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Diffstat (limited to 'net/ipv4/gre_demux.c')
-rw-r--r--net/ipv4/gre_demux.c61
1 files changed, 61 insertions, 0 deletions
diff --git a/net/ipv4/gre_demux.c b/net/ipv4/gre_demux.c
index d9c552a721fc..4c39f4fd332a 100644
--- a/net/ipv4/gre_demux.c
+++ b/net/ipv4/gre_demux.c
@@ -60,6 +60,67 @@ int gre_del_protocol(const struct gre_protocol *proto, u8 version)
}
EXPORT_SYMBOL_GPL(gre_del_protocol);
+/* Fills in tpi and returns header length to be pulled. */
+int gre_parse_header(struct sk_buff *skb, struct tnl_ptk_info *tpi,
+ bool *csum_err, __be16 proto)
+{
+ const struct gre_base_hdr *greh;
+ __be32 *options;
+ int hdr_len;
+
+ if (unlikely(!pskb_may_pull(skb, sizeof(struct gre_base_hdr))))
+ return -EINVAL;
+
+ greh = (struct gre_base_hdr *)skb_transport_header(skb);
+ if (unlikely(greh->flags & (GRE_VERSION | GRE_ROUTING)))
+ return -EINVAL;
+
+ tpi->flags = gre_flags_to_tnl_flags(greh->flags);
+ hdr_len = gre_calc_hlen(tpi->flags);
+
+ if (!pskb_may_pull(skb, hdr_len))
+ return -EINVAL;
+
+ greh = (struct gre_base_hdr *)skb_transport_header(skb);
+ tpi->proto = greh->protocol;
+
+ options = (__be32 *)(greh + 1);
+ if (greh->flags & GRE_CSUM) {
+ if (skb_checksum_simple_validate(skb)) {
+ *csum_err = true;
+ return -EINVAL;
+ }
+
+ skb_checksum_try_convert(skb, IPPROTO_GRE, 0,
+ null_compute_pseudo);
+ options++;
+ }
+
+ if (greh->flags & GRE_KEY) {
+ tpi->key = *options;
+ options++;
+ } else {
+ tpi->key = 0;
+ }
+ if (unlikely(greh->flags & GRE_SEQ)) {
+ tpi->seq = *options;
+ options++;
+ } else {
+ tpi->seq = 0;
+ }
+ /* WCCP version 1 and 2 protocol decoding.
+ * - Change protocol to IPv4/IPv6
+ * - When dealing with WCCPv2, Skip extra 4 bytes in GRE header
+ */
+ if (greh->flags == 0 && tpi->proto == htons(ETH_P_WCCP)) {
+ tpi->proto = proto;
+ if ((*(u8 *)options & 0xF0) != 0x40)
+ hdr_len += 4;
+ }
+ return hdr_len;
+}
+EXPORT_SYMBOL(gre_parse_header);
+
static int gre_rcv(struct sk_buff *skb)
{
const struct gre_protocol *proto;