From 4d4eb9e793e7722c05c697812320a14ae5797bae Mon Sep 17 00:00:00 2001

From: Pino Toscano <ptoscano@redhat.com>

Date: Mon, 8 Jul 2019 15:26:00 +0100

Subject: [PATCH 14/39] ssh: switch from libssh2 to libssh

MIME-Version: 1.0

Content-Type: text/plain; charset=UTF-8

Content-Transfer-Encoding: 8bit

RH-Author: Pino Toscano <ptoscano@redhat.com>

Message-id: <20190708152601.21123-10-ptoscano@redhat.com>

Patchwork-id: 89421

O-Subject: [RHEL-8.1.0 qemu-kvm PATCH v3 09/10] ssh: switch from libssh2 to libssh

Bugzilla: 1513367

RH-Acked-by: Philippe Mathieu-Daudé <philmd@redhat.com>

RH-Acked-by: Max Reitz <mreitz@redhat.com>

RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>

RH-Acked-by: Markus Armbruster <armbru@redhat.com>

Rewrite the implementation of the ssh block driver to use libssh instead

of libssh2.  The libssh library has various advantages over libssh2:

- easier API for authentication (for example for using ssh-agent)

- easier API for known_hosts handling

- supports newer types of keys in known_hosts

Use APIs/features available in libssh 0.8 conditionally, to support

older versions (which are not recommended though).

Adjust the iotest 207 according to the different error message, and to

find the default key type for localhost (to properly compare the

fingerprint with).

Contributed-by: Max Reitz <mreitz@redhat.com>

Adjust the various Docker/Travis scripts to use libssh when available

instead of libssh2. The mingw/mxe testing is dropped for now, as there

are no packages for it.

Signed-off-by: Pino Toscano <ptoscano@redhat.com>

Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>

Acked-by: Alex Bennée <alex.bennee@linaro.org>

Message-id: 20190620200840.17655-1-ptoscano@redhat.com

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>

Message-id: 5873173.t2JhDm7DL7@lindworm.usersys.redhat.com

Signed-off-by: Max Reitz <mreitz@redhat.com>

(cherry picked from commit b10d49d7619e4957b4b971f816661b57e5061d71)

Signed-off-by: Pino Toscano <ptoscano@redhat.com>

Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>

---

 .travis.yml                                        |   4 +-

 block/Makefile.objs                                |   6 +-

 block/ssh.c                                        | 652 ++++++++++++---------

 block/trace-events                                 |  14 +-

 configure                                          |  65 +-

 docs/qemu-block-drivers.texi                       |   2 +-

 tests/docker/dockerfiles/debian-win32-cross.docker |   1 -

 tests/docker/dockerfiles/debian-win64-cross.docker |   1 -

 tests/docker/dockerfiles/fedora.docker             |   6 +-

 tests/docker/dockerfiles/ubuntu.docker             |   2 +-

 tests/qemu-iotests/207                             |  54 +-

 tests/qemu-iotests/207.out                         |   2 +-

 12 files changed, 450 insertions(+), 359 deletions(-)

diff --git a/.travis.yml b/.travis.yml

index c1e9923..d174d82 100644

--- a/.travis.yml

+++ b/.travis.yml

@@ -28,7 +28,7 @@ addons:

       - libseccomp-dev

       - libspice-protocol-dev

       - libspice-server-dev

-      - libssh2-1-dev

+      - libssh-dev

       - liburcu-dev

       - libusb-1.0-0-dev

       - libvte-2.90-dev

@@ -188,7 +188,7 @@ matrix:

             - libseccomp-dev

             - libspice-protocol-dev

             - libspice-server-dev

-            - libssh2-1-dev

+            - libssh-dev

             - liburcu-dev

             - libusb-1.0-0-dev

             - libvte-2.90-dev

diff --git a/block/Makefile.objs b/block/Makefile.objs

index ac7a1f8..51cd336 100644

--- a/block/Makefile.objs

+++ b/block/Makefile.objs

@@ -30,7 +30,7 @@ block-obj-$(CONFIG_CURL) += curl.o

 block-obj-$(CONFIG_RBD) += rbd.o

 block-obj-$(CONFIG_GLUSTERFS) += gluster.o

 block-obj-$(CONFIG_VXHS) += vxhs.o

-block-obj-$(CONFIG_LIBSSH2) += ssh.o

+block-obj-$(CONFIG_LIBSSH) += ssh.o

 block-obj-y += accounting.o dirty-bitmap.o

 block-obj-y += write-threshold.o

 block-obj-y += backup.o

@@ -51,8 +51,8 @@ rbd.o-libs         := $(RBD_LIBS)

 gluster.o-cflags   := $(GLUSTERFS_CFLAGS)

 gluster.o-libs     := $(GLUSTERFS_LIBS)

 vxhs.o-libs        := $(VXHS_LIBS)

-ssh.o-cflags       := $(LIBSSH2_CFLAGS)

-ssh.o-libs         := $(LIBSSH2_LIBS)

+ssh.o-cflags       := $(LIBSSH_CFLAGS)

+ssh.o-libs         := $(LIBSSH_LIBS)

 block-obj-dmg-bz2-$(CONFIG_BZIP2) += dmg-bz2.o

 block-obj-$(if $(CONFIG_DMG),m,n) += $(block-obj-dmg-bz2-y)

 dmg-bz2.o-libs     := $(BZIP2_LIBS)

diff --git a/block/ssh.c b/block/ssh.c

index f0ef874..a4a374c 100644

--- a/block/ssh.c

+++ b/block/ssh.c

@@ -24,8 +24,8 @@

 #include "qemu/osdep.h"

-#include <libssh2.h>

-#include <libssh2_sftp.h>

+#include <libssh/libssh.h>

+#include <libssh/sftp.h>

 #include "block/block_int.h"

 #include "block/qdict.h"

@@ -44,13 +44,11 @@

 #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

+ * 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_LIBSSH2 0 /* or try: LIBSSH2_TRACE_SFTP */

+#define TRACE_LIBSSH  0 /* see: SSH_LOG_* */

 typedef struct BDRVSSHState {

     /* Coroutine. */

@@ -58,18 +56,15 @@ typedef struct BDRVSSHState {

     /* SSH connection. */

     int sock;                         /* socket */

-    LIBSSH2_SESSION *session;         /* ssh session */

-    LIBSSH2_SFTP *sftp;               /* sftp session */

-    LIBSSH2_SFTP_HANDLE *sftp_handle; /* sftp remote file handle */

+    ssh_session session;              /* ssh session */

+    sftp_session sftp;                /* sftp session */

+    sftp_file 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

+    /*

+     * File attributes at open.  We try to keep the .size field

      * updated if it changes (eg by writing at the end of the file).

      */

-    LIBSSH2_SFTP_ATTRIBUTES attrs;

+    sftp_attributes attrs;

     InetSocketAddress *inet;

@@ -89,7 +84,6 @@ static void ssh_state_init(BDRVSSHState *s)

 {

     memset(s, 0, sizeof *s);

     s->sock = -1;

-    s->offset = -1;

     qemu_co_mutex_init(&s->lock);

 }

@@ -97,20 +91,18 @@ static void ssh_state_free(BDRVSSHState *s)

 {

     g_free(s->user);

+    if (s->attrs) {

+        sftp_attributes_free(s->attrs);

+    }

     if (s->sftp_handle) {

-        libssh2_sftp_close(s->sftp_handle);

+        sftp_close(s->sftp_handle);

     }

     if (s->sftp) {

-        libssh2_sftp_shutdown(s->sftp);

+        sftp_free(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);

+        ssh_disconnect(s->session);

+        ssh_free(s->session); /* This frees s->sock */

     }

 }

@@ -125,13 +117,13 @@ session_error_setg(Error **errp, BDRVSSHState *s, const char *fs, ...)

     va_end(args);

     if (s->session) {

-        char *ssh_err;

+        const 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)",

+        /* 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);

@@ -150,18 +142,18 @@ sftp_error_setg(Error **errp, BDRVSSHState *s, const char *fs, ...)

     va_end(args);

     if (s->sftp) {

-        char *ssh_err;

+        const char *ssh_err;

         int ssh_err_code;

-        unsigned long sftp_err_code;

+        int 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);

+        /* 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 (libssh2 error code: %d, sftp error code: %lu)",

+                   "%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);

@@ -171,15 +163,15 @@ sftp_error_setg(Error **errp, BDRVSSHState *s, const char *fs, ...)

 static void sftp_error_trace(BDRVSSHState *s, const char *op)

 {

-    char *ssh_err;

+    const char *ssh_err;

     int ssh_err_code;

-    unsigned long sftp_err_code;

+    int 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);

+    /* 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);

 }

@@ -280,82 +272,120 @@ static void ssh_parse_filename(const char *filename, QDict *options,

     parse_uri(filename, options, errp);

 }

-static int check_host_key_knownhosts(BDRVSSHState *s,

-                                     const char *host, int port, Error **errp)

+static int check_host_key_knownhosts(BDRVSSHState *s, 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) {

+    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;

-        session_error_setg(errp, s, "failed to read remote host key");

+        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;

-    }

-

-    knh = libssh2_knownhost_init(s->session);

-    if (!knh) {

+    case SSH_KNOWN_HOSTS_OTHER:

         ret = -EINVAL;

-        session_error_setg(errp, s,

-                           "failed to initialize known hosts support");

+        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;

-    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);

+    state = ssh_is_server_known(s->session);

+    trace_ssh_server_status(state);

-    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:

+    switch (state) {

+    case SSH_SERVER_KNOWN_OK:

         /* OK */

-        trace_ssh_check_host_key_knownhosts(found->key);

+        trace_ssh_check_host_key_knownhosts();

         break;

-    case LIBSSH2_KNOWNHOST_CHECK_MISMATCH:

+    case SSH_SERVER_KNOWN_CHANGED:

         ret = -EINVAL;

-        session_error_setg(errp, s,

-                      "host key does not match the one in known_hosts"

-                      " (found key %s)", found->key);

+        error_setg(errp,

+                   "host key does not match the one in known_hosts; this "

+                   "may be a possible attack");

         goto out;

-    case LIBSSH2_KNOWNHOST_CHECK_NOTFOUND:

+    case SSH_SERVER_FOUND_OTHER:

         ret = -EINVAL;

-        session_error_setg(errp, s, "no host key was found in known_hosts");

+        error_setg(errp,

+                   "host key for this server not found, another type exists");

         goto out;

-    case LIBSSH2_KNOWNHOST_CHECK_FAILURE:

+    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;

-        session_error_setg(errp, s,

-                      "failure matching the host key with known_hosts");

+        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;

-        session_error_setg(errp, s, "unknown error matching the host key"

-                      " with known_hosts (%d)", r);

+        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:

-    if (knh != NULL) {

-        libssh2_knownhost_free(knh);

-    }

-    g_free(knh_file);

     return ret;

 }

@@ -399,18 +429,34 @@ static int compare_fingerprint(const unsigned char *fingerprint, size_t len,

 static int

 check_host_key_hash(BDRVSSHState *s, const char *hash,

-                    int hash_type, size_t fingerprint_len, Error **errp)

+                    enum ssh_publickey_hash_type type, Error **errp)

 {

-    const char *fingerprint;

-

-    fingerprint = libssh2_hostkey_hash(s->session, hash_type);

-    if (!fingerprint) {

+    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;

     }

-    if(compare_fingerprint((unsigned char *) fingerprint, fingerprint_len,

-                           hash) != 0) {

+    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;

@@ -419,8 +465,7 @@ check_host_key_hash(BDRVSSHState *s, const char *hash,

     return 0;

 }

-static int check_host_key(BDRVSSHState *s, const char *host, int port,

-                          SshHostKeyCheck *hkc, Error **errp)

+static int check_host_key(BDRVSSHState *s, SshHostKeyCheck *hkc, Error **errp)

 {

     SshHostKeyCheckMode mode;

@@ -436,15 +481,15 @@ static int check_host_key(BDRVSSHState *s, const char *host, int port,

     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);

+                                       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,

-                                       LIBSSH2_HOSTKEY_HASH_SHA1, 20, errp);

+                                       SSH_PUBLICKEY_HASH_SHA1, errp);

         }

         g_assert_not_reached();

         break;

     case SSH_HOST_KEY_CHECK_MODE_KNOWN_HOSTS:

-        return check_host_key_knownhosts(s, host, port, errp);

+        return check_host_key_knownhosts(s, errp);

     default:

         g_assert_not_reached();

     }

@@ -452,60 +497,43 @@ static int check_host_key(BDRVSSHState *s, const char *host, int port,

     return -EINVAL;

 }

-static int authenticate(BDRVSSHState *s, const char *user, Error **errp)

+static int authenticate(BDRVSSHState *s, Error **errp)

 {

     int r, ret;

-    const char *userauthlist;

-    LIBSSH2_AGENT *agent = NULL;

-    struct libssh2_agent_publickey *identity;

-    struct libssh2_agent_publickey *prev_identity = NULL;

+    int method;

-    userauthlist = libssh2_userauth_list(s->session, user, strlen(user));

-    if (strstr(userauthlist, "publickey") == NULL) {

+    /* Try to authenticate with the "none" method. */

+    r = ssh_userauth_none(s->session, NULL);

+    if (r == SSH_AUTH_ERROR) {

         ret = -EPERM;

-        error_setg(errp,

-                "remote server does not support \"publickey\" authentication");

+        session_error_setg(errp, s, "failed to authenticate using none "

+                                    "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");

+    } else if (r == SSH_AUTH_SUCCESS) {

+        /* Authenticated! */

+        ret = 0;

         goto out;

     }

-    for(;;) {

-        r = libssh2_agent_get_identity(agent, &identity, prev_identity);

-        if (r == 1) {           /* end of list */

-            break;

-        }

-        if (r < 0) {

+    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 obtain identity from ssh-agent");

+            session_error_setg(errp, s, "failed to authenticate using "

+                                        "publickey authentication");

             goto out;

-        }

-        r = libssh2_agent_userauth(agent, user, identity);

-        if (r == 0) {

+        } else if (r == SSH_AUTH_SUCCESS) {

             /* Authenticated! */

             ret = 0;

             goto out;

         }

-        /* Failed to authenticate with this identity, try the next one. */

-        prev_identity = identity;

     }

     ret = -EPERM;

@@ -513,13 +541,6 @@ static int authenticate(BDRVSSHState *s, const char *user, Error **errp)

                "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;

 }

@@ -638,7 +659,8 @@ static int connect_to_ssh(BDRVSSHState *s, BlockdevOptionsSsh *opts,

                           int ssh_flags, int creat_mode, Error **errp)

 {

     int r, ret;

-    long port = 0;

+    unsigned int port = 0;

+    int new_sock = -1;

     if (opts->has_user) {

         s->user = g_strdup(opts->user);

@@ -655,71 +677,147 @@ static int connect_to_ssh(BDRVSSHState *s, BlockdevOptionsSsh *opts,

     s->inet = opts->server;

     opts->server = NULL;

-    if (qemu_strtol(s->inet->port, NULL, 10, &port) < 0) {

+    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. */

-    s->sock = inet_connect_saddr(s->inet, errp);

-    if (s->sock < 0) {

+    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 = libssh2_session_init();

+    s->session = ssh_new();

     if (!s->session) {

         ret = -EINVAL;

-        session_error_setg(errp, s, "failed to initialize libssh2 session");

+        session_error_setg(errp, s, "failed to initialize libssh session");

         goto err;

     }

-#if TRACE_LIBSSH2 != 0

-    libssh2_trace(s->session, TRACE_LIBSSH2);

-#endif

+    /*

+     * Make sure we are in blocking mode during the connection and

+     * authentication phases.

+     */

+    ssh_set_blocking(s->session, 1);

-    r = libssh2_session_handshake(s->session, s->sock);

-    if (r != 0) {

+    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,