net: introduce skb_crc32c_csum_help
skb_crc32c_csum_help is like skb_checksum_help, but it is designed for
checksumming SCTP packets using crc32c (see RFC3309), provided that
libcrc32c.ko has been loaded before. In case libcrc32c is not loaded,
invoking skb_crc32c_csum_help on a skb results in one the following
printouts:
warn_crc32c_csum_update: attempt to compute crc32c without libcrc32c.ko
warn_crc32c_csum_combine: attempt to compute crc32c without libcrc32c.ko
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/dev.c b/net/core/dev.c
index acd594c..8356d5f 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -143,6 +143,7 @@
#include <linux/hrtimer.h>
#include <linux/netfilter_ingress.h>
#include <linux/crash_dump.h>
+#include <linux/sctp.h>
#include "net-sysfs.h"
@@ -2612,6 +2613,46 @@ int skb_checksum_help(struct sk_buff *skb)
}
EXPORT_SYMBOL(skb_checksum_help);
+int skb_crc32c_csum_help(struct sk_buff *skb)
+{
+ __le32 crc32c_csum;
+ int ret = 0, offset, start;
+
+ if (skb->ip_summed != CHECKSUM_PARTIAL)
+ goto out;
+
+ if (unlikely(skb_is_gso(skb)))
+ goto out;
+
+ /* Before computing a checksum, we should make sure no frag could
+ * be modified by an external entity : checksum could be wrong.
+ */
+ if (unlikely(skb_has_shared_frag(skb))) {
+ ret = __skb_linearize(skb);
+ if (ret)
+ goto out;
+ }
+ start = skb_checksum_start_offset(skb);
+ offset = start + offsetof(struct sctphdr, checksum);
+ if (WARN_ON_ONCE(offset >= skb_headlen(skb))) {
+ ret = -EINVAL;
+ goto out;
+ }
+ if (skb_cloned(skb) &&
+ !skb_clone_writable(skb, offset + sizeof(__le32))) {
+ ret = pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
+ if (ret)
+ goto out;
+ }
+ crc32c_csum = cpu_to_le32(~__skb_checksum(skb, start,
+ skb->len - start, ~(__u32)0,
+ crc32c_csum_stub));
+ *(__le32 *)(skb->data + offset) = crc32c_csum;
+ skb->ip_summed = CHECKSUM_NONE;
+out:
+ return ret;
+}
+
__be16 skb_network_protocol(struct sk_buff *skb, int *depth)
{
__be16 type = skb->protocol;
