From: Roy Marples <roy@marples.name>
Date: Mon, 1 Jun 2020 14:33:05 +0000 (+0100)
Subject: privsep: Double the size of the send buffer.
X-Git-Tag: v9.1.1~17
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=74df3b70381ee3a84c363f4ffed40322490063d5;p=thirdparty%2Fdhcpcd.git

privsep: Double the size of the send buffer.

And ensure the buffer size is not reduced.
---

diff --git a/src/privsep.c b/src/privsep.c
index ce84ff80..d35b2be0 100644
--- a/src/privsep.c
+++ b/src/privsep.c
@@ -131,13 +131,34 @@ ps_dropprivs(struct dhcpcd_ctx *ctx)
 	return 0;
 }
 
+static int
+ps_setbuf0(int fd, int ctl, int minlen)
+{
+	int len;
+	socklen_t slen;
+
+	slen = sizeof(len);
+	if (getsockopt(fd, SOL_SOCKET, ctl, &len, &slen) == -1)
+		return -1;
+
+#ifdef __linux__
+	len /= 2;
+#endif
+	if (len >= minlen)
+		return 0;
+
+	return setsockopt(fd, SOL_SOCKET, ctl, &minlen, sizeof(minlen));
+}
+
 static int
 ps_setbuf(int fd)
 {
-	socklen_t len = (socklen_t)sizeof(struct ps_msg);
+	/* Ensure we can receive a fully sized privsep message.
+	 * Double the send buffer. */
+	int minlen = (int)sizeof(struct ps_msg);
 
-	if (setsockopt(fd, SOL_SOCKET, SO_RCVBUF, &len, sizeof(len)) == -1 ||
-	    setsockopt(fd, SOL_SOCKET, SO_SNDBUF, &len, sizeof(len)) == -1)
+	if (ps_setbuf0(fd, SO_RCVBUF, minlen) == -1 ||
+	    ps_setbuf0(fd, SO_SNDBUF, minlen * 2) == -1)
 	{
 		logerr(__func__);
 		return -1;