/* * Copyright (c) 2000 Markus Friedl. 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" RCSID("$OpenBSD: sshconnect2.c,v 1.107 2002/07/01 19:48:46 markus Exp $"); RCSID("$FreeBSD: src/crypto/openssh/sshconnect2.c,v 1.1.1.2.2.7 2003/02/03 17:31:08 des Exp $"); RCSID("$DragonFly: src/crypto/openssh/Attic/sshconnect2.c,v 1.2 2003/06/17 04:24:36 dillon Exp $"); #include "ssh.h" #include "ssh2.h" #include "xmalloc.h" #include "buffer.h" #include "packet.h" #include "compat.h" #include "bufaux.h" #include "cipher.h" #include "kex.h" #include "myproposal.h" #include "sshconnect.h" #include "authfile.h" #include "dh.h" #include "authfd.h" #include "log.h" #include "readconf.h" #include "readpass.h" #include "match.h" #include "dispatch.h" #include "canohost.h" #include "msg.h" #include "pathnames.h" /* import */ extern char *client_version_string; extern char *server_version_string; extern Options options; /* * SSH2 key exchange */ u_char *session_id2 = NULL; int session_id2_len = 0; char *xxx_host; struct sockaddr *xxx_hostaddr; Kex *xxx_kex = NULL; static int verify_host_key_callback(Key *hostkey) { if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1) fatal("Host key verification failed."); return 0; } void ssh_kex2(char *host, struct sockaddr *hostaddr) { Kex *kex; xxx_host = host; xxx_hostaddr = hostaddr; if (options.ciphers == (char *)-1) { log("No valid ciphers for protocol version 2 given, using defaults."); options.ciphers = NULL; } if (options.ciphers != NULL) { myproposal[PROPOSAL_ENC_ALGS_CTOS] = myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; } myproposal[PROPOSAL_ENC_ALGS_CTOS] = compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); myproposal[PROPOSAL_ENC_ALGS_STOC] = compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); if (options.compression) { myproposal[PROPOSAL_COMP_ALGS_CTOS] = myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib,none"; } else { myproposal[PROPOSAL_COMP_ALGS_CTOS] = myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib"; } if (options.macs != NULL) { myproposal[PROPOSAL_MAC_ALGS_CTOS] = myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; } if (options.hostkeyalgorithms != NULL) myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = options.hostkeyalgorithms; /* start key exchange */ kex = kex_setup(myproposal); kex->client_version_string=client_version_string; kex->server_version_string=server_version_string; kex->verify_host_key=&verify_host_key_callback; xxx_kex = kex; dispatch_run(DISPATCH_BLOCK, &kex->done, kex); session_id2 = kex->session_id; session_id2_len = kex->session_id_len; #ifdef DEBUG_KEXDH /* send 1st encrypted/maced/compressed message */ packet_start(SSH2_MSG_IGNORE); packet_put_cstring("markus"); packet_send(); packet_write_wait(); #endif debug("done: ssh_kex2."); } /* * Authenticate user */ typedef struct Authctxt Authctxt; typedef struct Authmethod Authmethod; typedef int sign_cb_fn( Authctxt *authctxt, Key *key, u_char **sigp, u_int *lenp, u_char *data, u_int datalen); struct Authctxt { const char *server_user; const char *local_user; const char *host; const char *service; Authmethod *method; int success; char *authlist; /* pubkey */ Key *last_key; sign_cb_fn *last_key_sign; int last_key_hint; AuthenticationConnection *agent; /* hostbased */ Sensitive *sensitive; /* kbd-interactive */ int info_req_seen; }; struct Authmethod { char *name; /* string to compare against server's list */ int (*userauth)(Authctxt *authctxt); int *enabled; /* flag in option struct that enables method */ int *batch_flag; /* flag in option struct that disables method */ }; void input_userauth_success(int, u_int32_t, void *); void input_userauth_failure(int, u_int32_t, void *); void input_userauth_banner(int, u_int32_t, void *); void input_userauth_error(int, u_int32_t, void *); void input_userauth_info_req(int, u_int32_t, void *); void input_userauth_pk_ok(int, u_int32_t, void *); void input_userauth_passwd_changereq(int, u_int32_t, void *); int userauth_none(Authctxt *); int userauth_pubkey(Authctxt *); int userauth_passwd(Authctxt *); int userauth_kbdint(Authctxt *); int userauth_hostbased(Authctxt *); void userauth(Authctxt *, char *); static int sign_and_send_pubkey(Authctxt *, Key *, sign_cb_fn *); static void clear_auth_state(Authctxt *); static Authmethod *authmethod_get(char *authlist); static Authmethod *authmethod_lookup(const char *name); static char *authmethods_get(void); Authmethod authmethods[] = { {"hostbased", userauth_hostbased, &options.hostbased_authentication, NULL}, {"publickey", userauth_pubkey, &options.pubkey_authentication, NULL}, {"keyboard-interactive", userauth_kbdint, &options.kbd_interactive_authentication, &options.batch_mode}, {"password", userauth_passwd, &options.password_authentication, &options.batch_mode}, {"none", userauth_none, NULL, NULL}, {NULL, NULL, NULL, NULL} }; void ssh_userauth2(const char *local_user, const char *server_user, char *host, Sensitive *sensitive) { Authctxt authctxt; int type; if (options.challenge_response_authentication) options.kbd_interactive_authentication = 1; debug("send SSH2_MSG_SERVICE_REQUEST"); packet_start(SSH2_MSG_SERVICE_REQUEST); packet_put_cstring("ssh-userauth"); packet_send(); packet_write_wait(); type = packet_read(); if (type != SSH2_MSG_SERVICE_ACCEPT) { fatal("denied SSH2_MSG_SERVICE_ACCEPT: %d", type); } if (packet_remaining() > 0) { char *reply = packet_get_string(NULL); debug("service_accept: %s", reply); xfree(reply); } else { debug("buggy server: service_accept w/o service"); } packet_check_eom(); debug("got SSH2_MSG_SERVICE_ACCEPT"); if (options.preferred_authentications == NULL) options.preferred_authentications = authmethods_get(); /* setup authentication context */ memset(&authctxt, 0, sizeof(authctxt)); authctxt.agent = ssh_get_authentication_connection(); 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.sensitive = sensitive; authctxt.info_req_seen = 0; if (authctxt.method == NULL) fatal("ssh_userauth2: internal error: cannot send userauth none request"); /* initial userauth request */ userauth_none(&authctxt); dispatch_init(&input_userauth_error); dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */ if (authctxt.agent != NULL) ssh_close_authentication_connection(authctxt.agent); debug("ssh-userauth2 successful: method %s", authctxt.method->name); } void userauth(Authctxt *authctxt, char *authlist) { if (authlist == NULL) { authlist = authctxt->authlist; } else { if (authctxt->authlist) xfree(authctxt->authlist); authctxt->authlist = authlist; } for (;;) { Authmethod *method = authmethod_get(authlist); if (method == NULL) fatal("Permission denied (%s).", authlist); authctxt->method = method; if (method->userauth(authctxt) != 0) { debug2("we sent a %s packet, wait for reply", method->name); break; } else { debug2("we did not send a packet, disable method"); method->enabled = NULL; } } } void input_userauth_error(int type, u_int32_t seq, void *ctxt) { fatal("input_userauth_error: bad message during authentication: " "type %d", type); } void input_userauth_banner(int type, u_int32_t seq, void *ctxt) { char *msg, *lang; debug3("input_userauth_banner"); msg = packet_get_string(NULL); lang = packet_get_string(NULL); fprintf(stderr, "%s", msg); xfree(msg); xfree(lang); } void input_userauth_success(int type, u_int32_t seq, void *ctxt) { Authctxt *authctxt = ctxt; if (authctxt == NULL) fatal("input_userauth_success: no authentication context"); if (authctxt->authlist) xfree(authctxt->authlist); clear_auth_state(authctxt); authctxt->success = 1; /* break out */ } void input_userauth_failure(int type, u_int32_t seq, void *ctxt) { Authctxt *authctxt = ctxt; char *authlist = NULL; int partial; if (authctxt == NULL) fatal("input_userauth_failure: no authentication context"); authlist = packet_get_string(NULL); partial = packet_get_char(); packet_check_eom(); if (partial != 0) log("Authenticated with partial success."); debug("authentications that can continue: %s", authlist); clear_auth_state(authctxt); userauth(authctxt, authlist); } void input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt) { Authctxt *authctxt = ctxt; Key *key = NULL; Buffer b; int pktype, sent = 0; u_int alen, blen; char *pkalg, *fp; u_char *pkblob; if (authctxt == NULL) fatal("input_userauth_pk_ok: no authentication context"); if (datafellows & SSH_BUG_PKOK) { /* this is similar to SSH_BUG_PKAUTH */ debug2("input_userauth_pk_ok: SSH_BUG_PKOK"); pkblob = packet_get_string(&blen); buffer_init(&b); buffer_append(&b, pkblob, blen); pkalg = buffer_get_string(&b, &alen); buffer_free(&b); } else { pkalg = packet_get_string(&alen); pkblob = packet_get_string(&blen); } packet_check_eom(); debug("input_userauth_pk_ok: pkalg %s blen %u lastkey %p hint %d", pkalg, blen, authctxt->last_key, authctxt->last_key_hint); do { if (authctxt->last_key == NULL || authctxt->last_key_sign == NULL) { debug("no last key or no sign cb"); break; } if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) { debug("unknown pkalg %s", pkalg); break; } if ((key = key_from_blob(pkblob, blen)) == NULL) { debug("no key from blob. pkalg %s", pkalg); break; } if (key->type != pktype) { error("input_userauth_pk_ok: type mismatch " "for decoded key (received %d, expected %d)", key->type, pktype); break; } fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX); debug2("input_userauth_pk_ok: fp %s", fp); xfree(fp); if (!key_equal(key, authctxt->last_key)) { debug("key != last_key"); break; } sent = sign_and_send_pubkey(authctxt, key, authctxt->last_key_sign); } while (0); if (key != NULL) key_free(key); xfree(pkalg); xfree(pkblob); /* unregister */ clear_auth_state(authctxt); dispatch_set(SSH2_MSG_USERAUTH_PK_OK, NULL); /* try another method if we did not send a packet */ if (sent == 0) userauth(authctxt, NULL); } int userauth_none(Authctxt *authctxt) { /* initial userauth request */ packet_start(SSH2_MSG_USERAUTH_REQUEST); packet_put_cstring(authctxt->server_user); packet_put_cstring(authctxt->service); packet_put_cstring(authctxt->method->name); packet_send(); return 1; } int userauth_passwd(Authctxt *authctxt) { static int attempt = 0; char prompt[150]; char *password; if (attempt++ >= options.number_of_password_prompts) return 0; if (attempt != 1) error("Permission denied, please try again."); snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ", authctxt->server_user, authctxt->host); password = read_passphrase(prompt, 0); packet_start(SSH2_MSG_USERAUTH_REQUEST); packet_put_cstring(authctxt->server_user); packet_put_cstring(authctxt->service); packet_put_cstring(authctxt->method->name); packet_put_char(0); packet_put_cstring(password); memset(password, 0, strlen(password)); xfree(password); packet_add_padding(64); packet_send(); dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, &input_userauth_passwd_changereq); return 1; } /* * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST */ void input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt) { Authctxt *authctxt = ctxt; char *info, *lang, *password = NULL, *retype = NULL; char prompt[150]; debug2("input_userauth_passwd_changereq"); if (authctxt == NULL) fatal("input_userauth_passwd_changereq: " "no authentication context"); info = packet_get_string(NULL); lang = packet_get_string(NULL); if (strlen(info) > 0) log("%s", info); xfree(info); xfree(lang); packet_start(SSH2_MSG_USERAUTH_REQUEST); packet_put_cstring(authctxt->server_user); packet_put_cstring(authctxt->service); packet_put_cstring(authctxt->method->name); packet_put_char(1); /* additional info */ snprintf(prompt, sizeof(prompt), "Enter %.30s@%.128s's old password: ", authctxt->server_user, authctxt->host); password = read_passphrase(prompt, 0); packet_put_cstring(password); memset(password, 0, strlen(password)); xfree(password); password = NULL; while (password == NULL) { snprintf(prompt, sizeof(prompt), "Enter %.30s@%.128s's new password: ", authctxt->server_user, authctxt->host); password = read_passphrase(prompt, RP_ALLOW_EOF); if (password == NULL) { /* bail out */ return; } snprintf(prompt, sizeof(prompt), "Retype %.30s@%.128s's new password: ", authctxt->server_user, authctxt->host); retype = read_passphrase(prompt, 0); if (strcmp(password, retype) != 0) { memset(password, 0, strlen(password)); xfree(password); log("Mismatch; try again, EOF to quit."); password = NULL; } memset(retype, 0, strlen(retype)); xfree(retype); } packet_put_cstring(password); memset(password, 0, strlen(password)); xfree(password); packet_add_padding(64); packet_send(); dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, &input_userauth_passwd_changereq); } static void clear_auth_state(Authctxt *authctxt) { /* XXX clear authentication state */ dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, NULL); if (authctxt->last_key != NULL && authctxt->last_key_hint == -1) { debug3("clear_auth_state: key_free %p", authctxt->last_key); key_free(authctxt->last_key); } authctxt->last_key = NULL; authctxt->last_key_hint = -2; authctxt->last_key_sign = NULL; } static int sign_and_send_pubkey(Authctxt *authctxt, Key *k, sign_cb_fn *sign_callback) { Buffer b; u_char *blob, *signature; u_int bloblen, slen; int skip = 0; int ret = -1; int have_sig = 1; debug3("sign_and_send_pubkey"); if (key_to_blob(k, &blob, &bloblen) == 0) { /* we cannot handle this key */ debug3("sign_and_send_pubkey: cannot handle key"); return 0; } /* data to be signed */ buffer_init(&b); if (datafellows & SSH_OLD_SESSIONID) { buffer_append(&b, session_id2, session_id2_len); skip = session_id2_len; } else { buffer_put_string(&b, session_id2, session_id2_len); skip = buffer_len(&b); } buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); buffer_put_cstring(&b, authctxt->server_user); buffer_put_cstring(&b, datafellows & SSH_BUG_PKSERVICE ? "ssh-userauth" : authctxt->service); if (datafellows & SSH_BUG_PKAUTH) { buffer_put_char(&b, have_sig); } else { buffer_put_cstring(&b, authctxt->method->name); buffer_put_char(&b, have_sig); buffer_put_cstring(&b, key_ssh_name(k)); } buffer_put_string(&b, blob, bloblen); /* generate signature */ ret = (*sign_callback)(authctxt, k, &signature, &slen, buffer_ptr(&b), buffer_len(&b)); if (ret == -1) { xfree(blob); buffer_free(&b); return 0; } #ifdef DEBUG_PK buffer_dump(&b); #endif if (datafellows & SSH_BUG_PKSERVICE) { buffer_clear(&b); buffer_append(&b, session_id2, session_id2_len); skip = session_id2_len; buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); buffer_put_cstring(&b, authctxt->server_user); buffer_put_cstring(&b, authctxt->service); buffer_put_cstring(&b, authctxt->method->name); buffer_put_char(&b, have_sig); if (!(datafellows & SSH_BUG_PKAUTH)) buffer_put_cstring(&b, key_ssh_name(k)); buffer_put_string(&b, blob, bloblen); } xfree(blob); /* append signature */ buffer_put_string(&b, signature, slen); xfree(signature); /* skip session id and packet type */ if (buffer_len(&b) < skip + 1) fatal("userauth_pubkey: internal error"); buffer_consume(&b, skip + 1); /* put remaining data from buffer into packet */ packet_start(SSH2_MSG_USERAUTH_REQUEST); packet_put_raw(buffer_ptr(&b), buffer_len(&b)); buffer_free(&b); packet_send(); return 1; } static int send_pubkey_test(Authctxt *authctxt, Key *k, sign_cb_fn *sign_callback, int hint) { u_char *blob; u_int bloblen, have_sig = 0; debug3("send_pubkey_test"); if (key_to_blob(k, &blob, &bloblen) == 0) { /* we cannot handle this key */ debug3("send_pubkey_test: cannot handle key"); return 0; } /* register callback for USERAUTH_PK_OK message */ authctxt->last_key_sign = sign_callback; authctxt->last_key_hint = hint; authctxt->last_key = k; dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); packet_start(SSH2_MSG_USERAUTH_REQUEST); packet_put_cstring(authctxt->server_user); packet_put_cstring(authctxt->service); packet_put_cstring(authctxt->method->name); packet_put_char(have_sig); if (!(datafellows & SSH_BUG_PKAUTH)) packet_put_cstring(key_ssh_name(k)); packet_put_string(blob, bloblen); xfree(blob); packet_send(); return 1; } static Key * load_identity_file(char *filename) { Key *private; char prompt[300], *passphrase; int quit, i; struct stat st; if (stat(filename, &st) < 0) { debug3("no such identity: %s", filename); return NULL; } private = key_load_private_type(KEY_UNSPEC, filename, "", NULL); if (private == NULL) { if (options.batch_mode) return NULL; snprintf(prompt, sizeof prompt, "Enter passphrase for key '%.100s': ", filename); for (i = 0; i < options.number_of_password_prompts; i++) { passphrase = read_passphrase(prompt, 0); if (strcmp(passphrase, "") != 0) { private = key_load_private_type(KEY_UNSPEC, filename, passphrase, NULL); quit = 0; } else { debug2("no passphrase given, try next key"); quit = 1; } memset(passphrase, 0, strlen(passphrase)); xfree(passphrase); if (private != NULL || quit) break; debug2("bad passphrase given, try again..."); } } return private; } static int identity_sign_cb(Authctxt *authctxt, Key *key, u_char **sigp, u_int *lenp, u_char *data, u_int datalen) { Key *private; int idx, ret; idx = authctxt->last_key_hint; if (idx < 0) return -1; /* private key is stored in external hardware */ if (options.identity_keys[idx]->flags & KEY_FLAG_EXT) return key_sign(options.identity_keys[idx], sigp, lenp, data, datalen); private = load_identity_file(options.identity_files[idx]); if (private == NULL) return -1; ret = key_sign(private, sigp, lenp, data, datalen); key_free(private); return ret; } static int agent_sign_cb(Authctxt *authctxt, Key *key, u_char **sigp, u_int *lenp, u_char *data, u_int datalen) { return ssh_agent_sign(authctxt->agent, key, sigp, lenp, data, datalen); } static int key_sign_cb(Authctxt *authctxt, Key *key, u_char **sigp, u_int *lenp, u_char *data, u_int datalen) { return key_sign(key, sigp, lenp, data, datalen); } static int userauth_pubkey_agent(Authctxt *authctxt) { static int called = 0; int ret = 0; char *comment; Key *k; if (called == 0) { if (ssh_get_num_identities(authctxt->agent, 2) == 0) debug2("userauth_pubkey_agent: no keys at all"); called = 1; } k = ssh_get_next_identity(authctxt->agent, &comment, 2); if (k == NULL) { debug2("userauth_pubkey_agent: no more keys"); } else { debug("userauth_pubkey_agent: testing agent key %s", comment); xfree(comment); ret = send_pubkey_test(authctxt, k, agent_sign_cb, -1); if (ret == 0) key_free(k); } if (ret == 0) debug2("userauth_pubkey_agent: no message sent"); return ret; } int userauth_pubkey(Authctxt *authctxt) { static int idx = 0; int sent = 0; Key *key; char *filename; if (authctxt->agent != NULL) { do { sent = userauth_pubkey_agent(authctxt); } while (!sent && authctxt->agent->howmany > 0); } while (!sent && idx < options.num_identity_files) { key = options.identity_keys[idx]; filename = options.identity_files[idx]; if (key == NULL) { debug("try privkey: %s", filename); key = load_identity_file(filename); if (key != NULL) { sent = sign_and_send_pubkey(authctxt, key, key_sign_cb); key_free(key); } } else if (key->type != KEY_RSA1) { debug("try pubkey: %s", filename); sent = send_pubkey_test(authctxt, key, identity_sign_cb, idx); } idx++; } return sent; } /* * Send userauth request message specifying keyboard-interactive method. */ int userauth_kbdint(Authctxt *authctxt) { static int attempt = 0; if (attempt++ >= options.number_of_password_prompts) return 0; /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ if (attempt > 1 && !authctxt->info_req_seen) { debug3("userauth_kbdint: disable: no info_req_seen"); dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); return 0; } debug2("userauth_kbdint"); packet_start(SSH2_MSG_USERAUTH_REQUEST); packet_put_cstring(authctxt->server_user); packet_put_cstring(authctxt->service); packet_put_cstring(authctxt->method->name); packet_put_cstring(""); /* lang */ packet_put_cstring(options.kbd_interactive_devices ? options.kbd_interactive_devices : ""); packet_send(); dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); return 1; } /* * parse INFO_REQUEST, prompt user and send INFO_RESPONSE */ void input_userauth_info_req(int type, u_int32_t seq, void *ctxt) { Authctxt *authctxt = ctxt; char *name, *inst, *lang, *prompt, *response; u_int num_prompts, i; int echo = 0; debug2("input_userauth_info_req"); if (authctxt == NULL) fatal("input_userauth_info_req: no authentication context"); authctxt->info_req_seen = 1; name = packet_get_string(NULL); inst = packet_get_string(NULL); lang = packet_get_string(NULL); if (strlen(name) > 0) log("%s", name); if (strlen(inst) > 0) log("%s", inst); xfree(name); xfree(inst); xfree(lang); num_prompts = packet_get_int(); /* * Begin to build info response packet based on prompts requested. * We commit to providing the correct number of responses, so if * further on we run into a problem that prevents this, we have to * be sure and clean this up and send a correct error response. */ packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); packet_put_int(num_prompts); debug2("input_userauth_info_req: num_prompts %d", num_prompts); for (i = 0; i < num_prompts; i++) { prompt = packet_get_string(NULL); echo = packet_get_char(); response = read_passphrase(prompt, echo ? RP_ECHO : 0); packet_put_cstring(response); memset(response, 0, strlen(response)); xfree(response); xfree(prompt); } packet_check_eom(); /* done with parsing incoming message. */ packet_add_padding(64); packet_send(); } static int ssh_keysign(Key *key, u_char **sigp, u_int *lenp, u_char *data, u_int datalen) { Buffer b; struct stat st; pid_t pid; int to[2], from[2], status, version = 2; debug("ssh_keysign called"); if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) { error("ssh_keysign: no installed: %s", strerror(errno)); return -1; } if (fflush(stdout) != 0) error("ssh_keysign: fflush: %s", strerror(errno)); if (pipe(to) < 0) { error("ssh_keysign: pipe: %s", strerror(errno)); return -1; } if (pipe(from) < 0) { error("ssh_keysign: pipe: %s", strerror(errno)); return -1; } if ((pid = fork()) < 0) { error("ssh_keysign: fork: %s", strerror(errno)); return -1; } if (pid == 0) { seteuid(getuid()); setuid(getuid()); close(from[0]); if (dup2(from[1], STDOUT_FILENO) < 0) fatal("ssh_keysign: dup2: %s", strerror(errno)); close(to[1]); if (dup2(to[0], STDIN_FILENO) < 0) fatal("ssh_keysign: dup2: %s", strerror(errno)); close(from[1]); close(to[0]); execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0); fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN, strerror(errno)); } close(from[1]); close(to[0]); buffer_init(&b); buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */ buffer_put_string(&b, data, datalen); ssh_msg_send(to[1], version, &b); if (ssh_msg_recv(from[0], &b) < 0) { error("ssh_keysign: no reply"); buffer_clear(&b); return -1; } close(from[0]); close(to[1]); while (waitpid(pid, &status, 0) < 0) if (errno != EINTR) break; if (buffer_get_char(&b) != version) { error("ssh_keysign: bad version"); buffer_clear(&b); return -1; } *sigp = buffer_get_string(&b, lenp); buffer_clear(&b); return 0; } int userauth_hostbased(Authctxt *authctxt) { Key *private = NULL; Sensitive *sensitive = authctxt->sensitive; Buffer b; u_char *signature, *blob; char *chost, *pkalg, *p; const char *service; u_int blen, slen; int ok, i, len, found = 0; /* check for a useful key */ for (i = 0; i < sensitive->nkeys; i++) { private = sensitive->keys[i]; if (private && private->type != KEY_RSA1) { found = 1; /* we take and free the key */ sensitive->keys[i] = NULL; break; } } if (!found) { debug("userauth_hostbased: no more client hostkeys"); return 0; } if (key_to_blob(private, &blob, &blen) == 0) { key_free(private); return 0; } /* figure out a name for the client host */ p = get_local_name(packet_get_connection_in()); if (p == NULL) { error("userauth_hostbased: cannot get local ipaddr/name"); key_free(private); return 0; } len = strlen(p) + 2; chost = xmalloc(len); strlcpy(chost, p, len); strlcat(chost, ".", len); debug2("userauth_hostbased: chost %s", chost); service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : authctxt->service; pkalg = xstrdup(key_ssh_name(private)); buffer_init(&b); /* construct data */ buffer_put_string(&b, session_id2, session_id2_len); buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); buffer_put_cstring(&b, authctxt->server_user); buffer_put_cstring(&b, service); buffer_put_cstring(&b, authctxt->method->name); buffer_put_cstring(&b, pkalg); buffer_put_string(&b, blob, blen); buffer_put_cstring(&b, chost); buffer_put_cstring(&b, authctxt->local_user); #ifdef DEBUG_PK buffer_dump(&b); #endif if (sensitive->external_keysign) ok = ssh_keysign(private, &signature, &slen, buffer_ptr(&b), buffer_len(&b)); else ok = key_sign(private, &signature, &slen, buffer_ptr(&b), buffer_len(&b)); key_free(private); buffer_free(&b); if (ok != 0) { error("key_sign failed"); xfree(chost); xfree(pkalg); return 0; } packet_start(SSH2_MSG_USERAUTH_REQUEST); packet_put_cstring(authctxt->server_user); packet_put_cstring(authctxt->service); packet_put_cstring(authctxt->method->name); packet_put_cstring(pkalg); packet_put_string(blob, blen); packet_put_cstring(chost); packet_put_cstring(authctxt->local_user); packet_put_string(signature, slen); memset(signature, 's', slen); xfree(signature); xfree(chost); xfree(pkalg); packet_send(); return 1; } /* 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); if (supported != NULL) xfree(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 auth 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 auth method to try is %s", name); return current; } } } static char * authmethods_get(void) { Authmethod *method = NULL; Buffer b; char *list; buffer_init(&b); for (method = authmethods; method->name != NULL; method++) { if (authmethod_is_enabled(method)) { if (buffer_len(&b) > 0) buffer_append(&b, ",", 1); buffer_append(&b, method->name, strlen(method->name)); } } buffer_append(&b, "\0", 1); list = xstrdup(buffer_ptr(&b)); buffer_free(&b); return list; }