crypto/openssh-5/auth2-none.c

   1 /* $OpenBSD: auth2-none.c,v 1.14 2007/08/23 03:22:16 djm 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 #include <sys/uio.h>
  31
  32 #include <fcntl.h>
  33 #include <stdarg.h>
  34 #include <unistd.h>
  35 #include <string.h>
  36
  37 #include "xmalloc.h"
  38 #include "key.h"
  39 #include "hostfile.h"
  40 #include "auth.h"
  41 #include "packet.h"
  42 #include "log.h"
  43 #include "buffer.h"
  44 #include "servconf.h"
  45 #include "atomicio.h"
  46 #include "compat.h"
  47 #include "ssh2.h"
  48 #ifdef GSSAPI
  49 #include "ssh-gss.h"
  50 #endif
  51 #include "monitor_wrap.h"
  52
  53 /* import */
  54 extern ServerOptions options;
  55
  56 /* "none" is allowed only one time */
  57 static int none_enabled = 1;
  58
  59 char *
  60 auth2_read_banner(void)
  61 {
  62         struct stat st;
  63         char *banner = NULL;
  64         size_t len, n;
  65         int fd;
  66
  67         if ((fd = open(options.banner, O_RDONLY)) == -1)
  68                 return (NULL);
  69         if (fstat(fd, &st) == -1) {
  70                 close(fd);
  71                 return (NULL);
  72         }
  73         if (st.st_size > 1*1024*1024) {
  74                 close(fd);
  75                 return (NULL);
  76         }
  77
  78         len = (size_t)st.st_size;               /* truncate */
  79         banner = xmalloc(len + 1);
  80         n = atomicio(read, fd, banner, len);
  81         close(fd);
  82
  83         if (n != len) {
  84                 xfree(banner);
  85                 return (NULL);
  86         }
  87         banner[n] = '\0';
  88
  89         return (banner);
  90 }
  91
  92 void
  93 userauth_send_banner(const char *msg)
  94 {
  95         if (datafellows & SSH_BUG_BANNER)
  96                 return;
  97
  98         packet_start(SSH2_MSG_USERAUTH_BANNER);
  99         packet_put_cstring(msg);
 100         packet_put_cstring("");         /* language, unused */
 101         packet_send();
 102         debug("%s: sent", __func__);
 103 }
 104
 105 static void
 106 userauth_banner(void)
 107 {
 108         char *banner = NULL;
 109
 110         if (options.banner == NULL ||
 111             strcasecmp(options.banner, "none") == 0 ||
 112             (datafellows & SSH_BUG_BANNER) != 0)
 113                 return;
 114
 115         if ((banner = PRIVSEP(auth2_read_banner())) == NULL)
 116                 goto done;
 117         userauth_send_banner(banner);
 118
 119 done:
 120         if (banner)
 121                 xfree(banner);
 122 }
 123
 124 static int
 125 userauth_none(Authctxt *authctxt)
 126 {
 127         none_enabled = 0;
 128         packet_check_eom();
 129         userauth_banner();
 130 #ifdef HAVE_CYGWIN
 131         if (check_nt_auth(1, authctxt->pw) == 0)
 132                 return (0);
 133 #endif
 134         if (options.password_authentication)
 135                 return (PRIVSEP(auth_password(authctxt, "")));
 136         return (0);
 137 }
 138
 139 Authmethod method_none = {
 140         "none",
 141         userauth_none,
 142         &none_enabled
 143 };