the MAC policy modules to improve robustness against C string
bugs and vulnerabilities. Following these revisions, all
string construction of labels for export to userspace (or
elsewhere) is performed using the sbuf API, which prevents
the consumer from having to perform laborious and intricate
pointer and buffer checks. This substantially simplifies
the externalization logic, both at the MAC Framework level,
and in individual policies; this becomes especially useful
when policies export more complex label data, such as with
compartments in Biba and MLS.
Bundled in here are some other minor fixes associated with
externalization: including avoiding malloc while holding the
process mutex in mac_lomac, and hence avoid a failure mode
when printing labels during a downgrade operation due to
the removal of the M_NOWAIT case.
This has been running in the MAC development tree for about
three weeks without problems.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
Several of the subtypes have an associated vnode which is used for
stuff like the f*() functions.
By giving the vnode a speparate field, a number of checks for the specific
subtype can be replaced simply with a check for f_vnode != NULL, and
we can later free f_data up to subtype specific use.
At this point in time, f_data still points to the vnode, so any code I
might have overlooked will still work.
constants in question refer to the number of label slots, not the
maximum number of policies that may be loaded. This should reduce
confusion regarding an element in the MAC sysctl MIB, as well as
make it more clear what the affect of changing the compile-time
constants is.
Approved by: re (jhb)
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
(1) Accept that we're now going to use mutexes, so don't attempt
to avoid treating them as mutexes. This cleans up locking
accessor function names some.
(2) Rename variables to _mtx, _cv, _count, simplifying the naming.
(3) Add a new form of the _busy() primitive that conditionally
makes the list busy: if there are entries on the list, bump
the busy count. If there are no entries, don't bump the busy
count. Return a boolean indicating whether or not the busy
count was bumped.
(4) Break mac_policy_list into two lists: one with the same name
holding dynamic policies, and a new list, mac_static_policy_list,
which holds policies loaded before mac_late and without the
unload flag set. The static list may be accessed without
holding the busy count, since it can't change at run-time.
(5) In general, prefer making the list busy conditionally, meaning
we pay only one mutex lock per entry point if all modules are
on the static list, rather than two (since we don't have to
lower the busy count when we're done with the framework). For
systems running just Biba or MLS, this will halve the mutex
accesses in the network stack, and may offer a substantial
performance benefits.
(6) Lay the groundwork for a dynamic-free kernel option which
eliminates all locking associated with dynamically loaded or
unloaded policies, for pre-configured systems requiring
maximum performance but less run-time flexibility.
These changes have been running for a few weeks on MAC development
branch systems.
Approved by: re (jhb)
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
- Add a parameter to vm_pageout_flush() that tells vm_pageout_flush()
whether its caller has locked the vm_object. (This is a temporary
measure to bootstrap vm_object locking.)
don't try and convert the argument flags to malloc flags, or we risk
implicitly requesting blocking and generating witness warnings.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
returning some additional room in the first mbuf in a chain, and
avoiding feature-specific contents in the mbuf header. To do this:
- Modify mbuf_to_label() to extract the tag, returning NULL if not
found.
- Introduce mac_init_mbuf_tag() which does most of the work
mac_init_mbuf() used to do, except on an m_tag rather than an
mbuf.
- Scale back mac_init_mbuf() to perform m_tag allocation and invoke
mac_init_mbuf_tag().
- Replace mac_destroy_mbuf() with mac_destroy_mbuf_tag(), since
m_tag's are now GC'd deep in the m_tag/mbuf code rather than
at a higher level when mbufs are directly free()'d.
- Add mac_copy_mbuf_tag() to support m_copy_pkthdr() and related
notions.
- Generally change all references to mbuf labels so that they use
mbuf_to_label() rather than &mbuf->m_pkthdr.label. This
required no changes in the MAC policies (yay!).
- Tweak mbuf release routines to not call mac_destroy_mbuf(),
tag destruction takes care of it for us now.
- Remove MAC magic from m_copy_pkthdr() and m_move_pkthdr() --
the existing m_tag support does all this for us. Note that
we can no longer just zero the m_tag list on the target mbuf,
rather, we have to delete the chain because m_tag's will
already be hung off freshly allocated mbuf's.
- Tweak m_tag copying routines so that if we're copying a MAC
m_tag, we don't do a binary copy, rather, we initialize the
new storage and do a deep copy of the label.
- Remove use of MAC_FLAG_INITIALIZED in a few bizarre places
having to do with mbuf header copies previously.
- When an mbuf is copied in ip_input(), we no longer need to
explicitly copy the label because it will get handled by the
m_tag code now.
- No longer any weird handling of MAC labels in if_loop.c during
header copies.
- Add MPC_LOADTIME_FLAG_LABELMBUFS flag to Biba, MLS, mac_test.
In mac_test, handle the label==NULL case, since it can be
dynamically loaded.
In order to improve performance with this change, introduce the notion
of "lazy MAC label allocation" -- only allocate m_tag storage for MAC
labels if we're running with a policy that uses MAC labels on mbufs.
Policies declare this intent by setting the MPC_LOADTIME_FLAG_LABELMBUFS
flag in their load-time flags field during declaration. Note: this
opens up the possibility of post-boot policy modules getting back NULL
slot entries even though they have policy invariants of non-NULL slot
entries, as the policy might have been loaded after the mbuf was
allocated, leaving the mbuf without label storage. Policies that cannot
handle this case must be declared as NOTLATE, or must be modified.
- mac_labelmbufs holds the current cumulative status as to whether
any policies require mbuf labeling or not. This is updated whenever
the active policy set changes by the function mac_policy_updateflags().
The function iterates the list and checks whether any have the
flag set. Write access to this variable is protected by the policy
list; read access is currently not protected for performance reasons.
This might change if it causes problems.
- Add MAC_POLICY_LIST_ASSERT_EXCLUSIVE() to permit the flags update
function to assert appropriate locks.
- This makes allocation in mac_init_mbuf() conditional on the flag.
Reviewed by: sam
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
mbuf_to_label(). This permits the vast majority of entry point code
to be unaware that labels are stored in m->m_pkthdr.label, such that
we can experiment storage of labels elsewhere (such as in m_tags).
Reviewed by: sam
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
of asserting that an mbuf has a packet header. Use it instead of hand-
rolled versions wherever applicable.
Submitted by: Hiten Pandya <hiten@unixdaemons.com>
additional flags argument to indicate blocking disposition, and
pass in M_NOWAIT from the IP reassembly code to indicate that
blocking is not OK when labeling a new IP fragment reassembly
queue. This should eliminate some of the WITNESS warnings that
have started popping up since fine-grained IP stack locking
started going in; if memory allocation fails, the creation of
the fragment queue will be aborted.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
check, mac_check_sysarch_ioperm(), permitting MAC security policy
modules to control access to these interfaces. Currently, they
protect access to IOPL on i386, and setting HAE on Alpha.
Additional checks might be required on other platforms to prevent
bypass of kernel security protections by unauthorized processes.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
modules to authorize disabling of swap against a particular vnode.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
pointer types, and remove a huge number of casts from code using it.
Change struct xfile xf_data to xun_data (ABI is still compatible).
If we need to add a #define for f_data and xf_data we can, but I don't
think it will be necessary. There are no operational changes in this
commit.
unused. Replace it with a dm_mount back-pointer to the struct mount
that the devfs_mount is associated with. Export that pointer to MAC
Framework entry points, where all current policies don't use the
pointer. This permits the SEBSD port of SELinux's FLASK/TE to compile
out-of-the-box on 5.0-CURRENT with full file system labeling support.
Approved by: re (murray)
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
by policy modules making use of downgrades in the MAC AST event. This
is required by the mac_lomac port of LOMAC to the MAC Framework.
Approved by: re
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
in struct proc. While the process label is actually stored in the
struct ucred pointed to by p_ucred, there is a need for transient
storage that may be used when asynchronous (deferred) updates need to
be performed on the "real" label for locking reasons. Unlike other
label storage, this label has no locking semantics, relying on policies
to provide their own protection for the label contents, meaning that
a policy leaf mutex may be used, avoiding lock order issues. This
permits policies that act based on historical process behavior (such
as audit policies, the MAC Framework port of LOMAC, etc) can update
process properties even when many existing locks are held without
violating the lock order. No currently committed policies implement use
of this label storage.
Approved by: re
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
checks permit policy modules to augment the system policy for permitting
kld operations. This permits policies to limit access to kld operations
based on credential (and other) properties, as well as to perform checks
on the kld being loaded (integrity, etc).
Approved by: re
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
the MAC policy list is busy during a load or unload attempt.
We assert no locks held during the cv wait, meaning we should
be fairly deadlock-safe. Because of the cv model and busy
count, it's possible for a cv waiter waiting for exclusive
access to the policy list to be starved by active and
long-lived access control/labeling events. For now, we
accept that as a necessary tradeoff.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
we brought in the new cache and locking model for vnode labels. We
now rely on mac_associate_devfs_vnode().
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
dynamic mapping of an operation vector into an operation structure,
rather, we rely on C99 sparse structure initialization.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
points, rather than relying on policies to grub around in the
image activator instance structure.
Approved by: re
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
(1) Permit userland applications to request a change of label atomic
with an execve() via mac_execve(). This is required for the
SEBSD port of SELinux/FLASK. Attempts to invoke this without
MAC compiled in result in ENOSYS, as with all other MAC system
calls. Complexity, if desired, is present in policy modules,
rather than the framework.
(2) Permit policies to have access to both the label of the vnode
being executed as well as the interpreter if it's a shell
script or related UNIX nonsense. Because we can't hold both
vnode locks at the same time, cache the interpreter label.
SEBSD relies on this because it supports secure transitioning
via shell script executables. Other policies might want to
take both labels into account during an integrity or
confidentiality decision at execve()-time.
Approved by: re
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
Allow transitioning to be twiddled off using the process and fs enforcement
flags, although at some point this should probably be its own flag.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
system accounting configuration and for nfsd server thread attach.
Policies might use this to protect the integrity or confidentiality
of accounting data, limit the ability to turn on or off accounting,
as well as to prevent inappropriately labeled threads from becoming nfs
server threads.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
permitting MAC policies to limit access to the kernel environment.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
structure definition, rather than using an operation vector
we translate into the structure. Originally, we used a vector
for two reasons:
(1) We wanted to define the structure sparsely, which wasn't
supported by the C compiler for structures. For a policy
with five entry points, you don't want to have to stick in
a few hundred NULL function pointers.
(2) We thought it would improve ABI compatibility allowing modules
to work with kernels that had a superset of the entry points
defined in the module, even if the kernel had changed its
entry point set.
Both of these no longer apply:
(1) C99 gives us a way to sparsely define a static structure.
(2) The ABI problems existed anyway, due to enumeration numbers,
argument changes, and semantic mismatches. Since the going
rule for FreeBSD is that you really need your modules to
pretty closely match your kernel, it's not worth the
complexity.
This submit eliminates the operation vector, dynamic allocation
of the operation structure, copying of the vector to the
structure, and redoes the vectors in each policy to direct
structure definitions. One enourmous benefit of this change
is that we now get decent type checking on policy entry point
implementation arguments.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
MAC access() and open() checks, the argument actually has an int type
where it becomes available. Switch to using 'int' for the mode argument
throughout the MAC Framework and policy modules.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
mac_enforce_system toggle, rather than several separate toggles.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
permit MAC policies to augment the security protections on sysctl()
operations. This is not really a wonderful entry point, as we
only have access to the MIB of the target sysctl entry, rather than
the more useful entry name, but this is sufficient for policies
like Biba that wish to use their notions of privilege or integrity
to prevent inappropriate sysctl modification. Affects MAC kernels
only. Since SYSCTL_LOCK isn't in sysctl.h, just kern_sysctl.c,
we can't assert the SYSCTL subsystem lockin the MAC Framework.
Approved by: re
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
permits MAC modules to augment system security decisions regarding
the reboot() system call, if MAC is compiled into the kernel.
Approved by: re
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
mac_check_system_swapon(), to reflect the fact that the primary
object of this change is the running kernel as a whole, rather
than just the vnode. We'll drop additional checks of this
class into the same check namespace, including reboot(),
sysctl(), et al.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
"refreshing" the label on the vnode before use, just get the label
right from inception. For single-label file systems, set the label
in the generic VFS getnewvnode() code; for multi-label file systems,
leave the labeling up to the file system. With UFS1/2, this means
reading the extended attribute during vfs_vget() as the inode is
pulled off disk, rather than hitting the extended attributes
frequently during operations later, improving performance. This
also corrects sematics for shared vnode locks, which were not
previously present in the system. This chances the cache
coherrency properties WRT out-of-band access to label data, but in
an acceptable form. With UFS1, there is a small race condition
during automatic extended attribute start -- this is not present
with UFS2, and occurs because EAs aren't available at vnode
inception. We'll introduce a work around for this shortly.
Approved by: re
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
perform authorization checks during swapon() events; policies
might choose to enforce protections based on the credential
requesting the swap configuration, the target of the swap operation,
or other factors such as internal policy state.
Approved by: re
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
to use a modified notion of 'struct mac', and flesh out the new variation
system calls (almost identical to existing ones except that they permit
a pid to be specified for process label retrieval, and don't follow
symlinks). This generalizes the label API so that the framework is
now almost entirely policy-agnostic.
Approved by: re
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
