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284 lines
6.7 KiB
284 lines
6.7 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* connector.c |
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* |
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* 2004+ Copyright (c) Evgeniy Polyakov <[email protected]> |
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* All rights reserved. |
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*/ |
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#include <linux/compiler.h> |
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#include <linux/kernel.h> |
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#include <linux/module.h> |
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#include <linux/list.h> |
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#include <linux/skbuff.h> |
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#include <net/netlink.h> |
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#include <linux/moduleparam.h> |
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#include <linux/connector.h> |
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#include <linux/slab.h> |
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#include <linux/mutex.h> |
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#include <linux/proc_fs.h> |
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#include <linux/spinlock.h> |
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#include <net/sock.h> |
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MODULE_LICENSE("GPL"); |
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MODULE_AUTHOR("Evgeniy Polyakov <[email protected]>"); |
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MODULE_DESCRIPTION("Generic userspace <-> kernelspace connector."); |
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MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_CONNECTOR); |
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static struct cn_dev cdev; |
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static int cn_already_initialized; |
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/* |
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* Sends mult (multiple) cn_msg at a time. |
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* |
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* msg->seq and msg->ack are used to determine message genealogy. |
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* When someone sends message it puts there locally unique sequence |
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* and random acknowledge numbers. Sequence number may be copied into |
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* nlmsghdr->nlmsg_seq too. |
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* |
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* Sequence number is incremented with each message to be sent. |
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* |
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* If we expect a reply to our message then the sequence number in |
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* received message MUST be the same as in original message, and |
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* acknowledge number MUST be the same + 1. |
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* |
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* If we receive a message and its sequence number is not equal to the |
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* one we are expecting then it is a new message. |
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* |
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* If we receive a message and its sequence number is the same as one |
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* we are expecting but it's acknowledgement number is not equal to |
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* the acknowledgement number in the original message + 1, then it is |
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* a new message. |
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* |
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* If msg->len != len, then additional cn_msg messages are expected following |
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* the first msg. |
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* |
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* The message is sent to, the portid if given, the group if given, both if |
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* both, or if both are zero then the group is looked up and sent there. |
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*/ |
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int cn_netlink_send_mult(struct cn_msg *msg, u16 len, u32 portid, u32 __group, |
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gfp_t gfp_mask) |
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{ |
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struct cn_callback_entry *__cbq; |
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unsigned int size; |
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struct sk_buff *skb; |
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struct nlmsghdr *nlh; |
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struct cn_msg *data; |
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struct cn_dev *dev = &cdev; |
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u32 group = 0; |
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int found = 0; |
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if (portid || __group) { |
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group = __group; |
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} else { |
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spin_lock_bh(&dev->cbdev->queue_lock); |
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list_for_each_entry(__cbq, &dev->cbdev->queue_list, |
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callback_entry) { |
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if (cn_cb_equal(&__cbq->id.id, &msg->id)) { |
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found = 1; |
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group = __cbq->group; |
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break; |
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} |
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} |
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spin_unlock_bh(&dev->cbdev->queue_lock); |
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if (!found) |
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return -ENODEV; |
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} |
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if (!portid && !netlink_has_listeners(dev->nls, group)) |
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return -ESRCH; |
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size = sizeof(*msg) + len; |
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skb = nlmsg_new(size, gfp_mask); |
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if (!skb) |
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return -ENOMEM; |
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nlh = nlmsg_put(skb, 0, msg->seq, NLMSG_DONE, size, 0); |
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if (!nlh) { |
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kfree_skb(skb); |
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return -EMSGSIZE; |
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} |
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data = nlmsg_data(nlh); |
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memcpy(data, msg, size); |
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NETLINK_CB(skb).dst_group = group; |
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if (group) |
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return netlink_broadcast(dev->nls, skb, portid, group, |
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gfp_mask); |
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return netlink_unicast(dev->nls, skb, portid, |
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!gfpflags_allow_blocking(gfp_mask)); |
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} |
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EXPORT_SYMBOL_GPL(cn_netlink_send_mult); |
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/* same as cn_netlink_send_mult except msg->len is used for len */ |
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int cn_netlink_send(struct cn_msg *msg, u32 portid, u32 __group, |
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gfp_t gfp_mask) |
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{ |
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return cn_netlink_send_mult(msg, msg->len, portid, __group, gfp_mask); |
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} |
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EXPORT_SYMBOL_GPL(cn_netlink_send); |
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/* |
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* Callback helper - queues work and setup destructor for given data. |
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*/ |
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static int cn_call_callback(struct sk_buff *skb) |
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{ |
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struct nlmsghdr *nlh; |
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struct cn_callback_entry *i, *cbq = NULL; |
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struct cn_dev *dev = &cdev; |
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struct cn_msg *msg = nlmsg_data(nlmsg_hdr(skb)); |
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struct netlink_skb_parms *nsp = &NETLINK_CB(skb); |
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int err = -ENODEV; |
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/* verify msg->len is within skb */ |
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nlh = nlmsg_hdr(skb); |
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if (nlh->nlmsg_len < NLMSG_HDRLEN + sizeof(struct cn_msg) + msg->len) |
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return -EINVAL; |
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spin_lock_bh(&dev->cbdev->queue_lock); |
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list_for_each_entry(i, &dev->cbdev->queue_list, callback_entry) { |
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if (cn_cb_equal(&i->id.id, &msg->id)) { |
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refcount_inc(&i->refcnt); |
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cbq = i; |
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break; |
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} |
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} |
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spin_unlock_bh(&dev->cbdev->queue_lock); |
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if (cbq != NULL) { |
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cbq->callback(msg, nsp); |
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kfree_skb(skb); |
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cn_queue_release_callback(cbq); |
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err = 0; |
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} |
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return err; |
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} |
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/* |
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* Main netlink receiving function. |
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* |
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* It checks skb, netlink header and msg sizes, and calls callback helper. |
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*/ |
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static void cn_rx_skb(struct sk_buff *skb) |
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{ |
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struct nlmsghdr *nlh; |
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int len, err; |
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if (skb->len >= NLMSG_HDRLEN) { |
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nlh = nlmsg_hdr(skb); |
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len = nlmsg_len(nlh); |
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if (len < (int)sizeof(struct cn_msg) || |
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skb->len < nlh->nlmsg_len || |
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len > CONNECTOR_MAX_MSG_SIZE) |
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return; |
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err = cn_call_callback(skb_get(skb)); |
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if (err < 0) |
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kfree_skb(skb); |
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} |
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} |
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/* |
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* Callback add routing - adds callback with given ID and name. |
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* If there is registered callback with the same ID it will not be added. |
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* |
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* May sleep. |
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*/ |
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int cn_add_callback(const struct cb_id *id, const char *name, |
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void (*callback)(struct cn_msg *, |
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struct netlink_skb_parms *)) |
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{ |
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struct cn_dev *dev = &cdev; |
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if (!cn_already_initialized) |
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return -EAGAIN; |
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return cn_queue_add_callback(dev->cbdev, name, id, callback); |
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} |
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EXPORT_SYMBOL_GPL(cn_add_callback); |
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/* |
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* Callback remove routing - removes callback |
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* with given ID. |
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* If there is no registered callback with given |
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* ID nothing happens. |
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* |
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* May sleep while waiting for reference counter to become zero. |
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*/ |
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void cn_del_callback(const struct cb_id *id) |
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{ |
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struct cn_dev *dev = &cdev; |
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cn_queue_del_callback(dev->cbdev, id); |
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} |
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EXPORT_SYMBOL_GPL(cn_del_callback); |
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static int __maybe_unused cn_proc_show(struct seq_file *m, void *v) |
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{ |
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struct cn_queue_dev *dev = cdev.cbdev; |
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struct cn_callback_entry *cbq; |
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seq_printf(m, "Name ID\n"); |
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spin_lock_bh(&dev->queue_lock); |
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list_for_each_entry(cbq, &dev->queue_list, callback_entry) { |
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seq_printf(m, "%-15s %u:%u\n", |
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cbq->id.name, |
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cbq->id.id.idx, |
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cbq->id.id.val); |
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} |
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spin_unlock_bh(&dev->queue_lock); |
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return 0; |
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} |
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static int cn_init(void) |
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{ |
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struct cn_dev *dev = &cdev; |
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struct netlink_kernel_cfg cfg = { |
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.groups = CN_NETLINK_USERS + 0xf, |
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.input = cn_rx_skb, |
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}; |
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dev->nls = netlink_kernel_create(&init_net, NETLINK_CONNECTOR, &cfg); |
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if (!dev->nls) |
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return -EIO; |
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dev->cbdev = cn_queue_alloc_dev("cqueue", dev->nls); |
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if (!dev->cbdev) { |
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netlink_kernel_release(dev->nls); |
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return -EINVAL; |
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} |
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cn_already_initialized = 1; |
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proc_create_single("connector", S_IRUGO, init_net.proc_net, cn_proc_show); |
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return 0; |
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} |
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static void cn_fini(void) |
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{ |
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struct cn_dev *dev = &cdev; |
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cn_already_initialized = 0; |
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remove_proc_entry("connector", init_net.proc_net); |
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cn_queue_free_dev(dev->cbdev); |
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netlink_kernel_release(dev->nls); |
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} |
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subsys_initcall(cn_init); |
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module_exit(cn_fini);
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