From: David Hill <dhill@mindcry.org>
Subject: Re: wireguard - prepend mbuf allocations
To: tech@openbsd.org
Date: Sat, 28 Sep 2024 10:47:33 -0400

Something like this?


Index: net/if_wg.c
===================================================================
RCS file: /cvs/src/sys/net/if_wg.c,v
retrieving revision 1.38
diff -u -p -r1.38 if_wg.c
--- net/if_wg.c	9 Apr 2024 12:53:08 -0000	1.38
+++ net/if_wg.c	28 Sep 2024 14:46:51 -0000
@@ -860,10 +860,14 @@ wg_send_buf(struct wg_softc *sc, struct
  {
  	struct mbuf	*m;
  	int		 ret = 0;
+	size_t		 mlen = len + max_hdr;

  retry:
  	m = m_gethdr(M_WAIT, MT_DATA);
+	if (mlen > MHLEN)
+		MCLGETL(m, M_WAIT, mlen);
  	m->m_len = 0;
+	m_align(m, len);
  	m_copyback(m, 0, len, buf, M_WAIT);

  	/* As we're sending a handshake packet here, we want high priority */
@@ -1522,8 +1526,9 @@ wg_encap(struct wg_softc *sc, struct mbu
  	 * noise_remote_encrypt about mbufs, but we would need to sort out the
  	 * p_encap_queue situation first.
  	 */
-	if ((mc = m_clget(NULL, M_NOWAIT, out_len)) == NULL)
+	if ((mc = m_clget(NULL, M_NOWAIT, out_len + max_hdr)) == NULL)
  		goto error;
+	m_align(mc, out_len);

  	data = mtod(mc, struct wg_pkt_data *);
  	m_copydata(m, 0, m->m_pkthdr.len, data->buf);