modules are loaded by avoiding mbuf label lookups when policies aren't loaded, pushing further socket locking into MAC policy modules, and avoiding locking MAC ifnet locks when no policies are loaded: - Check mac_policies_count before looking for mbuf MAC label m_tags in MAC Framework entry points. We will still pay label lookup costs if MAC policies are present but don't require labels (typically a single mbuf header field read, but perhaps further indirection if IPSEC or other m_tag consumers are in use). - Further push socket locking for socket-related access control checks and events into MAC policies from the MAC Framework, so that sockets are only locked if a policy specifically requires a lock to protect a label. This resolves lock order issues during sonewconn() and also in local domain socket cross-connect where multiple socket locks could not be held at once for the purposes of propagatig MAC labels across multiple sockets. Eliminate mac_policy_count check in some entry points where it no longer avoids locking. - Add mac_policy_count checking in some entry points relating to network interfaces that otherwise lock a global MAC ifnet lock used to protect ifnet labels. Obtained from: TrustedBSD Project
count of the number of registered policies. Rather than unconditionally locking sockets before passing them into MAC, lock them in the MAC entry points only if mac_policy_count is non-zero. This avoids locking overhead for a number of socket system calls when no policies are registered, eliminating measurable overhead for the MAC Framework for the socket subsystem when there are no active policies. Possibly socket locks should be acquired by policies if they are required for socket labels, which would further avoid locking overhead when there are policies but they don't require labeling of sockets, or possibly don't even implement socket controls. Obtained from: TrustedBSD Project
MAC_BOOLEAN -> MAC_POLICY_BOOLEAN MAC_BOOLEAN_NOSLEEP -> MAC_POLICY_BOOLEANN_NOSLEEP MAC_CHECK -> MAC_POLICY_CHECK MAC_CHECK_NOSLEEP -> MAC_POLICY_CHECK_NOSLEEP MAC_EXTERNALIZE -> MAC_POLICY_EXTERNALIZE MAC_GRANT -> MAC_POLICY_GRANT MAC_GRANT_NOSLEEP -> MAC_POLICY_GRANT_NOSLEEP MAC_INTERNALIZE -> MAC_POLICY_INTERNALIZE MAC_PERFORM -> MAC_POLICY_PERFORM_CHECK MAC_PERFORM_NOSLEEP -> MAC_POLICY_PERFORM_NOSLEEP This frees up those macro names for use in wrapping calls into the MAC Framework from the remainder of the kernel. Obtained from: TrustedBSD Project
improve performance: - Eliminate custom reference count and condition variable to monitor threads entering the framework, as this had both significant overhead and behaved badly in the face of contention. - Replace reference count with two locks: an rwlock and an sx lock, which will be read-acquired by threads entering the framework depending on whether a give policy entry point is permitted to sleep or not. - Replace previous mutex locking of the reference count for exclusive access with write acquiring of both the policy list sx and rw locks, which occurs only when policies are attached or detached. - Do a lockless read of the dynamic policy list head before acquiring any locks in order to reduce overhead when no dynamic policies are loaded; this a race we can afford to lose. - For every policy entry point invocation, decide whether sleeping is permitted, and if not, use a _NOSLEEP() variant of the composition macros, which will use the rwlock instead of the sxlock. In some cases, we decide which to use based on allocation flags passed to the MAC Framework entry point. As with the move to rwlocks/rmlocks in pfil, this may trigger witness warnings, but these should (generally) be false positives as all acquisition of the locks is for read with two very narrow exceptions for policy load/unload, and those code blocks should never acquire other locks. Sponsored by: Google, Inc. Obtained from: TrustedBSD Project Discussed with: csjp (idea, not specific patch)
other use of the same variable type. Obtained from: TrustedBSD Project Sponsored by: Google, Inc.
privilege grants so that dtrace can be more easily used to monitor the security decisions being generated by the MAC Framework following policy invocation. Successful access control checks will be reported by: mac_framework:kernel:<entrypoint>:mac_check_ok Failed access control checks will be reported by: mac_framework:kernel:<entrypoint>:mac_check_err Successful privilege grants will be reported by: mac_framework:kernel:priv_grant:mac_grant_ok Failed privilege grants will be reported by: mac_framework:kernel:priv_grant:mac_grant_err In all cases, the return value (always 0 for _ok, otherwise an errno for _err) will be reported via arg0 on the probe, and subsequent arguments will hold entrypoint-specific data, in a style similar to privilege tracing. Obtained from: TrustedBSD Project Sponsored by: Google, Inc.
(1) Abstract interpreter vnode labeling in execve(2) and mac_execve(2)
so that the general exec code isn't aware of the details of
allocating, copying, and freeing labels, rather, simply passes in
a void pointer to start and stop functions that will be used by
the framework. This change will be MFC'd.
(2) Introduce a new flags field to the MAC_POLICY_SET(9) interface
allowing policies to declare which types of objects require label
allocation, initialization, and destruction, and define a set of
flags covering various supported object types (MPC_OBJECT_PROC,
MPC_OBJECT_VNODE, MPC_OBJECT_INPCB, ...). This change reduces the
overhead of compiling the MAC Framework into the kernel if policies
aren't loaded, or if policies require labels on only a small number
or even no object types. Each time a policy is loaded or unloaded,
we recalculate a mask of labeled object types across all policies
present in the system. Eliminate MAC_ALWAYS_LABEL_MBUF option as it
is no longer required.
MFC after: 1 week ((1) only)
Reviewed by: csjp
Obtained from: TrustedBSD Project
Sponsored by: Apple, Inc.
from Mac OS X Leopard--rationalize naming for entry points to
the following general forms:
mac_<object>_<method/action>
mac_<object>_check_<method/action>
The previous naming scheme was inconsistent and mostly
reversed from the new scheme. Also, make object types more
consistent and remove spaces from object types that contain
multiple parts ("posix_sem" -> "posixsem") to make mechanical
parsing easier. Introduce a new "netinet" object type for
certain IPv4/IPv6-related methods. Also simplify, slightly,
some entry point names.
All MAC policy modules will need to be recompiled, and modules
not updates as part of this commit will need to be modified to
conform to the new KPI.
Sponsored by: SPARTA (original patches against Mac OS X)
Obtained from: TrustedBSD Project, Apple Computer
variable name conventions for arguments passed into the framework -- for example, name network interfaces 'ifp', sockets 'so', mounts 'mp', mbufs 'm', processes 'p', etc, wherever possible. Previously there was significant variation in this regard. Normalize copyright lists to ranges where sensible.
Framework and security modules, to src/sys/security/mac/mac_policy.h, completing the removal of kernel-only MAC Framework include files from src/sys/sys. Update the MAC Framework and MAC policy modules. Delete the old mac_policy.h. Third party policy modules will need similar updating. Obtained from: TrustedBSD Project