crypto/openssh/auth-rh-rsa.c

   1 /* $OpenBSD: auth-rh-rsa.c,v 1.44 2014/07/15 15:54:14 millert 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 #include <stdarg.h>
  22
  23 #include "packet.h"
  24 #include "uidswap.h"
  25 #include "log.h"
  26 #include "buffer.h"
  27 #include "misc.h"
  28 #include "servconf.h"
  29 #include "key.h"
  30 #include "hostfile.h"
  31 #include "pathnames.h"
  32 #include "auth.h"
  33 #include "canohost.h"
  34 #ifdef GSSAPI
  35 #include "ssh-gss.h"
  36 #endif
  37 #include "monitor_wrap.h"
  38
  39 /* import */
  40 extern ServerOptions options;
  41
  42 int
  43 auth_rhosts_rsa_key_allowed(struct passwd *pw, char *cuser, char *chost,
  44     Key *client_host_key)
  45 {
  46         HostStatus host_status;
  47
  48         if (auth_key_is_revoked(client_host_key))
  49                 return 0;
  50
  51         /* Check if we would accept it using rhosts authentication. */
  52         if (!auth_rhosts(pw, cuser))
  53                 return 0;
  54
  55         host_status = check_key_in_hostfiles(pw, client_host_key,
  56             chost, _PATH_SSH_SYSTEM_HOSTFILE,
  57             options.ignore_user_known_hosts ? NULL : _PATH_SSH_USER_HOSTFILE);
  58
  59         return (host_status == HOST_OK);
  60 }
  61
  62 /*
  63  * Tries to authenticate the user using the .rhosts file and the host using
  64  * its host key.  Returns true if authentication succeeds.
  65  */
  66 int
  67 auth_rhosts_rsa(Authctxt *authctxt, char *cuser, Key *client_host_key)
  68 {
  69         char *chost;
  70         struct passwd *pw = authctxt->pw;
  71
  72         debug("Trying rhosts with RSA host authentication for client user %.100s",
  73             cuser);
  74
  75         if (!authctxt->valid || client_host_key == NULL ||
  76             client_host_key->rsa == NULL)
  77                 return 0;
  78
  79         chost = (char *)get_canonical_hostname(options.use_dns);
  80         debug("Rhosts RSA authentication: canonical host %.900s", chost);
  81
  82         if (!PRIVSEP(auth_rhosts_rsa_key_allowed(pw, cuser, chost, client_host_key))) {
  83                 debug("Rhosts with RSA host authentication denied: unknown or invalid host key");
  84                 packet_send_debug("Your host key cannot be verified: unknown or invalid host key.");
  85                 return 0;
  86         }
  87         /* A matching host key was found and is known. */
  88
  89         /* Perform the challenge-response dialog with the client for the host key. */
  90         if (!auth_rsa_challenge_dialog(client_host_key)) {
  91                 logit("Client on %.800s failed to respond correctly to host authentication.",
  92                     chost);
  93                 return 0;
  94         }
  95         /*
  96          * We have authenticated the user using .rhosts or /etc/hosts.equiv,
  97          * and the host using RSA. We accept the authentication.
  98          */
  99
 100         verbose("Rhosts with RSA host authentication accepted for %.100s, %.100s on %.700s.",
 101             pw->pw_name, cuser, chost);
 102         packet_send_debug("Rhosts with RSA host authentication accepted.");
 103         return 1;
 104 }