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@redhat.com>
   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/slab.h>
  24 #include <linux/skbuff.h>
  25 #include <linux/netlink.h>
  26 #include <linux/poll.h>
  27 #include <linux/init.h>
  28 #include <linux/devfs_fs_kernel.h>
  29 #include <linux/smp_lock.h>
  30
  31 #include <asm/bitops.h>
  32 #include <asm/system.h>
  33 #include <asm/uaccess.h>
  34
  35 static long open_map;
  36 static struct socket *netlink_user[MAX_LINKS];
  37
  38 /*
  39  *      Device operations
  40  */
  41
  42 static unsigned int netlink_poll(struct file *file, poll_table * wait)
  43 {
  44         struct socket *sock = netlink_user[minor(file->f_dentry->d_inode->i_rdev)];
  45
  46         if (sock->ops->poll==NULL)
  47                 return 0;
  48         return sock->ops->poll(file, sock, wait);
  49 }
  50
  51 /*
  52  *      Write a message to the kernel side of a communication link
  53  */
  54
  55 static ssize_t netlink_write(struct file * file, const char * buf,
  56                              size_t count, loff_t *pos)
  57 {
  58         struct inode *inode = file->f_dentry->d_inode;
  59         struct socket *sock = netlink_user[minor(inode->i_rdev)];
  60         struct msghdr msg;
  61         struct iovec iov;
  62
  63         iov.iov_base = (void*)buf;
  64         iov.iov_len = count;
  65         msg.msg_name=NULL;
  66         msg.msg_namelen=0;
  67         msg.msg_controllen=0;
  68         msg.msg_flags=0;
  69         msg.msg_iov=&iov;
  70         msg.msg_iovlen=1;
  71
  72         return sock_sendmsg(sock, &msg, count);
  73 }
  74
  75 /*
  76  *      Read a message from the kernel side of the communication link
  77  */
  78
  79 static ssize_t netlink_read(struct file * file, char * buf,
  80                             size_t count, loff_t *pos)
  81 {
  82         struct inode *inode = file->f_dentry->d_inode;
  83         struct socket *sock = netlink_user[minor(inode->i_rdev)];
  84         struct msghdr msg;
  85         struct iovec iov;
  86
  87         iov.iov_base = buf;
  88         iov.iov_len = count;
  89         msg.msg_name=NULL;
  90         msg.msg_namelen=0;
  91         msg.msg_controllen=0;
  92         msg.msg_flags=0;
  93         msg.msg_iov=&iov;
  94         msg.msg_iovlen=1;
  95         if (file->f_flags&O_NONBLOCK)
  96                 msg.msg_flags=MSG_DONTWAIT;
  97
  98         return sock_recvmsg(sock, &msg, count, msg.msg_flags);
  99 }
 100
 101 static int netlink_open(struct inode * inode, struct file * file)
 102 {
 103         unsigned int minor = minor(inode->i_rdev);
 104         struct socket *sock;
 105         struct sockaddr_nl nladdr;
 106         int err;
 107
 108         if (minor>=MAX_LINKS)
 109                 return -ENODEV;
 110         if (test_and_set_bit(minor, &open_map))
 111                 return -EBUSY;
 112
 113         err = sock_create(PF_NETLINK, SOCK_RAW, minor, &sock);
 114         if (err < 0)
 115                 goto out;
 116
 117         memset(&nladdr, 0, sizeof(nladdr));
 118         nladdr.nl_family = AF_NETLINK;
 119         nladdr.nl_groups = ~0;
 120         if ((err = sock->ops->bind(sock, (struct sockaddr*)&nladdr, sizeof(nladdr))) < 0) {
 121                 sock_release(sock);
 122                 goto out;
 123         }
 124
 125         netlink_user[minor] = sock;
 126         return 0;
 127
 128 out:
 129         clear_bit(minor, &open_map);
 130         return err;
 131 }
 132
 133 static int netlink_release(struct inode * inode, struct file * file)
 134 {
 135         unsigned int minor = minor(inode->i_rdev);
 136         struct socket *sock;
 137
 138         sock = netlink_user[minor];
 139         netlink_user[minor] = NULL;
 140         clear_bit(minor, &open_map);
 141         sock_release(sock);
 142         return 0;
 143 }
 144
 145
 146 static int netlink_ioctl(struct inode *inode, struct file *file,
 147                     unsigned int cmd, unsigned long arg)
 148 {
 149         unsigned int minor = minor(inode->i_rdev);
 150         int retval = 0;
 151
 152         if (minor >= MAX_LINKS)
 153                 return -ENODEV;
 154         switch ( cmd ) {
 155                 default:
 156                         retval = -EINVAL;
 157         }
 158         return retval;
 159 }
 160
 161
 162 static struct file_operations netlink_fops = {
 163         .owner =        THIS_MODULE,
 164         .llseek =       no_llseek,
 165         .read =         netlink_read,
 166         .write =        netlink_write,
 167         .poll =         netlink_poll,
 168         .ioctl =        netlink_ioctl,
 169         .open =         netlink_open,
 170         .release =      netlink_release,
 171 };
 172
 173 static struct {
 174         char *name;
 175         int minor;
 176 } entries[] = {
 177         {
 178                 .name   = "route",
 179                 .minor  = NETLINK_ROUTE,
 180         },
 181         {
 182                 .name   = "skip",
 183                 .minor  = NETLINK_SKIP,
 184         },
 185         {
 186                 .name   = "usersock",
 187                 .minor  = NETLINK_USERSOCK,
 188         },
 189         {
 190                 .name   = "fwmonitor",
 191                 .minor  = NETLINK_FIREWALL,
 192         },
 193         {
 194                 .name   = "tcpdiag",
 195                 .minor  = NETLINK_TCPDIAG,
 196         },
 197         {
 198                 .name   = "nflog",
 199                 .minor  = NETLINK_NFLOG,
 200         },
 201         {
 202                 .name   = "xfrm",
 203                 .minor  = NETLINK_XFRM,
 204         },
 205         {
 206                 .name   = "arpd",
 207                 .minor  = NETLINK_ARPD,
 208         },
 209         {
 210                 .name   = "route6",
 211                 .minor  = NETLINK_ROUTE6,
 212         },
 213         {
 214                 .name   = "ip6_fw",
 215                 .minor  = NETLINK_IP6_FW,
 216         },
 217         {
 218                 .name   = "dnrtmsg",
 219                 .minor  = NETLINK_DNRTMSG,
 220         },
 221 };
 222
 223 static int __init init_netlink(void)
 224 {
 225         int i;
 226
 227         if (register_chrdev(NETLINK_MAJOR,"netlink", &netlink_fops)) {
 228                 printk(KERN_ERR "netlink: unable to get major %d\n", NETLINK_MAJOR);
 229                 return -EIO;
 230         }
 231
 232         devfs_mk_dir("netlink");
 233
 234         /*  Someone tell me the official names for the uppercase ones  */
 235         for (i = 0; i < ARRAY_SIZE(entries); i++) {
 236                 devfs_mk_cdev(MKDEV(NETLINK_MAJOR, entries[i].minor),
 237                         S_IFCHR|S_IRUSR|S_IWUSR, "netlink/%s", entries[i].name);
 238         }
 239
 240         for (i = 0; i < 16; i++) {
 241                 devfs_mk_cdev(MKDEV(NETLINK_MAJOR, i + 16),
 242                         S_IFCHR|S_IRUSR|S_IWUSR, "netlink/tap%d", i);
 243         }
 244
 245         return 0;
 246 }
 247
 248 static void __exit cleanup_netlink(void)
 249 {
 250         int i;
 251
 252         for (i = 0; i < ARRAY_SIZE(entries); i++)
 253                 devfs_remove("netlink/%s", entries[i].name);
 254         for (i = 0; i < 16; i++)
 255                 devfs_remove("netlink/tap%d", i);
 256         devfs_remove("netlink");
 257         unregister_chrdev(NETLINK_MAJOR, "netlink");
 258 }
 259
 260 MODULE_LICENSE("GPL");
 261 module_init(init_netlink);
 262 module_exit(cleanup_netlink);