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, 57 insertions, 62 deletions

diff --git a/sys/security/mac/mac_syscalls.c b/sys/security/mac/mac_syscalls.c
index c459003..f9adf9b 100644
--- a/sys/security/mac/mac_syscalls.c
+++ b/sys/security/mac/mac_syscalls.c
@@ -256,6 +256,7 @@ mac_init(void)
 
 	LIST_INIT(&mac_static_policy_list);
 	LIST_INIT(&mac_policy_list);
+	mac_labelzone_init();
 
 	mtx_init(&mac_policy_mtx, "mac_policy_mtx", NULL, MTX_DEF);
 	cv_init(&mac_policy_cv, "mac_policy_cv");
@@ -565,7 +566,7 @@ __mac_get_pid(struct thread *td, struct __mac_get_pid_args *uap)
 	}
 
 	buffer = malloc(mac.m_buflen, M_MACTEMP, M_WAITOK | M_ZERO);
-	error = mac_externalize_cred_label(&tcred->cr_label, elements,
+	error = mac_externalize_cred_label(tcred->cr_label, elements,
 	    buffer, mac.m_buflen);
 	if (error == 0)
 		error = copyout(buffer, mac.m_string, strlen(buffer)+1);
@@ -602,7 +603,7 @@ __mac_get_proc(struct thread *td, struct __mac_get_proc_args *uap)
 	}
 
 	buffer = malloc(mac.m_buflen, M_MACTEMP, M_WAITOK | M_ZERO);
-	error = mac_externalize_cred_label(&td->td_ucred->cr_label,
+	error = mac_externalize_cred_label(td->td_ucred->cr_label,
 	    elements, buffer, mac.m_buflen);
 	if (error == 0)
 		error = copyout(buffer, mac.m_string, strlen(buffer)+1);
@@ -619,7 +620,7 @@ int
 __mac_set_proc(struct thread *td, struct __mac_set_proc_args *uap)
 {
 	struct ucred *newcred, *oldcred;
-	struct label intlabel;
+	struct label *intlabel;
 	struct proc *p;
 	struct mac mac;
 	char *buffer;
@@ -640,13 +641,11 @@ __mac_set_proc(struct thread *td, struct __mac_set_proc_args *uap)
 		return (error);
 	}
 
-	mac_init_cred_label(&intlabel);
-	error = mac_internalize_cred_label(&intlabel, buffer);
+	intlabel = mac_cred_label_alloc();
+	error = mac_internalize_cred_label(intlabel, buffer);
 	free(buffer, M_MACTEMP);
-	if (error) {
-		mac_destroy_cred_label(&intlabel);
-		return (error);
-	}
+	if (error)
+		goto out;
 
 	newcred = crget();
 
@@ -654,7 +653,7 @@ __mac_set_proc(struct thread *td, struct __mac_set_proc_args *uap)
 	PROC_LOCK(p);
 	oldcred = p->p_ucred;
 
-	error = mac_check_cred_relabel(oldcred, &intlabel);
+	error = mac_check_cred_relabel(oldcred, intlabel);
 	if (error) {
 		PROC_UNLOCK(p);
 		crfree(newcred);
@@ -663,7 +662,7 @@ __mac_set_proc(struct thread *td, struct __mac_set_proc_args *uap)
 
 	setsugid(p);
 	crcopy(newcred, oldcred);
-	mac_relabel_cred(newcred, &intlabel);
+	mac_relabel_cred(newcred, intlabel);
 	p->p_ucred = newcred;
 
 	/*
@@ -683,7 +682,7 @@ __mac_set_proc(struct thread *td, struct __mac_set_proc_args *uap)
 	crfree(oldcred);
 
 out:
-	mac_destroy_cred_label(&intlabel);
+	mac_cred_label_free(intlabel);
 	return (error);
 }
 
@@ -694,7 +693,7 @@ int
 __mac_get_fd(struct thread *td, struct __mac_get_fd_args *uap)
 {
 	char *elements, *buffer;
-	struct label intlabel;
+	struct label *intlabel;
 	struct file *fp;
 	struct mac mac;
 	struct vnode *vp;
@@ -729,20 +728,20 @@ __mac_get_fd(struct thread *td, struct __mac_get_fd_args *uap)
 	case DTYPE_VNODE:
 		vp = fp->f_vnode;
 
-		mac_init_vnode_label(&intlabel);
+		intlabel = mac_vnode_label_alloc();
 
 		vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
-		mac_copy_vnode_label(&vp->v_label, &intlabel);
+		mac_copy_vnode_label(vp->v_label, intlabel);
 		VOP_UNLOCK(vp, 0, td);
 
 		break;
 	case DTYPE_PIPE:
 		pipe = fp->f_data;
 
-		mac_init_pipe_label(&intlabel);
+		intlabel = mac_pipe_label_alloc();
 
 		PIPE_LOCK(pipe);
-		mac_copy_pipe_label(pipe->pipe_label, &intlabel);
+		mac_copy_pipe_label(pipe->pipe_label, intlabel);
 		PIPE_UNLOCK(pipe);
 		break;
 	default:
@@ -756,14 +755,14 @@ __mac_get_fd(struct thread *td, struct __mac_get_fd_args *uap)
 	case DTYPE_FIFO:
 	case DTYPE_VNODE:
 		if (error == 0)
-			error = mac_externalize_vnode_label(&intlabel,
+			error = mac_externalize_vnode_label(intlabel,
 			    elements, buffer, mac.m_buflen);
-		mac_destroy_vnode_label(&intlabel);
+		mac_vnode_label_free(intlabel);
 		break;
 	case DTYPE_PIPE:
-		error = mac_externalize_pipe_label(&intlabel, elements,
+		error = mac_externalize_pipe_label(intlabel, elements,
 		    buffer, mac.m_buflen);
-		mac_destroy_pipe_label(&intlabel);
+		mac_pipe_label_free(intlabel);
 		break;
 	default:
 		panic("__mac_get_fd: corrupted label_type");
@@ -788,7 +787,7 @@ __mac_get_file(struct thread *td, struct __mac_get_file_args *uap)
 {
 	char *elements, *buffer;
 	struct nameidata nd;
-	struct label intlabel;
+	struct label *intlabel;
 	struct mac mac;
 	int error;
 
@@ -815,13 +814,13 @@ __mac_get_file(struct thread *td, struct __mac_get_file_args *uap)
 	if (error)
 		goto out;
 
-	mac_init_vnode_label(&intlabel);
-	mac_copy_vnode_label(&nd.ni_vp->v_label, &intlabel);
-	error = mac_externalize_vnode_label(&intlabel, elements, buffer,
+	intlabel = mac_vnode_label_alloc();
+	mac_copy_vnode_label(nd.ni_vp->v_label, intlabel);
+	error = mac_externalize_vnode_label(intlabel, elements, buffer,
 	    mac.m_buflen);
 
 	NDFREE(&nd, 0);
-	mac_destroy_vnode_label(&intlabel);
+	mac_vnode_label_free(intlabel);
 
 	if (error == 0)
 		error = copyout(buffer, mac.m_string, strlen(buffer)+1);
@@ -843,7 +842,7 @@ __mac_get_link(struct thread *td, struct __mac_get_link_args *uap)
 {
 	char *elements, *buffer;
 	struct nameidata nd;
-	struct label intlabel;
+	struct label *intlabel;
 	struct mac mac;
 	int error;
 
@@ -870,12 +869,12 @@ __mac_get_link(struct thread *td, struct __mac_get_link_args *uap)
 	if (error)
 		goto out;
 
-	mac_init_vnode_label(&intlabel);
-	mac_copy_vnode_label(&nd.ni_vp->v_label, &intlabel);
-	error = mac_externalize_vnode_label(&intlabel, elements, buffer,
+	intlabel = mac_vnode_label_alloc();
+	mac_copy_vnode_label(nd.ni_vp->v_label, intlabel);
+	error = mac_externalize_vnode_label(intlabel, elements, buffer,
 	    mac.m_buflen);
 	NDFREE(&nd, 0);
-	mac_destroy_vnode_label(&intlabel);
+	mac_vnode_label_free(intlabel);
 
 	if (error == 0)
 		error = copyout(buffer, mac.m_string, strlen(buffer)+1);
@@ -895,7 +894,7 @@ out:
 int
 __mac_set_fd(struct thread *td, struct __mac_set_fd_args *uap)
 {
-	struct label intlabel;
+	struct label *intlabel;
 	struct pipe *pipe;
 	struct file *fp;
 	struct mount *mp;
@@ -928,40 +927,40 @@ __mac_set_fd(struct thread *td, struct __mac_set_fd_args *uap)
 	switch (fp->f_type) {
 	case DTYPE_FIFO:
 	case DTYPE_VNODE:
-		mac_init_vnode_label(&intlabel);
-		error = mac_internalize_vnode_label(&intlabel, buffer);
+		intlabel = mac_vnode_label_alloc();
+		error = mac_internalize_vnode_label(intlabel, buffer);
 		if (error) {
-			mac_destroy_vnode_label(&intlabel);
+			mac_vnode_label_free(intlabel);
 			break;
 		}
 
 		vp = fp->f_vnode;
 		error = vn_start_write(vp, &mp, V_WAIT | PCATCH);
 		if (error != 0) {
-			mac_destroy_vnode_label(&intlabel);
+			mac_vnode_label_free(intlabel);
 			break;
 		}
 
 		vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
-		error = vn_setlabel(vp, &intlabel, td->td_ucred);
+		error = vn_setlabel(vp, intlabel, td->td_ucred);
 		VOP_UNLOCK(vp, 0, td);
 		vn_finished_write(mp);
 
-		mac_destroy_vnode_label(&intlabel);
+		mac_vnode_label_free(intlabel);
 		break;
 
 	case DTYPE_PIPE:
-		mac_init_pipe_label(&intlabel);
-		error = mac_internalize_pipe_label(&intlabel, buffer);
+		intlabel = mac_pipe_label_alloc();
+		error = mac_internalize_pipe_label(intlabel, buffer);
 		if (error == 0) {
 			pipe = fp->f_data;
 			PIPE_LOCK(pipe);
 			error = mac_pipe_label_set(td->td_ucred, pipe,
-			    &intlabel);
+			    intlabel);
 			PIPE_UNLOCK(pipe);
 		}
 
-		mac_destroy_pipe_label(&intlabel);
+		mac_pipe_label_free(intlabel);
 		break;
 
 	default:
@@ -983,7 +982,7 @@ out:
 int
 __mac_set_file(struct thread *td, struct __mac_set_file_args *uap)
 {
-	struct label intlabel;
+	struct label *intlabel;
 	struct nameidata nd;
 	struct mount *mp;
 	struct mac mac;
@@ -1005,13 +1004,11 @@ __mac_set_file(struct thread *td, struct __mac_set_file_args *uap)
 		return (error);
 	}
 
-	mac_init_vnode_label(&intlabel);
-	error = mac_internalize_vnode_label(&intlabel, buffer);
+	intlabel = mac_vnode_label_alloc();
+	error = mac_internalize_vnode_label(intlabel, buffer);
 	free(buffer, M_MACTEMP);
-	if (error) {
-		mac_destroy_vnode_label(&intlabel);
-		return (error);
-	}
+	if (error)
+		goto out;
 
 	mtx_lock(&Giant);				/* VFS */
 
@@ -1021,15 +1018,15 @@ __mac_set_file(struct thread *td, struct __mac_set_file_args *uap)
 	if (error == 0) {
 		error = vn_start_write(nd.ni_vp, &mp, V_WAIT | PCATCH);
 		if (error == 0)
-			error = vn_setlabel(nd.ni_vp, &intlabel,
+			error = vn_setlabel(nd.ni_vp, intlabel,
 			    td->td_ucred);
 		vn_finished_write(mp);
 	}
 
 	NDFREE(&nd, 0);
 	mtx_unlock(&Giant);				/* VFS */
-	mac_destroy_vnode_label(&intlabel);
-
+out:
+	mac_vnode_label_free(intlabel);
 	return (error);
 }
 
@@ -1039,7 +1036,7 @@ __mac_set_file(struct thread *td, struct __mac_set_file_args *uap)
 int
 __mac_set_link(struct thread *td, struct __mac_set_link_args *uap)
 {
-	struct label intlabel;
+	struct label *intlabel;
 	struct nameidata nd;
 	struct mount *mp;
 	struct mac mac;
@@ -1061,13 +1058,11 @@ __mac_set_link(struct thread *td, struct __mac_set_link_args *uap)
 		return (error);
 	}
 
-	mac_init_vnode_label(&intlabel);
-	error = mac_internalize_vnode_label(&intlabel, buffer);
+	intlabel = mac_vnode_label_alloc();
+	error = mac_internalize_vnode_label(intlabel, buffer);
 	free(buffer, M_MACTEMP);
-	if (error) {
-		mac_destroy_vnode_label(&intlabel);
-		return (error);
-	}
+	if (error)
+		goto out;
 
 	mtx_lock(&Giant);				/* VFS */
 
@@ -1077,15 +1072,15 @@ __mac_set_link(struct thread *td, struct __mac_set_link_args *uap)
 	if (error == 0) {
 		error = vn_start_write(nd.ni_vp, &mp, V_WAIT | PCATCH);
 		if (error == 0)
-			error = vn_setlabel(nd.ni_vp, &intlabel,
+			error = vn_setlabel(nd.ni_vp, intlabel,
 			    td->td_ucred);
 		vn_finished_write(mp);
 	}
 
 	NDFREE(&nd, 0);
 	mtx_unlock(&Giant);				/* VFS */
-	mac_destroy_vnode_label(&intlabel);
-
+out:
+	mac_vnode_label_free(intlabel);
 	return (error);
 }