tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1#include <linux/err.h>
2#include <linux/init.h>
3#include <linux/kernel.h>
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>
10
11int sysctl_tcp_fastopen __read_mostly;
12
13struct tcp_fastopen_context __rcu *tcp_fastopen_ctx;
14
15static DEFINE_SPINLOCK(tcp_fastopen_ctx_lock);
16
17static void tcp_fastopen_ctx_free(struct rcu_head *head)
18{
19 struct tcp_fastopen_context *ctx =
20 container_of(head, struct tcp_fastopen_context, rcu);
21 crypto_free_cipher(ctx->tfm);
22 kfree(ctx);
23}
24
25int tcp_fastopen_reset_cipher(void *key, unsigned int len)
26{
27 int err;
28 struct tcp_fastopen_context *ctx, *octx;
29
30 ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
31 if (!ctx)
32 return -ENOMEM;
33 ctx->tfm = crypto_alloc_cipher("aes", 0, 0);
34
35 if (IS_ERR(ctx->tfm)) {
36 err = PTR_ERR(ctx->tfm);
37error: kfree(ctx);
38 pr_err("TCP: TFO aes cipher alloc error: %d\n", err);
39 return err;
40 }
41 err = crypto_cipher_setkey(ctx->tfm, key, len);
42 if (err) {
43 pr_err("TCP: TFO cipher key error: %d\n", err);
44 crypto_free_cipher(ctx->tfm);
45 goto error;
46 }
47 memcpy(ctx->key, key, len);
48
49 spin_lock(&tcp_fastopen_ctx_lock);
50
51 octx = rcu_dereference_protected(tcp_fastopen_ctx,
52 lockdep_is_held(&tcp_fastopen_ctx_lock));
53 rcu_assign_pointer(tcp_fastopen_ctx, ctx);
54 spin_unlock(&tcp_fastopen_ctx_lock);
55
56 if (octx)
57 call_rcu(&octx->rcu, tcp_fastopen_ctx_free);
58 return err;
59}
60
61/* Computes the fastopen cookie for the peer.
62 * The peer address is a 128 bits long (pad with zeros for IPv4).
63 *
64 * The caller must check foc->len to determine if a valid cookie
65 * has been generated successfully.
66*/
67void tcp_fastopen_cookie_gen(__be32 addr, struct tcp_fastopen_cookie *foc)
68{
69 __be32 peer_addr[4] = { addr, 0, 0, 0 };
70 struct tcp_fastopen_context *ctx;
71
72 rcu_read_lock();
73 ctx = rcu_dereference(tcp_fastopen_ctx);
74 if (ctx) {
75 crypto_cipher_encrypt_one(ctx->tfm,
76 foc->val,
77 (__u8 *)peer_addr);
78 foc->len = TCP_FASTOPEN_COOKIE_SIZE;
79 }
80 rcu_read_unlock();
81}
82
83static int __init tcp_fastopen_init(void)
84{
85 __u8 key[TCP_FASTOPEN_KEY_LENGTH];
86
87 get_random_bytes(key, sizeof(key));
88 tcp_fastopen_reset_cipher(key, sizeof(key));
89 return 0;
90}
91
92late_initcall(tcp_fastopen_init);