[PATCH ghak10 v5 0/2] audit: Log modifying adjtimex(2) calls

This patchset implements more detailed auditing of the adjtimex(2) syscall in order to make it possible to: a) distinguish modifying vs. read-only calls in the audit log b) reconstruct from the audit log what changes were made and how they have influenced the system clock The main motivation is to be able to detect an adversary that tries to confuse the audit timestamps by changing system time via adjtimex(2), but at the same time avoid flooding the audit log with records of benign read-only adjtimex(2) calls. The current version of the patchset logs the following changes: - 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 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 Ondrej Mosnacek (2): audit: Add functions to log time adjustments timekeeping/ntp: Audit clock/NTP params adjustments include/linux/audit.h | 21 +++++++++++++++++++++ include/uapi/linux/audit.h | 2 ++ kernel/auditsc.c | 15 +++++++++++++++ kernel/time/ntp.c | 38 ++++++++++++++++++++++++++++++-------- kernel/time/timekeeping.c | 3 +++ 5 files changed, 71 insertions(+), 8 deletions(-) -- 2.17.1