Re: [RFC PATCH ghak10 v6 0/2] audit: Log changes that can affect the system clock

On Mon, Mar 25, 2019 at 10:50 AM Paul Moore <paul(a)paul-moore.com&gt; wrote: > On Thu, Mar 7, 2019 at 7:33 AM Ondrej Mosnacek <omosnace(a)redhat.com&gt; wrote: > > This patchset implements auditing of (syscall-triggered) changes that > > can modify or indirectly affect the system clock. Some of these > > changes can already be detected by simply logging relevant syscalls, > > but this has some disadvantages: > > a) It is usually not possible to find out from the syscall records > > the amount by which the time was shifted. > > b) Syscalls like adjtimex(2) or clock_adjtime(2) can be used also > > for read-only operations, which might flood the audit log with > > false positives. (Note that these patches don't solve this > > problem yet due to the limitations of current record filtering > > capabilities.) > > > > The main motivation is to provide better reliability of timestamps > > on the system as mandated by the FPT_STM.1 security functional > > requirement from Common Criteria. This requirement apparently demands > > that it is possible to reconstruct from audit trail the old and new > > values of the time when it is adjusted (see [1]). > > > > The current version of the patchset logs the following changes: > > - direct setting of system time to a given value > > - direct injection of timekeeping offset > > - adjustment of timekeeping's TAI offset > > - NTP value adjustments: > > - time_offset > > - time_freq > > - time_status > > - time_adjust > > - tick_usec > > > > Changes to the following NTP values are not logged, as they are not > > important for security: > > - time_maxerror > > - time_esterror > > - time_constant > > > > Audit kernel GitHub issue: https://github.com/linux-audit/audit-kernel/issues/10 > > Audit kernel RFE page: https://github.com/linux-audit/audit-kernel/wiki/RFE-More-detailed-auditi... > > > > Testing: Passed audit-testuite; functional tests TBD > > > > Changes in v6: > > - Reorganized the patches to group changes by record type, not > > kernel subsytem, as suggested in earlier discussions > > - Added checks to ignore no-change events (new value == old value) > > - Added TIME_INJOFFSET logging also to do_settimeofday64() to cover > > syscalls such as settimeofday(2), stime(2), clock_settime(2) > > - Created an RFE page on audit-kernel GitHub > > TODO: > > - tests for audit-testsuite > > > > v5: https://www.redhat.com/archives/linux-audit/2018-August/msg00039.html > > Changes in v5: > > - Dropped logging of some less important changes and update commit messages > > - No longer mark the patchset as RFC > > > > v4: https://www.redhat.com/archives/linux-audit/2018-August/msg00023.html > > Changes in v4: > > - Squashed first two patches into one > > - Renamed ADJNTPVAL's "type" field to "op" to align with audit record > > conventions > > - Minor commit message editing > > - Cc timekeeping/NTP people for feedback > > > > v3: https://www.redhat.com/archives/linux-audit/2018-July/msg00001.html > > Changes in v3: > > - Switched to separate records for each variable > > - Both old and new value is now reported for each change > > - Injecting offset is reported via a separate record (since this > > offset consists of two values and is added directly to the clock, > > i.e. it doesn't make sense to log old and new value) > > - Added example records produced by chronyd -q (see the commit message > > of the last patch) > > > > v2: https://www.redhat.com/archives/linux-audit/2018-June/msg00114.html > > Changes in v2: > > - The audit_adjtime() function has been modified to only log those > > fields that contain values that are actually used, resulting in more > > compact records. > > - The audit_adjtime() call has been moved to do_adjtimex() in > > timekeeping.c > > - Added an additional patch (for review) that simplifies the detection > > if the syscall is read-only. > > > > v1: https://www.redhat.com/archives/linux-audit/2018-June/msg00095.html > > > > [1] https://www.niap-ccevs.org/MMO/PP/pp_ca_v2.1.pdf -- section 5.1, > > table 4 > > > > Ondrej Mosnacek (2): > > timekeeping: Audit clock adjustments > > ntp: Audit NTP parameters adjustment > > > > include/linux/audit.h | 29 +++++++++++++++++++++++++++++ > > include/uapi/linux/audit.h | 2 ++ > > kernel/auditsc.c | 15 +++++++++++++++ > > kernel/time/ntp.c | 38 ++++++++++++++++++++++++++++++-------- > > kernel/time/timekeeping.c | 6 ++++++ > > 5 files changed, 82 insertions(+), 8 deletions(-) > > These patches look fine to me, but it would be really nice to get an > ACK from the time folks before I merge this into audit/next. Time > folks, I know you've looked at previous versions of this patchset, can > you give this a quick look to make sure everything is still okay from > your perspective? Ondrej, please don't let the lack of response from the time folks keep you from working on the tests. If you can get the tests ready in time, I see no reason why this couldn't get merged before the next merge window.