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skbuff.h
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skbuff.h
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/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* Definitions for the 'struct sk_buff' memory handlers.
*
* Authors:
* Alan Cox, <gw4pts@gw4pts.ampr.org>
* Florian La Roche, <rzsfl@rz.uni-sb.de>
*/
#ifndef _LINUX_SKBUFF_H
#define _LINUX_SKBUFF_H
#include <linux/kernel.h>
#include <linux/compiler.h>
#include <linux/time.h>
#include <linux/bug.h>
#include <linux/bvec.h>
#include <linux/cache.h>
#include <linux/rbtree.h>
#include <linux/socket.h>
#include <linux/refcount.h>
#include <linux/atomic.h>
#include <asm/types.h>
#include <linux/spinlock.h>
#include <linux/net.h>
#include <linux/textsearch.h>
#include <net/checksum.h>
#include <linux/rcupdate.h>
#include <linux/hrtimer.h>
#include <linux/dma-mapping.h>
#include <linux/netdev_features.h>
#include <linux/sched.h>
#include <linux/sched/clock.h>
#include <net/flow_dissector.h>
#include <linux/splice.h>
#include <linux/in6.h>
#include <linux/if_packet.h>
#include <linux/llist.h>
#include <net/flow.h>
#include <net/page_pool.h>
#if IS_ENABLED(CONFIG_NF_CONNTRACK)
#include <linux/netfilter/nf_conntrack_common.h>
#endif
/* 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
* IPv6|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 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 set in skb->ip_summed. Possible values are:
*
* CHECKSUM_NONE:
*
* 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.
*
* CHECKSUM_UNNECESSARY:
*
* The hardware you're dealing with doesn't calculate the full checksum
* (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. 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.
* UDP: IPv4 and IPv6. A device may apply CHECKSUM_UNNECESSARY to a
* zero UDP checksum for either IPv4 or IPv6, the networking stack
* may perform further validation in this case.
* GRE: only if the checksum is present in the header.
* SCTP: indicates the CRC in SCTP header has been validated.
* FCOE: indicates the CRC in FC frame has been validated.
*
* skb->csum_level indicates the number of consecutive checksums found in
* the packet minus one that have been verified as CHECKSUM_UNNECESSARY.
* For instance if a device receives an IPv6->UDP->GRE->IPv4->TCP packet
* and a device is able to verify the checksums for UDP (possibly zero),
* GRE (checksum flag is set) and TCP, skb->csum_level would be set to
* two. If the device were only able to verify the UDP checksum and not
* GRE, either because it doesn't support GRE checksum or because GRE
* checksum is bad, skb->csum_level would be set to zero (TCP checksum is
* not considered in this case).
*
* CHECKSUM_COMPLETE:
*
* This is the most generic way. The device supplied checksum of the _whole_
* packet as seen by netif_rx() and fills in skb->csum. This means the
* hardware doesn't need to parse L3/L4 headers to implement this.
*
* Notes:
* - Even if device supports only some protocols, but is able to produce
* skb->csum, it MUST use CHECKSUM_COMPLETE, not CHECKSUM_UNNECESSARY.
* - CHECKSUM_COMPLETE is not applicable to SCTP and FCoE protocols.
*
* CHECKSUM_PARTIAL:
*
* A checksum is set up to be offloaded to a device as described in the
* output description for CHECKSUM_PARTIAL. This may occur on a packet
* received directly from another Linux OS, e.g., a virtualized Linux kernel
* on the same host, or it may be set in the input path in GRO or remote
* checksum offload. For the purposes of checksum verification, the checksum
* referred to by skb->csum_start + skb->csum_offset and any preceding
* checksums in the packet are considered verified. Any checksums in the
* packet that are after the checksum being offloaded are not considered to
* be verified.
*
* 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 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. A driver may verify that the
* csum_start and csum_offset values are valid values given the length and
* offset of the packet, but it 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.
* skb_csum_hwoffload_help() can be called to resolve CHECKSUM_PARTIAL based
* on network device checksumming capabilities: if a packet does not match
* them, skb_checksum_help or skb_crc32c_help (depending on the value of
* csum_not_inet, see item D.) is called to resolve the checksum.
*
* CHECKSUM_NONE:
*
* The skb was already checksummed by the protocol, or a checksum is not
* required.
*
* CHECKSUM_UNNECESSARY:
*
* This has the same meaning as CHECKSUM_NONE for checksum offload on
* output.
*
* CHECKSUM_COMPLETE:
* Not used in checksum output. If a driver observes a packet with this value
* set in skbuff, it should treat the packet as if CHECKSUM_NONE were 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 csum_start and csum_offset accordingly, set ip_summed to
* CHECKSUM_PARTIAL and set csum_not_inet to 1, to provide an indication in
* the skbuff that the CHECKSUM_PARTIAL refers to CRC32c.
* A driver that supports both IP checksum offload and SCTP CRC32c offload
* must verify which offload is configured for a packet by testing the
* value of skb->csum_not_inet; skb_crc32c_csum_help is provided to resolve
* CHECKSUM_PARTIAL on skbs where csum_not_inet is set to 1.
*
* 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 that there is no indication in the skbuff that the
* CHECKSUM_PARTIAL refers to an FCOE checksum, so 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, and both csum_start and
* csum_offset are set to refer to the outermost checksum being offloaded
* (two offloaded checksums are possible with UDP encapsulation).
*/
/* Don't change this without changing skb_csum_unnecessary! */
#define CHECKSUM_NONE 0
#define CHECKSUM_UNNECESSARY 1
#define CHECKSUM_COMPLETE 2
#define CHECKSUM_PARTIAL 3
/* Maximum value in skb->csum_level */
#define SKB_MAX_CSUM_LEVEL 3
#define SKB_DATA_ALIGN(X) ALIGN(X, SMP_CACHE_BYTES)
#define SKB_WITH_OVERHEAD(X) \
((X) - SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
#define SKB_MAX_ORDER(X, ORDER) \
SKB_WITH_OVERHEAD((PAGE_SIZE << (ORDER)) - (X))
#define SKB_MAX_HEAD(X) (SKB_MAX_ORDER((X), 0))
#define SKB_MAX_ALLOC (SKB_MAX_ORDER(0, 2))
/* return minimum truesize of one skb containing X bytes of data */
#define SKB_TRUESIZE(X) ((X) + \
SKB_DATA_ALIGN(sizeof(struct sk_buff)) + \
SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
struct ahash_request;
struct net_device;
struct scatterlist;
struct pipe_inode_info;
struct iov_iter;
struct napi_struct;
struct bpf_prog;
union bpf_attr;
struct skb_ext;
#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
struct nf_bridge_info {
enum {
BRNF_PROTO_UNCHANGED,
BRNF_PROTO_8021Q,
BRNF_PROTO_PPPOE
} orig_proto:8;
u8 pkt_otherhost:1;
u8 in_prerouting:1;
u8 bridged_dnat:1;
__u16 frag_max_size;
struct net_device *physindev;
/* always valid & non-NULL from FORWARD on, for physdev match */
struct net_device *physoutdev;
union {
/* prerouting: detect dnat in orig/reply direction */
__be32 ipv4_daddr;
struct in6_addr ipv6_daddr;
/* after prerouting + nat detected: store original source
* mac since neigh resolution overwrites it, only used while
* skb is out in neigh layer.
*/
char neigh_header[8];
};
};
#endif
#if IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
/* Chain in tc_skb_ext will be used to share the tc chain with
* ovs recirc_id. It will be set to the current chain by tc
* and read by ovs to recirc_id.
*/
struct tc_skb_ext {
__u32 chain;
__u16 mru;
__u16 zone;
u8 post_ct:1;
u8 post_ct_snat:1;
u8 post_ct_dnat:1;
};
#endif
struct sk_buff_head {
/* These two members must be first to match sk_buff. */
struct_group_tagged(sk_buff_list, list,
struct sk_buff *next;
struct sk_buff *prev;
);
__u32 qlen;
spinlock_t lock;
};
struct sk_buff;
/* The reason of skb drop, which is used in kfree_skb_reason().
* en...maybe they should be splited by group?
*
* Each item here should also be in 'TRACE_SKB_DROP_REASON', which is
* used to translate the reason to string.
*/
enum skb_drop_reason {
SKB_DROP_REASON_NOT_SPECIFIED, /* drop reason is not specified */
SKB_DROP_REASON_NO_SOCKET, /* socket not found */
SKB_DROP_REASON_PKT_TOO_SMALL, /* packet size is too small */
SKB_DROP_REASON_TCP_CSUM, /* TCP checksum error */
SKB_DROP_REASON_SOCKET_FILTER, /* dropped by socket filter */
SKB_DROP_REASON_UDP_CSUM, /* UDP checksum error */
SKB_DROP_REASON_NETFILTER_DROP, /* dropped by netfilter */
SKB_DROP_REASON_OTHERHOST, /* packet don't belong to current
* host (interface is in promisc
* mode)
*/
SKB_DROP_REASON_IP_CSUM, /* IP checksum error */
SKB_DROP_REASON_IP_INHDR, /* there is something wrong with
* IP header (see
* IPSTATS_MIB_INHDRERRORS)
*/
SKB_DROP_REASON_IP_RPFILTER, /* IP rpfilter validate failed.
* see the document for rp_filter
* in ip-sysctl.rst for more
* information
*/
SKB_DROP_REASON_UNICAST_IN_L2_MULTICAST, /* destination address of L2
* is multicast, but L3 is
* unicast.
*/
SKB_DROP_REASON_XFRM_POLICY, /* xfrm policy check failed */
SKB_DROP_REASON_IP_NOPROTO, /* no support for IP protocol */
SKB_DROP_REASON_SOCKET_RCVBUFF, /* socket receive buff is full */
SKB_DROP_REASON_PROTO_MEM, /* proto memory limition, such as
* udp packet drop out of
* udp_memory_allocated.
*/
SKB_DROP_REASON_MAX,
};
/* To allow 64K frame to be packed as single skb without frag_list we
* require 64K/PAGE_SIZE pages plus 1 additional page to allow for
* buffers which do not start on a page boundary.
*
* Since GRO uses frags we allocate at least 16 regardless of page
* size.
*/
#if (65536/PAGE_SIZE + 1) < 16
#define MAX_SKB_FRAGS 16UL
#else
#define MAX_SKB_FRAGS (65536/PAGE_SIZE + 1)
#endif
extern int sysctl_max_skb_frags;
/* Set skb_shinfo(skb)->gso_size to this in case you want skb_segment to
* segment using its current segmentation instead.
*/
#define GSO_BY_FRAGS 0xFFFF
typedef struct bio_vec skb_frag_t;
/**
* skb_frag_size() - Returns the size of a skb fragment
* @frag: skb fragment
*/
static inline unsigned int skb_frag_size(const skb_frag_t *frag)
{
return frag->bv_len;
}
/**
* skb_frag_size_set() - Sets the size of a skb fragment
* @frag: skb fragment
* @size: size of fragment
*/
static inline void skb_frag_size_set(skb_frag_t *frag, unsigned int size)
{
frag->bv_len = size;
}
/**
* skb_frag_size_add() - Increments the size of a skb fragment by @delta
* @frag: skb fragment
* @delta: value to add
*/
static inline void skb_frag_size_add(skb_frag_t *frag, int delta)
{
frag->bv_len += delta;
}
/**
* skb_frag_size_sub() - Decrements the size of a skb fragment by @delta
* @frag: skb fragment
* @delta: value to subtract
*/
static inline void skb_frag_size_sub(skb_frag_t *frag, int delta)
{
frag->bv_len -= delta;
}
/**
* skb_frag_must_loop - Test if %p is a high memory page
* @p: fragment's page
*/
static inline bool skb_frag_must_loop(struct page *p)
{
#if defined(CONFIG_HIGHMEM)
if (IS_ENABLED(CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP) || PageHighMem(p))
return true;
#endif
return false;
}
/**
* skb_frag_foreach_page - loop over pages in a fragment
*
* @f: skb frag to operate on
* @f_off: offset from start of f->bv_page
* @f_len: length from f_off to loop over
* @p: (temp var) current page
* @p_off: (temp var) offset from start of current page,
* non-zero only on first page.
* @p_len: (temp var) length in current page,
* < PAGE_SIZE only on first and last page.
* @copied: (temp var) length so far, excluding current p_len.
*
* A fragment can hold a compound page, in which case per-page
* operations, notably kmap_atomic, must be called for each
* regular page.
*/
#define skb_frag_foreach_page(f, f_off, f_len, p, p_off, p_len, copied) \
for (p = skb_frag_page(f) + ((f_off) >> PAGE_SHIFT), \
p_off = (f_off) & (PAGE_SIZE - 1), \
p_len = skb_frag_must_loop(p) ? \
min_t(u32, f_len, PAGE_SIZE - p_off) : f_len, \
copied = 0; \
copied < f_len; \
copied += p_len, p++, p_off = 0, \
p_len = min_t(u32, f_len - copied, PAGE_SIZE)) \
#define HAVE_HW_TIME_STAMP
/**
* struct skb_shared_hwtstamps - hardware time stamps
* @hwtstamp: hardware time stamp transformed into duration
* since arbitrary point in time
*
* Software time stamps generated by ktime_get_real() are stored in
* skb->tstamp.
*
* hwtstamps can only be compared against other hwtstamps from
* the same device.
*
* This structure is attached to packets as part of the
* &skb_shared_info. Use skb_hwtstamps() to get a pointer.
*/
struct skb_shared_hwtstamps {
ktime_t hwtstamp;
};
/* Definitions for tx_flags in struct skb_shared_info */
enum {
/* generate hardware time stamp */
SKBTX_HW_TSTAMP = 1 << 0,
/* generate software time stamp when queueing packet to NIC */
SKBTX_SW_TSTAMP = 1 << 1,
/* device driver is going to provide hardware time stamp */
SKBTX_IN_PROGRESS = 1 << 2,
/* generate wifi status information (where possible) */
SKBTX_WIFI_STATUS = 1 << 4,
/* generate software time stamp when entering packet scheduling */
SKBTX_SCHED_TSTAMP = 1 << 6,
};
#define SKBTX_ANY_SW_TSTAMP (SKBTX_SW_TSTAMP | \
SKBTX_SCHED_TSTAMP)
#define SKBTX_ANY_TSTAMP (SKBTX_HW_TSTAMP | SKBTX_ANY_SW_TSTAMP)
/* Definitions for flags in struct skb_shared_info */
enum {
/* use zcopy routines */
SKBFL_ZEROCOPY_ENABLE = BIT(0),
/* This indicates at least one fragment might be overwritten
* (as in vmsplice(), sendfile() ...)
* If we need to compute a TX checksum, we'll need to copy
* all frags to avoid possible bad checksum
*/
SKBFL_SHARED_FRAG = BIT(1),
/* segment contains only zerocopy data and should not be
* charged to the kernel memory.
*/
SKBFL_PURE_ZEROCOPY = BIT(2),
};
#define SKBFL_ZEROCOPY_FRAG (SKBFL_ZEROCOPY_ENABLE | SKBFL_SHARED_FRAG)
#define SKBFL_ALL_ZEROCOPY (SKBFL_ZEROCOPY_FRAG | SKBFL_PURE_ZEROCOPY)
/*
* The callback notifies userspace to release buffers when skb DMA is done in
* lower device, the skb last reference should be 0 when calling this.
* The zerocopy_success argument is true if zero copy transmit occurred,
* false on data copy or out of memory error caused by data copy attempt.
* The ctx field is used to track device context.
* The desc field is used to track userspace buffer index.
*/
struct ubuf_info {
void (*callback)(struct sk_buff *, struct ubuf_info *,
bool zerocopy_success);
union {
struct {
unsigned long desc;
void *ctx;
};
struct {
u32 id;
u16 len;
u16 zerocopy:1;
u32 bytelen;
};
};
refcount_t refcnt;
u8 flags;
struct mmpin {
struct user_struct *user;
unsigned int num_pg;
} mmp;
};
#define skb_uarg(SKB) ((struct ubuf_info *)(skb_shinfo(SKB)->destructor_arg))
int mm_account_pinned_pages(struct mmpin *mmp, size_t size);
void mm_unaccount_pinned_pages(struct mmpin *mmp);
struct ubuf_info *msg_zerocopy_alloc(struct sock *sk, size_t size);
struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
struct ubuf_info *uarg);
void msg_zerocopy_put_abort(struct ubuf_info *uarg, bool have_uref);
void msg_zerocopy_callback(struct sk_buff *skb, struct ubuf_info *uarg,
bool success);
int skb_zerocopy_iter_dgram(struct sk_buff *skb, struct msghdr *msg, int len);
int skb_zerocopy_iter_stream(struct sock *sk, struct sk_buff *skb,
struct msghdr *msg, int len,
struct ubuf_info *uarg);
/* This data is invariant across clones and lives at
* the end of the header data, ie. at skb->end.
*/
struct skb_shared_info {
__u8 flags;
__u8 meta_len;
__u8 nr_frags;
__u8 tx_flags;
unsigned short gso_size;
/* Warning: this field is not always filled in (UFO)! */
unsigned short gso_segs;
struct sk_buff *frag_list;
struct skb_shared_hwtstamps hwtstamps;
unsigned int gso_type;
u32 tskey;
/*
* Warning : all fields before dataref are cleared in __alloc_skb()
*/
atomic_t dataref;
unsigned int xdp_frags_size;
/* Intermediate layers must ensure that destructor_arg
* remains valid until skb destructor */
void * destructor_arg;
/* must be last field, see pskb_expand_head() */
skb_frag_t frags[MAX_SKB_FRAGS];
};
/* We divide dataref into two halves. The higher 16 bits hold references
* to the payload part of skb->data. The lower 16 bits hold references to
* the entire skb->data. A clone of a headerless skb holds the length of
* the header in skb->hdr_len.
*
* All users must obey the rule that the skb->data reference count must be
* greater than or equal to the payload reference count.
*
* Holding a reference to the payload part means that the user does not
* care about modifications to the header part of skb->data.
*/
#define SKB_DATAREF_SHIFT 16
#define SKB_DATAREF_MASK ((1 << SKB_DATAREF_SHIFT) - 1)
enum {
SKB_FCLONE_UNAVAILABLE, /* skb has no fclone (from head_cache) */
SKB_FCLONE_ORIG, /* orig skb (from fclone_cache) */
SKB_FCLONE_CLONE, /* companion fclone skb (from fclone_cache) */
};
enum {
SKB_GSO_TCPV4 = 1 << 0,
/* This indicates the skb is from an untrusted source. */
SKB_GSO_DODGY = 1 << 1,
/* This indicates the tcp segment has CWR set. */
SKB_GSO_TCP_ECN = 1 << 2,
SKB_GSO_TCP_FIXEDID = 1 << 3,
SKB_GSO_TCPV6 = 1 << 4,
SKB_GSO_FCOE = 1 << 5,
SKB_GSO_GRE = 1 << 6,
SKB_GSO_GRE_CSUM = 1 << 7,
SKB_GSO_IPXIP4 = 1 << 8,
SKB_GSO_IPXIP6 = 1 << 9,
SKB_GSO_UDP_TUNNEL = 1 << 10,
SKB_GSO_UDP_TUNNEL_CSUM = 1 << 11,
SKB_GSO_PARTIAL = 1 << 12,
SKB_GSO_TUNNEL_REMCSUM = 1 << 13,
SKB_GSO_SCTP = 1 << 14,
SKB_GSO_ESP = 1 << 15,
SKB_GSO_UDP = 1 << 16,
SKB_GSO_UDP_L4 = 1 << 17,
SKB_GSO_FRAGLIST = 1 << 18,
};
#if BITS_PER_LONG > 32
#define NET_SKBUFF_DATA_USES_OFFSET 1
#endif
#ifdef NET_SKBUFF_DATA_USES_OFFSET
typedef unsigned int sk_buff_data_t;
#else
typedef unsigned char *sk_buff_data_t;
#endif
/**
* struct sk_buff - socket buffer
* @next: Next buffer in list
* @prev: Previous buffer in list
* @tstamp: Time we arrived/left
* @skb_mstamp_ns: (aka @tstamp) earliest departure time; start point
* for retransmit timer
* @rbnode: RB tree node, alternative to next/prev for netem/tcp
* @list: queue head
* @ll_node: anchor in an llist (eg socket defer_list)
* @sk: Socket we are owned by
* @ip_defrag_offset: (aka @sk) alternate use of @sk, used in
* fragmentation management
* @dev: Device we arrived on/are leaving by
* @dev_scratch: (aka @dev) alternate use of @dev when @dev would be %NULL
* @cb: Control buffer. Free for use by every layer. Put private vars here
* @_skb_refdst: destination entry (with norefcount bit)
* @sp: the security path, used for xfrm
* @len: Length of actual data
* @data_len: Data length
* @mac_len: Length of link layer header
* @hdr_len: writable header length of cloned skb
* @csum: Checksum (must include start/offset pair)
* @csum_start: Offset from skb->head where checksumming should start
* @csum_offset: Offset from csum_start where checksum should be stored
* @priority: Packet queueing priority
* @ignore_df: allow local fragmentation
* @cloned: Head may be cloned (check refcnt to be sure)
* @ip_summed: Driver fed us an IP checksum
* @nohdr: Payload reference only, must not modify header
* @pkt_type: Packet class
* @fclone: skbuff clone status
* @ipvs_property: skbuff is owned by ipvs
* @inner_protocol_type: whether the inner protocol is
* ENCAP_TYPE_ETHER or ENCAP_TYPE_IPPROTO
* @remcsum_offload: remote checksum offload is enabled
* @offload_fwd_mark: Packet was L2-forwarded in hardware
* @offload_l3_fwd_mark: Packet was L3-forwarded in hardware
* @tc_skip_classify: do not classify packet. set by IFB device
* @tc_at_ingress: used within tc_classify to distinguish in/egress
* @redirected: packet was redirected by packet classifier
* @from_ingress: packet was redirected from the ingress path
* @nf_skip_egress: packet shall skip nf egress - see netfilter_netdev.h
* @peeked: this packet has been seen already, so stats have been
* done for it, don't do them again
* @nf_trace: netfilter packet trace flag
* @protocol: Packet protocol from driver
* @destructor: Destruct function
* @tcp_tsorted_anchor: list structure for TCP (tp->tsorted_sent_queue)
* @_sk_redir: socket redirection information for skmsg
* @_nfct: Associated connection, if any (with nfctinfo bits)
* @nf_bridge: Saved data about a bridged frame - see br_netfilter.c
* @skb_iif: ifindex of device we arrived on
* @tc_index: Traffic control index
* @hash: the packet hash
* @queue_mapping: Queue mapping for multiqueue devices
* @head_frag: skb was allocated from page fragments,
* not allocated by kmalloc() or vmalloc().
* @pfmemalloc: skbuff was allocated from PFMEMALLOC reserves
* @pp_recycle: mark the packet for recycling instead of freeing (implies
* page_pool support on driver)
* @active_extensions: active extensions (skb_ext_id types)
* @ndisc_nodetype: router type (from link layer)
* @ooo_okay: allow the mapping of a socket to a queue to be changed
* @l4_hash: indicate hash is a canonical 4-tuple hash over transport
* ports.
* @sw_hash: indicates hash was computed in software stack
* @wifi_acked_valid: wifi_acked was set
* @wifi_acked: whether frame was acked on wifi or not
* @no_fcs: Request NIC to treat last 4 bytes as Ethernet FCS
* @encapsulation: indicates the inner headers in the skbuff are valid
* @encap_hdr_csum: software checksum is needed
* @csum_valid: checksum is already valid
* @csum_not_inet: use CRC32c to resolve CHECKSUM_PARTIAL
* @csum_complete_sw: checksum was completed by software
* @csum_level: indicates the number of consecutive checksums found in
* the packet minus one that have been verified as
* CHECKSUM_UNNECESSARY (max 3)
* @dst_pending_confirm: need to confirm neighbour
* @decrypted: Decrypted SKB
* @slow_gro: state present at GRO time, slower prepare step required
* @napi_id: id of the NAPI struct this skb came from
* @sender_cpu: (aka @napi_id) source CPU in XPS
* @secmark: security marking
* @mark: Generic packet mark
* @reserved_tailroom: (aka @mark) number of bytes of free space available
* at the tail of an sk_buff
* @vlan_present: VLAN tag is present
* @vlan_proto: vlan encapsulation protocol
* @vlan_tci: vlan tag control information
* @inner_protocol: Protocol (encapsulation)
* @inner_ipproto: (aka @inner_protocol) stores ipproto when
* skb->inner_protocol_type == ENCAP_TYPE_IPPROTO;
* @inner_transport_header: Inner transport layer header (encapsulation)
* @inner_network_header: Network layer header (encapsulation)
* @inner_mac_header: Link layer header (encapsulation)
* @transport_header: Transport layer header
* @network_header: Network layer header
* @mac_header: Link layer header
* @kcov_handle: KCOV remote handle for remote coverage collection
* @tail: Tail pointer
* @end: End pointer
* @head: Head of buffer
* @data: Data head pointer
* @truesize: Buffer size
* @users: User count - see {datagram,tcp}.c
* @extensions: allocated extensions, valid if active_extensions is nonzero
*/
struct sk_buff {
union {
struct {
/* These two members must be first to match sk_buff_head. */
struct sk_buff *next;
struct sk_buff *prev;
union {
struct net_device *dev;
/* Some protocols might use this space to store information,
* while device pointer would be NULL.
* UDP receive path is one user.
*/
unsigned long dev_scratch;
};
};
struct rb_node rbnode; /* used in netem, ip4 defrag, and tcp stack */
struct list_head list;
struct llist_node ll_node;
};
union {
struct sock *sk;
int ip_defrag_offset;
};
union {
ktime_t tstamp;
u64 skb_mstamp_ns; /* earliest departure time */
};
/*
* This is the control buffer. It is free to use for every
* layer. Please put your private variables there. If you
* want to keep them across layers you have to do a skb_clone()
* first. This is owned by whoever has the skb queued ATM.
*/
char cb[48] __aligned(8);
union {
struct {
unsigned long _skb_refdst;
void (*destructor)(struct sk_buff *skb);
};
struct list_head tcp_tsorted_anchor;
#ifdef CONFIG_NET_SOCK_MSG
unsigned long _sk_redir;
#endif
};
#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
unsigned long _nfct;
#endif
unsigned int len,
data_len;
__u16 mac_len,
hdr_len;
/* Following fields are _not_ copied in __copy_skb_header()
* Note that queue_mapping is here mostly to fill a hole.
*/
__u16 queue_mapping;
/* if you move cloned around you also must adapt those constants */
#ifdef __BIG_ENDIAN_BITFIELD
#define CLONED_MASK (1 << 7)
#else
#define CLONED_MASK 1
#endif
#define CLONED_OFFSET offsetof(struct sk_buff, __cloned_offset)
/* private: */
__u8 __cloned_offset[0];
/* public: */
__u8 cloned:1,
nohdr:1,
fclone:2,
peeked:1,
head_frag:1,
pfmemalloc:1,
pp_recycle:1; /* page_pool recycle indicator */
#ifdef CONFIG_SKB_EXTENSIONS
__u8 active_extensions;
#endif
/* Fields enclosed in headers group are copied
* using a single memcpy() in __copy_skb_header()
*/
struct_group(headers,
/* private: */
__u8 __pkt_type_offset[0];
/* public: */
__u8 pkt_type:3; /* see PKT_TYPE_MAX */
__u8 ignore_df:1;
__u8 nf_trace:1;
__u8 ip_summed:2;
__u8 ooo_okay:1;
__u8 l4_hash:1;
__u8 sw_hash:1;
__u8 wifi_acked_valid:1;
__u8 wifi_acked:1;
__u8 no_fcs:1;
/* Indicates the inner headers are valid in the skbuff. */
__u8 encapsulation:1;
__u8 encap_hdr_csum:1;
__u8 csum_valid:1;
/* private: */
__u8 __pkt_vlan_present_offset[0];
/* public: */
__u8 vlan_present:1; /* See PKT_VLAN_PRESENT_BIT */
__u8 csum_complete_sw:1;
__u8 csum_level:2;
__u8 csum_not_inet:1;
__u8 dst_pending_confirm:1;
#ifdef CONFIG_IPV6_NDISC_NODETYPE
__u8 ndisc_nodetype:2;
#endif
__u8 ipvs_property:1;
__u8 inner_protocol_type:1;
__u8 remcsum_offload:1;
#ifdef CONFIG_NET_SWITCHDEV
__u8 offload_fwd_mark:1;
__u8 offload_l3_fwd_mark:1;
#endif
#ifdef CONFIG_NET_CLS_ACT
__u8 tc_skip_classify:1;
__u8 tc_at_ingress:1;
#endif
__u8 redirected:1;
#ifdef CONFIG_NET_REDIRECT
__u8 from_ingress:1;
#endif
#ifdef CONFIG_NETFILTER_SKIP_EGRESS
__u8 nf_skip_egress:1;
#endif
#ifdef CONFIG_TLS_DEVICE
__u8 decrypted:1;
#endif
__u8 slow_gro:1;
#ifdef CONFIG_NET_SCHED
__u16 tc_index; /* traffic control index */
#endif
union {
__wsum csum;
struct {
__u16 csum_start;
__u16 csum_offset;
};
};
__u32 priority;
int skb_iif;
__u32 hash;
__be16 vlan_proto;
__u16 vlan_tci;
#if defined(CONFIG_NET_RX_BUSY_POLL) || defined(CONFIG_XPS)
union {
unsigned int napi_id;
unsigned int sender_cpu;
};
#endif
#ifdef CONFIG_NETWORK_SECMARK
__u32 secmark;
#endif
union {
__u32 mark;
__u32 reserved_tailroom;
};
union {
__be16 inner_protocol;
__u8 inner_ipproto;
};
__u16 inner_transport_header;
__u16 inner_network_header;
__u16 inner_mac_header;
__be16 protocol;
__u16 transport_header;
__u16 network_header;
__u16 mac_header;
#ifdef CONFIG_KCOV
u64 kcov_handle;
#endif
); /* end headers group */
/* These elements must be at the end, see alloc_skb() for details. */
sk_buff_data_t tail;
sk_buff_data_t end;
unsigned char *head,
*data;
unsigned int truesize;
refcount_t users;
#ifdef CONFIG_SKB_EXTENSIONS
/* only useable after checking ->active_extensions != 0 */
struct skb_ext *extensions;
#endif
};
/* if you move pkt_type around you also must adapt those constants */
#ifdef __BIG_ENDIAN_BITFIELD
#define PKT_TYPE_MAX (7 << 5)
#else
#define PKT_TYPE_MAX 7
#endif
#define PKT_TYPE_OFFSET offsetof(struct sk_buff, __pkt_type_offset)
/* if you move pkt_vlan_present around you also must adapt these constants */
#ifdef __BIG_ENDIAN_BITFIELD
#define PKT_VLAN_PRESENT_BIT 7
#else
#define PKT_VLAN_PRESENT_BIT 0
#endif
#define PKT_VLAN_PRESENT_OFFSET offsetof(struct sk_buff, __pkt_vlan_present_offset)