/*      $OpenBSD: login_fbtab.c,v 1.22 2026/03/11 14:59:10 deraadt Exp $        */

/************************************************************************
* Copyright 1995 by Wietse Venema.  All rights reserved.  Some individual
* files may be covered by other copyrights.
*
* This material was originally written and compiled by Wietse Venema at
* Eindhoven University of Technology, The Netherlands, in 1990, 1991,
* 1992, 1993, 1994 and 1995.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that this entire copyright notice
* is duplicated in all such copies.
*
* This software is provided "as is" and without any expressed or implied
* warranties, including, without limitation, the implied warranties of
* merchantibility and fitness for any particular purpose.
************************************************************************/
/*
    SYNOPSIS
        void login_fbtab(const char *tty, uid_t uid, gid_t gid);

    DESCRIPTION
        This module implements device security as described in the
        SunOS 4.1.x fbtab(5) and SunOS 5.x logindevperm(4) manual
        pages. The program first looks for /etc/fbtab. If that file
        cannot be opened it attempts to process /etc/logindevperm.
        We expect entries with the following format:

            Comments start with a # and extend to the end of the line.

            Blank lines or lines with only a comment are ignored.

            All other lines consist of three fields delimited by
            whitespace: a login device (/dev/console), an octal
            permission number (0600), and a ":"-delimited list of
            devices (/dev/kbd:/dev/mouse). All device names are
            absolute paths. A path that ends in "*" refers to all
            directory entries except "." and "..".

            If the tty argument (relative path) matches a login device
            name (absolute path), the permissions of the devices in the
            ":"-delimited list are set as specified in the second
            field, and their ownership is changed to that of the uid
            and gid arguments.

    DIAGNOSTICS
        Problems are reported via the syslog daemon with severity
        LOG_ERR.

    AUTHOR
        Wietse Venema (wietse@wzv.win.tue.nl)
        Eindhoven University of Technology
        The Netherlands
 */

#include <sys/types.h>
#include <sys/stat.h>

#include <errno.h>
#include <limits.h>
#include <glob.h>
#include <paths.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
#include <util.h>

#define _PATH_FBTAB     "/etc/fbtab"

static void login_protect(const char *, mode_t, uid_t, gid_t);

#define WSPACE          " \t\n"

/*
 * login_fbtab - apply protections specified in /etc/fbtab or logindevperm
 */
void
login_fbtab(const char *tty, uid_t uid, gid_t gid)
{
        FILE    *fp;
        char    *buf = NULL;
        size_t  bufsize = 0;
        char    *toklast, *devnam, *cp;
        mode_t  prot;
        ssize_t len;

        if ((fp = fopen(_PATH_FBTAB, "re")) == NULL)
                return;

        while ((len = getline(&buf, &bufsize, fp)) != -1) {
                if (buf[len - 1] == '\n')
                        buf[len - 1] = '\0';
                if ((cp = strchr(buf, '#')))
                        *cp = '\0';     /* strip comment */
                if (buf[0] == '\0' ||
                    (cp = devnam = strtok_r(buf, WSPACE, &toklast)) == NULL)
                        continue;       /* empty or comment */
                if (strncmp(devnam, _PATH_DEV, sizeof(_PATH_DEV) - 1) != 0 ||
                    (cp = strtok_r(NULL, WSPACE, &toklast)) == NULL ||
                    *cp != '0' ||
                    sscanf(cp, "%o", &prot) == 0 ||
                    prot == 0 ||
                    (prot & 0777) != prot ||
                    (cp = strtok_r(NULL, WSPACE, &toklast)) == NULL) {
                        syslog(LOG_ERR, "%s: bad entry: %s", _PATH_FBTAB,
                            cp ? cp : "(null)");
                        continue;
                }
                if (strcmp(devnam + sizeof(_PATH_DEV) - 1, tty) == 0) {
                        for (cp = strtok_r(cp, ":", &toklast); cp != NULL;
                            cp = strtok_r(NULL, ":", &toklast))
                                login_protect(cp, prot, uid, gid);
                }
        }
        free(buf);
        fclose(fp);
}

/*
 * login_protect - protect one device entry
 */
static void
login_protect(const char *path, mode_t mask, uid_t uid, gid_t gid)
{
        glob_t  g;
        size_t  n;
        char    *gpath;

        if (strlen(path) >= PATH_MAX) {
                errno = ENAMETOOLONG;
                syslog(LOG_ERR, "%s: %s: %m", _PATH_FBTAB, path);
                return;
        }

        if (glob(path, GLOB_NOSORT, NULL, &g) != 0) {
                if (errno != ENOENT)
                        syslog(LOG_ERR, "%s: glob(%s): %m", _PATH_FBTAB, path);
                globfree(&g);
                return;
        }

        for (n = 0; n < g.gl_matchc; n++) {
                gpath = g.gl_pathv[n];

                if (chown(gpath, uid, gid) && errno != ENOENT)
                        syslog(LOG_ERR, "%s: chown(%s): %m", _PATH_FBTAB, gpath);
                if (chmod(gpath, mask) && errno != ENOENT)
                        syslog(LOG_ERR, "%s: chmod(%s): %m", _PATH_FBTAB, gpath);
        }

        globfree(&g);
}