// SPDX-License-Identifier: GPL-2.0-or-later
#include <linux/skbuff.h>
#include <linux/sctp.h>
#include <net/gso.h>
#include <net/gro.h>
/**
* skb_eth_gso_segment - segmentation handler for ethernet protocols.
* @skb: buffer to segment
* @features: features for the output path (see dev->features)
* @type: Ethernet Protocol ID
*/
struct sk_buff *skb_eth_gso_segment(struct sk_buff *skb,
netdev_features_t features, __be16 type)
{
struct sk_buff *segs = ERR_PTR(-EPROTONOSUPPORT);
struct packet_offload *ptype;
rcu_read_lock();
list_for_each_entry_rcu(ptype, &net_hotdata.offload_base, list) {
if (ptype->type == type && ptype->callbacks.gso_segment) {
segs = ptype->callbacks.gso_segment(skb, features);
break;
}
}
rcu_read_unlock();
return segs;
}
EXPORT_SYMBOL(skb_eth_gso_segment);
/**
* skb_mac_gso_segment - mac layer segmentation handler.
* @skb: buffer to segment
* @features: features for the output path (see dev->features)
*/
struct sk_buff *skb_mac_gso_segment(struct sk_buff *skb,
netdev_features_t features)
{
struct sk_buff *segs = ERR_PTR(-EPROTONOSUPPORT);
struct packet_offload *ptype;
int vlan_depth = skb->mac_len;
__be16 type = skb_network_protocol(skb, &vlan_depth);
if (unlikely(!type))
return ERR_PTR(-EINVAL);
__skb_pull(skb, vlan_depth);
rcu_read_lock();
list_for_each_entry_rcu(ptype, &net_hotdata.offload_base, list) {
if (ptype->type == type && ptype->callbacks.gso_segment) {
segs = ptype->callbacks.gso_segment(skb, features);
break;
}
}
rcu_read_unlock();
__skb_push(skb, skb->data - skb_mac_header(skb));
return segs;
}
EXPORT_SYMBOL(skb_mac_gso_segment);
/* openvswitch calls this on rx path, so we need a different check.
*/
static bool skb_needs_check(const struct sk_buff *skb, bool tx_path)
{
if (tx_path)
return skb->ip_summed != CHECKSUM_PARTIAL &&
skb->ip_summed != CHECKSUM_UNNECESSARY;
return skb->ip_summed == CHECKSUM_NONE;
}
/**
* __skb_gso_segment - Perform segmentation on skb.
* @skb: buffer to segment
* @features: features for the output path (see dev->features)
* @tx_path: whether it is called in TX path
*
* This function segments the given skb and returns a list of segments.
*
* It may return NULL if the skb requires no segmentation. This is
* only possible when GSO is used for verifying header integrity.
*
* Segmentation preserves SKB_GSO_CB_OFFSET bytes of previous skb cb.
*/
struct sk_buff *__skb_gso_segment(struct sk_buff *skb,
netdev_features_t features, bool tx_path)
{
struct sk_buff *segs;
if (unlikely(skb_needs_check(skb, tx_path))) {
int err;
/* We're going to init ->check field in TCP or UDP header */
err = skb_cow_head(skb, 0);
if (err < 0)
return ERR_PTR(err);
}
/* Only report GSO partial support if it will enable us to
* support segmentation on this frame without needing additional
* work.
*/
if (features & NETIF_F_GSO_PARTIAL) {
netdev_features_t partial_features = NETIF_F_GSO_ROBUST;
struct net_device *dev = skb->dev;
partial_features |= dev->features & dev->gso_partial_features;
if (!skb_gso_ok(skb, features | partial_features))
features &= ~NETIF_F_GSO_PARTIAL;
}
BUILD_BUG_ON(SKB_GSO_CB_OFFSET +
sizeof(*SKB_GSO_CB(skb)) > sizeof(skb->cb));
SKB_GSO_CB(skb)->mac_offset = skb_headroom(skb);
SKB_GSO_CB(skb)->encap_level = 0;
skb_reset_mac_header(skb);
skb_reset_mac_len(skb);
segs = skb_mac_gso_segment(skb, features);
if (segs != skb && unlikely(skb_needs_check(skb, tx_path) && !IS_ERR(segs)))
skb_warn_bad_offload(skb);
return segs;
}
EXPORT_SYMBOL(__skb_gso_segment);
/**
* skb_gso_transport_seglen - Return length of individual segments of a gso packet
*
* @skb: GSO skb
*
* skb_gso_transport_seglen is used to determine the real size of the
* individual segments, including Layer4 headers (TCP/UDP).
*
* The MAC/L2 or network (IP, IPv6) headers are not accounted for.
*/
static unsigned int skb_gso_transport_seglen(const struct sk_buff *skb)
{
const struct skb_shared_info *shinfo = skb_shinfo(skb);
unsigned int thlen = 0;
if (skb->encapsulation) {
thlen = skb_inner_transport_header(skb) -
skb_transport_header(skb);
if (likely(shinfo->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6)))
thlen += inner_tcp_hdrlen(skb);
} else if (likely(shinfo->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6))) {
thlen = tcp_hdrlen(skb);
} else if (unlikely(skb_is_gso_sctp(skb))) {
thlen = sizeof(struct sctphdr);
} else if (shinfo->gso_type & SKB_GSO_UDP_L4) {
thlen = sizeof(struct udphdr);
}
/* UFO sets gso_size to the size of the fragmentation
* payload, i.e. the size of the L4 (UDP) header is already
* accounted for.
*/
return thlen + shinfo->gso_size;
}
/**
* skb_gso_network_seglen - Return length of individual segments of a gso packet
*
* @skb: GSO skb
*
* skb_gso_network_seglen is used to determine the real size of the
* individual segments, including Layer3 (IP, IPv6) and L4 headers (TCP/UDP).
*
* The MAC/L2 header is not accounted for.
*/
static unsigned int skb_gso_network_seglen(const struct sk_buff *skb)
{
unsigned int hdr_len = skb_transport_header(skb) -
skb_network_header(skb);
return hdr_len + skb_gso_transport_seglen(skb);
}
/**
* skb_gso_mac_seglen - Return length of individual segments of a gso packet
*
* @skb: GSO skb
*
* skb_gso_mac_seglen is used to determine the real size of the
* individual segments, including MAC/L2, Layer3 (IP, IPv6) and L4
* headers (TCP/UDP).
*/
static unsigned int skb_gso_mac_seglen(const struct sk_buff *skb)
{
unsigned int hdr_len = skb_transport_header(skb) - skb_mac_header(skb);
return hdr_len + skb_gso_transport_seglen(skb);
}
/**
* skb_gso_size_check - check the skb size, considering GSO_BY_FRAGS
*
* There are a couple of instances where we have a GSO skb, and we
* want to determine what size it would be after it is segmented.
*
* We might want to check:
* - L3+L4+payload size (e.g. IP forwarding)
* - L2+L3+L4+payload size (e.g. sanity check before passing to driver)
*
* This is a helper to do that correctly considering GSO_BY_FRAGS.
*
* @skb: GSO skb
*
* @seg_len: The segmented length (from skb_gso_*_seglen). In the
* GSO_BY_FRAGS case this will be [header sizes + GSO_BY_FRAGS].
*
* @max_len: The maximum permissible length.
*
* Returns true if the segmented length <= max length.
*/
static inline bool skb_gso_size_check(const struct sk_buff *skb,
unsigned int seg_len,
unsigned int max_len) {
const struct skb_shared_info *shinfo = skb_shinfo(skb);
const struct sk_buff *iter;
if (shinfo->gso_size != GSO_BY_FRAGS)
return seg_len <= max_len;
/* Undo this so we can re-use header sizes */
seg_len -= GSO_BY_FRAGS;
skb_walk_frags(skb, iter) {
if (seg_len + skb_headlen(iter) > max_len)
return false;
}
return true;
}
/**
* skb_gso_validate_network_len - Will a split GSO skb fit into a given MTU?
*
* @skb: GSO skb
* @mtu: MTU to validate against
*
* skb_gso_validate_network_len validates if a given skb will fit a
* wanted MTU once split. It considers L3 headers, L4 headers, and the
* payload.
*/
bool skb_gso_validate_network_len(const struct sk_buff *skb, unsigned int mtu)
{
return skb_gso_size_check(skb, skb_gso_network_seglen(skb), mtu);
}
EXPORT_SYMBOL_GPL(skb_gso_validate_network_len);
/**
* skb_gso_validate_mac_len - Will a split GSO skb fit in a given length?
*
* @skb: GSO skb
* @len: length to validate against
*
* skb_gso_validate_mac_len validates if a given skb will fit a wanted
* length once split, including L2, L3 and L4 headers and the payload.
*/
bool skb_gso_validate_mac_len(const struct sk_buff *skb, unsigned int len)
{
return skb_gso_size_check(skb, skb_gso_mac_seglen(skb), len);
}
EXPORT_SYMBOL_GPL(skb_gso_validate_mac_len);
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