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   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 /*
 103  * Prepends an ISI header and sends a datagram.
 104  */
 105 static int pn_send(struct sk_buff *skb, struct net_device *dev,
 106                         u16 dst, u16 src, u8 res)
 107 {
 108         struct phonethdr *ph;
 109         int err;
 110
 111         if (skb->len + 2 > 0xffff) {
 112                 /* Phonet length field would overflow */
 113                 err = -EMSGSIZE;
 114                 goto drop;
 115         }
 116
 117         skb_reset_transport_header(skb);
 118         WARN_ON(skb_headroom(skb) & 1); /* HW assumes word alignment */
 119         skb_push(skb, sizeof(struct phonethdr));
 120         skb_reset_network_header(skb);
 121         ph = pn_hdr(skb);
 122         ph->pn_rdev = pn_dev(dst);
 123         ph->pn_sdev = pn_dev(src);
 124         ph->pn_res = res;
 125         ph->pn_length = __cpu_to_be16(skb->len + 2 - sizeof(*ph));
 126         ph->pn_robj = pn_obj(dst);
 127         ph->pn_sobj = pn_obj(src);
 128
 129         skb->protocol = htons(ETH_P_PHONET);
 130         skb->priority = 0;
 131         skb->dev = dev;
 132
 133         if (pn_addr(src) == pn_addr(dst)) {
 134                 skb_reset_mac_header(skb);
 135                 skb->pkt_type = PACKET_LOOPBACK;
 136                 skb_orphan(skb);
 137                 netif_rx_ni(skb);
 138                 err = 0;
 139         } else {
 140                 err = dev_hard_header(skb, dev, ntohs(skb->protocol),
 141                                         NULL, NULL, skb->len);
 142                 if (err < 0) {
 143                         err = -EHOSTUNREACH;
 144                         goto drop;
 145                 }
 146                 err = dev_queue_xmit(skb);
 147         }
 148
 149         return err;
 150 drop:
 151         kfree_skb(skb);
 152         return err;
 153 }
 154
 155 /*
 156  * Create a Phonet header for the skb and send it out. Returns
 157  * non-zero error code if failed. The skb is freed then.
 158  */
 159 int pn_skb_send(struct sock *sk, struct sk_buff *skb,
 160                 const struct sockaddr_pn *target)
 161 {
 162         struct net_device *dev;
 163         struct pn_sock *pn = pn_sk(sk);
 164         int err;
 165         u16 src;
 166         u8 daddr = pn_sockaddr_get_addr(target), saddr = PN_NO_ADDR;
 167
 168         err = -EHOSTUNREACH;
 169         if (sk->sk_bound_dev_if)
 170                 dev = dev_get_by_index(sock_net(sk), sk->sk_bound_dev_if);
 171         else
 172                 dev = phonet_device_get(sock_net(sk));
 173         if (!dev || !(dev->flags & IFF_UP))
 174                 goto drop;
 175
 176         saddr = phonet_address_get(dev, daddr);
 177         if (saddr == PN_NO_ADDR)
 178                 goto drop;
 179
 180         src = pn->sobject;
 181         if (!pn_addr(src))
 182                 src = pn_object(saddr, pn_obj(src));
 183
 184         err = pn_send(skb, dev, pn_sockaddr_get_object(target),
 185                         src, pn_sockaddr_get_resource(target));
 186         dev_put(dev);
 187         return err;
 188
 189 drop:
 190         kfree_skb(skb);
 191         if (dev)
 192                 dev_put(dev);
 193         return err;
 194 }
 195 EXPORT_SYMBOL(pn_skb_send);
 196
 197 /* packet type functions */
 198
 199 /*
 200  * Stuff received packets to associated sockets.
 201  * On error, returns non-zero and releases the skb.
 202  */
 203 static int phonet_rcv(struct sk_buff *skb, struct net_device *dev,
 204                         struct packet_type *pkttype,
 205                         struct net_device *orig_dev)
 206 {
 207         struct phonethdr *ph;
 208         struct sock *sk;
 209         struct sockaddr_pn sa;
 210         u16 len;
 211
 212         if (dev_net(dev) != &init_net)
 213                 goto out;
 214
 215         /* check we have at least a full Phonet header */
 216         if (!pskb_pull(skb, sizeof(struct phonethdr)))
 217                 goto out;
 218
 219         /* check that the advertised length is correct */
 220         ph = pn_hdr(skb);
 221         len = get_unaligned_be16(&ph->pn_length);
 222         if (len < 2)
 223                 goto out;
 224         len -= 2;
 225         if ((len > skb->len) || pskb_trim(skb, len))
 226                 goto out;
 227         skb_reset_transport_header(skb);
 228
 229         pn_skb_get_dst_sockaddr(skb, &sa);
 230         if (pn_sockaddr_get_addr(&sa) == 0)
 231                 goto out; /* currently, we cannot be device 0 */
 232
 233         sk = pn_find_sock_by_sa(&sa);
 234         if (sk == NULL)
 235                 goto out;
 236
 237         /* Push data to the socket (or other sockets connected to it). */
 238         return sk_receive_skb(sk, skb, 0);
 239
 240 out:
 241         kfree_skb(skb);
 242         return NET_RX_DROP;
 243 }
 244
 245 static struct packet_type phonet_packet_type = {
 246         .type = __constant_htons(ETH_P_PHONET),
 247         .dev = NULL,
 248         .func = phonet_rcv,
 249 };
 250
 251 /* Transport protocol registration */
 252 static struct phonet_protocol *proto_tab[PHONET_NPROTO] __read_mostly;
 253 static DEFINE_SPINLOCK(proto_tab_lock);
 254
 255 int __init_or_module phonet_proto_register(int protocol,
 256                                                 struct phonet_protocol *pp)
 257 {
 258         int err = 0;
 259
 260         if (protocol >= PHONET_NPROTO)
 261                 return -EINVAL;
 262
 263         err = proto_register(pp->prot, 1);
 264         if (err)
 265                 return err;
 266
 267         spin_lock(&proto_tab_lock);
 268         if (proto_tab[protocol])
 269                 err = -EBUSY;
 270         else
 271                 proto_tab[protocol] = pp;
 272         spin_unlock(&proto_tab_lock);
 273
 274         return err;
 275 }
 276 EXPORT_SYMBOL(phonet_proto_register);
 277
 278 void phonet_proto_unregister(int protocol, struct phonet_protocol *pp)
 279 {
 280         spin_lock(&proto_tab_lock);
 281         BUG_ON(proto_tab[protocol] != pp);
 282         proto_tab[protocol] = NULL;
 283         spin_unlock(&proto_tab_lock);
 284         proto_unregister(pp->prot);
 285 }
 286 EXPORT_SYMBOL(phonet_proto_unregister);
 287
 288 static struct phonet_protocol *phonet_proto_get(int protocol)
 289 {
 290         struct phonet_protocol *pp;
 291
 292         if (protocol >= PHONET_NPROTO)
 293                 return NULL;
 294
 295         spin_lock(&proto_tab_lock);
 296         pp = proto_tab[protocol];
 297         if (pp && !try_module_get(pp->prot->owner))
 298                 pp = NULL;
 299         spin_unlock(&proto_tab_lock);
 300
 301         return pp;
 302 }
 303
 304 static inline void phonet_proto_put(struct phonet_protocol *pp)
 305 {
 306         module_put(pp->prot->owner);
 307 }
 308
 309 /* Module registration */
 310 static int __init phonet_init(void)
 311 {
 312         int err;
 313
 314         err = sock_register(&phonet_proto_family);
 315         if (err) {
 316                 printk(KERN_ALERT
 317                         "phonet protocol family initialization failed\n");
 318                 return err;
 319         }
 320
 321         phonet_device_init();
 322         dev_add_pack(&phonet_packet_type);
 323         phonet_netlink_register();
 324
 325         err = isi_register();
 326         if (err)
 327                 goto err;
 328         return 0;
 329
 330 err:
 331         sock_unregister(AF_PHONET);
 332         dev_remove_pack(&phonet_packet_type);
 333         phonet_device_exit();
 334         return err;
 335 }
 336
 337 static void __exit phonet_exit(void)
 338 {
 339         isi_unregister();
 340         sock_unregister(AF_PHONET);
 341         dev_remove_pack(&phonet_packet_type);
 342         phonet_device_exit();
 343 }
 344
 345 module_init(phonet_init);
 346 module_exit(phonet_exit);
 347 MODULE_DESCRIPTION("Phonet protocol stack for Linux");
 348 MODULE_LICENSE("GPL");