- markus@cvs.openbsd.org 2001/06/23 02:34:33

     [kexdh.c kexgex.c kex.h pathnames.h readconf.c servconf.h ssh.1
      sshconnect1.c sshconnect2.c sshconnect.c sshconnect.h sshd.8]
     get rid of known_hosts2, use it for hostkey lookup, but do not
     modify.

1 files changed, 105 insertions, 42 deletions

diff --git a/sshconnect.c b/sshconnect.c
index bafdec95a..1766de0c3 100644
--- a/sshconnect.c
+++ b/sshconnect.c
@@ -13,7 +13,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: sshconnect.c,v 1.107 2001/06/07 20:23:05 markus Exp $");
+RCSID("$OpenBSD: sshconnect.c,v 1.108 2001/06/23 02:34:31 markus Exp $");
 
 #include <openssl/bn.h>
 
@@ -467,7 +467,10 @@ read_yes_or_no(const char *prompt, int defval)
         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);
                 }
@@ -493,12 +496,13 @@ read_yes_or_no(const char *prompt, int defval)
 }
 
 /*
- * 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
+int
 check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
-        const char *user_hostfile, const char *system_hostfile)
+    int readonly, const char *user_hostfile, const char *system_hostfile)
 {
         Key *file_key;
         char *type = key_type(host_key);
@@ -523,11 +527,13 @@ check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
         /**  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:
@@ -538,7 +544,7 @@ check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
         if (local && options.host_key_alias == NULL) {
                 debug("Forcing accepting of host key for "
                     "loopback/localhost.");
-                return;
+                return 0;
         }
 
         /*
@@ -582,10 +588,12 @@ check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
          * hosts or in the systemwide list.
          */
         host_file = user_hostfile;
-        host_status = check_host_in_hostfile(host_file, host, host_key, file_key, &host_line);
+        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);
+                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
@@ -595,10 +603,12 @@ check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
                 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);
+                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);
+                        ip_status = check_host_in_hostfile(ip_file, ip,
+                            host_key, ip_key, &ip_line);
                 }
                 if (host_status == HOST_CHANGED &&
                     (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
@@ -617,32 +627,49 @@ check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
                     host, type);
                 debug("Found key in %s:%d", host_file, host_line);
                 if (options.check_host_ip && ip_status == HOST_NEW) {
-                        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.",
+                        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 %s host key is known for %.200s and you have requested strict checking.", type, 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];
                         fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
                         snprintf(prompt, sizeof(prompt),
-                            "The authenticity of host '%.200s (%s)' can't be established.\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);
+                            "Are you sure you want to continue connecting "
+                            "(yes/no)? ", host, ip, type, fp);
                         xfree(fp);
-                        if (!read_yes_or_no(prompt, -1))
-                                fatal("Aborted by user!");
+                        if (!read_yes_or_no(prompt, -1)) {
+                                log("Aborted by user!");
+                                goto fail;
+                        }
                 }
                 if (options.check_host_ip && ip_status == HOST_NEW) {
                         snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
@@ -650,13 +677,16 @@ check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
                 } else
                         hostp = host;
 
-                /* If not in strict mode, add the key automatically to the local known_hosts file. */
+                /*
+                 * 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);
+                        log("Failed to add the host to the list of known "
+                            "hosts (%.500s).", user_hostfile);
                 else
-                        log("Warning: Permanently added '%.200s' (%s) to the list of known hosts.",
-                            hostp, type);
+                        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) {
@@ -698,8 +728,11 @@ check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
                  * 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("%s host key for %.200s has changed and you have requested strict checking.", type, 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
@@ -707,20 +740,26 @@ check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
                  * 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 trojan horses.");
+                        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 trojan horses.");
-                        options.num_local_forwards = options.num_remote_forwards = 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.
@@ -741,15 +780,39 @@ check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
                         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) {
-                        fatal("Exiting, you have requested strict checking.");
+                        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))
-                                fatal("Aborted by user!");
+                        if (!read_yes_or_no("Are you sure you want " 
+                            "to continue connecting (yes/no)? ", -1)) {
+                                log("Aborted by user!");
+                                goto fail;
+                        }
                 }
         }
 
         xfree(ip);
+        return 0;
+
+fail:
+        xfree(ip);
+        return -1;
+}
+
+int
+verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
+{
+        struct stat st;
+
+        /* 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;
+        }
+        return check_host_key(host, hostaddr, host_key, /*readonly*/ 0,
+            options.user_hostfile, options.system_hostfile);
 }
 
 /*