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      1 /*
      2  * Author: Tatu Ylonen <ylo (at) cs.hut.fi>
      3  * Copyright (c) 1995 Tatu Ylonen <ylo (at) cs.hut.fi>, Espoo, Finland
      4  *                    All rights reserved
      5  * Rhosts or /etc/hosts.equiv authentication combined with RSA host
      6  * authentication.
      7  *
      8  * As far as I am concerned, the code I have written for this software
      9  * can be used freely for any purpose.  Any derived versions of this
     10  * software must be clearly marked as such, and if the derived work is
     11  * incompatible with the protocol description in the RFC file, it must be
     12  * called by a name other than "ssh" or "Secure Shell".
     13  */
     14 
     15 #include "includes.h"
     16 RCSID("$OpenBSD: auth-rh-rsa.c,v 1.34 2002/03/25 09:25:06 markus Exp $");
     17 
     18 #pragma ident	"%Z%%M%	%I%	%E% SMI"
     19 
     20 #include "packet.h"
     21 #include "uidswap.h"
     22 #include "log.h"
     23 #include "servconf.h"
     24 #include "key.h"
     25 #include "hostfile.h"
     26 #include "pathnames.h"
     27 #include "auth.h"
     28 #include "canohost.h"
     29 
     30 /* import */
     31 extern ServerOptions options;
     32 
     33 int
     34 auth_rhosts_rsa_key_allowed(struct passwd *pw, char *cuser, char *chost,
     35     Key *client_host_key)
     36 {
     37 	HostStatus host_status;
     38 
     39 	/* Check if we would accept it using rhosts authentication. */
     40 	if (!auth_rhosts(pw, cuser))
     41 		return 0;
     42 
     43 	host_status = check_key_in_hostfiles(pw, client_host_key,
     44 	    chost, _PATH_SSH_SYSTEM_HOSTFILE,
     45 	    options.ignore_user_known_hosts ? NULL : _PATH_SSH_USER_HOSTFILE);
     46 
     47 	return (host_status == HOST_OK);
     48 }
     49 
     50 /*
     51  * Tries to authenticate the user using the .rhosts file and the host using
     52  * its host key.  Returns true if authentication succeeds.
     53  */
     54 int
     55 auth_rhosts_rsa(struct passwd *pw, char *cuser, Key *client_host_key)
     56 {
     57 	char *chost;
     58 
     59 	debug("Trying rhosts with RSA host authentication for client user %.100s",
     60 	    cuser);
     61 
     62 	if (pw == NULL || client_host_key == NULL ||
     63 	    client_host_key->rsa == NULL)
     64 		return 0;
     65 
     66 	chost = (char *)get_canonical_hostname(options.verify_reverse_mapping);
     67 	debug("Rhosts RSA authentication: canonical host %.900s", chost);
     68 
     69 	if (!auth_rhosts_rsa_key_allowed(pw, cuser, chost, client_host_key)) {
     70 		debug("Rhosts with RSA host authentication denied: unknown or invalid host key");
     71 		packet_send_debug("Your host key cannot be verified: unknown or invalid host key.");
     72 		return 0;
     73 	}
     74 	/* A matching host key was found and is known. */
     75 
     76 	/* Perform the challenge-response dialog with the client for the host key. */
     77 	if (!auth_rsa_challenge_dialog(client_host_key)) {
     78 		log("Client on %.800s failed to respond correctly to host authentication.",
     79 		    chost);
     80 		return 0;
     81 	}
     82 	/*
     83 	 * We have authenticated the user using .rhosts or /etc/hosts.equiv,
     84 	 * and the host using RSA. We accept the authentication.
     85 	 */
     86 
     87 	verbose("Rhosts with RSA host authentication accepted for %.100s, %.100s on %.700s.",
     88 	   pw->pw_name, cuser, chost);
     89 	packet_send_debug("Rhosts with RSA host authentication accepted.");
     90 	return 1;
     91 }
     92