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- // SPDX-License-Identifier: GPL-2.0-or-later
- /*
- * connector.c
- *
- * 2004+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
- * All rights reserved.
- */
- #include <linux/compiler.h>
- #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;
- /*
- * Sends mult (multiple) cn_msg at a time.
- *
- * 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 a 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.
- *
- * If msg->len != len, then additional cn_msg messages are expected following
- * the first msg.
- *
- * The message is sent to, the portid if given, the group if given, both if
- * both, or if both are zero then the group is looked up and sent there.
- */
- int cn_netlink_send_mult(struct cn_msg *msg, u16 len, u32 portid, 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 (portid || __group) {
- group = __group;
- } else {
- 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;
- }
- if (!portid && !netlink_has_listeners(dev->nls, group))
- return -ESRCH;
- size = sizeof(*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, size);
- NETLINK_CB(skb).dst_group = group;
- if (group)
- return netlink_broadcast(dev->nls, skb, portid, group,
- gfp_mask);
- return netlink_unicast(dev->nls, skb, portid,
- !gfpflags_allow_blocking(gfp_mask));
- }
- EXPORT_SYMBOL_GPL(cn_netlink_send_mult);
- /* same as cn_netlink_send_mult except msg->len is used for len */
- int cn_netlink_send(struct cn_msg *msg, u32 portid, u32 __group,
- gfp_t gfp_mask)
- {
- return cn_netlink_send_mult(msg, msg->len, portid, __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 nlmsghdr *nlh;
- 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;
- /* verify msg->len is within skb */
- nlh = nlmsg_hdr(skb);
- if (nlh->nlmsg_len < NLMSG_HDRLEN + sizeof(struct cn_msg) + msg->len)
- return -EINVAL;
- 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)) {
- refcount_inc(&i->refcnt);
- cbq = i;
- break;
- }
- }
- spin_unlock_bh(&dev->cbdev->queue_lock);
- if (cbq != NULL) {
- 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;
- int len, err;
- 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)
- return;
- err = cn_call_callback(skb_get(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 __maybe_unused 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_init(void)
- {
- struct cn_dev *dev = &cdev;
- struct netlink_kernel_cfg cfg = {
- .groups = CN_NETLINK_USERS + 0xf,
- .input = cn_rx_skb,
- };
- 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_single("connector", S_IRUGO, init_net.proc_net, cn_proc_show);
- 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);
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