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netfilter: nf_tables: use READ_ONCE and WRITE_ONCE for shared generation id access

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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: 38e029f14a ("netfilter: nf_tables: set NLM_F_DUMP_INTR if netlink dumping is stale")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Pablo Neira Ayuso 2022-08-09 13:22:01 +02:00
parent f329a0ebea
commit 3400278328
1 changed files with 13 additions and 7 deletions
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20
net/netfilter/nf_tables_api.c
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@ -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);