From: bluhm <bluhm@openbsd.org>
Date: Thu, 5 Oct 2023 11:08:56 +0000 (+0000)
Subject: Protect interface queues with read once and mutex.
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=37a618ff0e3b8e2e9e04053f139425739064f885;p=openbsd

Protect interface queues with read once and mutex.

Reading atomic values need at least read once and writing values
should have a mutex.  This is what mbuf queues already do.  Add
READ_ONCE() to ifq and ifiq macros for len and empty.  Convert
ifq_set_maxlen() to a function that grabs ifq_mtx.

OK mvs@
---

diff --git a/sys/net/ifq.c b/sys/net/ifq.c
index 81aa5b9a61f..7255f449ba3 100644
--- a/sys/net/ifq.c
+++ b/sys/net/ifq.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ifq.c,v 1.50 2023/07/30 05:39:52 dlg Exp $ */
+/*	$OpenBSD: ifq.c,v 1.51 2023/10/05 11:08:56 bluhm Exp $ */
 
 /*
  * Copyright (c) 2015 David Gwynne <dlg@openbsd.org>
@@ -529,6 +529,14 @@ ifq_hdatalen(struct ifqueue *ifq)
 	return (len);
 }
 
+void
+ifq_set_maxlen(struct ifqueue *ifq, unsigned int maxlen)
+{
+	mtx_enter(&ifq->ifq_mtx);
+	ifq->ifq_maxlen = maxlen;
+	mtx_leave(&ifq->ifq_mtx);
+}
+
 unsigned int
 ifq_purge(struct ifqueue *ifq)
 {
diff --git a/sys/net/ifq.h b/sys/net/ifq.h
index c32a635a835..d15af37b45f 100644
--- a/sys/net/ifq.h
+++ b/sys/net/ifq.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ifq.h,v 1.38 2023/07/30 05:39:52 dlg Exp $ */
+/*	$OpenBSD: ifq.h,v 1.39 2023/10/05 11:08:56 bluhm Exp $ */
 
 /*
  * Copyright (c) 2015 David Gwynne <dlg@openbsd.org>
@@ -435,6 +435,7 @@ void		 ifq_deq_commit(struct ifqueue *, struct mbuf *);
 void		 ifq_deq_rollback(struct ifqueue *, struct mbuf *);
 struct mbuf	*ifq_dequeue(struct ifqueue *);
 int		 ifq_hdatalen(struct ifqueue *);
+void		 ifq_set_maxlen(struct ifqueue *, unsigned int);
 void		 ifq_mfreem(struct ifqueue *, struct mbuf *);
 void		 ifq_mfreeml(struct ifqueue *, struct mbuf_list *);
 unsigned int	 ifq_purge(struct ifqueue *);
@@ -448,9 +449,8 @@ int		 ifq_deq_sleep(struct ifqueue *, struct mbuf **, int, int,
 		     const char *, volatile unsigned int *,
 		     volatile unsigned int *);
 
-#define	ifq_len(_ifq)			((_ifq)->ifq_len)
-#define	ifq_empty(_ifq)			(ifq_len(_ifq) == 0)
-#define	ifq_set_maxlen(_ifq, _l)	((_ifq)->ifq_maxlen = (_l))
+#define ifq_len(_ifq)		READ_ONCE((_ifq)->ifq_len)
+#define ifq_empty(_ifq)		(ifq_len(_ifq) == 0)
 
 static inline int
 ifq_is_priq(struct ifqueue *ifq)
@@ -490,8 +490,8 @@ int		 ifiq_input(struct ifiqueue *, struct mbuf_list *);
 int		 ifiq_enqueue(struct ifiqueue *, struct mbuf *);
 void		 ifiq_add_data(struct ifiqueue *, struct if_data *);
 
-#define	ifiq_len(_ifiq)			ml_len(&(_ifiq)->ifiq_ml)
-#define	ifiq_empty(_ifiq)		ml_empty(&(_ifiq)->ifiq_ml)
+#define ifiq_len(_ifiq)		READ_ONCE(ml_len(&(_ifiq)->ifiq_ml))
+#define ifiq_empty(_ifiq)	(ifiq_len(_ifiq) == 0)
 
 #endif /* _KERNEL */