netdev - [PATCH iproute2-master] bridge: fdb: Fix FDB dump with strict checking disabled

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Date:   Fri, 25 Jan 2019 17:09:17 +0000
From:   Ido Schimmel <idosch@...lanox.com>
To:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>
CC:     "stephen@...workplumber.org" <stephen@...workplumber.org>,
        "dsahern@...il.com" <dsahern@...il.com>,
        "ivecera@...hat.com" <ivecera@...hat.com>,
        "liali@...hat.com" <liali@...hat.com>, mlxsw <mlxsw@...lanox.com>,
        Ido Schimmel <idosch@...lanox.com>
Subject: [PATCH iproute2-master] bridge: fdb: Fix FDB dump with strict
 checking disabled

While iproute2 correctly uses ifinfomsg struct as the ancillary header
when requesting an FDB dump on old kernels, it sets the message type to
RTM_GETLINK. This results in wrong reply being returned.

Fix this by using RTM_GETNEIGH instead.

Before:
$ bridge fdb show brport dummy0
Not RTM_NEWNEIGH: 00000158 00000010 00000002

After:
$ bridge fdb show brport dummy0
2a:0b:41:1c:92:d3 vlan 1 master br0 permanent
2a:0b:41:1c:92:d3 master br0 permanent
33:33:00:00:00:01 self permanent
01:00:5e:00:00:01 self permanent

Fixes: 05880354c2cf ("bridge: fdb: Fix filtering with strict checking disabled")
Signed-off-by: Ido Schimmel <idosch@...lanox.com>
Reported-by: LiLiang <liali@...hat.com>
---
 bridge/fdb.c         |  3 +--
 include/libnetlink.h |  3 +++
 lib/libnetlink.c     | 23 +++++++++++++++++++++++
 3 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/bridge/fdb.c b/bridge/fdb.c
index f75e953a80e2..c4bf40390f42 100644
--- a/bridge/fdb.c
+++ b/bridge/fdb.c
@@ -346,8 +346,7 @@ static int fdb_show(int argc, char **argv)
 	if (rth.flags & RTNL_HANDLE_F_STRICT_CHK)
 		rc = rtnl_neighdump_req(&rth, PF_BRIDGE, fdb_dump_filter);
 	else
-		rc = rtnl_linkdump_req_filter_fn(&rth, PF_BRIDGE,
-						 fdb_linkdump_filter);
+		rc = rtnl_fdb_linkdump_req_filter_fn(&rth, fdb_linkdump_filter);
 	if (rc < 0) {
 		perror("Cannot send dump request");
 		exit(1);
diff --git a/include/libnetlink.h b/include/libnetlink.h
index 0854d6ad2fab..503b3ec11bb6 100644
--- a/include/libnetlink.h
+++ b/include/libnetlink.h
@@ -81,6 +81,9 @@ int rtnl_linkdump_req_filter(struct rtnl_handle *rth, int fam, __u32 filt_mask)
 int rtnl_linkdump_req_filter_fn(struct rtnl_handle *rth, int fam,
 				req_filter_fn_t fn)
 	__attribute__((warn_unused_result));
+int rtnl_fdb_linkdump_req_filter_fn(struct rtnl_handle *rth,
+				    req_filter_fn_t filter_fn)
+	__attribute__((warn_unused_result));
 int rtnl_statsdump_req_filter(struct rtnl_handle *rth, int fam, __u32 filt_mask)
 	__attribute__((warn_unused_result));
 int rtnl_dump_request(struct rtnl_handle *rth, int type, void *req,
diff --git a/lib/libnetlink.c b/lib/libnetlink.c
index 110f47bcd65a..7b392862cb91 100644
--- a/lib/libnetlink.c
+++ b/lib/libnetlink.c
@@ -503,6 +503,29 @@ int rtnl_linkdump_req_filter_fn(struct rtnl_handle *rth, int family,
 	return __rtnl_linkdump_req(rth, family);
 }
 
+int rtnl_fdb_linkdump_req_filter_fn(struct rtnl_handle *rth,
+				    req_filter_fn_t filter_fn)
+{
+	struct {
+		struct nlmsghdr nlh;
+		struct ifinfomsg ifm;
+		char buf[128];
+	} req = {
+		.nlh.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg)),
+		.nlh.nlmsg_type = RTM_GETNEIGH,
+		.nlh.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST,
+		.nlh.nlmsg_seq = rth->dump = ++rth->seq,
+		.ifm.ifi_family = PF_BRIDGE,
+	};
+	int err;
+
+	err = filter_fn(&req.nlh, sizeof(req));
+	if (err)
+		return err;
+
+	return send(rth->fd, &req, sizeof(req), 0);
+}
+
 int rtnl_statsdump_req_filter(struct rtnl_handle *rth, int fam, __u32 filt_mask)
 {
 	struct {
-- 
2.20.1