Tools: hv: verify origin of netlink connector message

The SuSE security team suggested to use recvfrom instead of recv to be
certain that the connector message is originated from kernel.

CVE-2012-2669
Signed-off-by: NOlaf Hering <olaf@aepfle.de>
Signed-off-by: NMarcus Meissner <meissner@suse.de>
Signed-off-by: NSebastian Krahmer <krahmer@suse.de>
Signed-off-by: NK. Y. Srinivasan <kys@microsoft.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

tools/hv/hv_kvp_daemon.c

@@ -701,14 +701,18 @@ int main(void)
 	pfd.fd = fd;
 
 	while (1) {
+		struct sockaddr *addr_p = (struct sockaddr *) &addr;
+		socklen_t addr_l = sizeof(addr);
 		pfd.events = POLLIN;
 		pfd.revents = 0;
 		poll(&pfd, 1, -1);
 
-		len = recv(fd, kvp_recv_buffer, sizeof(kvp_recv_buffer), 0);
+		len = recvfrom(fd, kvp_recv_buffer, sizeof(kvp_recv_buffer), 0,
+				addr_p, &addr_l);
 
-		if (len < 0) {
-			syslog(LOG_ERR, "recv failed; error:%d", len);
+		if (len < 0 || addr.nl_pid) {
+			syslog(LOG_ERR, "recvfrom failed; pid:%u error:%d %s",
+					addr.nl_pid, errno, strerror(errno));
 			close(fd);
 			return -1;
 		}