From 9ada0093e92388590c7368600ca4e9e3e376f0d0 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 16:22:51 +0200 Subject: Adding upstream version 1.5.2. Signed-off-by: Daniel Baumann --- doc/man/pam_conv.3 | 177 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 177 insertions(+) create mode 100644 doc/man/pam_conv.3 (limited to 'doc/man/pam_conv.3') diff --git a/doc/man/pam_conv.3 b/doc/man/pam_conv.3 new file mode 100644 index 0000000..5f65b2e --- /dev/null +++ b/doc/man/pam_conv.3 @@ -0,0 +1,177 @@ +'\" t +.\" Title: pam_conv +.\" Author: [FIXME: author] [see http://docbook.sf.net/el/author] +.\" Generator: DocBook XSL Stylesheets v1.79.1 +.\" Date: 09/03/2021 +.\" Manual: Linux-PAM Manual +.\" Source: Linux-PAM Manual +.\" Language: English +.\" +.TH "PAM_CONV" "3" "09/03/2021" "Linux-PAM Manual" "Linux-PAM Manual" +.\" ----------------------------------------------------------------- +.\" * Define some portability stuff +.\" ----------------------------------------------------------------- +.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +.\" http://bugs.debian.org/507673 +.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html +.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +.ie \n(.g .ds Aq \(aq +.el .ds Aq ' +.\" ----------------------------------------------------------------- +.\" * set default formatting +.\" ----------------------------------------------------------------- +.\" disable hyphenation +.nh +.\" disable justification (adjust text to left margin only) +.ad l +.\" ----------------------------------------------------------------- +.\" * MAIN CONTENT STARTS HERE * +.\" ----------------------------------------------------------------- +.SH "NAME" +pam_conv \- PAM conversation function +.SH "SYNOPSIS" +.sp +.ft B +.nf +#include +.fi +.ft +.sp +.nf +struct pam_message { + int msg_style; + const char *msg; +}; + +struct pam_response { + char *resp; + int resp_retcode; +}; + +struct pam_conv { + int (*conv)(int num_msg, const struct pam_message **msg, + struct pam_response **resp, void *appdata_ptr); + void *appdata_ptr; +}; + +.fi +.SH "DESCRIPTION" +.PP +The PAM library uses an application\-defined callback to allow a direct communication between a loaded module and the application\&. This callback is specified by the +\fIstruct pam_conv\fR +passed to +\fBpam_start\fR(3) +at the start of the transaction\&. +.PP +When a module calls the referenced conv() function, the argument +\fIappdata_ptr\fR +is set to the second element of this structure\&. +.PP +The other arguments of a call to conv() concern the information exchanged by module and application\&. That is to say, +\fInum_msg\fR +holds the length of the array of pointers, +\fImsg\fR\&. After a successful return, the pointer +\fIresp\fR +points to an array of pam_response structures, holding the application supplied text\&. The +\fIresp_retcode\fR +member of this struct is unused and should be set to zero\&. It is the caller\*(Aqs responsibility to release both, this array and the responses themselves, using +\fBfree\fR(3)\&. Note, +\fI*resp\fR +is a +\fIstruct pam_response\fR +array and not an array of pointers\&. +.PP +The number of responses is always equal to the +\fInum_msg\fR +conversation function argument\&. This does require that the response array is +\fBfree\fR(3)\*(Aqd after every call to the conversation function\&. The index of the responses corresponds directly to the prompt index in the pam_message array\&. +.PP +On failure, the conversation function should release any resources it has allocated, and return one of the predefined PAM error codes\&. +.PP +Each message can have one of four types, specified by the +\fImsg_style\fR +member of +\fIstruct pam_message\fR: +.PP +PAM_PROMPT_ECHO_OFF +.RS 4 +Obtain a string without echoing any text\&. +.RE +.PP +PAM_PROMPT_ECHO_ON +.RS 4 +Obtain a string whilst echoing text\&. +.RE +.PP +PAM_ERROR_MSG +.RS 4 +Display an error message\&. +.RE +.PP +PAM_TEXT_INFO +.RS 4 +Display some text\&. +.RE +.PP +The point of having an array of messages is that it becomes possible to pass a number of things to the application in a single call from the module\&. It can also be convenient for the application that related things come at once: a windows based application can then present a single form with many messages/prompts on at once\&. +.PP +In passing, it is worth noting that there is a discrepancy between the way Linux\-PAM handles the const struct pam_message **msg conversation function argument and the way that Solaris\*(Aq PAM (and derivatives, known to include HP/UX, are there others?) does\&. Linux\-PAM interprets the msg argument as entirely equivalent to the following prototype const struct pam_message *msg[] (which, in spirit, is consistent with the commonly used prototypes for argv argument to the familiar main() function: char **argv; and char *argv[])\&. Said another way Linux\-PAM interprets the msg argument as a pointer to an array of num_msg read only \*(Aqstruct pam_message\*(Aq pointers\&. Solaris\*(Aq PAM implementation interprets this argument as a pointer to a pointer to an array of num_msg pam_message structures\&. Fortunately, perhaps, for most module/application developers when num_msg has a value of one these two definitions are entirely equivalent\&. Unfortunately, casually raising this number to two has led to unanticipated compatibility problems\&. +.PP +For what its worth the two known module writer work\-arounds for trying to maintain source level compatibility with both PAM implementations are: +.sp +.RS 4 +.ie n \{\ +\h'-04'\(bu\h'+03'\c +.\} +.el \{\ +.sp -1 +.IP \(bu 2.3 +.\} +never call the conversation function with num_msg greater than one\&. +.RE +.sp +.RS 4 +.ie n \{\ +\h'-04'\(bu\h'+03'\c +.\} +.el \{\ +.sp -1 +.IP \(bu 2.3 +.\} +set up msg as doubly referenced so both types of conversation function can find the messages\&. That is, make +.sp +.if n \{\ +.RS 4 +.\} +.nf + msg[n] = & (( *msg )[n]) + +.fi +.if n \{\ +.RE +.\} +.RE +.SH "RETURN VALUES" +.PP +PAM_BUF_ERR +.RS 4 +Memory buffer error\&. +.RE +.PP +PAM_CONV_ERR +.RS 4 +Conversation failure\&. The application should not set +\fI*resp\fR\&. +.RE +.PP +PAM_SUCCESS +.RS 4 +Success\&. +.RE +.SH "SEE ALSO" +.PP +\fBpam_start\fR(3), +\fBpam_set_item\fR(3), +\fBpam_get_item\fR(3), +\fBpam_strerror\fR(3), +\fBpam\fR(8) -- cgit v1.2.3