Update Linux to v5.10.109
Sourced from [1]
[1] https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.10.109.tar.xz
Change-Id: I19bca9fc6762d4e63bcf3e4cba88bbe560d9c76c
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/net/mptcp/syncookies.c b/net/mptcp/syncookies.c
new file mode 100644
index 0000000..7f22526
--- /dev/null
+++ b/net/mptcp/syncookies.c
@@ -0,0 +1,133 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/skbuff.h>
+
+#include "protocol.h"
+
+/* Syncookies do not work for JOIN requests.
+ *
+ * Unlike MP_CAPABLE, where the ACK cookie contains the needed MPTCP
+ * options to reconstruct the initial syn state, MP_JOIN does not contain
+ * the token to obtain the mptcp socket nor the server-generated nonce
+ * that was used in the cookie SYN/ACK response.
+ *
+ * Keep a small best effort state table to store the syn/synack data,
+ * indexed by skb hash.
+ *
+ * A MP_JOIN SYN packet handled by syn cookies is only stored if the 32bit
+ * token matches a known mptcp connection that can still accept more subflows.
+ *
+ * There is no timeout handling -- state is only re-constructed
+ * when the TCP ACK passed the cookie validation check.
+ */
+
+struct join_entry {
+ u32 token;
+ u32 remote_nonce;
+ u32 local_nonce;
+ u8 join_id;
+ u8 local_id;
+ u8 backup;
+ u8 valid;
+};
+
+#define COOKIE_JOIN_SLOTS 1024
+
+static struct join_entry join_entries[COOKIE_JOIN_SLOTS] __cacheline_aligned_in_smp;
+static spinlock_t join_entry_locks[COOKIE_JOIN_SLOTS] __cacheline_aligned_in_smp;
+
+static u32 mptcp_join_entry_hash(struct sk_buff *skb, struct net *net)
+{
+ static u32 mptcp_join_hash_secret __read_mostly;
+ struct tcphdr *th = tcp_hdr(skb);
+ u32 seq, i;
+
+ net_get_random_once(&mptcp_join_hash_secret,
+ sizeof(mptcp_join_hash_secret));
+
+ if (th->syn)
+ seq = TCP_SKB_CB(skb)->seq;
+ else
+ seq = TCP_SKB_CB(skb)->seq - 1;
+
+ i = jhash_3words(seq, net_hash_mix(net),
+ (__force __u32)th->source << 16 | (__force __u32)th->dest,
+ mptcp_join_hash_secret);
+
+ return i % ARRAY_SIZE(join_entries);
+}
+
+static void mptcp_join_store_state(struct join_entry *entry,
+ const struct mptcp_subflow_request_sock *subflow_req)
+{
+ entry->token = subflow_req->token;
+ entry->remote_nonce = subflow_req->remote_nonce;
+ entry->local_nonce = subflow_req->local_nonce;
+ entry->backup = subflow_req->backup;
+ entry->join_id = subflow_req->remote_id;
+ entry->local_id = subflow_req->local_id;
+ entry->valid = 1;
+}
+
+void subflow_init_req_cookie_join_save(const struct mptcp_subflow_request_sock *subflow_req,
+ struct sk_buff *skb)
+{
+ struct net *net = read_pnet(&subflow_req->sk.req.ireq_net);
+ u32 i = mptcp_join_entry_hash(skb, net);
+
+ /* No use in waiting if other cpu is already using this slot --
+ * would overwrite the data that got stored.
+ */
+ spin_lock_bh(&join_entry_locks[i]);
+ mptcp_join_store_state(&join_entries[i], subflow_req);
+ spin_unlock_bh(&join_entry_locks[i]);
+}
+
+/* Called for a cookie-ack with MP_JOIN option present.
+ * Look up the saved state based on skb hash & check token matches msk
+ * in same netns.
+ *
+ * Caller will check msk can still accept another subflow. The hmac
+ * present in the cookie ACK mptcp option space will be checked later.
+ */
+bool mptcp_token_join_cookie_init_state(struct mptcp_subflow_request_sock *subflow_req,
+ struct sk_buff *skb)
+{
+ struct net *net = read_pnet(&subflow_req->sk.req.ireq_net);
+ u32 i = mptcp_join_entry_hash(skb, net);
+ struct mptcp_sock *msk;
+ struct join_entry *e;
+
+ e = &join_entries[i];
+
+ spin_lock_bh(&join_entry_locks[i]);
+
+ if (e->valid == 0) {
+ spin_unlock_bh(&join_entry_locks[i]);
+ return false;
+ }
+
+ e->valid = 0;
+
+ msk = mptcp_token_get_sock(net, e->token);
+ if (!msk) {
+ spin_unlock_bh(&join_entry_locks[i]);
+ return false;
+ }
+
+ subflow_req->remote_nonce = e->remote_nonce;
+ subflow_req->local_nonce = e->local_nonce;
+ subflow_req->backup = e->backup;
+ subflow_req->remote_id = e->join_id;
+ subflow_req->token = e->token;
+ subflow_req->msk = msk;
+ spin_unlock_bh(&join_entry_locks[i]);
+ return true;
+}
+
+void __init mptcp_join_cookie_init(void)
+{
+ int i;
+
+ for (i = 0; i < COOKIE_JOIN_SLOTS; i++)
+ spin_lock_init(&join_entry_locks[i]);
+}