#include <linux/in6.h>
#include <net/flow.h>
-/* A. Checksumming of received packets by device.
+/* The interface for checksum offload between the stack and networking drivers
+ * is as follows...
+ *
+ * A. IP checksum related features
+ *
+ * Drivers advertise checksum offload capabilities in the features of a device.
+ * From the stack's point of view these are capabilities offered by the driver,
+ * a driver typically only advertises features that it is capable of offloading
+ * to its device.
+ *
+ * The checksum related features are:
+ *
+ * NETIF_F_HW_CSUM - The driver (or its device) is able to compute one
+ * IP (one's complement) checksum for any combination
+ * of protocols or protocol layering. The checksum is
+ * computed and set in a packet per the CHECKSUM_PARTIAL
+ * interface (see below).
+ *
+ * NETIF_F_IP_CSUM - Driver (device) is only able to checksum plain
+ * TCP or UDP packets over IPv4. These are specifically
+ * unencapsulated packets of the form IPv4|TCP or
+ * IPv4|UDP where the Protocol field in the IPv4 header
+ * is TCP or UDP. The IPv4 header may contain IP options
+ * This feature cannot be set in features for a device
+ * with NETIF_F_HW_CSUM also set. This feature is being
+ * DEPRECATED (see below).
+ *
+ * NETIF_F_IPV6_CSUM - Driver (device) is only able to checksum plain
+ * TCP or UDP packets over IPv6. These are specifically
+ * unencapsulated packets of the form IPv6|TCP or
+ * IPv4|UDP where the Next Header field in the IPv6
+ * header is either TCP or UDP. IPv6 extension headers
+ * are not supported with this feature. This feature
+ * cannot be set in features for a device with
+ * NETIF_F_HW_CSUM also set. This feature is being
+ * DEPRECATED (see below).
+ *
+ * NETIF_F_RXCSUM - Driver (device) performs receive checksum offload.
+ * This flag is used only used to disable the RX checksum
+ * feature for a device. The stack will accept receive
+ * checksum indication in packets received on a device
+ * regardless of whether NETIF_F_RXCSUM is set.
+ *
+ * B. Checksumming of received packets by device. Indication of checksum
+ * verification is in set skb->ip_summed. Possible values are:
*
* CHECKSUM_NONE:
*
- * Device failed to checksum this packet e.g. due to lack of capabilities.
+ * Device did not checksum this packet e.g. due to lack of capabilities.
* The packet contains full (though not verified) checksum in packet but
* not in skb->csum. Thus, skb->csum is undefined in this case.
*
* (as in CHECKSUM_COMPLETE), but it does parse headers and verify checksums
* for specific protocols. For such packets it will set CHECKSUM_UNNECESSARY
* if their checksums are okay. skb->csum is still undefined in this case
- * though. It is a bad option, but, unfortunately, nowadays most vendors do
- * this. Apparently with the secret goal to sell you new devices, when you
- * will add new protocol to your host, f.e. IPv6 8)
+ * though. A driver or device must never modify the checksum field in the
+ * packet even if checksum is verified.
*
* CHECKSUM_UNNECESSARY is applicable to following protocols:
* TCP: IPv6 and IPv4.
* packet that are after the checksum being offloaded are not considered to
* be verified.
*
- * B. Checksumming on output.
- *
- * CHECKSUM_NONE:
- *
- * The skb was already checksummed by the protocol, or a checksum is not
- * required.
+ * C. Checksumming on transmit for non-GSO. The stack requests checksum offload
+ * in the skb->ip_summed for a packet. Values are:
*
* CHECKSUM_PARTIAL:
*
- * The device is required to checksum the packet as seen by hard_start_xmit()
+ * The driver is required to checksum the packet as seen by hard_start_xmit()
* from skb->csum_start up to the end, and to record/write the checksum at
- * offset skb->csum_start + skb->csum_offset.
+ * offset skb->csum_start + skb->csum_offset. A driver may verify that the
+ * csum_start and csum_offset values are valid values given the length and
+ * offset of the packet, however they should not attempt to validate that the
+ * checksum refers to a legitimate transport layer checksum-- it is the
+ * purview of the stack to validate that csum_start and csum_offset are set
+ * correctly.
+ *
+ * When the stack requests checksum offload for a packet, the driver MUST
+ * ensure that the checksum is set correctly. A driver can either offload the
+ * checksum calculation to the device, or call skb_checksum_help (in the case
+ * that the device does not support offload for a particular checksum).
+ *
+ * NETIF_F_IP_CSUM and NETIF_F_IPV6_CSUM are being deprecated in favor of
+ * NETIF_F_HW_CSUM. New devices should use NETIF_F_HW_CSUM to indicate
+ * checksum offload capability. If a device has limited checksum capabilities
+ * (for instance can only perform NETIF_F_IP_CSUM or NETIF_F_IPV6_CSUM as
+ * described above) a helper function can be called to resolve
+ * CHECKSUM_PARTIAL. The helper functions are skb_csum_off_chk*. The helper
+ * function takes a spec argument that describes the protocol layer that is
+ * supported for checksum offload and can be called for each packet. If a
+ * packet does not match the specification for offload, skb_checksum_help
+ * is called to resolve the checksum.
*
- * The device must show its capabilities in dev->features, set up at device
- * setup time, e.g. netdev_features.h:
+ * CHECKSUM_NONE:
*
- * NETIF_F_HW_CSUM - It's a clever device, it's able to checksum everything.
- * NETIF_F_IP_CSUM - Device is dumb, it's able to checksum only TCP/UDP over
- * IPv4. Sigh. Vendors like this way for an unknown reason.
- * Though, see comment above about CHECKSUM_UNNECESSARY. 8)
- * NETIF_F_IPV6_CSUM - About as dumb as the last one but does IPv6 instead.
- * NETIF_F_... - Well, you get the picture.
+ * The skb was already checksummed by the protocol, or a checksum is not
+ * required.
*
* CHECKSUM_UNNECESSARY:
*
- * Normally, the device will do per protocol specific checksumming. Protocol
- * implementations that do not want the NIC to perform the checksum
- * calculation should use this flag in their outgoing skbs.
- *
- * NETIF_F_FCOE_CRC - This indicates that the device can do FCoE FC CRC
- * offload. Correspondingly, the FCoE protocol driver
- * stack should use CHECKSUM_UNNECESSARY.
+ * This has the same meaning on as CHECKSUM_NONE for checksum offload on
+ * output.
*
- * Any questions? No questions, good. --ANK
+ * CHECKSUM_COMPLETE:
+ * Not used in checksum output. If a driver observes a packet with this value
+ * set in skbuff, if should treat as CHECKSUM_NONE being set.
+ *
+ * D. Non-IP checksum (CRC) offloads
+ *
+ * NETIF_F_SCTP_CRC - This feature indicates that a device is capable of
+ * offloading the SCTP CRC in a packet. To perform this offload the stack
+ * will set ip_summed to CHECKSUM_PARTIAL and set csum_start and csum_offset
+ * accordingly. Note the there is no indication in the skbuff that the
+ * CHECKSUM_PARTIAL refers to an SCTP checksum, a driver that supports
+ * both IP checksum offload and SCTP CRC offload must verify which offload
+ * is configured for a packet presumably by inspecting packet headers.
+ *
+ * NETIF_F_FCOE_CRC - This feature indicates that a device is capable of
+ * offloading the FCOE CRC in a packet. To perform this offload the stack
+ * will set ip_summed to CHECKSUM_PARTIAL and set csum_start and csum_offset
+ * accordingly. Note the there is no indication in the skbuff that the
+ * CHECKSUM_PARTIAL refers to an FCOE checksum, a driver that supports
+ * both IP checksum offload and FCOE CRC offload must verify which offload
+ * is configured for a packet presumably by inspecting packet headers.
+ *
+ * E. Checksumming on output with GSO.
+ *
+ * In the case of a GSO packet (skb_is_gso(skb) is true), checksum offload
+ * is implied by the SKB_GSO_* flags in gso_type. Most obviously, if the
+ * gso_type is SKB_GSO_TCPV4 or SKB_GSO_TCPV6, TCP checksum offload as
+ * part of the GSO operation is implied. If a checksum is being offloaded
+ * with GSO then ip_summed is CHECKSUM_PARTIAL, csum_start and csum_offset
+ * are set to refer to the outermost checksum being offload (two offloaded
+ * checksums are possible with UDP encapsulation).
*/
/* Don't change this without changing skb_csum_unnecessary! */
* skb_fclone_busy - check if fclone is busy
* @skb: buffer
*
- * Returns true is skb is a fast clone, and its clone is not freed.
+ * Returns true if skb is a fast clone, and its clone is not freed.
* Some drivers call skb_orphan() in their ndo_start_xmit(),
* so we also check that this didnt happen.
*/
static inline void skb_sender_cpu_clear(struct sk_buff *skb)
{
-#ifdef CONFIG_XPS
- skb->sender_cpu = 0;
-#endif
}
#ifdef NET_SKBUFF_DATA_USES_OFFSET
return skb->head + skb->inner_transport_header;
}
+static inline int skb_inner_transport_offset(const struct sk_buff *skb)
+{
+ return skb_inner_transport_header(skb) - skb->data;
+}
+
static inline void skb_reset_inner_transport_header(struct sk_buff *skb)
{
skb->inner_transport_header = skb->data - skb->head;
unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len);
+static inline void skb_postpush_rcsum(struct sk_buff *skb,
+ const void *start, unsigned int len)
+{
+ /* For performing the reverse operation to skb_postpull_rcsum(),
+ * we can instead of ...
+ *
+ * skb->csum = csum_add(skb->csum, csum_partial(start, len, 0));
+ *
+ * ... just use this equivalent version here to save a few
+ * instructions. Feeding csum of 0 in csum_partial() and later
+ * on adding skb->csum is equivalent to feed skb->csum in the
+ * first place.
+ */
+ if (skb->ip_summed == CHECKSUM_COMPLETE)
+ skb->csum = csum_partial(start, len, skb->csum);
+}
+
/**
* pskb_trim_rcsum - trim received skb and update checksum
* @skb: buffer to trim
#define skb_walk_frags(skb, iter) \
for (iter = skb_shinfo(skb)->frag_list; iter; iter = iter->next)
+
+int __skb_wait_for_more_packets(struct sock *sk, int *err, long *timeo_p,
+ const struct sk_buff *skb);
+struct sk_buff *__skb_try_recv_datagram(struct sock *sk, unsigned flags,
+ int *peeked, int *off, int *err,
+ struct sk_buff **last);
struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned flags,
int *peeked, int *off, int *err);
struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags, int noblock,
int encap_level;
__u16 csum_start;
};
-#define SKB_GSO_CB(skb) ((struct skb_gso_cb *)(skb)->cb)
+#define SKB_SGO_CB_OFFSET 32
+#define SKB_GSO_CB(skb) ((struct skb_gso_cb *)((skb)->cb + SKB_SGO_CB_OFFSET))
static inline int skb_tnl_header_len(const struct sk_buff *inner_skb)
{
projects / mirror_ubuntu-bionic-kernel.git / blobdiff