/* Copyright 1988,1990,1993,1994 by Paul Vixie * All rights reserved * * Distribute freely, except: don't remove my name from the source or * documentation (don't take credit for my work), mark your changes (don't * get me blamed for your possible bugs), don't alter or remove this * notice. May be sold if buildable source is provided to buyer. No * warrantee of any kind, express or implied, is included with this * software; use at your own risk, responsibility for damages (if any) to * anyone resulting from the use of this software rests entirely with the * user. * * Send bug reports, bug fixes, enhancements, requests, flames, etc., and * I'll try to keep a version up to date. I can be reached as follows: * Paul Vixie uunet!decwrl!vixie!paul */ #if !defined(lint) && !defined(LINT) static char rcsid[] = "$Id: do_command.c,v 1.2 1996/08/07 06:18:33 deraadt Exp $"; #endif #include "cron.h" #include #if defined(sequent) # include #endif #if defined(SYSLOG) # include #endif static void child_process __P((entry *, user *)), do_univ __P((user *)); void do_command(e, u) entry *e; user *u; { Debug(DPROC, ("[%d] do_command(%s, (%s,%d,%d))\n", getpid(), e->cmd, u->name, e->uid, e->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, ("[%d] child process done, exiting\n", getpid())) _exit(OK_EXIT); break; default: /* parent process */ break; } Debug(DPROC, ("[%d] main process returning to work\n", getpid())) } static void child_process(e, u) entry *e; user *u; { int stdin_pipe[2], stdout_pipe[2]; register char *input_data; char *usernm, *mailto; int children = 0; Debug(DPROC, ("[%d] child_process('%s')\n", getpid(), e->cmd)) /* mark ourselves as different to PS command watchers by upshifting * our program name. This has no effect on some kernels. */ /*local*/{ register char *pch; for (pch = ProgramName; *pch; pch++) *pch = MkUpper(*pch); } /* discover some useful and important environment settings */ usernm = env_get("LOGNAME", e->envp); mailto = env_get("MAILTO", e->envp); #ifdef USE_SIGCHLD /* 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() explictly. so we have to disable the signal (which * was inherited from the parent). */ (void) signal(SIGCHLD, SIG_IGN); #else /* on system-V systems, we are ignoring SIGCLD. we have to stop * ignoring it now or the wait() in cron_pclose() won't work. * because of this, we have to wait() for our children here, as well. */ (void) signal(SIGCLD, SIG_DFL); #endif /*BSD*/ /* 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. Subsequent %'s will be transformed into newlines, * but that happens later. */ /*local*/{ register int escaped = FALSE; register int ch; for (input_data = e->cmd; ch = *input_data; input_data++) { if (escaped) { escaped = FALSE; continue; } if (ch == '\\') { escaped = TRUE; continue; } if (ch == '%') { *input_data++ = '\0'; break; } } } /* fork again, this time so we can exec the user's command. */ switch (vfork()) { case -1: log_it("CRON",getpid(),"error","can't vfork"); exit(ERROR_EXIT); /*NOTREACHED*/ case 0: Debug(DPROC, ("[%d] grandchild process Vfork()'ed\n", 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. */ /*local*/{ 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. */ #ifdef SYSLOG closelog(); #endif /* 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. */ close(STDIN); dup2(stdin_pipe[READ_PIPE], STDIN); close(STDOUT); dup2(stdout_pipe[WRITE_PIPE], STDOUT); close(STDERR); dup2(STDOUT, STDERR); /* close the pipes we just dup'ed. The resources will remain. */ close(stdin_pipe[READ_PIPE]); close(stdout_pipe[WRITE_PIPE]); /* set our login universe. Do this in the grandchild * so that the child can invoke /usr/lib/sendmail * without surprises. */ do_univ(u); /* set our directory, uid and gid. Set gid first, since once * we set uid, we've lost root privledges. */ setgid(e->gid); # if defined(BSD) initgroups(env_get("LOGNAME", e->envp), e->gid); # endif setlogin(usernm); setuid(e->uid); /* we aren't root after this... */ 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 *)0, e->envp); fprintf(stderr, "execl: couldn't exec `%s'\n", shell); perror("execl"); _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, ("[%d] child continues, closing pipes\n", 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) { register FILE *out = fdopen(stdin_pipe[WRITE_PIPE], "w"); register int need_newline = FALSE; register int escaped = FALSE; register int ch; Debug(DPROC, ("[%d] child2 sending data to grandchild\n", 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++) { 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, ("[%d] child2 done sending to grandchild\n", 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, ("[%d] child reading output from grandchild\n", getpid())) /*local*/{ register FILE *in = fdopen(stdout_pipe[READ_PIPE], "r"); register int ch = getc(in); if (ch != EOF) { register FILE *mail; register int bytes = 1; int status = 0; Debug(DPROC|DEXT, ("[%d] got data (%x:%c) from grandchild\n", getpid(), ch, ch)) /* get name of recipient. this is MAILTO if set to a * valid local username; USER otherwise. */ if (mailto) { /* MAILTO was present in the environment */ if (!*mailto) { /* ... but it's empty. set to NULL */ mailto = NULL; } } else { /* MAILTO not present, set to USER. */ mailto = usernm; } /* 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) { register char **env; auto char mailcmd[MAX_COMMAND]; auto char hostname[MAXHOSTNAMELEN]; (void) gethostname(hostname, MAXHOSTNAMELEN); (void) snprintf(mailcmd, sizeof(mailcmd), MAILARGS, MAILCMD); if (!(mail = cron_popen(mailcmd, "w"))) { 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); # if defined(MAIL_DATE) fprintf(mail, "Date: %s\n", arpadate(&TargetTime)); # 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 */ putc(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 (mailto) putc(ch, mail); } /* only close pipe if we opened it -- i.e., we're * mailing... */ if (mailto) { Debug(DPROC, ("[%d] closing pipe to mail\n", 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 (mailto && status) { char buf[MAX_TEMPSTR]; sprintf(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, ("[%d] got EOF from grandchild\n", 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, ("[%d] waiting for grandchild #%d to finish\n", getpid(), children)) pid = wait(&waiter); if (pid < OK) { Debug(DPROC, ("[%d] no more grandchildren--mail written?\n", getpid())) break; } Debug(DPROC, ("[%d] grandchild #%d finished, status=%04x", getpid(), pid, WEXITSTATUS(waiter))) if (WIFSIGNALED(waiter) && WCOREDUMP(waiter)) Debug(DPROC, (", dumped core")) Debug(DPROC, ("\n")) } } static void do_univ(u) user *u; { #if defined(sequent) /* Dynix (Sequent) hack to put the user associated with * the passed user structure into the ATT universe if * necessary. We have to dig the gecos info out of * the user's password entry to see if the magic * "universe(att)" string is present. */ struct passwd *p; char *s; int i; p = getpwuid(u->uid); (void) endpwent(); if (p == NULL) return; s = p->pw_gecos; for (i = 0; i < 4; i++) { if ((s = strchr(s, ',')) == NULL) return; s++; } if (strcmp(s, "universe(att)")) return; (void) universe(U_ATT); #endif }