auth-rh-rsa.c

   1 /* $OpenBSD: auth-rh-rsa.c,v 1.41 2006/07/06 16:03:53 stevesk Exp $ */
   2 /*
   3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   5  *                    All rights reserved
   6  * Rhosts or /etc/hosts.equiv authentication combined with RSA host
   7  * authentication.
   8  *
   9  * As far as I am concerned, the code I have written for this software
  10  * can be used freely for any purpose.  Any derived versions of this
  11  * software must be clearly marked as such, and if the derived work is
  12  * incompatible with the protocol description in the RFC file, it must be
  13  * called by a name other than "ssh" or "Secure Shell".
  14  */
  15
  16 #include "includes.h"
  17
  18 #include <sys/types.h>
  19
  20 #include <pwd.h>
  21
  22 #include "packet.h"
  23 #include "uidswap.h"
  24 #include "log.h"
  25 #include "servconf.h"
  26 #include "key.h"
  27 #include "hostfile.h"
  28 #include "pathnames.h"
  29 #include "auth.h"
  30 #include "canohost.h"
  31
  32 #include "monitor_wrap.h"
  33
  34 /* import */
  35 extern ServerOptions options;
  36
  37 int
  38 auth_rhosts_rsa_key_allowed(struct passwd *pw, char *cuser, char *chost,
  39     Key *client_host_key)
  40 {
  41         HostStatus host_status;
  42
  43         /* Check if we would accept it using rhosts authentication. */
  44         if (!auth_rhosts(pw, cuser))
  45                 return 0;
  46
  47         host_status = check_key_in_hostfiles(pw, client_host_key,
  48             chost, _PATH_SSH_SYSTEM_HOSTFILE,
  49             options.ignore_user_known_hosts ? NULL : _PATH_SSH_USER_HOSTFILE);
  50
  51         return (host_status == HOST_OK);
  52 }
  53
  54 /*
  55  * Tries to authenticate the user using the .rhosts file and the host using
  56  * its host key.  Returns true if authentication succeeds.
  57  */
  58 int
  59 auth_rhosts_rsa(Authctxt *authctxt, char *cuser, Key *client_host_key)
  60 {
  61         char *chost;
  62         struct passwd *pw = authctxt->pw;
  63
  64         debug("Trying rhosts with RSA host authentication for client user %.100s",
  65             cuser);
  66
  67         if (!authctxt->valid || client_host_key == NULL ||
  68             client_host_key->rsa == NULL)
  69                 return 0;
  70
  71         chost = (char *)get_canonical_hostname(options.use_dns);
  72         debug("Rhosts RSA authentication: canonical host %.900s", chost);
  73
  74         if (!PRIVSEP(auth_rhosts_rsa_key_allowed(pw, cuser, chost, client_host_key))) {
  75                 debug("Rhosts with RSA host authentication denied: unknown or invalid host key");
  76                 packet_send_debug("Your host key cannot be verified: unknown or invalid host key.");
  77                 return 0;
  78         }
  79         /* A matching host key was found and is known. */
  80
  81         /* Perform the challenge-response dialog with the client for the host key. */
  82         if (!auth_rsa_challenge_dialog(client_host_key)) {
  83                 logit("Client on %.800s failed to respond correctly to host authentication.",
  84                     chost);
  85                 return 0;
  86         }
  87         /*
  88          * We have authenticated the user using .rhosts or /etc/hosts.equiv,
  89          * and the host using RSA. We accept the authentication.
  90          */
  91
  92         verbose("Rhosts with RSA host authentication accepted for %.100s, %.100s on %.700s.",
  93             pw->pw_name, cuser, chost);
  94         packet_send_debug("Rhosts with RSA host authentication accepted.");
  95         return 1;
  96 }