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Message-ID: <20190409144033.pqcvuzllanqfgj7n@madcap2.tricolour.ca>
Date: Tue, 9 Apr 2019 10:40:33 -0400
From: Richard Guy Briggs <rgb@...hat.com>
To: Ondrej Mosnacek <omosnace@...hat.com>
Cc: linux-audit@...hat.com, Paul Moore <paul@...l-moore.com>,
Steve Grubb <sgrubb@...hat.com>,
Miroslav Lichvar <mlichvar@...hat.com>,
John Stultz <john.stultz@...aro.org>,
Thomas Gleixner <tglx@...utronix.de>,
Stephen Boyd <sboyd@...nel.org>, linux-kernel@...r.kernel.org
Subject: 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@...hat.com>
Reviewed-by: Richard Guy Briggs <rgb@...hat.com>
> ---
> 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@...hat.com>
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
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