On Tue, Jul 26, 2016 at 04:22:10PM +0200, Laura Garcia Liebana wrote:
> 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).
Please, break lines at 80 characters for patch descriptions.
More comments below.
> Signed-off-by: Laura Garcia Liebana <nevola@xxxxxxxxx>
> ---
> 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;
You don't need this data variable, see below why.
> + u32 every;
> + struct nft_nth_priv *master __attribute__((aligned(8)));
You can remove this master pointer, this was only required by xtables.
Declare atomic_t counter here and initialize it from init().
> +};
> +
> +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);
You don't need this header file. Make nft_nth_init() and other
function static, see below.
> 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)
Rename NTH_DATA to NTH_EVERY.
> + */
> +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 <nevola@xxxxxxxxx>
> + *
> + * 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 <linux/kernel.h>
> +#include <linux/init.h>
> +#include <linux/module.h>
> +#include <linux/netlink.h>
> +#include <linux/netfilter.h>
> +#include <linux/netfilter/nf_tables.h>
> +#include <linux/in.h>
> +#include <linux/ip.h>
> +#include <linux/ipv6.h>
> +#include <linux/smp.h>
> +#include <linux/static_key.h>
> +#include <net/netfilter/nf_tables.h>
> +#include <net/netfilter/nf_tables_core.h>
> +#include <net/netfilter/nft_nth.h>
> +
> +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[])
This should be:
static int nft_nth_init(const struct nft_ctx *ctx,
const struct nft_expr *expr,
const struct nlattr * const tb[])
Same thing for every function.
> +{
> + 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;
You can simplify this above to something like:
priv->every = ntohl(nla_get_be32(tb[NFTA_NTH_EVERY]));
> +
> + 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);
No need to export these symbols.
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