UPSTREAM: netfilter: nf_tables: disallow rule removal from chain binding

[ Upstream commit f15f29fd ]

Chain binding only requires the rule addition/insertion command within
the same transaction. Removal of rules from chain bindings within the
same transaction makes no sense, userspace does not utilize this
feature. Replace nft_chain_is_bound() check to nft_chain_binding() in
rule deletion commands. Replace command implies a rule deletion, reject
this command too.

Rule flush command can also safely rely on this nft_chain_binding()
check because unbound chains are not allowed since 62e1e94b
("netfilter: nf_tables: reject unbound chain set before commit phase").

Bug: 302085977
Fixes: d0e2c7de ("netfilter: nf_tables: add NFT_CHAIN_BINDING")
Reported-by: Kevin Rich <kevinrich1337@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
(cherry picked from commit 9af8bb2a)
Signed-off-by: Lee Jones <joneslee@google.com>
Change-Id: I8b05dc37062824db4c2901000fdf701b38605d32