The pam_open_session() function is called after a user has been successfully authenticated. See pam_authenticate(3PAM) and pam_acct_mgmt(3PAM). It is used to notify the session modules that a new session has been initiated. All programs that use the pam(3PAM) library should invoke pam_open_session() when beginning a new session. Upon termination of this activity, pam_close_session() should be invoked to inform pam(3PAM) that the session has terminated.

The pamh argument is an authentication handle obtained by a prior call to pam_start(). The following flag may be set in the flags field for pam_open_session() and pam_close_session():

PAM_SILENT

The session service should not generate any messages.

Upon successful completion, PAM_SUCCESS is returned. In addition to the return values defined in pam(3PAM), the following value may be returned on error:

PAM_SESSION_ERR

Cannot make or remove an entry for the specified session.

See attributes(5) for description of the following attributes:

getutxent(3C), pam(3PAM), pam_acct_mgmt(3PAM), pam_authenticate(3PAM), pam_start(3PAM), attributes(5)

In many instances, the pam_open_session() and pam_close_session() calls may be made by different processes. For example, in UNIX the login process opens a session, while the init process closes the session. In this case, UTMP/WTMP entries may be used to link the call to pam_close_session() with an earlier call to pam_open_session(). This is possible because UTMP/WTMP entries are uniquely identified by a combination of attributes, including the user login name and device name, which are accessible through the PAM handle, pamh. The call to pam_open_session() should precede UTMP/WTMP entry management, and the call to pam_close_session() should follow UTMP/WTMP exit management.

The interfaces in libpam are MT-Safe only if each thread within the multithreaded application uses its own PAM handle.