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authorOndrej Mosnacek <omosnace@redhat.com>2019-04-10 11:14:20 +0200
committerPaul Moore <paul@paul-moore.com>2019-04-15 18:14:01 -0400
commit7e8eda734d30de81d06a949c9bf9853c445ede4e (patch)
treed16d77f902e5e7bc24ce1afcb0589544d5e5e602 /kernel/time
parent2d87a0674bd60d855e4008e2d84f5b23d7cb9b7d (diff)
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ntp: Audit NTP parameters adjustment
Emit an audit record every time selected NTP parameters are modified from userspace (via adjtimex(2) or clock_adjtime(2)). These parameters may be used to indirectly change system clock, and thus their modifications should be audited. Such events will now generate records of type AUDIT_TIME_ADJNTPVAL containing the following fields: - op -- which value was adjusted: - offset -- corresponding to the time_offset variable - freq -- corresponding to the time_freq variable - status -- corresponding to the time_status variable - adjust -- corresponding to the time_adjust variable - tick -- corresponding to the tick_usec variable - tai -- corresponding to the timekeeping's TAI offset - old -- the old value - new -- the new value Example records: type=TIME_ADJNTPVAL msg=audit(1530616044.507:7): op=status old=64 new=8256 type=TIME_ADJNTPVAL msg=audit(1530616044.511:11): op=freq old=0 new=49180377088000 The records of this type will be associated with the corresponding syscall records. An overview of parameter changes that can be done via do_adjtimex() (based on information from Miroslav Lichvar) and whether they are audited: __timekeeping_set_tai_offset() -- sets the offset from the International Atomic Time (AUDITED) NTP variables: time_offset -- can adjust the clock by up to 0.5 seconds per call and also speed it up or slow down by up to about 0.05% (43 seconds per day) (AUDITED) time_freq -- can speed up or slow down by up to about 0.05% (AUDITED) time_status -- can insert/delete leap seconds and it also enables/ disables synchronization of the hardware real-time clock (AUDITED) time_maxerror, time_esterror -- change error estimates used to inform userspace applications (NOT AUDITED) time_constant -- controls the speed of the clock adjustments that are made when time_offset is set (NOT AUDITED) time_adjust -- can temporarily speed up or slow down the clock by up to 0.05% (AUDITED) tick_usec -- a more extreme version of time_freq; can speed up or slow down the clock by up to 10% (AUDITED) Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com> Reviewed-by: Richard Guy Briggs <rgb@redhat.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Paul Moore <paul@paul-moore.com>
Diffstat (limited to 'kernel/time')
-rw-r--r--kernel/time/ntp.c22
-rw-r--r--kernel/time/ntp_internal.h4
-rw-r--r--kernel/time/timekeeping.c7
3 files changed, 28 insertions, 5 deletions
diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index 92a90014a925..ac5555e25733 100644
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -17,6 +17,7 @@
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/rtc.h>
+#include <linux/audit.h>
#include "ntp_internal.h"
#include "timekeeping_internal.h"
@@ -709,7 +710,7 @@ static inline void process_adjtimex_modes(const struct __kernel_timex *txc,
* kernel time-keeping variables. used by xntpd.
*/
int __do_adjtimex(struct __kernel_timex *txc, const struct timespec64 *ts,
- s32 *time_tai)
+ s32 *time_tai, struct audit_ntp_data *ad)
{
int result;
@@ -720,14 +721,29 @@ int __do_adjtimex(struct __kernel_timex *txc, const struct timespec64 *ts,
/* adjtime() is independent from ntp_adjtime() */
time_adjust = txc->offset;
ntp_update_frequency();
+
+ audit_ntp_set_old(ad, AUDIT_NTP_ADJUST, save_adjust);
+ audit_ntp_set_new(ad, AUDIT_NTP_ADJUST, time_adjust);
}
txc->offset = save_adjust;
} else {
-
/* If there are input parameters, then process them: */
- if (txc->modes)
+ if (txc->modes) {
+ audit_ntp_set_old(ad, AUDIT_NTP_OFFSET, time_offset);
+ audit_ntp_set_old(ad, AUDIT_NTP_FREQ, time_freq);
+ audit_ntp_set_old(ad, AUDIT_NTP_STATUS, time_status);
+ audit_ntp_set_old(ad, AUDIT_NTP_TAI, *time_tai);
+ audit_ntp_set_old(ad, AUDIT_NTP_TICK, tick_usec);
+
process_adjtimex_modes(txc, time_tai);
+ audit_ntp_set_new(ad, AUDIT_NTP_OFFSET, time_offset);
+ audit_ntp_set_new(ad, AUDIT_NTP_FREQ, time_freq);
+ audit_ntp_set_new(ad, AUDIT_NTP_STATUS, time_status);
+ audit_ntp_set_new(ad, AUDIT_NTP_TAI, *time_tai);
+ audit_ntp_set_new(ad, AUDIT_NTP_TICK, tick_usec);
+ }
+
txc->offset = shift_right(time_offset * NTP_INTERVAL_FREQ,
NTP_SCALE_SHIFT);
if (!(time_status & STA_NANO))
diff --git a/kernel/time/ntp_internal.h b/kernel/time/ntp_internal.h
index 40e6122e634e..908ecaa65fc3 100644
--- a/kernel/time/ntp_internal.h
+++ b/kernel/time/ntp_internal.h
@@ -8,6 +8,8 @@ extern void ntp_clear(void);
extern u64 ntp_tick_length(void);
extern ktime_t ntp_get_next_leap(void);
extern int second_overflow(time64_t secs);
-extern int __do_adjtimex(struct __kernel_timex *txc, const struct timespec64 *ts, s32 *time_tai);
+extern int __do_adjtimex(struct __kernel_timex *txc,
+ const struct timespec64 *ts,
+ s32 *time_tai, struct audit_ntp_data *ad);
extern void __hardpps(const struct timespec64 *phase_ts, const struct timespec64 *raw_ts);
#endif /* _LINUX_NTP_INTERNAL_H */
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 3d24be4cd607..f366f2fdf1b0 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -2307,6 +2307,7 @@ static int timekeeping_validate_timex(const struct __kernel_timex *txc)
int do_adjtimex(struct __kernel_timex *txc)
{
struct timekeeper *tk = &tk_core.timekeeper;
+ struct audit_ntp_data ad;
unsigned long flags;
struct timespec64 ts;
s32 orig_tai, tai;
@@ -2330,13 +2331,15 @@ int do_adjtimex(struct __kernel_timex *txc)
audit_tk_injoffset(delta);
}
+ audit_ntp_init(&ad);
+
ktime_get_real_ts64(&ts);
raw_spin_lock_irqsave(&timekeeper_lock, flags);
write_seqcount_begin(&tk_core.seq);
orig_tai = tai = tk->tai_offset;
- ret = __do_adjtimex(txc, &ts, &tai);
+ ret = __do_adjtimex(txc, &ts, &tai, &ad);
if (tai != orig_tai) {
__timekeeping_set_tai_offset(tk, tai);
@@ -2347,6 +2350,8 @@ int do_adjtimex(struct __kernel_timex *txc)
write_seqcount_end(&tk_core.seq);
raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
+ audit_ntp_log(&ad);
+
/* Update the multiplier immediately if frequency was set directly */
if (txc->modes & (ADJ_FREQUENCY | ADJ_TICK))
timekeeping_advance(TK_ADV_FREQ);