1 /* $NetBSD: utmp_update.c,v 1.7 2004/11/07 07:04:31 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 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the NetBSD 21 * Foundation, Inc. and its contributors. 22 * 4. Neither the name of The NetBSD Foundation nor the names of its 23 * contributors may be used to endorse or promote products derived 24 * from this software without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 27 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 29 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 30 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 31 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 32 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 35 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 36 * POSSIBILITY OF SUCH DAMAGE. 37 */ 38 #include <sys/cdefs.h> 39 40 __RCSID("$NetBSD: utmp_update.c,v 1.7 2004/11/07 07:04:31 christos Exp $"); 41 42 #include <sys/types.h> 43 #include <sys/param.h> 44 #include <sys/stat.h> 45 46 #include <stdio.h> 47 #include <vis.h> 48 #include <err.h> 49 #include <fcntl.h> 50 #include <pwd.h> 51 #include <utmpx.h> 52 #include <stdlib.h> 53 #include <string.h> 54 #include <unistd.h> 55 #include <paths.h> 56 57 int main(int, char *[]); 58 59 int 60 main(int argc, char *argv[]) 61 { 62 struct utmpx *utx; 63 size_t len; 64 struct passwd *pwd; 65 struct stat st; 66 int fd; 67 uid_t euid, ruid; 68 char tty[MAXPATHLEN]; 69 70 euid = geteuid(); 71 ruid = getuid(); 72 if (seteuid(ruid) == -1) 73 err(1, "seteuid"); 74 75 if (argc != 2) { 76 (void)fprintf(stderr, "Usage: %s <vis-utmpx-entry>\n", 77 getprogname()); 78 exit(1); 79 } 80 81 len = strlen(argv[1]); 82 83 if (len > sizeof(*utx) * 4 + 1 || len < sizeof(*utx)) 84 errx(1, "Bad argument"); 85 86 if ((utx = malloc(len)) == NULL) 87 err(1, NULL); 88 89 if (strunvis((char *)utx, argv[1]) != sizeof(*utx)) 90 errx(1, "Decoding error"); 91 92 switch (utx->ut_type) { 93 case USER_PROCESS: 94 case DEAD_PROCESS: 95 break; 96 default: 97 errx(1, "Invalid utmpx type %d", (int)utx->ut_type); 98 } 99 100 if (ruid != 0) { 101 if ((pwd = getpwuid(ruid)) == NULL) 102 errx(1, "User %lu does not exist in password database", 103 (long)ruid); 104 105 if (strcmp(pwd->pw_name, utx->ut_name) != 0) 106 errx(1, "Current user `%s' does not match " 107 "`%s' in utmpx entry", pwd->pw_name, utx->ut_name); 108 } 109 110 (void)snprintf(tty, sizeof(tty), "%s%s", _PATH_DEV, utx->ut_line); 111 fd = open(tty, O_RDONLY|O_NONBLOCK, 0); 112 if (fd != -1) { 113 if (fstat(fd, &st) == -1) 114 err(1, "Cannot stat `%s'", tty); 115 if (ruid != 0 && st.st_uid != ruid) 116 errx(1, "%s: Is not owned by you", tty); 117 if (!isatty(fd)) 118 errx(1, "%s: Not a tty device", tty); 119 (void)close(fd); 120 if (access(tty, W_OK|R_OK) == -1) 121 err(1, "%s", tty); 122 } else { 123 struct utmpx utold, *utoldp; 124 /* 125 * A daemon like ftpd that does not use a tty line? 126 * We only allow it to kill its own existing entries 127 */ 128 if (utx->ut_type != DEAD_PROCESS) 129 err(1, "Cannot open `%s'", tty); 130 131 (void)memcpy(utold.ut_line, utx->ut_line, sizeof(utx->ut_line)); 132 if ((utoldp = getutxline(&utold)) == NULL) 133 err(1, "Cannot find existing entry for `%s'", 134 utx->ut_line); 135 if (utoldp->ut_pid != getppid()) 136 err(1, "Cannot modify entry for `%s'", tty); 137 } 138 139 (void)seteuid(euid); 140 if (pututxline(utx) == NULL) 141 err(1, "Cannot update utmp entry"); 142 143 return 0; 144 } 145