drivers/staging/gdm724x/netlink_k.c

   1 /*
   2  * Copyright (c) 2012 GCT Semiconductor, Inc. All rights reserved.
   3  *
   4  * This software is licensed under the terms of the GNU General Public
   5  * License version 2, as published by the Free Software Foundation, and
   6  * may be copied, distributed, and modified under those terms.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  11  * GNU General Public License for more details.
  12  */
  13
  14 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  15
  16 #include <linux/export.h>
  17 #include <linux/etherdevice.h>
  18 #include <linux/netlink.h>
  19 #include <asm/byteorder.h>
  20 #include <net/sock.h>
  21
  22 #include "netlink_k.h"
  23
  24 #if defined(DEFINE_MUTEX)
  25 static DEFINE_MUTEX(netlink_mutex);
  26 #else
  27 static struct semaphore netlink_mutex;
  28 #define mutex_lock(x)           down(x)
  29 #define mutex_unlock(x)         up(x)
  30 #endif
  31
  32 #define ND_MAX_GROUP            30
  33 #define ND_IFINDEX_LEN          sizeof(int)
  34 #define ND_NLMSG_SPACE(len)     (NLMSG_SPACE(len) + ND_IFINDEX_LEN)
  35 #define ND_NLMSG_DATA(nlh)      ((void *)((char *)NLMSG_DATA(nlh) + \
  36                                                   ND_IFINDEX_LEN))
  37 #define ND_NLMSG_S_LEN(len)     (len+ND_IFINDEX_LEN)
  38 #define ND_NLMSG_R_LEN(nlh)     (nlh->nlmsg_len-ND_IFINDEX_LEN)
  39 #define ND_NLMSG_IFIDX(nlh)     NLMSG_DATA(nlh)
  40 #define ND_MAX_MSG_LEN          (1024 * 32)
  41
  42 static void (*rcv_cb)(struct net_device *dev, u16 type, void *msg, int len);
  43
  44 static void netlink_rcv_cb(struct sk_buff *skb)
  45 {
  46         struct nlmsghdr *nlh;
  47         struct net_device *dev;
  48         u32 mlen;
  49         void *msg;
  50         int ifindex;
  51
  52         if (!rcv_cb) {
  53                 pr_err("nl cb - unregistered\n");
  54                 return;
  55         }
  56
  57         if (skb->len < NLMSG_HDRLEN) {
  58                 pr_err("nl cb - invalid skb length\n");
  59                 return;
  60         }
  61
  62         nlh = (struct nlmsghdr *)skb->data;
  63
  64         if (skb->len < nlh->nlmsg_len || nlh->nlmsg_len > ND_MAX_MSG_LEN) {
  65                 pr_err("nl cb - invalid length (%d,%d)\n",
  66                        skb->len, nlh->nlmsg_len);
  67                 return;
  68         }
  69
  70         memcpy(&ifindex, ND_NLMSG_IFIDX(nlh), ND_IFINDEX_LEN);
  71         msg = ND_NLMSG_DATA(nlh);
  72         mlen = ND_NLMSG_R_LEN(nlh);
  73
  74         dev = dev_get_by_index(&init_net, ifindex);
  75         if (dev) {
  76                 rcv_cb(dev, nlh->nlmsg_type, msg, mlen);
  77                 dev_put(dev);
  78         } else {
  79                 pr_err("nl cb - dev (%d) not found\n", ifindex);
  80         }
  81 }
  82
  83 static void netlink_rcv(struct sk_buff *skb)
  84 {
  85         mutex_lock(&netlink_mutex);
  86         netlink_rcv_cb(skb);
  87         mutex_unlock(&netlink_mutex);
  88 }
  89
  90 struct sock *netlink_init(int unit,
  91         void (*cb)(struct net_device *dev, u16 type, void *msg, int len))
  92 {
  93         struct sock *sock;
  94         struct netlink_kernel_cfg cfg = {
  95                 .input  = netlink_rcv,
  96         };
  97
  98 #if !defined(DEFINE_MUTEX)
  99         init_MUTEX(&netlink_mutex);
 100 #endif
 101
 102         sock = netlink_kernel_create(&init_net, unit, &cfg);
 103
 104         if (sock)
 105                 rcv_cb = cb;
 106
 107         return sock;
 108 }
 109
 110 void netlink_exit(struct sock *sock)
 111 {
 112         sock_release(sock->sk_socket);
 113 }
 114
 115 int netlink_send(struct sock *sock, int group, u16 type, void *msg, int len)
 116 {
 117         static u32 seq;
 118         struct sk_buff *skb = NULL;
 119         struct nlmsghdr *nlh;
 120         int ret = 0;
 121
 122         if (group > ND_MAX_GROUP)
 123                 return -EINVAL;
 124
 125         if (!netlink_has_listeners(sock, group+1))
 126                 return -ESRCH;
 127
 128         skb = alloc_skb(NLMSG_SPACE(len), GFP_ATOMIC);
 129         if (!skb)
 130                 return -ENOMEM;
 131
 132         seq++;
 133
 134         nlh = nlmsg_put(skb, 0, seq, type, len, 0);
 135         memcpy(NLMSG_DATA(nlh), msg, len);
 136         NETLINK_CB(skb).portid = 0;
 137         NETLINK_CB(skb).dst_group = 0;
 138
 139         ret = netlink_broadcast(sock, skb, 0, group+1, GFP_ATOMIC);
 140         if (!ret)
 141                 return len;
 142
 143         if (ret != -ESRCH)
 144                 pr_err("nl broadcast g=%d, t=%d, l=%d, r=%d\n",
 145                        group, type, len, ret);
 146         else if (netlink_has_listeners(sock, group+1))
 147                 return -EAGAIN;
 148
 149         return ret;
 150 }