SELinux: add boundary support and thread context assignment

The purpose of this patch is to assign per-thread security context
under a constraint. It enables multi-threaded server application
to kick a request handler with its fair security context, and
helps some of userspace object managers to handle user's request.

When we assign a per-thread security context, it must not have wider
permissions than the original one. Because a multi-threaded process
shares a single local memory, an arbitary per-thread security context
also means another thread can easily refer violated information.

The constraint on a per-thread security context requires a new domain
has to be equal or weaker than its original one, when it tries to assign
a per-thread security context.

Bounds relationship between two types is a way to ensure a domain can
never have wider permission than its bounds. We can define it in two
explicit or implicit ways.

The first way is using new TYPEBOUNDS statement. It enables to define
a boundary of types explicitly. The other one expand the concept of
existing named based hierarchy. If we defines a type with "." separated
name like "httpd_t.php", toolchain implicitly set its bounds on "httpd_t".

This feature requires a new policy version.
The 24th version (POLICYDB_VERSION_BOUNDARY) enables to ship them into
kernel space, and the following patch enables to handle it.

Signed-off-by: KaiGai Kohei <kaigai@ak.jp.nec.com>
Acked-by:  Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 5 insertions, 0 deletions

diff --git a/security/selinux/ss/policydb.h b/security/selinux/ss/policydb.h
index 4253370fda6a..55152d498b53 100644
--- a/security/selinux/ss/policydb.h
+++ b/security/selinux/ss/policydb.h
@@ -61,6 +61,7 @@ struct class_datum {
 /* Role attributes */
 struct role_datum {
 	u32 value;			/* internal role value */
+	u32 bounds;			/* boundary of role */
 	struct ebitmap dominates;	/* set of roles dominated by this role */
 	struct ebitmap types;		/* set of authorized types for role */
 };
@@ -81,12 +82,15 @@ struct role_allow {
 /* Type attributes */
 struct type_datum {
 	u32 value;		/* internal type value */
+	u32 bounds;		/* boundary of type */
 	unsigned char primary;	/* primary name? */
+	unsigned char attribute;/* attribute ?*/
 };
 
 /* User attributes */
 struct user_datum {
 	u32 value;			/* internal user value */
+	u32 bounds;			/* bounds of user */
 	struct ebitmap roles;		/* set of authorized roles for user */
 	struct mls_range range;		/* MLS range (min - max) for user */
 	struct mls_level dfltlevel;	/* default login MLS level for user */
@@ -209,6 +213,7 @@ struct policydb {
 	struct class_datum **class_val_to_struct;
 	struct role_datum **role_val_to_struct;
 	struct user_datum **user_val_to_struct;
+	struct type_datum **type_val_to_struct;
 
 	/* type enforcement access vectors and transitions */
 	struct avtab te_avtab;