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/*
* $Id$
*/
/* Andrew Morgan (morgan@kernel.org) -- an example application
* that invokes a shell, based on blank.c */
#include <stdio.h>
#include <stdlib.h>
#include <security/pam_appl.h>
#include <security/pam_misc.h>
/* ------ some local (static) functions ------- */
static void bail_out(pam_handle_t *pamh,int really, int code, const char *fn)
{
fprintf(stderr,"==> called %s()\n got: `%s'\n", fn,
pam_strerror(pamh,code));
if (really && code)
exit (1);
}
/* ------ some static data objects ------- */
static struct pam_conv conv = {
misc_conv,
NULL
};
/* ------- the application itself -------- */
int main(int argc, char **argv)
{
pam_handle_t *pamh=NULL;
char *username=NULL;
int retcode;
/* did the user call with a username as an argument ? */
if (argc > 2) {
fprintf(stderr,"usage: %s [username]\n",argv[0]);
} else if (argc == 2) {
username = argv[1];
}
/* initialize the Linux-PAM library */
retcode = pam_start("xsh", username, &conv, &pamh);
bail_out(pamh,1,retcode,"pam_start");
/* to avoid using goto we abuse a loop here */
for (;;) {
/* authenticate the user --- `0' here, could have been PAM_SILENT
* | PAM_DISALLOW_NULL_AUTHTOK */
retcode = pam_authenticate(pamh, 0);
bail_out(pamh,0,retcode,"pam_authenticate");
/* has the user proved themself valid? */
if (retcode != PAM_SUCCESS) {
fprintf(stderr,"%s: invalid request\n",argv[0]);
break;
}
/* the user is valid, but should they have access at this
time? */
retcode = pam_acct_mgmt(pamh, 0); /* `0' could be as above */
bail_out(pamh,0,retcode,"pam_acct_mgmt");
if (retcode == PAM_NEW_AUTHTOK_REQD) {
fprintf(stderr,"Application must request new password...\n");
retcode = pam_chauthtok(pamh,PAM_CHANGE_EXPIRED_AUTHTOK);
bail_out(pamh,0,retcode,"pam_chauthtok");
}
if (retcode != PAM_SUCCESS) {
fprintf(stderr,"%s: invalid request\n",argv[0]);
break;
}
/* `0' could be as above */
retcode = pam_setcred(pamh, PAM_ESTABLISH_CRED);
bail_out(pamh,0,retcode,"pam_setcred");
if (retcode != PAM_SUCCESS) {
fprintf(stderr,"%s: problem setting user credentials\n"
,argv[0]);
break;
}
/* open a session for the user --- `0' could be PAM_SILENT */
retcode = pam_open_session(pamh,0);
bail_out(pamh,0,retcode,"pam_open_session");
if (retcode != PAM_SUCCESS) {
fprintf(stderr,"%s: problem opening a session\n",argv[0]);
break;
}
fprintf(stderr,"The user has been authenticated and `logged in'\n");
/* this is always a really bad thing for security! */
system("/bin/sh");
/* close a session for the user --- `0' could be PAM_SILENT
* it is possible that this pam_close_call is in another program..
*/
retcode = pam_close_session(pamh,0);
bail_out(pamh,0,retcode,"pam_close_session");
if (retcode != PAM_SUCCESS) {
fprintf(stderr,"%s: problem closing a session\n",argv[0]);
break;
}
break; /* don't go on for ever! */
}
/* close the Linux-PAM library */
retcode = pam_end(pamh, PAM_SUCCESS);
pamh = NULL;
bail_out(pamh,1,retcode,"pam_end");
exit(0);
}
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