auth2-none.c

   1 /* $OpenBSD: auth2-none.c,v 1.11 2006/07/09 15:15:10 stevesk Exp $ */
   2 /*
   3  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  15  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  16  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  17  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  18  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  19  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  20  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  21  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  23  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  24  */
  25
  26 #include "includes.h"
  27
  28 #include <sys/types.h>
  29 #include <sys/stat.h>
  30
  31 #include <fcntl.h>
  32
  33 #include "auth.h"
  34 #include "xmalloc.h"
  35 #include "packet.h"
  36 #include "log.h"
  37 #include "servconf.h"
  38 #include "atomicio.h"
  39 #include "compat.h"
  40 #include "ssh2.h"
  41 #include "monitor_wrap.h"
  42
  43 /* import */
  44 extern ServerOptions options;
  45
  46 /* "none" is allowed only one time */
  47 static int none_enabled = 1;
  48
  49 char *
  50 auth2_read_banner(void)
  51 {
  52         struct stat st;
  53         char *banner = NULL;
  54         size_t len, n;
  55         int fd;
  56
  57         if ((fd = open(options.banner, O_RDONLY)) == -1)
  58                 return (NULL);
  59         if (fstat(fd, &st) == -1) {
  60                 close(fd);
  61                 return (NULL);
  62         }
  63         if (st.st_size > 1*1024*1024) {
  64                 close(fd);
  65                 return (NULL);
  66         }
  67
  68         len = (size_t)st.st_size;               /* truncate */
  69         banner = xmalloc(len + 1);
  70         n = atomicio(read, fd, banner, len);
  71         close(fd);
  72
  73         if (n != len) {
  74                 xfree(banner);
  75                 return (NULL);
  76         }
  77         banner[n] = '\0';
  78
  79         return (banner);
  80 }
  81
  82 void
  83 userauth_send_banner(const char *msg)
  84 {
  85         if (datafellows & SSH_BUG_BANNER)
  86                 return;
  87
  88         packet_start(SSH2_MSG_USERAUTH_BANNER);
  89         packet_put_cstring(msg);
  90         packet_put_cstring("");         /* language, unused */
  91         packet_send();
  92         debug("%s: sent", __func__);
  93 }
  94
  95 static void
  96 userauth_banner(void)
  97 {
  98         char *banner = NULL;
  99
 100         if (options.banner == NULL || (datafellows & SSH_BUG_BANNER))
 101                 return;
 102
 103         if ((banner = PRIVSEP(auth2_read_banner())) == NULL)
 104                 goto done;
 105         userauth_send_banner(banner);
 106
 107 done:
 108         if (banner)
 109                 xfree(banner);
 110 }
 111
 112 static int
 113 userauth_none(Authctxt *authctxt)
 114 {
 115         none_enabled = 0;
 116         packet_check_eom();
 117         userauth_banner();
 118 #ifdef HAVE_CYGWIN
 119         if (check_nt_auth(1, authctxt->pw) == 0)
 120                 return (0);
 121 #endif
 122         if (options.password_authentication)
 123                 return (PRIVSEP(auth_password(authctxt, "")));
 124         return (0);
 125 }
 126
 127 Authmethod method_none = {
 128         "none",
 129         userauth_none,
 130         &none_enabled
 131 };