diff options
Diffstat (limited to 'sshconnect2.c')
| -rw-r--r-- | sshconnect2.c | 2396 |
1 files changed, 2396 insertions, 0 deletions
diff --git a/sshconnect2.c b/sshconnect2.c new file mode 100644 index 0000000..58fe98d --- /dev/null +++ b/sshconnect2.c @@ -0,0 +1,2396 @@ +/* $OpenBSD: sshconnect2.c,v 1.361 2022/09/17 10:33:18 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 <limits.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 + */ + +static char *xxx_host; +static struct sockaddr *xxx_hostaddr; +static const struct ssh_conn_info *xxx_conn_info; + +static int +verify_host_key_callback(struct sshkey *hostkey, struct ssh *ssh) +{ + int r; + + if ((r = sshkey_check_rsa_length(hostkey, + options.required_rsa_size)) != 0) + fatal_r(r, "Bad server host key"); + if (verify_host_key(xxx_host, xxx_hostaddr, hostkey, + xxx_conn_info) == -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, + const struct ssh_conn_info *cinfo) +{ + 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], 0); + for (i = 0; i < options.num_system_hostfiles; i++) { + load_hostkeys(hostkeys, hostname, + options.system_hostfiles[i], 0); + } + if (options.known_hosts_command != NULL) { + load_hostkeys_command(hostkeys, options.known_hosts_command, + "ORDER", cinfo, NULL, host); + } + /* + * 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)), + sshkey_ecdsa_nid_from_name(best), NULL)) { + debug3_f("have matching best-preference key type %s, " + "using HostkeyAlgorithms verbatim", 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_f("unknown alg %s", 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), + sshkey_ecdsa_nid_from_name(alg), 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_f("prefer hostkeyalgs: %s", first); + else + debug3_f("no algorithms matched; accept original"); + 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, + const struct ssh_conn_info *cinfo) +{ + char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT }; + char *s, *all_key; + char *prop_kex = NULL, *prop_enc = NULL, *prop_hostkey = NULL; + int r, use_known_hosts_order = 0; + + xxx_host = host; + xxx_hostaddr = hostaddr; + xxx_conn_info = cinfo; + + /* + * 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 ((r = kex_assemble_names(&options.hostkeyalgorithms, + kex_default_pk_alg(), all_key)) != 0) + fatal_fr(r, "kex_assemble_namelist"); + free(all_key); + + if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL) + fatal_f("kex_names_cat"); + myproposal[PROPOSAL_KEX_ALGS] = prop_kex = compat_kex_proposal(ssh, s); + myproposal[PROPOSAL_ENC_ALGS_CTOS] = + myproposal[PROPOSAL_ENC_ALGS_STOC] = prop_enc = + compat_cipher_proposal(ssh, 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] = prop_hostkey = + compat_pkalg_proposal(ssh, + order_hostkeyalgs(host, hostaddr, port, cinfo)); + } else { + /* Use specified HostkeyAlgorithms exactly */ + myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = prop_hostkey = + compat_pkalg_proposal(ssh, 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_r(r, "kex_setup"); +#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_SNTRUP761X25519_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(ssh, options.kex_algorithms); + if ((r = kex_prop2buf(ssh->kex->my, myproposal)) != 0) + fatal_r(r, "kex_prop2buf"); + +#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_fr(r, "send packet"); +#endif + /* Free only parts of proposal that were dynamically allocated here. */ + free(prop_kex); + free(prop_enc); + free(prop_hostkey); +} + +/* + * 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(struct ssh *, 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.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(ssh, &authctxt); + if (authctxt.method == NULL) { + fatal_f("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_fr(r, "send packet"); + + 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."); + if (ssh_packet_connection_is_on_socket(ssh)) { + verbose("Authenticated to %s ([%s]:%d) using \"%s\".", host, + ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), + authctxt.method->name); + } else { + verbose("Authenticated to %s (via proxy) using \"%s\".", host, + 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_f("bad message during authentication: type %d", 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_f("entering"); + 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_f("no authentication context"); + 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_f("no authentication context"); + + 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 using \"%s\" with partial success.", + authctxt->method->name); + /* 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_f("server sent unknown pkalg %s", pkalg); + goto done; + } + if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) { + debug_r(r, "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; + } + + /* + * 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_f("server replied with unknown key: %s %s", + 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_fr(r, "send packet"); + + 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_fr(r, "send %u packet", type); + + 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_fr(r, "send completion"); + } else { + struct sshbuf *b; + + if ((b = sshbuf_new()) == NULL) + fatal_f("sshbuf_new failed"); + ssh_gssapi_buildmic(b, authctxt->server_user, + authctxt->service, "gssapi-with-mic", + ssh->kex->session_id); + + if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL) + fatal_f("sshbuf_mutable_ptr failed"); + 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_fr(r, "send MIC"); + } + + 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_fr(r, "send packet"); + 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_fr(r, "send packet"); + + 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; + const char *server_sig_algs; + + /* + * 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 && (ssh->compat & SSH_BUG_SIGTYPE))) { + /* Filter base key signature alg against our configuration */ + return match_list(sshkey_ssh_name(key), + options.pubkey_accepted_algos, NULL); + } + + /* + * Workaround OpenSSH 7.4 bug: this version supports RSA/SHA-2 but + * fails to advertise it via SSH2_MSG_EXT_INFO. + */ + server_sig_algs = ssh->kex->server_sig_algs; + if (key->type == KEY_RSA && (ssh->compat & SSH_BUG_SIGTYPE74)) + server_sig_algs = "rsa-sha2-256,rsa-sha2-512"; + + /* + * For RSA keys/certs, since these might have a different sig type: + * find the first entry in PubkeyAcceptedAlgorithms of the right type + * that also appears in the supported signature algorithms list from + * the server. + */ + oallowed = allowed = xstrdup(options.pubkey_accepted_algos); + while ((cp = strsep(&allowed, ",")) != NULL) { + if (sshkey_type_from_name(cp) != key->type) + continue; + tmp = match_list(sshkey_sigalg_by_name(cp), + 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 is_agent = 0, retried = 0, 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; + is_agent = 1; + } 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_f("private key %s contents do not match public", + id->filename); + r = SSH_ERR_KEY_NOT_FOUND; + goto out; + } + sign_key = prv; + } + retry_pin: + /* Prompt for touch for non-agent FIDO keys that request UP */ + if (!is_agent && sshkey_is_sk(sign_key) && + (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_f("fingerprint failed"); + 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_fr(r, "sshkey_sign"); + if (!retried && pin == NULL && !is_agent && + sshkey_is_sk(sign_key) && + r == SSH_ERR_KEY_WRONG_PASSPHRASE) { + notify_complete(notifier, NULL); + notifier = NULL; + xasprintf(&prompt, "Enter PIN for %s key %s: ", + sshkey_type(sign_key), id->filename); + pin = read_passphrase(prompt, 0); + retried = 1; + goto retry_pin; + } + 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_fr(r, "sshkey_check_sigtype"); + goto out; + } + /* success */ + r = 0; + out: + free(prompt); + if (pin != NULL) + freezero(pin, strlen(pin)); + notify_complete(notifier, r == 0 ? "User presence confirmed" : NULL); + sshkey_free(prv); + return r; +} + +static int +id_filename_matches(Identity *id, Identity *private_id) +{ + static const char * const 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 = "", *method = "publickey"; + int hostbound = 0; + + /* prefer host-bound pubkey signatures if supported by server */ + if ((ssh->kex->flags & KEX_HAS_PUBKEY_HOSTBOUND) != 0 && + (options.pubkey_authentication & SSH_PUBKEY_AUTH_HBOUND) != 0) { + hostbound = 1; + method = "publickey-hostbound-v00@openssh.com"; + } + + if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, + SSH_FP_DEFAULT)) == NULL) + return 0; + + debug3_f("using %s with %s %s", method, 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_f("using private key \"%s\"%s for " + "certificate", sign_id->filename, + sign_id->agent_fd != -1 ? " from agent" : ""); + } else { + debug_f("no separate private key for certificate " + "\"%s\"", 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_f("no mutual signature supported"); + goto out; + } + debug3_f("signing using %s %s", alg, fp); + + sshbuf_free(b); + if ((b = sshbuf_new()) == NULL) + fatal_f("sshbuf_new failed"); + if (ssh->compat & SSH_OLD_SESSIONID) { + if ((r = sshbuf_putb(b, ssh->kex->session_id)) != 0) + fatal_fr(r, "sshbuf_putb"); + } else { + if ((r = sshbuf_put_stringb(b, + ssh->kex->session_id)) != 0) + fatal_fr(r, "sshbuf_put_stringb"); + } + 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, method)) != 0 || + (r = sshbuf_put_u8(b, 1)) != 0 || + (r = sshbuf_put_cstring(b, alg)) != 0 || + (r = sshkey_puts(id->key, b)) != 0) { + fatal_fr(r, "assemble signed data"); + } + if (hostbound) { + if (ssh->kex->initial_hostkey == NULL) { + fatal_f("internal error: initial hostkey " + "not recorded"); + } + if ((r = sshkey_puts(ssh->kex->initial_hostkey, b)) != 0) + fatal_fr(r, "assemble %s hostkey", method); + } + /* generate signature */ + r = identity_sign(sign_id, &signature, &slen, + sshbuf_ptr(b), sshbuf_len(b), ssh->compat, 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_fr(r, "signing failed for %s \"%s\"%s", + sshkey_type(sign_id->key), sign_id->filename, + id->agent_fd != -1 ? " from agent" : ""); + goto out; + } + if (slen == 0 || signature == NULL) /* shouldn't happen */ + fatal_f("no signature"); + + /* append signature */ + if ((r = sshbuf_put_string(b, signature, slen)) != 0) + fatal_fr(r, "append signature"); + +#ifdef DEBUG_PK + sshbuf_dump(b, stderr); +#endif + /* skip session id and packet type */ + if ((r = sshbuf_consume(b, skip + 1)) != 0) + fatal_fr(r, "consume"); + + /* 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_fr(r, "enqueue request"); + + /* 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_f("no mutual signature algorithm"); + goto out; + } + + if ((r = sshkey_to_blob(id->key, &blob, &bloblen)) != 0) { + /* we cannot handle this key */ + debug3_f("cannot handle key"); + 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_fr(r, "send packet"); + 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) { + do_log2(id->userprovided ? + SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_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_r(r, "Load key \"%s\"", id->filename); + quit = 1; + break; + } + /* FALLTHROUGH */ + default: + error_r(r, "Load key \"%s\"", id->filename); + 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 && (r = sshkey_check_rsa_length(private, + options.required_rsa_size)) != 0) { + debug_fr(r, "Skipping key %s", 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_accepted_algos, 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_accepted_algos, 0) == 1) + return 1; + if (match_pattern_list("rsa-sha2-256", + options.pubkey_accepted_algos, 0) == 1) + return 1; + break; + case KEY_RSA_CERT: + if (match_pattern_list("rsa-sha2-512-cert-v01@openssh.com", + options.pubkey_accepted_algos, 0) == 1) + return 1; + if (match_pattern_list("rsa-sha2-256-cert-v01@openssh.com", + options.pubkey_accepted_algos, 0) == 1) + return 1; + break; + } + return 0; +} + +/* obtain a list of keys from the agent */ +static int +get_agent_identities(struct ssh *ssh, int *agent_fdp, + struct ssh_identitylist **idlistp) +{ + int r, agent_fd; + struct ssh_identitylist *idlist; + + if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) { + if (r != SSH_ERR_AGENT_NOT_PRESENT) + debug_fr(r, "ssh_get_authentication_socket"); + return r; + } + if ((r = ssh_agent_bind_hostkey(agent_fd, ssh->kex->initial_hostkey, + ssh->kex->session_id, ssh->kex->initial_sig, 0)) == 0) + debug_f("bound agent to hostkey"); + else + debug2_fr(r, "ssh_agent_bind_hostkey"); + + if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) { + debug_fr(r, "ssh_fetch_identitylist"); + close(agent_fd); + return r; + } + /* success */ + *agent_fdp = agent_fd; + *idlistp = idlist; + debug_f("agent returned %zu keys", idlist->nkeys); + 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(struct ssh *ssh, 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_f("ignoring certificate %s: not a user " + "certificate", options.identity_files[i]); + continue; + } + if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { + debug_f("ignoring authenticator-hosted key %s as no " + "SecurityKeyProvider has been specified", + 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_f("ignoring certificate %s: not a user " + "certificate", options.identity_files[i]); + continue; + } + if (key && sshkey_is_sk(key) && options.sk_provider == NULL) { + debug_f("ignoring authenticator-hosted key " + "certificate %s as no " + "SecurityKeyProvider has been specified", + 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 = get_agent_identities(ssh, &agent_fd, &idlist)) == 0) { + for (j = 0; j < idlist->nkeys; j++) { + if ((r = sshkey_check_rsa_length(idlist->keys[j], + options.required_rsa_size)) != 0) { + debug_fr(r, "ignoring %s agent key", + sshkey_ssh_name(idlist->keys[j])); + continue; + } + 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 PubkeyAcceptedAlgorithms */ + TAILQ_FOREACH_SAFE(id, preferred, next, id2) { + if (id->key != NULL && !key_type_allowed_by_config(id->key)) { + debug("Skipping %s key %s - " + "corresponding algo not in PubkeyAcceptedAlgorithms", + 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_f("done"); +} + +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(struct ssh *ssh, Identity *id) +{ + if (!id->key) + return (0); + if (sshkey_type_plain(id->key->type) == KEY_RSA && + (ssh->compat & 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(ssh, 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(ssh, 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_fr(r, "send packet"); + + 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 *display_prompt = NULL, *response = NULL; + u_char echo = 0; + u_int num_prompts, i; + int r; + + debug2_f("entering"); + + if (authctxt == NULL) + fatal_f("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_f("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; + if (asmprintf(&display_prompt, INT_MAX, NULL, "(%s@%s) %s", + authctxt->server_user, options.host_key_alias ? + options.host_key_alias : authctxt->host, prompt) == -1) + fatal_f("asmprintf failed"); + response = read_passphrase(display_prompt, echo ? RP_ECHO : 0); + if ((r = sshpkt_put_cstring(ssh, response)) != 0) + goto out; + freezero(response, strlen(response)); + free(prompt); + free(display_prompt); + display_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(display_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_f("not installed: %s", strerror(errno)); + return -1; + } + if (fflush(stdout) != 0) { + error_f("fflush: %s", strerror(errno)); + return -1; + } + if (pipe(to) == -1) { + error_f("pipe: %s", strerror(errno)); + return -1; + } + if (pipe(from) == -1) { + error_f("pipe: %s", strerror(errno)); + return -1; + } + if ((pid = fork()) == -1) { + error_f("fork: %s", strerror(errno)); + return -1; + } + osigchld = ssh_signal(SIGCHLD, SIG_DFL); + if (pid == 0) { + close(from[0]); + if (dup2(from[1], STDOUT_FILENO) == -1) + fatal_f("dup2: %s", strerror(errno)); + close(to[1]); + if (dup2(to[0], STDIN_FILENO) == -1) + fatal_f("dup2: %s", strerror(errno)); + close(from[1]); + close(to[0]); + + if (dup2(sock, STDERR_FILENO + 1) == -1) + fatal_f("dup2: %s", strerror(errno)); + sock = STDERR_FILENO + 1; + fcntl(sock, F_SETFD, 0); /* keep the socket on exec */ + closefrom(sock + 1); + + debug3_f("[child] pid=%ld, exec %s", + (long)getpid(), _PATH_SSH_KEY_SIGN); + execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL); + fatal_f("exec(%s): %s", _PATH_SSH_KEY_SIGN, + strerror(errno)); + } + close(from[1]); + close(to[0]); + sock = STDERR_FILENO + 1; + + if ((b = sshbuf_new()) == NULL) + fatal_f("sshbuf_new failed"); + /* send # of sock, data to be signed */ + if ((r = sshbuf_put_u32(b, sock)) != 0 || + (r = sshbuf_put_string(b, data, datalen)) != 0) + fatal_fr(r, "buffer error"); + if (ssh_msg_send(to[1], version, b) == -1) + fatal_f("couldn't send request"); + sshbuf_reset(b); + r = ssh_msg_recv(from[0], b); + close(from[0]); + close(to[1]); + if (r < 0) { + error_f("no reply"); + goto fail; + } + + errno = 0; + while (waitpid(pid, &status, 0) == -1) { + if (errno != EINTR) { + error_f("waitpid %ld: %s", (long)pid, strerror(errno)); + goto fail; + } + } + if (!WIFEXITED(status)) { + error_f("exited abnormally"); + goto fail; + } + if (WEXITSTATUS(status) != 0) { + error_f("exited with status %d", WEXITSTATUS(status)); + goto fail; + } + if ((r = sshbuf_get_u8(b, &rversion)) != 0) { + error_fr(r, "buffer error"); + goto fail; + } + if (rversion != version) { + error_f("bad version"); + goto fail; + } + if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) { + error_fr(r, "buffer error"); + 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_accepted_algos); + authctxt->ktypes = authctxt->oktypes; + } + + /* + * Work through each listed type pattern in HostbasedAcceptedAlgorithms, + * 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_f("trying key type %s", 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 (!sshkey_match_keyname_to_sigalgs( + sshkey_ssh_name(authctxt->sensitive->keys[i]), + authctxt->active_ktype)) + 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_f("sshkey_fingerprint failed"); + goto out; + } + debug_f("trying hostkey %s %s using sigalg %s", + sshkey_ssh_name(private), fp, authctxt->active_ktype); + + /* figure out a name for the client host */ + lname = get_local_name(ssh_packet_get_connection_in(ssh)); + if (lname == NULL) { + error_f("cannot get local ipaddr/name"); + goto out; + } + + /* XXX sshbuf_put_stringf? */ + xasprintf(&chost, "%s.", lname); + debug2_f("chost %s", chost); + + /* construct data */ + if ((b = sshbuf_new()) == NULL) { + error_f("sshbuf_new failed"); + goto out; + } + if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) { + error_fr(r, "sshkey_to_blob"); + goto out; + } + if ((r = sshbuf_put_stringb(b, ssh->kex->session_id)) != 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, authctxt->active_ktype)) != 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_fr(r, "buffer error"); + 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, authctxt->active_ktype)) != 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_fr(r, "packet error"); + 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_f("sshbuf_new failed"); + 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_fr(r, "buffer error"); + } + } + if ((list = sshbuf_dup_string(b)) == NULL) + fatal_f("sshbuf_dup_string failed"); + sshbuf_free(b); + return list; +} |