Commit | Line | Data |
---|---|---|
10467163 | 1 | #include <linux/err.h> |
2100c8d2 YC |
2 | #include <linux/init.h> |
3 | #include <linux/kernel.h> | |
10467163 JC |
4 | #include <linux/list.h> |
5 | #include <linux/tcp.h> | |
6 | #include <linux/rcupdate.h> | |
7 | #include <linux/rculist.h> | |
8 | #include <net/inetpeer.h> | |
9 | #include <net/tcp.h> | |
2100c8d2 | 10 | |
0d41cca4 | 11 | int sysctl_tcp_fastopen __read_mostly = TFO_CLIENT_ENABLE; |
10467163 JC |
12 | |
13 | struct tcp_fastopen_context __rcu *tcp_fastopen_ctx; | |
14 | ||
15 | static DEFINE_SPINLOCK(tcp_fastopen_ctx_lock); | |
16 | ||
222e83d2 HFS |
17 | void tcp_fastopen_init_key_once(bool publish) |
18 | { | |
19 | static u8 key[TCP_FASTOPEN_KEY_LENGTH]; | |
20 | ||
21 | /* tcp_fastopen_reset_cipher publishes the new context | |
22 | * atomically, so we allow this race happening here. | |
23 | * | |
24 | * All call sites of tcp_fastopen_cookie_gen also check | |
25 | * for a valid cookie, so this is an acceptable risk. | |
26 | */ | |
27 | if (net_get_random_once(key, sizeof(key)) && publish) | |
28 | tcp_fastopen_reset_cipher(key, sizeof(key)); | |
29 | } | |
30 | ||
10467163 JC |
31 | static void tcp_fastopen_ctx_free(struct rcu_head *head) |
32 | { | |
33 | struct tcp_fastopen_context *ctx = | |
34 | container_of(head, struct tcp_fastopen_context, rcu); | |
35 | crypto_free_cipher(ctx->tfm); | |
36 | kfree(ctx); | |
37 | } | |
38 | ||
39 | int tcp_fastopen_reset_cipher(void *key, unsigned int len) | |
40 | { | |
41 | int err; | |
42 | struct tcp_fastopen_context *ctx, *octx; | |
43 | ||
44 | ctx = kmalloc(sizeof(*ctx), GFP_KERNEL); | |
45 | if (!ctx) | |
46 | return -ENOMEM; | |
47 | ctx->tfm = crypto_alloc_cipher("aes", 0, 0); | |
48 | ||
49 | if (IS_ERR(ctx->tfm)) { | |
50 | err = PTR_ERR(ctx->tfm); | |
51 | error: kfree(ctx); | |
52 | pr_err("TCP: TFO aes cipher alloc error: %d\n", err); | |
53 | return err; | |
54 | } | |
55 | err = crypto_cipher_setkey(ctx->tfm, key, len); | |
56 | if (err) { | |
57 | pr_err("TCP: TFO cipher key error: %d\n", err); | |
58 | crypto_free_cipher(ctx->tfm); | |
59 | goto error; | |
60 | } | |
61 | memcpy(ctx->key, key, len); | |
62 | ||
63 | spin_lock(&tcp_fastopen_ctx_lock); | |
64 | ||
65 | octx = rcu_dereference_protected(tcp_fastopen_ctx, | |
66 | lockdep_is_held(&tcp_fastopen_ctx_lock)); | |
67 | rcu_assign_pointer(tcp_fastopen_ctx, ctx); | |
68 | spin_unlock(&tcp_fastopen_ctx_lock); | |
69 | ||
70 | if (octx) | |
71 | call_rcu(&octx->rcu, tcp_fastopen_ctx_free); | |
72 | return err; | |
73 | } | |
74 | ||
149479d0 YC |
75 | /* Computes the fastopen cookie for the IP path. |
76 | * The path is a 128 bits long (pad with zeros for IPv4). | |
10467163 JC |
77 | * |
78 | * The caller must check foc->len to determine if a valid cookie | |
79 | * has been generated successfully. | |
80 | */ | |
149479d0 YC |
81 | void tcp_fastopen_cookie_gen(__be32 src, __be32 dst, |
82 | struct tcp_fastopen_cookie *foc) | |
10467163 | 83 | { |
149479d0 | 84 | __be32 path[4] = { src, dst, 0, 0 }; |
10467163 JC |
85 | struct tcp_fastopen_context *ctx; |
86 | ||
222e83d2 HFS |
87 | tcp_fastopen_init_key_once(true); |
88 | ||
10467163 JC |
89 | rcu_read_lock(); |
90 | ctx = rcu_dereference(tcp_fastopen_ctx); | |
91 | if (ctx) { | |
149479d0 | 92 | crypto_cipher_encrypt_one(ctx->tfm, foc->val, (__u8 *)path); |
10467163 JC |
93 | foc->len = TCP_FASTOPEN_COOKIE_SIZE; |
94 | } | |
95 | rcu_read_unlock(); | |
96 | } |