src/openvpn/sample-scripts/verify-cn

   1 #!/usr/bin/perl
   2
   3 # verify-cn -- a sample OpenVPN tls-verify script
   4 #
   5 # Return 0 if cn matches the common name component of
   6 # X509_NAME_oneline, 1 otherwise.
   7 #
   8 # For example in OpenVPN, you could use the directive:
   9 #
  10 #   tls-verify "./verify-cn Test-Client"
  11 #
  12 # This would cause the connection to be dropped unless
  13 # the client common name is "Test-Client"
  14
  15 die "usage: verify-cn cn certificate_depth X509_NAME_oneline" if (@ARGV != 3);
  16
  17 # Parse out arguments:
  18 #   cn    -- The common name which the client is required to have,
  19 #            taken from the argument to the tls-verify directive
  20 #            in the OpenVPN config file.
  21 #   depth -- The current certificate chain depth.  In a typical
  22 #            bi-level chain, the root certificate will be at level
  23 #            1 and the client certificate will be at level 0.
  24 #            This script will be called separately for each level.
  25 #   x509  -- the X509 subject string as extracted by OpenVPN from
  26 #            the client's provided certificate.
  27 ($cn, $depth, $x509) = @ARGV;
  28
  29 if ($depth == 0) {
  30     # If depth is zero, we know that this is the final
  31     # certificate in the chain (i.e. the client certificate),
  32     # and the one we are interested in examining.
  33     # If so, parse out the common name substring in
  34     # the X509 subject string.
  35
  36     if ($x509 =~ /\/CN=([^\/]+)/) {
  37         # Accept the connection if the X509 common name
  38         # string matches the passed cn argument.
  39         if ($cn eq $1) {
  40             exit 0;
  41         }
  42     }
  43
  44     # Authentication failed -- Either we could not parse
  45     # the X509 subject string, or the common name in the
  46     # subject string didn't match the passed cn argument.
  47     exit 1;
  48 }
  49
  50 # If depth is nonzero, tell OpenVPN to continue processing
  51 # the certificate chain.
  52 exit 0;