140 lines
4.0 KiB
C
140 lines
4.0 KiB
C
/* $NetBSD: utmp_update.c,v 1.9 2009/04/13 03:38:15 christos Exp $ */
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/*-
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* Copyright (c) 2002 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by Christos Zoulas.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__RCSID("$NetBSD: utmp_update.c,v 1.9 2009/04/13 03:38:15 christos Exp $");
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#include <sys/types.h>
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#include <sys/param.h>
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#include <sys/stat.h>
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#include <stdio.h>
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#include <vis.h>
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#include <err.h>
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#include <fcntl.h>
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#include <pwd.h>
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#include <utmpx.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <paths.h>
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int main(int, char *[]);
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int
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main(int argc, char *argv[])
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{
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struct utmpx *utx;
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size_t len;
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struct passwd *pwd;
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struct stat st;
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int fd;
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int res;
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uid_t euid, ruid;
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char tty[MAXPATHLEN];
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euid = geteuid();
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ruid = getuid();
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if (seteuid(ruid) == -1)
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err(1, "seteuid");
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if (argc != 2) {
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(void)fprintf(stderr, "Usage: %s <vis-utmpx-entry>\n",
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getprogname());
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exit(1);
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}
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len = strlen(argv[1]);
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if (len > sizeof(*utx) * 4 + 1 || len < sizeof(*utx))
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errx(1, "Bad argument");
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if ((utx = malloc(len)) == NULL)
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err(1, NULL);
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res = strunvis((char *)utx, argv[1]);
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if (res != (int)sizeof(*utx))
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errx(1, "Decoding error %s %d != %zu", argv[1], res, sizeof(*utx));
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switch (utx->ut_type) {
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case USER_PROCESS:
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case DEAD_PROCESS:
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break;
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default:
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errx(1, "Invalid utmpx type %d", (int)utx->ut_type);
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}
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if (ruid != 0) {
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if ((pwd = getpwuid(ruid)) == NULL)
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errx(1, "User %lu does not exist in password database",
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(long)ruid);
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if (strcmp(pwd->pw_name, utx->ut_name) != 0)
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errx(1, "Current user `%s' does not match "
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"`%s' in utmpx entry", pwd->pw_name, utx->ut_name);
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}
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(void)snprintf(tty, sizeof(tty), "%s%s", _PATH_DEV, utx->ut_line);
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fd = open(tty, O_RDONLY|O_NONBLOCK, 0);
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if (fd != -1) {
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if (fstat(fd, &st) == -1)
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err(1, "Cannot stat `%s'", tty);
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if (ruid != 0 && st.st_uid != ruid)
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errx(1, "%s: Is not owned by you", tty);
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if (!isatty(fd))
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errx(1, "%s: Not a tty device", tty);
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(void)close(fd);
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if (access(tty, W_OK|R_OK) == -1)
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err(1, "%s", tty);
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} else {
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struct utmpx utold, *utoldp;
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/*
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* A daemon like ftpd that does not use a tty line?
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* We only allow it to kill its own existing entries
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*/
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if (utx->ut_type != DEAD_PROCESS)
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err(1, "Cannot open `%s'", tty);
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(void)memcpy(utold.ut_line, utx->ut_line, sizeof(utx->ut_line));
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if ((utoldp = getutxline(&utold)) == NULL)
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err(1, "Cannot find existing entry for `%s'",
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utx->ut_line);
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if (utoldp->ut_pid != getppid())
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err(1, "Cannot modify entry for `%s'", tty);
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}
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(void)seteuid(euid);
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if (pututxline(utx) == NULL)
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err(1, "Cannot update utmp entry");
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return 0;
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}
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