1 /*- 2 * Copyright (c) 2006 nCircle Network Security, Inc. 3 * All rights reserved. 4 * 5 * This software was developed by Robert N. M. Watson for the TrustedBSD 6 * Project under contract to nCircle Network Security, Inc. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR, NCIRCLE NETWORK SECURITY, 21 * INC., OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 22 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED 23 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 24 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF 25 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING 26 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 27 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28 * 29 * $FreeBSD$ 30 */ 31 32 /* 33 * Confirm that a generation number isn't returned by stat() when not running 34 * with privilege. In order to differentiate between a generation of 0 and 35 * a generation not being returned, we have to create a temporary file known 36 * to have a non-0 generation. We try up to 10 times, and then give up, 37 * which is non-ideal, but better than not testing for a problem. 38 */ 39 40 #include <sys/stat.h> 41 42 #include <err.h> 43 #include <errno.h> 44 #include <string.h> 45 #include <unistd.h> 46 47 #include "main.h" 48 49 /* 50 * Can't use setup_file() since the resulting file needs to have specific 51 * properties. 52 */ 53 void 54 priv_vfs_generation(void) 55 { 56 char fpath[1024] = "/tmp/priv.XXXXXXXXXX"; 57 struct stat sb; 58 int fd, i; 59 60 assert_root(); 61 62 /* 63 * Create a file with a non-0 generation number. Try ten times, 64 * which gives a high chance of succeeds, fail otherwise. Not ideal, 65 * since we can't distinguish the file having a generation of 0 from 66 * not being able to query it for access control reasons. The perils 67 * of an API that changes behavior based on lack of privilege rather 68 * than failing... 69 */ 70 for (i = 0; i < 10; i++) { 71 fd = mkstemp(fpath); 72 if (fd < 0) 73 err(-1, "mkstemp"); 74 if (fstat(fd, &sb) < 0) { 75 warn("fstat(%s)", fpath); 76 close(fd); 77 goto out; 78 } 79 if (sb.st_gen != 0) 80 break; 81 close(fd); 82 (void)unlink(fpath); 83 strcpy(fpath, "/tmp/generation.XXXXXXXXXX"); 84 fd = -1; 85 } 86 if (fd == -1) 87 errx(-1, 88 "could not create file with non-0 generation as root"); 89 close(fd); 90 91 /* 92 * We've already tested that fstat() works, but try stat() to be 93 * consistent between privileged and unprivileged tests. 94 */ 95 if (stat(fpath, &sb) < 0) { 96 warn("stat(%s) as root", fpath); 97 goto out; 98 } 99 100 set_euid(UID_OTHER); 101 102 if (stat(fpath, &sb) < 0) { 103 warn("stat(%s) as !root", fpath); 104 goto out; 105 } 106 107 if (sb.st_gen != 0) 108 warn("stat(%s) returned generation as !root", fpath); 109 110 out: 111 (void)seteuid(UID_ROOT); 112 (void)unlink(fpath); 113 } 114