From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001 From: André Fabian Silva Delgado Date: Wed, 5 Aug 2015 17:04:01 -0300 Subject: Initial import --- drivers/connector/connector.c | 322 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 322 insertions(+) create mode 100644 drivers/connector/connector.c (limited to 'drivers/connector/connector.c') diff --git a/drivers/connector/connector.c b/drivers/connector/connector.c new file mode 100644 index 000000000..30f522848 --- /dev/null +++ b/drivers/connector/connector.c @@ -0,0 +1,322 @@ +/* + * connector.c + * + * 2004+ Copyright (c) Evgeniy Polyakov + * 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 +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Evgeniy Polyakov "); +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, !(gfp_mask&__GFP_WAIT)); +} +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)) { + atomic_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; + 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); -- cgit v1.2.3-54-g00ecf