Fill in some gaps in the TLS offload doc: - describe the tls_dev_del and tls_dev_resync callbacks - add a mention of rekeying being out of scope for now Signed-off-by: Jakub Kicinski --- v2: - add mentions of the callback in resync text - Stack -> The stack v1: https://lore.kernel.org/20260609201224.1191391-1-kuba@kernel.org CC: john.fastabend@gmail.com CC: sd@queasysnail.net CC: corbet@lwn.net CC: skhan@linuxfoundation.org CC: linux-doc@vger.kernel.org --- Documentation/networking/tls-offload.rst | 45 ++++++++++++++++++++---- 1 file changed, 38 insertions(+), 7 deletions(-) diff --git a/Documentation/networking/tls-offload.rst b/Documentation/networking/tls-offload.rst index 25ee8d9f12c9..e5802bcd4d22 100644 --- a/Documentation/networking/tls-offload.rst +++ b/Documentation/networking/tls-offload.rst @@ -99,6 +99,29 @@ at the end of kernel structures (see :c:member:`driver_state` members in ``include/net/tls.h``) to avoid additional allocations and pointer dereferences. +When the offloaded connection is destroyed the core calls +the :c:member:`tls_dev_del` callback so the driver can release per-direction +state: + +.. code-block:: c + + void (*tls_dev_del)(struct net_device *netdev, + struct tls_context *ctx, + enum tls_offload_ctx_dir direction); + +``tls_dev_del`` is mandatory whenever ``tls_dev_add`` is provided. + +The third TLS device callback is :c:member:`tls_dev_resync`, called by the core +to synchronize the TCP stream with the record boundaries: + +.. code-block:: c + + int (*tls_dev_resync)(struct net_device *netdev, + struct sock *sk, u32 seq, u8 *rcd_sn, + enum tls_offload_ctx_dir direction); + +See the `Resync handling`_ section for details. + TX -- @@ -250,9 +273,9 @@ sequence number (as it will be updated from a different context). 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). +and TLS record number to the driver via the ``tls_dev_resync`` callback. +The 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 -- @@ -344,9 +367,10 @@ all TLS record headers that have been logged since the resync request started. The kernel confirms the guessed location was correct and tells the device -the record sequence number. Meanwhile, the device had been parsing -and counting all records since the just-confirmed one, it adds the number -of records it had seen to the record number provided by the kernel. +the record sequence number via the ``tls_dev_resync`` callback. Meanwhile, +the device had been parsing and counting all records since the just-confirmed +one, it adds the number of records it had seen to the record number provided +by the kernel. At this point the device is in sync and can resume decryption at next segment boundary. @@ -370,12 +394,19 @@ schedules resynchronization after it has received two completely encrypted records. The stack waits for the socket to drain and informs the device about -the next expected record number and its TCP sequence number. If the +the next expected record number and its TCP sequence number via the +``tls_dev_resync`` callback. If the records continue to be received fully encrypted stack retries the synchronization with an exponential back off (first after 2 encrypted records, then after 4 records, after 8, after 16... up until every 128 records). +Rekey +===== + +Offload does not currently support TLS 1.3, therefore key rotation +is not a concern for offloaded connections at this point. + Error handling ============== -- 2.54.0