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

[Ido Schimmel]

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 <ido...@mellanox.com>
Reported-by: LiLiang <li...@redhat.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