Adding upstream version 1:8.4p1.upstream/1%8.4p1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2314 insertions, 0 deletions

diff --git a/sshconnect2.c b/sshconnect2.c
new file mode 100644
index 0000000..f64aae6
--- /dev/null
+++ b/sshconnect2.c
@@ -0,0 +1,2314 @@
+/* $OpenBSD: sshconnect2.c,v 1.326 2020/09/18 05:23:03 djm Exp $ */
+/*
+ * Copyright (c) 2000 Markus Friedl.  All rights reserved.
+ * Copyright (c) 2008 Damien Miller.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "includes.h"
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/wait.h>
+#include <sys/stat.h>
+
+#include <errno.h>
+#include <fcntl.h>
+#include <netdb.h>
+#include <pwd.h>
+#include <signal.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdarg.h>
+#include <unistd.h>
+#if defined(HAVE_STRNVIS) && defined(HAVE_VIS_H) && !defined(BROKEN_STRNVIS)
+#include <vis.h>
+#endif
+
+#include "openbsd-compat/sys-queue.h"
+
+#include "xmalloc.h"
+#include "ssh.h"
+#include "ssh2.h"
+#include "sshbuf.h"
+#include "packet.h"
+#include "compat.h"
+#include "cipher.h"
+#include "sshkey.h"
+#include "kex.h"
+#include "myproposal.h"
+#include "sshconnect.h"
+#include "authfile.h"
+#include "dh.h"
+#include "authfd.h"
+#include "log.h"
+#include "misc.h"
+#include "readconf.h"
+#include "match.h"
+#include "dispatch.h"
+#include "canohost.h"
+#include "msg.h"
+#include "pathnames.h"
+#include "uidswap.h"
+#include "hostfile.h"
+#include "ssherr.h"
+#include "utf8.h"
+#include "ssh-sk.h"
+#include "sk-api.h"
+
+#ifdef GSSAPI
+#include "ssh-gss.h"
+#endif
+
+/* import */
+extern char *client_version_string;
+extern char *server_version_string;
+extern Options options;
+
+/*
+ * SSH2 key exchange
+ */
+
+u_char *session_id2 = NULL;
+u_int session_id2_len = 0;
+
+char *xxx_host;
+struct sockaddr *xxx_hostaddr;
+
+static int
+verify_host_key_callback(struct sshkey *hostkey, struct ssh *ssh)
+{
+	if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1)
+		fatal("Host key verification failed.");
+	return 0;
+}
+
+/* Returns the first item from a comma-separated algorithm list */
+static char *
+first_alg(const char *algs)
+{
+	char *ret, *cp;
+
+	ret = xstrdup(algs);
+	if ((cp = strchr(ret, ',')) != NULL)
+		*cp = '\0';
+	return ret;
+}
+
+static char *
+order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port)
+{
+	char *oavail = NULL, *avail = NULL, *first = NULL, *last = NULL;
+	char *alg = NULL, *hostname = NULL, *ret = NULL, *best = NULL;
+	size_t maxlen;
+	struct hostkeys *hostkeys = NULL;
+	int ktype;
+	u_int i;
+
+	/* Find all hostkeys for this hostname */
+	get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL);
+	hostkeys = init_hostkeys();
+	for (i = 0; i < options.num_user_hostfiles; i++)
+		load_hostkeys(hostkeys, hostname, options.user_hostfiles[i]);
+	for (i = 0; i < options.num_system_hostfiles; i++)
+		load_hostkeys(hostkeys, hostname, options.system_hostfiles[i]);
+
+	/*
+	 * If a plain public key exists that matches the type of the best
+	 * preference HostkeyAlgorithms, then use the whole list as is.
+	 * Note that we ignore whether the best preference algorithm is a
+	 * certificate type, as sshconnect.c will downgrade certs to
+	 * plain keys if necessary.
+	 */
+	best = first_alg(options.hostkeyalgorithms);
+	if (lookup_key_in_hostkeys_by_type(hostkeys,
+	    sshkey_type_plain(sshkey_type_from_name(best)), NULL)) {
+		debug3("%s: have matching best-preference key type %s, "
+		    "using HostkeyAlgorithms verbatim", __func__, best);
+		ret = xstrdup(options.hostkeyalgorithms);
+		goto out;
+	}
+
+	/*
+	 * Otherwise, prefer the host key algorithms that match known keys
+	 * while keeping the ordering of HostkeyAlgorithms as much as possible.
+	 */
+	oavail = avail = xstrdup(options.hostkeyalgorithms);
+	maxlen = strlen(avail) + 1;
+	first = xmalloc(maxlen);
+	last = xmalloc(maxlen);
+	*first = *last = '\0';
+
+#define ALG_APPEND(to, from) \
+	do { \
+		if (*to != '\0') \
+			strlcat(to, ",", maxlen); \
+		strlcat(to, from, maxlen); \
+	} while (0)
+
+	while ((alg = strsep(&avail, ",")) && *alg != '\0') {
+		if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC)
+			fatal("%s: unknown alg %s", __func__, alg);
+		/*
+		 * If we have a @cert-authority marker in known_hosts then
+		 * prefer all certificate algorithms.
+		 */
+		if (sshkey_type_is_cert(ktype) &&
+		    lookup_marker_in_hostkeys(hostkeys, MRK_CA)) {
+			ALG_APPEND(first, alg);
+			continue;
+		}
+		/* If the key appears in known_hosts then prefer it */
+		if (lookup_key_in_hostkeys_by_type(hostkeys,
+		    sshkey_type_plain(ktype), NULL)) {
+			ALG_APPEND(first, alg);
+			continue;
+		}
+		/* Otherwise, put it last */
+		ALG_APPEND(last, alg);
+	}
+#undef ALG_APPEND
+	xasprintf(&ret, "%s%s%s", first,
+	    (*first == '\0' || *last == '\0') ? "" : ",", last);
+	if (*first != '\0')
+		debug3("%s: prefer hostkeyalgs: %s", __func__, first);
+
+ out:
+	free(best);
+	free(first);
+	free(last);
+	free(hostname);
+	free(oavail);
+	free_hostkeys(hostkeys);
+
+	return ret;
+}
+
+void
+ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port)
+{
+	char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT };
+	char *s, *all_key;
+	int r, use_known_hosts_order = 0;
+
+	xxx_host = host;
+	xxx_hostaddr = hostaddr;
+
+	/*
+	 * If the user has not specified HostkeyAlgorithms, or has only
+	 * appended or removed algorithms from that list then prefer algorithms
+	 * that are in the list that are supported by known_hosts keys.
+	 */
+	if (options.hostkeyalgorithms == NULL ||
+	    options.hostkeyalgorithms[0] == '-' ||
+	    options.hostkeyalgorithms[0] == '+')
+		use_known_hosts_order = 1;
+
+	/* Expand or fill in HostkeyAlgorithms */
+	all_key = sshkey_alg_list(0, 0, 1, ',');
+	if (kex_assemble_names(&options.hostkeyalgorithms,
+	    kex_default_pk_alg(), all_key) != 0)
+		fatal("%s: kex_assemble_namelist", __func__);
+	free(all_key);
+
+	if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL)
+		fatal("%s: kex_names_cat", __func__);
+	myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(s);
+	myproposal[PROPOSAL_ENC_ALGS_CTOS] =
+	    compat_cipher_proposal(options.ciphers);
+	myproposal[PROPOSAL_ENC_ALGS_STOC] =
+	    compat_cipher_proposal(options.ciphers);
+	myproposal[PROPOSAL_COMP_ALGS_CTOS] =
+	    myproposal[PROPOSAL_COMP_ALGS_STOC] =
+	    (char *)compression_alg_list(options.compression);
+	myproposal[PROPOSAL_MAC_ALGS_CTOS] =
+	    myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
+	if (use_known_hosts_order) {
+		/* Query known_hosts and prefer algorithms that appear there */
+		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
+		    compat_pkalg_proposal(
+		    order_hostkeyalgs(host, hostaddr, port));
+	} else {
+		/* Use specified HostkeyAlgorithms exactly */
+		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
+		    compat_pkalg_proposal(options.hostkeyalgorithms);
+	}
+
+	if (options.rekey_limit || options.rekey_interval)
+		ssh_packet_set_rekey_limits(ssh, options.rekey_limit,
+		    options.rekey_interval);
+
+	/* start key exchange */
+	if ((r = kex_setup(ssh, myproposal)) != 0)
+		fatal("kex_setup: %s", ssh_err(r));
+#ifdef WITH_OPENSSL
+	ssh->kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_client;
+	ssh->kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_client;
+	ssh->kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_client;
+	ssh->kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_client;
+	ssh->kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_client;
+	ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
+	ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
+# ifdef OPENSSL_HAS_ECC
+	ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client;
+# endif
+#endif
+	ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client;
+	ssh->kex->kex[KEX_KEM_SNTRUP4591761X25519_SHA512] = kex_gen_client;
+	ssh->kex->verify_host_key=&verify_host_key_callback;
+
+	ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &ssh->kex->done);
+
+	/* remove ext-info from the KEX proposals for rekeying */
+	myproposal[PROPOSAL_KEX_ALGS] =
+	    compat_kex_proposal(options.kex_algorithms);
+	if ((r = kex_prop2buf(ssh->kex->my, myproposal)) != 0)
+		fatal("kex_prop2buf: %s", ssh_err(r));
+
+	session_id2 = ssh->kex->session_id;
+	session_id2_len = ssh->kex->session_id_len;
+
+#ifdef DEBUG_KEXDH
+	/* send 1st encrypted/maced/compressed message */
+	if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, "markus")) != 0 ||
+	    (r = sshpkt_send(ssh)) != 0 ||
+	    (r = ssh_packet_write_wait(ssh)) != 0)
+		fatal("%s: %s", __func__, ssh_err(r));
+#endif
+}
+
+/*
+ * Authenticate user
+ */
+
+typedef struct cauthctxt Authctxt;
+typedef struct cauthmethod Authmethod;
+typedef struct identity Identity;
+typedef struct idlist Idlist;
+
+struct identity {
+	TAILQ_ENTRY(identity) next;
+	int	agent_fd;		/* >=0 if agent supports key */
+	struct sshkey	*key;		/* public/private key */
+	char	*filename;		/* comment for agent-only keys */
+	int	tried;
+	int	isprivate;		/* key points to the private key */
+	int	userprovided;
+};
+TAILQ_HEAD(idlist, identity);
+
+struct cauthctxt {
+	const char *server_user;
+	const char *local_user;
+	const char *host;
+	const char *service;
+	struct cauthmethod *method;
+	sig_atomic_t success;
+	char *authlist;
+#ifdef GSSAPI
+	/* gssapi */
+	gss_OID_set gss_supported_mechs;
+	u_int mech_tried;
+#endif
+	/* pubkey */
+	struct idlist keys;
+	int agent_fd;
+	/* hostbased */
+	Sensitive *sensitive;
+	char *oktypes, *ktypes;
+	const char *active_ktype;
+	/* kbd-interactive */
+	int info_req_seen;
+	int attempt_kbdint;
+	/* password */
+	int attempt_passwd;
+	/* generic */
+	void *methoddata;
+};
+
+struct cauthmethod {
+	char	*name;		/* string to compare against server's list */
+	int	(*userauth)(struct ssh *ssh);
+	void	(*cleanup)(struct ssh *ssh);
+	int	*enabled;	/* flag in option struct that enables method */
+	int	*batch_flag;	/* flag in option struct that disables method */
+};
+
+static int input_userauth_service_accept(int, u_int32_t, struct ssh *);
+static int input_userauth_ext_info(int, u_int32_t, struct ssh *);
+static int input_userauth_success(int, u_int32_t, struct ssh *);
+static int input_userauth_failure(int, u_int32_t, struct ssh *);
+static int input_userauth_banner(int, u_int32_t, struct ssh *);
+static int input_userauth_error(int, u_int32_t, struct ssh *);
+static int input_userauth_info_req(int, u_int32_t, struct ssh *);
+static int input_userauth_pk_ok(int, u_int32_t, struct ssh *);
+static int input_userauth_passwd_changereq(int, u_int32_t, struct ssh *);
+
+static int userauth_none(struct ssh *);
+static int userauth_pubkey(struct ssh *);
+static int userauth_passwd(struct ssh *);
+static int userauth_kbdint(struct ssh *);
+static int userauth_hostbased(struct ssh *);
+
+#ifdef GSSAPI
+static int userauth_gssapi(struct ssh *);
+static void userauth_gssapi_cleanup(struct ssh *);
+static int input_gssapi_response(int type, u_int32_t, struct ssh *);
+static int input_gssapi_token(int type, u_int32_t, struct ssh *);
+static int input_gssapi_error(int, u_int32_t, struct ssh *);
+static int input_gssapi_errtok(int, u_int32_t, struct ssh *);
+#endif
+
+void	userauth(struct ssh *, char *);
+
+static void pubkey_cleanup(struct ssh *);
+static int sign_and_send_pubkey(struct ssh *ssh, Identity *);
+static void pubkey_prepare(Authctxt *);
+static void pubkey_reset(Authctxt *);
+static struct sshkey *load_identity_file(Identity *);
+
+static Authmethod *authmethod_get(char *authlist);
+static Authmethod *authmethod_lookup(const char *name);
+static char *authmethods_get(void);
+
+Authmethod authmethods[] = {
+#ifdef GSSAPI
+	{"gssapi-with-mic",
+		userauth_gssapi,
+		userauth_gssapi_cleanup,
+		&options.gss_authentication,
+		NULL},
+#endif
+	{"hostbased",
+		userauth_hostbased,
+		NULL,
+		&options.hostbased_authentication,
+		NULL},
+	{"publickey",
+		userauth_pubkey,
+		NULL,
+		&options.pubkey_authentication,
+		NULL},
+	{"keyboard-interactive",
+		userauth_kbdint,
+		NULL,
+		&options.kbd_interactive_authentication,
+		&options.batch_mode},
+	{"password",
+		userauth_passwd,
+		NULL,
+		&options.password_authentication,
+		&options.batch_mode},
+	{"none",
+		userauth_none,
+		NULL,
+		NULL,
+		NULL},
+	{NULL, NULL, NULL, NULL, NULL}
+};
+
+void
+ssh_userauth2(struct ssh *ssh, const char *local_user,
+    const char *server_user, char *host, Sensitive *sensitive)
+{
+	Authctxt authctxt;
+	int r;
+
+	if (options.challenge_response_authentication)
+		options.kbd_interactive_authentication = 1;
+	if (options.preferred_authentications == NULL)
+		options.preferred_authentications = authmethods_get();
+
+	/* setup authentication context */
+	memset(&authctxt, 0, sizeof(authctxt));
+	authctxt.server_user = server_user;
+	authctxt.local_user = local_user;
+	authctxt.host = host;
+	authctxt.service = "ssh-connection";		/* service name */
+	authctxt.success = 0;
+	authctxt.method = authmethod_lookup("none");
+	authctxt.authlist = NULL;
+	authctxt.methoddata = NULL;
+	authctxt.sensitive = sensitive;
+	authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL;
+	authctxt.info_req_seen = 0;
+	authctxt.attempt_kbdint = 0;
+	authctxt.attempt_passwd = 0;
+#if GSSAPI
+	authctxt.gss_supported_mechs = NULL;
+	authctxt.mech_tried = 0;
+#endif
+	authctxt.agent_fd = -1;
+	pubkey_prepare(&authctxt);
+	if (authctxt.method == NULL) {
+		fatal("%s: internal error: cannot send userauth none request",
+		    __func__);
+	}
+
+	if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 ||
+	    (r = sshpkt_send(ssh)) != 0)
+		fatal("%s: %s", __func__, ssh_err(r));
+
+	ssh->authctxt = &authctxt;
+	ssh_dispatch_init(ssh, &input_userauth_error);
+	ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_ext_info);
+	ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept);
+	ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success);	/* loop until success */
+	pubkey_cleanup(ssh);
+	ssh->authctxt = NULL;
+
+	ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL);
+
+	if (!authctxt.success)
+		fatal("Authentication failed.");
+	debug("Authentication succeeded (%s).", authctxt.method->name);
+}
+
+/* ARGSUSED */
+static int
+input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh)
+{
+	int r;
+
+	if (ssh_packet_remaining(ssh) > 0) {
+		char *reply;
+
+		if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0)
+			goto out;
+		debug2("service_accept: %s", reply);
+		free(reply);
+	} else {
+		debug2("buggy server: service_accept w/o service");
+	}
+	if ((r = sshpkt_get_end(ssh)) != 0)
+		goto out;
+	debug("SSH2_MSG_SERVICE_ACCEPT received");
+
+	/* initial userauth request */
+	userauth_none(ssh);
+
+	ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_error);
+	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
+	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
+	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
+	r = 0;
+ out:
+	return r;
+}
+
+/* ARGSUSED */
+static int
+input_userauth_ext_info(int type, u_int32_t seqnr, struct ssh *ssh)
+{
+	return kex_input_ext_info(type, seqnr, ssh);
+}
+
+void
+userauth(struct ssh *ssh, char *authlist)
+{
+	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
+
+	if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
+		authctxt->method->cleanup(ssh);
+
+	free(authctxt->methoddata);
+	authctxt->methoddata = NULL;
+	if (authlist == NULL) {
+		authlist = authctxt->authlist;
+	} else {
+		free(authctxt->authlist);
+		authctxt->authlist = authlist;
+	}
+	for (;;) {
+		Authmethod *method = authmethod_get(authlist);
+		if (method == NULL)
+			fatal("%s@%s: Permission denied (%s).",
+			    authctxt->server_user, authctxt->host, authlist);
+		authctxt->method = method;
+
+		/* reset the per method handler */
+		ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_PER_METHOD_MIN,
+		    SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);
+
+		/* and try new method */
+		if (method->userauth(ssh) != 0) {
+			debug2("we sent a %s packet, wait for reply", method->name);
+			break;
+		} else {
+			debug2("we did not send a packet, disable method");
+			method->enabled = NULL;
+		}
+	}
+}
+
+/* ARGSUSED */
+static int
+input_userauth_error(int type, u_int32_t seq, struct ssh *ssh)
+{
+	fatal("%s: bad message during authentication: type %d", __func__, type);
+	return 0;
+}
+
+/* ARGSUSED */
+static int
+input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh)
+{
+	char *msg = NULL;
+	size_t len;
+	int r;
+
+	debug3("%s", __func__);
+	if ((r = sshpkt_get_cstring(ssh, &msg, &len)) != 0 ||
+	    (r = sshpkt_get_cstring(ssh, NULL, NULL)) != 0)
+		goto out;
+	if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO)
+		fmprintf(stderr, "%s", msg);
+	r = 0;
+ out:
+	free(msg);
+	return r;
+}
+
+/* ARGSUSED */
+static int
+input_userauth_success(int type, u_int32_t seq, struct ssh *ssh)
+{
+	Authctxt *authctxt = ssh->authctxt;
+
+	if (authctxt == NULL)
+		fatal("%s: no authentication context", __func__);
+	free(authctxt->authlist);
+	authctxt->authlist = NULL;
+	if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
+		authctxt->method->cleanup(ssh);
+	free(authctxt->methoddata);
+	authctxt->methoddata = NULL;
+	authctxt->success = 1;			/* break out */
+	return 0;
+}
+
+#if 0
+static int
+input_userauth_success_unexpected(int type, u_int32_t seq, struct ssh *ssh)
+{
+	Authctxt *authctxt = ssh->authctxt;
+
+	if (authctxt == NULL)
+		fatal("%s: no authentication context", __func__);
+
+	fatal("Unexpected authentication success during %s.",
+	    authctxt->method->name);
+	return 0;
+}
+#endif
+
+/* ARGSUSED */
+static int
+input_userauth_failure(int type, u_int32_t seq, struct ssh *ssh)
+{
+	Authctxt *authctxt = ssh->authctxt;
+	char *authlist = NULL;
+	u_char partial;
+
+	if (authctxt == NULL)
+		fatal("input_userauth_failure: no authentication context");
+
+	if (sshpkt_get_cstring(ssh, &authlist, NULL) != 0 ||
+	    sshpkt_get_u8(ssh, &partial) != 0 ||
+	    sshpkt_get_end(ssh) != 0)
+		goto out;
+
+	if (partial != 0) {
+		verbose("Authenticated with partial success.");
+		/* reset state */
+		pubkey_reset(authctxt);
+	}
+	debug("Authentications that can continue: %s", authlist);
+
+	userauth(ssh, authlist);
+	authlist = NULL;
+ out:
+	free(authlist);
+	return 0;
+}
+
+/*
+ * Format an identity for logging including filename, key type, fingerprint
+ * and location (agent, etc.). Caller must free.
+ */
+static char *
+format_identity(Identity *id)
+{
+	char *fp = NULL, *ret = NULL;
+	const char *note = "";
+
+	if (id->key != NULL) {
+	     fp = sshkey_fingerprint(id->key, options.fingerprint_hash,
+		    SSH_FP_DEFAULT);
+	}
+	if (id->key) {
+		if ((id->key->flags & SSHKEY_FLAG_EXT) != 0)
+			note = " token";
+		else if (sshkey_is_sk(id->key))
+			note = " authenticator";
+	}
+	xasprintf(&ret, "%s %s%s%s%s%s%s",
+	    id->filename,
+	    id->key ? sshkey_type(id->key) : "", id->key ? " " : "",
+	    fp ? fp : "",
+	    id->userprovided ? " explicit" : "", note,
+	    id->agent_fd != -1 ? " agent" : "");
+	free(fp);
+	return ret;
+}
+
+/* ARGSUSED */
+static int
+input_userauth_pk_ok(int type, u_int32_t seq, struct ssh *ssh)
+{
+	Authctxt *authctxt = ssh->authctxt;
+	struct sshkey *key = NULL;
+	Identity *id = NULL;
+	int pktype, found = 0, sent = 0;
+	size_t blen;
+	char *pkalg = NULL, *fp = NULL, *ident = NULL;
+	u_char *pkblob = NULL;
+	int r;
+
+	if (authctxt == NULL)
+		fatal("input_userauth_pk_ok: no authentication context");
+
+	if ((r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 ||
+	    (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0 ||
+	    (r = sshpkt_get_end(ssh)) != 0)
+		goto done;
+
+	if ((pktype = sshkey_type_from_name(pkalg)) == KEY_UNSPEC) {
+		debug("%s: server sent unknown pkalg %s", __func__, pkalg);
+		goto done;
+	}
+	if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) {
+		debug("no key from blob. pkalg %s: %s", pkalg, ssh_err(r));
+		goto done;
+	}
+	if (key->type != pktype) {
+		error("input_userauth_pk_ok: type mismatch "
+		    "for decoded key (received %d, expected %d)",
+		    key->type, pktype);
+		goto done;
+	}
+
+	/*
+	 * search keys in the reverse order, because last candidate has been
+	 * moved to the end of the queue.  this also avoids confusion by
+	 * duplicate keys
+	 */
+	TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) {
+		if (sshkey_equal(key, id->key)) {
+			found = 1;
+			break;
+		}
+	}
+	if (!found || id == NULL) {
+		fp = sshkey_fingerprint(key, options.fingerprint_hash,
+		    SSH_FP_DEFAULT);
+		error("%s: server replied with unknown key: %s %s", __func__,
+		    sshkey_type(key), fp == NULL ? "<ERROR>" : fp);
+		goto done;
+	}
+	ident = format_identity(id);
+	debug("Server accepts key: %s", ident);
+	sent = sign_and_send_pubkey(ssh, id);
+	r = 0;
+ done:
+	sshkey_free(key);
+	free(ident);
+	free(fp);
+	free(pkalg);
+	free(pkblob);
+
+	/* try another method if we did not send a packet */
+	if (r == 0 && sent == 0)
+		userauth(ssh, NULL);
+	return r;
+}
+
+#ifdef GSSAPI
+static int
+userauth_gssapi(struct ssh *ssh)
+{
+	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
+	Gssctxt *gssctxt = NULL;
+	OM_uint32 min;
+	int r, ok = 0;
+	gss_OID mech = NULL;
+
+	/* Try one GSSAPI method at a time, rather than sending them all at
+	 * once. */
+
+	if (authctxt->gss_supported_mechs == NULL)
+		gss_indicate_mechs(&min, &authctxt->gss_supported_mechs);
+
+	/* Check to see whether the mechanism is usable before we offer it */
+	while (authctxt->mech_tried < authctxt->gss_supported_mechs->count &&
+	    !ok) {
+		mech = &authctxt->gss_supported_mechs->
+		    elements[authctxt->mech_tried];
+		/* My DER encoding requires length<128 */
+		if (mech->length < 128 && ssh_gssapi_check_mechanism(&gssctxt,
+		    mech, authctxt->host)) {
+			ok = 1; /* Mechanism works */
+		} else {
+			authctxt->mech_tried++;
+		}
+	}
+
+	if (!ok || mech == NULL)
+		return 0;
+
+	authctxt->methoddata=(void *)gssctxt;
+
+	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
+	    (r = sshpkt_put_u32(ssh, 1)) != 0 ||
+	    (r = sshpkt_put_u32(ssh, (mech->length) + 2)) != 0 ||
+	    (r = sshpkt_put_u8(ssh, SSH_GSS_OIDTYPE)) != 0 ||
+	    (r = sshpkt_put_u8(ssh, mech->length)) != 0 ||
+	    (r = sshpkt_put(ssh, mech->elements, mech->length)) != 0 ||
+	    (r = sshpkt_send(ssh)) != 0)
+		fatal("%s: %s", __func__, ssh_err(r));
+
+	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
+	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
+	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
+	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
+
+	authctxt->mech_tried++; /* Move along to next candidate */
+
+	return 1;
+}
+
+static void
+userauth_gssapi_cleanup(struct ssh *ssh)
+{
+	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
+	Gssctxt *gssctxt = (Gssctxt *)authctxt->methoddata;
+
+	ssh_gssapi_delete_ctx(&gssctxt);
+	authctxt->methoddata = NULL;
+
+	free(authctxt->gss_supported_mechs);
+	authctxt->gss_supported_mechs = NULL;
+}
+
+static OM_uint32
+process_gssapi_token(struct ssh *ssh, gss_buffer_t recv_tok)
+{
+	Authctxt *authctxt = ssh->authctxt;
+	Gssctxt *gssctxt = authctxt->methoddata;
+	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
+	gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
+	gss_buffer_desc gssbuf;
+	OM_uint32 status, ms, flags;
+	int r;
+
+	status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
+	    recv_tok, &send_tok, &flags);
+
+	if (send_tok.length > 0) {
+		u_char type = GSS_ERROR(status) ?
+		    SSH2_MSG_USERAUTH_GSSAPI_ERRTOK :
+		    SSH2_MSG_USERAUTH_GSSAPI_TOKEN;
+
+		if ((r = sshpkt_start(ssh, type)) != 0 ||
+		    (r = sshpkt_put_string(ssh, send_tok.value,
+		    send_tok.length)) != 0 ||
+		    (r = sshpkt_send(ssh)) != 0)
+			fatal("%s: %s", __func__, ssh_err(r));
+
+		gss_release_buffer(&ms, &send_tok);
+	}
+
+	if (status == GSS_S_COMPLETE) {
+		/* send either complete or MIC, depending on mechanism */
+		if (!(flags & GSS_C_INTEG_FLAG)) {
+			if ((r = sshpkt_start(ssh,
+			    SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE)) != 0 ||
+			    (r = sshpkt_send(ssh)) != 0)
+				fatal("%s: %s", __func__, ssh_err(r));
+		} else {
+			struct sshbuf *b;
+
+			if ((b = sshbuf_new()) == NULL)
+				fatal("%s: sshbuf_new failed", __func__);
+			ssh_gssapi_buildmic(b, authctxt->server_user,
+			    authctxt->service, "gssapi-with-mic");
+
+			if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL)
+				fatal("%s: sshbuf_mutable_ptr failed", __func__);
+			gssbuf.length = sshbuf_len(b);
+
+			status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);
+
+			if (!GSS_ERROR(status)) {
+				if ((r = sshpkt_start(ssh,
+				    SSH2_MSG_USERAUTH_GSSAPI_MIC)) != 0 ||
+				    (r = sshpkt_put_string(ssh, mic.value,
+				    mic.length)) != 0 ||
+				    (r = sshpkt_send(ssh)) != 0)
+					fatal("%s: %s", __func__, ssh_err(r));
+			}
+
+			sshbuf_free(b);
+			gss_release_buffer(&ms, &mic);
+		}
+	}
+
+	return status;
+}
+
+/* ARGSUSED */
+static int
+input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh)
+{
+	Authctxt *authctxt = ssh->authctxt;
+	Gssctxt *gssctxt;
+	size_t oidlen;
+	u_char *oidv = NULL;
+	int r;
+
+	if (authctxt == NULL)
+		fatal("input_gssapi_response: no authentication context");
+	gssctxt = authctxt->methoddata;
+
+	/* Setup our OID */
+	if ((r = sshpkt_get_string(ssh, &oidv, &oidlen)) != 0)
+		goto done;
+
+	if (oidlen <= 2 ||
+	    oidv[0] != SSH_GSS_OIDTYPE ||
+	    oidv[1] != oidlen - 2) {
+		debug("Badly encoded mechanism OID received");
+		userauth(ssh, NULL);
+		goto ok;
+	}
+
+	if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2))
+		fatal("Server returned different OID than expected");
+
+	if ((r = sshpkt_get_end(ssh)) != 0)
+		goto done;
+
+	if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) {
+		/* Start again with next method on list */
+		debug("Trying to start again");
+		userauth(ssh, NULL);
+		goto ok;
+	}
+ ok:
+	r = 0;
+ done:
+	free(oidv);
+	return r;
+}
+
+/* ARGSUSED */
+static int
+input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh)
+{
+	Authctxt *authctxt = ssh->authctxt;
+	gss_buffer_desc recv_tok;
+	u_char *p = NULL;
+	size_t len;
+	OM_uint32 status;
+	int r;
+
+	if (authctxt == NULL)
+		fatal("input_gssapi_response: no authentication context");
+
+	if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 ||
+	    (r = sshpkt_get_end(ssh)) != 0)
+		goto out;
+
+	recv_tok.value = p;
+	recv_tok.length = len;
+	status = process_gssapi_token(ssh, &recv_tok);
+
+	/* Start again with the next method in the list */
+	if (GSS_ERROR(status)) {
+		userauth(ssh, NULL);
+		/* ok */
+	}
+	r = 0;
+ out:
+	free(p);
+	return r;
+}
+
+/* ARGSUSED */
+static int
+input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh)
+{
+	Authctxt *authctxt = ssh->authctxt;
+	Gssctxt *gssctxt;
+	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
+	gss_buffer_desc recv_tok;
+	OM_uint32 ms;
+	u_char *p = NULL;
+	size_t len;
+	int r;
+
+	if (authctxt == NULL)
+		fatal("input_gssapi_response: no authentication context");
+	gssctxt = authctxt->methoddata;
+
+	if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 ||
+	    (r = sshpkt_get_end(ssh)) != 0) {
+		free(p);
+		return r;
+	}
+
+	/* Stick it into GSSAPI and see what it says */
+	recv_tok.value = p;
+	recv_tok.length = len;
+	(void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
+	    &recv_tok, &send_tok, NULL);
+	free(p);
+	gss_release_buffer(&ms, &send_tok);
+
+	/* Server will be returning a failed packet after this one */
+	return 0;
+}
+
+/* ARGSUSED */
+static int
+input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh)
+{
+	char *msg = NULL;
+	char *lang = NULL;
+	int r;
+
+	if ((r = sshpkt_get_u32(ssh, NULL)) != 0 ||	/* maj */
+	    (r = sshpkt_get_u32(ssh, NULL)) != 0 ||	/* min */
+	    (r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 ||
+	    (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0)
+		goto out;
+	r = sshpkt_get_end(ssh);
+	debug("Server GSSAPI Error:\n%s", msg);
+ out:
+	free(msg);
+	free(lang);
+	return r;
+}
+#endif /* GSSAPI */
+
+static int
+userauth_none(struct ssh *ssh)
+{
+	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
+	int r;
+
+	/* initial userauth request */
+	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
+	    (r = sshpkt_send(ssh)) != 0)
+		fatal("%s: %s", __func__, ssh_err(r));
+	return 1;
+}
+
+static int
+userauth_passwd(struct ssh *ssh)
+{
+	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
+	char *password, *prompt = NULL;
+	const char *host = options.host_key_alias ?  options.host_key_alias :
+	    authctxt->host;
+	int r;
+
+	if (authctxt->attempt_passwd++ >= options.number_of_password_prompts)
+		return 0;
+
+	if (authctxt->attempt_passwd != 1)
+		error("Permission denied, please try again.");
+
+	xasprintf(&prompt, "%s@%s's password: ", authctxt->server_user, host);
+	password = read_passphrase(prompt, 0);
+	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
+	    (r = sshpkt_put_u8(ssh, 0)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, password)) != 0 ||
+	    (r = sshpkt_add_padding(ssh, 64)) != 0 ||
+	    (r = sshpkt_send(ssh)) != 0)
+		fatal("%s: %s", __func__, ssh_err(r));
+
+	free(prompt);
+	if (password != NULL)
+		freezero(password, strlen(password));
+
+	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
+	    &input_userauth_passwd_changereq);
+
+	return 1;
+}
+
+/*
+ * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
+ */
+/* ARGSUSED */
+static int
+input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh)
+{
+	Authctxt *authctxt = ssh->authctxt;
+	char *info = NULL, *lang = NULL, *password = NULL, *retype = NULL;
+	char prompt[256];
+	const char *host;
+	int r;
+
+	debug2("input_userauth_passwd_changereq");
+
+	if (authctxt == NULL)
+		fatal("input_userauth_passwd_changereq: "
+		    "no authentication context");
+	host = options.host_key_alias ? options.host_key_alias : authctxt->host;
+
+	if ((r = sshpkt_get_cstring(ssh, &info, NULL)) != 0 ||
+	    (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0)
+		goto out;
+	if (strlen(info) > 0)
+		logit("%s", info);
+	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
+	    (r = sshpkt_put_u8(ssh, 1)) != 0)	/* additional info */
+		goto out;
+
+	snprintf(prompt, sizeof(prompt),
+	    "Enter %.30s@%.128s's old password: ",
+	    authctxt->server_user, host);
+	password = read_passphrase(prompt, 0);
+	if ((r = sshpkt_put_cstring(ssh, password)) != 0)
+		goto out;
+
+	freezero(password, strlen(password));
+	password = NULL;
+	while (password == NULL) {
+		snprintf(prompt, sizeof(prompt),
+		    "Enter %.30s@%.128s's new password: ",
+		    authctxt->server_user, host);
+		password = read_passphrase(prompt, RP_ALLOW_EOF);
+		if (password == NULL) {
+			/* bail out */
+			r = 0;
+			goto out;
+		}
+		snprintf(prompt, sizeof(prompt),
+		    "Retype %.30s@%.128s's new password: ",
+		    authctxt->server_user, host);
+		retype = read_passphrase(prompt, 0);
+		if (strcmp(password, retype) != 0) {
+			freezero(password, strlen(password));
+			logit("Mismatch; try again, EOF to quit.");
+			password = NULL;
+		}
+		freezero(retype, strlen(retype));
+	}
+	if ((r = sshpkt_put_cstring(ssh, password)) != 0 ||
+	    (r = sshpkt_add_padding(ssh, 64)) != 0 ||
+	    (r = sshpkt_send(ssh)) != 0)
+		goto out;
+
+	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
+	    &input_userauth_passwd_changereq);
+	r = 0;
+ out:
+	if (password)
+		freezero(password, strlen(password));
+	free(info);
+	free(lang);
+	return r;
+}
+
+/*
+ * Select an algorithm for publickey signatures.
+ * Returns algorithm (caller must free) or NULL if no mutual algorithm found.
+ *
+ * Call with ssh==NULL to ignore server-sig-algs extension list and
+ * only attempt with the key's base signature type.
+ */
+static char *
+key_sig_algorithm(struct ssh *ssh, const struct sshkey *key)
+{
+	char *allowed, *oallowed, *cp, *tmp, *alg = NULL;
+
+	/*
+	 * The signature algorithm will only differ from the key algorithm
+	 * for RSA keys/certs and when the server advertises support for
+	 * newer (SHA2) algorithms.
+	 */
+	if (ssh == NULL || ssh->kex->server_sig_algs == NULL ||
+	    (key->type != KEY_RSA && key->type != KEY_RSA_CERT) ||
+	    (key->type == KEY_RSA_CERT && (datafellows & SSH_BUG_SIGTYPE))) {
+		/* Filter base key signature alg against our configuration */
+		return match_list(sshkey_ssh_name(key),
+		    options.pubkey_key_types, NULL);
+	}
+
+	/*
+	 * For RSA keys/certs, since these might have a different sig type:
+	 * find the first entry in PubkeyAcceptedKeyTypes of the right type
+	 * that also appears in the supported signature algorithms list from
+	 * the server.
+	 */
+	oallowed = allowed = xstrdup(options.pubkey_key_types);
+	while ((cp = strsep(&allowed, ",")) != NULL) {
+		if (sshkey_type_from_name(cp) != key->type)
+			continue;
+		tmp = match_list(sshkey_sigalg_by_name(cp),
+		    ssh->kex->server_sig_algs, NULL);
+		if (tmp != NULL)
+			alg = xstrdup(cp);
+		free(tmp);
+		if (alg != NULL)
+			break;
+	}
+	free(oallowed);
+	return alg;
+}
+
+static int
+identity_sign(struct identity *id, u_char **sigp, size_t *lenp,
+    const u_char *data, size_t datalen, u_int compat, const char *alg)
+{
+	struct sshkey *sign_key = NULL, *prv = NULL;
+	int r = SSH_ERR_INTERNAL_ERROR;
+	struct notifier_ctx *notifier = NULL;
+	char *fp = NULL, *pin = NULL, *prompt = NULL;
+
+	*sigp = NULL;
+	*lenp = 0;
+
+	/* The agent supports this key. */
+	if (id->key != NULL && id->agent_fd != -1) {
+		return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp,
+		    data, datalen, alg, compat);
+	}
+
+	/*
+	 * We have already loaded the private key or the private key is
+	 * stored in external hardware.
+	 */
+	if (id->key != NULL &&
+	    (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) {
+		sign_key = id->key;
+	} else {
+		/* Load the private key from the file. */
+		if ((prv = load_identity_file(id)) == NULL)
+			return SSH_ERR_KEY_NOT_FOUND;
+		if (id->key != NULL && !sshkey_equal_public(prv, id->key)) {
+			error("%s: private key %s contents do not match public",
+			   __func__, id->filename);
+			r = SSH_ERR_KEY_NOT_FOUND;
+			goto out;
+		}
+		sign_key = prv;
+		if (sshkey_is_sk(sign_key)) {
+			if ((sign_key->sk_flags &
+			    SSH_SK_USER_VERIFICATION_REQD)) {
+				xasprintf(&prompt, "Enter PIN for %s key %s: ",
+				    sshkey_type(sign_key), id->filename);
+				pin = read_passphrase(prompt, 0);
+			}
+			if ((sign_key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) {
+				/* XXX should batch mode just skip these? */
+				if ((fp = sshkey_fingerprint(sign_key,
+				    options.fingerprint_hash,
+				    SSH_FP_DEFAULT)) == NULL)
+					fatal("%s: fingerprint", __func__);
+				notifier = notify_start(options.batch_mode,
+				    "Confirm user presence for key %s %s",
+				    sshkey_type(sign_key), fp);
+				free(fp);
+			}
+		}
+	}
+	if ((r = sshkey_sign(sign_key, sigp, lenp, data, datalen,
+	    alg, options.sk_provider, pin, compat)) != 0) {
+		debug("%s: sshkey_sign: %s", __func__, ssh_err(r));
+		goto out;
+	}
+	/*
+	 * PKCS#11 tokens may not support all signature algorithms,
+	 * so check what we get back.
+	 */
+	if ((r = sshkey_check_sigtype(*sigp, *lenp, alg)) != 0) {
+		debug("%s: sshkey_check_sigtype: %s", __func__, ssh_err(r));
+		goto out;
+	}
+	/* success */
+	r = 0;
+ out:
+	free(prompt);
+	if (pin != NULL)
+		freezero(pin, strlen(pin));
+	notify_complete(notifier);
+	sshkey_free(prv);
+	return r;
+}
+
+static int
+id_filename_matches(Identity *id, Identity *private_id)
+{
+	const char *suffixes[] = { ".pub", "-cert.pub", NULL };
+	size_t len = strlen(id->filename), plen = strlen(private_id->filename);
+	size_t i, slen;
+
+	if (strcmp(id->filename, private_id->filename) == 0)
+		return 1;
+	for (i = 0; suffixes[i]; i++) {
+		slen = strlen(suffixes[i]);
+		if (len > slen && plen == len - slen &&
+		    strcmp(id->filename + (len - slen), suffixes[i]) == 0 &&
+		    memcmp(id->filename, private_id->filename, plen) == 0)
+			return 1;
+	}
+	return 0;
+}
+
+static int
+sign_and_send_pubkey(struct ssh *ssh, Identity *id)
+{
+	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
+	struct sshbuf *b = NULL;
+	Identity *private_id, *sign_id = NULL;
+	u_char *signature = NULL;
+	size_t slen = 0, skip = 0;
+	int r, fallback_sigtype, sent = 0;
+	char *alg = NULL, *fp = NULL;
+	const char *loc = "";
+
+	if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash,
+	    SSH_FP_DEFAULT)) == NULL)
+		return 0;
+
+	debug3("%s: %s %s", __func__, sshkey_type(id->key), fp);
+
+	/*
+	 * If the key is an certificate, try to find a matching private key
+	 * and use it to complete the signature.
+	 * If no such private key exists, fall back to trying the certificate
+	 * key itself in case it has a private half already loaded.
+	 * This will try to set sign_id to the private key that will perform
+	 * the signature.
+	 */
+	if (sshkey_is_cert(id->key)) {
+		TAILQ_FOREACH(private_id, &authctxt->keys, next) {
+			if (sshkey_equal_public(id->key, private_id->key) &&
+			    id->key->type != private_id->key->type) {
+				sign_id = private_id;
+				break;
+			}
+		}
+		/*
+		 * Exact key matches are preferred, but also allow
+		 * filename matches for non-PKCS#11/agent keys that
+		 * didn't load public keys. This supports the case
+		 * of keeping just a private key file and public
+		 * certificate on disk.
+		 */
+		if (sign_id == NULL &&
+		    !id->isprivate && id->agent_fd == -1 &&
+		    (id->key->flags & SSHKEY_FLAG_EXT) == 0) {
+			TAILQ_FOREACH(private_id, &authctxt->keys, next) {
+				if (private_id->key == NULL &&
+				    id_filename_matches(id, private_id)) {
+					sign_id = private_id;
+					break;
+				}
+			}
+		}
+		if (sign_id != NULL) {
+			debug2("%s: using private key \"%s\"%s for "
+			    "certificate", __func__, id->filename,
+			    id->agent_fd != -1 ? " from agent" : "");
+		} else {
+			debug("%s: no separate private key for certificate "
+			    "\"%s\"", __func__, id->filename);
+		}
+	}
+
+	/*
+	 * If the above didn't select another identity to do the signing
+	 * then default to the one we started with.
+	 */
+	if (sign_id == NULL)
+		sign_id = id;
+
+	/* assemble and sign data */
+	for (fallback_sigtype = 0; fallback_sigtype <= 1; fallback_sigtype++) {
+		free(alg);
+		slen = 0;
+		signature = NULL;
+		if ((alg = key_sig_algorithm(fallback_sigtype ? NULL : ssh,
+		    id->key)) == NULL) {
+			error("%s: no mutual signature supported", __func__);
+			goto out;
+		}
+		debug3("%s: signing using %s %s", __func__, alg, fp);
+
+		sshbuf_free(b);
+		if ((b = sshbuf_new()) == NULL)
+			fatal("%s: sshbuf_new failed", __func__);
+		if (datafellows & SSH_OLD_SESSIONID) {
+			if ((r = sshbuf_put(b, session_id2,
+			    session_id2_len)) != 0) {
+				fatal("%s: sshbuf_put: %s",
+				    __func__, ssh_err(r));
+			}
+		} else {
+			if ((r = sshbuf_put_string(b, session_id2,
+			    session_id2_len)) != 0) {
+				fatal("%s: sshbuf_put_string: %s",
+				    __func__, ssh_err(r));
+			}
+		}
+		skip = sshbuf_len(b);
+		if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
+		    (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 ||
+		    (r = sshbuf_put_cstring(b, authctxt->service)) != 0 ||
+		    (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 ||
+		    (r = sshbuf_put_u8(b, 1)) != 0 ||
+		    (r = sshbuf_put_cstring(b, alg)) != 0 ||
+		    (r = sshkey_puts(id->key, b)) != 0) {
+			fatal("%s: assemble signed data: %s",
+			    __func__, ssh_err(r));
+		}
+
+		/* generate signature */
+		r = identity_sign(sign_id, &signature, &slen,
+		    sshbuf_ptr(b), sshbuf_len(b), datafellows, alg);
+		if (r == 0)
+			break;
+		else if (r == SSH_ERR_KEY_NOT_FOUND)
+			goto out; /* soft failure */
+		else if (r == SSH_ERR_SIGN_ALG_UNSUPPORTED &&
+		    !fallback_sigtype) {
+			if (sign_id->agent_fd != -1)
+				loc = "agent ";
+			else if ((sign_id->key->flags & SSHKEY_FLAG_EXT) != 0)
+				loc = "token ";
+			logit("%skey %s %s returned incorrect signature type",
+			    loc, sshkey_type(id->key), fp);
+			continue;
+		}
+		error("%s: signing failed for %s \"%s\"%s: %s", __func__,
+		    sshkey_type(sign_id->key), sign_id->filename,
+		    id->agent_fd != -1 ? " from agent" : "", ssh_err(r));
+		goto out;
+	}
+	if (slen == 0 || signature == NULL) /* shouldn't happen */
+		fatal("%s: no signature", __func__);
+
+	/* append signature */
+	if ((r = sshbuf_put_string(b, signature, slen)) != 0)
+		fatal("%s: append signature: %s", __func__, ssh_err(r));
+
+#ifdef DEBUG_PK
+	sshbuf_dump(b, stderr);
+#endif
+	/* skip session id and packet type */
+	if ((r = sshbuf_consume(b, skip + 1)) != 0)
+		fatal("%s: consume: %s", __func__, ssh_err(r));
+
+	/* put remaining data from buffer into packet */
+	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
+	    (r = sshpkt_putb(ssh, b)) != 0 ||
+	    (r = sshpkt_send(ssh)) != 0)
+		fatal("%s: enqueue request: %s", __func__, ssh_err(r));
+
+	/* success */
+	sent = 1;
+
+ out:
+	free(fp);
+	free(alg);
+	sshbuf_free(b);
+	freezero(signature, slen);
+	return sent;
+}
+
+static int
+send_pubkey_test(struct ssh *ssh, Identity *id)
+{
+	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
+	u_char *blob = NULL;
+	char *alg = NULL;
+	size_t bloblen;
+	u_int have_sig = 0;
+	int sent = 0, r;
+
+	if ((alg = key_sig_algorithm(ssh, id->key)) == NULL) {
+		debug("%s: no mutual signature algorithm", __func__);
+		goto out;
+	}
+
+	if ((r = sshkey_to_blob(id->key, &blob, &bloblen)) != 0) {
+		/* we cannot handle this key */
+		debug3("%s: cannot handle key", __func__);
+		goto out;
+	}
+	/* register callback for USERAUTH_PK_OK message */
+	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
+
+	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
+	    (r = sshpkt_put_u8(ssh, have_sig)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, alg)) != 0 ||
+	    (r = sshpkt_put_string(ssh, blob, bloblen)) != 0 ||
+	    (r = sshpkt_send(ssh)) != 0)
+		fatal("%s: %s", __func__, ssh_err(r));
+	sent = 1;
+
+ out:
+	free(alg);
+	free(blob);
+	return sent;
+}
+
+static struct sshkey *
+load_identity_file(Identity *id)
+{
+	struct sshkey *private = NULL;
+	char prompt[300], *passphrase, *comment;
+	int r, quit = 0, i;
+	struct stat st;
+
+	if (stat(id->filename, &st) == -1) {
+		(id->userprovided ? logit : debug3)("no such identity: %s: %s",
+		    id->filename, strerror(errno));
+		return NULL;
+	}
+	snprintf(prompt, sizeof prompt,
+	    "Enter passphrase for key '%.100s': ", id->filename);
+	for (i = 0; i <= options.number_of_password_prompts; i++) {
+		if (i == 0)
+			passphrase = "";
+		else {
+			passphrase = read_passphrase(prompt, 0);
+			if (*passphrase == '\0') {
+				debug2("no passphrase given, try next key");
+				free(passphrase);
+				break;
+			}
+		}
+		switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename,
+		    passphrase, &private, &comment))) {
+		case 0:
+			break;
+		case SSH_ERR_KEY_WRONG_PASSPHRASE:
+			if (options.batch_mode) {
+				quit = 1;
+				break;
+			}
+			if (i != 0)
+				debug2("bad passphrase given, try again...");
+			break;
+		case SSH_ERR_SYSTEM_ERROR:
+			if (errno == ENOENT) {
+				debug2("Load key \"%s\": %s",
+				    id->filename, ssh_err(r));
+				quit = 1;
+				break;
+			}
+			/* FALLTHROUGH */
+		default:
+			error("Load key \"%s\": %s", id->filename, ssh_err(r));
+			quit = 1;
+			break;
+		}
+		if (private != NULL && sshkey_is_sk(private) &&
+		    options.sk_provider == NULL) {
+			debug("key \"%s\" is an authenticator-hosted key, "
+			    "but no provider specified", id->filename);
+			sshkey_free(private);
+			private = NULL;
+			quit = 1;
+		}
+		if (!quit && private != NULL && id->agent_fd == -1 &&
+		    !(id->key && id->isprivate))
+			maybe_add_key_to_agent(id->filename, private, comment,
+			    passphrase);
+		if (i > 0)
+			freezero(passphrase, strlen(passphrase));
+		free(comment);
+		if (private != NULL || quit)
+			break;
+	}
+	return private;
+}
+
+static int
+key_type_allowed_by_config(struct sshkey *key)
+{
+	if (match_pattern_list(sshkey_ssh_name(key),
+	    options.pubkey_key_types, 0) == 1)
+		return 1;
+
+	/* RSA keys/certs might be allowed by alternate signature types */
+	switch (key->type) {
+	case KEY_RSA:
+		if (match_pattern_list("rsa-sha2-512",
+		    options.pubkey_key_types, 0) == 1)
+			return 1;
+		if (match_pattern_list("rsa-sha2-256",
+		    options.pubkey_key_types, 0) == 1)
+			return 1;
+		break;
+	case KEY_RSA_CERT:
+		if (match_pattern_list("rsa-sha2-512-cert-v01@openssh.com",
+		    options.pubkey_key_types, 0) == 1)
+			return 1;
+		if (match_pattern_list("rsa-sha2-256-cert-v01@openssh.com",
+		    options.pubkey_key_types, 0) == 1)
+			return 1;
+		break;
+	}
+	return 0;
+}
+
+
+/*
+ * try keys in the following order:
+ * 	1. certificates listed in the config file
+ * 	2. other input certificates
+ *	3. agent keys that are found in the config file
+ *	4. other agent keys
+ *	5. keys that are only listed in the config file
+ */
+static void
+pubkey_prepare(Authctxt *authctxt)
+{
+	struct identity *id, *id2, *tmp;
+	struct idlist agent, files, *preferred;
+	struct sshkey *key;
+	int agent_fd = -1, i, r, found;
+	size_t j;
+	struct ssh_identitylist *idlist;
+	char *ident;
+
+	TAILQ_INIT(&agent);	/* keys from the agent */
+	TAILQ_INIT(&files);	/* keys from the config file */
+	preferred = &authctxt->keys;
+	TAILQ_INIT(preferred);	/* preferred order of keys */
+
+	/* list of keys stored in the filesystem and PKCS#11 */
+	for (i = 0; i < options.num_identity_files; i++) {
+		key = options.identity_keys[i];
+		if (key && key->cert &&
+		    key->cert->type != SSH2_CERT_TYPE_USER) {
+			debug("%s: ignoring certificate %s: not a user "
+			    "certificate",  __func__,
+			    options.identity_files[i]);
+			continue;
+		}
+		if (key && sshkey_is_sk(key) && options.sk_provider == NULL) {
+			debug("%s: ignoring authenticator-hosted key %s as no "
+			    "SecurityKeyProvider has been specified",
+			    __func__, options.identity_files[i]);
+			continue;
+		}
+		options.identity_keys[i] = NULL;
+		id = xcalloc(1, sizeof(*id));
+		id->agent_fd = -1;
+		id->key = key;
+		id->filename = xstrdup(options.identity_files[i]);
+		id->userprovided = options.identity_file_userprovided[i];
+		TAILQ_INSERT_TAIL(&files, id, next);
+	}
+	/* list of certificates specified by user */
+	for (i = 0; i < options.num_certificate_files; i++) {
+		key = options.certificates[i];
+		if (!sshkey_is_cert(key) || key->cert == NULL ||
+		    key->cert->type != SSH2_CERT_TYPE_USER) {
+			debug("%s: ignoring certificate %s: not a user "
+			    "certificate",  __func__,
+			    options.identity_files[i]);
+			continue;
+		}
+		if (key && sshkey_is_sk(key) && options.sk_provider == NULL) {
+			debug("%s: ignoring authenticator-hosted key "
+			    "certificate %s as no "
+			    "SecurityKeyProvider has been specified",
+			    __func__, options.identity_files[i]);
+			continue;
+		}
+		id = xcalloc(1, sizeof(*id));
+		id->agent_fd = -1;
+		id->key = key;
+		id->filename = xstrdup(options.certificate_files[i]);
+		id->userprovided = options.certificate_file_userprovided[i];
+		TAILQ_INSERT_TAIL(preferred, id, next);
+	}
+	/* list of keys supported by the agent */
+	if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) {
+		if (r != SSH_ERR_AGENT_NOT_PRESENT)
+			debug("%s: ssh_get_authentication_socket: %s",
+			    __func__, ssh_err(r));
+	} else if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) {
+		if (r != SSH_ERR_AGENT_NO_IDENTITIES)
+			debug("%s: ssh_fetch_identitylist: %s",
+			    __func__, ssh_err(r));
+		close(agent_fd);
+	} else {
+		for (j = 0; j < idlist->nkeys; j++) {
+			found = 0;
+			TAILQ_FOREACH(id, &files, next) {
+				/*
+				 * agent keys from the config file are
+				 * preferred
+				 */
+				if (sshkey_equal(idlist->keys[j], id->key)) {
+					TAILQ_REMOVE(&files, id, next);
+					TAILQ_INSERT_TAIL(preferred, id, next);
+					id->agent_fd = agent_fd;
+					found = 1;
+					break;
+				}
+			}
+			if (!found && !options.identities_only) {
+				id = xcalloc(1, sizeof(*id));
+				/* XXX "steals" key/comment from idlist */
+				id->key = idlist->keys[j];
+				id->filename = idlist->comments[j];
+				idlist->keys[j] = NULL;
+				idlist->comments[j] = NULL;
+				id->agent_fd = agent_fd;
+				TAILQ_INSERT_TAIL(&agent, id, next);
+			}
+		}
+		ssh_free_identitylist(idlist);
+		/* append remaining agent keys */
+		TAILQ_CONCAT(preferred, &agent, next);
+		authctxt->agent_fd = agent_fd;
+	}
+	/* Prefer PKCS11 keys that are explicitly listed */
+	TAILQ_FOREACH_SAFE(id, &files, next, tmp) {
+		if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0)
+			continue;
+		found = 0;
+		TAILQ_FOREACH(id2, &files, next) {
+			if (id2->key == NULL ||
+			    (id2->key->flags & SSHKEY_FLAG_EXT) != 0)
+				continue;
+			if (sshkey_equal(id->key, id2->key)) {
+				TAILQ_REMOVE(&files, id, next);
+				TAILQ_INSERT_TAIL(preferred, id, next);
+				found = 1;
+				break;
+			}
+		}
+		/* If IdentitiesOnly set and key not found then don't use it */
+		if (!found && options.identities_only) {
+			TAILQ_REMOVE(&files, id, next);
+			freezero(id, sizeof(*id));
+		}
+	}
+	/* append remaining keys from the config file */
+	TAILQ_CONCAT(preferred, &files, next);
+	/* finally, filter by PubkeyAcceptedKeyTypes */
+	TAILQ_FOREACH_SAFE(id, preferred, next, id2) {
+		if (id->key != NULL && !key_type_allowed_by_config(id->key)) {
+			debug("Skipping %s key %s - "
+			    "not in PubkeyAcceptedKeyTypes",
+			    sshkey_ssh_name(id->key), id->filename);
+			TAILQ_REMOVE(preferred, id, next);
+			sshkey_free(id->key);
+			free(id->filename);
+			memset(id, 0, sizeof(*id));
+			continue;
+		}
+	}
+	/* List the keys we plan on using */
+	TAILQ_FOREACH_SAFE(id, preferred, next, id2) {
+		ident = format_identity(id);
+		debug("Will attempt key: %s", ident);
+		free(ident);
+	}
+	debug2("%s: done", __func__);
+}
+
+static void
+pubkey_cleanup(struct ssh *ssh)
+{
+	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
+	Identity *id;
+
+	if (authctxt->agent_fd != -1) {
+		ssh_close_authentication_socket(authctxt->agent_fd);
+		authctxt->agent_fd = -1;
+	}
+	for (id = TAILQ_FIRST(&authctxt->keys); id;
+	    id = TAILQ_FIRST(&authctxt->keys)) {
+		TAILQ_REMOVE(&authctxt->keys, id, next);
+		sshkey_free(id->key);
+		free(id->filename);
+		free(id);
+	}
+}
+
+static void
+pubkey_reset(Authctxt *authctxt)
+{
+	Identity *id;
+
+	TAILQ_FOREACH(id, &authctxt->keys, next)
+		id->tried = 0;
+}
+
+static int
+try_identity(Identity *id)
+{
+	if (!id->key)
+		return (0);
+	if (sshkey_type_plain(id->key->type) == KEY_RSA &&
+	    (datafellows & SSH_BUG_RSASIGMD5) != 0) {
+		debug("Skipped %s key %s for RSA/MD5 server",
+		    sshkey_type(id->key), id->filename);
+		return (0);
+	}
+	return 1;
+}
+
+static int
+userauth_pubkey(struct ssh *ssh)
+{
+	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
+	Identity *id;
+	int sent = 0;
+	char *ident;
+
+	while ((id = TAILQ_FIRST(&authctxt->keys))) {
+		if (id->tried++)
+			return (0);
+		/* move key to the end of the queue */
+		TAILQ_REMOVE(&authctxt->keys, id, next);
+		TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
+		/*
+		 * send a test message if we have the public key. for
+		 * encrypted keys we cannot do this and have to load the
+		 * private key instead
+		 */
+		if (id->key != NULL) {
+			if (try_identity(id)) {
+				ident = format_identity(id);
+				debug("Offering public key: %s", ident);
+				free(ident);
+				sent = send_pubkey_test(ssh, id);
+			}
+		} else {
+			debug("Trying private key: %s", id->filename);
+			id->key = load_identity_file(id);
+			if (id->key != NULL) {
+				if (try_identity(id)) {
+					id->isprivate = 1;
+					sent = sign_and_send_pubkey(ssh, id);
+				}
+				sshkey_free(id->key);
+				id->key = NULL;
+				id->isprivate = 0;
+			}
+		}
+		if (sent)
+			return (sent);
+	}
+	return (0);
+}
+
+/*
+ * Send userauth request message specifying keyboard-interactive method.
+ */
+static int
+userauth_kbdint(struct ssh *ssh)
+{
+	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
+	int r;
+
+	if (authctxt->attempt_kbdint++ >= options.number_of_password_prompts)
+		return 0;
+	/* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
+	if (authctxt->attempt_kbdint > 1 && !authctxt->info_req_seen) {
+		debug3("userauth_kbdint: disable: no info_req_seen");
+		ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
+		return 0;
+	}
+
+	debug2("userauth_kbdint");
+	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, "")) != 0 ||		/* lang */
+	    (r = sshpkt_put_cstring(ssh, options.kbd_interactive_devices ?
+	    options.kbd_interactive_devices : "")) != 0 ||
+	    (r = sshpkt_send(ssh)) != 0)
+		fatal("%s: %s", __func__, ssh_err(r));
+
+	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
+	return 1;
+}
+
+/*
+ * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
+ */
+static int
+input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh)
+{
+	Authctxt *authctxt = ssh->authctxt;
+	char *name = NULL, *inst = NULL, *lang = NULL, *prompt = NULL;
+	char *response = NULL;
+	u_char echo = 0;
+	u_int num_prompts, i;
+	int r;
+
+	debug2("input_userauth_info_req");
+
+	if (authctxt == NULL)
+		fatal("input_userauth_info_req: no authentication context");
+
+	authctxt->info_req_seen = 1;
+
+	if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 ||
+	    (r = sshpkt_get_cstring(ssh, &inst, NULL)) != 0 ||
+	    (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0)
+		goto out;
+	if (strlen(name) > 0)
+		logit("%s", name);
+	if (strlen(inst) > 0)
+		logit("%s", inst);
+
+	if ((r = sshpkt_get_u32(ssh, &num_prompts)) != 0)
+		goto out;
+	/*
+	 * Begin to build info response packet based on prompts requested.
+	 * We commit to providing the correct number of responses, so if
+	 * further on we run into a problem that prevents this, we have to
+	 * be sure and clean this up and send a correct error response.
+	 */
+	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE)) != 0 ||
+	    (r = sshpkt_put_u32(ssh, num_prompts)) != 0)
+		goto out;
+
+	debug2("input_userauth_info_req: num_prompts %d", num_prompts);
+	for (i = 0; i < num_prompts; i++) {
+		if ((r = sshpkt_get_cstring(ssh, &prompt, NULL)) != 0 ||
+		    (r = sshpkt_get_u8(ssh, &echo)) != 0)
+			goto out;
+		response = read_passphrase(prompt, echo ? RP_ECHO : 0);
+		if ((r = sshpkt_put_cstring(ssh, response)) != 0)
+			goto out;
+		freezero(response, strlen(response));
+		free(prompt);
+		response = prompt = NULL;
+	}
+	/* done with parsing incoming message. */
+	if ((r = sshpkt_get_end(ssh)) != 0 ||
+	    (r = sshpkt_add_padding(ssh, 64)) != 0)
+		goto out;
+	r = sshpkt_send(ssh);
+ out:
+	if (response)
+		freezero(response, strlen(response));
+	free(prompt);
+	free(name);
+	free(inst);
+	free(lang);
+	return r;
+}
+
+static int
+ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp,
+    const u_char *data, size_t datalen)
+{
+	struct sshbuf *b;
+	struct stat st;
+	pid_t pid;
+	int r, to[2], from[2], status;
+	int sock = ssh_packet_get_connection_in(ssh);
+	u_char rversion = 0, version = 2;
+	void (*osigchld)(int);
+
+	*sigp = NULL;
+	*lenp = 0;
+
+	if (stat(_PATH_SSH_KEY_SIGN, &st) == -1) {
+		error("%s: not installed: %s", __func__, strerror(errno));
+		return -1;
+	}
+	if (fflush(stdout) != 0) {
+		error("%s: fflush: %s", __func__, strerror(errno));
+		return -1;
+	}
+	if (pipe(to) == -1) {
+		error("%s: pipe: %s", __func__, strerror(errno));
+		return -1;
+	}
+	if (pipe(from) == -1) {
+		error("%s: pipe: %s", __func__, strerror(errno));
+		return -1;
+	}
+	if ((pid = fork()) == -1) {
+		error("%s: fork: %s", __func__, strerror(errno));
+		return -1;
+	}
+	osigchld = ssh_signal(SIGCHLD, SIG_DFL);
+	if (pid == 0) {
+		close(from[0]);
+		if (dup2(from[1], STDOUT_FILENO) == -1)
+			fatal("%s: dup2: %s", __func__, strerror(errno));
+		close(to[1]);
+		if (dup2(to[0], STDIN_FILENO) == -1)
+			fatal("%s: dup2: %s", __func__, strerror(errno));
+		close(from[1]);
+		close(to[0]);
+
+		if (dup2(sock, STDERR_FILENO + 1) == -1)
+			fatal("%s: dup2: %s", __func__, strerror(errno));
+		sock = STDERR_FILENO + 1;
+		fcntl(sock, F_SETFD, 0);	/* keep the socket on exec */
+		closefrom(sock + 1);
+
+		debug3("%s: [child] pid=%ld, exec %s",
+		    __func__, (long)getpid(), _PATH_SSH_KEY_SIGN);
+		execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL);
+		fatal("%s: exec(%s): %s", __func__, _PATH_SSH_KEY_SIGN,
+		    strerror(errno));
+	}
+	close(from[1]);
+	close(to[0]);
+	sock = STDERR_FILENO + 1;
+
+	if ((b = sshbuf_new()) == NULL)
+		fatal("%s: sshbuf_new failed", __func__);
+	/* send # of sock, data to be signed */
+	if ((r = sshbuf_put_u32(b, sock)) != 0 ||
+	    (r = sshbuf_put_string(b, data, datalen)) != 0)
+		fatal("%s: buffer error: %s", __func__, ssh_err(r));
+	if (ssh_msg_send(to[1], version, b) == -1)
+		fatal("%s: couldn't send request", __func__);
+	sshbuf_reset(b);
+	r = ssh_msg_recv(from[0], b);
+	close(from[0]);
+	close(to[1]);
+	if (r < 0) {
+		error("%s: no reply", __func__);
+		goto fail;
+	}
+
+	errno = 0;
+	while (waitpid(pid, &status, 0) == -1) {
+		if (errno != EINTR) {
+			error("%s: waitpid %ld: %s",
+			    __func__, (long)pid, strerror(errno));
+			goto fail;
+		}
+	}
+	if (!WIFEXITED(status)) {
+		error("%s: exited abnormally", __func__);
+		goto fail;
+	}
+	if (WEXITSTATUS(status) != 0) {
+		error("%s: exited with status %d",
+		    __func__, WEXITSTATUS(status));
+		goto fail;
+	}
+	if ((r = sshbuf_get_u8(b, &rversion)) != 0) {
+		error("%s: buffer error: %s", __func__, ssh_err(r));
+		goto fail;
+	}
+	if (rversion != version) {
+		error("%s: bad version", __func__);
+		goto fail;
+	}
+	if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) {
+		error("%s: buffer error: %s", __func__, ssh_err(r));
+ fail:
+		ssh_signal(SIGCHLD, osigchld);
+		sshbuf_free(b);
+		return -1;
+	}
+	ssh_signal(SIGCHLD, osigchld);
+	sshbuf_free(b);
+
+	return 0;
+}
+
+static int
+userauth_hostbased(struct ssh *ssh)
+{
+	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
+	struct sshkey *private = NULL;
+	struct sshbuf *b = NULL;
+	u_char *sig = NULL, *keyblob = NULL;
+	char *fp = NULL, *chost = NULL, *lname = NULL;
+	size_t siglen = 0, keylen = 0;
+	int i, r, success = 0;
+
+	if (authctxt->ktypes == NULL) {
+		authctxt->oktypes = xstrdup(options.hostbased_key_types);
+		authctxt->ktypes = authctxt->oktypes;
+	}
+
+	/*
+	 * Work through each listed type pattern in HostbasedKeyTypes,
+	 * trying each hostkey that matches the type in turn.
+	 */
+	for (;;) {
+		if (authctxt->active_ktype == NULL)
+			authctxt->active_ktype = strsep(&authctxt->ktypes, ",");
+		if (authctxt->active_ktype == NULL ||
+		    *authctxt->active_ktype == '\0')
+			break;
+		debug3("%s: trying key type %s", __func__,
+		    authctxt->active_ktype);
+
+		/* check for a useful key */
+		private = NULL;
+		for (i = 0; i < authctxt->sensitive->nkeys; i++) {
+			if (authctxt->sensitive->keys[i] == NULL ||
+			    authctxt->sensitive->keys[i]->type == KEY_UNSPEC)
+				continue;
+			if (match_pattern_list(
+			    sshkey_ssh_name(authctxt->sensitive->keys[i]),
+			    authctxt->active_ktype, 0) != 1)
+				continue;
+			/* we take and free the key */
+			private = authctxt->sensitive->keys[i];
+			authctxt->sensitive->keys[i] = NULL;
+			break;
+		}
+		/* Found one */
+		if (private != NULL)
+			break;
+		/* No more keys of this type; advance */
+		authctxt->active_ktype = NULL;
+	}
+	if (private == NULL) {
+		free(authctxt->oktypes);
+		authctxt->oktypes = authctxt->ktypes = NULL;
+		authctxt->active_ktype = NULL;
+		debug("No more client hostkeys for hostbased authentication.");
+		goto out;
+	}
+
+	if ((fp = sshkey_fingerprint(private, options.fingerprint_hash,
+	    SSH_FP_DEFAULT)) == NULL) {
+		error("%s: sshkey_fingerprint failed", __func__);
+		goto out;
+	}
+	debug("%s: trying hostkey %s %s",
+	    __func__, sshkey_ssh_name(private), fp);
+
+	/* figure out a name for the client host */
+	lname = get_local_name(ssh_packet_get_connection_in(ssh));
+	if (lname == NULL) {
+		error("%s: cannot get local ipaddr/name", __func__);
+		goto out;
+	}
+
+	/* XXX sshbuf_put_stringf? */
+	xasprintf(&chost, "%s.", lname);
+	debug2("%s: chost %s", __func__, chost);
+
+	/* construct data */
+	if ((b = sshbuf_new()) == NULL) {
+		error("%s: sshbuf_new failed", __func__);
+		goto out;
+	}
+	if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) {
+		error("%s: sshkey_to_blob: %s", __func__, ssh_err(r));
+		goto out;
+	}
+	if ((r = sshbuf_put_string(b, session_id2, session_id2_len)) != 0 ||
+	    (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
+	    (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 ||
+	    (r = sshbuf_put_cstring(b, authctxt->service)) != 0 ||
+	    (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 ||
+	    (r = sshbuf_put_cstring(b, sshkey_ssh_name(private))) != 0 ||
+	    (r = sshbuf_put_string(b, keyblob, keylen)) != 0 ||
+	    (r = sshbuf_put_cstring(b, chost)) != 0 ||
+	    (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) {
+		error("%s: buffer error: %s", __func__, ssh_err(r));
+		goto out;
+	}
+
+#ifdef DEBUG_PK
+	sshbuf_dump(b, stderr);
+#endif
+	if ((r = ssh_keysign(ssh, private, &sig, &siglen,
+	    sshbuf_ptr(b), sshbuf_len(b))) != 0) {
+		error("sign using hostkey %s %s failed",
+		    sshkey_ssh_name(private), fp);
+		goto out;
+	}
+	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, sshkey_ssh_name(private))) != 0 ||
+	    (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, chost)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 ||
+	    (r = sshpkt_put_string(ssh, sig, siglen)) != 0 ||
+	    (r = sshpkt_send(ssh)) != 0) {
+		error("%s: packet error: %s", __func__, ssh_err(r));
+		goto out;
+	}
+	success = 1;
+
+ out:
+	if (sig != NULL)
+		freezero(sig, siglen);
+	free(keyblob);
+	free(lname);
+	free(fp);
+	free(chost);
+	sshkey_free(private);
+	sshbuf_free(b);
+
+	return success;
+}
+
+/* find auth method */
+
+/*
+ * given auth method name, if configurable options permit this method fill
+ * in auth_ident field and return true, otherwise return false.
+ */
+static int
+authmethod_is_enabled(Authmethod *method)
+{
+	if (method == NULL)
+		return 0;
+	/* return false if options indicate this method is disabled */
+	if  (method->enabled == NULL || *method->enabled == 0)
+		return 0;
+	/* return false if batch mode is enabled but method needs interactive mode */
+	if  (method->batch_flag != NULL && *method->batch_flag != 0)
+		return 0;
+	return 1;
+}
+
+static Authmethod *
+authmethod_lookup(const char *name)
+{
+	Authmethod *method = NULL;
+	if (name != NULL)
+		for (method = authmethods; method->name != NULL; method++)
+			if (strcmp(name, method->name) == 0)
+				return method;
+	debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
+	return NULL;
+}
+
+/* XXX internal state */
+static Authmethod *current = NULL;
+static char *supported = NULL;
+static char *preferred = NULL;
+
+/*
+ * Given the authentication method list sent by the server, return the
+ * next method we should try.  If the server initially sends a nil list,
+ * use a built-in default list.
+ */
+static Authmethod *
+authmethod_get(char *authlist)
+{
+	char *name = NULL;
+	u_int next;
+
+	/* Use a suitable default if we're passed a nil list.  */
+	if (authlist == NULL || strlen(authlist) == 0)
+		authlist = options.preferred_authentications;
+
+	if (supported == NULL || strcmp(authlist, supported) != 0) {
+		debug3("start over, passed a different list %s", authlist);
+		free(supported);
+		supported = xstrdup(authlist);
+		preferred = options.preferred_authentications;
+		debug3("preferred %s", preferred);
+		current = NULL;
+	} else if (current != NULL && authmethod_is_enabled(current))
+		return current;
+
+	for (;;) {
+		if ((name = match_list(preferred, supported, &next)) == NULL) {
+			debug("No more authentication methods to try.");
+			current = NULL;
+			return NULL;
+		}
+		preferred += next;
+		debug3("authmethod_lookup %s", name);
+		debug3("remaining preferred: %s", preferred);
+		if ((current = authmethod_lookup(name)) != NULL &&
+		    authmethod_is_enabled(current)) {
+			debug3("authmethod_is_enabled %s", name);
+			debug("Next authentication method: %s", name);
+			free(name);
+			return current;
+		}
+		free(name);
+	}
+}
+
+static char *
+authmethods_get(void)
+{
+	Authmethod *method = NULL;
+	struct sshbuf *b;
+	char *list;
+	int r;
+
+	if ((b = sshbuf_new()) == NULL)
+		fatal("%s: sshbuf_new failed", __func__);
+	for (method = authmethods; method->name != NULL; method++) {
+		if (authmethod_is_enabled(method)) {
+			if ((r = sshbuf_putf(b, "%s%s",
+			    sshbuf_len(b) ? "," : "", method->name)) != 0)
+				fatal("%s: buffer error: %s",
+				    __func__, ssh_err(r));
+		}
+	}
+	if ((list = sshbuf_dup_string(b)) == NULL)
+		fatal("%s: sshbuf_dup_string failed", __func__);
+	sshbuf_free(b);
+	return list;
+}