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
|
// SPDX-License-Identifier: GPL-2.0
#include <linux/skbuff.h>
#include "protocol.h"
/* Syncookies do not work for JOIN requests.
*
* Unlike MP_CAPABLE, where the ACK cookie contains the needed MPTCP
* options to reconstruct the initial syn state, MP_JOIN does not contain
* the token to obtain the mptcp socket nor the server-generated nonce
* that was used in the cookie SYN/ACK response.
*
* Keep a small best effort state table to store the syn/synack data,
* indexed by skb hash.
*
* A MP_JOIN SYN packet handled by syn cookies is only stored if the 32bit
* token matches a known mptcp connection that can still accept more subflows.
*
* There is no timeout handling -- state is only re-constructed
* when the TCP ACK passed the cookie validation check.
*/
struct join_entry {
u32 token;
u32 remote_nonce;
u32 local_nonce;
u8 join_id;
u8 local_id;
u8 backup;
u8 valid;
};
#define COOKIE_JOIN_SLOTS 1024
static struct join_entry join_entries[COOKIE_JOIN_SLOTS] __cacheline_aligned_in_smp;
static spinlock_t join_entry_locks[COOKIE_JOIN_SLOTS] __cacheline_aligned_in_smp;
static u32 mptcp_join_entry_hash(struct sk_buff *skb, struct net *net)
{
u32 i = skb_get_hash(skb) ^ net_hash_mix(net);
return i % ARRAY_SIZE(join_entries);
}
static void mptcp_join_store_state(struct join_entry *entry,
const struct mptcp_subflow_request_sock *subflow_req)
{
entry->token = subflow_req->token;
entry->remote_nonce = subflow_req->remote_nonce;
entry->local_nonce = subflow_req->local_nonce;
entry->backup = subflow_req->backup;
entry->join_id = subflow_req->remote_id;
entry->local_id = subflow_req->local_id;
entry->valid = 1;
}
void subflow_init_req_cookie_join_save(const struct mptcp_subflow_request_sock *subflow_req,
struct sk_buff *skb)
{
struct net *net = read_pnet(&subflow_req->sk.req.ireq_net);
u32 i = mptcp_join_entry_hash(skb, net);
/* No use in waiting if other cpu is already using this slot --
* would overwrite the data that got stored.
*/
spin_lock_bh(&join_entry_locks[i]);
mptcp_join_store_state(&join_entries[i], subflow_req);
spin_unlock_bh(&join_entry_locks[i]);
}
/* Called for a cookie-ack with MP_JOIN option present.
* Look up the saved state based on skb hash & check token matches msk
* in same netns.
*
* Caller will check msk can still accept another subflow. The hmac
* present in the cookie ACK mptcp option space will be checked later.
*/
bool mptcp_token_join_cookie_init_state(struct mptcp_subflow_request_sock *subflow_req,
struct sk_buff *skb)
{
struct net *net = read_pnet(&subflow_req->sk.req.ireq_net);
u32 i = mptcp_join_entry_hash(skb, net);
struct mptcp_sock *msk;
struct join_entry *e;
e = &join_entries[i];
spin_lock_bh(&join_entry_locks[i]);
if (e->valid == 0) {
spin_unlock_bh(&join_entry_locks[i]);
return false;
}
e->valid = 0;
msk = mptcp_token_get_sock(e->token);
if (!msk) {
spin_unlock_bh(&join_entry_locks[i]);
return false;
}
/* If this fails, the token got re-used in the mean time by another
* mptcp socket in a different netns, i.e. entry is outdated.
*/
if (!net_eq(sock_net((struct sock *)msk), net))
goto err_put;
subflow_req->remote_nonce = e->remote_nonce;
subflow_req->local_nonce = e->local_nonce;
subflow_req->backup = e->backup;
subflow_req->remote_id = e->join_id;
subflow_req->token = e->token;
subflow_req->msk = msk;
spin_unlock_bh(&join_entry_locks[i]);
return true;
err_put:
spin_unlock_bh(&join_entry_locks[i]);
sock_put((struct sock *)msk);
return false;
}
void __init mptcp_join_cookie_init(void)
{
int i;
for (i = 0; i < COOKIE_JOIN_SLOTS; i++)
spin_lock_init(&join_entry_locks[i]);
}
|
