1 files changed, 157 insertions, 28 deletions

diff --git a/sshconnect.c b/sshconnect.c
index 013a896b7..5c56f3178 100644
--- a/sshconnect.c
+++ b/sshconnect.c
@@ -13,7 +13,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: sshconnect.c,v 1.137 2002/11/21 23:03:51 deraadt Exp $");
+RCSID("$OpenBSD: sshconnect.c,v 1.148 2003/09/18 07:52:54 markus Exp $");
 
 #include <openssl/bn.h>
 
@@ -33,9 +33,17 @@ RCSID("$OpenBSD: sshconnect.c,v 1.137 2002/11/21 23:03:51 deraadt Exp $");
 #include "misc.h"
 #include "readpass.h"
 
+#ifdef DNS
+#include "dns.h"
+#endif
+
 char *client_version_string = NULL;
 char *server_version_string = NULL;
 
+#ifdef DNS
+int verified_host_key_dns = 0;
+#endif
+
 /* import */
 extern Options options;
 extern char *__progname;
@@ -170,7 +178,7 @@ ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
  * Creates a (possibly privileged) socket for use as the ssh connection.
  */
 static int
-ssh_create_socket(int privileged, int family)
+ssh_create_socket(int privileged, struct addrinfo *ai)
 {
         int sock, gaierr;
         struct addrinfo hints, *res;
@@ -182,15 +190,16 @@ ssh_create_socket(int privileged, int family)
         if (privileged) {
                 int p = IPPORT_RESERVED - 1;
                 PRIV_START;
-                sock = rresvport_af(&p, family);
+                sock = rresvport_af(&p, ai->ai_family);
                 PRIV_END;
                 if (sock < 0)
-                        error("rresvport: af=%d %.100s", family, strerror(errno));
+                        error("rresvport: af=%d %.100s", ai->ai_family,
+                            strerror(errno));
                 else
                         debug("Allocated local port %d.", p);
                 return sock;
         }
-        sock = socket(family, SOCK_STREAM, 0);
+        sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
         if (sock < 0)
                 error("socket: %.100s", strerror(errno));
 
@@ -199,8 +208,9 @@ ssh_create_socket(int privileged, int family)
                 return sock;
 
         memset(&hints, 0, sizeof(hints));
-        hints.ai_family = family;
-        hints.ai_socktype = SOCK_STREAM;
+        hints.ai_family = ai->ai_family;
+        hints.ai_socktype = ai->ai_socktype;
+        hints.ai_protocol = ai->ai_protocol;
         hints.ai_flags = AI_PASSIVE;
         gaierr = getaddrinfo(options.bind_address, "0", &hints, &res);
         if (gaierr) {
@@ -219,6 +229,74 @@ ssh_create_socket(int privileged, int family)
         return sock;
 }
 
+static int
+timeout_connect(int sockfd, const struct sockaddr *serv_addr,
+    socklen_t addrlen, int timeout)
+{
+        fd_set *fdset;
+        struct timeval tv;
+        socklen_t optlen;
+        int fdsetsz, optval, rc, result = -1;
+
+        if (timeout <= 0)
+                return (connect(sockfd, serv_addr, addrlen));
+
+        if (fcntl(sockfd, F_SETFL, O_NONBLOCK) < 0)
+                return (-1);
+
+        rc = connect(sockfd, serv_addr, addrlen);
+        if (rc == 0)
+                return (0);
+        if (errno != EINPROGRESS)
+                return (-1);
+
+        fdsetsz = howmany(sockfd + 1, NFDBITS) * sizeof(fd_mask);
+        fdset = (fd_set *)xmalloc(fdsetsz);
+
+        memset(fdset, 0, fdsetsz);
+        FD_SET(sockfd, fdset);
+        tv.tv_sec = timeout;
+        tv.tv_usec = 0;
+
+        for(;;) {
+                rc = select(sockfd + 1, NULL, fdset, NULL, &tv);
+                if (rc != -1 || errno != EINTR)
+                        break;
+        }
+
+        switch(rc) {
+        case 0:
+                /* Timed out */
+                errno = ETIMEDOUT;
+                break;
+        case -1:
+                /* Select error */
+                debug("select: %s", strerror(errno));
+                break;
+        case 1:
+                /* Completed or failed */
+                optval = 0;
+                optlen = sizeof(optval);
+                if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval, 
+                    &optlen) == -1) {
+                        debug("getsockopt: %s", strerror(errno));
+                        break;
+                }
+                if (optval != 0) {
+                        errno = optval;
+                        break;
+                }
+                result = 0;
+                break;
+        default:
+                /* Should not occur */
+                fatal("Bogus return (%d) from select()", rc);
+        }
+
+        xfree(fdset);
+        return (result);
+}
+
 /*
  * Opens a TCP/IP connection to the remote server on the given host.
  * The address of the remote host will be returned in hostaddr.
@@ -302,12 +380,13 @@ ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
                                 host, ntop, strport);
 
                         /* Create a socket for connecting. */
-                        sock = ssh_create_socket(needpriv, ai->ai_family);
+                        sock = ssh_create_socket(needpriv, ai);
                         if (sock < 0)
                                 /* Any error is already output */
                                 continue;
 
-                        if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) {
+                        if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
+                            options.connection_timeout) >= 0) {
                                 /* Successful connection. */
                                 memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
                                 break;
@@ -339,7 +418,7 @@ ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
 
         /* Return failure if we didn't get a successful connection. */
         if (attempt >= connection_attempts) {
-                log("ssh: connect to host %s port %s: %s",
+                logit("ssh: connect to host %s port %s: %s",
                     host, strport, strerror(errno));
                 return full_failure ? ECONNABORTED : ECONNREFUSED;
         }
@@ -453,7 +532,7 @@ ssh_exchange_identification(void)
                         enable_compat13();
                         minor1 = 3;
                         if (options.forward_agent) {
-                                log("Agent forwarding disabled for protocol 1.3");
+                                logit("Agent forwarding disabled for protocol 1.3");
                                 options.forward_agent = 0;
                         }
                 }
@@ -477,7 +556,7 @@ ssh_exchange_identification(void)
             compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
             compat20 ? PROTOCOL_MINOR_2 : minor1,
             SSH_VERSION);
-        if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf))
+        if (atomicio(vwrite, connection_out, buf, strlen(buf)) != strlen(buf))
                 fatal("write: %.100s", strerror(errno));
         client_version_string = xstrdup(buf);
         chop(client_version_string);
@@ -528,7 +607,7 @@ check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
         int salen;
         char ntop[NI_MAXHOST];
         char msg[1024];
-        int len, host_line, ip_line, has_keys;
+        int len, host_line, ip_line;
         const char *host_file = NULL, *ip_file = NULL;
 
         /*
@@ -644,16 +723,16 @@ check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
                 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 "
+                                logit("%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 "
+                                logit("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 "
+                                logit("Warning: Permanently added the %s host "
                                     "key for IP address '%.128s' to the list "
                                     "of known hosts.", type, ip);
                 }
@@ -672,19 +751,36 @@ check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
                             "have requested strict checking.", type, host);
                         goto fail;
                 } else if (options.strict_host_key_checking == 2) {
-                        has_keys = show_other_keys(host, host_key);
+                        char msg1[1024], msg2[1024];
+
+                        if (show_other_keys(host, host_key))
+                                snprintf(msg1, sizeof(msg1),
+                                   "\nbut keys of different type are already"
+                                   " known for this host.");
+                        else
+                                snprintf(msg1, sizeof(msg1), ".");
                         /* The default */
                         fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
+                        msg2[0] = '\0';
+#ifdef DNS
+                        if (options.verify_host_key_dns) {
+                                if (verified_host_key_dns)
+                                        snprintf(msg2, sizeof(msg2),
+                                            "Matching host key fingerprint"
+                                            " found in DNS.\n");
+                                else
+                                        snprintf(msg2, sizeof(msg2),
+                                            "No matching host key fingerprint"
+                                            " found in DNS.\n");
+                        }
+#endif
                         snprintf(msg, sizeof(msg),
                             "The authenticity of host '%.200s (%s)' can't be "
                             "established%s\n"
-                            "%s key fingerprint is %s.\n"
+                            "%s key fingerprint is %s.\n%s"
                             "Are you sure you want to continue connecting "
                             "(yes/no)? ",
-                            host, ip,
-                            has_keys ? ",\nbut keys of different type are already "
-                            "known for this host." : ".",
-                            type, fp);
+                            host, ip, msg1, type, fp, msg2);
                         xfree(fp);
                         if (!confirm(msg))
                                 goto fail;
@@ -700,10 +796,10 @@ check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
                  * 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 "
+                        logit("Failed to add the host to the list of known "
                             "hosts (%.500s).", user_hostfile);
                 else
-                        log("Warning: Permanently added '%.200s' (%s) to the "
+                        logit("Warning: Permanently added '%.200s' (%s) to the "
                             "list of known hosts.", hostp, type);
                 break;
         case HOST_CHANGED:
@@ -754,7 +850,7 @@ check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
 
                 /*
                  * If strict host key checking has not been requested, allow
-                 * the connection but without password authentication or
+                 * the connection but without MITM-able authentication or
                  * agent forwarding.
                  */
                 if (options.password_authentication) {
@@ -762,6 +858,17 @@ check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
                             "man-in-the-middle attacks.");
                         options.password_authentication = 0;
                 }
+                if (options.kbd_interactive_authentication) {
+                        error("Keyboard-interactive authentication is disabled"
+                            " to avoid man-in-the-middle attacks.");
+                        options.kbd_interactive_authentication = 0;
+                        options.challenge_response_authentication = 0;
+                }
+                if (options.challenge_response_authentication) {
+                        error("Challenge/response authentication is disabled"
+                            " to avoid man-in-the-middle attacks.");
+                        options.challenge_response_authentication = 0;
+                }
                 if (options.forward_agent) {
                         error("Agent forwarding is disabled to avoid "
                             "man-in-the-middle attacks.");
@@ -806,7 +913,7 @@ check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
                             host_file, host_line);
                 }
                 if (options.strict_host_key_checking == 1) {
-                        log(msg);
+                        logit("%s", msg);
                         error("Exiting, you have requested strict checking.");
                         goto fail;
                 } else if (options.strict_host_key_checking == 2) {
@@ -815,7 +922,7 @@ check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
                         if (!confirm(msg))
                                 goto fail;
                 } else {
-                        log(msg);
+                        logit("%s", msg);
                 }
         }
 
@@ -827,11 +934,33 @@ fail:
         return -1;
 }
 
+/* returns 0 if key verifies or -1 if key does NOT verify */
 int
 verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
 {
         struct stat st;
 
+#ifdef DNS
+        if (options.verify_host_key_dns) {
+                switch(verify_host_key_dns(host, hostaddr, host_key)) {
+                case DNS_VERIFY_OK:
+#ifdef DNSSEC
+                        return 0;
+#else
+                        verified_host_key_dns = 1;
+                        break;
+#endif
+                case DNS_VERIFY_FAILED:
+                        return -1;
+                case DNS_VERIFY_ERROR:
+                        break;
+                default:
+                        debug3("bad return value from verify_host_key_dns");
+                        break;
+                }
+        }
+#endif /* DNS */
+
         /* 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) {
@@ -913,7 +1042,7 @@ show_key_from_file(const char *file, const char *host, int keytype)
         if ((ret = lookup_key_in_hostfile_by_type(file, host,
             keytype, found, &line))) {
                 fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
-                log("WARNING: %s key found for host %s\n"
+                logit("WARNING: %s key found for host %s\n"
                     "in %s:%d\n"
                     "%s key fingerprint %s.",
                     key_type(found), host, file, line,