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 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 17 static 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 25 int 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); 37 error: 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 */ 67 void 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 83 static 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 92 late_initcall(tcp_fastopen_init); 93