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: seglen is <= mtu
244 if (skb_gso_validate_mtu(skb
, mtu
))
245 return ip_finish_output2(net
, sk
, skb
);
247 /* Slowpath - GSO segment length exceeds the egress MTU.
249 * This can happen in several cases:
250 * - Forwarding of a TCP GRO skb, when DF flag is not set.
251 * - Forwarding of an skb that arrived on a virtualization interface
252 * (virtio-net/vhost/tap) with TSO/GSO size set by other network
254 * - Local GSO skb transmitted on an NETIF_F_TSO tunnel stacked over an
255 * interface with a smaller MTU.
256 * - Arriving GRO skb (or GSO skb in a virtualized environment) that is
257 * bridged to a NETIF_F_TSO tunnel stacked over an interface with an
260 features
= netif_skb_features(skb
);
261 BUILD_BUG_ON(sizeof(*IPCB(skb
)) > SKB_SGO_CB_OFFSET
);
262 segs
= skb_gso_segment(skb
, features
& ~NETIF_F_GSO_MASK
);
263 if (IS_ERR_OR_NULL(segs
)) {
271 struct sk_buff
*nskb
= segs
->next
;
275 err
= ip_fragment(net
, sk
, segs
, mtu
, ip_finish_output2
);
285 static int ip_finish_output(struct net
*net
, struct sock
*sk
, struct sk_buff
*skb
)
289 #if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
290 /* Policy lookup after SNAT yielded a new policy */
291 if (skb_dst(skb
)->xfrm
) {
292 IPCB(skb
)->flags
|= IPSKB_REROUTED
;
293 return dst_output(net
, sk
, skb
);
296 mtu
= ip_skb_dst_mtu(sk
, skb
);
298 return ip_finish_output_gso(net
, sk
, skb
, mtu
);
300 if (skb
->len
> mtu
|| (IPCB(skb
)->flags
& IPSKB_FRAG_PMTU
))
301 return ip_fragment(net
, sk
, skb
, mtu
, ip_finish_output2
);
303 return ip_finish_output2(net
, sk
, skb
);
306 int ip_mc_output(struct net
*net
, struct sock
*sk
, struct sk_buff
*skb
)
308 struct rtable
*rt
= skb_rtable(skb
);
309 struct net_device
*dev
= rt
->dst
.dev
;
312 * If the indicated interface is up and running, send the packet.
314 IP_UPD_PO_STATS(net
, IPSTATS_MIB_OUT
, skb
->len
);
317 skb
->protocol
= htons(ETH_P_IP
);
320 * Multicasts are looped back for other local users
323 if (rt
->rt_flags
&RTCF_MULTICAST
) {
325 #ifdef CONFIG_IP_MROUTE
326 /* Small optimization: do not loopback not local frames,
327 which returned after forwarding; they will be dropped
328 by ip_mr_input in any case.
329 Note, that local frames are looped back to be delivered
332 This check is duplicated in ip_mr_input at the moment.
335 ((rt
->rt_flags
& RTCF_LOCAL
) ||
336 !(IPCB(skb
)->flags
& IPSKB_FORWARDED
))
339 struct sk_buff
*newskb
= skb_clone(skb
, GFP_ATOMIC
);
341 NF_HOOK(NFPROTO_IPV4
, NF_INET_POST_ROUTING
,
342 net
, sk
, newskb
, NULL
, newskb
->dev
,
346 /* Multicasts with ttl 0 must not go beyond the host */
348 if (ip_hdr(skb
)->ttl
== 0) {
354 if (rt
->rt_flags
&RTCF_BROADCAST
) {
355 struct sk_buff
*newskb
= skb_clone(skb
, GFP_ATOMIC
);
357 NF_HOOK(NFPROTO_IPV4
, NF_INET_POST_ROUTING
,
358 net
, sk
, newskb
, NULL
, newskb
->dev
,
362 return NF_HOOK_COND(NFPROTO_IPV4
, NF_INET_POST_ROUTING
,
363 net
, sk
, skb
, NULL
, skb
->dev
,
365 !(IPCB(skb
)->flags
& IPSKB_REROUTED
));
368 int ip_output(struct net
*net
, struct sock
*sk
, struct sk_buff
*skb
)
370 struct net_device
*dev
= skb_dst(skb
)->dev
;
372 IP_UPD_PO_STATS(net
, IPSTATS_MIB_OUT
, skb
->len
);
375 skb
->protocol
= htons(ETH_P_IP
);
377 return NF_HOOK_COND(NFPROTO_IPV4
, NF_INET_POST_ROUTING
,
378 net
, sk
, skb
, NULL
, dev
,
380 !(IPCB(skb
)->flags
& IPSKB_REROUTED
));
384 * copy saddr and daddr, possibly using 64bit load/stores
386 * iph->saddr = fl4->saddr;
387 * iph->daddr = fl4->daddr;
389 static void ip_copy_addrs(struct iphdr
*iph
, const struct flowi4
*fl4
)
391 BUILD_BUG_ON(offsetof(typeof(*fl4
), daddr
) !=
392 offsetof(typeof(*fl4
), saddr
) + sizeof(fl4
->saddr
));
393 memcpy(&iph
->saddr
, &fl4
->saddr
,
394 sizeof(fl4
->saddr
) + sizeof(fl4
->daddr
));
397 /* Note: skb->sk can be different from sk, in case of tunnels */
398 int ip_queue_xmit(struct sock
*sk
, struct sk_buff
*skb
, struct flowi
*fl
)
400 struct inet_sock
*inet
= inet_sk(sk
);
401 struct net
*net
= sock_net(sk
);
402 struct ip_options_rcu
*inet_opt
;
408 /* Skip all of this if the packet is already routed,
409 * f.e. by something like SCTP.
412 inet_opt
= rcu_dereference(inet
->inet_opt
);
414 rt
= skb_rtable(skb
);
418 /* Make sure we can route this packet. */
419 rt
= (struct rtable
*)__sk_dst_check(sk
, 0);
423 /* Use correct destination address if we have options. */
424 daddr
= inet
->inet_daddr
;
425 if (inet_opt
&& inet_opt
->opt
.srr
)
426 daddr
= inet_opt
->opt
.faddr
;
428 /* If this fails, retransmit mechanism of transport layer will
429 * keep trying until route appears or the connection times
432 rt
= ip_route_output_ports(net
, fl4
, sk
,
433 daddr
, inet
->inet_saddr
,
438 sk
->sk_bound_dev_if
);
441 sk_setup_caps(sk
, &rt
->dst
);
443 skb_dst_set_noref(skb
, &rt
->dst
);
446 if (inet_opt
&& inet_opt
->opt
.is_strictroute
&& rt
->rt_uses_gateway
)
449 /* OK, we know where to send it, allocate and build IP header. */
450 skb_push(skb
, sizeof(struct iphdr
) + (inet_opt
? inet_opt
->opt
.optlen
: 0));
451 skb_reset_network_header(skb
);
453 *((__be16
*)iph
) = htons((4 << 12) | (5 << 8) | (inet
->tos
& 0xff));
454 if (ip_dont_fragment(sk
, &rt
->dst
) && !skb
->ignore_df
)
455 iph
->frag_off
= htons(IP_DF
);
458 iph
->ttl
= ip_select_ttl(inet
, &rt
->dst
);
459 iph
->protocol
= sk
->sk_protocol
;
460 ip_copy_addrs(iph
, fl4
);
462 /* Transport layer set skb->h.foo itself. */
464 if (inet_opt
&& inet_opt
->opt
.optlen
) {
465 iph
->ihl
+= inet_opt
->opt
.optlen
>> 2;
466 ip_options_build(skb
, &inet_opt
->opt
, inet
->inet_daddr
, rt
, 0);
469 ip_select_ident_segs(net
, skb
, sk
,
470 skb_shinfo(skb
)->gso_segs
?: 1);
472 /* TODO : should we use skb->sk here instead of sk ? */
473 skb
->priority
= sk
->sk_priority
;
474 skb
->mark
= sk
->sk_mark
;
476 res
= ip_local_out(net
, sk
, skb
);
482 IP_INC_STATS(net
, IPSTATS_MIB_OUTNOROUTES
);
484 return -EHOSTUNREACH
;
486 EXPORT_SYMBOL(ip_queue_xmit
);
488 static void ip_copy_metadata(struct sk_buff
*to
, struct sk_buff
*from
)
490 to
->pkt_type
= from
->pkt_type
;
491 to
->priority
= from
->priority
;
492 to
->protocol
= from
->protocol
;
494 skb_dst_copy(to
, from
);
496 to
->mark
= from
->mark
;
498 /* Copy the flags to each fragment. */
499 IPCB(to
)->flags
= IPCB(from
)->flags
;
501 #ifdef CONFIG_NET_SCHED
502 to
->tc_index
= from
->tc_index
;
505 #if IS_ENABLED(CONFIG_IP_VS)
506 to
->ipvs_property
= from
->ipvs_property
;
508 skb_copy_secmark(to
, from
);
511 static int ip_fragment(struct net
*net
, struct sock
*sk
, struct sk_buff
*skb
,
513 int (*output
)(struct net
*, struct sock
*, struct sk_buff
*))
515 struct iphdr
*iph
= ip_hdr(skb
);
517 if ((iph
->frag_off
& htons(IP_DF
)) == 0)
518 return ip_do_fragment(net
, sk
, skb
, output
);
520 if (unlikely(!skb
->ignore_df
||
521 (IPCB(skb
)->frag_max_size
&&
522 IPCB(skb
)->frag_max_size
> mtu
))) {
523 IP_INC_STATS(net
, IPSTATS_MIB_FRAGFAILS
);
524 icmp_send(skb
, ICMP_DEST_UNREACH
, ICMP_FRAG_NEEDED
,
530 return ip_do_fragment(net
, sk
, skb
, output
);
534 * This IP datagram is too large to be sent in one piece. Break it up into
535 * smaller pieces (each of size equal to IP header plus
536 * a block of the data of the original IP data part) that will yet fit in a
537 * single device frame, and queue such a frame for sending.
540 int ip_do_fragment(struct net
*net
, struct sock
*sk
, struct sk_buff
*skb
,
541 int (*output
)(struct net
*, struct sock
*, struct sk_buff
*))
545 struct sk_buff
*skb2
;
546 unsigned int mtu
, hlen
, left
, len
, ll_rs
;
548 __be16 not_last_frag
;
549 struct rtable
*rt
= skb_rtable(skb
);
552 /* for offloaded checksums cleanup checksum before fragmentation */
553 if (skb
->ip_summed
== CHECKSUM_PARTIAL
&&
554 (err
= skb_checksum_help(skb
)))
558 * Point into the IP datagram header.
563 mtu
= ip_skb_dst_mtu(sk
, skb
);
564 if (IPCB(skb
)->frag_max_size
&& IPCB(skb
)->frag_max_size
< mtu
)
565 mtu
= IPCB(skb
)->frag_max_size
;
568 * Setup starting values.
572 mtu
= mtu
- hlen
; /* Size of data space */
573 IPCB(skb
)->flags
|= IPSKB_FRAG_COMPLETE
;
575 /* When frag_list is given, use it. First, check its validity:
576 * some transformers could create wrong frag_list or break existing
577 * one, it is not prohibited. In this case fall back to copying.
579 * LATER: this step can be merged to real generation of fragments,
580 * we can switch to copy when see the first bad fragment.
582 if (skb_has_frag_list(skb
)) {
583 struct sk_buff
*frag
, *frag2
;
584 int first_len
= skb_pagelen(skb
);
586 if (first_len
- hlen
> mtu
||
587 ((first_len
- hlen
) & 7) ||
588 ip_is_fragment(iph
) ||
592 skb_walk_frags(skb
, frag
) {
593 /* Correct geometry. */
594 if (frag
->len
> mtu
||
595 ((frag
->len
& 7) && frag
->next
) ||
596 skb_headroom(frag
) < hlen
)
597 goto slow_path_clean
;
599 /* Partially cloned skb? */
600 if (skb_shared(frag
))
601 goto slow_path_clean
;
606 frag
->destructor
= sock_wfree
;
608 skb
->truesize
-= frag
->truesize
;
611 /* Everything is OK. Generate! */
615 frag
= skb_shinfo(skb
)->frag_list
;
616 skb_frag_list_init(skb
);
617 skb
->data_len
= first_len
- skb_headlen(skb
);
618 skb
->len
= first_len
;
619 iph
->tot_len
= htons(first_len
);
620 iph
->frag_off
= htons(IP_MF
);
624 /* Prepare header of the next frame,
625 * before previous one went down. */
627 frag
->ip_summed
= CHECKSUM_NONE
;
628 skb_reset_transport_header(frag
);
629 __skb_push(frag
, hlen
);
630 skb_reset_network_header(frag
);
631 memcpy(skb_network_header(frag
), iph
, hlen
);
633 iph
->tot_len
= htons(frag
->len
);
634 ip_copy_metadata(frag
, skb
);
636 ip_options_fragment(frag
);
637 offset
+= skb
->len
- hlen
;
638 iph
->frag_off
= htons(offset
>>3);
640 iph
->frag_off
|= htons(IP_MF
);
641 /* Ready, complete checksum */
645 err
= output(net
, sk
, skb
);
648 IP_INC_STATS(net
, IPSTATS_MIB_FRAGCREATES
);
658 IP_INC_STATS(net
, IPSTATS_MIB_FRAGOKS
);
667 IP_INC_STATS(net
, IPSTATS_MIB_FRAGFAILS
);
671 skb_walk_frags(skb
, frag2
) {
675 frag2
->destructor
= NULL
;
676 skb
->truesize
+= frag2
->truesize
;
683 left
= skb
->len
- hlen
; /* Space per frame */
684 ptr
= hlen
; /* Where to start from */
686 ll_rs
= LL_RESERVED_SPACE(rt
->dst
.dev
);
689 * Fragment the datagram.
692 offset
= (ntohs(iph
->frag_off
) & IP_OFFSET
) << 3;
693 not_last_frag
= iph
->frag_off
& htons(IP_MF
);
696 * Keep copying data until we run out.
701 /* IF: it doesn't fit, use 'mtu' - the data space left */
704 /* IF: we are not sending up to and including the packet end
705 then align the next start on an eight byte boundary */
710 /* Allocate buffer */
711 skb2
= alloc_skb(len
+ hlen
+ ll_rs
, GFP_ATOMIC
);
718 * Set up data on packet
721 ip_copy_metadata(skb2
, skb
);
722 skb_reserve(skb2
, ll_rs
);
723 skb_put(skb2
, len
+ hlen
);
724 skb_reset_network_header(skb2
);
725 skb2
->transport_header
= skb2
->network_header
+ hlen
;
728 * Charge the memory for the fragment to any owner
733 skb_set_owner_w(skb2
, skb
->sk
);
736 * Copy the packet header into the new buffer.
739 skb_copy_from_linear_data(skb
, skb_network_header(skb2
), hlen
);
742 * Copy a block of the IP datagram.
744 if (skb_copy_bits(skb
, ptr
, skb_transport_header(skb2
), len
))
749 * Fill in the new header fields.
752 iph
->frag_off
= htons((offset
>> 3));
754 if (IPCB(skb
)->flags
& IPSKB_FRAG_PMTU
)
755 iph
->frag_off
|= htons(IP_DF
);
757 /* ANK: dirty, but effective trick. Upgrade options only if
758 * the segment to be fragmented was THE FIRST (otherwise,
759 * options are already fixed) and make it ONCE
760 * on the initial skb, so that all the following fragments
761 * will inherit fixed options.
764 ip_options_fragment(skb
);
767 * Added AC : If we are fragmenting a fragment that's not the
768 * last fragment then keep MF on each bit
770 if (left
> 0 || not_last_frag
)
771 iph
->frag_off
|= htons(IP_MF
);
776 * Put this fragment into the sending queue.
778 iph
->tot_len
= htons(len
+ hlen
);
782 err
= output(net
, sk
, skb2
);
786 IP_INC_STATS(net
, IPSTATS_MIB_FRAGCREATES
);
789 IP_INC_STATS(net
, IPSTATS_MIB_FRAGOKS
);
794 IP_INC_STATS(net
, IPSTATS_MIB_FRAGFAILS
);
797 EXPORT_SYMBOL(ip_do_fragment
);
800 ip_generic_getfrag(void *from
, char *to
, int offset
, int len
, int odd
, struct sk_buff
*skb
)
802 struct msghdr
*msg
= from
;
804 if (skb
->ip_summed
== CHECKSUM_PARTIAL
) {
805 if (copy_from_iter(to
, len
, &msg
->msg_iter
) != len
)
809 if (csum_and_copy_from_iter(to
, len
, &csum
, &msg
->msg_iter
) != len
)
811 skb
->csum
= csum_block_add(skb
->csum
, csum
, odd
);
815 EXPORT_SYMBOL(ip_generic_getfrag
);
818 csum_page(struct page
*page
, int offset
, int copy
)
823 csum
= csum_partial(kaddr
+ offset
, copy
, 0);
828 static inline int ip_ufo_append_data(struct sock
*sk
,
829 struct sk_buff_head
*queue
,
830 int getfrag(void *from
, char *to
, int offset
, int len
,
831 int odd
, struct sk_buff
*skb
),
832 void *from
, int length
, int hh_len
, int fragheaderlen
,
833 int transhdrlen
, int maxfraglen
, unsigned int flags
)
838 /* There is support for UDP fragmentation offload by network
839 * device, so create one single skb packet containing complete
842 skb
= skb_peek_tail(queue
);
844 skb
= sock_alloc_send_skb(sk
,
845 hh_len
+ fragheaderlen
+ transhdrlen
+ 20,
846 (flags
& MSG_DONTWAIT
), &err
);
851 /* reserve space for Hardware header */
852 skb_reserve(skb
, hh_len
);
854 /* create space for UDP/IP header */
855 skb_put(skb
, fragheaderlen
+ transhdrlen
);
857 /* initialize network header pointer */
858 skb_reset_network_header(skb
);
860 /* initialize protocol header pointer */
861 skb
->transport_header
= skb
->network_header
+ fragheaderlen
;
865 __skb_queue_tail(queue
, skb
);
866 } else if (skb_is_gso(skb
)) {
870 skb
->ip_summed
= CHECKSUM_PARTIAL
;
871 /* specify the length of each IP datagram fragment */
872 skb_shinfo(skb
)->gso_size
= maxfraglen
- fragheaderlen
;
873 skb_shinfo(skb
)->gso_type
= SKB_GSO_UDP
;
876 return skb_append_datato_frags(sk
, skb
, getfrag
, from
,
877 (length
- transhdrlen
));
880 static int __ip_append_data(struct sock
*sk
,
882 struct sk_buff_head
*queue
,
883 struct inet_cork
*cork
,
884 struct page_frag
*pfrag
,
885 int getfrag(void *from
, char *to
, int offset
,
886 int len
, int odd
, struct sk_buff
*skb
),
887 void *from
, int length
, int transhdrlen
,
890 struct inet_sock
*inet
= inet_sk(sk
);
893 struct ip_options
*opt
= cork
->opt
;
900 unsigned int maxfraglen
, fragheaderlen
, maxnonfragsize
;
901 int csummode
= CHECKSUM_NONE
;
902 struct rtable
*rt
= (struct rtable
*)cork
->dst
;
905 skb
= skb_peek_tail(queue
);
907 exthdrlen
= !skb
? rt
->dst
.header_len
: 0;
908 mtu
= cork
->fragsize
;
909 if (cork
->tx_flags
& SKBTX_ANY_SW_TSTAMP
&&
910 sk
->sk_tsflags
& SOF_TIMESTAMPING_OPT_ID
)
911 tskey
= sk
->sk_tskey
++;
913 hh_len
= LL_RESERVED_SPACE(rt
->dst
.dev
);
915 fragheaderlen
= sizeof(struct iphdr
) + (opt
? opt
->optlen
: 0);
916 maxfraglen
= ((mtu
- fragheaderlen
) & ~7) + fragheaderlen
;
917 maxnonfragsize
= ip_sk_ignore_df(sk
) ? 0xFFFF : mtu
;
919 if (cork
->length
+ length
> maxnonfragsize
- fragheaderlen
) {
920 ip_local_error(sk
, EMSGSIZE
, fl4
->daddr
, inet
->inet_dport
,
921 mtu
- (opt
? opt
->optlen
: 0));
926 * transhdrlen > 0 means that this is the first fragment and we wish
927 * it won't be fragmented in the future.
930 length
+ fragheaderlen
<= mtu
&&
931 rt
->dst
.dev
->features
& (NETIF_F_HW_CSUM
| NETIF_F_IP_CSUM
) &&
932 !(flags
& MSG_MORE
) &&
934 csummode
= CHECKSUM_PARTIAL
;
936 cork
->length
+= length
;
937 if (((length
> mtu
) || (skb
&& skb_is_gso(skb
))) &&
938 (sk
->sk_protocol
== IPPROTO_UDP
) &&
939 (rt
->dst
.dev
->features
& NETIF_F_UFO
) && !rt
->dst
.header_len
&&
940 (sk
->sk_type
== SOCK_DGRAM
) && !sk
->sk_no_check_tx
) {
941 err
= ip_ufo_append_data(sk
, queue
, getfrag
, from
, length
,
942 hh_len
, fragheaderlen
, transhdrlen
,
949 /* So, what's going on in the loop below?
951 * We use calculated fragment length to generate chained skb,
952 * each of segments is IP fragment ready for sending to network after
953 * adding appropriate IP header.
960 /* Check if the remaining data fits into current packet. */
961 copy
= mtu
- skb
->len
;
963 copy
= maxfraglen
- skb
->len
;
966 unsigned int datalen
;
967 unsigned int fraglen
;
968 unsigned int fraggap
;
969 unsigned int alloclen
;
970 struct sk_buff
*skb_prev
;
974 fraggap
= skb_prev
->len
- maxfraglen
;
979 * If remaining data exceeds the mtu,
980 * we know we need more fragment(s).
982 datalen
= length
+ fraggap
;
983 if (datalen
> mtu
- fragheaderlen
)
984 datalen
= maxfraglen
- fragheaderlen
;
985 fraglen
= datalen
+ fragheaderlen
;
987 if ((flags
& MSG_MORE
) &&
988 !(rt
->dst
.dev
->features
&NETIF_F_SG
))
993 alloclen
+= exthdrlen
;
995 /* The last fragment gets additional space at tail.
996 * Note, with MSG_MORE we overallocate on fragments,
997 * because we have no idea what fragment will be
1000 if (datalen
== length
+ fraggap
)
1001 alloclen
+= rt
->dst
.trailer_len
;
1004 skb
= sock_alloc_send_skb(sk
,
1005 alloclen
+ hh_len
+ 15,
1006 (flags
& MSG_DONTWAIT
), &err
);
1009 if (atomic_read(&sk
->sk_wmem_alloc
) <=
1011 skb
= sock_wmalloc(sk
,
1012 alloclen
+ hh_len
+ 15, 1,
1021 * Fill in the control structures
1023 skb
->ip_summed
= csummode
;
1025 skb_reserve(skb
, hh_len
);
1027 /* only the initial fragment is time stamped */
1028 skb_shinfo(skb
)->tx_flags
= cork
->tx_flags
;
1030 skb_shinfo(skb
)->tskey
= tskey
;
1034 * Find where to start putting bytes.
1036 data
= skb_put(skb
, fraglen
+ exthdrlen
);
1037 skb_set_network_header(skb
, exthdrlen
);
1038 skb
->transport_header
= (skb
->network_header
+
1040 data
+= fragheaderlen
+ exthdrlen
;
1043 skb
->csum
= skb_copy_and_csum_bits(
1044 skb_prev
, maxfraglen
,
1045 data
+ transhdrlen
, fraggap
, 0);
1046 skb_prev
->csum
= csum_sub(skb_prev
->csum
,
1049 pskb_trim_unique(skb_prev
, maxfraglen
);
1052 copy
= datalen
- transhdrlen
- fraggap
;
1053 if (copy
> 0 && getfrag(from
, data
+ transhdrlen
, offset
, copy
, fraggap
, skb
) < 0) {
1060 length
-= datalen
- fraggap
;
1063 csummode
= CHECKSUM_NONE
;
1066 * Put the packet on the pending queue.
1068 __skb_queue_tail(queue
, skb
);
1075 if (!(rt
->dst
.dev
->features
&NETIF_F_SG
)) {
1079 if (getfrag(from
, skb_put(skb
, copy
),
1080 offset
, copy
, off
, skb
) < 0) {
1081 __skb_trim(skb
, off
);
1086 int i
= skb_shinfo(skb
)->nr_frags
;
1089 if (!sk_page_frag_refill(sk
, pfrag
))
1092 if (!skb_can_coalesce(skb
, i
, pfrag
->page
,
1095 if (i
== MAX_SKB_FRAGS
)
1098 __skb_fill_page_desc(skb
, i
, pfrag
->page
,
1100 skb_shinfo(skb
)->nr_frags
= ++i
;
1101 get_page(pfrag
->page
);
1103 copy
= min_t(int, copy
, pfrag
->size
- pfrag
->offset
);
1105 page_address(pfrag
->page
) + pfrag
->offset
,
1106 offset
, copy
, skb
->len
, skb
) < 0)
1109 pfrag
->offset
+= copy
;
1110 skb_frag_size_add(&skb_shinfo(skb
)->frags
[i
- 1], copy
);
1112 skb
->data_len
+= copy
;
1113 skb
->truesize
+= copy
;
1114 atomic_add(copy
, &sk
->sk_wmem_alloc
);
1125 cork
->length
-= length
;
1126 IP_INC_STATS(sock_net(sk
), IPSTATS_MIB_OUTDISCARDS
);
1130 static int ip_setup_cork(struct sock
*sk
, struct inet_cork
*cork
,
1131 struct ipcm_cookie
*ipc
, struct rtable
**rtp
)
1133 struct ip_options_rcu
*opt
;
1137 * setup for corking.
1142 cork
->opt
= kmalloc(sizeof(struct ip_options
) + 40,
1144 if (unlikely(!cork
->opt
))
1147 memcpy(cork
->opt
, &opt
->opt
, sizeof(struct ip_options
) + opt
->opt
.optlen
);
1148 cork
->flags
|= IPCORK_OPT
;
1149 cork
->addr
= ipc
->addr
;
1155 * We steal reference to this route, caller should not release it
1158 cork
->fragsize
= ip_sk_use_pmtu(sk
) ?
1159 dst_mtu(&rt
->dst
) : rt
->dst
.dev
->mtu
;
1160 cork
->dst
= &rt
->dst
;
1162 cork
->ttl
= ipc
->ttl
;
1163 cork
->tos
= ipc
->tos
;
1164 cork
->priority
= ipc
->priority
;
1165 cork
->tx_flags
= ipc
->tx_flags
;
1171 * ip_append_data() and ip_append_page() can make one large IP datagram
1172 * from many pieces of data. Each pieces will be holded on the socket
1173 * until ip_push_pending_frames() is called. Each piece can be a page
1176 * Not only UDP, other transport protocols - e.g. raw sockets - can use
1177 * this interface potentially.
1179 * LATER: length must be adjusted by pad at tail, when it is required.
1181 int ip_append_data(struct sock
*sk
, struct flowi4
*fl4
,
1182 int getfrag(void *from
, char *to
, int offset
, int len
,
1183 int odd
, struct sk_buff
*skb
),
1184 void *from
, int length
, int transhdrlen
,
1185 struct ipcm_cookie
*ipc
, struct rtable
**rtp
,
1188 struct inet_sock
*inet
= inet_sk(sk
);
1191 if (flags
&MSG_PROBE
)
1194 if (skb_queue_empty(&sk
->sk_write_queue
)) {
1195 err
= ip_setup_cork(sk
, &inet
->cork
.base
, ipc
, rtp
);
1202 return __ip_append_data(sk
, fl4
, &sk
->sk_write_queue
, &inet
->cork
.base
,
1203 sk_page_frag(sk
), getfrag
,
1204 from
, length
, transhdrlen
, flags
);
1207 ssize_t
ip_append_page(struct sock
*sk
, struct flowi4
*fl4
, struct page
*page
,
1208 int offset
, size_t size
, int flags
)
1210 struct inet_sock
*inet
= inet_sk(sk
);
1211 struct sk_buff
*skb
;
1213 struct ip_options
*opt
= NULL
;
1214 struct inet_cork
*cork
;
1219 unsigned int maxfraglen
, fragheaderlen
, fraggap
, maxnonfragsize
;
1224 if (flags
&MSG_PROBE
)
1227 if (skb_queue_empty(&sk
->sk_write_queue
))
1230 cork
= &inet
->cork
.base
;
1231 rt
= (struct rtable
*)cork
->dst
;
1232 if (cork
->flags
& IPCORK_OPT
)
1235 if (!(rt
->dst
.dev
->features
&NETIF_F_SG
))
1238 hh_len
= LL_RESERVED_SPACE(rt
->dst
.dev
);
1239 mtu
= cork
->fragsize
;
1241 fragheaderlen
= sizeof(struct iphdr
) + (opt
? opt
->optlen
: 0);
1242 maxfraglen
= ((mtu
- fragheaderlen
) & ~7) + fragheaderlen
;
1243 maxnonfragsize
= ip_sk_ignore_df(sk
) ? 0xFFFF : mtu
;
1245 if (cork
->length
+ size
> maxnonfragsize
- fragheaderlen
) {
1246 ip_local_error(sk
, EMSGSIZE
, fl4
->daddr
, inet
->inet_dport
,
1247 mtu
- (opt
? opt
->optlen
: 0));
1251 skb
= skb_peek_tail(&sk
->sk_write_queue
);
1255 if ((size
+ skb
->len
> mtu
) &&
1256 (sk
->sk_protocol
== IPPROTO_UDP
) &&
1257 (rt
->dst
.dev
->features
& NETIF_F_UFO
)) {
1258 if (skb
->ip_summed
!= CHECKSUM_PARTIAL
)
1261 skb_shinfo(skb
)->gso_size
= mtu
- fragheaderlen
;
1262 skb_shinfo(skb
)->gso_type
= SKB_GSO_UDP
;
1264 cork
->length
+= size
;
1267 if (skb_is_gso(skb
)) {
1271 /* Check if the remaining data fits into current packet. */
1272 len
= mtu
- skb
->len
;
1274 len
= maxfraglen
- skb
->len
;
1277 struct sk_buff
*skb_prev
;
1281 fraggap
= skb_prev
->len
- maxfraglen
;
1283 alloclen
= fragheaderlen
+ hh_len
+ fraggap
+ 15;
1284 skb
= sock_wmalloc(sk
, alloclen
, 1, sk
->sk_allocation
);
1285 if (unlikely(!skb
)) {
1291 * Fill in the control structures
1293 skb
->ip_summed
= CHECKSUM_NONE
;
1295 skb_reserve(skb
, hh_len
);
1298 * Find where to start putting bytes.
1300 skb_put(skb
, fragheaderlen
+ fraggap
);
1301 skb_reset_network_header(skb
);
1302 skb
->transport_header
= (skb
->network_header
+
1305 skb
->csum
= skb_copy_and_csum_bits(skb_prev
,
1307 skb_transport_header(skb
),
1309 skb_prev
->csum
= csum_sub(skb_prev
->csum
,
1311 pskb_trim_unique(skb_prev
, maxfraglen
);
1315 * Put the packet on the pending queue.
1317 __skb_queue_tail(&sk
->sk_write_queue
, skb
);
1324 if (skb_append_pagefrags(skb
, page
, offset
, len
)) {
1329 if (skb
->ip_summed
== CHECKSUM_NONE
) {
1331 csum
= csum_page(page
, offset
, len
);
1332 skb
->csum
= csum_block_add(skb
->csum
, csum
, skb
->len
);
1336 skb
->data_len
+= len
;
1337 skb
->truesize
+= len
;
1338 atomic_add(len
, &sk
->sk_wmem_alloc
);
1345 cork
->length
-= size
;
1346 IP_INC_STATS(sock_net(sk
), IPSTATS_MIB_OUTDISCARDS
);
1350 static void ip_cork_release(struct inet_cork
*cork
)
1352 cork
->flags
&= ~IPCORK_OPT
;
1355 dst_release(cork
->dst
);
1360 * Combined all pending IP fragments on the socket as one IP datagram
1361 * and push them out.
1363 struct sk_buff
*__ip_make_skb(struct sock
*sk
,
1365 struct sk_buff_head
*queue
,
1366 struct inet_cork
*cork
)
1368 struct sk_buff
*skb
, *tmp_skb
;
1369 struct sk_buff
**tail_skb
;
1370 struct inet_sock
*inet
= inet_sk(sk
);
1371 struct net
*net
= sock_net(sk
);
1372 struct ip_options
*opt
= NULL
;
1373 struct rtable
*rt
= (struct rtable
*)cork
->dst
;
1378 skb
= __skb_dequeue(queue
);
1381 tail_skb
= &(skb_shinfo(skb
)->frag_list
);
1383 /* move skb->data to ip header from ext header */
1384 if (skb
->data
< skb_network_header(skb
))
1385 __skb_pull(skb
, skb_network_offset(skb
));
1386 while ((tmp_skb
= __skb_dequeue(queue
)) != NULL
) {
1387 __skb_pull(tmp_skb
, skb_network_header_len(skb
));
1388 *tail_skb
= tmp_skb
;
1389 tail_skb
= &(tmp_skb
->next
);
1390 skb
->len
+= tmp_skb
->len
;
1391 skb
->data_len
+= tmp_skb
->len
;
1392 skb
->truesize
+= tmp_skb
->truesize
;
1393 tmp_skb
->destructor
= NULL
;
1397 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow
1398 * to fragment the frame generated here. No matter, what transforms
1399 * how transforms change size of the packet, it will come out.
1401 skb
->ignore_df
= ip_sk_ignore_df(sk
);
1403 /* DF bit is set when we want to see DF on outgoing frames.
1404 * If ignore_df is set too, we still allow to fragment this frame
1406 if (inet
->pmtudisc
== IP_PMTUDISC_DO
||
1407 inet
->pmtudisc
== IP_PMTUDISC_PROBE
||
1408 (skb
->len
<= dst_mtu(&rt
->dst
) &&
1409 ip_dont_fragment(sk
, &rt
->dst
)))
1412 if (cork
->flags
& IPCORK_OPT
)
1417 else if (rt
->rt_type
== RTN_MULTICAST
)
1420 ttl
= ip_select_ttl(inet
, &rt
->dst
);
1425 iph
->tos
= (cork
->tos
!= -1) ? cork
->tos
: inet
->tos
;
1428 iph
->protocol
= sk
->sk_protocol
;
1429 ip_copy_addrs(iph
, fl4
);
1430 ip_select_ident(net
, skb
, sk
);
1433 iph
->ihl
+= opt
->optlen
>>2;
1434 ip_options_build(skb
, opt
, cork
->addr
, rt
, 0);
1437 skb
->priority
= (cork
->tos
!= -1) ? cork
->priority
: sk
->sk_priority
;
1438 skb
->mark
= sk
->sk_mark
;
1440 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec
1444 skb_dst_set(skb
, &rt
->dst
);
1446 if (iph
->protocol
== IPPROTO_ICMP
)
1447 icmp_out_count(net
, ((struct icmphdr
*)
1448 skb_transport_header(skb
))->type
);
1450 ip_cork_release(cork
);
1455 int ip_send_skb(struct net
*net
, struct sk_buff
*skb
)
1459 err
= ip_local_out(net
, skb
->sk
, skb
);
1462 err
= net_xmit_errno(err
);
1464 IP_INC_STATS(net
, IPSTATS_MIB_OUTDISCARDS
);
1470 int ip_push_pending_frames(struct sock
*sk
, struct flowi4
*fl4
)
1472 struct sk_buff
*skb
;
1474 skb
= ip_finish_skb(sk
, fl4
);
1478 /* Netfilter gets whole the not fragmented skb. */
1479 return ip_send_skb(sock_net(sk
), skb
);
1483 * Throw away all pending data on the socket.
1485 static void __ip_flush_pending_frames(struct sock
*sk
,
1486 struct sk_buff_head
*queue
,
1487 struct inet_cork
*cork
)
1489 struct sk_buff
*skb
;
1491 while ((skb
= __skb_dequeue_tail(queue
)) != NULL
)
1494 ip_cork_release(cork
);
1497 void ip_flush_pending_frames(struct sock
*sk
)
1499 __ip_flush_pending_frames(sk
, &sk
->sk_write_queue
, &inet_sk(sk
)->cork
.base
);
1502 struct sk_buff
*ip_make_skb(struct sock
*sk
,
1504 int getfrag(void *from
, char *to
, int offset
,
1505 int len
, int odd
, struct sk_buff
*skb
),
1506 void *from
, int length
, int transhdrlen
,
1507 struct ipcm_cookie
*ipc
, struct rtable
**rtp
,
1510 struct inet_cork cork
;
1511 struct sk_buff_head queue
;
1514 if (flags
& MSG_PROBE
)
1517 __skb_queue_head_init(&queue
);
1522 err
= ip_setup_cork(sk
, &cork
, ipc
, rtp
);
1524 return ERR_PTR(err
);
1526 err
= __ip_append_data(sk
, fl4
, &queue
, &cork
,
1527 ¤t
->task_frag
, getfrag
,
1528 from
, length
, transhdrlen
, flags
);
1530 __ip_flush_pending_frames(sk
, &queue
, &cork
);
1531 return ERR_PTR(err
);
1534 return __ip_make_skb(sk
, fl4
, &queue
, &cork
);
1538 * Fetch data from kernel space and fill in checksum if needed.
1540 static int ip_reply_glue_bits(void *dptr
, char *to
, int offset
,
1541 int len
, int odd
, struct sk_buff
*skb
)
1545 csum
= csum_partial_copy_nocheck(dptr
+offset
, to
, len
, 0);
1546 skb
->csum
= csum_block_add(skb
->csum
, csum
, odd
);
1551 * Generic function to send a packet as reply to another packet.
1552 * Used to send some TCP resets/acks so far.
1554 void ip_send_unicast_reply(struct sock
*sk
, struct sk_buff
*skb
,
1555 const struct ip_options
*sopt
,
1556 __be32 daddr
, __be32 saddr
,
1557 const struct ip_reply_arg
*arg
,
1560 struct ip_options_data replyopts
;
1561 struct ipcm_cookie ipc
;
1563 struct rtable
*rt
= skb_rtable(skb
);
1564 struct net
*net
= sock_net(sk
);
1565 struct sk_buff
*nskb
;
1569 if (__ip_options_echo(&replyopts
.opt
.opt
, skb
, sopt
))
1578 if (replyopts
.opt
.opt
.optlen
) {
1579 ipc
.opt
= &replyopts
.opt
;
1581 if (replyopts
.opt
.opt
.srr
)
1582 daddr
= replyopts
.opt
.opt
.faddr
;
1585 oif
= arg
->bound_dev_if
;
1586 if (!oif
&& netif_index_is_l3_master(net
, skb
->skb_iif
))
1589 flowi4_init_output(&fl4
, oif
,
1590 IP4_REPLY_MARK(net
, skb
->mark
),
1592 RT_SCOPE_UNIVERSE
, ip_hdr(skb
)->protocol
,
1593 ip_reply_arg_flowi_flags(arg
),
1595 tcp_hdr(skb
)->source
, tcp_hdr(skb
)->dest
,
1597 security_skb_classify_flow(skb
, flowi4_to_flowi(&fl4
));
1598 rt
= ip_route_output_key(net
, &fl4
);
1602 inet_sk(sk
)->tos
= arg
->tos
;
1604 sk
->sk_priority
= skb
->priority
;
1605 sk
->sk_protocol
= ip_hdr(skb
)->protocol
;
1606 sk
->sk_bound_dev_if
= arg
->bound_dev_if
;
1607 sk
->sk_sndbuf
= sysctl_wmem_default
;
1608 err
= ip_append_data(sk
, &fl4
, ip_reply_glue_bits
, arg
->iov
->iov_base
,
1609 len
, 0, &ipc
, &rt
, MSG_DONTWAIT
);
1610 if (unlikely(err
)) {
1611 ip_flush_pending_frames(sk
);
1615 nskb
= skb_peek(&sk
->sk_write_queue
);
1617 if (arg
->csumoffset
>= 0)
1618 *((__sum16
*)skb_transport_header(nskb
) +
1619 arg
->csumoffset
) = csum_fold(csum_add(nskb
->csum
,
1621 nskb
->ip_summed
= CHECKSUM_NONE
;
1622 ip_push_pending_frames(sk
, &fl4
);
1628 void __init
ip_init(void)
1633 #if defined(CONFIG_IP_MULTICAST)