Modify the MAC Framework so that instead of embedding a (struct label)

in various kernel objects to represent security data, we embed a
(struct label *) pointer, which now references labels allocated using
a UMA zone (mac_label.c).  This allows the size and shape of struct
label to be varied without changing the size and shape of these kernel
objects, which become part of the frozen ABI with 5-STABLE.  This opens
the door for boot-time selection of the number of label slots, and hence
changes to the bound on the number of simultaneous labeled policies
at boot-time instead of compile-time.  This also makes it easier to
embed label references in new objects as required for locking/caching
with fine-grained network stack locking, such as inpcb structures.

This change also moves us further in the direction of hiding the
structure of kernel objects from MAC policy modules, not to mention
dramatically reducing the number of '&' symbols appearing in both the
MAC Framework and MAC policy modules, and improving readability.

While this results in minimal performance change with MAC enabled, it
will observably shrink the size of a number of critical kernel data
structures for the !MAC case, and should have a small (but measurable)
performance benefit (i.e., struct vnode, struct socket) do to memory
conservation and reduced cost of zeroing memory.

NOTE: Users of MAC must recompile their kernel and all MAC modules as a
result of this change.  Because this is an API change, third party
MAC modules will also need to be updated to make less use of the '&'
symbol.

Suggestions from:	bmilekic
Obtained from:		TrustedBSD Project
Sponsored by:		DARPA, Network Associates Laboratories

1 files changed, 7 insertions, 4 deletions

diff --git a/sys/security/mac/mac_framework.h b/sys/security/mac/mac_framework.h
index 7955c25a..1dc6bf1 100644
--- a/sys/security/mac/mac_framework.h
+++ b/sys/security/mac/mac_framework.h
@@ -144,7 +144,6 @@ int	mac_init_mbuf_tag(struct m_tag *, int flag);
 void	mac_init_mount(struct mount *);
 void	mac_init_proc(struct proc *);
 void	mac_init_vnode(struct vnode *);
-void	mac_init_vnode_label(struct label *);
 void	mac_copy_mbuf_tag(struct m_tag *, struct m_tag *);
 void	mac_copy_vnode_label(struct label *, struct label *label);
 void	mac_destroy_bpfdesc(struct bpf_d *);
@@ -158,7 +157,12 @@ void	mac_destroy_proc(struct proc *);
 void	mac_destroy_mbuf_tag(struct m_tag *);
 void	mac_destroy_mount(struct mount *);
 void	mac_destroy_vnode(struct vnode *);
-void	mac_destroy_vnode_label(struct label *);
+
+struct label	*mac_cred_label_alloc(void);
+void		 mac_cred_label_free(struct label *label);
+struct label	*mac_vnode_label_alloc(void);
+void		 mac_vnode_label_free(struct label *label);
+void		 mac_destroy_vnode_label(struct label *);
 
 /*
  * Labeling event operations: file system objects, and things that
@@ -220,8 +224,7 @@ void	mac_update_ipq(struct mbuf *fragment, struct ipq *ipq);
  * Labeling event operations: processes.
  */
 void	mac_create_cred(struct ucred *cred_parent, struct ucred *cred_child);
-int	mac_execve_enter(struct image_params *imgp, struct mac *mac_p,
-	    struct label *execlabel);
+int	mac_execve_enter(struct image_params *imgp, struct mac *mac_p);
 void	mac_execve_exit(struct image_params *imgp);
 void	mac_execve_transition(struct ucred *old, struct ucred *new,
 	    struct vnode *vp, struct label *interpvnodelabel,