From 535fb8152f313dd5d30ef84ce55b01ad9cbae3cf Mon Sep 17 00:00:00 2001
From: Florian Westphal <fw@strlen.de>
Date: Thu, 30 Jul 2020 21:25:51 +0200
Subject: [PATCH] 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>
---
net/mptcp/subflow.c | 9 ++++++++-
net/mptcp/token.c | 12 ++++--------
2 files changed, 12 insertions(+), 9 deletions(-)
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 1c8482bc2ce55..9feb87880d1c2 100644
--- 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 97cfc45bcc4f3..f82410c546538 100644
--- 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);
--
2.30.2