/* * connector.c * * 2004-2005 Copyright (c) Evgeniy Polyakov <johnpol@2ka.mipt.ru> * 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 <linux/netlink.h> #include <linux/moduleparam.h> #include <linux/connector.h> #include <linux/mutex.h> #include <net/sock.h> MODULE_LICENSE("GPL"); MODULE_AUTHOR("Evgeniy Polyakov <johnpol@2ka.mipt.ru>"); MODULE_DESCRIPTION("Generic userspace <-> kernelspace connector."); static u32 cn_idx = CN_IDX_CONNECTOR; static u32 cn_val = CN_VAL_CONNECTOR; module_param(cn_idx, uint, 0); module_param(cn_val, uint, 0); MODULE_PARM_DESC(cn_idx, "Connector's main device idx."); MODULE_PARM_DESC(cn_val, "Connector's main device val."); static DEFINE_MUTEX(notify_lock); static LIST_HEAD(notify_list); static struct cn_dev cdev; int cn_already_initialized = 0; /* * 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; } } spin_unlock_bh(&dev->cbdev->queue_lock); if (!found) return -ENODEV; } else { group = __group; } if (!netlink_has_listeners(dev->nls, group)) return -ESRCH; size = NLMSG_SPACE(sizeof(*msg) + msg->len); skb = alloc_skb(size, gfp_mask); if (!skb) return -ENOMEM; nlh = NLMSG_PUT(skb, 0, msg->seq, NLMSG_DONE, size - sizeof(*nlh)); 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); nlmsg_failure: kfree_skb(skb); return -EINVAL; } EXPORT_SYMBOL_GPL(cn_netlink_send); /* * Callback helper - queues work and setup destructor for given data. */ static int cn_call_callback(struct cn_msg *msg, void (*destruct_data)(void *), void *data) { struct cn_callback_entry *__cbq, *__new_cbq; struct cn_dev *dev = &cdev; int err = -ENODEV; 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)) { if (likely(!work_pending(&__cbq->work) && __cbq->data.ddata == NULL)) { __cbq->data.callback_priv = msg; __cbq->data.ddata = data; __cbq->data.destruct_data = destruct_data; if (queue_work(dev->cbdev->cn_queue, &__cbq->work)) err = 0; } else { struct cn_callback_data *d; err = -ENOMEM; __new_cbq = kzalloc(sizeof(struct cn_callback_entry), GFP_ATOMIC); if (__new_cbq) { d = &__new_cbq->data; d->callback_priv = msg; d->callback = __cbq->data.callback; d->ddata = data; d->destruct_data = destruct_data; d->free = __new_cbq; INIT_WORK(&__new_cbq->work, &cn_queue_wrapper); if (queue_work(dev->cbdev->cn_queue, &__new_cbq->work)) err = 0; else { kfree(__new_cbq); err = -EINVAL; } } } break; } } spin_unlock_bh(&dev->cbdev->queue_lock); return err; } /* * Skb receive helper - checks skb and msg size and calls callback * helper. */ static int __cn_rx_skb(struct sk_buff *skb, struct nlmsghdr *nlh) { u32 pid, uid, seq, group; struct cn_msg *msg; pid = NETLINK_CREDS(skb)->pid; uid = NETLINK_CREDS(skb)->uid; seq = nlh->nlmsg_seq; group = NETLINK_CB((skb)).dst_group; msg = NLMSG_DATA(nlh); return cn_call_callback(msg, (void (*)(void *))kfree_skb, skb); } /* * Main netlink receiving function. * * It checks skb and netlink header sizes and calls the skb receive * helper with a shared skb. */ static void cn_rx_skb(struct sk_buff *__skb) { struct nlmsghdr *nlh; u32 len; int err; struct sk_buff *skb; skb = skb_get(__skb); if (skb->len >= NLMSG_SPACE(0)) { nlh = nlmsg_hdr(skb); if (nlh->nlmsg_len < sizeof(struct cn_msg) || skb->len < nlh->nlmsg_len || nlh->nlmsg_len > CONNECTOR_MAX_MSG_SIZE) { kfree_skb(skb); goto out; } len = NLMSG_ALIGN(nlh->nlmsg_len); if (len > skb->len) len = skb->len; err = __cn_rx_skb(skb, nlh); if (err < 0) kfree_skb(skb); } out: kfree_skb(__skb); } /* * Notification routing. * * Gets id and checks if there are notification request for it's idx * and val. If there are such requests notify the listeners with the * given notify event. * */ static void cn_notify(struct cb_id *id, u32 notify_event) { struct cn_ctl_entry *ent; mutex_lock(¬ify_lock); list_for_each_entry(ent, ¬ify_list, notify_entry) { int i; struct cn_notify_req *req; struct cn_ctl_msg *ctl = ent->msg; int idx_found, val_found; idx_found = val_found = 0; req = (struct cn_notify_req *)ctl->data; for (i = 0; i < ctl->idx_notify_num; ++i, ++req) { if (id->idx >= req->first && id->idx < req->first + req->range) { idx_found = 1; break; } } for (i = 0; i < ctl->val_notify_num; ++i, ++req) { if (id->val >= req->first && id->val < req->first + req->range) { val_found = 1; break; } } if (idx_found && val_found) { struct cn_msg m = { .ack = notify_event, }; memcpy(&m.id, id, sizeof(m.id)); cn_netlink_send(&m, ctl->group, GFP_KERNEL); } } mutex_unlock(¬ify_lock); } /* * 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, char *name, void (*callback)(void *)) { 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; cn_notify(id, 0); 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); cn_notify(id, 1); } EXPORT_SYMBOL_GPL(cn_del_callback); /* * Checks two connector's control messages to be the same. * Returns 1 if they are the same or if the first one is corrupted. */ static int cn_ctl_msg_equals(struct cn_ctl_msg *m1, struct cn_ctl_msg *m2) { int i; struct cn_notify_req *req1, *req2; if (m1->idx_notify_num != m2->idx_notify_num) return 0; if (m1->val_notify_num != m2->val_notify_num) return 0; if (m1->len != m2->len) return 0; if ((m1->idx_notify_num + m1->val_notify_num) * sizeof(*req1) != m1->len) return 1; req1 = (struct cn_notify_req *)m1->data; req2 = (struct cn_notify_req *)m2->data; for (i = 0; i < m1->idx_notify_num; ++i) { if (req1->first != req2->first || req1->range != req2->range) return 0; req1++; req2++; } for (i = 0; i < m1->val_notify_num; ++i) { if (req1->first != req2->first || req1->range != req2->range) return 0; req1++; req2++; } return 1; } /* * Main connector device's callback. * * Used for notification of a request's processing. */ static void cn_callback(void *data) { struct cn_msg *msg = data; struct cn_ctl_msg *ctl; struct cn_ctl_entry *ent; u32 size; if (msg->len < sizeof(*ctl)) return; ctl = (struct cn_ctl_msg *)msg->data; size = (sizeof(*ctl) + ((ctl->idx_notify_num + ctl->val_notify_num) * sizeof(struct cn_notify_req))); if (msg->len != size) return; if (ctl->len + sizeof(*ctl) != msg->len) return; /* * Remove notification. */ if (ctl->group == 0) { struct cn_ctl_entry *n; mutex_lock(¬ify_lock); list_for_each_entry_safe(ent, n, ¬ify_list, notify_entry) { if (cn_ctl_msg_equals(ent->msg, ctl)) { list_del(&ent->notify_entry); kfree(ent); } } mutex_unlock(¬ify_lock); return; } size += sizeof(*ent); ent = kzalloc(size, GFP_KERNEL); if (!ent) return; ent->msg = (struct cn_ctl_msg *)(ent + 1); memcpy(ent->msg, ctl, size - sizeof(*ent)); mutex_lock(¬ify_lock); list_add(&ent->notify_entry, ¬ify_list); mutex_unlock(¬ify_lock); } static int __devinit cn_init(void) { struct cn_dev *dev = &cdev; int err; dev->input = cn_rx_skb; dev->id.idx = cn_idx; dev->id.val = cn_val; dev->nls = netlink_kernel_create(&init_net, NETLINK_CONNECTOR, CN_NETLINK_USERS + 0xf, dev->input, NULL, THIS_MODULE); if (!dev->nls) return -EIO; dev->cbdev = cn_queue_alloc_dev("cqueue", dev->nls); if (!dev->cbdev) { if (dev->nls->sk_socket) sock_release(dev->nls->sk_socket); return -EINVAL; } cn_already_initialized = 1; err = cn_add_callback(&dev->id, "connector", &cn_callback); if (err) { cn_already_initialized = 0; cn_queue_free_dev(dev->cbdev); if (dev->nls->sk_socket) sock_release(dev->nls->sk_socket); return -EINVAL; } return 0; } static void __devexit cn_fini(void) { struct cn_dev *dev = &cdev; cn_already_initialized = 0; cn_del_callback(&dev->id); cn_queue_free_dev(dev->cbdev); if (dev->nls->sk_socket) sock_release(dev->nls->sk_socket); } subsys_initcall(cn_init); module_exit(cn_fini);