Jerry Chu | 1046716 | 2012-08-31 12:29:11 +0000 | [diff] [blame] | 1 | #include <linux/err.h> |
Yuchung Cheng | 2100c8d | 2012-07-19 06:43:05 +0000 | [diff] [blame] | 2 | #include <linux/init.h> |
| 3 | #include <linux/kernel.h> |
Jerry Chu | 1046716 | 2012-08-31 12:29:11 +0000 | [diff] [blame] | 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> |
Yuchung Cheng | 2100c8d | 2012-07-19 06:43:05 +0000 | [diff] [blame] | 10 | |
Jerry Chu | 1046716 | 2012-08-31 12:29:11 +0000 | [diff] [blame] | 11 | int sysctl_tcp_fastopen __read_mostly; |
| 12 | |
| 13 | struct tcp_fastopen_context __rcu *tcp_fastopen_ctx; |
| 14 | |
| 15 | static DEFINE_SPINLOCK(tcp_fastopen_ctx_lock); |
| 16 | |
Hannes Frederic Sowa | 222e83d | 2013-10-19 21:48:58 +0200 | [diff] [blame] | 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 | |
Jerry Chu | 1046716 | 2012-08-31 12:29:11 +0000 | [diff] [blame] | 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 | |
Yuchung Cheng | 149479d | 2013-08-08 14:06:22 -0700 | [diff] [blame] | 75 | /* Computes the fastopen cookie for the IP path. |
| 76 | * The path is a 128 bits long (pad with zeros for IPv4). |
Jerry Chu | 1046716 | 2012-08-31 12:29:11 +0000 | [diff] [blame] | 77 | * |
| 78 | * The caller must check foc->len to determine if a valid cookie |
| 79 | * has been generated successfully. |
| 80 | */ |
Yuchung Cheng | 149479d | 2013-08-08 14:06:22 -0700 | [diff] [blame] | 81 | void tcp_fastopen_cookie_gen(__be32 src, __be32 dst, |
| 82 | struct tcp_fastopen_cookie *foc) |
Jerry Chu | 1046716 | 2012-08-31 12:29:11 +0000 | [diff] [blame] | 83 | { |
Yuchung Cheng | 149479d | 2013-08-08 14:06:22 -0700 | [diff] [blame] | 84 | __be32 path[4] = { src, dst, 0, 0 }; |
Jerry Chu | 1046716 | 2012-08-31 12:29:11 +0000 | [diff] [blame] | 85 | struct tcp_fastopen_context *ctx; |
| 86 | |
Hannes Frederic Sowa | 222e83d | 2013-10-19 21:48:58 +0200 | [diff] [blame] | 87 | tcp_fastopen_init_key_once(true); |
| 88 | |
Jerry Chu | 1046716 | 2012-08-31 12:29:11 +0000 | [diff] [blame] | 89 | rcu_read_lock(); |
| 90 | ctx = rcu_dereference(tcp_fastopen_ctx); |
| 91 | if (ctx) { |
Yuchung Cheng | 149479d | 2013-08-08 14:06:22 -0700 | [diff] [blame] | 92 | crypto_cipher_encrypt_one(ctx->tfm, foc->val, (__u8 *)path); |
Jerry Chu | 1046716 | 2012-08-31 12:29:11 +0000 | [diff] [blame] | 93 | foc->len = TCP_FASTOPEN_COOKIE_SIZE; |
| 94 | } |
| 95 | rcu_read_unlock(); |
| 96 | } |