Merge tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Don't destroy user event fields when removal fails

   User event fields are destroyed before the event is removed from
   visibility. But that can fail leaving the still visible event with no
   fields. Move the destroying of the fields to after the event is
   successfully removed from visibility.

 - Initialize function graph state is fork before calling
   copy_exec_state()

   For non-CLONE_VM forks, copy_exec_state() allocates a new
   task_exec_state. If that allocation fails, ftrace_graph_exit_task()
   will free the tasks ret_stack pointer. Since that pointer is still
   using the parent's ret_stack, it mistakenly frees the parent's
   pointer too.

   Call ftrace_graph_init() on the task first which will NULL out the
   new tasks's ret_stack and if the copy fails, it will not free
   anything.

 - Remove FGRAPH_MAX_INDEX

   The macro FGRAPH_MAX_INDEX was added but never used. Remove it.

 - Save ent_size in function graph printing of nested functions

   The function graph tracer needs to look at the next event to see if
   the next event is the return of the current function entry. If it is,
   it prints a single line:

	ktime_get();

   Otherwise it prints it like a nested function:

	tick_nohz_irq_exit() {
	    ktime_get();
	    kcpustat_irq_exit();
	}

   In order to look at the next event, it must save the current event so
   that it has the information to print from it. It saves the event in
   the iterator descriptor called "ent". What it doesn't save is the
   ent_size of the event which is now used to know if the function graph
   arguments are to be printed. The peek doesn't save the size so the
   size used happens to be that of the size of the last event that was
   seen.

   Save the entry event size in the iterator descriptor so that the
   correct size is used.

 - Fix several errors with freeing data in the histogram code

   The histogram code had a lot of leaked or or incorrect accounting
   when failures happen. Correct them.

 - Fix histogram regression of .percent and .graph modifiers

   Up until 6.3 histogram values could have "percent" or "graph"
   modifiers that changed how they were printed. But a change that added
   restricting histograms values from being strings, stack traces and
   other modifiers inadvertently prevented them from using the percent
   and graph modifiers, which were legal use cases for values.

   Put back the percent and graph modifiers.

 - Fix various typos in the comments

 - Set the trace_clock before initializing a histogram with clock
   argument

   The histogram API allows the user to specific which trace clock to
   use via a "clock=" string. The histogram is set up first before the
   clock is checked. If the passed in clock is not valid, it exits
   without fully fixing up the histogram leaving it on the list and a
   use-after-free can trigger.

   Update the clock argument first and if it fails then exit gracefully
   before the histogram trigger is placed on any lists.

 - Restore :mod: trailer after parsing in ftrace_set_clr_event

   The function ftrace_set_clr_event() modifies the parse string and
   needs to put it back to what was passed in. It searches for ":mod:"
   via a strsep() but fails to put back the first ':' in the string.

   Add back the ':' in the passed in string.

 - Take trace_array reference when opening a tracer options file

   The options files are dynamically created and some tracers add their
   own options. When a tracer adds their own list of options, the
   trace_array holding them has an array to hold the list of options for
   each tracer. This array increases in size via a krealloc(), and the
   new entry gets a newly allocated array to hold the options of the new
   tracer being added.

   The element in each entry of the tracer's option array holds a
   pointer back to the trace_array, a pointer to the tracer it is
   associated to, a pointer to the flags of the option.

   The issue is that these arrays are freed when the trace_array is
   freed when its instance it represents is removed from the instances
   directory. There's a race that an open of one of these options files
   can happen when the instance is being removed.

   Add a new helper function to be called by the open function of the
   options file to iterate all existing trace_arrays under a lock and
   find the one that has the given option element in one of it's tracer
   arrays. If found, then update the associated trace_array's reference
   counter to keep it from being freed. If not found, have the open call
   return -ENODEV.

 - Disable interrupts when acquiring the lock in rb_wake_up_waiters()

   The function rb_wake_up_waiters() assumes it will be called in
   interrupt context and does not disable irqs when taking
   cpu_buffer->reader_lock, which can be called in hard interrupt
   context. The issue is in PREEMPT_RT, this function is called in
   thread context leaving this lock open to a deadlock.

   Take the lock with interrupts disabled.

 - Use rcu_assign_pointer() for tmp_ops filter hash

   The tmp_ops used in update_ftrace_direct_mod() assigns its
   filter_hash field directly, but that field is annotated as __rcu and
   sparse complains. Assign it with rcu_assign_pointer()

 - Fix use-after-free in enable_trigger_private_data_free()

   The trace_event_call is accessed through the event_trigger_data's
   trace_event_file pointer to put the trace_event_call on freeing. The
   issue is that the trace_event_file data may have been freed already
   causing a use-after-free. Add a field to the event_trigger_data that
   points directly to the trace_event_call so that it can decrement its
   reference directly without needing to go through the
   trace_event_file.

 - Fix accounting of buffer data remote headers

   trace_buffer_desc_size() and trace_remote_alloc_buffer() undercount
   the number of pages is needed for the asked for size as it doesn't
   take into account the meta data on each page. Add a helper function
   to do the calculation properly and use that in these functions.

 - Catch nr_page_va overflow in ring_buffer_desc sizing

   The number of pages per remote ring buffer is capped by
   ring_buffer_desc::nr_page_va (32 bits). A buffer_size large enough to
   overflow that field would silently allocate a descriptor smaller than
   what was asked for.

 - Do not resize the subbuf order if any per_cpu buffer is disabled

   The mmapping of ring buffers disables resizing the subbuffers, but it
   is done per-cpu whereas the subbuf size change is done for all the
   per_cpu buffers under the buffer->mutex. It could change the size of
   some while the mapping is happening on others. Have the resize of the
   subbuf order check all the per_cpu buffers under the lock to see if
   any of them is disabled before starting and causing an inconsistency
   between buffers that are being mapped.

* tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (25 commits)
  ring-buffer: Check resize_disabled before publishing the new subbuf order
  tracing/remotes: Catch nr_page_va overflow in ring_buffer_desc sizing
  tracing/remotes: Account for ring buffer page header in size calculation
  tracing: Don't dereference trace_event_file in deferred trigger free
  ftrace: Use rcu_assign_pointer() for tmp_ops filter hash
  ring-buffer: Acquire the lock with irqsave in rb_wake_up_waiters()
  tracing: Take trace_array reference when opening a tracer options file
  tracing: Fix ring_buffer_read_page_size() kernel-doc
  tracing: Restore :mod: trailer after parsing in ftrace_set_clr_event()
  tracing: Fix memory corruption from a "STACKTRACE" histogram key
  tracing: Fix memory corruption from the histogram stacktrace modifier
  tracing: Undo the registration when enabling the histogram trigger fails
  tracing: Take the reference before publishing the named histogram trigger
  tracing: Set the trace clock before registering the histogram trigger
  tracing: Fix typo "preceeded" in comment
  tracing: Fix typo "availabe" in comment
  tracing: Let histogram values keep the percent and graph modifiers
  tracing: Keep the entry count when the histogram stats allocation fails
  tracing: Free histogram the field rejected for a bad modifier
  tracing: Free histogram the var ref when its initialization fails
  ...

1 files changed, 1695 insertions, 0 deletions

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
new file mode 100644
index 000000000..a24cc8ee1
--- /dev/null
+++ b/net/ipv4/ip_output.c
@@ -0,0 +1,1695 @@
+// 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/flow.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/gso.h>
+#include <net/inetpeer.h>
+#include <net/lwtunnel.h>
+#include <net/inet_dscp.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>
+#include <net/psp.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);
+
+	IP_INC_STATS(net, IPSTATS_MIB_OUTREQUESTS);
+
+	iph_set_totlen(iph, 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_dev(skb),
+		       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(const struct inet_sock *inet,
+				const struct dst_entry *dst)
+{
+	int ttl = READ_ONCE(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)
+{
+	const 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)get_random_u16();
+		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 = READ_ONCE(sk->sk_priority);
+	if (!skb->mark)
+		skb->mark = READ_ONCE(sk->sk_mark);
+
+	/* Send it out. */
+	return ip_local_out(net, skb->sk, skb);
+}
+
+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 = dst_rtable(dst);
+	struct net_device *dev = dst_dev(dst);
+	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);
+
+	/* OUTOCTETS should be counted after fragment */
+	IP_UPD_PO_STATS(net, IPSTATS_MIB_OUT, 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 != LWTUNNEL_XMIT_CONTINUE)
+			return res;
+	}
+
+	rcu_read_lock();
+	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();
+		return res;
+	}
+	rcu_read_unlock();
+
+	net_dbg_ratelimited("%s: No header cache and no neighbour!\n",
+			    __func__);
+	kfree_skb_reason(skb, SKB_DROP_REASON_NEIGH_CREATEFAIL);
+	return PTR_ERR(neigh);
+}
+
+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.
+	 */
+	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, *indev = skb->dev;
+	int ret_val;
+
+	rcu_read_lock();
+	dev = skb_dst_dev_rcu(skb);
+	skb->dev = dev;
+	skb->protocol = htons(ETH_P_IP);
+
+	ret_val = NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
+				net, sk, skb, indev, dev,
+				ip_finish_output,
+				!(IPCB(skb)->flags & IPSKB_REROUTED));
+	rcu_read_unlock();
+	return ret_val;
+}
+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 = dst_rtable(__sk_dst_check(sk, 0));
+	if (!rt) {
+		inet_sk_init_flowi4(inet, fl4);
+
+		/* sctp_v4_xmit() uses its own DSCP value */
+		fl4->flowi4_dscp = inet_dsfield_to_dscp(tos);
+
+		/* If this fails, retransmit mechanism of transport layer will
+		 * keep trying until route appears or the connection times
+		 * itself out.
+		 */
+		rt = ip_route_output_flow(net, fl4, sk);
+		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 = READ_ONCE(sk->sk_priority);
+	skb->mark = READ_ONCE(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, READ_ONCE(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;
+	u8 tstamp_type = skb->tstamp_type;
+	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;
+	if (mtu < hlen + 8) {
+		err = -EMSGSIZE;
+		goto fail;
+	}
+	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, tstamp_type);
+			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, tstamp_type);
+		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 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 = dst_rtable(cork->dst);
+	bool paged, hold_tskey = false, extra_uref = false;
+	unsigned int wmem_alloc_delta = 0;
+	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;
+
+	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),
+						    false);
+			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_to_msgzc(uarg)->zerocopy = 0;
+				skb_zcopy_set(skb, uarg, &extra_uref);
+			}
+		}
+	} else if ((flags & MSG_SPLICE_PAGES) && length) {
+		if (inet_test_bit(HDRINCL, sk))
+			return -EPERM;
+		if (rt->dst.dev->features & NETIF_F_SG &&
+		    getfrag == ip_generic_getfrag)
+			/* We need an empty buffer to attach stuff to */
+			paged = true;
+		else
+			flags &= ~MSG_SPLICE_PAGES;
+	}
+
+	cork->length += length;
+
+	if (cork->tx_flags & SKBTX_ANY_TSTAMP &&
+	    READ_ONCE(sk->sk_tsflags) & SOF_TIMESTAMPING_OPT_ID) {
+		if (cork->flags & IPCORK_TS_OPT_ID) {
+			tskey = cork->ts_opt_id;
+		} else {
+			tskey = atomic_inc_return(&sk->sk_tskey) - 1;
+			hold_tskey = true;
+		}
+	}
+
+	/* 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 {
+				alloclen = fragheaderlen + transhdrlen + fraggap;
+				pagedlen = datalen - transhdrlen - fraggap;
+			}
+
+			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 &&
+			    INDIRECT_CALL_1(getfrag, ip_generic_getfrag,
+					    from, data + transhdrlen, offset,
+					    copy, fraggap, skb) < 0) {
+				err = -EFAULT;
+				kfree_skb(skb);
+				goto error;
+			} else if (flags & MSG_SPLICE_PAGES) {
+				copy = 0;
+			}
+
+			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 (INDIRECT_CALL_1(getfrag, ip_generic_getfrag,
+					    from, skb_put(skb, copy),
+					    offset, copy, off, skb) < 0) {
+				__skb_trim(skb, off);
+				err = -EFAULT;
+				goto error;
+			}
+		} else if (flags & MSG_SPLICE_PAGES) {
+			struct msghdr *msg = from;
+
+			err = -EIO;
+			if (WARN_ON_ONCE(copy > msg->msg_iter.count))
+				goto error;
+
+			err = skb_splice_from_iter(skb, &msg->msg_iter, copy);
+			if (err < 0)
+				goto error;
+			copy = err;
+			if (!(flags & MSG_NO_SHARED_FRAGS))
+				skb_shinfo(skb)->flags |= SKBFL_SHARED_FRAG;
+			wmem_alloc_delta += copy;
+		} 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 (INDIRECT_CALL_1(getfrag, ip_generic_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);
+	if (hold_tskey)
+		atomic_dec(&sk->sk_tskey);
+	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;
+
+	cork->fragsize = ip_sk_use_pmtu(sk) ?
+			 dst4_mtu(&rt->dst) : READ_ONCE(rt->dst.dev->mtu);
+	cork->fragsize = min(cork->fragsize, IP_MAX_MTU);
+
+	if (!inetdev_valid_mtu(cork->fragsize))
+		return -ENETUNREACH;
+
+	/*
+	 * 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->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->sockc.priority;
+	cork->transmit_time = ipc->sockc.transmit_time;
+	cork->tx_flags = 0;
+	sock_tx_timestamp(sk, &ipc->sockc, &cork->tx_flags);
+	if (ipc->sockc.tsflags & SOCKCM_FLAG_TS_OPT_ID) {
+		cork->flags |= IPCORK_TS_OPT_ID;
+		cork->ts_opt_id = ipc->sockc.ts_opt_id;
+	}
+
+	return 0;
+}
+
+/*
+ *	ip_append_data() can make one large IP datagram from many pieces of
+ *	data.  Each piece will be held 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);
+}
+
+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 = dst_rtable(cork->dst);
+	struct iphdr *iph;
+	u8 pmtudisc, ttl;
+	__be16 df = 0;
+
+	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. */
+	pmtudisc = READ_ONCE(inet->pmtudisc);
+	if (pmtudisc == IP_PMTUDISC_DO ||
+	    pmtudisc == IP_PMTUDISC_PROBE ||
+	    (skb->len <= dst4_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 = READ_ONCE(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 : READ_ONCE(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->priority;
+	skb->mark = cork->mark;
+	if (sk_is_tcp(sk))
+		skb_set_delivery_time(skb, cork->transmit_time, SKB_CLOCK_MONOTONIC);
+	else
+		skb_set_delivery_type_by_clockid(skb, cork->transmit_time, sk->sk_clockid);
+	/*
+	 * 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) {
+		u8 icmp_type;
+
+		/* For such sockets, transhdrlen is zero when do ip_append_data(),
+		 * so icmphdr does not in skb linear region and can not get icmp_type
+		 * by icmp_hdr(skb)->type.
+		 */
+		if (sk->sk_type == SOCK_RAW &&
+		    !(fl4->flowi4_flags & FLOWI_FLAG_KNOWN_NH))
+			icmp_type = fl4->fl4_icmp_type;
+		else
+			icmp_type = icmp_hdr(skb)->type;
+		icmp_out_count(net, icmp_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, const struct sock *orig_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, u32 txhash)
+{
+	DEFINE_RAW_FLEX(struct ip_options_rcu, replyopts, opt.__data,
+			IP_OPTIONS_DATA_FIXED_SIZE);
+	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, skb, sopt))
+		return;
+
+	ipcm_init(&ipc);
+	ipc.addr = daddr;
+	ipc.sockc.transmit_time = transmit_time;
+
+	if (replyopts->opt.optlen) {
+		ipc.opt = replyopts;
+
+		if (replyopts->opt.srr)
+			daddr = replyopts->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,
+			   arg->tos & INET_DSCP_MASK,
+			   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;
+
+	sk->sk_protocol = ip_hdr(skb)->protocol;
+	sk->sk_bound_dev_if = arg->bound_dev_if;
+	sk->sk_sndbuf = READ_ONCE(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;
+		if (orig_sk) {
+			skb_set_owner_edemux(nskb, (struct sock *)orig_sk);
+			psp_reply_set_decrypted(orig_sk, nskb);
+		}
+		if (transmit_time)
+			nskb->tstamp_type = SKB_CLOCK_MONOTONIC;
+		if (txhash)
+			skb_set_hash(nskb, txhash, PKT_HASH_TYPE_L4);
+		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
+}