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/* $OpenBSD: database.c,v 1.36 2017/10/25 17:08:58 jca Exp $ */
/* Copyright 1988,1990,1993,1994 by Paul Vixie
* 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.
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <bitstring.h> /* for structs.h */
#include <dirent.h>
#include <fcntl.h>
#include <limits.h>
#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <time.h> /* for structs.h */
#include <unistd.h>
#include "pathnames.h"
#include "globals.h"
#include "macros.h"
#include "structs.h"
#include "funcs.h"
#define HASH(a,b) ((a)+(b))
static void process_crontab(int, const char *, const char *,
struct stat *, cron_db *, cron_db *);
void
load_database(cron_db **db)
{
struct stat statbuf, syscron_stat;
cron_db *new_db, *old_db = *db;
struct timespec mtime;
struct dirent *dp;
DIR *dir;
user *u;
/* before we start loading any data, do a stat on _PATH_CRON_SPOOL
* so that if anything changes as of this moment (i.e., before we've
* cached any of the database), we'll see the changes next time.
*/
if (stat(_PATH_CRON_SPOOL, &statbuf) < 0) {
syslog(LOG_ERR, "(CRON) STAT FAILED (%s)", _PATH_CRON_SPOOL);
return;
}
/* track system crontab file
*/
if (stat(_PATH_SYS_CRONTAB, &syscron_stat) < 0)
timespecclear(&syscron_stat.st_mtim);
/* hash mtime of system crontab file and crontab dir
*/
mtime.tv_sec =
HASH(statbuf.st_mtim.tv_sec, syscron_stat.st_mtim.tv_sec);
mtime.tv_nsec =
HASH(statbuf.st_mtim.tv_nsec, syscron_stat.st_mtim.tv_nsec);
/* if spooldir's mtime has not changed, we don't need to fiddle with
* the database.
*/
if (old_db != NULL && timespeccmp(&mtime, &old_db->mtime, ==))
return;
/* something's different. make a new database, moving unchanged
* elements from the old database, reloading elements that have
* actually changed. Whatever is left in the old database when
* we're done is chaff -- crontabs that disappeared.
*/
if ((new_db = malloc(sizeof(*new_db))) == NULL)
return;
new_db->mtime = mtime;
TAILQ_INIT(&new_db->users);
if (timespecisset(&syscron_stat.st_mtim)) {
process_crontab(AT_FDCWD, "*system*", _PATH_SYS_CRONTAB,
&syscron_stat, new_db, old_db);
}
/* we used to keep this dir open all the time, for the sake of
* efficiency. however, we need to close it in every fork, and
* we fork a lot more often than the mtime of the dir changes.
*/
if (!(dir = opendir(_PATH_CRON_SPOOL))) {
syslog(LOG_ERR, "(CRON) OPENDIR FAILED (%s)", _PATH_CRON_SPOOL);
/* Restore system crontab entry as needed. */
if (!TAILQ_EMPTY(&new_db->users) &&
(u = TAILQ_FIRST(&old_db->users))) {
if (strcmp(u->name, "*system*") == 0) {
TAILQ_REMOVE(&old_db->users, u, entries);
free_user(u);
TAILQ_INSERT_HEAD(&old_db->users,
TAILQ_FIRST(&new_db->users), entries);
}
}
free(new_db);
return;
}
while (NULL != (dp = readdir(dir))) {
/* avoid file names beginning with ".". this is good
* because we would otherwise waste two guaranteed calls
* to getpwnam() for . and .., and also because user names
* starting with a period are just too nasty to consider.
*/
if (dp->d_name[0] == '.')
continue;
process_crontab(dirfd(dir), dp->d_name, dp->d_name,
&statbuf, new_db, old_db);
}
closedir(dir);
/* if we don't do this, then when our children eventually call
* getpwnam() in do_command.c's child_process to verify MAILTO=,
* they will screw us up (and v-v).
*/
endpwent();
/* whatever's left in the old database is now junk.
*/
if (old_db != NULL) {
while ((u = TAILQ_FIRST(&old_db->users))) {
TAILQ_REMOVE(&old_db->users, u, entries);
free_user(u);
}
free(old_db);
}
/* overwrite the database control block with the new one.
*/
*db = new_db;
}
user *
find_user(cron_db *db, const char *name)
{
user *u = NULL;
if (db != NULL) {
TAILQ_FOREACH(u, &db->users, entries) {
if (strcmp(u->name, name) == 0)
break;
}
}
return (u);
}
static void
process_crontab(int dfd, const char *uname, const char *fname,
struct stat *statbuf, cron_db *new_db, cron_db *old_db)
{
struct passwd *pw = NULL;
int crontab_fd = -1;
user *u, *new_u;
mode_t tabmask, tabperm;
/* Note: pw must remain NULL for system crontab (see below). */
if (fname[0] != '/' && (pw = getpwnam(uname)) == NULL) {
/* file doesn't have a user in passwd file.
*/
syslog(LOG_WARNING, "(%s) ORPHAN (no passwd entry)", uname);
goto next_crontab;
}
crontab_fd = openat(dfd, fname,
O_RDONLY|O_NONBLOCK|O_NOFOLLOW|O_CLOEXEC);
if (crontab_fd < 0) {
/* crontab not accessible?
*/
syslog(LOG_ERR, "(%s) CAN'T OPEN (%s)", uname, fname);
goto next_crontab;
}
if (fstat(crontab_fd, statbuf) < 0) {
syslog(LOG_ERR, "(%s) FSTAT FAILED (%s)", uname, fname);
goto next_crontab;
}
if (!S_ISREG(statbuf->st_mode)) {
syslog(LOG_WARNING, "(%s) NOT REGULAR (%s)", uname, fname);
goto next_crontab;
}
/* Looser permissions on system crontab. */
tabmask = pw ? ALLPERMS : (ALLPERMS & ~(S_IWUSR|S_IRGRP|S_IROTH));
tabperm = pw ? (S_IRUSR|S_IWUSR) : S_IRUSR;
if ((statbuf->st_mode & tabmask) != tabperm) {
syslog(LOG_WARNING, "(%s) BAD FILE MODE (%s)", uname, fname);
goto next_crontab;
}
if (statbuf->st_uid != 0 && (pw == NULL ||
statbuf->st_uid != pw->pw_uid || strcmp(uname, pw->pw_name) != 0)) {
syslog(LOG_WARNING, "(%s) WRONG FILE OWNER (%s)", uname, fname);
goto next_crontab;
}
if (pw != NULL && statbuf->st_gid != cron_gid) {
syslog(LOG_WARNING, "(%s) WRONG FILE GROUP (%s)", uname, fname);
goto next_crontab;
}
if (pw != NULL && statbuf->st_nlink != 1) {
syslog(LOG_WARNING, "(%s) BAD LINK COUNT (%s)", uname, fname);
goto next_crontab;
}
u = find_user(old_db, fname);
if (u != NULL) {
/* if crontab has not changed since we last read it
* in, then we can just use our existing entry.
*/
if (timespeccmp(&u->mtime, &statbuf->st_mtim, ==)) {
TAILQ_REMOVE(&old_db->users, u, entries);
TAILQ_INSERT_TAIL(&new_db->users, u, entries);
goto next_crontab;
}
syslog(LOG_INFO, "(%s) RELOAD (%s)", uname, fname);
}
new_u = load_user(crontab_fd, pw, fname);
if (new_u != NULL) {
/* Insert user into the new database and remove from old. */
new_u->mtime = statbuf->st_mtim;
TAILQ_INSERT_TAIL(&new_db->users, new_u, entries);
if (u != NULL) {
TAILQ_REMOVE(&old_db->users, u, entries);
free_user(u);
}
} else if (u != NULL) {
/* New user crontab failed to load, preserve the old one. */
TAILQ_REMOVE(&old_db->users, u, entries);
TAILQ_INSERT_TAIL(&new_db->users, u, entries);
}
next_crontab:
if (crontab_fd >= 0) {
close(crontab_fd);
}
}
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