pam_filter(8) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | MODULE TYPES PROVIDED | RETURN VALUES | EXAMPLES | SEE ALSO | AUTHOR | COLOPHON

PAM_FILTER(8)                Linux-PAM Manual               PAM_FILTER(8)

NAME         top

       pam_filter - PAM filter module

SYNOPSIS         top


       pam_filter.so [debug] [new_term] [non_term] run1|run2 filter [...]

DESCRIPTION         top

       This module is intended to be a platform for providing access to
       all of the input/output that passes between the user and the
       application. It is only suitable for tty-based and (stdin/stdout)
       applications.

       To function this module requires filters to be installed on the
       system. The single filter provided with the module simply
       transposes upper and lower case letters in the input and output
       streams. (This can be very annoying and is not kind to termcap
       based editors).

       Each component of the module has the potential to invoke the
       desired filter. The filter is always execv(2) with the privilege
       of the calling application and not that of the user. For this
       reason it cannot usually be killed by the user without closing
       their session.

OPTIONS         top

       debug
           Print debug information.

       new_term
           The default action of the filter is to set the PAM_TTY item to
           indicate the terminal that the user is using to connect to the
           application. This argument indicates that the filter should
           set PAM_TTY to the filtered pseudo-terminal.

       non_term
           don't try to set the PAM_TTY item.

       runX
           In order that the module can invoke a filter it should know
           when to invoke it. This argument is required to tell the
           filter when to do this.

           Permitted values for X are 1 and 2. These indicate the precise
           time that the filter is to be run. To understand this concept
           it will be useful to have read the pam(3) manual page.
           Basically, for each management group there are up to two ways
           of calling the module's functions. In the case of the
           authentication and session components there are actually two
           separate functions. For the case of authentication, these
           functions are pam_authenticate(3) and pam_setcred(3), here
           run1 means run the filter from the pam_authenticate function
           and run2 means run the filter from pam_setcred. In the case of
           the session modules, run1 implies that the filter is invoked
           at the pam_open_session(3) stage, and run2 for
           pam_close_session(3).

           For the case of the account component. Either run1 or run2 may
           be used.

           For the case of the password component, run1 is used to
           indicate that the filter is run on the first occasion of
           pam_chauthtok(3) (the PAM_PRELIM_CHECK phase) and run2 is used
           to indicate that the filter is run on the second occasion (the
           PAM_UPDATE_AUTHTOK phase).

       filter
           The full pathname of the filter to be run and any command line
           arguments that the filter might expect.

MODULE TYPES PROVIDED         top

       All module types (auth, account, password and session) are
       provided.

RETURN VALUES         top

       PAM_SUCCESS
           The new filter was set successfully.

       PAM_ABORT
           Critical error, immediate abort.

EXAMPLES         top

       Add the following line to /etc/pam.d/login to see how to configure
       login to transpose upper and lower case letters once the user has
       logged in:

                   session required pam_filter.so run1 /lib/security/pam_filter/upperLOWER

SEE ALSO         top

       pam.conf(5), pam.d(5), pam(8)

AUTHOR         top

       pam_filter was written by Andrew G. Morgan <morgan@kernel.org>.

COLOPHON         top

       This page is part of the linux-pam (Pluggable Authentication
       Modules for Linux) project.  Information about the project can be
       found at ⟨http://www.linux-pam.org/⟩.  If you have a bug report
       for this manual page, see ⟨//www.linux-pam.org/⟩.  This page was
       obtained from the project's upstream Git repository
       ⟨https://github.com/linux-pam/linux-pam.git⟩ on 2023-12-22.  (At
       that time, the date of the most recent commit that was found in
       the repository was 2023-12-18.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there is
       a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to
       man-pages@man7.org

Linux-PAM Manual                12/22/2023                  PAM_FILTER(8)