Merge tag 'selinux-pr-20191126' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux

Pull selinux updates from Paul Moore:
 "Only three SELinux patches for v5.5:

   - Remove the size limit on SELinux policies, the limitation was a
     lingering vestige and no longer necessary.

   - Allow file labeling before the policy is loaded. This should ease
     some of the burden when the policy is initially loaded (no need to
     relabel files), but it should also help enable some new system
     concepts which dynamically create the root filesystem in the
     initrd.

   - Add support for the "greatest lower bound" policy construct which
     is defined as the intersection of the MLS range of two SELinux
     labels"

* tag 'selinux-pr-20191126' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
  selinux: default_range glblub implementation
  selinux: allow labeling before policy is loaded
  selinux: remove load size limit

security/selinux/ss/context.h

@@ -95,6 +95,38 @@ out:
 	return rc;
 }
 
+
+static inline int mls_context_glblub(struct context *dst,
+				     struct context *c1, struct context *c2)
+{
+	struct mls_range *dr = &dst->range, *r1 = &c1->range, *r2 = &c2->range;
+	int rc = 0;
+
+	if (r1->level[1].sens < r2->level[0].sens ||
+	    r2->level[1].sens < r1->level[0].sens)
+		/* These ranges have no common sensitivities */
+		return -EINVAL;
+
+	/* Take the greatest of the low */
+	dr->level[0].sens = max(r1->level[0].sens, r2->level[0].sens);
+
+	/* Take the least of the high */
+	dr->level[1].sens = min(r1->level[1].sens, r2->level[1].sens);
+
+	rc = ebitmap_and(&dr->level[0].cat,
+			 &r1->level[0].cat, &r2->level[0].cat);
+	if (rc)
+		goto out;
+
+	rc = ebitmap_and(&dr->level[1].cat,
+			 &r1->level[1].cat, &r2->level[1].cat);
+	if (rc)
+		goto out;
+
+out:
+	return rc;
+}
+
 static inline int mls_context_cmp(struct context *c1, struct context *c2)
 {
 	return ((c1->range.level[0].sens == c2->range.level[0].sens) &&

security/selinux/ss/ebitmap.c

@@ -77,6 +77,24 @@ int ebitmap_cpy(struct ebitmap *dst, struct ebitmap *src)
 	return 0;
 }
 
+int ebitmap_and(struct ebitmap *dst, struct ebitmap *e1, struct ebitmap *e2)
+{
+	struct ebitmap_node *n;
+	int bit, rc;
+
+	ebitmap_init(dst);
+
+	ebitmap_for_each_positive_bit(e1, n, bit) {
+		if (ebitmap_get_bit(e2, bit)) {
+			rc = ebitmap_set_bit(dst, bit, 1);
+			if (rc < 0)
+				return rc;
+		}
+	}
+	return 0;
+}
+
+
 #ifdef CONFIG_NETLABEL
 /**
  * ebitmap_netlbl_export - Export an ebitmap into a NetLabel category bitmap

security/selinux/ss/ebitmap.h

@@ -124,6 +124,7 @@ static inline void ebitmap_node_clr_bit(struct ebitmap_node *n,
 
 int ebitmap_cmp(struct ebitmap *e1, struct ebitmap *e2);
 int ebitmap_cpy(struct ebitmap *dst, struct ebitmap *src);
+int ebitmap_and(struct ebitmap *dst, struct ebitmap *e1, struct ebitmap *e2);
 int ebitmap_contains(struct ebitmap *e1, struct ebitmap *e2, u32 last_e2bit);
 int ebitmap_get_bit(struct ebitmap *e, unsigned long bit);
 int ebitmap_set_bit(struct ebitmap *e, unsigned long bit, int value);

security/selinux/ss/mls.c

@@ -529,6 +529,9 @@ int mls_compute_sid(struct policydb *p,
 			return mls_context_cpy_high(newcontext, tcontext);
 		case DEFAULT_TARGET_LOW_HIGH:
 			return mls_context_cpy(newcontext, tcontext);
+		case DEFAULT_GLBLUB:
+			return mls_context_glblub(newcontext,
+						  scontext, tcontext);
 		}
 
 		/* Fallthrough */

security/selinux/ss/policydb.c

@@ -160,6 +160,11 @@ static struct policydb_compat_info policydb_compat[] = {
 		.sym_num	= SYM_NUM,
 		.ocon_num	= OCON_NUM,
 	},
+	{
+		.version	= POLICYDB_VERSION_GLBLUB,
+		.sym_num	= SYM_NUM,
+		.ocon_num	= OCON_NUM,
+	},
 };
 
 static struct policydb_compat_info *policydb_lookup_compat(int version)

security/selinux/ss/policydb.h

@@ -69,6 +69,7 @@ struct class_datum {
 #define DEFAULT_TARGET_LOW     4
 #define DEFAULT_TARGET_HIGH    5
 #define DEFAULT_TARGET_LOW_HIGH        6
+#define DEFAULT_GLBLUB		7
 	char default_range;
 };