pam_conv(3) BSD Library Functions Manual pam_conv(3)
NAME
pam_conv -- PAM conversation system
LIBRARY
Pluggable Authentication Module Library (libpam, -lpam)
SYNOPSIS
#include <security/pam_appl.h>
struct pam_message {
int msg_style;
char *msg;
};
struct pam_response {
char *resp;
int resp_retcode;
};
struct pam_conv {
int (*conv)(int, const struct pam_message **,
struct pam_response **, void *);
void *appdata_ptr;
};
DESCRIPTION
The PAM library uses an application-defined callback to communicate with
the user. This callback is specified by the struct pam_conv passed to
pam_start() at the start of the transaction. It is also possible to set
or change the conversation function at any point during a PAM transaction
by changing the value of the PAM_CONV item.
The conversation function's first argument specifies the number of mes-
sages (up to PAM_NUM_MSG) to process. The second argument is a pointer
to an array of pointers to pam_message structures containing the actual
messages.
Each message can have one of four types, specified by the msg_style mem-
ber of struct pam_message:
PAM_PROMPT_ECHO_OFF
Display a prompt and accept the user's response with-
out echoing it to the terminal. This is commonly
used for passwords.
PAM_PROMPT_ECHO_ON Display a prompt and accept the user's response,
echoing it to the terminal. This is commonly used
for login names and one-time passphrases.
PAM_ERROR_MSG Display an error message.
PAM_TEXT_INFO Display an informational message.
In each case, the prompt or message to display is pointed to by the msg
member of struct pam_message. It can be up to PAM_MAX_MSG_SIZE charac-
ters long, including the terminating NUL.
On success, the conversation function should allocate and fill a contigu-
ous array of struct pam_response, one for each message that was passed
in. A pointer to the user's response to each message (or NULL in the
case of informational or error messages) should be stored in the resp
member of the corresponding struct pam_response. Each response can be up
to PAM_MAX_RESP_SIZE characters long, including the terminating NUL.
The resp_retcode member of struct pam_response is unused and should be
set to zero.
The conversation function should store a pointer to this array in the
location pointed to by its third argument. It is the caller's responsi-
bility to release both this array and the responses themselves, using
free(3). It is the conversation function's responsibility to ensure that
it is legal to do so.
The appdata_ptr member of struct pam_conv is passed unmodified to the
conversation function as its fourth and final argument.
On failure, the conversation function should release any resources it has
allocated, and return one of the predefined PAM error codes.
RETURN VALUES
The conversation function should return one of the following values:
[PAM_BUF_ERR] Memory buffer error.
[PAM_CONV_ERR] Conversation failure.
[PAM_SUCCESS] Success.
[PAM_SYSTEM_ERR] System error.
SEE ALSO
openpam_nullconv(3), openpam_ttyconv(3), pam(3), pam_error(3),
pam_get_item(3), pam_info(3), pam_prompt(3), pam_set_item(3),
pam_start(3)
STANDARDS
X/Open Single Sign-On Service (XSSO) - Pluggable Authentication Modules,
June 1997.
AUTHORS
The OpenPAM library and this manual page were developed for the FreeBSD
Project by ThinkSec AS and Network Associates Laboratories, the Security
Research Division of Network Associates, Inc. under DARPA/SPAWAR contract
N66001-01-C-8035 (``CBOSS''), as part of the DARPA CHATS research pro-
gram.
BSD June 16, 2005 BSD
Mac OS X 10.8 - Generated Wed Aug 29 15:48:56 CDT 2012