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block: Add support for Secure Shell (ssh) block device.
qemu-system-x86_64 -drive file=ssh://hostname/some/image QEMU will ssh into 'hostname' and open '/some/image' which is made available as a standard block device. You can specify a username (ssh://user@host/...) and/or a port number (ssh://host:port/...). You can also use an alternate syntax using properties (file.user, file.host, file.port, file.path). Current limitations: - Authentication must be done without passwords or passphrases, using ssh-agent. Other authentication methods are not supported. - Uses a single connection, instead of concurrent AIO with multiple SSH connections. This is implemented using libssh2 on the client side. The server just requires a regular ssh daemon with sftp-server support. Most ssh daemons on Unix/Linux systems will work out of the box. Signed-off-by: Richard W.M. Jones <rjones@redhat.com> Cc: Stefan Hajnoczi <stefanha@gmail.com> Cc: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Richard W.M. Jones
Stefan Hajnoczi
parent
aad64f3193
commit
0a12ec87a5
@ -13,6 +13,7 @@ block-obj-$(CONFIG_LIBISCSI) += iscsi.o
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block-obj-$(CONFIG_CURL) += curl.o
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block-obj-$(CONFIG_RBD) += rbd.o
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block-obj-$(CONFIG_GLUSTERFS) += gluster.o
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block-obj-$(CONFIG_LIBSSH2) += ssh.o
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endif
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common-obj-y += stream.o
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995
block/ssh.c
Normal file
995
block/ssh.c
Normal file
@ -0,0 +1,995 @@
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/*
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* Secure Shell (ssh) backend for QEMU.
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*
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* Copyright (C) 2013 Red Hat Inc., Richard W.M. Jones <rjones@redhat.com>
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <stdarg.h>
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#include <libssh2.h>
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#include <libssh2_sftp.h>
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#include "block/block_int.h"
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#include "qemu/sockets.h"
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#include "qemu/uri.h"
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#include "qapi/qmp/qint.h"
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/* DEBUG_SSH=1 enables the DPRINTF (debugging printf) statements in
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* this block driver code.
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*
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* TRACE_LIBSSH2=<bitmask> enables tracing in libssh2 itself. Note
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* that this requires that libssh2 was specially compiled with the
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* `./configure --enable-debug' option, so most likely you will have
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* to compile it yourself. The meaning of <bitmask> is described
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* here: http://www.libssh2.org/libssh2_trace.html
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*/
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#define DEBUG_SSH 0
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#define TRACE_LIBSSH2 0 /* or try: LIBSSH2_TRACE_SFTP */
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#define DPRINTF(fmt, ...) \
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do { \
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if (DEBUG_SSH) { \
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fprintf(stderr, "ssh: %-15s " fmt "\n", \
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__func__, ##__VA_ARGS__); \
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} \
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} while (0)
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typedef struct BDRVSSHState {
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/* Coroutine. */
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CoMutex lock;
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/* SSH connection. */
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int sock; /* socket */
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LIBSSH2_SESSION *session; /* ssh session */
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LIBSSH2_SFTP *sftp; /* sftp session */
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LIBSSH2_SFTP_HANDLE *sftp_handle; /* sftp remote file handle */
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/* See ssh_seek() function below. */
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int64_t offset;
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bool offset_op_read;
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/* File attributes at open. We try to keep the .filesize field
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* updated if it changes (eg by writing at the end of the file).
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*/
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LIBSSH2_SFTP_ATTRIBUTES attrs;
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} BDRVSSHState;
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static void ssh_state_init(BDRVSSHState *s)
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{
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memset(s, 0, sizeof *s);
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s->sock = -1;
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s->offset = -1;
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qemu_co_mutex_init(&s->lock);
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}
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static void ssh_state_free(BDRVSSHState *s)
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{
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if (s->sftp_handle) {
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libssh2_sftp_close(s->sftp_handle);
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}
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if (s->sftp) {
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libssh2_sftp_shutdown(s->sftp);
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}
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if (s->session) {
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libssh2_session_disconnect(s->session,
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"from qemu ssh client: "
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"user closed the connection");
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libssh2_session_free(s->session);
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}
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if (s->sock >= 0) {
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close(s->sock);
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}
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}
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/* Wrappers around error_report which make sure to dump as much
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* information from libssh2 as possible.
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*/
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static void
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session_error_report(BDRVSSHState *s, const char *fs, ...)
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{
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va_list args;
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va_start(args, fs);
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error_vprintf(fs, args);
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if ((s)->session) {
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char *ssh_err;
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int ssh_err_code;
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libssh2_session_last_error((s)->session, &ssh_err, NULL, 0);
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/* This is not an errno. See <libssh2.h>. */
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ssh_err_code = libssh2_session_last_errno((s)->session);
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error_printf(": %s (libssh2 error code: %d)", ssh_err, ssh_err_code);
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}
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va_end(args);
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error_printf("\n");
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}
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static void
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sftp_error_report(BDRVSSHState *s, const char *fs, ...)
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{
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va_list args;
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va_start(args, fs);
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error_vprintf(fs, args);
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if ((s)->sftp) {
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char *ssh_err;
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int ssh_err_code;
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unsigned long sftp_err_code;
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libssh2_session_last_error((s)->session, &ssh_err, NULL, 0);
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/* This is not an errno. See <libssh2.h>. */
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ssh_err_code = libssh2_session_last_errno((s)->session);
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/* See <libssh2_sftp.h>. */
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sftp_err_code = libssh2_sftp_last_error((s)->sftp);
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error_printf(": %s (libssh2 error code: %d, sftp error code: %lu)",
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ssh_err, ssh_err_code, sftp_err_code);
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}
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va_end(args);
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error_printf("\n");
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}
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static int parse_uri(const char *filename, QDict *options, Error **errp)
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{
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URI *uri = NULL;
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QueryParams *qp = NULL;
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int i;
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uri = uri_parse(filename);
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if (!uri) {
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return -EINVAL;
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}
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if (strcmp(uri->scheme, "ssh") != 0) {
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error_setg(errp, "URI scheme must be 'ssh'");
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goto err;
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}
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if (!uri->server || strcmp(uri->server, "") == 0) {
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error_setg(errp, "missing hostname in URI");
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goto err;
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}
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if (!uri->path || strcmp(uri->path, "") == 0) {
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error_setg(errp, "missing remote path in URI");
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goto err;
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}
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qp = query_params_parse(uri->query);
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if (!qp) {
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error_setg(errp, "could not parse query parameters");
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goto err;
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}
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if(uri->user && strcmp(uri->user, "") != 0) {
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qdict_put(options, "user", qstring_from_str(uri->user));
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}
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qdict_put(options, "host", qstring_from_str(uri->server));
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if (uri->port) {
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qdict_put(options, "port", qint_from_int(uri->port));
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}
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qdict_put(options, "path", qstring_from_str(uri->path));
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/* Pick out any query parameters that we understand, and ignore
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* the rest.
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*/
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for (i = 0; i < qp->n; ++i) {
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if (strcmp(qp->p[i].name, "host_key_check") == 0) {
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qdict_put(options, "host_key_check",
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qstring_from_str(qp->p[i].value));
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}
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}
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query_params_free(qp);
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uri_free(uri);
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return 0;
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err:
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if (qp) {
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query_params_free(qp);
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}
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if (uri) {
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uri_free(uri);
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}
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return -EINVAL;
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}
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static void ssh_parse_filename(const char *filename, QDict *options,
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Error **errp)
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{
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if (qdict_haskey(options, "user") ||
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qdict_haskey(options, "host") ||
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qdict_haskey(options, "port") ||
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qdict_haskey(options, "path") ||
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qdict_haskey(options, "host_key_check")) {
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error_setg(errp, "user, host, port, path, host_key_check cannot be used at the same time as a file option");
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return;
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}
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parse_uri(filename, options, errp);
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}
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static int check_host_key_knownhosts(BDRVSSHState *s,
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const char *host, int port)
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{
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const char *home;
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char *knh_file = NULL;
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LIBSSH2_KNOWNHOSTS *knh = NULL;
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struct libssh2_knownhost *found;
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int ret, r;
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const char *hostkey;
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size_t len;
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int type;
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hostkey = libssh2_session_hostkey(s->session, &len, &type);
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if (!hostkey) {
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ret = -EINVAL;
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session_error_report(s, "failed to read remote host key");
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goto out;
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}
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knh = libssh2_knownhost_init(s->session);
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if (!knh) {
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ret = -EINVAL;
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session_error_report(s, "failed to initialize known hosts support");
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goto out;
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}
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home = getenv("HOME");
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if (home) {
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knh_file = g_strdup_printf("%s/.ssh/known_hosts", home);
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} else {
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knh_file = g_strdup_printf("/root/.ssh/known_hosts");
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}
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/* Read all known hosts from OpenSSH-style known_hosts file. */
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libssh2_knownhost_readfile(knh, knh_file, LIBSSH2_KNOWNHOST_FILE_OPENSSH);
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r = libssh2_knownhost_checkp(knh, host, port, hostkey, len,
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LIBSSH2_KNOWNHOST_TYPE_PLAIN|
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LIBSSH2_KNOWNHOST_KEYENC_RAW,
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&found);
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switch (r) {
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case LIBSSH2_KNOWNHOST_CHECK_MATCH:
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/* OK */
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DPRINTF("host key OK: %s", found->key);
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break;
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case LIBSSH2_KNOWNHOST_CHECK_MISMATCH:
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ret = -EINVAL;
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session_error_report(s, "host key does not match the one in known_hosts (found key %s)",
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found->key);
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goto out;
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case LIBSSH2_KNOWNHOST_CHECK_NOTFOUND:
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ret = -EINVAL;
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session_error_report(s, "no host key was found in known_hosts");
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goto out;
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case LIBSSH2_KNOWNHOST_CHECK_FAILURE:
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ret = -EINVAL;
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session_error_report(s, "failure matching the host key with known_hosts");
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goto out;
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default:
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ret = -EINVAL;
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session_error_report(s, "unknown error matching the host key with known_hosts (%d)",
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r);
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goto out;
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}
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/* known_hosts checking successful. */
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ret = 0;
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out:
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if (knh != NULL) {
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libssh2_knownhost_free(knh);
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}
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g_free(knh_file);
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return ret;
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}
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static unsigned hex2decimal(char ch)
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{
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if (ch >= '0' && ch <= '9') {
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return (ch - '0');
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} else if (ch >= 'a' && ch <= 'f') {
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return 10 + (ch - 'a');
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} else if (ch >= 'A' && ch <= 'F') {
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return 10 + (ch - 'A');
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}
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return -1;
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}
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/* Compare the binary fingerprint (hash of host key) with the
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* host_key_check parameter.
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*/
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static int compare_fingerprint(const unsigned char *fingerprint, size_t len,
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const char *host_key_check)
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{
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unsigned c;
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while (len > 0) {
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while (*host_key_check == ':')
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host_key_check++;
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if (!qemu_isxdigit(host_key_check[0]) ||
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!qemu_isxdigit(host_key_check[1]))
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return 1;
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c = hex2decimal(host_key_check[0]) * 16 +
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hex2decimal(host_key_check[1]);
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if (c - *fingerprint != 0)
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return c - *fingerprint;
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fingerprint++;
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len--;
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host_key_check += 2;
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}
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return *host_key_check - '\0';
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}
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static int
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check_host_key_hash(BDRVSSHState *s, const char *hash,
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int hash_type, size_t fingerprint_len)
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{
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const char *fingerprint;
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fingerprint = libssh2_hostkey_hash(s->session, hash_type);
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if (!fingerprint) {
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session_error_report(s, "failed to read remote host key");
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return -EINVAL;
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}
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|
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if(compare_fingerprint((unsigned char *) fingerprint, fingerprint_len,
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hash) != 0) {
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error_report("remote host key does not match host_key_check '%s'",
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hash);
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return -EPERM;
|
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}
|
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|
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return 0;
|
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}
|
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|
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static int check_host_key(BDRVSSHState *s, const char *host, int port,
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const char *host_key_check)
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{
|
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/* host_key_check=no */
|
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if (strcmp(host_key_check, "no") == 0) {
|
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return 0;
|
||||
}
|
||||
|
||||
/* host_key_check=md5:xx:yy:zz:... */
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if (strlen(host_key_check) >= 4 &&
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strncmp(host_key_check, "md5:", 4) == 0) {
|
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return check_host_key_hash(s, &host_key_check[4],
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LIBSSH2_HOSTKEY_HASH_MD5, 16);
|
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}
|
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|
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/* host_key_check=sha1:xx:yy:zz:... */
|
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if (strlen(host_key_check) >= 5 &&
|
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strncmp(host_key_check, "sha1:", 5) == 0) {
|
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return check_host_key_hash(s, &host_key_check[5],
|
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LIBSSH2_HOSTKEY_HASH_SHA1, 20);
|
||||
}
|
||||
|
||||
/* host_key_check=yes */
|
||||
if (strcmp(host_key_check, "yes") == 0) {
|
||||
return check_host_key_knownhosts(s, host, port);
|
||||
}
|
||||
|
||||
error_report("unknown host_key_check setting (%s)", host_key_check);
|
||||
return -EINVAL;
|
||||
}
|
||||
|
||||
static int authenticate(BDRVSSHState *s, const char *user)
|
||||
{
|
||||
int r, ret;
|
||||
const char *userauthlist;
|
||||
LIBSSH2_AGENT *agent = NULL;
|
||||
struct libssh2_agent_publickey *identity;
|
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struct libssh2_agent_publickey *prev_identity = NULL;
|
||||
|
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userauthlist = libssh2_userauth_list(s->session, user, strlen(user));
|
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if (strstr(userauthlist, "publickey") == NULL) {
|
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ret = -EPERM;
|
||||
error_report("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_report(s, "failed to initialize ssh-agent support");
|
||||
goto out;
|
||||
}
|
||||
if (libssh2_agent_connect(agent)) {
|
||||
ret = -ECONNREFUSED;
|
||||
session_error_report(s, "failed to connect to ssh-agent");
|
||||
goto out;
|
||||
}
|
||||
if (libssh2_agent_list_identities(agent)) {
|
||||
ret = -EINVAL;
|
||||
session_error_report(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_report(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_report("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 int connect_to_ssh(BDRVSSHState *s, QDict *options,
|
||||
int ssh_flags, int creat_mode)
|
||||
{
|
||||
int r, ret;
|
||||
Error *err = NULL;
|
||||
const char *host, *user, *path, *host_key_check;
|
||||
int port;
|
||||
char *hostport = NULL;
|
||||
|
||||
host = qdict_get_str(options, "host");
|
||||
|
||||
if (qdict_haskey(options, "port")) {
|
||||
port = qdict_get_int(options, "port");
|
||||
} else {
|
||||
port = 22;
|
||||
}
|
||||
|
||||
path = qdict_get_str(options, "path");
|
||||
|
||||
if (qdict_haskey(options, "user")) {
|
||||
user = qdict_get_str(options, "user");
|
||||
} else {
|
||||
user = g_get_user_name();
|
||||
if (!user) {
|
||||
ret = -errno;
|
||||
goto err;
|
||||
}
|
||||
}
|
||||
|
||||
if (qdict_haskey(options, "host_key_check")) {
|
||||
host_key_check = qdict_get_str(options, "host_key_check");
|
||||
} else {
|
||||
host_key_check = "yes";
|
||||
}
|
||||
|
||||
/* Open the socket and connect. */
|
||||
hostport = g_strdup_printf("%s:%d", host, port);
|
||||
s->sock = inet_connect(hostport, &err);
|
||||
if (err != NULL) {
|
||||
ret = -errno;
|
||||
qerror_report_err(err);
|
||||
error_free(err);
|
||||
goto err;
|
||||
}
|
||||
|
||||
/* Create SSH session. */
|
||||
s->session = libssh2_session_init();
|
||||
if (!s->session) {
|
||||
ret = -EINVAL;
|
||||
session_error_report(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_report(s, "failed to establish SSH session");
|
||||
goto err;
|
||||
}
|
||||
|
||||
/* Check the remote host's key against known_hosts. */
|
||||
ret = check_host_key(s, host, port, host_key_check);
|
||||
if (ret < 0) {
|
||||
goto err;
|
||||
}
|
||||
|
||||
/* Authenticate. */
|
||||
ret = authenticate(s, user);
|
||||
if (ret < 0) {
|
||||
goto err;
|
||||
}
|
||||
|
||||
/* Start SFTP. */
|
||||
s->sftp = libssh2_sftp_init(s->session);
|
||||
if (!s->sftp) {
|
||||
session_error_report(s, "failed to initialize sftp handle");
|
||||
ret = -EINVAL;
|
||||
goto err;
|
||||
}
|
||||
|
||||
/* Open the remote file. */
|
||||
DPRINTF("opening file %s flags=0x%x creat_mode=0%o",
|
||||
path, ssh_flags, creat_mode);
|
||||
s->sftp_handle = libssh2_sftp_open(s->sftp, path, ssh_flags, creat_mode);
|
||||
if (!s->sftp_handle) {
|
||||
session_error_report(s, "failed to open remote file '%s'", path);
|
||||
ret = -EINVAL;
|
||||
goto err;
|
||||
}
|
||||
|
||||
r = libssh2_sftp_fstat(s->sftp_handle, &s->attrs);
|
||||
if (r < 0) {
|
||||
sftp_error_report(s, "failed to read file attributes");
|
||||
return -EINVAL;
|
||||
}
|
||||
|
||||
/* Delete the options we've used; any not deleted will cause the
|
||||
* block layer to give an error about unused options.
|
||||
*/
|
||||
qdict_del(options, "host");
|
||||
qdict_del(options, "port");
|
||||
qdict_del(options, "user");
|
||||
qdict_del(options, "path");
|
||||
qdict_del(options, "host_key_check");
|
||||
|
||||
g_free(hostport);
|
||||
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;
|
||||
g_free(hostport);
|
||||
|
||||
return ret;
|
||||
}
|
||||
|
||||
static int ssh_file_open(BlockDriverState *bs, const char *filename,
|
||||
QDict *options, int bdrv_flags)
|
||||
{
|
||||
BDRVSSHState *s = bs->opaque;
|
||||
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;
|
||||
}
|
||||
|
||||
/* Start up SSH. */
|
||||
ret = connect_to_ssh(s, options, ssh_flags, 0);
|
||||
if (ret < 0) {
|
||||
goto err;
|
||||
}
|
||||
|
||||
/* Go non-blocking. */
|
||||
libssh2_session_set_blocking(s->session, 0);
|
||||
|
||||
return 0;
|
||||
|
||||
err:
|
||||
if (s->sock >= 0) {
|
||||
close(s->sock);
|
||||
}
|
||||
s->sock = -1;
|
||||
|
||||
return ret;
|
||||
}
|
||||
|
||||
static QEMUOptionParameter ssh_create_options[] = {
|
||||
{
|
||||
.name = BLOCK_OPT_SIZE,
|
||||
.type = OPT_SIZE,
|
||||
.help = "Virtual disk size"
|
||||
},
|
||||
{ NULL }
|
||||
};
|
||||
|
||||
static int ssh_create(const char *filename, QEMUOptionParameter *options)
|
||||
{
|
||||
int r, ret;
|
||||
Error *local_err = NULL;
|
||||
int64_t total_size = 0;
|
||||
QDict *uri_options = NULL;
|
||||
BDRVSSHState s;
|
||||
ssize_t r2;
|
||||
char c[1] = { '\0' };
|
||||
|
||||
ssh_state_init(&s);
|
||||
|
||||
/* Get desired file size. */
|
||||
while (options && options->name) {
|
||||
if (!strcmp(options->name, BLOCK_OPT_SIZE)) {
|
||||
total_size = options->value.n;
|
||||
}
|
||||
options++;
|
||||
}
|
||||
DPRINTF("total_size=%" PRIi64, total_size);
|
||||
|
||||
uri_options = qdict_new();
|
||||
r = parse_uri(filename, uri_options, &local_err);
|
||||
if (r < 0) {
|
||||
qerror_report_err(local_err);
|
||||
error_free(local_err);
|
||||
ret = r;
|
||||
goto out;
|
||||
}
|
||||
|
||||
r = connect_to_ssh(&s, uri_options,
|
||||
LIBSSH2_FXF_READ|LIBSSH2_FXF_WRITE|
|
||||
LIBSSH2_FXF_CREAT|LIBSSH2_FXF_TRUNC, 0644);
|
||||
if (r < 0) {
|
||||
ret = r;
|
||||
goto out;
|
||||
}
|
||||
|
||||
if (total_size > 0) {
|
||||
libssh2_sftp_seek64(s.sftp_handle, total_size-1);
|
||||
r2 = libssh2_sftp_write(s.sftp_handle, c, 1);
|
||||
if (r2 < 0) {
|
||||
sftp_error_report(&s, "truncate failed");
|
||||
ret = -EINVAL;
|
||||
goto out;
|
||||
}
|
||||
s.attrs.filesize = total_size;
|
||||
}
|
||||
|
||||
ret = 0;
|
||||
|
||||
out:
|
||||
ssh_state_free(&s);
|
||||
if (uri_options != NULL) {
|
||||
QDECREF(uri_options);
|
||||
}
|
||||
return ret;
|
||||
}
|
||||
|
||||
static void ssh_close(BlockDriverState *bs)
|
||||
{
|
||||
BDRVSSHState *s = bs->opaque;
|
||||
|
||||
ssh_state_free(s);
|
||||
}
|
||||
|
||||
static void restart_coroutine(void *opaque)
|
||||
{
|
||||
Coroutine *co = opaque;
|
||||
|
||||
DPRINTF("co=%p", co);
|
||||
|
||||
qemu_coroutine_enter(co, NULL);
|
||||
}
|
||||
|
||||
/* Always true because when we have called set_fd_handler there is
|
||||
* always a request being processed.
|
||||
*/
|
||||
static int return_true(void *opaque)
|
||||
{
|
||||
return 1;
|
||||
}
|
||||
|
||||
static coroutine_fn void set_fd_handler(BDRVSSHState *s)
|
||||
{
|
||||
int r;
|
||||
IOHandler *rd_handler = NULL, *wr_handler = NULL;
|
||||
Coroutine *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;
|
||||
}
|
||||
|
||||
DPRINTF("s->sock=%d rd_handler=%p wr_handler=%p", s->sock,
|
||||
rd_handler, wr_handler);
|
||||
|
||||
qemu_aio_set_fd_handler(s->sock, rd_handler, wr_handler, return_true, co);
|
||||
}
|
||||
|
||||
static coroutine_fn void clear_fd_handler(BDRVSSHState *s)
|
||||
{
|
||||
DPRINTF("s->sock=%d", s->sock);
|
||||
qemu_aio_set_fd_handler(s->sock, NULL, NULL, NULL, NULL);
|
||||
}
|
||||
|
||||
/* 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)
|
||||
{
|
||||
set_fd_handler(s);
|
||||
qemu_coroutine_yield();
|
||||
clear_fd_handler(s);
|
||||
}
|
||||
|
||||
/* 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) {
|
||||
DPRINTF("seeking to offset=%" PRIi64, 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,
|
||||
int64_t offset, size_t size,
|
||||
QEMUIOVector *qiov)
|
||||
{
|
||||
ssize_t r;
|
||||
size_t got;
|
||||
char *buf, *end_of_vec;
|
||||
struct iovec *i;
|
||||
|
||||
DPRINTF("offset=%" PRIi64 " size=%zu", 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:
|
||||
DPRINTF("sftp_read buf=%p size=%zu", buf, end_of_vec - buf);
|
||||
r = libssh2_sftp_read(s->sftp_handle, buf, end_of_vec - buf);
|
||||
DPRINTF("sftp_read returned %zd", r);
|
||||
|
||||
if (r == LIBSSH2_ERROR_EAGAIN || r == LIBSSH2_ERROR_TIMEOUT) {
|
||||
co_yield(s);
|
||||
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, 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,
|
||||
int64_t offset, size_t size,
|
||||
QEMUIOVector *qiov)
|
||||
{
|
||||
ssize_t r;
|
||||
size_t written;
|
||||
char *buf, *end_of_vec;
|
||||
struct iovec *i;
|
||||
|
||||
DPRINTF("offset=%" PRIi64 " size=%zu", 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:
|
||||
DPRINTF("sftp_write buf=%p size=%zu", buf, end_of_vec - buf);
|
||||
r = libssh2_sftp_write(s->sftp_handle, buf, end_of_vec - buf);
|
||||
DPRINTF("sftp_write returned %zd", r);
|
||||
|
||||
if (r == LIBSSH2_ERROR_EAGAIN || r == LIBSSH2_ERROR_TIMEOUT) {
|
||||
co_yield(s);
|
||||
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);
|
||||
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)
|
||||
{
|
||||
BDRVSSHState *s = bs->opaque;
|
||||
int ret;
|
||||
|
||||
qemu_co_mutex_lock(&s->lock);
|
||||
ret = ssh_write(s, sector_num * BDRV_SECTOR_SIZE,
|
||||
nb_sectors * BDRV_SECTOR_SIZE, qiov);
|
||||
qemu_co_mutex_unlock(&s->lock);
|
||||
|
||||
return ret;
|
||||
}
|
||||
|
||||
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;
|
||||
DPRINTF("length=%" PRIi64, length);
|
||||
|
||||
return length;
|
||||
}
|
||||
|
||||
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_create = ssh_create,
|
||||
.bdrv_close = ssh_close,
|
||||
.bdrv_co_readv = ssh_co_readv,
|
||||
.bdrv_co_writev = ssh_co_writev,
|
||||
.bdrv_getlength = ssh_getlength,
|
||||
.create_options = ssh_create_options,
|
||||
};
|
||||
|
||||
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);
|
||||
48
configure
vendored
48
configure
vendored
@ -239,6 +239,7 @@ virtio_blk_data_plane=""
|
||||
gtk=""
|
||||
gtkabi="2.0"
|
||||
tpm="no"
|
||||
libssh2=""
|
||||
|
||||
# parse CC options first
|
||||
for opt do
|
||||
@ -922,6 +923,10 @@ for opt do
|
||||
;;
|
||||
--enable-tpm) tpm="yes"
|
||||
;;
|
||||
--disable-libssh2) libssh2="no"
|
||||
;;
|
||||
--enable-libssh2) libssh2="yes"
|
||||
;;
|
||||
*) echo "ERROR: unknown option $opt"; show_help="yes"
|
||||
;;
|
||||
esac
|
||||
@ -1182,6 +1187,8 @@ echo " --disable-glusterfs disable GlusterFS backend"
|
||||
echo " --enable-gcov enable test coverage analysis with gcov"
|
||||
echo " --gcov=GCOV use specified gcov [$gcov_tool]"
|
||||
echo " --enable-tpm enable TPM support"
|
||||
echo " --disable-libssh2 disable ssh block device support"
|
||||
echo " --enable-libssh2 enable ssh block device support"
|
||||
echo ""
|
||||
echo "NOTE: The object files are built at the place where configure is launched"
|
||||
exit 1
|
||||
@ -2313,6 +2320,42 @@ EOF
|
||||
fi
|
||||
fi
|
||||
|
||||
##########################################
|
||||
# libssh2 probe
|
||||
if test "$libssh2" != "no" ; then
|
||||
cat > $TMPC <<EOF
|
||||
#include <stdio.h>
|
||||
#include <libssh2.h>
|
||||
#include <libssh2_sftp.h>
|
||||
int main(void) {
|
||||
LIBSSH2_SESSION *session;
|
||||
session = libssh2_session_init ();
|
||||
(void) libssh2_sftp_init (session);
|
||||
return 0;
|
||||
}
|
||||
EOF
|
||||
|
||||
if $pkg_config libssh2 --modversion >/dev/null 2>&1; then
|
||||
libssh2_cflags=`$pkg_config libssh2 --cflags`
|
||||
libssh2_libs=`$pkg_config libssh2 --libs`
|
||||
else
|
||||
libssh2_cflags=
|
||||
libssh2_libs="-lssh2"
|
||||
fi
|
||||
|
||||
if compile_prog "$libssh2_cflags" "$libssh2_libs" ; then
|
||||
libssh2=yes
|
||||
libs_tools="$libssh2_libs $libs_tools"
|
||||
libs_softmmu="$libssh2_libs $libs_softmmu"
|
||||
QEMU_CFLAGS="$QEMU_CFLAGS $libssh2_cflags"
|
||||
else
|
||||
if test "$libssh2" = "yes" ; then
|
||||
feature_not_found "libssh2"
|
||||
fi
|
||||
libssh2=no
|
||||
fi
|
||||
fi
|
||||
|
||||
##########################################
|
||||
# linux-aio probe
|
||||
|
||||
@ -3435,6 +3478,7 @@ echo "virtio-blk-data-plane $virtio_blk_data_plane"
|
||||
echo "gcov $gcov_tool"
|
||||
echo "gcov enabled $gcov"
|
||||
echo "TPM support $tpm"
|
||||
echo "libssh2 support $libssh2"
|
||||
|
||||
if test "$sdl_too_old" = "yes"; then
|
||||
echo "-> Your SDL version is too old - please upgrade to have SDL support"
|
||||
@ -3793,6 +3837,10 @@ if test "$glusterfs" = "yes" ; then
|
||||
echo "CONFIG_GLUSTERFS=y" >> $config_host_mak
|
||||
fi
|
||||
|
||||
if test "$libssh2" = "yes" ; then
|
||||
echo "CONFIG_LIBSSH2=y" >> $config_host_mak
|
||||
fi
|
||||
|
||||
if test "$virtio_blk_data_plane" = "yes" ; then
|
||||
echo 'CONFIG_VIRTIO_BLK_DATA_PLANE=$(CONFIG_VIRTIO)' >> $config_host_mak
|
||||
fi
|
||||
|
||||
@ -423,6 +423,7 @@ snapshots.
|
||||
* disk_images_sheepdog:: Sheepdog disk images
|
||||
* disk_images_iscsi:: iSCSI LUNs
|
||||
* disk_images_gluster:: GlusterFS disk images
|
||||
* disk_images_ssh:: Secure Shell (ssh) disk images
|
||||
@end menu
|
||||
|
||||
@node disk_images_quickstart
|
||||
@ -1038,6 +1039,54 @@ qemu-system-x86_64 -drive file=gluster+unix:///testvol/dir/a.img?socket=/tmp/glu
|
||||
qemu-system-x86_64 -drive file=gluster+rdma://1.2.3.4:24007/testvol/a.img
|
||||
@end example
|
||||
|
||||
@node disk_images_ssh
|
||||
@subsection Secure Shell (ssh) disk images
|
||||
|
||||
You can access disk images located on a remote ssh server
|
||||
by using the ssh protocol:
|
||||
|
||||
@example
|
||||
qemu-system-x86_64 -drive file=ssh://[@var{user}@@]@var{server}[:@var{port}]/@var{path}[?host_key_check=@var{host_key_check}]
|
||||
@end example
|
||||
|
||||
Alternative syntax using properties:
|
||||
|
||||
@example
|
||||
qemu-system-x86_64 -drive file.driver=ssh[,file.user=@var{user}],file.host=@var{server}[,file.port=@var{port}],file.path=@var{path}[,file.host_key_check=@var{host_key_check}]
|
||||
@end example
|
||||
|
||||
@var{ssh} is the protocol.
|
||||
|
||||
@var{user} is the remote user. If not specified, then the local
|
||||
username is tried.
|
||||
|
||||
@var{server} specifies the remote ssh server. Any ssh server can be
|
||||
used, but it must implement the sftp-server protocol. Most Unix/Linux
|
||||
systems should work without requiring any extra configuration.
|
||||
|
||||
@var{port} is the port number on which sshd is listening. By default
|
||||
the standard ssh port (22) is used.
|
||||
|
||||
@var{path} is the path to the disk image.
|
||||
|
||||
The optional @var{host_key_check} parameter controls how the remote
|
||||
host's key is checked. The default is @code{yes} which means to use
|
||||
the local @file{.ssh/known_hosts} file. Setting this to @code{no}
|
||||
turns off known-hosts checking. Or you can check that the host key
|
||||
matches a specific fingerprint:
|
||||
@code{host_key_check=md5:78:45:8e:14:57:4f:d5:45:83:0a:0e:f3:49:82:c9:c8}
|
||||
(@code{sha1:} can also be used as a prefix, but note that OpenSSH
|
||||
tools only use MD5 to print fingerprints).
|
||||
|
||||
Currently authentication must be done using ssh-agent. Other
|
||||
authentication methods may be supported in future.
|
||||
|
||||
Note: The ssh driver does not obey disk flush requests (ie. to commit
|
||||
data to the backing disk when the guest requests it). This is because
|
||||
the underlying protocol (SFTP) does not support this. Thus there is a
|
||||
risk of guest disk corruption if the remote server or network goes
|
||||
down during writes.
|
||||
|
||||
@node pcsys_network
|
||||
@section Network emulation
|
||||
|
||||
|
||||
@ -2107,6 +2107,18 @@ Example for Unix Domain Sockets
|
||||
qemu-system-i386 --drive file=nbd:unix:/tmp/nbd-socket
|
||||
@end example
|
||||
|
||||
@item SSH
|
||||
QEMU supports SSH (Secure Shell) access to remote disks.
|
||||
|
||||
Examples:
|
||||
@example
|
||||
qemu-system-i386 -drive file=ssh://user@@host/path/to/disk.img
|
||||
qemu-system-i386 -drive file.driver=ssh,file.user=user,file.host=host,file.port=22,file.path=/path/to/disk.img
|
||||
@end example
|
||||
|
||||
Currently authentication must be done using ssh-agent. Other
|
||||
authentication methods may be supported in future.
|
||||
|
||||
@item Sheepdog
|
||||
Sheepdog is a distributed storage system for QEMU.
|
||||
QEMU supports using either local sheepdog devices or remote networked
|
||||
|
||||
Loading…
x
Reference in New Issue
Block a user