net/ipv4/protocol.c

   1 /*
   2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   3  *              operating system.  INET is implemented using the  BSD Socket
   4  *              interface as the means of communication with the user level.
   5  *
   6  *              INET protocol dispatch tables.
   7  *
   8  * Authors:     Ross Biro
   9  *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
  10  *
  11  * Fixes:
  12  *              Alan Cox        : Ahah! udp icmp errors don't work because
  13  *                                udp_err is never called!
  14  *              Alan Cox        : Added new fields for init and ready for
  15  *                                proper fragmentation (_NO_ 4K limits!)
  16  *              Richard Colella : Hang on hash collision
  17  *              Vince Laviano   : Modified inet_del_protocol() to correctly
  18  *                                maintain copy bit.
  19  *
  20  *              This program is free software; you can redistribute it and/or
  21  *              modify it under the terms of the GNU General Public License
  22  *              as published by the Free Software Foundation; either version
  23  *              2 of the License, or (at your option) any later version.
  24  */
  25
  26 #include <asm/uaccess.h>
  27 #include <asm/system.h>
  28 #include <linux/module.h>
  29 #include <linux/types.h>
  30 #include <linux/kernel.h>
  31 #include <linux/string.h>
  32 #include <linux/socket.h>
  33 #include <linux/in.h>
  34 #include <linux/inet.h>
  35 #include <linux/netdevice.h>
  36 #include <linux/timer.h>
  37 #include <net/ip.h>
  38 #include <net/protocol.h>
  39 #include <linux/skbuff.h>
  40 #include <net/sock.h>
  41 #include <net/icmp.h>
  42 #include <net/udp.h>
  43 #include <net/ipip.h>
  44 #include <linux/igmp.h>
  45
  46 struct net_protocol *inet_protos[MAX_INET_PROTOS] ____cacheline_aligned_in_smp;
  47 static DEFINE_SPINLOCK(inet_proto_lock);
  48
  49 /*
  50  *      Add a protocol handler to the hash tables
  51  */
  52
  53 int inet_add_protocol(struct net_protocol *prot, unsigned char protocol)
  54 {
  55         int hash, ret;
  56
  57         hash = protocol & (MAX_INET_PROTOS - 1);
  58
  59         spin_lock_bh(&inet_proto_lock);
  60         if (inet_protos[hash]) {
  61                 ret = -1;
  62         } else {
  63                 inet_protos[hash] = prot;
  64                 ret = 0;
  65         }
  66         spin_unlock_bh(&inet_proto_lock);
  67
  68         return ret;
  69 }
  70
  71 /*
  72  *      Remove a protocol from the hash tables.
  73  */
  74
  75 int inet_del_protocol(struct net_protocol *prot, unsigned char protocol)
  76 {
  77         int hash, ret;
  78
  79         hash = protocol & (MAX_INET_PROTOS - 1);
  80
  81         spin_lock_bh(&inet_proto_lock);
  82         if (inet_protos[hash] == prot) {
  83                 inet_protos[hash] = NULL;
  84                 ret = 0;
  85         } else {
  86                 ret = -1;
  87         }
  88         spin_unlock_bh(&inet_proto_lock);
  89
  90         synchronize_net();
  91
  92         return ret;
  93 }
  94
  95 EXPORT_SYMBOL(inet_add_protocol);
  96 EXPORT_SYMBOL(inet_del_protocol);