- markus@cvs.openbsd.org 2002/07/24 16:11:18

     [hostfile.c hostfile.h sshconnect.c]
     print out all known keys for a host if we get a unknown host key,
     see discussion at http://marc.theaimsgroup.com/?t=101069210100016&r=1&w=4

     the ssharp mitm tool attacks users in a similar way, so i'd like to
     pointed out again:
        A MITM attack is always possible if the ssh client prints:
        The authenticity of host 'bla' can't be established.
     (protocol version 2 with pubkey authentication allows you to detect
     MITM attacks)

1 files changed, 36 insertions, 8 deletions

diff --git a/hostfile.c b/hostfile.c
index cefff8d62..dcee03448 100644
--- a/hostfile.c
+++ b/hostfile.c
@@ -36,7 +36,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: hostfile.c,v 1.29 2001/12/18 10:04:21 jakob Exp $");
+RCSID("$OpenBSD: hostfile.c,v 1.30 2002/07/24 16:11:18 markus Exp $");
 
 #include "packet.h"
 #include "match.h"
@@ -91,11 +91,14 @@ hostfile_check_key(int bits, Key *key, const char *host, const char *filename, i
  * in the list of our known hosts. Returns HOST_OK if the host is known and
  * has the specified key, HOST_NEW if the host is not known, and HOST_CHANGED
  * if the host is known but used to have a different host key.
+ *
+ * If no 'key' has been specified and a key of type 'keytype' is known
+ * for the specified host, then HOST_FOUND is returned.
  */
 
-HostStatus
-check_host_in_hostfile(const char *filename, const char *host, Key *key,
-    Key *found, int *numret)
+static HostStatus
+check_host_in_hostfile_by_key_or_type(const char *filename,
+    const char *host, Key *key, int keytype, Key *found, int *numret)
 {
         FILE *f;
         char line[8192];
@@ -105,8 +108,7 @@ check_host_in_hostfile(const char *filename, const char *host, Key *key,
         HostStatus end_return;
 
         debug3("check_host_in_hostfile: filename %s", filename);
-        if (key == NULL)
-                fatal("no key to look up");
+
         /* Open the file containing the list of known hosts. */
         f = fopen(filename, "r");
         if (!f)
@@ -147,12 +149,20 @@ check_host_in_hostfile(const char *filename, const char *host, Key *key,
                  */
                 if (!hostfile_read_key(&cp, &kbits, found))
                         continue;
-                if (!hostfile_check_key(kbits, found, host, filename, linenum))
-                        continue;
 
                 if (numret != NULL)
                         *numret = linenum;
 
+                if (key == NULL) {
+                        /* we found a key of the requested type */
+                        if (found->type == keytype)
+                                return HOST_FOUND;
+                        continue;
+                }
+
+                if (!hostfile_check_key(kbits, found, host, filename, linenum))
+                        continue;
+
                 /* Check if the current key is the same as the given key. */
                 if (key_equal(key, found)) {
                         /* Ok, they match. */
@@ -177,6 +187,24 @@ check_host_in_hostfile(const char *filename, const char *host, Key *key,
         return end_return;
 }
 
+HostStatus
+check_host_in_hostfile(const char *filename, const char *host, Key *key,
+    Key *found, int *numret)
+{
+        if (key == NULL)
+                fatal("no key to look up");
+        return (check_host_in_hostfile_by_key_or_type(filename, host, key, 0,
+            found, numret));
+}
+
+int
+lookup_key_in_hostfile_by_type(const char *filename, const char *host,
+    int keytype, Key *found, int *numret)
+{
+        return (check_host_in_hostfile_by_key_or_type(filename, host, NULL,
+            keytype, found, numret) == HOST_FOUND);
+}
+
 /*
  * Appends an entry to the host file.  Returns false if the entry could not
  * be appended.