From 3544c98acd09b3b40e86f015f7df75a7d2d72a5c Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Mon, 2 Sep 2019 21:31:04 -0700 Subject: [PATCH] net/tls: narrow down the critical area of device_offload_lock On setsockopt path we need to hold device_offload_lock from the moment we check netdev is up until the context is fully ready to be added to the tls_device_list. No need to hold it around the get_netdev_for_sock(). Change the code and remove the confusing comment. Signed-off-by: Jakub Kicinski Reviewed-by: John Hurley Reviewed-by: Dirk van der Merwe Signed-off-by: David S. Miller --- net/tls/tls_device.c | 46 +++++++++++++++++++++----------------------- 1 file changed, 22 insertions(+), 24 deletions(-) diff --git a/net/tls/tls_device.c b/net/tls/tls_device.c index 2cd7318a1338..9e1bec1a0a28 100644 --- a/net/tls/tls_device.c +++ b/net/tls/tls_device.c @@ -935,17 +935,11 @@ int tls_set_device_offload(struct sock *sk, struct tls_context *ctx) if (skb) TCP_SKB_CB(skb)->eor = 1; - /* We support starting offload on multiple sockets - * concurrently, so we only need a read lock here. - * This lock must precede get_netdev_for_sock to prevent races between - * NETDEV_DOWN and setsockopt. - */ - down_read(&device_offload_lock); netdev = get_netdev_for_sock(sk); if (!netdev) { pr_err_ratelimited("%s: netdev not found\n", __func__); rc = -EINVAL; - goto release_lock; + goto disable_cad; } if (!(netdev->features & NETIF_F_HW_TLS_TX)) { @@ -956,10 +950,15 @@ int tls_set_device_offload(struct sock *sk, struct tls_context *ctx) /* Avoid offloading if the device is down * We don't want to offload new flows after * the NETDEV_DOWN event + * + * device_offload_lock is taken in tls_devices's NETDEV_DOWN + * handler thus protecting from the device going down before + * ctx was added to tls_device_list. */ + down_read(&device_offload_lock); if (!(netdev->flags & IFF_UP)) { rc = -EINVAL; - goto release_netdev; + goto release_lock; } ctx->priv_ctx_tx = offload_ctx; @@ -967,9 +966,10 @@ int tls_set_device_offload(struct sock *sk, struct tls_context *ctx) &ctx->crypto_send.info, tcp_sk(sk)->write_seq); if (rc) - goto release_netdev; + goto release_lock; tls_device_attach(ctx, sk, netdev); + up_read(&device_offload_lock); /* following this assignment tls_is_sk_tx_device_offloaded * will return true and the context might be accessed @@ -977,14 +977,14 @@ int tls_set_device_offload(struct sock *sk, struct tls_context *ctx) */ smp_store_release(&sk->sk_validate_xmit_skb, tls_validate_xmit_skb); dev_put(netdev); - up_read(&device_offload_lock); return 0; -release_netdev: - dev_put(netdev); release_lock: up_read(&device_offload_lock); +release_netdev: + dev_put(netdev); +disable_cad: clean_acked_data_disable(inet_csk(sk)); crypto_free_aead(offload_ctx->aead_send); free_rec_seq: @@ -1008,17 +1008,10 @@ int tls_set_device_offload_rx(struct sock *sk, struct tls_context *ctx) if (ctx->crypto_recv.info.version != TLS_1_2_VERSION) return -EOPNOTSUPP; - /* We support starting offload on multiple sockets - * concurrently, so we only need a read lock here. - * This lock must precede get_netdev_for_sock to prevent races between - * NETDEV_DOWN and setsockopt. - */ - down_read(&device_offload_lock); netdev = get_netdev_for_sock(sk); if (!netdev) { pr_err_ratelimited("%s: netdev not found\n", __func__); - rc = -EINVAL; - goto release_lock; + return -EINVAL; } if (!(netdev->features & NETIF_F_HW_TLS_RX)) { @@ -1029,16 +1022,21 @@ int tls_set_device_offload_rx(struct sock *sk, struct tls_context *ctx) /* Avoid offloading if the device is down * We don't want to offload new flows after * the NETDEV_DOWN event + * + * device_offload_lock is taken in tls_devices's NETDEV_DOWN + * handler thus protecting from the device going down before + * ctx was added to tls_device_list. */ + down_read(&device_offload_lock); if (!(netdev->flags & IFF_UP)) { rc = -EINVAL; - goto release_netdev; + goto release_lock; } context = kzalloc(TLS_OFFLOAD_CONTEXT_SIZE_RX, GFP_KERNEL); if (!context) { rc = -ENOMEM; - goto release_netdev; + goto release_lock; } context->resync_nh_reset = 1; @@ -1066,10 +1064,10 @@ free_sw_resources: down_read(&device_offload_lock); release_ctx: ctx->priv_ctx_rx = NULL; -release_netdev: - dev_put(netdev); release_lock: up_read(&device_offload_lock); +release_netdev: + dev_put(netdev); return rc; }