mptcp: token: move retry to caller

Once syncookie support is added, no state will be stored anymore when the
syn/ack is generated in syncookie mode.

When the ACK comes back, the generated key will be taken from the TCP ACK,
the token is re-generated and inserted into the token tree.

This means we can't retry with a new key when the token is already taken
in the syncookie case.

Therefore, move the retry logic to the caller to prepare for syncookie
support in mptcp.

Signed-off-by: Florian Westphal <fw@strlen.de>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 1c8482b..9feb878 100644 (file)
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -126,11 +126,18 @@ static void subflow_init_req(struct request_sock *req,
        }
 
        if (mp_opt.mp_capable && listener->request_mptcp) {
-               int err;
+               int err, retries = 4;
+
+again:
+               do {
+                       get_random_bytes(&subflow_req->local_key, sizeof(subflow_req->local_key));
+               } while (subflow_req->local_key == 0);
 
                err = mptcp_token_new_request(req);
                if (err == 0)
                        subflow_req->mp_capable = 1;
+               else if (retries-- > 0)
+                       goto again;
 
                subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq;
        } else if (mp_opt.mp_join && listener->request_mptcp) {

diff --git a/net/mptcp/token.c b/net/mptcp/token.c
index 97cfc45..f82410c 100644 (file)
--- a/net/mptcp/token.c
+++ b/net/mptcp/token.c
@@ -109,14 +109,12 @@ static void mptcp_crypto_key_gen_sha(u64 *key, u32 *token, u64 *idsn)
 int mptcp_token_new_request(struct request_sock *req)
 {
        struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
-       int retries = TOKEN_MAX_RETRIES;
        struct token_bucket *bucket;
        u32 token;
 
-again:
-       mptcp_crypto_key_gen_sha(&subflow_req->local_key,
-                                &subflow_req->token,
-                                &subflow_req->idsn);
+       mptcp_crypto_key_sha(subflow_req->local_key,
+                            &subflow_req->token,
+                            &subflow_req->idsn);
        pr_debug("req=%p local_key=%llu, token=%u, idsn=%llu\n",
                 req, subflow_req->local_key, subflow_req->token,
                 subflow_req->idsn);
@@ -126,9 +124,7 @@ again:
        spin_lock_bh(&bucket->lock);
        if (__token_bucket_busy(bucket, token)) {
                spin_unlock_bh(&bucket->lock);
-               if (!--retries)
-                       return -EBUSY;
-               goto again;
+               return -EBUSY;
        }
 
        hlist_nulls_add_head_rcu(&subflow_req->token_node, &bucket->req_chain);