1 /* $NetBSD: utmp_update.c,v 1.8 2008/04/28 20:23:04 martin 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 #include <sys/types.h> 34 #include <sys/param.h> 35 #include <sys/stat.h> 36 37 #include <stdio.h> 38 #include <vis.h> 39 #include <err.h> 40 #include <fcntl.h> 41 #include <pwd.h> 42 #include <utmpx.h> 43 #include <stdlib.h> 44 #include <string.h> 45 #include <unistd.h> 46 #include <paths.h> 47 48 int 49 main(int argc, char *argv[]) 50 { 51 struct utmpx *utx; 52 size_t len; 53 struct passwd *pwd; 54 struct stat st; 55 int fd; 56 int res; 57 uid_t euid, ruid; 58 char tty[MAXPATHLEN]; 59 60 euid = geteuid(); 61 ruid = getuid(); 62 if (seteuid(ruid) == -1) 63 err(1, "seteuid"); 64 65 if (argc != 2) { 66 (void)fprintf(stderr, "Usage: %s <vis-utmpx-entry>\n", 67 getprogname()); 68 exit(1); 69 } 70 71 len = strlen(argv[1]); 72 73 if (len > sizeof(*utx) * 4 + 1 || len < sizeof(*utx)) 74 errx(1, "Bad argument"); 75 76 if ((utx = malloc(len)) == NULL) 77 err(1, NULL); 78 79 res = strunvis((char *)utx, argv[1]); 80 if (res != (int)sizeof(*utx)) 81 errx(1, "Decoding error %s %d != %zu", argv[1], res, sizeof(*utx)); 82 83 switch (utx->ut_type) { 84 case USER_PROCESS: 85 case DEAD_PROCESS: 86 break; 87 default: 88 errx(1, "Invalid utmpx type %d", (int)utx->ut_type); 89 } 90 91 if (ruid != 0) { 92 if ((pwd = getpwuid(ruid)) == NULL) 93 errx(1, "User %lu does not exist in password database", 94 (long)ruid); 95 96 if (strcmp(pwd->pw_name, utx->ut_name) != 0) 97 errx(1, "Current user `%s' does not match " 98 "`%s' in utmpx entry", pwd->pw_name, utx->ut_name); 99 } 100 101 (void)snprintf(tty, sizeof(tty), "%s%s", _PATH_DEV, utx->ut_line); 102 fd = open(tty, O_RDONLY|O_NONBLOCK, 0); 103 if (fd != -1) { 104 if (fstat(fd, &st) == -1) 105 err(1, "Cannot stat `%s'", tty); 106 if (ruid != 0 && st.st_uid != ruid) 107 errx(1, "%s: Is not owned by you", tty); 108 if (!isatty(fd)) 109 errx(1, "%s: Not a tty device", tty); 110 (void)close(fd); 111 if (access(tty, W_OK|R_OK) == -1) 112 err(1, "%s", tty); 113 } else { 114 struct utmpx utold, *utoldp; 115 /* 116 * A daemon like ftpd that does not use a tty line? 117 * We only allow it to kill its own existing entries 118 */ 119 if (utx->ut_type != DEAD_PROCESS) 120 err(1, "Cannot open `%s'", tty); 121 122 (void)memcpy(utold.ut_line, utx->ut_line, sizeof(utx->ut_line)); 123 if ((utoldp = getutxline(&utold)) == NULL) 124 err(1, "Cannot find existing entry for `%s'", 125 utx->ut_line); 126 if (utoldp->ut_pid != getppid()) 127 err(1, "Cannot modify entry for `%s'", tty); 128 } 129 130 (void)seteuid(euid); 131 if (pututxline(utx) == NULL) 132 err(1, "Cannot update utmp entry"); 133 134 return 0; 135 } 136