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>

diff --git a/include/linux/timex.h b/include/linux/timex.h
index fc6035d..c00bcdd 100644 (file)
--- a/include/linux/timex.h
+++ b/include/linux/timex.h
@@ -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

diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index 5125ddd..c6921aa 100644 (file)
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -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);