NAME

pam_exec - PAM module which calls an external command

SYNOPSIS

pam_exec.so [debug] [expose_authtok] [seteuid] [quiet] [stdout] [log=file] [type=type] command [...]

DESCRIPTION

pam_exec is a PAM module that can be used to run an external command.

The child's environment is set to the current PAM environment list, as returned by pam_getenvlist(3) In addition, the following PAM items are exported as environment variables: PAM_RHOST, PAM_RUSER, PAM_SERVICE, PAM_TTY, PAM_USER and PAM_TYPE, which contains one of the module types: account, auth, password, open_session and close_session.

Commands called by pam_exec need to be aware of that the user can have control over the environment.

OPTIONS

debug

Print debug information.

expose_authtok

During authentication the calling command can read the password from stdin(3). Only first PAM_MAX_RESP_SIZE bytes of a password are provided to the command.

log=file

The output of the command is appended to file

type=type

Only run the command if the module type matches the given type.

stdout

Per default the output of the executed command is written to /dev/null. With this option, the stdout output of the executed command is redirected to the calling application. It's in the responsibility of this application what happens with the output. The log option is ignored.

quiet

Per default pam_exec.so will echo the exit status of the external command if it fails. Specifying this option will suppress the message.

seteuid

Per default pam_exec.so will execute the external command with the real user ID of the calling process. Specifying this option means the command is run with the effective user ID.

MODULE TYPES PROVIDED

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

RETURN VALUES

PAM_SUCCESS

The external command was run successfully.

PAM_BUF_ERR

Memory buffer error.

PAM_CONV_ERR

The conversation method supplied by the application failed to obtain the username.

PAM_INCOMPLETE

The conversation method supplied by the application returned PAM_CONV_AGAIN.

PAM_SERVICE_ERR

No argument or a wrong number of arguments were given.

PAM_SYSTEM_ERR

A system error occurred or the command to execute failed.

PAM_IGNORE

pam_setcred was called, which does not execute the command. Or, the value given for the type= parameter did not match the module type.

EXAMPLES

Add the following line to /etc/pam.d/passwd to rebuild the NIS database after each local password change:



        password optional pam_exec.so seteuid /usr/bin/make -C /var/yp

This will execute the command

make -C /var/yp

with effective user ID.

AUTHOR

pam_exec was written by Thorsten Kukuk <kukuk@thkukuk.de> and Josh Triplett <josh@joshtriplett.org>.

06/08/2020

Linux-PAM Manual