net: sched: report if filter is too large to dump
[ Upstream commit 5ae437ad5a
]
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: Roman Kapl <code@rkapl.cz>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Acked-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -871,13 +871,18 @@ static int tc_dump_tfilter(struct sk_buff *skb, struct netlink_callback *cb)
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if (tca[TCA_CHAIN] &&
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if (tca[TCA_CHAIN] &&
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nla_get_u32(tca[TCA_CHAIN]) != chain->index)
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nla_get_u32(tca[TCA_CHAIN]) != chain->index)
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continue;
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continue;
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if (!tcf_chain_dump(chain, skb, cb, index_start, &index))
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if (!tcf_chain_dump(chain, skb, cb, index_start, &index)) {
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err = -EMSGSIZE;
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break;
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break;
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}
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}
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}
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cb->args[0] = index;
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cb->args[0] = index;
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out:
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out:
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/* If we did no progress, the error (EMSGSIZE) is real */
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if (skb->len == 0 && err)
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return err;
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return skb->len;
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return skb->len;
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}
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}
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