Version:  2.0.40 2.2.26 2.4.37 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4

Linux/include/linux/skbuff.h

  1 /*
  2  *      Definitions for the 'struct sk_buff' memory handlers.
  3  *
  4  *      Authors:
  5  *              Alan Cox, <gw4pts@gw4pts.ampr.org>
  6  *              Florian La Roche, <rzsfl@rz.uni-sb.de>
  7  *
  8  *      This program is free software; you can redistribute it and/or
  9  *      modify it under the terms of the GNU General Public License
 10  *      as published by the Free Software Foundation; either version
 11  *      2 of the License, or (at your option) any later version.
 12  */
 13 
 14 #ifndef _LINUX_SKBUFF_H
 15 #define _LINUX_SKBUFF_H
 16 
 17 #include <linux/kernel.h>
 18 #include <linux/kmemcheck.h>
 19 #include <linux/compiler.h>
 20 #include <linux/time.h>
 21 #include <linux/bug.h>
 22 #include <linux/cache.h>
 23 #include <linux/rbtree.h>
 24 #include <linux/socket.h>
 25 
 26 #include <linux/atomic.h>
 27 #include <asm/types.h>
 28 #include <linux/spinlock.h>
 29 #include <linux/net.h>
 30 #include <linux/textsearch.h>
 31 #include <net/checksum.h>
 32 #include <linux/rcupdate.h>
 33 #include <linux/hrtimer.h>
 34 #include <linux/dma-mapping.h>
 35 #include <linux/netdev_features.h>
 36 #include <linux/sched.h>
 37 #include <net/flow_dissector.h>
 38 #include <linux/splice.h>
 39 #include <linux/in6.h>
 40 #include <net/flow.h>
 41 
 42 /* A. Checksumming of received packets by device.
 43  *
 44  * CHECKSUM_NONE:
 45  *
 46  *   Device failed to checksum this packet e.g. due to lack of capabilities.
 47  *   The packet contains full (though not verified) checksum in packet but
 48  *   not in skb->csum. Thus, skb->csum is undefined in this case.
 49  *
 50  * CHECKSUM_UNNECESSARY:
 51  *
 52  *   The hardware you're dealing with doesn't calculate the full checksum
 53  *   (as in CHECKSUM_COMPLETE), but it does parse headers and verify checksums
 54  *   for specific protocols. For such packets it will set CHECKSUM_UNNECESSARY
 55  *   if their checksums are okay. skb->csum is still undefined in this case
 56  *   though. It is a bad option, but, unfortunately, nowadays most vendors do
 57  *   this. Apparently with the secret goal to sell you new devices, when you
 58  *   will add new protocol to your host, f.e. IPv6 8)
 59  *
 60  *   CHECKSUM_UNNECESSARY is applicable to following protocols:
 61  *     TCP: IPv6 and IPv4.
 62  *     UDP: IPv4 and IPv6. A device may apply CHECKSUM_UNNECESSARY to a
 63  *       zero UDP checksum for either IPv4 or IPv6, the networking stack
 64  *       may perform further validation in this case.
 65  *     GRE: only if the checksum is present in the header.
 66  *     SCTP: indicates the CRC in SCTP header has been validated.
 67  *
 68  *   skb->csum_level indicates the number of consecutive checksums found in
 69  *   the packet minus one that have been verified as CHECKSUM_UNNECESSARY.
 70  *   For instance if a device receives an IPv6->UDP->GRE->IPv4->TCP packet
 71  *   and a device is able to verify the checksums for UDP (possibly zero),
 72  *   GRE (checksum flag is set), and TCP-- skb->csum_level would be set to
 73  *   two. If the device were only able to verify the UDP checksum and not
 74  *   GRE, either because it doesn't support GRE checksum of because GRE
 75  *   checksum is bad, skb->csum_level would be set to zero (TCP checksum is
 76  *   not considered in this case).
 77  *
 78  * CHECKSUM_COMPLETE:
 79  *
 80  *   This is the most generic way. The device supplied checksum of the _whole_
 81  *   packet as seen by netif_rx() and fills out in skb->csum. Meaning, the
 82  *   hardware doesn't need to parse L3/L4 headers to implement this.
 83  *
 84  *   Note: Even if device supports only some protocols, but is able to produce
 85  *   skb->csum, it MUST use CHECKSUM_COMPLETE, not CHECKSUM_UNNECESSARY.
 86  *
 87  * CHECKSUM_PARTIAL:
 88  *
 89  *   A checksum is set up to be offloaded to a device as described in the
 90  *   output description for CHECKSUM_PARTIAL. This may occur on a packet
 91  *   received directly from another Linux OS, e.g., a virtualized Linux kernel
 92  *   on the same host, or it may be set in the input path in GRO or remote
 93  *   checksum offload. For the purposes of checksum verification, the checksum
 94  *   referred to by skb->csum_start + skb->csum_offset and any preceding
 95  *   checksums in the packet are considered verified. Any checksums in the
 96  *   packet that are after the checksum being offloaded are not considered to
 97  *   be verified.
 98  *
 99  * B. Checksumming on output.
100  *
101  * CHECKSUM_NONE:
102  *
103  *   The skb was already checksummed by the protocol, or a checksum is not
104  *   required.
105  *
106  * CHECKSUM_PARTIAL:
107  *
108  *   The device is required to checksum the packet as seen by hard_start_xmit()
109  *   from skb->csum_start up to the end, and to record/write the checksum at
110  *   offset skb->csum_start + skb->csum_offset.
111  *
112  *   The device must show its capabilities in dev->features, set up at device
113  *   setup time, e.g. netdev_features.h:
114  *
115  *      NETIF_F_HW_CSUM - It's a clever device, it's able to checksum everything.
116  *      NETIF_F_IP_CSUM - Device is dumb, it's able to checksum only TCP/UDP over
117  *                        IPv4. Sigh. Vendors like this way for an unknown reason.
118  *                        Though, see comment above about CHECKSUM_UNNECESSARY. 8)
119  *      NETIF_F_IPV6_CSUM - About as dumb as the last one but does IPv6 instead.
120  *      NETIF_F_...     - Well, you get the picture.
121  *
122  * CHECKSUM_UNNECESSARY:
123  *
124  *   Normally, the device will do per protocol specific checksumming. Protocol
125  *   implementations that do not want the NIC to perform the checksum
126  *   calculation should use this flag in their outgoing skbs.
127  *
128  *      NETIF_F_FCOE_CRC - This indicates that the device can do FCoE FC CRC
129  *                         offload. Correspondingly, the FCoE protocol driver
130  *                         stack should use CHECKSUM_UNNECESSARY.
131  *
132  * Any questions? No questions, good.           --ANK
133  */
134 
135 /* Don't change this without changing skb_csum_unnecessary! */
136 #define CHECKSUM_NONE           0
137 #define CHECKSUM_UNNECESSARY    1
138 #define CHECKSUM_COMPLETE       2
139 #define CHECKSUM_PARTIAL        3
140 
141 /* Maximum value in skb->csum_level */
142 #define SKB_MAX_CSUM_LEVEL      3
143 
144 #define SKB_DATA_ALIGN(X)       ALIGN(X, SMP_CACHE_BYTES)
145 #define SKB_WITH_OVERHEAD(X)    \
146         ((X) - SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
147 #define SKB_MAX_ORDER(X, ORDER) \
148         SKB_WITH_OVERHEAD((PAGE_SIZE << (ORDER)) - (X))
149 #define SKB_MAX_HEAD(X)         (SKB_MAX_ORDER((X), 0))
150 #define SKB_MAX_ALLOC           (SKB_MAX_ORDER(0, 2))
151 
152 /* return minimum truesize of one skb containing X bytes of data */
153 #define SKB_TRUESIZE(X) ((X) +                                          \
154                          SKB_DATA_ALIGN(sizeof(struct sk_buff)) +       \
155                          SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
156 
157 struct net_device;
158 struct scatterlist;
159 struct pipe_inode_info;
160 struct iov_iter;
161 struct napi_struct;
162 
163 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
164 struct nf_conntrack {
165         atomic_t use;
166 };
167 #endif
168 
169 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
170 struct nf_bridge_info {
171         atomic_t                use;
172         enum {
173                 BRNF_PROTO_UNCHANGED,
174                 BRNF_PROTO_8021Q,
175                 BRNF_PROTO_PPPOE
176         } orig_proto:8;
177         u8                      pkt_otherhost:1;
178         u8                      in_prerouting:1;
179         u8                      bridged_dnat:1;
180         __u16                   frag_max_size;
181         struct net_device       *physindev;
182 
183         /* always valid & non-NULL from FORWARD on, for physdev match */
184         struct net_device       *physoutdev;
185         union {
186                 /* prerouting: detect dnat in orig/reply direction */
187                 __be32          ipv4_daddr;
188                 struct in6_addr ipv6_daddr;
189 
190                 /* after prerouting + nat detected: store original source
191                  * mac since neigh resolution overwrites it, only used while
192                  * skb is out in neigh layer.
193                  */
194                 char neigh_header[8];
195         };
196 };
197 #endif
198 
199 struct sk_buff_head {
200         /* These two members must be first. */
201         struct sk_buff  *next;
202         struct sk_buff  *prev;
203 
204         __u32           qlen;
205         spinlock_t      lock;
206 };
207 
208 struct sk_buff;
209 
210 /* To allow 64K frame to be packed as single skb without frag_list we
211  * require 64K/PAGE_SIZE pages plus 1 additional page to allow for
212  * buffers which do not start on a page boundary.
213  *
214  * Since GRO uses frags we allocate at least 16 regardless of page
215  * size.
216  */
217 #if (65536/PAGE_SIZE + 1) < 16
218 #define MAX_SKB_FRAGS 16UL
219 #else
220 #define MAX_SKB_FRAGS (65536/PAGE_SIZE + 1)
221 #endif
222 
223 typedef struct skb_frag_struct skb_frag_t;
224 
225 struct skb_frag_struct {
226         struct {
227                 struct page *p;
228         } page;
229 #if (BITS_PER_LONG > 32) || (PAGE_SIZE >= 65536)
230         __u32 page_offset;
231         __u32 size;
232 #else
233         __u16 page_offset;
234         __u16 size;
235 #endif
236 };
237 
238 static inline unsigned int skb_frag_size(const skb_frag_t *frag)
239 {
240         return frag->size;
241 }
242 
243 static inline void skb_frag_size_set(skb_frag_t *frag, unsigned int size)
244 {
245         frag->size = size;
246 }
247 
248 static inline void skb_frag_size_add(skb_frag_t *frag, int delta)
249 {
250         frag->size += delta;
251 }
252 
253 static inline void skb_frag_size_sub(skb_frag_t *frag, int delta)
254 {
255         frag->size -= delta;
256 }
257 
258 #define HAVE_HW_TIME_STAMP
259 
260 /**
261  * struct skb_shared_hwtstamps - hardware time stamps
262  * @hwtstamp:   hardware time stamp transformed into duration
263  *              since arbitrary point in time
264  *
265  * Software time stamps generated by ktime_get_real() are stored in
266  * skb->tstamp.
267  *
268  * hwtstamps can only be compared against other hwtstamps from
269  * the same device.
270  *
271  * This structure is attached to packets as part of the
272  * &skb_shared_info. Use skb_hwtstamps() to get a pointer.
273  */
274 struct skb_shared_hwtstamps {
275         ktime_t hwtstamp;
276 };
277 
278 /* Definitions for tx_flags in struct skb_shared_info */
279 enum {
280         /* generate hardware time stamp */
281         SKBTX_HW_TSTAMP = 1 << 0,
282 
283         /* generate software time stamp when queueing packet to NIC */
284         SKBTX_SW_TSTAMP = 1 << 1,
285 
286         /* device driver is going to provide hardware time stamp */
287         SKBTX_IN_PROGRESS = 1 << 2,
288 
289         /* device driver supports TX zero-copy buffers */
290         SKBTX_DEV_ZEROCOPY = 1 << 3,
291 
292         /* generate wifi status information (where possible) */
293         SKBTX_WIFI_STATUS = 1 << 4,
294 
295         /* This indicates at least one fragment might be overwritten
296          * (as in vmsplice(), sendfile() ...)
297          * If we need to compute a TX checksum, we'll need to copy
298          * all frags to avoid possible bad checksum
299          */
300         SKBTX_SHARED_FRAG = 1 << 5,
301 
302         /* generate software time stamp when entering packet scheduling */
303         SKBTX_SCHED_TSTAMP = 1 << 6,
304 
305         /* generate software timestamp on peer data acknowledgment */
306         SKBTX_ACK_TSTAMP = 1 << 7,
307 };
308 
309 #define SKBTX_ANY_SW_TSTAMP     (SKBTX_SW_TSTAMP    | \
310                                  SKBTX_SCHED_TSTAMP | \
311                                  SKBTX_ACK_TSTAMP)
312 #define SKBTX_ANY_TSTAMP        (SKBTX_HW_TSTAMP | SKBTX_ANY_SW_TSTAMP)
313 
314 /*
315  * The callback notifies userspace to release buffers when skb DMA is done in
316  * lower device, the skb last reference should be 0 when calling this.
317  * The zerocopy_success argument is true if zero copy transmit occurred,
318  * false on data copy or out of memory error caused by data copy attempt.
319  * The ctx field is used to track device context.
320  * The desc field is used to track userspace buffer index.
321  */
322 struct ubuf_info {
323         void (*callback)(struct ubuf_info *, bool zerocopy_success);
324         void *ctx;
325         unsigned long desc;
326 };
327 
328 /* This data is invariant across clones and lives at
329  * the end of the header data, ie. at skb->end.
330  */
331 struct skb_shared_info {
332         unsigned char   nr_frags;
333         __u8            tx_flags;
334         unsigned short  gso_size;
335         /* Warning: this field is not always filled in (UFO)! */
336         unsigned short  gso_segs;
337         unsigned short  gso_type;
338         struct sk_buff  *frag_list;
339         struct skb_shared_hwtstamps hwtstamps;
340         u32             tskey;
341         __be32          ip6_frag_id;
342 
343         /*
344          * Warning : all fields before dataref are cleared in __alloc_skb()
345          */
346         atomic_t        dataref;
347 
348         /* Intermediate layers must ensure that destructor_arg
349          * remains valid until skb destructor */
350         void *          destructor_arg;
351 
352         /* must be last field, see pskb_expand_head() */
353         skb_frag_t      frags[MAX_SKB_FRAGS];
354 };
355 
356 /* We divide dataref into two halves.  The higher 16 bits hold references
357  * to the payload part of skb->data.  The lower 16 bits hold references to
358  * the entire skb->data.  A clone of a headerless skb holds the length of
359  * the header in skb->hdr_len.
360  *
361  * All users must obey the rule that the skb->data reference count must be
362  * greater than or equal to the payload reference count.
363  *
364  * Holding a reference to the payload part means that the user does not
365  * care about modifications to the header part of skb->data.
366  */
367 #define SKB_DATAREF_SHIFT 16
368 #define SKB_DATAREF_MASK ((1 << SKB_DATAREF_SHIFT) - 1)
369 
370 
371 enum {
372         SKB_FCLONE_UNAVAILABLE, /* skb has no fclone (from head_cache) */
373         SKB_FCLONE_ORIG,        /* orig skb (from fclone_cache) */
374         SKB_FCLONE_CLONE,       /* companion fclone skb (from fclone_cache) */
375 };
376 
377 enum {
378         SKB_GSO_TCPV4 = 1 << 0,
379         SKB_GSO_UDP = 1 << 1,
380 
381         /* This indicates the skb is from an untrusted source. */
382         SKB_GSO_DODGY = 1 << 2,
383 
384         /* This indicates the tcp segment has CWR set. */
385         SKB_GSO_TCP_ECN = 1 << 3,
386 
387         SKB_GSO_TCPV6 = 1 << 4,
388 
389         SKB_GSO_FCOE = 1 << 5,
390 
391         SKB_GSO_GRE = 1 << 6,
392 
393         SKB_GSO_GRE_CSUM = 1 << 7,
394 
395         SKB_GSO_IPIP = 1 << 8,
396 
397         SKB_GSO_SIT = 1 << 9,
398 
399         SKB_GSO_UDP_TUNNEL = 1 << 10,
400 
401         SKB_GSO_UDP_TUNNEL_CSUM = 1 << 11,
402 
403         SKB_GSO_TUNNEL_REMCSUM = 1 << 12,
404 };
405 
406 #if BITS_PER_LONG > 32
407 #define NET_SKBUFF_DATA_USES_OFFSET 1
408 #endif
409 
410 #ifdef NET_SKBUFF_DATA_USES_OFFSET
411 typedef unsigned int sk_buff_data_t;
412 #else
413 typedef unsigned char *sk_buff_data_t;
414 #endif
415 
416 /**
417  * struct skb_mstamp - multi resolution time stamps
418  * @stamp_us: timestamp in us resolution
419  * @stamp_jiffies: timestamp in jiffies
420  */
421 struct skb_mstamp {
422         union {
423                 u64             v64;
424                 struct {
425                         u32     stamp_us;
426                         u32     stamp_jiffies;
427                 };
428         };
429 };
430 
431 /**
432  * skb_mstamp_get - get current timestamp
433  * @cl: place to store timestamps
434  */
435 static inline void skb_mstamp_get(struct skb_mstamp *cl)
436 {
437         u64 val = local_clock();
438 
439         do_div(val, NSEC_PER_USEC);
440         cl->stamp_us = (u32)val;
441         cl->stamp_jiffies = (u32)jiffies;
442 }
443 
444 /**
445  * skb_mstamp_delta - compute the difference in usec between two skb_mstamp
446  * @t1: pointer to newest sample
447  * @t0: pointer to oldest sample
448  */
449 static inline u32 skb_mstamp_us_delta(const struct skb_mstamp *t1,
450                                       const struct skb_mstamp *t0)
451 {
452         s32 delta_us = t1->stamp_us - t0->stamp_us;
453         u32 delta_jiffies = t1->stamp_jiffies - t0->stamp_jiffies;
454 
455         /* If delta_us is negative, this might be because interval is too big,
456          * or local_clock() drift is too big : fallback using jiffies.
457          */
458         if (delta_us <= 0 ||
459             delta_jiffies >= (INT_MAX / (USEC_PER_SEC / HZ)))
460 
461                 delta_us = jiffies_to_usecs(delta_jiffies);
462 
463         return delta_us;
464 }
465 
466 static inline bool skb_mstamp_after(const struct skb_mstamp *t1,
467                                     const struct skb_mstamp *t0)
468 {
469         s32 diff = t1->stamp_jiffies - t0->stamp_jiffies;
470 
471         if (!diff)
472                 diff = t1->stamp_us - t0->stamp_us;
473         return diff > 0;
474 }
475 
476 /** 
477  *      struct sk_buff - socket buffer
478  *      @next: Next buffer in list
479  *      @prev: Previous buffer in list
480  *      @tstamp: Time we arrived/left
481  *      @rbnode: RB tree node, alternative to next/prev for netem/tcp
482  *      @sk: Socket we are owned by
483  *      @dev: Device we arrived on/are leaving by
484  *      @cb: Control buffer. Free for use by every layer. Put private vars here
485  *      @_skb_refdst: destination entry (with norefcount bit)
486  *      @sp: the security path, used for xfrm
487  *      @len: Length of actual data
488  *      @data_len: Data length
489  *      @mac_len: Length of link layer header
490  *      @hdr_len: writable header length of cloned skb
491  *      @csum: Checksum (must include start/offset pair)
492  *      @csum_start: Offset from skb->head where checksumming should start
493  *      @csum_offset: Offset from csum_start where checksum should be stored
494  *      @priority: Packet queueing priority
495  *      @ignore_df: allow local fragmentation
496  *      @cloned: Head may be cloned (check refcnt to be sure)
497  *      @ip_summed: Driver fed us an IP checksum
498  *      @nohdr: Payload reference only, must not modify header
499  *      @nfctinfo: Relationship of this skb to the connection
500  *      @pkt_type: Packet class
501  *      @fclone: skbuff clone status
502  *      @ipvs_property: skbuff is owned by ipvs
503  *      @peeked: this packet has been seen already, so stats have been
504  *              done for it, don't do them again
505  *      @nf_trace: netfilter packet trace flag
506  *      @protocol: Packet protocol from driver
507  *      @destructor: Destruct function
508  *      @nfct: Associated connection, if any
509  *      @nf_bridge: Saved data about a bridged frame - see br_netfilter.c
510  *      @skb_iif: ifindex of device we arrived on
511  *      @tc_index: Traffic control index
512  *      @tc_verd: traffic control verdict
513  *      @hash: the packet hash
514  *      @queue_mapping: Queue mapping for multiqueue devices
515  *      @xmit_more: More SKBs are pending for this queue
516  *      @ndisc_nodetype: router type (from link layer)
517  *      @ooo_okay: allow the mapping of a socket to a queue to be changed
518  *      @l4_hash: indicate hash is a canonical 4-tuple hash over transport
519  *              ports.
520  *      @sw_hash: indicates hash was computed in software stack
521  *      @wifi_acked_valid: wifi_acked was set
522  *      @wifi_acked: whether frame was acked on wifi or not
523  *      @no_fcs:  Request NIC to treat last 4 bytes as Ethernet FCS
524   *     @napi_id: id of the NAPI struct this skb came from
525  *      @secmark: security marking
526  *      @offload_fwd_mark: fwding offload mark
527  *      @mark: Generic packet mark
528  *      @vlan_proto: vlan encapsulation protocol
529  *      @vlan_tci: vlan tag control information
530  *      @inner_protocol: Protocol (encapsulation)
531  *      @inner_transport_header: Inner transport layer header (encapsulation)
532  *      @inner_network_header: Network layer header (encapsulation)
533  *      @inner_mac_header: Link layer header (encapsulation)
534  *      @transport_header: Transport layer header
535  *      @network_header: Network layer header
536  *      @mac_header: Link layer header
537  *      @tail: Tail pointer
538  *      @end: End pointer
539  *      @head: Head of buffer
540  *      @data: Data head pointer
541  *      @truesize: Buffer size
542  *      @users: User count - see {datagram,tcp}.c
543  */
544 
545 struct sk_buff {
546         union {
547                 struct {
548                         /* These two members must be first. */
549                         struct sk_buff          *next;
550                         struct sk_buff          *prev;
551 
552                         union {
553                                 ktime_t         tstamp;
554                                 struct skb_mstamp skb_mstamp;
555                         };
556                 };
557                 struct rb_node  rbnode; /* used in netem & tcp stack */
558         };
559         struct sock             *sk;
560         struct net_device       *dev;
561 
562         /*
563          * This is the control buffer. It is free to use for every
564          * layer. Please put your private variables there. If you
565          * want to keep them across layers you have to do a skb_clone()
566          * first. This is owned by whoever has the skb queued ATM.
567          */
568         char                    cb[48] __aligned(8);
569 
570         unsigned long           _skb_refdst;
571         void                    (*destructor)(struct sk_buff *skb);
572 #ifdef CONFIG_XFRM
573         struct  sec_path        *sp;
574 #endif
575 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
576         struct nf_conntrack     *nfct;
577 #endif
578 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
579         struct nf_bridge_info   *nf_bridge;
580 #endif
581         unsigned int            len,
582                                 data_len;
583         __u16                   mac_len,
584                                 hdr_len;
585 
586         /* Following fields are _not_ copied in __copy_skb_header()
587          * Note that queue_mapping is here mostly to fill a hole.
588          */
589         kmemcheck_bitfield_begin(flags1);
590         __u16                   queue_mapping;
591         __u8                    cloned:1,
592                                 nohdr:1,
593                                 fclone:2,
594                                 peeked:1,
595                                 head_frag:1,
596                                 xmit_more:1;
597         /* one bit hole */
598         kmemcheck_bitfield_end(flags1);
599 
600         /* fields enclosed in headers_start/headers_end are copied
601          * using a single memcpy() in __copy_skb_header()
602          */
603         /* private: */
604         __u32                   headers_start[0];
605         /* public: */
606 
607 /* if you move pkt_type around you also must adapt those constants */
608 #ifdef __BIG_ENDIAN_BITFIELD
609 #define PKT_TYPE_MAX    (7 << 5)
610 #else
611 #define PKT_TYPE_MAX    7
612 #endif
613 #define PKT_TYPE_OFFSET()       offsetof(struct sk_buff, __pkt_type_offset)
614 
615         __u8                    __pkt_type_offset[0];
616         __u8                    pkt_type:3;
617         __u8                    pfmemalloc:1;
618         __u8                    ignore_df:1;
619         __u8                    nfctinfo:3;
620 
621         __u8                    nf_trace:1;
622         __u8                    ip_summed:2;
623         __u8                    ooo_okay:1;
624         __u8                    l4_hash:1;
625         __u8                    sw_hash:1;
626         __u8                    wifi_acked_valid:1;
627         __u8                    wifi_acked:1;
628 
629         __u8                    no_fcs:1;
630         /* Indicates the inner headers are valid in the skbuff. */
631         __u8                    encapsulation:1;
632         __u8                    encap_hdr_csum:1;
633         __u8                    csum_valid:1;
634         __u8                    csum_complete_sw:1;
635         __u8                    csum_level:2;
636         __u8                    csum_bad:1;
637 
638 #ifdef CONFIG_IPV6_NDISC_NODETYPE
639         __u8                    ndisc_nodetype:2;
640 #endif
641         __u8                    ipvs_property:1;
642         __u8                    inner_protocol_type:1;
643         __u8                    remcsum_offload:1;
644         /* 3 or 5 bit hole */
645 
646 #ifdef CONFIG_NET_SCHED
647         __u16                   tc_index;       /* traffic control index */
648 #ifdef CONFIG_NET_CLS_ACT
649         __u16                   tc_verd;        /* traffic control verdict */
650 #endif
651 #endif
652 
653         union {
654                 __wsum          csum;
655                 struct {
656                         __u16   csum_start;
657                         __u16   csum_offset;
658                 };
659         };
660         __u32                   priority;
661         int                     skb_iif;
662         __u32                   hash;
663         __be16                  vlan_proto;
664         __u16                   vlan_tci;
665 #if defined(CONFIG_NET_RX_BUSY_POLL) || defined(CONFIG_XPS)
666         union {
667                 unsigned int    napi_id;
668                 unsigned int    sender_cpu;
669         };
670 #endif
671         union {
672 #ifdef CONFIG_NETWORK_SECMARK
673                 __u32           secmark;
674 #endif
675 #ifdef CONFIG_NET_SWITCHDEV
676                 __u32           offload_fwd_mark;
677 #endif
678         };
679 
680         union {
681                 __u32           mark;
682                 __u32           reserved_tailroom;
683         };
684 
685         union {
686                 __be16          inner_protocol;
687                 __u8            inner_ipproto;
688         };
689 
690         __u16                   inner_transport_header;
691         __u16                   inner_network_header;
692         __u16                   inner_mac_header;
693 
694         __be16                  protocol;
695         __u16                   transport_header;
696         __u16                   network_header;
697         __u16                   mac_header;
698 
699         /* private: */
700         __u32                   headers_end[0];
701         /* public: */
702 
703         /* These elements must be at the end, see alloc_skb() for details.  */
704         sk_buff_data_t          tail;
705         sk_buff_data_t          end;
706         unsigned char           *head,
707                                 *data;
708         unsigned int            truesize;
709         atomic_t                users;
710 };
711 
712 #ifdef __KERNEL__
713 /*
714  *      Handling routines are only of interest to the kernel
715  */
716 #include <linux/slab.h>
717 
718 
719 #define SKB_ALLOC_FCLONE        0x01
720 #define SKB_ALLOC_RX            0x02
721 #define SKB_ALLOC_NAPI          0x04
722 
723 /* Returns true if the skb was allocated from PFMEMALLOC reserves */
724 static inline bool skb_pfmemalloc(const struct sk_buff *skb)
725 {
726         return unlikely(skb->pfmemalloc);
727 }
728 
729 /*
730  * skb might have a dst pointer attached, refcounted or not.
731  * _skb_refdst low order bit is set if refcount was _not_ taken
732  */
733 #define SKB_DST_NOREF   1UL
734 #define SKB_DST_PTRMASK ~(SKB_DST_NOREF)
735 
736 /**
737  * skb_dst - returns skb dst_entry
738  * @skb: buffer
739  *
740  * Returns skb dst_entry, regardless of reference taken or not.
741  */
742 static inline struct dst_entry *skb_dst(const struct sk_buff *skb)
743 {
744         /* If refdst was not refcounted, check we still are in a 
745          * rcu_read_lock section
746          */
747         WARN_ON((skb->_skb_refdst & SKB_DST_NOREF) &&
748                 !rcu_read_lock_held() &&
749                 !rcu_read_lock_bh_held());
750         return (struct dst_entry *)(skb->_skb_refdst & SKB_DST_PTRMASK);
751 }
752 
753 /**
754  * skb_dst_set - sets skb dst
755  * @skb: buffer
756  * @dst: dst entry
757  *
758  * Sets skb dst, assuming a reference was taken on dst and should
759  * be released by skb_dst_drop()
760  */
761 static inline void skb_dst_set(struct sk_buff *skb, struct dst_entry *dst)
762 {
763         skb->_skb_refdst = (unsigned long)dst;
764 }
765 
766 /**
767  * skb_dst_set_noref - sets skb dst, hopefully, without taking reference
768  * @skb: buffer
769  * @dst: dst entry
770  *
771  * Sets skb dst, assuming a reference was not taken on dst.
772  * If dst entry is cached, we do not take reference and dst_release
773  * will be avoided by refdst_drop. If dst entry is not cached, we take
774  * reference, so that last dst_release can destroy the dst immediately.
775  */
776 static inline void skb_dst_set_noref(struct sk_buff *skb, struct dst_entry *dst)
777 {
778         WARN_ON(!rcu_read_lock_held() && !rcu_read_lock_bh_held());
779         skb->_skb_refdst = (unsigned long)dst | SKB_DST_NOREF;
780 }
781 
782 /**
783  * skb_dst_is_noref - Test if skb dst isn't refcounted
784  * @skb: buffer
785  */
786 static inline bool skb_dst_is_noref(const struct sk_buff *skb)
787 {
788         return (skb->_skb_refdst & SKB_DST_NOREF) && skb_dst(skb);
789 }
790 
791 static inline struct rtable *skb_rtable(const struct sk_buff *skb)
792 {
793         return (struct rtable *)skb_dst(skb);
794 }
795 
796 void kfree_skb(struct sk_buff *skb);
797 void kfree_skb_list(struct sk_buff *segs);
798 void skb_tx_error(struct sk_buff *skb);
799 void consume_skb(struct sk_buff *skb);
800 void  __kfree_skb(struct sk_buff *skb);
801 extern struct kmem_cache *skbuff_head_cache;
802 
803 void kfree_skb_partial(struct sk_buff *skb, bool head_stolen);
804 bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from,
805                       bool *fragstolen, int *delta_truesize);
806 
807 struct sk_buff *__alloc_skb(unsigned int size, gfp_t priority, int flags,
808                             int node);
809 struct sk_buff *__build_skb(void *data, unsigned int frag_size);
810 struct sk_buff *build_skb(void *data, unsigned int frag_size);
811 static inline struct sk_buff *alloc_skb(unsigned int size,
812                                         gfp_t priority)
813 {
814         return __alloc_skb(size, priority, 0, NUMA_NO_NODE);
815 }
816 
817 struct sk_buff *alloc_skb_with_frags(unsigned long header_len,
818                                      unsigned long data_len,
819                                      int max_page_order,
820                                      int *errcode,
821                                      gfp_t gfp_mask);
822 
823 /* Layout of fast clones : [skb1][skb2][fclone_ref] */
824 struct sk_buff_fclones {
825         struct sk_buff  skb1;
826 
827         struct sk_buff  skb2;
828 
829         atomic_t        fclone_ref;
830 };
831 
832 /**
833  *      skb_fclone_busy - check if fclone is busy
834  *      @skb: buffer
835  *
836  * Returns true is skb is a fast clone, and its clone is not freed.
837  * Some drivers call skb_orphan() in their ndo_start_xmit(),
838  * so we also check that this didnt happen.
839  */
840 static inline bool skb_fclone_busy(const struct sock *sk,
841                                    const struct sk_buff *skb)
842 {
843         const struct sk_buff_fclones *fclones;
844 
845         fclones = container_of(skb, struct sk_buff_fclones, skb1);
846 
847         return skb->fclone == SKB_FCLONE_ORIG &&
848                atomic_read(&fclones->fclone_ref) > 1 &&
849                fclones->skb2.sk == sk;
850 }
851 
852 static inline struct sk_buff *alloc_skb_fclone(unsigned int size,
853                                                gfp_t priority)
854 {
855         return __alloc_skb(size, priority, SKB_ALLOC_FCLONE, NUMA_NO_NODE);
856 }
857 
858 struct sk_buff *__alloc_skb_head(gfp_t priority, int node);
859 static inline struct sk_buff *alloc_skb_head(gfp_t priority)
860 {
861         return __alloc_skb_head(priority, -1);
862 }
863 
864 struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src);
865 int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask);
866 struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t priority);
867 struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t priority);
868 struct sk_buff *__pskb_copy_fclone(struct sk_buff *skb, int headroom,
869                                    gfp_t gfp_mask, bool fclone);
870 static inline struct sk_buff *__pskb_copy(struct sk_buff *skb, int headroom,
871                                           gfp_t gfp_mask)
872 {
873         return __pskb_copy_fclone(skb, headroom, gfp_mask, false);
874 }
875 
876 int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail, gfp_t gfp_mask);
877 struct sk_buff *skb_realloc_headroom(struct sk_buff *skb,
878                                      unsigned int headroom);
879 struct sk_buff *skb_copy_expand(const struct sk_buff *skb, int newheadroom,
880                                 int newtailroom, gfp_t priority);
881 int skb_to_sgvec_nomark(struct sk_buff *skb, struct scatterlist *sg,
882                         int offset, int len);
883 int skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset,
884                  int len);
885 int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer);
886 int skb_pad(struct sk_buff *skb, int pad);
887 #define dev_kfree_skb(a)        consume_skb(a)
888 
889 int skb_append_datato_frags(struct sock *sk, struct sk_buff *skb,
890                             int getfrag(void *from, char *to, int offset,
891                                         int len, int odd, struct sk_buff *skb),
892                             void *from, int length);
893 
894 int skb_append_pagefrags(struct sk_buff *skb, struct page *page,
895                          int offset, size_t size);
896 
897 struct skb_seq_state {
898         __u32           lower_offset;
899         __u32           upper_offset;
900         __u32           frag_idx;
901         __u32           stepped_offset;
902         struct sk_buff  *root_skb;
903         struct sk_buff  *cur_skb;
904         __u8            *frag_data;
905 };
906 
907 void skb_prepare_seq_read(struct sk_buff *skb, unsigned int from,
908                           unsigned int to, struct skb_seq_state *st);
909 unsigned int skb_seq_read(unsigned int consumed, const u8 **data,
910                           struct skb_seq_state *st);
911 void skb_abort_seq_read(struct skb_seq_state *st);
912 
913 unsigned int skb_find_text(struct sk_buff *skb, unsigned int from,
914                            unsigned int to, struct ts_config *config);
915 
916 /*
917  * Packet hash types specify the type of hash in skb_set_hash.
918  *
919  * Hash types refer to the protocol layer addresses which are used to
920  * construct a packet's hash. The hashes are used to differentiate or identify
921  * flows of the protocol layer for the hash type. Hash types are either
922  * layer-2 (L2), layer-3 (L3), or layer-4 (L4).
923  *
924  * Properties of hashes:
925  *
926  * 1) Two packets in different flows have different hash values
927  * 2) Two packets in the same flow should have the same hash value
928  *
929  * A hash at a higher layer is considered to be more specific. A driver should
930  * set the most specific hash possible.
931  *
932  * A driver cannot indicate a more specific hash than the layer at which a hash
933  * was computed. For instance an L3 hash cannot be set as an L4 hash.
934  *
935  * A driver may indicate a hash level which is less specific than the
936  * actual layer the hash was computed on. For instance, a hash computed
937  * at L4 may be considered an L3 hash. This should only be done if the
938  * driver can't unambiguously determine that the HW computed the hash at
939  * the higher layer. Note that the "should" in the second property above
940  * permits this.
941  */
942 enum pkt_hash_types {
943         PKT_HASH_TYPE_NONE,     /* Undefined type */
944         PKT_HASH_TYPE_L2,       /* Input: src_MAC, dest_MAC */
945         PKT_HASH_TYPE_L3,       /* Input: src_IP, dst_IP */
946         PKT_HASH_TYPE_L4,       /* Input: src_IP, dst_IP, src_port, dst_port */
947 };
948 
949 static inline void skb_clear_hash(struct sk_buff *skb)
950 {
951         skb->hash = 0;
952         skb->sw_hash = 0;
953         skb->l4_hash = 0;
954 }
955 
956 static inline void skb_clear_hash_if_not_l4(struct sk_buff *skb)
957 {
958         if (!skb->l4_hash)
959                 skb_clear_hash(skb);
960 }
961 
962 static inline void
963 __skb_set_hash(struct sk_buff *skb, __u32 hash, bool is_sw, bool is_l4)
964 {
965         skb->l4_hash = is_l4;
966         skb->sw_hash = is_sw;
967         skb->hash = hash;
968 }
969 
970 static inline void
971 skb_set_hash(struct sk_buff *skb, __u32 hash, enum pkt_hash_types type)
972 {
973         /* Used by drivers to set hash from HW */
974         __skb_set_hash(skb, hash, false, type == PKT_HASH_TYPE_L4);
975 }
976 
977 static inline void
978 __skb_set_sw_hash(struct sk_buff *skb, __u32 hash, bool is_l4)
979 {
980         __skb_set_hash(skb, hash, true, is_l4);
981 }
982 
983 void __skb_get_hash(struct sk_buff *skb);
984 u32 skb_get_poff(const struct sk_buff *skb);
985 u32 __skb_get_poff(const struct sk_buff *skb, void *data,
986                    const struct flow_keys *keys, int hlen);
987 __be32 __skb_flow_get_ports(const struct sk_buff *skb, int thoff, u8 ip_proto,
988                             void *data, int hlen_proto);
989 
990 static inline __be32 skb_flow_get_ports(const struct sk_buff *skb,
991                                         int thoff, u8 ip_proto)
992 {
993         return __skb_flow_get_ports(skb, thoff, ip_proto, NULL, 0);
994 }
995 
996 void skb_flow_dissector_init(struct flow_dissector *flow_dissector,
997                              const struct flow_dissector_key *key,
998                              unsigned int key_count);
999 
1000 bool __skb_flow_dissect(const struct sk_buff *skb,
1001                         struct flow_dissector *flow_dissector,
1002                         void *target_container,
1003                         void *data, __be16 proto, int nhoff, int hlen,
1004                         unsigned int flags);
1005 
1006 static inline bool skb_flow_dissect(const struct sk_buff *skb,
1007                                     struct flow_dissector *flow_dissector,
1008                                     void *target_container, unsigned int flags)
1009 {
1010         return __skb_flow_dissect(skb, flow_dissector, target_container,
1011                                   NULL, 0, 0, 0, flags);
1012 }
1013 
1014 static inline bool skb_flow_dissect_flow_keys(const struct sk_buff *skb,
1015                                               struct flow_keys *flow,
1016                                               unsigned int flags)
1017 {
1018         memset(flow, 0, sizeof(*flow));
1019         return __skb_flow_dissect(skb, &flow_keys_dissector, flow,
1020                                   NULL, 0, 0, 0, flags);
1021 }
1022 
1023 static inline bool skb_flow_dissect_flow_keys_buf(struct flow_keys *flow,
1024                                                   void *data, __be16 proto,
1025                                                   int nhoff, int hlen,
1026                                                   unsigned int flags)
1027 {
1028         memset(flow, 0, sizeof(*flow));
1029         return __skb_flow_dissect(NULL, &flow_keys_buf_dissector, flow,
1030                                   data, proto, nhoff, hlen, flags);
1031 }
1032 
1033 static inline __u32 skb_get_hash(struct sk_buff *skb)
1034 {
1035         if (!skb->l4_hash && !skb->sw_hash)
1036                 __skb_get_hash(skb);
1037 
1038         return skb->hash;
1039 }
1040 
1041 __u32 __skb_get_hash_flowi6(struct sk_buff *skb, const struct flowi6 *fl6);
1042 
1043 static inline __u32 skb_get_hash_flowi6(struct sk_buff *skb, const struct flowi6 *fl6)
1044 {
1045         if (!skb->l4_hash && !skb->sw_hash) {
1046                 struct flow_keys keys;
1047                 __u32 hash = __get_hash_from_flowi6(fl6, &keys);
1048 
1049                 __skb_set_sw_hash(skb, hash, flow_keys_have_l4(&keys));
1050         }
1051 
1052         return skb->hash;
1053 }
1054 
1055 __u32 __skb_get_hash_flowi4(struct sk_buff *skb, const struct flowi4 *fl);
1056 
1057 static inline __u32 skb_get_hash_flowi4(struct sk_buff *skb, const struct flowi4 *fl4)
1058 {
1059         if (!skb->l4_hash && !skb->sw_hash) {
1060                 struct flow_keys keys;
1061                 __u32 hash = __get_hash_from_flowi4(fl4, &keys);
1062 
1063                 __skb_set_sw_hash(skb, hash, flow_keys_have_l4(&keys));
1064         }
1065 
1066         return skb->hash;
1067 }
1068 
1069 __u32 skb_get_hash_perturb(const struct sk_buff *skb, u32 perturb);
1070 
1071 static inline __u32 skb_get_hash_raw(const struct sk_buff *skb)
1072 {
1073         return skb->hash;
1074 }
1075 
1076 static inline void skb_copy_hash(struct sk_buff *to, const struct sk_buff *from)
1077 {
1078         to->hash = from->hash;
1079         to->sw_hash = from->sw_hash;
1080         to->l4_hash = from->l4_hash;
1081 };
1082 
1083 static inline void skb_sender_cpu_clear(struct sk_buff *skb)
1084 {
1085 #ifdef CONFIG_XPS
1086         skb->sender_cpu = 0;
1087 #endif
1088 }
1089 
1090 #ifdef NET_SKBUFF_DATA_USES_OFFSET
1091 static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
1092 {
1093         return skb->head + skb->end;
1094 }
1095 
1096 static inline unsigned int skb_end_offset(const struct sk_buff *skb)
1097 {
1098         return skb->end;
1099 }
1100 #else
1101 static inline unsigned char *skb_end_pointer(const struct sk_buff *skb)
1102 {
1103         return skb->end;
1104 }
1105 
1106 static inline unsigned int skb_end_offset(const struct sk_buff *skb)
1107 {
1108         return skb->end - skb->head;
1109 }
1110 #endif
1111 
1112 /* Internal */
1113 #define skb_shinfo(SKB) ((struct skb_shared_info *)(skb_end_pointer(SKB)))
1114 
1115 static inline struct skb_shared_hwtstamps *skb_hwtstamps(struct sk_buff *skb)
1116 {
1117         return &skb_shinfo(skb)->hwtstamps;
1118 }
1119 
1120 /**
1121  *      skb_queue_empty - check if a queue is empty
1122  *      @list: queue head
1123  *
1124  *      Returns true if the queue is empty, false otherwise.
1125  */
1126 static inline int skb_queue_empty(const struct sk_buff_head *list)
1127 {
1128         return list->next == (const struct sk_buff *) list;
1129 }
1130 
1131 /**
1132  *      skb_queue_is_last - check if skb is the last entry in the queue
1133  *      @list: queue head
1134  *      @skb: buffer
1135  *
1136  *      Returns true if @skb is the last buffer on the list.
1137  */
1138 static inline bool skb_queue_is_last(const struct sk_buff_head *list,
1139                                      const struct sk_buff *skb)
1140 {
1141         return skb->next == (const struct sk_buff *) list;
1142 }
1143 
1144 /**
1145  *      skb_queue_is_first - check if skb is the first entry in the queue
1146  *      @list: queue head
1147  *      @skb: buffer
1148  *
1149  *      Returns true if @skb is the first buffer on the list.
1150  */
1151 static inline bool skb_queue_is_first(const struct sk_buff_head *list,
1152                                       const struct sk_buff *skb)
1153 {
1154         return skb->prev == (const struct sk_buff *) list;
1155 }
1156 
1157 /**
1158  *      skb_queue_next - return the next packet in the queue
1159  *      @list: queue head
1160  *      @skb: current buffer
1161  *
1162  *      Return the next packet in @list after @skb.  It is only valid to
1163  *      call this if skb_queue_is_last() evaluates to false.
1164  */
1165 static inline struct sk_buff *skb_queue_next(const struct sk_buff_head *list,
1166                                              const struct sk_buff *skb)
1167 {
1168         /* This BUG_ON may seem severe, but if we just return then we
1169          * are going to dereference garbage.
1170          */
1171         BUG_ON(skb_queue_is_last(list, skb));
1172         return skb->next;
1173 }
1174 
1175 /**
1176  *      skb_queue_prev - return the prev packet in the queue
1177  *      @list: queue head
1178  *      @skb: current buffer
1179  *
1180  *      Return the prev packet in @list before @skb.  It is only valid to
1181  *      call this if skb_queue_is_first() evaluates to false.
1182  */
1183 static inline struct sk_buff *skb_queue_prev(const struct sk_buff_head *list,
1184                                              const struct sk_buff *skb)
1185 {
1186         /* This BUG_ON may seem severe, but if we just return then we
1187          * are going to dereference garbage.
1188          */
1189         BUG_ON(skb_queue_is_first(list, skb));
1190         return skb->prev;
1191 }
1192 
1193 /**
1194  *      skb_get - reference buffer
1195  *      @skb: buffer to reference
1196  *
1197  *      Makes another reference to a socket buffer and returns a pointer
1198  *      to the buffer.
1199  */
1200 static inline struct sk_buff *skb_get(struct sk_buff *skb)
1201 {
1202         atomic_inc(&skb->users);
1203         return skb;
1204 }
1205 
1206 /*
1207  * If users == 1, we are the only owner and are can avoid redundant
1208  * atomic change.
1209  */
1210 
1211 /**
1212  *      skb_cloned - is the buffer a clone
1213  *      @skb: buffer to check
1214  *
1215  *      Returns true if the buffer was generated with skb_clone() and is
1216  *      one of multiple shared copies of the buffer. Cloned buffers are
1217  *      shared data so must not be written to under normal circumstances.
1218  */
1219 static inline int skb_cloned(const struct sk_buff *skb)
1220 {
1221         return skb->cloned &&
1222                (atomic_read(&skb_shinfo(skb)->dataref) & SKB_DATAREF_MASK) != 1;
1223 }
1224 
1225 static inline int skb_unclone(struct sk_buff *skb, gfp_t pri)
1226 {
1227         might_sleep_if(gfpflags_allow_blocking(pri));
1228 
1229         if (skb_cloned(skb))
1230                 return pskb_expand_head(skb, 0, 0, pri);
1231 
1232         return 0;
1233 }
1234 
1235 /**
1236  *      skb_header_cloned - is the header a clone
1237  *      @skb: buffer to check
1238  *
1239  *      Returns true if modifying the header part of the buffer requires
1240  *      the data to be copied.
1241  */
1242 static inline int skb_header_cloned(const struct sk_buff *skb)
1243 {
1244         int dataref;
1245 
1246         if (!skb->cloned)
1247                 return 0;
1248 
1249         dataref = atomic_read(&skb_shinfo(skb)->dataref);
1250         dataref = (dataref & SKB_DATAREF_MASK) - (dataref >> SKB_DATAREF_SHIFT);
1251         return dataref != 1;
1252 }
1253 
1254 /**
1255  *      skb_header_release - release reference to header
1256  *      @skb: buffer to operate on
1257  *
1258  *      Drop a reference to the header part of the buffer.  This is done
1259  *      by acquiring a payload reference.  You must not read from the header
1260  *      part of skb->data after this.
1261  *      Note : Check if you can use __skb_header_release() instead.
1262  */
1263 static inline void skb_header_release(struct sk_buff *skb)
1264 {
1265         BUG_ON(skb->nohdr);
1266         skb->nohdr = 1;
1267         atomic_add(1 << SKB_DATAREF_SHIFT, &skb_shinfo(skb)->dataref);
1268 }
1269 
1270 /**
1271  *      __skb_header_release - release reference to header
1272  *      @skb: buffer to operate on
1273  *
1274  *      Variant of skb_header_release() assuming skb is private to caller.
1275  *      We can avoid one atomic operation.
1276  */
1277 static inline void __skb_header_release(struct sk_buff *skb)
1278 {
1279         skb->nohdr = 1;
1280         atomic_set(&skb_shinfo(skb)->dataref, 1 + (1 << SKB_DATAREF_SHIFT));
1281 }
1282 
1283 
1284 /**
1285  *      skb_shared - is the buffer shared
1286  *      @skb: buffer to check
1287  *
1288  *      Returns true if more than one person has a reference to this
1289  *      buffer.
1290  */
1291 static inline int skb_shared(const struct sk_buff *skb)
1292 {
1293         return atomic_read(&skb->users) != 1;
1294 }
1295 
1296 /**
1297  *      skb_share_check - check if buffer is shared and if so clone it
1298  *      @skb: buffer to check
1299  *      @pri: priority for memory allocation
1300  *
1301  *      If the buffer is shared the buffer is cloned and the old copy
1302  *      drops a reference. A new clone with a single reference is returned.
1303  *      If the buffer is not shared the original buffer is returned. When
1304  *      being called from interrupt status or with spinlocks held pri must
1305  *      be GFP_ATOMIC.
1306  *
1307  *      NULL is returned on a memory allocation failure.
1308  */
1309 static inline struct sk_buff *skb_share_check(struct sk_buff *skb, gfp_t pri)
1310 {
1311         might_sleep_if(gfpflags_allow_blocking(pri));
1312         if (skb_shared(skb)) {
1313                 struct sk_buff *nskb = skb_clone(skb, pri);
1314 
1315                 if (likely(nskb))
1316                         consume_skb(skb);
1317                 else
1318                         kfree_skb(skb);
1319                 skb = nskb;
1320         }
1321         return skb;
1322 }
1323 
1324 /*
1325  *      Copy shared buffers into a new sk_buff. We effectively do COW on
1326  *      packets to handle cases where we have a local reader and forward
1327  *      and a couple of other messy ones. The normal one is tcpdumping
1328  *      a packet thats being forwarded.
1329  */
1330 
1331 /**
1332  *      skb_unshare - make a copy of a shared buffer
1333  *      @skb: buffer to check
1334  *      @pri: priority for memory allocation
1335  *
1336  *      If the socket buffer is a clone then this function creates a new
1337  *      copy of the data, drops a reference count on the old copy and returns
1338  *      the new copy with the reference count at 1. If the buffer is not a clone
1339  *      the original buffer is returned. When called with a spinlock held or
1340  *      from interrupt state @pri must be %GFP_ATOMIC
1341  *
1342  *      %NULL is returned on a memory allocation failure.
1343  */
1344 static inline struct sk_buff *skb_unshare(struct sk_buff *skb,
1345                                           gfp_t pri)
1346 {
1347         might_sleep_if(gfpflags_allow_blocking(pri));
1348         if (skb_cloned(skb)) {
1349                 struct sk_buff *nskb = skb_copy(skb, pri);
1350 
1351                 /* Free our shared copy */
1352                 if (likely(nskb))
1353                         consume_skb(skb);
1354                 else
1355                         kfree_skb(skb);
1356                 skb = nskb;
1357         }
1358         return skb;
1359 }
1360 
1361 /**
1362  *      skb_peek - peek at the head of an &sk_buff_head
1363  *      @list_: list to peek at
1364  *
1365  *      Peek an &sk_buff. Unlike most other operations you _MUST_
1366  *      be careful with this one. A peek leaves the buffer on the
1367  *      list and someone else may run off with it. You must hold
1368  *      the appropriate locks or have a private queue to do this.
1369  *
1370  *      Returns %NULL for an empty list or a pointer to the head element.
1371  *      The reference count is not incremented and the reference is therefore
1372  *      volatile. Use with caution.
1373  */
1374 static inline struct sk_buff *skb_peek(const struct sk_buff_head *list_)
1375 {
1376         struct sk_buff *skb = list_->next;
1377 
1378         if (skb == (struct sk_buff *)list_)
1379                 skb = NULL;
1380         return skb;
1381 }
1382 
1383 /**
1384  *      skb_peek_next - peek skb following the given one from a queue
1385  *      @skb: skb to start from
1386  *      @list_: list to peek at
1387  *
1388  *      Returns %NULL when the end of the list is met or a pointer to the
1389  *      next element. The reference count is not incremented and the
1390  *      reference is therefore volatile. Use with caution.
1391  */
1392 static inline struct sk_buff *skb_peek_next(struct sk_buff *skb,
1393                 const struct sk_buff_head *list_)
1394 {
1395         struct sk_buff *next = skb->next;
1396 
1397         if (next == (struct sk_buff *)list_)
1398                 next = NULL;
1399         return next;
1400 }
1401 
1402 /**
1403  *      skb_peek_tail - peek at the tail of an &sk_buff_head
1404  *      @list_: list to peek at
1405  *
1406  *      Peek an &sk_buff. Unlike most other operations you _MUST_
1407  *      be careful with this one. A peek leaves the buffer on the
1408  *      list and someone else may run off with it. You must hold
1409  *      the appropriate locks or have a private queue to do this.
1410  *
1411  *      Returns %NULL for an empty list or a pointer to the tail element.
1412  *      The reference count is not incremented and the reference is therefore
1413  *      volatile. Use with caution.
1414  */
1415 static inline struct sk_buff *skb_peek_tail(const struct sk_buff_head *list_)
1416 {
1417         struct sk_buff *skb = list_->prev;
1418 
1419         if (skb == (struct sk_buff *)list_)
1420                 skb = NULL;
1421         return skb;
1422 
1423 }
1424 
1425 /**
1426  *      skb_queue_len   - get queue length
1427  *      @list_: list to measure
1428  *
1429  *      Return the length of an &sk_buff queue.
1430  */
1431 static inline __u32 skb_queue_len(const struct sk_buff_head *list_)
1432 {
1433         return list_->qlen;
1434 }
1435 
1436 /**
1437  *      __skb_queue_head_init - initialize non-spinlock portions of sk_buff_head
1438  *      @list: queue to initialize
1439  *
1440  *      This initializes only the list and queue length aspects of
1441  *      an sk_buff_head object.  This allows to initialize the list
1442  *      aspects of an sk_buff_head without reinitializing things like
1443  *      the spinlock.  It can also be used for on-stack sk_buff_head
1444  *      objects where the spinlock is known to not be used.
1445  */
1446 static inline void __skb_queue_head_init(struct sk_buff_head *list)
1447 {
1448         list->prev = list->next = (struct sk_buff *)list;
1449         list->qlen = 0;
1450 }
1451 
1452 /*
1453  * This function creates a split out lock class for each invocation;
1454  * this is needed for now since a whole lot of users of the skb-queue
1455  * infrastructure in drivers have different locking usage (in hardirq)
1456  * than the networking core (in softirq only). In the long run either the
1457  * network layer or drivers should need annotation to consolidate the
1458  * main types of usage into 3 classes.
1459  */
1460 static inline void skb_queue_head_init(struct sk_buff_head *list)
1461 {
1462         spin_lock_init(&list->lock);
1463         __skb_queue_head_init(list);
1464 }
1465 
1466 static inline void skb_queue_head_init_class(struct sk_buff_head *list,
1467                 struct lock_class_key *class)
1468 {
1469         skb_queue_head_init(list);
1470         lockdep_set_class(&list->lock, class);
1471 }
1472 
1473 /*
1474  *      Insert an sk_buff on a list.
1475  *
1476  *      The "__skb_xxxx()" functions are the non-atomic ones that
1477  *      can only be called with interrupts disabled.
1478  */
1479 void skb_insert(struct sk_buff *old, struct sk_buff *newsk,
1480                 struct sk_buff_head *list);
1481 static inline void __skb_insert(struct sk_buff *newsk,
1482                                 struct sk_buff *prev, struct sk_buff *next,
1483                                 struct sk_buff_head *list)
1484 {
1485         newsk->next = next;
1486         newsk->prev = prev;
1487         next->prev  = prev->next = newsk;
1488         list->qlen++;
1489 }
1490 
1491 static inline void __skb_queue_splice(const struct sk_buff_head *list,
1492                                       struct sk_buff *prev,
1493                                       struct sk_buff *next)
1494 {
1495         struct sk_buff *first = list->next;
1496         struct sk_buff *last = list->prev;
1497 
1498         first->prev = prev;
1499         prev->next = first;
1500 
1501         last->next = next;
1502         next->prev = last;
1503 }
1504 
1505 /**
1506  *      skb_queue_splice - join two skb lists, this is designed for stacks
1507  *      @list: the new list to add
1508  *      @head: the place to add it in the first list
1509  */
1510 static inline void skb_queue_splice(const struct sk_buff_head *list,
1511                                     struct sk_buff_head *head)
1512 {
1513         if (!skb_queue_empty(list)) {
1514                 __skb_queue_splice(list, (struct sk_buff *) head, head->next);
1515                 head->qlen += list->qlen;
1516         }
1517 }
1518 
1519 /**
1520  *      skb_queue_splice_init - join two skb lists and reinitialise the emptied list
1521  *      @list: the new list to add
1522  *      @head: the place to add it in the first list
1523  *
1524  *      The list at @list is reinitialised
1525  */
1526 static inline void skb_queue_splice_init(struct sk_buff_head *list,
1527                                          struct sk_buff_head *head)
1528 {
1529         if (!skb_queue_empty(list)) {
1530                 __skb_queue_splice(list, (struct sk_buff *) head, head->next);
1531                 head->qlen += list->qlen;
1532                 __skb_queue_head_init(list);
1533         }
1534 }
1535 
1536 /**
1537  *      skb_queue_splice_tail - join two skb lists, each list being a queue
1538  *      @list: the new list to add
1539  *      @head: the place to add it in the first list
1540  */
1541 static inline void skb_queue_splice_tail(const struct sk_buff_head *list,
1542                                          struct sk_buff_head *head)
1543 {
1544         if (!skb_queue_empty(list)) {
1545                 __skb_queue_splice(list, head->prev, (struct sk_buff *) head);
1546                 head->qlen += list->qlen;
1547         }
1548 }
1549 
1550 /**
1551  *      skb_queue_splice_tail_init - join two skb lists and reinitialise the emptied list
1552  *      @list: the new list to add
1553  *      @head: the place to add it in the first list
1554  *
1555  *      Each of the lists is a queue.
1556  *      The list at @list is reinitialised
1557  */
1558 static inline void skb_queue_splice_tail_init(struct sk_buff_head *list,
1559                                               struct sk_buff_head *head)
1560 {
1561         if (!skb_queue_empty(list)) {
1562                 __skb_queue_splice(list, head->prev, (struct sk_buff *) head);
1563                 head->qlen += list->qlen;
1564                 __skb_queue_head_init(list);
1565         }
1566 }
1567 
1568 /**
1569  *      __skb_queue_after - queue a buffer at the list head
1570  *      @list: list to use
1571  *      @prev: place after this buffer
1572  *      @newsk: buffer to queue
1573  *
1574  *      Queue a buffer int the middle of a list. This function takes no locks
1575  *      and you must therefore hold required locks before calling it.
1576  *
1577  *      A buffer cannot be placed on two lists at the same time.
1578  */
1579 static inline void __skb_queue_after(struct sk_buff_head *list,
1580                                      struct sk_buff *prev,
1581                                      struct sk_buff *newsk)
1582 {
1583         __skb_insert(newsk, prev, prev->next, list);
1584 }
1585 
1586 void skb_append(struct sk_buff *old, struct sk_buff *newsk,
1587                 struct sk_buff_head *list);
1588 
1589 static inline void __skb_queue_before(struct sk_buff_head *list,
1590                                       struct sk_buff *next,
1591                                       struct sk_buff *newsk)
1592 {
1593         __skb_insert(newsk, next->prev, next, list);
1594 }
1595 
1596 /**
1597  *      __skb_queue_head - queue a buffer at the list head
1598  *      @list: list to use
1599  *      @newsk: buffer to queue
1600  *
1601  *      Queue a buffer at the start of a list. This function takes no locks
1602  *      and you must therefore hold required locks before calling it.
1603  *
1604  *      A buffer cannot be placed on two lists at the same time.
1605  */
1606 void skb_queue_head(struct sk_buff_head *list, struct sk_buff *newsk);
1607 static inline void __skb_queue_head(struct sk_buff_head *list,
1608                                     struct sk_buff *newsk)
1609 {
1610         __skb_queue_after(list, (struct sk_buff *)list, newsk);
1611 }
1612 
1613 /**
1614  *      __skb_queue_tail - queue a buffer at the list tail
1615  *      @list: list to use
1616  *      @newsk: buffer to queue
1617  *
1618  *      Queue a buffer at the end of a list. This function takes no locks
1619  *      and you must therefore hold required locks before calling it.
1620  *
1621  *      A buffer cannot be placed on two lists at the same time.
1622  */
1623 void skb_queue_tail(struct sk_buff_head *list, struct sk_buff *newsk);
1624 static inline void __skb_queue_tail(struct sk_buff_head *list,
1625                                    struct sk_buff *newsk)
1626 {
1627         __skb_queue_before(list, (struct sk_buff *)list, newsk);
1628 }
1629 
1630 /*
1631  * remove sk_buff from list. _Must_ be called atomically, and with
1632  * the list known..
1633  */
1634 void skb_unlink(struct sk_buff *skb, struct sk_buff_head *list);
1635 static inline void __skb_unlink(struct sk_buff *skb, struct sk_buff_head *list)
1636 {
1637         struct sk_buff *next, *prev;
1638 
1639         list->qlen--;
1640         next       = skb->next;
1641         prev       = skb->prev;
1642         skb->next  = skb->prev = NULL;
1643         next->prev = prev;
1644         prev->next = next;
1645 }
1646 
1647 /**
1648  *      __skb_dequeue - remove from the head of the queue
1649  *      @list: list to dequeue from
1650  *
1651  *      Remove the head of the list. This function does not take any locks
1652  *      so must be used with appropriate locks held only. The head item is
1653  *      returned or %NULL if the list is empty.
1654  */
1655 struct sk_buff *skb_dequeue(struct sk_buff_head *list);
1656 static inline struct sk_buff *__skb_dequeue(struct sk_buff_head *list)
1657 {
1658         struct sk_buff *skb = skb_peek(list);
1659         if (skb)
1660                 __skb_unlink(skb, list);
1661         return skb;
1662 }
1663 
1664 /**
1665  *      __skb_dequeue_tail - remove from the tail of the queue
1666  *      @list: list to dequeue from
1667  *
1668  *      Remove the tail of the list. This function does not take any locks
1669  *      so must be used with appropriate locks held only. The tail item is
1670  *      returned or %NULL if the list is empty.
1671  */
1672 struct sk_buff *skb_dequeue_tail(struct sk_buff_head *list);
1673 static inline struct sk_buff *__skb_dequeue_tail(struct sk_buff_head *list)
1674 {
1675         struct sk_buff *skb = skb_peek_tail(list);
1676         if (skb)
1677                 __skb_unlink(skb, list);
1678         return skb;
1679 }
1680 
1681 
1682 static inline bool skb_is_nonlinear(const struct sk_buff *skb)
1683 {
1684         return skb->data_len;
1685 }
1686 
1687 static inline unsigned int skb_headlen(const struct sk_buff *skb)
1688 {
1689         return skb->len - skb->data_len;
1690 }
1691 
1692 static inline int skb_pagelen(const struct sk_buff *skb)
1693 {
1694         int i, len = 0;
1695 
1696         for (i = (int)skb_shinfo(skb)->nr_frags - 1; i >= 0; i--)
1697                 len += skb_frag_size(&skb_shinfo(skb)->frags[i]);
1698         return len + skb_headlen(skb);
1699 }
1700 
1701 /**
1702  * __skb_fill_page_desc - initialise a paged fragment in an skb
1703  * @skb: buffer containing fragment to be initialised
1704  * @i: paged fragment index to initialise
1705  * @page: the page to use for this fragment
1706  * @off: the offset to the data with @page
1707  * @size: the length of the data
1708  *
1709  * Initialises the @i'th fragment of @skb to point to &size bytes at
1710  * offset @off within @page.
1711  *
1712  * Does not take any additional reference on the fragment.
1713  */
1714 static inline void __skb_fill_page_desc(struct sk_buff *skb, int i,
1715                                         struct page *page, int off, int size)
1716 {
1717         skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
1718 
1719         /*
1720          * Propagate page pfmemalloc to the skb if we can. The problem is
1721          * that not all callers have unique ownership of the page but rely
1722          * on page_is_pfmemalloc doing the right thing(tm).
1723          */
1724         frag->page.p              = page;
1725         frag->page_offset         = off;
1726         skb_frag_size_set(frag, size);
1727 
1728         page = compound_head(page);
1729         if (page_is_pfmemalloc(page))
1730                 skb->pfmemalloc = true;
1731 }
1732 
1733 /**
1734  * skb_fill_page_desc - initialise a paged fragment in an skb
1735  * @skb: buffer containing fragment to be initialised
1736  * @i: paged fragment index to initialise
1737  * @page: the page to use for this fragment
1738  * @off: the offset to the data with @page
1739  * @size: the length of the data
1740  *
1741  * As per __skb_fill_page_desc() -- initialises the @i'th fragment of
1742  * @skb to point to @size bytes at offset @off within @page. In
1743  * addition updates @skb such that @i is the last fragment.
1744  *
1745  * Does not take any additional reference on the fragment.
1746  */
1747 static inline void skb_fill_page_desc(struct sk_buff *skb, int i,
1748                                       struct page *page, int off, int size)
1749 {
1750         __skb_fill_page_desc(skb, i, page, off, size);
1751         skb_shinfo(skb)->nr_frags = i + 1;
1752 }
1753 
1754 void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page, int off,
1755                      int size, unsigned int truesize);
1756 
1757 void skb_coalesce_rx_frag(struct sk_buff *skb, int i, int size,
1758                           unsigned int truesize);
1759 
1760 #define SKB_PAGE_ASSERT(skb)    BUG_ON(skb_shinfo(skb)->nr_frags)
1761 #define SKB_FRAG_ASSERT(skb)    BUG_ON(skb_has_frag_list(skb))
1762 #define SKB_LINEAR_ASSERT(skb)  BUG_ON(skb_is_nonlinear(skb))
1763 
1764 #ifdef NET_SKBUFF_DATA_USES_OFFSET
1765 static inline unsigned char *skb_tail_pointer(const struct sk_buff *skb)
1766 {
1767         return skb->head + skb->tail;
1768 }
1769 
1770 static inline void skb_reset_tail_pointer(struct sk_buff *skb)
1771 {
1772         skb->tail = skb->data - skb->head;
1773 }
1774 
1775 static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
1776 {
1777         skb_reset_tail_pointer(skb);
1778         skb->tail += offset;
1779 }
1780 
1781 #else /* NET_SKBUFF_DATA_USES_OFFSET */
1782 static inline unsigned char *skb_tail_pointer(const struct sk_buff *skb)
1783 {
1784         return skb->tail;
1785 }
1786 
1787 static inline void skb_reset_tail_pointer(struct sk_buff *skb)
1788 {
1789         skb->tail = skb->data;
1790 }
1791 
1792 static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
1793 {
1794         skb->tail = skb->data + offset;
1795 }
1796 
1797 #endif /* NET_SKBUFF_DATA_USES_OFFSET */
1798 
1799 /*
1800  *      Add data to an sk_buff
1801  */
1802 unsigned char *pskb_put(struct sk_buff *skb, struct sk_buff *tail, int len);
1803 unsigned char *skb_put(struct sk_buff *skb, unsigned int len);
1804 static inline unsigned char *__skb_put(struct sk_buff *skb, unsigned int len)
1805 {
1806         unsigned char *tmp = skb_tail_pointer(skb);
1807         SKB_LINEAR_ASSERT(skb);
1808         skb->tail += len;
1809         skb->len  += len;
1810         return tmp;
1811 }
1812 
1813 unsigned char *skb_push(struct sk_buff *skb, unsigned int len);
1814 static inline unsigned char *__skb_push(struct sk_buff *skb, unsigned int len)
1815 {
1816         skb->data -= len;
1817         skb->len  += len;
1818         return skb->data;
1819 }
1820 
1821 unsigned char *skb_pull(struct sk_buff *skb, unsigned int len);
1822 static inline unsigned char *__skb_pull(struct sk_buff *skb, unsigned int len)
1823 {
1824         skb->len -= len;
1825         BUG_ON(skb->len < skb->data_len);
1826         return skb->data += len;
1827 }
1828 
1829 static inline unsigned char *skb_pull_inline(struct sk_buff *skb, unsigned int len)
1830 {
1831         return unlikely(len > skb->len) ? NULL : __skb_pull(skb, len);
1832 }
1833 
1834 unsigned char *__pskb_pull_tail(struct sk_buff *skb, int delta);
1835 
1836 static inline unsigned char *__pskb_pull(struct sk_buff *skb, unsigned int len)
1837 {
1838         if (len > skb_headlen(skb) &&
1839             !__pskb_pull_tail(skb, len - skb_headlen(skb)))
1840                 return NULL;
1841         skb->len -= len;
1842         return skb->data += len;
1843 }
1844 
1845 static inline unsigned char *pskb_pull(struct sk_buff *skb, unsigned int len)
1846 {
1847         return unlikely(len > skb->len) ? NULL : __pskb_pull(skb, len);
1848 }
1849 
1850 static inline int pskb_may_pull(struct sk_buff *skb, unsigned int len)
1851 {
1852         if (likely(len <= skb_headlen(skb)))
1853                 return 1;
1854         if (unlikely(len > skb->len))
1855                 return 0;
1856         return __pskb_pull_tail(skb, len - skb_headlen(skb)) != NULL;
1857 }
1858 
1859 /**
1860  *      skb_headroom - bytes at buffer head
1861  *      @skb: buffer to check
1862  *
1863  *      Return the number of bytes of free space at the head of an &sk_buff.
1864  */
1865 static inline unsigned int skb_headroom(const struct sk_buff *skb)
1866 {
1867         return skb->data - skb->head;
1868 }
1869 
1870 /**
1871  *      skb_tailroom - bytes at buffer end
1872  *      @skb: buffer to check
1873  *
1874  *      Return the number of bytes of free space at the tail of an sk_buff
1875  */
1876 static inline int skb_tailroom(const struct sk_buff *skb)
1877 {
1878         return skb_is_nonlinear(skb) ? 0 : skb->end - skb->tail;
1879 }
1880 
1881 /**
1882  *      skb_availroom - bytes at buffer end
1883  *      @skb: buffer to check
1884  *
1885  *      Return the number of bytes of free space at the tail of an sk_buff
1886  *      allocated by sk_stream_alloc()
1887  */
1888 static inline int skb_availroom(const struct sk_buff *skb)
1889 {
1890         if (skb_is_nonlinear(skb))
1891                 return 0;
1892 
1893         return skb->end - skb->tail - skb->reserved_tailroom;
1894 }
1895 
1896 /**
1897  *      skb_reserve - adjust headroom
1898  *      @skb: buffer to alter
1899  *      @len: bytes to move
1900  *
1901  *      Increase the headroom of an empty &sk_buff by reducing the tail
1902  *      room. This is only allowed for an empty buffer.
1903  */
1904 static inline void skb_reserve(struct sk_buff *skb, int len)
1905 {
1906         skb->data += len;
1907         skb->tail += len;
1908 }
1909 
1910 #define ENCAP_TYPE_ETHER        0
1911 #define ENCAP_TYPE_IPPROTO      1
1912 
1913 static inline void skb_set_inner_protocol(struct sk_buff *skb,
1914                                           __be16 protocol)
1915 {
1916         skb->inner_protocol = protocol;
1917         skb->inner_protocol_type = ENCAP_TYPE_ETHER;
1918 }
1919 
1920 static inline void skb_set_inner_ipproto(struct sk_buff *skb,
1921                                          __u8 ipproto)
1922 {
1923         skb->inner_ipproto = ipproto;
1924         skb->inner_protocol_type = ENCAP_TYPE_IPPROTO;
1925 }
1926 
1927 static inline void skb_reset_inner_headers(struct sk_buff *skb)
1928 {
1929         skb->inner_mac_header = skb->mac_header;
1930         skb->inner_network_header = skb->network_header;
1931         skb->inner_transport_header = skb->transport_header;
1932 }
1933 
1934 static inline void skb_reset_mac_len(struct sk_buff *skb)
1935 {
1936         skb->mac_len = skb->network_header - skb->mac_header;
1937 }
1938 
1939 static inline unsigned char *skb_inner_transport_header(const struct sk_buff
1940                                                         *skb)
1941 {
1942         return skb->head + skb->inner_transport_header;
1943 }
1944 
1945 static inline void skb_reset_inner_transport_header(struct sk_buff *skb)
1946 {
1947         skb->inner_transport_header = skb->data - skb->head;
1948 }
1949 
1950 static inline void skb_set_inner_transport_header(struct sk_buff *skb,
1951                                                    const int offset)
1952 {
1953         skb_reset_inner_transport_header(skb);
1954         skb->inner_transport_header += offset;
1955 }
1956 
1957 static inline unsigned char *skb_inner_network_header(const struct sk_buff *skb)
1958 {
1959         return skb->head + skb->inner_network_header;
1960 }
1961 
1962 static inline void skb_reset_inner_network_header(struct sk_buff *skb)
1963 {
1964         skb->inner_network_header = skb->data - skb->head;
1965 }
1966 
1967 static inline void skb_set_inner_network_header(struct sk_buff *skb,
1968                                                 const int offset)
1969 {
1970         skb_reset_inner_network_header(skb);
1971         skb->inner_network_header += offset;
1972 }
1973 
1974 static inline unsigned char *skb_inner_mac_header(const struct sk_buff *skb)
1975 {
1976         return skb->head + skb->inner_mac_header;
1977 }
1978 
1979 static inline void skb_reset_inner_mac_header(struct sk_buff *skb)
1980 {
1981         skb->inner_mac_header = skb->data - skb->head;
1982 }
1983 
1984 static inline void skb_set_inner_mac_header(struct sk_buff *skb,
1985                                             const int offset)
1986 {
1987         skb_reset_inner_mac_header(skb);
1988         skb->inner_mac_header += offset;
1989 }
1990 static inline bool skb_transport_header_was_set(const struct sk_buff *skb)
1991 {
1992         return skb->transport_header != (typeof(skb->transport_header))~0U;
1993 }
1994 
1995 static inline unsigned char *skb_transport_header(const struct sk_buff *skb)
1996 {
1997         return skb->head + skb->transport_header;
1998 }
1999 
2000 static inline void skb_reset_transport_header(struct sk_buff *skb)
2001 {
2002         skb->transport_header = skb->data - skb->head;
2003 }
2004 
2005 static inline void skb_set_transport_header(struct sk_buff *skb,
2006                                             const int offset)
2007 {
2008         skb_reset_transport_header(skb);
2009         skb->transport_header += offset;
2010 }
2011 
2012 static inline unsigned char *skb_network_header(const struct sk_buff *skb)
2013 {
2014         return skb->head + skb->network_header;
2015 }
2016 
2017 static inline void skb_reset_network_header(struct sk_buff *skb)
2018 {
2019         skb->network_header = skb->data - skb->head;
2020 }
2021 
2022 static inline void skb_set_network_header(struct sk_buff *skb, const int offset)
2023 {
2024         skb_reset_network_header(skb);
2025         skb->network_header += offset;
2026 }
2027 
2028 static inline unsigned char *skb_mac_header(const struct sk_buff *skb)
2029 {
2030         return skb->head + skb->mac_header;
2031 }
2032 
2033 static inline int skb_mac_header_was_set(const struct sk_buff *skb)
2034 {
2035         return skb->mac_header != (typeof(skb->mac_header))~0U;
2036 }
2037 
2038 static inline void skb_reset_mac_header(struct sk_buff *skb)
2039 {
2040         skb->mac_header = skb->data - skb->head;
2041 }
2042 
2043 static inline void skb_set_mac_header(struct sk_buff *skb, const int offset)
2044 {
2045         skb_reset_mac_header(skb);
2046         skb->mac_header += offset;
2047 }
2048 
2049 static inline void skb_pop_mac_header(struct sk_buff *skb)
2050 {
2051         skb->mac_header = skb->network_header;
2052 }
2053 
2054 static inline void skb_probe_transport_header(struct sk_buff *skb,
2055                                               const int offset_hint)
2056 {
2057         struct flow_keys keys;
2058 
2059         if (skb_transport_header_was_set(skb))
2060                 return;
2061         else if (skb_flow_dissect_flow_keys(skb, &keys, 0))
2062                 skb_set_transport_header(skb, keys.control.thoff);
2063         else
2064                 skb_set_transport_header(skb, offset_hint);
2065 }
2066 
2067 static inline void skb_mac_header_rebuild(struct sk_buff *skb)
2068 {
2069         if (skb_mac_header_was_set(skb)) {
2070                 const unsigned char *old_mac = skb_mac_header(skb);
2071 
2072                 skb_set_mac_header(skb, -skb->mac_len);
2073                 memmove(skb_mac_header(skb), old_mac, skb->mac_len);
2074         }
2075 }
2076 
2077 static inline int skb_checksum_start_offset(const struct sk_buff *skb)
2078 {
2079         return skb->csum_start - skb_headroom(skb);
2080 }
2081 
2082 static inline int skb_transport_offset(const struct sk_buff *skb)
2083 {
2084         return skb_transport_header(skb) - skb->data;
2085 }
2086 
2087 static inline u32 skb_network_header_len(const struct sk_buff *skb)
2088 {
2089         return skb->transport_header - skb->network_header;
2090 }
2091 
2092 static inline u32 skb_inner_network_header_len(const struct sk_buff *skb)
2093 {
2094         return skb->inner_transport_header - skb->inner_network_header;
2095 }
2096 
2097 static inline int skb_network_offset(const struct sk_buff *skb)
2098 {
2099         return skb_network_header(skb) - skb->data;
2100 }
2101 
2102 static inline int skb_inner_network_offset(const struct sk_buff *skb)
2103 {
2104         return skb_inner_network_header(skb) - skb->data;
2105 }
2106 
2107 static inline int pskb_network_may_pull(struct sk_buff *skb, unsigned int len)
2108 {
2109         return pskb_may_pull(skb, skb_network_offset(skb) + len);
2110 }
2111 
2112 /*
2113  * CPUs often take a performance hit when accessing unaligned memory
2114  * locations. The actual performance hit varies, it can be small if the
2115  * hardware handles it or large if we have to take an exception and fix it
2116  * in software.
2117  *
2118  * Since an ethernet header is 14 bytes network drivers often end up with
2119  * the IP header at an unaligned offset. The IP header can be aligned by
2120  * shifting the start of the packet by 2 bytes. Drivers should do this
2121  * with:
2122  *
2123  * skb_reserve(skb, NET_IP_ALIGN);
2124  *
2125  * The downside to this alignment of the IP header is that the DMA is now
2126  * unaligned. On some architectures the cost of an unaligned DMA is high
2127  * and this cost outweighs the gains made by aligning the IP header.
2128  *
2129  * Since this trade off varies between architectures, we allow NET_IP_ALIGN
2130  * to be overridden.
2131  */
2132 #ifndef NET_IP_ALIGN
2133 #define NET_IP_ALIGN    2
2134 #endif
2135 
2136 /*
2137  * The networking layer reserves some headroom in skb data (via
2138  * dev_alloc_skb). This is used to avoid having to reallocate skb data when
2139  * the header has to grow. In the default case, if the header has to grow
2140  * 32 bytes or less we avoid the reallocation.
2141  *
2142  * Unfortunately this headroom changes the DMA alignment of the resulting
2143  * network packet. As for NET_IP_ALIGN, this unaligned DMA is expensive
2144  * on some architectures. An architecture can override this value,
2145  * perhaps setting it to a cacheline in size (since that will maintain
2146  * cacheline alignment of the DMA). It must be a power of 2.
2147  *
2148  * Various parts of the networking layer expect at least 32 bytes of
2149  * headroom, you should not reduce this.
2150  *
2151  * Using max(32, L1_CACHE_BYTES) makes sense (especially with RPS)
2152  * to reduce average number of cache lines per packet.
2153  * get_rps_cpus() for example only access one 64 bytes aligned block :
2154  * NET_IP_ALIGN(2) + ethernet_header(14) + IP_header(20/40) + ports(8)
2155  */
2156 #ifndef NET_SKB_PAD
2157 #define NET_SKB_PAD     max(32, L1_CACHE_BYTES)
2158 #endif
2159 
2160 int ___pskb_trim(struct sk_buff *skb, unsigned int len);
2161 
2162 static inline void __skb_trim(struct sk_buff *skb, unsigned int len)
2163 {
2164         if (unlikely(skb_is_nonlinear(skb))) {
2165                 WARN_ON(1);
2166                 return;
2167         }
2168         skb->len = len;
2169         skb_set_tail_pointer(skb, len);
2170 }
2171 
2172 void skb_trim(struct sk_buff *skb, unsigned int len);
2173 
2174 static inline int __pskb_trim(struct sk_buff *skb, unsigned int len)
2175 {
2176         if (skb->data_len)
2177                 return ___pskb_trim(skb, len);
2178         __skb_trim(skb, len);
2179         return 0;
2180 }
2181 
2182 static inline int pskb_trim(struct sk_buff *skb, unsigned int len)
2183 {
2184         return (len < skb->len) ? __pskb_trim(skb, len) : 0;
2185 }
2186 
2187 /**
2188  *      pskb_trim_unique - remove end from a paged unique (not cloned) buffer
2189  *      @skb: buffer to alter
2190  *      @len: new length
2191  *
2192  *      This is identical to pskb_trim except that the caller knows that
2193  *      the skb is not cloned so we should never get an error due to out-
2194  *      of-memory.
2195  */
2196 static inline void pskb_trim_unique(struct sk_buff *skb, unsigned int len)
2197 {
2198         int err = pskb_trim(skb, len);
2199         BUG_ON(err);
2200 }
2201 
2202 /**
2203  *      skb_orphan - orphan a buffer
2204  *      @skb: buffer to orphan
2205  *
2206  *      If a buffer currently has an owner then we call the owner's
2207  *      destructor function and make the @skb unowned. The buffer continues
2208  *      to exist but is no longer charged to its former owner.
2209  */
2210 static inline void skb_orphan(struct sk_buff *skb)
2211 {
2212         if (skb->destructor) {
2213                 skb->destructor(skb);
2214                 skb->destructor = NULL;
2215                 skb->sk         = NULL;
2216         } else {
2217                 BUG_ON(skb->sk);
2218         }
2219 }
2220 
2221 /**
2222  *      skb_orphan_frags - orphan the frags contained in a buffer
2223  *      @skb: buffer to orphan frags from
2224  *      @gfp_mask: allocation mask for replacement pages
2225  *
2226  *      For each frag in the SKB which needs a destructor (i.e. has an
2227  *      owner) create a copy of that frag and release the original
2228  *      page by calling the destructor.
2229  */
2230 static inline int skb_orphan_frags(struct sk_buff *skb, gfp_t gfp_mask)
2231 {
2232         if (likely(!(skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY)))
2233                 return 0;
2234         return skb_copy_ubufs(skb, gfp_mask);
2235 }
2236 
2237 /**
2238  *      __skb_queue_purge - empty a list
2239  *      @list: list to empty
2240  *
2241  *      Delete all buffers on an &sk_buff list. Each buffer is removed from
2242  *      the list and one reference dropped. This function does not take the
2243  *      list lock and the caller must hold the relevant locks to use it.
2244  */
2245 void skb_queue_purge(struct sk_buff_head *list);
2246 static inline void __skb_queue_purge(struct sk_buff_head *list)
2247 {
2248         struct sk_buff *skb;
2249         while ((skb = __skb_dequeue(list)) != NULL)
2250                 kfree_skb(skb);
2251 }
2252 
2253 void *netdev_alloc_frag(unsigned int fragsz);
2254 
2255 struct sk_buff *__netdev_alloc_skb(struct net_device *dev, unsigned int length,
2256                                    gfp_t gfp_mask);
2257 
2258 /**
2259  *      netdev_alloc_skb - allocate an skbuff for rx on a specific device
2260  *      @dev: network device to receive on
2261  *      @length: length to allocate
2262  *
2263  *      Allocate a new &sk_buff and assign it a usage count of one. The
2264  *      buffer has unspecified headroom built in. Users should allocate
2265  *      the headroom they think they need without accounting for the
2266  *      built in space. The built in space is used for optimisations.
2267  *
2268  *      %NULL is returned if there is no free memory. Although this function
2269  *      allocates memory it can be called from an interrupt.
2270  */
2271 static inline struct sk_buff *netdev_alloc_skb(struct net_device *dev,
2272                                                unsigned int length)
2273 {
2274         return __netdev_alloc_skb(dev, length, GFP_ATOMIC);
2275 }
2276 
2277 /* legacy helper around __netdev_alloc_skb() */
2278 static inline struct sk_buff *__dev_alloc_skb(unsigned int length,
2279                                               gfp_t gfp_mask)
2280 {
2281         return __netdev_alloc_skb(NULL, length, gfp_mask);
2282 }
2283 
2284 /* legacy helper around netdev_alloc_skb() */
2285 static inline struct sk_buff *dev_alloc_skb(unsigned int length)
2286 {
2287         return netdev_alloc_skb(NULL, length);
2288 }
2289 
2290 
2291 static inline struct sk_buff *__netdev_alloc_skb_ip_align(struct net_device *dev,
2292                 unsigned int length, gfp_t gfp)
2293 {
2294         struct sk_buff *skb = __netdev_alloc_skb(dev, length + NET_IP_ALIGN, gfp);
2295 
2296         if (NET_IP_ALIGN && skb)
2297                 skb_reserve(skb, NET_IP_ALIGN);
2298         return skb;
2299 }
2300 
2301 static inline struct sk_buff *netdev_alloc_skb_ip_align(struct net_device *dev,
2302                 unsigned int length)
2303 {
2304         return __netdev_alloc_skb_ip_align(dev, length, GFP_ATOMIC);
2305 }
2306 
2307 static inline void skb_free_frag(void *addr)
2308 {
2309         __free_page_frag(addr);
2310 }
2311 
2312 void *napi_alloc_frag(unsigned int fragsz);
2313 struct sk_buff *__napi_alloc_skb(struct napi_struct *napi,
2314                                  unsigned int length, gfp_t gfp_mask);
2315 static inline struct sk_buff *napi_alloc_skb(struct napi_struct *napi,
2316                                              unsigned int length)
2317 {
2318         return __napi_alloc_skb(napi, length, GFP_ATOMIC);
2319 }
2320 
2321 /**
2322  * __dev_alloc_pages - allocate page for network Rx
2323  * @gfp_mask: allocation priority. Set __GFP_NOMEMALLOC if not for network Rx
2324  * @order: size of the allocation
2325  *
2326  * Allocate a new page.
2327  *
2328  * %NULL is returned if there is no free memory.
2329 */
2330 static inline struct page *__dev_alloc_pages(gfp_t gfp_mask,
2331                                              unsigned int order)
2332 {
2333         /* This piece of code contains several assumptions.
2334          * 1.  This is for device Rx, therefor a cold page is preferred.
2335          * 2.  The expectation is the user wants a compound page.
2336          * 3.  If requesting a order 0 page it will not be compound
2337          *     due to the check to see if order has a value in prep_new_page
2338          * 4.  __GFP_MEMALLOC is ignored if __GFP_NOMEMALLOC is set due to
2339          *     code in gfp_to_alloc_flags that should be enforcing this.
2340          */
2341         gfp_mask |= __GFP_COLD | __GFP_COMP | __GFP_MEMALLOC;
2342 
2343         return alloc_pages_node(NUMA_NO_NODE, gfp_mask, order);
2344 }
2345 
2346 static inline struct page *dev_alloc_pages(unsigned int order)
2347 {
2348         return __dev_alloc_pages(GFP_ATOMIC, order);
2349 }
2350 
2351 /**
2352  * __dev_alloc_page - allocate a page for network Rx
2353  * @gfp_mask: allocation priority. Set __GFP_NOMEMALLOC if not for network Rx
2354  *
2355  * Allocate a new page.
2356  *
2357  * %NULL is returned if there is no free memory.
2358  */
2359 static inline struct page *__dev_alloc_page(gfp_t gfp_mask)
2360 {
2361         return __dev_alloc_pages(gfp_mask, 0);
2362 }
2363 
2364 static inline struct page *dev_alloc_page(void)
2365 {
2366         return __dev_alloc_page(GFP_ATOMIC);
2367 }
2368 
2369 /**
2370  *      skb_propagate_pfmemalloc - Propagate pfmemalloc if skb is allocated after RX page
2371  *      @page: The page that was allocated from skb_alloc_page
2372  *      @skb: The skb that may need pfmemalloc set
2373  */
2374 static inline void skb_propagate_pfmemalloc(struct page *page,
2375                                              struct sk_buff *skb)
2376 {
2377         if (page_is_pfmemalloc(page))
2378                 skb->pfmemalloc = true;
2379 }
2380 
2381 /**
2382  * skb_frag_page - retrieve the page referred to by a paged fragment
2383  * @frag: the paged fragment
2384  *
2385  * Returns the &struct page associated with @frag.
2386  */
2387 static inline struct page *skb_frag_page(const skb_frag_t *frag)
2388 {
2389         return frag->page.p;
2390 }
2391 
2392 /**
2393  * __skb_frag_ref - take an addition reference on a paged fragment.
2394  * @frag: the paged fragment
2395  *
2396  * Takes an additional reference on the paged fragment @frag.
2397  */
2398 static inline void __skb_frag_ref(skb_frag_t *frag)
2399 {
2400         get_page(skb_frag_page(frag));
2401 }
2402 
2403 /**
2404  * skb_frag_ref - take an addition reference on a paged fragment of an skb.
2405  * @skb: the buffer
2406  * @f: the fragment offset.
2407  *
2408  * Takes an additional reference on the @f'th paged fragment of @skb.
2409  */
2410 static inline void skb_frag_ref(struct sk_buff *skb, int f)
2411 {
2412         __skb_frag_ref(&skb_shinfo(skb)->frags[f]);
2413 }
2414 
2415 /**
2416  * __skb_frag_unref - release a reference on a paged fragment.
2417  * @frag: the paged fragment
2418  *
2419  * Releases a reference on the paged fragment @frag.
2420  */
2421 static inline void __skb_frag_unref(skb_frag_t *frag)
2422 {
2423         put_page(skb_frag_page(frag));
2424 }
2425 
2426 /**
2427  * skb_frag_unref - release a reference on a paged fragment of an skb.
2428  * @skb: the buffer
2429  * @f: the fragment offset
2430  *
2431  * Releases a reference on the @f'th paged fragment of @skb.
2432  */
2433 static inline void skb_frag_unref(struct sk_buff *skb, int f)
2434 {
2435         __skb_frag_unref(&skb_shinfo(skb)->frags[f]);
2436 }
2437 
2438 /**
2439  * skb_frag_address - gets the address of the data contained in a paged fragment
2440  * @frag: the paged fragment buffer
2441  *
2442  * Returns the address of the data within @frag. The page must already
2443  * be mapped.
2444  */
2445 static inline void *skb_frag_address(const skb_frag_t *frag)
2446 {
2447         return page_address(skb_frag_page(frag)) + frag->page_offset;
2448 }
2449 
2450 /**
2451  * skb_frag_address_safe - gets the address of the data contained in a paged fragment
2452  * @frag: the paged fragment buffer
2453  *
2454  * Returns the address of the data within @frag. Checks that the page
2455  * is mapped and returns %NULL otherwise.
2456  */
2457 static inline void *skb_frag_address_safe(const skb_frag_t *frag)
2458 {
2459         void *ptr = page_address(skb_frag_page(frag));
2460         if (unlikely(!ptr))
2461                 return NULL;
2462 
2463         return ptr + frag->page_offset;
2464 }
2465 
2466 /**
2467  * __skb_frag_set_page - sets the page contained in a paged fragment
2468  * @frag: the paged fragment
2469  * @page: the page to set
2470  *
2471  * Sets the fragment @frag to contain @page.
2472  */
2473 static inline void __skb_frag_set_page(skb_frag_t *frag, struct page *page)
2474 {
2475         frag->page.p = page;
2476 }
2477 
2478 /**
2479  * skb_frag_set_page - sets the page contained in a paged fragment of an skb
2480  * @skb: the buffer
2481  * @f: the fragment offset
2482  * @page: the page to set
2483  *
2484  * Sets the @f'th fragment of @skb to contain @page.
2485  */
2486 static inline void skb_frag_set_page(struct sk_buff *skb, int f,
2487                                      struct page *page)
2488 {
2489         __skb_frag_set_page(&skb_shinfo(skb)->frags[f], page);
2490 }
2491 
2492 bool skb_page_frag_refill(unsigned int sz, struct page_frag *pfrag, gfp_t prio);
2493 
2494 /**
2495  * skb_frag_dma_map - maps a paged fragment via the DMA API
2496  * @dev: the device to map the fragment to
2497  * @frag: the paged fragment to map
2498  * @offset: the offset within the fragment (starting at the
2499  *          fragment's own offset)
2500  * @size: the number of bytes to map
2501  * @dir: the direction of the mapping (%PCI_DMA_*)
2502  *
2503  * Maps the page associated with @frag to @device.
2504  */
2505 static inline dma_addr_t skb_frag_dma_map(struct device *dev,
2506                                           const skb_frag_t *frag,
2507                                           size_t offset, size_t size,
2508                                           enum dma_data_direction dir)
2509 {
2510         return dma_map_page(dev, skb_frag_page(frag),
2511                             frag->page_offset + offset, size, dir);
2512 }
2513 
2514 static inline struct sk_buff *pskb_copy(struct sk_buff *skb,
2515                                         gfp_t gfp_mask)
2516 {
2517         return __pskb_copy(skb, skb_headroom(skb), gfp_mask);
2518 }
2519 
2520 
2521 static inline struct sk_buff *pskb_copy_for_clone(struct sk_buff *skb,
2522                                                   gfp_t gfp_mask)
2523 {
2524         return __pskb_copy_fclone(skb, skb_headroom(skb), gfp_mask, true);
2525 }
2526 
2527 
2528 /**
2529  *      skb_clone_writable - is the header of a clone writable
2530  *      @skb: buffer to check
2531  *      @len: length up to which to write
2532  *
2533  *      Returns true if modifying the header part of the cloned buffer
2534  *      does not requires the data to be copied.
2535  */
2536 static inline int skb_clone_writable(const struct sk_buff *skb, unsigned int len)
2537 {
2538         return !skb_header_cloned(skb) &&
2539                skb_headroom(skb) + len <= skb->hdr_len;
2540 }
2541 
2542 static inline int __skb_cow(struct sk_buff *skb, unsigned int headroom,
2543                             int cloned)
2544 {
2545         int delta = 0;
2546 
2547         if (headroom > skb_headroom(skb))
2548                 delta = headroom - skb_headroom(skb);
2549 
2550         if (delta || cloned)
2551                 return pskb_expand_head(skb, ALIGN(delta, NET_SKB_PAD), 0,
2552                                         GFP_ATOMIC);
2553         return 0;
2554 }
2555 
2556 /**
2557  *      skb_cow - copy header of skb when it is required
2558  *      @skb: buffer to cow
2559  *      @headroom: needed headroom
2560  *
2561  *      If the skb passed lacks sufficient headroom or its data part
2562  *      is shared, data is reallocated. If reallocation fails, an error
2563  *      is returned and original skb is not changed.
2564  *
2565  *      The result is skb with writable area skb->head...skb->tail
2566  *      and at least @headroom of space at head.
2567  */
2568 static inline int skb_cow(struct sk_buff *skb, unsigned int headroom)
2569 {
2570         return __skb_cow(skb, headroom, skb_cloned(skb));
2571 }
2572 
2573 /**
2574  *      skb_cow_head - skb_cow but only making the head writable
2575  *      @skb: buffer to cow
2576  *      @headroom: needed headroom
2577  *
2578  *      This function is identical to skb_cow except that we replace the
2579  *      skb_cloned check by skb_header_cloned.  It should be used when
2580  *      you only need to push on some header and do not need to modify
2581  *      the data.
2582  */
2583 static inline int skb_cow_head(struct sk_buff *skb, unsigned int headroom)
2584 {
2585         return __skb_cow(skb, headroom, skb_header_cloned(skb));
2586 }
2587 
2588 /**
2589  *      skb_padto       - pad an skbuff up to a minimal size
2590  *      @skb: buffer to pad
2591  *      @len: minimal length
2592  *
2593  *      Pads up a buffer to ensure the trailing bytes exist and are
2594  *      blanked. If the buffer already contains sufficient data it
2595  *      is untouched. Otherwise it is extended. Returns zero on
2596  *      success. The skb is freed on error.
2597  */
2598 static inline int skb_padto(struct sk_buff *skb, unsigned int len)
2599 {
2600         unsigned int size = skb->len;
2601         if (likely(size >= len))
2602                 return 0;
2603         return skb_pad(skb, len - size);
2604 }
2605 
2606 /**
2607  *      skb_put_padto - increase size and pad an skbuff up to a minimal size
2608  *      @skb: buffer to pad
2609  *      @len: minimal length
2610  *
2611  *      Pads up a buffer to ensure the trailing bytes exist and are
2612  *      blanked. If the buffer already contains sufficient data it
2613  *      is untouched. Otherwise it is extended. Returns zero on
2614  *      success. The skb is freed on error.
2615  */
2616 static inline int skb_put_padto(struct sk_buff *skb, unsigned int len)
2617 {
2618         unsigned int size = skb->len;
2619 
2620         if (unlikely(size < len)) {
2621                 len -= size;
2622                 if (skb_pad(skb, len))
2623                         return -ENOMEM;
2624                 __skb_put(skb, len);
2625         }
2626         return 0;
2627 }
2628 
2629 static inline int skb_add_data(struct sk_buff *skb,
2630                                struct iov_iter *from, int copy)
2631 {
2632         const int off = skb->len;
2633 
2634         if (skb->ip_summed == CHECKSUM_NONE) {
2635                 __wsum csum = 0;
2636                 if (csum_and_copy_from_iter(skb_put(skb, copy), copy,
2637                                             &csum, from) == copy) {
2638                         skb->csum = csum_block_add(skb->csum, csum, off);
2639                         return 0;
2640                 }
2641         } else if (copy_from_iter(skb_put(skb, copy), copy, from) == copy)
2642                 return 0;
2643 
2644         __skb_trim(skb, off);
2645         return -EFAULT;
2646 }
2647 
2648 static inline bool skb_can_coalesce(struct sk_buff *skb, int i,
2649                                     const struct page *page, int off)
2650 {
2651         if (i) {
2652                 const struct skb_frag_struct *frag = &skb_shinfo(skb)->frags[i - 1];
2653 
2654                 return page == skb_frag_page(frag) &&
2655                        off == frag->page_offset + skb_frag_size(frag);
2656         }
2657         return false;
2658 }
2659 
2660 static inline int __skb_linearize(struct sk_buff *skb)
2661 {
2662         return __pskb_pull_tail(skb, skb->data_len) ? 0 : -ENOMEM;
2663 }
2664 
2665 /**
2666  *      skb_linearize - convert paged skb to linear one
2667  *      @skb: buffer to linarize
2668  *
2669  *      If there is no free memory -ENOMEM is returned, otherwise zero
2670  *      is returned and the old skb data released.
2671  */
2672 static inline int skb_linearize(struct sk_buff *skb)
2673 {
2674         return skb_is_nonlinear(skb) ? __skb_linearize(skb) : 0;
2675 }
2676 
2677 /**
2678  * skb_has_shared_frag - can any frag be overwritten
2679  * @skb: buffer to test
2680  *
2681  * Return true if the skb has at least one frag that might be modified
2682  * by an external entity (as in vmsplice()/sendfile())
2683  */
2684 static inline bool skb_has_shared_frag(const struct sk_buff *skb)
2685 {
2686         return skb_is_nonlinear(skb) &&
2687                skb_shinfo(skb)->tx_flags & SKBTX_SHARED_FRAG;
2688 }
2689 
2690 /**
2691  *      skb_linearize_cow - make sure skb is linear and writable
2692  *      @skb: buffer to process
2693  *
2694  *      If there is no free memory -ENOMEM is returned, otherwise zero
2695  *      is returned and the old skb data released.
2696  */
2697 static inline int skb_linearize_cow(struct sk_buff *skb)
2698 {
2699         return skb_is_nonlinear(skb) || skb_cloned(skb) ?
2700                __skb_linearize(skb) : 0;
2701 }
2702 
2703 /**
2704  *      skb_postpull_rcsum - update checksum for received skb after pull
2705  *      @skb: buffer to update
2706  *      @start: start of data before pull
2707  *      @len: length of data pulled
2708  *
2709  *      After doing a pull on a received packet, you need to call this to
2710  *      update the CHECKSUM_COMPLETE checksum, or set ip_summed to
2711  *      CHECKSUM_NONE so that it can be recomputed from scratch.
2712  */
2713 
2714 static inline void skb_postpull_rcsum(struct sk_buff *skb,
2715                                       const void *start, unsigned int len)
2716 {
2717         if (skb->ip_summed == CHECKSUM_COMPLETE)
2718                 skb->csum = csum_sub(skb->csum, csum_partial(start, len, 0));
2719         else if (skb->ip_summed == CHECKSUM_PARTIAL &&
2720                  skb_checksum_start_offset(skb) < 0)
2721                 skb->ip_summed = CHECKSUM_NONE;
2722 }
2723 
2724 unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len);
2725 
2726 /**
2727  *      pskb_trim_rcsum - trim received skb and update checksum
2728  *      @skb: buffer to trim
2729  *      @len: new length
2730  *
2731  *      This is exactly the same as pskb_trim except that it ensures the
2732  *      checksum of received packets are still valid after the operation.
2733  */
2734 
2735 static inline int pskb_trim_rcsum(struct sk_buff *skb, unsigned int len)
2736 {
2737         if (likely(len >= skb->len))
2738                 return 0;
2739         if (skb->ip_summed == CHECKSUM_COMPLETE)
2740                 skb->ip_summed = CHECKSUM_NONE;
2741         return __pskb_trim(skb, len);
2742 }
2743 
2744 #define skb_queue_walk(queue, skb) \
2745                 for (skb = (queue)->next;                                       \
2746                      skb != (struct sk_buff *)(queue);                          \
2747                      skb = skb->next)
2748 
2749 #define skb_queue_walk_safe(queue, skb, tmp)                                    \
2750                 for (skb = (queue)->next, tmp = skb->next;                      \
2751                      skb != (struct sk_buff *)(queue);                          \
2752                      skb = tmp, tmp = skb->next)
2753 
2754 #define skb_queue_walk_from(queue, skb)                                         \
2755                 for (; skb != (struct sk_buff *)(queue);                        \
2756                      skb = skb->next)
2757 
2758 #define skb_queue_walk_from_safe(queue, skb, tmp)                               \
2759                 for (tmp = skb->next;                                           \
2760                      skb != (struct sk_buff *)(queue);                          \
2761                      skb = tmp, tmp = skb->next)
2762 
2763 #define skb_queue_reverse_walk(queue, skb) \
2764                 for (skb = (queue)->prev;                                       \
2765                      skb != (struct sk_buff *)(queue);                          \
2766                      skb = skb->prev)
2767 
2768 #define skb_queue_reverse_walk_safe(queue, skb, tmp)                            \
2769                 for (skb = (queue)->prev, tmp = skb->prev;                      \
2770                      skb != (struct sk_buff *)(queue);                          \
2771                      skb = tmp, tmp = skb->prev)
2772 
2773 #define skb_queue_reverse_walk_from_safe(queue, skb, tmp)                       \
2774                 for (tmp = skb->prev;                                           \
2775                      skb != (struct sk_buff *)(queue);                          \
2776                      skb = tmp, tmp = skb->prev)
2777 
2778 static inline bool skb_has_frag_list(const struct sk_buff *skb)
2779 {
2780         return skb_shinfo(skb)->frag_list != NULL;
2781 }
2782 
2783 static inline void skb_frag_list_init(struct sk_buff *skb)
2784 {
2785         skb_shinfo(skb)->frag_list = NULL;
2786 }
2787 
2788 #define skb_walk_frags(skb, iter)       \
2789         for (iter = skb_shinfo(skb)->frag_list; iter; iter = iter->next)
2790 
2791 struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned flags,
2792                                     int *peeked, int *off, int *err);
2793 struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags, int noblock,
2794                                   int *err);
2795 unsigned int datagram_poll(struct file *file, struct socket *sock,
2796                            struct poll_table_struct *wait);
2797 int skb_copy_datagram_iter(const struct sk_buff *from, int offset,
2798                            struct iov_iter *to, int size);
2799 static inline int skb_copy_datagram_msg(const struct sk_buff *from, int offset,
2800                                         struct msghdr *msg, int size)
2801 {
2802         return skb_copy_datagram_iter(from, offset, &msg->msg_iter, size);
2803 }
2804 int skb_copy_and_csum_datagram_msg(struct sk_buff *skb, int hlen,
2805                                    struct msghdr *msg);
2806 int skb_copy_datagram_from_iter(struct sk_buff *skb, int offset,
2807                                  struct iov_iter *from, int len);
2808 int zerocopy_sg_from_iter(struct sk_buff *skb, struct iov_iter *frm);
2809 void skb_free_datagram(struct sock *sk, struct sk_buff *skb);
2810 void skb_free_datagram_locked(struct sock *sk, struct sk_buff *skb);
2811 int skb_kill_datagram(struct sock *sk, struct sk_buff *skb, unsigned int flags);
2812 int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len);
2813 int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len);
2814 __wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset, u8 *to,
2815                               int len, __wsum csum);
2816 ssize_t skb_socket_splice(struct sock *sk,
2817                           struct pipe_inode_info *pipe,
2818                           struct splice_pipe_desc *spd);
2819 int skb_splice_bits(struct sk_buff *skb, struct sock *sk, unsigned int offset,
2820                     struct pipe_inode_info *pipe, unsigned int len,
2821                     unsigned int flags,
2822                     ssize_t (*splice_cb)(struct sock *,
2823                                          struct pipe_inode_info *,
2824                                          struct splice_pipe_desc *));
2825 void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to);
2826 unsigned int skb_zerocopy_headlen(const struct sk_buff *from);
2827 int skb_zerocopy(struct sk_buff *to, struct sk_buff *from,
2828                  int len, int hlen);
2829 void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len);
2830 int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen);
2831 void skb_scrub_packet(struct sk_buff *skb, bool xnet);
2832 unsigned int skb_gso_transport_seglen(const struct sk_buff *skb);
2833 struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features);
2834 struct sk_buff *skb_vlan_untag(struct sk_buff *skb);
2835 int skb_ensure_writable(struct sk_buff *skb, int write_len);
2836 int skb_vlan_pop(struct sk_buff *skb);
2837 int skb_vlan_push(struct sk_buff *skb, __be16 vlan_proto, u16 vlan_tci);
2838 
2839 static inline int memcpy_from_msg(void *data, struct msghdr *msg, int len)
2840 {
2841         return copy_from_iter(data, len, &msg->msg_iter) == len ? 0 : -EFAULT;
2842 }
2843 
2844 static inline int memcpy_to_msg(struct msghdr *msg, void *data, int len)
2845 {
2846         return copy_to_iter(data, len, &msg->msg_iter) == len ? 0 : -EFAULT;
2847 }
2848 
2849 struct skb_checksum_ops {
2850         __wsum (*update)(const void *mem, int len, __wsum wsum);
2851         __wsum (*combine)(__wsum csum, __wsum csum2, int offset, int len);
2852 };
2853 
2854 __wsum __skb_checksum(const struct sk_buff *skb, int offset, int len,
2855                       __wsum csum, const struct skb_checksum_ops *ops);
2856 __wsum skb_checksum(const struct sk_buff *skb, int offset, int len,
2857                     __wsum csum);
2858 
2859 static inline void * __must_check
2860 __skb_header_pointer(const struct sk_buff *skb, int offset,
2861                      int len, void *data, int hlen, void *buffer)
2862 {
2863         if (hlen - offset >= len)
2864                 return data + offset;
2865 
2866         if (!skb ||
2867             skb_copy_bits(skb, offset, buffer, len) < 0)
2868                 return NULL;
2869 
2870         return buffer;
2871 }
2872 
2873 static inline void * __must_check
2874 skb_header_pointer(const struct sk_buff *skb, int offset, int len, void *buffer)
2875 {
2876         return __skb_header_pointer(skb, offset, len, skb->data,
2877                                     skb_headlen(skb), buffer);
2878 }
2879 
2880 /**
2881  *      skb_needs_linearize - check if we need to linearize a given skb
2882  *                            depending on the given device features.
2883  *      @skb: socket buffer to check
2884  *      @features: net device features
2885  *
2886  *      Returns true if either:
2887  *      1. skb has frag_list and the device doesn't support FRAGLIST, or
2888  *      2. skb is fragmented and the device does not support SG.
2889  */
2890 static inline bool skb_needs_linearize(struct sk_buff *skb,
2891                                        netdev_features_t features)
2892 {
2893         return skb_is_nonlinear(skb) &&
2894                ((skb_has_frag_list(skb) && !(features & NETIF_F_FRAGLIST)) ||
2895                 (skb_shinfo(skb)->nr_frags && !(features & NETIF_F_SG)));
2896 }
2897 
2898 static inline void skb_copy_from_linear_data(const struct sk_buff *skb,
2899                                              void *to,
2900                                              const unsigned int len)
2901 {
2902         memcpy(to, skb->data, len);
2903 }
2904 
2905 static inline void skb_copy_from_linear_data_offset(const struct sk_buff *skb,
2906                                                     const int offset, void *to,
2907                                                     const unsigned int len)
2908 {
2909         memcpy(to, skb->data + offset, len);
2910 }
2911 
2912 static inline void skb_copy_to_linear_data(struct sk_buff *skb,
2913                                            const void *from,
2914                                            const unsigned int len)
2915 {
2916         memcpy(skb->data, from, len);
2917 }
2918 
2919 static inline void skb_copy_to_linear_data_offset(struct sk_buff *skb,
2920                                                   const int offset,
2921                                                   const void *from,
2922                                                   const unsigned int len)
2923 {
2924         memcpy(skb->data + offset, from, len);
2925 }
2926 
2927 void skb_init(void);
2928 
2929 static inline ktime_t skb_get_ktime(const struct sk_buff *skb)
2930 {
2931         return skb->tstamp;
2932 }
2933 
2934 /**
2935  *      skb_get_timestamp - get timestamp from a skb
2936  *      @skb: skb to get stamp from
2937  *      @stamp: pointer to struct timeval to store stamp in
2938  *
2939  *      Timestamps are stored in the skb as offsets to a base timestamp.
2940  *      This function converts the offset back to a struct timeval and stores
2941  *      it in stamp.
2942  */
2943 static inline void skb_get_timestamp(const struct sk_buff *skb,
2944                                      struct timeval *stamp)
2945 {
2946         *stamp = ktime_to_timeval(skb->tstamp);
2947 }
2948 
2949 static inline void skb_get_timestampns(const struct sk_buff *skb,
2950                                        struct timespec *stamp)
2951 {
2952         *stamp = ktime_to_timespec(skb->tstamp);
2953 }
2954 
2955 static inline void __net_timestamp(struct sk_buff *skb)
2956 {
2957         skb->tstamp = ktime_get_real();
2958 }
2959 
2960 static inline ktime_t net_timedelta(ktime_t t)
2961 {
2962         return ktime_sub(ktime_get_real(), t);
2963 }
2964 
2965 static inline ktime_t net_invalid_timestamp(void)
2966 {
2967         return ktime_set(0, 0);
2968 }
2969 
2970 struct sk_buff *skb_clone_sk(struct sk_buff *skb);
2971 
2972 #ifdef CONFIG_NETWORK_PHY_TIMESTAMPING
2973 
2974 void skb_clone_tx_timestamp(struct sk_buff *skb);
2975 bool skb_defer_rx_timestamp(struct sk_buff *skb);
2976 
2977 #else /* CONFIG_NETWORK_PHY_TIMESTAMPING */
2978 
2979 static inline void skb_clone_tx_timestamp(struct sk_buff *skb)
2980 {
2981 }
2982 
2983 static inline bool skb_defer_rx_timestamp(struct sk_buff *skb)
2984 {
2985         return false;
2986 }
2987 
2988 #endif /* !CONFIG_NETWORK_PHY_TIMESTAMPING */
2989 
2990 /**
2991  * skb_complete_tx_timestamp() - deliver cloned skb with tx timestamps
2992  *
2993  * PHY drivers may accept clones of transmitted packets for
2994  * timestamping via their phy_driver.txtstamp method. These drivers
2995  * must call this function to return the skb back to the stack with a
2996  * timestamp.
2997  *
2998  * @skb: clone of the the original outgoing packet
2999  * @hwtstamps: hardware time stamps
3000  *
3001  */
3002 void skb_complete_tx_timestamp(struct sk_buff *skb,
3003                                struct skb_shared_hwtstamps *hwtstamps);
3004 
3005 void __skb_tstamp_tx(struct sk_buff *orig_skb,
3006                      struct skb_shared_hwtstamps *hwtstamps,
3007                      struct sock *sk, int tstype);
3008 
3009 /**
3010  * skb_tstamp_tx - queue clone of skb with send time stamps
3011  * @orig_skb:   the original outgoing packet
3012  * @hwtstamps:  hardware time stamps, may be NULL if not available
3013  *
3014  * If the skb has a socket associated, then this function clones the
3015  * skb (thus sharing the actual data and optional structures), stores
3016  * the optional hardware time stamping information (if non NULL) or
3017  * generates a software time stamp (otherwise), then queues the clone
3018  * to the error queue of the socket.  Errors are silently ignored.
3019  */
3020 void skb_tstamp_tx(struct sk_buff *orig_skb,
3021                    struct skb_shared_hwtstamps *hwtstamps);
3022 
3023 static inline void sw_tx_timestamp(struct sk_buff *skb)
3024 {
3025         if (skb_shinfo(skb)->tx_flags & SKBTX_SW_TSTAMP &&
3026             !(skb_shinfo(skb)->tx_flags & SKBTX_IN_PROGRESS))
3027                 skb_tstamp_tx(skb, NULL);
3028 }
3029 
3030 /**
3031  * skb_tx_timestamp() - Driver hook for transmit timestamping
3032  *
3033  * Ethernet MAC Drivers should call this function in their hard_xmit()
3034  * function immediately before giving the sk_buff to the MAC hardware.
3035  *
3036  * Specifically, one should make absolutely sure that this function is
3037  * called before TX completion of this packet can trigger.  Otherwise
3038  * the packet could potentially already be freed.
3039  *
3040  * @skb: A socket buffer.
3041  */
3042 static inline void skb_tx_timestamp(struct sk_buff *skb)
3043 {
3044         skb_clone_tx_timestamp(skb);
3045         sw_tx_timestamp(skb);
3046 }
3047 
3048 /**
3049  * skb_complete_wifi_ack - deliver skb with wifi status
3050  *
3051  * @skb: the original outgoing packet
3052  * @acked: ack status
3053  *
3054  */
3055 void skb_complete_wifi_ack(struct sk_buff *skb, bool acked);
3056 
3057 __sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len);
3058 __sum16 __skb_checksum_complete(struct sk_buff *skb);
3059 
3060 static inline int skb_csum_unnecessary(const struct sk_buff *skb)
3061 {
3062         return ((skb->ip_summed == CHECKSUM_UNNECESSARY) ||
3063                 skb->csum_valid ||
3064                 (skb->ip_summed == CHECKSUM_PARTIAL &&
3065                  skb_checksum_start_offset(skb) >= 0));
3066 }
3067 
3068 /**
3069  *      skb_checksum_complete - Calculate checksum of an entire packet
3070  *      @skb: packet to process
3071  *
3072  *      This function calculates the checksum over the entire packet plus
3073  *      the value of skb->csum.  The latter can be used to supply the
3074  *      checksum of a pseudo header as used by TCP/UDP.  It returns the
3075  *      checksum.
3076  *
3077  *      For protocols that contain complete checksums such as ICMP/TCP/UDP,
3078  *      this function can be used to verify that checksum on received
3079  *      packets.  In that case the function should return zero if the
3080  *      checksum is correct.  In particular, this function will return zero
3081  *      if skb->ip_summed is CHECKSUM_UNNECESSARY which indicates that the
3082  *      hardware has already verified the correctness of the checksum.
3083  */
3084 static inline __sum16 skb_checksum_complete(struct sk_buff *skb)
3085 {
3086         return skb_csum_unnecessary(skb) ?
3087                0 : __skb_checksum_complete(skb);
3088 }
3089 
3090 static inline void __skb_decr_checksum_unnecessary(struct sk_buff *skb)
3091 {
3092         if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
3093                 if (skb->csum_level == 0)
3094                         skb->ip_summed = CHECKSUM_NONE;
3095                 else
3096                         skb->csum_level--;
3097         }
3098 }
3099 
3100 static inline void __skb_incr_checksum_unnecessary(struct sk_buff *skb)
3101 {
3102         if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
3103                 if (skb->csum_level < SKB_MAX_CSUM_LEVEL)
3104                         skb->csum_level++;
3105         } else if (skb->ip_summed == CHECKSUM_NONE) {
3106                 skb->ip_summed = CHECKSUM_UNNECESSARY;
3107                 skb->csum_level = 0;
3108         }
3109 }
3110 
3111 static inline void __skb_mark_checksum_bad(struct sk_buff *skb)
3112 {
3113         /* Mark current checksum as bad (typically called from GRO
3114          * path). In the case that ip_summed is CHECKSUM_NONE
3115          * this must be the first checksum encountered in the packet.
3116          * When ip_summed is CHECKSUM_UNNECESSARY, this is the first
3117          * checksum after the last one validated. For UDP, a zero
3118          * checksum can not be marked as bad.
3119          */
3120 
3121         if (skb->ip_summed == CHECKSUM_NONE ||
3122             skb->ip_summed == CHECKSUM_UNNECESSARY)
3123                 skb->csum_bad = 1;
3124 }
3125 
3126 /* Check if we need to perform checksum complete validation.
3127  *
3128  * Returns true if checksum complete is needed, false otherwise
3129  * (either checksum is unnecessary or zero checksum is allowed).
3130  */
3131 static inline bool __skb_checksum_validate_needed(struct sk_buff *skb,
3132                                                   bool zero_okay,
3133                                                   __sum16 check)
3134 {
3135         if (skb_csum_unnecessary(skb) || (zero_okay && !check)) {
3136                 skb->csum_valid = 1;
3137                 __skb_decr_checksum_unnecessary(skb);
3138                 return false;
3139         }
3140 
3141         return true;
3142 }
3143 
3144 /* For small packets <= CHECKSUM_BREAK peform checksum complete directly
3145  * in checksum_init.
3146  */
3147 #define CHECKSUM_BREAK 76
3148 
3149 /* Unset checksum-complete
3150  *
3151  * Unset checksum complete can be done when packet is being modified
3152  * (uncompressed for instance) and checksum-complete value is
3153  * invalidated.
3154  */
3155 static inline void skb_checksum_complete_unset(struct sk_buff *skb)
3156 {
3157         if (skb->ip_summed == CHECKSUM_COMPLETE)
3158                 skb->ip_summed = CHECKSUM_NONE;
3159 }
3160 
3161 /* Validate (init) checksum based on checksum complete.
3162  *
3163  * Return values:
3164  *   0: checksum is validated or try to in skb_checksum_complete. In the latter
3165  *      case the ip_summed will not be CHECKSUM_UNNECESSARY and the pseudo
3166  *      checksum is stored in skb->csum for use in __skb_checksum_complete
3167  *   non-zero: value of invalid checksum
3168  *
3169  */
3170 static inline __sum16 __skb_checksum_validate_complete(struct sk_buff *skb,
3171                                                        bool complete,
3172                                                        __wsum psum)
3173 {
3174         if (skb->ip_summed == CHECKSUM_COMPLETE) {
3175                 if (!csum_fold(csum_add(psum, skb->csum))) {
3176                         skb->csum_valid = 1;
3177                         return 0;
3178                 }
3179         } else if (skb->csum_bad) {
3180                 /* ip_summed == CHECKSUM_NONE in this case */
3181                 return (__force __sum16)1;
3182         }
3183 
3184         skb->csum = psum;
3185 
3186         if (complete || skb->len <= CHECKSUM_BREAK) {
3187                 __sum16 csum;
3188 
3189                 csum = __skb_checksum_complete(skb);
3190                 skb->csum_valid = !csum;
3191                 return csum;
3192         }
3193 
3194         return 0;
3195 }
3196 
3197 static inline __wsum null_compute_pseudo(struct sk_buff *skb, int proto)
3198 {
3199         return 0;
3200 }
3201 
3202 /* Perform checksum validate (init). Note that this is a macro since we only
3203  * want to calculate the pseudo header which is an input function if necessary.
3204  * First we try to validate without any computation (checksum unnecessary) and
3205  * then calculate based on checksum complete calling the function to compute
3206  * pseudo header.
3207  *
3208  * Return values:
3209  *   0: checksum is validated or try to in skb_checksum_complete
3210  *   non-zero: value of invalid checksum
3211  */
3212 #define __skb_checksum_validate(skb, proto, complete,                   \
3213                                 zero_okay, check, compute_pseudo)       \
3214 ({                                                                      \
3215         __sum16 __ret = 0;                                              \
3216         skb->csum_valid = 0;                                            \
3217         if (__skb_checksum_validate_needed(skb, zero_okay, check))      \
3218                 __ret = __skb_checksum_validate_complete(skb,           \
3219                                 complete, compute_pseudo(skb, proto));  \
3220         __ret;                                                          \
3221 })
3222 
3223 #define skb_checksum_init(skb, proto, compute_pseudo)                   \
3224         __skb_checksum_validate(skb, proto, false, false, 0, compute_pseudo)
3225 
3226 #define skb_checksum_init_zero_check(skb, proto, check, compute_pseudo) \
3227         __skb_checksum_validate(skb, proto, false, true, check, compute_pseudo)
3228 
3229 #define skb_checksum_validate(skb, proto, compute_pseudo)               \
3230         __skb_checksum_validate(skb, proto, true, false, 0, compute_pseudo)
3231 
3232 #define skb_checksum_validate_zero_check(skb, proto, check,             \
3233                                          compute_pseudo)                \
3234         __skb_checksum_validate(skb, proto, true, true, check, compute_pseudo)
3235 
3236 #define skb_checksum_simple_validate(skb)                               \
3237         __skb_checksum_validate(skb, 0, true, false, 0, null_compute_pseudo)
3238 
3239 static inline bool __skb_checksum_convert_check(struct sk_buff *skb)
3240 {
3241         return (skb->ip_summed == CHECKSUM_NONE &&
3242                 skb->csum_valid && !skb->csum_bad);
3243 }
3244 
3245 static inline void __skb_checksum_convert(struct sk_buff *skb,
3246                                           __sum16 check, __wsum pseudo)
3247 {
3248         skb->csum = ~pseudo;
3249         skb->ip_summed = CHECKSUM_COMPLETE;
3250 }
3251 
3252 #define skb_checksum_try_convert(skb, proto, check, compute_pseudo)     \
3253 do {                                                                    \
3254         if (__skb_checksum_convert_check(skb))                          \
3255                 __skb_checksum_convert(skb, check,                      \
3256                                        compute_pseudo(skb, proto));     \
3257 } while (0)
3258 
3259 static inline void skb_remcsum_adjust_partial(struct sk_buff *skb, void *ptr,
3260                                               u16 start, u16 offset)
3261 {
3262         skb->ip_summed = CHECKSUM_PARTIAL;
3263         skb->csum_start = ((unsigned char *)ptr + start) - skb->head;
3264         skb->csum_offset = offset - start;
3265 }
3266 
3267 /* Update skbuf and packet to reflect the remote checksum offload operation.
3268  * When called, ptr indicates the starting point for skb->csum when
3269  * ip_summed is CHECKSUM_COMPLETE. If we need create checksum complete
3270  * here, skb_postpull_rcsum is done so skb->csum start is ptr.
3271  */
3272 static inline void skb_remcsum_process(struct sk_buff *skb, void *ptr,
3273                                        int start, int offset, bool nopartial)
3274 {
3275         __wsum delta;
3276 
3277         if (!nopartial) {
3278                 skb_remcsum_adjust_partial(skb, ptr, start, offset);
3279                 return;
3280         }
3281 
3282          if (unlikely(skb->ip_summed != CHECKSUM_COMPLETE)) {
3283                 __skb_checksum_complete(skb);
3284                 skb_postpull_rcsum(skb, skb->data, ptr - (void *)skb->data);
3285         }
3286 
3287         delta = remcsum_adjust(ptr, skb->csum, start, offset);
3288 
3289         /* Adjust skb->csum since we changed the packet */
3290         skb->csum = csum_add(skb->csum, delta);
3291 }
3292 
3293 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
3294 void nf_conntrack_destroy(struct nf_conntrack *nfct);
3295 static inline void nf_conntrack_put(struct nf_conntrack *nfct)
3296 {
3297         if (nfct && atomic_dec_and_test(&nfct->use))
3298                 nf_conntrack_destroy(nfct);
3299 }
3300 static inline void nf_conntrack_get(struct nf_conntrack *nfct)
3301 {
3302         if (nfct)
3303                 atomic_inc(&nfct->use);
3304 }
3305 #endif
3306 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
3307 static inline void nf_bridge_put(struct nf_bridge_info *nf_bridge)
3308 {
3309         if (nf_bridge && atomic_dec_and_test(&nf_bridge->use))
3310                 kfree(nf_bridge);
3311 }
3312 static inline void nf_bridge_get(struct nf_bridge_info *nf_bridge)
3313 {
3314         if (nf_bridge)
3315                 atomic_inc(&nf_bridge->use);
3316 }
3317 #endif /* CONFIG_BRIDGE_NETFILTER */
3318 static inline void nf_reset(struct sk_buff *skb)
3319 {
3320 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
3321         nf_conntrack_put(skb->nfct);
3322         skb->nfct = NULL;
3323 #endif
3324 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
3325         nf_bridge_put(skb->nf_bridge);
3326         skb->nf_bridge = NULL;
3327 #endif
3328 }
3329 
3330 static inline void nf_reset_trace(struct sk_buff *skb)
3331 {
3332 #if IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TRACE) || defined(CONFIG_NF_TABLES)
3333         skb->nf_trace = 0;
3334 #endif
3335 }
3336 
3337 /* Note: This doesn't put any conntrack and bridge info in dst. */
3338 static inline void __nf_copy(struct sk_buff *dst, const struct sk_buff *src,
3339                              bool copy)
3340 {
3341 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
3342         dst->nfct = src->nfct;
3343         nf_conntrack_get(src->nfct);
3344         if (copy)
3345                 dst->nfctinfo = src->nfctinfo;
3346 #endif
3347 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
3348         dst->nf_bridge  = src->nf_bridge;
3349         nf_bridge_get(src->nf_bridge);
3350 #endif
3351 #if IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TRACE) || defined(CONFIG_NF_TABLES)
3352         if (copy)
3353                 dst->nf_trace = src->nf_trace;
3354 #endif
3355 }
3356 
3357 static inline void nf_copy(struct sk_buff *dst, const struct sk_buff *src)
3358 {
3359 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
3360         nf_conntrack_put(dst->nfct);
3361 #endif
3362 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
3363         nf_bridge_put(dst->nf_bridge);
3364 #endif
3365         __nf_copy(dst, src, true);
3366 }
3367 
3368 #ifdef CONFIG_NETWORK_SECMARK
3369 static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
3370 {
3371         to->secmark = from->secmark;
3372 }
3373 
3374 static inline void skb_init_secmark(struct sk_buff *skb)
3375 {
3376         skb->secmark = 0;
3377 }
3378 #else
3379 static inline void skb_copy_secmark(struct sk_buff *to, const struct sk_buff *from)
3380 { }
3381 
3382 static inline void skb_init_secmark(struct sk_buff *skb)
3383 { }
3384 #endif
3385 
3386 static inline bool skb_irq_freeable(const struct sk_buff *skb)
3387 {
3388         return !skb->destructor &&
3389 #if IS_ENABLED(CONFIG_XFRM)
3390                 !skb->sp &&
3391 #endif
3392 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
3393                 !skb->nfct &&
3394 #endif
3395                 !skb->_skb_refdst &&
3396                 !skb_has_frag_list(skb);
3397 }
3398 
3399 static inline void skb_set_queue_mapping(struct sk_buff *skb, u16 queue_mapping)
3400 {
3401         skb->queue_mapping = queue_mapping;
3402 }
3403 
3404 static inline u16 skb_get_queue_mapping(const struct sk_buff *skb)
3405 {
3406         return skb->queue_mapping;
3407 }
3408 
3409 static inline void skb_copy_queue_mapping(struct sk_buff *to, const struct sk_buff *from)
3410 {
3411         to->queue_mapping = from->queue_mapping;
3412 }
3413 
3414 static inline void skb_record_rx_queue(struct sk_buff *skb, u16 rx_queue)
3415 {
3416         skb->queue_mapping = rx_queue + 1;
3417 }
3418 
3419 static inline u16 skb_get_rx_queue(const struct sk_buff *skb)
3420 {
3421         return skb->queue_mapping - 1;
3422 }
3423 
3424 static inline bool skb_rx_queue_recorded(const struct sk_buff *skb)
3425 {
3426         return skb->queue_mapping != 0;
3427 }
3428 
3429 static inline struct sec_path *skb_sec_path(struct sk_buff *skb)
3430 {
3431 #ifdef CONFIG_XFRM
3432         return skb->sp;
3433 #else
3434         return NULL;
3435 #endif
3436 }
3437 
3438 /* Keeps track of mac header offset relative to skb->head.
3439  * It is useful for TSO of Tunneling protocol. e.g. GRE.
3440  * For non-tunnel skb it points to skb_mac_header() and for
3441  * tunnel skb it points to outer mac header.
3442  * Keeps track of level of encapsulation of network headers.
3443  */
3444 struct skb_gso_cb {
3445         int     mac_offset;
3446         int     encap_level;
3447         __u16   csum_start;
3448 };
3449 #define SKB_GSO_CB(skb) ((struct skb_gso_cb *)(skb)->cb)
3450 
3451 static inline int skb_tnl_header_len(const struct sk_buff *inner_skb)
3452 {
3453         return (skb_mac_header(inner_skb) - inner_skb->head) -
3454                 SKB_GSO_CB(inner_skb)->mac_offset;
3455 }
3456 
3457 static inline int gso_pskb_expand_head(struct sk_buff *skb, int extra)
3458 {
3459         int new_headroom, headroom;
3460         int ret;
3461 
3462         headroom = skb_headroom(skb);
3463         ret = pskb_expand_head(skb, extra, 0, GFP_ATOMIC);
3464         if (ret)
3465                 return ret;
3466 
3467         new_headroom = skb_headroom(skb);
3468         SKB_GSO_CB(skb)->mac_offset += (new_headroom - headroom);
3469         return 0;
3470 }
3471 
3472 /* Compute the checksum for a gso segment. First compute the checksum value
3473  * from the start of transport header to SKB_GSO_CB(skb)->csum_start, and
3474  * then add in skb->csum (checksum from csum_start to end of packet).
3475  * skb->csum and csum_start are then updated to reflect the checksum of the
3476  * resultant packet starting from the transport header-- the resultant checksum
3477  * is in the res argument (i.e. normally zero or ~ of checksum of a pseudo
3478  * header.
3479  */
3480 static inline __sum16 gso_make_checksum(struct sk_buff *skb, __wsum res)
3481 {
3482         int plen = SKB_GSO_CB(skb)->csum_start - skb_headroom(skb) -
3483                    skb_transport_offset(skb);
3484         __wsum partial;
3485 
3486         partial = csum_partial(skb_transport_header(skb), plen, skb->csum);
3487         skb->csum = res;
3488         SKB_GSO_CB(skb)->csum_start -= plen;
3489 
3490         return csum_fold(partial);
3491 }
3492 
3493 static inline bool skb_is_gso(const struct sk_buff *skb)
3494 {
3495         return skb_shinfo(skb)->gso_size;
3496 }
3497 
3498 /* Note: Should be called only if skb_is_gso(skb) is true */
3499 static inline bool skb_is_gso_v6(const struct sk_buff *skb)
3500 {
3501         return skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6;
3502 }
3503 
3504 void __skb_warn_lro_forwarding(const struct sk_buff *skb);
3505 
3506 static inline bool skb_warn_if_lro(const struct sk_buff *skb)
3507 {
3508         /* LRO sets gso_size but not gso_type, whereas if GSO is really
3509          * wanted then gso_type will be set. */
3510         const struct skb_shared_info *shinfo = skb_shinfo(skb);
3511 
3512         if (skb_is_nonlinear(skb) && shinfo->gso_size != 0 &&
3513             unlikely(shinfo->gso_type == 0)) {
3514                 __skb_warn_lro_forwarding(skb);
3515                 return true;
3516         }
3517         return false;
3518 }
3519 
3520 static inline void skb_forward_csum(struct sk_buff *skb)
3521 {
3522         /* Unfortunately we don't support this one.  Any brave souls? */
3523         if (skb->ip_summed == CHECKSUM_COMPLETE)
3524                 skb->ip_summed = CHECKSUM_NONE;
3525 }
3526 
3527 /**
3528  * skb_checksum_none_assert - make sure skb ip_summed is CHECKSUM_NONE
3529  * @skb: skb to check
3530  *
3531  * fresh skbs have their ip_summed set to CHECKSUM_NONE.
3532  * Instead of forcing ip_summed to CHECKSUM_NONE, we can
3533  * use this helper, to document places where we make this assertion.
3534  */
3535 static inline void skb_checksum_none_assert(const struct sk_buff *skb)
3536 {
3537 #ifdef DEBUG
3538         BUG_ON(skb->ip_summed != CHECKSUM_NONE);
3539 #endif
3540 }
3541 
3542 bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off);
3543 
3544 int skb_checksum_setup(struct sk_buff *skb, bool recalculate);
3545 struct sk_buff *skb_checksum_trimmed(struct sk_buff *skb,
3546                                      unsigned int transport_len,
3547                                      __sum16(*skb_chkf)(struct sk_buff *skb));
3548 
3549 /**
3550  * skb_head_is_locked - Determine if the skb->head is locked down
3551  * @skb: skb to check
3552  *
3553  * The head on skbs build around a head frag can be removed if they are
3554  * not cloned.  This function returns true if the skb head is locked down
3555  * due to either being allocated via kmalloc, or by being a clone with
3556  * multiple references to the head.
3557  */
3558 static inline bool skb_head_is_locked(const struct sk_buff *skb)
3559 {
3560         return !skb->head_frag || skb_cloned(skb);
3561 }
3562 
3563 /**
3564  * skb_gso_network_seglen - Return length of individual segments of a gso packet
3565  *
3566  * @skb: GSO skb
3567  *
3568  * skb_gso_network_seglen is used to determine the real size of the
3569  * individual segments, including Layer3 (IP, IPv6) and L4 headers (TCP/UDP).
3570  *
3571  * The MAC/L2 header is not accounted for.
3572  */
3573 static inline unsigned int skb_gso_network_seglen(const struct sk_buff *skb)
3574 {
3575         unsigned int hdr_len = skb_transport_header(skb) -
3576                                skb_network_header(skb);
3577         return hdr_len + skb_gso_transport_seglen(skb);
3578 }
3579 
3580 #endif  /* __KERNEL__ */
3581 #endif  /* _LINUX_SKBUFF_H */
3582 

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