diff options
Diffstat (limited to 'net/ipv4/ip_output.c')
| -rw-r--r-- | net/ipv4/ip_output.c | 1543 |
1 files changed, 1543 insertions, 0 deletions
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c new file mode 100644 index 00000000..51a3eec2 --- /dev/null +++ b/net/ipv4/ip_output.c @@ -0,0 +1,1543 @@ +/* + * INET An implementation of the TCP/IP protocol suite for the LINUX + * operating system. INET is implemented using the BSD Socket + * interface as the means of communication with the user level. + * + * The Internet Protocol (IP) output module. + * + * Authors: Ross Biro + * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> + * Donald Becker, <becker@super.org> + * Alan Cox, <Alan.Cox@linux.org> + * Richard Underwood + * Stefan Becker, <stefanb@yello.ping.de> + * Jorge Cwik, <jorge@laser.satlink.net> + * Arnt Gulbrandsen, <agulbra@nvg.unit.no> + * Hirokazu Takahashi, <taka@valinux.co.jp> + * + * See ip_input.c for original log + * + * Fixes: + * Alan Cox : Missing nonblock feature in ip_build_xmit. + * Mike Kilburn : htons() missing in ip_build_xmit. + * Bradford Johnson: Fix faulty handling of some frames when + * no route is found. + * Alexander Demenshin: Missing sk/skb free in ip_queue_xmit + * (in case if packet not accepted by + * output firewall rules) + * Mike McLagan : Routing by source + * Alexey Kuznetsov: use new route cache + * Andi Kleen: Fix broken PMTU recovery and remove + * some redundant tests. + * Vitaly E. Lavrov : Transparent proxy revived after year coma. + * Andi Kleen : Replace ip_reply with ip_send_reply. + * Andi Kleen : Split fast and slow ip_build_xmit path + * for decreased register pressure on x86 + * and more readibility. + * Marc Boucher : When call_out_firewall returns FW_QUEUE, + * silently drop skb instead of failing with -EPERM. + * Detlev Wengorz : Copy protocol for fragments. + * Hirokazu Takahashi: HW checksumming for outgoing UDP + * datagrams. + * Hirokazu Takahashi: sendfile() on UDP works now. + */ + +#include <asm/uaccess.h> +#include <asm/system.h> +#include <linux/module.h> +#include <linux/types.h> +#include <linux/kernel.h> +#include <linux/mm.h> +#include <linux/string.h> +#include <linux/errno.h> +#include <linux/highmem.h> +#include <linux/slab.h> + +#include <linux/socket.h> +#include <linux/sockios.h> +#include <linux/in.h> +#include <linux/inet.h> +#include <linux/netdevice.h> +#include <linux/etherdevice.h> +#include <linux/proc_fs.h> +#include <linux/stat.h> +#include <linux/init.h> + +#include <net/snmp.h> +#include <net/ip.h> +#include <net/protocol.h> +#include <net/route.h> +#include <net/xfrm.h> +#include <linux/skbuff.h> +#include <net/sock.h> +#include <net/arp.h> +#include <net/icmp.h> +#include <net/checksum.h> +#include <net/inetpeer.h> +#include <linux/igmp.h> +#include <linux/netfilter_ipv4.h> +#include <linux/netfilter_bridge.h> +#include <linux/mroute.h> +#include <linux/netlink.h> +#include <linux/tcp.h> + +int sysctl_ip_default_ttl __read_mostly = IPDEFTTL; +EXPORT_SYMBOL(sysctl_ip_default_ttl); + +/* Generate a checksum for an outgoing IP datagram. */ +__inline__ 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 sk_buff *skb) +{ + struct iphdr *iph = ip_hdr(skb); + + iph->tot_len = htons(skb->len); + ip_send_check(iph); + return nf_hook(NFPROTO_IPV4, NF_INET_LOCAL_OUT, skb, NULL, + skb_dst(skb)->dev, dst_output); +} + +int ip_local_out(struct sk_buff *skb) +{ + int err; + + err = __ip_local_out(skb); + if (likely(err == 1)) + err = dst_output(skb); + + return err; +} +EXPORT_SYMBOL_GPL(ip_local_out); + +/* dev_loopback_xmit for use with netfilter. */ +static int ip_dev_loopback_xmit(struct sk_buff *newskb) +{ + skb_reset_mac_header(newskb); + __skb_pull(newskb, skb_network_offset(newskb)); + newskb->pkt_type = PACKET_LOOPBACK; + newskb->ip_summed = CHECKSUM_UNNECESSARY; + WARN_ON(!skb_dst(newskb)); + netif_rx_ni(newskb); + return 0; +} + +static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst) +{ + int ttl = inet->uc_ttl; + + if (ttl < 0) + ttl = ip4_dst_hoplimit(dst); + return ttl; +} + +/* + * Add an ip header to a skbuff and send it out. + * + */ +int ip_build_and_send_pkt(struct sk_buff *skb, struct sock *sk, + __be32 saddr, __be32 daddr, struct ip_options_rcu *opt) +{ + struct inet_sock *inet = inet_sk(sk); + struct rtable *rt = skb_rtable(skb); + struct iphdr *iph; + + /* Build the IP header. */ + skb_push(skb, sizeof(struct iphdr) + (opt ? opt->opt.optlen : 0)); + skb_reset_network_header(skb); + iph = ip_hdr(skb); + iph->version = 4; + iph->ihl = 5; + iph->tos = inet->tos; + if (ip_dont_fragment(sk, &rt->dst)) + iph->frag_off = htons(IP_DF); + else + iph->frag_off = 0; + 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; + ip_select_ident(iph, &rt->dst, sk); + + if (opt && opt->opt.optlen) { + iph->ihl += opt->opt.optlen>>2; + ip_options_build(skb, &opt->opt, daddr, rt, 0); + } + + skb->priority = sk->sk_priority; + skb->mark = sk->sk_mark; + + /* Send it out. */ + return ip_local_out(skb); +} +EXPORT_SYMBOL_GPL(ip_build_and_send_pkt); + +static inline int ip_finish_output2(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; + int res; + + if (rt->rt_type == RTN_MULTICAST) { + IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUTMCAST, skb->len); + } else if (rt->rt_type == RTN_BROADCAST) + IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUTBCAST, skb->len); + + /* Be paranoid, rather than too clever. */ + if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) { + struct sk_buff *skb2; + + skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev)); + if (skb2 == NULL) { + kfree_skb(skb); + return -ENOMEM; + } + if (skb->sk) + skb_set_owner_w(skb2, skb->sk); + kfree_skb(skb); + skb = skb2; + } + + rcu_read_lock(); + if (dst->hh) { + int res = neigh_hh_output(dst->hh, skb); + + rcu_read_unlock(); + return res; + } else { + neigh = dst_get_neighbour(dst); + if (neigh) { + res = neigh->output(skb); + + rcu_read_unlock(); + return res; + } + rcu_read_unlock(); + } + + if (net_ratelimit()) + printk(KERN_DEBUG "ip_finish_output2: No header cache and no neighbour!\n"); + kfree_skb(skb); + return -EINVAL; +} + +static inline int ip_skb_dst_mtu(struct sk_buff *skb) +{ + struct inet_sock *inet = skb->sk ? inet_sk(skb->sk) : NULL; + + return (inet && inet->pmtudisc == IP_PMTUDISC_PROBE) ? + skb_dst(skb)->dev->mtu : dst_mtu(skb_dst(skb)); +} + +static int ip_finish_output(struct sk_buff *skb) +{ +#if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM) + /* Policy lookup after SNAT yielded a new policy */ + if (skb_dst(skb)->xfrm != NULL) { + IPCB(skb)->flags |= IPSKB_REROUTED; + return dst_output(skb); + } +#endif + if (skb->len > ip_skb_dst_mtu(skb) && !skb_is_gso(skb)) + return ip_fragment(skb, ip_finish_output2); + else + return ip_finish_output2(skb); +} + +int ip_mc_output(struct sk_buff *skb) +{ + struct sock *sk = skb->sk; + struct rtable *rt = skb_rtable(skb); + struct net_device *dev = rt->dst.dev; + + /* + * If the indicated interface is up and running, send the packet. + */ + IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len); + + skb->dev = dev; + skb->protocol = htons(ETH_P_IP); + + /* + * Multicasts are looped back for other local users + */ + + if (rt->rt_flags&RTCF_MULTICAST) { + if (sk_mc_loop(sk) +#ifdef CONFIG_IP_MROUTE + /* Small optimization: do not loopback not local frames, + which returned after forwarding; they will be dropped + by ip_mr_input in any case. + Note, that local frames are looped back to be delivered + to local recipients. + + This check is duplicated in ip_mr_input at the moment. + */ + && + ((rt->rt_flags & RTCF_LOCAL) || + !(IPCB(skb)->flags & IPSKB_FORWARDED)) +#endif + ) { + struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC); + if (newskb) + NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, + newskb, NULL, newskb->dev, + ip_dev_loopback_xmit); + } + + /* 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, newskb, + NULL, newskb->dev, ip_dev_loopback_xmit); + } + + return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb, NULL, + skb->dev, ip_finish_output, + !(IPCB(skb)->flags & IPSKB_REROUTED)); +} + +int ip_output(struct sk_buff *skb) +{ + struct net_device *dev = skb_dst(skb)->dev; + + IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len); + + skb->dev = dev; + skb->protocol = htons(ETH_P_IP); + + return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb, NULL, dev, + ip_finish_output, + !(IPCB(skb)->flags & IPSKB_REROUTED)); +} + +int ip_queue_xmit(struct sk_buff *skb, struct flowi *fl) +{ + struct sock *sk = skb->sk; + struct inet_sock *inet = inet_sk(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 != NULL) + goto packet_routed; + + /* Make sure we can route this packet. */ + rt = (struct rtable *)__sk_dst_check(sk, 0); + if (rt == NULL) { + __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(sock_net(sk), fl4, sk, + daddr, inet->inet_saddr, + inet->inet_dport, + inet->inet_sport, + sk->sk_protocol, + RT_CONN_FLAGS(sk), + 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 && fl4->daddr != rt->rt_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) | (inet->tos & 0xff)); + if (ip_dont_fragment(sk, &rt->dst) && !skb->local_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; + iph->saddr = fl4->saddr; + iph->daddr = fl4->daddr; + /* Transport layer set skb->h.foo itself. */ + + if (inet_opt && inet_opt->opt.optlen) { + iph->ihl += inet_opt->opt.optlen >> 2; + ip_options_build(skb, &inet_opt->opt, inet->inet_daddr, rt, 0); + } + + ip_select_ident_more(iph, &rt->dst, sk, + (skb_shinfo(skb)->gso_segs ?: 1) - 1); + + skb->priority = sk->sk_priority; + skb->mark = sk->sk_mark; + + res = ip_local_out(skb); + rcu_read_unlock(); + return res; + +no_route: + rcu_read_unlock(); + IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES); + kfree_skb(skb); + return -EHOSTUNREACH; +} +EXPORT_SYMBOL(ip_queue_xmit); + + +static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from) +{ + to->pkt_type = from->pkt_type; + to->priority = from->priority; + to->protocol = from->protocol; + skb_dst_drop(to); + skb_dst_copy(to, from); + to->dev = from->dev; + to->mark = from->mark; + + /* Copy the flags to each fragment. */ + IPCB(to)->flags = IPCB(from)->flags; + +#ifdef CONFIG_NET_SCHED + to->tc_index = from->tc_index; +#endif + nf_copy(to, from); +#if defined(CONFIG_NETFILTER_XT_TARGET_TRACE) || \ + defined(CONFIG_NETFILTER_XT_TARGET_TRACE_MODULE) + to->nf_trace = from->nf_trace; +#endif +#if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE) + to->ipvs_property = from->ipvs_property; +#endif + skb_copy_secmark(to, from); +} + +/* + * 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_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *)) +{ + struct iphdr *iph; + int ptr; + struct net_device *dev; + struct sk_buff *skb2; + unsigned int mtu, hlen, left, len, ll_rs; + int offset; + __be16 not_last_frag; + struct rtable *rt = skb_rtable(skb); + int err = 0; + + dev = rt->dst.dev; + + /* + * Point into the IP datagram header. + */ + + iph = ip_hdr(skb); + + if (unlikely((iph->frag_off & htons(IP_DF)) && !skb->local_df)) { + IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); + icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, + htonl(ip_skb_dst_mtu(skb))); + kfree_skb(skb); + return -EMSGSIZE; + } + + /* + * Setup starting values. + */ + + hlen = iph->ihl * 4; + mtu = dst_mtu(&rt->dst) - hlen; /* Size of data space */ +#ifdef CONFIG_BRIDGE_NETFILTER + if (skb->nf_bridge) + mtu -= nf_bridge_mtu_reduction(skb); +#endif + IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE; + + /* 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; + int first_len = skb_pagelen(skb); + + if (first_len - hlen > mtu || + ((first_len - hlen) & 7) || + (iph->frag_off & htons(IP_MF|IP_OFFSET)) || + skb_cloned(skb)) + goto slow_path; + + skb_walk_frags(skb, frag) { + /* Correct geometry. */ + if (frag->len > mtu || + ((frag->len & 7) && frag->next) || + skb_headroom(frag) < hlen) + goto slow_path_clean; + + /* Partially cloned skb? */ + if (skb_shared(frag)) + goto slow_path_clean; + + BUG_ON(frag->sk); + if (skb->sk) { + frag->sk = skb->sk; + frag->destructor = sock_wfree; + } + skb->truesize -= frag->truesize; + } + + /* Everything is OK. Generate! */ + + err = 0; + offset = 0; + frag = skb_shinfo(skb)->frag_list; + skb_frag_list_init(skb); + skb->data_len = first_len - skb_headlen(skb); + skb->len = first_len; + iph->tot_len = htons(first_len); + iph->frag_off = htons(IP_MF); + ip_send_check(iph); + + for (;;) { + /* Prepare header of the next frame, + * before previous one went down. */ + if (frag) { + frag->ip_summed = CHECKSUM_NONE; + skb_reset_transport_header(frag); + __skb_push(frag, hlen); + skb_reset_network_header(frag); + memcpy(skb_network_header(frag), iph, hlen); + iph = ip_hdr(frag); + iph->tot_len = htons(frag->len); + ip_copy_metadata(frag, skb); + if (offset == 0) + ip_options_fragment(frag); + offset += skb->len - hlen; + iph->frag_off = htons(offset>>3); + if (frag->next != NULL) + iph->frag_off |= htons(IP_MF); + /* Ready, complete checksum */ + ip_send_check(iph); + } + + err = output(skb); + + if (!err) + IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES); + if (err || !frag) + break; + + skb = frag; + frag = skb->next; + skb->next = NULL; + } + + if (err == 0) { + IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS); + return 0; + } + + while (frag) { + skb = frag->next; + kfree_skb(frag); + frag = skb; + } + IP_INC_STATS(dev_net(dev), 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: + left = skb->len - hlen; /* Space per frame */ + ptr = hlen; /* Where to start from */ + + /* for bridged IP traffic encapsulated inside f.e. a vlan header, + * we need to make room for the encapsulating header + */ + ll_rs = LL_RESERVED_SPACE_EXTRA(rt->dst.dev, nf_bridge_pad(skb)); + + /* + * Fragment the datagram. + */ + + offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3; + not_last_frag = iph->frag_off & htons(IP_MF); + + /* + * Keep copying data until we run out. + */ + + while (left > 0) { + len = left; + /* IF: it doesn't fit, use 'mtu' - the data space left */ + if (len > mtu) + len = mtu; + /* IF: we are not sending up to and including the packet end + then align the next start on an eight byte boundary */ + if (len < left) { + len &= ~7; + } + /* + * Allocate buffer. + */ + + if ((skb2 = alloc_skb(len+hlen+ll_rs, GFP_ATOMIC)) == NULL) { + NETDEBUG(KERN_INFO "IP: frag: no memory for new fragment!\n"); + err = -ENOMEM; + goto fail; + } + + /* + * Set up data on packet + */ + + ip_copy_metadata(skb2, skb); + skb_reserve(skb2, ll_rs); + skb_put(skb2, len + hlen); + skb_reset_network_header(skb2); + skb2->transport_header = skb2->network_header + hlen; + + /* + * Charge the memory for the fragment to any owner + * it might possess + */ + + if (skb->sk) + skb_set_owner_w(skb2, skb->sk); + + /* + * Copy the packet header into the new buffer. + */ + + skb_copy_from_linear_data(skb, skb_network_header(skb2), hlen); + + /* + * Copy a block of the IP datagram. + */ + if (skb_copy_bits(skb, ptr, skb_transport_header(skb2), len)) + BUG(); + left -= len; + + /* + * Fill in the new header fields. + */ + iph = ip_hdr(skb2); + iph->frag_off = htons((offset >> 3)); + + /* ANK: dirty, but effective trick. Upgrade options only if + * the segment to be fragmented was THE FIRST (otherwise, + * options are already fixed) and make it ONCE + * on the initial skb, so that all the following fragments + * will inherit fixed options. + */ + if (offset == 0) + ip_options_fragment(skb); + + /* + * Added AC : If we are fragmenting a fragment that's not the + * last fragment then keep MF on each bit + */ + if (left > 0 || not_last_frag) + iph->frag_off |= htons(IP_MF); + ptr += len; + offset += len; + + /* + * Put this fragment into the sending queue. + */ + iph->tot_len = htons(len + hlen); + + ip_send_check(iph); + + err = output(skb2); + if (err) + goto fail; + + IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES); + } + kfree_skb(skb); + IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS); + return err; + +fail: + kfree_skb(skb); + IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); + return err; +} +EXPORT_SYMBOL(ip_fragment); + +int +ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb) +{ + struct iovec *iov = from; + + if (skb->ip_summed == CHECKSUM_PARTIAL) { + if (memcpy_fromiovecend(to, iov, offset, len) < 0) + return -EFAULT; + } else { + __wsum csum = 0; + if (csum_partial_copy_fromiovecend(to, iov, offset, len, &csum) < 0) + return -EFAULT; + skb->csum = csum_block_add(skb->csum, csum, odd); + } + return 0; +} +EXPORT_SYMBOL(ip_generic_getfrag); + +static inline __wsum +csum_page(struct page *page, int offset, int copy) +{ + char *kaddr; + __wsum csum; + kaddr = kmap(page); + csum = csum_partial(kaddr + offset, copy, 0); + kunmap(page); + return csum; +} + +static inline int ip_ufo_append_data(struct sock *sk, + struct sk_buff_head *queue, + int getfrag(void *from, char *to, int offset, int len, + int odd, struct sk_buff *skb), + void *from, int length, int hh_len, int fragheaderlen, + int transhdrlen, int maxfraglen, unsigned int flags) +{ + struct sk_buff *skb; + int err; + + /* There is support for UDP fragmentation offload by network + * device, so create one single skb packet containing complete + * udp datagram + */ + if ((skb = skb_peek_tail(queue)) == NULL) { + skb = sock_alloc_send_skb(sk, + hh_len + fragheaderlen + transhdrlen + 20, + (flags & MSG_DONTWAIT), &err); + + if (skb == NULL) + return err; + + /* reserve space for Hardware header */ + skb_reserve(skb, hh_len); + + /* create space for UDP/IP header */ + skb_put(skb, fragheaderlen + transhdrlen); + + /* initialize network header pointer */ + skb_reset_network_header(skb); + + /* initialize protocol header pointer */ + skb->transport_header = skb->network_header + fragheaderlen; + + skb->ip_summed = CHECKSUM_PARTIAL; + skb->csum = 0; + + /* specify the length of each IP datagram fragment */ + skb_shinfo(skb)->gso_size = maxfraglen - fragheaderlen; + skb_shinfo(skb)->gso_type = SKB_GSO_UDP; + __skb_queue_tail(queue, skb); + } + + return skb_append_datato_frags(sk, skb, getfrag, from, + (length - transhdrlen)); +} + +static int __ip_append_data(struct sock *sk, + struct flowi4 *fl4, + struct sk_buff_head *queue, + struct inet_cork *cork, + 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 sk_buff *skb; + + struct ip_options *opt = cork->opt; + int hh_len; + int exthdrlen; + int mtu; + int copy; + int err; + int offset = 0; + unsigned int maxfraglen, fragheaderlen; + int csummode = CHECKSUM_NONE; + struct rtable *rt = (struct rtable *)cork->dst; + + skb = skb_peek_tail(queue); + + exthdrlen = !skb ? rt->dst.header_len : 0; + mtu = cork->fragsize; + + hh_len = LL_RESERVED_SPACE(rt->dst.dev); + + fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0); + maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen; + + if (cork->length + length > 0xFFFF - fragheaderlen) { + ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport, + mtu-exthdrlen); + 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_V4_CSUM && + !exthdrlen) + csummode = CHECKSUM_PARTIAL; + + cork->length += length; + if (((length > mtu) || (skb && skb_is_gso(skb))) && + (sk->sk_protocol == IPPROTO_UDP) && + (rt->dst.dev->features & NETIF_F_UFO) && !rt->dst.header_len) { + err = ip_ufo_append_data(sk, queue, getfrag, from, length, + hh_len, fragheaderlen, transhdrlen, + maxfraglen, flags); + if (err) + goto error; + return 0; + } + + /* 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; + 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; + + if ((flags & MSG_MORE) && + !(rt->dst.dev->features&NETIF_F_SG)) + alloclen = mtu; + else + alloclen = fraglen; + + alloclen += exthdrlen; + + /* The last fragment gets additional space at tail. + * Note, with MSG_MORE we overallocate on fragments, + * because we have no idea what fragment will be + * the last. + */ + if (datalen == length + fraggap) + alloclen += rt->dst.trailer_len; + + if (transhdrlen) { + skb = sock_alloc_send_skb(sk, + alloclen + hh_len + 15, + (flags & MSG_DONTWAIT), &err); + } else { + skb = NULL; + if (atomic_read(&sk->sk_wmem_alloc) <= + 2 * sk->sk_sndbuf) + skb = sock_wmalloc(sk, + alloclen + hh_len + 15, 1, + sk->sk_allocation); + if (unlikely(skb == NULL)) + err = -ENOBUFS; + else + /* only the initial fragment is + time stamped */ + cork->tx_flags = 0; + } + if (skb == NULL) + goto error; + + /* + * Fill in the control structures + */ + skb->ip_summed = csummode; + skb->csum = 0; + skb_reserve(skb, hh_len); + skb_shinfo(skb)->tx_flags = cork->tx_flags; + + /* + * Find where to start putting bytes. + */ + data = skb_put(skb, fraglen + exthdrlen); + 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, 0); + skb_prev->csum = csum_sub(skb_prev->csum, + skb->csum); + data += fraggap; + pskb_trim_unique(skb_prev, maxfraglen); + } + + copy = datalen - transhdrlen - fraggap; + if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) { + err = -EFAULT; + kfree_skb(skb); + goto error; + } + + offset += copy; + length -= datalen - fraggap; + transhdrlen = 0; + exthdrlen = 0; + csummode = CHECKSUM_NONE; + + /* + * Put the packet on the pending queue. + */ + __skb_queue_tail(queue, skb); + continue; + } + + if (copy > length) + copy = length; + + if (!(rt->dst.dev->features&NETIF_F_SG)) { + 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 { + int i = skb_shinfo(skb)->nr_frags; + skb_frag_t *frag = &skb_shinfo(skb)->frags[i-1]; + struct page *page = cork->page; + int off = cork->off; + unsigned int left; + + if (page && (left = PAGE_SIZE - off) > 0) { + if (copy >= left) + copy = left; + if (page != frag->page) { + if (i == MAX_SKB_FRAGS) { + err = -EMSGSIZE; + goto error; + } + get_page(page); + skb_fill_page_desc(skb, i, page, off, 0); + frag = &skb_shinfo(skb)->frags[i]; + } + } else if (i < MAX_SKB_FRAGS) { + if (copy > PAGE_SIZE) + copy = PAGE_SIZE; + page = alloc_pages(sk->sk_allocation, 0); + if (page == NULL) { + err = -ENOMEM; + goto error; + } + cork->page = page; + cork->off = 0; + + skb_fill_page_desc(skb, i, page, 0, 0); + frag = &skb_shinfo(skb)->frags[i]; + } else { + err = -EMSGSIZE; + goto error; + } + if (getfrag(from, page_address(frag->page)+frag->page_offset+frag->size, offset, copy, skb->len, skb) < 0) { + err = -EFAULT; + goto error; + } + cork->off += copy; + frag->size += copy; + skb->len += copy; + skb->data_len += copy; + skb->truesize += copy; + atomic_add(copy, &sk->sk_wmem_alloc); + } + offset += copy; + length -= copy; + } + + return 0; + +error: + cork->length -= length; + IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS); + return err; +} + +static int ip_setup_cork(struct sock *sk, struct inet_cork *cork, + struct ipcm_cookie *ipc, struct rtable **rtp) +{ + struct inet_sock *inet = inet_sk(sk); + struct ip_options_rcu *opt; + struct rtable *rt; + + /* + * setup for corking. + */ + opt = ipc->opt; + if (opt) { + if (cork->opt == NULL) { + cork->opt = kmalloc(sizeof(struct ip_options) + 40, + sk->sk_allocation); + if (unlikely(cork->opt == NULL)) + return -ENOBUFS; + } + memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen); + cork->flags |= IPCORK_OPT; + cork->addr = ipc->addr; + } + rt = *rtp; + if (unlikely(!rt)) + return -EFAULT; + /* + * We steal reference to this route, caller should not release it + */ + *rtp = NULL; + cork->fragsize = inet->pmtudisc == IP_PMTUDISC_PROBE ? + rt->dst.dev->mtu : dst_mtu(&rt->dst); + cork->dst = &rt->dst; + cork->length = 0; + cork->tx_flags = ipc->tx_flags; + cork->page = NULL; + cork->off = 0; + + return 0; +} + +/* + * ip_append_data() and ip_append_page() can make one large IP datagram + * from many pieces of data. Each pieces will be holded on the socket + * until ip_push_pending_frames() is called. Each piece can be a page + * or non-page data. + * + * Not only UDP, other transport protocols - e.g. raw sockets - can use + * this interface potentially. + * + * LATER: length must be adjusted by pad at tail, when it is required. + */ +int ip_append_data(struct sock *sk, struct flowi4 *fl4, + int getfrag(void *from, char *to, int offset, int len, + int odd, struct sk_buff *skb), + void *from, int length, int transhdrlen, + struct ipcm_cookie *ipc, struct rtable **rtp, + unsigned int flags) +{ + struct inet_sock *inet = inet_sk(sk); + int err; + + if (flags&MSG_PROBE) + return 0; + + if (skb_queue_empty(&sk->sk_write_queue)) { + err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp); + if (err) + return err; + } else { + transhdrlen = 0; + } + + return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base, getfrag, + from, length, transhdrlen, flags); +} + +ssize_t ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page, + int offset, size_t size, int flags) +{ + struct inet_sock *inet = inet_sk(sk); + struct sk_buff *skb; + struct rtable *rt; + struct ip_options *opt = NULL; + struct inet_cork *cork; + int hh_len; + int mtu; + int len; + int err; + unsigned int maxfraglen, fragheaderlen, fraggap; + + if (inet->hdrincl) + return -EPERM; + + if (flags&MSG_PROBE) + return 0; + + if (skb_queue_empty(&sk->sk_write_queue)) + return -EINVAL; + + cork = &inet->cork.base; + rt = (struct rtable *)cork->dst; + if (cork->flags & IPCORK_OPT) + opt = cork->opt; + + if (!(rt->dst.dev->features&NETIF_F_SG)) + return -EOPNOTSUPP; + + hh_len = LL_RESERVED_SPACE(rt->dst.dev); + mtu = cork->fragsize; + + fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0); + maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen; + + if (cork->length + size > 0xFFFF - fragheaderlen) { + ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport, mtu); + return -EMSGSIZE; + } + + if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL) + return -EINVAL; + + cork->length += size; + if ((size + skb->len > mtu) && + (sk->sk_protocol == IPPROTO_UDP) && + (rt->dst.dev->features & NETIF_F_UFO)) { + skb_shinfo(skb)->gso_size = mtu - fragheaderlen; + skb_shinfo(skb)->gso_type = SKB_GSO_UDP; + } + + + while (size > 0) { + int i; + + if (skb_is_gso(skb)) + len = size; + else { + + /* Check if the remaining data fits into current packet. */ + len = mtu - skb->len; + if (len < size) + len = maxfraglen - skb->len; + } + if (len <= 0) { + struct sk_buff *skb_prev; + int alloclen; + + skb_prev = skb; + fraggap = skb_prev->len - maxfraglen; + + alloclen = fragheaderlen + hh_len + fraggap + 15; + skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation); + if (unlikely(!skb)) { + err = -ENOBUFS; + goto error; + } + + /* + * Fill in the control structures + */ + skb->ip_summed = CHECKSUM_NONE; + skb->csum = 0; + skb_reserve(skb, hh_len); + + /* + * Find where to start putting bytes. + */ + skb_put(skb, fragheaderlen + fraggap); + skb_reset_network_header(skb); + skb->transport_header = (skb->network_header + + fragheaderlen); + if (fraggap) { + skb->csum = skb_copy_and_csum_bits(skb_prev, + maxfraglen, + skb_transport_header(skb), + fraggap, 0); + skb_prev->csum = csum_sub(skb_prev->csum, + skb->csum); + pskb_trim_unique(skb_prev, maxfraglen); + } + + /* + * Put the packet on the pending queue. + */ + __skb_queue_tail(&sk->sk_write_queue, skb); + continue; + } + + i = skb_shinfo(skb)->nr_frags; + if (len > size) + len = size; + if (skb_can_coalesce(skb, i, page, offset)) { + skb_shinfo(skb)->frags[i-1].size += len; + } else if (i < MAX_SKB_FRAGS) { + get_page(page); + skb_fill_page_desc(skb, i, page, offset, len); + } else { + err = -EMSGSIZE; + goto error; + } + + if (skb->ip_summed == CHECKSUM_NONE) { + __wsum csum; + csum = csum_page(page, offset, len); + skb->csum = csum_block_add(skb->csum, csum, skb->len); + } + + skb->len += len; + skb->data_len += len; + skb->truesize += len; + atomic_add(len, &sk->sk_wmem_alloc); + offset += len; + size -= len; + } + return 0; + +error: + cork->length -= size; + IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS); + return err; +} + +static void ip_cork_release(struct inet_cork *cork) +{ + cork->flags &= ~IPCORK_OPT; + kfree(cork->opt); + cork->opt = NULL; + dst_release(cork->dst); + cork->dst = NULL; +} + +/* + * Combined all pending IP fragments on the socket as one IP datagram + * and push them out. + */ +struct sk_buff *__ip_make_skb(struct sock *sk, + struct flowi4 *fl4, + struct sk_buff_head *queue, + struct inet_cork *cork) +{ + struct sk_buff *skb, *tmp_skb; + struct sk_buff **tail_skb; + struct inet_sock *inet = inet_sk(sk); + struct net *net = sock_net(sk); + struct ip_options *opt = NULL; + struct rtable *rt = (struct rtable *)cork->dst; + struct iphdr *iph; + __be16 df = 0; + __u8 ttl; + + if ((skb = __skb_dequeue(queue)) == NULL) + 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. + */ + if (inet->pmtudisc < IP_PMTUDISC_DO) + skb->local_df = 1; + + /* DF bit is set when we want to see DF on outgoing frames. + * If local_df is set too, we still allow to fragment this frame + * locally. */ + if (inet->pmtudisc >= IP_PMTUDISC_DO || + (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 (rt->rt_type == RTN_MULTICAST) + ttl = inet->mc_ttl; + else + ttl = ip_select_ttl(inet, &rt->dst); + + iph = (struct iphdr *)skb->data; + iph->version = 4; + iph->ihl = 5; + iph->tos = inet->tos; + iph->frag_off = df; + ip_select_ident(iph, &rt->dst, sk); + iph->ttl = ttl; + iph->protocol = sk->sk_protocol; + iph->saddr = fl4->saddr; + iph->daddr = fl4->daddr; + + if (opt) { + iph->ihl += opt->optlen>>2; + ip_options_build(skb, opt, cork->addr, rt, 0); + } + + skb->priority = sk->sk_priority; + skb->mark = sk->sk_mark; + /* + * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec + * on dst refcount + */ + cork->dst = NULL; + skb_dst_set(skb, &rt->dst); + + if (iph->protocol == IPPROTO_ICMP) + icmp_out_count(net, ((struct icmphdr *) + skb_transport_header(skb))->type); + + ip_cork_release(cork); +out: + return skb; +} + +int ip_send_skb(struct sk_buff *skb) +{ + struct net *net = sock_net(skb->sk); + int err; + + err = ip_local_out(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(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, + unsigned int flags) +{ + struct inet_cork cork; + 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, 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, 0); + 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 TCP resets so far. ICMP should use this function too. + * + * Should run single threaded per socket because it uses the sock + * structure to pass arguments. + */ +void ip_send_reply(struct sock *sk, struct sk_buff *skb, __be32 daddr, + struct ip_reply_arg *arg, unsigned int len) +{ + struct inet_sock *inet = inet_sk(sk); + struct ip_options_data replyopts; + struct ipcm_cookie ipc; + struct flowi4 fl4; + struct rtable *rt = skb_rtable(skb); + + if (ip_options_echo(&replyopts.opt.opt, skb)) + return; + + ipc.addr = daddr; + ipc.opt = NULL; + ipc.tx_flags = 0; + + if (replyopts.opt.opt.optlen) { + ipc.opt = &replyopts.opt; + + if (replyopts.opt.opt.srr) + daddr = replyopts.opt.opt.faddr; + } + + flowi4_init_output(&fl4, arg->bound_dev_if, 0, + RT_TOS(ip_hdr(skb)->tos), + RT_SCOPE_UNIVERSE, sk->sk_protocol, + ip_reply_arg_flowi_flags(arg), + daddr, rt->rt_spec_dst, + tcp_hdr(skb)->source, tcp_hdr(skb)->dest); + security_skb_classify_flow(skb, flowi4_to_flowi(&fl4)); + rt = ip_route_output_key(sock_net(sk), &fl4); + if (IS_ERR(rt)) + return; + + /* And let IP do all the hard work. + + This chunk is not reenterable, hence spinlock. + Note that it uses the fact, that this function is called + with locally disabled BH and that sk cannot be already spinlocked. + */ + bh_lock_sock(sk); + inet->tos = ip_hdr(skb)->tos; + sk->sk_priority = skb->priority; + sk->sk_protocol = ip_hdr(skb)->protocol; + sk->sk_bound_dev_if = arg->bound_dev_if; + ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base, len, 0, + &ipc, &rt, MSG_DONTWAIT); + if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) { + if (arg->csumoffset >= 0) + *((__sum16 *)skb_transport_header(skb) + + arg->csumoffset) = csum_fold(csum_add(skb->csum, + arg->csum)); + skb->ip_summed = CHECKSUM_NONE; + ip_push_pending_frames(sk, &fl4); + } + + bh_unlock_sock(sk); + + ip_rt_put(rt); +} + +void __init ip_init(void) +{ + ip_rt_init(); + inet_initpeers(); + +#if defined(CONFIG_IP_MULTICAST) && defined(CONFIG_PROC_FS) + igmp_mc_proc_init(); +#endif +} |