NAME

       vmod_unix - Utilities for Unix domain sockets

SYNOPSIS

          import unix [as name] [from "path"]

          STRING user()

          STRING group()

          INT uid()

          INT gid()

DESCRIPTION

       This  VMOD  provides information about the credentials of the peer process (user and group
       of the process owner) that is connected to a Varnish listener via a Unix domain socket, if
       the platform supports it.

       Examples:

          import unix;

          sub vcl_recv {
                # Return "403 Forbidden" if the connected peer is
                # not running as the user "trusteduser".
                if (unix.user() != "trusteduser") {
                        return( synth(403) );
                }

                # Require the connected peer to run in the group
                # "trustedgroup".
                if (unix.group() != "trustedgroup") {
                        return( synth(403) );
                }

                # Require the connected peer to run under a specific numeric
                # user id.
                if (unix.uid() != 4711) {
                        return( synth(403) );
                }

                # Require the connected peer to run under a numeric group id.
                if (unix.gid() != 815) {
                        return( synth(403) );
                }
          }

       Obtaining  the  peer  credentials  is  possible  on  a  platform  that supports one of the
       following:

       • getpeereid(3) (such as FreeBSD and other BSD-derived systems)

       • the socket option SO_PEERCRED for getsockopt(2) (Linux)

       • getpeerucred(3C) (SunOS and descendants)

       On SunOS and friends, the PRIV_PROC_INFO privilege set  is  added  to  the  Varnish  child
       process while the VMOD is loaded, see setppriv(2).

       On  most  platforms, the value returned is the effective user or group that was valid when
       the peer process initiated the connection.

   STRING user()
       Return the user name of the peer process owner.

   STRING group()
       Return the group name of the peer process owner.

   INT uid()
       Return the numeric user id of the peer process owner.

   INT gid()
       Return the numeric group id of the peer process owner.

ERRORS

       All functions in this VMOD are subject to the following constraints:

       • None of them may be called in vcl_init{} or vcl_fini{}. If one  of  them  is  called  in
         vcl_init{}, then the VCL program will fail to load, with an error message from the VMOD.

       • If  called  on  a  platform that is not supported, then VCL failure is invoked. An error
         message is written to the log (with the VCL_Error tag),  and  for  all  VCL  subroutines
         except  for  vcl_synth{},  control  is  directed  immediately  to  vcl_synth{}, with the
         response status set to 503 and the reason string set to "VCL failed".

         If the failure occurs during vcl_synth{}, then  vcl_synth{}  is  aborted,  and  the  the
         response line "503 VCL failed" is sent.

       • If  the  current  listener  is  not  a  Unix  domain  socket,  or if the attempt to read
         credentials fails, then a VCL_Error message is written to the log. The STRING  functions
         (unix.user()  and  unix.group())  return  NULL,  while the INT functions (unix.uid() and
         unix.gid()) return -1.

SEE ALSO

       • varnishd(1)

       • vcl(7)

       • getpeereid(3)

       • getsockopt(2)

       • getpeerucred(3C)

       • setppriv(2)

COPYRIGHT

          This document is licensed under the same conditions as Varnish itself.
          See LICENSE for details.

          SPDX-License-Identifier: BSD-2-Clause

          Authors: Geoffrey Simmons <geoffrey.simmons@uplex.de>

                                                                                     VMOD_UNIX(3)