usr.bin/login/login_fbtab.c

   1 /************************************************************************
   2 * Copyright 1995 by Wietse Venema.  All rights reserved.
   3 *
   4 * This material was originally written and compiled by Wietse Venema at
   5 * Eindhoven University of Technology, The Netherlands, in 1990, 1991,
   6 * 1992, 1993, 1994 and 1995.
   7 *
   8 * Redistribution and use in source and binary forms are permitted
   9 * provided that this entire copyright notice is duplicated in all such
  10 * copies.
  11 *
  12 * This software is provided "as is" and without any expressed or implied
  13 * warranties, including, without limitation, the implied warranties of
  14 * merchantibility and fitness for any particular purpose.
  15 ************************************************************************/
  16 /* $FreeBSD: src/usr.bin/login/login_fbtab.c,v 1.18 2007/09/21 01:55:11 kevlo Exp $ */
  17 /*
  18     SYNOPSIS
  19         void login_fbtab(tty, uid, gid)
  20         char *tty;
  21         uid_t uid;
  22         gid_t gid;
  23
  24     DESCRIPTION
  25         This module implements device security as described in the
  26         SunOS 4.1.x fbtab(5) and SunOS 5.x logindevperm(4) manual
  27         pages. The program first looks for /etc/fbtab. If that file
  28         cannot be opened it attempts to process /etc/logindevperm.
  29         We expect entries with the folowing format:
  30
  31             Comments start with a # and extend to the end of the line.
  32
  33             Blank lines or lines with only a comment are ignored.
  34
  35             All other lines consist of three fields delimited by
  36             whitespace: a login device (/dev/console), an octal
  37             permission number (0600), and a ":"-delimited list of
  38             devices (/dev/kbd:/dev/mouse). All device names are
  39             absolute paths. A path that ends in "*" refers to all
  40             directory entries except "." and "..".
  41
  42             If the tty argument (relative path) matches a login device
  43             name (absolute path), the permissions of the devices in the
  44             ":"-delimited list are set as specified in the second
  45             field, and their ownership is changed to that of the uid
  46             and gid arguments.
  47
  48     DIAGNOSTICS
  49         Problems are reported via the syslog daemon with severity
  50         LOG_ERR.
  51
  52     BUGS
  53         This module uses strtok(3), which may cause conflicts with other
  54         uses of that same routine.
  55
  56     AUTHOR
  57         Wietse Venema (wietse@wzv.win.tue.nl)
  58         Eindhoven University of Technology
  59         The Netherlands
  60  */
  61
  62 #include <sys/types.h>
  63 #include <sys/stat.h>
  64 #include <errno.h>
  65 #include <glob.h>
  66 #include <paths.h>
  67 #include <stdio.h>
  68 #include <string.h>
  69 #include <syslog.h>
  70 #include <unistd.h>
  71
  72 #include "login.h"
  73 #include "pathnames.h"
  74
  75 static void     login_protect(const char *, char *, int, uid_t, gid_t);
  76
  77 #define WSPACE          " \t\n"
  78
  79 /* login_fbtab - apply protections specified in /etc/fbtab or logindevperm */
  80
  81 void
  82 login_fbtab(char *tty, uid_t uid, gid_t gid)
  83 {
  84     FILE   *fp;
  85     char    buf[BUFSIZ];
  86     char   *devname;
  87     char   *cp;
  88     int     prot;
  89     const char *table;
  90
  91     if ((fp = fopen(table = _PATH_FBTAB, "r")) == NULL
  92     && (fp = fopen(table = _PATH_LOGINDEVPERM, "r")) == NULL)
  93         return;
  94
  95     while (fgets(buf, sizeof(buf), fp)) {
  96         if ((cp = strchr(buf, '#')))
  97             *cp = 0;                            /* strip comment */
  98         if ((cp = devname = strtok(buf, WSPACE)) == NULL)
  99             continue;                           /* empty or comment */
 100         if (strncmp(devname, _PATH_DEV, sizeof _PATH_DEV - 1) != 0
 101                || (cp = strtok(NULL, WSPACE)) == NULL
 102                || *cp != '0'
 103                || sscanf(cp, "%o", &prot) == 0
 104                || prot == 0
 105                || (prot & 0777) != prot
 106                || (cp = strtok(NULL, WSPACE)) == NULL) {
 107             syslog(LOG_ERR, "%s: bad entry: %s", table, cp ? cp : "(null)");
 108             continue;
 109         }
 110         if (strcmp(devname + 5, tty) == 0) {
 111             for (cp = strtok(cp, ":"); cp; cp = strtok(NULL, ":")) {
 112                 login_protect(table, cp, prot, uid, gid);
 113             }
 114         }
 115     }
 116     fclose(fp);
 117 }
 118
 119 /* login_protect - protect one device entry */
 120
 121 void
 122 login_protect(const char *table, char *pattern, int mask, uid_t uid, gid_t gid)
 123 {
 124     glob_t  gl;
 125     char   *path;
 126     unsigned int     i;
 127
 128     if (glob(pattern, GLOB_NOSORT, NULL, &gl) != 0)
 129         return;
 130     for (i = 0; i < gl.gl_pathc; i++) {
 131         path = gl.gl_pathv[i];
 132         /* clear flags of the device */
 133         if (chflags(path, 0) && errno != ENOENT && errno != EOPNOTSUPP)
 134             syslog(LOG_ERR, "%s: chflags(%s): %m", table, path);
 135         if (chmod(path, mask) && errno != ENOENT)
 136             syslog(LOG_ERR, "%s: chmod(%s): %m", table, path);
 137         if (chown(path, uid, gid) && errno != ENOENT)
 138             syslog(LOG_ERR, "%s: chown(%s): %m", table, path);
 139     }
 140     globfree(&gl);
 141 }