/* $OpenBSD: kern_time.c,v 1.54 2006/01/20 07:53:48 tedu Exp $ */ /* $NetBSD: kern_time.c,v 1.20 1996/02/18 11:57:06 fvdl Exp $ */ /* * Copyright (c) 1982, 1986, 1989, 1993 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)kern_time.c 8.4 (Berkeley) 5/26/95 */ #include #include #include #include #include #include #include #ifdef __HAVE_TIMECOUNTER #include #endif #include #include #include void itimerround(struct timeval *); /* * Time of day and interval timer support. * * These routines provide the kernel entry points to get and set * the time-of-day and per-process interval timers. Subroutines * here provide support for adding and subtracting timeval structures * and decrementing interval timers, optionally reloading the interval * timers when they expire. */ /* This function is used by clock_settime and settimeofday */ #ifdef __HAVE_TIMECOUNTER int settime(struct timespec *ts) { struct timespec now; /* * Don't allow the time to be set forward so far it will wrap * and become negative, thus allowing an attacker to bypass * the next check below. The cutoff is 1 year before rollover * occurs, so even if the attacker uses adjtime(2) to move * the time past the cutoff, it will take a very long time * to get to the wrap point. * * XXX: we check against INT_MAX since on 64-bit * platforms, sizeof(int) != sizeof(long) and * time_t is 32 bits even when atv.tv_sec is 64 bits. */ if (ts->tv_sec > INT_MAX - 365*24*60*60) { printf("denied attempt to set clock forward to %ld\n", ts->tv_sec); return (EPERM); } /* * If the system is secure, we do not allow the time to be * set to an earlier value (it may be slowed using adjtime, * but not set back). This feature prevent interlopers from * setting arbitrary time stamps on files. */ nanotime(&now); if (securelevel > 1 && timespeccmp(ts, &now, <)) { printf("denied attempt to set clock back %ld seconds\n", now.tv_sec - ts->tv_sec); return (EPERM); } tc_setclock(ts); resettodr(); return (0); } #else int settime(struct timespec *ts) { struct timeval delta, tvv, *tv; int s; /* XXX - Ugh. */ tv = &tvv; tvv.tv_sec = ts->tv_sec; tvv.tv_usec = ts->tv_nsec / 1000; /* * Don't allow the time to be set forward so far it will wrap * and become negative, thus allowing an attacker to bypass * the next check below. The cutoff is 1 year before rollover * occurs, so even if the attacker uses adjtime(2) to move * the time past the cutoff, it will take a very long time * to get to the wrap point. * * XXX: we check against INT_MAX since on 64-bit * platforms, sizeof(int) != sizeof(long) and * time_t is 32 bits even when atv.tv_sec is 64 bits. */ if (tv->tv_sec > INT_MAX - 365*24*60*60) { printf("denied attempt to set clock forward to %ld\n", tv->tv_sec); return (EPERM); } /* * If the system is secure, we do not allow the time to be * set to an earlier value (it may be slowed using adjtime, * but not set back). This feature prevent interlopers from * setting arbitrary time stamps on files. */ if (securelevel > 1 && timercmp(tv, &time, <)) { printf("denied attempt to set clock back %ld seconds\n", time_second - tv->tv_sec); return (EPERM); } /* WHAT DO WE DO ABOUT PENDING REAL-TIME TIMEOUTS??? */ s = splclock(); timersub(tv, &time, &delta); time = *tv; timeradd(&boottime, &delta, &boottime); splx(s); resettodr(); return (0); } #endif /* ARGSUSED */ int sys_clock_gettime(struct proc *p, void *v, register_t *retval) { struct sys_clock_gettime_args /* { syscallarg(clockid_t) clock_id; syscallarg(struct timespec *) tp; } */ *uap = v; clockid_t clock_id; struct timespec ats; clock_id = SCARG(uap, clock_id); switch (clock_id) { case CLOCK_REALTIME: nanotime(&ats); break; case CLOCK_MONOTONIC: nanouptime(&ats); break; default: return (EINVAL); } return copyout(&ats, SCARG(uap, tp), sizeof(ats)); } /* ARGSUSED */ int sys_clock_settime(struct proc *p, void *v, register_t *retval) { struct sys_clock_settime_args /* { syscallarg(clockid_t) clock_id; syscallarg(const struct timespec *) tp; } */ *uap = v; struct timespec ats; clockid_t clock_id; int error; if ((error = suser(p, 0)) != 0) return (error); if ((error = copyin(SCARG(uap, tp), &ats, sizeof(ats))) != 0) return (error); clock_id = SCARG(uap, clock_id); switch (clock_id) { case CLOCK_REALTIME: if ((error = settime(&ats)) != 0) return (error); break; case CLOCK_MONOTONIC: return (EINVAL); /* read-only clock */ default: return (EINVAL); } return (0); } int sys_clock_getres(struct proc *p, void *v, register_t *retval) { struct sys_clock_getres_args /* { syscallarg(clockid_t) clock_id; syscallarg(struct timespec *) tp; } */ *uap = v; clockid_t clock_id; struct timespec ts; int error = 0; clock_id = SCARG(uap, clock_id); switch (clock_id) { case CLOCK_REALTIME: case CLOCK_MONOTONIC: ts.tv_sec = 0; ts.tv_nsec = 1000000000 / hz; break; default: return (EINVAL); } if (SCARG(uap, tp)) error = copyout(&ts, SCARG(uap, tp), sizeof (ts)); return error; } /* ARGSUSED */ int sys_nanosleep(struct proc *p, void *v, register_t *retval) { static int nanowait; struct sys_nanosleep_args/* { syscallarg(const struct timespec *) rqtp; syscallarg(struct timespec *) rmtp; } */ *uap = v; struct timespec rqt, rmt; struct timespec sts, ets; struct timeval tv; int error; error = copyin((const void *)SCARG(uap, rqtp), (void *)&rqt, sizeof(struct timespec)); if (error) return (error); TIMESPEC_TO_TIMEVAL(&tv, &rqt); if (itimerfix(&tv)) return (EINVAL); if (SCARG(uap, rmtp)) getnanouptime(&sts); error = tsleep(&nanowait, PWAIT | PCATCH, "nanosleep", MAX(1, tvtohz(&tv))); if (error == ERESTART) error = EINTR; if (error == EWOULDBLOCK) error = 0; if (SCARG(uap, rmtp)) { getnanouptime(&ets); timespecsub(&ets, &sts, &sts); timespecsub(&rqt, &sts, &rmt); if (rmt.tv_sec < 0) timespecclear(&rmt); error = copyout((void *)&rmt, (void *)SCARG(uap,rmtp), sizeof(rmt)); } return error; } /* ARGSUSED */ int sys_gettimeofday(struct proc *p, void *v, register_t *retval) { struct sys_gettimeofday_args /* { syscallarg(struct timeval *) tp; syscallarg(struct timezone *) tzp; } */ *uap = v; struct timeval atv; int error = 0; if (SCARG(uap, tp)) { microtime(&atv); if ((error = copyout((void *)&atv, (void *)SCARG(uap, tp), sizeof (atv)))) return (error); } if (SCARG(uap, tzp)) error = copyout((void *)&tz, (void *)SCARG(uap, tzp), sizeof (tz)); return (error); } /* ARGSUSED */ int sys_settimeofday(struct proc *p, void *v, register_t *retval) { struct sys_settimeofday_args /* { syscallarg(const struct timeval *) tv; syscallarg(const struct timezone *) tzp; } */ *uap = v; struct timezone atz; struct timeval atv; int error; if ((error = suser(p, 0))) return (error); /* Verify all parameters before changing time. */ if (SCARG(uap, tv) && (error = copyin((void *)SCARG(uap, tv), (void *)&atv, sizeof(atv)))) return (error); if (SCARG(uap, tzp) && (error = copyin((void *)SCARG(uap, tzp), (void *)&atz, sizeof(atz)))) return (error); if (SCARG(uap, tv)) { struct timespec ts; TIMEVAL_TO_TIMESPEC(&atv, &ts); if ((error = settime(&ts)) != 0) return (error); } if (SCARG(uap, tzp)) tz = atz; return (0); } #ifdef __HAVE_TIMECOUNTER struct timeval adjtimedelta; /* unapplied time correction */ #else int tickdelta; /* current clock skew, us. per tick */ long timedelta; /* unapplied time correction, us. */ long bigadj = 1000000; /* use 10x skew above bigadj us. */ #endif /* ARGSUSED */ int sys_adjtime(struct proc *p, void *v, register_t *retval) { struct sys_adjtime_args /* { syscallarg(const struct timeval *) delta; syscallarg(struct timeval *) olddelta; } */ *uap = v; #ifdef __HAVE_TIMECOUNTER int error; if ((error = suser(p, 0))) return (error); if (SCARG(uap, olddelta)) if ((error = copyout((void *)&adjtimedelta, (void *)SCARG(uap, olddelta), sizeof(struct timeval)))) return (error); if ((error = copyin((void *)SCARG(uap, delta), (void *)&adjtimedelta, sizeof(struct timeval)))) return (error); return (0); #else struct timeval atv; long ndelta, ntickdelta, odelta; int s, error; if ((error = suser(p, 0))) return (error); if ((error = copyin((void *)SCARG(uap, delta), (void *)&atv, sizeof(struct timeval)))) return (error); /* * Compute the total correction and the rate at which to apply it. * Round the adjustment down to a whole multiple of the per-tick * delta, so that after some number of incremental changes in * hardclock(), tickdelta will become zero, lest the correction * overshoot and start taking us away from the desired final time. */ if (atv.tv_sec > LONG_MAX / 1000000L) ndelta = LONG_MAX; else if (atv.tv_sec < LONG_MIN / 1000000L) ndelta = LONG_MIN; else { ndelta = atv.tv_sec * 1000000L; odelta = ndelta; ndelta += atv.tv_usec; if (atv.tv_usec > 0 && ndelta <= odelta) ndelta = LONG_MAX; else if (atv.tv_usec < 0 && ndelta >= odelta) ndelta = LONG_MIN; } if (ndelta > bigadj || ndelta < -bigadj) ntickdelta = 10 * tickadj; else ntickdelta = tickadj; if (ndelta % ntickdelta) ndelta = ndelta / ntickdelta * ntickdelta; /* * To make hardclock()'s job easier, make the per-tick delta negative * if we want time to run slower; then hardclock can simply compute * tick + tickdelta, and subtract tickdelta from timedelta. */ if (ndelta < 0) ntickdelta = -ntickdelta; s = splclock(); odelta = timedelta; timedelta = ndelta; tickdelta = ntickdelta; splx(s); if (SCARG(uap, olddelta)) { atv.tv_sec = odelta / 1000000; atv.tv_usec = odelta % 1000000; if ((error = copyout((void *)&atv, (void *)SCARG(uap, olddelta), sizeof(struct timeval)))) return (error); } return (0); #endif } /* * Get value of an interval timer. The process virtual and * profiling virtual time timers are kept in the p_stats area, since * they can be swapped out. These are kept internally in the * way they are specified externally: in time until they expire. * * The real time interval timer is kept in the process table slot * for the process, and its value (it_value) is kept as an * absolute time rather than as a delta, so that it is easy to keep * periodic real-time signals from drifting. * * Virtual time timers are processed in the hardclock() routine of * kern_clock.c. The real time timer is processed by a timeout * routine, called from the softclock() routine. Since a callout * may be delayed in real time due to interrupt processing in the system, * it is possible for the real time timeout routine (realitexpire, given below), * to be delayed in real time past when it is supposed to occur. It * does not suffice, therefore, to reload the real timer .it_value from the * real time timers .it_interval. Rather, we compute the next time in * absolute time the timer should go off. */ /* ARGSUSED */ int sys_getitimer(struct proc *p, void *v, register_t *retval) { struct sys_getitimer_args /* { syscallarg(int) which; syscallarg(struct itimerval *) itv; } */ *uap = v; struct itimerval aitv; int s; if (SCARG(uap, which) < ITIMER_REAL || SCARG(uap, which) > ITIMER_PROF) return (EINVAL); s = splclock(); if (SCARG(uap, which) == ITIMER_REAL) { struct timeval now; getmicrotime(&now); /* * Convert from absolute to relative time in .it_value * part of real time timer. If time for real time timer * has passed return 0, else return difference between * current time and time for the timer to go off. */ aitv = p->p_realtimer; if (timerisset(&aitv.it_value)) { if (timercmp(&aitv.it_value, &now, <)) timerclear(&aitv.it_value); else timersub(&aitv.it_value, &now, &aitv.it_value); } } else aitv = p->p_stats->p_timer[SCARG(uap, which)]; splx(s); return (copyout((void *)&aitv, (void *)SCARG(uap, itv), sizeof (struct itimerval))); } /* ARGSUSED */ int sys_setitimer(struct proc *p, void *v, register_t *retval) { struct sys_setitimer_args /* { syscallarg(int) which; syscallarg(const struct itimerval *) itv; syscallarg(struct itimerval *) oitv; } */ *uap = v; struct sys_getitimer_args getargs; struct itimerval aitv; const struct itimerval *itvp; int error; int timo; if (SCARG(uap, which) < ITIMER_REAL || SCARG(uap, which) > ITIMER_PROF) return (EINVAL); itvp = SCARG(uap, itv); if (itvp && (error = copyin((void *)itvp, (void *)&aitv, sizeof(struct itimerval)))) return (error); if (SCARG(uap, oitv) != NULL) { SCARG(&getargs, which) = SCARG(uap, which); SCARG(&getargs, itv) = SCARG(uap, oitv); if ((error = sys_getitimer(p, &getargs, retval))) return (error); } if (itvp == 0) return (0); if (itimerfix(&aitv.it_value) || itimerfix(&aitv.it_interval)) return (EINVAL); if (SCARG(uap, which) == ITIMER_REAL) { struct timeval ctv; timeout_del(&p->p_realit_to); getmicrouptime(&ctv); if (timerisset(&aitv.it_value)) { timo = tvtohz(&aitv.it_value); timeout_add(&p->p_realit_to, timo); timeradd(&aitv.it_value, &ctv, &aitv.it_value); } p->p_realtimer = aitv; } else { int s; itimerround(&aitv.it_interval); s = splclock(); p->p_stats->p_timer[SCARG(uap, which)] = aitv; splx(s); } return (0); } /* * Real interval timer expired: * send process whose timer expired an alarm signal. * If time is not set up to reload, then just return. * Else compute next time timer should go off which is > current time. * This is where delay in processing this timeout causes multiple * SIGALRM calls to be compressed into one. */ void realitexpire(void *arg) { struct proc *p; p = (struct proc *)arg; psignal(p, SIGALRM); if (!timerisset(&p->p_realtimer.it_interval)) { timerclear(&p->p_realtimer.it_value); return; } for (;;) { struct timeval ctv, ntv; int timo; timeradd(&p->p_realtimer.it_value, &p->p_realtimer.it_interval, &p->p_realtimer.it_value); getmicrouptime(&ctv); if (timercmp(&p->p_realtimer.it_value, &ctv, >)) { ntv = p->p_realtimer.it_value; timersub(&ntv, &ctv, &ntv); timo = tvtohz(&ntv) - 1; if (timo <= 0) timo = 1; if ((p->p_flag & P_WEXIT) == 0) timeout_add(&p->p_realit_to, timo); return; } } } /* * Check that a proposed value to load into the .it_value or * .it_interval part of an interval timer is acceptable. */ int itimerfix(struct timeval *tv) { if (tv->tv_sec < 0 || tv->tv_sec > 100000000 || tv->tv_usec < 0 || tv->tv_usec >= 1000000) return (EINVAL); if (tv->tv_sec == 0 && tv->tv_usec != 0 && tv->tv_usec < tick) tv->tv_usec = tick; return (0); } /* * Timer interval smaller than the resolution of the system clock are * rounded up. */ void itimerround(struct timeval *tv) { if (tv->tv_sec == 0 && tv->tv_usec < tick) tv->tv_usec = tick; } /* * Decrement an interval timer by a specified number * of microseconds, which must be less than a second, * i.e. < 1000000. If the timer expires, then reload * it. In this case, carry over (usec - old value) to * reduce the value reloaded into the timer so that * the timer does not drift. This routine assumes * that it is called in a context where the timers * on which it is operating cannot change in value. */ int itimerdecr(struct itimerval *itp, int usec) { if (itp->it_value.tv_usec < usec) { if (itp->it_value.tv_sec == 0) { /* expired, and already in next interval */ usec -= itp->it_value.tv_usec; goto expire; } itp->it_value.tv_usec += 1000000; itp->it_value.tv_sec--; } itp->it_value.tv_usec -= usec; usec = 0; if (timerisset(&itp->it_value)) return (1); /* expired, exactly at end of interval */ expire: if (timerisset(&itp->it_interval)) { itp->it_value = itp->it_interval; itp->it_value.tv_usec -= usec; if (itp->it_value.tv_usec < 0) { itp->it_value.tv_usec += 1000000; itp->it_value.tv_sec--; } } else itp->it_value.tv_usec = 0; /* sec is already 0 */ return (0); } /* * ratecheck(): simple time-based rate-limit checking. see ratecheck(9) * for usage and rationale. */ int ratecheck(struct timeval *lasttime, const struct timeval *mininterval) { struct timeval tv, delta; int rv = 0; microuptime(&tv); timersub(&tv, lasttime, &delta); /* * check for 0,0 is so that the message will be seen at least once, * even if interval is huge. */ if (timercmp(&delta, mininterval, >=) || (lasttime->tv_sec == 0 && lasttime->tv_usec == 0)) { *lasttime = tv; rv = 1; } return (rv); } /* * ppsratecheck(): packets (or events) per second limitation. */ int ppsratecheck(struct timeval *lasttime, int *curpps, int maxpps) { struct timeval tv, delta; int rv; microuptime(&tv); timersub(&tv, lasttime, &delta); /* * check for 0,0 is so that the message will be seen at least once. * if more than one second have passed since the last update of * lasttime, reset the counter. * * we do increment *curpps even in *curpps < maxpps case, as some may * try to use *curpps for stat purposes as well. */ if (maxpps == 0) rv = 0; else if ((lasttime->tv_sec == 0 && lasttime->tv_usec == 0) || delta.tv_sec >= 1) { *lasttime = tv; *curpps = 0; rv = 1; } else if (maxpps < 0) rv = 1; else if (*curpps < maxpps) rv = 1; else rv = 0; #if 1 /*DIAGNOSTIC?*/ /* be careful about wrap-around */ if (*curpps + 1 > *curpps) *curpps = *curpps + 1; #else /* * assume that there's not too many calls to this function. * not sure if the assumption holds, as it depends on *caller's* * behavior, not the behavior of this function. * IMHO it is wrong to make assumption on the caller's behavior, * so the above #if is #if 1, not #ifdef DIAGNOSTIC. */ *curpps = *curpps + 1; #endif return (rv); }