1 files changed, 82 insertions, 1 deletions

diff --git a/net/ipv4/tcp_fastopen.c b/net/ipv4/tcp_fastopen.c
index a7f729c409d7..8f7ef0ad80e5 100644
--- a/net/ipv4/tcp_fastopen.c
+++ b/net/ipv4/tcp_fastopen.c
@@ -1,10 +1,91 @@
+#include <linux/err.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/tcp.h>
+#include <linux/rcupdate.h>
+#include <linux/rculist.h>
+#include <net/inetpeer.h>
+#include <net/tcp.h>
 
-int sysctl_tcp_fastopen;
+int sysctl_tcp_fastopen __read_mostly;
+
+struct tcp_fastopen_context __rcu *tcp_fastopen_ctx;
+
+static DEFINE_SPINLOCK(tcp_fastopen_ctx_lock);
+
+static void tcp_fastopen_ctx_free(struct rcu_head *head)
+{
+        struct tcp_fastopen_context *ctx =
+            container_of(head, struct tcp_fastopen_context, rcu);
+        crypto_free_cipher(ctx->tfm);
+        kfree(ctx);
+}
+
+int tcp_fastopen_reset_cipher(void *key, unsigned int len)
+{
+        int err;
+        struct tcp_fastopen_context *ctx, *octx;
+
+        ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
+        if (!ctx)
+                return -ENOMEM;
+        ctx->tfm = crypto_alloc_cipher("aes", 0, 0);
+
+        if (IS_ERR(ctx->tfm)) {
+                err = PTR_ERR(ctx->tfm);
+error:          kfree(ctx);
+                pr_err("TCP: TFO aes cipher alloc error: %d\n", err);
+                return err;
+        }
+        err = crypto_cipher_setkey(ctx->tfm, key, len);
+        if (err) {
+                pr_err("TCP: TFO cipher key error: %d\n", err);
+                crypto_free_cipher(ctx->tfm);
+                goto error;
+        }
+        memcpy(ctx->key, key, len);
+
+        spin_lock(&tcp_fastopen_ctx_lock);
+
+        octx = rcu_dereference_protected(tcp_fastopen_ctx,
+                                lockdep_is_held(&tcp_fastopen_ctx_lock));
+        rcu_assign_pointer(tcp_fastopen_ctx, ctx);
+        spin_unlock(&tcp_fastopen_ctx_lock);
+
+        if (octx)
+                call_rcu(&octx->rcu, tcp_fastopen_ctx_free);
+        return err;
+}
+
+/* Computes the fastopen cookie for the peer.
+ * The peer address is a 128 bits long (pad with zeros for IPv4).
+ *
+ * The caller must check foc->len to determine if a valid cookie
+ * has been generated successfully.
+*/
+void tcp_fastopen_cookie_gen(__be32 addr, struct tcp_fastopen_cookie *foc)
+{
+        __be32 peer_addr[4] = { addr, 0, 0, 0 };
+        struct tcp_fastopen_context *ctx;
+
+        rcu_read_lock();
+        ctx = rcu_dereference(tcp_fastopen_ctx);
+        if (ctx) {
+                crypto_cipher_encrypt_one(ctx->tfm,
+                                          foc->val,
+                                          (__u8 *)peer_addr);
+                foc->len = TCP_FASTOPEN_COOKIE_SIZE;
+        }
+        rcu_read_unlock();
+}
 
 static int __init tcp_fastopen_init(void)
 {
+        __u8 key[TCP_FASTOPEN_KEY_LENGTH];
+
+        get_random_bytes(key, sizeof(key));
+        tcp_fastopen_reset_cipher(key, sizeof(key));
         return 0;
 }