From mboxrd@z Thu Jan 1 00:00:00 1970 From: Laura Garcia Liebana Subject: [PATCH] netfilter: nft_nth: match every n packets Date: Tue, 26 Jul 2016 16:22:10 +0200 Message-ID: <20160726142207.GA18550@sonyv> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii To: netfilter-devel@vger.kernel.org Return-path: Received: from mail-wm0-f68.google.com ([74.125.82.68]:34198 "EHLO mail-wm0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753878AbcGZOWQ (ORCPT ); Tue, 26 Jul 2016 10:22:16 -0400 Received: by mail-wm0-f68.google.com with SMTP id q128so1933771wma.1 for ; Tue, 26 Jul 2016 07:22:15 -0700 (PDT) Received: from sonyv (cli-5b7e49a2.wholesale.adamo.es. [91.126.73.162]) by smtp.gmail.com with ESMTPSA id wc3sm1197137wjc.47.2016.07.26.07.22.12 for (version=TLS1_2 cipher=AES128-SHA bits=128/128); Tue, 26 Jul 2016 07:22:13 -0700 (PDT) Content-Disposition: inline Sender: netfilter-devel-owner@vger.kernel.org List-ID: Add support for the nth expression in netfilter. A nft_nth structure is created with dreg (to store the result into a given register), data (a nft_data structure to store the input value, it must be > 0), every (to store the data) and counter (to store atomically the current value). Signed-off-by: Laura Garcia Liebana --- include/net/netfilter/nft_nth.h | 31 +++++++ include/uapi/linux/netfilter/nf_tables.h | 15 ++++ net/netfilter/Kconfig | 6 ++ net/netfilter/Makefile | 1 + net/netfilter/nft_nth.c | 145 +++++++++++++++++++++++++++++++ 5 files changed, 198 insertions(+) create mode 100644 include/net/netfilter/nft_nth.h create mode 100644 net/netfilter/nft_nth.c diff --git a/include/net/netfilter/nft_nth.h b/include/net/netfilter/nft_nth.h new file mode 100644 index 0000000..0d8788d --- /dev/null +++ b/include/net/netfilter/nft_nth.h @@ -0,0 +1,31 @@ +#ifndef _NFT_NTH_H_ +#define _NFT_NTH_H_ + +struct nft_nth { + enum nft_registers dreg:8; + struct nft_data data; + u32 every; + struct nft_nth_priv *master __attribute__((aligned(8))); +}; + +struct nft_nth_priv { + atomic_t counter; +} ____cacheline_aligned_in_smp; + +extern const struct nla_policy nft_nth_policy[]; + +int nft_nth_init(const struct nft_ctx *ctx, + const struct nft_expr *expr, + const struct nlattr * const tb[]); + +int nft_nth_dump(struct sk_buff *skb, + const struct nft_expr *expr); + +void nft_nth_eval(const struct nft_expr *expr, + struct nft_regs *regs, + const struct nft_pktinfo *pkt); + +void nft_nth_destroy(const struct nft_ctx *ctx, + const struct nft_expr *expr); + +#endif diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h index 6a4dbe0..5ba075a 100644 --- a/include/uapi/linux/netfilter/nf_tables.h +++ b/include/uapi/linux/netfilter/nf_tables.h @@ -1076,4 +1076,19 @@ enum nft_trace_types { __NFT_TRACETYPE_MAX }; #define NFT_TRACETYPE_MAX (__NFT_TRACETYPE_MAX - 1) + +/** + * enum nft_nth_attributes - nf_tables nth expression netlink attributes + * @NFTA_NTH_UNSPEC: unspecified attribute + * @NFTA_NTH_DREG: destination register (NLA_U32) + * @NFTA_NTH_DATA: source data (NLA_NESTED) + */ +enum nft_nth_attributes { + NFTA_NTH_UNSPEC, + NFTA_NTH_DREG, + NFTA_NTH_DATA, + __NFTA_NTH_MAX +}; +#define NFTA_NTH_MAX (__NFTA_NTH_MAX - 1) + #endif /* _LINUX_NF_TABLES_H */ diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig index 95e757c..6f00d01 100644 --- a/net/netfilter/Kconfig +++ b/net/netfilter/Kconfig @@ -474,6 +474,12 @@ config NFT_META This option adds the "meta" expression that you can use to match and to set packet metainformation such as the packet mark. +config NFT_NTH + tristate "Netfilter nf_tables nth module" + help + This option adds the "nth" expression that you can use to match a + packet every a specific given value. + config NFT_CT depends on NF_CONNTRACK tristate "Netfilter nf_tables conntrack module" diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile index 6913454..2378f00 100644 --- a/net/netfilter/Makefile +++ b/net/netfilter/Makefile @@ -80,6 +80,7 @@ obj-$(CONFIG_NF_TABLES_NETDEV) += nf_tables_netdev.o obj-$(CONFIG_NFT_COMPAT) += nft_compat.o obj-$(CONFIG_NFT_EXTHDR) += nft_exthdr.o obj-$(CONFIG_NFT_META) += nft_meta.o +obj-$(CONFIG_NFT_NTH) += nft_nth.o obj-$(CONFIG_NFT_CT) += nft_ct.o obj-$(CONFIG_NFT_LIMIT) += nft_limit.o obj-$(CONFIG_NFT_NAT) += nft_nat.o diff --git a/net/netfilter/nft_nth.c b/net/netfilter/nft_nth.c new file mode 100644 index 0000000..d0a5387 --- /dev/null +++ b/net/netfilter/nft_nth.c @@ -0,0 +1,145 @@ +/* + * Copyright (c) 2016 Laura Garcia + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +void nft_nth_eval(const struct nft_expr *expr, + struct nft_regs *regs, + const struct nft_pktinfo *pkt) +{ + struct nft_nth *nth = nft_expr_priv(expr); + u32 nval, oval; + + do { + oval = atomic_read(&nth->master->counter); + nval = (oval+1 < nth->every) ? oval+1 : 0; + } while (atomic_cmpxchg(&nth->master->counter, oval, nval) != oval); + + memcpy(®s->data[nth->dreg], &nth->master->counter, sizeof(u32)); +} +EXPORT_SYMBOL_GPL(nft_nth_eval); + +const struct nla_policy nft_nth_policy[NFTA_NTH_MAX + 1] = { + [NFTA_NTH_DREG] = { .type = NLA_U32 }, + [NFTA_NTH_DATA] = { .type = NLA_NESTED }, +}; + +int nft_nth_init(const struct nft_ctx *ctx, + const struct nft_expr *expr, + const struct nlattr * const tb[]) +{ + struct nft_nth *nth = nft_expr_priv(expr); + struct nft_data_desc desc; + int err = 0; + + err = nft_data_init(NULL, &nth->data, + sizeof(nth->data), &desc, + tb[NFTA_NTH_DATA]); + if (err < 0) + goto err; + + memcpy(&nth->every, &nth->data, sizeof(u32)); + if (nth->every == 0) + return -EINVAL; + + nth->dreg = nft_parse_register(tb[NFTA_NTH_DREG]); + + nth->master = kzalloc(sizeof(*nth->master), GFP_KERNEL); + if (!nth->master) + return -ENOMEM; + atomic_set(&nth->master->counter, 0); + +err: + return err; +} +EXPORT_SYMBOL_GPL(nft_nth_init); + +int nft_nth_dump(struct sk_buff *skb, + const struct nft_expr *expr) +{ + const struct nft_nth *nth = nft_expr_priv(expr); + + if (nft_dump_register(skb, NFTA_NTH_DREG, nth->dreg)) + goto nla_put_failure; + if (nft_data_dump(skb, NFTA_NTH_DATA, &nth->data, + NFT_DATA_VALUE, sizeof(nth->data)) < 0) + goto nla_put_failure; + + return 0; + +nla_put_failure: + return -1; +} +EXPORT_SYMBOL_GPL(nft_nth_dump); + +void nft_nth_destroy(const struct nft_ctx *ctx, + const struct nft_expr *expr) +{ + struct nft_nth *nth = nft_expr_priv(expr); + + kfree(nth->master); +} +EXPORT_SYMBOL_GPL(nft_nth_destroy); + +static struct nft_expr_type nft_nth_type; +static const struct nft_expr_ops nft_nth_ops = { + .type = &nft_nth_type, + .size = NFT_EXPR_SIZE(sizeof(struct nft_nth)), + .eval = nft_nth_eval, + .init = nft_nth_init, + .destroy = nft_nth_destroy, + .dump = nft_nth_dump, +}; + +static const struct nft_expr_ops * +nft_nth_select_ops(const struct nft_ctx *ctx, + const struct nlattr * const tb[]) +{ + if (!tb[NFTA_NTH_DREG] || + !tb[NFTA_NTH_DATA]) + return ERR_PTR(-EINVAL); + + return &nft_nth_ops; +} + +static struct nft_expr_type nft_nth_type __read_mostly = { + .name = "nth", + .select_ops = &nft_nth_select_ops, + .policy = nft_nth_policy, + .maxattr = NFTA_NTH_MAX, + .owner = THIS_MODULE, +}; + +static int __init nft_nth_module_init(void) +{ + return nft_register_expr(&nft_nth_type); +} + +static void __exit nft_nth_module_exit(void) +{ + nft_unregister_expr(&nft_nth_type); +} + +module_init(nft_nth_module_init); +module_exit(nft_nth_module_exit); + +MODULE_LICENSE("GPL"); -- 2.8.1