xref: /linux/include/net/ip.h (revision f79e4d5f92a129a1159c973735007d4ddc8541f3)
1 /*
2  * INET		An implementation of the TCP/IP protocol suite for the LINUX
3  *		operating system.  INET is implemented using the  BSD Socket
4  *		interface as the means of communication with the user level.
5  *
6  *		Definitions for the IP module.
7  *
8  * Version:	@(#)ip.h	1.0.2	05/07/93
9  *
10  * Authors:	Ross Biro
11  *		Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
12  *		Alan Cox, <gw4pts@gw4pts.ampr.org>
13  *
14  * Changes:
15  *		Mike McLagan    :       Routing by source
16  *
17  *		This program is free software; you can redistribute it and/or
18  *		modify it under the terms of the GNU General Public License
19  *		as published by the Free Software Foundation; either version
20  *		2 of the License, or (at your option) any later version.
21  */
22 #ifndef _IP_H
23 #define _IP_H
24 
25 #include <linux/types.h>
26 #include <linux/ip.h>
27 #include <linux/in.h>
28 #include <linux/skbuff.h>
29 #include <linux/jhash.h>
30 
31 #include <net/inet_sock.h>
32 #include <net/route.h>
33 #include <net/snmp.h>
34 #include <net/flow.h>
35 #include <net/flow_dissector.h>
36 #include <net/netns/hash.h>
37 
38 #define IPV4_MAX_PMTU		65535U		/* RFC 2675, Section 5.1 */
39 #define IPV4_MIN_MTU		68			/* RFC 791 */
40 
41 struct sock;
42 
43 struct inet_skb_parm {
44 	int			iif;
45 	struct ip_options	opt;		/* Compiled IP options		*/
46 	u16			flags;
47 
48 #define IPSKB_FORWARDED		BIT(0)
49 #define IPSKB_XFRM_TUNNEL_SIZE	BIT(1)
50 #define IPSKB_XFRM_TRANSFORMED	BIT(2)
51 #define IPSKB_FRAG_COMPLETE	BIT(3)
52 #define IPSKB_REROUTED		BIT(4)
53 #define IPSKB_DOREDIRECT	BIT(5)
54 #define IPSKB_FRAG_PMTU		BIT(6)
55 #define IPSKB_L3SLAVE		BIT(7)
56 
57 	u16			frag_max_size;
58 };
59 
60 static inline bool ipv4_l3mdev_skb(u16 flags)
61 {
62 	return !!(flags & IPSKB_L3SLAVE);
63 }
64 
65 static inline unsigned int ip_hdrlen(const struct sk_buff *skb)
66 {
67 	return ip_hdr(skb)->ihl * 4;
68 }
69 
70 struct ipcm_cookie {
71 	struct sockcm_cookie	sockc;
72 	__be32			addr;
73 	int			oif;
74 	struct ip_options_rcu	*opt;
75 	__u8			tx_flags;
76 	__u8			ttl;
77 	__s16			tos;
78 	char			priority;
79 	__u16			gso_size;
80 };
81 
82 #define IPCB(skb) ((struct inet_skb_parm*)((skb)->cb))
83 #define PKTINFO_SKB_CB(skb) ((struct in_pktinfo *)((skb)->cb))
84 
85 /* return enslaved device index if relevant */
86 static inline int inet_sdif(struct sk_buff *skb)
87 {
88 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
89 	if (skb && ipv4_l3mdev_skb(IPCB(skb)->flags))
90 		return IPCB(skb)->iif;
91 #endif
92 	return 0;
93 }
94 
95 /* Special input handler for packets caught by router alert option.
96    They are selected only by protocol field, and then processed likely
97    local ones; but only if someone wants them! Otherwise, router
98    not running rsvpd will kill RSVP.
99 
100    It is user level problem, what it will make with them.
101    I have no idea, how it will masquearde or NAT them (it is joke, joke :-)),
102    but receiver should be enough clever f.e. to forward mtrace requests,
103    sent to multicast group to reach destination designated router.
104  */
105 
106 struct ip_ra_chain {
107 	struct ip_ra_chain __rcu *next;
108 	struct sock		*sk;
109 	union {
110 		void			(*destructor)(struct sock *);
111 		struct sock		*saved_sk;
112 	};
113 	struct rcu_head		rcu;
114 };
115 
116 /* IP flags. */
117 #define IP_CE		0x8000		/* Flag: "Congestion"		*/
118 #define IP_DF		0x4000		/* Flag: "Don't Fragment"	*/
119 #define IP_MF		0x2000		/* Flag: "More Fragments"	*/
120 #define IP_OFFSET	0x1FFF		/* "Fragment Offset" part	*/
121 
122 #define IP_FRAG_TIME	(30 * HZ)		/* fragment lifetime	*/
123 
124 struct msghdr;
125 struct net_device;
126 struct packet_type;
127 struct rtable;
128 struct sockaddr;
129 
130 int igmp_mc_init(void);
131 
132 /*
133  *	Functions provided by ip.c
134  */
135 
136 int ip_build_and_send_pkt(struct sk_buff *skb, const struct sock *sk,
137 			  __be32 saddr, __be32 daddr,
138 			  struct ip_options_rcu *opt);
139 int ip_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt,
140 	   struct net_device *orig_dev);
141 int ip_local_deliver(struct sk_buff *skb);
142 int ip_mr_input(struct sk_buff *skb);
143 int ip_output(struct net *net, struct sock *sk, struct sk_buff *skb);
144 int ip_mc_output(struct net *net, struct sock *sk, struct sk_buff *skb);
145 int ip_do_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
146 		   int (*output)(struct net *, struct sock *, struct sk_buff *));
147 void ip_send_check(struct iphdr *ip);
148 int __ip_local_out(struct net *net, struct sock *sk, struct sk_buff *skb);
149 int ip_local_out(struct net *net, struct sock *sk, struct sk_buff *skb);
150 
151 int ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl);
152 void ip_init(void);
153 int ip_append_data(struct sock *sk, struct flowi4 *fl4,
154 		   int getfrag(void *from, char *to, int offset, int len,
155 			       int odd, struct sk_buff *skb),
156 		   void *from, int len, int protolen,
157 		   struct ipcm_cookie *ipc,
158 		   struct rtable **rt,
159 		   unsigned int flags);
160 int ip_generic_getfrag(void *from, char *to, int offset, int len, int odd,
161 		       struct sk_buff *skb);
162 ssize_t ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page,
163 		       int offset, size_t size, int flags);
164 struct sk_buff *__ip_make_skb(struct sock *sk, struct flowi4 *fl4,
165 			      struct sk_buff_head *queue,
166 			      struct inet_cork *cork);
167 int ip_send_skb(struct net *net, struct sk_buff *skb);
168 int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4);
169 void ip_flush_pending_frames(struct sock *sk);
170 struct sk_buff *ip_make_skb(struct sock *sk, struct flowi4 *fl4,
171 			    int getfrag(void *from, char *to, int offset,
172 					int len, int odd, struct sk_buff *skb),
173 			    void *from, int length, int transhdrlen,
174 			    struct ipcm_cookie *ipc, struct rtable **rtp,
175 			    struct inet_cork *cork, unsigned int flags);
176 
177 static inline struct sk_buff *ip_finish_skb(struct sock *sk, struct flowi4 *fl4)
178 {
179 	return __ip_make_skb(sk, fl4, &sk->sk_write_queue, &inet_sk(sk)->cork.base);
180 }
181 
182 static inline __u8 get_rttos(struct ipcm_cookie* ipc, struct inet_sock *inet)
183 {
184 	return (ipc->tos != -1) ? RT_TOS(ipc->tos) : RT_TOS(inet->tos);
185 }
186 
187 static inline __u8 get_rtconn_flags(struct ipcm_cookie* ipc, struct sock* sk)
188 {
189 	return (ipc->tos != -1) ? RT_CONN_FLAGS_TOS(sk, ipc->tos) : RT_CONN_FLAGS(sk);
190 }
191 
192 /* datagram.c */
193 int __ip4_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
194 int ip4_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
195 
196 void ip4_datagram_release_cb(struct sock *sk);
197 
198 struct ip_reply_arg {
199 	struct kvec iov[1];
200 	int	    flags;
201 	__wsum 	    csum;
202 	int	    csumoffset; /* u16 offset of csum in iov[0].iov_base */
203 				/* -1 if not needed */
204 	int	    bound_dev_if;
205 	u8  	    tos;
206 	kuid_t	    uid;
207 };
208 
209 #define IP_REPLY_ARG_NOSRCCHECK 1
210 
211 static inline __u8 ip_reply_arg_flowi_flags(const struct ip_reply_arg *arg)
212 {
213 	return (arg->flags & IP_REPLY_ARG_NOSRCCHECK) ? FLOWI_FLAG_ANYSRC : 0;
214 }
215 
216 void ip_send_unicast_reply(struct sock *sk, struct sk_buff *skb,
217 			   const struct ip_options *sopt,
218 			   __be32 daddr, __be32 saddr,
219 			   const struct ip_reply_arg *arg,
220 			   unsigned int len);
221 
222 #define IP_INC_STATS(net, field)	SNMP_INC_STATS64((net)->mib.ip_statistics, field)
223 #define __IP_INC_STATS(net, field)	__SNMP_INC_STATS64((net)->mib.ip_statistics, field)
224 #define IP_ADD_STATS(net, field, val)	SNMP_ADD_STATS64((net)->mib.ip_statistics, field, val)
225 #define __IP_ADD_STATS(net, field, val) __SNMP_ADD_STATS64((net)->mib.ip_statistics, field, val)
226 #define IP_UPD_PO_STATS(net, field, val) SNMP_UPD_PO_STATS64((net)->mib.ip_statistics, field, val)
227 #define __IP_UPD_PO_STATS(net, field, val) __SNMP_UPD_PO_STATS64((net)->mib.ip_statistics, field, val)
228 #define NET_INC_STATS(net, field)	SNMP_INC_STATS((net)->mib.net_statistics, field)
229 #define __NET_INC_STATS(net, field)	__SNMP_INC_STATS((net)->mib.net_statistics, field)
230 #define NET_ADD_STATS(net, field, adnd)	SNMP_ADD_STATS((net)->mib.net_statistics, field, adnd)
231 #define __NET_ADD_STATS(net, field, adnd) __SNMP_ADD_STATS((net)->mib.net_statistics, field, adnd)
232 
233 u64 snmp_get_cpu_field(void __percpu *mib, int cpu, int offct);
234 unsigned long snmp_fold_field(void __percpu *mib, int offt);
235 #if BITS_PER_LONG==32
236 u64 snmp_get_cpu_field64(void __percpu *mib, int cpu, int offct,
237 			 size_t syncp_offset);
238 u64 snmp_fold_field64(void __percpu *mib, int offt, size_t sync_off);
239 #else
240 static inline u64  snmp_get_cpu_field64(void __percpu *mib, int cpu, int offct,
241 					size_t syncp_offset)
242 {
243 	return snmp_get_cpu_field(mib, cpu, offct);
244 
245 }
246 
247 static inline u64 snmp_fold_field64(void __percpu *mib, int offt, size_t syncp_off)
248 {
249 	return snmp_fold_field(mib, offt);
250 }
251 #endif
252 
253 #define snmp_get_cpu_field64_batch(buff64, stats_list, mib_statistic, offset) \
254 { \
255 	int i, c; \
256 	for_each_possible_cpu(c) { \
257 		for (i = 0; stats_list[i].name; i++) \
258 			buff64[i] += snmp_get_cpu_field64( \
259 					mib_statistic, \
260 					c, stats_list[i].entry, \
261 					offset); \
262 	} \
263 }
264 
265 #define snmp_get_cpu_field_batch(buff, stats_list, mib_statistic) \
266 { \
267 	int i, c; \
268 	for_each_possible_cpu(c) { \
269 		for (i = 0; stats_list[i].name; i++) \
270 			buff[i] += snmp_get_cpu_field( \
271 						mib_statistic, \
272 						c, stats_list[i].entry); \
273 	} \
274 }
275 
276 void inet_get_local_port_range(struct net *net, int *low, int *high);
277 
278 #ifdef CONFIG_SYSCTL
279 static inline int inet_is_local_reserved_port(struct net *net, int port)
280 {
281 	if (!net->ipv4.sysctl_local_reserved_ports)
282 		return 0;
283 	return test_bit(port, net->ipv4.sysctl_local_reserved_ports);
284 }
285 
286 static inline bool sysctl_dev_name_is_allowed(const char *name)
287 {
288 	return strcmp(name, "default") != 0  && strcmp(name, "all") != 0;
289 }
290 
291 static inline int inet_prot_sock(struct net *net)
292 {
293 	return net->ipv4.sysctl_ip_prot_sock;
294 }
295 
296 #else
297 static inline int inet_is_local_reserved_port(struct net *net, int port)
298 {
299 	return 0;
300 }
301 
302 static inline int inet_prot_sock(struct net *net)
303 {
304 	return PROT_SOCK;
305 }
306 #endif
307 
308 __be32 inet_current_timestamp(void);
309 
310 /* From inetpeer.c */
311 extern int inet_peer_threshold;
312 extern int inet_peer_minttl;
313 extern int inet_peer_maxttl;
314 
315 void ipfrag_init(void);
316 
317 void ip_static_sysctl_init(void);
318 
319 #define IP4_REPLY_MARK(net, mark) \
320 	((net)->ipv4.sysctl_fwmark_reflect ? (mark) : 0)
321 
322 static inline bool ip_is_fragment(const struct iphdr *iph)
323 {
324 	return (iph->frag_off & htons(IP_MF | IP_OFFSET)) != 0;
325 }
326 
327 #ifdef CONFIG_INET
328 #include <net/dst.h>
329 
330 /* The function in 2.2 was invalid, producing wrong result for
331  * check=0xFEFF. It was noticed by Arthur Skawina _year_ ago. --ANK(000625) */
332 static inline
333 int ip_decrease_ttl(struct iphdr *iph)
334 {
335 	u32 check = (__force u32)iph->check;
336 	check += (__force u32)htons(0x0100);
337 	iph->check = (__force __sum16)(check + (check>=0xFFFF));
338 	return --iph->ttl;
339 }
340 
341 static inline int ip_mtu_locked(const struct dst_entry *dst)
342 {
343 	const struct rtable *rt = (const struct rtable *)dst;
344 
345 	return rt->rt_mtu_locked || dst_metric_locked(dst, RTAX_MTU);
346 }
347 
348 static inline
349 int ip_dont_fragment(const struct sock *sk, const struct dst_entry *dst)
350 {
351 	u8 pmtudisc = READ_ONCE(inet_sk(sk)->pmtudisc);
352 
353 	return  pmtudisc == IP_PMTUDISC_DO ||
354 		(pmtudisc == IP_PMTUDISC_WANT &&
355 		 !ip_mtu_locked(dst));
356 }
357 
358 static inline bool ip_sk_accept_pmtu(const struct sock *sk)
359 {
360 	return inet_sk(sk)->pmtudisc != IP_PMTUDISC_INTERFACE &&
361 	       inet_sk(sk)->pmtudisc != IP_PMTUDISC_OMIT;
362 }
363 
364 static inline bool ip_sk_use_pmtu(const struct sock *sk)
365 {
366 	return inet_sk(sk)->pmtudisc < IP_PMTUDISC_PROBE;
367 }
368 
369 static inline bool ip_sk_ignore_df(const struct sock *sk)
370 {
371 	return inet_sk(sk)->pmtudisc < IP_PMTUDISC_DO ||
372 	       inet_sk(sk)->pmtudisc == IP_PMTUDISC_OMIT;
373 }
374 
375 static inline unsigned int ip_dst_mtu_maybe_forward(const struct dst_entry *dst,
376 						    bool forwarding)
377 {
378 	struct net *net = dev_net(dst->dev);
379 
380 	if (net->ipv4.sysctl_ip_fwd_use_pmtu ||
381 	    ip_mtu_locked(dst) ||
382 	    !forwarding)
383 		return dst_mtu(dst);
384 
385 	return min(READ_ONCE(dst->dev->mtu), IP_MAX_MTU);
386 }
387 
388 static inline unsigned int ip_skb_dst_mtu(struct sock *sk,
389 					  const struct sk_buff *skb)
390 {
391 	if (!sk || !sk_fullsock(sk) || ip_sk_use_pmtu(sk)) {
392 		bool forwarding = IPCB(skb)->flags & IPSKB_FORWARDED;
393 
394 		return ip_dst_mtu_maybe_forward(skb_dst(skb), forwarding);
395 	}
396 
397 	return min(READ_ONCE(skb_dst(skb)->dev->mtu), IP_MAX_MTU);
398 }
399 
400 int ip_metrics_convert(struct net *net, struct nlattr *fc_mx, int fc_mx_len,
401 		       u32 *metrics);
402 
403 u32 ip_idents_reserve(u32 hash, int segs);
404 void __ip_select_ident(struct net *net, struct iphdr *iph, int segs);
405 
406 static inline void ip_select_ident_segs(struct net *net, struct sk_buff *skb,
407 					struct sock *sk, int segs)
408 {
409 	struct iphdr *iph = ip_hdr(skb);
410 
411 	if ((iph->frag_off & htons(IP_DF)) && !skb->ignore_df) {
412 		/* This is only to work around buggy Windows95/2000
413 		 * VJ compression implementations.  If the ID field
414 		 * does not change, they drop every other packet in
415 		 * a TCP stream using header compression.
416 		 */
417 		if (sk && inet_sk(sk)->inet_daddr) {
418 			iph->id = htons(inet_sk(sk)->inet_id);
419 			inet_sk(sk)->inet_id += segs;
420 		} else {
421 			iph->id = 0;
422 		}
423 	} else {
424 		__ip_select_ident(net, iph, segs);
425 	}
426 }
427 
428 static inline void ip_select_ident(struct net *net, struct sk_buff *skb,
429 				   struct sock *sk)
430 {
431 	ip_select_ident_segs(net, skb, sk, 1);
432 }
433 
434 static inline __wsum inet_compute_pseudo(struct sk_buff *skb, int proto)
435 {
436 	return csum_tcpudp_nofold(ip_hdr(skb)->saddr, ip_hdr(skb)->daddr,
437 				  skb->len, proto, 0);
438 }
439 
440 /* copy IPv4 saddr & daddr to flow_keys, possibly using 64bit load/store
441  * Equivalent to :	flow->v4addrs.src = iph->saddr;
442  *			flow->v4addrs.dst = iph->daddr;
443  */
444 static inline void iph_to_flow_copy_v4addrs(struct flow_keys *flow,
445 					    const struct iphdr *iph)
446 {
447 	BUILD_BUG_ON(offsetof(typeof(flow->addrs), v4addrs.dst) !=
448 		     offsetof(typeof(flow->addrs), v4addrs.src) +
449 			      sizeof(flow->addrs.v4addrs.src));
450 	memcpy(&flow->addrs.v4addrs, &iph->saddr, sizeof(flow->addrs.v4addrs));
451 	flow->control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
452 }
453 
454 static inline __wsum inet_gro_compute_pseudo(struct sk_buff *skb, int proto)
455 {
456 	const struct iphdr *iph = skb_gro_network_header(skb);
457 
458 	return csum_tcpudp_nofold(iph->saddr, iph->daddr,
459 				  skb_gro_len(skb), proto, 0);
460 }
461 
462 /*
463  *	Map a multicast IP onto multicast MAC for type ethernet.
464  */
465 
466 static inline void ip_eth_mc_map(__be32 naddr, char *buf)
467 {
468 	__u32 addr=ntohl(naddr);
469 	buf[0]=0x01;
470 	buf[1]=0x00;
471 	buf[2]=0x5e;
472 	buf[5]=addr&0xFF;
473 	addr>>=8;
474 	buf[4]=addr&0xFF;
475 	addr>>=8;
476 	buf[3]=addr&0x7F;
477 }
478 
479 /*
480  *	Map a multicast IP onto multicast MAC for type IP-over-InfiniBand.
481  *	Leave P_Key as 0 to be filled in by driver.
482  */
483 
484 static inline void ip_ib_mc_map(__be32 naddr, const unsigned char *broadcast, char *buf)
485 {
486 	__u32 addr;
487 	unsigned char scope = broadcast[5] & 0xF;
488 
489 	buf[0]  = 0;		/* Reserved */
490 	buf[1]  = 0xff;		/* Multicast QPN */
491 	buf[2]  = 0xff;
492 	buf[3]  = 0xff;
493 	addr    = ntohl(naddr);
494 	buf[4]  = 0xff;
495 	buf[5]  = 0x10 | scope;	/* scope from broadcast address */
496 	buf[6]  = 0x40;		/* IPv4 signature */
497 	buf[7]  = 0x1b;
498 	buf[8]  = broadcast[8];		/* P_Key */
499 	buf[9]  = broadcast[9];
500 	buf[10] = 0;
501 	buf[11] = 0;
502 	buf[12] = 0;
503 	buf[13] = 0;
504 	buf[14] = 0;
505 	buf[15] = 0;
506 	buf[19] = addr & 0xff;
507 	addr  >>= 8;
508 	buf[18] = addr & 0xff;
509 	addr  >>= 8;
510 	buf[17] = addr & 0xff;
511 	addr  >>= 8;
512 	buf[16] = addr & 0x0f;
513 }
514 
515 static inline void ip_ipgre_mc_map(__be32 naddr, const unsigned char *broadcast, char *buf)
516 {
517 	if ((broadcast[0] | broadcast[1] | broadcast[2] | broadcast[3]) != 0)
518 		memcpy(buf, broadcast, 4);
519 	else
520 		memcpy(buf, &naddr, sizeof(naddr));
521 }
522 
523 #if IS_ENABLED(CONFIG_IPV6)
524 #include <linux/ipv6.h>
525 #endif
526 
527 static __inline__ void inet_reset_saddr(struct sock *sk)
528 {
529 	inet_sk(sk)->inet_rcv_saddr = inet_sk(sk)->inet_saddr = 0;
530 #if IS_ENABLED(CONFIG_IPV6)
531 	if (sk->sk_family == PF_INET6) {
532 		struct ipv6_pinfo *np = inet6_sk(sk);
533 
534 		memset(&np->saddr, 0, sizeof(np->saddr));
535 		memset(&sk->sk_v6_rcv_saddr, 0, sizeof(sk->sk_v6_rcv_saddr));
536 	}
537 #endif
538 }
539 
540 #endif
541 
542 static inline unsigned int ipv4_addr_hash(__be32 ip)
543 {
544 	return (__force unsigned int) ip;
545 }
546 
547 static inline u32 ipv4_portaddr_hash(const struct net *net,
548 				     __be32 saddr,
549 				     unsigned int port)
550 {
551 	return jhash_1word((__force u32)saddr, net_hash_mix(net)) ^ port;
552 }
553 
554 bool ip_call_ra_chain(struct sk_buff *skb);
555 
556 /*
557  *	Functions provided by ip_fragment.c
558  */
559 
560 enum ip_defrag_users {
561 	IP_DEFRAG_LOCAL_DELIVER,
562 	IP_DEFRAG_CALL_RA_CHAIN,
563 	IP_DEFRAG_CONNTRACK_IN,
564 	__IP_DEFRAG_CONNTRACK_IN_END	= IP_DEFRAG_CONNTRACK_IN + USHRT_MAX,
565 	IP_DEFRAG_CONNTRACK_OUT,
566 	__IP_DEFRAG_CONNTRACK_OUT_END	= IP_DEFRAG_CONNTRACK_OUT + USHRT_MAX,
567 	IP_DEFRAG_CONNTRACK_BRIDGE_IN,
568 	__IP_DEFRAG_CONNTRACK_BRIDGE_IN = IP_DEFRAG_CONNTRACK_BRIDGE_IN + USHRT_MAX,
569 	IP_DEFRAG_VS_IN,
570 	IP_DEFRAG_VS_OUT,
571 	IP_DEFRAG_VS_FWD,
572 	IP_DEFRAG_AF_PACKET,
573 	IP_DEFRAG_MACVLAN,
574 };
575 
576 /* Return true if the value of 'user' is between 'lower_bond'
577  * and 'upper_bond' inclusively.
578  */
579 static inline bool ip_defrag_user_in_between(u32 user,
580 					     enum ip_defrag_users lower_bond,
581 					     enum ip_defrag_users upper_bond)
582 {
583 	return user >= lower_bond && user <= upper_bond;
584 }
585 
586 int ip_defrag(struct net *net, struct sk_buff *skb, u32 user);
587 #ifdef CONFIG_INET
588 struct sk_buff *ip_check_defrag(struct net *net, struct sk_buff *skb, u32 user);
589 #else
590 static inline struct sk_buff *ip_check_defrag(struct net *net, struct sk_buff *skb, u32 user)
591 {
592 	return skb;
593 }
594 #endif
595 
596 /*
597  *	Functions provided by ip_forward.c
598  */
599 
600 int ip_forward(struct sk_buff *skb);
601 
602 /*
603  *	Functions provided by ip_options.c
604  */
605 
606 void ip_options_build(struct sk_buff *skb, struct ip_options *opt,
607 		      __be32 daddr, struct rtable *rt, int is_frag);
608 
609 int __ip_options_echo(struct net *net, struct ip_options *dopt,
610 		      struct sk_buff *skb, const struct ip_options *sopt);
611 static inline int ip_options_echo(struct net *net, struct ip_options *dopt,
612 				  struct sk_buff *skb)
613 {
614 	return __ip_options_echo(net, dopt, skb, &IPCB(skb)->opt);
615 }
616 
617 void ip_options_fragment(struct sk_buff *skb);
618 int ip_options_compile(struct net *net, struct ip_options *opt,
619 		       struct sk_buff *skb);
620 int ip_options_get(struct net *net, struct ip_options_rcu **optp,
621 		   unsigned char *data, int optlen);
622 int ip_options_get_from_user(struct net *net, struct ip_options_rcu **optp,
623 			     unsigned char __user *data, int optlen);
624 void ip_options_undo(struct ip_options *opt);
625 void ip_forward_options(struct sk_buff *skb);
626 int ip_options_rcv_srr(struct sk_buff *skb);
627 
628 /*
629  *	Functions provided by ip_sockglue.c
630  */
631 
632 void ipv4_pktinfo_prepare(const struct sock *sk, struct sk_buff *skb);
633 void ip_cmsg_recv_offset(struct msghdr *msg, struct sock *sk,
634 			 struct sk_buff *skb, int tlen, int offset);
635 int ip_cmsg_send(struct sock *sk, struct msghdr *msg,
636 		 struct ipcm_cookie *ipc, bool allow_ipv6);
637 int ip_setsockopt(struct sock *sk, int level, int optname, char __user *optval,
638 		  unsigned int optlen);
639 int ip_getsockopt(struct sock *sk, int level, int optname, char __user *optval,
640 		  int __user *optlen);
641 int compat_ip_setsockopt(struct sock *sk, int level, int optname,
642 			 char __user *optval, unsigned int optlen);
643 int compat_ip_getsockopt(struct sock *sk, int level, int optname,
644 			 char __user *optval, int __user *optlen);
645 int ip_ra_control(struct sock *sk, unsigned char on,
646 		  void (*destructor)(struct sock *));
647 
648 int ip_recv_error(struct sock *sk, struct msghdr *msg, int len, int *addr_len);
649 void ip_icmp_error(struct sock *sk, struct sk_buff *skb, int err, __be16 port,
650 		   u32 info, u8 *payload);
651 void ip_local_error(struct sock *sk, int err, __be32 daddr, __be16 dport,
652 		    u32 info);
653 
654 static inline void ip_cmsg_recv(struct msghdr *msg, struct sk_buff *skb)
655 {
656 	ip_cmsg_recv_offset(msg, skb->sk, skb, 0, 0);
657 }
658 
659 bool icmp_global_allow(void);
660 extern int sysctl_icmp_msgs_per_sec;
661 extern int sysctl_icmp_msgs_burst;
662 
663 #ifdef CONFIG_PROC_FS
664 int ip_misc_proc_init(void);
665 #endif
666 
667 int rtm_getroute_parse_ip_proto(struct nlattr *attr, u8 *ip_proto,
668 				struct netlink_ext_ack *extack);
669 
670 #endif	/* _IP_H */
671