audit: deprecate the AUDIT_FILTER_ENTRY filter

The audit entry filter has been long deprecated with userspace support
finally removed in audit-v2.6.7 and plans to remove kernel support have
existed since kernel-v2.6.31.
Remove it.

Since removing the audit entry filter, test for early return before
setting up any context state.

Passes audit-testsuite.

See: https://github.com/linux-audit/audit-kernel/issues/6

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

kernel/auditfilter.c

@@ -258,8 +258,8 @@ static inline struct audit_entry *audit_to_entry_common(struct audit_rule_data *
 		goto exit_err;
 #ifdef CONFIG_AUDITSYSCALL
 	case AUDIT_FILTER_ENTRY:
-		if (rule->action == AUDIT_ALWAYS)
-			goto exit_err;
+		pr_err("AUDIT_FILTER_ENTRY is deprecated\n");
+		goto exit_err;
 	case AUDIT_FILTER_EXIT:
 	case AUDIT_FILTER_TASK:
 #endif

kernel/auditsc.c

@@ -1519,22 +1519,23 @@ void __audit_syscall_entry(int major, unsigned long a1, unsigned long a2,
 	if (!audit_enabled)
 		return;
 
+	state = context->state;
+	if (state == AUDIT_DISABLED)
+		return;
+
+	context->dummy = !audit_n_rules;
+	if (!context->dummy && state == AUDIT_BUILD_CONTEXT) {
+		context->prio = 0;
+		if (auditd_test_task(tsk))
+			return;
+	}
+
 	context->arch	    = syscall_get_arch();
 	context->major      = major;
 	context->argv[0]    = a1;
 	context->argv[1]    = a2;
 	context->argv[2]    = a3;
 	context->argv[3]    = a4;
-
-	state = context->state;
-	context->dummy = !audit_n_rules;
-	if (!context->dummy && state == AUDIT_BUILD_CONTEXT) {
-		context->prio = 0;
-		state = audit_filter_syscall(tsk, context, &audit_filter_list[AUDIT_FILTER_ENTRY]);
-	}
-	if (state == AUDIT_DISABLED)
-		return;
-
 	context->serial     = 0;
 	context->ctime = current_kernel_time64();
 	context->in_syscall = 1;