mptcp: generate the data checksum

This patch added a new member named csum in struct mptcp_ext, implemented
a new function named mptcp_generate_data_checksum().

Generate the data checksum in mptcp_sendmsg_frag, save it in mpext->csum.

Note that we must generate the csum for zero window probe, too.

Do the csum update incrementally, to avoid multiple csum computation
when the data is appended to existing skb.

Note that in a later patch we will skip unneeded csum related operation.
Changes not included here to keep the delta small.

Co-developed-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/mptcp.h b/include/net/mptcp.h
index 83f23774b90844e40a76c564687dd1e0be05bb11..23bbd439e1152d22aa3d8f94151bbf8b40f720b9 100644 (file)
--- a/include/net/mptcp.h
+++ b/include/net/mptcp.h
@@ -23,6 +23,7 @@ struct mptcp_ext {
        u64             data_seq;
        u32             subflow_seq;
        u16             data_len;
+       __sum16         csum;
        u8              use_map:1,
                        dsn64:1,
                        data_fin:1,

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 2caca0dc2c1c9c7981acbe6e1ee6ebb7698cd7ce..f0da067301f6313ee42e75ec8cdcb3267334dd11 100644 (file)
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -1308,6 +1308,18 @@ static bool mptcp_alloc_tx_skb(struct sock *sk, struct sock *ssk)
        return __mptcp_alloc_tx_skb(sk, ssk, sk->sk_allocation);
 }
 
+/* note: this always recompute the csum on the whole skb, even
+ * if we just appended a single frag. More status info needed
+ */
+static void mptcp_update_data_checksum(struct sk_buff *skb, int added)
+{
+       struct mptcp_ext *mpext = mptcp_get_ext(skb);
+       __wsum csum = ~csum_unfold(mpext->csum);
+       int offset = skb->len - added;
+
+       mpext->csum = csum_fold(csum_block_add(csum, skb_checksum(skb, offset, added, 0), offset));
+}
+
 static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk,
                              struct mptcp_data_frag *dfrag,
                              struct mptcp_sendmsg_info *info)
@@ -1402,10 +1414,14 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk,
        if (zero_window_probe) {
                mptcp_subflow_ctx(ssk)->rel_write_seq += ret;
                mpext->frozen = 1;
-               ret = 0;
+               if (READ_ONCE(msk->csum_enabled))
+                       mptcp_update_data_checksum(tail, ret);
                tcp_push_pending_frames(ssk);
+               return 0;
        }
 out:
+       if (READ_ONCE(msk->csum_enabled))
+               mptcp_update_data_checksum(tail, ret);
        mptcp_subflow_ctx(ssk)->rel_write_seq += ret;
        return ret;
 }

diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 1fc6693e257e18f0a8e7754c6f8003685c923366..4913ac7b6d199b10aecd1f6fe0c49b7b6dc83b7d 100644 (file)
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -336,6 +336,13 @@ static inline struct mptcp_data_frag *mptcp_rtx_head(const struct sock *sk)
        return list_first_entry_or_null(&msk->rtx_queue, struct mptcp_data_frag, list);
 }
 
+struct csum_pseudo_header {
+       __be64 data_seq;
+       __be32 subflow_seq;
+       __be16 data_len;
+       __sum16 csum;
+};
+
 struct mptcp_subflow_request_sock {
        struct  tcp_request_sock sk;
        u16     mp_capable : 1,