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netfilter: nf_tables: report use refcount overflow

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commit 1689f25924ada8fe14a4a82c38925d04994c7142 upstream.

Overflow use refcount checks are not complete.

Add helper function to deal with object reference counter tracking.
Report -EMFILE in case UINT_MAX is reached.

nft_use_dec() splats in case that reference counter underflows,
which should not ever happen.

Add nft_use_inc_restore() and nft_use_dec_restore() which are used
to restore reference counter from error and abort paths.

Use u32 in nft_flowtable and nft_object since helper functions cannot
work on bitfields.

Remove the few early incomplete checks now that the helper functions
are in place and used to check for refcount overflow.

Fixes: 96518518cc41 ("netfilter: add nftables")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Pablo Neira Ayuso 2023-08-13 00:09:03 +02:00 committed by Greg Kroah-Hartman
parent 00c0a1fb18
commit 92fe04aaca
4 changed files with 140 additions and 71 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

31
include/net/netfilter/nf_tables.h
View File

@ -992,6 +992,29 @@ int __nft_release_basechain(struct nft_ctx *ctx);
unsigned int nft_do_chain(struct nft_pktinfo *pkt, void *priv);
static inline bool nft_use_inc(u32 *use)
{
if (*use == UINT_MAX)
return false;
(*use)++;
return true;
}
static inline void nft_use_dec(u32 *use)
{
WARN_ON_ONCE((*use)-- == 0);
}
/* For error and abort path: restore use counter to previous state. */
static inline void nft_use_inc_restore(u32 *use)
{
WARN_ON_ONCE(!nft_use_inc(use));
}
#define nft_use_dec_restore nft_use_dec
/**
* struct nft_table - nf_tables table
*
@ -1050,8 +1073,8 @@ struct nft_object {
struct list_head list;
char *name;
struct nft_table *table;
u32 genmask:2,
use:30;
u32 genmask:2;
u32 use;
u64 handle;
/* runtime data below here */
const struct nft_object_ops *ops ____cacheline_aligned;
@ -1149,8 +1172,8 @@ struct nft_flowtable {
int hooknum;
int priority;
int ops_len;
u32 genmask:2,
use:30;
u32 genmask:2;
u32 use;
u64 handle;
/* runtime data below here */
struct nf_hook_ops *ops ____cacheline_aligned;

166
net/netfilter/nf_tables_api.c
View File

@ -266,7 +266,7 @@ static int nft_delchain(struct nft_ctx *ctx)
if (err < 0)
return err;
ctx->table->use--;
nft_use_dec(&ctx->table->use);
nft_deactivate_next(ctx->net, ctx->chain);
return err;
@ -307,7 +307,7 @@ nf_tables_delrule_deactivate(struct nft_ctx *ctx, struct nft_rule *rule)
/* You cannot delete the same rule twice */
if (nft_is_active_next(ctx->net, rule)) {
nft_deactivate_next(ctx->net, rule);
ctx->chain->use--;
nft_use_dec(&ctx->chain->use);
return 0;
}
return -ENOENT;
@ -396,7 +396,7 @@ static int nft_delset(const struct nft_ctx *ctx, struct nft_set *set)
return err;
nft_deactivate_next(ctx->net, set);
ctx->table->use--;
nft_use_dec(&ctx->table->use);
return err;
}
@ -428,7 +428,7 @@ static int nft_delobj(struct nft_ctx *ctx, struct nft_object *obj)
return err;
nft_deactivate_next(ctx->net, obj);
ctx->table->use--;
nft_use_dec(&ctx->table->use);
return err;
}
@ -462,7 +462,7 @@ static int nft_delflowtable(struct nft_ctx *ctx,
return err;
nft_deactivate_next(ctx->net, flowtable);
ctx->table->use--;
nft_use_dec(&ctx->table->use);
return err;
}
@ -1660,9 +1660,6 @@ static int nf_tables_addchain(struct nft_ctx *ctx, u8 family, u8 genmask,
struct nft_rule **rules;
int err;
if (table->use == UINT_MAX)
return -EOVERFLOW;
if (nla[NFTA_CHAIN_HOOK]) {
struct nft_chain_hook hook;
struct nf_hook_ops *ops;
@ -1734,6 +1731,11 @@ static int nf_tables_addchain(struct nft_ctx *ctx, u8 family, u8 genmask,
if (err < 0)
goto err1;
if (!nft_use_inc(&table->use)) {
err = -EMFILE;
goto err_use;
}
err = rhltable_insert_key(&table->chains_ht, chain->name,
&chain->rhlhead, nft_chain_ht_params);
if (err)
@ -1746,11 +1748,12 @@ static int nf_tables_addchain(struct nft_ctx *ctx, u8 family, u8 genmask,
goto err2;
}
table->use++;
list_add_tail_rcu(&chain->list, &table->chains);
return 0;
err2:
nft_use_dec_restore(&table->use);
err_use:
nf_tables_unregister_hook(net, table, chain);
err1:
nf_tables_chain_destroy(ctx);
@ -2692,9 +2695,6 @@ static int nf_tables_newrule(struct net *net, struct sock *nlsk,
return -EINVAL;
handle = nf_tables_alloc_handle(table);
if (chain->use == UINT_MAX)
return -EOVERFLOW;
if (nla[NFTA_RULE_POSITION]) {
pos_handle = be64_to_cpu(nla_get_be64(nla[NFTA_RULE_POSITION]));
old_rule = __nft_rule_lookup(chain, pos_handle);
@ -2770,23 +2770,28 @@ static int nf_tables_newrule(struct net *net, struct sock *nlsk,
expr = nft_expr_next(expr);
}
if (!nft_use_inc(&chain->use)) {
err = -EMFILE;
goto err2;
}
if (nlh->nlmsg_flags & NLM_F_REPLACE) {
trans = nft_trans_rule_add(&ctx, NFT_MSG_NEWRULE, rule);
if (trans == NULL) {
err = -ENOMEM;
goto err2;
goto err_destroy_flow_rule;
}
err = nft_delrule(&ctx, old_rule);
if (err < 0) {
nft_trans_destroy(trans);
goto err2;
goto err_destroy_flow_rule;
}
list_add_tail_rcu(&rule->list, &old_rule->list);
} else {
if (nft_trans_rule_add(&ctx, NFT_MSG_NEWRULE, rule) == NULL) {
err = -ENOMEM;
goto err2;
goto err_destroy_flow_rule;
}
if (nlh->nlmsg_flags & NLM_F_APPEND) {
@ -2802,12 +2807,14 @@ static int nf_tables_newrule(struct net *net, struct sock *nlsk,
}
}
kvfree(info);
chain->use++;
if (nft_net->validate_state == NFT_VALIDATE_DO)
return nft_table_validate(net, table);
return 0;
err_destroy_flow_rule:
nft_use_dec_restore(&chain->use);
err2:
nft_rule_expr_deactivate(&ctx, rule, NFT_TRANS_PREPARE_ERROR);
nf_tables_rule_destroy(&ctx, rule);
@ -3625,10 +3632,15 @@ static int nf_tables_newset(struct net *net, struct sock *nlsk,
if (ops->privsize != NULL)
size = ops->privsize(nla, &desc);
if (!nft_use_inc(&table->use)) {
err = -EMFILE;
goto err1;
}
set = kvzalloc(sizeof(*set) + size + udlen, GFP_KERNEL);
if (!set) {
err = -ENOMEM;
goto err1;
goto err_alloc;
}
name = nla_strdup(nla[NFTA_SET_NAME], GFP_KERNEL);
@ -3675,7 +3687,7 @@ static int nf_tables_newset(struct net *net, struct sock *nlsk,
goto err4;
list_add_tail_rcu(&set->list, &table->sets);
table->use++;
return 0;
err4:
@ -3684,6 +3696,8 @@ err3:
kfree(set->name);
err2:
kvfree(set);
err_alloc:
nft_use_dec_restore(&table->use);
err1:
module_put(to_set_type(ops)->owner);
return err;
@ -3770,9 +3784,6 @@ int nf_tables_bind_set(const struct nft_ctx *ctx, struct nft_set *set,
struct nft_set_binding *i;
struct nft_set_iter iter;
if (set->use == UINT_MAX)
return -EOVERFLOW;
if (!list_empty(&set->bindings) && nft_set_is_anonymous(set))
return -EBUSY;
@ -3797,10 +3808,12 @@ int nf_tables_bind_set(const struct nft_ctx *ctx, struct nft_set *set,
return iter.err;
}
bind:
if (!nft_use_inc(&set->use))
return -EMFILE;
binding->chain = ctx->chain;
list_add_tail_rcu(&binding->list, &set->bindings);
nft_set_trans_bind(ctx, set);
set->use++;
return 0;
}
@ -3825,7 +3838,7 @@ void nf_tables_activate_set(const struct nft_ctx *ctx, struct nft_set *set)
if (nft_set_is_anonymous(set))
nft_clear(ctx->net, set);
set->use++;
nft_use_inc_restore(&set->use);
}
EXPORT_SYMBOL_GPL(nf_tables_activate_set);
@ -3841,17 +3854,17 @@ void nf_tables_deactivate_set(const struct nft_ctx *ctx, struct nft_set *set,
else
list_del_rcu(&binding->list);
set->use--;
nft_use_dec(&set->use);
break;
case NFT_TRANS_PREPARE:
if (nft_set_is_anonymous(set))
nft_deactivate_next(ctx->net, set);
set->use--;
nft_use_dec(&set->use);
return;
case NFT_TRANS_ABORT:
case NFT_TRANS_RELEASE:
set->use--;
nft_use_dec(&set->use);
/* fall through */
default:
nf_tables_unbind_set(ctx, set, binding,
@ -4433,7 +4446,7 @@ void nft_set_elem_destroy(const struct nft_set *set, void *elem,
}
}
if (nft_set_ext_exists(ext, NFT_SET_EXT_OBJREF))
(*nft_set_ext_obj(ext))->use--;
nft_use_dec(&(*nft_set_ext_obj(ext))->use);
kfree(elem);
}
EXPORT_SYMBOL_GPL(nft_set_elem_destroy);
@ -4542,8 +4555,16 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,
set->objtype, genmask);
if (IS_ERR(obj)) {
err = PTR_ERR(obj);
obj = NULL;
goto err2;
}
if (!nft_use_inc(&obj->use)) {
err = -EMFILE;
obj = NULL;
goto err2;
}
nft_set_ext_add(&tmpl, NFT_SET_EXT_OBJREF);
}
@ -4608,10 +4629,8 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,
udata->len = ulen - 1;
nla_memcpy(&udata->data, nla[NFTA_SET_ELEM_USERDATA], ulen);
}
if (obj) {
if (obj)
*nft_set_ext_obj(ext) = obj;
obj->use++;
}
trans = nft_trans_elem_alloc(ctx, NFT_MSG_NEWSETELEM, set);
if (trans == NULL)
@ -4657,13 +4676,14 @@ err6:
err5:
kfree(trans);
err4:
if (obj)
obj->use--;
kfree(elem.priv);
err3:
if (nla[NFTA_SET_ELEM_DATA] != NULL)
nft_data_release(&elem.data.val, desc.type);
err2:
if (obj)
nft_use_dec_restore(&obj->use);
nft_data_release(&elem.key.val, NFT_DATA_VALUE);
err1:
return err;
@ -4723,11 +4743,14 @@ 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;
if (type == NFT_DATA_VERDICT) {
switch (data->verdict.code) {
case NFT_JUMP:
case NFT_GOTO:
data->verdict.chain->use++;
chain = data->verdict.chain;
nft_use_inc_restore(&chain->use);
break;
}
}
@ -4742,7 +4765,7 @@ static void nft_set_elem_activate(const struct net *net,
if (nft_set_ext_exists(ext, NFT_SET_EXT_DATA))
nft_data_hold(nft_set_ext_data(ext), set->dtype);
if (nft_set_ext_exists(ext, NFT_SET_EXT_OBJREF))
(*nft_set_ext_obj(ext))->use++;
nft_use_inc_restore(&(*nft_set_ext_obj(ext))->use);
}
static void nft_set_elem_deactivate(const struct net *net,
@ -4754,7 +4777,7 @@ static void nft_set_elem_deactivate(const struct net *net,
if (nft_set_ext_exists(ext, NFT_SET_EXT_DATA))
nft_data_release(nft_set_ext_data(ext), set->dtype);
if (nft_set_ext_exists(ext, NFT_SET_EXT_OBJREF))
(*nft_set_ext_obj(ext))->use--;
nft_use_dec(&(*nft_set_ext_obj(ext))->use);
}
static int nft_del_setelem(struct nft_ctx *ctx, struct nft_set *set,
@ -5151,9 +5174,14 @@ static int nf_tables_newobj(struct net *net, struct sock *nlsk,
nft_ctx_init(&ctx, net, skb, nlh, family, table, NULL, nla);
if (!nft_use_inc(&table->use))
return -EMFILE;
type = nft_obj_type_get(net, objtype);
if (IS_ERR(type))
return PTR_ERR(type);
if (IS_ERR(type)) {
err = PTR_ERR(type);
goto err_type;
}
obj = nft_obj_init(&ctx, type, nla[NFTA_OBJ_DATA]);
if (IS_ERR(obj)) {
@ -5174,7 +5202,7 @@ static int nf_tables_newobj(struct net *net, struct sock *nlsk,
goto err3;
list_add_tail_rcu(&obj->list, &table->objects);
table->use++;
return 0;
err3:
kfree(obj->name);
@ -5184,6 +5212,9 @@ err2:
kfree(obj);
err1:
module_put(type->owner);
err_type:
nft_use_dec_restore(&table->use);
return err;
}
@ -5527,7 +5558,7 @@ void nf_tables_deactivate_flowtable(const struct nft_ctx *ctx,
case NFT_TRANS_PREPARE:
case NFT_TRANS_ABORT:
case NFT_TRANS_RELEASE:
flowtable->use--;
nft_use_dec(&flowtable->use);
/* fall through */
default:
return;
@ -5734,9 +5765,14 @@ static int nf_tables_newflowtable(struct net *net, struct sock *nlsk,
nft_ctx_init(&ctx, net, skb, nlh, family, table, NULL, nla);
if (!nft_use_inc(&table->use))
return -EMFILE;
flowtable = kzalloc(sizeof(*flowtable), GFP_KERNEL);
if (!flowtable)
return -ENOMEM;
if (!flowtable) {
err = -ENOMEM;
goto flowtable_alloc;
}
flowtable->table = table;
flowtable->handle = nf_tables_alloc_handle(table);
@ -5790,7 +5826,6 @@ static int nf_tables_newflowtable(struct net *net, struct sock *nlsk,
goto err6;
list_add_tail_rcu(&flowtable->list, &table->flowtables);
table->use++;
return 0;
err6:
@ -5808,6 +5843,9 @@ err2:
kfree(flowtable->name);
err1:
kfree(flowtable);
flowtable_alloc:
nft_use_dec_restore(&table->use);
return err;
}
@ -6682,7 +6720,7 @@ static int nf_tables_commit(struct net *net, struct sk_buff *skb)
*/
if (nft_set_is_anonymous(nft_trans_set(trans)) &&
!list_empty(&nft_trans_set(trans)->bindings))
trans->ctx.table->use--;
nft_use_dec(&trans->ctx.table->use);
nf_tables_set_notify(&trans->ctx, nft_trans_set(trans),
NFT_MSG_NEWSET, GFP_KERNEL);
@ -6808,7 +6846,7 @@ static int __nf_tables_abort(struct net *net)
kfree(nft_trans_chain_name(trans));
nft_trans_destroy(trans);
} else {
trans->ctx.table->use--;
nft_use_dec_restore(&trans->ctx.table->use);
nft_chain_del(trans->ctx.chain);
nf_tables_unregister_hook(trans->ctx.net,
trans->ctx.table,
@ -6816,25 +6854,25 @@ static int __nf_tables_abort(struct net *net)
}
break;
case NFT_MSG_DELCHAIN:
trans->ctx.table->use++;
nft_use_inc_restore(&trans->ctx.table->use);
nft_clear(trans->ctx.net, trans->ctx.chain);
nft_trans_destroy(trans);
break;
case NFT_MSG_NEWRULE:
trans->ctx.chain->use--;
nft_use_dec_restore(&trans->ctx.chain->use);
list_del_rcu(&nft_trans_rule(trans)->list);
nft_rule_expr_deactivate(&trans->ctx,
nft_trans_rule(trans),
NFT_TRANS_ABORT);
break;
case NFT_MSG_DELRULE:
trans->ctx.chain->use++;
nft_use_inc_restore(&trans->ctx.chain->use);
nft_clear(trans->ctx.net, nft_trans_rule(trans));
nft_rule_expr_activate(&trans->ctx, nft_trans_rule(trans));
nft_trans_destroy(trans);
break;
case NFT_MSG_NEWSET:
trans->ctx.table->use--;
nft_use_dec_restore(&trans->ctx.table->use);
if (nft_trans_set_bound(trans)) {
nft_trans_destroy(trans);
break;
@ -6842,7 +6880,7 @@ static int __nf_tables_abort(struct net *net)
list_del_rcu(&nft_trans_set(trans)->list);
break;
case NFT_MSG_DELSET:
trans->ctx.table->use++;
nft_use_inc_restore(&trans->ctx.table->use);
nft_clear(trans->ctx.net, nft_trans_set(trans));
nft_trans_destroy(trans);
break;
@ -6865,22 +6903,22 @@ static int __nf_tables_abort(struct net *net)
nft_trans_destroy(trans);
break;
case NFT_MSG_NEWOBJ:
trans->ctx.table->use--;
nft_use_dec_restore(&trans->ctx.table->use);
list_del_rcu(&nft_trans_obj(trans)->list);
break;
case NFT_MSG_DELOBJ:
trans->ctx.table->use++;
nft_use_inc_restore(&trans->ctx.table->use);
nft_clear(trans->ctx.net, nft_trans_obj(trans));
nft_trans_destroy(trans);
break;
case NFT_MSG_NEWFLOWTABLE:
trans->ctx.table->use--;
nft_use_dec_restore(&trans->ctx.table->use);
list_del_rcu(&nft_trans_flowtable(trans)->list);
nft_unregister_flowtable_net_hooks(net,
nft_trans_flowtable(trans));
break;
case NFT_MSG_DELFLOWTABLE:
trans->ctx.table->use++;
nft_use_inc_restore(&trans->ctx.table->use);
nft_clear(trans->ctx.net, nft_trans_flowtable(trans));
nft_trans_destroy(trans);
break;
@ -7294,8 +7332,9 @@ static int nft_verdict_init(const struct nft_ctx *ctx, struct nft_data *data,
return PTR_ERR(chain);
if (nft_is_base_chain(chain))
return -EOPNOTSUPP;
if (!nft_use_inc(&chain->use))
return -EMFILE;
chain->use++;
data->verdict.chain = chain;
break;
}
@ -7307,10 +7346,13 @@ 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;
switch (data->verdict.code) {
case NFT_JUMP:
case NFT_GOTO:
data->verdict.chain->use--;
chain = data->verdict.chain;
nft_use_dec(&chain->use);
break;
}
}
@ -7463,11 +7505,11 @@ int __nft_release_basechain(struct nft_ctx *ctx)
nf_tables_unregister_hook(ctx->net, ctx->chain->table, ctx->chain);
list_for_each_entry_safe(rule, nr, &ctx->chain->rules, list) {
list_del(&rule->list);
ctx->chain->use--;
nft_use_dec(&ctx->chain->use);
nf_tables_rule_release(ctx, rule);
}
nft_chain_del(ctx->chain);
ctx->table->use--;
nft_use_dec(&ctx->table->use);
nf_tables_chain_destroy(ctx);
return 0;
@ -7496,29 +7538,29 @@ static void __nft_release_table(struct net *net, struct nft_table *table)
ctx.chain = chain;
list_for_each_entry_safe(rule, nr, &chain->rules, list) {
list_del(&rule->list);
chain->use--;
nft_use_dec(&chain->use);
nf_tables_rule_release(&ctx, rule);
}
}
list_for_each_entry_safe(flowtable, nf, &table->flowtables, list) {
list_del(&flowtable->list);
table->use--;
nft_use_dec(&table->use);
nf_tables_flowtable_destroy(flowtable);
}
list_for_each_entry_safe(set, ns, &table->sets, list) {
list_del(&set->list);
table->use--;
nft_use_dec(&table->use);
nft_set_destroy(set);
}
list_for_each_entry_safe(obj, ne, &table->objects, list) {
list_del(&obj->list);
table->use--;
nft_use_dec(&table->use);
nft_obj_destroy(&ctx, obj);
}
list_for_each_entry_safe(chain, nc, &table->chains, list) {
ctx.chain = chain;
nft_chain_del(chain);
table->use--;
nft_use_dec(&table->use);
nf_tables_chain_destroy(&ctx);
}
list_del(&table->list);

6
net/netfilter/nft_flow_offload.c
View File

@ -169,8 +169,10 @@ static int nft_flow_offload_init(const struct nft_ctx *ctx,
if (IS_ERR(flowtable))
return PTR_ERR(flowtable);
if (!nft_use_inc(&flowtable->use))
return -EMFILE;
priv->flowtable = flowtable;
flowtable->use++;
return nf_ct_netns_get(ctx->net, ctx->family);
}
@ -189,7 +191,7 @@ static void nft_flow_offload_activate(const struct nft_ctx *ctx,
{
struct nft_flow_offload *priv = nft_expr_priv(expr);
priv->flowtable->use++;
nft_use_inc_restore(&priv->flowtable->use);
}
static void nft_flow_offload_destroy(const struct nft_ctx *ctx,

8
net/netfilter/nft_objref.c
View File

@ -43,8 +43,10 @@ static int nft_objref_init(const struct nft_ctx *ctx,
if (IS_ERR(obj))
return -ENOENT;
if (!nft_use_inc(&obj->use))
return -EMFILE;
nft_objref_priv(expr) = obj;
obj->use++;
return 0;
}
@ -73,7 +75,7 @@ static void nft_objref_deactivate(const struct nft_ctx *ctx,
if (phase == NFT_TRANS_COMMIT)
return;
obj->use--;
nft_use_dec(&obj->use);
}
static void nft_objref_activate(const struct nft_ctx *ctx,
@ -81,7 +83,7 @@ static void nft_objref_activate(const struct nft_ctx *ctx,
{
struct nft_object *obj = nft_objref_priv(expr);
obj->use++;
nft_use_inc_restore(&obj->use);
}
static struct nft_expr_type nft_objref_type;