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 <linux/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/bpf-cgroup.h>
78 #include <linux/igmp.h>
79 #include <linux/netfilter_ipv4.h>
80 #include <linux/netfilter_bridge.h>
81 #include <linux/netlink.h>
82 #include <linux/tcp.h>
85 ip_fragment(struct net
*net
, struct sock
*sk
, struct sk_buff
*skb
,
87 int (*output
)(struct net
*, struct sock
*, struct sk_buff
*));
89 /* Generate a checksum for an outgoing IP datagram. */
90 void ip_send_check(struct iphdr
*iph
)
93 iph
->check
= ip_fast_csum((unsigned char *)iph
, iph
->ihl
);
95 EXPORT_SYMBOL(ip_send_check
);
97 int __ip_local_out(struct net
*net
, struct sock
*sk
, struct sk_buff
*skb
)
99 struct iphdr
*iph
= ip_hdr(skb
);
101 iph
->tot_len
= htons(skb
->len
);
104 /* if egress device is enslaved to an L3 master device pass the
105 * skb to its handler for processing
107 skb
= l3mdev_ip_out(sk
, skb
);
111 skb
->protocol
= htons(ETH_P_IP
);
113 return nf_hook(NFPROTO_IPV4
, NF_INET_LOCAL_OUT
,
114 net
, sk
, skb
, NULL
, skb_dst(skb
)->dev
,
118 int ip_local_out(struct net
*net
, struct sock
*sk
, struct sk_buff
*skb
)
122 err
= __ip_local_out(net
, sk
, skb
);
123 if (likely(err
== 1))
124 err
= dst_output(net
, sk
, skb
);
128 EXPORT_SYMBOL_GPL(ip_local_out
);
130 static inline int ip_select_ttl(struct inet_sock
*inet
, struct dst_entry
*dst
)
132 int ttl
= inet
->uc_ttl
;
135 ttl
= ip4_dst_hoplimit(dst
);
140 * Add an ip header to a skbuff and send it out.
143 int ip_build_and_send_pkt(struct sk_buff
*skb
, const struct sock
*sk
,
144 __be32 saddr
, __be32 daddr
, struct ip_options_rcu
*opt
)
146 struct inet_sock
*inet
= inet_sk(sk
);
147 struct rtable
*rt
= skb_rtable(skb
);
148 struct net
*net
= sock_net(sk
);
151 /* Build the IP header. */
152 skb_push(skb
, sizeof(struct iphdr
) + (opt
? opt
->opt
.optlen
: 0));
153 skb_reset_network_header(skb
);
157 iph
->tos
= inet
->tos
;
158 iph
->ttl
= ip_select_ttl(inet
, &rt
->dst
);
159 iph
->daddr
= (opt
&& opt
->opt
.srr
? opt
->opt
.faddr
: daddr
);
161 iph
->protocol
= sk
->sk_protocol
;
162 if (ip_dont_fragment(sk
, &rt
->dst
)) {
163 iph
->frag_off
= htons(IP_DF
);
167 __ip_select_ident(net
, iph
, 1);
170 if (opt
&& opt
->opt
.optlen
) {
171 iph
->ihl
+= opt
->opt
.optlen
>>2;
172 ip_options_build(skb
, &opt
->opt
, daddr
, rt
, 0);
175 skb
->priority
= sk
->sk_priority
;
177 skb
->mark
= sk
->sk_mark
;
180 return ip_local_out(net
, skb
->sk
, skb
);
182 EXPORT_SYMBOL_GPL(ip_build_and_send_pkt
);
184 static int ip_finish_output2(struct net
*net
, struct sock
*sk
, struct sk_buff
*skb
)
186 struct dst_entry
*dst
= skb_dst(skb
);
187 struct rtable
*rt
= (struct rtable
*)dst
;
188 struct net_device
*dev
= dst
->dev
;
189 unsigned int hh_len
= LL_RESERVED_SPACE(dev
);
190 struct neighbour
*neigh
;
193 if (rt
->rt_type
== RTN_MULTICAST
) {
194 IP_UPD_PO_STATS(net
, IPSTATS_MIB_OUTMCAST
, skb
->len
);
195 } else if (rt
->rt_type
== RTN_BROADCAST
)
196 IP_UPD_PO_STATS(net
, IPSTATS_MIB_OUTBCAST
, skb
->len
);
198 /* Be paranoid, rather than too clever. */
199 if (unlikely(skb_headroom(skb
) < hh_len
&& dev
->header_ops
)) {
200 struct sk_buff
*skb2
;
202 skb2
= skb_realloc_headroom(skb
, LL_RESERVED_SPACE(dev
));
208 skb_set_owner_w(skb2
, skb
->sk
);
213 if (lwtunnel_xmit_redirect(dst
->lwtstate
)) {
214 int res
= lwtunnel_xmit(skb
);
216 if (res
< 0 || res
== LWTUNNEL_XMIT_DONE
)
221 nexthop
= (__force u32
) rt_nexthop(rt
, ip_hdr(skb
)->daddr
);
222 neigh
= __ipv4_neigh_lookup_noref(dev
, nexthop
);
223 if (unlikely(!neigh
))
224 neigh
= __neigh_create(&arp_tbl
, &nexthop
, dev
, false);
225 if (!IS_ERR(neigh
)) {
228 sock_confirm_neigh(skb
, neigh
);
229 res
= neigh_output(neigh
, skb
);
231 rcu_read_unlock_bh();
234 rcu_read_unlock_bh();
236 net_dbg_ratelimited("%s: No header cache and no neighbour!\n",
242 static int ip_finish_output_gso(struct net
*net
, struct sock
*sk
,
243 struct sk_buff
*skb
, unsigned int mtu
)
245 netdev_features_t features
;
246 struct sk_buff
*segs
;
249 /* common case: seglen is <= mtu
251 if (skb_gso_validate_network_len(skb
, mtu
))
252 return ip_finish_output2(net
, sk
, skb
);
254 /* Slowpath - GSO segment length exceeds the egress MTU.
256 * This can happen in several cases:
257 * - Forwarding of a TCP GRO skb, when DF flag is not set.
258 * - Forwarding of an skb that arrived on a virtualization interface
259 * (virtio-net/vhost/tap) with TSO/GSO size set by other network
261 * - Local GSO skb transmitted on an NETIF_F_TSO tunnel stacked over an
262 * interface with a smaller MTU.
263 * - Arriving GRO skb (or GSO skb in a virtualized environment) that is
264 * bridged to a NETIF_F_TSO tunnel stacked over an interface with an
267 features
= netif_skb_features(skb
);
268 BUILD_BUG_ON(sizeof(*IPCB(skb
)) > SKB_SGO_CB_OFFSET
);
269 segs
= skb_gso_segment(skb
, features
& ~NETIF_F_GSO_MASK
);
270 if (IS_ERR_OR_NULL(segs
)) {
278 struct sk_buff
*nskb
= segs
->next
;
282 err
= ip_fragment(net
, sk
, segs
, mtu
, ip_finish_output2
);
292 static int ip_finish_output(struct net
*net
, struct sock
*sk
, struct sk_buff
*skb
)
297 ret
= BPF_CGROUP_RUN_PROG_INET_EGRESS(sk
, skb
);
303 #if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
304 /* Policy lookup after SNAT yielded a new policy */
305 if (skb_dst(skb
)->xfrm
) {
306 IPCB(skb
)->flags
|= IPSKB_REROUTED
;
307 return dst_output(net
, sk
, skb
);
310 mtu
= ip_skb_dst_mtu(sk
, skb
);
312 return ip_finish_output_gso(net
, sk
, skb
, mtu
);
314 if (skb
->len
> mtu
|| (IPCB(skb
)->flags
& IPSKB_FRAG_PMTU
))
315 return ip_fragment(net
, sk
, skb
, mtu
, ip_finish_output2
);
317 return ip_finish_output2(net
, sk
, skb
);
320 static int ip_mc_finish_output(struct net
*net
, struct sock
*sk
,
325 ret
= BPF_CGROUP_RUN_PROG_INET_EGRESS(sk
, skb
);
331 return dev_loopback_xmit(net
, sk
, skb
);
334 int ip_mc_output(struct net
*net
, struct sock
*sk
, struct sk_buff
*skb
)
336 struct rtable
*rt
= skb_rtable(skb
);
337 struct net_device
*dev
= rt
->dst
.dev
;
340 * If the indicated interface is up and running, send the packet.
342 IP_UPD_PO_STATS(net
, IPSTATS_MIB_OUT
, skb
->len
);
345 skb
->protocol
= htons(ETH_P_IP
);
348 * Multicasts are looped back for other local users
351 if (rt
->rt_flags
&RTCF_MULTICAST
) {
353 #ifdef CONFIG_IP_MROUTE
354 /* Small optimization: do not loopback not local frames,
355 which returned after forwarding; they will be dropped
356 by ip_mr_input in any case.
357 Note, that local frames are looped back to be delivered
360 This check is duplicated in ip_mr_input at the moment.
363 ((rt
->rt_flags
& RTCF_LOCAL
) ||
364 !(IPCB(skb
)->flags
& IPSKB_FORWARDED
))
367 struct sk_buff
*newskb
= skb_clone(skb
, GFP_ATOMIC
);
369 NF_HOOK(NFPROTO_IPV4
, NF_INET_POST_ROUTING
,
370 net
, sk
, newskb
, NULL
, newskb
->dev
,
371 ip_mc_finish_output
);
374 /* Multicasts with ttl 0 must not go beyond the host */
376 if (ip_hdr(skb
)->ttl
== 0) {
382 if (rt
->rt_flags
&RTCF_BROADCAST
) {
383 struct sk_buff
*newskb
= skb_clone(skb
, GFP_ATOMIC
);
385 NF_HOOK(NFPROTO_IPV4
, NF_INET_POST_ROUTING
,
386 net
, sk
, newskb
, NULL
, newskb
->dev
,
387 ip_mc_finish_output
);
390 return NF_HOOK_COND(NFPROTO_IPV4
, NF_INET_POST_ROUTING
,
391 net
, sk
, skb
, NULL
, skb
->dev
,
393 !(IPCB(skb
)->flags
& IPSKB_REROUTED
));
396 int ip_output(struct net
*net
, struct sock
*sk
, struct sk_buff
*skb
)
398 struct net_device
*dev
= skb_dst(skb
)->dev
;
400 IP_UPD_PO_STATS(net
, IPSTATS_MIB_OUT
, skb
->len
);
403 skb
->protocol
= htons(ETH_P_IP
);
405 return NF_HOOK_COND(NFPROTO_IPV4
, NF_INET_POST_ROUTING
,
406 net
, sk
, skb
, NULL
, dev
,
408 !(IPCB(skb
)->flags
& IPSKB_REROUTED
));
412 * copy saddr and daddr, possibly using 64bit load/stores
414 * iph->saddr = fl4->saddr;
415 * iph->daddr = fl4->daddr;
417 static void ip_copy_addrs(struct iphdr
*iph
, const struct flowi4
*fl4
)
419 BUILD_BUG_ON(offsetof(typeof(*fl4
), daddr
) !=
420 offsetof(typeof(*fl4
), saddr
) + sizeof(fl4
->saddr
));
421 memcpy(&iph
->saddr
, &fl4
->saddr
,
422 sizeof(fl4
->saddr
) + sizeof(fl4
->daddr
));
425 /* Note: skb->sk can be different from sk, in case of tunnels */
426 int __ip_queue_xmit(struct sock
*sk
, struct sk_buff
*skb
, struct flowi
*fl
,
429 struct inet_sock
*inet
= inet_sk(sk
);
430 struct net
*net
= sock_net(sk
);
431 struct ip_options_rcu
*inet_opt
;
437 /* Skip all of this if the packet is already routed,
438 * f.e. by something like SCTP.
441 inet_opt
= rcu_dereference(inet
->inet_opt
);
443 rt
= skb_rtable(skb
);
447 /* Make sure we can route this packet. */
448 rt
= (struct rtable
*)__sk_dst_check(sk
, 0);
452 /* Use correct destination address if we have options. */
453 daddr
= inet
->inet_daddr
;
454 if (inet_opt
&& inet_opt
->opt
.srr
)
455 daddr
= inet_opt
->opt
.faddr
;
457 /* If this fails, retransmit mechanism of transport layer will
458 * keep trying until route appears or the connection times
461 rt
= ip_route_output_ports(net
, fl4
, sk
,
462 daddr
, inet
->inet_saddr
,
466 RT_CONN_FLAGS_TOS(sk
, tos
),
467 sk
->sk_bound_dev_if
);
470 sk_setup_caps(sk
, &rt
->dst
);
472 skb_dst_set_noref(skb
, &rt
->dst
);
475 if (inet_opt
&& inet_opt
->opt
.is_strictroute
&& rt
->rt_uses_gateway
)
478 /* OK, we know where to send it, allocate and build IP header. */
479 skb_push(skb
, sizeof(struct iphdr
) + (inet_opt
? inet_opt
->opt
.optlen
: 0));
480 skb_reset_network_header(skb
);
482 *((__be16
*)iph
) = htons((4 << 12) | (5 << 8) | (tos
& 0xff));
483 if (ip_dont_fragment(sk
, &rt
->dst
) && !skb
->ignore_df
)
484 iph
->frag_off
= htons(IP_DF
);
487 iph
->ttl
= ip_select_ttl(inet
, &rt
->dst
);
488 iph
->protocol
= sk
->sk_protocol
;
489 ip_copy_addrs(iph
, fl4
);
491 /* Transport layer set skb->h.foo itself. */
493 if (inet_opt
&& inet_opt
->opt
.optlen
) {
494 iph
->ihl
+= inet_opt
->opt
.optlen
>> 2;
495 ip_options_build(skb
, &inet_opt
->opt
, inet
->inet_daddr
, rt
, 0);
498 ip_select_ident_segs(net
, skb
, sk
,
499 skb_shinfo(skb
)->gso_segs
?: 1);
501 /* TODO : should we use skb->sk here instead of sk ? */
502 skb
->priority
= sk
->sk_priority
;
503 skb
->mark
= sk
->sk_mark
;
505 res
= ip_local_out(net
, sk
, skb
);
511 IP_INC_STATS(net
, IPSTATS_MIB_OUTNOROUTES
);
513 return -EHOSTUNREACH
;
515 EXPORT_SYMBOL(__ip_queue_xmit
);
517 static void ip_copy_metadata(struct sk_buff
*to
, struct sk_buff
*from
)
519 to
->pkt_type
= from
->pkt_type
;
520 to
->priority
= from
->priority
;
521 to
->protocol
= from
->protocol
;
523 skb_dst_copy(to
, from
);
525 to
->mark
= from
->mark
;
527 /* Copy the flags to each fragment. */
528 IPCB(to
)->flags
= IPCB(from
)->flags
;
530 #ifdef CONFIG_NET_SCHED
531 to
->tc_index
= from
->tc_index
;
534 #if IS_ENABLED(CONFIG_IP_VS)
535 to
->ipvs_property
= from
->ipvs_property
;
537 skb_copy_secmark(to
, from
);
540 static int ip_fragment(struct net
*net
, struct sock
*sk
, struct sk_buff
*skb
,
542 int (*output
)(struct net
*, struct sock
*, struct sk_buff
*))
544 struct iphdr
*iph
= ip_hdr(skb
);
546 if ((iph
->frag_off
& htons(IP_DF
)) == 0)
547 return ip_do_fragment(net
, sk
, skb
, output
);
549 if (unlikely(!skb
->ignore_df
||
550 (IPCB(skb
)->frag_max_size
&&
551 IPCB(skb
)->frag_max_size
> mtu
))) {
552 IP_INC_STATS(net
, IPSTATS_MIB_FRAGFAILS
);
553 icmp_send(skb
, ICMP_DEST_UNREACH
, ICMP_FRAG_NEEDED
,
559 return ip_do_fragment(net
, sk
, skb
, output
);
563 * This IP datagram is too large to be sent in one piece. Break it up into
564 * smaller pieces (each of size equal to IP header plus
565 * a block of the data of the original IP data part) that will yet fit in a
566 * single device frame, and queue such a frame for sending.
569 int ip_do_fragment(struct net
*net
, struct sock
*sk
, struct sk_buff
*skb
,
570 int (*output
)(struct net
*, struct sock
*, struct sk_buff
*))
574 struct sk_buff
*skb2
;
575 unsigned int mtu
, hlen
, left
, len
, ll_rs
;
577 __be16 not_last_frag
;
578 struct rtable
*rt
= skb_rtable(skb
);
581 /* for offloaded checksums cleanup checksum before fragmentation */
582 if (skb
->ip_summed
== CHECKSUM_PARTIAL
&&
583 (err
= skb_checksum_help(skb
)))
587 * Point into the IP datagram header.
592 mtu
= ip_skb_dst_mtu(sk
, skb
);
593 if (IPCB(skb
)->frag_max_size
&& IPCB(skb
)->frag_max_size
< mtu
)
594 mtu
= IPCB(skb
)->frag_max_size
;
597 * Setup starting values.
601 mtu
= mtu
- hlen
; /* Size of data space */
602 IPCB(skb
)->flags
|= IPSKB_FRAG_COMPLETE
;
603 ll_rs
= LL_RESERVED_SPACE(rt
->dst
.dev
);
605 /* When frag_list is given, use it. First, check its validity:
606 * some transformers could create wrong frag_list or break existing
607 * one, it is not prohibited. In this case fall back to copying.
609 * LATER: this step can be merged to real generation of fragments,
610 * we can switch to copy when see the first bad fragment.
612 if (skb_has_frag_list(skb
)) {
613 struct sk_buff
*frag
, *frag2
;
614 unsigned int first_len
= skb_pagelen(skb
);
616 if (first_len
- hlen
> mtu
||
617 ((first_len
- hlen
) & 7) ||
618 ip_is_fragment(iph
) ||
620 skb_headroom(skb
) < ll_rs
)
623 skb_walk_frags(skb
, frag
) {
624 /* Correct geometry. */
625 if (frag
->len
> mtu
||
626 ((frag
->len
& 7) && frag
->next
) ||
627 skb_headroom(frag
) < hlen
+ ll_rs
)
628 goto slow_path_clean
;
630 /* Partially cloned skb? */
631 if (skb_shared(frag
))
632 goto slow_path_clean
;
637 frag
->destructor
= sock_wfree
;
639 skb
->truesize
-= frag
->truesize
;
642 /* Everything is OK. Generate! */
646 frag
= skb_shinfo(skb
)->frag_list
;
647 skb_frag_list_init(skb
);
648 skb
->data_len
= first_len
- skb_headlen(skb
);
649 skb
->len
= first_len
;
650 iph
->tot_len
= htons(first_len
);
651 iph
->frag_off
= htons(IP_MF
);
655 /* Prepare header of the next frame,
656 * before previous one went down. */
658 frag
->ip_summed
= CHECKSUM_NONE
;
659 skb_reset_transport_header(frag
);
660 __skb_push(frag
, hlen
);
661 skb_reset_network_header(frag
);
662 memcpy(skb_network_header(frag
), iph
, hlen
);
664 iph
->tot_len
= htons(frag
->len
);
665 ip_copy_metadata(frag
, skb
);
667 ip_options_fragment(frag
);
668 offset
+= skb
->len
- hlen
;
669 iph
->frag_off
= htons(offset
>>3);
671 iph
->frag_off
|= htons(IP_MF
);
672 /* Ready, complete checksum */
676 err
= output(net
, sk
, skb
);
679 IP_INC_STATS(net
, IPSTATS_MIB_FRAGCREATES
);
689 IP_INC_STATS(net
, IPSTATS_MIB_FRAGOKS
);
698 IP_INC_STATS(net
, IPSTATS_MIB_FRAGFAILS
);
702 skb_walk_frags(skb
, frag2
) {
706 frag2
->destructor
= NULL
;
707 skb
->truesize
+= frag2
->truesize
;
714 left
= skb
->len
- hlen
; /* Space per frame */
715 ptr
= hlen
; /* Where to start from */
718 * Fragment the datagram.
721 offset
= (ntohs(iph
->frag_off
) & IP_OFFSET
) << 3;
722 not_last_frag
= iph
->frag_off
& htons(IP_MF
);
725 * Keep copying data until we run out.
730 /* IF: it doesn't fit, use 'mtu' - the data space left */
733 /* IF: we are not sending up to and including the packet end
734 then align the next start on an eight byte boundary */
739 /* Allocate buffer */
740 skb2
= alloc_skb(len
+ hlen
+ ll_rs
, GFP_ATOMIC
);
747 * Set up data on packet
750 ip_copy_metadata(skb2
, skb
);
751 skb_reserve(skb2
, ll_rs
);
752 skb_put(skb2
, len
+ hlen
);
753 skb_reset_network_header(skb2
);
754 skb2
->transport_header
= skb2
->network_header
+ hlen
;
757 * Charge the memory for the fragment to any owner
762 skb_set_owner_w(skb2
, skb
->sk
);
765 * Copy the packet header into the new buffer.
768 skb_copy_from_linear_data(skb
, skb_network_header(skb2
), hlen
);
771 * Copy a block of the IP datagram.
773 if (skb_copy_bits(skb
, ptr
, skb_transport_header(skb2
), len
))
778 * Fill in the new header fields.
781 iph
->frag_off
= htons((offset
>> 3));
783 if (IPCB(skb
)->flags
& IPSKB_FRAG_PMTU
)
784 iph
->frag_off
|= htons(IP_DF
);
786 /* ANK: dirty, but effective trick. Upgrade options only if
787 * the segment to be fragmented was THE FIRST (otherwise,
788 * options are already fixed) and make it ONCE
789 * on the initial skb, so that all the following fragments
790 * will inherit fixed options.
793 ip_options_fragment(skb
);
796 * Added AC : If we are fragmenting a fragment that's not the
797 * last fragment then keep MF on each bit
799 if (left
> 0 || not_last_frag
)
800 iph
->frag_off
|= htons(IP_MF
);
805 * Put this fragment into the sending queue.
807 iph
->tot_len
= htons(len
+ hlen
);
811 err
= output(net
, sk
, skb2
);
815 IP_INC_STATS(net
, IPSTATS_MIB_FRAGCREATES
);
818 IP_INC_STATS(net
, IPSTATS_MIB_FRAGOKS
);
823 IP_INC_STATS(net
, IPSTATS_MIB_FRAGFAILS
);
826 EXPORT_SYMBOL(ip_do_fragment
);
829 ip_generic_getfrag(void *from
, char *to
, int offset
, int len
, int odd
, struct sk_buff
*skb
)
831 struct msghdr
*msg
= from
;
833 if (skb
->ip_summed
== CHECKSUM_PARTIAL
) {
834 if (!copy_from_iter_full(to
, len
, &msg
->msg_iter
))
838 if (!csum_and_copy_from_iter_full(to
, len
, &csum
, &msg
->msg_iter
))
840 skb
->csum
= csum_block_add(skb
->csum
, csum
, odd
);
844 EXPORT_SYMBOL(ip_generic_getfrag
);
847 csum_page(struct page
*page
, int offset
, int copy
)
852 csum
= csum_partial(kaddr
+ offset
, copy
, 0);
857 static int __ip_append_data(struct sock
*sk
,
859 struct sk_buff_head
*queue
,
860 struct inet_cork
*cork
,
861 struct page_frag
*pfrag
,
862 int getfrag(void *from
, char *to
, int offset
,
863 int len
, int odd
, struct sk_buff
*skb
),
864 void *from
, int length
, int transhdrlen
,
867 struct inet_sock
*inet
= inet_sk(sk
);
870 struct ip_options
*opt
= cork
->opt
;
877 unsigned int maxfraglen
, fragheaderlen
, maxnonfragsize
;
878 int csummode
= CHECKSUM_NONE
;
879 struct rtable
*rt
= (struct rtable
*)cork
->dst
;
880 unsigned int wmem_alloc_delta
= 0;
884 skb
= skb_peek_tail(queue
);
886 exthdrlen
= !skb
? rt
->dst
.header_len
: 0;
887 mtu
= cork
->gso_size
? IP_MAX_MTU
: cork
->fragsize
;
888 paged
= !!cork
->gso_size
;
890 if (cork
->tx_flags
& SKBTX_ANY_SW_TSTAMP
&&
891 sk
->sk_tsflags
& SOF_TIMESTAMPING_OPT_ID
)
892 tskey
= sk
->sk_tskey
++;
894 hh_len
= LL_RESERVED_SPACE(rt
->dst
.dev
);
896 fragheaderlen
= sizeof(struct iphdr
) + (opt
? opt
->optlen
: 0);
897 maxfraglen
= ((mtu
- fragheaderlen
) & ~7) + fragheaderlen
;
898 maxnonfragsize
= ip_sk_ignore_df(sk
) ? 0xFFFF : mtu
;
900 if (cork
->length
+ length
> maxnonfragsize
- fragheaderlen
) {
901 ip_local_error(sk
, EMSGSIZE
, fl4
->daddr
, inet
->inet_dport
,
902 mtu
- (opt
? opt
->optlen
: 0));
907 * transhdrlen > 0 means that this is the first fragment and we wish
908 * it won't be fragmented in the future.
911 length
+ fragheaderlen
<= mtu
&&
912 rt
->dst
.dev
->features
& (NETIF_F_HW_CSUM
| NETIF_F_IP_CSUM
) &&
913 (!(flags
& MSG_MORE
) || cork
->gso_size
) &&
914 (!exthdrlen
|| (rt
->dst
.dev
->features
& NETIF_F_HW_ESP_TX_CSUM
)))
915 csummode
= CHECKSUM_PARTIAL
;
917 cork
->length
+= length
;
919 /* So, what's going on in the loop below?
921 * We use calculated fragment length to generate chained skb,
922 * each of segments is IP fragment ready for sending to network after
923 * adding appropriate IP header.
930 /* Check if the remaining data fits into current packet. */
931 copy
= mtu
- skb
->len
;
933 copy
= maxfraglen
- skb
->len
;
936 unsigned int datalen
;
937 unsigned int fraglen
;
938 unsigned int fraggap
;
939 unsigned int alloclen
;
940 unsigned int pagedlen
= 0;
941 struct sk_buff
*skb_prev
;
945 fraggap
= skb_prev
->len
- maxfraglen
;
950 * If remaining data exceeds the mtu,
951 * we know we need more fragment(s).
953 datalen
= length
+ fraggap
;
954 if (datalen
> mtu
- fragheaderlen
)
955 datalen
= maxfraglen
- fragheaderlen
;
956 fraglen
= datalen
+ fragheaderlen
;
958 if ((flags
& MSG_MORE
) &&
959 !(rt
->dst
.dev
->features
&NETIF_F_SG
))
964 alloclen
= min_t(int, fraglen
, MAX_HEADER
);
965 pagedlen
= fraglen
- alloclen
;
968 alloclen
+= exthdrlen
;
970 /* The last fragment gets additional space at tail.
971 * Note, with MSG_MORE we overallocate on fragments,
972 * because we have no idea what fragment will be
975 if (datalen
== length
+ fraggap
)
976 alloclen
+= rt
->dst
.trailer_len
;
979 skb
= sock_alloc_send_skb(sk
,
980 alloclen
+ hh_len
+ 15,
981 (flags
& MSG_DONTWAIT
), &err
);
984 if (refcount_read(&sk
->sk_wmem_alloc
) + wmem_alloc_delta
<=
986 skb
= alloc_skb(alloclen
+ hh_len
+ 15,
995 * Fill in the control structures
997 skb
->ip_summed
= csummode
;
999 skb_reserve(skb
, hh_len
);
1001 /* only the initial fragment is time stamped */
1002 skb_shinfo(skb
)->tx_flags
= cork
->tx_flags
;
1004 skb_shinfo(skb
)->tskey
= tskey
;
1008 * Find where to start putting bytes.
1010 data
= skb_put(skb
, fraglen
+ exthdrlen
- pagedlen
);
1011 skb_set_network_header(skb
, exthdrlen
);
1012 skb
->transport_header
= (skb
->network_header
+
1014 data
+= fragheaderlen
+ exthdrlen
;
1017 skb
->csum
= skb_copy_and_csum_bits(
1018 skb_prev
, maxfraglen
,
1019 data
+ transhdrlen
, fraggap
, 0);
1020 skb_prev
->csum
= csum_sub(skb_prev
->csum
,
1023 pskb_trim_unique(skb_prev
, maxfraglen
);
1026 copy
= datalen
- transhdrlen
- fraggap
- pagedlen
;
1027 if (copy
> 0 && getfrag(from
, data
+ transhdrlen
, offset
, copy
, fraggap
, skb
) < 0) {
1034 length
-= copy
+ transhdrlen
;
1037 csummode
= CHECKSUM_NONE
;
1039 if ((flags
& MSG_CONFIRM
) && !skb_prev
)
1040 skb_set_dst_pending_confirm(skb
, 1);
1043 * Put the packet on the pending queue.
1045 if (!skb
->destructor
) {
1046 skb
->destructor
= sock_wfree
;
1048 wmem_alloc_delta
+= skb
->truesize
;
1050 __skb_queue_tail(queue
, skb
);
1057 if (!(rt
->dst
.dev
->features
&NETIF_F_SG
) &&
1058 skb_tailroom(skb
) >= copy
) {
1062 if (getfrag(from
, skb_put(skb
, copy
),
1063 offset
, copy
, off
, skb
) < 0) {
1064 __skb_trim(skb
, off
);
1069 int i
= skb_shinfo(skb
)->nr_frags
;
1072 if (!sk_page_frag_refill(sk
, pfrag
))
1075 if (!skb_can_coalesce(skb
, i
, pfrag
->page
,
1078 if (i
== MAX_SKB_FRAGS
)
1081 __skb_fill_page_desc(skb
, i
, pfrag
->page
,
1083 skb_shinfo(skb
)->nr_frags
= ++i
;
1084 get_page(pfrag
->page
);
1086 copy
= min_t(int, copy
, pfrag
->size
- pfrag
->offset
);
1088 page_address(pfrag
->page
) + pfrag
->offset
,
1089 offset
, copy
, skb
->len
, skb
) < 0)
1092 pfrag
->offset
+= copy
;
1093 skb_frag_size_add(&skb_shinfo(skb
)->frags
[i
- 1], copy
);
1095 skb
->data_len
+= copy
;
1096 skb
->truesize
+= copy
;
1097 wmem_alloc_delta
+= copy
;
1103 if (wmem_alloc_delta
)
1104 refcount_add(wmem_alloc_delta
, &sk
->sk_wmem_alloc
);
1110 cork
->length
-= length
;
1111 IP_INC_STATS(sock_net(sk
), IPSTATS_MIB_OUTDISCARDS
);
1112 refcount_add(wmem_alloc_delta
, &sk
->sk_wmem_alloc
);
1116 static int ip_setup_cork(struct sock
*sk
, struct inet_cork
*cork
,
1117 struct ipcm_cookie
*ipc
, struct rtable
**rtp
)
1119 struct ip_options_rcu
*opt
;
1127 * setup for corking.
1132 cork
->opt
= kmalloc(sizeof(struct ip_options
) + 40,
1134 if (unlikely(!cork
->opt
))
1137 memcpy(cork
->opt
, &opt
->opt
, sizeof(struct ip_options
) + opt
->opt
.optlen
);
1138 cork
->flags
|= IPCORK_OPT
;
1139 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
;
1149 cork
->gso_size
= sk
->sk_type
== SOCK_DGRAM
&&
1150 sk
->sk_protocol
== IPPROTO_UDP
? ipc
->gso_size
: 0;
1151 cork
->dst
= &rt
->dst
;
1153 cork
->ttl
= ipc
->ttl
;
1154 cork
->tos
= ipc
->tos
;
1155 cork
->priority
= ipc
->priority
;
1156 cork
->tx_flags
= ipc
->tx_flags
;
1157 cork
->transmit_time
= ipc
->sockc
.transmit_time
;
1163 * ip_append_data() and ip_append_page() can make one large IP datagram
1164 * from many pieces of data. Each pieces will be holded on the socket
1165 * until ip_push_pending_frames() is called. Each piece can be a page
1168 * Not only UDP, other transport protocols - e.g. raw sockets - can use
1169 * this interface potentially.
1171 * LATER: length must be adjusted by pad at tail, when it is required.
1173 int ip_append_data(struct sock
*sk
, struct flowi4
*fl4
,
1174 int getfrag(void *from
, char *to
, int offset
, int len
,
1175 int odd
, struct sk_buff
*skb
),
1176 void *from
, int length
, int transhdrlen
,
1177 struct ipcm_cookie
*ipc
, struct rtable
**rtp
,
1180 struct inet_sock
*inet
= inet_sk(sk
);
1183 if (flags
&MSG_PROBE
)
1186 if (skb_queue_empty(&sk
->sk_write_queue
)) {
1187 err
= ip_setup_cork(sk
, &inet
->cork
.base
, ipc
, rtp
);
1194 return __ip_append_data(sk
, fl4
, &sk
->sk_write_queue
, &inet
->cork
.base
,
1195 sk_page_frag(sk
), getfrag
,
1196 from
, length
, transhdrlen
, flags
);
1199 ssize_t
ip_append_page(struct sock
*sk
, struct flowi4
*fl4
, struct page
*page
,
1200 int offset
, size_t size
, int flags
)
1202 struct inet_sock
*inet
= inet_sk(sk
);
1203 struct sk_buff
*skb
;
1205 struct ip_options
*opt
= NULL
;
1206 struct inet_cork
*cork
;
1211 unsigned int maxfraglen
, fragheaderlen
, fraggap
, maxnonfragsize
;
1216 if (flags
&MSG_PROBE
)
1219 if (skb_queue_empty(&sk
->sk_write_queue
))
1222 cork
= &inet
->cork
.base
;
1223 rt
= (struct rtable
*)cork
->dst
;
1224 if (cork
->flags
& IPCORK_OPT
)
1227 if (!(rt
->dst
.dev
->features
&NETIF_F_SG
))
1230 hh_len
= LL_RESERVED_SPACE(rt
->dst
.dev
);
1231 mtu
= cork
->gso_size
? IP_MAX_MTU
: cork
->fragsize
;
1233 fragheaderlen
= sizeof(struct iphdr
) + (opt
? opt
->optlen
: 0);
1234 maxfraglen
= ((mtu
- fragheaderlen
) & ~7) + fragheaderlen
;
1235 maxnonfragsize
= ip_sk_ignore_df(sk
) ? 0xFFFF : mtu
;
1237 if (cork
->length
+ size
> maxnonfragsize
- fragheaderlen
) {
1238 ip_local_error(sk
, EMSGSIZE
, fl4
->daddr
, inet
->inet_dport
,
1239 mtu
- (opt
? opt
->optlen
: 0));
1243 skb
= skb_peek_tail(&sk
->sk_write_queue
);
1247 cork
->length
+= size
;
1250 /* Check if the remaining data fits into current packet. */
1251 len
= mtu
- skb
->len
;
1253 len
= maxfraglen
- skb
->len
;
1256 struct sk_buff
*skb_prev
;
1260 fraggap
= skb_prev
->len
- maxfraglen
;
1262 alloclen
= fragheaderlen
+ hh_len
+ fraggap
+ 15;
1263 skb
= sock_wmalloc(sk
, alloclen
, 1, sk
->sk_allocation
);
1264 if (unlikely(!skb
)) {
1270 * Fill in the control structures
1272 skb
->ip_summed
= CHECKSUM_NONE
;
1274 skb_reserve(skb
, hh_len
);
1277 * Find where to start putting bytes.
1279 skb_put(skb
, fragheaderlen
+ fraggap
);
1280 skb_reset_network_header(skb
);
1281 skb
->transport_header
= (skb
->network_header
+
1284 skb
->csum
= skb_copy_and_csum_bits(skb_prev
,
1286 skb_transport_header(skb
),
1288 skb_prev
->csum
= csum_sub(skb_prev
->csum
,
1290 pskb_trim_unique(skb_prev
, maxfraglen
);
1294 * Put the packet on the pending queue.
1296 __skb_queue_tail(&sk
->sk_write_queue
, skb
);
1303 if (skb_append_pagefrags(skb
, page
, offset
, len
)) {
1308 if (skb
->ip_summed
== CHECKSUM_NONE
) {
1310 csum
= csum_page(page
, offset
, len
);
1311 skb
->csum
= csum_block_add(skb
->csum
, csum
, skb
->len
);
1315 skb
->data_len
+= len
;
1316 skb
->truesize
+= len
;
1317 refcount_add(len
, &sk
->sk_wmem_alloc
);
1324 cork
->length
-= size
;
1325 IP_INC_STATS(sock_net(sk
), IPSTATS_MIB_OUTDISCARDS
);
1329 static void ip_cork_release(struct inet_cork
*cork
)
1331 cork
->flags
&= ~IPCORK_OPT
;
1334 dst_release(cork
->dst
);
1339 * Combined all pending IP fragments on the socket as one IP datagram
1340 * and push them out.
1342 struct sk_buff
*__ip_make_skb(struct sock
*sk
,
1344 struct sk_buff_head
*queue
,
1345 struct inet_cork
*cork
)
1347 struct sk_buff
*skb
, *tmp_skb
;
1348 struct sk_buff
**tail_skb
;
1349 struct inet_sock
*inet
= inet_sk(sk
);
1350 struct net
*net
= sock_net(sk
);
1351 struct ip_options
*opt
= NULL
;
1352 struct rtable
*rt
= (struct rtable
*)cork
->dst
;
1357 skb
= __skb_dequeue(queue
);
1360 tail_skb
= &(skb_shinfo(skb
)->frag_list
);
1362 /* move skb->data to ip header from ext header */
1363 if (skb
->data
< skb_network_header(skb
))
1364 __skb_pull(skb
, skb_network_offset(skb
));
1365 while ((tmp_skb
= __skb_dequeue(queue
)) != NULL
) {
1366 __skb_pull(tmp_skb
, skb_network_header_len(skb
));
1367 *tail_skb
= tmp_skb
;
1368 tail_skb
= &(tmp_skb
->next
);
1369 skb
->len
+= tmp_skb
->len
;
1370 skb
->data_len
+= tmp_skb
->len
;
1371 skb
->truesize
+= tmp_skb
->truesize
;
1372 tmp_skb
->destructor
= NULL
;
1376 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow
1377 * to fragment the frame generated here. No matter, what transforms
1378 * how transforms change size of the packet, it will come out.
1380 skb
->ignore_df
= ip_sk_ignore_df(sk
);
1382 /* DF bit is set when we want to see DF on outgoing frames.
1383 * If ignore_df is set too, we still allow to fragment this frame
1385 if (inet
->pmtudisc
== IP_PMTUDISC_DO
||
1386 inet
->pmtudisc
== IP_PMTUDISC_PROBE
||
1387 (skb
->len
<= dst_mtu(&rt
->dst
) &&
1388 ip_dont_fragment(sk
, &rt
->dst
)))
1391 if (cork
->flags
& IPCORK_OPT
)
1396 else if (rt
->rt_type
== RTN_MULTICAST
)
1399 ttl
= ip_select_ttl(inet
, &rt
->dst
);
1404 iph
->tos
= (cork
->tos
!= -1) ? cork
->tos
: inet
->tos
;
1407 iph
->protocol
= sk
->sk_protocol
;
1408 ip_copy_addrs(iph
, fl4
);
1409 ip_select_ident(net
, skb
, sk
);
1412 iph
->ihl
+= opt
->optlen
>>2;
1413 ip_options_build(skb
, opt
, cork
->addr
, rt
, 0);
1416 skb
->priority
= (cork
->tos
!= -1) ? cork
->priority
: sk
->sk_priority
;
1417 skb
->mark
= sk
->sk_mark
;
1418 skb
->tstamp
= cork
->transmit_time
;
1420 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec
1424 skb_dst_set(skb
, &rt
->dst
);
1426 if (iph
->protocol
== IPPROTO_ICMP
)
1427 icmp_out_count(net
, ((struct icmphdr
*)
1428 skb_transport_header(skb
))->type
);
1430 ip_cork_release(cork
);
1435 int ip_send_skb(struct net
*net
, struct sk_buff
*skb
)
1439 err
= ip_local_out(net
, skb
->sk
, skb
);
1442 err
= net_xmit_errno(err
);
1444 IP_INC_STATS(net
, IPSTATS_MIB_OUTDISCARDS
);
1450 int ip_push_pending_frames(struct sock
*sk
, struct flowi4
*fl4
)
1452 struct sk_buff
*skb
;
1454 skb
= ip_finish_skb(sk
, fl4
);
1458 /* Netfilter gets whole the not fragmented skb. */
1459 return ip_send_skb(sock_net(sk
), skb
);
1463 * Throw away all pending data on the socket.
1465 static void __ip_flush_pending_frames(struct sock
*sk
,
1466 struct sk_buff_head
*queue
,
1467 struct inet_cork
*cork
)
1469 struct sk_buff
*skb
;
1471 while ((skb
= __skb_dequeue_tail(queue
)) != NULL
)
1474 ip_cork_release(cork
);
1477 void ip_flush_pending_frames(struct sock
*sk
)
1479 __ip_flush_pending_frames(sk
, &sk
->sk_write_queue
, &inet_sk(sk
)->cork
.base
);
1482 struct sk_buff
*ip_make_skb(struct sock
*sk
,
1484 int getfrag(void *from
, char *to
, int offset
,
1485 int len
, int odd
, struct sk_buff
*skb
),
1486 void *from
, int length
, int transhdrlen
,
1487 struct ipcm_cookie
*ipc
, struct rtable
**rtp
,
1488 struct inet_cork
*cork
, unsigned int flags
)
1490 struct sk_buff_head queue
;
1493 if (flags
& MSG_PROBE
)
1496 __skb_queue_head_init(&queue
);
1501 err
= ip_setup_cork(sk
, cork
, ipc
, rtp
);
1503 return ERR_PTR(err
);
1505 err
= __ip_append_data(sk
, fl4
, &queue
, cork
,
1506 ¤t
->task_frag
, getfrag
,
1507 from
, length
, transhdrlen
, flags
);
1509 __ip_flush_pending_frames(sk
, &queue
, cork
);
1510 return ERR_PTR(err
);
1513 return __ip_make_skb(sk
, fl4
, &queue
, cork
);
1517 * Fetch data from kernel space and fill in checksum if needed.
1519 static int ip_reply_glue_bits(void *dptr
, char *to
, int offset
,
1520 int len
, int odd
, struct sk_buff
*skb
)
1524 csum
= csum_partial_copy_nocheck(dptr
+offset
, to
, len
, 0);
1525 skb
->csum
= csum_block_add(skb
->csum
, csum
, odd
);
1530 * Generic function to send a packet as reply to another packet.
1531 * Used to send some TCP resets/acks so far.
1533 void ip_send_unicast_reply(struct sock
*sk
, struct sk_buff
*skb
,
1534 const struct ip_options
*sopt
,
1535 __be32 daddr
, __be32 saddr
,
1536 const struct ip_reply_arg
*arg
,
1539 struct ip_options_data replyopts
;
1540 struct ipcm_cookie ipc
;
1542 struct rtable
*rt
= skb_rtable(skb
);
1543 struct net
*net
= sock_net(sk
);
1544 struct sk_buff
*nskb
;
1548 if (__ip_options_echo(net
, &replyopts
.opt
.opt
, skb
, sopt
))
1554 if (replyopts
.opt
.opt
.optlen
) {
1555 ipc
.opt
= &replyopts
.opt
;
1557 if (replyopts
.opt
.opt
.srr
)
1558 daddr
= replyopts
.opt
.opt
.faddr
;
1561 oif
= arg
->bound_dev_if
;
1562 if (!oif
&& netif_index_is_l3_master(net
, skb
->skb_iif
))
1565 flowi4_init_output(&fl4
, oif
,
1566 IP4_REPLY_MARK(net
, skb
->mark
) ?: sk
->sk_mark
,
1568 RT_SCOPE_UNIVERSE
, ip_hdr(skb
)->protocol
,
1569 ip_reply_arg_flowi_flags(arg
),
1571 tcp_hdr(skb
)->source
, tcp_hdr(skb
)->dest
,
1573 security_skb_classify_flow(skb
, flowi4_to_flowi(&fl4
));
1574 rt
= ip_route_output_key(net
, &fl4
);
1578 inet_sk(sk
)->tos
= arg
->tos
;
1580 sk
->sk_priority
= skb
->priority
;
1581 sk
->sk_protocol
= ip_hdr(skb
)->protocol
;
1582 sk
->sk_bound_dev_if
= arg
->bound_dev_if
;
1583 sk
->sk_sndbuf
= sysctl_wmem_default
;
1584 sk
->sk_mark
= fl4
.flowi4_mark
;
1585 err
= ip_append_data(sk
, &fl4
, ip_reply_glue_bits
, arg
->iov
->iov_base
,
1586 len
, 0, &ipc
, &rt
, MSG_DONTWAIT
);
1587 if (unlikely(err
)) {
1588 ip_flush_pending_frames(sk
);
1592 nskb
= skb_peek(&sk
->sk_write_queue
);
1594 if (arg
->csumoffset
>= 0)
1595 *((__sum16
*)skb_transport_header(nskb
) +
1596 arg
->csumoffset
) = csum_fold(csum_add(nskb
->csum
,
1598 nskb
->ip_summed
= CHECKSUM_NONE
;
1599 ip_push_pending_frames(sk
, &fl4
);
1605 void __init
ip_init(void)
1610 #if defined(CONFIG_IP_MULTICAST)