/* Copyright 1988,1990,1993,1994 by Paul Vixie
* All rights reserved
*/
/*
* Copyright (c) 1997 by Internet Software Consortium
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
* ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
* CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
* DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
* PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
* ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
* SOFTWARE.
*/
#if !defined(lint) && !defined(LINT)
static const char rcsid[] =
"$Id: crontab.c,v 1.3 1998/08/14 00:32:38 vixie Exp $";
#endif
/* crontab - install and manage per-user crontab files
* vix 02may87 [RCS has the rest of the log]
* vix 26jan87 [original]
*/
#define MAIN_PROGRAM
#include "cron.h"
#include <md5.h>
#define MD5_SIZE 33
#define NHEADER_LINES 3
enum opt_t { opt_unknown, opt_list, opt_delete, opt_edit, opt_replace };
#if DEBUGGING
static char *Options[] = { "???", "list", "delete", "edit", "replace" };
#endif
static PID_T Pid;
static char User[MAXLOGNAME], RealUser[MAXLOGNAME];
static char Filename[MAX_FNAME];
static FILE *NewCrontab;
static int CheckErrorCount;
static enum opt_t Option;
static int fflag;
static struct passwd *pw;
static void list_cmd(void),
delete_cmd(void),
edit_cmd(void),
poke_daemon(void),
check_error(const char *),
parse_args(int c, char *v[]);
static int replace_cmd(void);
static void
usage(const char *msg)
{
fprintf(stderr, "crontab: usage error: %s\n", msg);
fprintf(stderr, "%s\n%s\n",
"usage: crontab [-u user] file",
" crontab [-u user] { -l | -r [-f] | -e }");
exit(ERROR_EXIT);
}
int
main(int argc, char *argv[])
{
int exitstatus;
Pid = getpid();
ProgramName = argv[0];
setlocale(LC_ALL, "");
#if defined(BSD)
setlinebuf(stderr);
#endif
parse_args(argc, argv); /* sets many globals, opens a file */
set_cron_uid();
set_cron_cwd();
if (!allowed(User)) {
warnx("you (%s) are not allowed to use this program", User);
log_it(RealUser, Pid, "AUTH", "crontab command not allowed");
exit(ERROR_EXIT);
}
exitstatus = OK_EXIT;
switch (Option) {
case opt_list:
list_cmd();
break;
case opt_delete:
delete_cmd();
break;
case opt_edit:
edit_cmd();
break;
case opt_replace:
if (replace_cmd() < 0)
exitstatus = ERROR_EXIT;
break;
case opt_unknown:
default:
abort();
}
exit(exitstatus);
/*NOTREACHED*/
}
static void
parse_args(int argc, char *argv[])
{
int argch;
char resolved_path[PATH_MAX];
if (!(pw = getpwuid(getuid())))
errx(ERROR_EXIT, "your UID isn't in the passwd file, bailing out");
bzero(pw->pw_passwd, strlen(pw->pw_passwd));
(void) strncpy(User, pw->pw_name, (sizeof User)-1);
User[(sizeof User)-1] = '\0';
strcpy(RealUser, User);
Filename[0] = '\0';
Option = opt_unknown;
while ((argch = getopt(argc, argv, "u:lerx:f")) != -1) {
switch (argch) {
case 'x':
if (!set_debug_flags(optarg))
usage("bad debug option");
break;
case 'u':
if (getuid() != ROOT_UID)
errx(ERROR_EXIT, "must be privileged to use -u");
if (!(pw = getpwnam(optarg)))
errx(ERROR_EXIT, "user `%s' unknown", optarg);
bzero(pw->pw_passwd, strlen(pw->pw_passwd));
(void) strncpy(User, pw->pw_name, (sizeof User)-1);
User[(sizeof User)-1] = '\0';
break;
case 'l':
if (Option != opt_unknown)
usage("only one operation permitted");
Option = opt_list;
break;
case 'r':
if (Option != opt_unknown)
usage("only one operation permitted");
Option = opt_delete;
break;
case 'e':
if (Option != opt_unknown)
usage("only one operation permitted");
Option = opt_edit;
break;
case 'f':
fflag = 1;
break;
default:
usage("unrecognized option");
}
}
endpwent();
if (Option != opt_unknown) {
if (argv[optind] != NULL) {
usage("no arguments permitted after this option");
}
} else {
if (argv[optind] != NULL) {
Option = opt_replace;
(void) strncpy (Filename, argv[optind], (sizeof Filename)-1);
Filename[(sizeof Filename)-1] = '\0';
} else {
usage("file name must be specified for replace");
}
}
if (Option == opt_replace) {
/* relinquish the setuid status of the binary during
* the open, lest nonroot users read files they should
* not be able to read. we can't use access() here
* since there's a race condition. thanks go out to
* Arnt Gulbrandsen <agulbra@pvv.unit.no> for spotting
* the race.
*/
if (swap_uids() < OK)
err(ERROR_EXIT, "swapping uids");
/* we have to open the file here because we're going to
* chdir(2) into /var/cron before we get around to
* reading the file.
*/
if (!strcmp(Filename, "-")) {
NewCrontab = stdin;
} else if (realpath(Filename, resolved_path) != NULL &&
!strcmp(resolved_path, SYSCRONTAB)) {
err(ERROR_EXIT, SYSCRONTAB " must be edited manually");
} else {
if (!(NewCrontab = fopen(Filename, "r")))
err(ERROR_EXIT, "%s", Filename);
}
if (swap_uids_back() < OK)
err(ERROR_EXIT, "swapping uids back");
}
Debug(DMISC, ("user=%s, file=%s, option=%s\n",
User, Filename, Options[(int)Option]))
}
static void
copy_file(FILE *in, FILE *out)
{
int x, ch;
Set_LineNum(1)
/* ignore the top few comments since we probably put them there.
*/
for (x = 0; x < NHEADER_LINES; x++) {
ch = get_char(in);
if (EOF == ch)
break;
if ('#' != ch) {
putc(ch, out);
break;
}
while (EOF != (ch = get_char(in)))
if (ch == '\n')
break;
if (EOF == ch)
break;
}
/* copy the rest of the crontab (if any) to the output file.
*/
if (EOF != ch)
while (EOF != (ch = get_char(in)))
putc(ch, out);
}
static void
list_cmd(void)
{
char n[MAX_FNAME];
FILE *f;
log_it(RealUser, Pid, "LIST", User);
(void) snprintf(n, sizeof(n), CRON_TAB(User));
if (!(f = fopen(n, "r"))) {
if (errno == ENOENT)
errx(ERROR_EXIT, "no crontab for %s", User);
else
err(ERROR_EXIT, "%s", n);
}
/* file is open. copy to stdout, close.
*/
copy_file(f, stdout);
fclose(f);
}
static void
delete_cmd(void)
{
char n[MAX_FNAME];
int ch, first;
if (!fflag && isatty(STDIN_FILENO)) {
(void)fprintf(stderr, "remove crontab for %s? ", User);
first = ch = getchar();
while (ch != '\n' && ch != EOF)
ch = getchar();
if (first != 'y' && first != 'Y')
return;
}
log_it(RealUser, Pid, "DELETE", User);
if (snprintf(n, sizeof(n), CRON_TAB(User)) >= (int)sizeof(n))
errx(ERROR_EXIT, "path too long");
if (unlink(n) != 0) {
if (errno == ENOENT)
errx(ERROR_EXIT, "no crontab for %s", User);
else
err(ERROR_EXIT, "%s", n);
}
poke_daemon();
}
static void
check_error(const char *msg)
{
CheckErrorCount++;
fprintf(stderr, "\"%s\":%d: %s\n", Filename, LineNumber-1, msg);
}
static void
edit_cmd(void)
{
char n[MAX_FNAME], q[MAX_TEMPSTR], *editor;
FILE *f;
int t;
struct stat statbuf, fsbuf;
WAIT_T waiter;
PID_T pid, xpid;
mode_t um;
int syntax_error = 0;
char orig_md5[MD5_SIZE];
char new_md5[MD5_SIZE];
log_it(RealUser, Pid, "BEGIN EDIT", User);
if (snprintf(n, sizeof(n), CRON_TAB(User)) >= (int)sizeof(n))
errx(ERROR_EXIT, "path too long");
if (!(f = fopen(n, "r"))) {
if (errno != ENOENT)
err(ERROR_EXIT, "%s", n);
warnx("no crontab for %s - using an empty one", User);
if (!(f = fopen(_PATH_DEVNULL, "r")))
err(ERROR_EXIT, _PATH_DEVNULL);
}
um = umask(077);
(void) snprintf(Filename, sizeof(Filename), "/tmp/crontab.XXXXXXXXXX");
if ((t = mkstemp(Filename)) == -1) {
warn("%s", Filename);
(void) umask(um);
goto fatal;
}
(void) umask(um);
#ifdef HAS_FCHOWN
if (fchown(t, getuid(), getgid()) < 0) {
#else
if (chown(Filename, getuid(), getgid()) < 0) {
#endif
warn("fchown");
goto fatal;
}
if (!(NewCrontab = fdopen(t, "r+"))) {
warn("fdopen");
goto fatal;
}
copy_file(f, NewCrontab);
fclose(f);
if (fflush(NewCrontab))
err(ERROR_EXIT, "%s", Filename);
if (fstat(t, &fsbuf) < 0) {
warn("unable to fstat temp file");
goto fatal;
}
again:
if (swap_uids() < OK)
err(ERROR_EXIT, "swapping uids");
if (stat(Filename, &statbuf) < 0) {
warn("stat");
fatal:
unlink(Filename);
exit(ERROR_EXIT);
}
if (swap_uids_back() < OK)
err(ERROR_EXIT, "swapping uids back");
if (statbuf.st_dev != fsbuf.st_dev || statbuf.st_ino != fsbuf.st_ino)
errx(ERROR_EXIT, "temp file must be edited in place");
if (MD5File(Filename, orig_md5) == NULL) {
warn("MD5");
goto fatal;
}
if ((editor = getenv("VISUAL")) == NULL &&
(editor = getenv("EDITOR")) == NULL) {
editor = EDITOR;
}
/* we still have the file open. editors will generally rewrite the
* original file rather than renaming/unlinking it and starting a
* new one; even backup files are supposed to be made by copying
* rather than by renaming. if some editor does not support this,
* then don't use it. the security problems are more severe if we
* close and reopen the file around the edit.
*/
switch (pid = fork()) {
case -1:
warn("fork");
goto fatal;
case 0:
/* child */
if (setuid(getuid()) < 0)
err(ERROR_EXIT, "setuid(getuid())");
if (chdir("/tmp") < 0)
err(ERROR_EXIT, "chdir(/tmp)");
if (strlen(editor) + strlen(Filename) + 2 >= MAX_TEMPSTR)
errx(ERROR_EXIT, "editor or filename too long");
execlp(editor, editor, Filename, (char *)NULL);
err(ERROR_EXIT, "%s", editor);
/*NOTREACHED*/
default:
/* parent */
break;
}
/* parent */
{
void (*sig[3])(int signal);
sig[0] = signal(SIGHUP, SIG_IGN);
sig[1] = signal(SIGINT, SIG_IGN);
sig[2] = signal(SIGTERM, SIG_IGN);
xpid = wait(&waiter);
signal(SIGHUP, sig[0]);
signal(SIGINT, sig[1]);
signal(SIGTERM, sig[2]);
}
if (xpid != pid) {
warnx("wrong PID (%d != %d) from \"%s\"", xpid, pid, editor);
goto fatal;
}
if (WIFEXITED(waiter) && WEXITSTATUS(waiter)) {
warnx("\"%s\" exited with status %d", editor, WEXITSTATUS(waiter));
goto fatal;
}
if (WIFSIGNALED(waiter)) {
warnx("\"%s\" killed; signal %d (%score dumped)",
editor, WTERMSIG(waiter), WCOREDUMP(waiter) ?"" :"no ");
goto fatal;
}
if (swap_uids() < OK)
err(ERROR_EXIT, "swapping uids");
if (stat(Filename, &statbuf) < 0) {
warn("stat");
goto fatal;
}
if (statbuf.st_dev != fsbuf.st_dev || statbuf.st_ino != fsbuf.st_ino)
errx(ERROR_EXIT, "temp file must be edited in place");
if (MD5File(Filename, new_md5) == NULL) {
warn("MD5");
goto fatal;
}
if (swap_uids_back() < OK)
err(ERROR_EXIT, "swapping uids back");
if (strcmp(orig_md5, new_md5) == 0 && !syntax_error) {
warnx("no changes made to crontab");
goto remove;
}
warnx("installing new crontab");
switch (replace_cmd()) {
case 0: /* Success */
break;
case -1: /* Syntax error */
for (;;) {
printf("Do you want to retry the same edit? ");
fflush(stdout);
q[0] = '\0';
(void) fgets(q, sizeof q, stdin);
switch (islower(q[0]) ? q[0] : tolower(q[0])) {
case 'y':
syntax_error = 1;
goto again;
case 'n':
goto abandon;
default:
fprintf(stderr, "Enter Y or N\n");
}
}
/*NOTREACHED*/
case -2: /* Install error */
abandon:
warnx("edits left in %s", Filename);
goto done;
default:
warnx("panic: bad switch() in replace_cmd()");
goto fatal;
}
remove:
unlink(Filename);
done:
log_it(RealUser, Pid, "END EDIT", User);
}
/* returns 0 on success
* -1 on syntax error
* -2 on install error
*/
static int
replace_cmd(void)
{
char n[MAX_FNAME], envstr[MAX_ENVSTR], tn[MAX_FNAME];
FILE *tmp;
int ch, eof;
entry *e;
time_t now = time(NULL);
char **envp = env_init();
if (envp == NULL) {
warnx("cannot allocate memory");
return (-2);
}
(void) snprintf(n, sizeof(n), "tmp.%d", Pid);
if (snprintf(tn, sizeof(tn), CRON_TAB(n)) >= (int)sizeof(tn)) {
warnx("path too long");
return (-2);
}
if (!(tmp = fopen(tn, "w+"))) {
warn("%s", tn);
return (-2);
}
/* write a signature at the top of the file.
*
* VERY IMPORTANT: make sure NHEADER_LINES agrees with this code.
*/
fprintf(tmp, "# DO NOT EDIT THIS FILE - edit the master and reinstall.\n");
fprintf(tmp, "# (%s installed on %-24.24s)\n", Filename, ctime(&now));
fprintf(tmp, "# (Cron version -- %s)\n", rcsid);
/* copy the crontab to the tmp
*/
rewind(NewCrontab);
Set_LineNum(1)
while (EOF != (ch = get_char(NewCrontab)))
putc(ch, tmp);
ftruncate(fileno(tmp), ftello(tmp));
fflush(tmp); rewind(tmp);
if (ferror(tmp)) {
warnx("error while writing new crontab to %s", tn);
fclose(tmp); unlink(tn);
return (-2);
}
/* check the syntax of the file being installed.
*/
/* BUG: was reporting errors after the EOF if there were any errors
* in the file proper -- kludged it by stopping after first error.
* vix 31mar87
*/
Set_LineNum(1 - NHEADER_LINES)
CheckErrorCount = 0; eof = FALSE;
while (!CheckErrorCount && !eof) {
switch (load_env(envstr, tmp)) {
case ERR:
eof = TRUE;
break;
case FALSE:
e = load_entry(tmp, check_error, pw, envp);
if (e)
free_entry(e);
break;
case TRUE:
break;
}
}
if (CheckErrorCount != 0) {
warnx("errors in crontab file, can't install");
fclose(tmp); unlink(tn);
return (-1);
}
#ifdef HAS_FCHOWN
if (fchown(fileno(tmp), ROOT_UID, -1) < OK)
#else
if (chown(tn, ROOT_UID, -1) < OK)
#endif
{
warn("chown");
fclose(tmp); unlink(tn);
return (-2);
}
#ifdef HAS_FCHMOD
if (fchmod(fileno(tmp), 0600) < OK)
#else
if (chmod(tn, 0600) < OK)
#endif
{
warn("chown");
fclose(tmp); unlink(tn);
return (-2);
}
if (fclose(tmp) == EOF) {
warn("fclose");
unlink(tn);
return (-2);
}
if (snprintf(n, sizeof(n), CRON_TAB(User)) >= (int)sizeof(n)) {
warnx("path too long");
unlink(tn);
return (-2);
}
if (rename(tn, n)) {
warn("error renaming %s to %s", tn, n);
unlink(tn);
return (-2);
}
log_it(RealUser, Pid, "REPLACE", User);
/*
* Creating the 'tn' temp file has already updated the
* modification time of the spool directory. Sleep for a
* second to ensure that poke_daemon() sets a later
* modification time. Otherwise, this can race with the cron
* daemon scanning for updated crontabs.
*/
sleep(1);
poke_daemon();
return (0);
}
static void
poke_daemon(void)
{
if (utime(SPOOL_DIR, NULL) < OK) {
warn("can't update mtime on spooldir %s", SPOOL_DIR);
return;
}
}
plain