Re: [PATCH ghak10 v7 2/2] ntp: Audit NTP parameters adjustment

On 2019-04-09 14:31, Ondrej Mosnacek wrote: > 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% (I think you want an "(AUDITED)" at the end of the "time_freq" line.)

> 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(a)redhat.com&gt; Reviewed-by: Richard Guy Briggs <rgb(a)redhat.com&gt; > --- > include/linux/audit.h | 54 ++++++++++++++++++++++++++++++++++++++ > include/uapi/linux/audit.h | 1 + > kernel/auditsc.c | 23 ++++++++++++++++ > kernel/time/ntp.c | 22 +++++++++++++--- > kernel/time/ntp_internal.h | 4 ++- > kernel/time/timekeeping.c | 7 ++++- > 6 files changed, 106 insertions(+), 5 deletions(-) > > diff --git a/include/linux/audit.h b/include/linux/audit.h > index 2c62c0468888..1c372ad7ebe9 100644 > --- a/include/linux/audit.h > +++ b/include/linux/audit.h > @@ -86,6 +86,26 @@ struct audit_field { > u32 op; > }; > > +#define AUDIT_NTP_OFFSET 0 > +#define AUDIT_NTP_FREQ 1 > +#define AUDIT_NTP_STATUS 2 > +#define AUDIT_NTP_TAI 3 > +#define AUDIT_NTP_TICK 4 > +#define AUDIT_NTP_ADJUST 5 > +#define AUDIT_NTP_NVALS 6 /* count */ > + > +#ifdef CONFIG_AUDITSYSCALL > +struct audit_ntp_val { > + s64 oldval, newval; > +}; > + > +struct audit_ntp_data { > + struct audit_ntp_val vals[AUDIT_NTP_NVALS]; > +}; > +#else > +struct audit_ntp_data {}; > +#endif > + > extern int is_audit_feature_set(int which); > > extern int __init audit_register_class(int class, unsigned *list); > @@ -366,6 +386,7 @@ extern void __audit_mmap_fd(int fd, int flags); > extern void __audit_log_kern_module(char *name); > extern void __audit_fanotify(unsigned int response); > extern void __audit_tk_injoffset(struct timespec64 offset); > +extern void __audit_ntp_log(const struct audit_ntp_data *ad); > > static inline void audit_ipc_obj(struct kern_ipc_perm *ipcp) > { > @@ -478,6 +499,27 @@ static inline void audit_tk_injoffset(struct timespec64 offset) > __audit_tk_injoffset(offset); > } > > +static inline void audit_ntp_init(struct audit_ntp_data *ad) > +{ > + memset(ad, 0, sizeof(*ad)); > +} > + > +static inline void audit_ntp_set_old(struct audit_ntp_data *ad, int id, s64 val) > +{ > + ad->vals[id].oldval = val; > +} > + > +static inline void audit_ntp_set_new(struct audit_ntp_data *ad, int id, s64 val) > +{ > + ad->vals[id].newval = val; > +} > + > +static inline void audit_ntp_log(const struct audit_ntp_data *ad) > +{ > + if (!audit_dummy_context()) > + __audit_ntp_log(ad); > +} > + > extern int audit_n_rules; > extern int audit_signals; > #else /* CONFIG_AUDITSYSCALL */ > @@ -594,6 +636,18 @@ static inline void audit_fanotify(unsigned int response) > static inline void audit_tk_injoffset(struct timespec64 offset) > { } > > +static inline void audit_ntp_init(struct audit_ntp_data *ad) > +{ } > + > +static inline void audit_ntp_set_old(struct audit_ntp_data *ad, int id, s64 val) > +{ } > + > +static inline void audit_ntp_set_new(struct audit_ntp_data *ad, int id, s64 val) > +{ } > + > +static inline void audit_ntp_log(const struct audit_ntp_data *ad) > +{ } > + > static inline void audit_ptrace(struct task_struct *t) > { } > #define audit_n_rules 0 > diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h > index ab58d67baf4d..a1280af20336 100644 > --- a/include/uapi/linux/audit.h > +++ b/include/uapi/linux/audit.h > @@ -115,6 +115,7 @@ > #define AUDIT_KERN_MODULE 1330 /* Kernel Module events */ > #define AUDIT_FANOTIFY 1331 /* Fanotify access decision */ > #define AUDIT_TIME_INJOFFSET 1332 /* Timekeeping offset injected */ > +#define AUDIT_TIME_ADJNTPVAL 1333 /* NTP value adjustment */ > > #define AUDIT_AVC 1400 /* SE Linux avc denial or grant */ > #define AUDIT_SELINUX_ERR 1401 /* Internal SE Linux Errors */ > diff --git a/kernel/auditsc.c b/kernel/auditsc.c > index 80dfe0cdc636..519ada7522ad 100644 > --- a/kernel/auditsc.c > +++ b/kernel/auditsc.c > @@ -2518,6 +2518,29 @@ void __audit_tk_injoffset(struct timespec64 offset) > "sec=%lli nsec=%li", (long long)offset.tv_sec, offset.tv_nsec); > } > > +static void audit_log_ntp_val(const struct audit_ntp_data *ad, > + const char *type, int id) > +{ > + const struct audit_ntp_val *val = &ad->vals[id]; > + > + if (val->newval == val->oldval) > + return; > + > + audit_log(audit_context(), GFP_KERNEL, AUDIT_TIME_ADJNTPVAL, > + "op=%s old=%lli new=%lli", type, > + (long long)val->oldval, (long long)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); > -- > 2.20.1 > - RGB -- Richard Guy Briggs <rgb(a)redhat.com&gt; Sr. S/W Engineer, Kernel Security, Base Operating Systems Remote, Ottawa, Red Hat Canada IRC: rgb, SunRaycer Voice: +1.647.777.2635, Internal: (81) 32635