commands/simple/su.c

   1 /* su - become super-user               Author: Patrick van Kleef */
   2
   3 #include <sys/types.h>
   4 #include <pwd.h>
   5 #include <grp.h>
   6 #include <stdio.h>
   7 #include <stdlib.h>
   8 #include <string.h>
   9 #include <unistd.h>
  10 #include <limits.h>
  11 #include <fcntl.h>
  12 #include <time.h>
  13 #if __minix_vmd
  14 #include <sys/syslog.h>
  15 #endif
  16 #include <minix/minlib.h>
  17
  18 _PROTOTYPE(int main, (int argc, char **argv));
  19
  20 int main(argc, argv)
  21 int argc;
  22 char *argv[];
  23 {
  24   register char *name, *password;
  25   char *shell, sh0[100];
  26   char from_user[8+1], from_shell[100];
  27   register struct passwd *pwd;
  28   char USER[20], LOGNAME[25], HOME[100], SHELL[100];
  29   char *envv[20], **envp;
  30   int smallenv;
  31   char *p;
  32   int super;
  33   int loginshell;
  34 #if __minix_vmd
  35   gid_t groups[NGROUPS_MAX];
  36   int ngroups;
  37   int g;
  38 #endif
  39
  40   smallenv = 0;
  41   loginshell = 0;
  42   if (argc > 1 && (strcmp(argv[1], "-") == 0 || strcmp(argv[1], "-e") == 0)) {
  43         if (argv[1][1] == 0)
  44                 loginshell= 1;          /* 'su -' reads .profile */
  45         argv[1] = argv[0];
  46         argv++;
  47         argc--;
  48         smallenv = 1;   /* Use small environment. */
  49   }
  50   if (argc > 1) {
  51         if (argv[1][0] == '-') {
  52                 fprintf(stderr,
  53                         "Usage: su [-[e]] [user [shell-arguments ...]]\n");
  54                 exit(1);
  55         }
  56         name = argv[1];
  57         argv[1] = argv[0];
  58         argv++;
  59   } else {
  60         name = "root";
  61   }
  62
  63   if ((pwd = getpwuid(getuid())) == 0) {
  64         fprintf(stderr, "You do not exist\n");
  65         exit(1);
  66   }
  67   strncpy(from_user, pwd->pw_name, 8);
  68   from_user[8]= 0;
  69   strncpy(from_shell, pwd->pw_shell[0] == '\0' ? "/bin/sh" : pwd->pw_shell,
  70                                                 sizeof(from_shell)-1);
  71   from_shell[sizeof(from_shell)-1]= 0;
  72
  73   if ((pwd = getpwnam(name)) == 0) {
  74         fprintf(stderr, "Unknown id: %s\n", name);
  75         exit(1);
  76   }
  77   super = 0;
  78   if (getgid() == 0) super = 1;
  79 #if __minix_vmd
  80   ngroups = getgroups(NGROUPS_MAX, groups);
  81   for (g = 0; g < ngroups; g++) if (groups[g] == 0) super = 1;
  82 #endif
  83
  84   if (!super && strcmp(pwd->pw_passwd, crypt("", pwd->pw_passwd)) != 0) {
  85 #if __minix_vmd
  86         openlog("su", 0, LOG_AUTH);
  87 #endif
  88         password = getpass("Password:");
  89         if (password == 0
  90           || strcmp(pwd->pw_passwd, crypt(password, pwd->pw_passwd)) != 0) {
  91                 if (password != 0 && *password != 0) {
  92 #if __minix_vmd
  93                         syslog(LOG_WARNING, "su %s failed for %s",
  94                                                         name, from_user);
  95 #endif
  96                 }
  97                 fprintf(stderr, "Sorry\n");
  98                 exit(2);
  99         }
 100 #if __minix_vmd
 101         syslog(LOG_NOTICE, "su %s succeeded for %s", name, from_user);
 102         closelog();
 103 #endif
 104   }
 105
 106 #if __minix_vmd
 107   initgroups(pwd->pw_name, pwd->pw_gid);
 108 #endif
 109   setgid(pwd->pw_gid);
 110   setuid(pwd->pw_uid);
 111   if (loginshell) {
 112         shell = pwd->pw_shell[0] == '\0' ? "/bin/sh" : pwd->pw_shell;
 113   } else {
 114         if ((shell = getenv("SHELL")) == NULL) shell = from_shell;
 115   }
 116   if ((p= strrchr(shell, '/')) == 0) p= shell; else p++;
 117   sh0[0]= '-';
 118   strcpy(loginshell ? sh0+1 : sh0, p);
 119   argv[0]= sh0;
 120
 121   if (smallenv) {
 122         envp = envv;
 123         *envp++ = "PATH=:/bin:/usr/bin",
 124         strcpy(USER, "USER=");
 125         strcpy(USER + 5, name);
 126         *envp++ = USER;
 127         strcpy(LOGNAME, "LOGNAME=");
 128         strcpy(LOGNAME + 8, name);
 129         *envp++ = LOGNAME;
 130         strcpy(SHELL, "SHELL=");
 131         strcpy(SHELL + 6, shell);
 132         *envp++ = SHELL;
 133         strcpy(HOME, "HOME=");
 134         strcpy(HOME + 5, pwd->pw_dir);
 135         *envp++ = HOME;
 136         if ((p = getenv("TERM")) != NULL) {
 137                 *envp++ = p - 5;
 138         }
 139         if ((p = getenv("TERMCAP")) != NULL) {
 140                 *envp++ = p - 8;
 141         }
 142         if ((p = getenv("TZ")) != NULL) {
 143                 *envp++ = p - 3;
 144         }
 145         *envp = NULL;
 146         (void) chdir(pwd->pw_dir);
 147         execve(shell, argv, envv);
 148         perror(shell);
 149   } else {
 150         execv(shell, argv);
 151         perror(shell);
 152   }
 153   fprintf(stderr, "No shell\n");
 154   return(3);
 155 }