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 sock *sk;
  45         struct pn_sock *pn;
  46         struct phonet_protocol *pnp;
  47         int err;
  48
  49         if (net != &init_net)
  50                 return -EAFNOSUPPORT;
  51
  52         if (!capable(CAP_SYS_ADMIN))
  53                 return -EPERM;
  54
  55         if (protocol == 0) {
  56                 /* Default protocol selection */
  57                 switch (sock->type) {
  58                 case SOCK_DGRAM:
  59                         protocol = PN_PROTO_PHONET;
  60                         break;
  61                 default:
  62                         return -EPROTONOSUPPORT;
  63                 }
  64         }
  65
  66         pnp = phonet_proto_get(protocol);
  67         if (pnp == NULL)
  68                 return -EPROTONOSUPPORT;
  69         if (sock->type != pnp->sock_type) {
  70                 err = -EPROTONOSUPPORT;
  71                 goto out;
  72         }
  73
  74         sk = sk_alloc(net, PF_PHONET, GFP_KERNEL, pnp->prot);
  75         if (sk == NULL) {
  76                 err = -ENOMEM;
  77                 goto out;
  78         }
  79
  80         sock_init_data(sock, sk);
  81         sock->state = SS_UNCONNECTED;
  82         sock->ops = pnp->ops;
  83         sk->sk_backlog_rcv = sk->sk_prot->backlog_rcv;
  84         sk->sk_protocol = protocol;
  85         pn = pn_sk(sk);
  86         pn->sobject = 0;
  87         pn->resource = 0;
  88         sk->sk_prot->init(sk);
  89         err = 0;
  90
  91 out:
  92         phonet_proto_put(pnp);
  93         return err;
  94 }
  95
  96 static struct net_proto_family phonet_proto_family = {
  97         .family = AF_PHONET,
  98         .create = pn_socket_create,
  99         .owner = THIS_MODULE,
 100 };
 101
 102 /* packet type functions */
 103
 104 /*
 105  * Stuff received packets to associated sockets.
 106  * On error, returns non-zero and releases the skb.
 107  */
 108 static int phonet_rcv(struct sk_buff *skb, struct net_device *dev,
 109                         struct packet_type *pkttype,
 110                         struct net_device *orig_dev)
 111 {
 112         struct phonethdr *ph;
 113         struct sock *sk;
 114         struct sockaddr_pn sa;
 115         u16 len;
 116
 117         if (dev_net(dev) != &init_net)
 118                 goto out;
 119
 120         /* check we have at least a full Phonet header */
 121         if (!pskb_pull(skb, sizeof(struct phonethdr)))
 122                 goto out;
 123
 124         /* check that the advertised length is correct */
 125         ph = pn_hdr(skb);
 126         len = get_unaligned_be16(&ph->pn_length);
 127         if (len < 2)
 128                 goto out;
 129         len -= 2;
 130         if ((len > skb->len) || pskb_trim(skb, len))
 131                 goto out;
 132         skb_reset_transport_header(skb);
 133
 134         pn_skb_get_dst_sockaddr(skb, &sa);
 135         if (pn_sockaddr_get_addr(&sa) == 0)
 136                 goto out; /* currently, we cannot be device 0 */
 137
 138         sk = pn_find_sock_by_sa(&sa);
 139         if (sk == NULL)
 140                 goto out;
 141
 142         /* Push data to the socket (or other sockets connected to it). */
 143         return sk_receive_skb(sk, skb, 0);
 144
 145 out:
 146         kfree_skb(skb);
 147         return NET_RX_DROP;
 148 }
 149
 150 static struct packet_type phonet_packet_type = {
 151         .type = __constant_htons(ETH_P_PHONET),
 152         .dev = NULL,
 153         .func = phonet_rcv,
 154 };
 155
 156 /* Transport protocol registration */
 157 static struct phonet_protocol *proto_tab[PHONET_NPROTO] __read_mostly;
 158 static DEFINE_SPINLOCK(proto_tab_lock);
 159
 160 int __init_or_module phonet_proto_register(int protocol,
 161                                                 struct phonet_protocol *pp)
 162 {
 163         int err = 0;
 164
 165         if (protocol >= PHONET_NPROTO)
 166                 return -EINVAL;
 167
 168         err = proto_register(pp->prot, 1);
 169         if (err)
 170                 return err;
 171
 172         spin_lock(&proto_tab_lock);
 173         if (proto_tab[protocol])
 174                 err = -EBUSY;
 175         else
 176                 proto_tab[protocol] = pp;
 177         spin_unlock(&proto_tab_lock);
 178
 179         return err;
 180 }
 181 EXPORT_SYMBOL(phonet_proto_register);
 182
 183 void phonet_proto_unregister(int protocol, struct phonet_protocol *pp)
 184 {
 185         spin_lock(&proto_tab_lock);
 186         BUG_ON(proto_tab[protocol] != pp);
 187         proto_tab[protocol] = NULL;
 188         spin_unlock(&proto_tab_lock);
 189         proto_unregister(pp->prot);
 190 }
 191 EXPORT_SYMBOL(phonet_proto_unregister);
 192
 193 static struct phonet_protocol *phonet_proto_get(int protocol)
 194 {
 195         struct phonet_protocol *pp;
 196
 197         if (protocol >= PHONET_NPROTO)
 198                 return NULL;
 199
 200         spin_lock(&proto_tab_lock);
 201         pp = proto_tab[protocol];
 202         if (pp && !try_module_get(pp->prot->owner))
 203                 pp = NULL;
 204         spin_unlock(&proto_tab_lock);
 205
 206         return pp;
 207 }
 208
 209 static inline void phonet_proto_put(struct phonet_protocol *pp)
 210 {
 211         module_put(pp->prot->owner);
 212 }
 213
 214 /* Module registration */
 215 static int __init phonet_init(void)
 216 {
 217         int err;
 218
 219         err = sock_register(&phonet_proto_family);
 220         if (err) {
 221                 printk(KERN_ALERT
 222                         "phonet protocol family initialization failed\n");
 223                 return err;
 224         }
 225
 226         phonet_device_init();
 227         dev_add_pack(&phonet_packet_type);
 228         phonet_netlink_register();
 229         return 0;
 230 }
 231
 232 static void __exit phonet_exit(void)
 233 {
 234         sock_unregister(AF_PHONET);
 235         dev_remove_pack(&phonet_packet_type);
 236         phonet_device_exit();
 237 }
 238
 239 module_init(phonet_init);
 240 module_exit(phonet_exit);
 241 MODULE_DESCRIPTION("Phonet protocol stack for Linux");
 242 MODULE_LICENSE("GPL");