/* 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;
}
static void gre_fb_xmit(struct sk_buff *skb, struct net_device *dev,
__be16 proto)
{
struct ip_tunnel_info *tun_info;
const struct ip_tunnel_key *key;
struct rtable *rt = NULL;
struct flowi4 fl;
int min_headroom;
int tunnel_hlen;
__be16 df, flags;
bool use_cache;
int err;
tun_info = skb_tunnel_info(skb);
if (unlikely(!tun_info || !(tun_info->mode & IP_TUNNEL_INFO_TX) ||
ip_tunnel_info_af(tun_info) != AF_INET))
goto err_free_skb;
key = &tun_info->key;
use_cache = ip_tunnel_dst_cache_usable(skb, tun_info);
if (use_cache)
rt = dst_cache_get_ip4(&tun_info->dst_cache, &fl.saddr);
if (!rt) {
rt = gre_get_rt(skb, dev, &fl, key);
if (IS_ERR(rt))
goto err_free_skb;
if (use_cache)
dst_cache_set_ip4(&tun_info->dst_cache, &rt->dst,
fl.saddr);
}
tunnel_hlen = gre_calc_hlen(key->tun_flags);
min_headroom = LL_RESERVED_SPACE(rt->dst.dev) + rt->dst.header_len
+ tunnel_hlen + sizeof(struct iphdr);
if (skb_headroom(skb) < min_headroom || skb_header_cloned(skb)) {
int head_delta = SKB_DATA_ALIGN(min_headroom -
skb_headroom(skb) +
16);
err = pskb_expand_head(skb, max_t(int, head_delta, 0),
0, GFP_ATOMIC);
if (unlikely(err))
goto err_free_rt;
}
/* 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, int nhs)
{
const struct gre_base_hdr *greh;
__be32 *options;
int hdr_len;
if (unlikely(!pskb_may_pull(skb, nhs + sizeof(struct gre_base_hdr))))
return -EINVAL;
greh = (struct gre_base_hdr *)(skb->data + nhs);
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, nhs + hdr_len))
return -EINVAL;
greh = (struct gre_base_hdr *)(skb->data + nhs);
tpi->proto = greh->protocol;
options = (__be32 *)(greh + 1);
if (greh->flags & GRE_CSUM) {
if (!skb_checksum_simple_validate(skb)) {
skb_checksum_try_convert(skb, IPPROTO_GRE, 0,
null_compute_pseudo);
} else if (csum_err) {
*csum_err = true;
return -EINVAL;
}
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;
}
tpi->hdr_len = hdr_len;
/* ERSPAN ver 1 and 2 protocol sets GRE key field
* to 0 and sets the configured key in the
* inner erspan header field
*/
if (greh->protocol == htons(ETH_P_ERSPAN) ||
greh->protocol == htons(ETH_P_ERSPAN2)) {
struct erspan_base_hdr *ershdr;
if (!pskb_may_pull(skb, nhs + hdr_len + sizeof(*ershdr)))
return -EINVAL;
ershdr = (struct erspan_base_hdr *)options;
tpi->key = cpu_to_be32(get_session_id(ershdr));
}
return hdr_len;
}
