[NET]: Detect hardware rx checksum faults correctly
Here is the patch that introduces the generic skb_checksum_complete
which also checks for hardware RX checksum faults. If that happens,
it'll call netdev_rx_csum_fault which currently prints out a stack
trace with the device name. In future it can turn off RX checksum.
I've converted every spot under net/ that does RX checksum checks to
use skb_checksum_complete or __skb_checksum_complete with the
exceptions of:
* Those places where checksums are done bit by bit. These will call
netdev_rx_csum_fault directly.
* The following have not been completely checked/converted:
ipmr
ip_vs
netfilter
dccp
This patch is based on patches and suggestions from Stephen Hemminger
and David S. Miller.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/datagram.c b/net/core/datagram.c
index d219435..1bcfef5 100644
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -350,6 +350,20 @@
return -EFAULT;
}
+unsigned int __skb_checksum_complete(struct sk_buff *skb)
+{
+ unsigned int sum;
+
+ sum = (u16)csum_fold(skb_checksum(skb, 0, skb->len, skb->csum));
+ if (likely(!sum)) {
+ if (unlikely(skb->ip_summed == CHECKSUM_HW))
+ netdev_rx_csum_fault(skb->dev);
+ skb->ip_summed = CHECKSUM_UNNECESSARY;
+ }
+ return sum;
+}
+EXPORT_SYMBOL(__skb_checksum_complete);
+
/**
* skb_copy_and_csum_datagram_iovec - Copy and checkum skb to user iovec.
* @skb: skbuff
@@ -363,7 +377,7 @@
* -EFAULT - fault during copy. Beware, in this case iovec
* can be modified!
*/
-int skb_copy_and_csum_datagram_iovec(const struct sk_buff *skb,
+int skb_copy_and_csum_datagram_iovec(struct sk_buff *skb,
int hlen, struct iovec *iov)
{
unsigned int csum;
@@ -376,8 +390,7 @@
iov++;
if (iov->iov_len < chunk) {
- if ((unsigned short)csum_fold(skb_checksum(skb, 0, chunk + hlen,
- skb->csum)))
+ if (__skb_checksum_complete(skb))
goto csum_error;
if (skb_copy_datagram_iovec(skb, hlen, iov, chunk))
goto fault;
@@ -388,6 +401,8 @@
goto fault;
if ((unsigned short)csum_fold(csum))
goto csum_error;
+ if (unlikely(skb->ip_summed == CHECKSUM_HW))
+ netdev_rx_csum_fault(skb->dev);
iov->iov_len -= chunk;
iov->iov_base += chunk;
}
diff --git a/net/core/dev.c b/net/core/dev.c
index 8d15415..0b48e29 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1108,6 +1108,18 @@
return ret;
}
+/* Take action when hardware reception checksum errors are detected. */
+#ifdef CONFIG_BUG
+void netdev_rx_csum_fault(struct net_device *dev)
+{
+ if (net_ratelimit()) {
+ printk(KERN_ERR "%s: hw csum failure.\n", dev->name);
+ dump_stack();
+ }
+}
+EXPORT_SYMBOL(netdev_rx_csum_fault);
+#endif
+
#ifdef CONFIG_HIGHMEM
/* Actually, we should eliminate this check as soon as we know, that:
* 1. IOMMU is present and allows to map all the memory.
diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index 802fe11..49424a4 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -101,16 +101,20 @@
static int checksum_udp(struct sk_buff *skb, struct udphdr *uh,
unsigned short ulen, u32 saddr, u32 daddr)
{
- if (uh->check == 0)
+ unsigned int psum;
+
+ if (uh->check == 0 || skb->ip_summed == CHECKSUM_UNNECESSARY)
return 0;
- if (skb->ip_summed == CHECKSUM_HW)
- return csum_tcpudp_magic(
- saddr, daddr, ulen, IPPROTO_UDP, skb->csum);
+ psum = csum_tcpudp_nofold(saddr, daddr, ulen, IPPROTO_UDP, 0);
- skb->csum = csum_tcpudp_nofold(saddr, daddr, ulen, IPPROTO_UDP, 0);
+ if (skb->ip_summed == CHECKSUM_HW &&
+ !(u16)csum_fold(csum_add(psum, skb->csum)))
+ return 0;
- return csum_fold(skb_checksum(skb, 0, skb->len, skb->csum));
+ skb->csum = psum;
+
+ return __skb_checksum_complete(skb);
}
/*
@@ -489,7 +493,7 @@
if (ulen != len)
goto out;
- if (checksum_udp(skb, uh, ulen, iph->saddr, iph->daddr) < 0)
+ if (checksum_udp(skb, uh, ulen, iph->saddr, iph->daddr))
goto out;
if (np->local_ip && np->local_ip != ntohl(iph->daddr))
goto out;