OpenBSD-4.6/usr.sbin/cron/crontab.c
/* $OpenBSD: crontab.c,v 1.57 2009/01/29 22:50:16 sobrado Exp $ */
/* Copyright 1988,1990,1993,1994 by Paul Vixie
* All rights reserved
*/
/*
* Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
* Copyright (c) 1997,2000 by Internet Software Consortium, Inc.
*
* 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 ISC DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC 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.
*/
static char const rcsid[] = "$OpenBSD: crontab.c,v 1.57 2009/01/29 22:50:16 sobrado Exp $";
/* crontab - install and manage per-user crontab files
* vix 02may87 [RCS has the rest of the log]
* vix 26jan87 [original]
*/
#include <err.h>
#define MAIN_PROGRAM
#include "cron.h"
#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" };
static char *getoptargs = "u:lerx:";
#else
static char *getoptargs = "u:ler";
#endif
static PID_T Pid;
static char User[MAX_UNAME], RealUser[MAX_UNAME];
static char Filename[MAX_FNAME], TempFilename[MAX_FNAME];
static FILE *NewCrontab;
static int CheckErrorCount;
static enum opt_t Option;
static struct passwd *pw;
int editit(const char *);
static void list_cmd(void),
delete_cmd(void),
edit_cmd(void),
check_error(const char *),
parse_args(int c, char *v[]),
die(int);
static int replace_cmd(void);
static int ignore_comments(FILE *);
static void
usage(const char *msg) {
fprintf(stderr, "%s: usage error: %s\n", ProgramName, msg);
fprintf(stderr, "usage: %s [-u user] file\n", ProgramName);
fprintf(stderr, " %s [-e | -l | -r] [-u user]\n", ProgramName);
fprintf(stderr,
"\t\t(default operation is replace, per 1003.2)\n"
"\t-e\t(edit user's crontab)\n"
"\t-l\t(list user's crontab)\n"
"\t-r\t(delete user's crontab)\n");
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_cwd();
if (!allowed(RealUser, CRON_ALLOW, CRON_DENY)) {
fprintf(stderr,
"You (%s) are not allowed to use this program (%s)\n",
User, ProgramName);
fprintf(stderr, "See crontab(1) for more information\n");
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;
default:
exitstatus = ERROR_EXIT;
break;
}
exit(exitstatus);
/*NOTREACHED*/
}
static void
parse_args(int argc, char *argv[]) {
int argch;
if (!(pw = getpwuid(getuid()))) {
fprintf(stderr, "%s: your UID isn't in the passwd file.\n",
ProgramName);
fprintf(stderr, "bailing out.\n");
exit(ERROR_EXIT);
}
if (strlen(pw->pw_name) >= sizeof User) {
fprintf(stderr, "username too long\n");
exit(ERROR_EXIT);
}
strlcpy(User, pw->pw_name, sizeof(User));
strlcpy(RealUser, User, sizeof(RealUser));
Filename[0] = '\0';
Option = opt_unknown;
while (-1 != (argch = getopt(argc, argv, getoptargs))) {
switch (argch) {
#if DEBUGGING
case 'x':
if (!set_debug_flags(optarg))
usage("bad debug option");
break;
#endif
case 'u':
if (MY_UID(pw) != ROOT_UID) {
fprintf(stderr,
"must be privileged to use -u\n");
exit(ERROR_EXIT);
}
if (!(pw = getpwnam(optarg))) {
fprintf(stderr, "%s: user `%s' unknown\n",
ProgramName, optarg);
exit(ERROR_EXIT);
}
if (strlcpy(User, optarg, sizeof User) >= sizeof User)
usage("username too long");
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;
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;
if (strlcpy(Filename, argv[optind], sizeof Filename)
>= sizeof Filename)
usage("filename too long");
} else
usage("file name must be specified for replace");
}
if (Option == opt_replace) {
/* 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 {
/* relinquish the setgid 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_gids() < OK) {
perror("swapping gids");
exit(ERROR_EXIT);
}
if (!(NewCrontab = fopen(Filename, "r"))) {
perror(Filename);
exit(ERROR_EXIT);
}
if (swap_gids_back() < OK) {
perror("swapping gids back");
exit(ERROR_EXIT);
}
}
}
Debug(DMISC, ("user=%s, file=%s, option=%s\n",
User, Filename, Options[(int)Option]))
}
static void
list_cmd(void) {
char n[MAX_FNAME];
FILE *f;
int ch;
log_it(RealUser, Pid, "LIST", User);
if (snprintf(n, sizeof n, "%s/%s", SPOOL_DIR, User) >= sizeof(n)) {
fprintf(stderr, "path too long\n");
exit(ERROR_EXIT);
}
if (!(f = fopen(n, "r"))) {
if (errno == ENOENT)
fprintf(stderr, "no crontab for %s\n", User);
else
perror(n);
exit(ERROR_EXIT);
}
/* file is open. copy to stdout, close.
*/
Set_LineNum(1)
/* ignore the top few comments since we probably put them there.
*/
ch = ignore_comments(f);
while (EOF != (ch = get_char(f)))
putchar(ch);
fclose(f);
}
static void
delete_cmd(void) {
char n[MAX_FNAME];
log_it(RealUser, Pid, "DELETE", User);
if (snprintf(n, sizeof n, "%s/%s", SPOOL_DIR, User) >= sizeof(n)) {
fprintf(stderr, "path too long\n");
exit(ERROR_EXIT);
}
if (unlink(n) != 0) {
if (errno == ENOENT)
fprintf(stderr, "no crontab for %s\n", User);
else
perror(n);
exit(ERROR_EXIT);
}
poke_daemon(SPOOL_DIR, RELOAD_CRON);
}
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];
FILE *f;
int ch, t;
struct stat statbuf, xstatbuf;
struct timespec mtimespec;
struct timeval tv[2];
log_it(RealUser, Pid, "BEGIN EDIT", User);
if (snprintf(n, sizeof n, "%s/%s", SPOOL_DIR, User) >= sizeof(n)) {
fprintf(stderr, "path too long\n");
exit(ERROR_EXIT);
}
if (!(f = fopen(n, "r"))) {
if (errno != ENOENT) {
perror(n);
exit(ERROR_EXIT);
}
fprintf(stderr, "no crontab for %s - using an empty one\n",
User);
if (!(f = fopen(_PATH_DEVNULL, "r"))) {
perror(_PATH_DEVNULL);
exit(ERROR_EXIT);
}
}
if (fstat(fileno(f), &statbuf) < 0) {
perror("fstat");
goto fatal;
}
/*
* Note that timespec has higher precision than timeval so we
* store mtimespec using timeval precision so we can compare later.
*/
TIMESPEC_TO_TIMEVAL(&tv[0], &statbuf.st_atimespec);
TIMESPEC_TO_TIMEVAL(&tv[1], &statbuf.st_mtimespec);
TIMEVAL_TO_TIMESPEC(&tv[1], &mtimespec);
/* Turn off signals. */
(void)signal(SIGHUP, SIG_IGN);
(void)signal(SIGINT, SIG_IGN);
(void)signal(SIGQUIT, SIG_IGN);
if (snprintf(Filename, sizeof Filename, "%scrontab.XXXXXXXXXX",
_PATH_TMP) >= sizeof(Filename)) {
fprintf(stderr, "path too long\n");
goto fatal;
}
if (-1 == (t = mkstemp(Filename))) {
perror(Filename);
goto fatal;
}
if (!(NewCrontab = fdopen(t, "r+"))) {
perror("fdopen");
goto fatal;
}
Set_LineNum(1)
/* ignore the top few comments since we probably put them there.
*/
ch = ignore_comments(f);
/* copy the rest of the crontab (if any) to the temp file.
*/
if (EOF != ch)
while (EOF != (ch = get_char(f)))
putc(ch, NewCrontab);
fclose(f);
if (fflush(NewCrontab) < OK) {
perror(Filename);
exit(ERROR_EXIT);
}
(void)futimes(t, tv);
again:
rewind(NewCrontab);
if (ferror(NewCrontab)) {
fprintf(stderr, "%s: error while writing new crontab to %s\n",
ProgramName, Filename);
fatal:
unlink(Filename);
exit(ERROR_EXIT);
}
/* 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.
*/
if (editit(Filename) == -1) {
warn("error starting editor");
goto fatal;
}
if (fstat(t, &statbuf) < 0) {
perror("fstat");
goto fatal;
}
if (timespeccmp(&mtimespec, &statbuf.st_mtimespec, -) == 0) {
if (lstat(Filename, &xstatbuf) == 0 &&
statbuf.st_ino != xstatbuf.st_ino) {
fprintf(stderr, "%s: crontab temp file moved, editor "
"may create backup files improperly\n", ProgramName);
}
fprintf(stderr, "%s: no changes made to crontab\n",
ProgramName);
goto remove;
}
fprintf(stderr, "%s: installing new crontab\n", ProgramName);
switch (replace_cmd()) {
case 0:
break;
case -1:
for (;;) {
printf("Do you want to retry the same edit? ");
fflush(stdout);
q[0] = '\0';
if (fgets(q, sizeof q, stdin) == NULL) {
putchar('\n');
goto abandon;
}
switch (q[0]) {
case 'y':
case 'Y':
goto again;
case 'n':
case 'N':
goto abandon;
default:
fprintf(stderr, "Enter Y or N\n");
}
}
/*NOTREACHED*/
case -2:
abandon:
fprintf(stderr, "%s: edits left in %s\n",
ProgramName, Filename);
goto done;
default:
fprintf(stderr, "%s: panic: bad switch() in replace_cmd()\n",
ProgramName);
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];
FILE *tmp;
int ch, eof, fd;
int error = 0;
entry *e;
time_t now = time(NULL);
char **envp = env_init();
if (envp == NULL) {
fprintf(stderr, "%s: Cannot allocate memory.\n", ProgramName);
return (-2);
}
if (snprintf(TempFilename, sizeof TempFilename, "%s/tmp.XXXXXXXXX",
SPOOL_DIR) >= sizeof(TempFilename)) {
TempFilename[0] = '\0';
fprintf(stderr, "path too long\n");
return (-2);
}
if ((fd = mkstemp(TempFilename)) == -1 || !(tmp = fdopen(fd, "w+"))) {
perror(TempFilename);
if (fd != -1) {
close(fd);
unlink(TempFilename);
}
TempFilename[0] = '\0';
return (-2);
}
(void) signal(SIGHUP, die);
(void) signal(SIGINT, die);
(void) signal(SIGQUIT, die);
/* 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 -- %s)\n", CRON_VERSION, 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)); /* XXX redundant with "w+"? */
fflush(tmp); rewind(tmp);
if (ferror(tmp)) {
fprintf(stderr, "%s: error while writing new crontab to %s\n",
ProgramName, TempFilename);
fclose(tmp);
error = -2;
goto done;
}
/* 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:
/* check for data before the EOF */
if (envstr[0] != '\0') {
Set_LineNum(LineNumber + 1);
check_error("premature EOF");
}
eof = TRUE;
break;
case FALSE:
e = load_entry(tmp, check_error, pw, envp);
if (e)
free(e);
break;
case TRUE:
break;
}
}
if (CheckErrorCount != 0) {
fprintf(stderr, "errors in crontab file, can't install.\n");
fclose(tmp);
error = -1;
goto done;
}
#ifdef HAVE_FCHOWN
if (fchown(fileno(tmp), pw->pw_uid, -1) < OK) {
perror("fchown");
fclose(tmp);
error = -2;
goto done;
}
#else
if (chown(TempFilename, pw->pw_uid, -1) < OK) {
perror("chown");
fclose(tmp);
error = -2;
goto done;
}
#endif
if (fclose(tmp) == EOF) {
perror("fclose");
error = -2;
goto done;
}
if (snprintf(n, sizeof n, "%s/%s", SPOOL_DIR, User) >= sizeof(n)) {
fprintf(stderr, "path too long\n");
error = -2;
goto done;
}
if (rename(TempFilename, n)) {
fprintf(stderr, "%s: error renaming %s to %s\n",
ProgramName, TempFilename, n);
perror("rename");
error = -2;
goto done;
}
TempFilename[0] = '\0';
log_it(RealUser, Pid, "REPLACE", User);
poke_daemon(SPOOL_DIR, RELOAD_CRON);
done:
(void) signal(SIGHUP, SIG_DFL);
(void) signal(SIGINT, SIG_DFL);
(void) signal(SIGQUIT, SIG_DFL);
if (TempFilename[0]) {
(void) unlink(TempFilename);
TempFilename[0] = '\0';
}
return (error);
}
/*
* Execute an editor on the specified pathname, which is interpreted
* from the shell. This means flags may be included.
*
* Returns -1 on error, or the exit value on success.
*/
int
editit(const char *pathname)
{
char *argp[] = {"sh", "-c", NULL, NULL}, *ed, *p;
sig_t sighup, sigint, sigquit, sigchld;
pid_t pid;
int saved_errno, st, ret = -1;
ed = getenv("VISUAL");
if (ed == NULL || ed[0] == '\0')
ed = getenv("EDITOR");
if (ed == NULL || ed[0] == '\0')
ed = _PATH_VI;
if (asprintf(&p, "%s %s", ed, pathname) == -1)
return (-1);
argp[2] = p;
sighup = signal(SIGHUP, SIG_IGN);
sigint = signal(SIGINT, SIG_IGN);
sigquit = signal(SIGQUIT, SIG_IGN);
sigchld = signal(SIGCHLD, SIG_DFL);
if ((pid = fork()) == -1)
goto fail;
if (pid == 0) {
setgid(getgid());
setuid(getuid());
execv(_PATH_BSHELL, argp);
_exit(127);
}
while (waitpid(pid, &st, 0) == -1)
if (errno != EINTR)
goto fail;
if (!WIFEXITED(st))
errno = EINTR;
else
ret = WEXITSTATUS(st);
fail:
saved_errno = errno;
(void)signal(SIGHUP, sighup);
(void)signal(SIGINT, sigint);
(void)signal(SIGQUIT, sigquit);
(void)signal(SIGCHLD, sigchld);
free(p);
errno = saved_errno;
return (ret);
}
static void
die(int x) {
if (TempFilename[0])
(void) unlink(TempFilename);
_exit(ERROR_EXIT);
}
static int
ignore_comments(FILE *f) {
int ch, x;
x = 0;
while (EOF != (ch = get_char(f))) {
if ('#' != ch) {
putc(ch, NewCrontab);
break;
}
while (EOF != (ch = get_char(f)))
if (ch == '\n')
break;
if (++x >= NHEADER_LINES)
break;
}
return ch;
}