/* * Author: Tatu Ylonen * Copyright (c) 1995 Tatu Ylonen , Espoo, Finland * All rights reserved * Created: Sat Mar 18 22:15:47 1995 ylo * Code to connect to a remote host, and to perform the client side of the * login (authentication) dialog. * */ #include "includes.h" RCSID("$OpenBSD: sshconnect1.c,v 1.5 2000/08/19 21:34:44 markus Exp $"); #include #include #include #include #include "xmalloc.h" #include "rsa.h" #include "ssh.h" #include "buffer.h" #include "packet.h" #include "cipher.h" #include "mpaux.h" #include "uidswap.h" #include "readconf.h" #include "key.h" #include "authfd.h" #include "sshconnect.h" #include "authfile.h" /* Session id for the current session. */ unsigned char session_id[16]; unsigned int supported_authentications = 0; extern Options options; extern char *__progname; /* * Checks if the user has an authentication agent, and if so, tries to * authenticate using the agent. */ int try_agent_authentication() { int type; char *comment; AuthenticationConnection *auth; unsigned char response[16]; unsigned int i; int plen, clen; Key *key; BIGNUM *challenge; /* Get connection to the agent. */ auth = ssh_get_authentication_connection(); if (!auth) return 0; challenge = BN_new(); key = key_new(KEY_RSA); /* Loop through identities served by the agent. */ for (key = ssh_get_first_identity(auth, &comment, 1); key != NULL; key = ssh_get_next_identity(auth, &comment, 1)) { /* Try this identity. */ debug("Trying RSA authentication via agent with '%.100s'", comment); xfree(comment); /* Tell the server that we are willing to authenticate using this key. */ packet_start(SSH_CMSG_AUTH_RSA); packet_put_bignum(key->rsa->n); packet_send(); packet_write_wait(); /* Wait for server's response. */ type = packet_read(&plen); /* The server sends failure if it doesn\'t like our key or does not support RSA authentication. */ if (type == SSH_SMSG_FAILURE) { debug("Server refused our key."); key_free(key); continue; } /* Otherwise it should have sent a challenge. */ if (type != SSH_SMSG_AUTH_RSA_CHALLENGE) packet_disconnect("Protocol error during RSA authentication: %d", type); packet_get_bignum(challenge, &clen); packet_integrity_check(plen, clen, type); debug("Received RSA challenge from server."); /* Ask the agent to decrypt the challenge. */ if (!ssh_decrypt_challenge(auth, key, challenge, session_id, 1, response)) { /* * The agent failed to authenticate this identifier * although it advertised it supports this. Just * return a wrong value. */ log("Authentication agent failed to decrypt challenge."); memset(response, 0, sizeof(response)); } key_free(key); debug("Sending response to RSA challenge."); /* Send the decrypted challenge back to the server. */ packet_start(SSH_CMSG_AUTH_RSA_RESPONSE); for (i = 0; i < 16; i++) packet_put_char(response[i]); packet_send(); packet_write_wait(); /* Wait for response from the server. */ type = packet_read(&plen); /* The server returns success if it accepted the authentication. */ if (type == SSH_SMSG_SUCCESS) { BN_clear_free(challenge); debug("RSA authentication accepted by server."); return 1; } /* Otherwise it should return failure. */ if (type != SSH_SMSG_FAILURE) packet_disconnect("Protocol error waiting RSA auth response: %d", type); } BN_clear_free(challenge); debug("RSA authentication using agent refused."); return 0; } /* * Computes the proper response to a RSA challenge, and sends the response to * the server. */ void respond_to_rsa_challenge(BIGNUM * challenge, RSA * prv) { unsigned char buf[32], response[16]; MD5_CTX md; int i, len; /* Decrypt the challenge using the private key. */ rsa_private_decrypt(challenge, challenge, prv); /* Compute the response. */ /* The response is MD5 of decrypted challenge plus session id. */ len = BN_num_bytes(challenge); if (len <= 0 || len > sizeof(buf)) packet_disconnect("respond_to_rsa_challenge: bad challenge length %d", len); memset(buf, 0, sizeof(buf)); BN_bn2bin(challenge, buf + sizeof(buf) - len); MD5_Init(&md); MD5_Update(&md, buf, 32); MD5_Update(&md, session_id, 16); MD5_Final(response, &md); debug("Sending response to host key RSA challenge."); /* Send the response back to the server. */ packet_start(SSH_CMSG_AUTH_RSA_RESPONSE); for (i = 0; i < 16; i++) packet_put_char(response[i]); packet_send(); packet_write_wait(); memset(buf, 0, sizeof(buf)); memset(response, 0, sizeof(response)); memset(&md, 0, sizeof(md)); } /* * Checks if the user has authentication file, and if so, tries to authenticate * the user using it. */ int try_rsa_authentication(const char *authfile) { BIGNUM *challenge; Key *public; Key *private; char *passphrase, *comment; int type, i; int plen, clen; /* Try to load identification for the authentication key. */ public = key_new(KEY_RSA); if (!load_public_key(authfile, public, &comment)) { key_free(public); /* Could not load it. Fail. */ return 0; } debug("Trying RSA authentication with key '%.100s'", comment); /* Tell the server that we are willing to authenticate using this key. */ packet_start(SSH_CMSG_AUTH_RSA); packet_put_bignum(public->rsa->n); packet_send(); packet_write_wait(); /* We no longer need the public key. */ key_free(public); /* Wait for server's response. */ type = packet_read(&plen); /* * The server responds with failure if it doesn\'t like our key or * doesn\'t support RSA authentication. */ if (type == SSH_SMSG_FAILURE) { debug("Server refused our key."); xfree(comment); return 0; } /* Otherwise, the server should respond with a challenge. */ if (type != SSH_SMSG_AUTH_RSA_CHALLENGE) packet_disconnect("Protocol error during RSA authentication: %d", type); /* Get the challenge from the packet. */ challenge = BN_new(); packet_get_bignum(challenge, &clen); packet_integrity_check(plen, clen, type); debug("Received RSA challenge from server."); private = key_new(KEY_RSA); /* * Load the private key. Try first with empty passphrase; if it * fails, ask for a passphrase. */ if (!load_private_key(authfile, "", private, NULL)) { char buf[300]; snprintf(buf, sizeof buf, "Enter passphrase for RSA key '%.100s': ", comment); if (!options.batch_mode) passphrase = read_passphrase(buf, 0); else { debug("Will not query passphrase for %.100s in batch mode.", comment); passphrase = xstrdup(""); } /* Load the authentication file using the pasphrase. */ if (!load_private_key(authfile, passphrase, private, NULL)) { memset(passphrase, 0, strlen(passphrase)); xfree(passphrase); error("Bad passphrase."); /* Send a dummy response packet to avoid protocol error. */ packet_start(SSH_CMSG_AUTH_RSA_RESPONSE); for (i = 0; i < 16; i++) packet_put_char(0); packet_send(); packet_write_wait(); /* Expect the server to reject it... */ packet_read_expect(&plen, SSH_SMSG_FAILURE); xfree(comment); return 0; } /* Destroy the passphrase. */ memset(passphrase, 0, strlen(passphrase)); xfree(passphrase); } /* We no longer need the comment. */ xfree(comment); /* Compute and send a response to the challenge. */ respond_to_rsa_challenge(challenge, private->rsa); /* Destroy the private key. */ key_free(private); /* We no longer need the challenge. */ BN_clear_free(challenge); /* Wait for response from the server. */ type = packet_read(&plen); if (type == SSH_SMSG_SUCCESS) { debug("RSA authentication accepted by server."); return 1; } if (type != SSH_SMSG_FAILURE) packet_disconnect("Protocol error waiting RSA auth response: %d", type); debug("RSA authentication refused."); return 0; } /* * Tries to authenticate the user using combined rhosts or /etc/hosts.equiv * authentication and RSA host authentication. */ int try_rhosts_rsa_authentication(const char *local_user, RSA * host_key) { int type; BIGNUM *challenge; int plen, clen; debug("Trying rhosts or /etc/hosts.equiv with RSA host authentication."); /* Tell the server that we are willing to authenticate using this key. */ packet_start(SSH_CMSG_AUTH_RHOSTS_RSA); packet_put_string(local_user, strlen(local_user)); packet_put_int(BN_num_bits(host_key->n)); packet_put_bignum(host_key->e); packet_put_bignum(host_key->n); packet_send(); packet_write_wait(); /* Wait for server's response. */ type = packet_read(&plen); /* The server responds with failure if it doesn't admit our .rhosts authentication or doesn't know our host key. */ if (type == SSH_SMSG_FAILURE) { debug("Server refused our rhosts authentication or host key."); return 0; } /* Otherwise, the server should respond with a challenge. */ if (type != SSH_SMSG_AUTH_RSA_CHALLENGE) packet_disconnect("Protocol error during RSA authentication: %d", type); /* Get the challenge from the packet. */ challenge = BN_new(); packet_get_bignum(challenge, &clen); packet_integrity_check(plen, clen, type); debug("Received RSA challenge for host key from server."); /* Compute a response to the challenge. */ respond_to_rsa_challenge(challenge, host_key); /* We no longer need the challenge. */ BN_clear_free(challenge); /* Wait for response from the server. */ type = packet_read(&plen); if (type == SSH_SMSG_SUCCESS) { debug("Rhosts or /etc/hosts.equiv with RSA host authentication accepted by server."); return 1; } if (type != SSH_SMSG_FAILURE) packet_disconnect("Protocol error waiting RSA auth response: %d", type); debug("Rhosts or /etc/hosts.equiv with RSA host authentication refused."); return 0; } #ifdef KRB4 int try_kerberos_authentication() { KTEXT_ST auth; /* Kerberos data */ char *reply; char inst[INST_SZ]; char *realm; CREDENTIALS cred; int r, type, plen; socklen_t slen; Key_schedule schedule; u_long checksum, cksum; MSG_DAT msg_data; struct sockaddr_in local, foreign; struct stat st; /* Don't do anything if we don't have any tickets. */ if (stat(tkt_string(), &st) < 0) return 0; strncpy(inst, (char *) krb_get_phost(get_canonical_hostname()), INST_SZ); realm = (char *) krb_realmofhost(get_canonical_hostname()); if (!realm) { debug("Kerberos V4: no realm for %s", get_canonical_hostname()); return 0; } /* This can really be anything. */ checksum = (u_long) getpid(); r = krb_mk_req(&auth, KRB4_SERVICE_NAME, inst, realm, checksum); if (r != KSUCCESS) { debug("Kerberos V4 krb_mk_req failed: %s", krb_err_txt[r]); return 0; } /* Get session key to decrypt the server's reply with. */ r = krb_get_cred(KRB4_SERVICE_NAME, inst, realm, &cred); if (r != KSUCCESS) { debug("get_cred failed: %s", krb_err_txt[r]); return 0; } des_key_sched((des_cblock *) cred.session, schedule); /* Send authentication info to server. */ packet_start(SSH_CMSG_AUTH_KERBEROS); packet_put_string((char *) auth.dat, auth.length); packet_send(); packet_write_wait(); /* Zero the buffer. */ (void) memset(auth.dat, 0, MAX_KTXT_LEN); slen = sizeof(local); memset(&local, 0, sizeof(local)); if (getsockname(packet_get_connection_in(), (struct sockaddr *) & local, &slen) < 0) debug("getsockname failed: %s", strerror(errno)); slen = sizeof(foreign); memset(&foreign, 0, sizeof(foreign)); if (getpeername(packet_get_connection_in(), (struct sockaddr *) & foreign, &slen) < 0) { debug("getpeername failed: %s", strerror(errno)); fatal_cleanup(); } /* Get server reply. */ type = packet_read(&plen); switch (type) { case SSH_SMSG_FAILURE: /* Should really be SSH_SMSG_AUTH_KERBEROS_FAILURE */ debug("Kerberos V4 authentication failed."); return 0; break; case SSH_SMSG_AUTH_KERBEROS_RESPONSE: /* SSH_SMSG_AUTH_KERBEROS_SUCCESS */ debug("Kerberos V4 authentication accepted."); /* Get server's response. */ reply = packet_get_string((unsigned int *) &auth.length); memcpy(auth.dat, reply, auth.length); xfree(reply); packet_integrity_check(plen, 4 + auth.length, type); /* * If his response isn't properly encrypted with the session * key, and the decrypted checksum fails to match, he's * bogus. Bail out. */ r = krb_rd_priv(auth.dat, auth.length, schedule, &cred.session, &foreign, &local, &msg_data); if (r != KSUCCESS) { debug("Kerberos V4 krb_rd_priv failed: %s", krb_err_txt[r]); packet_disconnect("Kerberos V4 challenge failed!"); } /* Fetch the (incremented) checksum that we supplied in the request. */ (void) memcpy((char *) &cksum, (char *) msg_data.app_data, sizeof(cksum)); cksum = ntohl(cksum); /* If it matches, we're golden. */ if (cksum == checksum + 1) { debug("Kerberos V4 challenge successful."); return 1; } else packet_disconnect("Kerberos V4 challenge failed!"); break; default: packet_disconnect("Protocol error on Kerberos V4 response: %d", type); } return 0; } #endif /* KRB4 */ #ifdef AFS int send_kerberos_tgt() { CREDENTIALS *creds; char pname[ANAME_SZ], pinst[INST_SZ], prealm[REALM_SZ]; int r, type, plen; char buffer[8192]; struct stat st; /* Don't do anything if we don't have any tickets. */ if (stat(tkt_string(), &st) < 0) return 0; creds = xmalloc(sizeof(*creds)); if ((r = krb_get_tf_fullname(TKT_FILE, pname, pinst, prealm)) != KSUCCESS) { debug("Kerberos V4 tf_fullname failed: %s", krb_err_txt[r]); return 0; } if ((r = krb_get_cred("krbtgt", prealm, prealm, creds)) != GC_OK) { debug("Kerberos V4 get_cred failed: %s", krb_err_txt[r]); return 0; } if (time(0) > krb_life_to_time(creds->issue_date, creds->lifetime)) { debug("Kerberos V4 ticket expired: %s", TKT_FILE); return 0; } creds_to_radix(creds, (unsigned char *)buffer, sizeof buffer); xfree(creds); packet_start(SSH_CMSG_HAVE_KERBEROS_TGT); packet_put_string(buffer, strlen(buffer)); packet_send(); packet_write_wait(); type = packet_read(&plen); if (type == SSH_SMSG_FAILURE) debug("Kerberos TGT for realm %s rejected.", prealm); else if (type != SSH_SMSG_SUCCESS) packet_disconnect("Protocol error on Kerberos TGT response: %d", type); return 1; } void send_afs_tokens(void) { CREDENTIALS creds; struct ViceIoctl parms; struct ClearToken ct; int i, type, len, plen; char buf[2048], *p, *server_cell; char buffer[8192]; /* Move over ktc_GetToken, here's something leaner. */ for (i = 0; i < 100; i++) { /* just in case */ parms.in = (char *) &i; parms.in_size = sizeof(i); parms.out = buf; parms.out_size = sizeof(buf); if (k_pioctl(0, VIOCGETTOK, &parms, 0) != 0) break; p = buf; /* Get secret token. */ memcpy(&creds.ticket_st.length, p, sizeof(unsigned int)); if (creds.ticket_st.length > MAX_KTXT_LEN) break; p += sizeof(unsigned int); memcpy(creds.ticket_st.dat, p, creds.ticket_st.length); p += creds.ticket_st.length; /* Get clear token. */ memcpy(&len, p, sizeof(len)); if (len != sizeof(struct ClearToken)) break; p += sizeof(len); memcpy(&ct, p, len); p += len; p += sizeof(len); /* primary flag */ server_cell = p; /* Flesh out our credentials. */ strlcpy(creds.service, "afs", sizeof creds.service); creds.instance[0] = '\0'; strlcpy(creds.realm, server_cell, REALM_SZ); memcpy(creds.session, ct.HandShakeKey, DES_KEY_SZ); creds.issue_date = ct.BeginTimestamp; creds.lifetime = krb_time_to_life(creds.issue_date, ct.EndTimestamp); creds.kvno = ct.AuthHandle; snprintf(creds.pname, sizeof(creds.pname), "AFS ID %d", ct.ViceId); creds.pinst[0] = '\0'; /* Encode token, ship it off. */ if (creds_to_radix(&creds, (unsigned char*) buffer, sizeof buffer) <= 0) break; packet_start(SSH_CMSG_HAVE_AFS_TOKEN); packet_put_string(buffer, strlen(buffer)); packet_send(); packet_write_wait(); /* Roger, Roger. Clearance, Clarence. What's your vector, Victor? */ type = packet_read(&plen); if (type == SSH_SMSG_FAILURE) debug("AFS token for cell %s rejected.", server_cell); else if (type != SSH_SMSG_SUCCESS) packet_disconnect("Protocol error on AFS token response: %d", type); } } #endif /* AFS */ /* * Tries to authenticate with any string-based challenge/response system. * Note that the client code is not tied to s/key or TIS. */ int try_skey_authentication() { int type, i; int payload_len; unsigned int clen; char *challenge, *response; debug("Doing skey authentication."); /* request a challenge */ packet_start(SSH_CMSG_AUTH_TIS); packet_send(); packet_write_wait(); type = packet_read(&payload_len); if (type != SSH_SMSG_FAILURE && type != SSH_SMSG_AUTH_TIS_CHALLENGE) { packet_disconnect("Protocol error: got %d in response " "to skey-auth", type); } if (type != SSH_SMSG_AUTH_TIS_CHALLENGE) { debug("No challenge for skey authentication."); return 0; } challenge = packet_get_string(&clen); packet_integrity_check(payload_len, (4 + clen), type); if (options.cipher == SSH_CIPHER_NONE) log("WARNING: Encryption is disabled! " "Reponse will be transmitted in clear text."); fprintf(stderr, "%s\n", challenge); xfree(challenge); fflush(stderr); for (i = 0; i < options.number_of_password_prompts; i++) { if (i != 0) error("Permission denied, please try again."); response = read_passphrase("Response: ", 0); packet_start(SSH_CMSG_AUTH_TIS_RESPONSE); packet_put_string(response, strlen(response)); memset(response, 0, strlen(response)); xfree(response); packet_send(); packet_write_wait(); type = packet_read(&payload_len); if (type == SSH_SMSG_SUCCESS) return 1; if (type != SSH_SMSG_FAILURE) packet_disconnect("Protocol error: got %d in response " "to skey-auth-reponse", type); } /* failure */ return 0; } /* * Tries to authenticate with plain passwd authentication. */ int try_password_authentication(char *prompt) { int type, i, payload_len; char *password; debug("Doing password authentication."); if (options.cipher == SSH_CIPHER_NONE) log("WARNING: Encryption is disabled! Password will be transmitted in clear text."); for (i = 0; i < options.number_of_password_prompts; i++) { if (i != 0) error("Permission denied, please try again."); password = read_passphrase(prompt, 0); packet_start(SSH_CMSG_AUTH_PASSWORD); packet_put_string(password, strlen(password)); memset(password, 0, strlen(password)); xfree(password); packet_send(); packet_write_wait(); type = packet_read(&payload_len); if (type == SSH_SMSG_SUCCESS) return 1; if (type != SSH_SMSG_FAILURE) packet_disconnect("Protocol error: got %d in response to passwd auth", type); } /* failure */ return 0; } /* * SSH1 key exchange */ void ssh_kex(char *host, struct sockaddr *hostaddr) { int i; BIGNUM *key; RSA *host_key; RSA *public_key; Key k; int bits, rbits; int ssh_cipher_default = SSH_CIPHER_3DES; unsigned char session_key[SSH_SESSION_KEY_LENGTH]; unsigned char cookie[8]; unsigned int supported_ciphers; unsigned int server_flags, client_flags; int payload_len, clen, sum_len = 0; u_int32_t rand = 0; debug("Waiting for server public key."); /* Wait for a public key packet from the server. */ packet_read_expect(&payload_len, SSH_SMSG_PUBLIC_KEY); /* Get cookie from the packet. */ for (i = 0; i < 8; i++) cookie[i] = packet_get_char(); /* Get the public key. */ public_key = RSA_new(); bits = packet_get_int();/* bits */ public_key->e = BN_new(); packet_get_bignum(public_key->e, &clen); sum_len += clen; public_key->n = BN_new(); packet_get_bignum(public_key->n, &clen); sum_len += clen; rbits = BN_num_bits(public_key->n); if (bits != rbits) { log("Warning: Server lies about size of server public key: " "actual size is %d bits vs. announced %d.", rbits, bits); log("Warning: This may be due to an old implementation of ssh."); } /* Get the host key. */ host_key = RSA_new(); bits = packet_get_int();/* bits */ host_key->e = BN_new(); packet_get_bignum(host_key->e, &clen); sum_len += clen; host_key->n = BN_new(); packet_get_bignum(host_key->n, &clen); sum_len += clen; rbits = BN_num_bits(host_key->n); if (bits != rbits) { log("Warning: Server lies about size of server host key: " "actual size is %d bits vs. announced %d.", rbits, bits); log("Warning: This may be due to an old implementation of ssh."); } /* Get protocol flags. */ server_flags = packet_get_int(); packet_set_protocol_flags(server_flags); supported_ciphers = packet_get_int(); supported_authentications = packet_get_int(); debug("Received server public key (%d bits) and host key (%d bits).", BN_num_bits(public_key->n), BN_num_bits(host_key->n)); packet_integrity_check(payload_len, 8 + 4 + sum_len + 0 + 4 + 0 + 0 + 4 + 4 + 4, SSH_SMSG_PUBLIC_KEY); k.type = KEY_RSA; k.rsa = host_key; check_host_key(host, hostaddr, &k, options.user_hostfile, options.system_hostfile); client_flags = SSH_PROTOFLAG_SCREEN_NUMBER | SSH_PROTOFLAG_HOST_IN_FWD_OPEN; compute_session_id(session_id, cookie, host_key->n, public_key->n); /* Generate a session key. */ arc4random_stir(); /* * Generate an encryption key for the session. The key is a 256 bit * random number, interpreted as a 32-byte key, with the least * significant 8 bits being the first byte of the key. */ for (i = 0; i < 32; i++) { if (i % 4 == 0) rand = arc4random(); session_key[i] = rand & 0xff; rand >>= 8; } /* * According to the protocol spec, the first byte of the session key * is the highest byte of the integer. The session key is xored with * the first 16 bytes of the session id. */ key = BN_new(); BN_set_word(key, 0); for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) { BN_lshift(key, key, 8); if (i < 16) BN_add_word(key, session_key[i] ^ session_id[i]); else BN_add_word(key, session_key[i]); } /* * Encrypt the integer using the public key and host key of the * server (key with smaller modulus first). */ if (BN_cmp(public_key->n, host_key->n) < 0) { /* Public key has smaller modulus. */ if (BN_num_bits(host_key->n) < BN_num_bits(public_key->n) + SSH_KEY_BITS_RESERVED) { fatal("respond_to_rsa_challenge: host_key %d < public_key %d + " "SSH_KEY_BITS_RESERVED %d", BN_num_bits(host_key->n), BN_num_bits(public_key->n), SSH_KEY_BITS_RESERVED); } rsa_public_encrypt(key, key, public_key); rsa_public_encrypt(key, key, host_key); } else { /* Host key has smaller modulus (or they are equal). */ if (BN_num_bits(public_key->n) < BN_num_bits(host_key->n) + SSH_KEY_BITS_RESERVED) { fatal("respond_to_rsa_challenge: public_key %d < host_key %d + " "SSH_KEY_BITS_RESERVED %d", BN_num_bits(public_key->n), BN_num_bits(host_key->n), SSH_KEY_BITS_RESERVED); } rsa_public_encrypt(key, key, host_key); rsa_public_encrypt(key, key, public_key); } /* Destroy the public keys since we no longer need them. */ RSA_free(public_key); RSA_free(host_key); if (options.cipher == SSH_CIPHER_ILLEGAL) { log("No valid SSH1 cipher, using %.100s instead.", cipher_name(SSH_FALLBACK_CIPHER)); options.cipher = SSH_FALLBACK_CIPHER; } else if (options.cipher == SSH_CIPHER_NOT_SET) { if (cipher_mask1() & supported_ciphers & (1 << ssh_cipher_default)) options.cipher = ssh_cipher_default; else { debug("Cipher %s not supported, using %.100s instead.", cipher_name(ssh_cipher_default), cipher_name(SSH_FALLBACK_CIPHER)); options.cipher = SSH_FALLBACK_CIPHER; } } /* Check that the selected cipher is supported. */ if (!(supported_ciphers & (1 << options.cipher))) fatal("Selected cipher type %.100s not supported by server.", cipher_name(options.cipher)); debug("Encryption type: %.100s", cipher_name(options.cipher)); /* Send the encrypted session key to the server. */ packet_start(SSH_CMSG_SESSION_KEY); packet_put_char(options.cipher); /* Send the cookie back to the server. */ for (i = 0; i < 8; i++) packet_put_char(cookie[i]); /* Send and destroy the encrypted encryption key integer. */ packet_put_bignum(key); BN_clear_free(key); /* Send protocol flags. */ packet_put_int(client_flags); /* Send the packet now. */ packet_send(); packet_write_wait(); debug("Sent encrypted session key."); /* Set the encryption key. */ packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, options.cipher); /* We will no longer need the session key here. Destroy any extra copies. */ memset(session_key, 0, sizeof(session_key)); /* * Expect a success message from the server. Note that this message * will be received in encrypted form. */ packet_read_expect(&payload_len, SSH_SMSG_SUCCESS); debug("Received encrypted confirmation."); } /* * Authenticate user */ void ssh_userauth( const char* local_user, const char* server_user, char *host, int host_key_valid, RSA *own_host_key) { int i, type; int payload_len; if (supported_authentications == 0) fatal("ssh_userauth: server supports no auth methods"); /* Send the name of the user to log in as on the server. */ packet_start(SSH_CMSG_USER); packet_put_string(server_user, strlen(server_user)); packet_send(); packet_write_wait(); /* * The server should respond with success if no authentication is * needed (the user has no password). Otherwise the server responds * with failure. */ type = packet_read(&payload_len); /* check whether the connection was accepted without authentication. */ if (type == SSH_SMSG_SUCCESS) return; if (type != SSH_SMSG_FAILURE) packet_disconnect("Protocol error: got %d in response to SSH_CMSG_USER", type); #ifdef AFS /* Try Kerberos tgt passing if the server supports it. */ if ((supported_authentications & (1 << SSH_PASS_KERBEROS_TGT)) && options.kerberos_tgt_passing) { if (options.cipher == SSH_CIPHER_NONE) log("WARNING: Encryption is disabled! Ticket will be transmitted in the clear!"); (void) send_kerberos_tgt(); } /* Try AFS token passing if the server supports it. */ if ((supported_authentications & (1 << SSH_PASS_AFS_TOKEN)) && options.afs_token_passing && k_hasafs()) { if (options.cipher == SSH_CIPHER_NONE) log("WARNING: Encryption is disabled! Token will be transmitted in the clear!"); send_afs_tokens(); } #endif /* AFS */ #ifdef KRB4 if ((supported_authentications & (1 << SSH_AUTH_KERBEROS)) && options.kerberos_authentication) { debug("Trying Kerberos authentication."); if (try_kerberos_authentication()) { /* The server should respond with success or failure. */ type = packet_read(&payload_len); if (type == SSH_SMSG_SUCCESS) return; if (type != SSH_SMSG_FAILURE) packet_disconnect("Protocol error: got %d in response to Kerberos auth", type); } } #endif /* KRB4 */ /* * Use rhosts authentication if running in privileged socket and we * do not wish to remain anonymous. */ if ((supported_authentications & (1 << SSH_AUTH_RHOSTS)) && options.rhosts_authentication) { debug("Trying rhosts authentication."); packet_start(SSH_CMSG_AUTH_RHOSTS); packet_put_string(local_user, strlen(local_user)); packet_send(); packet_write_wait(); /* The server should respond with success or failure. */ type = packet_read(&payload_len); if (type == SSH_SMSG_SUCCESS) return; if (type != SSH_SMSG_FAILURE) packet_disconnect("Protocol error: got %d in response to rhosts auth", type); } /* * Try .rhosts or /etc/hosts.equiv authentication with RSA host * authentication. */ if ((supported_authentications & (1 << SSH_AUTH_RHOSTS_RSA)) && options.rhosts_rsa_authentication && host_key_valid) { if (try_rhosts_rsa_authentication(local_user, own_host_key)) return; } /* Try RSA authentication if the server supports it. */ if ((supported_authentications & (1 << SSH_AUTH_RSA)) && options.rsa_authentication) { /* * Try RSA authentication using the authentication agent. The * agent is tried first because no passphrase is needed for * it, whereas identity files may require passphrases. */ if (try_agent_authentication()) return; /* Try RSA authentication for each identity. */ for (i = 0; i < options.num_identity_files; i++) if (try_rsa_authentication(options.identity_files[i])) return; } /* Try skey authentication if the server supports it. */ if ((supported_authentications & (1 << SSH_AUTH_TIS)) && options.skey_authentication && !options.batch_mode) { if (try_skey_authentication()) return; } /* Try password authentication if the server supports it. */ if ((supported_authentications & (1 << SSH_AUTH_PASSWORD)) && options.password_authentication && !options.batch_mode) { char prompt[80]; snprintf(prompt, sizeof(prompt), "%.30s@%.40s's password: ", server_user, host); if (try_password_authentication(prompt)) return; } /* All authentication methods have failed. Exit with an error message. */ fatal("Permission denied."); /* NOTREACHED */ }