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-rw-r--r--net/ipv4/ip_output.c1663
1 files changed, 1663 insertions, 0 deletions
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
new file mode 100644
index 0000000000..4ab877cf6d
--- /dev/null
+++ b/net/ipv4/ip_output.c
@@ -0,0 +1,1663 @@
+// 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/gso.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_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(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(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);
+}
+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);
+
+ /* 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 = skb_dst(skb)->dev, *indev = skb->dev;
+
+ 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 = 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, 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 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_TSTAMP &&
+ READ_ONCE(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_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;
+
+ /* 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;
+ 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;
+ /* [!] NOTE: copy will be negative if pagedlen>0
+ * because then the equation reduces to -fraggap.
+ */
+ if (copy > 0 && 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 (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,
+ sk->sk_allocation);
+ if (err < 0)
+ goto error;
+ copy = err;
+ 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 (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() 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 = (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) {
+ 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 &&
+ !inet_test_bit(HDRINCL, sk))
+ 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, 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)
+{
+ 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 = 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;
+ nskb->mono_delivery_time = !!transmit_time;
+ 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
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-16 15:42:23 +0000