1 /* $OpenBSD: login_fbtab.c,v 1.12 2004/09/18 19:22:42 deraadt Exp $ */ 2 3 /************************************************************************ 4 * Copyright 1995 by Wietse Venema. All rights reserved. Some individual 5 * files may be covered by other copyrights. 6 * 7 * This material was originally written and compiled by Wietse Venema at 8 * Eindhoven University of Technology, The Netherlands, in 1990, 1991, 9 * 1992, 1993, 1994 and 1995. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that this entire copyright notice 13 * is duplicated in all such copies. 14 * 15 * This software is provided "as is" and without any expressed or implied 16 * warranties, including, without limitation, the implied warranties of 17 * merchantibility and fitness for any particular purpose. 18 ************************************************************************/ 19 /* 20 SYNOPSIS 21 void login_fbtab(tty, uid, gid) 22 char *tty; 23 uid_t uid; 24 gid_t gid; 25 26 DESCRIPTION 27 This module implements device security as described in the 28 SunOS 4.1.x fbtab(5) and SunOS 5.x logindevperm(4) manual 29 pages. The program first looks for /etc/fbtab. If that file 30 cannot be opened it attempts to process /etc/logindevperm. 31 We expect entries with the folowing format: 32 33 Comments start with a # and extend to the end of the line. 34 35 Blank lines or lines with only a comment are ignored. 36 37 All other lines consist of three fields delimited by 38 whitespace: a login device (/dev/console), an octal 39 permission number (0600), and a ":"-delimited list of 40 devices (/dev/kbd:/dev/mouse). All device names are 41 absolute paths. A path that ends in "*" refers to all 42 directory entries except "." and "..". 43 44 If the tty argument (relative path) matches a login device 45 name (absolute path), the permissions of the devices in the 46 ":"-delimited list are set as specified in the second 47 field, and their ownership is changed to that of the uid 48 and gid arguments. 49 50 DIAGNOSTICS 51 Problems are reported via the syslog daemon with severity 52 LOG_ERR. 53 54 AUTHOR 55 Wietse Venema (wietse@wzv.win.tue.nl) 56 Eindhoven University of Technology 57 The Netherlands 58 */ 59 60 #include <sys/types.h> 61 #include <sys/stat.h> 62 63 #include <errno.h> 64 #include <dirent.h> 65 #include <limits.h> 66 #include <paths.h> 67 #include <stdio.h> 68 #include <stdlib.h> 69 #include <string.h> 70 #include <syslog.h> 71 #include <unistd.h> 72 #include <util.h> 73 74 #define _PATH_FBTAB "/etc/fbtab" 75 76 static void login_protect(const char *, int, uid_t, gid_t); 77 78 #define WSPACE " \t\n" 79 80 /* 81 * login_fbtab - apply protections specified in /etc/fbtab or logindevperm 82 */ 83 void 84 login_fbtab(const char *tty, uid_t uid, gid_t gid) 85 { 86 FILE *fp; 87 char *buf, *toklast, *tbuf, *devnam, *cp; 88 int prot; 89 size_t len; 90 91 if ((fp = fopen(_PATH_FBTAB, "r")) == NULL) 92 return; 93 94 tbuf = NULL; 95 while ((buf = fgetln(fp, &len)) != NULL) { 96 if (buf[len - 1] == '\n') 97 buf[len - 1] = '\0'; 98 else { 99 if ((tbuf = (char *)malloc(len + 1)) == NULL) 100 break; 101 memcpy(tbuf, buf, len); 102 tbuf[len] = '\0'; 103 buf = tbuf; 104 } 105 if ((cp = strchr(buf, '#'))) 106 *cp = '\0'; /* strip comment */ 107 if (buf[0] == '\0' || 108 (cp = devnam = strtok_r(buf, WSPACE, &toklast)) == NULL) 109 continue; /* empty or comment */ 110 if (strncmp(devnam, _PATH_DEV, sizeof(_PATH_DEV) - 1) != 0 || 111 (cp = strtok_r(NULL, WSPACE, &toklast)) == NULL || 112 *cp != '0' || 113 sscanf(cp, "%o", &prot) == 0 || 114 prot == 0 || 115 (prot & 0777) != prot || 116 (cp = strtok_r(NULL, WSPACE, &toklast)) == NULL) { 117 syslog(LOG_ERR, "%s: bad entry: %s", _PATH_FBTAB, 118 cp ? cp : "(null)"); 119 continue; 120 } 121 if (strcmp(devnam + sizeof(_PATH_DEV) - 1, tty) == 0) { 122 for (cp = strtok_r(cp, ":", &toklast); cp != NULL; 123 cp = strtok_r(NULL, ":", &toklast)) 124 login_protect(cp, prot, uid, gid); 125 } 126 } 127 if (tbuf != NULL) 128 free(tbuf); 129 fclose(fp); 130 } 131 132 /* 133 * login_protect - protect one device entry 134 */ 135 static void 136 login_protect(const char *path, int mask, uid_t uid, gid_t gid) 137 { 138 char buf[PATH_MAX]; 139 size_t pathlen = strlen(path); 140 DIR *dir; 141 struct dirent *ent; 142 143 if (pathlen >= sizeof(buf)) { 144 errno = ENAMETOOLONG; 145 syslog(LOG_ERR, "%s: %s: %m", _PATH_FBTAB, path); 146 return; 147 } 148 149 if (strcmp("/*", path + pathlen - 2) != 0) { 150 if (chmod(path, mask) && errno != ENOENT) 151 syslog(LOG_ERR, "%s: chmod(%s): %m", _PATH_FBTAB, path); 152 if (chown(path, uid, gid) && errno != ENOENT) 153 syslog(LOG_ERR, "%s: chown(%s): %m", _PATH_FBTAB, path); 154 } else { 155 /* 156 * This is a wildcard directory (/path/to/whatever/*). 157 * Make a copy of path without the trailing '*' (but leave 158 * the trailing '/' so we can append directory entries.) 159 */ 160 memcpy(buf, path, pathlen - 1); 161 buf[pathlen - 1] = '\0'; 162 if ((dir = opendir(buf)) == NULL) { 163 syslog(LOG_ERR, "%s: opendir(%s): %m", _PATH_FBTAB, 164 path); 165 return; 166 } 167 168 while ((ent = readdir(dir)) != NULL) { 169 if (strcmp(ent->d_name, ".") != 0 && 170 strcmp(ent->d_name, "..") != 0) { 171 buf[pathlen - 1] = '\0'; 172 if (strlcat(buf, ent->d_name, sizeof(buf)) 173 >= sizeof(buf)) { 174 errno = ENAMETOOLONG; 175 syslog(LOG_ERR, "%s: %s: %m", 176 _PATH_FBTAB, path); 177 } else 178 login_protect(buf, mask, uid, gid); 179 } 180 } 181 closedir(dir); 182 } 183 } 184