[PATCH 4.19 26/33] netfilter: nf_tables: report use refcount overflow

From: Pablo Neira Ayuso pablo@netfilter.org

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 --- include/net/netfilter/nf_tables.h | 31 ++++++- net/netfilter/nf_tables_api.c | 166 +++++++++++++++++++++++--------------- net/netfilter/nft_flow_offload.c | 6 - net/netfilter/nft_objref.c | 8 + 4 files changed, 140 insertions(+), 71 deletions(-)

--- a/include/net/netfilter/nf_tables.h +++ b/include/net/netfilter/nf_tables.h @@ -992,6 +992,29 @@ int __nft_release_basechain(struct nft_c

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; --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -266,7 +266,7 @@ static int nft_delchain(struct nft_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_ /* 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_c 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 *ct 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_c 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 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 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 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 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 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 } } 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 * 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 * 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_ 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_ 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 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 stru 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 n } } 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_c 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_c 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 n */ 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 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(cons 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 *

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 * 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(cons 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

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 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 * */ 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 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 } 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 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 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 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

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_c 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 n 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); --- a/net/netfilter/nft_flow_offload.c +++ b/net/netfilter/nft_flow_offload.c @@ -169,8 +169,10 @@ static int nft_flow_offload_init(const s 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(co { 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, --- a/net/netfilter/nft_objref.c +++ b/net/netfilter/nft_objref.c @@ -43,8 +43,10 @@ static int nft_objref_init(const struct 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 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 st { struct nft_object *obj = nft_objref_priv(expr);

- obj->use++; + nft_use_inc_restore(&obj->use); }

static struct nft_expr_type nft_objref_type;