| /* |
| |
| sshconnect.c |
| |
| 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("$Id: sshconnect.c,v 1.12 1999/11/18 21:25:48 damien Exp $"); |
| |
| #ifdef HAVE_OPENSSL |
| #include <openssl/bn.h> |
| #include <openssl/md5.h> |
| #endif |
| #ifdef HAVE_SSL |
| #include <ssl/bn.h> |
| #include <ssl/md5.h> |
| #endif |
| |
| #include "xmalloc.h" |
| #include "rsa.h" |
| #include "ssh.h" |
| #include "packet.h" |
| #include "authfd.h" |
| #include "cipher.h" |
| #include "mpaux.h" |
| #include "uidswap.h" |
| #include "compat.h" |
| #include "readconf.h" |
| #include "fingerprint.h" |
| |
| /* Session id for the current session. */ |
| unsigned char session_id[16]; |
| |
| /* Connect to the given ssh server using a proxy command. */ |
| |
| int |
| ssh_proxy_connect(const char *host, int port, uid_t original_real_uid, |
| const char *proxy_command) |
| { |
| Buffer command; |
| const char *cp; |
| char *command_string; |
| int pin[2], pout[2]; |
| int pid; |
| char portstring[100]; |
| |
| /* Convert the port number into a string. */ |
| snprintf(portstring, sizeof portstring, "%d", port); |
| |
| /* Build the final command string in the buffer by making the appropriate |
| substitutions to the given proxy command. */ |
| buffer_init(&command); |
| for (cp = proxy_command; *cp; cp++) |
| { |
| if (cp[0] == '%' && cp[1] == '%') |
| { |
| buffer_append(&command, "%", 1); |
| cp++; |
| continue; |
| } |
| if (cp[0] == '%' && cp[1] == 'h') |
| { |
| buffer_append(&command, host, strlen(host)); |
| cp++; |
| continue; |
| } |
| if (cp[0] == '%' && cp[1] == 'p') |
| { |
| buffer_append(&command, portstring, strlen(portstring)); |
| cp++; |
| continue; |
| } |
| buffer_append(&command, cp, 1); |
| } |
| buffer_append(&command, "\0", 1); |
| |
| /* Get the final command string. */ |
| command_string = buffer_ptr(&command); |
| |
| /* Create pipes for communicating with the proxy. */ |
| if (pipe(pin) < 0 || pipe(pout) < 0) |
| fatal("Could not create pipes to communicate with the proxy: %.100s", |
| strerror(errno)); |
| |
| debug("Executing proxy command: %.500s", command_string); |
| |
| /* Fork and execute the proxy command. */ |
| if ((pid = fork()) == 0) |
| { |
| char *argv[10]; |
| |
| /* Child. Permanently give up superuser privileges. */ |
| permanently_set_uid(original_real_uid); |
| |
| /* Redirect stdin and stdout. */ |
| close(pin[1]); |
| if (pin[0] != 0) |
| { |
| if (dup2(pin[0], 0) < 0) |
| perror("dup2 stdin"); |
| close(pin[0]); |
| } |
| close(pout[0]); |
| if (dup2(pout[1], 1) < 0) |
| perror("dup2 stdout"); |
| close(pout[1]); /* Cannot be 1 because pin allocated two descriptors. */ |
| |
| /* Stderr is left as it is so that error messages get printed on |
| the user's terminal. */ |
| argv[0] = "/bin/sh"; |
| argv[1] = "-c"; |
| argv[2] = command_string; |
| argv[3] = NULL; |
| |
| /* Execute the proxy command. Note that we gave up any extra |
| privileges above. */ |
| execv("/bin/sh", argv); |
| perror("/bin/sh"); |
| exit(1); |
| } |
| /* Parent. */ |
| if (pid < 0) |
| fatal("fork failed: %.100s", strerror(errno)); |
| |
| /* Close child side of the descriptors. */ |
| close(pin[0]); |
| close(pout[1]); |
| |
| /* Free the command name. */ |
| buffer_free(&command); |
| |
| /* Set the connection file descriptors. */ |
| packet_set_connection(pout[0], pin[1]); |
| |
| return 1; |
| } |
| |
| /* Creates a (possibly privileged) socket for use as the ssh connection. */ |
| |
| int ssh_create_socket(uid_t original_real_uid, int privileged) |
| { |
| int sock; |
| |
| /* If we are running as root and want to connect to a privileged port, |
| bind our own socket to a privileged port. */ |
| if (privileged) |
| { |
| int p = IPPORT_RESERVED - 1; |
| |
| sock = rresvport(&p); |
| if (sock < 0) |
| fatal("rresvport: %.100s", strerror(errno)); |
| debug("Allocated local port %d.", p); |
| } |
| else |
| { |
| /* Just create an ordinary socket on arbitrary port. We use the |
| user's uid to create the socket. */ |
| temporarily_use_uid(original_real_uid); |
| sock = socket(AF_INET, SOCK_STREAM, 0); |
| if (sock < 0) |
| fatal("socket: %.100s", strerror(errno)); |
| restore_uid(); |
| } |
| return sock; |
| } |
| |
| /* Opens a TCP/IP connection to the remote server on the given host. If |
| port is 0, the default port will be used. If anonymous is zero, |
| a privileged port will be allocated to make the connection. |
| This requires super-user privileges if anonymous is false. |
| Connection_attempts specifies the maximum number of tries (one per |
| second). If proxy_command is non-NULL, it specifies the command (with %h |
| and %p substituted for host and port, respectively) to use to contact |
| the daemon. */ |
| |
| int ssh_connect(const char *host, struct sockaddr_in *hostaddr, |
| int port, int connection_attempts, |
| int anonymous, uid_t original_real_uid, |
| const char *proxy_command) |
| { |
| int sock = -1, attempt, i; |
| int on = 1; |
| struct servent *sp; |
| struct hostent *hp; |
| struct linger linger; |
| |
| debug("ssh_connect: getuid %d geteuid %d anon %d", |
| (int)getuid(), (int)geteuid(), anonymous); |
| |
| /* Get default port if port has not been set. */ |
| if (port == 0) |
| { |
| sp = getservbyname(SSH_SERVICE_NAME, "tcp"); |
| if (sp) |
| port = ntohs(sp->s_port); |
| else |
| port = SSH_DEFAULT_PORT; |
| } |
| |
| /* If a proxy command is given, connect using it. */ |
| if (proxy_command != NULL) |
| return ssh_proxy_connect(host, port, original_real_uid, proxy_command); |
| |
| /* No proxy command. */ |
| |
| /* No host lookup made yet. */ |
| hp = NULL; |
| |
| /* Try to connect several times. On some machines, the first time will |
| sometimes fail. In general socket code appears to behave quite |
| magically on many machines. */ |
| for (attempt = 0; attempt < connection_attempts; attempt++) |
| { |
| if (attempt > 0) |
| debug("Trying again..."); |
| |
| /* Try to parse the host name as a numeric inet address. */ |
| memset(hostaddr, 0, sizeof(hostaddr)); |
| hostaddr->sin_family = AF_INET; |
| hostaddr->sin_port = htons(port); |
| hostaddr->sin_addr.s_addr = inet_addr(host); |
| if ((hostaddr->sin_addr.s_addr & 0xffffffff) != 0xffffffff) |
| { |
| /* Valid numeric IP address */ |
| debug("Connecting to %.100s port %d.", |
| inet_ntoa(hostaddr->sin_addr), port); |
| |
| /* Create a socket. */ |
| sock = ssh_create_socket(original_real_uid, |
| !anonymous && geteuid() == 0 && |
| port < IPPORT_RESERVED); |
| |
| /* Connect to the host. We use the user's uid in the hope that |
| it will help with the problems of tcp_wrappers showing the |
| remote uid as root. */ |
| temporarily_use_uid(original_real_uid); |
| if (connect(sock, (struct sockaddr *)hostaddr, sizeof(*hostaddr)) |
| >= 0) |
| { |
| /* Successful connect. */ |
| restore_uid(); |
| break; |
| } |
| debug("connect: %.100s", strerror(errno)); |
| restore_uid(); |
| |
| /* Destroy the failed socket. */ |
| shutdown(sock, SHUT_RDWR); |
| close(sock); |
| } |
| else |
| { |
| /* Not a valid numeric inet address. */ |
| /* Map host name to an address. */ |
| if (!hp) |
| hp = gethostbyname(host); |
| if (!hp) |
| fatal("Bad host name: %.100s", host); |
| if (!hp->h_addr_list[0]) |
| fatal("Host does not have an IP address: %.100s", host); |
| |
| /* Loop through addresses for this host, and try each one in |
| sequence until the connection succeeds. */ |
| for (i = 0; hp->h_addr_list[i]; i++) |
| { |
| /* Set the address to connect to. */ |
| hostaddr->sin_family = hp->h_addrtype; |
| memcpy(&hostaddr->sin_addr, hp->h_addr_list[i], |
| sizeof(hostaddr->sin_addr)); |
| |
| debug("Connecting to %.200s [%.100s] port %d.", |
| host, inet_ntoa(hostaddr->sin_addr), port); |
| |
| /* Create a socket for connecting. */ |
| sock = ssh_create_socket(original_real_uid, |
| !anonymous && geteuid() == 0 && |
| port < IPPORT_RESERVED); |
| |
| /* Connect to the host. We use the user's uid in the hope that |
| it will help with tcp_wrappers showing the remote uid as |
| root. */ |
| temporarily_use_uid(original_real_uid); |
| if (connect(sock, (struct sockaddr *)hostaddr, |
| sizeof(*hostaddr)) >= 0) |
| { |
| /* Successful connection. */ |
| restore_uid(); |
| break; |
| } |
| debug("connect: %.100s", strerror(errno)); |
| restore_uid(); |
| |
| /* Close the failed socket; there appear to be some problems |
| when reusing a socket for which connect() has already |
| returned an error. */ |
| shutdown(sock, SHUT_RDWR); |
| close(sock); |
| } |
| if (hp->h_addr_list[i]) |
| break; /* Successful connection. */ |
| } |
| |
| /* Sleep a moment before retrying. */ |
| sleep(1); |
| } |
| /* Return failure if we didn't get a successful connection. */ |
| if (attempt >= connection_attempts) |
| return 0; |
| |
| debug("Connection established."); |
| |
| /* Set socket options. We would like the socket to disappear as soon as |
| it has been closed for whatever reason. */ |
| /* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */ |
| setsockopt(sock, IPPROTO_TCP, TCP_NODELAY, (void *)&on, sizeof(on)); |
| linger.l_onoff = 1; |
| linger.l_linger = 5; |
| setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *)&linger, sizeof(linger)); |
| |
| /* Set the connection. */ |
| packet_set_connection(sock, sock); |
| |
| return 1; |
| } |
| |
| /* 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(struct passwd *pw, const char *authfile) |
| { |
| extern Options options; |
| BIGNUM *challenge; |
| RSA *private_key; |
| RSA *public_key; |
| char *passphrase, *comment; |
| int type, i; |
| int plen, clen; |
| |
| /* Try to load identification for the authentication key. */ |
| public_key = RSA_new(); |
| if (!load_public_key(authfile, public_key, &comment)) { |
| RSA_free(public_key); |
| return 0; /* Could not load it. Fail. */ |
| } |
| |
| 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_key->n); |
| packet_send(); |
| packet_write_wait(); |
| |
| /* We no longer need the public key. */ |
| RSA_free(public_key); |
| |
| /* 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; /* Server refuses to authenticate with this key. */ |
| } |
| |
| /* 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 = RSA_new(); |
| /* Load the private key. Try first with empty passphrase; if it fails, |
| ask for a passphrase. */ |
| if (!load_private_key(authfile, "", private_key, NULL)) |
| { |
| char buf[300]; |
| /* Request passphrase from the user. We read from /dev/tty to make |
| this work even if stdin has been redirected. If running in |
| batch mode, we just use the empty passphrase, which will fail and |
| return. */ |
| 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_key, 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_key); |
| |
| /* Destroy the private key. */ |
| RSA_free(private_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("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; /* Server refuses to authenticate us with this method. */ |
| } |
| |
| /* 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; |
| 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); |
| |
| r = sizeof(local); |
| memset(&local, 0, sizeof(local)); |
| if (getsockname(packet_get_connection_in(), |
| (struct sockaddr *) &local, &r) < 0) |
| debug("getsockname failed: %s", strerror(errno)); |
| |
| r = sizeof(foreign); |
| memset(&foreign, 0, sizeof(foreign)); |
| if (getpeername(packet_get_connection_in(), |
| (struct sockaddr *)&foreign, &r) < 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; |
| unsigned 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, buffer); |
| xfree(creds); |
| |
| packet_start(SSH_CMSG_HAVE_KERBEROS_TGT); |
| packet_put_string((char *)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; |
| unsigned 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, buffer)) break; |
| packet_start(SSH_CMSG_HAVE_AFS_TOKEN); |
| packet_put_string((char *)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 */ |
| |
| /* Waits for the server identification string, and sends our own identification |
| string. */ |
| |
| void ssh_exchange_identification() |
| { |
| char buf[256], remote_version[256]; /* must be same size! */ |
| int remote_major, remote_minor, i; |
| int connection_in = packet_get_connection_in(); |
| int connection_out = packet_get_connection_out(); |
| extern Options options; |
| |
| /* Read other side\'s version identification. */ |
| for (i = 0; i < sizeof(buf) - 1; i++) |
| { |
| if (read(connection_in, &buf[i], 1) != 1) |
| fatal("read: %.100s", strerror(errno)); |
| if (buf[i] == '\r') |
| { |
| buf[i] = '\n'; |
| buf[i + 1] = 0; |
| break; |
| } |
| if (buf[i] == '\n') |
| { |
| buf[i + 1] = 0; |
| break; |
| } |
| } |
| buf[sizeof(buf) - 1] = 0; |
| |
| /* Check that the versions match. In future this might accept several |
| versions and set appropriate flags to handle them. */ |
| if (sscanf(buf, "SSH-%d.%d-%[^\n]\n", &remote_major, &remote_minor, |
| remote_version) != 3) |
| fatal("Bad remote protocol version identification: '%.100s'", buf); |
| debug("Remote protocol version %d.%d, remote software version %.100s", |
| remote_major, remote_minor, remote_version); |
| |
| /* Check if the remote protocol version is too old. */ |
| if (remote_major == 1 && remote_minor < 3) |
| fatal("Remote machine has too old SSH software version."); |
| |
| /* We speak 1.3, too. */ |
| if (remote_major == 1 && remote_minor == 3) { |
| enable_compat13(); |
| if (options.forward_agent && strcmp(remote_version, SSH_VERSION) != 0) { |
| log("Agent forwarding disabled, remote version '%s' is not compatible.", |
| remote_version); |
| options.forward_agent = 0; |
| } |
| } |
| #if 0 |
| /* Removed for now, to permit compatibility with latter versions. The server |
| will reject our version and disconnect if it doesn't support it. */ |
| if (remote_major != PROTOCOL_MAJOR) |
| fatal("Protocol major versions differ: %d vs. %d", |
| PROTOCOL_MAJOR, remote_major); |
| #endif |
| |
| /* Send our own protocol version identification. */ |
| snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", |
| PROTOCOL_MAJOR, PROTOCOL_MINOR, SSH_VERSION); |
| if (write(connection_out, buf, strlen(buf)) != strlen(buf)) |
| fatal("write: %.100s", strerror(errno)); |
| } |
| |
| int ssh_cipher_default = SSH_CIPHER_3DES; |
| |
| int read_yes_or_no(const char *prompt, int defval) |
| { |
| char buf[1024]; |
| FILE *f; |
| int retval = -1; |
| |
| if (isatty(0)) |
| f = stdin; |
| else |
| f = fopen("/dev/tty", "rw"); |
| |
| if (f == NULL) |
| return 0; |
| |
| fflush(stdout); |
| |
| while (1) |
| { |
| fprintf(stderr, "%s", prompt); |
| if (fgets(buf, sizeof(buf), f) == NULL) |
| { |
| /* Print a newline (the prompt probably didn\'t have one). */ |
| fprintf(stderr, "\n"); |
| strlcpy(buf, "no", sizeof buf); |
| } |
| /* Remove newline from response. */ |
| if (strchr(buf, '\n')) |
| *strchr(buf, '\n') = 0; |
| |
| if (buf[0] == 0) |
| retval = defval; |
| if (strcmp(buf, "yes") == 0) |
| retval = 1; |
| if (strcmp(buf, "no") == 0) |
| retval = 0; |
| |
| if (retval != -1) |
| { |
| if (f != stdin) |
| fclose(f); |
| return retval; |
| } |
| } |
| } |
| |
| /* Starts a dialog with the server, and authenticates the current user on the |
| server. This does not need any extra privileges. The basic connection |
| to the server must already have been established before this is called. |
| User is the remote user; if it is NULL, the current local user name will |
| be used. Anonymous indicates that no rhosts authentication will be used. |
| If login fails, this function prints an error and never returns. |
| This function does not require super-user privileges. */ |
| |
| void ssh_login(int host_key_valid, |
| RSA *own_host_key, |
| const char *orighost, |
| struct sockaddr_in *hostaddr, |
| uid_t original_real_uid) |
| { |
| extern Options options; |
| int i, type; |
| char *password; |
| struct passwd *pw; |
| BIGNUM *key; |
| RSA *host_key, *file_key; |
| RSA *public_key; |
| int bits, rbits; |
| unsigned char session_key[SSH_SESSION_KEY_LENGTH]; |
| const char *server_user, *local_user; |
| char *cp, *host, *ip = NULL; |
| unsigned char check_bytes[8]; |
| unsigned int supported_ciphers, supported_authentications, protocol_flags; |
| HostStatus host_status; |
| HostStatus ip_status; |
| int host_ip_differ = 0; |
| int local = (ntohl(hostaddr->sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; |
| int payload_len, clen, sum_len = 0; |
| u_int32_t rand = 0; |
| |
| if (options.check_host_ip) |
| ip = xstrdup(inet_ntoa(hostaddr->sin_addr)); |
| |
| /* Convert the user-supplied hostname into all lowercase. */ |
| host = xstrdup(orighost); |
| for (cp = host; *cp; cp++) |
| if (isupper(*cp)) |
| *cp = tolower(*cp); |
| |
| /* Exchange protocol version identification strings with the server. */ |
| ssh_exchange_identification(); |
| |
| /* Put the connection into non-blocking mode. */ |
| packet_set_nonblocking(); |
| |
| /* Get local user name. Use it as server user if no user name |
| was given. */ |
| pw = getpwuid(original_real_uid); |
| if (!pw) |
| fatal("User id %d not found from user database.", original_real_uid); |
| local_user = xstrdup(pw->pw_name); |
| server_user = options.user ? options.user : local_user; |
| |
| 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 check bytes from the packet. */ |
| for (i = 0; i < 8; i++) |
| check_bytes[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."); |
| } |
| |
| /* Store the host key from the known host file in here |
| * so that we can compare it with the key for the IP |
| * address. */ |
| file_key = RSA_new(); |
| file_key->n = BN_new(); |
| file_key->e = BN_new(); |
| |
| /* Get protocol flags. */ |
| protocol_flags = packet_get_int(); |
| packet_set_protocol_flags(protocol_flags); |
| |
| /* Get supported cipher types. */ |
| supported_ciphers = packet_get_int(); |
| |
| /* Get supported authentication types. */ |
| 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); |
| |
| /* Compute the session id. */ |
| compute_session_id(session_id, check_bytes, host_key->n, public_key->n); |
| |
| /* Check if the host key is present in the user\'s list of known hosts |
| or in the systemwide list. */ |
| host_status = check_host_in_hostfile(options.user_hostfile, host, |
| host_key->e, host_key->n, |
| file_key->e, file_key->n); |
| if (host_status == HOST_NEW) |
| host_status = check_host_in_hostfile(options.system_hostfile, host, |
| host_key->e, host_key->n, |
| file_key->e, file_key->n); |
| /* Force accepting of the host key for localhost and 127.0.0.1. |
| The problem is that if the home directory is NFS-mounted to multiple |
| machines, localhost will refer to a different machine in each of them, |
| and the user will get bogus HOST_CHANGED warnings. This essentially |
| disables host authentication for localhost; however, this is probably |
| not a real problem. */ |
| if (local) { |
| debug("Forcing accepting of host key for localhost."); |
| host_status = HOST_OK; |
| } |
| |
| /* Also perform check for the ip address, skip the check if we are |
| localhost or the hostname was an ip address to begin with */ |
| if (options.check_host_ip && !local && strcmp(host, ip)) { |
| RSA *ip_key = RSA_new(); |
| ip_key->n = BN_new(); |
| ip_key->e = BN_new(); |
| ip_status = check_host_in_hostfile(options.user_hostfile, ip, |
| host_key->e, host_key->n, |
| ip_key->e, ip_key->n); |
| |
| if (ip_status == HOST_NEW) |
| ip_status = check_host_in_hostfile(options.system_hostfile, ip, |
| host_key->e, host_key->n, |
| ip_key->e, ip_key->n); |
| if (host_status == HOST_CHANGED && |
| (ip_status != HOST_CHANGED || |
| (BN_cmp(ip_key->e, file_key->e) || BN_cmp(ip_key->n, file_key->n)))) |
| host_ip_differ = 1; |
| |
| RSA_free(ip_key); |
| } else |
| ip_status = host_status; |
| |
| RSA_free(file_key); |
| |
| switch (host_status) { |
| case HOST_OK: |
| /* The host is known and the key matches. */ |
| debug("Host '%.200s' is known and matches the host key.", host); |
| if (options.check_host_ip) { |
| if (ip_status == HOST_NEW) { |
| if (!add_host_to_hostfile(options.user_hostfile, ip, |
| host_key->e, host_key->n)) |
| log("Failed to add the host key for IP address '%.30s' to the list of known hosts (%.30s).", |
| ip, options.user_hostfile); |
| else |
| log("Warning: Permanently added host key for IP address '%.30s' to the list of known hosts.", |
| ip); |
| } else if (ip_status != HOST_OK) |
| log("Warning: the host key for '%.200s' differs from the key for the IP address '%.30s'", |
| host, ip); |
| } |
| |
| break; |
| case HOST_NEW: |
| { |
| char hostline[1000], *hostp = hostline; |
| /* The host is new. */ |
| if (options.strict_host_key_checking == 1) { |
| /* User has requested strict host key checking. We will not |
| add the host key automatically. The only alternative left |
| is to abort. */ |
| fatal("No host key is known for %.200s and you have requested strict checking.", host); |
| } else if (options.strict_host_key_checking == 2) { /* The default */ |
| char prompt[1024]; |
| char *fp = fingerprint(host_key->e, host_key->n); |
| snprintf(prompt, sizeof(prompt), |
| "The authenticity of host '%.200s' can't be established.\n" |
| "Key fingerprint is %d %s.\n" |
| "Are you sure you want to continue connecting (yes/no)? ", |
| host, BN_num_bits(host_key->n), fp); |
| if (!read_yes_or_no(prompt, -1)) |
| fatal("Aborted by user!\n"); |
| } |
| |
| if (options.check_host_ip && ip_status == HOST_NEW && strcmp(host, ip)) |
| snprintf(hostline, sizeof(hostline), "%s,%s", host, ip); |
| else |
| hostp = host; |
| |
| /* If not in strict mode, add the key automatically to the local |
| known_hosts file. */ |
| if (!add_host_to_hostfile(options.user_hostfile, hostp, |
| host_key->e, host_key->n)) |
| log("Failed to add the host to the list of known hosts (%.500s).", |
| options.user_hostfile); |
| else |
| log("Warning: Permanently added '%.200s' to the list of known hosts.", |
| hostp); |
| break; |
| } |
| case HOST_CHANGED: |
| if (options.check_host_ip) { |
| if (host_ip_differ) { |
| char *msg; |
| if (ip_status == HOST_NEW) |
| msg = "is unknown"; |
| else if (ip_status == HOST_OK) |
| msg = "is unchanged"; |
| else |
| msg = "has a different value"; |
| error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); |
| error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @"); |
| error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); |
| error("The host key for %s has changed,", host); |
| error("and the key for the according IP address %s", ip); |
| error("%s. This could either mean that", msg); |
| error("DNS SPOOFING is happening or the IP address for the host"); |
| error("and its host key have changed at the same time"); |
| } |
| } |
| |
| /* The host key has changed. */ |
| error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); |
| error("@ WARNING: HOST IDENTIFICATION HAS CHANGED! @"); |
| error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); |
| error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!"); |
| error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!"); |
| error("It is also possible that the host key has just been changed."); |
| error("Please contact your system administrator."); |
| error("Add correct host key in %.100s to get rid of this message.", |
| options.user_hostfile); |
| |
| /* If strict host key checking is in use, the user will have to edit |
| the key manually and we can only abort. */ |
| if (options.strict_host_key_checking) |
| fatal("Host key for %.200s has changed and you have requested strict checking.", host); |
| |
| /* If strict host key checking has not been requested, allow the |
| connection but without password authentication or |
| agent forwarding. */ |
| if (options.password_authentication) { |
| error("Password authentication is disabled to avoid trojan horses."); |
| options.password_authentication = 0; |
| } |
| if (options.forward_agent) { |
| error("Agent forwarding is disabled to avoid trojan horses."); |
| options.forward_agent = 0; |
| } |
| /* XXX Should permit the user to change to use the new id. This could |
| be done by converting the host key to an identifying sentence, tell |
| that the host identifies itself by that sentence, and ask the user |
| if he/she whishes to accept the authentication. */ |
| break; |
| } |
| |
| if (options.check_host_ip) |
| xfree(ip); |
| |
| /* 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); |
| } |
| |
| if (options.cipher == SSH_CIPHER_NOT_SET) { |
| if (cipher_mask() & 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 check bytes back to the server. */ |
| for (i = 0; i < 8; i++) |
| packet_put_char(check_bytes[i]); |
| |
| /* Send the encrypted encryption key. */ |
| packet_put_bignum(key); |
| |
| /* Send protocol flags. */ |
| packet_put_int(SSH_PROTOFLAG_SCREEN_NUMBER | SSH_PROTOFLAG_HOST_IN_FWD_OPEN); |
| |
| /* Send the packet now. */ |
| packet_send(); |
| packet_write_wait(); |
| |
| /* Destroy the session key integer and the public keys since we no longer |
| need them. */ |
| BN_clear_free(key); |
| RSA_free(public_key); |
| RSA_free(host_key); |
| |
| 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."); |
| |
| /* 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); |
| if (type == SSH_SMSG_SUCCESS) |
| return; /* Connection was accepted without authentication. */ |
| 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; /* Successful connection. */ |
| 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; /* Successful connection. */ |
| 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; /* Successful authentication. */ |
| } |
| |
| /* 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; /* Successful connection. */ |
| |
| /* Try RSA authentication for each identity. */ |
| for (i = 0; i < options.num_identity_files; i++) |
| if (try_rsa_authentication(pw, options.identity_files[i])) |
| return; /* Successful connection. */ |
| } |
| |
| /* 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@%.30s's password: ", |
| server_user, host); |
| 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; /* Successful connection. */ |
| if (type != SSH_SMSG_FAILURE) |
| packet_disconnect("Protocol error: got %d in response to passwd auth", type); |
| } |
| } |
| |
| /* All authentication methods have failed. Exit with an error message. */ |
| fatal("Permission denied."); |
| /*NOTREACHED*/ |
| } |