pam_get_authtok

3 Linux-PAM Manual

pam_get_authtok

pam_get_authtok_verify

pam_get_authtok_noverify

get authentication token

          #include <security/pam_ext.h>

            int pam_get_authtok
            pam_handle_t *pamh
            int item
            const char **authtok
            const char *prompt

            int pam_get_authtok_noverify
            pam_handle_t *pamh
            const char **authtok
            const char *prompt

            int pam_get_authtok_verify
            pam_handle_t *pamh
            const char **authtok
            const char *prompt

## DESCRIPTION

The `pam_get_authtok` function returns the cached authentication token, or prompts the user if no token is currently cached. It is intended for internal use by Linux-PAM and PAM service modules. Upon successful return, authtok contains a pointer to the value of the authentication token. Note, this is a pointer to the actual data and should not be free()'ed or over-written!

The prompt argument specifies a prompt to use if no token is cached. If a NULL pointer is given, `pam_get_authtok` uses pre-defined prompts.

The following values are supported for item:

PAM_AUTHTOK

- Returns the current authentication token. Called from

  pam_sm_chauthtok

  3 `pam_get_authtok` will ask the user to confirm the new token by retyping it. If a prompt was specified, "Retype" will be used as prefix.

PAM_OLDAUTHTOK

- Returns the previous authentication token when changing authentication tokens.

The `pam_get_authtok_noverify` function can only be used for changing the password (from

pam_sm_chauthtok

3 ). It returns the cached authentication token, or prompts the user if no token is currently cached. The difference to `pam_get_authtok` is, that this function does not ask a second time for the password to verify it. Upon successful return, authtok contains a pointer to the value of the authentication token. Note, this is a pointer to the actual data and should not be free()'ed or over-written!

The `pam_get_authtok_verify` function can only be used to verify a password for mistypes gotten by

pam_get_authtok_noverify

3 . This function asks a second time for the password and verify it with the password provided by authtok argument. In case of an error, the value of authtok is undefined. Else this argument will point to the actual data and should not be free()'ed or over-written!

## OPTIONS

`pam_get_authtok` honours the following module options:

`try_first_pass`

- Before prompting the user for their password, the module first tries the previous stacked module's password in case that satisfies this module as well.

`use_first_pass`

- The argument `use_first_pass` forces the module to use a previous stacked modules password and will never prompt the user - if no password is available or the password is not appropriate, the user will be denied access.

`use_authtok`

- When password changing enforce the module to set the new token to the one provided by a previously stacked `password` module. If no token is available token changing will fail.

`authtok_type=`XXX``

- The default action is for the module to use the following prompts when requesting passwords: "New UNIX password: " and "Retype UNIX password: ". The example word UNIX can be replaced with this option, by default it is empty.

## RETURN VALUES

PAM_AUTH_ERR

- Authentication token could not be retrieved.

PAM_AUTHTOK_ERR

- New authentication could not be retrieved.

PAM_SUCCESS

- Authentication token was successfully retrieved.

PAM_SYSTEM_ERR

- No space for an authentication token was provided.

PAM_TRY_AGAIN

- New authentication tokens mismatch.

## SEE ALSO

pam

8

## STANDARDS

The `pam_get_authtok` function is a Linux-PAM extensions.