mld6query(8): Rename mld6.c -> mld6query.c

[dragonfly.git] / crypto / openssh / sshconnect2.c

/* $OpenBSD: sshconnect2.c,v 1.266 2017/08/27 00:38:41 dtucker 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 <stdarg.h>
#include <stdio.h>
#include <string.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 "buffer.h"
#include "packet.h"
#include "compat.h"
#include "cipher.h"
#include "key.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"

#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;
}

static char *
order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port)
{
        char *oavail, *avail, *first, *last, *alg, *hostname, *ret;
        size_t maxlen;
        struct hostkeys *hostkeys;
        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]);

        oavail = avail = xstrdup(KEX_DEFAULT_PK_ALG);
        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 (lookup_key_in_hostkeys_by_type(hostkeys,
                    sshkey_type_plain(ktype), NULL))
                        ALG_APPEND(first, alg);
                else
                        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);

        free(first);
        free(last);
        free(hostname);
        free(oavail);
        free_hostkeys(hostkeys);

        return ret;
}

void
ssh_kex2(char *host, struct sockaddr *hostaddr, u_short port)
{
        char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT };
        char *s;
        struct kex *kex;
        int r;

        xxx_host = host;
        xxx_hostaddr = hostaddr;

        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] = options.compression ?
            "zlib@openssh.com,zlib,none" : "none,zlib@openssh.com,zlib";
        myproposal[PROPOSAL_MAC_ALGS_CTOS] =
            myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
        if (options.hostkeyalgorithms != NULL) {
                if (kex_assemble_names(KEX_DEFAULT_PK_ALG,
                    &options.hostkeyalgorithms) != 0)
                        fatal("%s: kex_assemble_namelist", __func__);
                myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
                    compat_pkalg_proposal(options.hostkeyalgorithms);
        } else {
                /* Enforce default */
                options.hostkeyalgorithms = xstrdup(KEX_DEFAULT_PK_ALG);
                /* Prefer algorithms that we already have keys for */
                myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
                    compat_pkalg_proposal(
                    order_hostkeyalgs(host, hostaddr, port));
        }

        if (options.rekey_limit || options.rekey_interval)
                packet_set_rekey_limits(options.rekey_limit,
                    options.rekey_interval);

        /* start key exchange */
        if ((r = kex_setup(active_state, myproposal)) != 0)
                fatal("kex_setup: %s", ssh_err(r));
        kex = active_state->kex;
#ifdef WITH_OPENSSL
        kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
        kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
        kex->kex[KEX_DH_GRP14_SHA256] = kexdh_client;
        kex->kex[KEX_DH_GRP16_SHA512] = kexdh_client;
        kex->kex[KEX_DH_GRP18_SHA512] = kexdh_client;
        kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
        kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
# ifdef OPENSSL_HAS_ECC
        kex->kex[KEX_ECDH_SHA2] = kexecdh_client;
# endif
#endif
        kex->kex[KEX_C25519_SHA256] = kexc25519_client;
        kex->client_version_string=client_version_string;
        kex->server_version_string=server_version_string;
        kex->verify_host_key=&verify_host_key_callback;

        ssh_dispatch_run_fatal(active_state, DISPATCH_BLOCK, &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(kex->my, myproposal)) != 0)
                fatal("kex_prop2buf: %s", ssh_err(r));

        session_id2 = kex->session_id;
        session_id2_len = kex->session_id_len;

#ifdef DEBUG_KEXDH
        /* send 1st encrypted/maced/compressed message */
        packet_start(SSH2_MSG_IGNORE);
        packet_put_cstring("markus");
        packet_send();
        packet_write_wait();
#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;
        int attempt;
        /* pubkey */
        struct idlist keys;
        int agent_fd;
        /* hostbased */
        Sensitive *sensitive;
        char *oktypes, *ktypes;
        const char *active_ktype;
        /* kbd-interactive */
        int info_req_seen;
        /* generic */
        void *methoddata;
};

struct cauthmethod {
        char    *name;          /* string to compare against server's list */
        int     (*userauth)(Authctxt *authctxt);
        void    (*cleanup)(Authctxt *authctxt);
        int     *enabled;       /* flag in option struct that enables method */
        int     *batch_flag;    /* flag in option struct that disables method */
};

int     input_userauth_service_accept(int, u_int32_t, struct ssh *);
int     input_userauth_ext_info(int, u_int32_t, struct ssh *);
int     input_userauth_success(int, u_int32_t, struct ssh *);
int     input_userauth_success_unexpected(int, u_int32_t, struct ssh *);
int     input_userauth_failure(int, u_int32_t, struct ssh *);
int     input_userauth_banner(int, u_int32_t, struct ssh *);
int     input_userauth_error(int, u_int32_t, struct ssh *);
int     input_userauth_info_req(int, u_int32_t, struct ssh *);
int     input_userauth_pk_ok(int, u_int32_t, struct ssh *);
int     input_userauth_passwd_changereq(int, u_int32_t, struct ssh *);

int     userauth_none(Authctxt *);
int     userauth_pubkey(Authctxt *);
int     userauth_passwd(Authctxt *);
int     userauth_kbdint(Authctxt *);
int     userauth_hostbased(Authctxt *);

#ifdef GSSAPI
int     userauth_gssapi(Authctxt *authctxt);
int     input_gssapi_response(int type, u_int32_t, struct ssh *);
int     input_gssapi_token(int type, u_int32_t, struct ssh *);
int     input_gssapi_hash(int type, u_int32_t, struct ssh *);
int     input_gssapi_error(int, u_int32_t, struct ssh *);
int     input_gssapi_errtok(int, u_int32_t, struct ssh *);
#endif

void    userauth(Authctxt *, char *);

static int sign_and_send_pubkey(Authctxt *, Identity *);
static void pubkey_prepare(Authctxt *);
static void pubkey_cleanup(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,
                NULL,
                &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(const char *local_user, const char *server_user, char *host,
    Sensitive *sensitive)
{
        struct ssh *ssh = active_state;
        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));
        pubkey_prepare(&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.agent_fd = -1;
        if (authctxt.method == NULL)
                fatal("ssh_userauth2: internal error: cannot send userauth none request");

        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 */
        ssh->authctxt = NULL;

        pubkey_cleanup(&authctxt);
        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 */
int
input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh)
{
        Authctxt *authctxt = ssh->authctxt;
        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(authctxt);

        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 */
int
input_userauth_ext_info(int type, u_int32_t seqnr, struct ssh *ssh)
{
        return kex_input_ext_info(type, seqnr, ssh);
}

void
userauth(Authctxt *authctxt, char *authlist)
{
        if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
                authctxt->method->cleanup(authctxt);

        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 */
                dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN,
                    SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);

                /* and try new method */
                if (method->userauth(authctxt) != 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 */
int
input_userauth_error(int type, u_int32_t seq, struct ssh *ssh)
{
        fatal("input_userauth_error: bad message during authentication: "
            "type %d", type);
        return 0;
}

/* ARGSUSED */
int
input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh)
{
        char *msg, *lang;
        u_int len;

        debug3("%s", __func__);
        msg = packet_get_string(&len);
        lang = packet_get_string(NULL);
        if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO)
                fmprintf(stderr, "%s", msg);
        free(msg);
        free(lang);
        return 0;
}

/* ARGSUSED */
int
input_userauth_success(int type, u_int32_t seq, struct ssh *ssh)
{
        Authctxt *authctxt = ssh->authctxt;

        if (authctxt == NULL)
                fatal("input_userauth_success: no authentication context");
        free(authctxt->authlist);
        authctxt->authlist = NULL;
        if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
                authctxt->method->cleanup(authctxt);
        free(authctxt->methoddata);
        authctxt->methoddata = NULL;
        authctxt->success = 1;                  /* break out */
        return 0;
}

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;
}

/* ARGSUSED */
int
input_userauth_failure(int type, u_int32_t seq, struct ssh *ssh)
{
        Authctxt *authctxt = ssh->authctxt;
        char *authlist = NULL;
        int partial;

        if (authctxt == NULL)
                fatal("input_userauth_failure: no authentication context");

        authlist = packet_get_string(NULL);
        partial = packet_get_char();
        packet_check_eom();

        if (partial != 0) {
                verbose("Authenticated with partial success.");
                /* reset state */
                pubkey_reset(authctxt);
        }
        debug("Authentications that can continue: %s", authlist);

        userauth(authctxt, authlist);
        return 0;
}

/* ARGSUSED */
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;
        Buffer b;
        int pktype, sent = 0;
        u_int alen, blen;
        char *pkalg, *fp;
        u_char *pkblob;

        if (authctxt == NULL)
                fatal("input_userauth_pk_ok: no authentication context");
        if (datafellows & SSH_BUG_PKOK) {
                /* this is similar to SSH_BUG_PKAUTH */
                debug2("input_userauth_pk_ok: SSH_BUG_PKOK");
                pkblob = packet_get_string(&blen);
                buffer_init(&b);
                buffer_append(&b, pkblob, blen);
                pkalg = buffer_get_string(&b, &alen);
                buffer_free(&b);
        } else {
                pkalg = packet_get_string(&alen);
                pkblob = packet_get_string(&blen);
        }
        packet_check_eom();

        debug("Server accepts key: pkalg %s blen %u", pkalg, blen);

        if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) {
                debug("unknown pkalg %s", pkalg);
                goto done;
        }
        if ((key = key_from_blob(pkblob, blen)) == NULL) {
                debug("no key from blob. pkalg %s", pkalg);
                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;
        }
        if ((fp = sshkey_fingerprint(key, options.fingerprint_hash,
            SSH_FP_DEFAULT)) == NULL)
                goto done;
        debug2("input_userauth_pk_ok: fp %s", fp);
        free(fp);

        /*
         * 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 (key_equal(key, id->key)) {
                        sent = sign_and_send_pubkey(authctxt, id);
                        break;
                }
        }
done:
        if (key != NULL)
                key_free(key);
        free(pkalg);
        free(pkblob);

        /* try another method if we did not send a packet */
        if (sent == 0)
                userauth(authctxt, NULL);
        return 0;
}

#ifdef GSSAPI
int
userauth_gssapi(Authctxt *authctxt)
{
        Gssctxt *gssctxt = NULL;
        static gss_OID_set gss_supported = NULL;
        static u_int mech = 0;
        OM_uint32 min;
        int ok = 0;

        /* Try one GSSAPI method at a time, rather than sending them all at
         * once. */

        if (gss_supported == NULL)
                gss_indicate_mechs(&min, &gss_supported);

        /* Check to see if the mechanism is usable before we offer it */
        while (mech < gss_supported->count && !ok) {
                /* My DER encoding requires length<128 */
                if (gss_supported->elements[mech].length < 128 &&
                    ssh_gssapi_check_mechanism(&gssctxt, 
                    &gss_supported->elements[mech], authctxt->host)) {
                        ok = 1; /* Mechanism works */
                } else {
                        mech++;
                }
        }

        if (!ok)
                return 0;

        authctxt->methoddata=(void *)gssctxt;

        packet_start(SSH2_MSG_USERAUTH_REQUEST);
        packet_put_cstring(authctxt->server_user);
        packet_put_cstring(authctxt->service);
        packet_put_cstring(authctxt->method->name);

        packet_put_int(1);

        packet_put_int((gss_supported->elements[mech].length) + 2);
        packet_put_char(SSH_GSS_OIDTYPE);
        packet_put_char(gss_supported->elements[mech].length);
        packet_put_raw(gss_supported->elements[mech].elements,
            gss_supported->elements[mech].length);

        packet_send();

        dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
        dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
        dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
        dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);

        mech++; /* Move along to next candidate */

        return 1;
}

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;
        Buffer b;

        status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
            recv_tok, &send_tok, &flags);

        if (send_tok.length > 0) {
                if (GSS_ERROR(status))
                        packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
                else
                        packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);

                packet_put_string(send_tok.value, send_tok.length);
                packet_send();
                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)) {
                        packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE);
                        packet_send();
                } else {
                        ssh_gssapi_buildmic(&b, authctxt->server_user,
                            authctxt->service, "gssapi-with-mic");

                        gssbuf.value = buffer_ptr(&b);
                        gssbuf.length = buffer_len(&b);

                        status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);

                        if (!GSS_ERROR(status)) {
                                packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC);
                                packet_put_string(mic.value, mic.length);

                                packet_send();
                        }

                        buffer_free(&b);
                        gss_release_buffer(&ms, &mic);
                }
        }

        return status;
}

/* ARGSUSED */
int
input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh)
{
        Authctxt *authctxt = ssh->authctxt;
        Gssctxt *gssctxt;
        int oidlen;
        char *oidv;

        if (authctxt == NULL)
                fatal("input_gssapi_response: no authentication context");
        gssctxt = authctxt->methoddata;

        /* Setup our OID */
        oidv = packet_get_string(&oidlen);

        if (oidlen <= 2 ||
            oidv[0] != SSH_GSS_OIDTYPE ||
            oidv[1] != oidlen - 2) {
                free(oidv);
                debug("Badly encoded mechanism OID received");
                userauth(authctxt, NULL);
                return 0;
        }

        if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2))
                fatal("Server returned different OID than expected");

        packet_check_eom();

        free(oidv);

        if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) {
                /* Start again with next method on list */
                debug("Trying to start again");
                userauth(authctxt, NULL);
                return 0;
        }
        return 0;
}

/* ARGSUSED */
int
input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh)
{
        Authctxt *authctxt = ssh->authctxt;
        gss_buffer_desc recv_tok;
        OM_uint32 status;
        u_int slen;

        if (authctxt == NULL)
                fatal("input_gssapi_response: no authentication context");

        recv_tok.value = packet_get_string(&slen);
        recv_tok.length = slen; /* safe typecast */

        packet_check_eom();

        status = process_gssapi_token(ssh, &recv_tok);

        free(recv_tok.value);

        if (GSS_ERROR(status)) {
                /* Start again with the next method in the list */
                userauth(authctxt, NULL);
                return 0;
        }
        return 0;
}

/* ARGSUSED */
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_int len;

        if (authctxt == NULL)
                fatal("input_gssapi_response: no authentication context");
        gssctxt = authctxt->methoddata;

        recv_tok.value = packet_get_string(&len);
        recv_tok.length = len;

        packet_check_eom();

        /* Stick it into GSSAPI and see what it says */
        (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
            &recv_tok, &send_tok, NULL);

        free(recv_tok.value);
        gss_release_buffer(&ms, &send_tok);

        /* Server will be returning a failed packet after this one */
        return 0;
}

/* ARGSUSED */
int
input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh)
{
        char *msg;
        char *lang;

        /* maj */(void)packet_get_int();
        /* min */(void)packet_get_int();
        msg=packet_get_string(NULL);
        lang=packet_get_string(NULL);

        packet_check_eom();

        debug("Server GSSAPI Error:\n%s", msg);
        free(msg);
        free(lang);
        return 0;
}
#endif /* GSSAPI */

int
userauth_none(Authctxt *authctxt)
{
        /* initial userauth request */
        packet_start(SSH2_MSG_USERAUTH_REQUEST);
        packet_put_cstring(authctxt->server_user);
        packet_put_cstring(authctxt->service);
        packet_put_cstring(authctxt->method->name);
        packet_send();
        return 1;
}

int
userauth_passwd(Authctxt *authctxt)
{
        static int attempt = 0;
        char prompt[256];
        char *password;
        const char *host = options.host_key_alias ?  options.host_key_alias :
            authctxt->host;

        if (attempt++ >= options.number_of_password_prompts)
                return 0;

        if (attempt != 1)
                error("Permission denied, please try again.");

        snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ",
            authctxt->server_user, host);
        password = read_passphrase(prompt, 0);
        packet_start(SSH2_MSG_USERAUTH_REQUEST);
        packet_put_cstring(authctxt->server_user);
        packet_put_cstring(authctxt->service);
        packet_put_cstring(authctxt->method->name);
        packet_put_char(0);
        packet_put_cstring(password);
        explicit_bzero(password, strlen(password));
        free(password);
        packet_add_padding(64);
        packet_send();

        dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
            &input_userauth_passwd_changereq);

        return 1;
}

/*
 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
 */
/* ARGSUSED */
int
input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh)
{
        Authctxt *authctxt = ssh->authctxt;
        char *info, *lang, *password = NULL, *retype = NULL;
        char prompt[256];
        const char *host;

        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;

        info = packet_get_string(NULL);
        lang = packet_get_string(NULL);
        if (strlen(info) > 0)
                logit("%s", info);
        free(info);
        free(lang);
        packet_start(SSH2_MSG_USERAUTH_REQUEST);
        packet_put_cstring(authctxt->server_user);
        packet_put_cstring(authctxt->service);
        packet_put_cstring(authctxt->method->name);
        packet_put_char(1);                     /* additional info */
        snprintf(prompt, sizeof(prompt),
            "Enter %.30s@%.128s's old password: ",
            authctxt->server_user, host);
        password = read_passphrase(prompt, 0);
        packet_put_cstring(password);
        explicit_bzero(password, strlen(password));
        free(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 */
                        return 0;
                }
                snprintf(prompt, sizeof(prompt),
                    "Retype %.30s@%.128s's new password: ",
                    authctxt->server_user, host);
                retype = read_passphrase(prompt, 0);
                if (strcmp(password, retype) != 0) {
                        explicit_bzero(password, strlen(password));
                        free(password);
                        logit("Mismatch; try again, EOF to quit.");
                        password = NULL;
                }
                explicit_bzero(retype, strlen(retype));
                free(retype);
        }
        packet_put_cstring(password);
        explicit_bzero(password, strlen(password));
        free(password);
        packet_add_padding(64);
        packet_send();

        dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
            &input_userauth_passwd_changereq);
        return 0;
}

static const char *
key_sign_encode(const struct sshkey *key)
{
        struct ssh *ssh = active_state;

        if (key->type == KEY_RSA) {
                switch (ssh->kex->rsa_sha2) {
                case 256:
                        return "rsa-sha2-256";
                case 512:
                        return "rsa-sha2-512";
                }
        }
        return key_ssh_name(key);
}

static int
identity_sign(struct identity *id, u_char **sigp, size_t *lenp,
    const u_char *data, size_t datalen, u_int compat)
{
        struct sshkey *prv;
        int ret;

        /* 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, key_sign_encode(id->key), 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)))
                return (sshkey_sign(id->key, sigp, lenp, data, datalen,
                    key_sign_encode(id->key), compat));

        /* 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);
                return SSH_ERR_KEY_NOT_FOUND;
        }
        ret = sshkey_sign(prv, sigp, lenp, data, datalen,
            key_sign_encode(prv), compat);
        sshkey_free(prv);
        return (ret);
}

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(Authctxt *authctxt, Identity *id)
{
        Buffer b;
        Identity *private_id;
        u_char *blob, *signature;
        size_t slen;
        u_int bloblen, skip = 0;
        int matched, ret = -1, have_sig = 1;
        char *fp;

        if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash,
            SSH_FP_DEFAULT)) == NULL)
                return 0;
        debug3("%s: %s %s", __func__, key_type(id->key), fp);
        free(fp);

        if (key_to_blob(id->key, &blob, &bloblen) == 0) {
                /* we cannot handle this key */
                debug3("sign_and_send_pubkey: cannot handle key");
                return 0;
        }
        /* data to be signed */
        buffer_init(&b);
        if (datafellows & SSH_OLD_SESSIONID) {
                buffer_append(&b, session_id2, session_id2_len);
                skip = session_id2_len;
        } else {
                buffer_put_string(&b, session_id2, session_id2_len);
                skip = buffer_len(&b);
        }
        buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
        buffer_put_cstring(&b, authctxt->server_user);
        buffer_put_cstring(&b,
            datafellows & SSH_BUG_PKSERVICE ?
            "ssh-userauth" :
            authctxt->service);
        if (datafellows & SSH_BUG_PKAUTH) {
                buffer_put_char(&b, have_sig);
        } else {
                buffer_put_cstring(&b, authctxt->method->name);
                buffer_put_char(&b, have_sig);
                buffer_put_cstring(&b, key_sign_encode(id->key));
        }
        buffer_put_string(&b, blob, bloblen);

        /*
         * 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.
         */
        if (key_is_cert(id->key)) {
                matched = 0;
                TAILQ_FOREACH(private_id, &authctxt->keys, next) {
                        if (sshkey_equal_public(id->key, private_id->key) &&
                            id->key->type != private_id->key->type) {
                                id = private_id;
                                matched = 1;
                                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 (!matched && !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)) {
                                        id = private_id;
                                        matched = 1;
                                        break;
                                }
                        }
                }
                if (matched) {
                        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);
                }
        }

        /* generate signature */
        ret = identity_sign(id, &signature, &slen,
            buffer_ptr(&b), buffer_len(&b), datafellows);
        if (ret != 0) {
                if (ret != SSH_ERR_KEY_NOT_FOUND)
                        error("%s: signing failed: %s", __func__, ssh_err(ret));
                free(blob);
                buffer_free(&b);
                return 0;
        }
#ifdef DEBUG_PK
        buffer_dump(&b);
#endif
        if (datafellows & SSH_BUG_PKSERVICE) {
                buffer_clear(&b);
                buffer_append(&b, session_id2, session_id2_len);
                skip = session_id2_len;
                buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
                buffer_put_cstring(&b, authctxt->server_user);
                buffer_put_cstring(&b, authctxt->service);
                buffer_put_cstring(&b, authctxt->method->name);
                buffer_put_char(&b, have_sig);
                if (!(datafellows & SSH_BUG_PKAUTH))
                        buffer_put_cstring(&b, key_ssh_name(id->key));
                buffer_put_string(&b, blob, bloblen);
        }
        free(blob);

        /* append signature */
        buffer_put_string(&b, signature, slen);
        free(signature);

        /* skip session id and packet type */
        if (buffer_len(&b) < skip + 1)
                fatal("userauth_pubkey: internal error");
        buffer_consume(&b, skip + 1);

        /* put remaining data from buffer into packet */
        packet_start(SSH2_MSG_USERAUTH_REQUEST);
        packet_put_raw(buffer_ptr(&b), buffer_len(&b));
        buffer_free(&b);
        packet_send();

        return 1;
}

static int
send_pubkey_test(Authctxt *authctxt, Identity *id)
{
        u_char *blob;
        u_int bloblen, have_sig = 0;

        debug3("send_pubkey_test");

        if (key_to_blob(id->key, &blob, &bloblen) == 0) {
                /* we cannot handle this key */
                debug3("send_pubkey_test: cannot handle key");
                return 0;
        }
        /* register callback for USERAUTH_PK_OK message */
        dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);

        packet_start(SSH2_MSG_USERAUTH_REQUEST);
        packet_put_cstring(authctxt->server_user);
        packet_put_cstring(authctxt->service);
        packet_put_cstring(authctxt->method->name);
        packet_put_char(have_sig);
        if (!(datafellows & SSH_BUG_PKAUTH))
                packet_put_cstring(key_sign_encode(id->key));
        packet_put_string(blob, bloblen);
        free(blob);
        packet_send();
        return 1;
}

static struct sshkey *
load_identity_file(Identity *id)
{
        struct sshkey *private = NULL;
        char prompt[300], *passphrase, *comment;
        int r, perm_ok = 0, quit = 0, i;
        struct stat st;

        if (stat(id->filename, &st) < 0) {
                (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, &perm_ok))) {
                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 (!quit && private != NULL && id->agent_fd == -1 &&
                    !(id->key && id->isprivate))
                        maybe_add_key_to_agent(id->filename, private, comment,
                            passphrase);
                if (i > 0) {
                        explicit_bzero(passphrase, strlen(passphrase));
                        free(passphrase);
                }
                free(comment);
                if (private != NULL || quit)
                        break;
        }
        return private;
}

/*
 * 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;

        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)
                        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 (!key_is_cert(key) || key->cert == NULL ||
                    key->cert->type != SSH2_CERT_TYPE_USER)
                        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 */
                for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) {
                        TAILQ_REMOVE(&agent, id, next);
                        TAILQ_INSERT_TAIL(preferred, id, 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);
                        explicit_bzero(id, sizeof(*id));
                        free(id);
                }
        }
        /* append remaining keys from the config file */
        for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) {
                TAILQ_REMOVE(&files, id, next);
                TAILQ_INSERT_TAIL(preferred, id, next);
        }
        /* finally, filter by PubkeyAcceptedKeyTypes */
        TAILQ_FOREACH_SAFE(id, preferred, next, id2) {
                if (id->key != NULL &&
                    match_pattern_list(sshkey_ssh_name(id->key),
                    options.pubkey_key_types, 0) != 1) {
                        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;
                }
                debug2("key: %s (%p)%s%s", id->filename, id->key,
                    id->userprovided ? ", explicit" : "",
                    id->agent_fd != -1 ? ", agent" : "");
        }
}

static void
pubkey_cleanup(Authctxt *authctxt)
{
        Identity *id;

        if (authctxt->agent_fd != -1)
                ssh_close_authentication_socket(authctxt->agent_fd);
        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 (key_type_plain(id->key->type) == KEY_RSA &&
            (datafellows & SSH_BUG_RSASIGMD5) != 0) {
                debug("Skipped %s key %s for RSA/MD5 server",
                    key_type(id->key), id->filename);
                return (0);
        }
        return 1;
}

int
userauth_pubkey(Authctxt *authctxt)
{
        Identity *id;
        int sent = 0;
        char *fp;

        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)) {
                                if ((fp = sshkey_fingerprint(id->key,
                                    options.fingerprint_hash,
                                    SSH_FP_DEFAULT)) == NULL) {
                                        error("%s: sshkey_fingerprint failed",
                                            __func__);
                                        return 0;
                                }
                                debug("Offering public key: %s %s %s",
                                    sshkey_type(id->key), fp, id->filename);
                                free(fp);
                                sent = send_pubkey_test(authctxt, 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(
                                            authctxt, id);
                                }
                                key_free(id->key);
                                id->key = NULL;
                                id->isprivate = 0;
                        }
                }
                if (sent)
                        return (sent);
        }
        return (0);
}

/*
 * Send userauth request message specifying keyboard-interactive method.
 */
int
userauth_kbdint(Authctxt *authctxt)
{
        static int attempt = 0;

        if (attempt++ >= options.number_of_password_prompts)
                return 0;
        /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
        if (attempt > 1 && !authctxt->info_req_seen) {
                debug3("userauth_kbdint: disable: no info_req_seen");
                dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
                return 0;
        }

        debug2("userauth_kbdint");
        packet_start(SSH2_MSG_USERAUTH_REQUEST);
        packet_put_cstring(authctxt->server_user);
        packet_put_cstring(authctxt->service);
        packet_put_cstring(authctxt->method->name);
        packet_put_cstring("");                                 /* lang */
        packet_put_cstring(options.kbd_interactive_devices ?
            options.kbd_interactive_devices : "");
        packet_send();

        dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
        return 1;
}

/*
 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
 */
int
input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh)
{
        Authctxt *authctxt = ssh->authctxt;
        char *name, *inst, *lang, *prompt, *response;
        u_int num_prompts, i;
        int echo = 0;

        debug2("input_userauth_info_req");

        if (authctxt == NULL)
                fatal("input_userauth_info_req: no authentication context");

        authctxt->info_req_seen = 1;

        name = packet_get_string(NULL);
        inst = packet_get_string(NULL);
        lang = packet_get_string(NULL);
        if (strlen(name) > 0)
                logit("%s", name);
        if (strlen(inst) > 0)
                logit("%s", inst);
        free(name);
        free(inst);
        free(lang);

        num_prompts = packet_get_int();
        /*
         * 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.
         */
        packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
        packet_put_int(num_prompts);

        debug2("input_userauth_info_req: num_prompts %d", num_prompts);
        for (i = 0; i < num_prompts; i++) {
                prompt = packet_get_string(NULL);
                echo = packet_get_char();

                response = read_passphrase(prompt, echo ? RP_ECHO : 0);

                packet_put_cstring(response);
                explicit_bzero(response, strlen(response));
                free(response);
                free(prompt);
        }
        packet_check_eom(); /* done with parsing incoming message. */

        packet_add_padding(64);
        packet_send();
        return 0;
}

static int
ssh_keysign(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 i, r, to[2], from[2], status, sock = packet_get_connection_in();
        u_char rversion = 0, version = 2;
        void (*osigchld)(int);

        *sigp = NULL;
        *lenp = 0;

        if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) {
                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) < 0) {
                error("%s: pipe: %s", __func__, strerror(errno));
                return -1;
        }
        if (pipe(from) < 0) {
                error("%s: pipe: %s", __func__, strerror(errno));
                return -1;
        }
        if ((pid = fork()) < 0) {
                error("%s: fork: %s", __func__, strerror(errno));
                return -1;
        }
        osigchld = signal(SIGCHLD, SIG_DFL);
        if (pid == 0) {
                /* keep the socket on exec */
                fcntl(sock, F_SETFD, 0);
                permanently_drop_suid(getuid());
                close(from[0]);
                if (dup2(from[1], STDOUT_FILENO) < 0)
                        fatal("%s: dup2: %s", __func__, strerror(errno));
                close(to[1]);
                if (dup2(to[0], STDIN_FILENO) < 0)
                        fatal("%s: dup2: %s", __func__, strerror(errno));
                close(from[1]);
                close(to[0]);
                /* Close everything but stdio and the socket */
                for (i = STDERR_FILENO + 1; i < sock; i++)
                        close(i);
                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]);

        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) < 0) {
                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:
                signal(SIGCHLD, osigchld);
                sshbuf_free(b);
                return -1;
        }
        signal(SIGCHLD, osigchld);
        sshbuf_free(b);

        return 0;
}

int
userauth_hostbased(Authctxt *authctxt)
{
        struct ssh *ssh = active_state;
        struct sshkey *private = NULL;
        struct sshbuf *b = NULL;
        const char *service;
        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 */
        if ((lname = get_local_name(packet_get_connection_in())) == 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);

        service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
            authctxt->service;

        /* 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, service)) != 0 ||
            (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 ||
            (r = sshbuf_put_cstring(b, key_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 (authctxt->sensitive->external_keysign)
                r = ssh_keysign(private, &sig, &siglen,
                    sshbuf_ptr(b), sshbuf_len(b));
        else if ((r = sshkey_sign(private, &sig, &siglen,
            sshbuf_ptr(b), sshbuf_len(b), NULL, datafellows)) != 0)
                debug("%s: sshkey_sign: %s", __func__, ssh_err(r));
        if (r != 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, key_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) {
                explicit_bzero(sig, siglen);
                free(sig);
        }
        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;
        Buffer b;
        char *list;

        buffer_init(&b);
        for (method = authmethods; method->name != NULL; method++) {
                if (authmethod_is_enabled(method)) {
                        if (buffer_len(&b) > 0)
                                buffer_append(&b, ",", 1);
                        buffer_append(&b, method->name, strlen(method->name));
                }
        }
        if ((list = sshbuf_dup_string(&b)) == NULL)
                fatal("%s: sshbuf_dup_string failed", __func__);
        buffer_free(&b);
        return list;
}