Linux 3.14

[~andy/linux] / net / ipv4 / tcp_fastopen.c

diff --git a/net/ipv4/tcp_fastopen.c b/net/ipv4/tcp_fastopen.c
index ab7bd35bb312c6e9e07aa2950d75ec4bbc982eac..f195d9316e55d3d7ef6dc5285606ea9de0f52a51 100644 (file)
--- a/net/ipv4/tcp_fastopen.c
+++ b/net/ipv4/tcp_fastopen.c
@@ -8,12 +8,26 @@
 #include <net/inetpeer.h>
 #include <net/tcp.h>
 
-int sysctl_tcp_fastopen __read_mostly;
+int sysctl_tcp_fastopen __read_mostly = TFO_CLIENT_ENABLE;
 
 struct tcp_fastopen_context __rcu *tcp_fastopen_ctx;
 
 static DEFINE_SPINLOCK(tcp_fastopen_ctx_lock);
 
+void tcp_fastopen_init_key_once(bool publish)
+{
+       static u8 key[TCP_FASTOPEN_KEY_LENGTH];
+
+       /* tcp_fastopen_reset_cipher publishes the new context
+        * atomically, so we allow this race happening here.
+        *
+        * All call sites of tcp_fastopen_cookie_gen also check
+        * for a valid cookie, so this is an acceptable risk.
+        */
+       if (net_get_random_once(key, sizeof(key)) && publish)
+               tcp_fastopen_reset_cipher(key, sizeof(key));
+}
+
 static void tcp_fastopen_ctx_free(struct rcu_head *head)
 {
        struct tcp_fastopen_context *ctx =
@@ -70,6 +84,8 @@ void tcp_fastopen_cookie_gen(__be32 src, __be32 dst,
        __be32 path[4] = { src, dst, 0, 0 };
        struct tcp_fastopen_context *ctx;
 
+       tcp_fastopen_init_key_once(true);
+
        rcu_read_lock();
        ctx = rcu_dereference(tcp_fastopen_ctx);
        if (ctx) {
@@ -78,14 +94,3 @@ void tcp_fastopen_cookie_gen(__be32 src, __be32 dst,
        }
        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;
-}
-
-late_initcall(tcp_fastopen_init);