mirror of https://github.com/hak5/openwrt.git
103 lines
3.2 KiB
Diff
103 lines
3.2 KiB
Diff
--- a/include/linux/skbuff.h
|
|
+++ b/include/linux/skbuff.h
|
|
@@ -912,6 +912,49 @@ static inline void skb_reserve(struct sk
|
|
skb->tail+=len;
|
|
}
|
|
|
|
+/*
|
|
+ * CPUs often take a performance hit when accessing unaligned memory
|
|
+ * locations. The actual performance hit varies, it can be small if the
|
|
+ * hardware handles it or large if we have to take an exception and fix it
|
|
+ * in software.
|
|
+ *
|
|
+ * Since an ethernet header is 14 bytes network drivers often end up with
|
|
+ * the IP header at an unaligned offset. The IP header can be aligned by
|
|
+ * shifting the start of the packet by 2 bytes. Drivers should do this
|
|
+ * with:
|
|
+ *
|
|
+ * skb_reserve(NET_IP_ALIGN);
|
|
+ *
|
|
+ * The downside to this alignment of the IP header is that the DMA is now
|
|
+ * unaligned. On some architectures the cost of an unaligned DMA is high
|
|
+ * and this cost outweighs the gains made by aligning the IP header.
|
|
+ *
|
|
+ * Since this trade off varies between architectures, we allow NET_IP_ALIGN
|
|
+ * to be overridden.
|
|
+ */
|
|
+#ifndef NET_IP_ALIGN
|
|
+#define NET_IP_ALIGN 2
|
|
+#endif
|
|
+
|
|
+/*
|
|
+ * The networking layer reserves some headroom in skb data (via
|
|
+ * dev_alloc_skb). This is used to avoid having to reallocate skb data when
|
|
+ * the header has to grow. In the default case, if the header has to grow
|
|
+ * 16 bytes or less we avoid the reallocation.
|
|
+ *
|
|
+ * Unfortunately this headroom changes the DMA alignment of the resulting
|
|
+ * network packet. As for NET_IP_ALIGN, this unaligned DMA is expensive
|
|
+ * on some architectures. An architecture can override this value,
|
|
+ * perhaps setting it to a cacheline in size (since that will maintain
|
|
+ * cacheline alignment of the DMA). It must be a power of 2.
|
|
+ *
|
|
+ * Various parts of the networking layer expect at least 16 bytes of
|
|
+ * headroom, you should not reduce this.
|
|
+ */
|
|
+#ifndef NET_SKB_PAD
|
|
+#define NET_SKB_PAD 16
|
|
+#endif
|
|
+
|
|
extern int ___pskb_trim(struct sk_buff *skb, unsigned int len, int realloc);
|
|
|
|
static inline void __skb_trim(struct sk_buff *skb, unsigned int len)
|
|
--- a/drivers/net/tun.c
|
|
+++ b/drivers/net/tun.c
|
|
@@ -185,22 +185,31 @@ static __inline__ ssize_t tun_get_user(s
|
|
{
|
|
struct tun_pi pi = { 0, __constant_htons(ETH_P_IP) };
|
|
struct sk_buff *skb;
|
|
- size_t len = count;
|
|
+ size_t len = count, align = 0;
|
|
|
|
if (!(tun->flags & TUN_NO_PI)) {
|
|
if ((len -= sizeof(pi)) > count)
|
|
return -EINVAL;
|
|
|
|
- memcpy_fromiovec((void *)&pi, iv, sizeof(pi));
|
|
+ if(memcpy_fromiovec((void *)&pi, iv, sizeof(pi)))
|
|
+ return -EFAULT;
|
|
}
|
|
-
|
|
- if (!(skb = alloc_skb(len + 2, GFP_KERNEL))) {
|
|
+
|
|
+ if ((tun->flags & TUN_TYPE_MASK) == TUN_TAP_DEV)
|
|
+ align = NET_IP_ALIGN;
|
|
+
|
|
+ if (!(skb = alloc_skb(len + align, GFP_KERNEL))) {
|
|
tun->stats.rx_dropped++;
|
|
return -ENOMEM;
|
|
}
|
|
|
|
- skb_reserve(skb, 2);
|
|
- memcpy_fromiovec(skb_put(skb, len), iv, len);
|
|
+ if (align)
|
|
+ skb_reserve(skb, align);
|
|
+ if (memcpy_fromiovec(skb_put(skb, len), iv, len)) {
|
|
+ tun->stats.rx_dropped++;
|
|
+ kfree_skb(skb);
|
|
+ return -EFAULT;
|
|
+ }
|
|
|
|
skb->dev = &tun->dev;
|
|
switch (tun->flags & TUN_TYPE_MASK) {
|
|
@@ -271,7 +280,8 @@ static __inline__ ssize_t tun_put_user(s
|
|
pi.flags |= TUN_PKT_STRIP;
|
|
}
|
|
|
|
- memcpy_toiovec(iv, (void *) &pi, sizeof(pi));
|
|
+ if(memcpy_toiovec(iv, (void *) &pi, sizeof(pi)))
|
|
+ return -EFAULT;
|
|
total += sizeof(pi);
|
|
}
|
|
|