1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
|
/*
* Copyright (c) 2016 Anders K. Pedersen <akp@cohaesio.com>
*
* 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/netlink.h>
#include <linux/netfilter.h>
#include <linux/netfilter/nf_tables.h>
#include <net/dst.h>
#include <net/ip6_route.h>
#include <net/route.h>
#include <net/netfilter/nf_tables.h>
#include <net/netfilter/nf_tables_core.h>
struct nft_rt {
enum nft_rt_keys key:8;
enum nft_registers dreg:8;
};
static u16 get_tcpmss(const struct nft_pktinfo *pkt, const struct dst_entry *skbdst)
{
u32 minlen = sizeof(struct ipv6hdr), mtu = dst_mtu(skbdst);
const struct sk_buff *skb = pkt->skb;
struct dst_entry *dst = NULL;
struct flowi fl;
memset(&fl, 0, sizeof(fl));
switch (nft_pf(pkt)) {
case NFPROTO_IPV4:
fl.u.ip4.daddr = ip_hdr(skb)->saddr;
minlen = sizeof(struct iphdr) + sizeof(struct tcphdr);
break;
case NFPROTO_IPV6:
fl.u.ip6.daddr = ipv6_hdr(skb)->saddr;
minlen = sizeof(struct ipv6hdr) + sizeof(struct tcphdr);
break;
}
nf_route(nft_net(pkt), &dst, &fl, false, nft_pf(pkt));
if (dst) {
mtu = min(mtu, dst_mtu(dst));
dst_release(dst);
}
if (mtu <= minlen || mtu > 0xffff)
return TCP_MSS_DEFAULT;
return mtu - minlen;
}
static void nft_rt_get_eval(const struct nft_expr *expr,
struct nft_regs *regs,
const struct nft_pktinfo *pkt)
{
const struct nft_rt *priv = nft_expr_priv(expr);
const struct sk_buff *skb = pkt->skb;
u32 *dest = ®s->data[priv->dreg];
const struct dst_entry *dst;
dst = skb_dst(skb);
if (!dst)
goto err;
switch (priv->key) {
#ifdef CONFIG_IP_ROUTE_CLASSID
case NFT_RT_CLASSID:
*dest = dst->tclassid;
break;
#endif
case NFT_RT_NEXTHOP4:
if (nft_pf(pkt) != NFPROTO_IPV4)
goto err;
*dest = (__force u32)rt_nexthop((const struct rtable *)dst,
ip_hdr(skb)->daddr);
break;
case NFT_RT_NEXTHOP6:
if (nft_pf(pkt) != NFPROTO_IPV6)
goto err;
memcpy(dest, rt6_nexthop((struct rt6_info *)dst,
&ipv6_hdr(skb)->daddr),
sizeof(struct in6_addr));
break;
case NFT_RT_TCPMSS:
nft_reg_store16(dest, get_tcpmss(pkt, dst));
break;
default:
WARN_ON(1);
goto err;
}
return;
err:
regs->verdict.code = NFT_BREAK;
}
static const struct nla_policy nft_rt_policy[NFTA_RT_MAX + 1] = {
[NFTA_RT_DREG] = { .type = NLA_U32 },
[NFTA_RT_KEY] = { .type = NLA_U32 },
};
static int nft_rt_get_init(const struct nft_ctx *ctx,
const struct nft_expr *expr,
const struct nlattr * const tb[])
{
struct nft_rt *priv = nft_expr_priv(expr);
unsigned int len;
if (tb[NFTA_RT_KEY] == NULL ||
tb[NFTA_RT_DREG] == NULL)
return -EINVAL;
priv->key = ntohl(nla_get_be32(tb[NFTA_RT_KEY]));
switch (priv->key) {
#ifdef CONFIG_IP_ROUTE_CLASSID
case NFT_RT_CLASSID:
#endif
case NFT_RT_NEXTHOP4:
len = sizeof(u32);
break;
case NFT_RT_NEXTHOP6:
len = sizeof(struct in6_addr);
break;
case NFT_RT_TCPMSS:
len = sizeof(u16);
break;
default:
return -EOPNOTSUPP;
}
priv->dreg = nft_parse_register(tb[NFTA_RT_DREG]);
return nft_validate_register_store(ctx, priv->dreg, NULL,
NFT_DATA_VALUE, len);
}
static int nft_rt_get_dump(struct sk_buff *skb,
const struct nft_expr *expr)
{
const struct nft_rt *priv = nft_expr_priv(expr);
if (nla_put_be32(skb, NFTA_RT_KEY, htonl(priv->key)))
goto nla_put_failure;
if (nft_dump_register(skb, NFTA_RT_DREG, priv->dreg))
goto nla_put_failure;
return 0;
nla_put_failure:
return -1;
}
static int nft_rt_validate(const struct nft_ctx *ctx, const struct nft_expr *expr,
const struct nft_data **data)
{
const struct nft_rt *priv = nft_expr_priv(expr);
unsigned int hooks;
switch (priv->key) {
case NFT_RT_NEXTHOP4:
case NFT_RT_NEXTHOP6:
case NFT_RT_CLASSID:
return 0;
case NFT_RT_TCPMSS:
hooks = (1 << NF_INET_FORWARD) |
(1 << NF_INET_LOCAL_OUT) |
(1 << NF_INET_POST_ROUTING);
break;
default:
return -EINVAL;
}
return nft_chain_validate_hooks(ctx->chain, hooks);
}
static const struct nft_expr_ops nft_rt_get_ops = {
.type = &nft_rt_type,
.size = NFT_EXPR_SIZE(sizeof(struct nft_rt)),
.eval = nft_rt_get_eval,
.init = nft_rt_get_init,
.dump = nft_rt_get_dump,
.validate = nft_rt_validate,
};
struct nft_expr_type nft_rt_type __read_mostly = {
.name = "rt",
.ops = &nft_rt_get_ops,
.policy = nft_rt_policy,
.maxattr = NFTA_RT_MAX,
.owner = THIS_MODULE,
};
|
