net/netlink/netlink_dev.c

   1 /*
   2  * NETLINK      An implementation of a loadable kernel mode driver providing
   3  *              multiple kernel/user space bidirectional communications links.
   4  *
   5  *              Author:         Alan Cox <alan@cymru.net>
   6  *
   7  *              This program is free software; you can redistribute it and/or
   8  *              modify it under the terms of the GNU General Public License
   9  *              as published by the Free Software Foundation; either version
  10  *              2 of the License, or (at your option) any later version.
  11  *
  12  *      Now netlink devices are emulated on the top of netlink sockets
  13  *      by compatibility reasons. Remove this file after a period. --ANK
  14  *
  15  */
  16
  17 #include <linux/module.h>
  18
  19 #include <linux/errno.h>
  20 #include <linux/kernel.h>
  21 #include <linux/major.h>
  22 #include <linux/sched.h>
  23 #include <linux/malloc.h>
  24 #include <linux/skbuff.h>
  25 #include <linux/netlink.h>
  26 #include <linux/poll.h>
  27 #include <linux/init.h>
  28
  29 #include <asm/system.h>
  30 #include <asm/uaccess.h>
  31
  32 static unsigned open_map = 0;
  33 static struct socket *netlink_user[MAX_LINKS];
  34
  35 /*
  36  *      Device operations
  37  */
  38
  39 static unsigned int netlink_poll(struct file *file, poll_table * wait)
  40 {
  41         struct socket *sock = netlink_user[MINOR(file->f_dentry->d_inode->i_rdev)];
  42
  43         if (sock->ops->poll==NULL)
  44                 return 0;
  45         return sock->ops->poll(file, sock, wait);
  46 }
  47
  48 /*
  49  *      Write a message to the kernel side of a communication link
  50  */
  51
  52 static ssize_t netlink_write(struct file * file, const char * buf,
  53                              size_t count, loff_t *pos)
  54 {
  55         struct inode *inode = file->f_dentry->d_inode;
  56         struct socket *sock = netlink_user[MINOR(inode->i_rdev)];
  57         struct msghdr msg;
  58         struct iovec iov;
  59
  60         iov.iov_base = (void*)buf;
  61         iov.iov_len = count;
  62         msg.msg_name=NULL;
  63         msg.msg_namelen=0;
  64         msg.msg_controllen=0;
  65         msg.msg_flags=0;
  66         msg.msg_iov=&iov;
  67         msg.msg_iovlen=1;
  68
  69         return sock_sendmsg(sock, &msg, count);
  70 }
  71
  72 /*
  73  *      Read a message from the kernel side of the communication link
  74  */
  75
  76 static ssize_t netlink_read(struct file * file, char * buf,
  77                             size_t count, loff_t *pos)
  78 {
  79         struct inode *inode = file->f_dentry->d_inode;
  80         struct socket *sock = netlink_user[MINOR(inode->i_rdev)];
  81         struct msghdr msg;
  82         struct iovec iov;
  83
  84         iov.iov_base = buf;
  85         iov.iov_len = count;
  86         msg.msg_name=NULL;
  87         msg.msg_namelen=0;
  88         msg.msg_controllen=0;
  89         msg.msg_flags=0;
  90         msg.msg_iov=&iov;
  91         msg.msg_iovlen=1;
  92         if (file->f_flags&O_NONBLOCK)
  93                 msg.msg_flags=MSG_DONTWAIT;
  94
  95         return sock_recvmsg(sock, &msg, count, msg.msg_flags);
  96 }
  97
  98 static loff_t netlink_lseek(struct file * file, loff_t offset, int origin)
  99 {
 100         return -ESPIPE;
 101 }
 102
 103 static int netlink_open(struct inode * inode, struct file * file)
 104 {
 105         unsigned int minor = MINOR(inode->i_rdev);
 106         struct socket *sock;
 107         struct sockaddr_nl nladdr;
 108         int err;
 109
 110         if (minor>=MAX_LINKS)
 111                 return -ENODEV;
 112         if (open_map&(1<<minor))
 113                 return -EBUSY;
 114
 115         open_map |= (1<<minor);
 116         MOD_INC_USE_COUNT;
 117
 118         err = -EINVAL;
 119         if (net_families[PF_NETLINK]==NULL)
 120                 goto out;
 121
 122         err = -ENFILE;
 123         if (!(sock = sock_alloc()))
 124                 goto out;
 125
 126         sock->type = SOCK_RAW;
 127
 128         if ((err = net_families[PF_NETLINK]->create(sock, minor)) < 0)
 129         {
 130                 sock_release(sock);
 131                 goto out;
 132         }
 133
 134         memset(&nladdr, 0, sizeof(nladdr));
 135         nladdr.nl_family = AF_NETLINK;
 136         nladdr.nl_groups = ~0;
 137         if ((err = sock->ops->bind(sock, (struct sockaddr*)&nladdr, sizeof(nladdr))) < 0) {
 138                 sock_release(sock);
 139                 goto out;
 140         }
 141
 142         netlink_user[minor] = sock;
 143         return 0;
 144
 145 out:
 146         open_map &= ~(1<<minor);
 147         return err;
 148 }
 149
 150 static int netlink_release(struct inode * inode, struct file * file)
 151 {
 152         unsigned int minor = MINOR(inode->i_rdev);
 153         struct socket *sock = netlink_user[minor];
 154
 155         netlink_user[minor] = NULL;
 156         open_map &= ~(1<<minor);
 157         sock_release(sock);
 158         MOD_DEC_USE_COUNT;
 159         return 0;
 160 }
 161
 162
 163 static int netlink_ioctl(struct inode *inode, struct file *file,
 164                     unsigned int cmd, unsigned long arg)
 165 {
 166         unsigned int minor = MINOR(inode->i_rdev);
 167         int retval = 0;
 168
 169         if (minor >= MAX_LINKS)
 170                 return -ENODEV;
 171         switch ( cmd ) {
 172                 default:
 173                         retval = -EINVAL;
 174         }
 175         return retval;
 176 }
 177
 178
 179 static struct file_operations netlink_fops = {
 180         netlink_lseek,
 181         netlink_read,
 182         netlink_write,
 183         NULL,           /* netlink_readdir */
 184         netlink_poll,
 185         netlink_ioctl,
 186         NULL,           /* netlink_mmap */
 187         netlink_open,
 188         NULL,           /* flush */
 189         netlink_release
 190 };
 191
 192 __initfunc(int init_netlink(void))
 193 {
 194         if (register_chrdev(NETLINK_MAJOR,"netlink", &netlink_fops)) {
 195                 printk(KERN_ERR "netlink: unable to get major %d\n", NETLINK_MAJOR);
 196                 return -EIO;
 197         }
 198         return 0;
 199 }
 200
 201 #ifdef MODULE
 202
 203 int init_module(void)
 204 {
 205         printk(KERN_INFO "Network Kernel/User communications module 0.04\n");
 206         return init_netlink();
 207 }
 208
 209 void cleanup_module(void)
 210 {
 211         unregister_chrdev(NET_MAJOR,"netlink");
 212 }
 213
 214 #endif