diff options
Diffstat (limited to 'crypto/openssh/sshconnect1.c')
| -rw-r--r-- | crypto/openssh/sshconnect1.c | 1024 |
1 files changed, 0 insertions, 1024 deletions
diff --git a/crypto/openssh/sshconnect1.c b/crypto/openssh/sshconnect1.c deleted file mode 100644 index 4360d7283d865..0000000000000 --- a/crypto/openssh/sshconnect1.c +++ /dev/null @@ -1,1024 +0,0 @@ -/* - * Author: Tatu Ylonen <ylo@cs.hut.fi> - * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, 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 1.3 2000/05/08 17:12:16 markus Exp $"); - -#include <openssl/bn.h> -#include <openssl/dsa.h> -#include <openssl/rsa.h> -#include <openssl/evp.h> - -#include "xmalloc.h" -#include "rsa.h" -#include "ssh.h" -#include "buffer.h" -#include "packet.h" -#include "authfd.h" -#include "cipher.h" -#include "mpaux.h" -#include "uidswap.h" -#include "readconf.h" -#include "key.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 status, type; - char *comment; - AuthenticationConnection *auth; - unsigned char response[16]; - unsigned int i; - BIGNUM *e, *n, *challenge; - - /* Get connection to the agent. */ - auth = ssh_get_authentication_connection(); - if (!auth) - return 0; - - e = BN_new(); - n = BN_new(); - challenge = BN_new(); - - /* Loop through identities served by the agent. */ - for (status = ssh_get_first_identity(auth, e, n, &comment); - status; - status = ssh_get_next_identity(auth, e, n, &comment)) { - int plen, clen; - - /* 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(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."); - 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, e, n, 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)); - } - 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) { - debug("RSA authentication accepted by server."); - BN_clear_free(e); - BN_clear_free(n); - BN_clear_free(challenge); - 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(e); - BN_clear_free(n); - 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 */ -} |