netfilter: nf_tables: don't fail when updating base chain policy

The following nftables test case fails on nf-next:

tests/shell/run-tests.sh tests/shell/testcases/transactions/0011chain_0

The test case contains:
add chain x y { type filter hook input priority 0; }
add chain x y { policy drop; }"

The new test
if (chain->flags ^ flags)
	return -EOPNOTSUPP;

triggers here, because chain->flags has NFT_BASE_CHAIN set, but flags
is 0 because no flag attribute was present in the policy update.

Just fetch the current flag settings of a pre-existing chain in case
userspace did not provide any.

Fixes: c9626a2cbdb20 ("netfilter: nf_tables: add hardware offload support")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index ed17a7c29b86f50578eae91827394d624c63c3cb..014e06b0b5cfb07ec6ea9026d0a0889f5ae81e17 100644 (file)
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -1900,6 +1900,8 @@ static int nf_tables_newchain(struct net *net, struct sock *nlsk,
 
        if (nla[NFTA_CHAIN_FLAGS])
                flags = ntohl(nla_get_be32(nla[NFTA_CHAIN_FLAGS]));
+       else if (chain)
+               flags = chain->flags;
 
        nft_ctx_init(&ctx, net, skb, nlh, family, table, chain, nla);