* 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.
+ *
+ * As far as I am concerned, the code I have written for this software
+ * can be used freely for any purpose. Any derived versions of this
+ * software must be clearly marked as such, and if the derived work is
+ * incompatible with the protocol description in the RFC file, it must be
+ * called by a name other than "ssh" or "Secure Shell".
*/
#include "includes.h"
-RCSID("$OpenBSD: sshconnect.c,v 1.53 2000/01/18 09:42:17 markus Exp $");
+RCSID("$OpenBSD: sshconnect.c,v 1.111 2001/10/01 21:51:16 markus 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 "ssh.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 "compat.h"
+#include "key.h"
+#include "sshconnect.h"
+#include "hostfile.h"
+#include "log.h"
#include "readconf.h"
-#include "fingerprint.h"
-
-/* Session id for the current session. */
-unsigned char session_id[16];
+#include "atomicio.h"
+#include "misc.h"
-/* authentications supported by server */
-unsigned int supported_authentications;
+char *client_version_string = NULL;
+char *server_version_string = NULL;
extern Options options;
extern char *__progname;
+/* AF_UNSPEC or AF_INET or AF_INET6 */
+extern int IPv4or6;
+
+#ifndef INET6_ADDRSTRLEN /* for non IPv6 machines */
+#define INET6_ADDRSTRLEN 46
+#endif
+
+static const char *
+sockaddr_ntop(struct sockaddr *sa)
+{
+ void *addr;
+ static char addrbuf[INET6_ADDRSTRLEN];
+
+ switch (sa->sa_family) {
+ case AF_INET:
+ addr = &((struct sockaddr_in *)sa)->sin_addr;
+ break;
+ case AF_INET6:
+ addr = &((struct sockaddr_in6 *)sa)->sin6_addr;
+ break;
+ default:
+ /* This case should be protected against elsewhere */
+ abort();
+ }
+ inet_ntop(sa->sa_family, addr, addrbuf, sizeof(addrbuf));
+ return addrbuf;
+}
+
/*
* Connect to the given ssh server using a proxy command.
*/
-int
-ssh_proxy_connect(const char *host, u_short port, uid_t original_real_uid,
+static int
+ssh_proxy_connect(const char *host, u_short port, struct passwd *pw,
const char *proxy_command)
{
Buffer command;
const char *cp;
char *command_string;
int pin[2], pout[2];
- int pid;
+ pid_t pid;
char strport[NI_MAXSERV];
/* Convert the port number into a string. */
char *argv[10];
/* Child. Permanently give up superuser privileges. */
- permanently_set_uid(original_real_uid);
+ permanently_set_uid(pw);
/* Redirect stdin and stdout. */
close(pin[1]);
/* Stderr is left as it is so that error messages get
printed on the user's terminal. */
- argv[0] = "/bin/sh";
+ argv[0] = _PATH_BSHELL;
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");
+ execv(argv[0], argv);
+ perror(argv[0]);
exit(1);
}
/* Parent. */
/* Set the connection file descriptors. */
packet_set_connection(pout[0], pin[1]);
- return 1;
+ /* Indicate OK return */
+ return 0;
}
/*
* Creates a (possibly privileged) socket for use as the ssh connection.
*/
-int
-ssh_create_socket(uid_t original_real_uid, int privileged, int family)
+static int
+ssh_create_socket(struct passwd *pw, int privileged, int family)
{
- int sock;
+ int sock, gaierr;
+ struct addrinfo hints, *res;
/*
* If we are running as root and want to connect to a privileged
int p = IPPORT_RESERVED - 1;
sock = rresvport_af(&p, family);
if (sock < 0)
- fatal("rresvport: af=%d %.100s", family, 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(family, SOCK_STREAM, 0);
- if (sock < 0)
- error("socket: %.100s", strerror(errno));
- restore_uid();
+ error("rresvport: af=%d %.100s", family, strerror(errno));
+ else
+ debug("Allocated local port %d.", p);
+ return sock;
+ }
+ /*
+ * Just create an ordinary socket on arbitrary port. We use
+ * the user's uid to create the socket.
+ */
+ temporarily_use_uid(pw);
+ sock = socket(family, SOCK_STREAM, 0);
+ if (sock < 0)
+ error("socket: %.100s", strerror(errno));
+ restore_uid();
+
+ /* Bind the socket to an alternative local IP address */
+ if (options.bind_address == NULL)
+ return sock;
+
+ memset(&hints, 0, sizeof(hints));
+ hints.ai_family = IPv4or6;
+ hints.ai_socktype = SOCK_STREAM;
+ hints.ai_flags = AI_PASSIVE;
+ gaierr = getaddrinfo(options.bind_address, "0", &hints, &res);
+ if (gaierr) {
+ error("getaddrinfo: %s: %s", options.bind_address,
+ gai_strerror(gaierr));
+ close(sock);
+ return -1;
+ }
+ if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
+ error("bind: %s: %s", options.bind_address, strerror(errno));
+ close(sock);
+ freeaddrinfo(res);
+ return -1;
}
+ freeaddrinfo(res);
return sock;
}
* 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.
+ * Return values:
+ * 0 for OK
+ * ECONNREFUSED if we got a "Connection Refused" by the peer on any address
+ * ECONNABORTED if we failed without a "Connection refused"
+ * Suitable error messages for the connection failure will already have been
+ * printed.
*/
int
ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
u_short port, int connection_attempts,
- int anonymous, uid_t original_real_uid,
+ int anonymous, struct passwd *pw,
const char *proxy_command)
{
+ int gaierr;
+ int on = 1;
int sock = -1, attempt;
- struct servent *sp;
- struct addrinfo hints, *ai, *aitop;
char ntop[NI_MAXHOST], strport[NI_MAXSERV];
- int gaierr;
+ struct addrinfo hints, *ai, *aitop;
struct linger linger;
+ struct servent *sp;
+ /*
+ * Did we get only other errors than "Connection refused" (which
+ * should block fallback to rsh and similar), or did we get at least
+ * one "Connection refused"?
+ */
+ int full_failure = 1;
- debug("ssh_connect: getuid %d geteuid %d anon %d",
- (int) getuid(), (int) geteuid(), anonymous);
+ debug("ssh_connect: getuid %u geteuid %u anon %d",
+ (u_int) getuid(), (u_int) geteuid(), anonymous);
/* Get default port if port has not been set. */
if (port == 0) {
}
/* If a proxy command is given, connect using it. */
if (proxy_command != NULL)
- return ssh_proxy_connect(host, port, original_real_uid, proxy_command);
+ return ssh_proxy_connect(host, port, pw, proxy_command);
/* No proxy command. */
* 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++) {
+ */
+ for (attempt = 0; ;) {
if (attempt > 0)
debug("Trying again...");
/* Loop through addresses for this host, and try each one in
- sequence until the connection succeeds. */
+ sequence until the connection succeeds. */
for (ai = aitop; ai; ai = ai->ai_next) {
if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
continue;
host, ntop, strport);
/* Create a socket for connecting. */
- sock = ssh_create_socket(original_real_uid,
- !anonymous && geteuid() == 0 && port < IPPORT_RESERVED,
+ sock = ssh_create_socket(pw,
+#ifdef HAVE_CYGWIN
+ !anonymous,
+#else
+ !anonymous && geteuid() == 0,
+#endif
ai->ai_family);
if (sock < 0)
+ /* Any error is already output */
continue;
/* 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);
+ temporarily_use_uid(pw);
if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) {
/* Successful connection. */
- memcpy(hostaddr, ai->ai_addr, sizeof(*(ai->ai_addr)));
+ memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
restore_uid();
break;
} else {
- debug("connect: %.100s", strerror(errno));
+ if (errno == ECONNREFUSED)
+ full_failure = 0;
+ log("ssh: connect to address %s port %s: %s",
+ sockaddr_ntop(ai->ai_addr), strport,
+ strerror(errno));
restore_uid();
/*
* Close the failed socket; there appear to
if (ai)
break; /* Successful connection. */
+ attempt++;
+ if (attempt >= connection_attempts)
+ break;
/* Sleep a moment before retrying. */
sleep(1);
}
/* Return failure if we didn't get a successful connection. */
if (attempt >= connection_attempts)
- return 0;
+ return full_failure ? ECONNABORTED : ECONNREFUSED;
debug("Connection established.");
/* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
linger.l_onoff = 1;
linger.l_linger = 5;
- setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger));
+ setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *)&linger, sizeof(linger));
+
+ /* Set keepalives if requested. */
+ if (options.keepalives &&
+ setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
+ sizeof(on)) < 0)
+ error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
/* 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(const char *authfile)
-{
- 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);
- /* 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_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;
- }
- /* 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];
- 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;
- }
- /* 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 */
-
-/*
- * 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, payload_len;
- 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(&payload_len);
- if (options.cipher == SSH_CIPHER_NONE)
- log("WARNING: Encryption is disabled! "
- "Reponse will be transmitted in clear text.");
- fprintf(stderr, "%s\n", 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;
}
* Waits for the server identification string, and sends our own
* identification string.
*/
-void
-ssh_exchange_identification()
+static void
+ssh_exchange_identification(void)
{
char buf[256], remote_version[256]; /* must be same size! */
- int remote_major, remote_minor, i;
+ int remote_major, remote_minor, i, mismatch;
int connection_in = packet_get_connection_in();
int connection_out = packet_get_connection_out();
+ int minor1 = PROTOCOL_MINOR_1;
/* Read other side\'s version identification. */
- for (i = 0; i < sizeof(buf) - 1; i++) {
- if (read(connection_in, &buf[i], 1) != 1)
- fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
- if (buf[i] == '\r') {
- buf[i] = '\n';
- buf[i + 1] = 0;
- break;
+ for (;;) {
+ for (i = 0; i < sizeof(buf) - 1; i++) {
+ int len = atomicio(read, connection_in, &buf[i], 1);
+ if (len < 0)
+ fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
+ if (len != 1)
+ fatal("ssh_exchange_identification: Connection closed by remote host");
+ if (buf[i] == '\r') {
+ buf[i] = '\n';
+ buf[i + 1] = 0;
+ continue; /**XXX wait for \n */
+ }
+ if (buf[i] == '\n') {
+ buf[i + 1] = 0;
+ break;
+ }
}
- if (buf[i] == '\n') {
- buf[i + 1] = 0;
+ buf[sizeof(buf) - 1] = 0;
+ if (strncmp(buf, "SSH-", 4) == 0)
break;
- }
+ debug("ssh_exchange_identification: %s", buf);
}
- buf[sizeof(buf) - 1] = 0;
+ server_version_string = xstrdup(buf);
/*
* 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)
+ if (sscanf(server_version_string, "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.");
+ compat_datafellows(remote_version);
+ mismatch = 0;
- /* We speak 1.3, too. */
- if (remote_major == 1 && remote_minor == 3) {
- enable_compat13();
- if (options.forward_agent) {
- log("Agent forwarding disabled for protocol 1.3");
- options.forward_agent = 0;
+ switch(remote_major) {
+ case 1:
+ if (remote_minor == 99 &&
+ (options.protocol & SSH_PROTO_2) &&
+ !(options.protocol & SSH_PROTO_1_PREFERRED)) {
+ enable_compat20();
+ break;
+ }
+ if (!(options.protocol & SSH_PROTO_1)) {
+ mismatch = 1;
+ break;
}
+ if (remote_minor < 3) {
+ fatal("Remote machine has too old SSH software version.");
+ } else if (remote_minor == 3 || remote_minor == 4) {
+ /* We speak 1.3, too. */
+ enable_compat13();
+ minor1 = 3;
+ if (options.forward_agent) {
+ log("Agent forwarding disabled for protocol 1.3");
+ options.forward_agent = 0;
+ }
+ }
+ break;
+ case 2:
+ if (options.protocol & SSH_PROTO_2) {
+ enable_compat20();
+ break;
+ }
+ /* FALLTHROUGH */
+ default:
+ mismatch = 1;
+ break;
}
-#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)
+ if (mismatch)
fatal("Protocol major versions differ: %d vs. %d",
- PROTOCOL_MAJOR, remote_major);
-#endif
-
+ (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
+ remote_major);
/* Send our own protocol version identification. */
snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
- PROTOCOL_MAJOR, PROTOCOL_MINOR, SSH_VERSION);
+ compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
+ compat20 ? PROTOCOL_MINOR_2 : minor1,
+ SSH_VERSION);
if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf))
fatal("write: %.100s", strerror(errno));
+ client_version_string = xstrdup(buf);
+ chop(client_version_string);
+ chop(server_version_string);
+ debug("Local version string %.100s", client_version_string);
}
-int ssh_cipher_default = SSH_CIPHER_3DES;
-
-int
+/* defaults to 'no' */
+static int
read_yes_or_no(const char *prompt, int defval)
{
char buf[1024];
FILE *f;
int retval = -1;
- if (isatty(0))
+ if (options.batch_mode)
+ return 0;
+
+ if (isatty(STDIN_FILENO))
f = stdin;
else
- f = fopen("/dev/tty", "rw");
+ f = fopen(_PATH_TTY, "rw");
if (f == NULL)
return 0;
while (1) {
fprintf(stderr, "%s", prompt);
if (fgets(buf, sizeof(buf), f) == NULL) {
- /* Print a newline (the prompt probably didn\'t have one). */
+ /*
+ * Print a newline (the prompt probably didn\'t have
+ * one).
+ */
fprintf(stderr, "\n");
strlcpy(buf, "no", sizeof buf);
}
retval = defval;
if (strcmp(buf, "yes") == 0)
retval = 1;
- if (strcmp(buf, "no") == 0)
+ else if (strcmp(buf, "no") == 0)
retval = 0;
+ else
+ fprintf(stderr, "Please type 'yes' or 'no'.\n");
if (retval != -1) {
if (f != stdin)
}
/*
- * check whether the supplied host key is valid, return only if ok.
+ * check whether the supplied host key is valid, return -1 if the key
+ * is not valid. the user_hostfile will not be updated if 'readonly' is true.
*/
-void
-check_host_key(char *host, struct sockaddr *hostaddr, RSA *host_key)
+static int
+check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
+ int readonly, const char *user_hostfile, const char *system_hostfile)
{
- RSA *file_key;
+ Key *file_key;
+ char *type = key_type(host_key);
char *ip = NULL;
- char hostline[1000], *hostp;
+ char hostline[1000], *hostp, *fp;
HostStatus host_status;
HostStatus ip_status;
int local = 0, host_ip_differ = 0;
int salen;
char ntop[NI_MAXHOST];
+ int host_line, ip_line;
+ const char *host_file = NULL, *ip_file = NULL;
/*
* Force accepting of the host key for loopback/localhost. The
* essentially disables host authentication for localhost; however,
* this is probably not a real problem.
*/
+ /** hostaddr == 0! */
switch (hostaddr->sa_family) {
case AF_INET:
- local = (ntohl(((struct sockaddr_in *)hostaddr)->sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
+ local = (ntohl(((struct sockaddr_in *)hostaddr)->
+ sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
salen = sizeof(struct sockaddr_in);
break;
case AF_INET6:
- local = IN6_IS_ADDR_LOOPBACK(&(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
+ local = IN6_IS_ADDR_LOOPBACK(
+ &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
salen = sizeof(struct sockaddr_in6);
break;
default:
salen = sizeof(struct sockaddr_storage);
break;
}
- if (local) {
- debug("Forcing accepting of host key for loopback/localhost.");
- return;
+ if (options.no_host_authentication_for_localhost == 1 && local &&
+ options.host_key_alias == NULL) {
+ debug("Forcing accepting of host key for "
+ "loopback/localhost.");
+ return 0;
}
/*
- * Turn off check_host_ip for proxy connects, since
- * we don't have the remote ip-address
+ * We don't have the remote ip-address for connections
+ * using a proxy command
*/
- if (options.proxy_command != NULL && options.check_host_ip)
- options.check_host_ip = 0;
-
- if (options.check_host_ip) {
+ if (options.proxy_command == NULL) {
if (getnameinfo(hostaddr, salen, ntop, sizeof(ntop),
NULL, 0, NI_NUMERICHOST) != 0)
fatal("check_host_key: getnameinfo failed");
ip = xstrdup(ntop);
+ } else {
+ ip = xstrdup("<no hostip for proxy command>");
+ }
+ /*
+ * Turn off check_host_ip if the connection is to localhost, via proxy
+ * command or if we don't have a hostname to compare with
+ */
+ if (options.check_host_ip &&
+ (local || strcmp(host, ip) == 0 || options.proxy_command != NULL))
+ options.check_host_ip = 0;
+
+ /*
+ * Allow the user to record the key under a different name. This is
+ * useful for ssh tunneling over forwarded connections or if you run
+ * multiple sshd's on different ports on the same machine.
+ */
+ if (options.host_key_alias != NULL) {
+ host = options.host_key_alias;
+ debug("using hostkeyalias: %s", host);
}
/*
* 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();
+ file_key = key_new(host_key->type);
/*
* 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);
+ host_file = user_hostfile;
+ host_status = check_host_in_hostfile(host_file, host, host_key,
+ file_key, &host_line);
+ if (host_status == HOST_NEW) {
+ host_file = system_hostfile;
+ host_status = check_host_in_hostfile(host_file, host, host_key,
+ file_key, &host_line);
+ }
/*
* 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 (options.check_host_ip) {
+ Key *ip_key = key_new(host_key->type);
+
+ ip_file = user_hostfile;
+ ip_status = check_host_in_hostfile(ip_file, ip, host_key,
+ ip_key, &ip_line);
+ if (ip_status == HOST_NEW) {
+ ip_file = system_hostfile;
+ ip_status = check_host_in_hostfile(ip_file, ip,
+ host_key, ip_key, &ip_line);
+ }
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))))
+ (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
host_ip_differ = 1;
- RSA_free(ip_key);
+ key_free(ip_key);
} else
ip_status = host_status;
- RSA_free(file_key);
+ key_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);
+ debug("Host '%.200s' is known and matches the %s host key.",
+ host, type);
+ debug("Found key in %s:%d", host_file, host_line);
+ if (options.check_host_ip && ip_status == HOST_NEW) {
+ if (readonly)
+ log("%s host key for IP address "
+ "'%.128s' not in list of known hosts.",
+ type, ip);
+ else if (!add_host_to_hostfile(user_hostfile, ip,
+ host_key))
+ log("Failed to add the %s host key for IP "
+ "address '%.128s' to the list of known "
+ "hosts (%.30s).", type, ip, user_hostfile);
+ else
+ log("Warning: Permanently added the %s host "
+ "key for IP address '%.128s' to the list "
+ "of known hosts.", type, ip);
}
break;
case HOST_NEW:
+ if (readonly)
+ goto fail;
/* 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);
+ /*
+ * User has requested strict host key checking. We
+ * will not add the host key automatically. The only
+ * alternative left is to abort.
+ */
+ error("No %s host key is known for %.200s and you "
+ "have requested strict checking.", type, host);
+ goto fail;
} else if (options.strict_host_key_checking == 2) {
/* The default */
char prompt[1024];
- char *fp = fingerprint(host_key->e, host_key->n);
+ fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
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");
+ "The authenticity of host '%.200s (%s)' can't be "
+ "established.\n"
+ "%s key fingerprint is %s.\n"
+ "Are you sure you want to continue connecting "
+ "(yes/no)? ", host, ip, type, fp);
+ xfree(fp);
+ if (!read_yes_or_no(prompt, -1)) {
+ log("Aborted by user!");
+ goto fail;
+ }
}
- if (options.check_host_ip && ip_status == HOST_NEW && strcmp(host, ip)) {
+ if (options.check_host_ip && ip_status == HOST_NEW) {
snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
hostp = hostline;
} 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);
+ /*
+ * If not in strict mode, add the key automatically to the
+ * local known_hosts file.
+ */
+ if (!add_host_to_hostfile(user_hostfile, hostp, host_key))
+ log("Failed to add the host to the list of known "
+ "hosts (%.500s).", user_hostfile);
else
- log("Warning: Permanently added '%.200s' to the list of known hosts.",
- hostp);
+ log("Warning: Permanently added '%.200s' (%s) to the "
+ "list of known hosts.", hostp, type);
break;
case HOST_CHANGED:
if (options.check_host_ip && host_ip_differ) {
error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
- error("The host key for %s has changed,", host);
+ error("The %s host key for %s has changed,", type, 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");
+ error("and its host key have changed at the same time.");
+ if (ip_status != HOST_NEW)
+ error("Offending key for IP in %s:%d", ip_file, ip_line);
}
/* The host key has changed. */
+ fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
error("@ WARNING: REMOTE 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("It is also possible that the %s host key has just been changed.", type);
+ error("The fingerprint for the %s key sent by the remote host is\n%s.",
+ type, fp);
error("Please contact your system administrator.");
error("Add correct host key in %.100s to get rid of this message.",
- options.user_hostfile);
+ user_hostfile);
+ error("Offending key in %s:%d", host_file, host_line);
+ xfree(fp);
/*
* 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 (options.strict_host_key_checking) {
+ error("%s host key for %.200s has changed and you have "
+ "requested strict checking.", type, host);
+ goto fail;
+ }
/*
* If strict host key checking has not been requested, allow
* agent forwarding.
*/
if (options.password_authentication) {
- error("Password authentication is disabled to avoid trojan horses.");
+ error("Password authentication is disabled to avoid "
+ "man-in-the-middle attacks.");
options.password_authentication = 0;
}
if (options.forward_agent) {
- error("Agent forwarding is disabled to avoid trojan horses.");
+ error("Agent forwarding is disabled to avoid "
+ "man-in-the-middle attacks.");
options.forward_agent = 0;
}
+ if (options.forward_x11) {
+ error("X11 forwarding is disabled to avoid "
+ "man-in-the-middle attacks.");
+ options.forward_x11 = 0;
+ }
+ if (options.num_local_forwards > 0 ||
+ options.num_remote_forwards > 0) {
+ error("Port forwarding is disabled to avoid "
+ "man-in-the-middle attacks.");
+ options.num_local_forwards =
+ options.num_remote_forwards = 0;
+ }
/*
* XXX Should permit the user to change to use the new id.
* This could be done by converting the host key to an
*/
break;
}
- if (options.check_host_ip)
- xfree(ip);
-}
-
-/*
- * SSH1 key exchange
- */
-void
-ssh_kex(char *host, struct sockaddr *hostaddr)
-{
- int i;
- BIGNUM *key;
- RSA *host_key;
- RSA *public_key;
- int bits, rbits;
- 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);
-
- check_host_key(host, hostaddr, host_key);
-
- 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_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;
+ if (options.check_host_ip && host_status != HOST_CHANGED &&
+ ip_status == HOST_CHANGED) {
+ log("Warning: the %s host key for '%.200s' "
+ "differs from the key for the IP address '%.128s'",
+ type, host, ip);
+ if (host_status == HOST_OK)
+ log("Matching host key in %s:%d", host_file, host_line);
+ log("Offending key for IP in %s:%d", ip_file, ip_line);
+ if (options.strict_host_key_checking == 1) {
+ error("Exiting, you have requested strict checking.");
+ goto fail;
+ } else if (options.strict_host_key_checking == 2) {
+ if (!read_yes_or_no("Are you sure you want "
+ "to continue connecting (yes/no)? ", -1)) {
+ log("Aborted by user!");
+ goto fail;
+ }
}
}
- /* 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);
+ xfree(ip);
+ return 0;
- debug("Received encrypted confirmation.");
+fail:
+ xfree(ip);
+ return -1;
}
-/*
- * Authenticate user
- */
-void
-ssh_userauth(int host_key_valid, RSA *own_host_key,
- uid_t original_real_uid, char *host)
+int
+verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
{
- int i, type;
- int payload_len;
- struct passwd *pw;
- const char *server_user, *local_user;
-
- /* 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;
-
- /* 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;
+ struct stat st;
- /* 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;
+ /* return ok if the key can be found in an old keyfile */
+ if (stat(options.system_hostfile2, &st) == 0 ||
+ stat(options.user_hostfile2, &st) == 0) {
+ if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1,
+ options.user_hostfile2, options.system_hostfile2) == 0)
+ return 0;
}
- /* All authentication methods have failed. Exit with an error message. */
- fatal("Permission denied.");
- /* NOTREACHED */
+ return check_host_key(host, hostaddr, host_key, /*readonly*/ 0,
+ options.user_hostfile, options.system_hostfile);
}
/*
* This function does not require super-user privileges.
*/
void
-ssh_login(int host_key_valid, RSA *own_host_key, const char *orighost,
- struct sockaddr *hostaddr, uid_t original_real_uid)
+ssh_login(Key **keys, int nkeys, const char *orighost,
+ struct sockaddr *hostaddr, struct passwd *pw)
{
char *host, *cp;
+ char *server_user, *local_user;
+
+ local_user = xstrdup(pw->pw_name);
+ server_user = options.user ? options.user : local_user;
/* Convert the user-supplied hostname into all lowercase. */
host = xstrdup(orighost);
/* Put the connection into non-blocking mode. */
packet_set_nonblocking();
- supported_authentications = 0;
/* key exchange */
- ssh_kex(host, hostaddr);
- if (supported_authentications == 0)
- fatal("supported_authentications == 0.");
/* authenticate user */
- ssh_userauth(host_key_valid, own_host_key, original_real_uid, host);
+ if (compat20) {
+ ssh_kex2(host, hostaddr);
+ ssh_userauth2(local_user, server_user, host, keys, nkeys);
+ } else {
+ ssh_kex(host, hostaddr);
+ ssh_userauth1(local_user, server_user, host, keys, nkeys);
+ }
+}
+
+void
+ssh_put_password(char *password)
+{
+ int size;
+ char *padded;
+
+ if (datafellows & SSH_BUG_PASSWORDPAD) {
+ packet_put_cstring(password);
+ return;
+ }
+ size = roundup(strlen(password) + 1, 32);
+ padded = xmalloc(size);
+ memset(padded, 0, size);
+ strlcpy(padded, password, size);
+ packet_put_string(padded, size);
+ memset(padded, 0, size);
+ xfree(padded);
}
andersk / openssh.git / blobdiff