Merge https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf

Daniel Borkmann says:

====================
pull-request: bpf 2020-11-28

1) Do not reference the skb for xsk's generic TX side since when looped
   back into RX it might crash in generic XDP, from Björn Töpel.

2) Fix umem cleanup on a partially set up xsk socket when being destroyed,
   from Magnus Karlsson.

3) Fix an incorrect netdev reference count when failing xsk_bind() operation,
   from Marek Majtyka.

4) Fix bpftool to set an error code on failed calloc() in build_btf_type_table(),
   from Zhen Lei.

* https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf:
  bpf: Add MAINTAINERS entry for BPF LSM
  bpftool: Fix error return value in build_btf_type_table
  net, xsk: Avoid taking multiple skbuff references
  xsk: Fix incorrect netdev reference count
  xsk: Fix umem cleanup bug at socket destruct
  MAINTAINERS: Update XDP and AF_XDP entries
====================

Link: https://lore.kernel.org/r/20201128005104.1205-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

5 files changed, 25 insertions, 20 deletions

diff --git a/net/core/dev.c b/net/core/dev.c
index 82dc6b48e45f..8588ade790cb 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4180,7 +4180,7 @@ int dev_queue_xmit_accel(struct sk_buff *skb, struct net_device *sb_dev)
 }
 EXPORT_SYMBOL(dev_queue_xmit_accel);
 
-int dev_direct_xmit(struct sk_buff *skb, u16 queue_id)
+int __dev_direct_xmit(struct sk_buff *skb, u16 queue_id)
 {
 	struct net_device *dev = skb->dev;
 	struct sk_buff *orig_skb = skb;
@@ -4210,17 +4210,13 @@ int dev_direct_xmit(struct sk_buff *skb, u16 queue_id)
 	dev_xmit_recursion_dec();
 
 	local_bh_enable();
-
-	if (!dev_xmit_complete(ret))
-		kfree_skb(skb);
-
 	return ret;
 drop:
 	atomic_long_inc(&dev->tx_dropped);
 	kfree_skb_list(skb);
 	return NET_XMIT_DROP;
 }
-EXPORT_SYMBOL(dev_direct_xmit);
+EXPORT_SYMBOL(__dev_direct_xmit);
 
 /*************************************************************************
  *			Receiver routines
diff --git a/net/xdp/xdp_umem.c b/net/xdp/xdp_umem.c
index 56d052bc65cb..56a28a686988 100644
--- a/net/xdp/xdp_umem.c
+++ b/net/xdp/xdp_umem.c
@@ -66,18 +66,31 @@ static void xdp_umem_release(struct xdp_umem *umem)
 	kfree(umem);
 }
 
+static void xdp_umem_release_deferred(struct work_struct *work)
+{
+	struct xdp_umem *umem = container_of(work, struct xdp_umem, work);
+
+	xdp_umem_release(umem);
+}
+
 void xdp_get_umem(struct xdp_umem *umem)
 {
 	refcount_inc(&umem->users);
 }
 
-void xdp_put_umem(struct xdp_umem *umem)
+void xdp_put_umem(struct xdp_umem *umem, bool defer_cleanup)
 {
 	if (!umem)
 		return;
 
-	if (refcount_dec_and_test(&umem->users))
-		xdp_umem_release(umem);
+	if (refcount_dec_and_test(&umem->users)) {
+		if (defer_cleanup) {
+			INIT_WORK(&umem->work, xdp_umem_release_deferred);
+			schedule_work(&umem->work);
+		} else {
+			xdp_umem_release(umem);
+		}
+	}
 }
 
 static int xdp_umem_pin_pages(struct xdp_umem *umem, unsigned long address)
diff --git a/net/xdp/xdp_umem.h b/net/xdp/xdp_umem.h
index 181fdda2f2a8..aa9fe2780410 100644
--- a/net/xdp/xdp_umem.h
+++ b/net/xdp/xdp_umem.h
@@ -9,7 +9,7 @@
 #include <net/xdp_sock_drv.h>
 
 void xdp_get_umem(struct xdp_umem *umem);
-void xdp_put_umem(struct xdp_umem *umem);
+void xdp_put_umem(struct xdp_umem *umem, bool defer_cleanup);
 struct xdp_umem *xdp_umem_create(struct xdp_umem_reg *mr);
 
 #endif /* XDP_UMEM_H_ */
diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index cfbec3989a76..b7b039bd9d03 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -411,11 +411,7 @@ static int xsk_generic_xmit(struct sock *sk)
 		skb_shinfo(skb)->destructor_arg = (void *)(long)desc.addr;
 		skb->destructor = xsk_destruct_skb;
 
-		/* Hinder dev_direct_xmit from freeing the packet and
-		 * therefore completing it in the destructor
-		 */
-		refcount_inc(&skb->users);
-		err = dev_direct_xmit(skb, xs->queue_id);
+		err = __dev_direct_xmit(skb, xs->queue_id);
 		if  (err == NETDEV_TX_BUSY) {
 			/* Tell user-space to retry the send */
 			skb->destructor = sock_wfree;
@@ -429,12 +425,10 @@ static int xsk_generic_xmit(struct sock *sk)
 		/* Ignore NET_XMIT_CN as packet might have been sent */
 		if (err == NET_XMIT_DROP) {
 			/* SKB completed but not sent */
-			kfree_skb(skb);
 			err = -EBUSY;
 			goto out;
 		}
 
-		consume_skb(skb);
 		sent_frame = true;
 	}
 
@@ -1147,7 +1141,7 @@ static void xsk_destruct(struct sock *sk)
 		return;
 
 	if (!xp_put_pool(xs->pool))
-		xdp_put_umem(xs->umem);
+		xdp_put_umem(xs->umem, !xs->pool);
 
 	sk_refcnt_debug_dec(sk);
 }
diff --git a/net/xdp/xsk_buff_pool.c b/net/xdp/xsk_buff_pool.c
index 8a3bf4e1318e..9287eddec52c 100644
--- a/net/xdp/xsk_buff_pool.c
+++ b/net/xdp/xsk_buff_pool.c
@@ -185,8 +185,10 @@ err_unreg_xsk:
 err_unreg_pool:
 	if (!force_zc)
 		err = 0; /* fallback to copy mode */
-	if (err)
+	if (err) {
 		xsk_clear_pool_at_qid(netdev, queue_id);
+		dev_put(netdev);
+	}
 	return err;
 }
 
@@ -242,7 +244,7 @@ static void xp_release_deferred(struct work_struct *work)
 		pool->cq = NULL;
 	}
 
-	xdp_put_umem(pool->umem);
+	xdp_put_umem(pool->umem, false);
 	xp_destroy(pool);
 }