pam_get_authtok(3) — Linux manual pages

Linux manual pages	Section 3: Subroutines

Name

pam_get_authtok, pam_get_authtok_verify, pam_get_authtok_noverify — get authentication token

Synopsis

#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.

STANDARDS