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
policy definition structure; this permits policies to reduce their
number of gratuitous includes for required for entry points they
don't implement. This also facilitates building the MAC Framework
on Darwin.
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
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
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
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
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
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
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
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
on all label parsing occuring in userland, and knowledge of the loaded
policies in the user libraries. This revision of the API pushes that
parsing into the kernel, avoiding the need for shared library support
of policies in userland, permitting statically linked binaries (such
as ls, ps, and ifconfig) to use MAC labels. In these API revisions,
high level parsing of the MAC label is done in the MAC Framework,
and interpretation of label elements is delegated to the MAC policy
modules. This permits modules to export zero or more label elements
to user space if desired, and support them in the manner they want
and with the semantics they want. This is believed to be the final
revision of this interface: from the perspective of user applications,
the API has actually not changed, although the ABI has.
Approved by: re
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
checks from the MAC tree: allow policies to perform access control
for the ability of a process to send and receive data via a socket.
At some point, we might also pass in additional address information
if an explicit address is requested on send.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
seperate entry points for each occasion:
mac_check_vnode_mmap() Check at initial mapping
mac_check_vnode_mprotect() Check at mapping protection change
mac_check_vnode_mmap_downgrade() Determine if a mapping downgrade
should take place following
subject relabel.
Implement mmap() and mprotect() entry points for labeled vnode
policies. These entry points are currently not hooked up to the
VM system in the base tree. These changes improve the consistency
of the access control interface and offer more flexibility regarding
limiting access to vnode mmaping.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
flags so that we can call malloc with M_NOWAIT if necessary, avoiding
potential sleeps while holding mutexes in the TCP syncache code.
Similar to the existing support for mbuf label allocation: if we can't
allocate all the necessary label store in each policy, we back out
the label allocation and fail the socket creation. Sync from MAC tree.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
devfs VOP symlink creation by introducing a new entry point to determine
the label of the devfs_dirent prior to allocation of a vnode for the
symlink.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
point that instruments the creation of hard links. Policy implementations
to follow.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
- Change mpo_init_foo(obj, label) and mpo_destroy_foo(obj, label) policy
entry points to mpo_init_foo_label(label) and
mpo_destroy_foo_label(label). This will permit the use of the same
entry points for holding temporary type-specific label during
internalization and externalization, as well as for caching purposes.
- Because of this, break out mpo_{init,destroy}_socket() and
mpo_{init,destroy}_mount() into seperate entry points for socket
main/peer labels and mount main/fs labels.
- Since the prototype for label initialization is the same across almost
all entry points, implement these entry points using common
implementations for Biba, MLS, and Test, reducing the number of
almost identical looking functions.
This simplifies policy implementation, as well as preparing us for the
merge of the new flexible userland API for managing labels on objects.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
modules to perform MAC-related events when a thread returns to user
space. This is required for policies that have floating process labels,
as it's not always possible to acquire the process lock at arbitrary
points in the stack during system call processing; process labels might
represent traditional authentication data, process history information,
or other data.
LOMAC will use this entry point to perform the process label update
prior to the thread returning to userspace, when plugged into the MAC
framework.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
for mac_check_vnode_{poll,read,stat,write}(). Pass in fp->f_cred
when calling these checks with a struct file available. Otherwise,
pass NOCRED. All currently MAC policies use active_cred, but
could now offer the cached credential semantic used for the base
system security model.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, NAI Labs
can offer new services without reserving system call numbers, or
augmented versions of existing services. User code requests a
target policy by name, and specifies the policy-specific API plus
target. This is required in particular for our port of SELinux/FLASK
to the MAC framework since it offers additional security services.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, NAI Labs
mac_check_pipe_poll(), mac_check_pipe_read(), mac_check_pipe_stat(),
and mac_check_pipe_write(). This is improves consistency with other
access control entry points and permits security modules to only
control the object methods that they are interested in, avoiding
switch statements.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, NAI Labs
mac_check_vnode_poll(), mac_check_vnode_read(), mac_check_vnode_write().
This improves the consistency with other existing vnode checks, and
allows policies to avoid implementing switch statements to determine
what operations they do and do not want to authorize.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, NAI Labs
we can use the names _receive() and _send() for the receive() and send()
checks. Rename related constants, policy implementations, etc.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, NAI Labs
enabled and the kernel provides the MAC registration and entry point
service. Declare a dependency on that module service for any
MAC module registered using mac_policy.h. For now, hard code the
version as 1, but once we've come up with a versioning policy, we'll
move to a #define of some sort. In the mean time, this will prevent
loading a MAC module when 'options MAC' isn't present, which (due to
a bug in the kernel linker) can result if the MAC module is preloaded
via loader.conf.
This particular evil recommended by: peter
Obtained from: TrustedBSD Project
Sponsored by: DARPA, NAI LAbs
structure. This prevents a boatload of warnings in the MAC modules,
so we can hook them up to the build.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, NAI Labs
kernel access control. The MAC framework permits loadable kernel
modules to link to the kernel at compile-time, boot-time, or run-time,
and augment the system security policy. This commit includes the
initial kernel implementation, although the interface with the userland
components of the oeprating system is still under work, and not all
kernel subsystems are supported. Later in this commit sequence,
documentation of which kernel subsystems will not work correctly with
a kernel compiled with MAC support will be added.
Include files to declare MAC userland interface (mac.h), MAC subsystem
entry points (mac.h), and MAC policy entry points (mac_policy.h). These
files define the interface between the kernel and the MAC framework,
and between the MAC framework and each registered policy module. These
APIs and ABIs may not be assumed to be stable until following FreeBSD
5.1-RELEASE.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, NAI Labs
