don't use the resolver to determine the full hostname of the target

host because DNS resolution of remote hostnames is insecure; instead,
use what was given on the command-line, except switch localhost
to the full localhostname and expand short hostnames according to the
local domainname

diff --git a/openssh/gss-genr.c b/openssh/gss-genr.c
index d00b73ef27d6a02eeee6b6b0f53bf6270ad96496..5e5dc0ed2457aae915b0b9388135a4238c34b59e 100644 (file)
--- a/openssh/gss-genr.c
+++ b/openssh/gss-genr.c
@@ -38,6 +38,7 @@
 #include "log.h"
 #include "compat.h"
 #include "monitor_wrap.h"
+#include "canohost.h"
 
 #include <netdb.h>
 
@@ -442,49 +443,20 @@ OM_uint32
 ssh_gssapi_import_name(Gssctxt *ctx, const char *host) {
        gss_buffer_desc gssbuf = {0,NULL};
        OM_uint32 maj_status, min_status;
-       struct hostent *hostinfo = NULL;
-       char *xhost, *addr;
+       char *xhost;
        
        /* Make a copy of the host name, in case it was returned by a
         * previous call to gethostbyname(). */ 
        xhost = xstrdup(host);
 
-       /* Make sure we have the FQDN. Some GSSAPI implementations don't do
+       /* If xhost is the loopback interface, switch it to our
+          true local hostname. */
+       resolve_localhost(&xhost);
+
+       /* Make sure we have the FQHN. Some GSSAPI implementations don't do
         * this for us themselves */
-       hostinfo = gethostbyname(xhost);
-       
-       /* Use local hostname when coming in on loopback interface because
-          we won't have 'localhost' credentials. */
-       if (hostinfo &&
-           hostinfo->h_addrtype == AF_INET) {
-           struct in_addr addr;
-           addr = *(struct in_addr *)(hostinfo->h_addr);
-           if (ntohl(addr.s_addr) == INADDR_LOOPBACK) {
-               char buf[4096];
-               if (gethostname(buf, 4096) == 0) {
-                   hostinfo = gethostbyname(buf);
-               }
-           }
-       }
+       make_fqhn(&xhost);
 
-       /* Go to the resolver to get the official hostname for our target.
-          WARNING: This makes us vulnerable to DNS spoofing. */
-       if ((hostinfo == NULL) || (hostinfo->h_name == NULL)) {
-               debug("Unable to get FQDN for \"%s\"", xhost);
-       } else {
-               addr = xmalloc(hostinfo->h_length);
-               memcpy(addr, hostinfo->h_addr, hostinfo->h_length);
-               hostinfo = gethostbyaddr(addr, hostinfo->h_length,
-                                        hostinfo->h_addrtype);
-               xfree(addr);
-               if ((hostinfo == NULL) || (hostinfo->h_name == NULL)) {
-                   debug("Unable to get FQDN for \"%s\"", xhost);
-               } else {
-                   xfree(xhost);
-                   xhost = xstrdup(hostinfo->h_name);
-               }
-       }
-               
         gssbuf.length = sizeof("host@")+strlen(xhost);
 
         gssbuf.value = xmalloc(gssbuf.length);

diff --git a/openssh/sshconnect1.c b/openssh/sshconnect1.c
index c4b76c0e10c8dced6f4d12c371efdf09f4c0f7e9..605658ba367a4a5a85f92107906c7b402bcc0341 100644 (file)
--- a/openssh/sshconnect1.c
+++ b/openssh/sshconnect1.c
@@ -1086,44 +1086,20 @@ int try_gssapi_authentication(char *host, Options *options)
   OM_uint32 ret_flags;
   int type;
   char *gssapi_auth_type = NULL;
-  struct hostent *hostinfo;
-  char *addr;
+  char *xhost;
   unsigned int slen;
 
-  /*
-   * host is not guarenteed to be a FQDN, so we need to make sure it is.
-   */
-  hostinfo = gethostbyname(host);
-
-  /* Use local hostname when coming in on loopback interface because
-     we won't have 'localhost' credentials. */
-  if (hostinfo && hostinfo->h_addrtype == AF_INET) {
-      struct in_addr addr;
-      addr = *(struct in_addr *)(hostinfo->h_addr);
-      if (ntohl(addr.s_addr) == INADDR_LOOPBACK) {
-         char buf[4096];
-         if (gethostname(buf, 4096) == 0) {
-             hostinfo = gethostbyname(buf);
-         }
-      }
-  }
-
-  if ((hostinfo == NULL) || (hostinfo->h_addr == NULL)) {
-      debug("GSSAPI authentication: Unable to get FQDN for \"%s\"", host);
-      goto cleanup;
-  }
+  /* Make a copy of the host name, in case it was returned by a
+   * previous call to gethostbyname(). */      
+  xhost = xstrdup(host);
 
-  addr = xmalloc(hostinfo->h_length);
-  memcpy(addr, hostinfo->h_addr, hostinfo->h_length);
-  hostinfo = gethostbyaddr(addr, hostinfo->h_length, AF_INET);
-  xfree(addr);
+  /* If xhost is the loopback interface, switch it to our
+     true local hostname. */
+  resolve_localhost(&xhost);
 
-  /* Go to the resolver to get the official hostname for our target.
-     WARNING: This makes us vulnerable to DNS spoofing. */
-  if ((hostinfo == NULL) || (hostinfo->h_name == NULL)) {
-      debug("GSSAPI authentication: Unable to get FQDN for \"%s\"", host);
-      goto cleanup;
-  }
+  /* Make sure we have the FQHN. Some GSSAPI implementations don't do
+   * this for us themselves */
+  make_fqhn(&xhost);
 
   /*
    * Default flags
@@ -1152,17 +1128,14 @@ int try_gssapi_authentication(char *host, Options *options)
 
   debug("Attempting %s authentication", gssapi_auth_type);
 
-  service_name = (char *) malloc(strlen("host") +
-                                 strlen(hostinfo->h_name) +
-                                 2 /* 1 for '@', 1 for NUL */);
-
-  if (service_name == NULL) {
-    debug("malloc() failed");
-    goto cleanup;
-  }
+  service_name = (char *) xmalloc(strlen("host") +
+                                 strlen(xhost) +
+                                 2 /* 1 for '@', 1 for NUL */);
 
+  sprintf(service_name, "host@%s", xhost);
 
-  sprintf(service_name, "host@%s", hostinfo->h_name);
+  xfree(xhost);
+  xhost = NULL;
 
   name_type = GSS_C_NT_HOSTBASED_SERVICE;