linux/net/core/gso.c

// 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)
{ … }
EXPORT_SYMBOL(…);

/**
 *	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)
{ … }
EXPORT_SYMBOL(…);
/* 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)
{ … }

/**
 *	__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)
{ … }
EXPORT_SYMBOL(…);

/**
 * 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)
{ … }

/**
 * 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)
{ … }

/**
 * 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)
{ … }

/**
 * 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) { … }

/**
 * 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)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 * 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)
{ … }
EXPORT_SYMBOL_GPL(…);