Re: so_rerror

[christos%astron.com@localhost (Christos Zoulas)]

In article <20181103201927.008EA17FDA1%rebar.astron.com@localhost>,
Christos Zoulas <christos%zoulas.com@localhost> wrote:
>On Nov 3,  8:23pm, martin%duskware.de@localhost (Martin Husemann) wrote:
>-- Subject: Re: so_rerror
>
>| On Sat, Nov 03, 2018 at 06:53:49PM +0000, Christos Zoulas wrote:
>| 
>| > @@ -537,6 +538,7 @@
>| >  	so->so_proto = prp;
>| >  	so->so_send = sosend;
>| >  	so->so_receive = soreceive;
>| > +	so->so_options = sooptions;
>| >  #ifdef MBUFTRACE
>| >  	so->so_rcv.sb_mowner = &prp->pr_domain->dom_mowner;
>| >  	so->so_snd.sb_mowner = &prp->pr_domain->dom_mowner;
>| 
>| 
>| I think we need to mask sooptions here or with an accessor function
>| when using the sysctl to write the value. It is likely not a good idea
>| to set e.g. "there is an accept filter running" to on when this is a lie.
>| 
>| Maybe we should instead do a boolean sysctl and just set the single bit 
>| in sooptions?
>
>I know, I thought about that but then I decided it was simpler and
>more functional to allow everything. I guess I can filter out the
>ones that don't make sense... Stay tuned.
>

Here's a patch that only allows the options that could be useful.

christos

Index: kern/uipc_socket.c
===================================================================
RCS file: /cvsroot/src/sys/kern/uipc_socket.c,v
retrieving revision 1.265
diff -u -u -r1.265 uipc_socket.c
--- kern/uipc_socket.c	3 Sep 2018 16:29:35 -0000	1.265
+++ kern/uipc_socket.c	3 Nov 2018 21:14:53 -0000
@@ -118,6 +118,7 @@
 
 extern const struct fileops socketops;
 
+static int	sooptions;
 extern int	somaxconn;			/* patchable (XXX sysctl) */
 int		somaxconn = SOMAXCONN;
 kmutex_t	*softnet_lock;
@@ -537,6 +538,7 @@
 	so->so_proto = prp;
 	so->so_send = sosend;
 	so->so_receive = soreceive;
+	so->so_options = sooptions;
 #ifdef MBUFTRACE
 	so->so_rcv.sb_mowner = &prp->pr_domain->dom_mowner;
 	so->so_snd.sb_mowner = &prp->pr_domain->dom_mowner;
@@ -1757,6 +1759,7 @@
 	case SO_OOBINLINE:
 	case SO_TIMESTAMP:
 	case SO_NOSIGPIPE:
+	case SO_RERROR:
 #ifdef SO_OTIMESTAMP
 	case SO_OTIMESTAMP:
 #endif
@@ -1958,6 +1961,7 @@
 	case SO_OOBINLINE:
 	case SO_TIMESTAMP:
 	case SO_NOSIGPIPE:
+	case SO_RERROR:
 #ifdef SO_OTIMESTAMP
 	case SO_OTIMESTAMP:
 #endif
@@ -2522,6 +2526,31 @@
 	return (error);
 }
 
+/*
+ * sysctl helper routine for kern.sooptions. Ensures that only allowed
+ * options can be set.
+ */
+static int
+sysctl_kern_sooptions(SYSCTLFN_ARGS)
+{
+	int error, new_options;
+	struct sysctlnode node;
+
+	new_options = sooptions;
+	node = *rnode;
+	node.sysctl_data = &new_options;
+	error = sysctl_lookup(SYSCTLFN_CALL(&node));
+	if (error || newp == NULL)
+		return error;
+
+	if (new_options & ~SO_DEFOPTS)
+		return EINVAL;
+
+	sooptions = new_options;
+
+	return 0;
+}
+
 static void
 sysctl_kern_socket_setup(void)
 {
@@ -2542,4 +2571,11 @@
 		       SYSCTL_DESCR("Maximum socket buffer size"),
 		       sysctl_kern_sbmax, 0, NULL, 0,
 		       CTL_KERN, KERN_SBMAX, CTL_EOL);
+
+	sysctl_createv(&socket_sysctllog, 0, NULL, NULL,
+		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
+		       CTLTYPE_INT, "sooptions",
+		       SYSCTL_DESCR("Default socket options"),
+		       sysctl_kern_sooptions, 0, NULL, 0,
+		       CTL_KERN, CTL_CREATE, CTL_EOL);
 }
Index: kern/uipc_socket2.c
===================================================================
RCS file: /cvsroot/src/sys/kern/uipc_socket2.c,v
retrieving revision 1.132
diff -u -u -r1.132 uipc_socket2.c
--- kern/uipc_socket2.c	3 Sep 2018 16:29:35 -0000	1.132
+++ kern/uipc_socket2.c	3 Nov 2018 21:14:53 -0000
@@ -509,8 +509,10 @@
 	KASSERT(solocked(so));
 
 	so->so_rcv.sb_overflowed++;
-	so->so_rerror = ENOBUFS;
-	sorwakeup(so);
+	if (so->so_options & SO_RERROR)  {
+		so->so_rerror = ENOBUFS;
+		sorwakeup(so);
+	}
 }
 
 /*
Index: sys/socket.h
===================================================================
RCS file: /cvsroot/src/sys/sys/socket.h,v
retrieving revision 1.128
diff -u -u -r1.128 socket.h
--- sys/socket.h	16 Sep 2018 20:40:20 -0000	1.128
+++ sys/socket.h	3 Nov 2018 21:14:53 -0000
@@ -132,7 +132,30 @@
 #define	SO_NOSIGPIPE	0x0800		/* no SIGPIPE from EPIPE */
 #define	SO_ACCEPTFILTER	0x1000		/* there is an accept filter */
 #define	SO_TIMESTAMP	0x2000		/* timestamp received dgram traffic */
+#define	SO_RERROR	0x4000		/* Keep track of receive errors */
 
+/* Allowed default option flags */
+#define SO_DEFOPTS	(SO_DEBUG|SO_REUSEADDR|SO_KEEPALIVE|SO_DONTROUTE| \
+    SO_BROADCAST|SO_USELOOPBACK|SO_LINGER|SO_OOBINLINE|SO_REUSEPORT| \
+    SO_NOSIGPIPE|SO_TIMESTAMP|SO_RERROR)
+
+#define __SO_OPTION_BITS \
+	"\20" \
+	"\1SO_DEBUG" \
+	"\2SO_ACCEPTCONN" \
+	"\3SO_REUSEADDR" \
+	"\4SO_KEEPALIVE" \
+	"\5SO_DONTROUTE" \
+	"\6SO_BROADCAST" \
+	"\7SO_USELOOPBACK" \
+	"\10SO_LINGER" \
+	"\11SO_OOBINLINE" \
+	"\12SO_REUSEPORT" \
+	"\13SO_OTIMESTAMP" \
+	"\14SO_NOSIGPIPE" \
+	"\15SO_ACCEPTFILTER" \
+	"\16SO_TIMESTAMP" \
+	"\17SO_RERROR"
 
 /*
  * Additional options, not kept in so_options.