Add bound flag to chain transaction as in 6a0a8d10a366 ("netfilter:
nf_tables: use-after-free in failing rule with bound set") to skip
it in case the chain is already bound from the abort path.
This patch fixes an imbalance in the chain use refcnt that triggers a
WARN_ON on the table and chain destroy path.
This patch also disallows nested chain bindings, which is not
supported from userspace.
The logic to deal with chain binding in nft_data_hold() and
nft_data_release() is not correct. The NFT_TRANS_PREPARE state needs a
special handling in case a chain is bound but next expressions in the
same rule fail to initialize as described by 1240eb93f061 ("netfilter:
nf_tables: incorrect error path handling with NFT_MSG_NEWRULE").
Fixes: d0e2c7de92c7 ("netfilter: nf_tables: add NFT_CHAIN_BINDING")
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
---
v2: use switch() instead of if() in nft_immediate_deactivate(), comestic
to prepare for new patch 7/7
include/net/netfilter/nf_tables.h | 13 +++++++
net/netfilter/nf_tables_api.c | 65 ++++++++++++++++++++-----------
net/netfilter/nft_immediate.c | 59 ++++++++++++++++++++++++----
3 files changed, 107 insertions(+), 30 deletions(-)
diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
index 83db182decc8..9d8f57301aad 100644
--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -1104,6 +1104,7 @@ int nft_setelem_validate(const struct nft_ctx *ctx, struct nft_set *set,
const struct nft_set_iter *iter,
struct nft_set_elem *elem);
int nft_set_catchall_validate(const struct nft_ctx *ctx, struct nft_set *set);
+int nf_tables_bind_chain(const struct nft_ctx *ctx, struct nft_chain *chain);
enum nft_chain_types {
NFT_CHAIN_T_DEFAULT = 0,
@@ -1140,11 +1141,17 @@ int nft_chain_validate_dependency(const struct nft_chain *chain,
int nft_chain_validate_hooks(const struct nft_chain *chain,
unsigned int hook_flags);
+static inline bool nft_chain_binding(const struct nft_chain *chain)
+{
+ return chain->flags & NFT_CHAIN_BINDING;
+}
+
static inline bool nft_chain_is_bound(struct nft_chain *chain)
{
return (chain->flags & NFT_CHAIN_BINDING) && chain->bound;
}
+int nft_chain_add(struct nft_table *table, struct nft_chain *chain);
void nft_chain_del(struct nft_chain *chain);
void nf_tables_chain_destroy(struct nft_ctx *ctx);
@@ -1607,15 +1614,19 @@ struct nft_trans_set {
(((struct nft_trans_set *)trans->data)->gc_int)
struct nft_trans_chain {
+ struct nft_chain *chain;
bool update;
char *name;
struct nft_stats __percpu *stats;
u8 policy;
+ bool bound;
u32 chain_id;
struct nft_base_chain *basechain;
struct list_head hook_list;
};
+#define nft_trans_chain(trans) \
+ (((struct nft_trans_chain *)trans->data)->chain)
#define nft_trans_chain_update(trans) \
(((struct nft_trans_chain *)trans->data)->update)
#define nft_trans_chain_name(trans) \
@@ -1624,6 +1635,8 @@ struct nft_trans_chain {
(((struct nft_trans_chain *)trans->data)->stats)
#define nft_trans_chain_policy(trans) \
(((struct nft_trans_chain *)trans->data)->policy)
+#define nft_trans_chain_bound(trans) \
+ (((struct nft_trans_chain *)trans->data)->bound)
#define nft_trans_chain_id(trans) \
(((struct nft_trans_chain *)trans->data)->chain_id)
#define nft_trans_basechain(trans) \
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 69bceefaa5c8..467c2a20e16d 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -193,6 +193,44 @@ static void nft_set_trans_bind(const struct nft_ctx *ctx, struct nft_set *set)
}
}
+static void nft_chain_trans_bind(const struct nft_ctx *ctx, struct nft_chain *chain)
+{
+ struct nftables_pernet *nft_net;
+ struct net *net = ctx->net;
+ struct nft_trans *trans;
+
+ if (!nft_chain_binding(chain))
+ return;
+
+ nft_net = nft_pernet(net);
+ list_for_each_entry_reverse(trans, &nft_net->commit_list, list) {
+ switch (trans->msg_type) {
+ case NFT_MSG_NEWCHAIN:
+ if (nft_trans_chain(trans) == chain)
+ nft_trans_chain_bound(trans) = true;
+ break;
+ }
+ }
+}
+
+int nf_tables_bind_chain(const struct nft_ctx *ctx, struct nft_chain *chain)
+{
+ if (!nft_chain_binding(chain))
+ return 0;
+
+ if (nft_chain_binding(ctx->chain))
+ return -EOPNOTSUPP;
+
+ if (chain->bound)
+ return -EBUSY;
+
+ chain->bound = true;
+ chain->use++;
+ nft_chain_trans_bind(ctx, chain);
+
+ return 0;
+}
+
static int nft_netdev_register_hooks(struct net *net,
struct list_head *hook_list)
{
@@ -338,8 +376,9 @@ static struct nft_trans *nft_trans_chain_add(struct nft_ctx *ctx, int msg_type)
ntohl(nla_get_be32(ctx->nla[NFTA_CHAIN_ID]));
}
}
-
+ nft_trans_chain(trans) = ctx->chain;
nft_trans_commit_list_add_tail(ctx->net, trans);
+
return trans;
}
@@ -2226,7 +2265,7 @@ static int nft_basechain_init(struct nft_base_chain *basechain, u8 family,
return 0;
}
-static int nft_chain_add(struct nft_table *table, struct nft_chain *chain)
+int nft_chain_add(struct nft_table *table, struct nft_chain *chain)
{
int err;
@@ -6638,7 +6677,6 @@ static int nf_tables_newsetelem(struct sk_buff *skb,
void nft_data_hold(const struct nft_data *data, enum nft_data_types type)
{
struct nft_chain *chain;
- struct nft_rule *rule;
if (type == NFT_DATA_VERDICT) {
switch (data->verdict.code) {
@@ -6646,15 +6684,6 @@ void nft_data_hold(const struct nft_data *data, enum nft_data_types type)
case NFT_GOTO:
chain = data->verdict.chain;
chain->use++;
-
- if (!nft_chain_is_bound(chain))
- break;
-
- chain->table->use++;
- list_for_each_entry(rule, &chain->rules, list)
- chain->use++;
-
- nft_chain_add(chain->table, chain);
break;
}
}
@@ -9677,7 +9706,7 @@ static int __nf_tables_abort(struct net *net, enum nfnl_abort_action action)
kfree(nft_trans_chain_name(trans));
nft_trans_destroy(trans);
} else {
- if (nft_chain_is_bound(trans->ctx.chain)) {
+ if (nft_trans_chain_bound(trans)) {
nft_trans_destroy(trans);
break;
}
@@ -10263,22 +10292,12 @@ static int nft_verdict_init(const struct nft_ctx *ctx, struct nft_data *data,
static void nft_verdict_uninit(const struct nft_data *data)
{
struct nft_chain *chain;
- struct nft_rule *rule;
switch (data->verdict.code) {
case NFT_JUMP:
case NFT_GOTO:
chain = data->verdict.chain;
chain->use--;
-
- if (!nft_chain_is_bound(chain))
- break;
-
- chain->table->use--;
- list_for_each_entry(rule, &chain->rules, list)
- chain->use--;
-
- nft_chain_del(chain);
break;
}
}
diff --git a/net/netfilter/nft_immediate.c b/net/netfilter/nft_immediate.c
index c9d2f7c29f53..85382d7428b0 100644
--- a/net/netfilter/nft_immediate.c
+++ b/net/netfilter/nft_immediate.c
@@ -76,11 +76,9 @@ static int nft_immediate_init(const struct nft_ctx *ctx,
switch (priv->data.verdict.code) {
case NFT_JUMP:
case NFT_GOTO:
- if (nft_chain_is_bound(chain)) {
- err = -EBUSY;
- goto err1;
- }
- chain->bound = true;
+ err = nf_tables_bind_chain(ctx, chain);
+ if (err < 0)
+ return err;
break;
default:
break;
@@ -98,6 +96,25 @@ static void nft_immediate_activate(const struct nft_ctx *ctx,
const struct nft_expr *expr)
{
const struct nft_immediate_expr *priv = nft_expr_priv(expr);
+ const struct nft_data *data = &priv->data;
+ struct nft_chain *chain;
+
+ if (priv->dreg == NFT_REG_VERDICT) {
+ switch (data->verdict.code) {
+ case NFT_JUMP:
+ case NFT_GOTO:
+ chain = data->verdict.chain;
+ if (!nft_chain_binding(chain))
+ break;
+
+ nft_clear(ctx->net, chain);
+ nft_chain_add(ctx->table, chain);
+ chain->table->use++;
+ break;
+ default:
+ break;
+ }
+ }
return nft_data_hold(&priv->data, nft_dreg_to_type(priv->dreg));
}
@@ -107,6 +124,31 @@ static void nft_immediate_deactivate(const struct nft_ctx *ctx,
enum nft_trans_phase phase)
{
const struct nft_immediate_expr *priv = nft_expr_priv(expr);
+ const struct nft_data *data = &priv->data;
+ struct nft_chain *chain;
+
+ if (priv->dreg == NFT_REG_VERDICT) {
+ switch (data->verdict.code) {
+ case NFT_JUMP:
+ case NFT_GOTO:
+ chain = data->verdict.chain;
+ if (!nft_chain_binding(chain))
+ break;
+
+ switch (phase) {
+ case NFT_TRANS_PREPARE:
+ nft_deactivate_next(ctx->net, chain);
+ break;
+ default:
+ nft_chain_del(chain);
+ chain->table->use--;
+ break;
+ }
+ break;
+ default:
+ break;
+ }
+ }
if (phase == NFT_TRANS_COMMIT)
return;
@@ -137,9 +179,12 @@ static void nft_immediate_destroy(const struct nft_ctx *ctx,
chain_ctx = *ctx;
chain_ctx.chain = chain;
- list_for_each_entry_safe(rule, n, &chain->rules, list)
+ chain->use--;
+ list_for_each_entry_safe(rule, n, &chain->rules, list) {
+ chain->use--;
+ list_del(&rule->list);
nf_tables_rule_release(&chain_ctx, rule);
-
+ }
nf_tables_chain_destroy(&chain_ctx);
break;
default:
--
2.30.2
