[PATCH 3.8 159/166] vlan: Fix header ops passthru when doing TX VLAN offload.

Kamal Mostafa
2014-01-15T21:52:53Z

From: "David S. Miller" <davem@davemloft.net>

[ Upstream commit 2205369a314e12fcec4781cc73ac9c08fc2b47de ]

When the vlan code detects that the real device can do TX VLAN offloads
in hardware, it tries to arrange for the real device's header_ops to
be invoked directly.

But it does so illegally, by simply hooking the real device's
header_ops up to the VLAN device.

This doesn't work because we will end up invoking a set of header_ops
routines which expect a device type which matches the real device, but
will see a VLAN device instead.

Fix this by providing a pass-thru set of header_ops which will arrange
to pass the proper real device instead.

To facilitate this add a dev_rebuild_header(). There are
implementations which provide a ->cache and ->create but not a
->rebuild (f.e. PLIP). So we need a helper function just like
dev_hard_header() to avoid crashes.

Use this helper in the one existing place where the
header_ops->rebuild was being invoked, the neighbour code.

With lots of help from Florian Westphal.

Signed-off-by: David S. Miller <davem@davemloft.net>
[ kamal: backport to 3.8 (context) ]
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
include/linux/netdevice.h | 9 +++++++++
net/8021q/vlan_dev.c | 19 ++++++++++++++++++-
net/core/neighbour.c | 2 +-
3 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 0e182f9..0cabad8 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1747,6 +1747,15 @@ static inline int dev_parse_header(const struct sk_buff *skb,
return dev->header_ops->parse(skb, haddr);
}

+static inline int dev_rebuild_header(struct sk_buff *skb)
+{
+ const struct net_device *dev = skb->dev;
+
+ if (!dev->header_ops || !dev->header_ops->rebuild)
+ return 0;
+ return dev->header_ops->rebuild(skb);
+}
+
typedef int gifconf_func_t(struct net_device * dev, char __user * bufptr, int len);
extern int register_gifconf(unsigned int family, gifconf_func_t * gifconf);
static inline int unregister_gifconf(unsigned int family)
diff --git a/net/8021q/vlan_dev.c b/net/8021q/vlan_dev.c
index 4c14e8a..bd0ba90 100644
--- a/net/8021q/vlan_dev.c
+++ b/net/8021q/vlan_dev.c
@@ -538,6 +538,23 @@ static const struct header_ops vlan_header_ops = {
.parse = eth_header_parse,
};

+static int vlan_passthru_hard_header(struct sk_buff *skb, struct net_device *dev,
+ unsigned short type,
+ const void *daddr, const void *saddr,
+ unsigned int len)
+{
+ struct vlan_dev_priv *vlan = vlan_dev_priv(dev);
+ struct net_device *real_dev = vlan->real_dev;
+
+ return dev_hard_header(skb, real_dev, type, daddr, saddr, len);
+}
+
+static const struct header_ops vlan_passthru_header_ops = {
+ .create = vlan_passthru_hard_header,
+ .rebuild = dev_rebuild_header,
+ .parse = eth_header_parse,
+};
+
static struct device_type vlan_type = {
.name = "vlan",
};
@@ -581,7 +598,7 @@ static int vlan_dev_init(struct net_device *dev)

dev->needed_headroom = real_dev->needed_headroom;
if (real_dev->features & NETIF_F_HW_VLAN_TX) {
- dev->header_ops = real_dev->header_ops;
+ dev->header_ops = &vlan_passthru_header_ops;
dev->hard_header_len = real_dev->hard_header_len;
} else {
dev->header_ops = &vlan_header_ops;
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index e7f5bff..4aa92e3 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -1286,7 +1286,7 @@ int neigh_compat_output(struct neighbour *neigh, struct sk_buff *skb)

if (dev_hard_header(skb, dev, ntohs(skb->protocol), NULL, NULL,
skb->len) < 0 &&
- dev->header_ops->rebuild(skb))
+ dev_rebuild_header(skb))
return 0;

return dev_queue_xmit(skb);
--
1.8.3.2