PAM_SM_CHAUTHTOK(3PAM) PAM Library Functions PAM_SM_CHAUTHTOK(3PAM)

NAME

pam_sm_chauthtok - service provider implementation for pam_chauthtok

SYNOPSIS

cc [ flag ...] file ... -lpam [ library ... ]
#include <security/pam_appl.h>
#include <security/pam_modules.h>

int pam_sm_chauthtok(pam_handle_t *pamh, int flags, int argc,
const char **argv);

DESCRIPTION

In response to a call to pam_chauthtok(3PAM) the PAM framework calls
pam_sm_chauthtok() from the modules listed in the pam.conf(5) file. The
password management provider supplies the back-end functionality for this
interface function.


The pam_sm_chauthtok() function changes the authentication token
associated with a particular user referenced by the authentication handle
pamh.


The following flags may be passed to pam_chauthtok():

PAM_SILENT
The password service should not generate
any messages.


PAM_CHANGE_EXPIRED_AUTHTOK
The password service should only update
those passwords that have aged. If this
flag is not passed, the password service
should update all passwords.


PAM_PRELIM_CHECK
The password service should only perform
preliminary checks. No passwords should be
updated.


PAM_NO_AUTHTOK_CHECK
The password service should not perform
conformance checks on the structure of the
password. Conformance checks do not apply
to verification that the same password was
entered during both passes.


PAM_UPDATE_AUTHTOK
The password service should update
passwords.


Note that PAM_PRELIM_CHECK and PAM_UPDATE_AUTHTOK cannot be set at the
same time.


Upon successful completion of the call, the authentication token of the
user will be ready for change or will be changed, depending upon the
flag, in accordance with the authentication scheme configured within the
system.


The argc argument represents the number of module options passed in from
the configuration file pam.conf(5). The argv argument specifies the
module options, which are interpreted and processed by the password
management service. Please refer to the specific module man pages for the
various available options.


It is the responsibility of pam_sm_chauthtok() to determine if the new
password meets certain strength requirements. pam_sm_chauthtok() may
continue to re-prompt the user (for a limited number of times) for a new
password until the password entered meets the strength requirements.


Before returning, pam_sm_chauthtok() should call pam_get_item() and
retrieve both PAM_AUTHTOK and PAM_OLDAUTHTOK. If both are NULL,
pam_sm_chauthtok() should set them to the new and old passwords as
entered by the user.

RETURN VALUES

Upon successful completion, PAM_SUCCESS must be returned. The following
values may also be returned:

PAM_PERM_DENIED
No permission.


PAM_AUTHTOK_ERR
Authentication token manipulation error.


PAM_AUTHTOK_RECOVERY_ERR
Old authentication token cannot be
recovered.


PAM_AUTHTOK_LOCK_BUSY
Authentication token lock busy.


PAM_AUTHTOK_DISABLE_AGING
Authentication token aging disabled.


PAM_USER_UNKNOWN
User unknown to password service.


PAM_TRY_AGAIN
Preliminary check by password service
failed.

ATTRIBUTES

See attributes(7) for description of the following attributes:


+--------------------+-------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-------------------------+
|Interface Stability | Stable |
+--------------------+-------------------------+
|MT-Level | MT-Safe with exceptions |
+--------------------+-------------------------+

SEE ALSO

libpam(3LIB), pam(3PAM), pam_chauthtok(3PAM), pam_get_data(3PAM),
pam_get_item(3PAM), pam_set_data(3PAM), pam.conf(5), attributes(7),
ping(8)

NOTES

The PAM framework invokes the password services twice. The first time the
modules are invoked with the flag, PAM_PRELIM_CHECK. During this stage,
the password modules should only perform preliminary checks. For example,
they may ping remote name services to see if they are ready for updates.
If a password module detects a transient error such as a remote name
service temporarily down, it should return PAM_TRY_AGAIN to the PAM
framework, which will immediately return the error back to the
application. If all password modules pass the preliminary check, the PAM
framework invokes the password services again with the flag,
PAM_UPDATE_AUTHTOK. During this stage, each password module should
proceed to update the appropriate password. Any error will again be
reported back to application.


If a service module receives the flag PAM_CHANGE_EXPIRED_AUTHTOK, it
should check whether the password has aged or expired. If the password
has aged or expired, then the service module should proceed to update the
password. If the status indicates that the password has not yet aged or
expired, then the password module should return PAM_IGNORE.


If a user's password has aged or expired, a PAM account module could save
this information as state in the authentication handle, pamh, using
pam_set_data(). The related password management module could retrieve
this information using pam_get_data() to determine whether or not it
should prompt the user to update the password for this particular module.


The interfaces in libpam(3LIB) are MT-Safe only if each thread within the
multithreaded application uses its own PAM handle.


If the PAM_REPOSITORY item_type is set and a service module does not
recognize the type, the service module does not process any information,
and returns PAM_IGNORE. If the PAM_REPOSITORY item_type is not set, a
service module performs its default action.

August 19, 2023 PAM_SM_CHAUTHTOK(3PAM)