- djm@cvs.openbsd.org 2010/11/29 23:45:51

     [auth.c hostfile.c hostfile.h ssh.c ssh_config.5 sshconnect.c]
     [sshconnect.h sshconnect2.c]
     automatically order the hostkeys requested by the client based on
     which hostkeys are already recorded in known_hosts. This avoids
     hostkey warnings when connecting to servers with new ECDSA keys
     that are preferred by default; with markus@

1 files changed, 153 insertions, 138 deletions

diff --git a/sshconnect.c b/sshconnect.c
index 78068c602..064bb74b3 100644
--- a/sshconnect.c
+++ b/sshconnect.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshconnect.c,v 1.228 2010/10/06 21:10:21 djm Exp $ */
+/* $OpenBSD: sshconnect.c,v 1.229 2010/11/29 23:45:51 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -75,7 +75,7 @@ extern char *__progname;
 extern uid_t original_real_uid;
 extern uid_t original_effective_uid;
 
-static int show_other_keys(const char *, Key *);
+static int show_other_keys(struct hostkeys *, Key *);
 static void warn_changed_key(Key *);
 
 /*
@@ -607,6 +607,79 @@ check_host_cert(const char *host, const Key *host_key)
         return 1;
 }
 
+static int
+sockaddr_is_local(struct sockaddr *hostaddr)
+{
+        switch (hostaddr->sa_family) {
+        case AF_INET:
+                return (ntohl(((struct sockaddr_in *)hostaddr)->
+                    sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
+        case AF_INET6:
+                return IN6_IS_ADDR_LOOPBACK(
+                    &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
+        default:
+                return 0;
+        }
+}
+
+/*
+ * Prepare the hostname and ip address strings that are used to lookup
+ * host keys in known_hosts files. These may have a port number appended.
+ */
+void
+get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr,
+    u_short port, char **hostfile_hostname, char **hostfile_ipaddr)
+{
+        char ntop[NI_MAXHOST];
+        socklen_t addrlen;
+
+        switch (hostaddr == NULL ? -1 : hostaddr->sa_family) {
+        case -1:
+                addrlen = 0;
+                break;
+        case AF_INET:
+                addrlen = sizeof(struct sockaddr_in);
+                break;
+        case AF_INET6:
+                addrlen = sizeof(struct sockaddr_in6);
+                break;
+        default:
+                addrlen = sizeof(struct sockaddr);
+                break;
+        }
+
+        /*
+         * We don't have the remote ip-address for connections
+         * using a proxy command
+         */
+        if (hostfile_ipaddr != NULL) {
+                if (options.proxy_command == NULL) {
+                        if (getnameinfo(hostaddr, addrlen,
+                            ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0)
+                        fatal("check_host_key: getnameinfo failed");
+                        *hostfile_ipaddr = put_host_port(ntop, port);
+                } else {
+                        *hostfile_ipaddr = xstrdup("<no hostip for proxy "
+                            "command>");
+                }
+        }
+
+        /*
+         * Allow the user to record the key under a different name or
+         * differentiate a non-standard port.  This is useful for ssh
+         * tunneling over forwarded connections or if you run multiple
+         * sshd's on different ports on the same machine.
+         */
+        if (hostfile_hostname != NULL) {
+                if (options.host_key_alias != NULL) {
+                        *hostfile_hostname = xstrdup(options.host_key_alias);
+                        debug("using hostkeyalias: %s", *hostfile_hostname);
+                } else {
+                        *hostfile_hostname = put_host_port(hostname, port);
+                }
+        }
+}
+
 /*
  * 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.
@@ -616,21 +689,21 @@ check_host_cert(const char *host, const Key *host_key)
 #define ROQUIET 2
 static int
 check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
-    Key *host_key, int readonly, const char *user_hostfile,
-    const char *system_hostfile)
+    Key *host_key, int readonly, char *user_hostfile,
+    char *system_hostfile)
 {
-        Key *file_key, *raw_key = NULL;
+        Key *raw_key = NULL;
         const char *type;
         char *ip = NULL, *host = NULL;
         char hostline[1000], *hostp, *fp, *ra;
         HostStatus host_status;
         HostStatus ip_status;
-        int r, want_cert, local = 0, host_ip_differ = 0;
-        int salen;
-        char ntop[NI_MAXHOST];
+        int r, want_cert = key_is_cert(host_key), host_ip_differ = 0;
+        int local = sockaddr_is_local(hostaddr);
         char msg[1024];
-        int len, host_line, ip_line, cancelled_forwarding = 0;
-        const char *host_file = NULL, *ip_file = NULL;
+        int len, cancelled_forwarding = 0;
+        struct hostkeys *host_hostkeys, *ip_hostkeys;
+        const struct hostkey_entry *host_found, *ip_found;
 
         /*
          * Force accepting of the host key for loopback/localhost. The
@@ -640,23 +713,6 @@ check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
          * 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;
-                salen = sizeof(struct sockaddr_in);
-                break;
-        case AF_INET6:
-                local = IN6_IS_ADDR_LOOPBACK(
-                    &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
-                salen = sizeof(struct sockaddr_in6);
-                break;
-        default:
-                local = 0;
-                salen = sizeof(struct sockaddr_storage);
-                break;
-        }
         if (options.no_host_authentication_for_localhost == 1 && local &&
             options.host_key_alias == NULL) {
                 debug("Forcing accepting of host key for "
@@ -665,17 +721,10 @@ check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
         }
 
         /*
-         * We don't have the remote ip-address for connections
-         * using a proxy command
+         * Prepare the hostname and address strings used for hostkey lookup.
+         * In some cases, these will have a port number appended.
          */
-        if (options.proxy_command == NULL) {
-                if (getnameinfo(hostaddr, salen, ntop, sizeof(ntop),
-                    NULL, 0, NI_NUMERICHOST) != 0)
-                        fatal("check_host_key: getnameinfo failed");
-                ip = put_host_port(ntop, port);
-        } else {
-                ip = xstrdup("<no hostip for proxy command>");
-        }
+        get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
 
         /*
          * Turn off check_host_ip if the connection is to localhost, via proxy
@@ -685,74 +734,52 @@ check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
             strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
                 options.check_host_ip = 0;
 
-        /*
-         * Allow the user to record the key under a different name or
-         * differentiate a non-standard port.  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 = xstrdup(options.host_key_alias);
-                debug("using hostkeyalias: %s", host);
-        } else {
-                host = put_host_port(hostname, port);
+        host_hostkeys = init_hostkeys();
+        load_hostkeys(host_hostkeys, host, user_hostfile);
+        load_hostkeys(host_hostkeys, host, system_hostfile);
+
+        ip_hostkeys = NULL;
+        if (!want_cert && options.check_host_ip) {
+                ip_hostkeys = init_hostkeys();
+                load_hostkeys(ip_hostkeys, ip, user_hostfile);
+                load_hostkeys(ip_hostkeys, ip, system_hostfile);
         }
 
  retry:
+        /* Reload these as they may have changed on cert->key downgrade */
         want_cert = key_is_cert(host_key);
         type = key_type(host_key);
 
         /*
-         * 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 = key_new(key_is_cert(host_key) ? KEY_UNSPEC : host_key->type);
-
-        /*
          * Check if the host key is present in the user's list of known
          * 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);
-        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_key_in_hostkeys(host_hostkeys, host_key,
+            &host_found);
+
         /*
          * Also perform check for the ip address, skip the check if we are
          * localhost, looking for a certificate, or the hostname was an ip
          * address to begin with.
          */
-        if (!want_cert && 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 (!want_cert && ip_hostkeys != NULL) {
+                ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
+                    &ip_found);
                 if (host_status == HOST_CHANGED &&
-                    (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
+                    (ip_status != HOST_CHANGED || 
+                    (ip_found != NULL &&
+                    !key_equal(ip_found->key, host_found->key))))
                         host_ip_differ = 1;
-
-                key_free(ip_key);
         } else
                 ip_status = host_status;
 
-        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 %s host %s.",
                     host, type, want_cert ? "certificate" : "key");
-                debug("Found %s in %s:%d",
-                    want_cert ? "CA key" : "key", host_file, host_line);
+                debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
+                    host_found->file, host_found->line);
                 if (want_cert && !check_host_cert(hostname, host_key))
                         goto fail;
                 if (options.check_host_ip && ip_status == HOST_NEW) {
@@ -803,7 +830,7 @@ check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
                 } else if (options.strict_host_key_checking == 2) {
                         char msg1[1024], msg2[1024];
 
-                        if (show_other_keys(host, host_key))
+                        if (show_other_keys(host_hostkeys, host_key))
                                 snprintf(msg1, sizeof(msg1),
                                     "\nbut keys of different type are already"
                                     " known for this host.");
@@ -844,8 +871,7 @@ check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
                  * local known_hosts file.
                  */
                 if (options.check_host_ip && ip_status == HOST_NEW) {
-                        snprintf(hostline, sizeof(hostline), "%s,%s",
-                            host, ip);
+                        snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
                         hostp = hostline;
                         if (options.hash_known_hosts) {
                                 /* Add hash of host and IP separately */
@@ -899,8 +925,8 @@ check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
                          * all hosts that one might visit.
                          */
                         debug("Host certificate authority does not "
-                            "match %s in %s:%d", CA_MARKER,
-                            host_file, host_line);
+                            "match %s in %s:%lu", CA_MARKER,
+                            host_found->file, host_found->line);
                         goto fail;
                 }
                 if (readonly == ROQUIET)
@@ -922,13 +948,15 @@ check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
                         error("DNS SPOOFING is happening or the IP address for the host");
                         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);
+                                error("Offending key for IP in %s:%lu",
+                                    ip_found->file, ip_found->line);
                 }
                 /* The host key has changed. */
                 warn_changed_key(host_key);
                 error("Add correct host key in %.100s to get rid of this message.",
                     user_hostfile);
-                error("Offending key in %s:%d", host_file, host_line);
+                error("Offending %s key in %s:%lu", key_type(host_found->key),
+                    host_found->file, host_found->line);
 
                 /*
                  * If strict host key checking is in use, the user will have
@@ -1013,13 +1041,13 @@ check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
                 snprintf(msg, sizeof(msg),
                     "Warning: the %s host key for '%.200s' "
                     "differs from the key for the IP address '%.128s'"
-                    "\nOffending key for IP in %s:%d",
-                    type, host, ip, ip_file, ip_line);
+                    "\nOffending key for IP in %s:%lu",
+                    type, host, ip, ip_found->file, ip_found->line);
                 if (host_status == HOST_OK) {
                         len = strlen(msg);
                         snprintf(msg + len, sizeof(msg) - len,
-                            "\nMatching host key in %s:%d",
-                            host_file, host_line);
+                            "\nMatching host key in %s:%lu",
+                            host_found->file, host_found->line);
                 }
                 if (options.strict_host_key_checking == 1) {
                         logit("%s", msg);
@@ -1037,6 +1065,10 @@ check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
 
         xfree(ip);
         xfree(host);
+        if (host_hostkeys != NULL)
+                free_hostkeys(host_hostkeys);
+        if (ip_hostkeys != NULL)
+                free_hostkeys(ip_hostkeys);
         return 0;
 
 fail:
@@ -1056,6 +1088,10 @@ fail:
                 key_free(raw_key);
         xfree(ip);
         xfree(host);
+        if (host_hostkeys != NULL)
+                free_hostkeys(host_hostkeys);
+        if (ip_hostkeys != NULL)
+                free_hostkeys(ip_hostkeys);
         return -1;
 }
 
@@ -1065,6 +1101,11 @@ verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
 {
         struct stat st;
         int flags = 0;
+        char *fp;
+
+        fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
+        debug("Server host key: %s %s", key_type(host_key), fp);
+        xfree(fp);
 
         /* XXX certs are not yet supported for DNS */
         if (!key_is_cert(host_key) && options.verify_host_key_dns &&
@@ -1108,7 +1149,7 @@ verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
  */
 void
 ssh_login(Sensitive *sensitive, const char *orighost,
-    struct sockaddr *hostaddr, struct passwd *pw, int timeout_ms)
+    struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
 {
         char *host, *cp;
         char *server_user, *local_user;
@@ -1131,7 +1172,7 @@ ssh_login(Sensitive *sensitive, const char *orighost,
         /* key exchange */
         /* authenticate user */
         if (compat20) {
-                ssh_kex2(host, hostaddr);
+                ssh_kex2(host, hostaddr, port);
                 ssh_userauth2(local_user, server_user, host, sensitive);
         } else {
                 ssh_kex(host, hostaddr);
@@ -1158,61 +1199,35 @@ ssh_put_password(char *password)
         xfree(padded);
 }
 
-static int
-show_key_from_file(const char *file, const char *host, int keytype)
-{
-        Key *found;
-        char *fp, *ra;
-        int line, ret;
-
-        found = key_new(keytype);
-        if ((ret = lookup_key_in_hostfile_by_type(file, host,
-            keytype, found, &line))) {
-                fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
-                ra = key_fingerprint(found, SSH_FP_MD5, SSH_FP_RANDOMART);
-                logit("WARNING: %s key found for host %s\n"
-                    "in %s:%d\n"
-                    "%s key fingerprint %s.\n%s\n",
-                    key_type(found), host, file, line,
-                    key_type(found), fp, ra);
-                xfree(ra);
-                xfree(fp);
-        }
-        key_free(found);
-        return (ret);
-}
-
 /* print all known host keys for a given host, but skip keys of given type */
 static int
-show_other_keys(const char *host, Key *key)
+show_other_keys(struct hostkeys *hostkeys, Key *key)
 {
         int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, KEY_ECDSA, -1};
-        int i, found = 0;
+        int i, ret = 0;
+        char *fp, *ra;
+        const struct hostkey_entry *found;
 
         for (i = 0; type[i] != -1; i++) {
                 if (type[i] == key->type)
                         continue;
-                if (type[i] != KEY_RSA1 &&
-                    show_key_from_file(options.user_hostfile2, host, type[i])) {
-                        found = 1;
-                        continue;
-                }
-                if (type[i] != KEY_RSA1 &&
-                    show_key_from_file(options.system_hostfile2, host, type[i])) {
-                        found = 1;
-                        continue;
-                }
-                if (show_key_from_file(options.user_hostfile, host, type[i])) {
-                        found = 1;
+                if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found))
                         continue;
-                }
-                if (show_key_from_file(options.system_hostfile, host, type[i])) {
-                        found = 1;
-                        continue;
-                }
-                debug2("no key of type %d for host %s", type[i], host);
+                fp = key_fingerprint(found->key, SSH_FP_MD5, SSH_FP_HEX);
+                ra = key_fingerprint(found->key, SSH_FP_MD5, SSH_FP_RANDOMART);
+                logit("WARNING: %s key found for host %s\n"
+                    "in %s:%lu\n"
+                    "%s key fingerprint %s.",
+                    key_type(found->key),
+                    found->host, found->file, found->line,
+                    key_type(found->key), fp);
+                if (options.visual_host_key)
+                        logit("%s", ra);
+                xfree(ra);
+                xfree(fp);
+                ret = 1;
         }
-        return (found);
+        return ret;
 }
 
 static void