[dpdk-dev] [PATCH] net/vdev_netvsc: fix routed devices probing

[Matan Azrad]

NetVSC netdevices which are already routed should not be probed because
they are used for management purposes by the HyperV.

The corrupted code got the routed devices from the system file
/proc/net/route and wrongly parsed only the odd lines, so devices which
their routes were in even lines, were considered as unrouted devices
and were probed.

Use linux netlink lib to detect the routed NetVSC devices instead of
file parsing.

Fixes: 31182fadfb21 ("net/vdev_netvsc: skip routed netvsc probing")
Cc: stable at dpdk.org
Cc: stephen at networkplumber.org

Suggested-by: Stephen Hemminger <stephen at networkplumber.org>
Signed-off-by: Matan Azrad <matan at mellanox.com>
---
 drivers/net/vdev_netvsc/vdev_netvsc.c | 109 +++++++++++++++++++++++++++-------
 1 file changed, 86 insertions(+), 23 deletions(-)

diff --git a/drivers/net/vdev_netvsc/vdev_netvsc.c b/drivers/net/vdev_netvsc/vdev_netvsc.c
index cbf4d59..db0080a 100644
--- a/drivers/net/vdev_netvsc/vdev_netvsc.c
+++ b/drivers/net/vdev_netvsc/vdev_netvsc.c
@@ -7,6 +7,8 @@
 #include <fcntl.h>
 #include <inttypes.h>
 #include <linux/sockios.h>
+#include <linux/netlink.h>
+#include <linux/rtnetlink.h>
 #include <net/if.h>
 #include <net/if_arp.h>
 #include <netinet/ip.h>
@@ -207,36 +209,96 @@ static LIST_HEAD(, vdev_netvsc_ctx) vdev_netvsc_ctx_list =
  *
  * @param[in] name
  *   Network device name.
+ * @param[in] family
+ *   Address family: AF_INET for IPv4 or AF_INET6 for IPv6.
  *
  * @return
- *   A nonzero value when interface has an route. In case of error,
- *   rte_errno is updated and 0 returned.
+ *   1 when interface has a route, negative errno value in case of error and
+ *   0 otherwise.
  */
 static int
-vdev_netvsc_has_route(const char *name)
+vdev_netvsc_has_route(const struct if_nameindex *iface,
+		      const unsigned char family)
 {
-	FILE *fp;
+	/*
+	 * The implementation can be simpler by getifaddrs() function usage but
+	 * it works for IPv6 only starting from glibc 2.3.3.
+	 */
+	char buf[4096];
+	int len;
 	int ret = 0;
-	char route[NETVSC_MAX_ROUTE_LINE_SIZE];
-	char *netdev;
-
-	fp = fopen("/proc/net/route", "r");
-	if (!fp) {
-		rte_errno = errno;
-		return 0;
+	int res;
+	int sock;
+	struct nlmsghdr *retmsg = (struct nlmsghdr *)buf;
+	struct sockaddr_nl sa;
+	struct {
+		struct nlmsghdr nlhdr;
+		struct ifaddrmsg addrmsg;
+	} msg;
+
+	if (!iface || (family != AF_INET && family != AF_INET6)) {
+		DRV_LOG(ERR, "%s", rte_strerror(EINVAL));
+		return -EINVAL;
 	}
-	while (fgets(route, NETVSC_MAX_ROUTE_LINE_SIZE, fp) != NULL) {
-		netdev = strtok(route, "\t");
-		if (strcmp(netdev, name) == 0) {
-			ret = 1;
-			break;
+	sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
+	if (sock == -1) {
+		DRV_LOG(ERR, "cannot open socket: %s", rte_strerror(errno));
+		return -errno;
+	}
+	memset(&sa, 0, sizeof(sa));
+	sa.nl_family = AF_NETLINK;
+	sa.nl_groups = RTMGRP_LINK | RTMGRP_IPV4_IFADDR;
+	res = bind(sock, (struct sockaddr *)&sa, sizeof(sa));
+	if (res == -1) {
+		ret = -errno;
+		DRV_LOG(ERR, "cannot bind socket: %s", rte_strerror(errno));
+		goto close;
+	}
+	memset(&msg, 0, sizeof(msg));
+	msg.nlhdr.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifaddrmsg));
+	msg.nlhdr.nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP;
+	msg.nlhdr.nlmsg_type = RTM_GETADDR;
+	msg.nlhdr.nlmsg_pid = getpid();
+	msg.addrmsg.ifa_family = family;
+	msg.addrmsg.ifa_index = iface->if_index;
+	res = send(sock, &msg, msg.nlhdr.nlmsg_len, 0);
+	if (res == -1) {
+		ret = -errno;
+		DRV_LOG(ERR, "cannot send socket message: %s",
+			rte_strerror(errno));
+		goto close;
+	}
+	memset(buf, 0, sizeof(buf));
+	len = recv(sock, buf, sizeof(buf), 0);
+	if (len == -1) {
+		ret = -errno;
+		DRV_LOG(ERR, "cannot receive socket message: %s",
+			rte_strerror(errno));
+		goto close;
+	}
+	while (NLMSG_OK(retmsg, (unsigned int)len)) {
+		struct ifaddrmsg *retaddr =
+				(struct ifaddrmsg *)NLMSG_DATA(retmsg);
+
+		if (retaddr->ifa_family == family &&
+		    retaddr->ifa_index == iface->if_index) {
+			struct rtattr *retrta = IFA_RTA(retaddr);
+			int attlen = IFA_PAYLOAD(retmsg);
+
+			while (RTA_OK(retrta, attlen)) {
+				if (retrta->rta_type == IFA_ADDRESS) {
+					ret = 1;
+					DRV_LOG(DEBUG, "interface %s has IP",
+						iface->if_name);
+					goto close;
+				}
+				retrta = RTA_NEXT(retrta, attlen);
+			}
 		}
-		/* Move file pointer to the next line. */
-		while (strchr(route, '\n') == NULL &&
-		       fgets(route, NETVSC_MAX_ROUTE_LINE_SIZE, fp) != NULL)
-			;
+		retmsg = NLMSG_NEXT(retmsg, len);
 	}
-	fclose(fp);
+close:
+	close(sock);
 	return ret;
 }
 
@@ -505,10 +567,11 @@ static LIST_HEAD(, vdev_netvsc_ctx) vdev_netvsc_ctx_list =
 			iface->if_name, iface->if_index);
 	}
 	/* Routed NetVSC should not be probed. */
-	if (vdev_netvsc_has_route(iface->if_name)) {
+	if (vdev_netvsc_has_route(iface, AF_INET) ||
+	    vdev_netvsc_has_route(iface, AF_INET6)) {
 		if (!specified || !force)
 			return 0;
-		DRV_LOG(WARNING, "using routed NetVSC interface \"%s\""
+		DRV_LOG(WARNING, "probably using routed NetVSC interface \"%s\""
 			" (index %u)", iface->if_name, iface->if_index);
 	}
 	/* Create interface context. */
-- 
1.9.5