/* $NetBSD: utmp_update.c,v 1.13.26.1 2024/02/17 16:07:38 martin Exp $ */ /*- * Copyright (c) 2002 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Christos Zoulas. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ #include __RCSID("$NetBSD: utmp_update.c,v 1.13.26.1 2024/02/17 16:07:38 martin Exp $"); #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include static __dead __printflike(2, 3) void logerr(int e, const char *fmt, ...) { va_list sap, eap; char *s = NULL; if (e) (void)asprintf(&s, "%s (%s)", fmt, strerror(e)); if (s) fmt = s; va_start(sap, fmt); va_copy(eap, sap); vsyslog(LOG_ERR, fmt, sap); va_end(sap); verrx(1, fmt, eap); va_end(eap); } int main(int argc, char *argv[]) { struct utmpx *utx; size_t len; struct passwd *pwd; struct stat st; int fd; int res; uid_t euid, ruid; char tty[MAXPATHLEN]; const char *p, *ep; euid = geteuid(); ruid = getuid(); if (argc != 2) { (void)fprintf(stderr, "Usage: %s \n", getprogname()); return 1; } openlog(getprogname(), LOG_PID | LOG_NDELAY, LOG_AUTH); if (seteuid(ruid) == -1) logerr(errno, "Can't setuid %ld", (long)ruid); len = strlen(argv[1]); if (len > sizeof(*utx) * 4 + 1 || len < sizeof(*utx)) logerr(0, "Bad argument size %zu", len); if ((utx = malloc(len+1)) == NULL) logerr(errno, "Can't allocate %zu", len+1); res = strunvis((char *)utx, argv[1]); if (res != (int)sizeof(*utx)) logerr(0, "Decoding error %s %d != %zu", argv[1], res, sizeof(*utx)); switch (utx->ut_type) { case USER_PROCESS: case DEAD_PROCESS: break; default: logerr(0, "Invalid utmpx type %d", (int)utx->ut_type); } p = utx->ut_host; ep = p + sizeof(utx->ut_host); for (; p < ep && *p; p++) if (!isprint((unsigned char)*p)) logerr(0, "Non-printable characters in hostname"); if (ruid != 0) { if ((pwd = getpwuid(ruid)) == NULL) logerr(0, "User %ld does not exist in password" " database", (long)ruid); if (strcmp(pwd->pw_name, utx->ut_name) != 0) logerr(0, "Current user `%s' does not match " "`%s' in utmpx entry", pwd->pw_name, utx->ut_name); } (void)snprintf(tty, sizeof(tty), "%s%s", _PATH_DEV, utx->ut_line); fd = open(tty, O_RDONLY|O_NONBLOCK, 0); if (fd != -1) { if (fstat(fd, &st) == -1) logerr(errno, "Cannot stat `%s'", tty); if (ruid != 0 && st.st_uid != ruid) logerr(0, "%s: Is not owned by you", tty); if (!isatty(fd)) logerr(0, "%s: Not a tty device", tty); (void)close(fd); if (access(tty, W_OK|R_OK) == -1) logerr(errno, "Can't access `%s'", tty); } else { struct utmpx utold, *utoldp; pid_t ppid; /* * A daemon like ftpd that does not use a tty line? * We only allow it to kill its own existing entries */ if (utx->ut_type != DEAD_PROCESS) logerr(errno, "Cannot open `%s'", tty); (void)memcpy(utold.ut_line, utx->ut_line, sizeof(utx->ut_line)); if ((utoldp = getutxline(&utold)) == NULL) logerr(0, "Cannot find existing entry for `%s'", utx->ut_line); if (utoldp->ut_pid != (ppid = getppid())) logerr(0, "Cannot modify entry for `%s' " "utmp pid %ld != parent %ld", tty, (long)utoldp->ut_pid, (long)ppid); } if (seteuid(euid) == 1) logerr(errno, "Can't setuid %ld", (long)euid); if (pututxline(utx) == NULL) logerr(errno, "Cannot update utmp entry"); return 0; }