apparmor: carry mediation check on label

In order to speed up the mediated check, precompute and store the
result as a bit per class type. This will not only allow us to
speed up the mediation check but is also a step to removing the
unconfined special cases as the unconfined check can be replaced
with the generic label_mediates() check.

Note: label check does not currently work for capabilities and resources
      which need to have their mediation updated first.

Signed-off-by: John Johansen <john.johansen@canonical.com>

3 files changed, 25 insertions, 13 deletions

diff --git a/security/apparmor/include/apparmor.h b/security/apparmor/include/apparmor.h
index 56767b1a8f06..dd12cba8139d 100644
--- a/security/apparmor/include/apparmor.h
+++ b/security/apparmor/include/apparmor.h
@@ -38,6 +38,7 @@
 #define AA_CLASS_X		31
 #define AA_CLASS_DBUS		32
 
+/* NOTE: if AA_CLASS_LAST > 63 need to update label->mediates */
 #define AA_CLASS_LAST		AA_CLASS_DBUS
 
 /* Control parameters settable through module/boot flags */
diff --git a/security/apparmor/include/label.h b/security/apparmor/include/label.h
index 93290ae300bb..5e7d199c15e2 100644
--- a/security/apparmor/include/label.h
+++ b/security/apparmor/include/label.h
@@ -129,6 +129,7 @@ struct aa_label {
 	long flags;
 	u32 secid;
 	int size;
+	u64 mediates;
 	struct aa_profile *vec[];
 };
 
@@ -231,20 +232,17 @@ int aa_label_next_confined(struct aa_label *l, int i);
 #define fn_for_each_not_in_set(L1, L2, P, FN)				\
 	fn_for_each2_XXX((L1), (L2), P, FN, _not_in_set)
 
-#define LABEL_MEDIATES(L, C)						\
-({									\
-	struct aa_profile *profile;					\
-	struct label_it i;						\
-	int ret = 0;							\
-	label_for_each(i, (L), profile) {				\
-		if (RULE_MEDIATES(&profile->rules, (C))) {		\
-			ret = 1;					\
-			break;						\
-		}							\
-	}								\
-	ret;								\
-})
+static inline bool label_mediates(struct aa_label *L, unsigned char C)
+{
+	return (L)->mediates & (((u64) 1) << (C));
+}
 
+static inline bool label_mediates_safe(struct aa_label *L, unsigned char C)
+{
+	if (C > AA_CLASS_LAST)
+		return false;
+	return label_mediates(L, C);
+}
 
 void aa_labelset_destroy(struct aa_labelset *ls);
 void aa_labelset_init(struct aa_labelset *ls);
diff --git a/security/apparmor/include/policy.h b/security/apparmor/include/policy.h
index 757e3c232c57..256fb27e5c3a 100644
--- a/security/apparmor/include/policy.h
+++ b/security/apparmor/include/policy.h
@@ -318,6 +318,19 @@ static inline aa_state_t ANY_RULE_MEDIATES(struct list_head *head,
 	return RULE_MEDIATES(rule, class);
 }
 
+void aa_compute_profile_mediates(struct aa_profile *profile);
+static inline bool profile_mediates(struct aa_profile *profile,
+				    unsigned char class)
+{
+	return label_mediates(&profile->label, class);
+}
+
+static inline bool profile_mediates_safe(struct aa_profile *profile,
+					 unsigned char class)
+{
+	return label_mediates_safe(&profile->label, class);
+}
+
 /**
  * aa_get_profile - increment refcount on profile @p
  * @p: profile  (MAYBE NULL)