system-call entry and whenever audit arguments or return values are
captured:
1. Expose a single global, audit_syscalls_enabled, which controls
whether the audit framework is entered, rather than exposing
components of the policy -- e.g., if the trail is enabled,
suspended, etc.
2. Introduce a new function audit_syscalls_enabled_update(), which is
called to update audit_syscalls_enabled whenever an aspect of the
policy changes, so that the value can be updated.
3. Remove a check of trail enablement/suspension from audit_new() --
at the point where this function has been entered, we believe that
system-call auditing is already in force, or we wouldn't get here,
so simply proceed to more expensive policy checks.
4. Use an audit-provided global, audit_dtrace_enabled, rather than a
dtaudit-provided global, to provide policy indicating whether
dtaudit would like system calls to be audited.
5. Do some minor cosmetic renaming to clarify what various variables
are for.
These changes collectively arrange it so that traditional audit
(trail, pipes) or the DTrace audit provider can enable system-call
probes without the other configured. Otherwise, dtaudit cannot
capture system-call data without auditd(8) started.
Reviewed by: gnn
Sponsored by: DARPA, AFRL
Approved by: re (gjb)
Differential Revision: https://reviews.freebsd.org/D17348
instrument security event auditing rather than relying on conventional BSM
trail files or audit pipes:
- Add a set of per-event 'commit' probes, which provide access to
particular auditable events at the time of commit in system-call return.
These probes gain access to audit data via the in-kernel audit_record
data structure, providing convenient access to system-call arguments and
return values in a single probe.
- Add a set of per-event 'bsm' probes, which provide access to particular
auditable events at the time of BSM record generation in the audit
worker thread. These probes have access to the in-kernel audit_record
data structure and BSM representation as would be written to a trail
file or audit pipe -- i.e., asynchronously in the audit worker thread.
DTrace probe arguments consist of the name of the audit event (to support
future mechanisms of instrumenting multiple events via a single probe --
e.g., using classes), a pointer to the in-kernel audit record, and an
optional pointer to the BSM data and its length. For human convenience,
upper-case audit event names (AUE_...) are converted to lower case in
DTrace.
DTrace scripts can now cause additional audit-based data to be collected
on system calls, and inspect internal and BSM representations of the data.
They do not affect data captured in the audit trail or audit pipes
configured in the system. auditd(8) must be configured and running in
order to provide a database of event information, as well as other audit
configuration parameters (e.g., to capture command-line arguments or
environmental variables) for the provider to operate.
Reviewed by: gnn, jonathan, markj
Sponsored by: DARPA, AFRL
MFC after: 3 weeks
Differential Revision: https://reviews.freebsd.org/D10149
