The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 3400278328285a8c2f121904496aff5e7b610a01 Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso pablo@netfilter.org Date: Tue, 9 Aug 2022 13:22:01 +0200 Subject: [PATCH] netfilter: nf_tables: use READ_ONCE and WRITE_ONCE for shared generation id access
The generation ID is bumped from the commit path while holding the mutex, however, netlink dump operations rely on RCU.
This patch also adds missing cb->base_eq initialization in nf_tables_dump_set().
Fixes: 38e029f14a97 ("netfilter: nf_tables: set NLM_F_DUMP_INTR if netlink dumping is stale") 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 3cc88998b879..8b084cd669ab 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -889,7 +889,7 @@ static int nf_tables_dump_tables(struct sk_buff *skb,
rcu_read_lock(); nft_net = nft_pernet(net); - cb->seq = nft_net->base_seq; + cb->seq = READ_ONCE(nft_net->base_seq);
list_for_each_entry_rcu(table, &nft_net->tables, list) { if (family != NFPROTO_UNSPEC && family != table->family) @@ -1705,7 +1705,7 @@ static int nf_tables_dump_chains(struct sk_buff *skb,
rcu_read_lock(); nft_net = nft_pernet(net); - cb->seq = nft_net->base_seq; + cb->seq = READ_ONCE(nft_net->base_seq);
list_for_each_entry_rcu(table, &nft_net->tables, list) { if (family != NFPROTO_UNSPEC && family != table->family) @@ -3149,7 +3149,7 @@ static int nf_tables_dump_rules(struct sk_buff *skb,
rcu_read_lock(); nft_net = nft_pernet(net); - cb->seq = nft_net->base_seq; + cb->seq = READ_ONCE(nft_net->base_seq);
list_for_each_entry_rcu(table, &nft_net->tables, list) { if (family != NFPROTO_UNSPEC && family != table->family) @@ -4133,7 +4133,7 @@ static int nf_tables_dump_sets(struct sk_buff *skb, struct netlink_callback *cb)
rcu_read_lock(); nft_net = nft_pernet(net); - cb->seq = nft_net->base_seq; + cb->seq = READ_ONCE(nft_net->base_seq);
list_for_each_entry_rcu(table, &nft_net->tables, list) { if (ctx->family != NFPROTO_UNSPEC && @@ -5061,6 +5061,8 @@ static int nf_tables_dump_set(struct sk_buff *skb, struct netlink_callback *cb)
rcu_read_lock(); nft_net = nft_pernet(net); + cb->seq = READ_ONCE(nft_net->base_seq); + list_for_each_entry_rcu(table, &nft_net->tables, list) { if (dump_ctx->ctx.family != NFPROTO_UNSPEC && dump_ctx->ctx.family != table->family) @@ -6941,7 +6943,7 @@ static int nf_tables_dump_obj(struct sk_buff *skb, struct netlink_callback *cb)
rcu_read_lock(); nft_net = nft_pernet(net); - cb->seq = nft_net->base_seq; + cb->seq = READ_ONCE(nft_net->base_seq);
list_for_each_entry_rcu(table, &nft_net->tables, list) { if (family != NFPROTO_UNSPEC && family != table->family) @@ -7873,7 +7875,7 @@ static int nf_tables_dump_flowtable(struct sk_buff *skb,
rcu_read_lock(); nft_net = nft_pernet(net); - cb->seq = nft_net->base_seq; + cb->seq = READ_ONCE(nft_net->base_seq);
list_for_each_entry_rcu(table, &nft_net->tables, list) { if (family != NFPROTO_UNSPEC && family != table->family) @@ -8806,6 +8808,7 @@ static int nf_tables_commit(struct net *net, struct sk_buff *skb) struct nft_trans_elem *te; struct nft_chain *chain; struct nft_table *table; + unsigned int base_seq; LIST_HEAD(adl); int err;
@@ -8855,9 +8858,12 @@ static int nf_tables_commit(struct net *net, struct sk_buff *skb) * Bump generation counter, invalidate any dump in progress. * Cannot fail after this point. */ - while (++nft_net->base_seq == 0) + base_seq = READ_ONCE(nft_net->base_seq); + while (++base_seq == 0) ;
+ WRITE_ONCE(nft_net->base_seq, base_seq); + /* step 3. Start new generation, rules_gen_X now in use. */ net->nft.gencursor = nft_gencursor_next(net);