linux-kernel - Re: [RFC PATCH ghak10 v6 2/2] ntp: Audit NTP parameters adjustment

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Message-ID: <CALAqxLVbOY+nBREEAciNUPqCZBYBhD_yw1QyoVP5eZfDHV1hTw@mail.gmail.com>
Date:   Wed, 27 Mar 2019 16:29:43 -0700
From:   John Stultz <john.stultz@...aro.org>
To:     Ondrej Mosnacek <omosnace@...hat.com>
Cc:     linux-audit@...hat.com, Paul Moore <paul@...l-moore.com>,
        Richard Guy Briggs <rgb@...hat.com>,
        Steve Grubb <sgrubb@...hat.com>,
        Miroslav Lichvar <mlichvar@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Stephen Boyd <sboyd@...nel.org>,
        lkml <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH ghak10 v6 2/2] ntp: Audit NTP parameters adjustment

On Thu, Mar 7, 2019 at 4:33 AM Ondrej Mosnacek <omosnace@...hat.com> wrote:
>
> Emit an audit record every time selected NTP parameters are modified
> from userspace (via adjtimex(2) or clock_adjtime(2)).
>
> 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
>
> For reference, running the following commands:
>
>     auditctl -D
>     auditctl -a exit,always -F arch=b64 -S adjtimex
>     chronyd -q
>
> produces audit records like this:
>
> type=SYSCALL msg=audit(1530616044.507:5): arch=c000003e syscall=159 success=yes exit=5 a0=7fff57e78c00 a1=0 a2=4 a3=7f754ae28c0a items=0 ppid=626 pid=629 auid=0 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=(none) ses=1 comm="chronyd" exe="/usr/sbin/chronyd" subj=system_u:system_r:kernel_t:s0 key=(null)
> type=PROCTITLE msg=audit(1530616044.507:5): proctitle=6368726F6E7964002D71
> type=SYSCALL msg=audit(1530616044.507:6): arch=c000003e syscall=159 success=yes exit=5 a0=7fff57e78c00 a1=1 a2=1 a3=7f754ae28c0a items=0 ppid=626 pid=629 auid=0 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=(none) ses=1 comm="chronyd" exe="/usr/sbin/chronyd" subj=system_u:system_r:kernel_t:s0 key=(null)
> type=PROCTITLE msg=audit(1530616044.507:6): proctitle=6368726F6E7964002D71
> type=TIME_ADJNTPVAL msg=audit(1530616044.507:7): op=status old=64 new=8256
> type=SYSCALL msg=audit(1530616044.507:7): arch=c000003e syscall=159 success=yes exit=5 a0=7fff57e78c00 a1=1 a2=1 a3=7f754ae28c0a items=0 ppid=626 pid=629 auid=0 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=(none) ses=1 comm="chronyd" exe="/usr/sbin/chronyd" subj=system_u:system_r:kernel_t:s0 key=(null)
> type=PROCTITLE msg=audit(1530616044.507:7): proctitle=6368726F6E7964002D71
> type=TIME_ADJNTPVAL msg=audit(1530616044.507:8): op=status old=8256 new=8257
> type=SYSCALL msg=audit(1530616044.507:8): arch=c000003e syscall=159 success=yes exit=5 a0=7fff57e78ab0 a1=0 a2=55e129c850c0 a3=7f754ae28c0a items=0 ppid=626 pid=629 auid=0 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=(none) ses=1 comm="chronyd" exe="/usr/sbin/chronyd" subj=system_u:system_r:kernel_t:s0 key=(null)
> type=PROCTITLE msg=audit(1530616044.507:8): proctitle=6368726F6E7964002D71
> type=TIME_ADJNTPVAL msg=audit(1530616044.507:9): op=status old=8257 new=64
> type=SYSCALL msg=audit(1530616044.507:9): arch=c000003e syscall=159 success=yes exit=5 a0=7fff57e78ab0 a1=0 a2=55e129c850c0 a3=7f754ae28c0a items=0 ppid=626 pid=629 auid=0 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=(none) ses=1 comm="chronyd" exe="/usr/sbin/chronyd" subj=system_u:system_r:kernel_t:s0 key=(null)
> type=PROCTITLE msg=audit(1530616044.507:9): proctitle=6368726F6E7964002D71
> type=SYSCALL msg=audit(1530616044.507:10): arch=c000003e syscall=159 success=yes exit=5 a0=7fff57e78a70 a1=0 a2=55e129c850c0 a3=7f754ae28c0a items=0 ppid=626 pid=629 auid=0 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=(none) ses=1 comm="chronyd" exe="/usr/sbin/chronyd" subj=system_u:system_r:kernel_t:s0 key=(null)
> type=PROCTITLE msg=audit(1530616044.507:10): proctitle=6368726F6E7964002D71
> type=TIME_ADJNTPVAL msg=audit(1530616044.511:11): op=freq old=0 new=49180377088000
> type=SYSCALL msg=audit(1530616044.511:11): arch=c000003e syscall=159 success=yes exit=5 a0=7fff57e78ad0 a1=0 a2=2710 a3=f42f82a800000 items=0 ppid=626 pid=629 auid=0 uid=385 gid=382 euid=385 suid=385 fsuid=385 egid=382 sgid=382 fsgid=382 tty=(none) ses=1 comm="chronyd" exe="/usr/sbin/chronyd" subj=system_u:system_r:kernel_t:s0 key=(null)
> type=PROCTITLE msg=audit(1530616044.511:11): proctitle=6368726F6E7964002D71
> type=SYSCALL msg=audit(1530616044.521:12): arch=c000003e syscall=159 success=yes exit=5 a0=7fff57e78b40 a1=1 a2=40 a3=f91f6ef84fbab items=0 ppid=626 pid=629 auid=0 uid=385 gid=382 euid=385 suid=385 fsuid=385 egid=382 sgid=382 fsgid=382 tty=(none) ses=1 comm="chronyd" exe="/usr/sbin/chronyd" subj=system_u:system_r:kernel_t:s0 key=(null)
> type=PROCTITLE msg=audit(1530616044.521:12): proctitle=6368726F6E7964002D71
> type=TIME_ADJNTPVAL msg=audit(1530616049.652:13): op=status old=64 new=8256
> type=SYSCALL msg=audit(1530616049.652:13): arch=c000003e syscall=159 success=yes exit=5 a0=7fff57e78270 a1=1 a2=fffffffffffffff0 a3=137b828205ca12 items=0 ppid=626 pid=629 auid=0 uid=385 gid=382 euid=385 suid=385 fsuid=385 egid=382 sgid=382 fsgid=382 tty=(none) ses=1 comm="chronyd" exe="/usr/sbin/chronyd" subj=system_u:system_r:kernel_t:s0 key=(null)
> type=PROCTITLE msg=audit(1530616049.652:13): proctitle=6368726F6E7964002D71
> type=SYSCALL msg=audit(1530616033.783:14): arch=c000003e syscall=159 success=yes exit=5 a0=7fff57e78bc0 a1=0 a2=2710 a3=0 items=0 ppid=626 pid=629 auid=0 uid=385 gid=382 euid=385 suid=385 fsuid=385 egid=382 sgid=382 fsgid=382 tty=(none) ses=1 comm="chronyd" exe="/usr/sbin/chronyd" subj=system_u:system_r:kernel_t:s0 key=(null)
> type=PROCTITLE msg=audit(1530616033.783:14): proctitle=6368726F6E7964002D71
>
> The chronyd command that produced the above records executed the
> following adjtimex(2) syscalls (as per strace output):
>
> adjtimex({modes=ADJ_OFFSET|0x8000, offset=0, freq=0, maxerror=16000000, esterror=16000000, status=STA_UNSYNC, constant=2, precision=1, tolerance=32768000, time={tv_sec=1530616044, tv_usec=507215}, tick=10000, ppsfreq=0, jitter=0, shift=0, stabil=0, jitcnt=0, calcnt=0, errcnt=0, stbcnt=0, tai=0}) = 5 (TIME_ERROR)
> adjtimex({modes=ADJ_MAXERROR, offset=0, freq=0, maxerror=0, esterror=16000000, status=STA_UNSYNC, constant=2, precision=1, tolerance=32768000, time={tv_sec=1530616044, tv_usec=507438}, tick=10000, ppsfreq=0, jitter=0, shift=0, stabil=0, jitcnt=0, calcnt=0, errcnt=0, stbcnt=0, tai=0}) = 5 (TIME_ERROR)
> adjtimex({modes=ADJ_SETOFFSET|ADJ_NANO, offset=0, freq=0, maxerror=16000000, esterror=16000000, status=STA_UNSYNC|STA_NANO, constant=2, precision=1, tolerance=32768000, time={tv_sec=1530616044, tv_usec=507604737}, tick=10000, ppsfreq=0, jitter=0, shift=0, stabil=0, jitcnt=0, calcnt=0, errcnt=0, stbcnt=0, tai=0}) = 5 (TIME_ERROR)
> adjtimex({modes=ADJ_OFFSET|ADJ_STATUS, offset=0, freq=0, maxerror=16000000, esterror=16000000, status=STA_PLL|STA_UNSYNC|STA_NANO, constant=2, precision=1, tolerance=32768000, time={tv_sec=1530616044, tv_usec=507698330}, tick=10000, ppsfreq=0, jitter=0, shift=0, stabil=0, jitcnt=0, calcnt=0, errcnt=0, stbcnt=0, tai=0}) = 5 (TIME_ERROR)
> adjtimex({modes=ADJ_STATUS, offset=0, freq=0, maxerror=16000000, esterror=16000000, status=STA_UNSYNC, constant=2, precision=1, tolerance=32768000, time={tv_sec=1530616044, tv_usec=507792}, tick=10000, ppsfreq=0, jitter=0, shift=0, stabil=0, jitcnt=0, calcnt=0, errcnt=0, stbcnt=0, tai=0}) = 5 (TIME_ERROR)
> adjtimex({modes=0, offset=0, freq=0, maxerror=16000000, esterror=16000000, status=STA_UNSYNC, constant=2, precision=1, tolerance=32768000, time={tv_sec=1530616044, tv_usec=508000}, tick=10000, ppsfreq=0, jitter=0, shift=0, stabil=0, jitcnt=0, calcnt=0, errcnt=0, stbcnt=0, tai=0}) = 5 (TIME_ERROR)
> adjtimex({modes=ADJ_FREQUENCY|ADJ_TICK, offset=0, freq=750433, maxerror=16000000, esterror=16000000, status=STA_UNSYNC, constant=2, precision=1, tolerance=32768000, time={tv_sec=1530616044, tv_usec=512146}, tick=10000, ppsfreq=0, jitter=0, shift=0, stabil=0, jitcnt=0, calcnt=0, errcnt=0, stbcnt=0, tai=0}) = 5 (TIME_ERROR)
> adjtimex({modes=ADJ_MAXERROR|ADJ_ESTERROR|ADJ_STATUS, offset=0, freq=750433, maxerror=16000000, esterror=16000000, status=STA_UNSYNC, constant=2, precision=1, tolerance=32768000, time={tv_sec=1530616044, tv_usec=522506}, tick=10000, ppsfreq=0, jitter=0, shift=0, stabil=0, jitcnt=0, calcnt=0, errcnt=0, stbcnt=0, tai=0}) = 5 (TIME_ERROR)
> adjtimex({modes=ADJ_SETOFFSET|ADJ_NANO, offset=0, freq=750433, maxerror=16000000, esterror=16000000, status=STA_UNSYNC|STA_NANO, constant=2, precision=1, tolerance=32768000, time={tv_sec=1530616033, tv_usec=778717675}, tick=10000, ppsfreq=0, jitter=0, shift=0, stabil=0, jitcnt=0, calcnt=0, errcnt=0, stbcnt=0, tai=0}) = 5 (TIME_ERROR)
> adjtimex({modes=ADJ_FREQUENCY|ADJ_TICK, offset=0, freq=750433, maxerror=16000000, esterror=16000000, status=STA_UNSYNC|STA_NANO, constant=2, precision=1, tolerance=32768000, time={tv_sec=1530616033, tv_usec=784644657}, tick=10000, ppsfreq=0, jitter=0, shift=0, stabil=0, jitcnt=0, calcnt=0, errcnt=0, stbcnt=0, tai=0}) = 5 (TIME_ERROR)
>
> (The struct timex fields above are from *after* the syscall was
> executed, so they contain the current (new) values as set from the
> kernel, except of the 'modes' field, which contains the original value
> sent by the caller.)
>
> The changes to the time_maxerror, time_esterror, and time_constant
> variables are not logged, as these are not important for security. Also,
> no-op adjustments that do not actually change the value are not logged.
>
> 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%
>     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>

Again, lightly looked over, and I don't see anything to object to.

Acked-by: John Stultz <john.stultz@...aro.org>