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 <net/lwtunnel.h>
77 #include <linux/igmp.h>
78 #include <linux/netfilter_ipv4.h>
79 #include <linux/netfilter_bridge.h>
80 #include <linux/netlink.h>
81 #include <linux/tcp.h>
84 ip_fragment(struct net
*net
, struct sock
*sk
, struct sk_buff
*skb
,
86 int (*output
)(struct net
*, struct sock
*, struct sk_buff
*));
88 /* Generate a checksum for an outgoing IP datagram. */
89 void ip_send_check(struct iphdr
*iph
)
92 iph
->check
= ip_fast_csum((unsigned char *)iph
, iph
->ihl
);
94 EXPORT_SYMBOL(ip_send_check
);
96 int __ip_local_out(struct net
*net
, struct sock
*sk
, struct sk_buff
*skb
)
98 struct iphdr
*iph
= ip_hdr(skb
);
100 iph
->tot_len
= htons(skb
->len
);
103 /* if egress device is enslaved to an L3 master device pass the
104 * skb to its handler for processing
106 skb
= l3mdev_ip_out(sk
, skb
);
110 return nf_hook(NFPROTO_IPV4
, NF_INET_LOCAL_OUT
,
111 net
, sk
, skb
, NULL
, skb_dst(skb
)->dev
,
115 int ip_local_out(struct net
*net
, struct sock
*sk
, struct sk_buff
*skb
)
119 err
= __ip_local_out(net
, sk
, skb
);
120 if (likely(err
== 1))
121 err
= dst_output(net
, sk
, skb
);
125 EXPORT_SYMBOL_GPL(ip_local_out
);
127 static inline int ip_select_ttl(struct inet_sock
*inet
, struct dst_entry
*dst
)
129 int ttl
= inet
->uc_ttl
;
132 ttl
= ip4_dst_hoplimit(dst
);
137 * Add an ip header to a skbuff and send it out.
140 int ip_build_and_send_pkt(struct sk_buff
*skb
, const struct sock
*sk
,
141 __be32 saddr
, __be32 daddr
, struct ip_options_rcu
*opt
)
143 struct inet_sock
*inet
= inet_sk(sk
);
144 struct rtable
*rt
= skb_rtable(skb
);
145 struct net
*net
= sock_net(sk
);
148 /* Build the IP header. */
149 skb_push(skb
, sizeof(struct iphdr
) + (opt
? opt
->opt
.optlen
: 0));
150 skb_reset_network_header(skb
);
154 iph
->tos
= inet
->tos
;
155 iph
->ttl
= ip_select_ttl(inet
, &rt
->dst
);
156 iph
->daddr
= (opt
&& opt
->opt
.srr
? opt
->opt
.faddr
: daddr
);
158 iph
->protocol
= sk
->sk_protocol
;
159 if (ip_dont_fragment(sk
, &rt
->dst
)) {
160 iph
->frag_off
= htons(IP_DF
);
164 __ip_select_ident(net
, iph
, 1);
167 if (opt
&& opt
->opt
.optlen
) {
168 iph
->ihl
+= opt
->opt
.optlen
>>2;
169 ip_options_build(skb
, &opt
->opt
, daddr
, rt
, 0);
172 skb
->priority
= sk
->sk_priority
;
173 skb
->mark
= sk
->sk_mark
;
176 return ip_local_out(net
, skb
->sk
, skb
);
178 EXPORT_SYMBOL_GPL(ip_build_and_send_pkt
);
180 static int ip_finish_output2(struct net
*net
, struct sock
*sk
, struct sk_buff
*skb
)
182 struct dst_entry
*dst
= skb_dst(skb
);
183 struct rtable
*rt
= (struct rtable
*)dst
;
184 struct net_device
*dev
= dst
->dev
;
185 unsigned int hh_len
= LL_RESERVED_SPACE(dev
);
186 struct neighbour
*neigh
;
189 if (rt
->rt_type
== RTN_MULTICAST
) {
190 IP_UPD_PO_STATS(net
, IPSTATS_MIB_OUTMCAST
, skb
->len
);
191 } else if (rt
->rt_type
== RTN_BROADCAST
)
192 IP_UPD_PO_STATS(net
, IPSTATS_MIB_OUTBCAST
, skb
->len
);
194 /* Be paranoid, rather than too clever. */
195 if (unlikely(skb_headroom(skb
) < hh_len
&& dev
->header_ops
)) {
196 struct sk_buff
*skb2
;
198 skb2
= skb_realloc_headroom(skb
, LL_RESERVED_SPACE(dev
));
204 skb_set_owner_w(skb2
, skb
->sk
);
209 if (lwtunnel_xmit_redirect(dst
->lwtstate
)) {
210 int res
= lwtunnel_xmit(skb
);
212 if (res
< 0 || res
== LWTUNNEL_XMIT_DONE
)
217 nexthop
= (__force u32
) rt_nexthop(rt
, ip_hdr(skb
)->daddr
);
218 neigh
= __ipv4_neigh_lookup_noref(dev
, nexthop
);
219 if (unlikely(!neigh
))
220 neigh
= __neigh_create(&arp_tbl
, &nexthop
, dev
, false);
221 if (!IS_ERR(neigh
)) {
222 int res
= dst_neigh_output(dst
, neigh
, skb
);
224 rcu_read_unlock_bh();
227 rcu_read_unlock_bh();
229 net_dbg_ratelimited("%s: No header cache and no neighbour!\n",
235 static int ip_finish_output_gso(struct net
*net
, struct sock
*sk
,
236 struct sk_buff
*skb
, unsigned int mtu
)
238 netdev_features_t features
;
239 struct sk_buff
*segs
;
242 /* common case: fragmentation of segments is not allowed,
243 * or seglen is <= mtu
245 if (((IPCB(skb
)->flags
& IPSKB_FRAG_SEGS
) == 0) ||
246 skb_gso_validate_mtu(skb
, mtu
))
247 return ip_finish_output2(net
, sk
, skb
);
249 /* Slowpath - GSO segment length is exceeding the dst MTU.
251 * This can happen in two cases:
252 * 1) TCP GRO packet, DF bit not set
253 * 2) skb arrived via virtio-net, we thus get TSO/GSO skbs directly
254 * from host network stack.
256 features
= netif_skb_features(skb
);
257 BUILD_BUG_ON(sizeof(*IPCB(skb
)) > SKB_SGO_CB_OFFSET
);
258 segs
= skb_gso_segment(skb
, features
& ~NETIF_F_GSO_MASK
);
259 if (IS_ERR_OR_NULL(segs
)) {
267 struct sk_buff
*nskb
= segs
->next
;
271 err
= ip_fragment(net
, sk
, segs
, mtu
, ip_finish_output2
);
281 static int ip_finish_output(struct net
*net
, struct sock
*sk
, struct sk_buff
*skb
)
285 #if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
286 /* Policy lookup after SNAT yielded a new policy */
287 if (skb_dst(skb
)->xfrm
) {
288 IPCB(skb
)->flags
|= IPSKB_REROUTED
;
289 return dst_output(net
, sk
, skb
);
292 mtu
= ip_skb_dst_mtu(sk
, skb
);
294 return ip_finish_output_gso(net
, sk
, skb
, mtu
);
296 if (skb
->len
> mtu
|| (IPCB(skb
)->flags
& IPSKB_FRAG_PMTU
))
297 return ip_fragment(net
, sk
, skb
, mtu
, ip_finish_output2
);
299 return ip_finish_output2(net
, sk
, skb
);
302 int ip_mc_output(struct net
*net
, struct sock
*sk
, struct sk_buff
*skb
)
304 struct rtable
*rt
= skb_rtable(skb
);
305 struct net_device
*dev
= rt
->dst
.dev
;
308 * If the indicated interface is up and running, send the packet.
310 IP_UPD_PO_STATS(net
, IPSTATS_MIB_OUT
, skb
->len
);
313 skb
->protocol
= htons(ETH_P_IP
);
316 * Multicasts are looped back for other local users
319 if (rt
->rt_flags
&RTCF_MULTICAST
) {
321 #ifdef CONFIG_IP_MROUTE
322 /* Small optimization: do not loopback not local frames,
323 which returned after forwarding; they will be dropped
324 by ip_mr_input in any case.
325 Note, that local frames are looped back to be delivered
328 This check is duplicated in ip_mr_input at the moment.
331 ((rt
->rt_flags
& RTCF_LOCAL
) ||
332 !(IPCB(skb
)->flags
& IPSKB_FORWARDED
))
335 struct sk_buff
*newskb
= skb_clone(skb
, GFP_ATOMIC
);
337 NF_HOOK(NFPROTO_IPV4
, NF_INET_POST_ROUTING
,
338 net
, sk
, newskb
, NULL
, newskb
->dev
,
342 /* Multicasts with ttl 0 must not go beyond the host */
344 if (ip_hdr(skb
)->ttl
== 0) {
350 if (rt
->rt_flags
&RTCF_BROADCAST
) {
351 struct sk_buff
*newskb
= skb_clone(skb
, GFP_ATOMIC
);
353 NF_HOOK(NFPROTO_IPV4
, NF_INET_POST_ROUTING
,
354 net
, sk
, newskb
, NULL
, newskb
->dev
,
358 return NF_HOOK_COND(NFPROTO_IPV4
, NF_INET_POST_ROUTING
,
359 net
, sk
, skb
, NULL
, skb
->dev
,
361 !(IPCB(skb
)->flags
& IPSKB_REROUTED
));
364 int ip_output(struct net
*net
, struct sock
*sk
, struct sk_buff
*skb
)
366 struct net_device
*dev
= skb_dst(skb
)->dev
;
368 IP_UPD_PO_STATS(net
, IPSTATS_MIB_OUT
, skb
->len
);
371 skb
->protocol
= htons(ETH_P_IP
);
373 return NF_HOOK_COND(NFPROTO_IPV4
, NF_INET_POST_ROUTING
,
374 net
, sk
, skb
, NULL
, dev
,
376 !(IPCB(skb
)->flags
& IPSKB_REROUTED
));
380 * copy saddr and daddr, possibly using 64bit load/stores
382 * iph->saddr = fl4->saddr;
383 * iph->daddr = fl4->daddr;
385 static void ip_copy_addrs(struct iphdr
*iph
, const struct flowi4
*fl4
)
387 BUILD_BUG_ON(offsetof(typeof(*fl4
), daddr
) !=
388 offsetof(typeof(*fl4
), saddr
) + sizeof(fl4
->saddr
));
389 memcpy(&iph
->saddr
, &fl4
->saddr
,
390 sizeof(fl4
->saddr
) + sizeof(fl4
->daddr
));
393 /* Note: skb->sk can be different from sk, in case of tunnels */
394 int ip_queue_xmit(struct sock
*sk
, struct sk_buff
*skb
, struct flowi
*fl
)
396 struct inet_sock
*inet
= inet_sk(sk
);
397 struct net
*net
= sock_net(sk
);
398 struct ip_options_rcu
*inet_opt
;
404 /* Skip all of this if the packet is already routed,
405 * f.e. by something like SCTP.
408 inet_opt
= rcu_dereference(inet
->inet_opt
);
410 rt
= skb_rtable(skb
);
414 /* Make sure we can route this packet. */
415 rt
= (struct rtable
*)__sk_dst_check(sk
, 0);
419 /* Use correct destination address if we have options. */
420 daddr
= inet
->inet_daddr
;
421 if (inet_opt
&& inet_opt
->opt
.srr
)
422 daddr
= inet_opt
->opt
.faddr
;
424 /* If this fails, retransmit mechanism of transport layer will
425 * keep trying until route appears or the connection times
428 rt
= ip_route_output_ports(net
, fl4
, sk
,
429 daddr
, inet
->inet_saddr
,
434 sk
->sk_bound_dev_if
);
437 sk_setup_caps(sk
, &rt
->dst
);
439 skb_dst_set_noref(skb
, &rt
->dst
);
442 if (inet_opt
&& inet_opt
->opt
.is_strictroute
&& rt
->rt_uses_gateway
)
445 /* OK, we know where to send it, allocate and build IP header. */
446 skb_push(skb
, sizeof(struct iphdr
) + (inet_opt
? inet_opt
->opt
.optlen
: 0));
447 skb_reset_network_header(skb
);
449 *((__be16
*)iph
) = htons((4 << 12) | (5 << 8) | (inet
->tos
& 0xff));
450 if (ip_dont_fragment(sk
, &rt
->dst
) && !skb
->ignore_df
)
451 iph
->frag_off
= htons(IP_DF
);
454 iph
->ttl
= ip_select_ttl(inet
, &rt
->dst
);
455 iph
->protocol
= sk
->sk_protocol
;
456 ip_copy_addrs(iph
, fl4
);
458 /* Transport layer set skb->h.foo itself. */
460 if (inet_opt
&& inet_opt
->opt
.optlen
) {
461 iph
->ihl
+= inet_opt
->opt
.optlen
>> 2;
462 ip_options_build(skb
, &inet_opt
->opt
, inet
->inet_daddr
, rt
, 0);
465 ip_select_ident_segs(net
, skb
, sk
,
466 skb_shinfo(skb
)->gso_segs
?: 1);
468 /* TODO : should we use skb->sk here instead of sk ? */
469 skb
->priority
= sk
->sk_priority
;
470 skb
->mark
= sk
->sk_mark
;
472 res
= ip_local_out(net
, sk
, skb
);
478 IP_INC_STATS(net
, IPSTATS_MIB_OUTNOROUTES
);
480 return -EHOSTUNREACH
;
482 EXPORT_SYMBOL(ip_queue_xmit
);
484 static void ip_copy_metadata(struct sk_buff
*to
, struct sk_buff
*from
)
486 to
->pkt_type
= from
->pkt_type
;
487 to
->priority
= from
->priority
;
488 to
->protocol
= from
->protocol
;
490 skb_dst_copy(to
, from
);
492 to
->mark
= from
->mark
;
494 /* Copy the flags to each fragment. */
495 IPCB(to
)->flags
= IPCB(from
)->flags
;
497 #ifdef CONFIG_NET_SCHED
498 to
->tc_index
= from
->tc_index
;
501 #if IS_ENABLED(CONFIG_IP_VS)
502 to
->ipvs_property
= from
->ipvs_property
;
504 skb_copy_secmark(to
, from
);
507 static int ip_fragment(struct net
*net
, struct sock
*sk
, struct sk_buff
*skb
,
509 int (*output
)(struct net
*, struct sock
*, struct sk_buff
*))
511 struct iphdr
*iph
= ip_hdr(skb
);
513 if ((iph
->frag_off
& htons(IP_DF
)) == 0)
514 return ip_do_fragment(net
, sk
, skb
, output
);
516 if (unlikely(!skb
->ignore_df
||
517 (IPCB(skb
)->frag_max_size
&&
518 IPCB(skb
)->frag_max_size
> mtu
))) {
519 IP_INC_STATS(net
, IPSTATS_MIB_FRAGFAILS
);
520 icmp_send(skb
, ICMP_DEST_UNREACH
, ICMP_FRAG_NEEDED
,
526 return ip_do_fragment(net
, sk
, skb
, output
);
530 * This IP datagram is too large to be sent in one piece. Break it up into
531 * smaller pieces (each of size equal to IP header plus
532 * a block of the data of the original IP data part) that will yet fit in a
533 * single device frame, and queue such a frame for sending.
536 int ip_do_fragment(struct net
*net
, struct sock
*sk
, struct sk_buff
*skb
,
537 int (*output
)(struct net
*, struct sock
*, struct sk_buff
*))
541 struct net_device
*dev
;
542 struct sk_buff
*skb2
;
543 unsigned int mtu
, hlen
, left
, len
, ll_rs
;
545 __be16 not_last_frag
;
546 struct rtable
*rt
= skb_rtable(skb
);
551 /* for offloaded checksums cleanup checksum before fragmentation */
552 if (skb
->ip_summed
== CHECKSUM_PARTIAL
&&
553 (err
= skb_checksum_help(skb
)))
557 * Point into the IP datagram header.
562 mtu
= ip_skb_dst_mtu(sk
, skb
);
563 if (IPCB(skb
)->frag_max_size
&& IPCB(skb
)->frag_max_size
< mtu
)
564 mtu
= IPCB(skb
)->frag_max_size
;
567 * Setup starting values.
571 mtu
= mtu
- hlen
; /* Size of data space */
572 IPCB(skb
)->flags
|= IPSKB_FRAG_COMPLETE
;
574 /* When frag_list is given, use it. First, check its validity:
575 * some transformers could create wrong frag_list or break existing
576 * one, it is not prohibited. In this case fall back to copying.
578 * LATER: this step can be merged to real generation of fragments,
579 * we can switch to copy when see the first bad fragment.
581 if (skb_has_frag_list(skb
)) {
582 struct sk_buff
*frag
, *frag2
;
583 int first_len
= skb_pagelen(skb
);
585 if (first_len
- hlen
> mtu
||
586 ((first_len
- hlen
) & 7) ||
587 ip_is_fragment(iph
) ||
591 skb_walk_frags(skb
, frag
) {
592 /* Correct geometry. */
593 if (frag
->len
> mtu
||
594 ((frag
->len
& 7) && frag
->next
) ||
595 skb_headroom(frag
) < hlen
)
596 goto slow_path_clean
;
598 /* Partially cloned skb? */
599 if (skb_shared(frag
))
600 goto slow_path_clean
;
605 frag
->destructor
= sock_wfree
;
607 skb
->truesize
-= frag
->truesize
;
610 /* Everything is OK. Generate! */
614 frag
= skb_shinfo(skb
)->frag_list
;
615 skb_frag_list_init(skb
);
616 skb
->data_len
= first_len
- skb_headlen(skb
);
617 skb
->len
= first_len
;
618 iph
->tot_len
= htons(first_len
);
619 iph
->frag_off
= htons(IP_MF
);
623 /* Prepare header of the next frame,
624 * before previous one went down. */
626 frag
->ip_summed
= CHECKSUM_NONE
;
627 skb_reset_transport_header(frag
);
628 __skb_push(frag
, hlen
);
629 skb_reset_network_header(frag
);
630 memcpy(skb_network_header(frag
), iph
, hlen
);
632 iph
->tot_len
= htons(frag
->len
);
633 ip_copy_metadata(frag
, skb
);
635 ip_options_fragment(frag
);
636 offset
+= skb
->len
- hlen
;
637 iph
->frag_off
= htons(offset
>>3);
639 iph
->frag_off
|= htons(IP_MF
);
640 /* Ready, complete checksum */
644 err
= output(net
, sk
, skb
);
647 IP_INC_STATS(net
, IPSTATS_MIB_FRAGCREATES
);
657 IP_INC_STATS(net
, IPSTATS_MIB_FRAGOKS
);
666 IP_INC_STATS(net
, IPSTATS_MIB_FRAGFAILS
);
670 skb_walk_frags(skb
, frag2
) {
674 frag2
->destructor
= NULL
;
675 skb
->truesize
+= frag2
->truesize
;
682 left
= skb
->len
- hlen
; /* Space per frame */
683 ptr
= hlen
; /* Where to start from */
685 ll_rs
= LL_RESERVED_SPACE(rt
->dst
.dev
);
688 * Fragment the datagram.
691 offset
= (ntohs(iph
->frag_off
) & IP_OFFSET
) << 3;
692 not_last_frag
= iph
->frag_off
& htons(IP_MF
);
695 * Keep copying data until we run out.
700 /* IF: it doesn't fit, use 'mtu' - the data space left */
703 /* IF: we are not sending up to and including the packet end
704 then align the next start on an eight byte boundary */
709 /* Allocate buffer */
710 skb2
= alloc_skb(len
+ hlen
+ ll_rs
, GFP_ATOMIC
);
717 * Set up data on packet
720 ip_copy_metadata(skb2
, skb
);
721 skb_reserve(skb2
, ll_rs
);
722 skb_put(skb2
, len
+ hlen
);
723 skb_reset_network_header(skb2
);
724 skb2
->transport_header
= skb2
->network_header
+ hlen
;
727 * Charge the memory for the fragment to any owner
732 skb_set_owner_w(skb2
, skb
->sk
);
735 * Copy the packet header into the new buffer.
738 skb_copy_from_linear_data(skb
, skb_network_header(skb2
), hlen
);
741 * Copy a block of the IP datagram.
743 if (skb_copy_bits(skb
, ptr
, skb_transport_header(skb2
), len
))
748 * Fill in the new header fields.
751 iph
->frag_off
= htons((offset
>> 3));
753 if (IPCB(skb
)->flags
& IPSKB_FRAG_PMTU
)
754 iph
->frag_off
|= htons(IP_DF
);
756 /* ANK: dirty, but effective trick. Upgrade options only if
757 * the segment to be fragmented was THE FIRST (otherwise,
758 * options are already fixed) and make it ONCE
759 * on the initial skb, so that all the following fragments
760 * will inherit fixed options.
763 ip_options_fragment(skb
);
766 * Added AC : If we are fragmenting a fragment that's not the
767 * last fragment then keep MF on each bit
769 if (left
> 0 || not_last_frag
)
770 iph
->frag_off
|= htons(IP_MF
);
775 * Put this fragment into the sending queue.
777 iph
->tot_len
= htons(len
+ hlen
);
781 err
= output(net
, sk
, skb2
);
785 IP_INC_STATS(net
, IPSTATS_MIB_FRAGCREATES
);
788 IP_INC_STATS(net
, IPSTATS_MIB_FRAGOKS
);
793 IP_INC_STATS(net
, IPSTATS_MIB_FRAGFAILS
);
796 EXPORT_SYMBOL(ip_do_fragment
);
799 ip_generic_getfrag(void *from
, char *to
, int offset
, int len
, int odd
, struct sk_buff
*skb
)
801 struct msghdr
*msg
= from
;
803 if (skb
->ip_summed
== CHECKSUM_PARTIAL
) {
804 if (copy_from_iter(to
, len
, &msg
->msg_iter
) != len
)
808 if (csum_and_copy_from_iter(to
, len
, &csum
, &msg
->msg_iter
) != len
)
810 skb
->csum
= csum_block_add(skb
->csum
, csum
, odd
);
814 EXPORT_SYMBOL(ip_generic_getfrag
);
817 csum_page(struct page
*page
, int offset
, int copy
)
822 csum
= csum_partial(kaddr
+ offset
, copy
, 0);
827 static inline int ip_ufo_append_data(struct sock
*sk
,
828 struct sk_buff_head
*queue
,
829 int getfrag(void *from
, char *to
, int offset
, int len
,
830 int odd
, struct sk_buff
*skb
),
831 void *from
, int length
, int hh_len
, int fragheaderlen
,
832 int transhdrlen
, int maxfraglen
, unsigned int flags
)
837 /* There is support for UDP fragmentation offload by network
838 * device, so create one single skb packet containing complete
841 skb
= skb_peek_tail(queue
);
843 skb
= sock_alloc_send_skb(sk
,
844 hh_len
+ fragheaderlen
+ transhdrlen
+ 20,
845 (flags
& MSG_DONTWAIT
), &err
);
850 /* reserve space for Hardware header */
851 skb_reserve(skb
, hh_len
);
853 /* create space for UDP/IP header */
854 skb_put(skb
, fragheaderlen
+ transhdrlen
);
856 /* initialize network header pointer */
857 skb_reset_network_header(skb
);
859 /* initialize protocol header pointer */
860 skb
->transport_header
= skb
->network_header
+ fragheaderlen
;
864 __skb_queue_tail(queue
, skb
);
865 } else if (skb_is_gso(skb
)) {
869 skb
->ip_summed
= CHECKSUM_PARTIAL
;
870 /* specify the length of each IP datagram fragment */
871 skb_shinfo(skb
)->gso_size
= maxfraglen
- fragheaderlen
;
872 skb_shinfo(skb
)->gso_type
= SKB_GSO_UDP
;
875 return skb_append_datato_frags(sk
, skb
, getfrag
, from
,
876 (length
- transhdrlen
));
879 static int __ip_append_data(struct sock
*sk
,
881 struct sk_buff_head
*queue
,
882 struct inet_cork
*cork
,
883 struct page_frag
*pfrag
,
884 int getfrag(void *from
, char *to
, int offset
,
885 int len
, int odd
, struct sk_buff
*skb
),
886 void *from
, int length
, int transhdrlen
,
889 struct inet_sock
*inet
= inet_sk(sk
);
892 struct ip_options
*opt
= cork
->opt
;
899 unsigned int maxfraglen
, fragheaderlen
, maxnonfragsize
;
900 int csummode
= CHECKSUM_NONE
;
901 struct rtable
*rt
= (struct rtable
*)cork
->dst
;
904 skb
= skb_peek_tail(queue
);
906 exthdrlen
= !skb
? rt
->dst
.header_len
: 0;
907 mtu
= cork
->fragsize
;
908 if (cork
->tx_flags
& SKBTX_ANY_SW_TSTAMP
&&
909 sk
->sk_tsflags
& SOF_TIMESTAMPING_OPT_ID
)
910 tskey
= sk
->sk_tskey
++;
912 hh_len
= LL_RESERVED_SPACE(rt
->dst
.dev
);
914 fragheaderlen
= sizeof(struct iphdr
) + (opt
? opt
->optlen
: 0);
915 maxfraglen
= ((mtu
- fragheaderlen
) & ~7) + fragheaderlen
;
916 maxnonfragsize
= ip_sk_ignore_df(sk
) ? 0xFFFF : mtu
;
918 if (cork
->length
+ length
> maxnonfragsize
- fragheaderlen
) {
919 ip_local_error(sk
, EMSGSIZE
, fl4
->daddr
, inet
->inet_dport
,
920 mtu
- (opt
? opt
->optlen
: 0));
925 * transhdrlen > 0 means that this is the first fragment and we wish
926 * it won't be fragmented in the future.
929 length
+ fragheaderlen
<= mtu
&&
930 rt
->dst
.dev
->features
& (NETIF_F_HW_CSUM
| NETIF_F_IP_CSUM
) &&
931 !(flags
& MSG_MORE
) &&
933 csummode
= CHECKSUM_PARTIAL
;
935 cork
->length
+= length
;
936 if (((length
> mtu
) || (skb
&& skb_is_gso(skb
))) &&
937 (sk
->sk_protocol
== IPPROTO_UDP
) &&
938 (rt
->dst
.dev
->features
& NETIF_F_UFO
) && !rt
->dst
.header_len
&&
939 (sk
->sk_type
== SOCK_DGRAM
) && !sk
->sk_no_check_tx
) {
940 err
= ip_ufo_append_data(sk
, queue
, getfrag
, from
, length
,
941 hh_len
, fragheaderlen
, transhdrlen
,
948 /* So, what's going on in the loop below?
950 * We use calculated fragment length to generate chained skb,
951 * each of segments is IP fragment ready for sending to network after
952 * adding appropriate IP header.
959 /* Check if the remaining data fits into current packet. */
960 copy
= mtu
- skb
->len
;
962 copy
= maxfraglen
- skb
->len
;
965 unsigned int datalen
;
966 unsigned int fraglen
;
967 unsigned int fraggap
;
968 unsigned int alloclen
;
969 struct sk_buff
*skb_prev
;
973 fraggap
= skb_prev
->len
- maxfraglen
;
978 * If remaining data exceeds the mtu,
979 * we know we need more fragment(s).
981 datalen
= length
+ fraggap
;
982 if (datalen
> mtu
- fragheaderlen
)
983 datalen
= maxfraglen
- fragheaderlen
;
984 fraglen
= datalen
+ fragheaderlen
;
986 if ((flags
& MSG_MORE
) &&
987 !(rt
->dst
.dev
->features
&NETIF_F_SG
))
992 alloclen
+= exthdrlen
;
994 /* The last fragment gets additional space at tail.
995 * Note, with MSG_MORE we overallocate on fragments,
996 * because we have no idea what fragment will be
999 if (datalen
== length
+ fraggap
)
1000 alloclen
+= rt
->dst
.trailer_len
;
1003 skb
= sock_alloc_send_skb(sk
,
1004 alloclen
+ hh_len
+ 15,
1005 (flags
& MSG_DONTWAIT
), &err
);
1008 if (atomic_read(&sk
->sk_wmem_alloc
) <=
1010 skb
= sock_wmalloc(sk
,
1011 alloclen
+ hh_len
+ 15, 1,
1020 * Fill in the control structures
1022 skb
->ip_summed
= csummode
;
1024 skb_reserve(skb
, hh_len
);
1026 /* only the initial fragment is time stamped */
1027 skb_shinfo(skb
)->tx_flags
= cork
->tx_flags
;
1029 skb_shinfo(skb
)->tskey
= tskey
;
1033 * Find where to start putting bytes.
1035 data
= skb_put(skb
, fraglen
+ exthdrlen
);
1036 skb_set_network_header(skb
, exthdrlen
);
1037 skb
->transport_header
= (skb
->network_header
+
1039 data
+= fragheaderlen
+ exthdrlen
;
1042 skb
->csum
= skb_copy_and_csum_bits(
1043 skb_prev
, maxfraglen
,
1044 data
+ transhdrlen
, fraggap
, 0);
1045 skb_prev
->csum
= csum_sub(skb_prev
->csum
,
1048 pskb_trim_unique(skb_prev
, maxfraglen
);
1051 copy
= datalen
- transhdrlen
- fraggap
;
1052 if (copy
> 0 && getfrag(from
, data
+ transhdrlen
, offset
, copy
, fraggap
, skb
) < 0) {
1059 length
-= datalen
- fraggap
;
1062 csummode
= CHECKSUM_NONE
;
1065 * Put the packet on the pending queue.
1067 __skb_queue_tail(queue
, skb
);
1074 if (!(rt
->dst
.dev
->features
&NETIF_F_SG
)) {
1078 if (getfrag(from
, skb_put(skb
, copy
),
1079 offset
, copy
, off
, skb
) < 0) {
1080 __skb_trim(skb
, off
);
1085 int i
= skb_shinfo(skb
)->nr_frags
;
1088 if (!sk_page_frag_refill(sk
, pfrag
))
1091 if (!skb_can_coalesce(skb
, i
, pfrag
->page
,
1094 if (i
== MAX_SKB_FRAGS
)
1097 __skb_fill_page_desc(skb
, i
, pfrag
->page
,
1099 skb_shinfo(skb
)->nr_frags
= ++i
;
1100 get_page(pfrag
->page
);
1102 copy
= min_t(int, copy
, pfrag
->size
- pfrag
->offset
);
1104 page_address(pfrag
->page
) + pfrag
->offset
,
1105 offset
, copy
, skb
->len
, skb
) < 0)
1108 pfrag
->offset
+= copy
;
1109 skb_frag_size_add(&skb_shinfo(skb
)->frags
[i
- 1], copy
);
1111 skb
->data_len
+= copy
;
1112 skb
->truesize
+= copy
;
1113 atomic_add(copy
, &sk
->sk_wmem_alloc
);
1124 cork
->length
-= length
;
1125 IP_INC_STATS(sock_net(sk
), IPSTATS_MIB_OUTDISCARDS
);
1129 static int ip_setup_cork(struct sock
*sk
, struct inet_cork
*cork
,
1130 struct ipcm_cookie
*ipc
, struct rtable
**rtp
)
1132 struct ip_options_rcu
*opt
;
1136 * setup for corking.
1141 cork
->opt
= kmalloc(sizeof(struct ip_options
) + 40,
1143 if (unlikely(!cork
->opt
))
1146 memcpy(cork
->opt
, &opt
->opt
, sizeof(struct ip_options
) + opt
->opt
.optlen
);
1147 cork
->flags
|= IPCORK_OPT
;
1148 cork
->addr
= ipc
->addr
;
1154 * We steal reference to this route, caller should not release it
1157 cork
->fragsize
= ip_sk_use_pmtu(sk
) ?
1158 dst_mtu(&rt
->dst
) : rt
->dst
.dev
->mtu
;
1159 cork
->dst
= &rt
->dst
;
1161 cork
->ttl
= ipc
->ttl
;
1162 cork
->tos
= ipc
->tos
;
1163 cork
->priority
= ipc
->priority
;
1164 cork
->tx_flags
= ipc
->tx_flags
;
1170 * ip_append_data() and ip_append_page() can make one large IP datagram
1171 * from many pieces of data. Each pieces will be holded on the socket
1172 * until ip_push_pending_frames() is called. Each piece can be a page
1175 * Not only UDP, other transport protocols - e.g. raw sockets - can use
1176 * this interface potentially.
1178 * LATER: length must be adjusted by pad at tail, when it is required.
1180 int ip_append_data(struct sock
*sk
, struct flowi4
*fl4
,
1181 int getfrag(void *from
, char *to
, int offset
, int len
,
1182 int odd
, struct sk_buff
*skb
),
1183 void *from
, int length
, int transhdrlen
,
1184 struct ipcm_cookie
*ipc
, struct rtable
**rtp
,
1187 struct inet_sock
*inet
= inet_sk(sk
);
1190 if (flags
&MSG_PROBE
)
1193 if (skb_queue_empty(&sk
->sk_write_queue
)) {
1194 err
= ip_setup_cork(sk
, &inet
->cork
.base
, ipc
, rtp
);
1201 return __ip_append_data(sk
, fl4
, &sk
->sk_write_queue
, &inet
->cork
.base
,
1202 sk_page_frag(sk
), getfrag
,
1203 from
, length
, transhdrlen
, flags
);
1206 ssize_t
ip_append_page(struct sock
*sk
, struct flowi4
*fl4
, struct page
*page
,
1207 int offset
, size_t size
, int flags
)
1209 struct inet_sock
*inet
= inet_sk(sk
);
1210 struct sk_buff
*skb
;
1212 struct ip_options
*opt
= NULL
;
1213 struct inet_cork
*cork
;
1218 unsigned int maxfraglen
, fragheaderlen
, fraggap
, maxnonfragsize
;
1223 if (flags
&MSG_PROBE
)
1226 if (skb_queue_empty(&sk
->sk_write_queue
))
1229 cork
= &inet
->cork
.base
;
1230 rt
= (struct rtable
*)cork
->dst
;
1231 if (cork
->flags
& IPCORK_OPT
)
1234 if (!(rt
->dst
.dev
->features
&NETIF_F_SG
))
1237 hh_len
= LL_RESERVED_SPACE(rt
->dst
.dev
);
1238 mtu
= cork
->fragsize
;
1240 fragheaderlen
= sizeof(struct iphdr
) + (opt
? opt
->optlen
: 0);
1241 maxfraglen
= ((mtu
- fragheaderlen
) & ~7) + fragheaderlen
;
1242 maxnonfragsize
= ip_sk_ignore_df(sk
) ? 0xFFFF : mtu
;
1244 if (cork
->length
+ size
> maxnonfragsize
- fragheaderlen
) {
1245 ip_local_error(sk
, EMSGSIZE
, fl4
->daddr
, inet
->inet_dport
,
1246 mtu
- (opt
? opt
->optlen
: 0));
1250 skb
= skb_peek_tail(&sk
->sk_write_queue
);
1254 if ((size
+ skb
->len
> mtu
) &&
1255 (sk
->sk_protocol
== IPPROTO_UDP
) &&
1256 (rt
->dst
.dev
->features
& NETIF_F_UFO
)) {
1257 if (skb
->ip_summed
!= CHECKSUM_PARTIAL
)
1260 skb_shinfo(skb
)->gso_size
= mtu
- fragheaderlen
;
1261 skb_shinfo(skb
)->gso_type
= SKB_GSO_UDP
;
1263 cork
->length
+= size
;
1266 if (skb_is_gso(skb
)) {
1270 /* Check if the remaining data fits into current packet. */
1271 len
= mtu
- skb
->len
;
1273 len
= maxfraglen
- skb
->len
;
1276 struct sk_buff
*skb_prev
;
1280 fraggap
= skb_prev
->len
- maxfraglen
;
1282 alloclen
= fragheaderlen
+ hh_len
+ fraggap
+ 15;
1283 skb
= sock_wmalloc(sk
, alloclen
, 1, sk
->sk_allocation
);
1284 if (unlikely(!skb
)) {
1290 * Fill in the control structures
1292 skb
->ip_summed
= CHECKSUM_NONE
;
1294 skb_reserve(skb
, hh_len
);
1297 * Find where to start putting bytes.
1299 skb_put(skb
, fragheaderlen
+ fraggap
);
1300 skb_reset_network_header(skb
);
1301 skb
->transport_header
= (skb
->network_header
+
1304 skb
->csum
= skb_copy_and_csum_bits(skb_prev
,
1306 skb_transport_header(skb
),
1308 skb_prev
->csum
= csum_sub(skb_prev
->csum
,
1310 pskb_trim_unique(skb_prev
, maxfraglen
);
1314 * Put the packet on the pending queue.
1316 __skb_queue_tail(&sk
->sk_write_queue
, skb
);
1323 if (skb_append_pagefrags(skb
, page
, offset
, len
)) {
1328 if (skb
->ip_summed
== CHECKSUM_NONE
) {
1330 csum
= csum_page(page
, offset
, len
);
1331 skb
->csum
= csum_block_add(skb
->csum
, csum
, skb
->len
);
1335 skb
->data_len
+= len
;
1336 skb
->truesize
+= len
;
1337 atomic_add(len
, &sk
->sk_wmem_alloc
);
1344 cork
->length
-= size
;
1345 IP_INC_STATS(sock_net(sk
), IPSTATS_MIB_OUTDISCARDS
);
1349 static void ip_cork_release(struct inet_cork
*cork
)
1351 cork
->flags
&= ~IPCORK_OPT
;
1354 dst_release(cork
->dst
);
1359 * Combined all pending IP fragments on the socket as one IP datagram
1360 * and push them out.
1362 struct sk_buff
*__ip_make_skb(struct sock
*sk
,
1364 struct sk_buff_head
*queue
,
1365 struct inet_cork
*cork
)
1367 struct sk_buff
*skb
, *tmp_skb
;
1368 struct sk_buff
**tail_skb
;
1369 struct inet_sock
*inet
= inet_sk(sk
);
1370 struct net
*net
= sock_net(sk
);
1371 struct ip_options
*opt
= NULL
;
1372 struct rtable
*rt
= (struct rtable
*)cork
->dst
;
1377 skb
= __skb_dequeue(queue
);
1380 tail_skb
= &(skb_shinfo(skb
)->frag_list
);
1382 /* move skb->data to ip header from ext header */
1383 if (skb
->data
< skb_network_header(skb
))
1384 __skb_pull(skb
, skb_network_offset(skb
));
1385 while ((tmp_skb
= __skb_dequeue(queue
)) != NULL
) {
1386 __skb_pull(tmp_skb
, skb_network_header_len(skb
));
1387 *tail_skb
= tmp_skb
;
1388 tail_skb
= &(tmp_skb
->next
);
1389 skb
->len
+= tmp_skb
->len
;
1390 skb
->data_len
+= tmp_skb
->len
;
1391 skb
->truesize
+= tmp_skb
->truesize
;
1392 tmp_skb
->destructor
= NULL
;
1396 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow
1397 * to fragment the frame generated here. No matter, what transforms
1398 * how transforms change size of the packet, it will come out.
1400 skb
->ignore_df
= ip_sk_ignore_df(sk
);
1402 /* DF bit is set when we want to see DF on outgoing frames.
1403 * If ignore_df is set too, we still allow to fragment this frame
1405 if (inet
->pmtudisc
== IP_PMTUDISC_DO
||
1406 inet
->pmtudisc
== IP_PMTUDISC_PROBE
||
1407 (skb
->len
<= dst_mtu(&rt
->dst
) &&
1408 ip_dont_fragment(sk
, &rt
->dst
)))
1411 if (cork
->flags
& IPCORK_OPT
)
1416 else if (rt
->rt_type
== RTN_MULTICAST
)
1419 ttl
= ip_select_ttl(inet
, &rt
->dst
);
1424 iph
->tos
= (cork
->tos
!= -1) ? cork
->tos
: inet
->tos
;
1427 iph
->protocol
= sk
->sk_protocol
;
1428 ip_copy_addrs(iph
, fl4
);
1429 ip_select_ident(net
, skb
, sk
);
1432 iph
->ihl
+= opt
->optlen
>>2;
1433 ip_options_build(skb
, opt
, cork
->addr
, rt
, 0);
1436 skb
->priority
= (cork
->tos
!= -1) ? cork
->priority
: sk
->sk_priority
;
1437 skb
->mark
= sk
->sk_mark
;
1439 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec
1443 skb_dst_set(skb
, &rt
->dst
);
1445 if (iph
->protocol
== IPPROTO_ICMP
)
1446 icmp_out_count(net
, ((struct icmphdr
*)
1447 skb_transport_header(skb
))->type
);
1449 ip_cork_release(cork
);
1454 int ip_send_skb(struct net
*net
, struct sk_buff
*skb
)
1458 err
= ip_local_out(net
, skb
->sk
, skb
);
1461 err
= net_xmit_errno(err
);
1463 IP_INC_STATS(net
, IPSTATS_MIB_OUTDISCARDS
);
1469 int ip_push_pending_frames(struct sock
*sk
, struct flowi4
*fl4
)
1471 struct sk_buff
*skb
;
1473 skb
= ip_finish_skb(sk
, fl4
);
1477 /* Netfilter gets whole the not fragmented skb. */
1478 return ip_send_skb(sock_net(sk
), skb
);
1482 * Throw away all pending data on the socket.
1484 static void __ip_flush_pending_frames(struct sock
*sk
,
1485 struct sk_buff_head
*queue
,
1486 struct inet_cork
*cork
)
1488 struct sk_buff
*skb
;
1490 while ((skb
= __skb_dequeue_tail(queue
)) != NULL
)
1493 ip_cork_release(cork
);
1496 void ip_flush_pending_frames(struct sock
*sk
)
1498 __ip_flush_pending_frames(sk
, &sk
->sk_write_queue
, &inet_sk(sk
)->cork
.base
);
1501 struct sk_buff
*ip_make_skb(struct sock
*sk
,
1503 int getfrag(void *from
, char *to
, int offset
,
1504 int len
, int odd
, struct sk_buff
*skb
),
1505 void *from
, int length
, int transhdrlen
,
1506 struct ipcm_cookie
*ipc
, struct rtable
**rtp
,
1509 struct inet_cork cork
;
1510 struct sk_buff_head queue
;
1513 if (flags
& MSG_PROBE
)
1516 __skb_queue_head_init(&queue
);
1521 err
= ip_setup_cork(sk
, &cork
, ipc
, rtp
);
1523 return ERR_PTR(err
);
1525 err
= __ip_append_data(sk
, fl4
, &queue
, &cork
,
1526 ¤t
->task_frag
, getfrag
,
1527 from
, length
, transhdrlen
, flags
);
1529 __ip_flush_pending_frames(sk
, &queue
, &cork
);
1530 return ERR_PTR(err
);
1533 return __ip_make_skb(sk
, fl4
, &queue
, &cork
);
1537 * Fetch data from kernel space and fill in checksum if needed.
1539 static int ip_reply_glue_bits(void *dptr
, char *to
, int offset
,
1540 int len
, int odd
, struct sk_buff
*skb
)
1544 csum
= csum_partial_copy_nocheck(dptr
+offset
, to
, len
, 0);
1545 skb
->csum
= csum_block_add(skb
->csum
, csum
, odd
);
1550 * Generic function to send a packet as reply to another packet.
1551 * Used to send some TCP resets/acks so far.
1553 void ip_send_unicast_reply(struct sock
*sk
, struct sk_buff
*skb
,
1554 const struct ip_options
*sopt
,
1555 __be32 daddr
, __be32 saddr
,
1556 const struct ip_reply_arg
*arg
,
1559 struct ip_options_data replyopts
;
1560 struct ipcm_cookie ipc
;
1562 struct rtable
*rt
= skb_rtable(skb
);
1563 struct net
*net
= sock_net(sk
);
1564 struct sk_buff
*nskb
;
1568 if (__ip_options_echo(&replyopts
.opt
.opt
, skb
, sopt
))
1577 if (replyopts
.opt
.opt
.optlen
) {
1578 ipc
.opt
= &replyopts
.opt
;
1580 if (replyopts
.opt
.opt
.srr
)
1581 daddr
= replyopts
.opt
.opt
.faddr
;
1584 oif
= arg
->bound_dev_if
;
1585 oif
= oif
? : skb
->skb_iif
;
1587 flowi4_init_output(&fl4
, oif
,
1588 IP4_REPLY_MARK(net
, skb
->mark
),
1590 RT_SCOPE_UNIVERSE
, ip_hdr(skb
)->protocol
,
1591 ip_reply_arg_flowi_flags(arg
),
1593 tcp_hdr(skb
)->source
, tcp_hdr(skb
)->dest
);
1594 security_skb_classify_flow(skb
, flowi4_to_flowi(&fl4
));
1595 rt
= ip_route_output_key(net
, &fl4
);
1599 inet_sk(sk
)->tos
= arg
->tos
;
1601 sk
->sk_priority
= skb
->priority
;
1602 sk
->sk_protocol
= ip_hdr(skb
)->protocol
;
1603 sk
->sk_bound_dev_if
= arg
->bound_dev_if
;
1604 sk
->sk_sndbuf
= sysctl_wmem_default
;
1605 err
= ip_append_data(sk
, &fl4
, ip_reply_glue_bits
, arg
->iov
->iov_base
,
1606 len
, 0, &ipc
, &rt
, MSG_DONTWAIT
);
1607 if (unlikely(err
)) {
1608 ip_flush_pending_frames(sk
);
1612 nskb
= skb_peek(&sk
->sk_write_queue
);
1614 if (arg
->csumoffset
>= 0)
1615 *((__sum16
*)skb_transport_header(nskb
) +
1616 arg
->csumoffset
) = csum_fold(csum_add(nskb
->csum
,
1618 nskb
->ip_summed
= CHECKSUM_NONE
;
1619 ip_push_pending_frames(sk
, &fl4
);
1625 void __init
ip_init(void)
1630 #if defined(CONFIG_IP_MULTICAST)