From ace9429bb58fd418f0c81d4c2835699bddf6bde6 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Thu, 11 Apr 2024 10:27:49 +0200 Subject: Adding upstream version 6.6.15. Signed-off-by: Daniel Baumann --- net/ipv4/ip_output.c | 1663 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 1663 insertions(+) create mode 100644 net/ipv4/ip_output.c (limited to 'net/ipv4/ip_output.c') diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c new file mode 100644 index 000000000..4ab877cf6 --- /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, + * Donald Becker, + * Alan Cox, + * Richard Underwood + * Stefan Becker, + * Jorge Cwik, + * Arnt Gulbrandsen, + * Hirokazu Takahashi, + * + * 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 +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +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, + ¤t->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 +} -- cgit v1.2.3