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ip_output.c
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ip_output.c
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/*
* INET An implementation of the TCP/IP protocol suite for the LINUX
* operating system. INET is implemented using the BSD Socket
* interface as the means of communication with the user level.
*
* The Internet Protocol (IP) output module.
*
* Authors: Ross Biro
* Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
* Donald Becker, <becker@super.org>
* Alan Cox, <Alan.Cox@linux.org>
* Richard Underwood
* Stefan Becker, <stefanb@yello.ping.de>
* Jorge Cwik, <jorge@laser.satlink.net>
* Arnt Gulbrandsen, <agulbra@nvg.unit.no>
* Hirokazu Takahashi, <taka@valinux.co.jp>
*
* See ip_input.c for original log
*
* Fixes:
* Alan Cox : Missing nonblock feature in ip_build_xmit.
* Mike Kilburn : htons() missing in ip_build_xmit.
* Bradford Johnson: Fix faulty handling of some frames when
* no route is found.
* Alexander Demenshin: Missing sk/skb free in ip_queue_xmit
* (in case if packet not accepted by
* output firewall rules)
* Mike McLagan : Routing by source
* Alexey Kuznetsov: use new route cache
* Andi Kleen: Fix broken PMTU recovery and remove
* some redundant tests.
* Vitaly E. Lavrov : Transparent proxy revived after year coma.
* Andi Kleen : Replace ip_reply with ip_send_reply.
* Andi Kleen : Split fast and slow ip_build_xmit path
* for decreased register pressure on x86
* and more readibility.
* Marc Boucher : When call_out_firewall returns FW_QUEUE,
* silently drop skb instead of failing with -EPERM.
* Detlev Wengorz : Copy protocol for fragments.
* Hirokazu Takahashi: HW checksumming for outgoing UDP
* datagrams.
* Hirokazu Takahashi: sendfile() on UDP works now.
*/
#include <linux/uaccess.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/highmem.h>
#include <linux/slab.h>
#include <linux/socket.h>
#include <linux/sockios.h>
#include <linux/in.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/proc_fs.h>
#include <linux/stat.h>
#include <linux/init.h>
#include <net/snmp.h>
#include <net/ip.h>
#include <net/protocol.h>
#include <net/route.h>
#include <net/xfrm.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <net/arp.h>
#include <net/icmp.h>
#include <net/checksum.h>
#include <net/inetpeer.h>
#include <net/lwtunnel.h>
#include <linux/bpf-cgroup.h>
#include <linux/igmp.h>
#include <linux/netfilter_ipv4.h>
#include <linux/netfilter_bridge.h>
#include <linux/netlink.h>
#include <linux/tcp.h>
static int
ip_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
unsigned int mtu,
int (*output)(struct net *, struct sock *, struct sk_buff *));
/* Generate a checksum for an outgoing IP datagram. */
void ip_send_check(struct iphdr *iph)
{
iph->check = 0;
iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
}
EXPORT_SYMBOL(ip_send_check);
int __ip_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
{
struct iphdr *iph = ip_hdr(skb);
iph->tot_len = htons(skb->len);
ip_send_check(iph);
/* if egress device is enslaved to an L3 master device pass the
* skb to its handler for processing
*/
skb = l3mdev_ip_out(sk, skb);
if (unlikely(!skb))
return 0;
skb->protocol = htons(ETH_P_IP);
return nf_hook(NFPROTO_IPV4, NF_INET_LOCAL_OUT,
net, sk, skb, NULL, skb_dst(skb)->dev,
dst_output);
}
int ip_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
{
int err;
err = __ip_local_out(net, sk, skb);
if (likely(err == 1))
err = dst_output(net, sk, skb);
return err;
}
EXPORT_SYMBOL_GPL(ip_local_out);
static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst)
{
int ttl = inet->uc_ttl;
if (ttl < 0)
ttl = ip4_dst_hoplimit(dst);
return ttl;
}
/*
* Add an ip header to a skbuff and send it out.
*
*/
int ip_build_and_send_pkt(struct sk_buff *skb, const struct sock *sk,
__be32 saddr, __be32 daddr, struct ip_options_rcu *opt)
{
struct inet_sock *inet = inet_sk(sk);
struct rtable *rt = skb_rtable(skb);
struct net *net = sock_net(sk);
struct iphdr *iph;
/* Build the IP header. */
skb_push(skb, sizeof(struct iphdr) + (opt ? opt->opt.optlen : 0));
skb_reset_network_header(skb);
iph = ip_hdr(skb);
iph->version = 4;
iph->ihl = 5;
iph->tos = inet->tos;
iph->ttl = ip_select_ttl(inet, &rt->dst);
iph->daddr = (opt && opt->opt.srr ? opt->opt.faddr : daddr);
iph->saddr = saddr;
iph->protocol = sk->sk_protocol;
if (ip_dont_fragment(sk, &rt->dst)) {
iph->frag_off = htons(IP_DF);
iph->id = 0;
} else {
iph->frag_off = 0;
__ip_select_ident(net, iph, 1);
}
if (opt && opt->opt.optlen) {
iph->ihl += opt->opt.optlen>>2;
ip_options_build(skb, &opt->opt, daddr, rt, 0);
}
skb->priority = sk->sk_priority;
if (!skb->mark)
skb->mark = sk->sk_mark;
/* Send it out. */
return ip_local_out(net, skb->sk, skb);
}
EXPORT_SYMBOL_GPL(ip_build_and_send_pkt);
static int ip_finish_output2(struct net *net, struct sock *sk, struct sk_buff *skb)
{
struct dst_entry *dst = skb_dst(skb);
struct rtable *rt = (struct rtable *)dst;
struct net_device *dev = dst->dev;
unsigned int hh_len = LL_RESERVED_SPACE(dev);
struct neighbour *neigh;
u32 nexthop;
if (rt->rt_type == RTN_MULTICAST) {
IP_UPD_PO_STATS(net, IPSTATS_MIB_OUTMCAST, skb->len);
} else if (rt->rt_type == RTN_BROADCAST)
IP_UPD_PO_STATS(net, IPSTATS_MIB_OUTBCAST, skb->len);
/* Be paranoid, rather than too clever. */
if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) {
struct sk_buff *skb2;
skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev));
if (!skb2) {
kfree_skb(skb);
return -ENOMEM;
}
if (skb->sk)
skb_set_owner_w(skb2, skb->sk);
consume_skb(skb);
skb = skb2;
}
if (lwtunnel_xmit_redirect(dst->lwtstate)) {
int res = lwtunnel_xmit(skb);
if (res < 0 || res == LWTUNNEL_XMIT_DONE)
return res;
}
rcu_read_lock_bh();
nexthop = (__force u32) rt_nexthop(rt, ip_hdr(skb)->daddr);
neigh = __ipv4_neigh_lookup_noref(dev, nexthop);
if (unlikely(!neigh))
neigh = __neigh_create(&arp_tbl, &nexthop, dev, false);
if (!IS_ERR(neigh)) {
int res;
sock_confirm_neigh(skb, neigh);
res = neigh_output(neigh, skb);
rcu_read_unlock_bh();
return res;
}
rcu_read_unlock_bh();
net_dbg_ratelimited("%s: No header cache and no neighbour!\n",
__func__);
kfree_skb(skb);
return -EINVAL;
}
static int ip_finish_output_gso(struct net *net, struct sock *sk,
struct sk_buff *skb, unsigned int mtu)
{
netdev_features_t features;
struct sk_buff *segs;
int ret = 0;
/* common case: seglen is <= mtu
*/
if (skb_gso_validate_network_len(skb, mtu))
return ip_finish_output2(net, sk, skb);
/* Slowpath - GSO segment length exceeds the egress MTU.
*
* This can happen in several cases:
* - Forwarding of a TCP GRO skb, when DF flag is not set.
* - Forwarding of an skb that arrived on a virtualization interface
* (virtio-net/vhost/tap) with TSO/GSO size set by other network
* stack.
* - Local GSO skb transmitted on an NETIF_F_TSO tunnel stacked over an
* interface with a smaller MTU.
* - Arriving GRO skb (or GSO skb in a virtualized environment) that is
* bridged to a NETIF_F_TSO tunnel stacked over an interface with an
* insufficent MTU.
*/
features = netif_skb_features(skb);
BUILD_BUG_ON(sizeof(*IPCB(skb)) > SKB_SGO_CB_OFFSET);
segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK);
if (IS_ERR_OR_NULL(segs)) {
kfree_skb(skb);
return -ENOMEM;
}
consume_skb(skb);
do {
struct sk_buff *nskb = segs->next;
int err;
skb_mark_not_on_list(segs);
err = ip_fragment(net, sk, segs, mtu, ip_finish_output2);
if (err && ret == 0)
ret = err;
segs = nskb;
} while (segs);
return ret;
}
static int ip_finish_output(struct net *net, struct sock *sk, struct sk_buff *skb)
{
unsigned int mtu;
int ret;
ret = BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb);
if (ret) {
kfree_skb(skb);
return ret;
}
#if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
/* Policy lookup after SNAT yielded a new policy */
if (skb_dst(skb)->xfrm) {
IPCB(skb)->flags |= IPSKB_REROUTED;
return dst_output(net, sk, skb);
}
#endif
mtu = ip_skb_dst_mtu(sk, skb);
if (skb_is_gso(skb))
return ip_finish_output_gso(net, sk, skb, mtu);
if (skb->len > mtu || (IPCB(skb)->flags & IPSKB_FRAG_PMTU))
return ip_fragment(net, sk, skb, mtu, ip_finish_output2);
return ip_finish_output2(net, sk, skb);
}
static int ip_mc_finish_output(struct net *net, struct sock *sk,
struct sk_buff *skb)
{
int ret;
ret = BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb);
if (ret) {
kfree_skb(skb);
return ret;
}
return dev_loopback_xmit(net, sk, skb);
}
int ip_mc_output(struct net *net, struct sock *sk, struct sk_buff *skb)
{
struct rtable *rt = skb_rtable(skb);
struct net_device *dev = rt->dst.dev;
/*
* If the indicated interface is up and running, send the packet.
*/
IP_UPD_PO_STATS(net, IPSTATS_MIB_OUT, skb->len);
skb->dev = dev;
skb->protocol = htons(ETH_P_IP);
/*
* Multicasts are looped back for other local users
*/
if (rt->rt_flags&RTCF_MULTICAST) {
if (sk_mc_loop(sk)
#ifdef CONFIG_IP_MROUTE
/* Small optimization: do not loopback not local frames,
which returned after forwarding; they will be dropped
by ip_mr_input in any case.
Note, that local frames are looped back to be delivered
to local recipients.
This check is duplicated in ip_mr_input at the moment.
*/
&&
((rt->rt_flags & RTCF_LOCAL) ||
!(IPCB(skb)->flags & IPSKB_FORWARDED))
#endif
) {
struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
if (newskb)
NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
net, sk, newskb, NULL, newskb->dev,
ip_mc_finish_output);
}
/* Multicasts with ttl 0 must not go beyond the host */
if (ip_hdr(skb)->ttl == 0) {
kfree_skb(skb);
return 0;
}
}
if (rt->rt_flags&RTCF_BROADCAST) {
struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
if (newskb)
NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
net, sk, newskb, NULL, newskb->dev,
ip_mc_finish_output);
}
return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
net, sk, skb, NULL, skb->dev,
ip_finish_output,
!(IPCB(skb)->flags & IPSKB_REROUTED));
}
int ip_output(struct net *net, struct sock *sk, struct sk_buff *skb)
{
struct net_device *dev = skb_dst(skb)->dev;
IP_UPD_PO_STATS(net, IPSTATS_MIB_OUT, skb->len);
skb->dev = dev;
skb->protocol = htons(ETH_P_IP);
return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
net, sk, skb, NULL, dev,
ip_finish_output,
!(IPCB(skb)->flags & IPSKB_REROUTED));
}
/*
* copy saddr and daddr, possibly using 64bit load/stores
* Equivalent to :
* iph->saddr = fl4->saddr;
* iph->daddr = fl4->daddr;
*/
static void ip_copy_addrs(struct iphdr *iph, const struct flowi4 *fl4)
{
BUILD_BUG_ON(offsetof(typeof(*fl4), daddr) !=
offsetof(typeof(*fl4), saddr) + sizeof(fl4->saddr));
memcpy(&iph->saddr, &fl4->saddr,
sizeof(fl4->saddr) + sizeof(fl4->daddr));
}
/* Note: skb->sk can be different from sk, in case of tunnels */
int __ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl,
__u8 tos)
{
struct inet_sock *inet = inet_sk(sk);
struct net *net = sock_net(sk);
struct ip_options_rcu *inet_opt;
struct flowi4 *fl4;
struct rtable *rt;
struct iphdr *iph;
int res;
/* Skip all of this if the packet is already routed,
* f.e. by something like SCTP.
*/
rcu_read_lock();
inet_opt = rcu_dereference(inet->inet_opt);
fl4 = &fl->u.ip4;
rt = skb_rtable(skb);
if (rt)
goto packet_routed;
/* Make sure we can route this packet. */
rt = (struct rtable *)__sk_dst_check(sk, 0);
if (!rt) {
__be32 daddr;
/* Use correct destination address if we have options. */
daddr = inet->inet_daddr;
if (inet_opt && inet_opt->opt.srr)
daddr = inet_opt->opt.faddr;
/* If this fails, retransmit mechanism of transport layer will
* keep trying until route appears or the connection times
* itself out.
*/
rt = ip_route_output_ports(net, fl4, sk,
daddr, inet->inet_saddr,
inet->inet_dport,
inet->inet_sport,
sk->sk_protocol,
RT_CONN_FLAGS_TOS(sk, tos),
sk->sk_bound_dev_if);
if (IS_ERR(rt))
goto no_route;
sk_setup_caps(sk, &rt->dst);
}
skb_dst_set_noref(skb, &rt->dst);
packet_routed:
if (inet_opt && inet_opt->opt.is_strictroute && rt->rt_uses_gateway)
goto no_route;
/* OK, we know where to send it, allocate and build IP header. */
skb_push(skb, sizeof(struct iphdr) + (inet_opt ? inet_opt->opt.optlen : 0));
skb_reset_network_header(skb);
iph = ip_hdr(skb);
*((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (tos & 0xff));
if (ip_dont_fragment(sk, &rt->dst) && !skb->ignore_df)
iph->frag_off = htons(IP_DF);
else
iph->frag_off = 0;
iph->ttl = ip_select_ttl(inet, &rt->dst);
iph->protocol = sk->sk_protocol;
ip_copy_addrs(iph, fl4);
/* Transport layer set skb->h.foo itself. */
if (inet_opt && inet_opt->opt.optlen) {
iph->ihl += inet_opt->opt.optlen >> 2;
ip_options_build(skb, &inet_opt->opt, inet->inet_daddr, rt, 0);
}
ip_select_ident_segs(net, skb, sk,
skb_shinfo(skb)->gso_segs ?: 1);
/* TODO : should we use skb->sk here instead of sk ? */
skb->priority = sk->sk_priority;
skb->mark = sk->sk_mark;
res = ip_local_out(net, sk, skb);
rcu_read_unlock();
return res;
no_route:
rcu_read_unlock();
IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
kfree_skb(skb);
return -EHOSTUNREACH;
}
EXPORT_SYMBOL(__ip_queue_xmit);
static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from)
{
to->pkt_type = from->pkt_type;
to->priority = from->priority;
to->protocol = from->protocol;
skb_dst_drop(to);
skb_dst_copy(to, from);
to->dev = from->dev;
to->mark = from->mark;
skb_copy_hash(to, from);
/* Copy the flags to each fragment. */
IPCB(to)->flags = IPCB(from)->flags;
#ifdef CONFIG_NET_SCHED
to->tc_index = from->tc_index;
#endif
nf_copy(to, from);
skb_ext_copy(to, from);
#if IS_ENABLED(CONFIG_IP_VS)
to->ipvs_property = from->ipvs_property;
#endif
skb_copy_secmark(to, from);
}
static int ip_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
unsigned int mtu,
int (*output)(struct net *, struct sock *, struct sk_buff *))
{
struct iphdr *iph = ip_hdr(skb);
if ((iph->frag_off & htons(IP_DF)) == 0)
return ip_do_fragment(net, sk, skb, output);
if (unlikely(!skb->ignore_df ||
(IPCB(skb)->frag_max_size &&
IPCB(skb)->frag_max_size > mtu))) {
IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
htonl(mtu));
kfree_skb(skb);
return -EMSGSIZE;
}
return ip_do_fragment(net, sk, skb, output);
}
/*
* This IP datagram is too large to be sent in one piece. Break it up into
* smaller pieces (each of size equal to IP header plus
* a block of the data of the original IP data part) that will yet fit in a
* single device frame, and queue such a frame for sending.
*/
int ip_do_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
int (*output)(struct net *, struct sock *, struct sk_buff *))
{
struct iphdr *iph;
int ptr;
struct sk_buff *skb2;
unsigned int mtu, hlen, left, len, ll_rs;
int offset;
__be16 not_last_frag;
struct rtable *rt = skb_rtable(skb);
int err = 0;
/* for offloaded checksums cleanup checksum before fragmentation */
if (skb->ip_summed == CHECKSUM_PARTIAL &&
(err = skb_checksum_help(skb)))
goto fail;
/*
* Point into the IP datagram header.
*/
iph = ip_hdr(skb);
mtu = ip_skb_dst_mtu(sk, skb);
if (IPCB(skb)->frag_max_size && IPCB(skb)->frag_max_size < mtu)
mtu = IPCB(skb)->frag_max_size;
/*
* Setup starting values.
*/
hlen = iph->ihl * 4;
mtu = mtu - hlen; /* Size of data space */
IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE;
ll_rs = LL_RESERVED_SPACE(rt->dst.dev);
/* When frag_list is given, use it. First, check its validity:
* some transformers could create wrong frag_list or break existing
* one, it is not prohibited. In this case fall back to copying.
*
* LATER: this step can be merged to real generation of fragments,
* we can switch to copy when see the first bad fragment.
*/
if (skb_has_frag_list(skb)) {
struct sk_buff *frag, *frag2;
unsigned int first_len = skb_pagelen(skb);
if (first_len - hlen > mtu ||
((first_len - hlen) & 7) ||
ip_is_fragment(iph) ||
skb_cloned(skb) ||
skb_headroom(skb) < ll_rs)
goto slow_path;
skb_walk_frags(skb, frag) {
/* Correct geometry. */
if (frag->len > mtu ||
((frag->len & 7) && frag->next) ||
skb_headroom(frag) < hlen + ll_rs)
goto slow_path_clean;
/* Partially cloned skb? */
if (skb_shared(frag))
goto slow_path_clean;
BUG_ON(frag->sk);
if (skb->sk) {
frag->sk = skb->sk;
frag->destructor = sock_wfree;
}
skb->truesize -= frag->truesize;
}
/* Everything is OK. Generate! */
err = 0;
offset = 0;
frag = skb_shinfo(skb)->frag_list;
skb_frag_list_init(skb);
skb->data_len = first_len - skb_headlen(skb);
skb->len = first_len;
iph->tot_len = htons(first_len);
iph->frag_off = htons(IP_MF);
ip_send_check(iph);
for (;;) {
/* Prepare header of the next frame,
* before previous one went down. */
if (frag) {
frag->ip_summed = CHECKSUM_NONE;
skb_reset_transport_header(frag);
__skb_push(frag, hlen);
skb_reset_network_header(frag);
memcpy(skb_network_header(frag), iph, hlen);
iph = ip_hdr(frag);
iph->tot_len = htons(frag->len);
ip_copy_metadata(frag, skb);
if (offset == 0)
ip_options_fragment(frag);
offset += skb->len - hlen;
iph->frag_off = htons(offset>>3);
if (frag->next)
iph->frag_off |= htons(IP_MF);
/* Ready, complete checksum */
ip_send_check(iph);
}
err = output(net, sk, skb);
if (!err)
IP_INC_STATS(net, IPSTATS_MIB_FRAGCREATES);
if (err || !frag)
break;
skb = frag;
frag = skb->next;
skb_mark_not_on_list(skb);
}
if (err == 0) {
IP_INC_STATS(net, IPSTATS_MIB_FRAGOKS);
return 0;
}
while (frag) {
skb = frag->next;
kfree_skb(frag);
frag = skb;
}
IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
return err;
slow_path_clean:
skb_walk_frags(skb, frag2) {
if (frag2 == frag)
break;
frag2->sk = NULL;
frag2->destructor = NULL;
skb->truesize += frag2->truesize;
}
}
slow_path:
iph = ip_hdr(skb);
left = skb->len - hlen; /* Space per frame */
ptr = hlen; /* Where to start from */
/*
* Fragment the datagram.
*/
offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3;
not_last_frag = iph->frag_off & htons(IP_MF);
/*
* Keep copying data until we run out.
*/
while (left > 0) {
len = left;
/* IF: it doesn't fit, use 'mtu' - the data space left */
if (len > mtu)
len = mtu;
/* IF: we are not sending up to and including the packet end
then align the next start on an eight byte boundary */
if (len < left) {
len &= ~7;
}
/* Allocate buffer */
skb2 = alloc_skb(len + hlen + ll_rs, GFP_ATOMIC);
if (!skb2) {
err = -ENOMEM;
goto fail;
}
/*
* Set up data on packet
*/
ip_copy_metadata(skb2, skb);
skb_reserve(skb2, ll_rs);
skb_put(skb2, len + hlen);
skb_reset_network_header(skb2);
skb2->transport_header = skb2->network_header + hlen;
/*
* Charge the memory for the fragment to any owner
* it might possess
*/
if (skb->sk)
skb_set_owner_w(skb2, skb->sk);
/*
* Copy the packet header into the new buffer.
*/
skb_copy_from_linear_data(skb, skb_network_header(skb2), hlen);
/*
* Copy a block of the IP datagram.
*/
if (skb_copy_bits(skb, ptr, skb_transport_header(skb2), len))
BUG();
left -= len;
/*
* Fill in the new header fields.
*/
iph = ip_hdr(skb2);
iph->frag_off = htons((offset >> 3));
if (IPCB(skb)->flags & IPSKB_FRAG_PMTU)
iph->frag_off |= htons(IP_DF);
/* ANK: dirty, but effective trick. Upgrade options only if
* the segment to be fragmented was THE FIRST (otherwise,
* options are already fixed) and make it ONCE
* on the initial skb, so that all the following fragments
* will inherit fixed options.
*/
if (offset == 0)
ip_options_fragment(skb);
/*
* Added AC : If we are fragmenting a fragment that's not the
* last fragment then keep MF on each bit
*/
if (left > 0 || not_last_frag)
iph->frag_off |= htons(IP_MF);
ptr += len;
offset += len;
/*
* Put this fragment into the sending queue.
*/
iph->tot_len = htons(len + hlen);
ip_send_check(iph);
err = output(net, sk, skb2);
if (err)
goto fail;
IP_INC_STATS(net, IPSTATS_MIB_FRAGCREATES);
}
consume_skb(skb);
IP_INC_STATS(net, IPSTATS_MIB_FRAGOKS);
return err;
fail:
kfree_skb(skb);
IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
return err;
}
EXPORT_SYMBOL(ip_do_fragment);
int
ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
{
struct msghdr *msg = from;
if (skb->ip_summed == CHECKSUM_PARTIAL) {
if (!copy_from_iter_full(to, len, &msg->msg_iter))
return -EFAULT;
} else {
__wsum csum = 0;
if (!csum_and_copy_from_iter_full(to, len, &csum, &msg->msg_iter))
return -EFAULT;
skb->csum = csum_block_add(skb->csum, csum, odd);
}
return 0;
}
EXPORT_SYMBOL(ip_generic_getfrag);
static inline __wsum
csum_page(struct page *page, int offset, int copy)
{
char *kaddr;
__wsum csum;
kaddr = kmap(page);
csum = csum_partial(kaddr + offset, copy, 0);
kunmap(page);
return csum;
}
static int __ip_append_data(struct sock *sk,
struct flowi4 *fl4,
struct sk_buff_head *queue,
struct inet_cork *cork,
struct page_frag *pfrag,
int getfrag(void *from, char *to, int offset,
int len, int odd, struct sk_buff *skb),
void *from, int length, int transhdrlen,
unsigned int flags)
{
struct inet_sock *inet = inet_sk(sk);
struct ubuf_info *uarg = NULL;
struct sk_buff *skb;
struct ip_options *opt = cork->opt;
int hh_len;
int exthdrlen;
int mtu;
int copy;
int err;
int offset = 0;
unsigned int maxfraglen, fragheaderlen, maxnonfragsize;
int csummode = CHECKSUM_NONE;
struct rtable *rt = (struct rtable *)cork->dst;
unsigned int wmem_alloc_delta = 0;
bool paged, extra_uref;
u32 tskey = 0;
skb = skb_peek_tail(queue);
exthdrlen = !skb ? rt->dst.header_len : 0;
mtu = cork->gso_size ? IP_MAX_MTU : cork->fragsize;
paged = !!cork->gso_size;
if (cork->tx_flags & SKBTX_ANY_SW_TSTAMP &&
sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID)
tskey = sk->sk_tskey++;
hh_len = LL_RESERVED_SPACE(rt->dst.dev);
fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
maxnonfragsize = ip_sk_ignore_df(sk) ? 0xFFFF : mtu;
if (cork->length + length > maxnonfragsize - fragheaderlen) {
ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
mtu - (opt ? opt->optlen : 0));
return -EMSGSIZE;
}
/*
* transhdrlen > 0 means that this is the first fragment and we wish
* it won't be fragmented in the future.
*/
if (transhdrlen &&
length + fragheaderlen <= mtu &&
rt->dst.dev->features & (NETIF_F_HW_CSUM | NETIF_F_IP_CSUM) &&
(!(flags & MSG_MORE) || cork->gso_size) &&
(!exthdrlen || (rt->dst.dev->features & NETIF_F_HW_ESP_TX_CSUM)))
csummode = CHECKSUM_PARTIAL;
if (flags & MSG_ZEROCOPY && length && sock_flag(sk, SOCK_ZEROCOPY)) {
uarg = sock_zerocopy_realloc(sk, length, skb_zcopy(skb));
if (!uarg)
return -ENOBUFS;
extra_uref = true;
if (rt->dst.dev->features & NETIF_F_SG &&
csummode == CHECKSUM_PARTIAL) {
paged = true;
} else {
uarg->zerocopy = 0;
skb_zcopy_set(skb, uarg, &extra_uref);
}
}
cork->length += length;
/* So, what's going on in the loop below?
*
* We use calculated fragment length to generate chained skb,
* each of segments is IP fragment ready for sending to network after
* adding appropriate IP header.
*/
if (!skb)
goto alloc_new_skb;
while (length > 0) {
/* Check if the remaining data fits into current packet. */
copy = mtu - skb->len;
if (copy < length)
copy = maxfraglen - skb->len;
if (copy <= 0) {
char *data;
unsigned int datalen;
unsigned int fraglen;
unsigned int fraggap;
unsigned int alloclen;
unsigned int pagedlen;
struct sk_buff *skb_prev;
alloc_new_skb:
skb_prev = skb;
if (skb_prev)
fraggap = skb_prev->len - maxfraglen;
else
fraggap = 0;
/*
* If remaining data exceeds the mtu,
* we know we need more fragment(s).
*/
datalen = length + fraggap;
if (datalen > mtu - fragheaderlen)
datalen = maxfraglen - fragheaderlen;
fraglen = datalen + fragheaderlen;
pagedlen = 0;
if ((flags & MSG_MORE) &&
!(rt->dst.dev->features&NETIF_F_SG))
alloclen = mtu;
else if (!paged)
alloclen = fraglen;
else {
alloclen = min_t(int, fraglen, MAX_HEADER);
pagedlen = fraglen - alloclen;
}
alloclen += exthdrlen;
/* The last fragment gets additional space at tail.
* Note, with MSG_MORE we overallocate on fragments,
* because we have no idea what fragment will be
* the last.
*/
if (datalen == length + fraggap)
alloclen += rt->dst.trailer_len;
if (transhdrlen) {
skb = sock_alloc_send_skb(sk,
alloclen + hh_len + 15,
(flags & MSG_DONTWAIT), &err);