Add MAC framework entries for posix shm read and write.
Do not allow implicit extension of the underlying memory segment past
the limit set by ftruncate(2) by either of the syscalls. Read and
write returns short i/o, lseek(2) fails with EINVAL when resulting
offset does not fit into the limit.
Discussed with: alc
Tested by: pho
Sponsored by: The FreeBSD Foundation
and the new setmode and setowner fileops in FreeBSD 9.0:
- Add new MAC Framework entry point mac_posixshm_check_create() to allow
MAC policies to authorise shared memory use. Provide a stub policy and
test policy templates.
- Add missing Biba and MLS implementations of mac_posixshm_check_setmode()
and mac_posixshm_check_setowner().
- Add 'accmode' argument to mac_posixshm_check_open() -- unlike the
mac_posixsem_check_open() entry point it was modeled on, the access mode
is required as shared memory access can be read-only as well as writable;
this isn't true of POSIX semaphores.
- Implement full range of POSIX shared memory entry points for Biba and MLS.
Sponsored by: Google Inc.
Obtained from: TrustedBSD Project
Approved by: re (kib)
to implement fchown(2) and fchmod(2) support for several file types
that previously lacked it. Add MAC entries for chown/chmod done on
posix shared memory and (old) in-kernel posix semaphores.
Based on the submission by: glebius
Reviewed by: rwatson
Approved by: re (bz)
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)
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.
implement shm_open(2) and shm_unlink(2) in the kernel:
- Each shared memory file descriptor is associated with a swap-backed vm
object which provides the backing store. Each descriptor starts off with
a size of zero, but the size can be altered via ftruncate(2). The shared
memory file descriptors also support fstat(2). read(2), write(2),
ioctl(2), select(2), poll(2), and kevent(2) are not supported on shared
memory file descriptors.
- shm_open(2) and shm_unlink(2) are now implemented as system calls that
manage shared memory file descriptors. The virtual namespace that maps
pathnames to shared memory file descriptors is implemented as a hash
table where the hash key is generated via the 32-bit Fowler/Noll/Vo hash
of the pathname.
- As an extension, the constant 'SHM_ANON' may be specified in place of the
path argument to shm_open(2). In this case, an unnamed shared memory
file descriptor will be created similar to the IPC_PRIVATE key for
shmget(2). Note that the shared memory object can still be shared among
processes by sharing the file descriptor via fork(2) or sendmsg(2), but
it is unnamed. This effectively serves to implement the getmemfd() idea
bandied about the lists several times over the years.
- The backing store for shared memory file descriptors are garbage
collected when they are not referenced by any open file descriptors or
the shm_open(2) virtual namespace.
Submitted by: dillon, peter (previous versions)
Submitted by: rwatson (I based this on his version)
Reviewed by: alc (suggested converting getmemfd() to shm_open())
