diff options
| -rw-r--r-- | net/netfilter/nft_compat.c | 92 |
1 files changed, 58 insertions, 34 deletions
diff --git a/net/netfilter/nft_compat.c b/net/netfilter/nft_compat.c index 8e23726b9081..870d8c29dae9 100644 --- a/net/netfilter/nft_compat.c +++ b/net/netfilter/nft_compat.c @@ -27,14 +27,24 @@ struct nft_xt { struct list_head head; struct nft_expr_ops ops; unsigned int refcnt; + + /* Unlike other expressions, ops doesn't have static storage duration. + * nft core assumes they do. We use kfree_rcu so that nft core can + * can check expr->ops->size even after nft_compat->destroy() frees + * the nft_xt struct that holds the ops structure. + */ + struct rcu_head rcu_head; }; -static void nft_xt_put(struct nft_xt *xt) +static bool nft_xt_put(struct nft_xt *xt) { if (--xt->refcnt == 0) { list_del(&xt->head); - kfree(xt); + kfree_rcu(xt, rcu_head); + return true; } + + return false; } static int nft_compat_chain_validate_dependency(const char *tablename, @@ -226,6 +236,7 @@ nft_target_init(const struct nft_ctx *ctx, const struct nft_expr *expr, struct xt_target *target = expr->ops->data; struct xt_tgchk_param par; size_t size = XT_ALIGN(nla_len(tb[NFTA_TARGET_INFO])); + struct nft_xt *nft_xt; u16 proto = 0; bool inv = false; union nft_entry e = {}; @@ -236,25 +247,22 @@ nft_target_init(const struct nft_ctx *ctx, const struct nft_expr *expr, if (ctx->nla[NFTA_RULE_COMPAT]) { ret = nft_parse_compat(ctx->nla[NFTA_RULE_COMPAT], &proto, &inv); if (ret < 0) - goto err; + return ret; } nft_target_set_tgchk_param(&par, ctx, target, info, &e, proto, inv); ret = xt_check_target(&par, size, proto, inv); if (ret < 0) - goto err; + return ret; /* The standard target cannot be used */ - if (target->target == NULL) { - ret = -EINVAL; - goto err; - } + if (!target->target) + return -EINVAL; + nft_xt = container_of(expr->ops, struct nft_xt, ops); + nft_xt->refcnt++; return 0; -err: - module_put(target->me); - return ret; } static void @@ -271,8 +279,8 @@ nft_target_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr) if (par.target->destroy != NULL) par.target->destroy(&par); - nft_xt_put(container_of(expr->ops, struct nft_xt, ops)); - module_put(target->me); + if (nft_xt_put(container_of(expr->ops, struct nft_xt, ops))) + module_put(target->me); } static int nft_target_dump(struct sk_buff *skb, const struct nft_expr *expr) @@ -411,6 +419,7 @@ nft_match_init(const struct nft_ctx *ctx, const struct nft_expr *expr, struct xt_match *match = expr->ops->data; struct xt_mtchk_param par; size_t size = XT_ALIGN(nla_len(tb[NFTA_MATCH_INFO])); + struct nft_xt *nft_xt; u16 proto = 0; bool inv = false; union nft_entry e = {}; @@ -421,19 +430,18 @@ nft_match_init(const struct nft_ctx *ctx, const struct nft_expr *expr, if (ctx->nla[NFTA_RULE_COMPAT]) { ret = nft_parse_compat(ctx->nla[NFTA_RULE_COMPAT], &proto, &inv); if (ret < 0) - goto err; + return ret; } nft_match_set_mtchk_param(&par, ctx, match, info, &e, proto, inv); ret = xt_check_match(&par, size, proto, inv); if (ret < 0) - goto err; + return ret; + nft_xt = container_of(expr->ops, struct nft_xt, ops); + nft_xt->refcnt++; return 0; -err: - module_put(match->me); - return ret; } static void @@ -450,8 +458,8 @@ nft_match_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr) if (par.match->destroy != NULL) par.match->destroy(&par); - nft_xt_put(container_of(expr->ops, struct nft_xt, ops)); - module_put(match->me); + if (nft_xt_put(container_of(expr->ops, struct nft_xt, ops))) + module_put(match->me); } static int nft_match_dump(struct sk_buff *skb, const struct nft_expr *expr) @@ -654,13 +662,8 @@ nft_match_select_ops(const struct nft_ctx *ctx, list_for_each_entry(nft_match, &nft_match_list, head) { struct xt_match *match = nft_match->ops.data; - if (nft_match_cmp(match, mt_name, rev, family)) { - if (!try_module_get(match->me)) - return ERR_PTR(-ENOENT); - - nft_match->refcnt++; + if (nft_match_cmp(match, mt_name, rev, family)) return &nft_match->ops; - } } match = xt_request_find_match(family, mt_name, rev); @@ -679,7 +682,7 @@ nft_match_select_ops(const struct nft_ctx *ctx, goto err; } - nft_match->refcnt = 1; + nft_match->refcnt = 0; nft_match->ops.type = &nft_match_type; nft_match->ops.size = NFT_EXPR_SIZE(XT_ALIGN(match->matchsize)); nft_match->ops.eval = nft_match_eval; @@ -739,13 +742,8 @@ nft_target_select_ops(const struct nft_ctx *ctx, list_for_each_entry(nft_target, &nft_target_list, head) { struct xt_target *target = nft_target->ops.data; - if (nft_target_cmp(target, tg_name, rev, family)) { - if (!try_module_get(target->me)) - return ERR_PTR(-ENOENT); - - nft_target->refcnt++; + if (nft_target_cmp(target, tg_name, rev, family)) return &nft_target->ops; - } } target = xt_request_find_target(family, tg_name, rev); @@ -764,7 +762,7 @@ nft_target_select_ops(const struct nft_ctx *ctx, goto err; } - nft_target->refcnt = 1; + nft_target->refcnt = 0; nft_target->ops.type = &nft_target_type; nft_target->ops.size = NFT_EXPR_SIZE(XT_ALIGN(target->targetsize)); nft_target->ops.init = nft_target_init; @@ -823,6 +821,32 @@ err_match: static void __exit nft_compat_module_exit(void) { + struct nft_xt *xt, *next; + + /* list should be empty here, it can be non-empty only in case there + * was an error that caused nft_xt expr to not be initialized fully + * and noone else requested the same expression later. + * + * In this case, the lists contain 0-refcount entries that still + * hold module reference. + */ + list_for_each_entry_safe(xt, next, &nft_target_list, head) { + struct xt_target *target = xt->ops.data; + + if (WARN_ON_ONCE(xt->refcnt)) + continue; + module_put(target->me); + kfree(xt); + } + + list_for_each_entry_safe(xt, next, &nft_match_list, head) { + struct xt_match *match = xt->ops.data; + + if (WARN_ON_ONCE(xt->refcnt)) + continue; + module_put(match->me); + kfree(xt); + } nfnetlink_subsys_unregister(&nfnl_compat_subsys); nft_unregister_expr(&nft_target_type); nft_unregister_expr(&nft_match_type); |