faxq-helper man page
faxq-helper — privileged helper process to access the fax queue
faxq-helper <command> [<options>]
faxq-helper is part of the internal workings of faxspool(1).
Formerly, the /var/spool/fax/outgoing directory was world-writeable, leading to all sort of funny symlink attacks against faxspool(1) and faxrunq(8).
These days, it's owned by the user “fax”, and only this user can write to it. To be able to put jobs there, faxspool(1) calls faxq-helper for very clearly defined purposes:
- make a new queue directory
- put a new fax G3 file into this queue directory
- put a JOB file into this queue directory, and activate the fax job
- remove a fax job from the queue (to be used by faxrm and in case of errors)
- re-queue a job that has been suspended due to repeated failures (faxq -r)
To achieve this, faxq-helper is installed set-user-id fax. If you remove the suid bit, or chown the fax queue directory to a different user, it will stop working.
faxq-helper has the following exit() values:
everything went fine
invalid JOB ID specified on the command line
some problem with the directory setup of the outgoing queue dir, /var/spool/fax/outgoing (it will print a detailed error message)
some problems with the user ID setup of the “fax” user (it will print a detailed error message)
failure to process the specified command (it will print a detailed error message)
faxspool(1), faxq(1), faxrm(1), faxqueue(5)
faxq-helper is Copyright (C) 2004-2006 by Gert Doering, <email@example.com>.