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author | Ondrej Mosnacek <omosnace@redhat.com> | 2019-04-10 12:14:20 +0300 |
---|---|---|
committer | Paul Moore <paul@paul-moore.com> | 2019-04-16 01:14:01 +0300 |
commit | 7e8eda734d30de81d06a949c9bf9853c445ede4e (patch) | |
tree | d16d77f902e5e7bc24ce1afcb0589544d5e5e602 /kernel | |
parent | 2d87a0674bd60d855e4008e2d84f5b23d7cb9b7d (diff) | |
download | linux-7e8eda734d30de81d06a949c9bf9853c445ede4e.tar.xz |
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')
-rw-r--r-- | kernel/auditsc.c | 22 | ||||
-rw-r--r-- | kernel/time/ntp.c | 22 | ||||
-rw-r--r-- | kernel/time/ntp_internal.h | 4 | ||||
-rw-r--r-- | kernel/time/timekeeping.c | 7 |
4 files changed, 50 insertions, 5 deletions
diff --git a/kernel/auditsc.c b/kernel/auditsc.c index 3843495d0083..5371b59bde36 100644 --- a/kernel/auditsc.c +++ b/kernel/auditsc.c @@ -2519,6 +2519,28 @@ void __audit_tk_injoffset(struct timespec64 offset) (long long)offset.tv_sec, offset.tv_nsec); } +static void audit_log_ntp_val(const struct audit_ntp_data *ad, + const char *op, enum audit_ntp_type type) +{ + const struct audit_ntp_val *val = &ad->vals[type]; + + if (val->newval == val->oldval) + return; + + audit_log(audit_context(), GFP_KERNEL, AUDIT_TIME_ADJNTPVAL, + "op=%s old=%lli new=%lli", op, val->oldval, val->newval); +} + +void __audit_ntp_log(const struct audit_ntp_data *ad) +{ + audit_log_ntp_val(ad, "offset", AUDIT_NTP_OFFSET); + audit_log_ntp_val(ad, "freq", AUDIT_NTP_FREQ); + audit_log_ntp_val(ad, "status", AUDIT_NTP_STATUS); + audit_log_ntp_val(ad, "tai", AUDIT_NTP_TAI); + audit_log_ntp_val(ad, "tick", AUDIT_NTP_TICK); + audit_log_ntp_val(ad, "adjust", AUDIT_NTP_ADJUST); +} + static void audit_log_task(struct audit_buffer *ab) { kuid_t auid, uid; 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); |