path in URI");
goto err;
}
qp = query_params_parse(uri->query);
if (!qp) {
error_setg(errp, "could not parse query parameters");
goto err;
}
if(uri->user && strcmp(uri->user, "") != 0) {
qdict_put_str(options, "user", uri->user);
}
qdict_put_str(options, "server.host", uri->server);
port_str = g_strdup_printf("%d", uri->port ?: 22);
qdict_put_str(options, "server.port", port_str);
g_free(port_str);
qdict_put_str(options, "path", uri->path);
/* Pick out any query parameters that we understand, and ignore
* the rest.
*/
for (i = 0; i < qp->n; ++i) {
if (strcmp(qp->p[i].name, "host_key_check") == 0) {
qdict_put_str(options, "host_key_check", qp->p[i].value);
}
}
query_params_free(qp);
uri_free(uri);
return 0;
err:
if (uri) {
uri_free(uri);
}
return -EINVAL;
}
static bool ssh_has_filename_options_conflict(QDict *options, Error **errp)
{
const QDictEntry *qe;
for (qe = qdict_first(options); qe; qe = qdict_next(options, qe)) {
if (!strcmp(qe->key, "host") ||
!strcmp(qe->key, "port") ||
!strcmp(qe->key, "path") ||
!strcmp(qe->key, "user") ||
!strcmp(qe->key, "host_key_check") ||
strstart(qe->key, "server.", NULL))
{
error_setg(errp, "Option '%s' cannot be used with a file name",
qe->key);
return true;
}
}
return false;
}
static void ssh_parse_filename(const char *filename, QDict *options,
Error **errp)
{
if (ssh_has_filename_options_conflict(options, errp)) {
return;
}
parse_uri(filename, options, errp);
}
static int check_host_key_knownhosts(BDRVSSHState *s, Error **errp)
{
int ret;
#ifdef HAVE_LIBSSH_0_8
enum ssh_known_hosts_e state;
int r;
ssh_key pubkey;
enum ssh_keytypes_e pubkey_type;
unsigned char *server_hash = NULL;
size_t server_hash_len;
char *fingerprint = NULL;
state = ssh_session_is_known_server(s->session);
trace_ssh_server_status(state);
switch (state) {
case SSH_KNOWN_HOSTS_OK:
/* OK */
trace_ssh_check_host_key_knownhosts();
break;
case SSH_KNOWN_HOSTS_CHANGED:
ret = -EINVAL;
r = ssh_get_server_publickey(s->session, &pubkey);
if (r == 0) {
r = ssh_get_publickey_hash(pubkey, SSH_PUBLICKEY_HASH_SHA256,
&server_hash, &server_hash_len);
pubkey_type = ssh_key_type(pubkey);
ssh_key_free(pubkey);
}
if (r == 0) {
fingerprint = ssh_get_fingerprint_hash(SSH_PUBLICKEY_HASH_SHA256,
server_hash,
server_hash_len);
ssh_clean_pubkey_hash(&server_hash);
}
if (fingerprint) {
error_setg(errp,
"host key (%s key with fingerprint %s) does not match "
"the one in known_hosts; this may be a possible attack",
ssh_key_type_to_char(pubkey_type), fingerprint);
ssh_string_free_char(fingerprint);
} else {
error_setg(errp,
"host key does not match the one in known_hosts; this "
"may be a possible attack");
}
goto out;
case SSH_KNOWN_HOSTS_OTHER:
ret = -EINVAL;
error_setg(errp,
"host key for this server not found, another type exists");
goto out;
case SSH_KNOWN_HOSTS_UNKNOWN:
ret = -EINVAL;
error_setg(errp, "no host key was found in known_hosts");
goto out;
case SSH_KNOWN_HOSTS_NOT_FOUND:
ret = -ENOENT;
error_setg(errp, "known_hosts file not found");
goto out;
case SSH_KNOWN_HOSTS_ERROR:
ret = -EINVAL;
error_setg(errp, "error while checking the host");
goto out;
default:
ret = -EINVAL;
error_setg(errp, "error while checking for known server (%d)", state);
goto out;
}
#else /* !HAVE_LIBSSH_0_8 */
int state;
state = ssh_is_server_known(s->session);
trace_ssh_server_status(state);
switch (state) {
case SSH_SERVER_KNOWN_OK:
/* OK */
trace_ssh_check_host_key_knownhosts();
break;
case SSH_SERVER_KNOWN_CHANGED:
ret = -EINVAL;
error_setg(errp,
"host key does not match the one in known_hosts; this "
"may be a possible attack");
goto out;
case SSH_SERVER_FOUND_OTHER:
ret = -EINVAL;
error_setg(errp,
"host key for this server not found, another type exists");
goto out;
case SSH_SERVER_FILE_NOT_FOUND:
ret = -ENOENT;
error_setg(errp, "known_hosts file not found");
goto out;
case SSH_SERVER_NOT_KNOWN:
ret = -EINVAL;
error_setg(errp, "no host key was found in known_hosts");
goto out;
case SSH_SERVER_ERROR:
ret = -EINVAL;
error_setg(errp, "server error");
goto out;
default:
ret = -EINVAL;
error_setg(errp, "error while checking for known server (%d)", state);
goto out;
}
#endif /* !HAVE_LIBSSH_0_8 */
/* known_hosts checking successful. */
ret = 0;
out:
return ret;
}
static unsigned hex2decimal(char ch)
{
if (ch >= '0' && ch <= '9') {
return (ch - '0');
} else if (ch >= 'a' && ch <= 'f') {
return 10 + (ch - 'a');
} else if (ch >= 'A' && ch <= 'F') {
return 10 + (ch - 'A');
}
return -1;
}
/* Compare the binary fingerprint (hash of host key) with the
* host_key_check parameter.
*/
static int compare_fingerprint(const unsigned char *fingerprint, size_t len,
const char *host_key_check)
{
unsigned c;
while (len > 0) {
while (*host_key_check == ':')
host_key_check++;
if (!qemu_isxdigit(host_key_check[0]) ||
!qemu_isxdigit(host_key_check[1]))
return 1;
c = hex2decimal(host_key_check[0]) * 16 +
hex2decimal(host_key_check[1]);
if (c - *fingerprint != 0)
return c - *fingerprint;
fingerprint++;
len--;
host_key_check += 2;
}
return *host_key_check - '\0';
}
static int
check_host_key_hash(BDRVSSHState *s, const char *hash,
enum ssh_publickey_hash_type type, Error **errp)
{
int r;
ssh_key pubkey;
unsigned char *server_hash;
size_t server_hash_len;
#ifdef HAVE_LIBSSH_0_8
r = ssh_get_server_publickey(s->session, &pubkey);
#else
r = ssh_get_publickey(s->session, &pubkey);
#endif
if (r != SSH_OK) {
session_error_setg(errp, s, "failed to read remote host key");
return -EINVAL;
}
r = ssh_get_publickey_hash(pubkey, type, &server_hash, &server_hash_len);
ssh_key_free(pubkey);
if (r != 0) {
session_error_setg(errp, s,
"failed reading the hash of the server SSH key");
return -EINVAL;
}
r = compare_fingerprint(server_hash, server_hash_len, hash);
ssh_clean_pubkey_hash(&server_hash);
if (r != 0) {
error_setg(errp, "remote host key does not match host_key_check '%s'",
hash);
return -EPERM;
}
return 0;
}
static int check_host_key(BDRVSSHState *s, SshHostKeyCheck *hkc, Error **errp)
{
SshHostKeyCheckMode mode;
if (hkc) {
mode = hkc->mode;
} else {
mode = SSH_HOST_KEY_CHECK_MODE_KNOWN_HOSTS;
}
switch (mode) {
case SSH_HOST_KEY_CHECK_MODE_NONE:
return 0;
case SSH_HOST_KEY_CHECK_MODE_HASH:
if (hkc->u.hash.type == SSH_HOST_KEY_CHECK_HASH_TYPE_MD5) {
return check_host_key_hash(s, hkc->u.hash.hash,
SSH_PUBLICKEY_HASH_MD5, errp);
} else if (hkc->u.hash.type == SSH_HOST_KEY_CHECK_HASH_TYPE_SHA1) {
return check_host_key_hash(s, hkc->u.hash.hash,
SSH_PUBLICKEY_HASH_SHA1, errp);
}
g_assert_not_reached();
break;
case SSH_HOST_KEY_CHECK_MODE_KNOWN_HOSTS:
return check_host_key_knownhosts(s, errp);
default:
g_assert_not_reached();
}
return -EINVAL;
}
static int authenticate(BDRVSSHState *s, Error **errp)
{
int r, ret;
int method;
/* Try to authenticate with the "none" method. */
r = ssh_userauth_none(s->session, NULL);
if (r == SSH_AUTH_ERROR) {
ret = -EPERM;
session_error_setg(errp, s, "failed to authenticate using none "
"authentication");
goto out;
} else if (r == SSH_AUTH_SUCCESS) {
/* Authenticated! */
ret = 0;
goto out;
}
method = ssh_userauth_list(s->session, NULL);
trace_ssh_auth_methods(method);
/*
* Try to authenticate with publickey, using the ssh-agent
* if available.
*/
if (method & SSH_AUTH_METHOD_PUBLICKEY) {
r = ssh_userauth_publickey_auto(s->session, NULL, NULL);
if (r == SSH_AUTH_ERROR) {
ret = -EINVAL;
session_error_setg(errp, s, "failed to authenticate using "
"publickey authentication");
goto out;
} else if (r == SSH_AUTH_SUCCESS) {
/* Authenticated! */
ret = 0;
goto out;
}
}
ret = -EPERM;
error_setg(errp, "failed to authenticate using publickey authentication "
"and the identities held by your ssh-agent");
out:
return ret;
}
static QemuOptsList ssh_runtime_opts = {
.name = "ssh",
.head = QTAILQ_HEAD_INITIALIZER(ssh_runtime_opts.head),
.desc = {
{
.name = "host",
.type = QEMU_OPT_STRING,
.help = "Host to connect to",
},
{
.name = "port",
.type = QEMU_OPT_NUMBER,
.help = "Port to connect to",
},
{
.name = "host_key_check",
.type = QEMU_OPT_STRING,
.help = "Defines how and what to check the host key against",
},
{ /* end of list */ }
},
};
static bool ssh_process_legacy_options(QDict *output_opts,
QemuOpts *legacy_opts,
Error **errp)
{
const char *host = qemu_opt_get(legacy_opts, "host");
const char *port = qemu_opt_get(legacy_opts, "port");
const char *host_key_check = qemu_opt_get(legacy_opts, "host_key_check");
if (!host && port) {
error_setg(errp, "port may not be used without host");
return false;
}
if (host) {
qdict_put_str(output_opts, "server.host", host);
qdict_put_str(output_opts, "server.port", port ?: stringify(22));
}
if (host_key_check) {
if (strcmp(host_key_check, "no") == 0) {
qdict_put_str(output_opts, "host-key-check.mode", "none");
} else if (strncmp(host_key_check, "md5:", 4) == 0) {
qdict_put_str(output_opts, "host-key-check.mode", "hash");
qdict_put_str(output_opts, "host-key-check.type", "md5");
qdict_put_str(output_opts, "host-key-check.hash",
&host_key_check[4]);
} else if (strncmp(host_key_check, "sha1:", 5) == 0) {
qdict_put_str(output_opts, "host-key-check.mode", "hash");
qdict_put_str(output_opts, "host-key-check.type", "sha1");
qdict_put_str(output_opts, "host-key-check.hash",
&host_key_check[5]);
} else if (strcmp(host_key_check, "yes") == 0) {
qdict_put_str(output_opts, "host-key-check.mode", "known_hosts");
} else {
error_setg(errp, "unknown host_key_check setting (%s)",
host_key_check);
return false;
}
}
return true;
}
static BlockdevOptionsSsh *ssh_parse_options(QDict *options, Error **errp)
{
BlockdevOptionsSsh *result = NULL;
QemuOpts *opts = NULL;
Error *local_err = NULL;
const QDictEntry *e;
Visitor *v;
/* Translate legacy options */
opts = qemu_opts_create(&ssh_runtime_opts, NULL, 0, &error_abort);
qemu_opts_absorb_qdict(opts, options, &local_err);
if (local_err) {
error_propagate(errp, local_err);
goto fail;
}
if (!ssh_process_legacy_options(options, opts, errp)) {
goto fail;
}
/* Create the QAPI object */
v = qobject_input_visitor_new_flat_confused(options, errp);
if (!v) {
goto fail;
}
visit_type_BlockdevOptionsSsh(v, NULL, &result, &local_err);
visit_free(v);
if (local_err) {
error_propagate(errp, local_err);
goto fail;
}
/* Remove the processed options from the QDict (the visitor processes
* _all_ options in the QDict) */
while ((e = qdict_first(options))) {
qdict_del(options, e->key);
}
fail:
qemu_opts_del(opts);
return result;
}
static int connect_to_ssh(BDRVSSHState *s, BlockdevOptionsSsh *opts,
int ssh_flags, int creat_mode, Error **errp)
{
int r, ret;
unsigned int port = 0;
int new_sock = -1;
if (opts->has_user) {
s->user = g_strdup(opts->user);
} else {
s->user = g_strdup(g_get_user_name());
if (!s->user) {
error_setg_errno(errp, errno, "Can't get user name");
ret = -errno;
goto err;
}
}
/* Pop the config into our state object, Exit if invalid */
s->inet = opts->server;
opts->server = NULL;
if (qemu_strtoui(s->inet->port, NULL, 10, &port) < 0) {
error_setg(errp, "Use only numeric port value");
ret = -EINVAL;
goto err;
}
/* Open the socket and connect. */
new_sock = inet_connect_saddr(s->inet, errp);
if (new_sock < 0) {
ret = -EIO;
goto err;
}
/*
* Try to disable the Nagle algorithm on TCP sockets to reduce latency,
* but do not fail if it cannot be disabled.
*/
r = socket_set_nodelay(new_sock);
if (r < 0) {
warn_report("can't set TCP_NODELAY for the ssh server %s: %s",
s->inet->host, strerror(errno));
}
/* Create SSH session. */
s->session = ssh_new();
if (!s->session) {
ret = -EINVAL;
session_error_setg(errp, s, "failed to initialize libssh session");
goto err;
}
/*
* Make sure we are in blocking mode during the connection and
* authentication phases.
*/
ssh_set_blocking(s->session, 1);
r = ssh_options_set(s->session, SSH_OPTIONS_USER, s->user);
if (r < 0) {
ret = -EINVAL;
session_error_setg(errp, s,
"failed to set the user in the libssh session");
goto err;
}
r = ssh_options_set(s->session, SSH_OPTIONS_HOST, s->inet->host);
if (r < 0) {
ret = -EINVAL;
session_error_setg(errp, s,
"failed to set the host in the libssh session");
goto err;
}
if (port > 0) {
r = ssh_options_set(s->session, SSH_OPTIONS_PORT, &port);
if (r < 0) {
ret = -EINVAL;
session_error_setg(errp, s,
"failed to set the port in the libssh session");
goto err;
}
}
r = ssh_options_set(s->session, SSH_OPTIONS_COMPRESSION, "none");
if (r < 0) {
ret = -EINVAL;
session_error_setg(errp, s,
"failed to disable the compression in the libssh "
"session");
goto err;
}
/* Read ~/.ssh/config. */
r = ssh_options_parse_config(s->session, NULL);
if (r < 0) {
ret = -EINVAL;
session_error_setg(errp, s, "failed to parse ~/.ssh/config");
goto err;
}
r = ssh_options_set(s->session, SSH_OPTIONS_FD, &new_sock);
if (r < 0) {
ret = -EINVAL;
session_error_setg(errp, s,
"failed to set the socket in the libssh session");
goto err;
}
/* libssh took ownership of the socket. */
s->sock = new_sock;
new_sock = -1;
/* Connect. */
r = ssh_connect(s->session);
if (r != SSH_OK) {
ret = -EINVAL;
session_error_setg(errp, s, "failed to establish SSH session");
goto err;
}
/* Check the remote host's key against known_hosts. */
ret = check_host_key(s, opts->host_key_check, errp);
if (ret < 0) {
goto err;
}
/* Authenticate. */
ret = authenticate(s, errp);
if (ret < 0) {
goto err;
}
/* Start SFTP. */
s->sftp = sftp_new(s->session);
if (!s->sftp) {
session_error_setg(errp, s, "failed to create sftp handle");
ret = -EINVAL;
goto err;
}
r = sftp_init(s->sftp);
if (r < 0) {
sftp_error_setg(errp, s, "failed to initialize sftp handle");
ret = -EINVAL;
goto err;
}
/* Open the remote file. */
trace_ssh_connect_to_ssh(opts->path, ssh_flags, creat_mode);
s->sftp_handle = sftp_open(s->sftp, opts->path, ssh_flags, creat_mode);
if (!s->sftp_handle) {
sftp_error_setg(errp, s, "failed to open remote file '%s'",
opts->path);
ret = -EINVAL;
goto err;
}
/* Make sure the SFTP file is handled in blocking mode. */
sftp_file_set_blocking(s->sftp_handle);
s->attrs = sftp_fstat(s->sftp_handle);
if (!s->attrs) {
sftp_error_setg(errp, s, "failed to read file attributes");
return -EINVAL;
}
return 0;
err:
if (s->attrs) {
sftp_attributes_free(s->attrs);
}
s->attrs = NULL;
if (s->sftp_handle) {
sftp_close(s->sftp_handle);
}
s->sftp_handle = NULL;
if (s->sftp) {
sftp_free(s->sftp);
}
s->sftp = NULL;
if (s->session) {
ssh_disconnect(s->session);
ssh_free(s->session);
}
s->session = NULL;
s->sock = -1;
if (new_sock >= 0) {
close(new_sock);
}
return ret;
}
static int ssh_file_open(BlockDriverState *bs, QDict *options, int bdrv_flags,
Error **errp)
{
BDRVSSHState *s = bs->opaque;
BlockdevOptionsSsh *opts;
int ret;
int ssh_flags;
ssh_state_init(s);
ssh_flags = 0;
if (bdrv_flags & BDRV_O_RDWR) {
ssh_flags |= O_RDWR;
} else {
ssh_flags |= O_RDONLY;
}
opts = ssh_parse_options(options, errp);
if (opts == NULL) {
return -EINVAL;
}
/* Start up SSH. */
ret = connect_to_ssh(s, opts, ssh_flags, 0, errp);
if (ret < 0) {
goto err;
}
/* Go non-blocking. */
ssh_set_blocking(s->session, 0);
if (s->attrs->type == SSH_FILEXFER_TYPE_REGULAR) {
bs->supported_truncate_flags = BDRV_REQ_ZERO_WRITE;
}
qapi_free_BlockdevOptionsSsh(opts);
return 0;
err:
qapi_free_BlockdevOptionsSsh(opts);
return ret;
}
/* Note: This is a blocking operation */
static int ssh_grow_file(BDRVSSHState *s, int64_t offset, Error **errp)
{
ssize_t ret;
char c[1] = { '\0' };
int was_blocking = ssh_is_blocking(s->session);
/* offset must be strictly greater than the current size so we do
* not overwrite anything */
assert(offset > 0 && offset > s->attrs->size);
ssh_set_blocking(s->session, 1);
sftp_seek64(s->sftp_handle, offset - 1);
ret = sftp_write(s->sftp_handle, c, 1);
ssh_set_blocking(s->session, was_blocking);
if (ret < 0) {
sftp_error_setg(errp, s, "Failed to grow file");
return -EIO;
}
s->attrs->size = offset;
return 0;
}
static QemuOptsList ssh_create_opts = {
.name = "ssh-create-opts",
.head = QTAILQ_HEAD_INITIALIZER(ssh_create_opts.head),
.desc = {
{
.name = BLOCK_OPT_SIZE,
.type = QEMU_OPT_SIZE,
.help = "Virtual disk size"
},
{ /* end of list */ }
}
};
static int ssh_co_create(BlockdevCreateOptions *options, Error **errp)
{
BlockdevCreateOptionsSsh *opts = &options->u.ssh;
BDRVSSHState s;
int ret;
assert(options->driver == BLOCKDEV_DRIVER_SSH);
ssh_state_init(&s);
ret = connect_to_ssh(&s, opts->location,
O_RDWR | O_CREAT | O_TRUNC,
0644, errp);
if (ret < 0) {
goto fail;
}
if (opts->size > 0) {
ret = ssh_grow_file(&s, opts->size, errp);
if (ret < 0) {
goto fail;
}
}
ret = 0;
fail:
ssh_state_free(&s);
return ret;
}
static int coroutine_fn ssh_co_create_opts(BlockDriver *drv,
const char *filename,
QemuOpts *opts,
Error **errp)
{
BlockdevCreateOptions *create_options;
BlockdevCreateOptionsSsh *ssh_opts;
int ret;
QDict *uri_options = NULL;
create_options = g_new0(BlockdevCreateOptions, 1);
create_options->driver = BLOCKDEV_DRIVER_SSH;
ssh_opts = &create_options->u.ssh;
/* Get desired file size. */
ssh_opts->size = ROUND_UP(qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0),
BDRV_SECTOR_SIZE);
trace_ssh_co_create_opts(ssh_opts->size);
uri_options = qdict_new();
ret = parse_uri(filename, uri_options, errp);
if (ret < 0) {
goto out;
}
ssh_opts->location = ssh_parse_options(uri_options, errp);
if (ssh_opts->location == NULL) {
ret = -EINVAL;
goto out;
}
ret = ssh_co_create(create_options, errp);
out:
qobject_unref(uri_options);
qapi_free_BlockdevCreateOptions(create_options);
return ret;
}
static void ssh_close(BlockDriverState *bs)
{
BDRVSSHState *s = bs->opaque;
ssh_state_free(s);
}
static int ssh_has_zero_init(BlockDriverState *bs)
{
BDRVSSHState *s = bs->opaque;
/* Assume false, unless we can positively prove it's true. */
int has_zero_init = 0;
if (s->attrs->type == SSH_FILEXFER_TYPE_REGULAR) {
has_zero_init = 1;
}
return has_zero_init;
}
typedef struct BDRVSSHRestart {
BlockDriverState *bs;
Coroutine *co;
} BDRVSSHRestart;
static void restart_coroutine(void *opaque)
{
BDRVSSHRestart *restart = opaque;
BlockDriverState *bs = restart->bs;
BDRVSSHState *s = bs->opaque;
AioContext *ctx = bdrv_get_aio_context(bs);
trace_ssh_restart_coroutine(restart->co);
aio_set_fd_handler(ctx, s->sock, false, NULL, NULL, NULL, NULL);
aio_co_wake(restart->co);
}
/* A non-blocking call returned EAGAIN, so yield, ensuring the
* handlers are set up so that we'll be rescheduled when there is an
* interesting event on the socket.
*/
static coroutine_fn void co_yield(BDRVSSHState *s, BlockDriverState *bs)
{
int r;
IOHandler *rd_handler = NULL, *wr_handler = NULL;
BDRVSSHRestart restart = {
.bs = bs,
.co = qemu_coroutine_self()
};
r = ssh_get_poll_flags(s->session);
if (r & SSH_READ_PENDING) {
rd_handler = restart_coroutine;
}
if (r & SSH_WRITE_PENDING) {
wr_handler = restart_coroutine;
}
trace_ssh_co_yield(s->sock, rd_handler, wr_handler);
aio_set_fd_handler(bdrv_get_aio_context(bs), s->sock,
false, rd_handler, wr_handler, NULL, &restart);
qemu_coroutine_yield();
trace_ssh_co_yield_back(s->sock);
}
static coroutine_fn int ssh_read(BDRVSSHState *s, BlockDriverState *bs,
int64_t offset, size_t size,
QEMUIOVector *qiov)
{
ssize_t r;
size_t got;
char *buf, *end_of_vec;
struct iovec *i;
trace_ssh_read(offset, size);
trace_ssh_seek(offset);
sftp_seek64(s->sftp_handle, offset);
/* This keeps track of the current iovec element ('i'), where we
* will write to next ('buf'), and the end of the current iovec
* ('end_of_vec').
*/
i = &qiov->iov[0];
buf = i->iov_base;
end_of_vec = i->iov_base + i->iov_len;
for (got = 0; got < size; ) {
size_t request_read_size;
again:
/*
* The size of SFTP packets is limited to 32K bytes, so limit
* the amount of data requested to 16K, as libssh currently
* does not handle multiple requests on its own.
*/
request_read_size = MIN(end_of_vec - buf, 16384);
trace_ssh_read_buf(buf, end_of_vec - buf, request_read_size);
r = sftp_read(s->sftp_handle, buf, request_read_size);
trace_ssh_read_return(r, sftp_get_error(s->sftp));
if (r == SSH_AGAIN) {
co_yield(s, bs);
goto again;
}
if (r == SSH_EOF || (r == 0 && sftp_get_error(s->sftp) == SSH_FX_EOF)) {
/* EOF: Short read so pad the buffer with zeroes and return it. */
qemu_iovec_memset(qiov, got, 0, size - got);
return 0;
}
if (r <= 0) {
sftp_error_trace(s, "read");
return -EIO;
}
got += r;
buf += r;
if (buf >= end_of_vec && got < size) {
i++;
buf = i->iov_base;
end_of_vec = i->iov_base + i->iov_len;
}
}
return 0;
}
static coroutine_fn int ssh_co_readv(BlockDriverState *bs,
int64_t sector_num,
int nb_sectors, QEMUIOVector *qiov)
{
BDRVSSHState *s = bs->opaque;
int ret;
qemu_co_mutex_lock(&s->lock);
ret = ssh_read(s, bs, sector_num * BDRV_SECTOR_SIZE,
nb_sectors * BDRV_SECTOR_SIZE, qiov);
qemu_co_mutex_unlock(&s->lock);
return ret;
}
static int ssh_write(BDRVSSHState *s, BlockDriverState *bs,
int64_t offset, size_t size,
QEMUIOVector *qiov)
{
ssize_t r;
size_t written;
char *buf, *end_of_vec;
struct iovec *i;
trace_ssh_write(offset, size);
trace_ssh_seek(offset);
sftp_seek64(s->sftp_handle, offset);
/* This keeps track of the current iovec element ('i'), where we
* will read from next ('buf'), and the end of the current iovec
* ('end_of_vec').
*/
i = &qiov->iov[0];
buf = i->iov_base;
end_of_vec = i->iov_base + i->iov_len;
for (written = 0; written < size; ) {
size_t request_write_size;
again:
/*
* Avoid too large data packets, as libssh currently does not
* handle multiple requests on its own.
*/
request_write_size = MIN(end_of_vec - buf, 131072);
trace_ssh_write_buf(buf, end_of_vec - buf, request_write_size);
r = sftp_write(s->sftp_handle, buf, request_write_size);
trace_ssh_write_return(r, sftp_get_error(s->sftp));
if (r == SSH_AGAIN) {
co_yield(s, bs);
goto again;
}
if (r < 0) {
sftp_error_trace(s, "write");
return -EIO;
}
written += r;
buf += r;
if (buf >= end_of_vec && written < size) {
i++;
buf = i->iov_base;
end_of_vec = i->iov_base + i->iov_len;
}
if (offset + written > s->attrs->size) {
s->attrs->size = offset + written;
}
}
return 0;
}
static coroutine_fn int ssh_co_writev(BlockDriverState *bs,
int64_t sector_num,
int nb_sectors, QEMUIOVector *qiov,
int flags)
{
BDRVSSHState *s = bs->opaque;
int ret;
assert(!flags);
qemu_co_mutex_lock(&s->lock);
ret = ssh_write(s, bs, sector_num * BDRV_SECTOR_SIZE,
nb_sectors * BDRV_SECTOR_SIZE, qiov);
qemu_co_mutex_unlock(&s->lock);
return ret;
}
static void unsafe_flush_warning(BDRVSSHState *s, const char *what)
{
if (!s->unsafe_flush_warning) {
warn_report("ssh server %s does not support fsync",
s->inet->host);
if (what) {
error_report("to support fsync, you need %s", what);
}
s->unsafe_flush_warning = true;
}
}
#ifdef HAVE_LIBSSH_0_8
static coroutine_fn int ssh_flush(BDRVSSHState *s, BlockDriverState *bs)
{
int r;
trace_ssh_flush();
if (!sftp_extension_supported(s->sftp, "fsync@openssh.com", "1")) {
unsafe_flush_warning(s, "OpenSSH >= 6.3");
return 0;
}
again:
r = sftp_fsync(s->sftp_handle);
if (r == SSH_AGAIN) {
co_yield(s, bs);
goto again;
}
if (r < 0) {
sftp_error_trace(s, "fsync");
return -EIO;
}
return 0;
}
static coroutine_fn int ssh_co_flush(BlockDriverState *bs)
{
BDRVSSHState *s = bs->opaque;
int ret;
qemu_co_mutex_lock(&s->lock);
ret = ssh_flush(s, bs);
qemu_co_mutex_unlock(&s->lock);
return ret;
}
#else /* !HAVE_LIBSSH_0_8 */
static coroutine_fn int ssh_co_flush(BlockDriverState *bs)
{
BDRVSSHState *s = bs->opaque;
unsafe_flush_warning(s, "libssh >= 0.8.0");
return 0;
}
#endif /* !HAVE_LIBSSH_0_8 */
static int64_t ssh_getlength(BlockDriverState *bs)
{
BDRVSSHState *s = bs->opaque;
int64_t length;
/* Note we cannot make a libssh call here. */
length = (int64_t) s->attrs->size;
trace_ssh_getlength(length);
return length;
}
static int coroutine_fn ssh_co_truncate(BlockDriverState *bs, int64_t offset,
bool exact, PreallocMode prealloc,
BdrvRequestFlags flags, Error **errp)
{
BDRVSSHState *s = bs->opaque;
if (prealloc != PREALLOC_MODE_OFF) {
error_setg(errp, "Unsupported preallocation mode '%s'",
PreallocMode_str(prealloc));
return -ENOTSUP;
}
if (offset < s->attrs->size) {
error_setg(errp, "ssh driver does not support shrinking files");
return -ENOTSUP;
}
if (offset == s->attrs->size) {
return 0;
}
return ssh_grow_file(s, offset, errp);
}
static void ssh_refresh_filename(BlockDriverState *bs)
{
BDRVSSHState *s = bs->opaque;
const char *path, *host_key_check;
int ret;
/*
* None of these options can be represented in a plain "host:port"
* format, so if any was given, we have to abort.
*/
if (s->inet->has_ipv4 || s->inet->has_ipv6 || s->inet->has_to ||
s->inet->has_numeric)
{
return;
}
path = qdict_get_try_str(bs->full_open_options, "path");
assert(path); /* mandatory option */
host_key_check = qdict_get_try_str(bs->full_open_options, "host_key_check");
ret = snprintf(bs->exact_filename, sizeof(bs->exact_filename),
"ssh://%s@%s:%s%s%s%s",
s->user, s->inet->host, s->inet->port, path,
host_key_check ? "?host_key_check=" : "",
host_key_check ?: "");
if (ret >= sizeof(bs->exact_filename)) {
/* An overflow makes the filename unusable, so do not report any */
bs->exact_filename[0] = '\0';
}
}
static char *ssh_bdrv_dirname(BlockDriverState *bs, Error **errp)
{
if (qdict_haskey(bs->full_open_options, "host_key_check")) {
/*
* We cannot generate a simple prefix if we would have to
* append a query string.
*/
error_setg(errp,
"Cannot generate a base directory with host_key_check set");
return NULL;
}
if (bs->exact_filename[0] == '\0') {
error_setg(errp, "Cannot generate a base directory for this ssh node");
return NULL;
}
return path_combine(bs->exact_filename, "");
}
static const char *const ssh_strong_runtime_opts[] = {
"host",
"port",
"path",
"user",
"host_key_check",
"server.",
NULL
};
static BlockDriver bdrv_ssh = {
.format_name = "ssh",
.protocol_name = "ssh",
.instance_size = sizeof(BDRVSSHState),
.bdrv_parse_filename = ssh_parse_filename,
.bdrv_file_open = ssh_file_open,
.bdrv_co_create = ssh_co_create,
.bdrv_co_create_opts = ssh_co_create_opts,
.bdrv_close = ssh_close,
.bdrv_has_zero_init = ssh_has_zero_init,
.bdrv_has_zero_init_truncate = ssh_has_zero_init,
.bdrv_co_readv = ssh_co_readv,
.bdrv_co_writev = ssh_co_writev,
.bdrv_getlength = ssh_getlength,
.bdrv_co_truncate = ssh_co_truncate,
.bdrv_co_flush_to_disk = ssh_co_flush,
.bdrv_refresh_filename = ssh_refresh_filename,
.bdrv_dirname = ssh_bdrv_dirname,
.create_opts = &ssh_create_opts,
.strong_runtime_opts = ssh_strong_runtime_opts,
};
static void bdrv_ssh_init(void)
{
int r;
r = ssh_init();
if (r != 0) {
fprintf(stderr, "libssh initialization failed, %d\n", r);
exit(EXIT_FAILURE);
}
#if TRACE_LIBSSH != 0
ssh_set_log_level(TRACE_LIBSSH);
#endif
bdrv_register(&bdrv_ssh);
}
block_init(bdrv_ssh_init);
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