tls: keep TX and RX hardware offload on the same device

After TX is offloaded on device A, a route change, or a change in the
usable-slave set of an 802.3ad or balance-xor (layer3+4) bond, can make
RX setup program device B. tls_device_attach() sees the existing TLS
destructor and keeps ctx->netdev pointing at A. The RX driver state on B
is then untracked: tls_dev_resync() and tls_dev_del() are invoked on A
for a context it never created, and neither socket close nor
NETDEV_DOWN on B calls tls_dev_del() for B, so the driver context leaks.
The reverse setup order has the same problem.

Check the shared device binding under device_offload_lock before each
tls_dev_add(). Permit the first attachment and a second direction on the
same device. Reject a different device, including when the old binding
was cleared by NETDEV_DOWN: the TLS destructor remains installed and
tls_device_attach() cannot establish a new binding. Setup then falls
back to software for the requested direction.

The RX check precedes allocation and software setup. TX uses its existing
resource unwind path without calling the driver. Document the shared
binding and clarify that fallback is per direction.

This issue was discovered during code review and subsequently
reproduced on hardware using mlx5 and TLS 1.2 AES-GCM-128.

Changing the route between TX and RX setup installed the second
direction on a different device. Driver traces showed successful adds
on both devices, but both deletes at socket close targeted the first
device, leaving an orphaned context on the second. Both setup orders
reproduced the leak, even though all current core TLS context counters
returned to zero. No crash was observed.

With the fix, the same tests correctly fall back to software for the
second direction and leave no orphaned hardware context.

Fixes: 4799ac81e52a ("tls: Add rx inline crypto offload")
Signed-off-by: Rishikesh Jethwani <rjethwani@purestorage.com>
Signed-off-by: Dave Miller <davem@davem-thinkpadp1gen8.ibmlond.csb>

0 files changed, 0 insertions, 0 deletions