/* vi: set sw=4 ts=4: */ /* * crond -d[#] -c <crondir> -f -b * * run as root, but NOT setuid root * * Copyright 1994 Matthew Dillon (dillon@apollo.west.oic.com) * (version 2.3.2) * Vladimir Oleynik <dzo@simtreas.ru> (C) 2002 * * Licensed under the GPL v2 or later, see the file LICENSE in this tarball. */ #include "libbb.h" #include <syslog.h> /* glibc frees previous setenv'ed value when we do next setenv() * of the same variable. uclibc does not do this! */ #if (defined(__GLIBC__) && !defined(__UCLIBC__)) /* || OTHER_SAFE_LIBC... */ #define SETENV_LEAKS 0 #else #define SETENV_LEAKS 1 #endif #define TMPDIR CONFIG_FEATURE_CROND_DIR #define CRONTABS CONFIG_FEATURE_CROND_DIR "/crontabs" #ifndef SENDMAIL #define SENDMAIL "sendmail" #endif #ifndef SENDMAIL_ARGS #define SENDMAIL_ARGS "-ti", "oem" #endif #ifndef CRONUPDATE #define CRONUPDATE "cron.update" #endif #ifndef MAXLINES #define MAXLINES 256 /* max lines in non-root crontabs */ #endif typedef struct CronFile { struct CronFile *cf_Next; struct CronLine *cf_LineBase; char *cf_User; /* username */ smallint cf_Ready; /* bool: one or more jobs ready */ smallint cf_Running; /* bool: one or more jobs running */ smallint cf_Deleted; /* marked for deletion, ignore */ } CronFile; typedef struct CronLine { struct CronLine *cl_Next; char *cl_Shell; /* shell command */ pid_t cl_Pid; /* running pid, 0, or armed (-1) */ #if ENABLE_FEATURE_CROND_CALL_SENDMAIL int cl_MailPos; /* 'empty file' size */ smallint cl_MailFlag; /* running pid is for mail */ char *cl_MailTo; /* whom to mail results */ #endif /* ordered by size, not in natural order. makes code smaller: */ char cl_Dow[7]; /* 0-6, beginning sunday */ char cl_Mons[12]; /* 0-11 */ char cl_Hrs[24]; /* 0-23 */ char cl_Days[32]; /* 1-31 */ char cl_Mins[60]; /* 0-59 */ } CronLine; #define DaemonUid 0 enum { OPT_l = (1 << 0), OPT_L = (1 << 1), OPT_f = (1 << 2), OPT_b = (1 << 3), OPT_S = (1 << 4), OPT_c = (1 << 5), OPT_d = (1 << 6) * ENABLE_FEATURE_CROND_D, }; #if ENABLE_FEATURE_CROND_D #define DebugOpt (option_mask32 & OPT_d) #else #define DebugOpt 0 #endif struct globals { unsigned LogLevel; /* = 8; */ const char *LogFile; const char *CDir; /* = CRONTABS; */ CronFile *FileBase; #if SETENV_LEAKS char *env_var_user; char *env_var_home; #endif }; #define G (*(struct globals*)&bb_common_bufsiz1) #define LogLevel (G.LogLevel ) #define LogFile (G.LogFile ) #define CDir (G.CDir ) #define FileBase (G.FileBase ) #define env_var_user (G.env_var_user ) #define env_var_home (G.env_var_home ) #define INIT_G() do { \ LogLevel = 8; \ CDir = CRONTABS; \ } while (0) static void CheckUpdates(void); static void SynchronizeDir(void); static int TestJobs(time_t t1, time_t t2); static void RunJobs(void); static int CheckJobs(void); static void RunJob(const char *user, CronLine *line); #if ENABLE_FEATURE_CROND_CALL_SENDMAIL static void EndJob(const char *user, CronLine *line); #else #define EndJob(user, line) ((line)->cl_Pid = 0) #endif static void DeleteFile(const char *userName); #define LVL5 "\x05" #define LVL7 "\x07" #define LVL8 "\x08" #define LVL9 "\x09" #define WARN9 "\x49" #define DIE9 "\xc9" /* level >= 20 is "error" */ #define ERR20 "\x14" static void crondlog(const char *ctl, ...) { va_list va; int level = (ctl[0] & 0x1f); va_start(va, ctl); if (level >= (int)LogLevel) { /* Debug mode: all to (non-redirected) stderr, */ /* Syslog mode: all to syslog (logmode = LOGMODE_SYSLOG), */ if (!DebugOpt && LogFile) { /* Otherwise (log to file): we reopen log file at every write: */ int logfd = open3_or_warn(LogFile, O_WRONLY | O_CREAT | O_APPEND, 0666); if (logfd >= 0) xmove_fd(logfd, STDERR_FILENO); } // TODO: ERR -> error, WARN -> warning, LVL -> info bb_verror_msg(ctl + 1, va, /* strerr: */ NULL); } va_end(va); if (ctl[0] & 0x80) exit(20); } int crond_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; int crond_main(int argc UNUSED_PARAM, char **argv) { unsigned opt; INIT_G(); /* "-b after -f is ignored", and so on for every pair a-b */ opt_complementary = "f-b:b-f:S-L:L-S" USE_FEATURE_CROND_D(":d-l") ":l+:d+"; /* -l and -d have numeric param */ opt = getopt32(argv, "l:L:fbSc:" USE_FEATURE_CROND_D("d:"), &LogLevel, &LogFile, &CDir USE_FEATURE_CROND_D(,&LogLevel)); /* both -d N and -l N set the same variable: LogLevel */ if (!(opt & OPT_f)) { /* close stdin, stdout, stderr. * close unused descriptors - don't need them. */ bb_daemonize_or_rexec(DAEMON_CLOSE_EXTRA_FDS, argv); } if (!DebugOpt && LogFile == NULL) { /* logging to syslog */ openlog(applet_name, LOG_CONS | LOG_PID, LOG_CRON); logmode = LOGMODE_SYSLOG; } xchdir(CDir); //signal(SIGHUP, SIG_IGN); /* ? original crond dies on HUP... */ xsetenv("SHELL", DEFAULT_SHELL); /* once, for all future children */ crondlog(LVL9 "crond (busybox "BB_VER") started, log level %d", LogLevel); SynchronizeDir(); /* main loop - synchronize to 1 second after the minute, minimum sleep * of 1 second. */ { time_t t1 = time(NULL); time_t t2; long dt; int rescan = 60; int sleep_time = 60; write_pidfile("/var/run/crond.pid"); for (;;) { sleep((sleep_time + 1) - (time(NULL) % sleep_time)); t2 = time(NULL); dt = (long)t2 - (long)t1; /* * The file 'cron.update' is checked to determine new cron * jobs. The directory is rescanned once an hour to deal * with any screwups. * * check for disparity. Disparities over an hour either way * result in resynchronization. A reverse-indexed disparity * less then an hour causes us to effectively sleep until we * match the original time (i.e. no re-execution of jobs that * have just been run). A forward-indexed disparity less then * an hour causes intermediate jobs to be run, but only once * in the worst case. * * when running jobs, the inequality used is greater but not * equal to t1, and less then or equal to t2. */ if (--rescan == 0) { rescan = 60; SynchronizeDir(); } CheckUpdates(); if (DebugOpt) crondlog(LVL5 "wakeup dt=%ld", dt); if (dt < -60 * 60 || dt > 60 * 60) { crondlog(WARN9 "time disparity of %d minutes detected", dt / 60); } else if (dt > 0) { TestJobs(t1, t2); RunJobs(); sleep(5); if (CheckJobs() > 0) { sleep_time = 10; } else { sleep_time = 60; } } t1 = t2; } } return 0; /* not reached */ } #if SETENV_LEAKS /* We set environment *before* vfork (because we want to use vfork), * so we cannot use setenv() - repeated calls to setenv() may leak memory! * Using putenv(), and freeing memory after unsetenv() won't leak */ static void safe_setenv(char **pvar_val, const char *var, const char *val) { char *var_val = *pvar_val; if (var_val) { bb_unsetenv(var_val); free(var_val); } *pvar_val = xasprintf("%s=%s", var, val); putenv(*pvar_val); } #endif static void SetEnv(struct passwd *pas) { #if SETENV_LEAKS safe_setenv(&env_var_user, "USER", pas->pw_name); safe_setenv(&env_var_home, "HOME", pas->pw_dir); /* if we want to set user's shell instead: */ /*safe_setenv(env_var_user, "SHELL", pas->pw_shell);*/ #else xsetenv("USER", pas->pw_name); xsetenv("HOME", pas->pw_dir); #endif /* currently, we use constant one: */ /*setenv("SHELL", DEFAULT_SHELL, 1); - done earlier */ } static void ChangeUser(struct passwd *pas) { /* careful: we're after vfork! */ change_identity(pas); /* - initgroups, setgid, setuid */ if (chdir(pas->pw_dir) < 0) { crondlog(LVL9 "can't chdir(%s)", pas->pw_dir); if (chdir(TMPDIR) < 0) { crondlog(DIE9 "can't chdir(%s)", TMPDIR); /* exits */ } } } static const char DowAry[] ALIGN1 = "sun""mon""tue""wed""thu""fri""sat" /* "Sun""Mon""Tue""Wed""Thu""Fri""Sat" */ ; static const char MonAry[] ALIGN1 = "jan""feb""mar""apr""may""jun""jul""aug""sep""oct""nov""dec" /* "Jan""Feb""Mar""Apr""May""Jun""Jul""Aug""Sep""Oct""Nov""Dec" */ ; static void ParseField(char *user, char *ary, int modvalue, int off, const char *names, char *ptr) /* 'names' is a pointer to a set of 3-char abbreviations */ { char *base = ptr; int n1 = -1; int n2 = -1; // this can't happen due to config_read() /*if (base == NULL) return;*/ while (1) { int skip = 0; /* Handle numeric digit or symbol or '*' */ if (*ptr == '*') { n1 = 0; /* everything will be filled */ n2 = modvalue - 1; skip = 1; ++ptr; } else if (isdigit(*ptr)) { if (n1 < 0) { n1 = strtol(ptr, &ptr, 10) + off; } else { n2 = strtol(ptr, &ptr, 10) + off; } skip = 1; } else if (names) { int i; for (i = 0; names[i]; i += 3) { /* was using strncmp before... */ if (strncasecmp(ptr, &names[i], 3) == 0) { ptr += 3; if (n1 < 0) { n1 = i / 3; } else { n2 = i / 3; } skip = 1; break; } } } /* handle optional range '-' */ if (skip == 0) { goto err; } if (*ptr == '-' && n2 < 0) { ++ptr; continue; } /* * collapse single-value ranges, handle skipmark, and fill * in the character array appropriately. */ if (n2 < 0) { n2 = n1; } if (*ptr == '/') { skip = strtol(ptr + 1, &ptr, 10); } /* * fill array, using a failsafe is the easiest way to prevent * an endless loop */ { int s0 = 1; int failsafe = 1024; --n1; do { n1 = (n1 + 1) % modvalue; if (--s0 == 0) { ary[n1 % modvalue] = 1; s0 = skip; } if (--failsafe == 0) { goto err; } } while (n1 != n2); } if (*ptr != ',') { break; } ++ptr; n1 = -1; n2 = -1; } if (*ptr) { err: crondlog(WARN9 "user %s: parse error at %s", user, base); return; } if (DebugOpt && (LogLevel <= 5)) { /* like LVL5 */ /* can't use crondlog, it inserts '\n' */ int i; for (i = 0; i < modvalue; ++i) fprintf(stderr, "%d", (unsigned char)ary[i]); fputc('\n', stderr); } } static void FixDayDow(CronLine *line) { unsigned i; int weekUsed = 0; int daysUsed = 0; for (i = 0; i < ARRAY_SIZE(line->cl_Dow); ++i) { if (line->cl_Dow[i] == 0) { weekUsed = 1; break; } } for (i = 0; i < ARRAY_SIZE(line->cl_Days); ++i) { if (line->cl_Days[i] == 0) { daysUsed = 1; break; } } if (weekUsed != daysUsed) { if (weekUsed) memset(line->cl_Days, 0, sizeof(line->cl_Days)); else /* daysUsed */ memset(line->cl_Dow, 0, sizeof(line->cl_Dow)); } } static void SynchronizeFile(const char *fileName) { struct parser_t *parser; struct stat sbuf; int maxLines; char *tokens[6]; #if ENABLE_FEATURE_CROND_CALL_SENDMAIL char *mailTo = NULL; #endif if (!fileName) return; DeleteFile(fileName); parser = config_open(fileName); if (!parser) return; maxLines = (strcmp(fileName, "root") == 0) ? 65535 : MAXLINES; if (fstat(fileno(parser->fp), &sbuf) == 0 && sbuf.st_uid == DaemonUid) { CronFile *file = xzalloc(sizeof(CronFile)); CronLine **pline; int n; file->cf_User = xstrdup(fileName); pline = &file->cf_LineBase; while (1) { CronLine *line; if (!--maxLines) break; n = config_read(parser, tokens, 6, 1, "# \t", PARSE_NORMAL | PARSE_KEEP_COPY); if (!n) break; if (DebugOpt) crondlog(LVL5 "user:%s entry:%s", fileName, parser->data); /* check if line is setting MAILTO= */ if (0 == strncmp(tokens[0], "MAILTO=", 7)) { #if ENABLE_FEATURE_CROND_CALL_SENDMAIL free(mailTo); mailTo = (tokens[0][7]) ? xstrdup(&tokens[0][7]) : NULL; #endif /* otherwise just ignore such lines */ continue; } /* check if a minimum of tokens is specified */ if (n < 6) continue; *pline = line = xzalloc(sizeof(*line)); /* parse date ranges */ ParseField(file->cf_User, line->cl_Mins, 60, 0, NULL, tokens[0]); ParseField(file->cf_User, line->cl_Hrs, 24, 0, NULL, tokens[1]); ParseField(file->cf_User, line->cl_Days, 32, 0, NULL, tokens[2]); ParseField(file->cf_User, line->cl_Mons, 12, -1, MonAry, tokens[3]); ParseField(file->cf_User, line->cl_Dow, 7, 0, DowAry, tokens[4]); /* * fix days and dow - if one is not "*" and the other * is "*", the other is set to 0, and vise-versa */ FixDayDow(line); #if ENABLE_FEATURE_CROND_CALL_SENDMAIL /* copy mailto (can be NULL) */ line->cl_MailTo = xstrdup(mailTo); #endif /* copy command */ line->cl_Shell = xstrdup(tokens[5]); if (DebugOpt) { crondlog(LVL5 " command:%s", tokens[5]); } pline = &line->cl_Next; //bb_error_msg("M[%s]F[%s][%s][%s][%s][%s][%s]", mailTo, tokens[0], tokens[1], tokens[2], tokens[3], tokens[4], tokens[5]); } *pline = NULL; file->cf_Next = FileBase; FileBase = file; if (maxLines == 0) { crondlog(WARN9 "user %s: too many lines", fileName); } } config_close(parser); } static void CheckUpdates(void) { FILE *fi; char buf[256]; fi = fopen_for_read(CRONUPDATE); if (fi != NULL) { unlink(CRONUPDATE); while (fgets(buf, sizeof(buf), fi) != NULL) { /* use first word only */ SynchronizeFile(strtok(buf, " \t\r\n")); } fclose(fi); } } static void SynchronizeDir(void) { CronFile *file; /* Attempt to delete the database. */ again: for (file = FileBase; file; file = file->cf_Next) { if (!file->cf_Deleted) { DeleteFile(file->cf_User); goto again; } } /* * Remove cron update file * * Re-chdir, in case directory was renamed & deleted, or otherwise * screwed up. * * scan directory and add associated users */ unlink(CRONUPDATE); if (chdir(CDir) < 0) { crondlog(DIE9 "can't chdir(%s)", CDir); } { DIR *dir = opendir("."); struct dirent *den; if (!dir) crondlog(DIE9 "can't chdir(%s)", "."); /* exits */ while ((den = readdir(dir)) != NULL) { if (strchr(den->d_name, '.') != NULL) { continue; } if (getpwnam(den->d_name)) { SynchronizeFile(den->d_name); } else { crondlog(LVL7 "ignoring %s", den->d_name); } } closedir(dir); } } /* * DeleteFile() - delete user database * * Note: multiple entries for same user may exist if we were unable to * completely delete a database due to running processes. */ static void DeleteFile(const char *userName) { CronFile **pfile = &FileBase; CronFile *file; while ((file = *pfile) != NULL) { if (strcmp(userName, file->cf_User) == 0) { CronLine **pline = &file->cf_LineBase; CronLine *line; file->cf_Running = 0; file->cf_Deleted = 1; while ((line = *pline) != NULL) { if (line->cl_Pid > 0) { file->cf_Running = 1; pline = &line->cl_Next; } else { *pline = line->cl_Next; free(line->cl_Shell); free(line); } } if (file->cf_Running == 0) { *pfile = file->cf_Next; free(file->cf_User); free(file); } else { pfile = &file->cf_Next; } } else { pfile = &file->cf_Next; } } } /* * TestJobs() * * determine which jobs need to be run. Under normal conditions, the * period is about a minute (one scan). Worst case it will be one * hour (60 scans). */ static int TestJobs(time_t t1, time_t t2) { int nJobs = 0; time_t t; /* Find jobs > t1 and <= t2 */ for (t = t1 - t1 % 60; t <= t2; t += 60) { struct tm *tp; CronFile *file; CronLine *line; if (t <= t1) continue; tp = localtime(&t); for (file = FileBase; file; file = file->cf_Next) { if (DebugOpt) crondlog(LVL5 "file %s:", file->cf_User); if (file->cf_Deleted) continue; for (line = file->cf_LineBase; line; line = line->cl_Next) { if (DebugOpt) crondlog(LVL5 " line %s", line->cl_Shell); if (line->cl_Mins[tp->tm_min] && line->cl_Hrs[tp->tm_hour] && (line->cl_Days[tp->tm_mday] || line->cl_Dow[tp->tm_wday]) && line->cl_Mons[tp->tm_mon] ) { if (DebugOpt) { crondlog(LVL5 " job: %d %s", (int)line->cl_Pid, line->cl_Shell); } if (line->cl_Pid > 0) { crondlog(LVL8 "user %s: process already running: %s", file->cf_User, line->cl_Shell); } else if (line->cl_Pid == 0) { line->cl_Pid = -1; file->cf_Ready = 1; ++nJobs; } } } } } return nJobs; } static void RunJobs(void) { CronFile *file; CronLine *line; for (file = FileBase; file; file = file->cf_Next) { if (!file->cf_Ready) continue; file->cf_Ready = 0; for (line = file->cf_LineBase; line; line = line->cl_Next) { if (line->cl_Pid >= 0) continue; RunJob(file->cf_User, line); crondlog(LVL8 "USER %s pid %3d cmd %s", file->cf_User, (int)line->cl_Pid, line->cl_Shell); if (line->cl_Pid < 0) { file->cf_Ready = 1; } else if (line->cl_Pid > 0) { file->cf_Running = 1; } } } } /* * CheckJobs() - check for job completion * * Check for job completion, return number of jobs still running after * all done. */ static int CheckJobs(void) { CronFile *file; CronLine *line; int nStillRunning = 0; for (file = FileBase; file; file = file->cf_Next) { if (file->cf_Running) { file->cf_Running = 0; for (line = file->cf_LineBase; line; line = line->cl_Next) { int status, r; if (line->cl_Pid <= 0) continue; r = waitpid(line->cl_Pid, &status, WNOHANG); if (r < 0 || r == line->cl_Pid) { EndJob(file->cf_User, line); if (line->cl_Pid) { file->cf_Running = 1; } } else if (r == 0) { file->cf_Running = 1; } } } nStillRunning += file->cf_Running; } return nStillRunning; } #if ENABLE_FEATURE_CROND_CALL_SENDMAIL // TODO: sendmail should be _run-time_ option, not compile-time! static void ForkJob(const char *user, CronLine *line, int mailFd, const char *prog, const char *cmd, const char *arg, const char *mail_filename) { struct passwd *pas; pid_t pid; /* prepare things before vfork */ pas = getpwnam(user); if (!pas) { crondlog(LVL9 "can't get uid for %s", user); goto err; } SetEnv(pas); pid = vfork(); if (pid == 0) { /* CHILD */ /* change running state to the user in question */ ChangeUser(pas); if (DebugOpt) { crondlog(LVL5 "child running %s", prog); } if (mailFd >= 0) { xmove_fd(mailFd, mail_filename ? 1 : 0); dup2(1, 2); } /* crond 3.0pl1-100 puts tasks in separate process groups */ bb_setpgrp(); execlp(prog, prog, cmd, arg, (char *) NULL); crondlog(ERR20 "can't exec, user %s cmd %s %s %s", user, prog, cmd, arg); if (mail_filename) { fdprintf(1, "Exec failed: %s -c %s\n", prog, arg); } _exit(EXIT_SUCCESS); } line->cl_Pid = pid; if (pid < 0) { /* FORK FAILED */ crondlog(ERR20 "can't vfork"); err: line->cl_Pid = 0; if (mail_filename) { unlink(mail_filename); } } else if (mail_filename) { /* PARENT, FORK SUCCESS * rename mail-file based on pid of process */ char mailFile2[128]; snprintf(mailFile2, sizeof(mailFile2), "%s/cron.%s.%d", TMPDIR, user, pid); rename(mail_filename, mailFile2); // TODO: xrename? } /* * Close the mail file descriptor.. we can't just leave it open in * a structure, closing it later, because we might run out of descriptors */ if (mailFd >= 0) { close(mailFd); } } static void RunJob(const char *user, CronLine *line) { char mailFile[128]; int mailFd = -1; line->cl_Pid = 0; line->cl_MailFlag = 0; if (line->cl_MailTo) { /* open mail file - owner root so nobody can screw with it. */ snprintf(mailFile, sizeof(mailFile), "%s/cron.%s.%d", TMPDIR, user, getpid()); mailFd = open(mailFile, O_CREAT | O_TRUNC | O_WRONLY | O_EXCL | O_APPEND, 0600); if (mailFd >= 0) { line->cl_MailFlag = 1; fdprintf(mailFd, "To: %s\nSubject: cron: %s\n\n", line->cl_MailTo, line->cl_Shell); line->cl_MailPos = lseek(mailFd, 0, SEEK_CUR); } else { crondlog(ERR20 "cannot create mail file %s for user %s, " "discarding output", mailFile, user); } } ForkJob(user, line, mailFd, DEFAULT_SHELL, "-c", line->cl_Shell, mailFile); } /* * EndJob - called when job terminates and when mail terminates */ static void EndJob(const char *user, CronLine *line) { int mailFd; char mailFile[128]; struct stat sbuf; /* No job */ if (line->cl_Pid <= 0) { line->cl_Pid = 0; return; } /* * End of job and no mail file * End of sendmail job */ snprintf(mailFile, sizeof(mailFile), "%s/cron.%s.%d", TMPDIR, user, line->cl_Pid); line->cl_Pid = 0; if (line->cl_MailFlag == 0) { return; } line->cl_MailFlag = 0; /* * End of primary job - check for mail file. If size has increased and * the file is still valid, we sendmail it. */ mailFd = open(mailFile, O_RDONLY); unlink(mailFile); if (mailFd < 0) { return; } if (fstat(mailFd, &sbuf) < 0 || sbuf.st_uid != DaemonUid || sbuf.st_nlink != 0 || sbuf.st_size == line->cl_MailPos || !S_ISREG(sbuf.st_mode) ) { close(mailFd); return; } if (line->cl_MailTo) ForkJob(user, line, mailFd, SENDMAIL, SENDMAIL_ARGS, NULL); } #else /* crond without sendmail */ static void RunJob(const char *user, CronLine *line) { struct passwd *pas; pid_t pid; /* prepare things before vfork */ pas = getpwnam(user); if (!pas) { crondlog(LVL9 "can't get uid for %s", user); goto err; } SetEnv(pas); /* fork as the user in question and run program */ pid = vfork(); if (pid == 0) { /* CHILD */ /* change running state to the user in question */ ChangeUser(pas); if (DebugOpt) { crondlog(LVL5 "child running %s", DEFAULT_SHELL); } /* crond 3.0pl1-100 puts tasks in separate process groups */ bb_setpgrp(); execl(DEFAULT_SHELL, DEFAULT_SHELL, "-c", line->cl_Shell, (char *) NULL); crondlog(ERR20 "can't exec, user %s cmd %s %s %s", user, DEFAULT_SHELL, "-c", line->cl_Shell); _exit(EXIT_SUCCESS); } if (pid < 0) { /* FORK FAILED */ crondlog(ERR20 "can't vfork"); err: pid = 0; } line->cl_Pid = pid; } #endif /* ENABLE_FEATURE_CROND_CALL_SENDMAIL */