From 3d2f30a1df907e3ef4175121f0d21456630a72aa Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Thu, 18 Aug 2016 01:46:06 +0200 Subject: [PATCH] netfilter: nf_tables: add quota expression This patch adds the quota expression. This new stateful expression integrate easily into the dynset expression to build 'hashquota' flow tables. Arguably, we could use instead "counter bytes > 1000" instead, but this approach has several problems: 1) We only support for one single stateful expression in dynamic set definitions, and the expression above is a composite of two expressions: get counter + comparison. 2) We would need to restore the packed counter representation (that we used to have) based on seqlock to synchronize this, since per-cpu is not suitable for this. So instead of bloating the counter expression back with the seqlock representation and extending the existing set infrastructure to make it more complex for the composite described above, let's follow the more simple approach of adding a quota expression that we can plug into our existing infrastructure. Signed-off-by: Pablo Neira Ayuso --- include/uapi/linux/netfilter/nf_tables.h | 19 ++++ net/netfilter/Kconfig | 6 ++ net/netfilter/Makefile | 1 + net/netfilter/nft_quota.c | 121 +++++++++++++++++++++++ 4 files changed, 147 insertions(+) create mode 100644 net/netfilter/nft_quota.c diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h index 6ce0a6dd0889..784fbf15ab3d 100644 --- a/include/uapi/linux/netfilter/nf_tables.h +++ b/include/uapi/linux/netfilter/nf_tables.h @@ -900,6 +900,25 @@ enum nft_queue_attributes { #define NFT_QUEUE_FLAG_CPU_FANOUT 0x02 /* use current CPU (no hashing) */ #define NFT_QUEUE_FLAG_MASK 0x03 +enum nft_quota_flags { + NFT_QUOTA_F_INV = (1 << 0), +}; + +/** + * enum nft_quota_attributes - nf_tables quota expression netlink attributes + * + * @NFTA_QUOTA_BYTES: quota in bytes (NLA_U16) + * @NFTA_QUOTA_FLAGS: flags (NLA_U32) + */ +enum nft_quota_attributes { + NFTA_QUOTA_UNSPEC, + NFTA_QUOTA_BYTES, + NFTA_QUOTA_FLAGS, + NFTA_QUOTA_PAD, + __NFTA_QUOTA_MAX +}; +#define NFTA_QUOTA_MAX (__NFTA_QUOTA_MAX - 1) + /** * enum nft_reject_types - nf_tables reject expression reject types * diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig index 9cfaa00c79b2..29a8078deafa 100644 --- a/net/netfilter/Kconfig +++ b/net/netfilter/Kconfig @@ -542,6 +542,12 @@ config NFT_QUEUE This is required if you intend to use the userspace queueing infrastructure (also known as NFQUEUE) from nftables. +config NFT_QUOTA + tristate "Netfilter nf_tables quota module" + help + This option adds the "quota" expression that you can use to match + enforce bytes quotas. + config NFT_REJECT default m if NETFILTER_ADVANCED=n tristate "Netfilter nf_tables reject support" diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile index 1106ccde215c..0fc42df19b8c 100644 --- a/net/netfilter/Makefile +++ b/net/netfilter/Makefile @@ -84,6 +84,7 @@ obj-$(CONFIG_NFT_CT) += nft_ct.o obj-$(CONFIG_NFT_LIMIT) += nft_limit.o obj-$(CONFIG_NFT_NAT) += nft_nat.o obj-$(CONFIG_NFT_QUEUE) += nft_queue.o +obj-$(CONFIG_NFT_QUOTA) += nft_quota.o obj-$(CONFIG_NFT_REJECT) += nft_reject.o obj-$(CONFIG_NFT_REJECT_INET) += nft_reject_inet.o obj-$(CONFIG_NFT_SET_RBTREE) += nft_set_rbtree.o diff --git a/net/netfilter/nft_quota.c b/net/netfilter/nft_quota.c new file mode 100644 index 000000000000..6eafbf987ed9 --- /dev/null +++ b/net/netfilter/nft_quota.c @@ -0,0 +1,121 @@ +/* + * Copyright (c) 2016 Pablo Neira Ayuso + * + * 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 + +struct nft_quota { + u64 quota; + bool invert; + atomic64_t remain; +}; + +static inline long nft_quota(struct nft_quota *priv, + const struct nft_pktinfo *pkt) +{ + return atomic64_sub_return(pkt->skb->len, &priv->remain); +} + +static void nft_quota_eval(const struct nft_expr *expr, + struct nft_regs *regs, + const struct nft_pktinfo *pkt) +{ + struct nft_quota *priv = nft_expr_priv(expr); + + if (nft_quota(priv, pkt) < 0 && !priv->invert) + regs->verdict.code = NFT_BREAK; +} + +static const struct nla_policy nft_quota_policy[NFTA_QUOTA_MAX + 1] = { + [NFTA_QUOTA_BYTES] = { .type = NLA_U64 }, + [NFTA_QUOTA_FLAGS] = { .type = NLA_U32 }, +}; + +static int nft_quota_init(const struct nft_ctx *ctx, + const struct nft_expr *expr, + const struct nlattr * const tb[]) +{ + struct nft_quota *priv = nft_expr_priv(expr); + u32 flags = 0; + u64 quota; + + if (!tb[NFTA_QUOTA_BYTES]) + return -EINVAL; + + quota = be64_to_cpu(nla_get_be64(tb[NFTA_QUOTA_BYTES])); + if (quota > S64_MAX) + return -EOVERFLOW; + + if (tb[NFTA_QUOTA_FLAGS]) { + flags = ntohl(nla_get_be32(tb[NFTA_QUOTA_FLAGS])); + if (flags & ~NFT_QUOTA_F_INV) + return -EINVAL; + } + + priv->quota = quota; + priv->invert = (flags & NFT_QUOTA_F_INV) ? true : false; + atomic64_set(&priv->remain, quota); + + return 0; +} + +static int nft_quota_dump(struct sk_buff *skb, const struct nft_expr *expr) +{ + const struct nft_quota *priv = nft_expr_priv(expr); + u32 flags = priv->invert ? NFT_QUOTA_F_INV : 0; + + if (nla_put_be64(skb, NFTA_QUOTA_BYTES, cpu_to_be64(priv->quota), + NFTA_QUOTA_PAD) || + nla_put_be32(skb, NFTA_QUOTA_FLAGS, htonl(flags))) + goto nla_put_failure; + return 0; + +nla_put_failure: + return -1; +} + +static struct nft_expr_type nft_quota_type; +static const struct nft_expr_ops nft_quota_ops = { + .type = &nft_quota_type, + .size = NFT_EXPR_SIZE(sizeof(struct nft_quota)), + .eval = nft_quota_eval, + .init = nft_quota_init, + .dump = nft_quota_dump, +}; + +static struct nft_expr_type nft_quota_type __read_mostly = { + .name = "quota", + .ops = &nft_quota_ops, + .policy = nft_quota_policy, + .maxattr = NFTA_QUOTA_MAX, + .flags = NFT_EXPR_STATEFUL, + .owner = THIS_MODULE, +}; + +static int __init nft_quota_module_init(void) +{ + return nft_register_expr(&nft_quota_type); +} + +static void __exit nft_quota_module_exit(void) +{ + nft_unregister_expr(&nft_quota_type); +} + +module_init(nft_quota_module_init); +module_exit(nft_quota_module_exit); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Pablo Neira Ayuso "); +MODULE_ALIAS_NFT_EXPR("quota"); -- 2.20.1