* [PATCH -stable,4.14 1/1] netfilter: nf_tables: report use refcount overflow
2023-08-12 22:09 [PATCH -stable,4.14 0/1] netfilter stable fix for 4.14 Pablo Neira Ayuso
@ 2023-08-12 22:09 ` Pablo Neira Ayuso
2023-08-13 16:33 ` [PATCH -stable,4.14 0/1] netfilter stable fix for 4.14 Greg KH
1 sibling, 0 replies; 3+ messages in thread
From: Pablo Neira Ayuso @ 2023-08-12 22:09 UTC (permalink / raw)
To: netfilter-devel; +Cc: gregkh, stable, sashal
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>
---
include/net/netfilter/nf_tables.h | 27 +++++-
net/netfilter/nf_tables_api.c | 143 +++++++++++++++++++-----------
net/netfilter/nft_objref.c | 8 +-
3 files changed, 119 insertions(+), 59 deletions(-)
diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
index d5e933e6a611..e71e155f3b88 100644
--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -968,6 +968,29 @@ 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
*
@@ -1051,8 +1074,8 @@ struct nft_object {
struct list_head list;
char *name;
struct nft_table *table;
- u32 genmask:2,
- use:30;
+ u32 genmask:2;
+ u32 use;
/* runtime data below here */
const struct nft_object_ops *ops ____cacheline_aligned;
unsigned char data[]
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index b016ae68d9db..e3c4fb6d5408 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -248,7 +248,7 @@ 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;
@@ -289,7 +289,7 @@ 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;
@@ -378,7 +378,7 @@ 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;
}
@@ -410,7 +410,7 @@ 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;
}
@@ -1421,9 +1421,6 @@ static int nf_tables_addchain(struct nft_ctx *ctx, u8 family, u8 genmask,
unsigned int i;
int err;
- if (table->use == UINT_MAX)
- return -EOVERFLOW;
-
if (nla[NFTA_CHAIN_HOOK]) {
struct nft_chain_hook hook;
struct nf_hook_ops *ops;
@@ -1491,16 +1488,22 @@ 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;
+ }
+
ctx->chain = chain;
err = nft_trans_chain_add(ctx, NFT_MSG_NEWCHAIN);
if (err < 0)
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_hooks(net, table, chain, afi->nops);
err1:
nf_tables_chain_destroy(chain);
@@ -2371,9 +2374,6 @@ static int nf_tables_newrule(struct net *net, struct sock *nlsk,
if (!create || nlh->nlmsg_flags & NLM_F_REPLACE)
return -EINVAL;
handle = nf_tables_alloc_handle(table);
-
- if (chain->use == UINT_MAX)
- return -EOVERFLOW;
}
if (nla[NFTA_RULE_POSITION]) {
@@ -2441,23 +2441,28 @@ 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) {
@@ -2472,9 +2477,11 @@ static int nf_tables_newrule(struct net *net, struct sock *nlsk,
list_add_rcu(&rule->list, &chain->rules);
}
}
- chain->use++;
+
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);
@@ -3262,10 +3269,15 @@ 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);
@@ -3310,7 +3322,7 @@ 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:
@@ -3319,6 +3331,8 @@ static int nf_tables_newset(struct net *net, struct sock *nlsk,
kfree(set->name);
err2:
kvfree(set);
+err_alloc:
+ nft_use_dec_restore(&table->use);
err1:
module_put(ops->type->owner);
return err;
@@ -3393,9 +3407,6 @@ 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) && set->flags & NFT_SET_ANONYMOUS)
return -EBUSY;
@@ -3420,10 +3431,12 @@ 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;
}
@@ -3448,7 +3461,7 @@ void nf_tables_activate_set(const struct nft_ctx *ctx, struct nft_set *set)
if (set->flags & NFT_SET_ANONYMOUS)
nft_clear(ctx->net, set);
- set->use++;
+ nft_use_inc_restore(&set->use);
}
EXPORT_SYMBOL_GPL(nf_tables_activate_set);
@@ -3464,17 +3477,17 @@ 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 (set->flags & NFT_SET_ANONYMOUS)
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,
@@ -3947,7 +3960,7 @@ void nft_set_elem_destroy(const struct nft_set *set, void *elem,
if (destroy_expr && nft_set_ext_exists(ext, NFT_SET_EXT_EXPR))
nf_tables_expr_destroy(NULL, nft_set_ext_expr(ext));
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);
@@ -4090,8 +4103,16 @@ 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);
}
@@ -4150,10 +4171,8 @@ 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)
@@ -4199,13 +4218,14 @@ static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,
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;
@@ -4266,11 +4286,14 @@ 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;
}
}
@@ -4285,7 +4308,7 @@ 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,
@@ -4297,7 +4320,7 @@ 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,
@@ -4672,9 +4695,14 @@ static int nf_tables_newobj(struct net *net, struct sock *nlsk,
nft_ctx_init(&ctx, net, skb, nlh, afi, table, NULL, nla);
+ if (!nft_use_inc(&table->use))
+ return -EMFILE;
+
type = nft_obj_type_get(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)) {
@@ -4693,7 +4721,7 @@ 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);
@@ -4703,6 +4731,9 @@ static int nf_tables_newobj(struct net *net, struct sock *nlsk,
kfree(obj);
err1:
module_put(type->owner);
+err_type:
+ nft_use_dec_restore(&table->use);
+
return err;
}
@@ -5304,7 +5335,7 @@ static int nf_tables_commit(struct net *net, struct sk_buff *skb)
*/
if (nft_trans_set(trans)->flags & NFT_SET_ANONYMOUS &&
!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);
@@ -5418,7 +5449,7 @@ static int nf_tables_abort(struct net *net, struct sk_buff *skb)
kfree(nft_trans_chain_name(trans));
nft_trans_destroy(trans);
} else {
- trans->ctx.table->use--;
+ nft_use_dec_restore(&trans->ctx.table->use);
list_del_rcu(&trans->ctx.chain->list);
nf_tables_unregister_hooks(trans->ctx.net,
trans->ctx.table,
@@ -5427,25 +5458,25 @@ static int nf_tables_abort(struct net *net, struct sk_buff *skb)
}
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;
@@ -5453,7 +5484,7 @@ static int nf_tables_abort(struct net *net, struct sk_buff *skb)
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;
@@ -5477,11 +5508,11 @@ static int nf_tables_abort(struct net *net, struct sk_buff *skb)
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;
@@ -5879,8 +5910,9 @@ 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;
}
@@ -5892,10 +5924,13 @@ 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;
}
}
@@ -6056,11 +6091,11 @@ int __nft_release_basechain(struct nft_ctx *ctx)
ctx->afi->nops);
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);
}
list_del(&ctx->chain->list);
- ctx->table->use--;
+ nft_use_dec(&ctx->table->use);
nf_tables_chain_destroy(ctx->chain);
return 0;
@@ -6090,23 +6125,23 @@ static void __nft_release_afinfo(struct net *net, struct nft_af_info *afi)
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(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(obj);
}
list_for_each_entry_safe(chain, nc, &table->chains, list) {
list_del(&chain->list);
- table->use--;
+ nft_use_dec(&table->use);
nf_tables_chain_destroy(chain);
}
list_del(&table->list);
diff --git a/net/netfilter/nft_objref.c b/net/netfilter/nft_objref.c
index 8ad0be6c53fd..f3c5d4b14657 100644
--- a/net/netfilter/nft_objref.c
+++ b/net/netfilter/nft_objref.c
@@ -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;
--
2.30.2
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