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