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// SPDX-License-Identifier: GPL-2.0-only
#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 <net/netfilter/nf_tables_core.h>
#include <net/netfilter/nf_tables.h>
struct nft_last {
unsigned long jiffies;
unsigned int set;
};
struct nft_last_priv {
struct nft_last *last;
};
static const struct nla_policy nft_last_policy[NFTA_LAST_MAX + 1] = {
[NFTA_LAST_SET] = { .type = NLA_U32 },
[NFTA_LAST_MSECS] = { .type = NLA_U64 },
};
static int nft_last_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
const struct nlattr * const tb[])
{
struct nft_last_priv *priv = nft_expr_priv(expr);
struct nft_last *last;
u64 last_jiffies;
int err;
last = kzalloc(sizeof(*last), GFP_KERNEL);
if (!last)
return -ENOMEM;
if (tb[NFTA_LAST_SET])
last->set = ntohl(nla_get_be32(tb[NFTA_LAST_SET]));
if (last->set && tb[NFTA_LAST_MSECS]) {
err = nf_msecs_to_jiffies64(tb[NFTA_LAST_MSECS], &last_jiffies);
if (err < 0)
goto err;
last->jiffies = jiffies - (unsigned long)last_jiffies;
}
priv->last = last;
return 0;
err:
kfree(last);
return err;
}
static void nft_last_eval(const struct nft_expr *expr,
struct nft_regs *regs, const struct nft_pktinfo *pkt)
{
struct nft_last_priv *priv = nft_expr_priv(expr);
struct nft_last *last = priv->last;
if (READ_ONCE(last->jiffies) != jiffies)
WRITE_ONCE(last->jiffies, jiffies);
if (READ_ONCE(last->set) == 0)
WRITE_ONCE(last->set, 1);
}
static int nft_last_dump(struct sk_buff *skb, const struct nft_expr *expr)
{
struct nft_last_priv *priv = nft_expr_priv(expr);
struct nft_last *last = priv->last;
unsigned long last_jiffies = READ_ONCE(last->jiffies);
u32 last_set = READ_ONCE(last->set);
__be64 msecs;
if (time_before(jiffies, last_jiffies)) {
WRITE_ONCE(last->set, 0);
last_set = 0;
}
if (last_set)
msecs = nf_jiffies64_to_msecs(jiffies - last_jiffies);
else
msecs = 0;
if (nla_put_be32(skb, NFTA_LAST_SET, htonl(last_set)) ||
nla_put_be64(skb, NFTA_LAST_MSECS, msecs, NFTA_LAST_PAD))
goto nla_put_failure;
return 0;
nla_put_failure:
return -1;
}
static void nft_last_destroy(const struct nft_ctx *ctx,
const struct nft_expr *expr)
{
struct nft_last_priv *priv = nft_expr_priv(expr);
kfree(priv->last);
}
static int nft_last_clone(struct nft_expr *dst, const struct nft_expr *src)
{
struct nft_last_priv *priv_dst = nft_expr_priv(dst);
priv_dst->last = kzalloc(sizeof(*priv_dst->last), GFP_ATOMIC);
if (!priv_dst->last)
return -ENOMEM;
return 0;
}
static const struct nft_expr_ops nft_last_ops = {
.type = &nft_last_type,
.size = NFT_EXPR_SIZE(sizeof(struct nft_last_priv)),
.eval = nft_last_eval,
.init = nft_last_init,
.destroy = nft_last_destroy,
.clone = nft_last_clone,
.dump = nft_last_dump,
.reduce = NFT_REDUCE_READONLY,
};
struct nft_expr_type nft_last_type __read_mostly = {
.name = "last",
.ops = &nft_last_ops,
.policy = nft_last_policy,
.maxattr = NFTA_LAST_MAX,
.flags = NFT_EXPR_STATEFUL,
.owner = THIS_MODULE,
};
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