[PATCH 6.1 135/149] 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 | 163 +++++++++++++++++++++++--------------- net/netfilter/nft_flow_offload.c | 6 - net/netfilter/nft_immediate.c | 8 - net/netfilter/nft_objref.c | 8 + 5 files changed, 141 insertions(+), 75 deletions(-)

--- a/include/net/netfilter/nf_tables.h +++ b/include/net/netfilter/nf_tables.h @@ -1192,6 +1192,29 @@ 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 * @@ -1275,8 +1298,8 @@ struct nft_object { struct list_head list; struct rhlist_head rhlhead; struct nft_object_hash_key key; - u32 genmask:2, - use:30; + u32 genmask:2; + u32 use; u64 handle; u16 udlen; u8 *udata; @@ -1378,8 +1401,8 @@ struct nft_flowtable { char *name; int hooknum; int ops_len; - u32 genmask:2, - use:30; + u32 genmask:2; + u32 use; u64 handle; /* runtime data below here */ struct list_head hook_list ____cacheline_aligned; --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -255,8 +255,10 @@ int nf_tables_bind_chain(const struct nf if (chain->bound) return -EBUSY;

+ if (!nft_use_inc(&chain->use)) + return -EMFILE; + chain->bound = true; - chain->use++; nft_chain_trans_bind(ctx, chain);

return 0; @@ -439,7 +441,7 @@ static int nft_delchain(struct nft_ctx * if (IS_ERR(trans)) return PTR_ERR(trans);

- ctx->table->use--; + nft_use_dec(&ctx->table->use); nft_deactivate_next(ctx->net, ctx->chain);

return 0; @@ -478,7 +480,7 @@ 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; @@ -645,7 +647,7 @@ static int nft_delset(const struct nft_c nft_map_deactivate(ctx, set);

nft_deactivate_next(ctx->net, set); - ctx->table->use--; + nft_use_dec(&ctx->table->use);

return err; } @@ -677,7 +679,7 @@ 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; } @@ -712,7 +714,7 @@ 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; } @@ -2358,9 +2360,6 @@ static int nf_tables_addchain(struct nft unsigned int data_size; int err;

- if (table->use == UINT_MAX) - return -EOVERFLOW; - if (nla[NFTA_CHAIN_HOOK]) { struct nft_stats __percpu *stats = NULL; struct nft_chain_hook hook; @@ -2457,6 +2456,11 @@ static int nf_tables_addchain(struct nft if (err < 0) goto err_destroy_chain;

+ if (!nft_use_inc(&table->use)) { + err = -EMFILE; + goto err_use; + } + trans = nft_trans_chain_add(ctx, NFT_MSG_NEWCHAIN); if (IS_ERR(trans)) { err = PTR_ERR(trans); @@ -2473,10 +2477,11 @@ static int nf_tables_addchain(struct nft goto err_unregister_hook; }

- table->use++; - return 0; + err_unregister_hook: + nft_use_dec_restore(&table->use); +err_use: nf_tables_unregister_hook(net, table, chain); err_destroy_chain: nf_tables_chain_destroy(ctx); @@ -3663,9 +3668,6 @@ static int nf_tables_newrule(struct sk_b 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); @@ -3759,6 +3761,11 @@ static int nf_tables_newrule(struct sk_b } }

+ if (!nft_use_inc(&chain->use)) { + err = -EMFILE; + goto err_release_rule; + } + if (info->nlh->nlmsg_flags & NLM_F_REPLACE) { err = nft_delrule(&ctx, old_rule); if (err < 0) @@ -3790,7 +3797,6 @@ static int nf_tables_newrule(struct sk_b } } kvfree(expr_info); - chain->use++;

if (flow) nft_trans_flow_rule(trans) = flow; @@ -3801,6 +3807,7 @@ static int nf_tables_newrule(struct sk_b return 0;

err_destroy_flow_rule: + nft_use_dec_restore(&chain->use); if (flow) nft_flow_rule_destroy(flow); err_release_rule: @@ -4818,9 +4825,15 @@ static int nf_tables_newset(struct sk_bu alloc_size = sizeof(*set) + size + udlen; if (alloc_size < size || alloc_size > INT_MAX) return -ENOMEM; + + if (!nft_use_inc(&table->use)) + return -EMFILE; + set = kvzalloc(alloc_size, GFP_KERNEL_ACCOUNT); - if (!set) - return -ENOMEM; + if (!set) { + err = -ENOMEM; + goto err_alloc; + }

name = nla_strdup(nla[NFTA_SET_NAME], GFP_KERNEL_ACCOUNT); if (!name) { @@ -4878,7 +4891,7 @@ static int nf_tables_newset(struct sk_bu goto err_set_expr_alloc;

list_add_tail_rcu(&set->list, &table->sets); - table->use++; + return 0;

err_set_expr_alloc: @@ -4890,6 +4903,9 @@ err_set_init: kfree(set->name); err_set_name: kvfree(set); +err_alloc: + nft_use_dec_restore(&table->use); + return err; }

@@ -5024,9 +5040,6 @@ 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;

@@ -5054,10 +5067,12 @@ 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; } @@ -5131,7 +5146,7 @@ void nf_tables_activate_set(const struct nft_clear(ctx->net, set); }

- set->use++; + nft_use_inc_restore(&set->use); } EXPORT_SYMBOL_GPL(nf_tables_activate_set);

@@ -5147,7 +5162,7 @@ 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)) { @@ -5156,7 +5171,7 @@ void nf_tables_deactivate_set(const stru

nft_deactivate_next(ctx->net, set); } - set->use--; + nft_use_dec(&set->use); return; case NFT_TRANS_ABORT: case NFT_TRANS_RELEASE: @@ -5164,7 +5179,7 @@ void nf_tables_deactivate_set(const stru set->flags & (NFT_SET_MAP | NFT_SET_OBJECT)) nft_map_deactivate(ctx, set);

- set->use--; + nft_use_dec(&set->use); fallthrough; default: nf_tables_unbind_set(ctx, set, binding, @@ -5937,7 +5952,7 @@ void nft_set_elem_destroy(const struct n nft_set_elem_expr_destroy(&ctx, 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); @@ -6439,8 +6454,16 @@ static int nft_add_set_elem(struct nft_c set->objtype, genmask); if (IS_ERR(obj)) { err = PTR_ERR(obj); + obj = NULL; goto err_parse_key_end; } + + if (!nft_use_inc(&obj->use)) { + err = -EMFILE; + obj = NULL; + goto err_parse_key_end; + } + err = nft_set_ext_add(&tmpl, NFT_SET_EXT_OBJREF); if (err < 0) goto err_parse_key_end; @@ -6509,10 +6532,9 @@ static int nft_add_set_elem(struct nft_c if (flags) *nft_set_ext_flags(ext) = flags;

- if (obj) { + if (obj) *nft_set_ext_obj(ext) = obj; - obj->use++; - } + if (ulen > 0) { if (nft_set_ext_check(&tmpl, NFT_SET_EXT_USERDATA, ulen) < 0) { err = -EINVAL; @@ -6577,12 +6599,13 @@ err_element_clash: kfree(trans); err_elem_free: nf_tables_set_elem_destroy(ctx, set, elem.priv); - if (obj) - obj->use--; err_parse_data: if (nla[NFTA_SET_ELEM_DATA] != NULL) nft_data_release(&elem.data.val, desc.type); err_parse_key_end: + if (obj) + nft_use_dec_restore(&obj->use); + nft_data_release(&elem.key_end.val, NFT_DATA_VALUE); err_parse_key: nft_data_release(&elem.key.val, NFT_DATA_VALUE); @@ -6663,7 +6686,7 @@ void nft_data_hold(const struct nft_data case NFT_JUMP: case NFT_GOTO: chain = data->verdict.chain; - chain->use++; + nft_use_inc_restore(&chain->use); break; } } @@ -6678,7 +6701,7 @@ static void nft_setelem_data_activate(co 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_setelem_data_deactivate(const struct net *net, @@ -6690,7 +6713,7 @@ static void nft_setelem_data_deactivate( 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, @@ -7229,9 +7252,14 @@ static int nf_tables_newobj(struct sk_bu

nft_ctx_init(&ctx, net, skb, info->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)) { @@ -7265,7 +7293,7 @@ static int nf_tables_newobj(struct sk_bu goto err_obj_ht;

list_add_tail_rcu(&obj->list, &table->objects); - table->use++; + return 0; err_obj_ht: /* queued in transaction log */ @@ -7281,6 +7309,9 @@ err_strdup: kfree(obj); err_init: module_put(type->owner); +err_type: + nft_use_dec_restore(&table->use); + return err; }

@@ -7671,7 +7702,7 @@ 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); fallthrough; default: return; @@ -8019,9 +8050,14 @@ static int nf_tables_newflowtable(struct

nft_ctx_init(&ctx, net, skb, info->nlh, family, table, NULL, nla);

+ if (!nft_use_inc(&table->use)) + return -EMFILE; + flowtable = kzalloc(sizeof(*flowtable), GFP_KERNEL_ACCOUNT); - if (!flowtable) - return -ENOMEM; + if (!flowtable) { + err = -ENOMEM; + goto flowtable_alloc; + }

flowtable->table = table; flowtable->handle = nf_tables_alloc_handle(table); @@ -8076,7 +8112,6 @@ static int nf_tables_newflowtable(struct goto err5;

list_add_tail_rcu(&flowtable->list, &table->flowtables); - table->use++;

return 0; err5: @@ -8093,6 +8128,9 @@ err2: kfree(flowtable->name); err1: kfree(flowtable); +flowtable_alloc: + nft_use_dec_restore(&table->use); + return err; }

@@ -9378,7 +9416,7 @@ 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); @@ -9597,7 +9635,7 @@ static int __nf_tables_abort(struct net nft_trans_destroy(trans); break; } - 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, @@ -9605,7 +9643,7 @@ 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; @@ -9614,7 +9652,7 @@ static int __nf_tables_abort(struct net nft_trans_destroy(trans); break; } - 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), @@ -9623,7 +9661,7 @@ static int __nf_tables_abort(struct net nft_flow_rule_destroy(nft_trans_flow_rule(trans)); 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)); if (trans->ctx.chain->flags & NFT_CHAIN_HW_OFFLOAD) @@ -9636,7 +9674,7 @@ static int __nf_tables_abort(struct net nft_trans_destroy(trans); break; } - trans->ctx.table->use--; + nft_use_dec_restore(&trans->ctx.table->use); if (nft_trans_set_bound(trans)) { nft_trans_destroy(trans); break; @@ -9644,7 +9682,7 @@ 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)); if (nft_trans_set(trans)->flags & (NFT_SET_MAP | NFT_SET_OBJECT)) nft_map_activate(&trans->ctx, nft_trans_set(trans)); @@ -9687,12 +9725,12 @@ static int __nf_tables_abort(struct net nft_obj_destroy(&trans->ctx, nft_trans_obj_newobj(trans)); nft_trans_destroy(trans); } else { - trans->ctx.table->use--; + nft_use_dec_restore(&trans->ctx.table->use); nft_obj_del(nft_trans_obj(trans)); } 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; @@ -9701,7 +9739,7 @@ static int __nf_tables_abort(struct net nft_unregister_flowtable_net_hooks(net, &nft_trans_flowtable_hooks(trans)); } else { - 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)->hook_list); @@ -9712,7 +9750,7 @@ static int __nf_tables_abort(struct net list_splice(&nft_trans_flowtable_hooks(trans), &nft_trans_flowtable(trans)->hook_list); } else { - 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); @@ -10165,8 +10203,9 @@ static int nft_verdict_init(const struct if (desc->flags & NFT_DATA_DESC_SETELEM && chain->flags & NFT_CHAIN_BINDING) return -EINVAL; + if (!nft_use_inc(&chain->use)) + return -EMFILE;

- chain->use++; data->verdict.chain = chain; break; } @@ -10184,7 +10223,7 @@ static void nft_verdict_uninit(const str case NFT_JUMP: case NFT_GOTO: chain = data->verdict.chain; - chain->use--; + nft_use_dec(&chain->use); break; } } @@ -10353,11 +10392,11 @@ 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; @@ -10410,18 +10449,18 @@ 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); if (set->flags & (NFT_SET_MAP | NFT_SET_OBJECT)) nft_map_deactivate(&ctx, set);

@@ -10429,13 +10468,13 @@ static void __nft_release_table(struct n } list_for_each_entry_safe(obj, ne, &table->objects, list) { nft_obj_del(obj); - 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); } nf_tables_table_destroy(&ctx); --- a/net/netfilter/nft_flow_offload.c +++ b/net/netfilter/nft_flow_offload.c @@ -404,8 +404,10 @@ 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); } @@ -424,7 +426,7 @@ 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_immediate.c +++ b/net/netfilter/nft_immediate.c @@ -168,7 +168,7 @@ static void nft_immediate_deactivate(con nft_immediate_chain_deactivate(ctx, chain, phase); nft_chain_del(chain); chain->bound = false; - chain->table->use--; + nft_use_dec(&chain->table->use); break; } break; @@ -207,7 +207,7 @@ static void nft_immediate_destroy(const * let the transaction records release this chain and its rules. */ if (chain->bound) { - chain->use--; + nft_use_dec(&chain->use); break; }

@@ -215,9 +215,9 @@ static void nft_immediate_destroy(const chain_ctx = *ctx; chain_ctx.chain = chain;

- chain->use--; + nft_use_dec(&chain->use); list_for_each_entry_safe(rule, n, &chain->rules, list) { - chain->use--; + nft_use_dec(&chain->use); list_del(&rule->list); nf_tables_rule_destroy(&chain_ctx, rule); } --- a/net/netfilter/nft_objref.c +++ b/net/netfilter/nft_objref.c @@ -41,8 +41,10 @@ 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; } @@ -71,7 +73,7 @@ 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, @@ -79,7 +81,7 @@ 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;