| /* |
| * 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. |
| * |
| * Version: $Id: ip_output.c,v 1.100 2002/02/01 22:01:03 davem Exp $ |
| * |
| * 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/sched.h> |
| #include <linux/mm.h> |
| #include <linux/string.h> |
| #include <linux/errno.h> |
| #include <linux/config.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/tcp.h> |
| #include <net/udp.h> |
| #include <linux/skbuff.h> |
| #include <net/sock.h> |
| #include <net/arp.h> |
| #include <net/icmp.h> |
| #include <net/raw.h> |
| #include <net/checksum.h> |
| #include <net/inetpeer.h> |
| #include <net/checksum.h> |
| #include <linux/igmp.h> |
| #include <linux/netfilter_ipv4.h> |
| #include <linux/netfilter_bridge.h> |
| #include <linux/mroute.h> |
| #include <linux/netlink.h> |
| |
| /* |
| * Shall we try to damage output packets if routing dev changes? |
| */ |
| |
| int sysctl_ip_dynaddr; |
| int sysctl_ip_default_ttl = IPDEFTTL; |
| |
| /* 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); |
| } |
| |
| /* dev_loopback_xmit for use with netfilter. */ |
| static int ip_dev_loopback_xmit(struct sk_buff *newskb) |
| { |
| newskb->mac.raw = newskb->data; |
| __skb_pull(newskb, newskb->nh.raw - newskb->data); |
| newskb->pkt_type = PACKET_LOOPBACK; |
| newskb->ip_summed = CHECKSUM_UNNECESSARY; |
| BUG_TRAP(newskb->dst); |
| nf_reset(newskb); |
| netif_rx(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 = dst_metric(dst, RTAX_HOPLIMIT); |
| 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, |
| u32 saddr, u32 daddr, struct ip_options *opt) |
| { |
| struct inet_sock *inet = inet_sk(sk); |
| struct rtable *rt = (struct rtable *)skb->dst; |
| struct iphdr *iph; |
| |
| /* Build the IP header. */ |
| if (opt) |
| iph=(struct iphdr *)skb_push(skb,sizeof(struct iphdr) + opt->optlen); |
| else |
| iph=(struct iphdr *)skb_push(skb,sizeof(struct iphdr)); |
| |
| iph->version = 4; |
| iph->ihl = 5; |
| iph->tos = inet->tos; |
| if (ip_dont_fragment(sk, &rt->u.dst)) |
| iph->frag_off = htons(IP_DF); |
| else |
| iph->frag_off = 0; |
| iph->ttl = ip_select_ttl(inet, &rt->u.dst); |
| iph->daddr = rt->rt_dst; |
| iph->saddr = rt->rt_src; |
| iph->protocol = sk->sk_protocol; |
| iph->tot_len = htons(skb->len); |
| ip_select_ident(iph, &rt->u.dst, sk); |
| skb->nh.iph = iph; |
| |
| if (opt && opt->optlen) { |
| iph->ihl += opt->optlen>>2; |
| ip_options_build(skb, opt, daddr, rt, 0); |
| } |
| ip_send_check(iph); |
| |
| skb->priority = sk->sk_priority; |
| |
| /* Send it out. */ |
| return NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, skb, NULL, rt->u.dst.dev, |
| dst_output); |
| } |
| |
| static inline int ip_finish_output2(struct sk_buff *skb) |
| { |
| struct dst_entry *dst = skb->dst; |
| struct hh_cache *hh = dst->hh; |
| struct net_device *dev = dst->dev; |
| int hh_len = LL_RESERVED_SPACE(dev); |
| |
| /* Be paranoid, rather than too clever. */ |
| if (unlikely(skb_headroom(skb) < hh_len && dev->hard_header)) { |
| 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; |
| } |
| |
| nf_reset(skb); |
| |
| if (hh) { |
| int hh_alen; |
| |
| read_lock_bh(&hh->hh_lock); |
| hh_alen = HH_DATA_ALIGN(hh->hh_len); |
| memcpy(skb->data - hh_alen, hh->hh_data, hh_alen); |
| read_unlock_bh(&hh->hh_lock); |
| skb_push(skb, hh->hh_len); |
| return hh->hh_output(skb); |
| } else if (dst->neighbour) |
| return dst->neighbour->output(skb); |
| |
| if (net_ratelimit()) |
| printk(KERN_DEBUG "ip_finish_output2: No header cache and no neighbour!\n"); |
| kfree_skb(skb); |
| return -EINVAL; |
| } |
| |
| int ip_finish_output(struct sk_buff *skb) |
| { |
| struct net_device *dev = skb->dst->dev; |
| |
| skb->dev = dev; |
| skb->protocol = htons(ETH_P_IP); |
| |
| return NF_HOOK(PF_INET, NF_IP_POST_ROUTING, skb, NULL, dev, |
| ip_finish_output2); |
| } |
| |
| int ip_mc_output(struct sk_buff *skb) |
| { |
| struct sock *sk = skb->sk; |
| struct rtable *rt = (struct rtable*)skb->dst; |
| struct net_device *dev = rt->u.dst.dev; |
| |
| /* |
| * If the indicated interface is up and running, send the packet. |
| */ |
| IP_INC_STATS(IPSTATS_MIB_OUTREQUESTS); |
| |
| 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 || inet_sk(sk)->mc_loop) |
| #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(PF_INET, NF_IP_POST_ROUTING, newskb, NULL, |
| newskb->dev, |
| ip_dev_loopback_xmit); |
| } |
| |
| /* Multicasts with ttl 0 must not go beyond the host */ |
| |
| if (skb->nh.iph->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(PF_INET, NF_IP_POST_ROUTING, newskb, NULL, |
| newskb->dev, ip_dev_loopback_xmit); |
| } |
| |
| if (skb->len > dst_mtu(&rt->u.dst)) |
| return ip_fragment(skb, ip_finish_output); |
| else |
| return ip_finish_output(skb); |
| } |
| |
| int ip_output(struct sk_buff *skb) |
| { |
| IP_INC_STATS(IPSTATS_MIB_OUTREQUESTS); |
| |
| if (skb->len > dst_mtu(skb->dst) && !skb_shinfo(skb)->tso_size) |
| return ip_fragment(skb, ip_finish_output); |
| else |
| return ip_finish_output(skb); |
| } |
| |
| int ip_queue_xmit(struct sk_buff *skb, int ipfragok) |
| { |
| struct sock *sk = skb->sk; |
| struct inet_sock *inet = inet_sk(sk); |
| struct ip_options *opt = inet->opt; |
| struct rtable *rt; |
| struct iphdr *iph; |
| |
| /* Skip all of this if the packet is already routed, |
| * f.e. by something like SCTP. |
| */ |
| rt = (struct rtable *) skb->dst; |
| if (rt != NULL) |
| goto packet_routed; |
| |
| /* Make sure we can route this packet. */ |
| rt = (struct rtable *)__sk_dst_check(sk, 0); |
| if (rt == NULL) { |
| u32 daddr; |
| |
| /* Use correct destination address if we have options. */ |
| daddr = inet->daddr; |
| if(opt && opt->srr) |
| daddr = opt->faddr; |
| |
| { |
| struct flowi fl = { .oif = sk->sk_bound_dev_if, |
| .nl_u = { .ip4_u = |
| { .daddr = daddr, |
| .saddr = inet->saddr, |
| .tos = RT_CONN_FLAGS(sk) } }, |
| .proto = sk->sk_protocol, |
| .uli_u = { .ports = |
| { .sport = inet->sport, |
| .dport = inet->dport } } }; |
| |
| /* If this fails, retransmit mechanism of transport layer will |
| * keep trying until route appears or the connection times |
| * itself out. |
| */ |
| if (ip_route_output_flow(&rt, &fl, sk, 0)) |
| goto no_route; |
| } |
| __sk_dst_set(sk, &rt->u.dst); |
| tcp_v4_setup_caps(sk, &rt->u.dst); |
| } |
| skb->dst = dst_clone(&rt->u.dst); |
| |
| packet_routed: |
| if (opt && opt->is_strictroute && rt->rt_dst != rt->rt_gateway) |
| goto no_route; |
| |
| /* OK, we know where to send it, allocate and build IP header. */ |
| iph = (struct iphdr *) skb_push(skb, sizeof(struct iphdr) + (opt ? opt->optlen : 0)); |
| *((__u16 *)iph) = htons((4 << 12) | (5 << 8) | (inet->tos & 0xff)); |
| iph->tot_len = htons(skb->len); |
| if (ip_dont_fragment(sk, &rt->u.dst) && !ipfragok) |
| iph->frag_off = htons(IP_DF); |
| else |
| iph->frag_off = 0; |
| iph->ttl = ip_select_ttl(inet, &rt->u.dst); |
| iph->protocol = sk->sk_protocol; |
| iph->saddr = rt->rt_src; |
| iph->daddr = rt->rt_dst; |
| skb->nh.iph = iph; |
| /* Transport layer set skb->h.foo itself. */ |
| |
| if (opt && opt->optlen) { |
| iph->ihl += opt->optlen >> 2; |
| ip_options_build(skb, opt, inet->daddr, rt, 0); |
| } |
| |
| ip_select_ident_more(iph, &rt->u.dst, sk, skb_shinfo(skb)->tso_segs); |
| |
| /* Add an IP checksum. */ |
| ip_send_check(iph); |
| |
| skb->priority = sk->sk_priority; |
| |
| return NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, skb, NULL, rt->u.dst.dev, |
| dst_output); |
| |
| no_route: |
| IP_INC_STATS(IPSTATS_MIB_OUTNOROUTES); |
| kfree_skb(skb); |
| return -EHOSTUNREACH; |
| } |
| |
| |
| 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->security = from->security; |
| dst_release(to->dst); |
| to->dst = dst_clone(from->dst); |
| to->dev = from->dev; |
| |
| /* Copy the flags to each fragment. */ |
| IPCB(to)->flags = IPCB(from)->flags; |
| |
| #ifdef CONFIG_NET_SCHED |
| to->tc_index = from->tc_index; |
| #endif |
| #ifdef CONFIG_NETFILTER |
| to->nfmark = from->nfmark; |
| to->nfcache = from->nfcache; |
| /* Connection association is same as pre-frag packet */ |
| nf_conntrack_put(to->nfct); |
| to->nfct = from->nfct; |
| nf_conntrack_get(to->nfct); |
| to->nfctinfo = from->nfctinfo; |
| #ifdef CONFIG_BRIDGE_NETFILTER |
| nf_bridge_put(to->nf_bridge); |
| to->nf_bridge = from->nf_bridge; |
| nf_bridge_get(to->nf_bridge); |
| #endif |
| #endif |
| } |
| |
| /* |
| * 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 raw = 0; |
| int ptr; |
| struct net_device *dev; |
| struct sk_buff *skb2; |
| unsigned int mtu, hlen, left, len, ll_rs; |
| int offset; |
| int not_last_frag; |
| struct rtable *rt = (struct rtable*)skb->dst; |
| int err = 0; |
| |
| dev = rt->u.dst.dev; |
| |
| /* |
| * Point into the IP datagram header. |
| */ |
| |
| iph = skb->nh.iph; |
| |
| if (unlikely((iph->frag_off & htons(IP_DF)) && !skb->local_df)) { |
| icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, |
| htonl(dst_mtu(&rt->u.dst))); |
| kfree_skb(skb); |
| return -EMSGSIZE; |
| } |
| |
| /* |
| * Setup starting values. |
| */ |
| |
| hlen = iph->ihl * 4; |
| mtu = dst_mtu(&rt->u.dst) - hlen; /* Size of data space */ |
| |
| /* 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_shinfo(skb)->frag_list) { |
| struct sk_buff *frag; |
| 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; |
| |
| for (frag = skb_shinfo(skb)->frag_list; frag; frag = frag->next) { |
| /* Correct geometry. */ |
| if (frag->len > mtu || |
| ((frag->len & 7) && frag->next) || |
| skb_headroom(frag) < hlen) |
| goto slow_path; |
| |
| /* Partially cloned skb? */ |
| if (skb_shared(frag)) |
| goto slow_path; |
| |
| BUG_ON(frag->sk); |
| if (skb->sk) { |
| sock_hold(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_shinfo(skb)->frag_list = NULL; |
| 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; |
| frag->h.raw = frag->data; |
| frag->nh.raw = __skb_push(frag, hlen); |
| memcpy(frag->nh.raw, iph, hlen); |
| iph = frag->nh.iph; |
| 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 || !frag) |
| break; |
| |
| skb = frag; |
| frag = skb->next; |
| skb->next = NULL; |
| } |
| |
| if (err == 0) { |
| IP_INC_STATS(IPSTATS_MIB_FRAGOKS); |
| return 0; |
| } |
| |
| while (frag) { |
| skb = frag->next; |
| kfree_skb(frag); |
| frag = skb; |
| } |
| IP_INC_STATS(IPSTATS_MIB_FRAGFAILS); |
| return err; |
| } |
| |
| slow_path: |
| left = skb->len - hlen; /* Space per frame */ |
| ptr = raw + hlen; /* Where to start from */ |
| |
| #ifdef CONFIG_BRIDGE_NETFILTER |
| /* 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->u.dst.dev, nf_bridge_pad(skb)); |
| mtu -= nf_bridge_pad(skb); |
| #else |
| ll_rs = LL_RESERVED_SPACE(rt->u.dst.dev); |
| #endif |
| /* |
| * 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 upto 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(printk(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); |
| skb2->nh.raw = skb2->data; |
| skb2->h.raw = skb2->data + 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. |
| */ |
| |
| memcpy(skb2->nh.raw, skb->data, hlen); |
| |
| /* |
| * Copy a block of the IP datagram. |
| */ |
| if (skb_copy_bits(skb, ptr, skb2->h.raw, len)) |
| BUG(); |
| left -= len; |
| |
| /* |
| * Fill in the new header fields. |
| */ |
| iph = skb2->nh.iph; |
| 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. |
| */ |
| |
| IP_INC_STATS(IPSTATS_MIB_FRAGCREATES); |
| |
| iph->tot_len = htons(len + hlen); |
| |
| ip_send_check(iph); |
| |
| err = output(skb2); |
| if (err) |
| goto fail; |
| } |
| kfree_skb(skb); |
| IP_INC_STATS(IPSTATS_MIB_FRAGOKS); |
| return err; |
| |
| fail: |
| kfree_skb(skb); |
| IP_INC_STATS(IPSTATS_MIB_FRAGFAILS); |
| return err; |
| } |
| |
| 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_HW) { |
| if (memcpy_fromiovecend(to, iov, offset, len) < 0) |
| return -EFAULT; |
| } else { |
| unsigned int 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; |
| } |
| |
| static inline unsigned int |
| csum_page(struct page *page, int offset, int copy) |
| { |
| char *kaddr; |
| unsigned int csum; |
| kaddr = kmap(page); |
| csum = csum_partial(kaddr + offset, copy, 0); |
| kunmap(page); |
| return csum; |
| } |
| |
| /* |
| * 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, |
| 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 *rt, |
| unsigned int flags) |
| { |
| struct inet_sock *inet = inet_sk(sk); |
| struct sk_buff *skb; |
| |
| struct ip_options *opt = NULL; |
| int hh_len; |
| int exthdrlen; |
| int mtu; |
| int copy; |
| int err; |
| int offset = 0; |
| unsigned int maxfraglen, fragheaderlen; |
| int csummode = CHECKSUM_NONE; |
| |
| if (flags&MSG_PROBE) |
| return 0; |
| |
| if (skb_queue_empty(&sk->sk_write_queue)) { |
| /* |
| * setup for corking. |
| */ |
| opt = ipc->opt; |
| if (opt) { |
| if (inet->cork.opt == NULL) { |
| inet->cork.opt = kmalloc(sizeof(struct ip_options) + 40, sk->sk_allocation); |
| if (unlikely(inet->cork.opt == NULL)) |
| return -ENOBUFS; |
| } |
| memcpy(inet->cork.opt, opt, sizeof(struct ip_options)+opt->optlen); |
| inet->cork.flags |= IPCORK_OPT; |
| inet->cork.addr = ipc->addr; |
| } |
| dst_hold(&rt->u.dst); |
| inet->cork.fragsize = mtu = dst_mtu(rt->u.dst.path); |
| inet->cork.rt = rt; |
| inet->cork.length = 0; |
| sk->sk_sndmsg_page = NULL; |
| sk->sk_sndmsg_off = 0; |
| if ((exthdrlen = rt->u.dst.header_len) != 0) { |
| length += exthdrlen; |
| transhdrlen += exthdrlen; |
| } |
| } else { |
| rt = inet->cork.rt; |
| if (inet->cork.flags & IPCORK_OPT) |
| opt = inet->cork.opt; |
| |
| transhdrlen = 0; |
| exthdrlen = 0; |
| mtu = inet->cork.fragsize; |
| } |
| hh_len = LL_RESERVED_SPACE(rt->u.dst.dev); |
| |
| fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0); |
| maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen; |
| |
| if (inet->cork.length + length > 0xFFFF - fragheaderlen) { |
| ip_local_error(sk, EMSGSIZE, rt->rt_dst, 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->u.dst.dev->features&(NETIF_F_IP_CSUM|NETIF_F_NO_CSUM|NETIF_F_HW_CSUM) && |
| !exthdrlen) |
| csummode = CHECKSUM_HW; |
| |
| inet->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 = skb_peek_tail(&sk->sk_write_queue)) == NULL) |
| 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->u.dst.dev->features&NETIF_F_SG)) |
| alloclen = mtu; |
| else |
| alloclen = datalen + fragheaderlen; |
| |
| /* 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) |
| alloclen += rt->u.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; |
| } |
| if (skb == NULL) |
| 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); |
| skb->nh.raw = data + exthdrlen; |
| data += fragheaderlen; |
| skb->h.raw = data + 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; |
| skb_trim(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(&sk->sk_write_queue, skb); |
| continue; |
| } |
| |
| if (copy > length) |
| copy = length; |
| |
| if (!(rt->u.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 = sk->sk_sndmsg_page; |
| int off = sk->sk_sndmsg_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, sk->sk_sndmsg_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; |
| } |
| sk->sk_sndmsg_page = page; |
| sk->sk_sndmsg_off = 0; |
| |
| skb_fill_page_desc(skb, i, page, 0, 0); |
| frag = &skb_shinfo(skb)->frags[i]; |
| skb->truesize += PAGE_SIZE; |
| atomic_add(PAGE_SIZE, &sk->sk_wmem_alloc); |
| } 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; |
| } |
| sk->sk_sndmsg_off += copy; |
| frag->size += copy; |
| skb->len += copy; |
| skb->data_len += copy; |
| } |
| offset += copy; |
| length -= copy; |
| } |
| |
| return 0; |
| |
| error: |
| inet->cork.length -= length; |
| IP_INC_STATS(IPSTATS_MIB_OUTDISCARDS); |
| return err; |
| } |
| |
| ssize_t ip_append_page(struct sock *sk, 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; |
| 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; |
| |
| rt = inet->cork.rt; |
| if (inet->cork.flags & IPCORK_OPT) |
| opt = inet->cork.opt; |
| |
| if (!(rt->u.dst.dev->features&NETIF_F_SG)) |
| return -EOPNOTSUPP; |
| |
| hh_len = LL_RESERVED_SPACE(rt->u.dst.dev); |
| mtu = inet->cork.fragsize; |
| |
| fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0); |
| maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen; |
| |
| if (inet->cork.length + size > 0xFFFF - fragheaderlen) { |
| ip_local_error(sk, EMSGSIZE, rt->rt_dst, inet->dport, mtu); |
| return -EMSGSIZE; |
| } |
| |
| if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL) |
| return -EINVAL; |
| |
| inet->cork.length += size; |
| |
| while (size > 0) { |
| int i; |
| |
| /* 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; |
| char *data; |
| struct iphdr *iph; |
| int alloclen; |
| |
| skb_prev = skb; |
| if (skb_prev) |
| fraggap = skb_prev->len - maxfraglen; |
| else |
| fraggap = 0; |
| |
| 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. |
| */ |
| data = skb_put(skb, fragheaderlen + fraggap); |
| skb->nh.iph = iph = (struct iphdr *)data; |
| data += fragheaderlen; |
| skb->h.raw = data; |
| |
| if (fraggap) { |
| skb->csum = skb_copy_and_csum_bits( |
| skb_prev, maxfraglen, |
| data, fraggap, 0); |
| skb_prev->csum = csum_sub(skb_prev->csum, |
| skb->csum); |
| skb_trim(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) { |
| unsigned int csum; |
| csum = csum_page(page, offset, len); |
| skb->csum = csum_block_add(skb->csum, csum, skb->len); |
| } |
| |
| skb->len += len; |
| skb->data_len += len; |
| offset += len; |
| size -= len; |
| } |
| return 0; |
| |
| error: |
| inet->cork.length -= size; |
| IP_INC_STATS(IPSTATS_MIB_OUTDISCARDS); |
| return err; |
| } |
| |
| /* |
| * Combined all pending IP fragments on the socket as one IP datagram |
| * and push them out. |
| */ |
| int ip_push_pending_frames(struct sock *sk) |
| { |
| struct sk_buff *skb, *tmp_skb; |
| struct sk_buff **tail_skb; |
| struct inet_sock *inet = inet_sk(sk); |
| struct ip_options *opt = NULL; |
| struct rtable *rt = inet->cork.rt; |
| struct iphdr *iph; |
| int df = 0; |
| __u8 ttl; |
| int err = 0; |
| |
| if ((skb = __skb_dequeue(&sk->sk_write_queue)) == NULL) |
| goto out; |
| tail_skb = &(skb_shinfo(skb)->frag_list); |
| |
| /* move skb->data to ip header from ext header */ |
| if (skb->data < skb->nh.raw) |
| __skb_pull(skb, skb->nh.raw - skb->data); |
| while ((tmp_skb = __skb_dequeue(&sk->sk_write_queue)) != NULL) { |
| __skb_pull(tmp_skb, skb->h.raw - skb->nh.raw); |
| *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; |
| __sock_put(tmp_skb->sk); |
| 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->u.dst) && |
| ip_dont_fragment(sk, &rt->u.dst))) |
| df = htons(IP_DF); |
| |
| if (inet->cork.flags & IPCORK_OPT) |
| opt = inet->cork.opt; |
| |
| if (rt->rt_type == RTN_MULTICAST) |
| ttl = inet->mc_ttl; |
| else |
| ttl = ip_select_ttl(inet, &rt->u.dst); |
| |
| iph = (struct iphdr *)skb->data; |
| iph->version = 4; |
| iph->ihl = 5; |
| if (opt) { |
| iph->ihl += opt->optlen>>2; |
| ip_options_build(skb, opt, inet->cork.addr, rt, 0); |
| } |
| iph->tos = inet->tos; |
| iph->tot_len = htons(skb->len); |
| iph->frag_off = df; |
| if (!df) { |
| __ip_select_ident(iph, &rt->u.dst, 0); |
| } else { |
| iph->id = htons(inet->id++); |
| } |
| iph->ttl = ttl; |
| iph->protocol = sk->sk_protocol; |
| iph->saddr = rt->rt_src; |
| iph->daddr = rt->rt_dst; |
| ip_send_check(iph); |
| |
| skb->priority = sk->sk_priority; |
| skb->dst = dst_clone(&rt->u.dst); |
| |
| /* Netfilter gets whole the not fragmented skb. */ |
| err = NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, skb, NULL, |
| skb->dst->dev, dst_output); |
| if (err) { |
| if (err > 0) |
| err = inet->recverr ? net_xmit_errno(err) : 0; |
| if (err) |
| goto error; |
| } |
| |
| out: |
| inet->cork.flags &= ~IPCORK_OPT; |
| if (inet->cork.opt) { |
| kfree(inet->cork.opt); |
| inet->cork.opt = NULL; |
| } |
| if (inet->cork.rt) { |
| ip_rt_put(inet->cork.rt); |
| inet->cork.rt = NULL; |
| } |
| return err; |
| |
| error: |
| IP_INC_STATS(IPSTATS_MIB_OUTDISCARDS); |
| goto out; |
| } |
| |
| /* |
| * Throw away all pending data on the socket. |
| */ |
| void ip_flush_pending_frames(struct sock *sk) |
| { |
| struct inet_sock *inet = inet_sk(sk); |
| struct sk_buff *skb; |
| |
| while ((skb = __skb_dequeue_tail(&sk->sk_write_queue)) != NULL) |
| kfree_skb(skb); |
| |
| inet->cork.flags &= ~IPCORK_OPT; |
| if (inet->cork.opt) { |
| kfree(inet->cork.opt); |
| inet->cork.opt = NULL; |
| } |
| if (inet->cork.rt) { |
| ip_rt_put(inet->cork.rt); |
| inet->cork.rt = NULL; |
| } |
| } |
| |
| |
| /* |
| * 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) |
| { |
| unsigned int 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. |
| * |
| * LATER: switch from ip_build_xmit to ip_append_* |
| */ |
| void ip_send_reply(struct sock *sk, struct sk_buff *skb, struct ip_reply_arg *arg, |
| unsigned int len) |
| { |
| struct inet_sock *inet = inet_sk(sk); |
| struct { |
| struct ip_options opt; |
| char data[40]; |
| } replyopts; |
| struct ipcm_cookie ipc; |
| u32 daddr; |
| struct rtable *rt = (struct rtable*)skb->dst; |
| |
| if (ip_options_echo(&replyopts.opt, skb)) |
| return; |
| |
| daddr = ipc.addr = rt->rt_src; |
| ipc.opt = NULL; |
| |
| if (replyopts.opt.optlen) { |
| ipc.opt = &replyopts.opt; |
| |
| if (ipc.opt->srr) |
| daddr = replyopts.opt.faddr; |
| } |
| |
| { |
| struct flowi fl = { .nl_u = { .ip4_u = |
| { .daddr = daddr, |
| .saddr = rt->rt_spec_dst, |
| .tos = RT_TOS(skb->nh.iph->tos) } }, |
| /* Not quite clean, but right. */ |
| .uli_u = { .ports = |
| { .sport = skb->h.th->dest, |
| .dport = skb->h.th->source } }, |
| .proto = sk->sk_protocol }; |
| if (ip_route_output_key(&rt, &fl)) |
| 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 = skb->nh.iph->tos; |
| sk->sk_priority = skb->priority; |
| sk->sk_protocol = skb->nh.iph->protocol; |
| ip_append_data(sk, 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) |
| *((u16 *)skb->h.raw + arg->csumoffset) = csum_fold(csum_add(skb->csum, arg->csum)); |
| skb->ip_summed = CHECKSUM_NONE; |
| ip_push_pending_frames(sk); |
| } |
| |
| bh_unlock_sock(sk); |
| |
| ip_rt_put(rt); |
| } |
| |
| /* |
| * IP protocol layer initialiser |
| */ |
| |
| static struct packet_type ip_packet_type = { |
| .type = __constant_htons(ETH_P_IP), |
| .func = ip_rcv, |
| }; |
| |
| /* |
| * IP registers the packet type and then calls the subprotocol initialisers |
| */ |
| |
| void __init ip_init(void) |
| { |
| dev_add_pack(&ip_packet_type); |
| |
| ip_rt_init(); |
| inet_initpeers(); |
| |
| #if defined(CONFIG_IP_MULTICAST) && defined(CONFIG_PROC_FS) |
| igmp_mc_proc_init(); |
| #endif |
| } |
| |
| EXPORT_SYMBOL(ip_finish_output); |
| EXPORT_SYMBOL(ip_fragment); |
| EXPORT_SYMBOL(ip_generic_getfrag); |
| EXPORT_SYMBOL(ip_queue_xmit); |
| EXPORT_SYMBOL(ip_send_check); |
| |
| #ifdef CONFIG_SYSCTL |
| EXPORT_SYMBOL(sysctl_ip_default_ttl); |
| #endif |