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

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