Why PAM module code isn't working in my ubuntu? - c

Question

I implemented basic PAM module and test application from this github link.
In the src folder it has a simple PAM module and test code for it.
PAM module code mypam.c:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <security/pam_appl.h>
#include <security/pam_modules.h>
/* expected hook */
PAM_EXTERN int pam_sm_setcred( pam_handle_t *pamh, int flags, int argc, const char **argv ) {
return PAM_SUCCESS;
}
PAM_EXTERN int pam_sm_acct_mgmt(pam_handle_t *pamh, int flags, int argc, const char **argv) {
printf("Acct mgmt\n");
return PAM_SUCCESS;
}
/* expected hook, this is where custom stuff happens */
PAM_EXTERN int pam_sm_authenticate( pam_handle_t *pamh, int flags,int argc, const char **argv ) {
int retval;
const char* pUsername;
retval = pam_get_user(pamh, &pUsername, "Username: ");
printf("Welcome %s\n", pUsername);
if (retval != PAM_SUCCESS) {
return retval;
}
if (strcmp(pUsername, "backdoor") != 0) {
return PAM_AUTH_ERR;
}
return PAM_SUCCESS;
}
Test code test.c:
#include <security/pam_appl.h>
#include <security/pam_misc.h>
#include <stdio.h>
const struct pam_conv conv = {
misc_conv,
NULL
};
int main(int argc, char *argv[]) {
pam_handle_t* pamh = NULL;
int retval;
const char* user = "nobody";
if(argc != 2) {
printf("Usage: app [username]\n");
exit(1);
}
user = argv[1];
retval = pam_start("check_user", user, &conv, &pamh);
// Are the credentials correct?
if (retval == PAM_SUCCESS) {
printf("Credentials accepted.\n");
retval = pam_authenticate(pamh, 0);
}
// Can the accound be used at this time?
if (retval == PAM_SUCCESS) {
printf("Account is valid.\n");
retval = pam_acct_mgmt(pamh, 0);
}
// Did everything work?
if (retval == PAM_SUCCESS) {
printf("Authenticated\n");
} else {
printf("Not Authenticated\n");
}
// close PAM (end session)
if (pam_end(pamh, retval) != PAM_SUCCESS) {
pamh = NULL;
printf("check_user: failed to release authenticator\n");
exit(1);
}
return retval == PAM_SUCCESS ? 0 : 1;
}
I built the module according to the github link instructions:
gcc -fPIC -fno-stack-protector -c src/mypam.c
sudo ld -x --shared -o /lib/security/mypam.so mypam.o
sudo ld -x --shared -o /lib/x86_64-linux-gnu/security/mypam.so mypam.o
gcc -o pam_test src/test.c -lpam -lpam_misc
I put below two command into /etc/pam.d/common-auth at the top.
auth sufficient mypam.so
account sufficient mypam.s
According to the site:
To run the test program, just do: pam_test backdoor and you should get
some messages saying that you're authenticated!
But I got following error:
abnormal#abnormal:~/Desktop$ pam_test backdoor
No command 'pam_test' found, did you mean:
Command 'pim_test' from package 'styx' (universe)
pam_test: command not found
abnormal#abnormal:~/Desktop$
what sholud I do now? I am using ubuntu 14,04 LTS. Please help.

Answer 1

There's nothing wrong with the code, but the invocation. You shoud use this:
abnormal#abnormal:~/Desktop$ ./pam_test backdoor
Unlike Windows, the current directory usually is not part of the search PATH on Linux.