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Date: Thu, 11 Feb 2021 18:56:35 -0800
From: Saeed Mahameed <saeed@...nel.org>
To: "David S. Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>
Cc: netdev@...r.kernel.org, Maxim Mikityanskiy <maximmi@...lanox.com>,
Tariq Toukan <tariqt@...dia.com>,
Saeed Mahameed <saeedm@...dia.com>
Subject: [net 09/15] net/mlx5e: kTLS, Use refcounts to free kTLS RX priv context
From: Maxim Mikityanskiy <maximmi@...lanox.com>
wait_for_resync is unreliable - if it timeouts, priv_rx will be freed
anyway. However, mlx5e_ktls_handle_get_psv_completion will be called
sooner or later, leading to use-after-free. For example, it can happen
if a CQ error happened, and ICOSQ stopped, but later on the queues are
destroyed, and ICOSQ is flushed with mlx5e_free_icosq_descs.
This patch converts the lifecycle of priv_rx to fully refcount-based, so
that the struct won't be freed before the refcount goes to zero.
Fixes: 0419d8c9d8f8 ("net/mlx5e: kTLS, Add kTLS RX resync support")
Signed-off-by: Maxim Mikityanskiy <maximmi@...lanox.com>
Reviewed-by: Tariq Toukan <tariqt@...dia.com>
Signed-off-by: Saeed Mahameed <saeedm@...dia.com>
---
.../mellanox/mlx5/core/en_accel/ktls_rx.c | 64 +++++++++----------
1 file changed, 30 insertions(+), 34 deletions(-)
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_accel/ktls_rx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_accel/ktls_rx.c
index 0f13b661f7f9..d06532d0baa4 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_accel/ktls_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_accel/ktls_rx.c
@@ -57,6 +57,20 @@ struct mlx5e_ktls_offload_context_rx {
struct mlx5e_ktls_rx_resync_ctx resync;
};
+static bool mlx5e_ktls_priv_rx_put(struct mlx5e_ktls_offload_context_rx *priv_rx)
+{
+ if (!refcount_dec_and_test(&priv_rx->resync.refcnt))
+ return false;
+
+ kfree(priv_rx);
+ return true;
+}
+
+static void mlx5e_ktls_priv_rx_get(struct mlx5e_ktls_offload_context_rx *priv_rx)
+{
+ refcount_inc(&priv_rx->resync.refcnt);
+}
+
static int mlx5e_ktls_create_tir(struct mlx5_core_dev *mdev, u32 *tirn, u32 rqtn)
{
int err, inlen;
@@ -326,7 +340,7 @@ static void resync_handle_work(struct work_struct *work)
priv_rx = container_of(resync, struct mlx5e_ktls_offload_context_rx, resync);
if (unlikely(test_bit(MLX5E_PRIV_RX_FLAG_DELETING, priv_rx->flags))) {
- refcount_dec(&resync->refcnt);
+ mlx5e_ktls_priv_rx_put(priv_rx);
return;
}
@@ -334,7 +348,7 @@ static void resync_handle_work(struct work_struct *work)
sq = &c->async_icosq;
if (resync_post_get_progress_params(sq, priv_rx))
- refcount_dec(&resync->refcnt);
+ mlx5e_ktls_priv_rx_put(priv_rx);
}
static void resync_init(struct mlx5e_ktls_rx_resync_ctx *resync,
@@ -377,7 +391,11 @@ static int resync_handle_seq_match(struct mlx5e_ktls_offload_context_rx *priv_rx
return err;
}
-/* Function is called with elevated refcount, it decreases it. */
+/* Function can be called with the refcount being either elevated or not.
+ * It decreases the refcount and may free the kTLS priv context.
+ * Refcount is not elevated only if tls_dev_del has been called, but GET_PSV was
+ * already in flight.
+ */
void mlx5e_ktls_handle_get_psv_completion(struct mlx5e_icosq_wqe_info *wi,
struct mlx5e_icosq *sq)
{
@@ -410,7 +428,7 @@ void mlx5e_ktls_handle_get_psv_completion(struct mlx5e_icosq_wqe_info *wi,
tls_offload_rx_resync_async_request_end(priv_rx->sk, cpu_to_be32(hw_seq));
priv_rx->stats->tls_resync_req_end++;
out:
- refcount_dec(&resync->refcnt);
+ mlx5e_ktls_priv_rx_put(priv_rx);
dma_unmap_single(dev, buf->dma_addr, PROGRESS_PARAMS_PADDED_SIZE, DMA_FROM_DEVICE);
kfree(buf);
}
@@ -431,9 +449,9 @@ static bool resync_queue_get_psv(struct sock *sk)
return false;
resync = &priv_rx->resync;
- refcount_inc(&resync->refcnt);
+ mlx5e_ktls_priv_rx_get(priv_rx);
if (unlikely(!queue_work(resync->priv->tls->rx_wq, &resync->work)))
- refcount_dec(&resync->refcnt);
+ mlx5e_ktls_priv_rx_put(priv_rx);
return true;
}
@@ -625,31 +643,6 @@ int mlx5e_ktls_add_rx(struct net_device *netdev, struct sock *sk,
return err;
}
-/* Elevated refcount on the resync object means there are
- * outstanding operations (uncompleted GET_PSV WQEs) that
- * will read the resync / priv_rx objects once completed.
- * Wait for them to avoid use-after-free.
- */
-static void wait_for_resync(struct net_device *netdev,
- struct mlx5e_ktls_rx_resync_ctx *resync)
-{
-#define MLX5E_KTLS_RX_RESYNC_TIMEOUT 20000 /* msecs */
- unsigned long exp_time = jiffies + msecs_to_jiffies(MLX5E_KTLS_RX_RESYNC_TIMEOUT);
- unsigned int refcnt;
-
- do {
- refcnt = refcount_read(&resync->refcnt);
- if (refcnt == 1)
- return;
-
- msleep(20);
- } while (time_before(jiffies, exp_time));
-
- netdev_warn(netdev,
- "Failed waiting for kTLS RX resync refcnt to be released (%u).\n",
- refcnt);
-}
-
void mlx5e_ktls_del_rx(struct net_device *netdev, struct tls_context *tls_ctx)
{
struct mlx5e_ktls_offload_context_rx *priv_rx;
@@ -671,8 +664,7 @@ void mlx5e_ktls_del_rx(struct net_device *netdev, struct tls_context *tls_ctx)
wait_for_completion(&priv_rx->add_ctx);
resync = &priv_rx->resync;
if (cancel_work_sync(&resync->work))
- refcount_dec(&resync->refcnt);
- wait_for_resync(netdev, resync);
+ mlx5e_ktls_priv_rx_put(priv_rx);
priv_rx->stats->tls_del++;
if (priv_rx->rule.rule)
@@ -680,5 +672,9 @@ void mlx5e_ktls_del_rx(struct net_device *netdev, struct tls_context *tls_ctx)
mlx5_core_destroy_tir(mdev, priv_rx->tirn);
mlx5_ktls_destroy_key(mdev, priv_rx->key_id);
- kfree(priv_rx);
+ /* priv_rx should normally be freed here, but if there is an outstanding
+ * GET_PSV, deallocation will be delayed until the CQE for GET_PSV is
+ * processed.
+ */
+ mlx5e_ktls_priv_rx_put(priv_rx);
}
--
2.29.2
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