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.
6 * The Internet Protocol (IP) output module.
9 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
10 * Donald Becker, <becker@super.org>
11 * Alan Cox, <Alan.Cox@linux.org>
13 * Stefan Becker, <stefanb@yello.ping.de>
14 * Jorge Cwik, <jorge@laser.satlink.net>
15 * Arnt Gulbrandsen, <agulbra@nvg.unit.no>
16 * Hirokazu Takahashi, <taka@valinux.co.jp>
18 * See ip_input.c for original log
21 * Alan Cox : Missing nonblock feature in ip_build_xmit.
22 * Mike Kilburn : htons() missing in ip_build_xmit.
23 * Bradford Johnson: Fix faulty handling of some frames when
25 * Alexander Demenshin: Missing sk/skb free in ip_queue_xmit
26 * (in case if packet not accepted by
27 * output firewall rules)
28 * Mike McLagan : Routing by source
29 * Alexey Kuznetsov: use new route cache
30 * Andi Kleen: Fix broken PMTU recovery and remove
31 * some redundant tests.
32 * Vitaly E. Lavrov : Transparent proxy revived after year coma.
33 * Andi Kleen : Replace ip_reply with ip_send_reply.
34 * Andi Kleen : Split fast and slow ip_build_xmit path
35 * for decreased register pressure on x86
36 * and more readibility.
37 * Marc Boucher : When call_out_firewall returns FW_QUEUE,
38 * silently drop skb instead of failing with -EPERM.
39 * Detlev Wengorz : Copy protocol for fragments.
40 * Hirokazu Takahashi: HW checksumming for outgoing UDP
42 * Hirokazu Takahashi: sendfile() on UDP works now.
45 #include <asm/uaccess.h>
46 #include <linux/module.h>
47 #include <linux/types.h>
48 #include <linux/kernel.h>
50 #include <linux/string.h>
51 #include <linux/errno.h>
52 #include <linux/highmem.h>
53 #include <linux/slab.h>
55 #include <linux/socket.h>
56 #include <linux/sockios.h>
58 #include <linux/inet.h>
59 #include <linux/netdevice.h>
60 #include <linux/etherdevice.h>
61 #include <linux/proc_fs.h>
62 #include <linux/stat.h>
63 #include <linux/init.h>
67 #include <net/protocol.h>
68 #include <net/route.h>
70 #include <linux/skbuff.h>
74 #include <net/checksum.h>
75 #include <net/inetpeer.h>
76 #include <linux/igmp.h>
77 #include <linux/netfilter_ipv4.h>
78 #include <linux/netfilter_bridge.h>
79 #include <linux/mroute.h>
80 #include <linux/netlink.h>
81 #include <linux/tcp.h>
83 int sysctl_ip_default_ttl __read_mostly
= IPDEFTTL
;
84 EXPORT_SYMBOL(sysctl_ip_default_ttl
);
87 ip_fragment(struct net
*net
, struct sock
*sk
, struct sk_buff
*skb
,
89 int (*output
)(struct net
*, struct sock
*, struct sk_buff
*));
91 /* Generate a checksum for an outgoing IP datagram. */
92 void ip_send_check(struct iphdr
*iph
)
95 iph
->check
= ip_fast_csum((unsigned char *)iph
, iph
->ihl
);
97 EXPORT_SYMBOL(ip_send_check
);
99 int __ip_local_out_sk(struct sock
*sk
, struct sk_buff
*skb
)
101 struct net
*net
= dev_net(skb_dst(skb
)->dev
);
102 struct iphdr
*iph
= ip_hdr(skb
);
104 iph
->tot_len
= htons(skb
->len
);
106 return nf_hook(NFPROTO_IPV4
, NF_INET_LOCAL_OUT
,
107 net
, sk
, skb
, NULL
, skb_dst(skb
)->dev
,
111 int __ip_local_out(struct sk_buff
*skb
)
113 return __ip_local_out_sk(skb
->sk
, skb
);
116 int ip_local_out_sk(struct sock
*sk
, struct sk_buff
*skb
)
118 struct net
*net
= dev_net(skb_dst(skb
)->dev
);
121 err
= __ip_local_out_sk(sk
, skb
);
122 if (likely(err
== 1))
123 err
= dst_output(net
, sk
, skb
);
127 EXPORT_SYMBOL_GPL(ip_local_out_sk
);
129 static inline int ip_select_ttl(struct inet_sock
*inet
, struct dst_entry
*dst
)
131 int ttl
= inet
->uc_ttl
;
134 ttl
= ip4_dst_hoplimit(dst
);
139 * Add an ip header to a skbuff and send it out.
142 int ip_build_and_send_pkt(struct sk_buff
*skb
, const struct sock
*sk
,
143 __be32 saddr
, __be32 daddr
, struct ip_options_rcu
*opt
)
145 struct inet_sock
*inet
= inet_sk(sk
);
146 struct rtable
*rt
= skb_rtable(skb
);
149 /* Build the IP header. */
150 skb_push(skb
, sizeof(struct iphdr
) + (opt
? opt
->opt
.optlen
: 0));
151 skb_reset_network_header(skb
);
155 iph
->tos
= inet
->tos
;
156 iph
->ttl
= ip_select_ttl(inet
, &rt
->dst
);
157 iph
->daddr
= (opt
&& opt
->opt
.srr
? opt
->opt
.faddr
: daddr
);
159 iph
->protocol
= sk
->sk_protocol
;
160 if (ip_dont_fragment(sk
, &rt
->dst
)) {
161 iph
->frag_off
= htons(IP_DF
);
165 __ip_select_ident(sock_net(sk
), iph
, 1);
168 if (opt
&& opt
->opt
.optlen
) {
169 iph
->ihl
+= opt
->opt
.optlen
>>2;
170 ip_options_build(skb
, &opt
->opt
, daddr
, rt
, 0);
173 skb
->priority
= sk
->sk_priority
;
174 skb
->mark
= sk
->sk_mark
;
177 return ip_local_out(skb
);
179 EXPORT_SYMBOL_GPL(ip_build_and_send_pkt
);
181 static int ip_finish_output2(struct net
*net
, struct sock
*sk
, struct sk_buff
*skb
)
183 struct dst_entry
*dst
= skb_dst(skb
);
184 struct rtable
*rt
= (struct rtable
*)dst
;
185 struct net_device
*dev
= dst
->dev
;
186 unsigned int hh_len
= LL_RESERVED_SPACE(dev
);
187 struct neighbour
*neigh
;
190 if (rt
->rt_type
== RTN_MULTICAST
) {
191 IP_UPD_PO_STATS(net
, IPSTATS_MIB_OUTMCAST
, skb
->len
);
192 } else if (rt
->rt_type
== RTN_BROADCAST
)
193 IP_UPD_PO_STATS(net
, IPSTATS_MIB_OUTBCAST
, skb
->len
);
195 /* Be paranoid, rather than too clever. */
196 if (unlikely(skb_headroom(skb
) < hh_len
&& dev
->header_ops
)) {
197 struct sk_buff
*skb2
;
199 skb2
= skb_realloc_headroom(skb
, LL_RESERVED_SPACE(dev
));
205 skb_set_owner_w(skb2
, skb
->sk
);
211 nexthop
= (__force u32
) rt_nexthop(rt
, ip_hdr(skb
)->daddr
);
212 neigh
= __ipv4_neigh_lookup_noref(dev
, nexthop
);
213 if (unlikely(!neigh
))
214 neigh
= __neigh_create(&arp_tbl
, &nexthop
, dev
, false);
215 if (!IS_ERR(neigh
)) {
216 int res
= dst_neigh_output(dst
, neigh
, skb
);
218 rcu_read_unlock_bh();
221 rcu_read_unlock_bh();
223 net_dbg_ratelimited("%s: No header cache and no neighbour!\n",
229 static int ip_finish_output_gso(struct net
*net
, struct sock
*sk
,
230 struct sk_buff
*skb
, unsigned int mtu
)
232 netdev_features_t features
;
233 struct sk_buff
*segs
;
236 /* common case: locally created skb or seglen is <= mtu */
237 if (((IPCB(skb
)->flags
& IPSKB_FORWARDED
) == 0) ||
238 skb_gso_network_seglen(skb
) <= mtu
)
239 return ip_finish_output2(net
, sk
, skb
);
241 /* Slowpath - GSO segment length is exceeding the dst MTU.
243 * This can happen in two cases:
244 * 1) TCP GRO packet, DF bit not set
245 * 2) skb arrived via virtio-net, we thus get TSO/GSO skbs directly
246 * from host network stack.
248 features
= netif_skb_features(skb
);
249 segs
= skb_gso_segment(skb
, features
& ~NETIF_F_GSO_MASK
);
250 if (IS_ERR_OR_NULL(segs
)) {
258 struct sk_buff
*nskb
= segs
->next
;
262 err
= ip_fragment(net
, sk
, segs
, mtu
, ip_finish_output2
);
272 static int ip_finish_output(struct net
*net
, struct sock
*sk
, struct sk_buff
*skb
)
276 #if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
277 /* Policy lookup after SNAT yielded a new policy */
278 if (skb_dst(skb
)->xfrm
) {
279 IPCB(skb
)->flags
|= IPSKB_REROUTED
;
280 return dst_output(net
, sk
, skb
);
283 mtu
= ip_skb_dst_mtu(skb
);
285 return ip_finish_output_gso(net
, sk
, skb
, mtu
);
287 if (skb
->len
> mtu
|| (IPCB(skb
)->flags
& IPSKB_FRAG_PMTU
))
288 return ip_fragment(net
, sk
, skb
, mtu
, ip_finish_output2
);
290 return ip_finish_output2(net
, sk
, skb
);
293 int ip_mc_output(struct sock
*sk
, struct sk_buff
*skb
)
295 struct rtable
*rt
= skb_rtable(skb
);
296 struct net_device
*dev
= rt
->dst
.dev
;
297 struct net
*net
= dev_net(dev
);
300 * If the indicated interface is up and running, send the packet.
302 IP_UPD_PO_STATS(net
, IPSTATS_MIB_OUT
, skb
->len
);
305 skb
->protocol
= htons(ETH_P_IP
);
308 * Multicasts are looped back for other local users
311 if (rt
->rt_flags
&RTCF_MULTICAST
) {
313 #ifdef CONFIG_IP_MROUTE
314 /* Small optimization: do not loopback not local frames,
315 which returned after forwarding; they will be dropped
316 by ip_mr_input in any case.
317 Note, that local frames are looped back to be delivered
320 This check is duplicated in ip_mr_input at the moment.
323 ((rt
->rt_flags
& RTCF_LOCAL
) ||
324 !(IPCB(skb
)->flags
& IPSKB_FORWARDED
))
327 struct sk_buff
*newskb
= skb_clone(skb
, GFP_ATOMIC
);
329 NF_HOOK(NFPROTO_IPV4
, NF_INET_POST_ROUTING
,
330 net
, sk
, newskb
, NULL
, newskb
->dev
,
334 /* Multicasts with ttl 0 must not go beyond the host */
336 if (ip_hdr(skb
)->ttl
== 0) {
342 if (rt
->rt_flags
&RTCF_BROADCAST
) {
343 struct sk_buff
*newskb
= skb_clone(skb
, GFP_ATOMIC
);
345 NF_HOOK(NFPROTO_IPV4
, NF_INET_POST_ROUTING
,
346 net
, sk
, newskb
, NULL
, newskb
->dev
,
350 return NF_HOOK_COND(NFPROTO_IPV4
, NF_INET_POST_ROUTING
,
351 net
, sk
, skb
, NULL
, skb
->dev
,
353 !(IPCB(skb
)->flags
& IPSKB_REROUTED
));
356 int ip_output(struct sock
*sk
, struct sk_buff
*skb
)
358 struct net_device
*dev
= skb_dst(skb
)->dev
;
359 struct net
*net
= dev_net(dev
);
361 IP_UPD_PO_STATS(net
, IPSTATS_MIB_OUT
, skb
->len
);
364 skb
->protocol
= htons(ETH_P_IP
);
366 return NF_HOOK_COND(NFPROTO_IPV4
, NF_INET_POST_ROUTING
,
367 net
, sk
, skb
, NULL
, dev
,
369 !(IPCB(skb
)->flags
& IPSKB_REROUTED
));
373 * copy saddr and daddr, possibly using 64bit load/stores
375 * iph->saddr = fl4->saddr;
376 * iph->daddr = fl4->daddr;
378 static void ip_copy_addrs(struct iphdr
*iph
, const struct flowi4
*fl4
)
380 BUILD_BUG_ON(offsetof(typeof(*fl4
), daddr
) !=
381 offsetof(typeof(*fl4
), saddr
) + sizeof(fl4
->saddr
));
382 memcpy(&iph
->saddr
, &fl4
->saddr
,
383 sizeof(fl4
->saddr
) + sizeof(fl4
->daddr
));
386 /* Note: skb->sk can be different from sk, in case of tunnels */
387 int ip_queue_xmit(struct sock
*sk
, struct sk_buff
*skb
, struct flowi
*fl
)
389 struct inet_sock
*inet
= inet_sk(sk
);
390 struct ip_options_rcu
*inet_opt
;
396 /* Skip all of this if the packet is already routed,
397 * f.e. by something like SCTP.
400 inet_opt
= rcu_dereference(inet
->inet_opt
);
402 rt
= skb_rtable(skb
);
406 /* Make sure we can route this packet. */
407 rt
= (struct rtable
*)__sk_dst_check(sk
, 0);
411 /* Use correct destination address if we have options. */
412 daddr
= inet
->inet_daddr
;
413 if (inet_opt
&& inet_opt
->opt
.srr
)
414 daddr
= inet_opt
->opt
.faddr
;
416 /* If this fails, retransmit mechanism of transport layer will
417 * keep trying until route appears or the connection times
420 rt
= ip_route_output_ports(sock_net(sk
), fl4
, sk
,
421 daddr
, inet
->inet_saddr
,
426 sk
->sk_bound_dev_if
);
429 sk_setup_caps(sk
, &rt
->dst
);
431 skb_dst_set_noref(skb
, &rt
->dst
);
434 if (inet_opt
&& inet_opt
->opt
.is_strictroute
&& rt
->rt_uses_gateway
)
437 /* OK, we know where to send it, allocate and build IP header. */
438 skb_push(skb
, sizeof(struct iphdr
) + (inet_opt
? inet_opt
->opt
.optlen
: 0));
439 skb_reset_network_header(skb
);
441 *((__be16
*)iph
) = htons((4 << 12) | (5 << 8) | (inet
->tos
& 0xff));
442 if (ip_dont_fragment(sk
, &rt
->dst
) && !skb
->ignore_df
)
443 iph
->frag_off
= htons(IP_DF
);
446 iph
->ttl
= ip_select_ttl(inet
, &rt
->dst
);
447 iph
->protocol
= sk
->sk_protocol
;
448 ip_copy_addrs(iph
, fl4
);
450 /* Transport layer set skb->h.foo itself. */
452 if (inet_opt
&& inet_opt
->opt
.optlen
) {
453 iph
->ihl
+= inet_opt
->opt
.optlen
>> 2;
454 ip_options_build(skb
, &inet_opt
->opt
, inet
->inet_daddr
, rt
, 0);
457 ip_select_ident_segs(sock_net(sk
), skb
, sk
,
458 skb_shinfo(skb
)->gso_segs
?: 1);
460 /* TODO : should we use skb->sk here instead of sk ? */
461 skb
->priority
= sk
->sk_priority
;
462 skb
->mark
= sk
->sk_mark
;
464 res
= ip_local_out_sk(sk
, skb
);
470 IP_INC_STATS(sock_net(sk
), IPSTATS_MIB_OUTNOROUTES
);
472 return -EHOSTUNREACH
;
474 EXPORT_SYMBOL(ip_queue_xmit
);
476 static void ip_copy_metadata(struct sk_buff
*to
, struct sk_buff
*from
)
478 to
->pkt_type
= from
->pkt_type
;
479 to
->priority
= from
->priority
;
480 to
->protocol
= from
->protocol
;
482 skb_dst_copy(to
, from
);
484 to
->mark
= from
->mark
;
486 /* Copy the flags to each fragment. */
487 IPCB(to
)->flags
= IPCB(from
)->flags
;
489 #ifdef CONFIG_NET_SCHED
490 to
->tc_index
= from
->tc_index
;
493 #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
494 to
->ipvs_property
= from
->ipvs_property
;
496 skb_copy_secmark(to
, from
);
499 static int ip_fragment(struct net
*net
, struct sock
*sk
, struct sk_buff
*skb
,
501 int (*output
)(struct net
*, struct sock
*, struct sk_buff
*))
503 struct iphdr
*iph
= ip_hdr(skb
);
505 if ((iph
->frag_off
& htons(IP_DF
)) == 0)
506 return ip_do_fragment(net
, sk
, skb
, output
);
508 if (unlikely(!skb
->ignore_df
||
509 (IPCB(skb
)->frag_max_size
&&
510 IPCB(skb
)->frag_max_size
> mtu
))) {
511 IP_INC_STATS(net
, IPSTATS_MIB_FRAGFAILS
);
512 icmp_send(skb
, ICMP_DEST_UNREACH
, ICMP_FRAG_NEEDED
,
518 return ip_do_fragment(net
, sk
, skb
, output
);
522 * This IP datagram is too large to be sent in one piece. Break it up into
523 * smaller pieces (each of size equal to IP header plus
524 * a block of the data of the original IP data part) that will yet fit in a
525 * single device frame, and queue such a frame for sending.
528 int ip_do_fragment(struct net
*net
, struct sock
*sk
, struct sk_buff
*skb
,
529 int (*output
)(struct net
*, struct sock
*, struct sk_buff
*))
533 struct net_device
*dev
;
534 struct sk_buff
*skb2
;
535 unsigned int mtu
, hlen
, left
, len
, ll_rs
;
537 __be16 not_last_frag
;
538 struct rtable
*rt
= skb_rtable(skb
);
544 * Point into the IP datagram header.
549 mtu
= ip_skb_dst_mtu(skb
);
550 if (IPCB(skb
)->frag_max_size
&& IPCB(skb
)->frag_max_size
< mtu
)
551 mtu
= IPCB(skb
)->frag_max_size
;
554 * Setup starting values.
558 mtu
= mtu
- hlen
; /* Size of data space */
559 IPCB(skb
)->flags
|= IPSKB_FRAG_COMPLETE
;
561 /* When frag_list is given, use it. First, check its validity:
562 * some transformers could create wrong frag_list or break existing
563 * one, it is not prohibited. In this case fall back to copying.
565 * LATER: this step can be merged to real generation of fragments,
566 * we can switch to copy when see the first bad fragment.
568 if (skb_has_frag_list(skb
)) {
569 struct sk_buff
*frag
, *frag2
;
570 int first_len
= skb_pagelen(skb
);
572 if (first_len
- hlen
> mtu
||
573 ((first_len
- hlen
) & 7) ||
574 ip_is_fragment(iph
) ||
578 skb_walk_frags(skb
, frag
) {
579 /* Correct geometry. */
580 if (frag
->len
> mtu
||
581 ((frag
->len
& 7) && frag
->next
) ||
582 skb_headroom(frag
) < hlen
)
583 goto slow_path_clean
;
585 /* Partially cloned skb? */
586 if (skb_shared(frag
))
587 goto slow_path_clean
;
592 frag
->destructor
= sock_wfree
;
594 skb
->truesize
-= frag
->truesize
;
597 /* Everything is OK. Generate! */
601 frag
= skb_shinfo(skb
)->frag_list
;
602 skb_frag_list_init(skb
);
603 skb
->data_len
= first_len
- skb_headlen(skb
);
604 skb
->len
= first_len
;
605 iph
->tot_len
= htons(first_len
);
606 iph
->frag_off
= htons(IP_MF
);
610 /* Prepare header of the next frame,
611 * before previous one went down. */
613 frag
->ip_summed
= CHECKSUM_NONE
;
614 skb_reset_transport_header(frag
);
615 __skb_push(frag
, hlen
);
616 skb_reset_network_header(frag
);
617 memcpy(skb_network_header(frag
), iph
, hlen
);
619 iph
->tot_len
= htons(frag
->len
);
620 ip_copy_metadata(frag
, skb
);
622 ip_options_fragment(frag
);
623 offset
+= skb
->len
- hlen
;
624 iph
->frag_off
= htons(offset
>>3);
626 iph
->frag_off
|= htons(IP_MF
);
627 /* Ready, complete checksum */
631 err
= output(net
, sk
, skb
);
634 IP_INC_STATS(net
, IPSTATS_MIB_FRAGCREATES
);
644 IP_INC_STATS(net
, IPSTATS_MIB_FRAGOKS
);
653 IP_INC_STATS(net
, IPSTATS_MIB_FRAGFAILS
);
657 skb_walk_frags(skb
, frag2
) {
661 frag2
->destructor
= NULL
;
662 skb
->truesize
+= frag2
->truesize
;
667 /* for offloaded checksums cleanup checksum before fragmentation */
668 if ((skb
->ip_summed
== CHECKSUM_PARTIAL
) && skb_checksum_help(skb
))
672 left
= skb
->len
- hlen
; /* Space per frame */
673 ptr
= hlen
; /* Where to start from */
675 ll_rs
= LL_RESERVED_SPACE(rt
->dst
.dev
);
678 * Fragment the datagram.
681 offset
= (ntohs(iph
->frag_off
) & IP_OFFSET
) << 3;
682 not_last_frag
= iph
->frag_off
& htons(IP_MF
);
685 * Keep copying data until we run out.
690 /* IF: it doesn't fit, use 'mtu' - the data space left */
693 /* IF: we are not sending up to and including the packet end
694 then align the next start on an eight byte boundary */
699 /* Allocate buffer */
700 skb2
= alloc_skb(len
+ hlen
+ ll_rs
, GFP_ATOMIC
);
707 * Set up data on packet
710 ip_copy_metadata(skb2
, skb
);
711 skb_reserve(skb2
, ll_rs
);
712 skb_put(skb2
, len
+ hlen
);
713 skb_reset_network_header(skb2
);
714 skb2
->transport_header
= skb2
->network_header
+ hlen
;
717 * Charge the memory for the fragment to any owner
722 skb_set_owner_w(skb2
, skb
->sk
);
725 * Copy the packet header into the new buffer.
728 skb_copy_from_linear_data(skb
, skb_network_header(skb2
), hlen
);
731 * Copy a block of the IP datagram.
733 if (skb_copy_bits(skb
, ptr
, skb_transport_header(skb2
), len
))
738 * Fill in the new header fields.
741 iph
->frag_off
= htons((offset
>> 3));
743 if (IPCB(skb
)->flags
& IPSKB_FRAG_PMTU
)
744 iph
->frag_off
|= htons(IP_DF
);
746 /* ANK: dirty, but effective trick. Upgrade options only if
747 * the segment to be fragmented was THE FIRST (otherwise,
748 * options are already fixed) and make it ONCE
749 * on the initial skb, so that all the following fragments
750 * will inherit fixed options.
753 ip_options_fragment(skb
);
756 * Added AC : If we are fragmenting a fragment that's not the
757 * last fragment then keep MF on each bit
759 if (left
> 0 || not_last_frag
)
760 iph
->frag_off
|= htons(IP_MF
);
765 * Put this fragment into the sending queue.
767 iph
->tot_len
= htons(len
+ hlen
);
771 err
= output(net
, sk
, skb2
);
775 IP_INC_STATS(net
, IPSTATS_MIB_FRAGCREATES
);
778 IP_INC_STATS(net
, IPSTATS_MIB_FRAGOKS
);
783 IP_INC_STATS(net
, IPSTATS_MIB_FRAGFAILS
);
786 EXPORT_SYMBOL(ip_do_fragment
);
789 ip_generic_getfrag(void *from
, char *to
, int offset
, int len
, int odd
, struct sk_buff
*skb
)
791 struct msghdr
*msg
= from
;
793 if (skb
->ip_summed
== CHECKSUM_PARTIAL
) {
794 if (copy_from_iter(to
, len
, &msg
->msg_iter
) != len
)
798 if (csum_and_copy_from_iter(to
, len
, &csum
, &msg
->msg_iter
) != len
)
800 skb
->csum
= csum_block_add(skb
->csum
, csum
, odd
);
804 EXPORT_SYMBOL(ip_generic_getfrag
);
807 csum_page(struct page
*page
, int offset
, int copy
)
812 csum
= csum_partial(kaddr
+ offset
, copy
, 0);
817 static inline int ip_ufo_append_data(struct sock
*sk
,
818 struct sk_buff_head
*queue
,
819 int getfrag(void *from
, char *to
, int offset
, int len
,
820 int odd
, struct sk_buff
*skb
),
821 void *from
, int length
, int hh_len
, int fragheaderlen
,
822 int transhdrlen
, int maxfraglen
, unsigned int flags
)
827 /* There is support for UDP fragmentation offload by network
828 * device, so create one single skb packet containing complete
831 skb
= skb_peek_tail(queue
);
833 skb
= sock_alloc_send_skb(sk
,
834 hh_len
+ fragheaderlen
+ transhdrlen
+ 20,
835 (flags
& MSG_DONTWAIT
), &err
);
840 /* reserve space for Hardware header */
841 skb_reserve(skb
, hh_len
);
843 /* create space for UDP/IP header */
844 skb_put(skb
, fragheaderlen
+ transhdrlen
);
846 /* initialize network header pointer */
847 skb_reset_network_header(skb
);
849 /* initialize protocol header pointer */
850 skb
->transport_header
= skb
->network_header
+ fragheaderlen
;
854 __skb_queue_tail(queue
, skb
);
855 } else if (skb_is_gso(skb
)) {
859 skb
->ip_summed
= CHECKSUM_PARTIAL
;
860 /* specify the length of each IP datagram fragment */
861 skb_shinfo(skb
)->gso_size
= maxfraglen
- fragheaderlen
;
862 skb_shinfo(skb
)->gso_type
= SKB_GSO_UDP
;
865 return skb_append_datato_frags(sk
, skb
, getfrag
, from
,
866 (length
- transhdrlen
));
869 static int __ip_append_data(struct sock
*sk
,
871 struct sk_buff_head
*queue
,
872 struct inet_cork
*cork
,
873 struct page_frag
*pfrag
,
874 int getfrag(void *from
, char *to
, int offset
,
875 int len
, int odd
, struct sk_buff
*skb
),
876 void *from
, int length
, int transhdrlen
,
879 struct inet_sock
*inet
= inet_sk(sk
);
882 struct ip_options
*opt
= cork
->opt
;
889 unsigned int maxfraglen
, fragheaderlen
, maxnonfragsize
;
890 int csummode
= CHECKSUM_NONE
;
891 struct rtable
*rt
= (struct rtable
*)cork
->dst
;
894 skb
= skb_peek_tail(queue
);
896 exthdrlen
= !skb
? rt
->dst
.header_len
: 0;
897 mtu
= cork
->fragsize
;
898 if (cork
->tx_flags
& SKBTX_ANY_SW_TSTAMP
&&
899 sk
->sk_tsflags
& SOF_TIMESTAMPING_OPT_ID
)
900 tskey
= sk
->sk_tskey
++;
902 hh_len
= LL_RESERVED_SPACE(rt
->dst
.dev
);
904 fragheaderlen
= sizeof(struct iphdr
) + (opt
? opt
->optlen
: 0);
905 maxfraglen
= ((mtu
- fragheaderlen
) & ~7) + fragheaderlen
;
906 maxnonfragsize
= ip_sk_ignore_df(sk
) ? 0xFFFF : mtu
;
908 if (cork
->length
+ length
> maxnonfragsize
- fragheaderlen
) {
909 ip_local_error(sk
, EMSGSIZE
, fl4
->daddr
, inet
->inet_dport
,
910 mtu
- (opt
? opt
->optlen
: 0));
915 * transhdrlen > 0 means that this is the first fragment and we wish
916 * it won't be fragmented in the future.
919 length
+ fragheaderlen
<= mtu
&&
920 rt
->dst
.dev
->features
& NETIF_F_V4_CSUM
&&
922 csummode
= CHECKSUM_PARTIAL
;
924 cork
->length
+= length
;
925 if (((length
> mtu
) || (skb
&& skb_is_gso(skb
))) &&
926 (sk
->sk_protocol
== IPPROTO_UDP
) &&
927 (rt
->dst
.dev
->features
& NETIF_F_UFO
) && !rt
->dst
.header_len
&&
928 (sk
->sk_type
== SOCK_DGRAM
)) {
929 err
= ip_ufo_append_data(sk
, queue
, getfrag
, from
, length
,
930 hh_len
, fragheaderlen
, transhdrlen
,
937 /* So, what's going on in the loop below?
939 * We use calculated fragment length to generate chained skb,
940 * each of segments is IP fragment ready for sending to network after
941 * adding appropriate IP header.
948 /* Check if the remaining data fits into current packet. */
949 copy
= mtu
- skb
->len
;
951 copy
= maxfraglen
- skb
->len
;
954 unsigned int datalen
;
955 unsigned int fraglen
;
956 unsigned int fraggap
;
957 unsigned int alloclen
;
958 struct sk_buff
*skb_prev
;
962 fraggap
= skb_prev
->len
- maxfraglen
;
967 * If remaining data exceeds the mtu,
968 * we know we need more fragment(s).
970 datalen
= length
+ fraggap
;
971 if (datalen
> mtu
- fragheaderlen
)
972 datalen
= maxfraglen
- fragheaderlen
;
973 fraglen
= datalen
+ fragheaderlen
;
975 if ((flags
& MSG_MORE
) &&
976 !(rt
->dst
.dev
->features
&NETIF_F_SG
))
981 alloclen
+= exthdrlen
;
983 /* The last fragment gets additional space at tail.
984 * Note, with MSG_MORE we overallocate on fragments,
985 * because we have no idea what fragment will be
988 if (datalen
== length
+ fraggap
)
989 alloclen
+= rt
->dst
.trailer_len
;
992 skb
= sock_alloc_send_skb(sk
,
993 alloclen
+ hh_len
+ 15,
994 (flags
& MSG_DONTWAIT
), &err
);
997 if (atomic_read(&sk
->sk_wmem_alloc
) <=
999 skb
= sock_wmalloc(sk
,
1000 alloclen
+ hh_len
+ 15, 1,
1009 * Fill in the control structures
1011 skb
->ip_summed
= csummode
;
1013 skb_reserve(skb
, hh_len
);
1015 /* only the initial fragment is time stamped */
1016 skb_shinfo(skb
)->tx_flags
= cork
->tx_flags
;
1018 skb_shinfo(skb
)->tskey
= tskey
;
1022 * Find where to start putting bytes.
1024 data
= skb_put(skb
, fraglen
+ exthdrlen
);
1025 skb_set_network_header(skb
, exthdrlen
);
1026 skb
->transport_header
= (skb
->network_header
+
1028 data
+= fragheaderlen
+ exthdrlen
;
1031 skb
->csum
= skb_copy_and_csum_bits(
1032 skb_prev
, maxfraglen
,
1033 data
+ transhdrlen
, fraggap
, 0);
1034 skb_prev
->csum
= csum_sub(skb_prev
->csum
,
1037 pskb_trim_unique(skb_prev
, maxfraglen
);
1040 copy
= datalen
- transhdrlen
- fraggap
;
1041 if (copy
> 0 && getfrag(from
, data
+ transhdrlen
, offset
, copy
, fraggap
, skb
) < 0) {
1048 length
-= datalen
- fraggap
;
1051 csummode
= CHECKSUM_NONE
;
1054 * Put the packet on the pending queue.
1056 __skb_queue_tail(queue
, skb
);
1063 if (!(rt
->dst
.dev
->features
&NETIF_F_SG
)) {
1067 if (getfrag(from
, skb_put(skb
, copy
),
1068 offset
, copy
, off
, skb
) < 0) {
1069 __skb_trim(skb
, off
);
1074 int i
= skb_shinfo(skb
)->nr_frags
;
1077 if (!sk_page_frag_refill(sk
, pfrag
))
1080 if (!skb_can_coalesce(skb
, i
, pfrag
->page
,
1083 if (i
== MAX_SKB_FRAGS
)
1086 __skb_fill_page_desc(skb
, i
, pfrag
->page
,
1088 skb_shinfo(skb
)->nr_frags
= ++i
;
1089 get_page(pfrag
->page
);
1091 copy
= min_t(int, copy
, pfrag
->size
- pfrag
->offset
);
1093 page_address(pfrag
->page
) + pfrag
->offset
,
1094 offset
, copy
, skb
->len
, skb
) < 0)
1097 pfrag
->offset
+= copy
;
1098 skb_frag_size_add(&skb_shinfo(skb
)->frags
[i
- 1], copy
);
1100 skb
->data_len
+= copy
;
1101 skb
->truesize
+= copy
;
1102 atomic_add(copy
, &sk
->sk_wmem_alloc
);
1113 cork
->length
-= length
;
1114 IP_INC_STATS(sock_net(sk
), IPSTATS_MIB_OUTDISCARDS
);
1118 static int ip_setup_cork(struct sock
*sk
, struct inet_cork
*cork
,
1119 struct ipcm_cookie
*ipc
, struct rtable
**rtp
)
1121 struct ip_options_rcu
*opt
;
1125 * setup for corking.
1130 cork
->opt
= kmalloc(sizeof(struct ip_options
) + 40,
1132 if (unlikely(!cork
->opt
))
1135 memcpy(cork
->opt
, &opt
->opt
, sizeof(struct ip_options
) + opt
->opt
.optlen
);
1136 cork
->flags
|= IPCORK_OPT
;
1137 cork
->addr
= ipc
->addr
;
1143 * We steal reference to this route, caller should not release it
1146 cork
->fragsize
= ip_sk_use_pmtu(sk
) ?
1147 dst_mtu(&rt
->dst
) : rt
->dst
.dev
->mtu
;
1148 cork
->dst
= &rt
->dst
;
1150 cork
->ttl
= ipc
->ttl
;
1151 cork
->tos
= ipc
->tos
;
1152 cork
->priority
= ipc
->priority
;
1153 cork
->tx_flags
= ipc
->tx_flags
;
1159 * ip_append_data() and ip_append_page() can make one large IP datagram
1160 * from many pieces of data. Each pieces will be holded on the socket
1161 * until ip_push_pending_frames() is called. Each piece can be a page
1164 * Not only UDP, other transport protocols - e.g. raw sockets - can use
1165 * this interface potentially.
1167 * LATER: length must be adjusted by pad at tail, when it is required.
1169 int ip_append_data(struct sock
*sk
, struct flowi4
*fl4
,
1170 int getfrag(void *from
, char *to
, int offset
, int len
,
1171 int odd
, struct sk_buff
*skb
),
1172 void *from
, int length
, int transhdrlen
,
1173 struct ipcm_cookie
*ipc
, struct rtable
**rtp
,
1176 struct inet_sock
*inet
= inet_sk(sk
);
1179 if (flags
&MSG_PROBE
)
1182 if (skb_queue_empty(&sk
->sk_write_queue
)) {
1183 err
= ip_setup_cork(sk
, &inet
->cork
.base
, ipc
, rtp
);
1190 return __ip_append_data(sk
, fl4
, &sk
->sk_write_queue
, &inet
->cork
.base
,
1191 sk_page_frag(sk
), getfrag
,
1192 from
, length
, transhdrlen
, flags
);
1195 ssize_t
ip_append_page(struct sock
*sk
, struct flowi4
*fl4
, struct page
*page
,
1196 int offset
, size_t size
, int flags
)
1198 struct inet_sock
*inet
= inet_sk(sk
);
1199 struct sk_buff
*skb
;
1201 struct ip_options
*opt
= NULL
;
1202 struct inet_cork
*cork
;
1207 unsigned int maxfraglen
, fragheaderlen
, fraggap
, maxnonfragsize
;
1212 if (flags
&MSG_PROBE
)
1215 if (skb_queue_empty(&sk
->sk_write_queue
))
1218 cork
= &inet
->cork
.base
;
1219 rt
= (struct rtable
*)cork
->dst
;
1220 if (cork
->flags
& IPCORK_OPT
)
1223 if (!(rt
->dst
.dev
->features
&NETIF_F_SG
))
1226 hh_len
= LL_RESERVED_SPACE(rt
->dst
.dev
);
1227 mtu
= cork
->fragsize
;
1229 fragheaderlen
= sizeof(struct iphdr
) + (opt
? opt
->optlen
: 0);
1230 maxfraglen
= ((mtu
- fragheaderlen
) & ~7) + fragheaderlen
;
1231 maxnonfragsize
= ip_sk_ignore_df(sk
) ? 0xFFFF : mtu
;
1233 if (cork
->length
+ size
> maxnonfragsize
- fragheaderlen
) {
1234 ip_local_error(sk
, EMSGSIZE
, fl4
->daddr
, inet
->inet_dport
,
1235 mtu
- (opt
? opt
->optlen
: 0));
1239 skb
= skb_peek_tail(&sk
->sk_write_queue
);
1243 cork
->length
+= size
;
1244 if ((size
+ skb
->len
> mtu
) &&
1245 (sk
->sk_protocol
== IPPROTO_UDP
) &&
1246 (rt
->dst
.dev
->features
& NETIF_F_UFO
)) {
1247 skb_shinfo(skb
)->gso_size
= mtu
- fragheaderlen
;
1248 skb_shinfo(skb
)->gso_type
= SKB_GSO_UDP
;
1252 if (skb_is_gso(skb
)) {
1256 /* Check if the remaining data fits into current packet. */
1257 len
= mtu
- skb
->len
;
1259 len
= maxfraglen
- skb
->len
;
1262 struct sk_buff
*skb_prev
;
1266 fraggap
= skb_prev
->len
- maxfraglen
;
1268 alloclen
= fragheaderlen
+ hh_len
+ fraggap
+ 15;
1269 skb
= sock_wmalloc(sk
, alloclen
, 1, sk
->sk_allocation
);
1270 if (unlikely(!skb
)) {
1276 * Fill in the control structures
1278 skb
->ip_summed
= CHECKSUM_NONE
;
1280 skb_reserve(skb
, hh_len
);
1283 * Find where to start putting bytes.
1285 skb_put(skb
, fragheaderlen
+ fraggap
);
1286 skb_reset_network_header(skb
);
1287 skb
->transport_header
= (skb
->network_header
+
1290 skb
->csum
= skb_copy_and_csum_bits(skb_prev
,
1292 skb_transport_header(skb
),
1294 skb_prev
->csum
= csum_sub(skb_prev
->csum
,
1296 pskb_trim_unique(skb_prev
, maxfraglen
);
1300 * Put the packet on the pending queue.
1302 __skb_queue_tail(&sk
->sk_write_queue
, skb
);
1309 if (skb_append_pagefrags(skb
, page
, offset
, len
)) {
1314 if (skb
->ip_summed
== CHECKSUM_NONE
) {
1316 csum
= csum_page(page
, offset
, len
);
1317 skb
->csum
= csum_block_add(skb
->csum
, csum
, skb
->len
);
1321 skb
->data_len
+= len
;
1322 skb
->truesize
+= len
;
1323 atomic_add(len
, &sk
->sk_wmem_alloc
);
1330 cork
->length
-= size
;
1331 IP_INC_STATS(sock_net(sk
), IPSTATS_MIB_OUTDISCARDS
);
1335 static void ip_cork_release(struct inet_cork
*cork
)
1337 cork
->flags
&= ~IPCORK_OPT
;
1340 dst_release(cork
->dst
);
1345 * Combined all pending IP fragments on the socket as one IP datagram
1346 * and push them out.
1348 struct sk_buff
*__ip_make_skb(struct sock
*sk
,
1350 struct sk_buff_head
*queue
,
1351 struct inet_cork
*cork
)
1353 struct sk_buff
*skb
, *tmp_skb
;
1354 struct sk_buff
**tail_skb
;
1355 struct inet_sock
*inet
= inet_sk(sk
);
1356 struct net
*net
= sock_net(sk
);
1357 struct ip_options
*opt
= NULL
;
1358 struct rtable
*rt
= (struct rtable
*)cork
->dst
;
1363 skb
= __skb_dequeue(queue
);
1366 tail_skb
= &(skb_shinfo(skb
)->frag_list
);
1368 /* move skb->data to ip header from ext header */
1369 if (skb
->data
< skb_network_header(skb
))
1370 __skb_pull(skb
, skb_network_offset(skb
));
1371 while ((tmp_skb
= __skb_dequeue(queue
)) != NULL
) {
1372 __skb_pull(tmp_skb
, skb_network_header_len(skb
));
1373 *tail_skb
= tmp_skb
;
1374 tail_skb
= &(tmp_skb
->next
);
1375 skb
->len
+= tmp_skb
->len
;
1376 skb
->data_len
+= tmp_skb
->len
;
1377 skb
->truesize
+= tmp_skb
->truesize
;
1378 tmp_skb
->destructor
= NULL
;
1382 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow
1383 * to fragment the frame generated here. No matter, what transforms
1384 * how transforms change size of the packet, it will come out.
1386 skb
->ignore_df
= ip_sk_ignore_df(sk
);
1388 /* DF bit is set when we want to see DF on outgoing frames.
1389 * If ignore_df is set too, we still allow to fragment this frame
1391 if (inet
->pmtudisc
== IP_PMTUDISC_DO
||
1392 inet
->pmtudisc
== IP_PMTUDISC_PROBE
||
1393 (skb
->len
<= dst_mtu(&rt
->dst
) &&
1394 ip_dont_fragment(sk
, &rt
->dst
)))
1397 if (cork
->flags
& IPCORK_OPT
)
1402 else if (rt
->rt_type
== RTN_MULTICAST
)
1405 ttl
= ip_select_ttl(inet
, &rt
->dst
);
1410 iph
->tos
= (cork
->tos
!= -1) ? cork
->tos
: inet
->tos
;
1413 iph
->protocol
= sk
->sk_protocol
;
1414 ip_copy_addrs(iph
, fl4
);
1415 ip_select_ident(net
, skb
, sk
);
1418 iph
->ihl
+= opt
->optlen
>>2;
1419 ip_options_build(skb
, opt
, cork
->addr
, rt
, 0);
1422 skb
->priority
= (cork
->tos
!= -1) ? cork
->priority
: sk
->sk_priority
;
1423 skb
->mark
= sk
->sk_mark
;
1425 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec
1429 skb_dst_set(skb
, &rt
->dst
);
1431 if (iph
->protocol
== IPPROTO_ICMP
)
1432 icmp_out_count(net
, ((struct icmphdr
*)
1433 skb_transport_header(skb
))->type
);
1435 ip_cork_release(cork
);
1440 int ip_send_skb(struct net
*net
, struct sk_buff
*skb
)
1444 err
= ip_local_out(skb
);
1447 err
= net_xmit_errno(err
);
1449 IP_INC_STATS(net
, IPSTATS_MIB_OUTDISCARDS
);
1455 int ip_push_pending_frames(struct sock
*sk
, struct flowi4
*fl4
)
1457 struct sk_buff
*skb
;
1459 skb
= ip_finish_skb(sk
, fl4
);
1463 /* Netfilter gets whole the not fragmented skb. */
1464 return ip_send_skb(sock_net(sk
), skb
);
1468 * Throw away all pending data on the socket.
1470 static void __ip_flush_pending_frames(struct sock
*sk
,
1471 struct sk_buff_head
*queue
,
1472 struct inet_cork
*cork
)
1474 struct sk_buff
*skb
;
1476 while ((skb
= __skb_dequeue_tail(queue
)) != NULL
)
1479 ip_cork_release(cork
);
1482 void ip_flush_pending_frames(struct sock
*sk
)
1484 __ip_flush_pending_frames(sk
, &sk
->sk_write_queue
, &inet_sk(sk
)->cork
.base
);
1487 struct sk_buff
*ip_make_skb(struct sock
*sk
,
1489 int getfrag(void *from
, char *to
, int offset
,
1490 int len
, int odd
, struct sk_buff
*skb
),
1491 void *from
, int length
, int transhdrlen
,
1492 struct ipcm_cookie
*ipc
, struct rtable
**rtp
,
1495 struct inet_cork cork
;
1496 struct sk_buff_head queue
;
1499 if (flags
& MSG_PROBE
)
1502 __skb_queue_head_init(&queue
);
1507 err
= ip_setup_cork(sk
, &cork
, ipc
, rtp
);
1509 return ERR_PTR(err
);
1511 err
= __ip_append_data(sk
, fl4
, &queue
, &cork
,
1512 ¤t
->task_frag
, getfrag
,
1513 from
, length
, transhdrlen
, flags
);
1515 __ip_flush_pending_frames(sk
, &queue
, &cork
);
1516 return ERR_PTR(err
);
1519 return __ip_make_skb(sk
, fl4
, &queue
, &cork
);
1523 * Fetch data from kernel space and fill in checksum if needed.
1525 static int ip_reply_glue_bits(void *dptr
, char *to
, int offset
,
1526 int len
, int odd
, struct sk_buff
*skb
)
1530 csum
= csum_partial_copy_nocheck(dptr
+offset
, to
, len
, 0);
1531 skb
->csum
= csum_block_add(skb
->csum
, csum
, odd
);
1536 * Generic function to send a packet as reply to another packet.
1537 * Used to send some TCP resets/acks so far.
1539 void ip_send_unicast_reply(struct sock
*sk
, struct sk_buff
*skb
,
1540 const struct ip_options
*sopt
,
1541 __be32 daddr
, __be32 saddr
,
1542 const struct ip_reply_arg
*arg
,
1545 struct ip_options_data replyopts
;
1546 struct ipcm_cookie ipc
;
1548 struct rtable
*rt
= skb_rtable(skb
);
1549 struct net
*net
= sock_net(sk
);
1550 struct sk_buff
*nskb
;
1554 if (__ip_options_echo(&replyopts
.opt
.opt
, skb
, sopt
))
1563 if (replyopts
.opt
.opt
.optlen
) {
1564 ipc
.opt
= &replyopts
.opt
;
1566 if (replyopts
.opt
.opt
.srr
)
1567 daddr
= replyopts
.opt
.opt
.faddr
;
1570 oif
= arg
->bound_dev_if
;
1571 if (!oif
&& netif_index_is_l3_master(net
, skb
->skb_iif
))
1574 flowi4_init_output(&fl4
, oif
,
1575 IP4_REPLY_MARK(net
, skb
->mark
),
1577 RT_SCOPE_UNIVERSE
, ip_hdr(skb
)->protocol
,
1578 ip_reply_arg_flowi_flags(arg
),
1580 tcp_hdr(skb
)->source
, tcp_hdr(skb
)->dest
);
1581 security_skb_classify_flow(skb
, flowi4_to_flowi(&fl4
));
1582 rt
= ip_route_output_key(net
, &fl4
);
1586 inet_sk(sk
)->tos
= arg
->tos
;
1588 sk
->sk_priority
= skb
->priority
;
1589 sk
->sk_protocol
= ip_hdr(skb
)->protocol
;
1590 sk
->sk_bound_dev_if
= arg
->bound_dev_if
;
1591 sk
->sk_sndbuf
= sysctl_wmem_default
;
1592 err
= ip_append_data(sk
, &fl4
, ip_reply_glue_bits
, arg
->iov
->iov_base
,
1593 len
, 0, &ipc
, &rt
, MSG_DONTWAIT
);
1594 if (unlikely(err
)) {
1595 ip_flush_pending_frames(sk
);
1599 nskb
= skb_peek(&sk
->sk_write_queue
);
1601 if (arg
->csumoffset
>= 0)
1602 *((__sum16
*)skb_transport_header(nskb
) +
1603 arg
->csumoffset
) = csum_fold(csum_add(nskb
->csum
,
1605 nskb
->ip_summed
= CHECKSUM_NONE
;
1606 skb_set_queue_mapping(nskb
, skb_get_queue_mapping(skb
));
1607 ip_push_pending_frames(sk
, &fl4
);
1613 void __init
ip_init(void)
1618 #if defined(CONFIG_IP_MULTICAST)