ClabureDB: Classified Bug-Reports Database

   /*
    * 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 User Datagram Protocol (UDP).
    *
    * Authors:        Ross Biro
    *                Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
   *                Arnt Gulbrandsen, <agulbra@nvg.unit.no>
   *                Alan Cox, <alan@lxorguk.ukuu.org.uk>
   *                Hirokazu Takahashi, <taka@valinux.co.jp>
   *
   * Fixes:
   *                Alan Cox        :        verify_area() calls
   *                Alan Cox        :         stopped close while in use off icmp
   *                                        messages. Not a fix but a botch that
   *                                        for udp at least is 'valid'.
   *                Alan Cox        :        Fixed icmp handling properly
   *                Alan Cox        :         Correct error for oversized datagrams
   *                Alan Cox        :        Tidied select() semantics.
   *                Alan Cox        :        udp_err() fixed properly, also now
   *                                        select and read wake correctly on errors
   *                Alan Cox        :        udp_send verify_area moved to avoid mem leak
   *                Alan Cox        :        UDP can count its memory
   *                Alan Cox        :        send to an unknown connection causes
   *                                        an ECONNREFUSED off the icmp, but
   *                                        does NOT close.
   *                Alan Cox        :        Switched to new sk_buff handlers. No more backlog!
   *                Alan Cox        :        Using generic datagram code. Even smaller and the PEEK
   *                                        bug no longer crashes it.
   *                Fred Van Kempen        :         Net2e support for sk->broadcast.
   *                Alan Cox        :        Uses skb_free_datagram
   *                Alan Cox        :        Added get/set sockopt support.
   *                Alan Cox        :        Broadcasting without option set returns EACCES.
   *                Alan Cox        :        No wakeup calls. Instead we now use the callbacks.
   *                Alan Cox        :        Use ip_tos and ip_ttl
   *                Alan Cox        :        SNMP Mibs
   *                Alan Cox        :        MSG_DONTROUTE, and 0.0.0.0 support.
   *                Matt Dillon        :        UDP length checks.
   *                Alan Cox        :        Smarter af_inet used properly.
   *                Alan Cox        :        Use new kernel side addressing.
   *                Alan Cox        :        Incorrect return on truncated datagram receive.
   *        Arnt Gulbrandsen         :        New udp_send and stuff
   *                Alan Cox        :        Cache last socket
   *                Alan Cox        :        Route cache
   *                Jon Peatfield        :        Minor efficiency fix to sendto().
   *                Mike Shaver        :        RFC1122 checks.
   *                Alan Cox        :        Nonblocking error fix.
   *        Willy Konynenberg        :        Transparent proxying support.
   *                Mike McLagan        :        Routing by source
   *                David S. Miller        :        New socket lookup architecture.
   *                                        Last socket cache retained as it
   *                                        does have a high hit rate.
   *                Olaf Kirch        :        Don't linearise iovec on sendmsg.
   *                Andi Kleen        :        Some cleanups, cache destination entry
   *                                        for connect.
   *        Vitaly E. Lavrov        :        Transparent proxy revived after year coma.
   *                Melvin Smith        :        Check msg_name not msg_namelen in sendto(),
   *                                        return ENOTCONN for unconnected sockets (POSIX)
   *                Janos Farkas        :        don't deliver multi/broadcasts to a different
   *                                        bound-to-device socket
   *        Hirokazu Takahashi        :        HW checksumming for outgoing UDP
   *                                        datagrams.
   *        Hirokazu Takahashi        :        sendfile() on UDP works now.
   *                Arnaldo C. Melo :        convert /proc/net/udp to seq_file
   *        YOSHIFUJI Hideaki @USAGI and:        Support IPV6_V6ONLY socket option, which
   *        Alexey Kuznetsov:                allow both IPv4 and IPv6 sockets to bind
   *                                        a single port at the same time.
   *        Derek Atkins <derek@ihtfp.com>: Add Encapulation Support
   *        James Chapman                :        Add L2TP encapsulation type.
   *
   *
   *                This program is free software; you can redistribute it and/or
   *                modify it under the terms of the GNU General Public License
   *                as published by the Free Software Foundation; either version
   *                2 of the License, or (at your option) any later version.
   */
  
  #include <asm/system.h>
  #include <asm/uaccess.h>
  #include <asm/ioctls.h>
  #include <linux/bootmem.h>
  #include <linux/types.h>
  #include <linux/fcntl.h>
  #include <linux/module.h>
  #include <linux/socket.h>
  #include <linux/sockios.h>
  #include <linux/igmp.h>
  #include <linux/in.h>
  #include <linux/errno.h>
  #include <linux/timer.h>
  #include <linux/mm.h>
  #include <linux/inet.h>
  #include <linux/netdevice.h>
  #include <net/tcp_states.h>
  #include <linux/skbuff.h>
  #include <linux/proc_fs.h>
  #include <linux/seq_file.h>
 #include <net/net_namespace.h>
 #include <net/icmp.h>
 #include <net/route.h>
 #include <net/checksum.h>
 #include <net/xfrm.h>
 #include "udp_impl.h"
 
 /*
  *        Snmp MIB for the UDP layer
  */
 
 struct hlist_head udp_hash[UDP_HTABLE_SIZE];
 DEFINE_RWLOCK(udp_hash_lock);
 
 int sysctl_udp_mem[3] __read_mostly;
 int sysctl_udp_rmem_min __read_mostly;
 int sysctl_udp_wmem_min __read_mostly;
 
 EXPORT_SYMBOL(sysctl_udp_mem);
 EXPORT_SYMBOL(sysctl_udp_rmem_min);
 EXPORT_SYMBOL(sysctl_udp_wmem_min);
 
 atomic_t udp_memory_allocated;
 EXPORT_SYMBOL(udp_memory_allocated);
 
 static int udp_lib_lport_inuse(struct net *net, __u16 num,
                                const struct hlist_head udptable[],
                                struct sock *sk,
                                int (*saddr_comp)(const struct sock *sk1,
                                                  const struct sock *sk2))
 {
         struct sock *sk2;
         struct hlist_node *node;
 
         sk_for_each(sk2, node, &udptable[udp_hashfn(net, num)])
                 if (net_eq(sock_net(sk2), net)                        &&
                     sk2 != sk                                        &&
                     sk2->sk_hash == num                                &&
                     (!sk2->sk_reuse || !sk->sk_reuse)                &&
                     (!sk2->sk_bound_dev_if || !sk->sk_bound_dev_if
                         || sk2->sk_bound_dev_if == sk->sk_bound_dev_if) &&
                     (*saddr_comp)(sk, sk2))
                         return 1;
         return 0;
 }
 
 /**
  *  udp_lib_get_port  -  UDP/-Lite port lookup for IPv4 and IPv6
  *
  *  @sk:          socket struct in question
  *  @snum:        port number to look up
  *  @saddr_comp:  AF-dependent comparison of bound local IP addresses
  */
 int udp_lib_get_port(struct sock *sk, unsigned short snum,
                        int (*saddr_comp)(const struct sock *sk1,
                                          const struct sock *sk2 )    )
 {
         struct hlist_head *udptable = sk->sk_prot->h.udp_hash;
         int    error = 1;
         struct net *net = sock_net(sk);
 
         write_lock_bh(&udp_hash_lock);
 
         if (!snum) {
                 int low, high, remaining;
                 unsigned rand;
                 unsigned short first;
 
                 inet_get_local_port_range(&low, &high);
                 remaining = (high - low) + 1;
 
                 rand = net_random();
                 snum = first = rand % remaining + low;
                 rand |= 1;
                 while (udp_lib_lport_inuse(net, snum, udptable, sk,
                                            saddr_comp)) {
                         do {
                                 snum = snum + rand;
                         } while (snum < low || snum > high);
                         if (snum == first)
                                 goto fail;
                 }
         } else if (udp_lib_lport_inuse(net, snum, udptable, sk, saddr_comp))
                 goto fail;
 
         inet_sk(sk)->num = snum;
         sk->sk_hash = snum;
         if (sk_unhashed(sk)) {
                 sk_add_node(sk, &udptable[udp_hashfn(net, snum)]);
                 sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
         }
         error = 0;
 fail:
         write_unlock_bh(&udp_hash_lock);
         return error;
 }
 
 static int ipv4_rcv_saddr_equal(const struct sock *sk1, const struct sock *sk2)
 {
         struct inet_sock *inet1 = inet_sk(sk1), *inet2 = inet_sk(sk2);
 
         return         ( !ipv6_only_sock(sk2)  &&
                   (!inet1->rcv_saddr || !inet2->rcv_saddr ||
                    inet1->rcv_saddr == inet2->rcv_saddr      ));
 }
 
 int udp_v4_get_port(struct sock *sk, unsigned short snum)
 {
         return udp_lib_get_port(sk, snum, ipv4_rcv_saddr_equal);
 }
 
 /* UDP is nearly always wildcards out the wazoo, it makes no sense to try
  * harder than this. -DaveM
  */
 static struct sock *__udp4_lib_lookup(struct net *net, __be32 saddr,
                 __be16 sport, __be32 daddr, __be16 dport,
                 int dif, struct hlist_head udptable[])
 {
         struct sock *sk, *result = NULL;
         struct hlist_node *node;
         unsigned short hnum = ntohs(dport);
         int badness = -1;
 
         read_lock(&udp_hash_lock);
         sk_for_each(sk, node, &udptable[udp_hashfn(net, hnum)]) {
                 struct inet_sock *inet = inet_sk(sk);
 
                 if (net_eq(sock_net(sk), net) && sk->sk_hash == hnum &&
                                 !ipv6_only_sock(sk)) {
                         int score = (sk->sk_family == PF_INET ? 1 : 0);
                         if (inet->rcv_saddr) {
                                 if (inet->rcv_saddr != daddr)
                                         continue;
                                 score+=2;
                         }
                         if (inet->daddr) {
                                 if (inet->daddr != saddr)
                                         continue;
                                 score+=2;
                         }
                         if (inet->dport) {
                                 if (inet->dport != sport)
                                         continue;
                                 score+=2;
                         }
                         if (sk->sk_bound_dev_if) {
                                 if (sk->sk_bound_dev_if != dif)
                                         continue;
                                 score+=2;
                         }
                         if (score == 9) {
                                 result = sk;
                                 break;
                         } else if (score > badness) {
                                 result = sk;
                                 badness = score;
                         }
                 }
         }
         if (result)
                 sock_hold(result);
         read_unlock(&udp_hash_lock);
         return result;
 }
 
 static inline struct sock *__udp4_lib_lookup_skb(struct sk_buff *skb,
                                                  __be16 sport, __be16 dport,
                                                  struct hlist_head udptable[])
 {
         struct sock *sk;
         const struct iphdr *iph = ip_hdr(skb);
 
         if (unlikely(sk = skb_steal_sock(skb)))
                 return sk;
         else
                 return __udp4_lib_lookup(dev_net(skb->dst->dev), iph->saddr, sport,
                                          iph->daddr, dport, inet_iif(skb),
                                          udptable);
 }
 
 struct sock *udp4_lib_lookup(struct net *net, __be32 saddr, __be16 sport,
                              __be32 daddr, __be16 dport, int dif)
 {
         return __udp4_lib_lookup(net, saddr, sport, daddr, dport, dif, udp_hash);
 }
 EXPORT_SYMBOL_GPL(udp4_lib_lookup);
 
 static inline struct sock *udp_v4_mcast_next(struct net *net, struct sock *sk,
                                              __be16 loc_port, __be32 loc_addr,
                                              __be16 rmt_port, __be32 rmt_addr,
                                              int dif)
 {
         struct hlist_node *node;
         struct sock *s = sk;
         unsigned short hnum = ntohs(loc_port);
 
         sk_for_each_from(s, node) {
                 struct inet_sock *inet = inet_sk(s);
 
                 if (!net_eq(sock_net(s), net)                                ||
                     s->sk_hash != hnum                                        ||
                     (inet->daddr && inet->daddr != rmt_addr)                ||
                     (inet->dport != rmt_port && inet->dport)                ||
                     (inet->rcv_saddr && inet->rcv_saddr != loc_addr)        ||
                     ipv6_only_sock(s)                                        ||
                     (s->sk_bound_dev_if && s->sk_bound_dev_if != dif))
                         continue;
                 if (!ip_mc_sf_allow(s, loc_addr, rmt_addr, dif))
                         continue;
                 goto found;
         }
         s = NULL;
 found:
         return s;
 }
 
 /*
  * This routine is called by the ICMP module when it gets some
  * sort of error condition.  If err < 0 then the socket should
  * be closed and the error returned to the user.  If err > 0
  * it's just the icmp type << 8 | icmp code.
  * Header points to the ip header of the error packet. We move
  * on past this. Then (as it used to claim before adjustment)
  * header points to the first 8 bytes of the udp header.  We need
  * to find the appropriate port.
  */
 
 void __udp4_lib_err(struct sk_buff *skb, u32 info, struct hlist_head udptable[])
 {
         struct inet_sock *inet;
         struct iphdr *iph = (struct iphdr*)skb->data;
         struct udphdr *uh = (struct udphdr*)(skb->data+(iph->ihl<<2));
         const int type = icmp_hdr(skb)->type;
         const int code = icmp_hdr(skb)->code;
         struct sock *sk;
         int harderr;
         int err;
         struct net *net = dev_net(skb->dev);
 
         sk = __udp4_lib_lookup(net, iph->daddr, uh->dest,
                         iph->saddr, uh->source, skb->dev->ifindex, udptable);
         if (sk == NULL) {
                 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
                 return;        /* No socket for error */
         }
 
         err = 0;
         harderr = 0;
         inet = inet_sk(sk);
 
         switch (type) {
         default:
         case ICMP_TIME_EXCEEDED:
                 err = EHOSTUNREACH;
                 break;
         case ICMP_SOURCE_QUENCH:
                 goto out;
         case ICMP_PARAMETERPROB:
                 err = EPROTO;
                 harderr = 1;
                 break;
         case ICMP_DEST_UNREACH:
                 if (code == ICMP_FRAG_NEEDED) { /* Path MTU discovery */
                         if (inet->pmtudisc != IP_PMTUDISC_DONT) {
                                 err = EMSGSIZE;
                                 harderr = 1;
                                 break;
                         }
                         goto out;
                 }
                 err = EHOSTUNREACH;
                 if (code <= NR_ICMP_UNREACH) {
                         harderr = icmp_err_convert[code].fatal;
                         err = icmp_err_convert[code].errno;
                 }
                 break;
         }
 
         /*
          *      RFC1122: OK.  Passes ICMP errors back to application, as per
          *        4.1.3.3.
          */
         if (!inet->recverr) {
                 if (!harderr || sk->sk_state != TCP_ESTABLISHED)
                         goto out;
         } else {
                 ip_icmp_error(sk, skb, err, uh->dest, info, (u8*)(uh+1));
         }
         sk->sk_err = err;
         sk->sk_error_report(sk);
 out:
         sock_put(sk);
 }
 
 void udp_err(struct sk_buff *skb, u32 info)
 {
         __udp4_lib_err(skb, info, udp_hash);
 }
 
 /*
  * Throw away all pending data and cancel the corking. Socket is locked.
  */
 void udp_flush_pending_frames(struct sock *sk)
 {
         struct udp_sock *up = udp_sk(sk);
 
         if (up->pending) {
                 up->len = 0;
                 up->pending = 0;
                 ip_flush_pending_frames(sk);
         }
 }
 EXPORT_SYMBOL(udp_flush_pending_frames);
 
 /**
  *         udp4_hwcsum_outgoing  -  handle outgoing HW checksumming
  *         @sk:         socket we are sending on
  *         @skb:         sk_buff containing the filled-in UDP header
  *                 (checksum field must be zeroed out)
  */
 static void udp4_hwcsum_outgoing(struct sock *sk, struct sk_buff *skb,
                                  __be32 src, __be32 dst, int len      )
 {
         unsigned int offset;
         struct udphdr *uh = udp_hdr(skb);
         __wsum csum = 0;
 
         if (skb_queue_len(&sk->sk_write_queue) == 1) {
                 /*
                  * Only one fragment on the socket.
                  */
                 skb->csum_start = skb_transport_header(skb) - skb->head;
                 skb->csum_offset = offsetof(struct udphdr, check);
                 uh->check = ~csum_tcpudp_magic(src, dst, len, IPPROTO_UDP, 0);
         } else {
                 /*
                  * HW-checksum won't work as there are two or more
                  * fragments on the socket so that all csums of sk_buffs
                  * should be together
                  */
                 offset = skb_transport_offset(skb);
                 skb->csum = skb_checksum(skb, offset, skb->len - offset, 0);
 
                 skb->ip_summed = CHECKSUM_NONE;
 
                 skb_queue_walk(&sk->sk_write_queue, skb) {
                         csum = csum_add(csum, skb->csum);
                 }
 
                 uh->check = csum_tcpudp_magic(src, dst, len, IPPROTO_UDP, csum);
                 if (uh->check == 0)
                         uh->check = CSUM_MANGLED_0;
         }
 }
 
 /*
  * Push out all pending data as one UDP datagram. Socket is locked.
  */
 static int udp_push_pending_frames(struct sock *sk)
 {
         struct udp_sock  *up = udp_sk(sk);
         struct inet_sock *inet = inet_sk(sk);
         struct flowi *fl = &inet->cork.fl;
         struct sk_buff *skb;
         struct udphdr *uh;
         int err = 0;
         int is_udplite = IS_UDPLITE(sk);
         __wsum csum = 0;
 
         /* Grab the skbuff where UDP header space exists. */
         if ((skb = skb_peek(&sk->sk_write_queue)) == NULL)
                 goto out;
 
         /*
          * Create a UDP header
          */
         uh = udp_hdr(skb);
         uh->source = fl->fl_ip_sport;
         uh->dest = fl->fl_ip_dport;
         uh->len = htons(up->len);
         uh->check = 0;
 
         if (is_udplite)                                   /*     UDP-Lite      */
                 csum  = udplite_csum_outgoing(sk, skb);
 
         else if (sk->sk_no_check == UDP_CSUM_NOXMIT) {   /* UDP csum disabled */
 
                 skb->ip_summed = CHECKSUM_NONE;
                 goto send;
 
         } else if (skb->ip_summed == CHECKSUM_PARTIAL) { /* UDP hardware csum */
 
                 udp4_hwcsum_outgoing(sk, skb, fl->fl4_src,fl->fl4_dst, up->len);
                 goto send;
 
         } else                                                 /*   `normal' UDP    */
                 csum = udp_csum_outgoing(sk, skb);
 
         /* add protocol-dependent pseudo-header */
         uh->check = csum_tcpudp_magic(fl->fl4_src, fl->fl4_dst, up->len,
                                       sk->sk_protocol, csum             );
         if (uh->check == 0)
                 uh->check = CSUM_MANGLED_0;
 
 send:
         err = ip_push_pending_frames(sk);
 out:
         up->len = 0;
         up->pending = 0;
         if (!err)
                 UDP_INC_STATS_USER(sock_net(sk),
                                 UDP_MIB_OUTDATAGRAMS, is_udplite);
         return err;
 }
 
 int udp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
                 size_t len)
 {
         struct inet_sock *inet = inet_sk(sk);
         struct udp_sock *up = udp_sk(sk);
         int ulen = len;
         struct ipcm_cookie ipc;
         struct rtable *rt = NULL;
         int free = 0;
         int connected = 0;
         __be32 daddr, faddr, saddr;
         __be16 dport;
         u8  tos;
         int err, is_udplite = IS_UDPLITE(sk);
         int corkreq = up->corkflag || msg->msg_flags&MSG_MORE;
         int (*getfrag)(void *, char *, int, int, int, struct sk_buff *);
 
         if (len > 0xFFFF)
                 return -EMSGSIZE;
 
         /*
          *        Check the flags.
          */
 
         if (msg->msg_flags&MSG_OOB)        /* Mirror BSD error message compatibility */
                 return -EOPNOTSUPP;
 
         ipc.opt = NULL;
 
         if (up->pending) {
                 /*
                  * There are pending frames.
                  * The socket lock must be held while it's corked.
                  */
                 lock_sock(sk);
                 if (likely(up->pending)) {
                         if (unlikely(up->pending != AF_INET)) {
                                 release_sock(sk);
                                 return -EINVAL;
                         }
                         goto do_append_data;
                 }
                 release_sock(sk);
         }
         ulen += sizeof(struct udphdr);
 
         /*
          *        Get and verify the address.
          */
         if (msg->msg_name) {
                 struct sockaddr_in * usin = (struct sockaddr_in*)msg->msg_name;
                 if (msg->msg_namelen < sizeof(*usin))
                         return -EINVAL;
                 if (usin->sin_family != AF_INET) {
                         if (usin->sin_family != AF_UNSPEC)
                                 return -EAFNOSUPPORT;
                 }
 
                 daddr = usin->sin_addr.s_addr;
                 dport = usin->sin_port;
                 if (dport == 0)
                         return -EINVAL;
         } else {
                 if (sk->sk_state != TCP_ESTABLISHED)
                         return -EDESTADDRREQ;
                 daddr = inet->daddr;
                 dport = inet->dport;
                 /* Open fast path for connected socket.
                    Route will not be used, if at least one option is set.
                  */
                 connected = 1;
         }
         ipc.addr = inet->saddr;
 
         ipc.oif = sk->sk_bound_dev_if;
         if (msg->msg_controllen) {
                 err = ip_cmsg_send(sock_net(sk), msg, &ipc);
                 if (err)
                         return err;
                 if (ipc.opt)
                         free = 1;
                 connected = 0;
         }
         if (!ipc.opt)
                 ipc.opt = inet->opt;
 
         saddr = ipc.addr;
         ipc.addr = faddr = daddr;
 
         if (ipc.opt && ipc.opt->srr) {
                 if (!daddr)
                         return -EINVAL;
                 faddr = ipc.opt->faddr;
                 connected = 0;
         }
         tos = RT_TOS(inet->tos);
         if (sock_flag(sk, SOCK_LOCALROUTE) ||
             (msg->msg_flags & MSG_DONTROUTE) ||
             (ipc.opt && ipc.opt->is_strictroute)) {
                 tos |= RTO_ONLINK;
                 connected = 0;
         }
 
         if (ipv4_is_multicast(daddr)) {
                 if (!ipc.oif)
                         ipc.oif = inet->mc_index;
                 if (!saddr)
                         saddr = inet->mc_addr;
                 connected = 0;
         }
 
         if (connected)
                 rt = (struct rtable*)sk_dst_check(sk, 0);
 
         if (rt == NULL) {
                 struct flowi fl = { .oif = ipc.oif,
                                     .nl_u = { .ip4_u =
                                               { .daddr = faddr,
                                                 .saddr = saddr,
                                                 .tos = tos } },
                                     .proto = sk->sk_protocol,
                                     .flags = inet_sk_flowi_flags(sk),
                                     .uli_u = { .ports =
                                                { .sport = inet->sport,
                                                  .dport = dport } } };
                 struct net *net = sock_net(sk);
 
                 security_sk_classify_flow(sk, &fl);
                 err = ip_route_output_flow(net, &rt, &fl, sk, 1);
                 if (err) {
                         if (err == -ENETUNREACH)
                                 IP_INC_STATS_BH(net, IPSTATS_MIB_OUTNOROUTES);
                         goto out;
                 }
 
                 err = -EACCES;
                 if ((rt->rt_flags & RTCF_BROADCAST) &&
                     !sock_flag(sk, SOCK_BROADCAST))
                         goto out;
                 if (connected)
                         sk_dst_set(sk, dst_clone(&rt->u.dst));
         }
 
         if (msg->msg_flags&MSG_CONFIRM)
                 goto do_confirm;
 back_from_confirm:
 
         saddr = rt->rt_src;
         if (!ipc.addr)
                 daddr = ipc.addr = rt->rt_dst;
 
         lock_sock(sk);
         if (unlikely(up->pending)) {
                 /* The socket is already corked while preparing it. */
                 /* ... which is an evident application bug. --ANK */
                 release_sock(sk);
 
                 LIMIT_NETDEBUG(KERN_DEBUG "udp cork app bug 2\n");
                 err = -EINVAL;
                 goto out;
         }
         /*
          *        Now cork the socket to pend data.
          */
         inet->cork.fl.fl4_dst = daddr;
         inet->cork.fl.fl_ip_dport = dport;
         inet->cork.fl.fl4_src = saddr;
         inet->cork.fl.fl_ip_sport = inet->sport;
         up->pending = AF_INET;
 
 do_append_data:
         up->len += ulen;
         getfrag  =  is_udplite ?  udplite_getfrag : ip_generic_getfrag;
         err = ip_append_data(sk, getfrag, msg->msg_iov, ulen,
                         sizeof(struct udphdr), &ipc, rt,
                         corkreq ? msg->msg_flags|MSG_MORE : msg->msg_flags);
         if (err)
                 udp_flush_pending_frames(sk);
         else if (!corkreq)
                 err = udp_push_pending_frames(sk);
         else if (unlikely(skb_queue_empty(&sk->sk_write_queue)))
                 up->pending = 0;
         release_sock(sk);
 
 out:
         ip_rt_put(rt);
         if (free)
                 kfree(ipc.opt);
         if (!err)
                 return len;
         /*
          * ENOBUFS = no kernel mem, SOCK_NOSPACE = no sndbuf space.  Reporting
          * ENOBUFS might not be good (it's not tunable per se), but otherwise
          * we don't have a good statistic (IpOutDiscards but it can be too many
          * things).  We could add another new stat but at least for now that
          * seems like overkill.
          */
         if (err == -ENOBUFS || test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) {
                 UDP_INC_STATS_USER(sock_net(sk),
                                 UDP_MIB_SNDBUFERRORS, is_udplite);
         }
         return err;
 
 do_confirm:
         dst_confirm(&rt->u.dst);
         if (!(msg->msg_flags&MSG_PROBE) || len)
                 goto back_from_confirm;
         err = 0;
         goto out;
 }
 
 int udp_sendpage(struct sock *sk, struct page *page, int offset,
                  size_t size, int flags)
 {
         struct udp_sock *up = udp_sk(sk);
         int ret;
 
         if (!up->pending) {
                 struct msghdr msg = {        .msg_flags = flags|MSG_MORE };
 
                 /* Call udp_sendmsg to specify destination address which
                  * sendpage interface can't pass.
                  * This will succeed only when the socket is connected.
                  */
                 ret = udp_sendmsg(NULL, sk, &msg, 0);
                 if (ret < 0)
                         return ret;
         }
 
         lock_sock(sk);
 
         if (unlikely(!up->pending)) {
                 release_sock(sk);
 
                 LIMIT_NETDEBUG(KERN_DEBUG "udp cork app bug 3\n");
                 return -EINVAL;
         }
 
         ret = ip_append_page(sk, page, offset, size, flags);
         if (ret == -EOPNOTSUPP) {
                 release_sock(sk);
                 return sock_no_sendpage(sk->sk_socket, page, offset,
                                         size, flags);
         }
         if (ret < 0) {
                 udp_flush_pending_frames(sk);
                 goto out;
         }
 
         up->len += size;
         if (!(up->corkflag || (flags&MSG_MORE)))
                 ret = udp_push_pending_frames(sk);
         if (!ret)
                 ret = size;
 out:
         release_sock(sk);
         return ret;
 }
 
 /*
  *        IOCTL requests applicable to the UDP protocol
  */
 
 int udp_ioctl(struct sock *sk, int cmd, unsigned long arg)
 {
         switch (cmd) {
         case SIOCOUTQ:
         {
                 int amount = atomic_read(&sk->sk_wmem_alloc);
                 return put_user(amount, (int __user *)arg);
         }
 
         case SIOCINQ:
         {
                 struct sk_buff *skb;
                 unsigned long amount;
 
                 amount = 0;
                 spin_lock_bh(&sk->sk_receive_queue.lock);
                 skb = skb_peek(&sk->sk_receive_queue);
                 if (skb != NULL) {
                         /*
                          * We will only return the amount
                          * of this packet since that is all
                          * that will be read.
                          */
                         amount = skb->len - sizeof(struct udphdr);
                 }
                 spin_unlock_bh(&sk->sk_receive_queue.lock);
                 return put_user(amount, (int __user *)arg);
         }
 
         default:
                 return -ENOIOCTLCMD;
         }
 
         return 0;
 }
 
 /*
  *         This should be easy, if there is something there we
  *         return it, otherwise we block.
  */
 
 int udp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
                 size_t len, int noblock, int flags, int *addr_len)
 {
         struct inet_sock *inet = inet_sk(sk);
         struct sockaddr_in *sin = (struct sockaddr_in *)msg->msg_name;
         struct sk_buff *skb;
         unsigned int ulen, copied;
         int peeked;
         int err;
         int is_udplite = IS_UDPLITE(sk);
 
         /*
          *        Check any passed addresses
          */
         if (addr_len)
                 *addr_len=sizeof(*sin);
 
         if (flags & MSG_ERRQUEUE)
                 return ip_recv_error(sk, msg, len);
 
 try_again:
         skb = __skb_recv_datagram(sk, flags | (noblock ? MSG_DONTWAIT : 0),
                                   &peeked, &err);
         if (!skb)
                 goto out;
 
         ulen = skb->len - sizeof(struct udphdr);
         copied = len;
         if (copied > ulen)
                 copied = ulen;
         else if (copied < ulen)
                 msg->msg_flags |= MSG_TRUNC;
 
         /*
          * If checksum is needed at all, try to do it while copying the
          * data.  If the data is truncated, or if we only want a partial
          * coverage checksum (UDP-Lite), do it before the copy.
          */
 
         if (copied < ulen || UDP_SKB_CB(skb)->partial_cov) {
                 if (udp_lib_checksum_complete(skb))
                         goto csum_copy_err;
         }
 
         if (skb_csum_unnecessary(skb))
                 err = skb_copy_datagram_iovec(skb, sizeof(struct udphdr),
                                               msg->msg_iov, copied       );
         else {
                 err = skb_copy_and_csum_datagram_iovec(skb, sizeof(struct udphdr), msg->msg_iov);
 
                 if (err == -EINVAL)
                         goto csum_copy_err;
         }
 
         if (err)
                 goto out_free;
 
         if (!peeked)
                 UDP_INC_STATS_USER(sock_net(sk),
                                 UDP_MIB_INDATAGRAMS, is_udplite);
 
         sock_recv_timestamp(msg, sk, skb);
 
         /* Copy the address. */
         if (sin)
         {
                 sin->sin_family = AF_INET;
                 sin->sin_port = udp_hdr(skb)->source;
                 sin->sin_addr.s_addr = ip_hdr(skb)->saddr;
                 memset(sin->sin_zero, 0, sizeof(sin->sin_zero));
         }
         if (inet->cmsg_flags)
                 ip_cmsg_recv(msg, skb);
 
         err = copied;
         if (flags & MSG_TRUNC)
                 err = ulen;
 
 out_free:
         lock_sock(sk);
         skb_free_datagram(sk, skb);
         release_sock(sk);
 out:
         return err;
 
 csum_copy_err:
         lock_sock(sk);
         if (!skb_kill_datagram(sk, skb, flags))
                 UDP_INC_STATS_USER(sock_net(sk), UDP_MIB_INERRORS, is_udplite);
         release_sock(sk);
 
         if (noblock)
                 return -EAGAIN;
         goto try_again;
 }
 
 
 int udp_disconnect(struct sock *sk, int flags)
 {
         struct inet_sock *inet = inet_sk(sk);
         /*
          *        1003.1g - break association.
          */
 
         sk->sk_state = TCP_CLOSE;
         inet->daddr = 0;
         inet->dport = 0;
         sk->sk_bound_dev_if = 0;
         if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
                 inet_reset_saddr(sk);
 
         if (!(sk->sk_userlocks & SOCK_BINDPORT_LOCK)) {
                 sk->sk_prot->unhash(sk);
                 inet->sport = 0;
         }
         sk_dst_reset(sk);
         return 0;
 }
 
 static int __udp_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
 {
         int is_udplite = IS_UDPLITE(sk);
         int rc;
 
         if ((rc = sock_queue_rcv_skb(sk, skb)) < 0) {
                 /* Note that an ENOMEM error is charged twice */
                 if (rc == -ENOMEM)
                         UDP_INC_STATS_BH(sock_net(sk), UDP_MIB_RCVBUFERRORS,
                                          is_udplite);
                 goto drop;
         }
 
         return 0;
 
 drop:
         UDP_INC_STATS_BH(sock_net(sk), UDP_MIB_INERRORS, is_udplite);
         kfree_skb(skb);
         return -1;
 }
 
 /* returns:
  *  -1: error
  *   0: success
  *  >0: "udp encap" protocol resubmission
  *
  * Note that in the success and error cases, the skb is assumed to
  * have either been requeued or freed.
  */
 int udp_queue_rcv_skb(struct sock * sk, struct sk_buff *skb)
 {
         struct udp_sock *up = udp_sk(sk);
         int rc;
         int is_udplite = IS_UDPLITE(sk);
 
         /*
          *        Charge it to the socket, dropping if the queue is full.
          */
         if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
                 goto drop;
         nf_reset(skb);
 
         if (up->encap_type) {
                 /*
                  * This is an encapsulation socket so pass the skb to
                  * the socket's udp_encap_rcv() hook. Otherwise, just
                  * fall through and pass this up the UDP socket.
                  * up->encap_rcv() returns the following value:
                  * =0 if skb was successfully passed to the encap
                  *    handler or was discarded by it.
                  * >0 if skb should be passed on to UDP.
                  * <0 if skb should be resubmitted as proto -N
                  */
 
                 /* if we're overly short, let UDP handle it */
                 if (skb->len > sizeof(struct udphdr) &&
                     up->encap_rcv != NULL) {
                         int ret;
 
                         ret = (*up->encap_rcv)(sk, skb);
                         if (ret <= 0) {
                                 UDP_INC_STATS_BH(sock_net(sk),
                                                 UDP_MIB_INDATAGRAMS,
                                                 is_udplite);
                                return -ret;
                        }
                }

                /* FALLTHROUGH -- it's a UDP Packet */
        }

        /*
         *         UDP-Lite specific tests, ignored on UDP sockets
         */
        if ((is_udplite & UDPLITE_RECV_CC)  &&  UDP_SKB_CB(skb)->partial_cov) {

                /*
                 * MIB statistics other than incrementing the error count are
                 * disabled for the following two types of errors: these depend
                 * on the application settings, not on the functioning of the
                 * protocol stack as such.
                 *
                 * RFC 3828 here recommends (sec 3.3): "There should also be a
                 * way ... to ... at least let the receiving application block
                 * delivery of packets with coverage values less than a value
                 * provided by the application."
                 */
                if (up->pcrlen == 0) {          /* full coverage was set  */
                        LIMIT_NETDEBUG(KERN_WARNING "UDPLITE: partial coverage "
                                "%d while full coverage %d requested\n",
                                UDP_SKB_CB(skb)->cscov, skb->len);
                        goto drop;
                }
                /* The next case involves violating the min. coverage requested
                 * by the receiver. This is subtle: if receiver wants x and x is
                 * greater than the buffersize/MTU then receiver will complain
                 * that it wants x while sender emits packets of smaller size y.
                 * Therefore the above ...()->partial_cov statement is essential.
                 */
                if (UDP_SKB_CB(skb)->cscov  <  up->pcrlen) {
                        LIMIT_NETDEBUG(KERN_WARNING
                                "UDPLITE: coverage %d too small, need min %d\n",
                                UDP_SKB_CB(skb)->cscov, up->pcrlen);
                        goto drop;
                }
        }

        if (sk->sk_filter) {
                if (udp_lib_checksum_complete(skb))
                        goto drop;
        }

        rc = 0;

        bh_lock_sock(sk);
        if (!sock_owned_by_user(sk))
                rc = __udp_queue_rcv_skb(sk, skb);
        else
                sk_add_backlog(sk, skb);
        bh_unlock_sock(sk);

        return rc;

drop:
        UDP_INC_STATS_BH(sock_net(sk), UDP_MIB_INERRORS, is_udplite);
        kfree_skb(skb);
        return -1;
}

/*
 *        Multicasts and broadcasts go to each listener.
 *
 *        Note: called only from the BH handler context,
 *        so we don't need to lock the hashes.
 */
static int __udp4_lib_mcast_deliver(struct net *net, struct sk_buff *skb,
                                    struct udphdr  *uh,
                                    __be32 saddr, __be32 daddr,
                                    struct hlist_head udptable[])
{
        struct sock *sk;
        int dif;

        read_lock(&udp_hash_lock);
        sk = sk_head(&udptable[udp_hashfn(net, ntohs(uh->dest))]);
        dif = skb->dev->ifindex;
        sk = udp_v4_mcast_next(net, sk, uh->dest, daddr, uh->source, saddr, dif);
        if (sk) {
                struct sock *sknext = NULL;

                do {
                        struct sk_buff *skb1 = skb;

                        sknext = udp_v4_mcast_next(net, sk_next(sk), uh->dest,
                                                   daddr, uh->source, saddr,
                                                   dif);
                        if (sknext)
                                skb1 = skb_clone(skb, GFP_ATOMIC);

                        if (skb1) {
                                int ret = udp_queue_rcv_skb(sk, skb1);
                                if (ret > 0)
                                        /* we should probably re-process instead
                                         * of dropping packets here. */
                                        kfree_skb(skb1);
                        }
                        sk = sknext;
                } while (sknext);
        } else
                kfree_skb(skb);
        read_unlock(&udp_hash_lock);
        return 0;
}

/* Initialize UDP checksum. If exited with zero value (success),
 * CHECKSUM_UNNECESSARY means, that no more checks are required.
 * Otherwise, csum completion requires chacksumming packet body,
 * including udp header and folding it to skb->csum.
 */
static inline int udp4_csum_init(struct sk_buff *skb, struct udphdr *uh,
                                 int proto)
{
        const struct iphdr *iph;
        int err;

        UDP_SKB_CB(skb)->partial_cov = 0;
        UDP_SKB_CB(skb)->cscov = skb->len;

        if (proto == IPPROTO_UDPLITE) {
                err = udplite_checksum_init(skb, uh);
                if (err)
                        return err;
        }

        iph = ip_hdr(skb);
        if (uh->check == 0) {
                skb->ip_summed = CHECKSUM_UNNECESSARY;
        } else if (skb->ip_summed == CHECKSUM_COMPLETE) {
               if (!csum_tcpudp_magic(iph->saddr, iph->daddr, skb->len,
                                      proto, skb->csum))
                        skb->ip_summed = CHECKSUM_UNNECESSARY;
        }
        if (!skb_csum_unnecessary(skb))
                skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
                                               skb->len, proto, 0);
        /* Probably, we should checksum udp header (it should be in cache
         * in any case) and data in tiny packets (< rx copybreak).
         */

        return 0;
}

/*
 *        All we need to do is get the socket, and then do a checksum.
 */

int __udp4_lib_rcv(struct sk_buff *skb, struct hlist_head udptable[],
                   int proto)
{
        struct sock *sk;
        struct udphdr *uh = udp_hdr(skb);
        unsigned short ulen;
        struct rtable *rt = (struct rtable*)skb->dst;
        __be32 saddr = ip_hdr(skb)->saddr;
        __be32 daddr = ip_hdr(skb)->daddr;
        struct net *net = dev_net(skb->dev);

        /*
         *  Validate the packet.
         */
        if (!pskb_may_pull(skb, sizeof(struct udphdr)))
                goto drop;                /* No space for header. */

        ulen = ntohs(uh->len);
        if (ulen > skb->len)
                goto short_packet;

        if (proto == IPPROTO_UDP) {
                /* UDP validates ulen. */
                if (ulen < sizeof(*uh) || pskb_trim_rcsum(skb, ulen))
                        goto short_packet;
                uh = udp_hdr(skb);
        }

        if (udp4_csum_init(skb, uh, proto))
                goto csum_error;

        if (rt->rt_flags & (RTCF_BROADCAST|RTCF_MULTICAST))
                return __udp4_lib_mcast_deliver(net, skb, uh,
                                saddr, daddr, udptable);

        sk = __udp4_lib_lookup_skb(skb, uh->source, uh->dest, udptable);

        if (sk != NULL) {
                int ret = udp_queue_rcv_skb(sk, skb);
                sock_put(sk);

                /* a return value > 0 means to resubmit the input, but
                 * it wants the return to be -protocol, or 0
                 */
                if (ret > 0)
                        return -ret;
                return 0;
        }

        if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
                goto drop;
        nf_reset(skb);

        /* No socket. Drop packet silently, if checksum is wrong */
        if (udp_lib_checksum_complete(skb))
                goto csum_error;

        UDP_INC_STATS_BH(net, UDP_MIB_NOPORTS, proto == IPPROTO_UDPLITE);
        icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);

        /*
         * Hmm.  We got an UDP packet to a port to which we
         * don't wanna listen.  Ignore it.
         */
        kfree_skb(skb);
        return 0;

short_packet:
        LIMIT_NETDEBUG(KERN_DEBUG "UDP%s: short packet: From " NIPQUAD_FMT ":%u %d/%d to " NIPQUAD_FMT ":%u\n",
                       proto == IPPROTO_UDPLITE ? "-Lite" : "",
                       NIPQUAD(saddr),
                       ntohs(uh->source),
                       ulen,
                       skb->len,
                       NIPQUAD(daddr),
                       ntohs(uh->dest));
        goto drop;

csum_error:
        /*
         * RFC1122: OK.  Discards the bad packet silently (as far as
         * the network is concerned, anyway) as per 4.1.3.4 (MUST).
         */
        LIMIT_NETDEBUG(KERN_DEBUG "UDP%s: bad checksum. From " NIPQUAD_FMT ":%u to " NIPQUAD_FMT ":%u ulen %d\n",
                       proto == IPPROTO_UDPLITE ? "-Lite" : "",
                       NIPQUAD(saddr),
                       ntohs(uh->source),
                       NIPQUAD(daddr),
                       ntohs(uh->dest),
                       ulen);
drop:
        UDP_INC_STATS_BH(net, UDP_MIB_INERRORS, proto == IPPROTO_UDPLITE);
        kfree_skb(skb);
        return 0;
}

int udp_rcv(struct sk_buff *skb)
{
        return __udp4_lib_rcv(skb, udp_hash, IPPROTO_UDP);
}

void udp_destroy_sock(struct sock *sk)
{
        lock_sock(sk);
        udp_flush_pending_frames(sk);
        release_sock(sk);
}

/*
 *        Socket option code for UDP
 */
int udp_lib_setsockopt(struct sock *sk, int level, int optname,
                       char __user *optval, int optlen,
                       int (*push_pending_frames)(struct sock *))
{
        struct udp_sock *up = udp_sk(sk);
        int val;
        int err = 0;
        int is_udplite = IS_UDPLITE(sk);

        if (optlen<sizeof(int))
                return -EINVAL;

        if (get_user(val, (int __user *)optval))
                return -EFAULT;

        switch (optname) {
        case UDP_CORK:
                if (val != 0) {
                        up->corkflag = 1;
                } else {
                        up->corkflag = 0;
                        lock_sock(sk);
                        (*push_pending_frames)(sk);
                        release_sock(sk);
                }
                break;

        case UDP_ENCAP:
                switch (val) {
                case 0:
                case UDP_ENCAP_ESPINUDP:
                case UDP_ENCAP_ESPINUDP_NON_IKE:
                        up->encap_rcv = xfrm4_udp_encap_rcv;
                        /* FALLTHROUGH */
                case UDP_ENCAP_L2TPINUDP:
                        up->encap_type = val;
                        break;
                default:
                        err = -ENOPROTOOPT;
                        break;
                }
                break;

        /*
         *         UDP-Lite's partial checksum coverage (RFC 3828).
         */
        /* The sender sets actual checksum coverage length via this option.
         * The case coverage > packet length is handled by send module. */
        case UDPLITE_SEND_CSCOV:
                if (!is_udplite)         /* Disable the option on UDP sockets */
                        return -ENOPROTOOPT;
                if (val != 0 && val < 8) /* Illegal coverage: use default (8) */
                        val = 8;
                else if (val > USHORT_MAX)
                        val = USHORT_MAX;
                up->pcslen = val;
                up->pcflag |= UDPLITE_SEND_CC;
                break;

        /* The receiver specifies a minimum checksum coverage value. To make
         * sense, this should be set to at least 8 (as done below). If zero is
         * used, this again means full checksum coverage.                     */
        case UDPLITE_RECV_CSCOV:
                if (!is_udplite)         /* Disable the option on UDP sockets */
                        return -ENOPROTOOPT;
                if (val != 0 && val < 8) /* Avoid silly minimal values.       */
                        val = 8;
                else if (val > USHORT_MAX)
                        val = USHORT_MAX;
                up->pcrlen = val;
                up->pcflag |= UDPLITE_RECV_CC;
                break;

        default:
                err = -ENOPROTOOPT;
                break;
        }

        return err;
}

int udp_setsockopt(struct sock *sk, int level, int optname,
                   char __user *optval, int optlen)
{
        if (level == SOL_UDP  ||  level == SOL_UDPLITE)
                return udp_lib_setsockopt(sk, level, optname, optval, optlen,
                                          udp_push_pending_frames);
        return ip_setsockopt(sk, level, optname, optval, optlen);
}

#ifdef CONFIG_COMPAT
int compat_udp_setsockopt(struct sock *sk, int level, int optname,
                          char __user *optval, int optlen)
{
        if (level == SOL_UDP  ||  level == SOL_UDPLITE)
                return udp_lib_setsockopt(sk, level, optname, optval, optlen,
                                          udp_push_pending_frames);
        return compat_ip_setsockopt(sk, level, optname, optval, optlen);
}
#endif

int udp_lib_getsockopt(struct sock *sk, int level, int optname,
                       char __user *optval, int __user *optlen)
{
        struct udp_sock *up = udp_sk(sk);
        int val, len;

        if (get_user(len,optlen))
                return -EFAULT;

        len = min_t(unsigned int, len, sizeof(int));

        if (len < 0)
                return -EINVAL;

        switch (optname) {
        case UDP_CORK:
                val = up->corkflag;
                break;

        case UDP_ENCAP:
                val = up->encap_type;
                break;

        /* The following two cannot be changed on UDP sockets, the return is
         * always 0 (which corresponds to the full checksum coverage of UDP). */
        case UDPLITE_SEND_CSCOV:
                val = up->pcslen;
                break;

        case UDPLITE_RECV_CSCOV:
                val = up->pcrlen;
                break;

        default:
                return -ENOPROTOOPT;
        }

        if (put_user(len, optlen))
                return -EFAULT;
        if (copy_to_user(optval, &val,len))
                return -EFAULT;
        return 0;
}

int udp_getsockopt(struct sock *sk, int level, int optname,
                   char __user *optval, int __user *optlen)
{
        if (level == SOL_UDP  ||  level == SOL_UDPLITE)
                return udp_lib_getsockopt(sk, level, optname, optval, optlen);
        return ip_getsockopt(sk, level, optname, optval, optlen);
}

#ifdef CONFIG_COMPAT
int compat_udp_getsockopt(struct sock *sk, int level, int optname,
                                 char __user *optval, int __user *optlen)
{
        if (level == SOL_UDP  ||  level == SOL_UDPLITE)
                return udp_lib_getsockopt(sk, level, optname, optval, optlen);
        return compat_ip_getsockopt(sk, level, optname, optval, optlen);
}
#endif
/**
 *         udp_poll - wait for a UDP event.
 *        @file - file struct
 *        @sock - socket
 *        @wait - poll table
 *
 *        This is same as datagram poll, except for the special case of
 *        blocking sockets. If application is using a blocking fd
 *        and a packet with checksum error is in the queue;
 *        then it could get return from select indicating data available
 *        but then block when reading it. Add special case code
 *        to work around these arguably broken applications.
 */
unsigned int udp_poll(struct file *file, struct socket *sock, poll_table *wait)
{
        unsigned int mask = datagram_poll(file, sock, wait);
        struct sock *sk = sock->sk;
        int         is_lite = IS_UDPLITE(sk);

        /* Check for false positives due to checksum errors */
        if ( (mask & POLLRDNORM) &&
             !(file->f_flags & O_NONBLOCK) &&
             !(sk->sk_shutdown & RCV_SHUTDOWN)){
                struct sk_buff_head *rcvq = &sk->sk_receive_queue;
                struct sk_buff *skb;

                spin_lock_bh(&rcvq->lock);
                while ((skb = skb_peek(rcvq)) != NULL &&
                       udp_lib_checksum_complete(skb)) {
                        UDP_INC_STATS_BH(sock_net(sk),
                                        UDP_MIB_INERRORS, is_lite);
                        __skb_unlink(skb, rcvq);
                        kfree_skb(skb);
                }
                spin_unlock_bh(&rcvq->lock);

                /* nothing to see, move along */
                if (skb == NULL)
                        mask &= ~(POLLIN | POLLRDNORM);
        }

        return mask;

}

struct proto udp_prot = {
        .name                   = "UDP",
        .owner                   = THIS_MODULE,
        .close                   = udp_lib_close,
        .connect           = ip4_datagram_connect,
        .disconnect           = udp_disconnect,
        .ioctl                   = udp_ioctl,
        .destroy           = udp_destroy_sock,
        .setsockopt           = udp_setsockopt,
        .getsockopt           = udp_getsockopt,
        .sendmsg           = udp_sendmsg,
        .recvmsg           = udp_recvmsg,
        .sendpage           = udp_sendpage,
        .backlog_rcv           = __udp_queue_rcv_skb,
        .hash                   = udp_lib_hash,
        .unhash                   = udp_lib_unhash,
        .get_port           = udp_v4_get_port,
        .memory_allocated  = &udp_memory_allocated,
        .sysctl_mem           = sysctl_udp_mem,
        .sysctl_wmem           = &sysctl_udp_wmem_min,
        .sysctl_rmem           = &sysctl_udp_rmem_min,
        .obj_size           = sizeof(struct udp_sock),
        .h.udp_hash           = udp_hash,
#ifdef CONFIG_COMPAT
        .compat_setsockopt = compat_udp_setsockopt,
        .compat_getsockopt = compat_udp_getsockopt,
#endif
};

/* ------------------------------------------------------------------------ */
#ifdef CONFIG_PROC_FS

static struct sock *udp_get_first(struct seq_file *seq)
{
        struct sock *sk;
        struct udp_iter_state *state = seq->private;
        struct net *net = seq_file_net(seq);

        for (state->bucket = 0; state->bucket < UDP_HTABLE_SIZE; ++state->bucket) {
                struct hlist_node *node;
                sk_for_each(sk, node, state->hashtable + state->bucket) {
                        if (!net_eq(sock_net(sk), net))
                                continue;
                        if (sk->sk_family == state->family)
                                goto found;
                }
        }
        sk = NULL;
found:
        return sk;
}

static struct sock *udp_get_next(struct seq_file *seq, struct sock *sk)
{
        struct udp_iter_state *state = seq->private;
        struct net *net = seq_file_net(seq);

        do {
                sk = sk_next(sk);
try_again:
                ;
        } while (sk && (!net_eq(sock_net(sk), net) || sk->sk_family != state->family));

        if (!sk && ++state->bucket < UDP_HTABLE_SIZE) {
                sk = sk_head(state->hashtable + state->bucket);
                goto try_again;
        }
        return sk;
}

static struct sock *udp_get_idx(struct seq_file *seq, loff_t pos)
{
        struct sock *sk = udp_get_first(seq);

        if (sk)
                while (pos && (sk = udp_get_next(seq, sk)) != NULL)
                        --pos;
        return pos ? NULL : sk;
}

static void *udp_seq_start(struct seq_file *seq, loff_t *pos)
        __acquires(udp_hash_lock)
{
        read_lock(&udp_hash_lock);
        return *pos ? udp_get_idx(seq, *pos-1) : SEQ_START_TOKEN;
}

static void *udp_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
        struct sock *sk;

        if (v == SEQ_START_TOKEN)
                sk = udp_get_idx(seq, 0);
        else
                sk = udp_get_next(seq, v);

        ++*pos;
        return sk;
}

static void udp_seq_stop(struct seq_file *seq, void *v)
        __releases(udp_hash_lock)
{
        read_unlock(&udp_hash_lock);
}

static int udp_seq_open(struct inode *inode, struct file *file)
{
        struct udp_seq_afinfo *afinfo = PDE(inode)->data;
        struct udp_iter_state *s;
        int err;

        err = seq_open_net(inode, file, &afinfo->seq_ops,
                           sizeof(struct udp_iter_state));
        if (err < 0)
                return err;

        s = ((struct seq_file *)file->private_data)->private;
        s->family                = afinfo->family;
        s->hashtable                = afinfo->hashtable;
        return err;
}

/* ------------------------------------------------------------------------ */
int udp_proc_register(struct net *net, struct udp_seq_afinfo *afinfo)
{
        struct proc_dir_entry *p;
        int rc = 0;

        afinfo->seq_fops.open                = udp_seq_open;
        afinfo->seq_fops.read                = seq_read;
        afinfo->seq_fops.llseek                = seq_lseek;
        afinfo->seq_fops.release        = seq_release_net;

        afinfo->seq_ops.start                = udp_seq_start;
        afinfo->seq_ops.next                = udp_seq_next;
        afinfo->seq_ops.stop                = udp_seq_stop;

        p = proc_create_data(afinfo->name, S_IRUGO, net->proc_net,
                             &afinfo->seq_fops, afinfo);
        if (!p)
                rc = -ENOMEM;
        return rc;
}

void udp_proc_unregister(struct net *net, struct udp_seq_afinfo *afinfo)
{
        proc_net_remove(net, afinfo->name);
}

/* ------------------------------------------------------------------------ */
static void udp4_format_sock(struct sock *sp, struct seq_file *f,
                int bucket, int *len)
{
        struct inet_sock *inet = inet_sk(sp);
        __be32 dest = inet->daddr;
        __be32 src  = inet->rcv_saddr;
        __u16 destp          = ntohs(inet->dport);
        __u16 srcp          = ntohs(inet->sport);

        seq_printf(f, "%4d: %08X:%04X %08X:%04X"
                " %02X %08X:%08X %02X:%08lX %08X %5d %8d %lu %d %p %d%n",
                bucket, src, srcp, dest, destp, sp->sk_state,
                atomic_read(&sp->sk_wmem_alloc),
                atomic_read(&sp->sk_rmem_alloc),
                0, 0L, 0, sock_i_uid(sp), 0, sock_i_ino(sp),
                atomic_read(&sp->sk_refcnt), sp,
                atomic_read(&sp->sk_drops), len);
}

int udp4_seq_show(struct seq_file *seq, void *v)
{
        if (v == SEQ_START_TOKEN)
                seq_printf(seq, "%-127s\n",
                           "  sl  local_address rem_address   st tx_queue "
                           "rx_queue tr tm->when retrnsmt   uid  timeout "
                           "inode ref pointer drops");
        else {
                struct udp_iter_state *state = seq->private;
                int len;

                udp4_format_sock(v, seq, state->bucket, &len);
                seq_printf(seq, "%*s\n", 127 - len ,"");
        }
        return 0;
}

/* ------------------------------------------------------------------------ */
static struct udp_seq_afinfo udp4_seq_afinfo = {
        .name                = "udp",
        .family                = AF_INET,
        .hashtable        = udp_hash,
        .seq_fops        = {
                .owner        =        THIS_MODULE,
        },
        .seq_ops        = {
                .show                = udp4_seq_show,
        },
};

static int udp4_proc_init_net(struct net *net)
{
        return udp_proc_register(net, &udp4_seq_afinfo);
}

static void udp4_proc_exit_net(struct net *net)
{
        udp_proc_unregister(net, &udp4_seq_afinfo);
}

static struct pernet_operations udp4_net_ops = {
        .init = udp4_proc_init_net,
        .exit = udp4_proc_exit_net,
};

int __init udp4_proc_init(void)
{
        return register_pernet_subsys(&udp4_net_ops);
}

void udp4_proc_exit(void)
{
        unregister_pernet_subsys(&udp4_net_ops);
}
#endif /* CONFIG_PROC_FS */

void __init udp_init(void)
{
        unsigned long limit;

        /* Set the pressure threshold up by the same strategy of TCP. It is a
         * fraction of global memory that is up to 1/2 at 256 MB, decreasing
         * toward zero with the amount of memory, with a floor of 128 pages.
         */
        limit = min(nr_all_pages, 1UL<<(28-PAGE_SHIFT)) >> (20-PAGE_SHIFT);
        limit = (limit * (nr_all_pages >> (20-PAGE_SHIFT))) >> (PAGE_SHIFT-11);
        limit = max(limit, 128UL);
        sysctl_udp_mem[0] = limit / 4 * 3;
        sysctl_udp_mem[1] = limit;
        sysctl_udp_mem[2] = sysctl_udp_mem[0] * 2;

        sysctl_udp_rmem_min = SK_MEM_QUANTUM;
        sysctl_udp_wmem_min = SK_MEM_QUANTUM;
}

EXPORT_SYMBOL(udp_disconnect);
EXPORT_SYMBOL(udp_hash);
EXPORT_SYMBOL(udp_hash_lock);
EXPORT_SYMBOL(udp_ioctl);
EXPORT_SYMBOL(udp_prot);
EXPORT_SYMBOL(udp_sendmsg);
EXPORT_SYMBOL(udp_lib_getsockopt);
EXPORT_SYMBOL(udp_lib_setsockopt);
EXPORT_SYMBOL(udp_poll);
EXPORT_SYMBOL(udp_lib_get_port);

#ifdef CONFIG_PROC_FS
EXPORT_SYMBOL(udp_proc_register);
EXPORT_SYMBOL(udp_proc_unregister);
#endif