From patchwork Fri Nov 15 13:31:59 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Pablo Neira Ayuso X-Patchwork-Id: 13876247 X-Patchwork-Delegate: kuba@kernel.org Received: from mail.netfilter.org (mail.netfilter.org [217.70.188.207]) by smtp.subspace.kernel.org (Postfix) with ESMTP id BB3491CD214; Fri, 15 Nov 2024 13:32:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.70.188.207 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731677545; cv=none; b=aAQU2pcnsYyr1j1MuWUKclqmm6i9nQ4YM8ObozZoeDpF2F7eQgAQ4nvYZ6u1zGMYBb0gn0KbH2DTOnWxzBXgt/R6rU4MXiDE2bWqSb+qPHlyCaU8wWuQDMge6IMRVNM22uZQjpDtpiNd6yGlkfaTwgbipNCo3ScLPJRgUMggD5c= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731677545; c=relaxed/simple; bh=Sj45/yAP8FW0CXeUrL4Ak6V5Ne0/KjRwcAoPkRGn0rE=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=BYuTwQlA0Um0lPkUWB3Gv4iiqO7aCJI8xLN0eMxcYOLtCH9QHHMaturIXgUBTeZQjyev2gveU4l51dt5h7bxhhis34FKvm75rOeAlhkHcl9nEh6T6ER3q10CH+9tPtG5tJOxuQk9UMhJKsSb9MctGC7PjO6ne5cBJ1YJxVkFrbo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=netfilter.org; spf=pass smtp.mailfrom=netfilter.org; arc=none smtp.client-ip=217.70.188.207 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=netfilter.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=netfilter.org From: Pablo Neira Ayuso To: netfilter-devel@vger.kernel.org Cc: davem@davemloft.net, netdev@vger.kernel.org, kuba@kernel.org, pabeni@redhat.com, edumazet@google.com, fw@strlen.de Subject: [PATCH net-next 06/14] netfilter: nf_tables: switch trans_elem to real flex array Date: Fri, 15 Nov 2024 14:31:59 +0100 Message-Id: <20241115133207.8907-7-pablo@netfilter.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20241115133207.8907-1-pablo@netfilter.org> References: <20241115133207.8907-1-pablo@netfilter.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: kuba@kernel.org From: Florian Westphal When queueing a set element add or removal operation to the transaction log, check if the previous operation already asks for a the identical operation on the same set. If so, store the element reference in the preceding operation. This significantlty reduces memory consumption when many set add/delete operations appear in a single transaction. Example: 10k elements require 937kb of memory (10k allocations from kmalloc-96 slab). Assuming we can compact 4 elements in the same set, 468 kbytes are needed (64 bytes for base struct, nft_trans_elemn, 32 bytes for nft_trans_one_elem structure, so 2500 allocations from kmalloc-192 slab). For large batch updates we can compact up to 62 elements into one single nft_trans_elem structure (~65% mem reduction): (64 bytes for base struct, nft_trans_elem, 32 byte for nft_trans_one_elem struct). We can halve size of nft_trans_one_elem struct by moving timeout/expire/update_flags into a dynamically allocated structure, this allows to store 124 elements in a 2k slab nft_trans_elem struct. This is done in a followup patch. Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_tables_api.c | 90 +++++++++++++++++++++++++++++++++++ 1 file changed, 90 insertions(+) diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index 5b5178841553..679312d71bbe 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -26,6 +26,9 @@ #define NFT_MODULE_AUTOLOAD_LIMIT (MODULE_NAME_LEN - sizeof("nft-expr-255-")) #define NFT_SET_MAX_ANONLEN 16 +/* limit compaction to avoid huge kmalloc/krealloc sizes. */ +#define NFT_MAX_SET_NELEMS ((2048 - sizeof(struct nft_trans_elem)) / sizeof(struct nft_trans_one_elem)) + unsigned int nf_tables_net_id __read_mostly; static LIST_HEAD(nf_tables_expressions); @@ -391,6 +394,86 @@ static void nf_tables_unregister_hook(struct net *net, return __nf_tables_unregister_hook(net, table, chain, false); } +static bool nft_trans_collapse_set_elem_allowed(const struct nft_trans_elem *a, const struct nft_trans_elem *b) +{ + /* NB: the ->bound equality check is defensive, at this time we only merge + * a new nft_trans_elem transaction request with the transaction tail + * element, but a->bound != b->bound would imply a NEWRULE transaction + * is queued in-between. + * + * The set check is mandatory, the NFT_MAX_SET_NELEMS check prevents + * huge krealloc() requests. + */ + return a->set == b->set && a->bound == b->bound && a->nelems < NFT_MAX_SET_NELEMS; +} + +static bool nft_trans_collapse_set_elem(struct nftables_pernet *nft_net, + struct nft_trans_elem *tail, + struct nft_trans_elem *trans, + gfp_t gfp) +{ + unsigned int nelems, old_nelems = tail->nelems; + struct nft_trans_elem *new_trans; + + if (!nft_trans_collapse_set_elem_allowed(tail, trans)) + return false; + + /* "cannot happen", at this time userspace element add + * requests always allocate a new transaction element. + * + * This serves as a reminder to adjust the list_add_tail + * logic below in case this ever changes. + */ + if (WARN_ON_ONCE(trans->nelems != 1)) + return false; + + if (check_add_overflow(old_nelems, trans->nelems, &nelems)) + return false; + + /* krealloc might free tail which invalidates list pointers */ + list_del_init(&tail->nft_trans.list); + + new_trans = krealloc(tail, struct_size(tail, elems, nelems), gfp); + if (!new_trans) { + list_add_tail(&tail->nft_trans.list, &nft_net->commit_list); + return false; + } + + /* + * new_trans->nft_trans.list contains garbage, but + * list_add_tail() doesn't care. + */ + new_trans->nelems = nelems; + new_trans->elems[old_nelems] = trans->elems[0]; + list_add_tail(&new_trans->nft_trans.list, &nft_net->commit_list); + + return true; +} + +static bool nft_trans_try_collapse(struct nftables_pernet *nft_net, + struct nft_trans *trans, gfp_t gfp) +{ + struct nft_trans *tail; + + if (list_empty(&nft_net->commit_list)) + return false; + + tail = list_last_entry(&nft_net->commit_list, struct nft_trans, list); + + if (tail->msg_type != trans->msg_type) + return false; + + switch (trans->msg_type) { + case NFT_MSG_NEWSETELEM: + case NFT_MSG_DELSETELEM: + return nft_trans_collapse_set_elem(nft_net, + nft_trans_container_elem(tail), + nft_trans_container_elem(trans), gfp); + } + + return false; +} + static void nft_trans_commit_list_add_tail(struct net *net, struct nft_trans *trans) { struct nftables_pernet *nft_net = nft_pernet(net); @@ -424,11 +507,18 @@ static void nft_trans_commit_list_add_tail(struct net *net, struct nft_trans *tr static void nft_trans_commit_list_add_elem(struct net *net, struct nft_trans *trans, gfp_t gfp) { + struct nftables_pernet *nft_net = nft_pernet(net); + WARN_ON_ONCE(trans->msg_type != NFT_MSG_NEWSETELEM && trans->msg_type != NFT_MSG_DELSETELEM); might_alloc(gfp); + if (nft_trans_try_collapse(nft_net, trans, gfp)) { + kfree(trans); + return; + } + nft_trans_commit_list_add_tail(net, trans); }