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linux-stable/net/ipv4/ip_output.c
Jakub Kicinski 7f9eee196e Merge branch 'io_uring-zerocopy-send' of git://git.kernel.org/pub/scm/linux/kernel/git/kuba/linux 
Pavel Begunkov says:

====================
io_uring zerocopy send

The patchset implements io_uring zerocopy send. It works with both registered
and normal buffers, mixing is allowed but not recommended. Apart from usual
request completions, just as with MSG_ZEROCOPY, io_uring separately notifies
the userspace when buffers are freed and can be reused (see API design below),
which is delivered into io_uring's Completion Queue. Those "buffer-free"
notifications are not necessarily per request, but the userspace has control
over it and should explicitly attaching a number of requests to a single
notification. The series also adds some internal optimisations when used with
registered buffers like removing page referencing.

From the kernel networking perspective there are two main changes. The first
one is passing ubuf_info into the network layer from io_uring (inside of an
in kernel struct msghdr). This allows extra optimisations, e.g. ubuf_info
caching on the io_uring side, but also helps to avoid cross-referencing
and synchronisation problems. The second part is an optional optimisation
removing page referencing for requests with registered buffers.

Benchmarking UDP with an optimised version of the selftest (see [1]), which
sends a bunch of requests, waits for completions and repeats. "+ flush" column
posts one additional "buffer-free" notification per request, and just "zc"
doesn't post buffer notifications at all.

NIC (requests / second):
IO size | non-zc    | zc             | zc + flush
4000    | 495134    | 606420 (+22%)  | 558971 (+12%)
1500    | 551808    | 577116 (+4.5%) | 565803 (+2.5%)
1000    | 584677    | 592088 (+1.2%) | 560885 (-4%)
600     | 596292    | 598550 (+0.4%) | 555366 (-6.7%)

dummy (requests / second):
IO size | non-zc    | zc             | zc + flush
8000    | 1299916   | 2396600 (+84%) | 2224219 (+71%)
4000    | 1869230   | 2344146 (+25%) | 2170069 (+16%)
1200    | 2071617   | 2361960 (+14%) | 2203052 (+6%)
600     | 2106794   | 2381527 (+13%) | 2195295 (+4%)

Previously it also brought a massive performance speedup compared to the
msg_zerocopy tool (see [3]), which is probably not super interesting. There
is also an additional bunch of refcounting optimisations that was omitted from
the series for simplicity and as they don't change the picture drastically,
they will be sent as follow up, as well as flushing optimisations closing the
performance gap b/w two last columns.

For TCP on localhost (with hacks enabling localhost zerocopy) and including
additional overhead for receive:

IO size | non-zc    | zc
1200    | 4174      | 4148
4096    | 7597      | 11228

Using a real NIC 1200 bytes, zc is worse than non-zc ~5-10%, maybe the
omitted optimisations will somewhat help, should look better for 4000,
but couldn't test properly because of setup problems.

Links:

  liburing (benchmark + tests):
  [1] https://github.com/isilence/liburing/tree/zc_v4

  kernel repo:
  [2] https://github.com/isilence/linux/tree/zc_v4

  RFC v1:
  [3] https://lore.kernel.org/io-uring/cover.1638282789.git.asml.silence@gmail.com/

  RFC v2:
  https://lore.kernel.org/io-uring/cover.1640029579.git.asml.silence@gmail.com/

  Net patches based:
  git@github.com:isilence/linux.git zc_v4-net-base
  or
  https://github.com/isilence/linux/tree/zc_v4-net-base

API design overview:

  The series introduces an io_uring concept of notifactors. From the userspace
  perspective it's an entity to which it can bind one or more requests and then
  requesting to flush it. Flushing a notifier makes it impossible to attach new
  requests to it, and instructs the notifier to post a completion once all
  requests attached to it are completed and the kernel doesn't need the buffers
  anymore.

  Notifications are stored in notification slots, which should be registered as
  an array in io_uring. Each slot stores only one notifier at any particular
  moment. Flushing removes it from the slot and the slot automatically replaces
  it with a new notifier. All operations with notifiers are done by specifying
  an index of a slot it's currently in.

  When registering a notification the userspace specifies a u64 tag for each
  slot, which will be copied in notification completion entries as
  cqe::user_data. cqe::res is 0 and cqe::flags is equal to wrap around u32
  sequence number counting notifiers of a slot.

====================

Link: https://lore.kernel.org/r/cover.1657643355.git.asml.silence@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-07-19 14:22:41 -07:00

1764 lines
44 KiB
C
Raw Blame History

// SPDX-License-Identifier: GPL-2.0-only
/*
* 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 readability.
* 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/inet_ecn.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,
u8 tos)
{
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 = 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;
/* Do not bother generating IPID for small packets (eg SYNACK) */
if (skb->len <= IPV4_MIN_MTU || ip_dont_fragment(sk, &rt->dst)) {
iph->frag_off = htons(IP_DF);
iph->id = 0;
} else {
iph->frag_off = 0;
/* TCP packets here are SYNACK with fat IPv4/TCP options.
* Avoid using the hashed IP ident generator.
*/
if (sk->sk_protocol == IPPROTO_TCP)
iph->id = (__force __be16)prandom_u32();
else
__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);
}
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;
bool is_v6gw = false;
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);
if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) {
skb = skb_expand_head(skb, hh_len);
if (!skb)
return -ENOMEM;
}
if (lwtunnel_xmit_redirect(dst->lwtstate)) {
int res = lwtunnel_xmit(skb);
if (res < 0 || res == LWTUNNEL_XMIT_DONE)
return res;
}
rcu_read_lock_bh();
neigh = ip_neigh_for_gw(rt, skb, &is_v6gw);
if (!IS_ERR(neigh)) {
int res;
sock_confirm_neigh(skb, neigh);
/* if crossing protocols, can not use the cached header */
res = neigh_output(neigh, skb, is_v6gw);
rcu_read_unlock_bh();
return res;
}
rcu_read_unlock_bh();
net_dbg_ratelimited("%s: No header cache and no neighbour!\n",
__func__);
kfree_skb_reason(skb, SKB_DROP_REASON_NEIGH_CREATEFAIL);
return -EINVAL;
}
static int ip_finish_output_gso(struct net *net, struct sock *sk,
struct sk_buff *skb, unsigned int mtu)
{
struct sk_buff *segs, *nskb;
netdev_features_t features;
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
* insufficient MTU.
*/
features = netif_skb_features(skb);
BUILD_BUG_ON(sizeof(*IPCB(skb)) > SKB_GSO_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);
skb_list_walk_safe(segs, segs, nskb) {
int err;
skb_mark_not_on_list(segs);
err = ip_fragment(net, sk, segs, mtu, ip_finish_output2);
if (err && ret == 0)
ret = err;
}
return ret;
}
static int __ip_finish_output(struct net *net, struct sock *sk, struct sk_buff *skb)
{
unsigned int mtu;
#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)->frag_max_size)
return ip_fragment(net, sk, skb, mtu, ip_finish_output2);
return ip_finish_output2(net, sk, skb);
}
static int ip_finish_output(struct net *net, struct sock *sk, struct sk_buff *skb)
{
int ret;
ret = BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb);
switch (ret) {
case NET_XMIT_SUCCESS:
return __ip_finish_output(net, sk, skb);
case NET_XMIT_CN:
return __ip_finish_output(net, sk, skb) ? : ret;
default:
kfree_skb_reason(skb, SKB_DROP_REASON_BPF_CGROUP_EGRESS);
return ret;
}
}
static int ip_mc_finish_output(struct net *net, struct sock *sk,
struct sk_buff *skb)
{
struct rtable *new_rt;
bool do_cn = false;
int ret, err;
ret = BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb);
switch (ret) {
case NET_XMIT_CN:
do_cn = true;
fallthrough;
case NET_XMIT_SUCCESS:
break;
default:
kfree_skb_reason(skb, SKB_DROP_REASON_BPF_CGROUP_EGRESS);
return ret;
}
/* Reset rt_iif so that inet_iif() will return skb->skb_iif. Setting
* this to non-zero causes ipi_ifindex in in_pktinfo to be overwritten,
* see ipv4_pktinfo_prepare().
*/
new_rt = rt_dst_clone(net->loopback_dev, skb_rtable(skb));
if (new_rt) {
new_rt->rt_iif = 0;
skb_dst_drop(skb);
skb_dst_set(skb, &new_rt->dst);
}
err = dev_loopback_xmit(net, sk, skb);
return (do_cn && err) ? ret : err;
}
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, *indev = 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, indev, dev,
ip_finish_output,
!(IPCB(skb)->flags & IPSKB_REROUTED));
}
EXPORT_SYMBOL(ip_output);
/*
* 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));
iph->saddr = fl4->saddr;
iph->daddr = 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);
}
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_reason(skb, SKB_DROP_REASON_IP_OUTNOROUTES);
return -EHOSTUNREACH;
}
EXPORT_SYMBOL(__ip_queue_xmit);
int ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl)
{
return __ip_queue_xmit(sk, skb, fl, inet_sk(sk)->tos);
}
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;
to->skb_iif = from->skb_iif;
skb_dst_drop(to);
skb_dst_copy(to, from);
to->dev = from->dev;
to->mark = from->mark;
skb_copy_hash(to, from);
#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);
}
void ip_fraglist_init(struct sk_buff *skb, struct iphdr *iph,
unsigned int hlen, struct ip_fraglist_iter *iter)
{
unsigned int first_len = skb_pagelen(skb);
iter->frag = skb_shinfo(skb)->frag_list;
skb_frag_list_init(skb);
iter->offset = 0;
iter->iph = iph;
iter->hlen = hlen;
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);
}
EXPORT_SYMBOL(ip_fraglist_init);
void ip_fraglist_prepare(struct sk_buff *skb, struct ip_fraglist_iter *iter)
{
unsigned int hlen = iter->hlen;
struct iphdr *iph = iter->iph;
struct sk_buff *frag;
frag = iter->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);
iter->iph = ip_hdr(frag);
iph = iter->iph;
iph->tot_len = htons(frag->len);
ip_copy_metadata(frag, skb);
iter->offset += skb->len - hlen;
iph->frag_off = htons(iter->offset >> 3);
if (frag->next)
iph->frag_off |= htons(IP_MF);
/* Ready, complete checksum */
ip_send_check(iph);
}
EXPORT_SYMBOL(ip_fraglist_prepare);
void ip_frag_init(struct sk_buff *skb, unsigned int hlen,
unsigned int ll_rs, unsigned int mtu, bool DF,
struct ip_frag_state *state)
{
struct iphdr *iph = ip_hdr(skb);
state->DF = DF;
state->hlen = hlen;
state->ll_rs = ll_rs;
state->mtu = mtu;
state->left = skb->len - hlen; /* Space per frame */
state->ptr = hlen; /* Where to start from */
state->offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3;
state->not_last_frag = iph->frag_off & htons(IP_MF);
}
EXPORT_SYMBOL(ip_frag_init);
static void ip_frag_ipcb(struct sk_buff *from, struct sk_buff *to,
bool first_frag)
{
/* Copy the flags to each fragment. */
IPCB(to)->flags = IPCB(from)->flags;
/* 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 (first_frag)
ip_options_fragment(from);
}
struct sk_buff *ip_frag_next(struct sk_buff *skb, struct ip_frag_state *state)
{
unsigned int len = state->left;
struct sk_buff *skb2;
struct iphdr *iph;
/* IF: it doesn't fit, use 'mtu' - the data space left */
if (len > state->mtu)
len = state->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 < state->left) {
len &= ~7;
}
/* Allocate buffer */
skb2 = alloc_skb(len + state->hlen + state->ll_rs, GFP_ATOMIC);
if (!skb2)
return ERR_PTR(-ENOMEM);
/*
* Set up data on packet
*/
ip_copy_metadata(skb2, skb);
skb_reserve(skb2, state->ll_rs);
skb_put(skb2, len + state->hlen);
skb_reset_network_header(skb2);
skb2->transport_header = skb2->network_header + state->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), state->hlen);
/*
* Copy a block of the IP datagram.
*/
if (skb_copy_bits(skb, state->ptr, skb_transport_header(skb2), len))
BUG();
state->left -= len;
/*
* Fill in the new header fields.
*/
iph = ip_hdr(skb2);
iph->frag_off = htons((state->offset >> 3));
if (state->DF)
iph->frag_off |= htons(IP_DF);
/*
* Added AC : If we are fragmenting a fragment that's not the
* last fragment then keep MF on each bit
*/
if (state->left > 0 || state->not_last_frag)
iph->frag_off |= htons(IP_MF);
state->ptr += len;
state->offset += len;
iph->tot_len = htons(len + state->hlen);
ip_send_check(iph);
return skb2;
}
EXPORT_SYMBOL(ip_frag_next);
/*
* 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;
struct sk_buff *skb2;
bool mono_delivery_time = skb->mono_delivery_time;
struct rtable *rt = skb_rtable(skb);
unsigned int mtu, hlen, ll_rs;
struct ip_fraglist_iter iter;
ktime_t tstamp = skb->tstamp;
struct ip_frag_state state;
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! */
ip_fraglist_init(skb, iph, hlen, &iter);
for (;;) {
/* Prepare header of the next frame,
* before previous one went down. */
if (iter.frag) {
bool first_frag = (iter.offset == 0);
IPCB(iter.frag)->flags = IPCB(skb)->flags;
ip_fraglist_prepare(skb, &iter);
if (first_frag && IPCB(skb)->opt.optlen) {
/* ipcb->opt is not populated for frags
* coming from __ip_make_skb(),
* ip_options_fragment() needs optlen
*/
IPCB(iter.frag)->opt.optlen =
IPCB(skb)->opt.optlen;
ip_options_fragment(iter.frag);
ip_send_check(iter.iph);
}
}
skb_set_delivery_time(skb, tstamp, mono_delivery_time);
err = output(net, sk, skb);
if (!err)
IP_INC_STATS(net, IPSTATS_MIB_FRAGCREATES);
if (err || !iter.frag)
break;
skb = ip_fraglist_next(&iter);
}
if (err == 0) {
IP_INC_STATS(net, IPSTATS_MIB_FRAGOKS);
return 0;
}
kfree_skb_list(iter.frag);
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:
/*
* Fragment the datagram.
*/
ip_frag_init(skb, hlen, ll_rs, mtu, IPCB(skb)->flags & IPSKB_FRAG_PMTU,
&state);
/*
* Keep copying data until we run out.
*/
while (state.left > 0) {
bool first_frag = (state.offset == 0);
skb2 = ip_frag_next(skb, &state);
if (IS_ERR(skb2)) {
err = PTR_ERR(skb2);
goto fail;
}
ip_frag_ipcb(skb, skb2, first_frag);
/*
* Put this fragment into the sending queue.
*/
skb_set_delivery_time(skb2, tstamp, mono_delivery_time);
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;
bool zc = false;
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 = false;
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 = atomic_inc_return(&sk->sk_tskey) - 1;
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) ? IP_MAX_MTU : 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) {
struct msghdr *msg = from;
if (getfrag == ip_generic_getfrag && msg->msg_ubuf) {
if (skb_zcopy(skb) && msg->msg_ubuf != skb_zcopy(skb))
return -EINVAL;
/* Leave uarg NULL if can't zerocopy, callers should
* be able to handle it.
*/
if ((rt->dst.dev->features & NETIF_F_SG) &&
csummode == CHECKSUM_PARTIAL) {
paged = true;
zc = true;
uarg = msg->msg_ubuf;
}
} else if (sock_flag(sk, SOCK_ZEROCOPY)) {
uarg = msg_zerocopy_realloc(sk, length, skb_zcopy(skb));
if (!uarg)
return -ENOBUFS;
extra_uref = !skb_zcopy(skb); /* only ref on new uarg */
if (rt->dst.dev->features & NETIF_F_SG &&
csummode == CHECKSUM_PARTIAL) {
paged = true;
zc = 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, alloc_extra;
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;
alloc_extra = hh_len + 15;
alloc_extra += 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)
alloc_extra += rt->dst.trailer_len;
if ((flags & MSG_MORE) &&
!(rt->dst.dev->features&NETIF_F_SG))
alloclen = mtu;
else if (!paged &&
(fraglen + alloc_extra < SKB_MAX_ALLOC ||
!(rt->dst.dev->features & NETIF_F_SG)))
alloclen = fraglen;
else if (!zc) {
alloclen = min_t(int, fraglen, MAX_HEADER);
pagedlen = fraglen - alloclen;
} else {
alloclen = fragheaderlen + transhdrlen;
pagedlen = datalen - transhdrlen;
}
alloclen += alloc_extra;
if (transhdrlen) {
skb = sock_alloc_send_skb(sk, alloclen,
(flags & MSG_DONTWAIT), &err);
} else {
skb = NULL;
if (refcount_read(&sk->sk_wmem_alloc) + wmem_alloc_delta <=
2 * sk->sk_sndbuf)
skb = alloc_skb(alloclen,
sk->sk_allocation);
if (unlikely(!skb))
err = -ENOBUFS;
}
if (!skb)
goto error;
/*
* Fill in the control structures
*/
skb->ip_summed = csummode;
skb->csum = 0;
skb_reserve(skb, hh_len);
/*
* Find where to start putting bytes.
*/
data = skb_put(skb, fraglen + exthdrlen - pagedlen);
skb_set_network_header(skb, exthdrlen);
skb->transport_header = (skb->network_header +
fragheaderlen);
data += fragheaderlen + exthdrlen;
if (fraggap) {
skb->csum = skb_copy_and_csum_bits(
skb_prev, maxfraglen,
data + transhdrlen, fraggap);
skb_prev->csum = csum_sub(skb_prev->csum,
skb->csum);
data += fraggap;
pskb_trim_unique(skb_prev, maxfraglen);
}
copy = datalen - transhdrlen - fraggap - pagedlen;
if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) {
err = -EFAULT;
kfree_skb(skb);
goto error;
}
offset += copy;
length -= copy + transhdrlen;
transhdrlen = 0;
exthdrlen = 0;
csummode = CHECKSUM_NONE;
/* only the initial fragment is time stamped */
skb_shinfo(skb)->tx_flags = cork->tx_flags;
cork->tx_flags = 0;
skb_shinfo(skb)->tskey = tskey;
tskey = 0;
skb_zcopy_set(skb, uarg, &extra_uref);
if ((flags & MSG_CONFIRM) && !skb_prev)
skb_set_dst_pending_confirm(skb, 1);
/*
* Put the packet on the pending queue.
*/
if (!skb->destructor) {
skb->destructor = sock_wfree;
skb->sk = sk;
wmem_alloc_delta += skb->truesize;
}
__skb_queue_tail(queue, skb);
continue;
}
if (copy > length)
copy = length;
if (!(rt->dst.dev->features&NETIF_F_SG) &&
skb_tailroom(skb) >= copy) {
unsigned int off;
off = skb->len;
if (getfrag(from, skb_put(skb, copy),
offset, copy, off, skb) < 0) {
__skb_trim(skb, off);
err = -EFAULT;
goto error;
}
} else if (!zc) {
int i = skb_shinfo(skb)->nr_frags;
err = -ENOMEM;
if (!sk_page_frag_refill(sk, pfrag))
goto error;
skb_zcopy_downgrade_managed(skb);
if (!skb_can_coalesce(skb, i, pfrag->page,
pfrag->offset)) {
err = -EMSGSIZE;
if (i == MAX_SKB_FRAGS)
goto error;
__skb_fill_page_desc(skb, i, pfrag->page,
pfrag->offset, 0);
skb_shinfo(skb)->nr_frags = ++i;
get_page(pfrag->page);
}
copy = min_t(int, copy, pfrag->size - pfrag->offset);
if (getfrag(from,
page_address(pfrag->page) + pfrag->offset,
offset, copy, skb->len, skb) < 0)
goto error_efault;
pfrag->offset += copy;
skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
skb_len_add(skb, copy);
wmem_alloc_delta += copy;
} else {
err = skb_zerocopy_iter_dgram(skb, from, copy);
if (err < 0)
goto error;
}
offset += copy;
length -= copy;
}
if (wmem_alloc_delta)
refcount_add(wmem_alloc_delta, &sk->sk_wmem_alloc);
return 0;
error_efault:
err = -EFAULT;
error:
net_zcopy_put_abort(uarg, extra_uref);
cork->length -= length;
IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
refcount_add(wmem_alloc_delta, &sk->sk_wmem_alloc);
return err;
}
static int ip_setup_cork(struct sock *sk, struct inet_cork *cork,
struct ipcm_cookie *ipc, struct rtable **rtp)
{
struct ip_options_rcu *opt;
struct rtable *rt;
rt = *rtp;
if (unlikely(!rt))
return -EFAULT;
/*
* setup for corking.
*/
opt = ipc->opt;
if (opt) {
if (!cork->opt) {
cork->opt = kmalloc(sizeof(struct ip_options) + 40,
sk->sk_allocation);
if (unlikely(!cork->opt))
return -ENOBUFS;
}
memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen);
cork->flags |= IPCORK_OPT;
cork->addr = ipc->addr;
}
cork->fragsize = ip_sk_use_pmtu(sk) ?
dst_mtu(&rt->dst) : READ_ONCE(rt->dst.dev->mtu);
if (!inetdev_valid_mtu(cork->fragsize))
return -ENETUNREACH;
cork->gso_size = ipc->gso_size;
cork->dst = &rt->dst;
/* We stole this route, caller should not release it. */
*rtp = NULL;
cork->length = 0;
cork->ttl = ipc->ttl;
cork->tos = ipc->tos;
cork->mark = ipc->sockc.mark;
cork->priority = ipc->priority;
cork->transmit_time = ipc->sockc.transmit_time;
cork->tx_flags = 0;
sock_tx_timestamp(sk, ipc->sockc.tsflags, &cork->tx_flags);
return 0;
}
/*
* ip_append_data() and ip_append_page() can make one large IP datagram
* from many pieces of data. Each pieces will be holded on the socket
* until ip_push_pending_frames() is called. Each piece can be a page
* or non-page data.
*
* Not only UDP, other transport protocols - e.g. raw sockets - can use
* this interface potentially.
*
* LATER: length must be adjusted by pad at tail, when it is required.
*/
int ip_append_data(struct sock *sk, struct flowi4 *fl4,
int getfrag(void *from, char *to, int offset, int len,
int odd, struct sk_buff *skb),
void *from, int length, int transhdrlen,
struct ipcm_cookie *ipc, struct rtable **rtp,
unsigned int flags)
{
struct inet_sock *inet = inet_sk(sk);
int err;
if (flags&MSG_PROBE)
return 0;
if (skb_queue_empty(&sk->sk_write_queue)) {
err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp);
if (err)
return err;
} else {
transhdrlen = 0;
}
return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base,
sk_page_frag(sk), getfrag,
from, length, transhdrlen, flags);
}
ssize_t ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page,
int offset, size_t size, int flags)
{
struct inet_sock *inet = inet_sk(sk);
struct sk_buff *skb;
struct rtable *rt;
struct ip_options *opt = NULL;
struct inet_cork *cork;
int hh_len;
int mtu;
int len;
int err;
unsigned int maxfraglen, fragheaderlen, fraggap, maxnonfragsize;
if (inet->hdrincl)
return -EPERM;
if (flags&MSG_PROBE)
return 0;
if (skb_queue_empty(&sk->sk_write_queue))
return -EINVAL;
cork = &inet->cork.base;
rt = (struct rtable *)cork->dst;
if (cork->flags & IPCORK_OPT)
opt = cork->opt;
if (!(rt->dst.dev->features & NETIF_F_SG))
return -EOPNOTSUPP;
hh_len = LL_RESERVED_SPACE(rt->dst.dev);
mtu = cork->gso_size ? IP_MAX_MTU : cork->fragsize;
fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
maxnonfragsize = ip_sk_ignore_df(sk) ? 0xFFFF : mtu;
if (cork->length + size > maxnonfragsize - fragheaderlen) {
ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
mtu - (opt ? opt->optlen : 0));
return -EMSGSIZE;
}
skb = skb_peek_tail(&sk->sk_write_queue);
if (!skb)
return -EINVAL;
cork->length += size;
while (size > 0) {
/* Check if the remaining data fits into current packet. */
len = mtu - skb->len;
if (len < size)
len = maxfraglen - skb->len;
if (len <= 0) {
struct sk_buff *skb_prev;
int alloclen;
skb_prev = skb;
fraggap = skb_prev->len - maxfraglen;
alloclen = fragheaderlen + hh_len + fraggap + 15;
skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation);
if (unlikely(!skb)) {
err = -ENOBUFS;
goto error;
}
/*
* Fill in the control structures
*/
skb->ip_summed = CHECKSUM_NONE;
skb->csum = 0;
skb_reserve(skb, hh_len);
/*
* Find where to start putting bytes.
*/
skb_put(skb, fragheaderlen + fraggap);
skb_reset_network_header(skb);
skb->transport_header = (skb->network_header +
fragheaderlen);
if (fraggap) {
skb->csum = skb_copy_and_csum_bits(skb_prev,
maxfraglen,
skb_transport_header(skb),
fraggap);
skb_prev->csum = csum_sub(skb_prev->csum,
skb->csum);
pskb_trim_unique(skb_prev, maxfraglen);
}
/*
* Put the packet on the pending queue.
*/
__skb_queue_tail(&sk->sk_write_queue, skb);
continue;
}
if (len > size)
len = size;
if (skb_append_pagefrags(skb, page, offset, len)) {
err = -EMSGSIZE;
goto error;
}
if (skb->ip_summed == CHECKSUM_NONE) {
__wsum csum;
csum = csum_page(page, offset, len);
skb->csum = csum_block_add(skb->csum, csum, skb->len);
}
skb_len_add(skb, len);
refcount_add(len, &sk->sk_wmem_alloc);
offset += len;
size -= len;
}
return 0;
error:
cork->length -= size;
IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
return err;
}
static void ip_cork_release(struct inet_cork *cork)
{
cork->flags &= ~IPCORK_OPT;
kfree(cork->opt);
cork->opt = NULL;
dst_release(cork->dst);
cork->dst = NULL;
}
/*
* Combined all pending IP fragments on the socket as one IP datagram
* and push them out.
*/
struct sk_buff *__ip_make_skb(struct sock *sk,
struct flowi4 *fl4,
struct sk_buff_head *queue,
struct inet_cork *cork)
{
struct sk_buff *skb, *tmp_skb;
struct sk_buff **tail_skb;
struct inet_sock *inet = inet_sk(sk);
struct net *net = sock_net(sk);
struct ip_options *opt = NULL;
struct rtable *rt = (struct rtable *)cork->dst;
struct iphdr *iph;
__be16 df = 0;
__u8 ttl;
skb = __skb_dequeue(queue);
if (!skb)
goto out;
tail_skb = &(skb_shinfo(skb)->frag_list);
/* move skb->data to ip header from ext header */
if (skb->data < skb_network_header(skb))
__skb_pull(skb, skb_network_offset(skb));
while ((tmp_skb = __skb_dequeue(queue)) != NULL) {
__skb_pull(tmp_skb, skb_network_header_len(skb));
*tail_skb = tmp_skb;
tail_skb = &(tmp_skb->next);
skb->len += tmp_skb->len;
skb->data_len += tmp_skb->len;
skb->truesize += tmp_skb->truesize;
tmp_skb->destructor = NULL;
tmp_skb->sk = NULL;
}
/* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow
* to fragment the frame generated here. No matter, what transforms
* how transforms change size of the packet, it will come out.
*/
skb->ignore_df = ip_sk_ignore_df(sk);
/* DF bit is set when we want to see DF on outgoing frames.
* If ignore_df is set too, we still allow to fragment this frame
* locally. */
if (inet->pmtudisc == IP_PMTUDISC_DO ||
inet->pmtudisc == IP_PMTUDISC_PROBE ||
(skb->len <= dst_mtu(&rt->dst) &&
ip_dont_fragment(sk, &rt->dst)))
df = htons(IP_DF);
if (cork->flags & IPCORK_OPT)
opt = cork->opt;
if (cork->ttl != 0)
ttl = cork->ttl;
else if (rt->rt_type == RTN_MULTICAST)
ttl = inet->mc_ttl;
else
ttl = ip_select_ttl(inet, &rt->dst);
iph = ip_hdr(skb);
iph->version = 4;
iph->ihl = 5;
iph->tos = (cork->tos != -1) ? cork->tos : inet->tos;
iph->frag_off = df;
iph->ttl = ttl;
iph->protocol = sk->sk_protocol;
ip_copy_addrs(iph, fl4);
ip_select_ident(net, skb, sk);
if (opt) {
iph->ihl += opt->optlen >> 2;
ip_options_build(skb, opt, cork->addr, rt);
}
skb->priority = (cork->tos != -1) ? cork->priority: sk->sk_priority;
skb->mark = cork->mark;
skb->tstamp = cork->transmit_time;
/*
* Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec
* on dst refcount
*/
cork->dst = NULL;
skb_dst_set(skb, &rt->dst);
if (iph->protocol == IPPROTO_ICMP)
icmp_out_count(net, ((struct icmphdr *)
skb_transport_header(skb))->type);
ip_cork_release(cork);
out:
return skb;
}
int ip_send_skb(struct net *net, struct sk_buff *skb)
{
int err;
err = ip_local_out(net, skb->sk, skb);
if (err) {
if (err > 0)
err = net_xmit_errno(err);
if (err)
IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS);
}
return err;
}
int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4)
{
struct sk_buff *skb;
skb = ip_finish_skb(sk, fl4);
if (!skb)
return 0;
/* Netfilter gets whole the not fragmented skb. */
return ip_send_skb(sock_net(sk), skb);
}
/*
* Throw away all pending data on the socket.
*/
static void __ip_flush_pending_frames(struct sock *sk,
struct sk_buff_head *queue,
struct inet_cork *cork)
{
struct sk_buff *skb;
while ((skb = __skb_dequeue_tail(queue)) != NULL)
kfree_skb(skb);
ip_cork_release(cork);
}
void ip_flush_pending_frames(struct sock *sk)
{
__ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork.base);
}
struct sk_buff *ip_make_skb(struct sock *sk,
struct flowi4 *fl4,
int getfrag(void *from, char *to, int offset,
int len, int odd, struct sk_buff *skb),
void *from, int length, int transhdrlen,
struct ipcm_cookie *ipc, struct rtable **rtp,
struct inet_cork *cork, unsigned int flags)
{
struct sk_buff_head queue;
int err;
if (flags & MSG_PROBE)
return NULL;
__skb_queue_head_init(&queue);
cork->flags = 0;
cork->addr = 0;
cork->opt = NULL;
err = ip_setup_cork(sk, cork, ipc, rtp);
if (err)
return ERR_PTR(err);
err = __ip_append_data(sk, fl4, &queue, cork,
&current->task_frag, getfrag,
from, length, transhdrlen, flags);
if (err) {
__ip_flush_pending_frames(sk, &queue, cork);
return ERR_PTR(err);
}
return __ip_make_skb(sk, fl4, &queue, cork);
}
/*
* Fetch data from kernel space and fill in checksum if needed.
*/
static int ip_reply_glue_bits(void *dptr, char *to, int offset,
int len, int odd, struct sk_buff *skb)
{
__wsum csum;
csum = csum_partial_copy_nocheck(dptr+offset, to, len);
skb->csum = csum_block_add(skb->csum, csum, odd);
return 0;
}
/*
* Generic function to send a packet as reply to another packet.
* Used to send some TCP resets/acks so far.
*/
void ip_send_unicast_reply(struct sock *sk, struct sk_buff *skb,
const struct ip_options *sopt,
__be32 daddr, __be32 saddr,
const struct ip_reply_arg *arg,
unsigned int len, u64 transmit_time)
{
struct ip_options_data replyopts;
struct ipcm_cookie ipc;
struct flowi4 fl4;
struct rtable *rt = skb_rtable(skb);
struct net *net = sock_net(sk);
struct sk_buff *nskb;
int err;
int oif;
if (__ip_options_echo(net, &replyopts.opt.opt, skb, sopt))
return;
ipcm_init(&ipc);
ipc.addr = daddr;
ipc.sockc.transmit_time = transmit_time;
if (replyopts.opt.opt.optlen) {
ipc.opt = &replyopts.opt;
if (replyopts.opt.opt.srr)
daddr = replyopts.opt.opt.faddr;
}
oif = arg->bound_dev_if;
if (!oif && netif_index_is_l3_master(net, skb->skb_iif))
oif = skb->skb_iif;
flowi4_init_output(&fl4, oif,
IP4_REPLY_MARK(net, skb->mark) ?: sk->sk_mark,
RT_TOS(arg->tos),
RT_SCOPE_UNIVERSE, ip_hdr(skb)->protocol,
ip_reply_arg_flowi_flags(arg),
daddr, saddr,
tcp_hdr(skb)->source, tcp_hdr(skb)->dest,
arg->uid);
security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4));
rt = ip_route_output_flow(net, &fl4, sk);
if (IS_ERR(rt))
return;
inet_sk(sk)->tos = arg->tos & ~INET_ECN_MASK;
sk->sk_protocol = ip_hdr(skb)->protocol;
sk->sk_bound_dev_if = arg->bound_dev_if;
sk->sk_sndbuf = sysctl_wmem_default;
ipc.sockc.mark = fl4.flowi4_mark;
err = ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base,
len, 0, &ipc, &rt, MSG_DONTWAIT);
if (unlikely(err)) {
ip_flush_pending_frames(sk);
goto out;
}
nskb = skb_peek(&sk->sk_write_queue);
if (nskb) {
if (arg->csumoffset >= 0)
*((__sum16 *)skb_transport_header(nskb) +
arg->csumoffset) = csum_fold(csum_add(nskb->csum,
arg->csum));
nskb->ip_summed = CHECKSUM_NONE;
nskb->mono_delivery_time = !!transmit_time;
ip_push_pending_frames(sk, &fl4);
}
out:
ip_rt_put(rt);
}
void __init ip_init(void)
{
ip_rt_init();
inet_initpeers();
#if defined(CONFIG_IP_MULTICAST)
igmp_mc_init();
#endif
}
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