| /* |
| * connector.c |
| * |
| * 2004+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net> |
| * All rights reserved. |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License as published by |
| * the Free Software Foundation; either version 2 of the License, or |
| * (at your option) any later version. |
| * |
| * This program is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU General Public License for more details. |
| * |
| * You should have received a copy of the GNU General Public License |
| * along with this program; if not, write to the Free Software |
| * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| */ |
| |
| #include <linux/kernel.h> |
| #include <linux/module.h> |
| #include <linux/list.h> |
| #include <linux/skbuff.h> |
| #include <net/netlink.h> |
| #include <linux/moduleparam.h> |
| #include <linux/connector.h> |
| #include <linux/slab.h> |
| #include <linux/mutex.h> |
| #include <linux/proc_fs.h> |
| #include <linux/spinlock.h> |
| |
| #include <net/sock.h> |
| |
| MODULE_LICENSE("GPL"); |
| MODULE_AUTHOR("Evgeniy Polyakov <zbr@ioremap.net>"); |
| MODULE_DESCRIPTION("Generic userspace <-> kernelspace connector."); |
| MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_CONNECTOR); |
| |
| static struct cn_dev cdev; |
| |
| static int cn_already_initialized; |
| |
| /* |
| * msg->seq and msg->ack are used to determine message genealogy. |
| * When someone sends message it puts there locally unique sequence |
| * and random acknowledge numbers. Sequence number may be copied into |
| * nlmsghdr->nlmsg_seq too. |
| * |
| * Sequence number is incremented with each message to be sent. |
| * |
| * If we expect reply to our message then the sequence number in |
| * received message MUST be the same as in original message, and |
| * acknowledge number MUST be the same + 1. |
| * |
| * If we receive a message and its sequence number is not equal to the |
| * one we are expecting then it is a new message. |
| * |
| * If we receive a message and its sequence number is the same as one |
| * we are expecting but it's acknowledgement number is not equal to |
| * the acknowledgement number in the original message + 1, then it is |
| * a new message. |
| * |
| */ |
| int cn_netlink_send(struct cn_msg *msg, u32 __group, gfp_t gfp_mask) |
| { |
| struct cn_callback_entry *__cbq; |
| unsigned int size; |
| struct sk_buff *skb; |
| struct nlmsghdr *nlh; |
| struct cn_msg *data; |
| struct cn_dev *dev = &cdev; |
| u32 group = 0; |
| int found = 0; |
| |
| if (!__group) { |
| spin_lock_bh(&dev->cbdev->queue_lock); |
| list_for_each_entry(__cbq, &dev->cbdev->queue_list, |
| callback_entry) { |
| if (cn_cb_equal(&__cbq->id.id, &msg->id)) { |
| found = 1; |
| group = __cbq->group; |
| break; |
| } |
| } |
| spin_unlock_bh(&dev->cbdev->queue_lock); |
| |
| if (!found) |
| return -ENODEV; |
| } else { |
| group = __group; |
| } |
| |
| if (!netlink_has_listeners(dev->nls, group)) |
| return -ESRCH; |
| |
| size = sizeof(*msg) + msg->len; |
| |
| skb = nlmsg_new(size, gfp_mask); |
| if (!skb) |
| return -ENOMEM; |
| |
| nlh = nlmsg_put(skb, 0, msg->seq, NLMSG_DONE, size, 0); |
| if (!nlh) { |
| kfree_skb(skb); |
| return -EMSGSIZE; |
| } |
| |
| data = nlmsg_data(nlh); |
| |
| memcpy(data, msg, sizeof(*data) + msg->len); |
| |
| NETLINK_CB(skb).dst_group = group; |
| |
| return netlink_broadcast(dev->nls, skb, 0, group, gfp_mask); |
| } |
| EXPORT_SYMBOL_GPL(cn_netlink_send); |
| |
| /* |
| * Callback helper - queues work and setup destructor for given data. |
| */ |
| static int cn_call_callback(struct sk_buff *skb) |
| { |
| struct cn_callback_entry *i, *cbq = NULL; |
| struct cn_dev *dev = &cdev; |
| struct cn_msg *msg = nlmsg_data(nlmsg_hdr(skb)); |
| struct netlink_skb_parms *nsp = &NETLINK_CB(skb); |
| int err = -ENODEV; |
| |
| spin_lock_bh(&dev->cbdev->queue_lock); |
| list_for_each_entry(i, &dev->cbdev->queue_list, callback_entry) { |
| if (cn_cb_equal(&i->id.id, &msg->id)) { |
| atomic_inc(&i->refcnt); |
| cbq = i; |
| break; |
| } |
| } |
| spin_unlock_bh(&dev->cbdev->queue_lock); |
| |
| if (cbq != NULL) { |
| err = 0; |
| cbq->callback(msg, nsp); |
| kfree_skb(skb); |
| cn_queue_release_callback(cbq); |
| err = 0; |
| } |
| |
| return err; |
| } |
| |
| /* |
| * Main netlink receiving function. |
| * |
| * It checks skb, netlink header and msg sizes, and calls callback helper. |
| */ |
| static void cn_rx_skb(struct sk_buff *__skb) |
| { |
| struct nlmsghdr *nlh; |
| struct sk_buff *skb; |
| int len, err; |
| |
| skb = skb_get(__skb); |
| |
| if (skb->len >= NLMSG_HDRLEN) { |
| nlh = nlmsg_hdr(skb); |
| len = nlmsg_len(nlh); |
| |
| if (len < (int)sizeof(struct cn_msg) || |
| skb->len < nlh->nlmsg_len || |
| len > CONNECTOR_MAX_MSG_SIZE) { |
| kfree_skb(skb); |
| return; |
| } |
| |
| err = cn_call_callback(skb); |
| if (err < 0) |
| kfree_skb(skb); |
| } |
| } |
| |
| /* |
| * Callback add routing - adds callback with given ID and name. |
| * If there is registered callback with the same ID it will not be added. |
| * |
| * May sleep. |
| */ |
| int cn_add_callback(struct cb_id *id, const char *name, |
| void (*callback)(struct cn_msg *, |
| struct netlink_skb_parms *)) |
| { |
| int err; |
| struct cn_dev *dev = &cdev; |
| |
| if (!cn_already_initialized) |
| return -EAGAIN; |
| |
| err = cn_queue_add_callback(dev->cbdev, name, id, callback); |
| if (err) |
| return err; |
| |
| return 0; |
| } |
| EXPORT_SYMBOL_GPL(cn_add_callback); |
| |
| /* |
| * Callback remove routing - removes callback |
| * with given ID. |
| * If there is no registered callback with given |
| * ID nothing happens. |
| * |
| * May sleep while waiting for reference counter to become zero. |
| */ |
| void cn_del_callback(struct cb_id *id) |
| { |
| struct cn_dev *dev = &cdev; |
| |
| cn_queue_del_callback(dev->cbdev, id); |
| } |
| EXPORT_SYMBOL_GPL(cn_del_callback); |
| |
| static int cn_proc_show(struct seq_file *m, void *v) |
| { |
| struct cn_queue_dev *dev = cdev.cbdev; |
| struct cn_callback_entry *cbq; |
| |
| seq_printf(m, "Name ID\n"); |
| |
| spin_lock_bh(&dev->queue_lock); |
| |
| list_for_each_entry(cbq, &dev->queue_list, callback_entry) { |
| seq_printf(m, "%-15s %u:%u\n", |
| cbq->id.name, |
| cbq->id.id.idx, |
| cbq->id.id.val); |
| } |
| |
| spin_unlock_bh(&dev->queue_lock); |
| |
| return 0; |
| } |
| |
| static int cn_proc_open(struct inode *inode, struct file *file) |
| { |
| return single_open(file, cn_proc_show, NULL); |
| } |
| |
| static const struct file_operations cn_file_ops = { |
| .owner = THIS_MODULE, |
| .open = cn_proc_open, |
| .read = seq_read, |
| .llseek = seq_lseek, |
| .release = single_release |
| }; |
| |
| static struct cn_dev cdev = { |
| .input = cn_rx_skb, |
| }; |
| |
| static int cn_init(void) |
| { |
| struct cn_dev *dev = &cdev; |
| struct netlink_kernel_cfg cfg = { |
| .groups = CN_NETLINK_USERS + 0xf, |
| .input = dev->input, |
| }; |
| |
| dev->nls = netlink_kernel_create(&init_net, NETLINK_CONNECTOR, &cfg); |
| if (!dev->nls) |
| return -EIO; |
| |
| dev->cbdev = cn_queue_alloc_dev("cqueue", dev->nls); |
| if (!dev->cbdev) { |
| netlink_kernel_release(dev->nls); |
| return -EINVAL; |
| } |
| |
| cn_already_initialized = 1; |
| |
| proc_create("connector", S_IRUGO, init_net.proc_net, &cn_file_ops); |
| |
| return 0; |
| } |
| |
| static void cn_fini(void) |
| { |
| struct cn_dev *dev = &cdev; |
| |
| cn_already_initialized = 0; |
| |
| remove_proc_entry("connector", init_net.proc_net); |
| |
| cn_queue_free_dev(dev->cbdev); |
| netlink_kernel_release(dev->nls); |
| } |
| |
| subsys_initcall(cn_init); |
| module_exit(cn_fini); |