Edit
IABSD.fr/src/usr.bin/ssh/sshconnect2.c
djm
- usr.bin/ssh/sshconnect2.c
-
/* $OpenBSD: sshconnect2.c,v 1.351 2021/07/23 05:24:02 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 <sys/types.h> #include <sys/socket.h> #include <sys/wait.h> #include <sys/queue.h> #include <sys/stat.h> #include <errno.h> #include <fcntl.h> #include <limits.h> #include <netdb.h> #include <stdio.h> #include <string.h> #include <stdarg.h> #include <signal.h> #include <pwd.h> #include <unistd.h> #include <vis.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) { 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; 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] = compat_kex_proposal(ssh, s); myproposal[PROPOSAL_ENC_ALGS_CTOS] = compat_cipher_proposal(ssh, options.ciphers); myproposal[PROPOSAL_ENC_ALGS_STOC] = 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] = compat_pkalg_proposal(ssh, order_hostkeyalgs(host, hostaddr, port, cinfo)); } else { /* Use specified HostkeyAlgorithms exactly */ myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = 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; ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client; #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 } /* * Authenticate user */ typedef struct cauthctxt Authctxt; typedef struct cauthmethod Authmethod; typedef struct identity Identity; typedef struct idlist Idlist; struct identity { TAILQ_ENTRY(identity) next; int agent_fd; /* >=0 if agent supports key */ struct sshkey *key; /* public/private key */ char *filename; /* comment for agent-only keys */ int tried; int isprivate; /* key points to the private key */ int userprovided; }; TAILQ_HEAD(idlist, identity); struct cauthctxt { const char *server_user; const char *local_user; const char *host; const char *service; struct cauthmethod *method; sig_atomic_t success; char *authlist; #ifdef GSSAPI /* gssapi */ gss_OID_set gss_supported_mechs; u_int mech_tried; #endif /* pubkey */ struct idlist keys; int agent_fd; /* hostbased */ Sensitive *sensitive; char *oktypes, *ktypes; const char *active_ktype; /* kbd-interactive */ int info_req_seen; int attempt_kbdint; /* password */ int attempt_passwd; /* generic */ void *methoddata; }; struct cauthmethod { char *name; /* string to compare against server's list */ int (*userauth)(struct ssh *ssh); void (*cleanup)(struct ssh *ssh); int *enabled; /* flag in option struct that enables method */ int *batch_flag; /* flag in option struct that disables method */ }; static int input_userauth_service_accept(int, u_int32_t, struct ssh *); static int input_userauth_ext_info(int, u_int32_t, struct ssh *); static int input_userauth_success(int, u_int32_t, struct ssh *); static int input_userauth_failure(int, u_int32_t, struct ssh *); static int input_userauth_banner(int, u_int32_t, struct ssh *); static int input_userauth_error(int, u_int32_t, struct ssh *); static int input_userauth_info_req(int, u_int32_t, struct ssh *); static int input_userauth_pk_ok(int, u_int32_t, struct ssh *); static int input_userauth_passwd_changereq(int, u_int32_t, struct ssh *); static int userauth_none(struct ssh *); static int userauth_pubkey(struct ssh *); static int userauth_passwd(struct ssh *); static int userauth_kbdint(struct ssh *); static int userauth_hostbased(struct ssh *); #ifdef GSSAPI static int userauth_gssapi(struct ssh *); static void userauth_gssapi_cleanup(struct ssh *); static int input_gssapi_response(int type, u_int32_t, struct ssh *); static int input_gssapi_token(int type, u_int32_t, struct ssh *); static int input_gssapi_error(int, u_int32_t, struct ssh *); static int input_gssapi_errtok(int, u_int32_t, struct ssh *); #endif void userauth(struct ssh *, char *); static void pubkey_cleanup(struct ssh *); static int sign_and_send_pubkey(struct ssh *ssh, Identity *); static void pubkey_prepare(Authctxt *); static void pubkey_reset(Authctxt *); static struct sshkey *load_identity_file(Identity *); static Authmethod *authmethod_get(char *authlist); static Authmethod *authmethod_lookup(const char *name); static char *authmethods_get(void); Authmethod authmethods[] = { #ifdef GSSAPI {"gssapi-with-mic", userauth_gssapi, userauth_gssapi_cleanup, &options.gss_authentication, NULL}, #endif {"hostbased", userauth_hostbased, NULL, &options.hostbased_authentication, NULL}, {"publickey", userauth_pubkey, NULL, &options.pubkey_authentication, NULL}, {"keyboard-interactive", userauth_kbdint, NULL, &options.kbd_interactive_authentication, &options.batch_mode}, {"password", userauth_passwd, NULL, &options.password_authentication, &options.batch_mode}, {"none", userauth_none, NULL, NULL, NULL}, {NULL, NULL, NULL, NULL, NULL} }; void ssh_userauth2(struct ssh *ssh, const char *local_user, const char *server_user, char *host, Sensitive *sensitive) { Authctxt authctxt; int r; if (options.preferred_authentications == NULL) options.preferred_authentications = authmethods_get(); /* setup authentication context */ memset(&authctxt, 0, sizeof(authctxt)); authctxt.server_user = server_user; authctxt.local_user = local_user; authctxt.host = host; authctxt.service = "ssh-connection"; /* service name */ authctxt.success = 0; authctxt.method = authmethod_lookup("none"); authctxt.authlist = NULL; authctxt.methoddata = NULL; authctxt.sensitive = sensitive; authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL; authctxt.info_req_seen = 0; authctxt.attempt_kbdint = 0; authctxt.attempt_passwd = 0; #if GSSAPI authctxt.gss_supported_mechs = NULL; authctxt.mech_tried = 0; #endif authctxt.agent_fd = -1; pubkey_prepare(&authctxt); if (authctxt.method == NULL) { fatal_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 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; } 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; if (sshkey_is_sk(sign_key)) { if ((sign_key->sk_flags & SSH_SK_USER_VERIFICATION_REQD)) { retry_pin: xasprintf(&prompt, "Enter PIN for %s key %s: ", sshkey_type(sign_key), id->filename); pin = read_passphrase(prompt, 0); } if ((sign_key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) { /* XXX should batch mode just skip these? */ if ((fp = sshkey_fingerprint(sign_key, options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) fatal_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 (pin == NULL && !retried && sshkey_is_sk(sign_key) && r == SSH_ERR_KEY_WRONG_PASSPHRASE) { notify_complete(notifier, NULL); notifier = NULL; 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) { const char *suffixes[] = { ".pub", "-cert.pub", NULL }; size_t len = strlen(id->filename), plen = strlen(private_id->filename); size_t i, slen; if (strcmp(id->filename, private_id->filename) == 0) return 1; for (i = 0; suffixes[i]; i++) { slen = strlen(suffixes[i]); if (len > slen && plen == len - slen && strcmp(id->filename + (len - slen), suffixes[i]) == 0 && memcmp(id->filename, private_id->filename, plen) == 0) return 1; } return 0; } static int sign_and_send_pubkey(struct ssh *ssh, Identity *id) { Authctxt *authctxt = (Authctxt *)ssh->authctxt; struct sshbuf *b = NULL; Identity *private_id, *sign_id = NULL; u_char *signature = NULL; size_t slen = 0, skip = 0; int r, fallback_sigtype, sent = 0; char *alg = NULL, *fp = NULL; const char *loc = ""; if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) return 0; debug3_f("%s %s", 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, authctxt->method->name)) != 0 || (r = sshbuf_put_u8(b, 1)) != 0 || (r = sshbuf_put_cstring(b, alg)) != 0 || (r = sshkey_puts(id->key, b)) != 0) { fatal_fr(r, "assemble signed data"); } /* 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 && 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; } /* * try keys in the following order: * 1. certificates listed in the config file * 2. other input certificates * 3. agent keys that are found in the config file * 4. other agent keys * 5. keys that are only listed in the config file */ static void pubkey_prepare(Authctxt *authctxt) { struct identity *id, *id2, *tmp; struct idlist agent, files, *preferred; struct sshkey *key; int agent_fd = -1, i, r, found; size_t j; struct ssh_identitylist *idlist; char *ident; TAILQ_INIT(&agent); /* keys from the agent */ TAILQ_INIT(&files); /* keys from the config file */ preferred = &authctxt->keys; TAILQ_INIT(preferred); /* preferred order of keys */ /* list of keys stored in the filesystem and PKCS#11 */ for (i = 0; i < options.num_identity_files; i++) { key = options.identity_keys[i]; if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER) { debug_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 = ssh_get_authentication_socket(&agent_fd)) != 0) { if (r != SSH_ERR_AGENT_NOT_PRESENT) debug_fr(r, "ssh_get_authentication_socket"); } else if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) { if (r != SSH_ERR_AGENT_NO_IDENTITIES) debug_fr(r, "ssh_fetch_identitylist"); close(agent_fd); } else { for (j = 0; j < idlist->nkeys; j++) { found = 0; TAILQ_FOREACH(id, &files, next) { /* * agent keys from the config file are * preferred */ if (sshkey_equal(idlist->keys[j], id->key)) { TAILQ_REMOVE(&files, id, next); TAILQ_INSERT_TAIL(preferred, id, next); id->agent_fd = agent_fd; found = 1; break; } } if (!found && !options.identities_only) { id = xcalloc(1, sizeof(*id)); /* XXX "steals" key/comment from idlist */ id->key = idlist->keys[j]; id->filename = idlist->comments[j]; idlist->keys[j] = NULL; idlist->comments[j] = NULL; id->agent_fd = agent_fd; TAILQ_INSERT_TAIL(&agent, id, next); } } ssh_free_identitylist(idlist); /* append remaining agent keys */ TAILQ_CONCAT(preferred, &agent, next); authctxt->agent_fd = agent_fd; } /* Prefer PKCS11 keys that are explicitly listed */ TAILQ_FOREACH_SAFE(id, &files, next, tmp) { if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0) continue; found = 0; TAILQ_FOREACH(id2, &files, next) { if (id2->key == NULL || (id2->key->flags & SSHKEY_FLAG_EXT) != 0) continue; if (sshkey_equal(id->key, id2->key)) { TAILQ_REMOVE(&files, id, next); TAILQ_INSERT_TAIL(preferred, id, next); found = 1; break; } } /* If IdentitiesOnly set and key not found then don't use it */ if (!found && options.identities_only) { TAILQ_REMOVE(&files, id, next); freezero(id, sizeof(*id)); } } /* append remaining keys from the config file */ TAILQ_CONCAT(preferred, &files, next); /* finally, filter by 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 (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_f("sshkey_fingerprint failed"); goto out; } debug_f("trying hostkey %s %s", sshkey_ssh_name(private), fp); /* figure out a name for the client host */ lname = get_local_name(ssh_packet_get_connection_in(ssh)); if (lname == NULL) { error_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; }