1// SPDX-License-Identifier: GPL-2.0-only
2#include <linux/kernel.h>
3#include <linux/init.h>
4#include <linux/module.h>
5#include <linux/netlink.h>
6#include <linux/netfilter.h>
7#include <linux/netfilter/nf_tables.h>
8#include <net/netfilter/nf_tables_core.h>
9#include <net/netfilter/nf_tables.h>
10
11struct nft_last {
12	unsigned long	jiffies;
13	unsigned int	set;
14};
15
16struct nft_last_priv {
17	struct nft_last	*last;
18};
19
20static const struct nla_policy nft_last_policy[NFTA_LAST_MAX + 1] = {
21	[NFTA_LAST_SET] = { .type = NLA_U32 },
22	[NFTA_LAST_MSECS] = { .type = NLA_U64 },
23};
24
25static int nft_last_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
26			 const struct nlattr * const tb[])
27{
28	struct nft_last_priv *priv = nft_expr_priv(expr);
29	struct nft_last *last;
30	u64 last_jiffies;
31	int err;
32
33	last = kzalloc(sizeof(*last), GFP_KERNEL_ACCOUNT);
34	if (!last)
35		return -ENOMEM;
36
37	if (tb[NFTA_LAST_SET])
38		last->set = ntohl(nla_get_be32(tb[NFTA_LAST_SET]));
39
40	if (last->set && tb[NFTA_LAST_MSECS]) {
41		err = nf_msecs_to_jiffies64(tb[NFTA_LAST_MSECS], &last_jiffies);
42		if (err < 0)
43			goto err;
44
45		last->jiffies = jiffies - (unsigned long)last_jiffies;
46	}
47	priv->last = last;
48
49	return 0;
50err:
51	kfree(last);
52
53	return err;
54}
55
56static void nft_last_eval(const struct nft_expr *expr,
57			  struct nft_regs *regs, const struct nft_pktinfo *pkt)
58{
59	struct nft_last_priv *priv = nft_expr_priv(expr);
60	struct nft_last *last = priv->last;
61
62	if (READ_ONCE(last->jiffies) != jiffies)
63		WRITE_ONCE(last->jiffies, jiffies);
64	if (READ_ONCE(last->set) == 0)
65		WRITE_ONCE(last->set, 1);
66}
67
68static int nft_last_dump(struct sk_buff *skb,
69			 const struct nft_expr *expr, bool reset)
70{
71	struct nft_last_priv *priv = nft_expr_priv(expr);
72	struct nft_last *last = priv->last;
73	unsigned long last_jiffies = READ_ONCE(last->jiffies);
74	u32 last_set = READ_ONCE(last->set);
75	__be64 msecs;
76
77	if (time_before(jiffies, last_jiffies)) {
78		WRITE_ONCE(last->set, 0);
79		last_set = 0;
80	}
81
82	if (last_set)
83		msecs = nf_jiffies64_to_msecs(jiffies - last_jiffies);
84	else
85		msecs = 0;
86
87	if (nla_put_be32(skb, NFTA_LAST_SET, htonl(last_set)) ||
88	    nla_put_be64(skb, NFTA_LAST_MSECS, msecs, NFTA_LAST_PAD))
89		goto nla_put_failure;
90
91	return 0;
92
93nla_put_failure:
94	return -1;
95}
96
97static void nft_last_destroy(const struct nft_ctx *ctx,
98			     const struct nft_expr *expr)
99{
100	struct nft_last_priv *priv = nft_expr_priv(expr);
101
102	kfree(priv->last);
103}
104
105static int nft_last_clone(struct nft_expr *dst, const struct nft_expr *src)
106{
107	struct nft_last_priv *priv_dst = nft_expr_priv(dst);
108	struct nft_last_priv *priv_src = nft_expr_priv(src);
109
110	priv_dst->last = kzalloc(sizeof(*priv_dst->last), GFP_ATOMIC);
111	if (!priv_dst->last)
112		return -ENOMEM;
113
114	priv_dst->last->set = priv_src->last->set;
115	priv_dst->last->jiffies = priv_src->last->jiffies;
116
117	return 0;
118}
119
120static const struct nft_expr_ops nft_last_ops = {
121	.type		= &nft_last_type,
122	.size		= NFT_EXPR_SIZE(sizeof(struct nft_last_priv)),
123	.eval		= nft_last_eval,
124	.init		= nft_last_init,
125	.destroy	= nft_last_destroy,
126	.clone		= nft_last_clone,
127	.dump		= nft_last_dump,
128	.reduce		= NFT_REDUCE_READONLY,
129};
130
131struct nft_expr_type nft_last_type __read_mostly = {
132	.name		= "last",
133	.ops		= &nft_last_ops,
134	.policy		= nft_last_policy,
135	.maxattr	= NFTA_LAST_MAX,
136	.flags		= NFT_EXPR_STATEFUL,
137	.owner		= THIS_MODULE,
138};
139