crypto/openssh/auth-rh-rsa.c

   1 /* $OpenBSD: auth-rh-rsa.c,v 1.45 2016/03/07 19:02:43 djm 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 #ifdef WITH_SSH1
  19
  20 #include <sys/types.h>
  21
  22 #include <pwd.h>
  23 #include <stdarg.h>
  24
  25 #include "packet.h"
  26 #include "uidswap.h"
  27 #include "log.h"
  28 #include "buffer.h"
  29 #include "misc.h"
  30 #include "servconf.h"
  31 #include "key.h"
  32 #include "hostfile.h"
  33 #include "pathnames.h"
  34 #include "auth.h"
  35 #include "canohost.h"
  36 #ifdef GSSAPI
  37 #include "ssh-gss.h"
  38 #endif
  39 #include "monitor_wrap.h"
  40
  41 /* import */
  42 extern ServerOptions options;
  43
  44 int
  45 auth_rhosts_rsa_key_allowed(struct passwd *pw, const char *cuser,
  46     const char *chost, Key *client_host_key)
  47 {
  48         HostStatus host_status;
  49
  50         if (auth_key_is_revoked(client_host_key))
  51                 return 0;
  52
  53         /* Check if we would accept it using rhosts authentication. */
  54         if (!auth_rhosts(pw, cuser))
  55                 return 0;
  56
  57         host_status = check_key_in_hostfiles(pw, client_host_key,
  58             chost, _PATH_SSH_SYSTEM_HOSTFILE,
  59             options.ignore_user_known_hosts ? NULL : _PATH_SSH_USER_HOSTFILE);
  60
  61         return (host_status == HOST_OK);
  62 }
  63
  64 /*
  65  * Tries to authenticate the user using the .rhosts file and the host using
  66  * its host key.  Returns true if authentication succeeds.
  67  */
  68 int
  69 auth_rhosts_rsa(Authctxt *authctxt, char *cuser, Key *client_host_key)
  70 {
  71         struct ssh *ssh = active_state; /* XXX */
  72         const char *chost;
  73         struct passwd *pw = authctxt->pw;
  74
  75         debug("Trying rhosts with RSA host authentication for client user %.100s",
  76             cuser);
  77
  78         if (!authctxt->valid || client_host_key == NULL ||
  79             client_host_key->rsa == NULL)
  80                 return 0;
  81
  82         chost = auth_get_canonical_hostname(ssh, options.use_dns);
  83         debug("Rhosts RSA authentication: canonical host %.900s", chost);
  84
  85         if (!PRIVSEP(auth_rhosts_rsa_key_allowed(pw, cuser, chost, client_host_key))) {
  86                 debug("Rhosts with RSA host authentication denied: unknown or invalid host key");
  87                 packet_send_debug("Your host key cannot be verified: unknown or invalid host key.");
  88                 return 0;
  89         }
  90         /* A matching host key was found and is known. */
  91
  92         /* Perform the challenge-response dialog with the client for the host key. */
  93         if (!auth_rsa_challenge_dialog(client_host_key)) {
  94                 logit("Client on %.800s failed to respond correctly to host authentication.",
  95                     chost);
  96                 return 0;
  97         }
  98         /*
  99          * We have authenticated the user using .rhosts or /etc/hosts.equiv,
 100          * and the host using RSA. We accept the authentication.
 101          */
 102
 103         verbose("Rhosts with RSA host authentication accepted for %.100s, %.100s on %.700s.",
 104             pw->pw_name, cuser, chost);
 105         packet_send_debug("Rhosts with RSA host authentication accepted.");
 106         return 1;
 107 }
 108
 109 #endif /* WITH_SSH1 */