diff options
Diffstat (limited to 'usr.bin/write/term_chk.c')
| -rw-r--r-- | usr.bin/write/term_chk.c | 137 |
1 files changed, 137 insertions, 0 deletions
diff --git a/usr.bin/write/term_chk.c b/usr.bin/write/term_chk.c new file mode 100644 index 0000000..d7d2cbe --- /dev/null +++ b/usr.bin/write/term_chk.c @@ -0,0 +1,137 @@ +/* $NetBSD: term_chk.c,v 1.8 2009/04/14 07:59:17 lukem Exp $ */ + +/* + * Copyright (c) 1989, 1993 + * The Regents of the University of California. All rights reserved. + * + * This code is derived from software contributed to Berkeley by + * Jef Poskanzer and Craig Leres of the Lawrence Berkeley Laboratory. + * + * 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. + * 3. Neither the name of the University nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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 <sys/cdefs.h> +#ifndef lint +__RCSID("$NetBSD: term_chk.c,v 1.8 2009/04/14 07:59:17 lukem Exp $"); +#endif + +#include <sys/types.h> +#include <sys/param.h> +#include <sys/stat.h> +#include <time.h> +#include <stdio.h> +#include <errno.h> +#include <unistd.h> +#include <paths.h> +#include <fcntl.h> +#include <string.h> +#include <err.h> + +#include "term_chk.h" + +/* + * term_chk - check that a terminal exists, and get the message bit + * and the access time + */ +int +term_chk(uid_t uid, const char *tty, int *msgsokP, time_t *atimeP, int ismytty, + gid_t saved_egid) +{ + char path[MAXPATHLEN]; + struct stat s; + int i, fd, serrno; + + if (strstr(tty, "../") != NULL) { + errno = EINVAL; + return -1; + } + i = snprintf(path, sizeof path, _PATH_DEV "%s", tty); + if (i < 0 || i >= (int)sizeof(path)) { + errno = ENOMEM; + return -1; + } + + (void)setegid(saved_egid); + fd = open(path, O_WRONLY, 0); + serrno = errno; + (void)setegid(getgid()); + errno = serrno; + + if (fd == -1) + return(-1); + if (fstat(fd, &s) == -1) + goto error; + if (!isatty(fd)) + goto error; + if (s.st_uid != uid && uid != 0) { + errno = EPERM; + goto error; + } + if (msgsokP) + *msgsokP = (s.st_mode & S_IWGRP) != 0; /* group write bit */ + if (atimeP) + *atimeP = s.st_atime; + if (ismytty) + (void)close(fd); + return ismytty ? 0 : fd; +error: + if (fd != -1) { + serrno = errno; + (void)close(fd); + errno = serrno; + } + return -1; +} + +char * +check_sender(time_t *atime, uid_t myuid, gid_t saved_egid) +{ + int myttyfd; + int msgsok; + char *mytty; + + /* check that sender has write enabled */ + if (isatty(fileno(stdin))) + myttyfd = fileno(stdin); + else if (isatty(fileno(stdout))) + myttyfd = fileno(stdout); + else if (isatty(fileno(stderr))) + myttyfd = fileno(stderr); + else if (atime == NULL) + return NULL; + else + errx(1, "Cannot find your tty"); + if ((mytty = ttyname(myttyfd)) == NULL) + err(1, "Cannot find the name of your tty"); + if (strncmp(mytty, _PATH_DEV, sizeof(_PATH_DEV) - 1) == 0) + mytty += sizeof(_PATH_DEV) - 1; + if (term_chk(myuid, mytty, &msgsok, atime, 1, saved_egid) == -1) + err(1, "%s%s", _PATH_DEV, mytty); + if (!msgsok) { + warnx( + "You have write permission turned off; no reply possible"); + } + return mytty; +} |