net/phonet/af_phonet.c

   1 /*
   2  * File: af_phonet.c
   3  *
   4  * Phonet protocols family
   5  *
   6  * Copyright (C) 2008 Nokia Corporation.
   7  *
   8  * Contact: Remi Denis-Courmont <remi.denis-courmont@nokia.com>
   9  * Original author: Sakari Ailus <sakari.ailus@nokia.com>
  10  *
  11  * This program is free software; you can redistribute it and/or
  12  * modify it under the terms of the GNU General Public License
  13  * version 2 as published by the Free Software Foundation.
  14  *
  15  * This program is distributed in the hope that it will be useful, but
  16  * WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18  * General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, write to the Free Software
  22  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
  23  * 02110-1301 USA
  24  */
  25
  26 #include <linux/kernel.h>
  27 #include <linux/module.h>
  28 #include <asm/unaligned.h>
  29 #include <net/sock.h>
  30
  31 #include <linux/if_phonet.h>
  32 #include <linux/phonet.h>
  33 #include <net/phonet/phonet.h>
  34 #include <net/phonet/pn_dev.h>
  35
  36 static struct net_proto_family phonet_proto_family;
  37 static struct phonet_protocol *phonet_proto_get(int protocol);
  38 static inline void phonet_proto_put(struct phonet_protocol *pp);
  39
  40 /* protocol family functions */
  41
  42 static int pn_socket_create(struct net *net, struct socket *sock, int protocol)
  43 {
  44         struct phonet_protocol *pnp;
  45         int err;
  46
  47         if (net != &init_net)
  48                 return -EAFNOSUPPORT;
  49
  50         if (!capable(CAP_SYS_ADMIN))
  51                 return -EPERM;
  52
  53         if (protocol == 0) {
  54                 /* Default protocol selection */
  55                 switch (sock->type) {
  56                 case SOCK_DGRAM:
  57                         protocol = PN_PROTO_PHONET;
  58                         break;
  59                 default:
  60                         return -EPROTONOSUPPORT;
  61                 }
  62         }
  63
  64         pnp = phonet_proto_get(protocol);
  65         if (pnp == NULL)
  66                 return -EPROTONOSUPPORT;
  67         if (sock->type != pnp->sock_type) {
  68                 err = -EPROTONOSUPPORT;
  69                 goto out;
  70         }
  71
  72         /* TODO: create and init the struct sock */
  73         err = -EPROTONOSUPPORT;
  74
  75 out:
  76         phonet_proto_put(pnp);
  77         return err;
  78 }
  79
  80 static struct net_proto_family phonet_proto_family = {
  81         .family = AF_PHONET,
  82         .create = pn_socket_create,
  83         .owner = THIS_MODULE,
  84 };
  85
  86 /* packet type functions */
  87
  88 /*
  89  * Stuff received packets to associated sockets.
  90  * On error, returns non-zero and releases the skb.
  91  */
  92 static int phonet_rcv(struct sk_buff *skb, struct net_device *dev,
  93                         struct packet_type *pkttype,
  94                         struct net_device *orig_dev)
  95 {
  96         struct phonethdr *ph;
  97         struct sockaddr_pn sa;
  98         u16 len;
  99
 100         if (dev_net(dev) != &init_net)
 101                 goto out;
 102
 103         /* check we have at least a full Phonet header */
 104         if (!pskb_pull(skb, sizeof(struct phonethdr)))
 105                 goto out;
 106
 107         /* check that the advertised length is correct */
 108         ph = pn_hdr(skb);
 109         len = get_unaligned_be16(&ph->pn_length);
 110         if (len < 2)
 111                 goto out;
 112         len -= 2;
 113         if ((len > skb->len) || pskb_trim(skb, len))
 114                 goto out;
 115         skb_reset_transport_header(skb);
 116
 117         pn_skb_get_dst_sockaddr(skb, &sa);
 118         if (pn_sockaddr_get_addr(&sa) == 0)
 119                 goto out; /* currently, we cannot be device 0 */
 120
 121         /* TODO: put packets to sockets backlog */
 122
 123 out:
 124         kfree_skb(skb);
 125         return NET_RX_DROP;
 126 }
 127
 128 static struct packet_type phonet_packet_type = {
 129         .type = __constant_htons(ETH_P_PHONET),
 130         .dev = NULL,
 131         .func = phonet_rcv,
 132 };
 133
 134 /* Transport protocol registration */
 135 static struct phonet_protocol *proto_tab[PHONET_NPROTO] __read_mostly;
 136 static DEFINE_SPINLOCK(proto_tab_lock);
 137
 138 int __init_or_module phonet_proto_register(int protocol,
 139                                                 struct phonet_protocol *pp)
 140 {
 141         int err = 0;
 142
 143         if (protocol >= PHONET_NPROTO)
 144                 return -EINVAL;
 145
 146         err = proto_register(pp->prot, 1);
 147         if (err)
 148                 return err;
 149
 150         spin_lock(&proto_tab_lock);
 151         if (proto_tab[protocol])
 152                 err = -EBUSY;
 153         else
 154                 proto_tab[protocol] = pp;
 155         spin_unlock(&proto_tab_lock);
 156
 157         return err;
 158 }
 159 EXPORT_SYMBOL(phonet_proto_register);
 160
 161 void phonet_proto_unregister(int protocol, struct phonet_protocol *pp)
 162 {
 163         spin_lock(&proto_tab_lock);
 164         BUG_ON(proto_tab[protocol] != pp);
 165         proto_tab[protocol] = NULL;
 166         spin_unlock(&proto_tab_lock);
 167         proto_unregister(pp->prot);
 168 }
 169 EXPORT_SYMBOL(phonet_proto_unregister);
 170
 171 static struct phonet_protocol *phonet_proto_get(int protocol)
 172 {
 173         struct phonet_protocol *pp;
 174
 175         if (protocol >= PHONET_NPROTO)
 176                 return NULL;
 177
 178         spin_lock(&proto_tab_lock);
 179         pp = proto_tab[protocol];
 180         if (pp && !try_module_get(pp->prot->owner))
 181                 pp = NULL;
 182         spin_unlock(&proto_tab_lock);
 183
 184         return pp;
 185 }
 186
 187 static inline void phonet_proto_put(struct phonet_protocol *pp)
 188 {
 189         module_put(pp->prot->owner);
 190 }
 191
 192 /* Module registration */
 193 static int __init phonet_init(void)
 194 {
 195         int err;
 196
 197         err = sock_register(&phonet_proto_family);
 198         if (err) {
 199                 printk(KERN_ALERT
 200                         "phonet protocol family initialization failed\n");
 201                 return err;
 202         }
 203
 204         phonet_device_init();
 205         dev_add_pack(&phonet_packet_type);
 206         phonet_netlink_register();
 207         return 0;
 208 }
 209
 210 static void __exit phonet_exit(void)
 211 {
 212         sock_unregister(AF_PHONET);
 213         dev_remove_pack(&phonet_packet_type);
 214         phonet_device_exit();
 215 }
 216
 217 module_init(phonet_init);
 218 module_exit(phonet_exit);
 219 MODULE_DESCRIPTION("Phonet protocol stack for Linux");
 220 MODULE_LICENSE("GPL");