On Thursday, March 7, 2019 7:32:53 AM EST Ondrej Mosnacek wrote: This is needed for common criteria. Requirements are getting stricter in certifications of IT products that are time stamp sensitive. The record format looks fine to me. Ack for the record format. -Steve unanswerd */

On Thu, Mar 28, 2019 at 12:27 AM John Stultz <john.stultz(a)linaro.org&gt; wrote: Well, __audit_syscall_entry() already logs the timestamp of the syscall entry (this is what ends up also in the TIME_INJOFFSET syscall-associated record as the timestamp, actually), so even though it is not precisely the moment when the change happened, it should be good enough in most cases. I'm not sure if it is worth it to add another slightly duplicit but exact timestamp... Steve Grubb is our local expert on certifications, so unless he tells me this is likely required, I don't feel like adding that extra information there right now... Yes, this turns out to be a bigger issue than I'd thought, see my reply to Thomas in the thread for 2/2. -- Ondrej Mosnacek <omosnace at redhat dot com> Software Engineer, Security Technologies Red Hat, Inc.

On Thu, 28 Mar 2019, Thomas Gleixner wrote: Aside of that you might talk to your colleagues working on Preempt-RT about this. I'm pretty sure they are going to have opinions simply because you cannot do ATOMIC allocations in those contexts on RT. Logging needs to be unintrusive and allocations are definitely not. Thanks, tglx

On Thu, Mar 28, 2019 at 1:09 AM Thomas Gleixner <tglx(a)linutronix.de&gt; wrote: Oh, sorry, I wrote that code last summer, when I didn't quite have the kernel coding style in my blood yet :) But fortunately I shouldn't need that comment at all in the next version... But wait, isn't this call outside of the critical section as well? (I must have been moving the call around when I was writing the code and didn't realize that this function actually doesn't need GFP_ATOMIC at all...) Or am I missing something? -- Ondrej Mosnacek <omosnace at redhat dot com> Software Engineer, Security Technologies Red Hat, Inc.

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(a)redhat.com&gt; --- include/linux/audit.h | 14 ++++++++++++++ include/uapi/linux/audit.h | 1 + kernel/auditsc.c | 7 +++++++ kernel/time/ntp.c | 38 ++++++++++++++++++++++++++++++-------- 4 files changed, 52 insertions(+), 8 deletions(-) diff --git a/include/linux/audit.h b/include/linux/audit.h index 43a60fbe74be..0f67964544cc 100644 --- a/include/linux/audit.h +++ b/include/linux/audit.h @@ -367,6 +367,7 @@ 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_adjust(const char *type, s64 oldval, s64 newval); static inline void audit_ipc_obj(struct kern_ipc_perm *ipcp) { @@ -479,6 +480,16 @@ static inline void audit_tk_injoffset(struct timespec64 offset) __audit_tk_injoffset(offset); } +static inline void audit_ntp_adjust(const char *type, s64 oldval, s64 newval) +{ + /* ignore no-op events */ + if (newval == oldval) + return; + + if (!audit_dummy_context()) + __audit_ntp_adjust(type, oldval, newval); +} + extern int audit_n_rules; extern int audit_signals; #else /* CONFIG_AUDITSYSCALL */ @@ -595,6 +606,9 @@ static inline void audit_fanotify(unsigned int response) static inline void audit_tk_injoffset(struct timespec64 offset) { } +static inline void audit_ntp_adjust(const char *type, s64 oldval, s64 newval) +{ } + 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 2167d55bc800..e9781f0385eb 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 781336d0f2de..946806174cd9 100644 --- a/kernel/auditsc.c +++ b/kernel/auditsc.c @@ -2520,6 +2520,13 @@ void __audit_tk_injoffset(struct timespec64 offset) "sec=%lli nsec=%li", (long long)offset.tv_sec, offset.tv_nsec); } +void __audit_ntp_adjust(const char *type, s64 oldval, s64 newval) +{ + audit_log(audit_context(), GFP_ATOMIC, AUDIT_TIME_ADJNTPVAL, + "op=%s old=%lli new=%lli", type, + (long long)oldval, (long long)newval); +} + 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 36a2bef00125..5f456a84151a 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" @@ -293,6 +294,8 @@ static inline s64 ntp_update_offset_fll(s64 offset64, long secs) static void ntp_update_offset(long offset) { + s64 old_offset = time_offset; + s64 old_freq = time_freq; s64 freq_adj; s64 offset64; long secs; @@ -341,6 +344,9 @@ static void ntp_update_offset(long offset) time_freq = max(freq_adj, -MAXFREQ_SCALED); time_offset = div_s64(offset64 << NTP_SCALE_SHIFT, NTP_INTERVAL_FREQ); + + audit_ntp_adjust("offset", old_offset, time_offset); + audit_ntp_adjust("freq", old_freq, time_freq); } /** @@ -658,21 +664,31 @@ static inline void process_adj_status(const struct timex *txc) static inline void process_adjtimex_modes(const struct timex *txc, s32 *time_tai) { - if (txc->modes & ADJ_STATUS) - process_adj_status(txc); + if (txc->modes & (ADJ_STATUS | ADJ_NANO | ADJ_MICRO)) { + int old_status = time_status; + + if (txc->modes & ADJ_STATUS) + process_adj_status(txc); - if (txc->modes & ADJ_NANO) - time_status |= STA_NANO; + if (txc->modes & ADJ_NANO) + time_status |= STA_NANO; - if (txc->modes & ADJ_MICRO) - time_status &= ~STA_NANO; + if (txc->modes & ADJ_MICRO) + time_status &= ~STA_NANO; + + audit_ntp_adjust("status", old_status, time_status); + } if (txc->modes & ADJ_FREQUENCY) { + s64 old_freq = time_freq; + time_freq = txc->freq * PPM_SCALE; time_freq = min(time_freq, MAXFREQ_SCALED); time_freq = max(time_freq, -MAXFREQ_SCALED); /* update pps_freq */ pps_set_freq(time_freq); + + audit_ntp_adjust("freq", old_freq, time_freq); } if (txc->modes & ADJ_MAXERROR) @@ -689,14 +705,18 @@ static inline void process_adjtimex_modes(const struct timex *txc, s32 *time_tai time_constant = max(time_constant, 0l); } - if (txc->modes & ADJ_TAI && txc->constant > 0) + if (txc->modes & ADJ_TAI && txc->constant > 0) { + audit_ntp_adjust("tai", *time_tai, txc->constant); *time_tai = txc->constant; + } if (txc->modes & ADJ_OFFSET) ntp_update_offset(txc->offset); - if (txc->modes & ADJ_TICK) + if (txc->modes & ADJ_TICK) { + audit_ntp_adjust("tick", tick_usec, txc->tick); tick_usec = txc->tick; + } if (txc->modes & (ADJ_TICK|ADJ_FREQUENCY|ADJ_OFFSET)) ntp_update_frequency(); @@ -718,6 +738,8 @@ int __do_adjtimex(struct timex *txc, const struct timespec64 *ts, s32 *time_tai) /* adjtime() is independent from ntp_adjtime() */ time_adjust = txc->offset; ntp_update_frequency(); + + audit_ntp_adjust("adjust", save_adjust, txc->offset); } txc->offset = save_adjust; } else { -- 2.20.1

On Thu, Mar 28, 2019 at 1:02 AM Thomas Gleixner <tglx(a)linutronix.de&gt; wrote: Yeah, sorry, I went a bit overboard with the record examples... I'll try to provide simpler and less verbose examples in the next version. OK, seems I underestimated the consequences of putting the logging calls directly in there. While I was offline over the weekend I already came up with a cleaner version that collects the changes in a structure and does the logging outside of the critical section. I currently does a few unnecessary writes into memory under CONFIG_AUDIT=n, but if that is an issue I can boost the abstraction or just add some #ifdefs to avoid that. I worry that extracting everything from the timex structures might get a little too complicated... Hopefully you'll be OK with the solution I am preparing for v8 - it still adds a bit of code to ntp.c, but it's much less intrusive. Thanks a lot for the review! -- Ondrej Mosnacek <omosnace at redhat dot com> Software Engineer, Security Technologies Red Hat, Inc.