Commit 5ae437ad authored by Roman Kapl's avatar Roman Kapl Committed by David S. Miller

net: sched: report if filter is too large to dump

So far, if the filter was too large to fit in the allocated skb, the
kernel did not return any error and stopped dumping. Modify the dumper
so that it returns -EMSGSIZE when a filter fails to dump and it is the
first filter in the skb. If we are not first, we will get a next chance
with more room.

I understand this is pretty near to being an API change, but the
original design (silent truncation) can be considered a bug.

Note: The error case can happen pretty easily if you create a filter
with 32 actions and have 4kb pages. Also recent versions of iproute try
to be clever with their buffer allocation size, which in turn leads to
Signed-off-by: default avatarRoman Kapl <code@rkapl.cz>
Acked-by: default avatarJiri Pirko <jiri@mellanox.com>
Acked-by: default avatarCong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent abe27a88
......@@ -1397,13 +1397,18 @@ static int tc_dump_tfilter(struct sk_buff *skb, struct netlink_callback *cb)
nla_get_u32(tca[TCA_CHAIN]) != chain->index)
continue;
if (!tcf_chain_dump(chain, q, parent, skb, cb,
index_start, &index))
index_start, &index)) {
err = -EMSGSIZE;
break;
}
}
cb->args[0] = index;
out:
/* If we did no progress, the error (EMSGSIZE) is real */
if (skb->len == 0 && err)
return err;
return skb->len;
}
......
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