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#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/wait.h>
#include <sys/types.h>
#include <pwd.h>
#include <security/pam_modules.h>
#include <security/pam_modutil.h>
#include <security/pam_appl.h>
#define PAM_TYPE_DOMAIN 1234
/* Either grab a value or prompt for it */
static char *
get_item (pam_handle_t * pamh, int type)
{
/* Check to see if we just have the value. If we do, great
let's dup it some we're consitently allocating memory */
if (type != PAM_TYPE_DOMAIN) {
char * value = NULL;
if (pam_get_item(pamh, type, (const void **)&value) == PAM_SUCCESS && value != NULL) {
return strdup(value);
}
}
/* Now we need to prompt */
/* Build up the message we're prompting for */
struct pam_message message;
const struct pam_message * pmessage = &message;
message.msg = NULL;
message.msg_style = PAM_PROMPT_ECHO_ON;
switch (type) {
case PAM_USER:
message.msg = "login:";
break;
case PAM_RUSER:
message.msg = "remote login:";
break;
case PAM_RHOST:
message.msg = "remote host:";
break;
case PAM_AUTHTOK:
message.msg = "password:";
message.msg_style = PAM_PROMPT_ECHO_OFF;
break;
case PAM_TYPE_DOMAIN:
message.msg = "domain:";
break;
default:
return NULL;
}
struct pam_conv * conv = NULL;
if (pam_get_item(pamh, PAM_CONV, (const void **)&conv) != PAM_SUCCESS || conv == NULL || conv->conv == NULL) {
return NULL;
}
struct pam_response * responses = NULL;
if (conv->conv(1, &pmessage, &responses, conv->appdata_ptr) != PAM_SUCCESS) {
return NULL;
}
char * retval = responses->resp;
free(responses);
return retval;
}
#define GET_ITEM(val, type) \
if ((val = get_item(pamh, type)) == NULL) { \
retval = PAM_AUTH_ERR; \
goto done; \
}
/* TODO: Make this a build thing */
#define XFREERDP "/usr/bin/xfreerdp"
/* Authenticate. We need to make sure we have a user account, that
there are remote accounts and then verify them with FreeRDP */
PAM_EXTERN int
pam_sm_authenticate (pam_handle_t *pamh, int flags, int argc, const char **argv)
{
char * username = NULL;
char * password = NULL;
char * ruser = NULL;
char * rhost = NULL;
char * rdomain = NULL;
int retval = PAM_IGNORE;
/* Get all the values, or prompt for them, or return with
an auth error */
GET_ITEM(username, PAM_USER);
GET_ITEM(ruser, PAM_RUSER);
GET_ITEM(rhost, PAM_RHOST);
GET_ITEM(rdomain, PAM_TYPE_DOMAIN);
GET_ITEM(password, PAM_AUTHTOK);
int stdinpipe[2];
if (pipe(stdinpipe) != 0) {
retval = PAM_SYSTEM_ERR;
goto done;
}
/* At this point we should have the values, let's check the auth */
pid_t pid;
switch (pid = fork()) {
case 0: { /* child */
dup2(stdinpipe[0], 0);
char * args[7];
args[0] = XFREERDP;
args[1] = "--plugin";
args[2] = "rdpsnd.so";
args[3] = "--no-nla";
args[4] = "-f";
args[5] = "--from-stdin";
args[6] = NULL;
struct passwd * pwdent = getpwnam(username);
if (pwdent == NULL) {
_exit(EXIT_FAILURE);
}
if (setgid(pwdent->pw_gid) < 0 || setuid(pwdent->pw_uid) < 0 ||
setegid(pwdent->pw_gid) < 0 || seteuid(pwdent->pw_uid) < 0) {
_exit(EXIT_FAILURE);
}
setenv("HOME", pwdent->pw_dir, 1);
execvp(args[0], args);
_exit(EXIT_FAILURE);
break;
}
case -1: { /* fork'n error! */
retval = PAM_SYSTEM_ERR;
break;
}
default: {
int forkret = 0;
int bytesout = 0;
bytesout += write(stdinpipe[1], ruser, strlen(ruser));
bytesout += write(stdinpipe[1], " ", 1);
bytesout += write(stdinpipe[1], password, strlen(password));
bytesout += write(stdinpipe[1], " ", 1);
bytesout += write(stdinpipe[1], rdomain, strlen(rdomain));
bytesout += write(stdinpipe[1], " ", 1);
bytesout += write(stdinpipe[1], rhost, strlen(rhost));
bytesout += write(stdinpipe[1], " ", 1);
close(stdinpipe[1]);
if (waitpid(pid, &forkret, 0) < 0 || bytesout == 0) {
retval = PAM_SYSTEM_ERR;
} else if (forkret == 0) {
retval = PAM_SUCCESS;
} else {
retval = PAM_AUTH_ERR;
}
}
}
/* Free Memory and return our status */
done:
if (username != NULL) { free(username); }
if (password != NULL) { free(password); }
if (ruser != NULL) { free(ruser); }
if (rhost != NULL) { free(rhost); }
if (rdomain != NULL) { free(rdomain); }
return retval;
}
/* Open Session. Here we need to fork a little process so that we can
give the credentials to the session itself so that it can startup the
xfreerdp viewer for the login */
PAM_EXTERN int
pam_sm_open_session (pam_handle_t *pamh, int flags, int argc, const char **argv)
{
return PAM_IGNORE;
}
/* Close Session. Make sure our little guy has died so he doesn't become
a zombie and eat things. */
PAM_EXTERN int
pam_sm_close_session (pam_handle_t *pamh, int flags, int argc, const char **argv)
{
return PAM_IGNORE;
}
#ifdef PAM_STATIC
struct pam_module _pam_freerdp_modstruct = {
"pam-freerdp",
pam_sm_authenticate,
NULL,
NULL,
pam_sm_open_session,
pam_sm_close_session,
NULL,
};
#endif
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