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0427b6257e
qemu-e2k/block/ssh.c
Max Reitz 2654267cc1 block: Add strong_runtime_opts to BlockDriver 
This new field can be set by block drivers to list the runtime options
they accept that may influence the contents of the respective BDS. As of
a follow-up patch, this list will be used by the common
bdrv_refresh_filename() implementation to decide which options to put
into BDS.full_open_options (and consequently whether a JSON filename has
to be created), thus freeing the drivers of having to implement that
logic themselves.

Additionally, this patch adds the field to all of the block drivers that
need it and sets it accordingly.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20190201192935.18394-22-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
2019-02-25 15:11:27 +01:00

1301 lines
36 KiB
C
Raw Blame History

/*
* 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 <libssh2.h>
#include <libssh2_sftp.h>
#include "block/block_int.h"
#include "block/qdict.h"
#include "qapi/error.h"
#include "qemu/error-report.h"
#include "qemu/option.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_LIBSSH2=<bitmask> enables tracing in libssh2 itself. Note
* that this requires that libssh2 was specially compiled with the
* `./configure --enable-debug' option, so most likely you will have
* to compile it yourself. The meaning of <bitmask> is described
* here: http://www.libssh2.org/libssh2_trace.html
*/
#define TRACE_LIBSSH2 0 /* or try: LIBSSH2_TRACE_SFTP */
typedef struct BDRVSSHState {
/* Coroutine. */
CoMutex lock;
/* SSH connection. */
int sock; /* socket */
LIBSSH2_SESSION *session; /* ssh session */
LIBSSH2_SFTP *sftp; /* sftp session */
LIBSSH2_SFTP_HANDLE *sftp_handle; /* sftp remote file handle */
/* See ssh_seek() function below. */
int64_t offset;
bool offset_op_read;
/* File attributes at open. We try to keep the .filesize field
* updated if it changes (eg by writing at the end of the file).
*/
LIBSSH2_SFTP_ATTRIBUTES attrs;
InetSocketAddress *inet;
/* Used to warn if 'flush' is not supported. */
bool unsafe_flush_warning;
} BDRVSSHState;
static void ssh_state_init(BDRVSSHState *s)
{
memset(s, 0, sizeof *s);
s->sock = -1;
s->offset = -1;
qemu_co_mutex_init(&s->lock);
}
static void ssh_state_free(BDRVSSHState *s)
{
if (s->sftp_handle) {
libssh2_sftp_close(s->sftp_handle);
}
if (s->sftp) {
libssh2_sftp_shutdown(s->sftp);
}
if (s->session) {
libssh2_session_disconnect(s->session,
"from qemu ssh client: "
"user closed the connection");
libssh2_session_free(s->session);
}
if (s->sock >= 0) {
close(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) {
char *ssh_err;
int ssh_err_code;
/* This is not an errno. See <libssh2.h>. */
ssh_err_code = libssh2_session_last_error(s->session,
&ssh_err, NULL, 0);
error_setg(errp, "%s: %s (libssh2 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) {
char *ssh_err;
int ssh_err_code;
unsigned long sftp_err_code;
/* This is not an errno. See <libssh2.h>. */
ssh_err_code = libssh2_session_last_error(s->session,
&ssh_err, NULL, 0);
/* See <libssh2_sftp.h>. */
sftp_err_code = libssh2_sftp_last_error((s)->sftp);
error_setg(errp,
"%s: %s (libssh2 error code: %d, sftp error code: %lu)",
msg, ssh_err, ssh_err_code, sftp_err_code);
} else {
error_setg(errp, "%s", msg);
}
g_free(msg);
}
static void GCC_FMT_ATTR(2, 3)
sftp_error_report(BDRVSSHState *s, const char *fs, ...)
{
va_list args;
va_start(args, fs);
error_vprintf(fs, args);
if ((s)->sftp) {
char *ssh_err;
int ssh_err_code;
unsigned long sftp_err_code;
/* This is not an errno. See <libssh2.h>. */
ssh_err_code = libssh2_session_last_error(s->session,
&ssh_err, NULL, 0);
/* See <libssh2_sftp.h>. */
sftp_err_code = libssh2_sftp_last_error((s)->sftp);
error_printf(": %s (libssh2 error code: %d, sftp error code: %lu)",
ssh_err, ssh_err_code, sftp_err_code);
}
va_end(args);
error_printf("\n");
}
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,
const char *host, int port, Error **errp)
{
const char *home;
char *knh_file = NULL;
LIBSSH2_KNOWNHOSTS *knh = NULL;
struct libssh2_knownhost *found;
int ret, r;
const char *hostkey;
size_t len;
int type;
hostkey = libssh2_session_hostkey(s->session, &len, &type);
if (!hostkey) {
ret = -EINVAL;
session_error_setg(errp, s, "failed to read remote host key");
goto out;
}
knh = libssh2_knownhost_init(s->session);
if (!knh) {
ret = -EINVAL;
session_error_setg(errp, s,
"failed to initialize known hosts support");
goto out;
}
home = getenv("HOME");
if (home) {
knh_file = g_strdup_printf("%s/.ssh/known_hosts", home);
} else {
knh_file = g_strdup_printf("/root/.ssh/known_hosts");
}
/* Read all known hosts from OpenSSH-style known_hosts file. */
libssh2_knownhost_readfile(knh, knh_file, LIBSSH2_KNOWNHOST_FILE_OPENSSH);
r = libssh2_knownhost_checkp(knh, host, port, hostkey, len,
LIBSSH2_KNOWNHOST_TYPE_PLAIN|
LIBSSH2_KNOWNHOST_KEYENC_RAW,
&found);
switch (r) {
case LIBSSH2_KNOWNHOST_CHECK_MATCH:
/* OK */
trace_ssh_check_host_key_knownhosts(found->key);
break;
case LIBSSH2_KNOWNHOST_CHECK_MISMATCH:
ret = -EINVAL;
session_error_setg(errp, s,
"host key does not match the one in known_hosts"
" (found key %s)", found->key);
goto out;
case LIBSSH2_KNOWNHOST_CHECK_NOTFOUND:
ret = -EINVAL;
session_error_setg(errp, s, "no host key was found in known_hosts");
goto out;
case LIBSSH2_KNOWNHOST_CHECK_FAILURE:
ret = -EINVAL;
session_error_setg(errp, s,
"failure matching the host key with known_hosts");
goto out;
default:
ret = -EINVAL;
session_error_setg(errp, s, "unknown error matching the host key"
" with known_hosts (%d)", r);
goto out;
}
/* known_hosts checking successful. */
ret = 0;
out:
if (knh != NULL) {
libssh2_knownhost_free(knh);
}
g_free(knh_file);
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,
int hash_type, size_t fingerprint_len, Error **errp)
{
const char *fingerprint;
fingerprint = libssh2_hostkey_hash(s->session, hash_type);
if (!fingerprint) {
session_error_setg(errp, s, "failed to read remote host key");
return -EINVAL;
}
if(compare_fingerprint((unsigned char *) fingerprint, fingerprint_len,
hash) != 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, const char *host, int port,
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,
LIBSSH2_HOSTKEY_HASH_MD5, 16, errp);
} else if (hkc->u.hash.type == SSH_HOST_KEY_CHECK_HASH_TYPE_SHA1) {
return check_host_key_hash(s, hkc->u.hash.hash,
LIBSSH2_HOSTKEY_HASH_SHA1, 20, errp);
}
g_assert_not_reached();
break;
case SSH_HOST_KEY_CHECK_MODE_KNOWN_HOSTS:
return check_host_key_knownhosts(s, host, port, errp);
default:
g_assert_not_reached();
}
return -EINVAL;
}
static int authenticate(BDRVSSHState *s, const char *user, Error **errp)
{
int r, ret;
const char *userauthlist;
LIBSSH2_AGENT *agent = NULL;
struct libssh2_agent_publickey *identity;
struct libssh2_agent_publickey *prev_identity = NULL;
userauthlist = libssh2_userauth_list(s->session, user, strlen(user));
if (strstr(userauthlist, "publickey") == NULL) {
ret = -EPERM;
error_setg(errp,
"remote server does not support \"publickey\" authentication");
goto out;
}
/* Connect to ssh-agent and try each identity in turn. */
agent = libssh2_agent_init(s->session);
if (!agent) {
ret = -EINVAL;
session_error_setg(errp, s, "failed to initialize ssh-agent support");
goto out;
}
if (libssh2_agent_connect(agent)) {
ret = -ECONNREFUSED;
session_error_setg(errp, s, "failed to connect to ssh-agent");
goto out;
}
if (libssh2_agent_list_identities(agent)) {
ret = -EINVAL;
session_error_setg(errp, s,
"failed requesting identities from ssh-agent");
goto out;
}
for(;;) {
r = libssh2_agent_get_identity(agent, &identity, prev_identity);
if (r == 1) { /* end of list */
break;
}
if (r < 0) {
ret = -EINVAL;
session_error_setg(errp, s,
"failed to obtain identity from ssh-agent");
goto out;
}
r = libssh2_agent_userauth(agent, user, identity);
if (r == 0) {
/* Authenticated! */
ret = 0;
goto out;
}
/* Failed to authenticate with this identity, try the next one. */
prev_identity = identity;
}
ret = -EPERM;
error_setg(errp, "failed to authenticate using publickey authentication "
"and the identities held by your ssh-agent");
out:
if (agent != NULL) {
/* Note: libssh2 implementation implicitly calls
* libssh2_agent_disconnect if necessary.
*/
libssh2_agent_free(agent);
}
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;
const char *user;
long port = 0;
if (opts->has_user) {
user = opts->user;
} else {
user = g_get_user_name();
if (!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_strtol(s->inet->port, NULL, 10, &port) < 0) {
error_setg(errp, "Use only numeric port value");
ret = -EINVAL;
goto err;
}
/* Open the socket and connect. */
s->sock = inet_connect_saddr(s->inet, errp);
if (s->sock < 0) {
ret = -EIO;
goto err;
}
/* Create SSH session. */
s->session = libssh2_session_init();
if (!s->session) {
ret = -EINVAL;
session_error_setg(errp, s, "failed to initialize libssh2 session");
goto err;
}
#if TRACE_LIBSSH2 != 0
libssh2_trace(s->session, TRACE_LIBSSH2);
#endif
r = libssh2_session_handshake(s->session, s->sock);
if (r != 0) {
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, s->inet->host, port, opts->host_key_check, errp);
if (ret < 0) {
goto err;
}
/* Authenticate. */
ret = authenticate(s, user, errp);
if (ret < 0) {
goto err;
}
/* Start SFTP. */
s->sftp = libssh2_sftp_init(s->session);
if (!s->sftp) {
session_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 = libssh2_sftp_open(s->sftp, opts->path, ssh_flags,
creat_mode);
if (!s->sftp_handle) {
session_error_setg(errp, s, "failed to open remote file '%s'",
opts->path);
ret = -EINVAL;
goto err;
}
r = libssh2_sftp_fstat(s->sftp_handle, &s->attrs);
if (r < 0) {
sftp_error_setg(errp, s, "failed to read file attributes");
return -EINVAL;
}
return 0;
err:
if (s->sftp_handle) {
libssh2_sftp_close(s->sftp_handle);
}
s->sftp_handle = NULL;
if (s->sftp) {
libssh2_sftp_shutdown(s->sftp);
}
s->sftp = NULL;
if (s->session) {
libssh2_session_disconnect(s->session,
"from qemu ssh client: "
"error opening connection");
libssh2_session_free(s->session);
}
s->session = NULL;
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 = LIBSSH2_FXF_READ;
if (bdrv_flags & BDRV_O_RDWR) {
ssh_flags |= LIBSSH2_FXF_WRITE;
}
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. */
libssh2_session_set_blocking(s->session, 0);
qapi_free_BlockdevOptionsSsh(opts);
return 0;
err:
if (s->sock >= 0) {
close(s->sock);
}
s->sock = -1;
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 = libssh2_session_get_blocking(s->session);
/* offset must be strictly greater than the current size so we do
* not overwrite anything */
assert(offset > 0 && offset > s->attrs.filesize);
libssh2_session_set_blocking(s->session, 1);
libssh2_sftp_seek64(s->sftp_handle, offset - 1);
ret = libssh2_sftp_write(s->sftp_handle, c, 1);
libssh2_session_set_blocking(s->session, was_blocking);
if (ret < 0) {
sftp_error_setg(errp, s, "Failed to grow file");
return -EIO;
}
s->attrs.filesize = 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,
LIBSSH2_FXF_READ|LIBSSH2_FXF_WRITE|
LIBSSH2_FXF_CREAT|LIBSSH2_FXF_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(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.flags & LIBSSH2_SFTP_ATTR_PERMISSIONS) {
if (s->attrs.permissions & LIBSSH2_SFTP_S_IFREG) {
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 = libssh2_session_block_directions(s->session);
if (r & LIBSSH2_SESSION_BLOCK_INBOUND) {
rd_handler = restart_coroutine;
}
if (r & LIBSSH2_SESSION_BLOCK_OUTBOUND) {
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);
}
/* SFTP has a function `libssh2_sftp_seek64' which seeks to a position
* in the remote file. Notice that it just updates a field in the
* sftp_handle structure, so there is no network traffic and it cannot
* fail.
*
* However, `libssh2_sftp_seek64' does have a catastrophic effect on
* performance since it causes the handle to throw away all in-flight
* reads and buffered readahead data. Therefore this function tries
* to be intelligent about when to call the underlying libssh2 function.
*/
#define SSH_SEEK_WRITE 0
#define SSH_SEEK_READ 1
#define SSH_SEEK_FORCE 2
static void ssh_seek(BDRVSSHState *s, int64_t offset, int flags)
{
bool op_read = (flags & SSH_SEEK_READ) != 0;
bool force = (flags & SSH_SEEK_FORCE) != 0;
if (force || op_read != s->offset_op_read || offset != s->offset) {
trace_ssh_seek(offset);
libssh2_sftp_seek64(s->sftp_handle, offset);
s->offset = offset;
s->offset_op_read = op_read;
}
}
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);
ssh_seek(s, offset, SSH_SEEK_READ);
/* 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;
/* libssh2 has a hard-coded limit of 2000 bytes per request,
* although it will also do readahead behind our backs. Therefore
* we may have to do repeated reads here until we have read 'size'
* bytes.
*/
for (got = 0; got < size; ) {
again:
trace_ssh_read_buf(buf, end_of_vec - buf);
r = libssh2_sftp_read(s->sftp_handle, buf, end_of_vec - buf);
trace_ssh_read_return(r);
if (r == LIBSSH2_ERROR_EAGAIN || r == LIBSSH2_ERROR_TIMEOUT) {
co_yield(s, bs);
goto again;
}
if (r < 0) {
sftp_error_report(s, "read failed");
s->offset = -1;
return -EIO;
}
if (r == 0) {
/* EOF: Short read so pad the buffer with zeroes and return it. */
qemu_iovec_memset(qiov, got, 0, size - got);
return 0;
}
got += r;
buf += r;
s->offset += 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);
ssh_seek(s, offset, SSH_SEEK_WRITE);
/* 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; ) {
again:
trace_ssh_write_buf(buf, end_of_vec - buf);
r = libssh2_sftp_write(s->sftp_handle, buf, end_of_vec - buf);
trace_ssh_write_return(r);
if (r == LIBSSH2_ERROR_EAGAIN || r == LIBSSH2_ERROR_TIMEOUT) {
co_yield(s, bs);
goto again;
}
if (r < 0) {
sftp_error_report(s, "write failed");
s->offset = -1;
return -EIO;
}
/* The libssh2 API is very unclear about this. A comment in
* the code says "nothing was acked, and no EAGAIN was
* received!" which apparently means that no data got sent
* out, and the underlying channel didn't return any EAGAIN
* indication. I think this is a bug in either libssh2 or
* OpenSSH (server-side). In any case, forcing a seek (to
* discard libssh2 internal buffers), and then trying again
* works for me.
*/
if (r == 0) {
ssh_seek(s, offset + written, SSH_SEEK_WRITE|SSH_SEEK_FORCE);
co_yield(s, bs);
goto again;
}
written += r;
buf += r;
s->offset += 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.filesize)
s->attrs.filesize = 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 HAS_LIBSSH2_SFTP_FSYNC
static coroutine_fn int ssh_flush(BDRVSSHState *s, BlockDriverState *bs)
{
int r;
trace_ssh_flush();
again:
r = libssh2_sftp_fsync(s->sftp_handle);
if (r == LIBSSH2_ERROR_EAGAIN || r == LIBSSH2_ERROR_TIMEOUT) {
co_yield(s, bs);
goto again;
}
if (r == LIBSSH2_ERROR_SFTP_PROTOCOL &&
libssh2_sftp_last_error(s->sftp) == LIBSSH2_FX_OP_UNSUPPORTED) {
unsafe_flush_warning(s, "OpenSSH >= 6.3");
return 0;
}
if (r < 0) {
sftp_error_report(s, "fsync failed");
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 /* !HAS_LIBSSH2_SFTP_FSYNC */
static coroutine_fn int ssh_co_flush(BlockDriverState *bs)
{
BDRVSSHState *s = bs->opaque;
unsafe_flush_warning(s, "libssh2 >= 1.4.4");
return 0;
}
#endif /* !HAS_LIBSSH2_SFTP_FSYNC */
static int64_t ssh_getlength(BlockDriverState *bs)
{
BDRVSSHState *s = bs->opaque;
int64_t length;
/* Note we cannot make a libssh2 call here. */
length = (int64_t) s->attrs.filesize;
trace_ssh_getlength(length);
return length;
}
static int coroutine_fn ssh_co_truncate(BlockDriverState *bs, int64_t offset,
PreallocMode prealloc, 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.filesize) {
error_setg(errp, "ssh driver does not support shrinking files");
return -ENOTSUP;
}
if (offset == s->attrs.filesize) {
return 0;
}
return ssh_grow_file(s, offset, errp);
}
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_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,
.create_opts = &ssh_create_opts,
.strong_runtime_opts = ssh_strong_runtime_opts,
};
static void bdrv_ssh_init(void)
{
int r;
r = libssh2_init(0);
if (r != 0) {
fprintf(stderr, "libssh2 initialization failed, %d\n", r);
exit(EXIT_FAILURE);
}
bdrv_register(&bdrv_ssh);
}
block_init(bdrv_ssh_init);
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