login-utils/newgrp.c

   1 /* setgrp.c - by Michael Haardt. Set the gid if possible */
   2 /* Added a bit more error recovery/reporting - poe */
   3 /* Vesa Roukonen added code for asking password */
   4 /* Currently maintained at ftp://ftp.daimi.aau.dk/pub/linux/poe/ */
   5
   6 /* 1999-02-22 Arkadiusz Mi¶kiewicz <misiek@misiek.eu.org>
   7  * - added Native Language Support
   8  */
   9
  10 #include <unistd.h>
  11 #include <pwd.h>
  12 #include <grp.h>
  13 #include <string.h>
  14 #include <stdio.h>
  15 #include <stdlib.h>
  16 #include <errno.h>
  17 #include "pathnames.h"
  18 #include "my_crypt.h"
  19 #include "nls.h"
  20
  21 #ifndef TRUE
  22 # define TRUE 1
  23 #endif
  24
  25 #ifndef FALSE
  26 # define FALSE 0
  27 #endif
  28
  29 static int
  30 allow_setgid(struct passwd *pe, struct group *ge)
  31 {
  32     char **look;
  33     int notfound = 1;
  34
  35     if (getuid() == 0) return TRUE;     /* root may do anything */
  36
  37     look = ge->gr_mem;
  38     while (*look && (notfound = strcmp(*look++,pe->pw_name)));
  39
  40     if(!notfound) return TRUE;          /* member of group => OK */
  41
  42     /* Ask for password. Often there is no password in /etc/group, so
  43        contrary to login et al. we let an empty password mean the same
  44        as * in /etc/passwd */
  45
  46     if(ge->gr_passwd && ge->gr_passwd[0] != 0) {
  47         if(strcmp(ge->gr_passwd,
  48                   crypt(getpass(_("Password: ")), ge->gr_passwd)) == 0) {
  49             return TRUE;                /* password accepted */
  50         }
  51     }
  52
  53     return FALSE;                       /* default to denial */
  54 }
  55
  56 int
  57 main(int argc, char *argv[])
  58 {
  59     struct passwd *pw_entry;
  60     struct group *gr_entry;
  61     char *shell;
  62
  63     setlocale(LC_ALL, "");
  64     bindtextdomain(PACKAGE, LOCALEDIR);
  65     textdomain(PACKAGE);
  66
  67     if (!(pw_entry = getpwuid(getuid()))) {
  68         perror(_("newgrp: Who are you?"));
  69         exit(1);
  70     }
  71
  72     shell = (pw_entry->pw_shell[0] ? pw_entry->pw_shell : _PATH_BSHELL);
  73
  74     if (argc < 2) {
  75         if(setgid(pw_entry->pw_gid) < 0) {
  76             perror(_("newgrp: setgid"));
  77             exit(1);
  78         }
  79     } else {
  80         if (!(gr_entry = getgrnam(argv[1]))) {
  81             perror(_("newgrp: No such group."));
  82             exit(1);
  83         } else {
  84             if(allow_setgid(pw_entry, gr_entry)) {
  85                 if(setgid(gr_entry->gr_gid) < 0) {
  86                     perror(_("newgrp: setgid"));
  87                     exit(1);
  88                 }
  89             } else {
  90                 puts(_("newgrp: Permission denied"));
  91                 exit(1);
  92             }
  93         }
  94     }
  95
  96     if(setuid(getuid()) < 0) {
  97         perror(_("newgrp: setuid"));
  98         exit(1);
  99     }
 100
 101     fflush(stdout); fflush(stderr);
 102     execl(shell,shell,(char*)0);
 103     perror(_("No shell"));
 104     fflush(stderr);
 105     exit(1);
 106 }