basic shell

[Ed Sutter]

Hi,
I'm using dropbear in an embedded linux application pulled in with 
buildroot.
In normal situations it appears to be working fine.
For my project though, I need to run a custom shell that only provides 
the user
with VERY minimal access to the system all through builtins. When I set up a
new user to run this shell and log in from my system's serial port 
console it
works just fine; however, when I try to login as that user using ssh, I 
get...

Permission denied, please try again.

I've narrowed the problem down significantly by running the executable
(as the shell) that is  built with this code:

#include <stdio.h>
#include <stdlib.h>

#define MAX_LENGTH 1024

int main(int argc, char *argv[]) {
   char line[MAX_LENGTH];

   while (1) {
     printf("MYSHELL: ");
     if (!fgets(line, MAX_LENGTH, stdin)) break;
     printf("You typed: <%s>\n",line);
   }

   return 0;
}

Obviously this does nothing, but it *should* work from dropbear's point
of view right?  Any idea why running this as my shell fails with SSH?
Thanks,
Ed