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netfilter: nf_tables: add NFT_CHAIN_BINDING
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This new chain flag specifies that:

* the kernel dynamically allocates the chain name, if no chain name
  is specified.

* If the immediate expression that refers to this chain is removed,
  then this bound chain (and its content) is destroyed.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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@ummakynes
ummakynes committed Jul 3, 2020
1 parent 04b7db4 commit d0e2c7d
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Showing 4 changed files with 138 additions and 13 deletions.
13 changes: 12 additions & 1 deletion include/net/netfilter/nf_tables.h
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Original file line number Diff line number Diff line change
Expand Up @@ -899,6 +899,8 @@ static inline struct nft_userdata *nft_userdata(const struct nft_rule *rule)
return (void *)&rule->data[rule->dlen];
}

void nf_tables_rule_release(const struct nft_ctx *ctx, struct nft_rule *rule);

static inline void nft_set_elem_update_expr(const struct nft_set_ext *ext,
struct nft_regs *regs,
const struct nft_pktinfo *pkt)
Expand Down Expand Up @@ -944,7 +946,8 @@ struct nft_chain {
struct nft_table *table;
u64 handle;
u32 use;
u8 flags:6,
u8 flags:5,
bound:1,
genmask:2;
char *name;

Expand Down Expand Up @@ -989,6 +992,14 @@ 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_is_bound(struct nft_chain *chain)
{
return (chain->flags & NFT_CHAIN_BINDING) && chain->bound;
}

void nft_chain_del(struct nft_chain *chain);
void nf_tables_chain_destroy(struct nft_ctx *ctx);

struct nft_stats {
u64 bytes;
u64 pkts;
Expand Down
1 change: 1 addition & 0 deletions include/uapi/linux/netfilter/nf_tables.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -187,6 +187,7 @@ enum nft_table_attributes {
enum nft_chain_flags {
NFT_CHAIN_BASE = (1 << 0),
NFT_CHAIN_HW_OFFLOAD = (1 << 1),
NFT_CHAIN_BINDING = (1 << 2),
};

/**
Expand Down
86 changes: 74 additions & 12 deletions net/netfilter/nf_tables_api.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1056,6 +1056,9 @@ static int nft_flush_table(struct nft_ctx *ctx)
if (!nft_is_active_next(ctx->net, chain))
continue;

if (nft_chain_is_bound(chain))
continue;

ctx->chain = chain;

err = nft_delrule_by_chain(ctx);
Expand Down Expand Up @@ -1098,6 +1101,9 @@ static int nft_flush_table(struct nft_ctx *ctx)
if (!nft_is_active_next(ctx->net, chain))
continue;

if (nft_chain_is_bound(chain))
continue;

ctx->chain = chain;

err = nft_delchain(ctx);
Expand Down Expand Up @@ -1413,13 +1419,12 @@ static int nf_tables_fill_chain_info(struct sk_buff *skb, struct net *net,
lockdep_commit_lock_is_held(net));
if (nft_dump_stats(skb, stats))
goto nla_put_failure;

if ((chain->flags & NFT_CHAIN_HW_OFFLOAD) &&
nla_put_be32(skb, NFTA_CHAIN_FLAGS,
htonl(NFT_CHAIN_HW_OFFLOAD)))
goto nla_put_failure;
}

if (chain->flags &&
nla_put_be32(skb, NFTA_CHAIN_FLAGS, htonl(chain->flags)))
goto nla_put_failure;

if (nla_put_be32(skb, NFTA_CHAIN_USE, htonl(chain->use)))
goto nla_put_failure;

Expand Down Expand Up @@ -1621,7 +1626,7 @@ static void nf_tables_chain_free_chain_rules(struct nft_chain *chain)
kvfree(chain->rules_next);
}

static void nf_tables_chain_destroy(struct nft_ctx *ctx)
void nf_tables_chain_destroy(struct nft_ctx *ctx)
{
struct nft_chain *chain = ctx->chain;
struct nft_hook *hook, *next;
Expand Down Expand Up @@ -1928,6 +1933,8 @@ static int nft_chain_add(struct nft_table *table, struct nft_chain *chain)
return 0;
}

static u64 chain_id;

static int nf_tables_addchain(struct nft_ctx *ctx, u8 family, u8 genmask,
u8 policy, u32 flags)
{
Expand All @@ -1936,6 +1943,7 @@ static int nf_tables_addchain(struct nft_ctx *ctx, u8 family, u8 genmask,
struct nft_base_chain *basechain;
struct nft_stats __percpu *stats;
struct net *net = ctx->net;
char name[NFT_NAME_MAXLEN];
struct nft_trans *trans;
struct nft_chain *chain;
struct nft_rule **rules;
Expand All @@ -1947,6 +1955,9 @@ static int nf_tables_addchain(struct nft_ctx *ctx, u8 family, u8 genmask,
if (nla[NFTA_CHAIN_HOOK]) {
struct nft_chain_hook hook;

if (flags & NFT_CHAIN_BINDING)
return -EOPNOTSUPP;

err = nft_chain_parse_hook(net, nla, &hook, family, true);
if (err < 0)
return err;
Expand Down Expand Up @@ -1976,16 +1987,33 @@ static int nf_tables_addchain(struct nft_ctx *ctx, u8 family, u8 genmask,
return err;
}
} else {
if (flags & NFT_CHAIN_BASE)
return -EINVAL;
if (flags & NFT_CHAIN_HW_OFFLOAD)
return -EOPNOTSUPP;

chain = kzalloc(sizeof(*chain), GFP_KERNEL);
if (chain == NULL)
return -ENOMEM;

chain->flags = flags;
}
ctx->chain = chain;

INIT_LIST_HEAD(&chain->rules);
chain->handle = nf_tables_alloc_handle(table);
chain->table = table;
chain->name = nla_strdup(nla[NFTA_CHAIN_NAME], GFP_KERNEL);

if (nla[NFTA_CHAIN_NAME]) {
chain->name = nla_strdup(nla[NFTA_CHAIN_NAME], GFP_KERNEL);
} else {
if (!(flags & NFT_CHAIN_BINDING))
return -EINVAL;

snprintf(name, sizeof(name), "__chain%llu", ++chain_id);
chain->name = kstrdup(name, GFP_KERNEL);
}

if (!chain->name) {
err = -ENOMEM;
goto err1;
Expand Down Expand Up @@ -2976,8 +3004,7 @@ static void nf_tables_rule_destroy(const struct nft_ctx *ctx,
kfree(rule);
}

static void nf_tables_rule_release(const struct nft_ctx *ctx,
struct nft_rule *rule)
void nf_tables_rule_release(const struct nft_ctx *ctx, struct nft_rule *rule)
{
nft_rule_expr_deactivate(ctx, rule, NFT_TRANS_RELEASE);
nf_tables_rule_destroy(ctx, rule);
Expand Down Expand Up @@ -3075,6 +3102,9 @@ static int nf_tables_newrule(struct net *net, struct sock *nlsk,
NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_CHAIN]);
return PTR_ERR(chain);
}
if (nft_chain_is_bound(chain))
return -EOPNOTSUPP;

} else if (nla[NFTA_RULE_CHAIN_ID]) {
chain = nft_chain_lookup_byid(net, nla[NFTA_RULE_CHAIN_ID]);
if (IS_ERR(chain)) {
Expand Down Expand Up @@ -3294,6 +3324,8 @@ static int nf_tables_delrule(struct net *net, struct sock *nlsk,
NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_CHAIN]);
return PTR_ERR(chain);
}
if (nft_chain_is_bound(chain))
return -EOPNOTSUPP;
}

nft_ctx_init(&ctx, net, skb, nlh, family, table, chain, nla);
Expand Down Expand Up @@ -5330,11 +5362,24 @@ static int nf_tables_newsetelem(struct net *net, struct sock *nlsk,
*/
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) {
case NFT_JUMP:
case NFT_GOTO:
data->verdict.chain->use++;
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;
}
}
Expand Down Expand Up @@ -7474,7 +7519,7 @@ static void nft_obj_del(struct nft_object *obj)
list_del_rcu(&obj->list);
}

static void nft_chain_del(struct nft_chain *chain)
void nft_chain_del(struct nft_chain *chain)
{
struct nft_table *table = chain->table;

Expand Down Expand Up @@ -7825,6 +7870,10 @@ static int __nf_tables_abort(struct net *net, bool autoload)
kfree(nft_trans_chain_name(trans));
nft_trans_destroy(trans);
} else {
if (nft_chain_is_bound(trans->ctx.chain)) {
nft_trans_destroy(trans);
break;
}
trans->ctx.table->use--;
nft_chain_del(trans->ctx.chain);
nf_tables_unregister_hook(trans->ctx.net,
Expand Down Expand Up @@ -8321,10 +8370,23 @@ 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:
data->verdict.chain->use--;
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;
}
}
Expand Down
51 changes: 51 additions & 0 deletions net/netfilter/nft_immediate.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -54,6 +54,23 @@ static int nft_immediate_init(const struct nft_ctx *ctx,
if (err < 0)
goto err1;

if (priv->dreg == NFT_REG_VERDICT) {
struct nft_chain *chain = priv->data.verdict.chain;

switch (priv->data.verdict.code) {
case NFT_JUMP:
case NFT_GOTO:
if (nft_chain_is_bound(chain)) {
err = -EBUSY;
goto err1;
}
chain->bound = true;
break;
default:
break;
}
}

return 0;

err1:
Expand Down Expand Up @@ -81,6 +98,39 @@ static void nft_immediate_deactivate(const struct nft_ctx *ctx,
return nft_data_release(&priv->data, nft_dreg_to_type(priv->dreg));
}

static void nft_immediate_destroy(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_ctx chain_ctx;
struct nft_chain *chain;
struct nft_rule *rule;

if (priv->dreg != NFT_REG_VERDICT)
return;

switch (data->verdict.code) {
case NFT_JUMP:
case NFT_GOTO:
chain = data->verdict.chain;

if (!nft_chain_is_bound(chain))
break;

chain_ctx = *ctx;
chain_ctx.chain = chain;

list_for_each_entry(rule, &chain->rules, list)
nf_tables_rule_release(&chain_ctx, rule);

nf_tables_chain_destroy(&chain_ctx);
break;
default:
break;
}
}

static int nft_immediate_dump(struct sk_buff *skb, const struct nft_expr *expr)
{
const struct nft_immediate_expr *priv = nft_expr_priv(expr);
Expand Down Expand Up @@ -170,6 +220,7 @@ static const struct nft_expr_ops nft_imm_ops = {
.init = nft_immediate_init,
.activate = nft_immediate_activate,
.deactivate = nft_immediate_deactivate,
.destroy = nft_immediate_destroy,
.dump = nft_immediate_dump,
.validate = nft_immediate_validate,
.offload = nft_immediate_offload,
Expand Down

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