net/tls: fix state removal with feature flags off [Linux 5.2]

net/tls: fix state removal with feature flags off [Linux 5.2]

This Linux kernel change "net/tls: fix state removal with feature flags off" is included in the Linux 5.2 release. This change is authored by Jakub Kicinski <jakub.kicinski [at] netronome.com> on Tue May 21 19:02:01 2019 -0700. The commit for this change in Linux stable tree is 3686637 (patch).

net/tls: fix state removal with feature flags off

TLS offload drivers shouldn't (and currently don't) block
the TLS offload feature changes based on whether there are
active offloaded connections or not.

This seems to be a good idea, because we want the admin to
be able to disable the TLS offload at any time, and there
is no clean way of disabling it for active connections
(TX side is quite problematic).  So if features are cleared
existing connections will stay offloaded until they close,
and new connections will not attempt offload to a given
device.

However, the offload state removal handling is currently
broken if feature flags get cleared while there are
active TLS offloads.

RX side will completely bail from cleanup, even on normal
remove path, leaving device state dangling, potentially
causing issues when the 5-tuple is reused.  It will also
fail to release the netdev reference.

Remove the RX-side warning message, in next release cycle
it should be printed when features are disabled, rather
than when connection dies, but for that we need a more
efficient method of finding connection of a given netdev
(a'la BPF offload code).

Fixes: 4799ac81e52a ("tls: Add rx inline crypto offload")
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Dirk van der Merwe <dirk.vandermerwe@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

There are 6 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 net/tls/tls_device.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/net/tls/tls_device.c b/net/tls/tls_device.c
index aa33e4a..0765044 100644
--- a/net/tls/tls_device.c
+++ b/net/tls/tls_device.c
@@ -939,12 +939,6 @@ void tls_device_offload_cleanup_rx(struct sock *sk)
    if (!netdev)
        goto out;

-   if (!(netdev->features & NETIF_F_HW_TLS_RX)) {
-       pr_err_ratelimited("%s: device is missing NETIF_F_HW_TLS_RX cap\n",
-                  __func__);
-       goto out;
-   }
-
    netdev->tlsdev_ops->tls_dev_del(netdev, tls_ctx,
                    TLS_OFFLOAD_CTX_DIR_RX);

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