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[thirdparty/linux.git] / net / netfilter / nft_osf.c
1 #include <net/ip.h>
2 #include <net/tcp.h>
3
4 #include <net/netfilter/nf_tables.h>
5 #include <linux/netfilter/nfnetlink_osf.h>
6
7 struct nft_osf {
8 enum nft_registers dreg:8;
9 u8 ttl;
10 };
11
12 static const struct nla_policy nft_osf_policy[NFTA_OSF_MAX + 1] = {
13 [NFTA_OSF_DREG] = { .type = NLA_U32 },
14 [NFTA_OSF_TTL] = { .type = NLA_U8 },
15 };
16
17 static void nft_osf_eval(const struct nft_expr *expr, struct nft_regs *regs,
18 const struct nft_pktinfo *pkt)
19 {
20 struct nft_osf *priv = nft_expr_priv(expr);
21 u32 *dest = &regs->data[priv->dreg];
22 struct sk_buff *skb = pkt->skb;
23 const struct tcphdr *tcp;
24 struct tcphdr _tcph;
25 const char *os_name;
26
27 tcp = skb_header_pointer(skb, ip_hdrlen(skb),
28 sizeof(struct tcphdr), &_tcph);
29 if (!tcp) {
30 regs->verdict.code = NFT_BREAK;
31 return;
32 }
33 if (!tcp->syn) {
34 regs->verdict.code = NFT_BREAK;
35 return;
36 }
37
38 os_name = nf_osf_find(skb, nf_osf_fingers, priv->ttl);
39 if (!os_name)
40 strncpy((char *)dest, "unknown", NFT_OSF_MAXGENRELEN);
41 else
42 strncpy((char *)dest, os_name, NFT_OSF_MAXGENRELEN);
43 }
44
45 static int nft_osf_init(const struct nft_ctx *ctx,
46 const struct nft_expr *expr,
47 const struct nlattr * const tb[])
48 {
49 struct nft_osf *priv = nft_expr_priv(expr);
50 int err;
51 u8 ttl;
52
53 if (tb[NFTA_OSF_TTL]) {
54 ttl = nla_get_u8(tb[NFTA_OSF_TTL]);
55 if (ttl > 2)
56 return -EINVAL;
57 priv->ttl = ttl;
58 }
59
60 priv->dreg = nft_parse_register(tb[NFTA_OSF_DREG]);
61 err = nft_validate_register_store(ctx, priv->dreg, NULL,
62 NFT_DATA_VALUE, NFT_OSF_MAXGENRELEN);
63 if (err < 0)
64 return err;
65
66 return 0;
67 }
68
69 static int nft_osf_dump(struct sk_buff *skb, const struct nft_expr *expr)
70 {
71 const struct nft_osf *priv = nft_expr_priv(expr);
72
73 if (nla_put_u8(skb, NFTA_OSF_TTL, priv->ttl))
74 goto nla_put_failure;
75
76 if (nft_dump_register(skb, NFTA_OSF_DREG, priv->dreg))
77 goto nla_put_failure;
78
79 return 0;
80
81 nla_put_failure:
82 return -1;
83 }
84
85 static int nft_osf_validate(const struct nft_ctx *ctx,
86 const struct nft_expr *expr,
87 const struct nft_data **data)
88 {
89 return nft_chain_validate_hooks(ctx->chain, (1 << NF_INET_LOCAL_IN) |
90 (1 << NF_INET_PRE_ROUTING) |
91 (1 << NF_INET_FORWARD));
92 }
93
94 static struct nft_expr_type nft_osf_type;
95 static const struct nft_expr_ops nft_osf_op = {
96 .eval = nft_osf_eval,
97 .size = NFT_EXPR_SIZE(sizeof(struct nft_osf)),
98 .init = nft_osf_init,
99 .dump = nft_osf_dump,
100 .type = &nft_osf_type,
101 .validate = nft_osf_validate,
102 };
103
104 static struct nft_expr_type nft_osf_type __read_mostly = {
105 .ops = &nft_osf_op,
106 .name = "osf",
107 .owner = THIS_MODULE,
108 .policy = nft_osf_policy,
109 .maxattr = NFTA_OSF_MAX,
110 };
111
112 static int __init nft_osf_module_init(void)
113 {
114 return nft_register_expr(&nft_osf_type);
115 }
116
117 static void __exit nft_osf_module_exit(void)
118 {
119 return nft_unregister_expr(&nft_osf_type);
120 }
121
122 module_init(nft_osf_module_init);
123 module_exit(nft_osf_module_exit);
124
125 MODULE_LICENSE("GPL");
126 MODULE_AUTHOR("Fernando Fernandez <ffmancera@riseup.net>");
127 MODULE_ALIAS_NFT_EXPR("osf");