net: ndo_fdb_dump should report -EMSGSIZE to rtnl_fdb_dump.

When the send skbuff reaches the end, nlmsg_put and friends returns -EMSGSIZE but it is silently thrown away in ndo_fdb_dump. It is called within a for_each_netdev loop and the first fdb entry of a following netdev could fit in the remaining skbuff. This breaks the mechanism of cb->args[0] and idx to keep track of the entries that are already dumped, which results missing entries in bridge fdb show command. Signed-off-by: Minoura Makoto <[email protected]> Signed-off-by: David S. Miller <[email protected]>
torvalds · Feb 26, 2016 · 472681d · 472681d
1 parent 4c0b6ea
commit 472681d
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Showing 4 changed files with 23 additions and 7 deletions.
diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
@@ -931,8 +931,10 @@ static int vxlan_fdb_dump(struct sk_buff *skb, struct netlink_callback *cb,
  cb->nlh->nlmsg_seq,
  RTM_NEWNEIGH,
  NLM_F_MULTI, rd);
- if (err < 0)
+ if (err < 0) {
+ cb->args[1] = err;
  goto out;
+ }
 skip:
  ++idx;
  }

diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
@@ -723,6 +723,8 @@ int br_fdb_dump(struct sk_buff *skb,
  struct net_bridge_fdb_entry *f;
 
  hlist_for_each_entry_rcu(f, &br->hash[i], hlist) {
+ int err;
+
  if (idx < cb->args[0])
  goto skip;
 
@@ -741,12 +743,15 @@ int br_fdb_dump(struct sk_buff *skb,
  if (!filter_dev && f->dst)
  goto skip;
 
- if (fdb_fill_info(skb, br, f,
- NETLINK_CB(cb->skb).portid,
- cb->nlh->nlmsg_seq,
- RTM_NEWNEIGH,
- NLM_F_MULTI) < 0)
+ err = fdb_fill_info(skb, br, f,
+ NETLINK_CB(cb->skb).portid,
+ cb->nlh->nlmsg_seq,
+ RTM_NEWNEIGH,
+ NLM_F_MULTI);
+ if (err < 0) {
+ cb->args[1] = err;
  break;
+ }
 skip:
  ++idx;
  }

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
@@ -2911,6 +2911,7 @@ int ndo_dflt_fdb_dump(struct sk_buff *skb,
  nlmsg_populate_fdb(skb, cb, dev, &idx, &dev->mc);
 out:
  netif_addr_unlock_bh(dev);
+ cb->args[1] = err;
  return idx;
 }
 EXPORT_SYMBOL(ndo_dflt_fdb_dump);
@@ -2944,6 +2945,7 @@ static int rtnl_fdb_dump(struct sk_buff *skb, struct netlink_callback *cb)
  ops = br_dev->netdev_ops;
  }
 
+ cb->args[1] = 0;
  for_each_netdev(net, dev) {
  if (brport_idx && (dev->ifindex != brport_idx))
  continue;
@@ -2971,12 +2973,16 @@ static int rtnl_fdb_dump(struct sk_buff *skb, struct netlink_callback *cb)
  idx = cops->ndo_fdb_dump(skb, cb, br_dev, dev,
  idx);
  }
+ if (cb->args[1] == -EMSGSIZE)
+ break;
 
  if (dev->netdev_ops->ndo_fdb_dump)
  idx = dev->netdev_ops->ndo_fdb_dump(skb, cb, dev, NULL,
  idx);
  else
  idx = ndo_dflt_fdb_dump(skb, cb, dev, NULL, idx);
+ if (cb->args[1] == -EMSGSIZE)
+ break;
 
  cops = NULL;
  }

diff --git a/net/switchdev/switchdev.c b/net/switchdev/switchdev.c
@@ -1093,8 +1093,11 @@ int switchdev_port_fdb_dump(struct sk_buff *skb, struct netlink_callback *cb,
  .cb = cb,
  .idx = idx,
  };
+ int err;
 
- switchdev_port_obj_dump(dev, &dump.fdb.obj, switchdev_port_fdb_dump_cb);
+ err = switchdev_port_obj_dump(dev, &dump.fdb.obj,
+ switchdev_port_fdb_dump_cb);
+ cb->args[1] = err;
  return dump.idx;
 }
 EXPORT_SYMBOL_GPL(switchdev_port_fdb_dump);