1 files changed, 20 insertions, 2 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index efe7cec111fa..fd30cb545c45 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -268,6 +268,7 @@ struct header_ops {
         void    (*cache_update)(struct hh_cache *hh,
                                 const struct net_device *dev,
                                 const unsigned char *haddr);
+        bool    (*validate)(const char *ll_header, unsigned int len);
 };
 
 /* These flag bits are private to the generic network queueing
@@ -1459,8 +1460,7 @@ enum netdev_priv_flags {
  *      @dma:           DMA channel
  *      @mtu:           Interface MTU value
  *      @type:          Interface hardware type
- *      @hard_header_len: Hardware header length, which means that this is the
- *                        minimum size of a packet.
+ *      @hard_header_len: Maximum hardware header length.
  *
  *      @needed_headroom: Extra headroom the hardware may need, but not in all
  *                        cases can this be guaranteed
@@ -2687,6 +2687,24 @@ static inline int dev_parse_header(const struct sk_buff *skb,
         return dev->header_ops->parse(skb, haddr);
 }
 
+/* ll_header must have at least hard_header_len allocated */
+static inline bool dev_validate_header(const struct net_device *dev,
+                                       char *ll_header, int len)
+{
+        if (likely(len >= dev->hard_header_len))
+                return true;
+
+        if (capable(CAP_SYS_RAWIO)) {
+                memset(ll_header + len, 0, dev->hard_header_len - len);
+                return true;
+        }
+
+        if (dev->header_ops && dev->header_ops->validate)
+                return dev->header_ops->validate(ll_header, len);
+
+        return false;
+}
+
 typedef int gifconf_func_t(struct net_device * dev, char __user * bufptr, int len);
 int register_gifconf(unsigned int family, gifconf_func_t *gifconf);
 static inline int unregister_gifconf(unsigned int family)