pam_filter(8)

1PAM_FILTER(8)                  Linux-PAM Manual                  PAM_FILTER(8)
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NAME

6       pam_filter - PAM filter module
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SYNOPSIS

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

12       This module is intended to be a platform for providing access to all of
13       the input/output that passes between the user and the application. It
14       is only suitable for tty-based and (stdin/stdout) applications.
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16       To function this module requires filters to be installed on the system.
17       The single filter provided with the module simply transposes upper and
18       lower case letters in the input and output streams. (This can be very
19       annoying and is not kind to termcap based editors).
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21       Each component of the module has the potential to invoke the desired
22       filter. The filter is always execv(2) with the privilege of the calling
23       application and not that of the user. For this reason it cannot usually
24       be killed by the user without closing their session.
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OPTIONS

27       debug
28           Print debug information.
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30       new_term
31           The default action of the filter is to set the PAM_TTY item to
32           indicate the terminal that the user is using to connect to the
33           application. This argument indicates that the filter should set
34           PAM_TTY to the filtered pseudo-terminal.
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36       non_term
37           don't try to set the PAM_TTY item.
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39       runX
40           In order that the module can invoke a filter it should know when to
41           invoke it. This argument is required to tell the filter when to do
42           this.
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44           Permitted values for X are 1 and 2. These indicate the precise time
45           that the filter is to be run. To understand this concept it will be
46           useful to have read the pam(3) manual page. Basically, for each
47           management group there are up to two ways of calling the module's
48           functions. In the case of the authentication and session components
49           there are actually two separate functions. For the case of
50           authentication, these functions are pam_authenticate(3) and
51           pam_setcred(3), here run1 means run the filter from the
52           pam_authenticate function and run2 means run the filter from
53           pam_setcred. In the case of the session modules, run1 implies that
54           the filter is invoked at the pam_open_session(3) stage, and run2
55           for pam_close_session(3).
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57           For the case of the account component. Either run1 or run2 may be
58           used.
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60           For the case of the password component, run1 is used to indicate
61           that the filter is run on the first occasion of pam_chauthtok(3)
62           (the PAM_PRELIM_CHECK phase) and run2 is used to indicate that the
63           filter is run on the second occasion (the PAM_UPDATE_AUTHTOK
64           phase).
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66       filter
67           The full pathname of the filter to be run and any command line
68           arguments that the filter might expect.
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MODULE TYPES PROVIDED

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

74       PAM_SUCCESS
75           The new filter was set successfully.
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77       PAM_ABORT
78           Critical error, immediate abort.
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EXAMPLES

81       Add the following line to /etc/pam.d/login to see how to configure
82       login to transpose upper and lower case letters once the user has
83       logged in:
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85                   session required pam_filter.so run1 /lib/security/pam_filter/upperLOWER
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AUTHOR

93       pam_filter was written by Andrew G. Morgan <morgan@kernel.org>.
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97Linux-PAM Manual                  09/03/2021                     PAM_FILTER(8)