OpenBSD-4.6/usr.sbin/cron/do_command.c
/* $OpenBSD: do_command.c,v 1.32 2007/05/25 17:50:41 millert 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.
*/
#if !defined(lint) && !defined(LINT)
static char const rcsid[] = "$OpenBSD: do_command.c,v 1.32 2007/05/25 17:50:41 millert Exp $";
#endif
#include "cron.h"
static void child_process(entry *, user *);
void
do_command(entry *e, user *u) {
Debug(DPROC, ("[%ld] do_command(%s, (%s,%lu,%lu))\n",
(long)getpid(), e->cmd, u->name,
(u_long)e->pwd->pw_uid, (u_long)e->pwd->pw_gid))
/* fork to become asynchronous -- parent process is done immediately,
* and continues to run the normal cron code, which means return to
* tick(). the child and grandchild don't leave this function, alive.
*
* vfork() is unsuitable, since we have much to do, and the parent
* needs to be able to run off and fork other processes.
*/
switch (fork()) {
case -1:
log_it("CRON", getpid(), "error", "can't fork");
break;
case 0:
/* child process */
acquire_daemonlock(1);
child_process(e, u);
Debug(DPROC, ("[%ld] child process done, exiting\n",
(long)getpid()))
_exit(OK_EXIT);
break;
default:
/* parent process */
break;
}
Debug(DPROC, ("[%ld] main process returning to work\n",(long)getpid()))
}
static void
child_process(entry *e, user *u) {
FILE *in;
int stdin_pipe[2], stdout_pipe[2];
char *input_data, *usernm;
int children = 0;
Debug(DPROC, ("[%ld] child_process('%s')\n", (long)getpid(), e->cmd))
/* mark ourselves as different to PS command watchers */
setproctitle("running job");
/* discover some useful and important environment settings
*/
usernm = e->pwd->pw_name;
/* our parent is watching for our death by catching SIGCHLD. we
* do not care to watch for our children's deaths this way -- we
* use wait() explicitly. so we have to reset the signal (which
* was inherited from the parent).
*/
(void) signal(SIGCHLD, SIG_DFL);
/* create some pipes to talk to our future child
*/
pipe(stdin_pipe); /* child's stdin */
pipe(stdout_pipe); /* child's stdout */
/* since we are a forked process, we can diddle the command string
* we were passed -- nobody else is going to use it again, right?
*
* if a % is present in the command, previous characters are the
* command, and subsequent characters are the additional input to
* the command. An escaped % will have the escape character stripped
* from it. Subsequent %'s will be transformed into newlines,
* but that happens later.
*/
/*local*/{
int escaped = FALSE;
int ch;
char *p;
for (input_data = p = e->cmd;
(ch = *input_data) != '\0';
input_data++, p++) {
if (p != input_data)
*p = ch;
if (escaped) {
if (ch == '%')
*--p = ch;
escaped = FALSE;
continue;
}
if (ch == '\\') {
escaped = TRUE;
continue;
}
if (ch == '%') {
*input_data++ = '\0';
break;
}
}
*p = '\0';
}
/* fork again, this time so we can exec the user's command.
*/
switch (fork()) {
case -1:
log_it("CRON", getpid(), "error", "can't fork");
exit(ERROR_EXIT);
/*NOTREACHED*/
case 0:
Debug(DPROC, ("[%ld] grandchild process fork()'ed\n",
(long)getpid()))
/* write a log message. we've waited this long to do it
* because it was not until now that we knew the PID that
* the actual user command shell was going to get and the
* PID is part of the log message.
*/
if ((e->flags & DONT_LOG) == 0) {
char *x = mkprints((u_char *)e->cmd, strlen(e->cmd));
log_it(usernm, getpid(), "CMD", x);
free(x);
}
/* that's the last thing we'll log. close the log files.
*/
log_close();
/* get new pgrp, void tty, etc.
*/
(void) setsid();
/* close the pipe ends that we won't use. this doesn't affect
* the parent, who has to read and write them; it keeps the
* kernel from recording us as a potential client TWICE --
* which would keep it from sending SIGPIPE in otherwise
* appropriate circumstances.
*/
close(stdin_pipe[WRITE_PIPE]);
close(stdout_pipe[READ_PIPE]);
/* grandchild process. make std{in,out} be the ends of
* pipes opened by our daddy; make stderr go to stdout.
*/
if (stdin_pipe[READ_PIPE] != STDIN) {
dup2(stdin_pipe[READ_PIPE], STDIN);
close(stdin_pipe[READ_PIPE]);
}
if (stdout_pipe[WRITE_PIPE] != STDOUT) {
dup2(stdout_pipe[WRITE_PIPE], STDOUT);
close(stdout_pipe[WRITE_PIPE]);
}
dup2(STDOUT, STDERR);
/* set our directory, uid and gid. Set gid first, since once
* we set uid, we've lost root privileges.
*/
#ifdef LOGIN_CAP
{
#ifdef BSD_AUTH
auth_session_t *as;
#endif
login_cap_t *lc;
char **p;
extern char **environ;
/* XXX - should just pass in a login_cap_t * */
if ((lc = login_getclass(e->pwd->pw_class)) == NULL) {
fprintf(stderr,
"unable to get login class for %s\n",
e->pwd->pw_name);
_exit(ERROR_EXIT);
}
if (setusercontext(lc, e->pwd, e->pwd->pw_uid, LOGIN_SETALL) < 0) {
fprintf(stderr,
"setusercontext failed for %s\n",
e->pwd->pw_name);
_exit(ERROR_EXIT);
}
#ifdef BSD_AUTH
as = auth_open();
if (as == NULL || auth_setpwd(as, e->pwd) != 0) {
fprintf(stderr, "can't malloc\n");
_exit(ERROR_EXIT);
}
if (auth_approval(as, lc, usernm, "cron") <= 0) {
fprintf(stderr, "approval failed for %s\n",
e->pwd->pw_name);
_exit(ERROR_EXIT);
}
auth_close(as);
#endif /* BSD_AUTH */
login_close(lc);
/* If no PATH specified in crontab file but
* we just added one via login.conf, add it to
* the crontab environment.
*/
if (env_get("PATH", e->envp) == NULL && environ != NULL) {
for (p = environ; *p; p++) {
if (strncmp(*p, "PATH=", 5) == 0) {
e->envp = env_set(e->envp, *p);
break;
}
}
}
}
#else
if (setgid(e->pwd->pw_gid) || initgroups(usernm, e->pwd->pw_gid)) {
fprintf(stderr,
"unable to set groups for %s\n", e->pwd->pw_name);
_exit(ERROR_EXIT);
}
#if (defined(BSD)) && (BSD >= 199103)
setlogin(usernm);
#endif /* BSD */
if (setuid(e->pwd->pw_uid)) {
fprintf(stderr,
"unable to set uid to %lu\n",
(unsigned long)e->pwd->pw_uid);
_exit(ERROR_EXIT);
}
#endif /* LOGIN_CAP */
chdir(env_get("HOME", e->envp));
/*
* Exec the command.
*/
{
char *shell = env_get("SHELL", e->envp);
# if DEBUGGING
if (DebugFlags & DTEST) {
fprintf(stderr,
"debug DTEST is on, not exec'ing command.\n");
fprintf(stderr,
"\tcmd='%s' shell='%s'\n", e->cmd, shell);
_exit(OK_EXIT);
}
# endif /*DEBUGGING*/
execle(shell, shell, "-c", e->cmd, (char *)NULL, e->envp);
fprintf(stderr, "execle: couldn't exec `%s'\n", shell);
perror("execle");
_exit(ERROR_EXIT);
}
break;
default:
/* parent process */
break;
}
children++;
/* middle process, child of original cron, parent of process running
* the user's command.
*/
Debug(DPROC, ("[%ld] child continues, closing pipes\n",(long)getpid()))
/* close the ends of the pipe that will only be referenced in the
* grandchild process...
*/
close(stdin_pipe[READ_PIPE]);
close(stdout_pipe[WRITE_PIPE]);
/*
* write, to the pipe connected to child's stdin, any input specified
* after a % in the crontab entry. while we copy, convert any
* additional %'s to newlines. when done, if some characters were
* written and the last one wasn't a newline, write a newline.
*
* Note that if the input data won't fit into one pipe buffer (2K
* or 4K on most BSD systems), and the child doesn't read its stdin,
* we would block here. thus we must fork again.
*/
if (*input_data && fork() == 0) {
FILE *out = fdopen(stdin_pipe[WRITE_PIPE], "w");
int need_newline = FALSE;
int escaped = FALSE;
int ch;
Debug(DPROC, ("[%ld] child2 sending data to grandchild\n",
(long)getpid()))
/* close the pipe we don't use, since we inherited it and
* are part of its reference count now.
*/
close(stdout_pipe[READ_PIPE]);
/* translation:
* \% -> %
* % -> \n
* \x -> \x for all x != %
*/
while ((ch = *input_data++) != '\0') {
if (escaped) {
if (ch != '%')
putc('\\', out);
} else {
if (ch == '%')
ch = '\n';
}
if (!(escaped = (ch == '\\'))) {
putc(ch, out);
need_newline = (ch != '\n');
}
}
if (escaped)
putc('\\', out);
if (need_newline)
putc('\n', out);
/* close the pipe, causing an EOF condition. fclose causes
* stdin_pipe[WRITE_PIPE] to be closed, too.
*/
fclose(out);
Debug(DPROC, ("[%ld] child2 done sending to grandchild\n",
(long)getpid()))
exit(0);
}
/* close the pipe to the grandkiddie's stdin, since its wicked uncle
* ernie back there has it open and will close it when he's done.
*/
close(stdin_pipe[WRITE_PIPE]);
children++;
/*
* read output from the grandchild. it's stderr has been redirected to
* it's stdout, which has been redirected to our pipe. if there is any
* output, we'll be mailing it to the user whose crontab this is...
* when the grandchild exits, we'll get EOF.
*/
Debug(DPROC, ("[%ld] child reading output from grandchild\n",
(long)getpid()))
(void) signal(SIGPIPE, SIG_IGN);
in = fdopen(stdout_pipe[READ_PIPE], "r");
if (in != NULL) {
int ch = getc(in);
if (ch != EOF) {
FILE *mail = NULL;
char *mailto;
int bytes = 1;
int status = 0;
Debug(DPROC|DEXT,
("[%ld] got data (%x:%c) from grandchild\n",
(long)getpid(), ch, ch))
/* get name of recipient. this is MAILTO if set to a
* valid local username; USER otherwise.
*/
mailto = env_get("MAILTO", e->envp);
if (!mailto) {
/* MAILTO not present, set to USER.
*/
mailto = usernm;
} else if (!*mailto || !safe_p(usernm, mailto)) {
mailto = NULL;
}
/* if we are supposed to be mailing, MAILTO will
* be non-NULL. only in this case should we set
* up the mail command and subjects and stuff...
*/
if (mailto) {
char **env;
char mailcmd[MAX_COMMAND];
char hostname[MAXHOSTNAMELEN];
gethostname(hostname, sizeof(hostname));
if (snprintf(mailcmd, sizeof mailcmd, MAILFMT,
MAILARG) >= sizeof mailcmd) {
fprintf(stderr, "mailcmd too long\n");
(void) _exit(ERROR_EXIT);
}
if (!(mail = cron_popen(mailcmd, "w", e->pwd))) {
perror(mailcmd);
(void) _exit(ERROR_EXIT);
}
fprintf(mail, "From: root (Cron Daemon)\n");
fprintf(mail, "To: %s\n", mailto);
fprintf(mail, "Subject: Cron <%s@%s> %s\n",
usernm, first_word(hostname, "."),
e->cmd);
fprintf(mail, "Auto-Submitted: auto-generated\n");
#ifdef MAIL_DATE
fprintf(mail, "Date: %s\n",
arpadate(&StartTime));
#endif /*MAIL_DATE*/
for (env = e->envp; *env; env++)
fprintf(mail, "X-Cron-Env: <%s>\n",
*env);
fprintf(mail, "\n");
/* this was the first char from the pipe
*/
fputc(ch, mail);
}
/* we have to read the input pipe no matter whether
* we mail or not, but obviously we only write to
* mail pipe if we ARE mailing.
*/
while (EOF != (ch = getc(in))) {
bytes++;
if (mail)
fputc(ch, mail);
}
/* only close pipe if we opened it -- i.e., we're
* mailing...
*/
if (mail) {
Debug(DPROC, ("[%ld] closing pipe to mail\n",
(long)getpid()))
/* Note: the pclose will probably see
* the termination of the grandchild
* in addition to the mail process, since
* it (the grandchild) is likely to exit
* after closing its stdout.
*/
status = cron_pclose(mail);
}
/* if there was output and we could not mail it,
* log the facts so the poor user can figure out
* what's going on.
*/
if (mail && status) {
char buf[MAX_TEMPSTR];
snprintf(buf, sizeof buf,
"mailed %d byte%s of output but got status 0x%04x\n",
bytes, (bytes==1)?"":"s",
status);
log_it(usernm, getpid(), "MAIL", buf);
}
} /*if data from grandchild*/
Debug(DPROC, ("[%ld] got EOF from grandchild\n",
(long)getpid()))
fclose(in); /* also closes stdout_pipe[READ_PIPE] */
}
/* wait for children to die.
*/
for (; children > 0; children--) {
WAIT_T waiter;
PID_T pid;
Debug(DPROC, ("[%ld] waiting for grandchild #%d to finish\n",
(long)getpid(), children))
while ((pid = wait(&waiter)) < OK && errno == EINTR)
;
if (pid < OK) {
Debug(DPROC,
("[%ld] no more grandchildren--mail written?\n",
(long)getpid()))
break;
}
Debug(DPROC, ("[%ld] grandchild #%ld finished, status=%04x",
(long)getpid(), (long)pid, WEXITSTATUS(waiter)))
if (WIFSIGNALED(waiter) && WCOREDUMP(waiter))
Debug(DPROC, (", dumped core"))
Debug(DPROC, ("\n"))
}
}
int
safe_p(const char *usernm, const char *s) {
static const char safe_delim[] = "@!:%-.,"; /* conservative! */
const char *t;
int ch, first;
for (t = s, first = 1; (ch = *t++) != '\0'; first = 0) {
if (isascii(ch) && isprint(ch) &&
(isalnum(ch) || ch == '_' ||
(!first && strchr(safe_delim, ch))))
continue;
log_it(usernm, getpid(), "UNSAFE", s);
return (FALSE);
}
return (TRUE);
}