[PATCH 4.19 0/4] batman-adv: Fixes for stable/linux-4.19.y

[PATCH 4.19 0/4] batman-adv: Fixes for stable/linux-4.19.y

[Sven Eckelmann]

Hi,

I went through  all changes in batman-adv since v4.19 with a Fixes: line
and checked whether they were backported to the LTS kernels. The ones which
weren't ported and applied to this branch are now part of this patch series.

There are also following three patches included:

* batman-adv: Consider fragmentation for needed_headroom
* batman-adv: Reserve needed_*room for fragments
* batman-adv: Don't always reallocate the fragmentation skb head

which could in some circumstances cause packet loss but which were created
to fix high CPU load/low throughput problems. But I've added them here
anyway because the corresponding VXLAN patches were also added to stable.
And some stable kernels also got these fixes a while back.

Kind regards,
	Sven

Linus Lüssing (1):
  batman-adv: mcast: fix duplicate mcast packets in BLA backbone from
    LAN

Sven Eckelmann (3):
  batman-adv: Consider fragmentation for needed_headroom
  batman-adv: Reserve needed_*room for fragments
  batman-adv: Don't always reallocate the fragmentation skb head

 net/batman-adv/fragmentation.c  | 26 ++++++++++++++++----------
 net/batman-adv/hard-interface.c |  3 +++
 net/batman-adv/multicast.c      | 31 +++++++++++++++++++++++++++++++
 net/batman-adv/multicast.h      | 15 +++++++++++++++
 net/batman-adv/soft-interface.c |  5 ++---
 5 files changed, 67 insertions(+), 13 deletions(-)

-- 
2.30.2

[PATCH 4.19 1/4] batman-adv: mcast: fix duplicate mcast packets in BLA backbone from LAN

[Sven Eckelmann]

From: Linus Lüssing <linus.luessing@c0d3.blue>

commit 3236d215ad38a3f5372e65cd1e0a52cf93d3c6a2 upstream.

Scenario:
* Multicast frame send from a BLA backbone (multiple nodes with
  their bat0 bridged together, with BLA enabled)

Issue:
* BLA backbone nodes receive the frame multiple times on bat0

For multicast frames received via batman-adv broadcast packets the
originator of the broadcast packet is checked before decapsulating and
forwarding the frame to bat0 (batadv_bla_is_backbone_gw()->
batadv_recv_bcast_packet()). If it came from a node which shares the
same BLA backbone with us then it is not forwarded to bat0 to avoid a
loop.

When sending a multicast frame in a non-4-address batman-adv unicast
packet we are currently missing this check - and cannot do so because
the batman-adv unicast packet has no originator address field.

However, we can simply fix this on the sender side by only sending the
multicast frame via unicasts to interested nodes which do not share the
same BLA backbone with us. This also nicely avoids some unnecessary
transmissions on mesh side.

Note that no infinite loop was observed, probably because of dropping
via batadv_interface_tx()->batadv_bla_tx(). However the duplicates still
utterly confuse switches/bridges, ICMPv6 duplicate address detection and
neighbor discovery and therefore leads to long delays before being able
to establish TCP connections, for instance. And it also leads to the Linux
bridge printing messages like:
"br-lan: received packet on eth1 with own address as source address ..."

Fixes: 1d8ab8d3c176 ("batman-adv: Modified forwarding behaviour for multicast packets")
Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
[ bp: 4.19 backport: drop usage in non-existing batadv_mcast_forw*, correct
  fixes line ]
Signed-off-by: Sven Eckelmann <sven@narfation.org>
---
 net/batman-adv/multicast.c      | 31 +++++++++++++++++++++++++++++++
 net/batman-adv/multicast.h      | 15 +++++++++++++++
 net/batman-adv/soft-interface.c |  5 ++---
 3 files changed, 48 insertions(+), 3 deletions(-)

diff --git a/net/batman-adv/multicast.c b/net/batman-adv/multicast.c
index b90fe25d6b0b..9b3311dae2e4 100644
--- a/net/batman-adv/multicast.c
+++ b/net/batman-adv/multicast.c
@@ -62,10 +62,12 @@
 #include <uapi/linux/batadv_packet.h>
 #include <uapi/linux/batman_adv.h>
 
+#include "bridge_loop_avoidance.h"
 #include "hard-interface.h"
 #include "hash.h"
 #include "log.h"
 #include "netlink.h"
+#include "send.h"
 #include "soft-interface.h"
 #include "translation-table.h"
 #include "tvlv.h"
@@ -1024,6 +1026,35 @@ batadv_mcast_forw_mode(struct batadv_priv *bat_priv, struct sk_buff *skb,
 	}
 }
 
+/**
+ * batadv_mcast_forw_send_orig() - send a multicast packet to an originator
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: the multicast packet to send
+ * @vid: the vlan identifier
+ * @orig_node: the originator to send the packet to
+ *
+ * Return: NET_XMIT_DROP in case of error or NET_XMIT_SUCCESS otherwise.
+ */
+int batadv_mcast_forw_send_orig(struct batadv_priv *bat_priv,
+				struct sk_buff *skb,
+				unsigned short vid,
+				struct batadv_orig_node *orig_node)
+{
+	/* Avoid sending multicast-in-unicast packets to other BLA
+	 * gateways - they already got the frame from the LAN side
+	 * we share with them.
+	 * TODO: Refactor to take BLA into account earlier, to avoid
+	 * reducing the mcast_fanout count.
+	 */
+	if (batadv_bla_is_backbone_gw_orig(bat_priv, orig_node->orig, vid)) {
+		dev_kfree_skb(skb);
+		return NET_XMIT_SUCCESS;
+	}
+
+	return batadv_send_skb_unicast(bat_priv, skb, BATADV_UNICAST, 0,
+				       orig_node, vid);
+}
+
 /**
  * batadv_mcast_want_unsnoop_update() - update unsnoop counter and list
  * @bat_priv: the bat priv with all the soft interface information
diff --git a/net/batman-adv/multicast.h b/net/batman-adv/multicast.h
index 3b04ab13f0eb..6f9f3813fc59 100644
--- a/net/batman-adv/multicast.h
+++ b/net/batman-adv/multicast.h
@@ -51,6 +51,11 @@ enum batadv_forw_mode
 batadv_mcast_forw_mode(struct batadv_priv *bat_priv, struct sk_buff *skb,
 		       struct batadv_orig_node **mcast_single_orig);
 
+int batadv_mcast_forw_send_orig(struct batadv_priv *bat_priv,
+				struct sk_buff *skb,
+				unsigned short vid,
+				struct batadv_orig_node *orig_node);
+
 void batadv_mcast_init(struct batadv_priv *bat_priv);
 
 int batadv_mcast_flags_seq_print_text(struct seq_file *seq, void *offset);
@@ -78,6 +83,16 @@ static inline int batadv_mcast_init(struct batadv_priv *bat_priv)
 	return 0;
 }
 
+static inline int
+batadv_mcast_forw_send_orig(struct batadv_priv *bat_priv,
+			    struct sk_buff *skb,
+			    unsigned short vid,
+			    struct batadv_orig_node *orig_node)
+{
+	kfree_skb(skb);
+	return NET_XMIT_DROP;
+}
+
 static inline int
 batadv_mcast_mesh_info_put(struct sk_buff *msg, struct batadv_priv *bat_priv)
 {
diff --git a/net/batman-adv/soft-interface.c b/net/batman-adv/soft-interface.c
index 6ff78080ec7f..1003abb8cc35 100644
--- a/net/batman-adv/soft-interface.c
+++ b/net/batman-adv/soft-interface.c
@@ -367,9 +367,8 @@ static netdev_tx_t batadv_interface_tx(struct sk_buff *skb,
 				goto dropped;
 			ret = batadv_send_skb_via_gw(bat_priv, skb, vid);
 		} else if (mcast_single_orig) {
-			ret = batadv_send_skb_unicast(bat_priv, skb,
-						      BATADV_UNICAST, 0,
-						      mcast_single_orig, vid);
+			ret = batadv_mcast_forw_send_orig(bat_priv, skb, vid,
+							  mcast_single_orig);
 		} else {
 			if (batadv_dat_snoop_outgoing_arp_request(bat_priv,
 								  skb))
-- 
2.30.2

[PATCH 4.19 2/4] batman-adv: Consider fragmentation for needed_headroom

[Sven Eckelmann]

commit 4ca23e2c2074465bff55ea14221175fecdf63c5f upstream.

If a batman-adv packets has to be fragmented, then the original batman-adv
packet header is not stripped away. Instead, only a new header is added in
front of the packet after it was split.

This size must be considered to avoid cost intensive reallocations during
the transmission through the various device layers.

Fixes: 7bca68c7844b ("batman-adv: Add lower layer needed_(head|tail)room to own ones")
Reported-by: Linus Lüssing <linus.luessing@c0d3.blue>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
---
 net/batman-adv/hard-interface.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/batman-adv/hard-interface.c b/net/batman-adv/hard-interface.c
index c4e0435c952d..fc732b78daf7 100644
--- a/net/batman-adv/hard-interface.c
+++ b/net/batman-adv/hard-interface.c
@@ -565,6 +565,9 @@ static void batadv_hardif_recalc_extra_skbroom(struct net_device *soft_iface)
 	needed_headroom = lower_headroom + (lower_header_len - ETH_HLEN);
 	needed_headroom += batadv_max_header_len();
 
+	/* fragmentation headers don't strip the unicast/... header */
+	needed_headroom += sizeof(struct batadv_frag_packet);
+
 	soft_iface->needed_headroom = needed_headroom;
 	soft_iface->needed_tailroom = lower_tailroom;
 }
-- 
2.30.2

[PATCH 4.19 3/4] batman-adv: Reserve needed_*room for fragments

[Sven Eckelmann]

commit c5cbfc87558168ef4c3c27ce36eba6b83391db19 upstream.

The batadv net_device is trying to propagate the needed_headroom and
needed_tailroom from the lower devices. This is needed to avoid cost
intensive reallocations using pskb_expand_head during the transmission.

But the fragmentation code split the skb's without adding extra room at the
end/beginning of the various fragments. This reduced the performance of
transmissions over complex scenarios (batadv on vxlan on wireguard) because
the lower devices had to perform the reallocations at least once.

Fixes: ee75ed88879a ("batman-adv: Fragment and send skbs larger than mtu")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
[ bp: 4.19 backported: adjust context. ]
Signed-off-by: Sven Eckelmann <sven@narfation.org>
---
 net/batman-adv/fragmentation.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/net/batman-adv/fragmentation.c b/net/batman-adv/fragmentation.c
index 5b71a289d04f..2dbd870221e4 100644
--- a/net/batman-adv/fragmentation.c
+++ b/net/batman-adv/fragmentation.c
@@ -403,6 +403,7 @@ bool batadv_frag_skb_fwd(struct sk_buff *skb,
 
 /**
  * batadv_frag_create() - create a fragment from skb
+ * @net_dev: outgoing device for fragment
  * @skb: skb to create fragment from
  * @frag_head: header to use in new fragment
  * @fragment_size: size of new fragment
@@ -413,22 +414,25 @@ bool batadv_frag_skb_fwd(struct sk_buff *skb,
  *
  * Return: the new fragment, NULL on error.
  */
-static struct sk_buff *batadv_frag_create(struct sk_buff *skb,
+static struct sk_buff *batadv_frag_create(struct net_device *net_dev,
+					  struct sk_buff *skb,
 					  struct batadv_frag_packet *frag_head,
 					  unsigned int fragment_size)
 {
+	unsigned int ll_reserved = LL_RESERVED_SPACE(net_dev);
+	unsigned int tailroom = net_dev->needed_tailroom;
 	struct sk_buff *skb_fragment;
 	unsigned int header_size = sizeof(*frag_head);
 	unsigned int mtu = fragment_size + header_size;
 
-	skb_fragment = netdev_alloc_skb(NULL, mtu + ETH_HLEN);
+	skb_fragment = dev_alloc_skb(ll_reserved + mtu + tailroom);
 	if (!skb_fragment)
 		goto err;
 
 	skb_fragment->priority = skb->priority;
 
 	/* Eat the last mtu-bytes of the skb */
-	skb_reserve(skb_fragment, header_size + ETH_HLEN);
+	skb_reserve(skb_fragment, ll_reserved + header_size);
 	skb_split(skb, skb_fragment, skb->len - fragment_size);
 
 	/* Add the header */
@@ -451,11 +455,12 @@ int batadv_frag_send_packet(struct sk_buff *skb,
 			    struct batadv_orig_node *orig_node,
 			    struct batadv_neigh_node *neigh_node)
 {
+	struct net_device *net_dev = neigh_node->if_incoming->net_dev;
 	struct batadv_priv *bat_priv;
 	struct batadv_hard_iface *primary_if = NULL;
 	struct batadv_frag_packet frag_header;
 	struct sk_buff *skb_fragment;
-	unsigned int mtu = neigh_node->if_incoming->net_dev->mtu;
+	unsigned int mtu = net_dev->mtu;
 	unsigned int header_size = sizeof(frag_header);
 	unsigned int max_fragment_size, num_fragments;
 	int ret;
@@ -515,7 +520,7 @@ int batadv_frag_send_packet(struct sk_buff *skb,
 			goto put_primary_if;
 		}
 
-		skb_fragment = batadv_frag_create(skb, &frag_header,
+		skb_fragment = batadv_frag_create(net_dev, skb, &frag_header,
 						  max_fragment_size);
 		if (!skb_fragment) {
 			ret = -ENOMEM;
-- 
2.30.2

[PATCH 4.19 4/4] batman-adv: Don't always reallocate the fragmentation skb head

[Sven Eckelmann]

commit 992b03b88e36254e26e9a4977ab948683e21bd9f upstream.

When a packet is fragmented by batman-adv, the original batman-adv header
is not modified. Only a new fragmentation is inserted between the original
one and the ethernet header. The code must therefore make sure that it has
a writable region of this size in the skbuff head.

But it is not useful to always reallocate the skbuff by this size even when
there would be more than enough headroom still in the skb. The reallocation
is just to costly during in this codepath.

Fixes: ee75ed88879a ("batman-adv: Fragment and send skbs larger than mtu")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
---
 net/batman-adv/fragmentation.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/net/batman-adv/fragmentation.c b/net/batman-adv/fragmentation.c
index 2dbd870221e4..cc062b69fc8d 100644
--- a/net/batman-adv/fragmentation.c
+++ b/net/batman-adv/fragmentation.c
@@ -539,13 +539,14 @@ int batadv_frag_send_packet(struct sk_buff *skb,
 		frag_header.no++;
 	}
 
-	/* Make room for the fragment header. */
-	if (batadv_skb_head_push(skb, header_size) < 0 ||
-	    pskb_expand_head(skb, header_size + ETH_HLEN, 0, GFP_ATOMIC) < 0) {
-		ret = -ENOMEM;
+	/* make sure that there is at least enough head for the fragmentation
+	 * and ethernet headers
+	 */
+	ret = skb_cow_head(skb, ETH_HLEN + header_size);
+	if (ret < 0)
 		goto put_primary_if;
-	}
 
+	skb_push(skb, header_size);
 	memcpy(skb->data, &frag_header, header_size);
 
 	/* Send the last fragment */
-- 
2.30.2