auth2-none.c

   1 /*
   2  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  *
  13  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  14  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  15  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  16  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  17  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  18  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  19  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  20  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  21  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  22  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  23  */
  24
  25 #include "includes.h"
  26 RCSID("$OpenBSD: auth2-none.c,v 1.7 2004/05/11 19:01:43 deraadt Exp $");
  27
  28 #include "auth.h"
  29 #include "xmalloc.h"
  30 #include "packet.h"
  31 #include "log.h"
  32 #include "servconf.h"
  33 #include "atomicio.h"
  34 #include "compat.h"
  35 #include "ssh2.h"
  36 #include "monitor_wrap.h"
  37
  38 /* import */
  39 extern ServerOptions options;
  40
  41 /* "none" is allowed only one time */
  42 static int none_enabled = 1;
  43
  44 char *
  45 auth2_read_banner(void)
  46 {
  47         struct stat st;
  48         char *banner = NULL;
  49         size_t len, n;
  50         int fd;
  51
  52         if ((fd = open(options.banner, O_RDONLY)) == -1)
  53                 return (NULL);
  54         if (fstat(fd, &st) == -1) {
  55                 close(fd);
  56                 return (NULL);
  57         }
  58         if (st.st_size > 1*1024*1024) {
  59                 close(fd);
  60                 return (NULL);
  61         }
  62
  63         len = (size_t)st.st_size;               /* truncate */
  64         banner = xmalloc(len + 1);
  65         n = atomicio(read, fd, banner, len);
  66         close(fd);
  67
  68         if (n != len) {
  69                 xfree(banner);
  70                 return (NULL);
  71         }
  72         banner[n] = '\0';
  73
  74         return (banner);
  75 }
  76
  77 void
  78 userauth_send_banner(const char *msg)
  79 {
  80         if (datafellows & SSH_BUG_BANNER)
  81                 return;
  82
  83         packet_start(SSH2_MSG_USERAUTH_BANNER);
  84         packet_put_cstring(msg);
  85         packet_put_cstring("");         /* language, unused */
  86         packet_send();
  87         debug("%s: sent", __func__);
  88 }
  89
  90 static void
  91 userauth_banner(void)
  92 {
  93         char *banner = NULL;
  94
  95         if (options.banner == NULL || (datafellows & SSH_BUG_BANNER))
  96                 return;
  97
  98         if ((banner = PRIVSEP(auth2_read_banner())) == NULL)
  99                 goto done;
 100         userauth_send_banner(banner);
 101
 102 done:
 103         if (banner)
 104                 xfree(banner);
 105 }
 106
 107 static int
 108 userauth_none(Authctxt *authctxt)
 109 {
 110         none_enabled = 0;
 111         packet_check_eom();
 112         userauth_banner();
 113 #ifdef HAVE_CYGWIN
 114         if (check_nt_auth(1, authctxt->pw) == 0)
 115                 return (0);
 116 #endif
 117         if (options.password_authentication)
 118                 return (PRIVSEP(auth_password(authctxt, "")));
 119         return (0);
 120 }
 121
 122 Authmethod method_none = {
 123         "none",
 124         userauth_none,
 125         &none_enabled
 126 };