1PAM_FILTER(8) Linux-PAM Manual PAM_FILTER(8)
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6 pam_filter - PAM filter module
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9 pam_filter.so [debug] [new_term] [non_term] run1|run2 filter [...]
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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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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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71 All module types (auth, account, password and session) are provided.
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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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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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90 pam.conf(5), pam.d(5), pam(8)
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93 pam_filter was written by Andrew G. Morgan <morgan@kernel.org>.
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97Linux-PAM Manual 05/18/2017 PAM_FILTER(8)