ip_queue.c
上传用户:lgb322
上传日期:2013-02-24
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文件大小:17k
- /*
- * This is a module which is used for queueing IPv4 packets and
- * communicating with userspace via netlink.
- *
- * (C) 2000 James Morris, this code is GPL.
- *
- * 2000-03-27: Simplified code (thanks to Andi Kleen for clues).
- * 2000-05-20: Fixed notifier problems (following Miguel Freitas' report).
- * 2000-06-19: Fixed so nfmark is copied to metadata (reported by Sebastian
- * Zander).
- * 2000-08-01: Added Nick Williams' MAC support.
- *
- */
- #include <linux/module.h>
- #include <linux/skbuff.h>
- #include <linux/init.h>
- #include <linux/ip.h>
- #include <linux/notifier.h>
- #include <linux/netdevice.h>
- #include <linux/netfilter.h>
- #include <linux/netlink.h>
- #include <linux/spinlock.h>
- #include <linux/rtnetlink.h>
- #include <linux/sysctl.h>
- #include <linux/proc_fs.h>
- #include <net/sock.h>
- #include <net/route.h>
- #include <linux/netfilter_ipv4/ip_queue.h>
- #include <linux/netfilter_ipv4/ip_tables.h>
- #define IPQ_QMAX_DEFAULT 1024
- #define IPQ_PROC_FS_NAME "ip_queue"
- #define NET_IPQ_QMAX 2088
- #define NET_IPQ_QMAX_NAME "ip_queue_maxlen"
- typedef struct ipq_rt_info {
- __u8 tos;
- __u32 daddr;
- __u32 saddr;
- } ipq_rt_info_t;
- typedef struct ipq_queue_element {
- struct list_head list; /* Links element into queue */
- int verdict; /* Current verdict */
- struct nf_info *info; /* Extra info from netfilter */
- struct sk_buff *skb; /* Packet inside */
- ipq_rt_info_t rt_info; /* May need post-mangle routing */
- } ipq_queue_element_t;
- typedef int (*ipq_send_cb_t)(ipq_queue_element_t *e);
- typedef struct ipq_peer {
- pid_t pid; /* PID of userland peer */
- unsigned char died; /* We think the peer died */
- unsigned char copy_mode; /* Copy packet as well as metadata? */
- size_t copy_range; /* Range past metadata to copy */
- ipq_send_cb_t send; /* Callback for sending data to peer */
- } ipq_peer_t;
- typedef struct ipq_queue {
- int len; /* Current queue len */
- int *maxlen; /* Maximum queue len, via sysctl */
- unsigned char flushing; /* If queue is being flushed */
- unsigned char terminate; /* If the queue is being terminated */
- struct list_head list; /* Head of packet queue */
- spinlock_t lock; /* Queue spinlock */
- ipq_peer_t peer; /* Userland peer */
- } ipq_queue_t;
- /****************************************************************************
- *
- * Packet queue
- *
- ****************************************************************************/
- /* Dequeue a packet if matched by cmp, or the next available if cmp is NULL */
- static ipq_queue_element_t *
- ipq_dequeue(ipq_queue_t *q,
- int (*cmp)(ipq_queue_element_t *, unsigned long),
- unsigned long data)
- {
- struct list_head *i;
- spin_lock_bh(&q->lock);
- for (i = q->list.prev; i != &q->list; i = i->prev) {
- ipq_queue_element_t *e = (ipq_queue_element_t *)i;
-
- if (!cmp || cmp(e, data)) {
- list_del(&e->list);
- q->len--;
- spin_unlock_bh(&q->lock);
- return e;
- }
- }
- spin_unlock_bh(&q->lock);
- return NULL;
- }
- /* Flush all packets */
- static void ipq_flush(ipq_queue_t *q)
- {
- ipq_queue_element_t *e;
-
- spin_lock_bh(&q->lock);
- q->flushing = 1;
- spin_unlock_bh(&q->lock);
- while ((e = ipq_dequeue(q, NULL, 0))) {
- e->verdict = NF_DROP;
- nf_reinject(e->skb, e->info, e->verdict);
- kfree(e);
- }
- spin_lock_bh(&q->lock);
- q->flushing = 0;
- spin_unlock_bh(&q->lock);
- }
- static ipq_queue_t *ipq_create_queue(nf_queue_outfn_t outfn,
- ipq_send_cb_t send_cb,
- int *errp, int *sysctl_qmax)
- {
- int status;
- ipq_queue_t *q;
- *errp = 0;
- q = kmalloc(sizeof(ipq_queue_t), GFP_KERNEL);
- if (q == NULL) {
- *errp = -ENOMEM;
- return NULL;
- }
- q->peer.pid = 0;
- q->peer.died = 0;
- q->peer.copy_mode = IPQ_COPY_NONE;
- q->peer.copy_range = 0;
- q->peer.send = send_cb;
- q->len = 0;
- q->maxlen = sysctl_qmax;
- q->flushing = 0;
- q->terminate = 0;
- INIT_LIST_HEAD(&q->list);
- spin_lock_init(&q->lock);
- status = nf_register_queue_handler(PF_INET, outfn, q);
- if (status < 0) {
- *errp = -EBUSY;
- kfree(q);
- return NULL;
- }
- return q;
- }
- static int ipq_enqueue(ipq_queue_t *q,
- struct sk_buff *skb, struct nf_info *info)
- {
- ipq_queue_element_t *e;
- int status;
-
- e = kmalloc(sizeof(*e), GFP_ATOMIC);
- if (e == NULL) {
- printk(KERN_ERR "ip_queue: OOM in enqueuen");
- return -ENOMEM;
- }
- e->verdict = NF_DROP;
- e->info = info;
- e->skb = skb;
- if (e->info->hook == NF_IP_LOCAL_OUT) {
- struct iphdr *iph = skb->nh.iph;
- e->rt_info.tos = iph->tos;
- e->rt_info.daddr = iph->daddr;
- e->rt_info.saddr = iph->saddr;
- }
- spin_lock_bh(&q->lock);
- if (q->len >= *q->maxlen) {
- spin_unlock_bh(&q->lock);
- if (net_ratelimit())
- printk(KERN_WARNING "ip_queue: full at %d entries, "
- "dropping packet(s).n", q->len);
- goto free_drop;
- }
- if (q->flushing || q->peer.copy_mode == IPQ_COPY_NONE
- || q->peer.pid == 0 || q->peer.died || q->terminate) {
- spin_unlock_bh(&q->lock);
- goto free_drop;
- }
- status = q->peer.send(e);
- if (status > 0) {
- list_add(&e->list, &q->list);
- q->len++;
- spin_unlock_bh(&q->lock);
- return status;
- }
- spin_unlock_bh(&q->lock);
- if (status == -ECONNREFUSED) {
- printk(KERN_INFO "ip_queue: peer %d died, "
- "resetting state and flushing queuen", q->peer.pid);
- q->peer.died = 1;
- q->peer.pid = 0;
- q->peer.copy_mode = IPQ_COPY_NONE;
- q->peer.copy_range = 0;
- ipq_flush(q);
- }
- free_drop:
- kfree(e);
- return -EBUSY;
- }
- static void ipq_destroy_queue(ipq_queue_t *q)
- {
- nf_unregister_queue_handler(PF_INET);
- spin_lock_bh(&q->lock);
- q->terminate = 1;
- spin_unlock_bh(&q->lock);
- ipq_flush(q);
- kfree(q);
- }
- static int ipq_mangle_ipv4(ipq_verdict_msg_t *v, ipq_queue_element_t *e)
- {
- int diff;
- struct iphdr *user_iph = (struct iphdr *)v->payload;
- if (v->data_len < sizeof(*user_iph))
- return 0;
- diff = v->data_len - e->skb->len;
- if (diff < 0)
- skb_trim(e->skb, v->data_len);
- else if (diff > 0) {
- if (v->data_len > 0xFFFF)
- return -EINVAL;
- if (diff > skb_tailroom(e->skb)) {
- struct sk_buff *newskb;
-
- newskb = skb_copy_expand(e->skb,
- skb_headroom(e->skb),
- diff,
- GFP_ATOMIC);
- if (newskb == NULL) {
- printk(KERN_WARNING "ip_queue: OOM "
- "in mangle, dropping packetn");
- return -ENOMEM;
- }
- if (e->skb->sk)
- skb_set_owner_w(newskb, e->skb->sk);
- kfree_skb(e->skb);
- e->skb = newskb;
- }
- skb_put(e->skb, diff);
- }
- memcpy(e->skb->data, v->payload, v->data_len);
- e->skb->nfcache |= NFC_ALTERED;
- /*
- * Extra routing may needed on local out, as the QUEUE target never
- * returns control to the table.
- */
- if (e->info->hook == NF_IP_LOCAL_OUT) {
- struct iphdr *iph = e->skb->nh.iph;
- if (!(iph->tos == e->rt_info.tos
- && iph->daddr == e->rt_info.daddr
- && iph->saddr == e->rt_info.saddr))
- return ip_route_me_harder(&e->skb);
- }
- return 0;
- }
- static inline int id_cmp(ipq_queue_element_t *e, unsigned long id)
- {
- return (id == (unsigned long )e);
- }
- static int ipq_set_verdict(ipq_queue_t *q,
- ipq_verdict_msg_t *v, unsigned int len)
- {
- ipq_queue_element_t *e;
- if (v->value > NF_MAX_VERDICT)
- return -EINVAL;
- e = ipq_dequeue(q, id_cmp, v->id);
- if (e == NULL)
- return -ENOENT;
- else {
- e->verdict = v->value;
- if (v->data_len && v->data_len == len)
- if (ipq_mangle_ipv4(v, e) < 0)
- e->verdict = NF_DROP;
- nf_reinject(e->skb, e->info, e->verdict);
- kfree(e);
- return 0;
- }
- }
- static int ipq_receive_peer(ipq_queue_t *q, ipq_peer_msg_t *m,
- unsigned char type, unsigned int len)
- {
- int status = 0;
- int busy;
-
- spin_lock_bh(&q->lock);
- busy = (q->terminate || q->flushing);
- spin_unlock_bh(&q->lock);
- if (busy)
- return -EBUSY;
- if (len < sizeof(ipq_peer_msg_t))
- return -EINVAL;
- switch (type) {
- case IPQM_MODE:
- switch (m->msg.mode.value) {
- case IPQ_COPY_META:
- q->peer.copy_mode = IPQ_COPY_META;
- q->peer.copy_range = 0;
- break;
- case IPQ_COPY_PACKET:
- q->peer.copy_mode = IPQ_COPY_PACKET;
- q->peer.copy_range = m->msg.mode.range;
- if (q->peer.copy_range > 0xFFFF)
- q->peer.copy_range = 0xFFFF;
- break;
- default:
- status = -EINVAL;
- }
- break;
- case IPQM_VERDICT:
- if (m->msg.verdict.value > NF_MAX_VERDICT)
- status = -EINVAL;
- else
- status = ipq_set_verdict(q,
- &m->msg.verdict,
- len - sizeof(*m));
- break;
- default:
- status = -EINVAL;
- }
- return status;
- }
- static inline int dev_cmp(ipq_queue_element_t *e, unsigned long ifindex)
- {
- if (e->info->indev)
- if (e->info->indev->ifindex == ifindex)
- return 1;
- if (e->info->outdev)
- if (e->info->outdev->ifindex == ifindex)
- return 1;
- return 0;
- }
- /* Drop any queued packets associated with device ifindex */
- static void ipq_dev_drop(ipq_queue_t *q, int ifindex)
- {
- ipq_queue_element_t *e;
-
- while ((e = ipq_dequeue(q, dev_cmp, ifindex))) {
- e->verdict = NF_DROP;
- nf_reinject(e->skb, e->info, e->verdict);
- kfree(e);
- }
- }
- /****************************************************************************
- *
- * Netfilter interface
- *
- ****************************************************************************/
- /*
- * Packets arrive here from netfilter for queuing to userspace.
- * All of them must be fed back via nf_reinject() or Alexey will kill Rusty.
- */
- static int netfilter_receive(struct sk_buff *skb,
- struct nf_info *info, void *data)
- {
- return ipq_enqueue((ipq_queue_t *)data, skb, info);
- }
- /****************************************************************************
- *
- * Netlink interface.
- *
- ****************************************************************************/
- static struct sock *nfnl = NULL;
- ipq_queue_t *nlq = NULL;
- static struct sk_buff *netlink_build_message(ipq_queue_element_t *e, int *errp)
- {
- unsigned char *old_tail;
- size_t size = 0;
- size_t data_len = 0;
- struct sk_buff *skb;
- ipq_packet_msg_t *pm;
- struct nlmsghdr *nlh;
- switch (nlq->peer.copy_mode) {
- size_t copy_range;
- case IPQ_COPY_META:
- size = NLMSG_SPACE(sizeof(*pm));
- data_len = 0;
- break;
- case IPQ_COPY_PACKET:
- copy_range = nlq->peer.copy_range;
- if (copy_range == 0 || copy_range > e->skb->len)
- data_len = e->skb->len;
- else
- data_len = copy_range;
- size = NLMSG_SPACE(sizeof(*pm) + data_len);
-
- break;
- case IPQ_COPY_NONE:
- default:
- *errp = -EINVAL;
- return NULL;
- }
- skb = alloc_skb(size, GFP_ATOMIC);
- if (!skb)
- goto nlmsg_failure;
- old_tail = skb->tail;
- nlh = NLMSG_PUT(skb, 0, 0, IPQM_PACKET, size - sizeof(*nlh));
- pm = NLMSG_DATA(nlh);
- memset(pm, 0, sizeof(*pm));
- pm->packet_id = (unsigned long )e;
- pm->data_len = data_len;
- pm->timestamp_sec = e->skb->stamp.tv_sec;
- pm->timestamp_usec = e->skb->stamp.tv_usec;
- pm->mark = e->skb->nfmark;
- pm->hook = e->info->hook;
- if (e->info->indev) strcpy(pm->indev_name, e->info->indev->name);
- else pm->indev_name[0] = ' ';
- if (e->info->outdev) strcpy(pm->outdev_name, e->info->outdev->name);
- else pm->outdev_name[0] = ' ';
- pm->hw_protocol = e->skb->protocol;
- if (e->info->indev && e->skb->dev) {
- pm->hw_type = e->skb->dev->type;
- if (e->skb->dev->hard_header_parse)
- pm->hw_addrlen =
- e->skb->dev->hard_header_parse(e->skb,
- pm->hw_addr);
- }
- if (data_len)
- memcpy(pm->payload, e->skb->data, data_len);
- nlh->nlmsg_len = skb->tail - old_tail;
- NETLINK_CB(skb).dst_groups = 0;
- return skb;
- nlmsg_failure:
- if (skb)
- kfree_skb(skb);
- *errp = 0;
- printk(KERN_ERR "ip_queue: error creating netlink messagen");
- return NULL;
- }
- static int netlink_send_peer(ipq_queue_element_t *e)
- {
- int status = 0;
- struct sk_buff *skb;
- skb = netlink_build_message(e, &status);
- if (skb == NULL)
- return status;
- return netlink_unicast(nfnl, skb, nlq->peer.pid, MSG_DONTWAIT);
- }
- #define RCV_SKB_FAIL(err) do { netlink_ack(skb, nlh, (err)); return; } while (0);
- static __inline__ void netlink_receive_user_skb(struct sk_buff *skb)
- {
- int status, type;
- struct nlmsghdr *nlh;
- if (skb->len < sizeof(struct nlmsghdr))
- return;
- nlh = (struct nlmsghdr *)skb->data;
- if (nlh->nlmsg_len < sizeof(struct nlmsghdr)
- || skb->len < nlh->nlmsg_len)
- return;
- if(nlh->nlmsg_pid <= 0
- || !(nlh->nlmsg_flags & NLM_F_REQUEST)
- || nlh->nlmsg_flags & NLM_F_MULTI)
- RCV_SKB_FAIL(-EINVAL);
- if (nlh->nlmsg_flags & MSG_TRUNC)
- RCV_SKB_FAIL(-ECOMM);
- type = nlh->nlmsg_type;
- if (type < NLMSG_NOOP || type >= IPQM_MAX)
- RCV_SKB_FAIL(-EINVAL);
- if (type <= IPQM_BASE)
- return;
- if(!cap_raised(NETLINK_CB(skb).eff_cap, CAP_NET_ADMIN))
- RCV_SKB_FAIL(-EPERM);
- if (nlq->peer.pid && !nlq->peer.died
- && (nlq->peer.pid != nlh->nlmsg_pid)) {
- printk(KERN_WARNING "ip_queue: peer pid changed from %d to "
- "%d, flushing queuen", nlq->peer.pid, nlh->nlmsg_pid);
- ipq_flush(nlq);
- }
- nlq->peer.pid = nlh->nlmsg_pid;
- nlq->peer.died = 0;
- status = ipq_receive_peer(nlq, NLMSG_DATA(nlh),
- type, skb->len - NLMSG_LENGTH(0));
- if (status < 0)
- RCV_SKB_FAIL(status);
- if (nlh->nlmsg_flags & NLM_F_ACK)
- netlink_ack(skb, nlh, 0);
- return;
- }
- /* Note: we are only dealing with single part messages at the moment. */
- static void netlink_receive_user_sk(struct sock *sk, int len)
- {
- do {
- struct sk_buff *skb;
- if (rtnl_shlock_nowait())
- return;
- while ((skb = skb_dequeue(&sk->receive_queue)) != NULL) {
- netlink_receive_user_skb(skb);
- kfree_skb(skb);
- }
- up(&rtnl_sem);
- } while (nfnl && nfnl->receive_queue.qlen);
- }
- /****************************************************************************
- *
- * System events
- *
- ****************************************************************************/
- static int receive_event(struct notifier_block *this,
- unsigned long event, void *ptr)
- {
- struct net_device *dev = ptr;
- /* Drop any packets associated with the downed device */
- if (event == NETDEV_DOWN)
- ipq_dev_drop(nlq, dev->ifindex);
- return NOTIFY_DONE;
- }
- struct notifier_block ipq_dev_notifier = {
- receive_event,
- NULL,
- 0
- };
- /****************************************************************************
- *
- * Sysctl - queue tuning.
- *
- ****************************************************************************/
- static int sysctl_maxlen = IPQ_QMAX_DEFAULT;
- static struct ctl_table_header *ipq_sysctl_header;
- static ctl_table ipq_table[] = {
- { NET_IPQ_QMAX, NET_IPQ_QMAX_NAME, &sysctl_maxlen,
- sizeof(sysctl_maxlen), 0644, NULL, proc_dointvec },
- { 0 }
- };
- static ctl_table ipq_dir_table[] = {
- {NET_IPV4, "ipv4", NULL, 0, 0555, ipq_table, 0, 0, 0, 0, 0},
- { 0 }
- };
- static ctl_table ipq_root_table[] = {
- {CTL_NET, "net", NULL, 0, 0555, ipq_dir_table, 0, 0, 0, 0, 0},
- { 0 }
- };
- /****************************************************************************
- *
- * Procfs - debugging info.
- *
- ****************************************************************************/
- static int ipq_get_info(char *buffer, char **start, off_t offset, int length)
- {
- int len;
- spin_lock_bh(&nlq->lock);
- len = sprintf(buffer,
- "Peer pid : %dn"
- "Peer died : %dn"
- "Peer copy mode : %dn"
- "Peer copy range : %Zun"
- "Queue length : %dn"
- "Queue max. length : %dn"
- "Queue flushing : %dn"
- "Queue terminate : %dn",
- nlq->peer.pid,
- nlq->peer.died,
- nlq->peer.copy_mode,
- nlq->peer.copy_range,
- nlq->len,
- *nlq->maxlen,
- nlq->flushing,
- nlq->terminate);
- spin_unlock_bh(&nlq->lock);
- *start = buffer + offset;
- len -= offset;
- if (len > length)
- len = length;
- else if (len < 0)
- len = 0;
- return len;
- }
- /****************************************************************************
- *
- * Module stuff.
- *
- ****************************************************************************/
- static int __init init(void)
- {
- int status = 0;
- struct proc_dir_entry *proc;
-
- nfnl = netlink_kernel_create(NETLINK_FIREWALL, netlink_receive_user_sk);
- if (nfnl == NULL) {
- printk(KERN_ERR "ip_queue: initialisation failed: unable to "
- "create kernel netlink socketn");
- return -ENOMEM;
- }
- nlq = ipq_create_queue(netfilter_receive,
- netlink_send_peer, &status, &sysctl_maxlen);
- if (nlq == NULL) {
- printk(KERN_ERR "ip_queue: initialisation failed: unable to "
- "create queuen");
- sock_release(nfnl->socket);
- return status;
- }
- proc = proc_net_create(IPQ_PROC_FS_NAME, 0, ipq_get_info);
- if (proc) proc->owner = THIS_MODULE;
- else {
- ipq_destroy_queue(nlq);
- sock_release(nfnl->socket);
- return -ENOMEM;
- }
- register_netdevice_notifier(&ipq_dev_notifier);
- ipq_sysctl_header = register_sysctl_table(ipq_root_table, 0);
- return status;
- }
- static void __exit fini(void)
- {
- unregister_sysctl_table(ipq_sysctl_header);
- proc_net_remove(IPQ_PROC_FS_NAME);
- unregister_netdevice_notifier(&ipq_dev_notifier);
- ipq_destroy_queue(nlq);
- sock_release(nfnl->socket);
- }
- MODULE_DESCRIPTION("IPv4 packet queue handler");
- MODULE_LICENSE("GPL");
- module_init(init);
- module_exit(fini);