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 main(int, char *[]); 49 50 int 51 main(int argc, char *argv[]) 52 { 53 struct utmpx *utx; 54 size_t len; 55 struct passwd *pwd; 56 struct stat st; 57 int fd; 58 int res; 59 uid_t euid, ruid; 60 char tty[MAXPATHLEN]; 61 62 euid = geteuid(); 63 ruid = getuid(); 64 if (seteuid(ruid) == -1) 65 err(1, "seteuid"); 66 67 if (argc != 2) { 68 (void)fprintf(stderr, "Usage: %s <vis-utmpx-entry>\n", 69 getprogname()); 70 exit(1); 71 } 72 73 len = strlen(argv[1]); 74 75 if (len > sizeof(*utx) * 4 + 1 || len < sizeof(*utx)) 76 errx(1, "Bad argument"); 77 78 if ((utx = malloc(len)) == NULL) 79 err(1, NULL); 80 81 res = strunvis((char *)utx, argv[1]); 82 if (res != (int)sizeof(*utx)) 83 errx(1, "Decoding error %s %d != %zu", argv[1], res, sizeof(*utx)); 84 85 switch (utx->ut_type) { 86 case USER_PROCESS: 87 case DEAD_PROCESS: 88 break; 89 default: 90 errx(1, "Invalid utmpx type %d", (int)utx->ut_type); 91 } 92 93 if (ruid != 0) { 94 if ((pwd = getpwuid(ruid)) == NULL) 95 errx(1, "User %lu does not exist in password database", 96 (long)ruid); 97 98 if (strcmp(pwd->pw_name, utx->ut_name) != 0) 99 errx(1, "Current user `%s' does not match " 100 "`%s' in utmpx entry", pwd->pw_name, utx->ut_name); 101 } 102 103 (void)snprintf(tty, sizeof(tty), "%s%s", _PATH_DEV, utx->ut_line); 104 fd = open(tty, O_RDONLY|O_NONBLOCK, 0); 105 if (fd != -1) { 106 if (fstat(fd, &st) == -1) 107 err(1, "Cannot stat `%s'", tty); 108 if (ruid != 0 && st.st_uid != ruid) 109 errx(1, "%s: Is not owned by you", tty); 110 if (!isatty(fd)) 111 errx(1, "%s: Not a tty device", tty); 112 (void)close(fd); 113 if (access(tty, W_OK|R_OK) == -1) 114 err(1, "%s", tty); 115 } else { 116 struct utmpx utold, *utoldp; 117 /* 118 * A daemon like ftpd that does not use a tty line? 119 * We only allow it to kill its own existing entries 120 */ 121 if (utx->ut_type != DEAD_PROCESS) 122 err(1, "Cannot open `%s'", tty); 123 124 (void)memcpy(utold.ut_line, utx->ut_line, sizeof(utx->ut_line)); 125 if ((utoldp = getutxline(&utold)) == NULL) 126 err(1, "Cannot find existing entry for `%s'", 127 utx->ut_line); 128 if (utoldp->ut_pid != getppid()) 129 err(1, "Cannot modify entry for `%s'", tty); 130 } 131 132 (void)seteuid(euid); 133 if (pututxline(utx) == NULL) 134 err(1, "Cannot update utmp entry"); 135 136 return 0; 137 } 138