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Diffstat (limited to 'Documentation/networking')
| -rw-r--r-- | Documentation/networking/tls-offload.rst | 35 |
1 files changed, 34 insertions, 1 deletions
diff --git a/Documentation/networking/tls-offload.rst b/Documentation/networking/tls-offload.rst index d134d63307e7..048e5ca44824 100644 --- a/Documentation/networking/tls-offload.rst +++ b/Documentation/networking/tls-offload.rst @@ -206,7 +206,11 @@ TX Segments transmitted from an offloaded socket can get out of sync in similar ways to the receive side-retransmissions - local drops -are possible, though network reorders are not. +are possible, though network reorders are not. There are currently +two mechanisms for dealing with out of order segments. + +Crypto state rebuilding +~~~~~~~~~~~~~~~~~~~~~~~ Whenever an out of order segment is transmitted the driver provides the device with enough information to perform cryptographic operations. @@ -225,6 +229,35 @@ was just a retransmission. The former is simpler, and does not require retransmission detection therefore it is the recommended method until such time it is proven inefficient. +Next record sync +~~~~~~~~~~~~~~~~ + +Whenever an out of order segment is detected the driver requests +that the ``ktls`` software fallback code encrypt it. If the segment's +sequence number is lower than expected the driver assumes retransmission +and doesn't change device state. If the segment is in the future, it +may imply a local drop, the driver asks the stack to sync the device +to the next record state and falls back to software. + +Resync request is indicated with: + +.. code-block:: c + + void tls_offload_tx_resync_request(struct sock *sk, u32 got_seq, u32 exp_seq) + +Until resync is complete driver should not access its expected TCP +sequence number (as it will be updated from a different context). +Following helper should be used to test if resync is complete: + +.. code-block:: c + + bool tls_offload_tx_resync_pending(struct sock *sk) + +Next time ``ktls`` pushes a record it will first send its TCP sequence number +and TLS record number to the driver. Stack will also make sure that +the new record will start on a segment boundary (like it does when +the connection is initially added). + RX -- |