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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: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Roman Zippel 2008-08-20 16:46:08 -07:00 committed by Ingo Molnar
parent 6a55617ed5
commit 916c7a8551
2 changed files with 48 additions and 37 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
include/linux/timex.h
View File

@ -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 */
#define ADJ_OFFSET_SS_READ 0xa001 /* read-only adjtime */
#endif
/* xntp 3.4 compatibility names */
#define MOD_OFFSET ADJ_OFFSET

76
kernel/time/ntp.c
View File

@ -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;
/* 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) {
/* 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_SS_READ)
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;
/* if the quartz is off by more than 10% something is VERY wrong! */
if (txc->modes & ADJ_TICK &&
(txc->tick < 900000/USER_HZ ||
txc->tick > 1100000/USER_HZ))
return -EINVAL;
if (txc->modes & ADJ_STATUS && time_state != TIME_OK)
hrtimer_cancel(&leap_timer);
}
/* 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)
return -EINVAL;
if (time_state != TIME_OK && txc->modes & ADJ_STATUS)
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
ntp_update_offset(txc->offset);
}
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();
}
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;
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;
}
txc->freq = shift_right((s32)(time_freq >> PPM_SCALE_INV_SHIFT) *
(s64)PPM_SCALE_INV,
NTP_SCALE_SHIFT);