1 /* $NetBSD: utmp_update.c,v 1.9 2009/04/13 03:38:15 christos Exp $ */ 2 3 /*- 4 * Copyright (c) 2002 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Christos Zoulas. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 #include <sys/cdefs.h> 32 33 __RCSID("$NetBSD: utmp_update.c,v 1.9 2009/04/13 03:38:15 christos Exp $"); 34 35 #include <sys/types.h> 36 #include <sys/param.h> 37 #include <sys/stat.h> 38 39 #include <stdio.h> 40 #include <vis.h> 41 #include <err.h> 42 #include <fcntl.h> 43 #include <pwd.h> 44 #include <utmpx.h> 45 #include <stdlib.h> 46 #include <string.h> 47 #include <unistd.h> 48 #include <paths.h> 49 50 int main(int, char *[]); 51 52 int 53 main(int argc, char *argv[]) 54 { 55 struct utmpx *utx; 56 size_t len; 57 struct passwd *pwd; 58 struct stat st; 59 int fd; 60 int res; 61 uid_t euid, ruid; 62 char tty[MAXPATHLEN]; 63 64 euid = geteuid(); 65 ruid = getuid(); 66 if (seteuid(ruid) == -1) 67 err(1, "seteuid"); 68 69 if (argc != 2) { 70 (void)fprintf(stderr, "Usage: %s <vis-utmpx-entry>\n", 71 getprogname()); 72 exit(1); 73 } 74 75 len = strlen(argv[1]); 76 77 if (len > sizeof(*utx) * 4 + 1 || len < sizeof(*utx)) 78 errx(1, "Bad argument"); 79 80 if ((utx = malloc(len)) == NULL) 81 err(1, NULL); 82 83 res = strunvis((char *)utx, argv[1]); 84 if (res != (int)sizeof(*utx)) 85 errx(1, "Decoding error %s %d != %zu", argv[1], res, sizeof(*utx)); 86 87 switch (utx->ut_type) { 88 case USER_PROCESS: 89 case DEAD_PROCESS: 90 break; 91 default: 92 errx(1, "Invalid utmpx type %d", (int)utx->ut_type); 93 } 94 95 if (ruid != 0) { 96 if ((pwd = getpwuid(ruid)) == NULL) 97 errx(1, "User %lu does not exist in password database", 98 (long)ruid); 99 100 if (strcmp(pwd->pw_name, utx->ut_name) != 0) 101 errx(1, "Current user `%s' does not match " 102 "`%s' in utmpx entry", pwd->pw_name, utx->ut_name); 103 } 104 105 (void)snprintf(tty, sizeof(tty), "%s%s", _PATH_DEV, utx->ut_line); 106 fd = open(tty, O_RDONLY|O_NONBLOCK, 0); 107 if (fd != -1) { 108 if (fstat(fd, &st) == -1) 109 err(1, "Cannot stat `%s'", tty); 110 if (ruid != 0 && st.st_uid != ruid) 111 errx(1, "%s: Is not owned by you", tty); 112 if (!isatty(fd)) 113 errx(1, "%s: Not a tty device", tty); 114 (void)close(fd); 115 if (access(tty, W_OK|R_OK) == -1) 116 err(1, "%s", tty); 117 } else { 118 struct utmpx utold, *utoldp; 119 /* 120 * A daemon like ftpd that does not use a tty line? 121 * We only allow it to kill its own existing entries 122 */ 123 if (utx->ut_type != DEAD_PROCESS) 124 err(1, "Cannot open `%s'", tty); 125 126 (void)memcpy(utold.ut_line, utx->ut_line, sizeof(utx->ut_line)); 127 if ((utoldp = getutxline(&utold)) == NULL) 128 err(1, "Cannot find existing entry for `%s'", 129 utx->ut_line); 130 if (utoldp->ut_pid != getppid()) 131 err(1, "Cannot modify entry for `%s'", tty); 132 } 133 134 (void)seteuid(euid); 135 if (pututxline(utx) == NULL) 136 err(1, "Cannot update utmp entry"); 137 138 return 0; 139 } 140