svn commit: r259681 - head/sys/netgraph

[Gleb Smirnoff]

Author: glebius
Date: Sat Dec 21 14:41:32 2013
New Revision: 259681
URL: http://svnweb.freebsd.org/changeset/base/259681

Log:
  In r248885 I have reduced size of fake uio resid that ng_ksocket(4) passes
  to the soreceive(). This exposed a bug. When reading from a raw socket,
  when our fake limit is depleted, we receive a truncated mbuf chain, with
  m->m_pkthdr.len > m_length(m). The first problem is that MSG_TRUNC was not
  handled. The second one is that we didn't reinit uio_resid in our endless
  loop (neither flags), and if socket buffer contained several records, then
  we quickly deplete our fake limit. The third bug, actually introduced in
  r248885, is that MJUMPAGESIZE isn't enough to handle maximum packet that
  ng_ksocket(4) can theoretically receive.
  
  Changes:
  - Reinit uio_resid and flags before every call to soreceive().
  - Set maximum acceptable size of packet to IP_MAXPACKET. As for now the
    module doesn't support INET6.
  - Properly handle MSG_TRUNC return from soreceive().
  
  PR:			184601
  Submitted & tested by:	Viktor Velichkin <avisom yandex.ru>
  Sponsored by:		Nginx, Inc.

Modified:
  head/sys/netgraph/ng_ksocket.c

Modified: head/sys/netgraph/ng_ksocket.c
==============================================================================
--- head/sys/netgraph/ng_ksocket.c	Sat Dec 21 13:58:55 2013	(r259680)
+++ head/sys/netgraph/ng_ksocket.c	Sat Dec 21 14:41:32 2013	(r259681)
@@ -66,6 +66,7 @@
 #include <netgraph/ng_ksocket.h>
 
 #include <netinet/in.h>
+#include <netinet/ip.h>
 #include <netatalk/at.h>
 
 #ifdef NG_SEPARATE_MALLOC
@@ -1043,8 +1044,7 @@ ng_ksocket_incoming2(node_p node, hook_p
 	struct socket *so = arg1;
 	const priv_p priv = NG_NODE_PRIVATE(node);
 	struct ng_mesg *response;
-	struct uio auio;
-	int flags, error;
+	int error;
 
 	KASSERT(so == priv->so, ("%s: wrong socket", __func__));
 
@@ -1093,20 +1093,27 @@ ng_ksocket_incoming2(node_p node, hook_p
 	if (priv->hook == NULL)
 		return;
 
-	/* Read and forward available mbuf's */
-	auio.uio_td = NULL;
-	auio.uio_resid = MJUMPAGESIZE;	/* XXXGL: sane limit? */
-	flags = MSG_DONTWAIT;
+	/* Read and forward available mbufs. */
 	while (1) {
-		struct sockaddr *sa = NULL;
+		struct uio uio;
+		struct sockaddr *sa;
 		struct mbuf *m;
+		int flags;
 
-		/* Try to get next packet from socket */
+		/* Try to get next packet from socket. */
+		uio.uio_td = NULL;
+		uio.uio_resid = IP_MAXPACKET;
+		flags = MSG_DONTWAIT;
+		sa = NULL;
 		if ((error = soreceive(so, (so->so_state & SS_ISCONNECTED) ?
-		    NULL : &sa, &auio, &m, NULL, &flags)) != 0)
+		    NULL : &sa, &uio, &m, NULL, &flags)) != 0)
 			break;
 
-		/* See if we got anything */
+		/* See if we got anything. */
+		if (flags & MSG_TRUNC) {
+			m_freem(m);
+			m = NULL;
+		}
 		if (m == NULL) {
 			if (sa != NULL)
 				free(sa, M_SONAME);