1 files changed, 81 insertions, 45 deletions

diff --git a/security/selinux/avc.c b/security/selinux/avc.c
index dca1c22d927..1a70fa26da7 100644
--- a/security/selinux/avc.c
+++ b/security/selinux/avc.c
@@ -457,6 +457,42 @@ static void avc_audit_post_callback(struct audit_buffer *ab, void *a)
 			   ad->selinux_audit_data.tclass);
 }
 
+/* This is the slow part of avc audit with big stack footprint */
+static noinline int slow_avc_audit(u32 ssid, u32 tsid, u16 tclass,
+		u32 requested, u32 audited, u32 denied,
+		struct av_decision *avd, struct common_audit_data *a,
+		unsigned flags)
+{
+	struct common_audit_data stack_data;
+
+	if (!a) {
+		a = &stack_data;
+		COMMON_AUDIT_DATA_INIT(a, NONE);
+	}
+
+	/*
+	 * When in a RCU walk do the audit on the RCU retry.  This is because
+	 * the collection of the dname in an inode audit message is not RCU
+	 * safe.  Note this may drop some audits when the situation changes
+	 * during retry. However this is logically just as if the operation
+	 * happened a little later.
+	 */
+	if ((a->type == LSM_AUDIT_DATA_INODE) &&
+	    (flags & MAY_NOT_BLOCK))
+		return -ECHILD;
+
+	a->selinux_audit_data.tclass = tclass;
+	a->selinux_audit_data.requested = requested;
+	a->selinux_audit_data.ssid = ssid;
+	a->selinux_audit_data.tsid = tsid;
+	a->selinux_audit_data.audited = audited;
+	a->selinux_audit_data.denied = denied;
+	a->lsm_pre_audit = avc_audit_pre_callback;
+	a->lsm_post_audit = avc_audit_post_callback;
+	common_lsm_audit(a);
+	return 0;
+}
+
 /**
  * avc_audit - Audit the granting or denial of permissions.
  * @ssid: source security identifier
@@ -477,15 +513,14 @@ static void avc_audit_post_callback(struct audit_buffer *ab, void *a)
  * be performed under a lock, to allow the lock to be released
  * before calling the auditing code.
  */
-int avc_audit(u32 ssid, u32 tsid,
+inline int avc_audit(u32 ssid, u32 tsid,
 	       u16 tclass, u32 requested,
 	       struct av_decision *avd, int result, struct common_audit_data *a,
 	       unsigned flags)
 {
-	struct common_audit_data stack_data;
 	u32 denied, audited;
 	denied = requested & ~avd->allowed;
-	if (denied) {
+	if (unlikely(denied)) {
 		audited = denied & avd->auditdeny;
 		/*
 		 * a->selinux_audit_data.auditdeny is TRICKY!  Setting a bit in
@@ -511,35 +546,12 @@ int avc_audit(u32 ssid, u32 tsid,
 		audited = denied = requested;
 	else
 		audited = requested & avd->auditallow;
-	if (!audited)
+	if (likely(!audited))
 		return 0;
 
-	if (!a) {
-		a = &stack_data;
-		COMMON_AUDIT_DATA_INIT(a, NONE);
-	}
-
-	/*
-	 * When in a RCU walk do the audit on the RCU retry.  This is because
-	 * the collection of the dname in an inode audit message is not RCU
-	 * safe.  Note this may drop some audits when the situation changes
-	 * during retry. However this is logically just as if the operation
-	 * happened a little later.
-	 */
-	if ((a->type == LSM_AUDIT_DATA_INODE) &&
-	    (flags & MAY_NOT_BLOCK))
-		return -ECHILD;
-
-	a->selinux_audit_data.tclass = tclass;
-	a->selinux_audit_data.requested = requested;
-	a->selinux_audit_data.ssid = ssid;
-	a->selinux_audit_data.tsid = tsid;
-	a->selinux_audit_data.audited = audited;
-	a->selinux_audit_data.denied = denied;
-	a->lsm_pre_audit = avc_audit_pre_callback;
-	a->lsm_post_audit = avc_audit_post_callback;
-	common_lsm_audit(a);
-	return 0;
+	return slow_avc_audit(ssid, tsid, tclass,
+		requested, audited, denied,
+		avd, a, flags);
 }
 
 /**
@@ -729,6 +741,41 @@ int avc_ss_reset(u32 seqno)
 	return rc;
 }
 
+/*
+ * Slow-path helper function for avc_has_perm_noaudit,
+ * when the avc_node lookup fails. We get called with
+ * the RCU read lock held, and need to return with it
+ * still held, but drop if for the security compute.
+ *
+ * Don't inline this, since it's the slow-path and just
+ * results in a bigger stack frame.
+ */
+static noinline struct avc_node *avc_compute_av(u32 ssid, u32 tsid,
+			 u16 tclass, struct av_decision *avd)
+{
+	rcu_read_unlock();
+	security_compute_av(ssid, tsid, tclass, avd);
+	rcu_read_lock();
+	return avc_insert(ssid, tsid, tclass, avd);
+}
+
+static noinline int avc_denied(u32 ssid, u32 tsid,
+			 u16 tclass, u32 requested,
+			 unsigned flags,
+			 struct av_decision *avd)
+{
+	if (flags & AVC_STRICT)
+		return -EACCES;
+
+	if (selinux_enforcing && !(avd->flags & AVD_FLAGS_PERMISSIVE))
+		return -EACCES;
+
+	avc_update_node(AVC_CALLBACK_GRANT, requested, ssid,
+				tsid, tclass, avd->seqno);
+	return 0;
+}
+
+
 /**
  * avc_has_perm_noaudit - Check permissions but perform no auditing.
  * @ssid: source security identifier
@@ -749,7 +796,7 @@ int avc_ss_reset(u32 seqno)
  * auditing, e.g. in cases where a lock must be held for the check but
  * should be released for the auditing.
  */
-int avc_has_perm_noaudit(u32 ssid, u32 tsid,
+inline int avc_has_perm_noaudit(u32 ssid, u32 tsid,
 			 u16 tclass, u32 requested,
 			 unsigned flags,
 			 struct av_decision *avd)
@@ -764,26 +811,15 @@ int avc_has_perm_noaudit(u32 ssid, u32 tsid,
 
 	node = avc_lookup(ssid, tsid, tclass);
 	if (unlikely(!node)) {
-		rcu_read_unlock();
-		security_compute_av(ssid, tsid, tclass, avd);
-		rcu_read_lock();
-		node = avc_insert(ssid, tsid, tclass, avd);
+		node = avc_compute_av(ssid, tsid, tclass, avd);
 	} else {
 		memcpy(avd, &node->ae.avd, sizeof(*avd));
 		avd = &node->ae.avd;
 	}
 
 	denied = requested & ~(avd->allowed);
-
-	if (denied) {
-		if (flags & AVC_STRICT)
-			rc = -EACCES;
-		else if (!selinux_enforcing || (avd->flags & AVD_FLAGS_PERMISSIVE))
-			avc_update_node(AVC_CALLBACK_GRANT, requested, ssid,
-					tsid, tclass, avd->seqno);
-		else
-			rc = -EACCES;
-	}
+	if (unlikely(denied))
+		rc = avc_denied(ssid, tsid, tclass, requested, flags, avd);
 
 	rcu_read_unlock();
 	return rc;