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
|
// SPDX-License-Identifier: GPL-2.0-only
/* Support ct functions for openvswitch and used by OVS and TC conntrack. */
#include <net/netfilter/nf_conntrack_helper.h>
#include <net/netfilter/nf_conntrack_seqadj.h>
#include <net/netfilter/ipv6/nf_defrag_ipv6.h>
#include <net/ipv6_frag.h>
#include <net/ip.h>
#include <linux/netfilter_ipv6.h>
/* 'skb' should already be pulled to nh_ofs. */
int nf_ct_helper(struct sk_buff *skb, struct nf_conn *ct,
enum ip_conntrack_info ctinfo, u16 proto)
{
const struct nf_conntrack_helper *helper;
const struct nf_conn_help *help;
unsigned int protoff;
int err;
if (ctinfo == IP_CT_RELATED_REPLY)
return NF_ACCEPT;
help = nfct_help(ct);
if (!help)
return NF_ACCEPT;
helper = rcu_dereference(help->helper);
if (!helper)
return NF_ACCEPT;
if (helper->tuple.src.l3num != NFPROTO_UNSPEC &&
helper->tuple.src.l3num != proto)
return NF_ACCEPT;
switch (proto) {
case NFPROTO_IPV4:
protoff = ip_hdrlen(skb);
proto = ip_hdr(skb)->protocol;
break;
case NFPROTO_IPV6: {
u8 nexthdr = ipv6_hdr(skb)->nexthdr;
__be16 frag_off;
int ofs;
ofs = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr,
&frag_off);
if (ofs < 0 || (frag_off & htons(~0x7)) != 0) {
pr_debug("proto header not found\n");
return NF_ACCEPT;
}
protoff = ofs;
proto = nexthdr;
break;
}
default:
WARN_ONCE(1, "helper invoked on non-IP family!");
return NF_DROP;
}
if (helper->tuple.dst.protonum != proto)
return NF_ACCEPT;
err = helper->help(skb, protoff, ct, ctinfo);
if (err != NF_ACCEPT)
return err;
/* Adjust seqs after helper. This is needed due to some helpers (e.g.,
* FTP with NAT) adusting the TCP payload size when mangling IP
* addresses and/or port numbers in the text-based control connection.
*/
if (test_bit(IPS_SEQ_ADJUST_BIT, &ct->status) &&
!nf_ct_seq_adjust(skb, ct, ctinfo, protoff))
return NF_DROP;
return NF_ACCEPT;
}
EXPORT_SYMBOL_GPL(nf_ct_helper);
int nf_ct_add_helper(struct nf_conn *ct, const char *name, u8 family,
u8 proto, bool nat, struct nf_conntrack_helper **hp)
{
struct nf_conntrack_helper *helper;
struct nf_conn_help *help;
int ret = 0;
helper = nf_conntrack_helper_try_module_get(name, family, proto);
if (!helper)
return -EINVAL;
help = nf_ct_helper_ext_add(ct, GFP_KERNEL);
if (!help) {
nf_conntrack_helper_put(helper);
return -ENOMEM;
}
#if IS_ENABLED(CONFIG_NF_NAT)
if (nat) {
ret = nf_nat_helper_try_module_get(name, family, proto);
if (ret) {
nf_conntrack_helper_put(helper);
return ret;
}
}
#endif
rcu_assign_pointer(help->helper, helper);
*hp = helper;
return ret;
}
EXPORT_SYMBOL_GPL(nf_ct_add_helper);
/* Trim the skb to the length specified by the IP/IPv6 header,
* removing any trailing lower-layer padding. This prepares the skb
* for higher-layer processing that assumes skb->len excludes padding
* (such as nf_ip_checksum). The caller needs to pull the skb to the
* network header, and ensure ip_hdr/ipv6_hdr points to valid data.
*/
int nf_ct_skb_network_trim(struct sk_buff *skb, int family)
{
unsigned int len;
switch (family) {
case NFPROTO_IPV4:
len = skb_ip_totlen(skb);
break;
case NFPROTO_IPV6:
len = ntohs(ipv6_hdr(skb)->payload_len);
if (ipv6_hdr(skb)->nexthdr == NEXTHDR_HOP) {
int err = nf_ip6_check_hbh_len(skb, &len);
if (err)
return err;
}
len += sizeof(struct ipv6hdr);
break;
default:
len = skb->len;
}
return pskb_trim_rcsum(skb, len);
}
EXPORT_SYMBOL_GPL(nf_ct_skb_network_trim);
/* Returns 0 on success, -EINPROGRESS if 'skb' is stolen, or other nonzero
* value if 'skb' is freed.
*/
int nf_ct_handle_fragments(struct net *net, struct sk_buff *skb,
u16 zone, u8 family, u8 *proto, u16 *mru)
{
int err;
if (family == NFPROTO_IPV4) {
enum ip_defrag_users user = IP_DEFRAG_CONNTRACK_IN + zone;
memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
local_bh_disable();
err = ip_defrag(net, skb, user);
local_bh_enable();
if (err)
return err;
*mru = IPCB(skb)->frag_max_size;
#if IS_ENABLED(CONFIG_NF_DEFRAG_IPV6)
} else if (family == NFPROTO_IPV6) {
enum ip6_defrag_users user = IP6_DEFRAG_CONNTRACK_IN + zone;
memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm));
err = nf_ct_frag6_gather(net, skb, user);
if (err) {
if (err != -EINPROGRESS)
kfree_skb(skb);
return err;
}
*proto = ipv6_hdr(skb)->nexthdr;
*mru = IP6CB(skb)->frag_max_size;
#endif
} else {
kfree_skb(skb);
return -EPFNOSUPPORT;
}
skb_clear_hash(skb);
skb->ignore_df = 1;
return 0;
}
EXPORT_SYMBOL_GPL(nf_ct_handle_fragments);
|
