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Commit 916c7a85 authored by Roman Zippel's avatar Roman Zippel Committed by Ingo Molnar
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ntp: fix ADJ_OFFSET_SS_READ bug and do_adjtimex() cleanup 



Thanks to the review by Michael Kerrisk a bug in the recent
ADJ_OFFSET_SS_READ option was discovered, where the ntp time_offset was
inadvertently set by it.  This fixes this by making the adjtime code
more separate from the ntp_adjtime code (both of which really want to
be separate syscalls).

Signed-off-by: default avatarRoman Zippel <zippel@linux-m68k.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Acked-by: default avatarJohn Stultz <johnstul@us.ibm.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 6a55617e

include/linux/timex.h

+8 −1
Original line number Diff line number Diff line
@@ -141,8 +141,15 @@ struct timex { 
#define ADJ_MICRO		0x1000	/* select microsecond resolution */

#define ADJ_NANO		0x2000	/* select nanosecond resolution */

#define ADJ_TICK		0x4000	/* tick value */



#ifdef __KERNEL__

#define ADJ_ADJTIME		0x8000	/* switch between adjtime/adjtimex modes */

#define ADJ_OFFSET_SINGLESHOT	0x0001	/* old-fashioned adjtime */

#define ADJ_OFFSET_READONLY	0x2000	/* read-only adjtime */

#else

#define ADJ_OFFSET_SINGLESHOT	0x8001	/* old-fashioned adjtime */

#define ADJ_OFFSET_SS_READ	0xa001	/* read-only adjtime */

#endif



/* xntp 3.4 compatibility names */

#define MOD_OFFSET	ADJ_OFFSET

kernel/time/ntp.c

+40 −36
Original line number Diff line number Diff line
@@ -277,38 +277,50 @@ static inline void notify_cmos_timer(void) { } 
int do_adjtimex(struct timex *txc)

{

	struct timespec ts;

	long save_adjust, sec;

	int result;



	/* Validate the data before disabling interrupts */

	if (txc->modes & ADJ_ADJTIME) {

		/* singleshot must not be used with any other mode bits */

		if (!(txc->modes & ADJ_OFFSET_SINGLESHOT))

			return -EINVAL;

		if (!(txc->modes & ADJ_OFFSET_READONLY) &&

		    !capable(CAP_SYS_TIME))

			return -EPERM;

	} else {

		/* In order to modify anything, you gotta be super-user! */

		 if (txc->modes && !capable(CAP_SYS_TIME))

			return -EPERM;



	/* Now we validate the data before disabling interrupts */



	if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT) {

		/* singleshot must not be used with any other mode bits */

		if (txc->modes & ~ADJ_OFFSET_SS_READ)

			return -EINVAL;

	}



		/* if the quartz is off by more than 10% something is VERY wrong! */

	if (txc->modes & ADJ_TICK)

		if (txc->tick <  900000/USER_HZ ||

		    txc->tick > 1100000/USER_HZ)

		if (txc->modes & ADJ_TICK &&

		    (txc->tick <  900000/USER_HZ ||

		     txc->tick > 1100000/USER_HZ))

				return -EINVAL;



	if (time_state != TIME_OK && txc->modes & ADJ_STATUS)

		if (txc->modes & ADJ_STATUS && time_state != TIME_OK)

			hrtimer_cancel(&leap_timer);

	}



	getnstimeofday(&ts);



	write_seqlock_irq(&xtime_lock);



	/* Save for later - semantics of adjtime is to return old value */

	save_adjust = time_adjust;



	/* If there are input parameters, then process them */

	if (txc->modes & ADJ_ADJTIME) {

		long save_adjust = time_adjust;



		if (!(txc->modes & ADJ_OFFSET_READONLY)) {

			/* adjtime() is independent from ntp_adjtime() */

			time_adjust = txc->offset;

			ntp_update_frequency();

		}

		txc->offset = save_adjust;

		goto adj_done;

	}

	if (txc->modes) {

		long sec;



		if (txc->modes & ADJ_STATUS) {

			if ((time_status & STA_PLL) &&

			    !(txc->status & STA_PLL)) {
@@ -375,13 +387,8 @@ int do_adjtimex(struct timex *txc) 
		if (txc->modes & ADJ_TAI && txc->constant > 0)

			time_tai = txc->constant;



		if (txc->modes & ADJ_OFFSET) {

			if (txc->modes == ADJ_OFFSET_SINGLESHOT)

				/* adjtime() is independent from ntp_adjtime() */

				time_adjust = txc->offset;

			else

		if (txc->modes & ADJ_OFFSET)

			ntp_update_offset(txc->offset);

		}

		if (txc->modes & ADJ_TICK)

			tick_usec = txc->tick;
@@ -389,19 +396,16 @@ int do_adjtimex(struct timex *txc) 
			ntp_update_frequency();

	}



	result = time_state;	/* mostly `TIME_OK' */

	if (time_status & (STA_UNSYNC|STA_CLOCKERR))

		result = TIME_ERROR;



	if ((txc->modes == ADJ_OFFSET_SINGLESHOT) ||

	    (txc->modes == ADJ_OFFSET_SS_READ))

		txc->offset = save_adjust;

	else {

	txc->offset = shift_right(time_offset * NTP_INTERVAL_FREQ,

				  NTP_SCALE_SHIFT);

	if (!(time_status & STA_NANO))

		txc->offset /= NSEC_PER_USEC;

	}



adj_done:

	result = time_state;	/* mostly `TIME_OK' */

	if (time_status & (STA_UNSYNC|STA_CLOCKERR))

		result = TIME_ERROR;



	txc->freq	   = shift_right((s32)(time_freq >> PPM_SCALE_INV_SHIFT) *

					 (s64)PPM_SCALE_INV,

					 NTP_SCALE_SHIFT);