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
11 struct nft_last {
12 unsigned long jiffies;
13 unsigned int set;
14 };
15
16 struct nft_last_priv {
17 struct nft_last *last;
18 };
19
20 static 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
nft_last_init(const struct nft_ctx * ctx,const struct nft_expr * expr,const struct nlattr * const tb[])25 static 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;
50 err:
51 kfree(last);
52
53 return err;
54 }
55
nft_last_eval(const struct nft_expr * expr,struct nft_regs * regs,const struct nft_pktinfo * pkt)56 static 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
nft_last_dump(struct sk_buff * skb,const struct nft_expr * expr,bool reset)68 static 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
93 nla_put_failure:
94 return -1;
95 }
96
nft_last_destroy(const struct nft_ctx * ctx,const struct nft_expr * expr)97 static 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
nft_last_clone(struct nft_expr * dst,const struct nft_expr * src,gfp_t gfp)105 static int nft_last_clone(struct nft_expr *dst, const struct nft_expr *src, gfp_t gfp)
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);
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
120 static 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
131 struct 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