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- /*
- * This is a module which is used for queueing IPv4 packets and
- * communicating with userspace via netlink.
- *
- * (C) 2000-2002 James Morris <jmorris@intercode.com.au>
- * (C) 2003-2005 Netfilter Core Team <coreteam@netfilter.org>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- *
- * 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.
- * 2002-06-25: Code cleanup.
- * 2005-01-10: Added /proc counter for dropped packets; fixed so
- * packets aren't delivered to user space if they're going
- * to be dropped.
- * 2005-05-26: local_bh_{disable,enable} around nf_reinject (Harald Welte)
- *
- */
- #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/netfilter_ipv4/ip_queue.h>
- #include <linux/netfilter_ipv4/ip_tables.h>
- #include <linux/netlink.h>
- #include <linux/spinlock.h>
- #include <linux/sysctl.h>
- #include <linux/proc_fs.h>
- #include <linux/security.h>
- #include <linux/mutex.h>
- #include <net/sock.h>
- #include <net/route.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"
- struct ipq_queue_entry {
- struct list_head list;
- struct nf_info *info;
- struct sk_buff *skb;
- };
- typedef int (*ipq_cmpfn)(struct ipq_queue_entry *, unsigned long);
- static unsigned char copy_mode __read_mostly = IPQ_COPY_NONE;
- static unsigned int queue_maxlen __read_mostly = IPQ_QMAX_DEFAULT;
- static DEFINE_RWLOCK(queue_lock);
- static int peer_pid __read_mostly;
- static unsigned int copy_range __read_mostly;
- static unsigned int queue_total;
- static unsigned int queue_dropped = 0;
- static unsigned int queue_user_dropped = 0;
- static struct sock *ipqnl __read_mostly;
- static LIST_HEAD(queue_list);
- static DEFINE_MUTEX(ipqnl_mutex);
- static void
- ipq_issue_verdict(struct ipq_queue_entry *entry, int verdict)
- {
- /* TCP input path (and probably other bits) assume to be called
- * from softirq context, not from syscall, like ipq_issue_verdict is
- * called. TCP input path deadlocks with locks taken from timer
- * softirq, e.g. We therefore emulate this by local_bh_disable() */
- local_bh_disable();
- nf_reinject(entry->skb, entry->info, verdict);
- local_bh_enable();
- kfree(entry);
- }
- static inline void
- __ipq_enqueue_entry(struct ipq_queue_entry *entry)
- {
- list_add(&entry->list, &queue_list);
- queue_total++;
- }
- /*
- * Find and return a queued entry matched by cmpfn, or return the last
- * entry if cmpfn is NULL.
- */
- static inline struct ipq_queue_entry *
- __ipq_find_entry(ipq_cmpfn cmpfn, unsigned long data)
- {
- struct list_head *p;
- list_for_each_prev(p, &queue_list) {
- struct ipq_queue_entry *entry = (struct ipq_queue_entry *)p;
- if (!cmpfn || cmpfn(entry, data))
- return entry;
- }
- return NULL;
- }
- static inline void
- __ipq_dequeue_entry(struct ipq_queue_entry *entry)
- {
- list_del(&entry->list);
- queue_total--;
- }
- static inline struct ipq_queue_entry *
- __ipq_find_dequeue_entry(ipq_cmpfn cmpfn, unsigned long data)
- {
- struct ipq_queue_entry *entry;
- entry = __ipq_find_entry(cmpfn, data);
- if (entry == NULL)
- return NULL;
- __ipq_dequeue_entry(entry);
- return entry;
- }
- static inline void
- __ipq_flush(int verdict)
- {
- struct ipq_queue_entry *entry;
- while ((entry = __ipq_find_dequeue_entry(NULL, 0)))
- ipq_issue_verdict(entry, verdict);
- }
- static inline int
- __ipq_set_mode(unsigned char mode, unsigned int range)
- {
- int status = 0;
- switch(mode) {
- case IPQ_COPY_NONE:
- case IPQ_COPY_META:
- copy_mode = mode;
- copy_range = 0;
- break;
- case IPQ_COPY_PACKET:
- copy_mode = mode;
- copy_range = range;
- if (copy_range > 0xFFFF)
- copy_range = 0xFFFF;
- break;
- default:
- status = -EINVAL;
- }
- return status;
- }
- static inline void
- __ipq_reset(void)
- {
- peer_pid = 0;
- net_disable_timestamp();
- __ipq_set_mode(IPQ_COPY_NONE, 0);
- __ipq_flush(NF_DROP);
- }
- static struct ipq_queue_entry *
- ipq_find_dequeue_entry(ipq_cmpfn cmpfn, unsigned long data)
- {
- struct ipq_queue_entry *entry;
- write_lock_bh(&queue_lock);
- entry = __ipq_find_dequeue_entry(cmpfn, data);
- write_unlock_bh(&queue_lock);
- return entry;
- }
- static void
- ipq_flush(int verdict)
- {
- write_lock_bh(&queue_lock);
- __ipq_flush(verdict);
- write_unlock_bh(&queue_lock);
- }
- static struct sk_buff *
- ipq_build_packet_message(struct ipq_queue_entry *entry, int *errp)
- {
- unsigned char *old_tail;
- size_t size = 0;
- size_t data_len = 0;
- struct sk_buff *skb;
- struct ipq_packet_msg *pmsg;
- struct nlmsghdr *nlh;
- read_lock_bh(&queue_lock);
- switch (copy_mode) {
- case IPQ_COPY_META:
- case IPQ_COPY_NONE:
- size = NLMSG_SPACE(sizeof(*pmsg));
- data_len = 0;
- break;
- case IPQ_COPY_PACKET:
- if ((entry->skb->ip_summed == CHECKSUM_PARTIAL ||
- entry->skb->ip_summed == CHECKSUM_COMPLETE) &&
- (*errp = skb_checksum_help(entry->skb))) {
- read_unlock_bh(&queue_lock);
- return NULL;
- }
- if (copy_range == 0 || copy_range > entry->skb->len)
- data_len = entry->skb->len;
- else
- data_len = copy_range;
- size = NLMSG_SPACE(sizeof(*pmsg) + data_len);
- break;
- default:
- *errp = -EINVAL;
- read_unlock_bh(&queue_lock);
- return NULL;
- }
- read_unlock_bh(&queue_lock);
- 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));
- pmsg = NLMSG_DATA(nlh);
- memset(pmsg, 0, sizeof(*pmsg));
- pmsg->packet_id = (unsigned long )entry;
- pmsg->data_len = data_len;
- pmsg->timestamp_sec = entry->skb->tstamp.off_sec;
- pmsg->timestamp_usec = entry->skb->tstamp.off_usec;
- pmsg->mark = entry->skb->mark;
- pmsg->hook = entry->info->hook;
- pmsg->hw_protocol = entry->skb->protocol;
- if (entry->info->indev)
- strcpy(pmsg->indev_name, entry->info->indev->name);
- else
- pmsg->indev_name[0] = '\0';
- if (entry->info->outdev)
- strcpy(pmsg->outdev_name, entry->info->outdev->name);
- else
- pmsg->outdev_name[0] = '\0';
- if (entry->info->indev && entry->skb->dev) {
- pmsg->hw_type = entry->skb->dev->type;
- if (entry->skb->dev->hard_header_parse)
- pmsg->hw_addrlen =
- entry->skb->dev->hard_header_parse(entry->skb,
- pmsg->hw_addr);
- }
- if (data_len)
- if (skb_copy_bits(entry->skb, 0, pmsg->payload, data_len))
- BUG();
- nlh->nlmsg_len = skb->tail - old_tail;
- return skb;
- nlmsg_failure:
- if (skb)
- kfree_skb(skb);
- *errp = -EINVAL;
- printk(KERN_ERR "ip_queue: error creating packet message\n");
- return NULL;
- }
- static int
- ipq_enqueue_packet(struct sk_buff *skb, struct nf_info *info,
- unsigned int queuenum, void *data)
- {
- int status = -EINVAL;
- struct sk_buff *nskb;
- struct ipq_queue_entry *entry;
- if (copy_mode == IPQ_COPY_NONE)
- return -EAGAIN;
- entry = kmalloc(sizeof(*entry), GFP_ATOMIC);
- if (entry == NULL) {
- printk(KERN_ERR "ip_queue: OOM in ipq_enqueue_packet()\n");
- return -ENOMEM;
- }
- entry->info = info;
- entry->skb = skb;
- nskb = ipq_build_packet_message(entry, &status);
- if (nskb == NULL)
- goto err_out_free;
- write_lock_bh(&queue_lock);
- if (!peer_pid)
- goto err_out_free_nskb;
- if (queue_total >= queue_maxlen) {
- queue_dropped++;
- status = -ENOSPC;
- if (net_ratelimit())
- printk (KERN_WARNING "ip_queue: full at %d entries, "
- "dropping packets(s). Dropped: %d\n", queue_total,
- queue_dropped);
- goto err_out_free_nskb;
- }
- /* netlink_unicast will either free the nskb or attach it to a socket */
- status = netlink_unicast(ipqnl, nskb, peer_pid, MSG_DONTWAIT);
- if (status < 0) {
- queue_user_dropped++;
- goto err_out_unlock;
- }
- __ipq_enqueue_entry(entry);
- write_unlock_bh(&queue_lock);
- return status;
- err_out_free_nskb:
- kfree_skb(nskb);
- err_out_unlock:
- write_unlock_bh(&queue_lock);
- err_out_free:
- kfree(entry);
- return status;
- }
- static int
- ipq_mangle_ipv4(ipq_verdict_msg_t *v, struct ipq_queue_entry *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) {
- if (pskb_trim(e->skb, v->data_len))
- return -ENOMEM;
- } 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 packet\n");
- 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);
- }
- if (!skb_make_writable(&e->skb, v->data_len))
- return -ENOMEM;
- memcpy(e->skb->data, v->payload, v->data_len);
- e->skb->ip_summed = CHECKSUM_NONE;
- return 0;
- }
- static inline int
- id_cmp(struct ipq_queue_entry *e, unsigned long id)
- {
- return (id == (unsigned long )e);
- }
- static int
- ipq_set_verdict(struct ipq_verdict_msg *vmsg, unsigned int len)
- {
- struct ipq_queue_entry *entry;
- if (vmsg->value > NF_MAX_VERDICT)
- return -EINVAL;
- entry = ipq_find_dequeue_entry(id_cmp, vmsg->id);
- if (entry == NULL)
- return -ENOENT;
- else {
- int verdict = vmsg->value;
- if (vmsg->data_len && vmsg->data_len == len)
- if (ipq_mangle_ipv4(vmsg, entry) < 0)
- verdict = NF_DROP;
- ipq_issue_verdict(entry, verdict);
- return 0;
- }
- }
- static int
- ipq_set_mode(unsigned char mode, unsigned int range)
- {
- int status;
- write_lock_bh(&queue_lock);
- status = __ipq_set_mode(mode, range);
- write_unlock_bh(&queue_lock);
- return status;
- }
- static int
- ipq_receive_peer(struct ipq_peer_msg *pmsg,
- unsigned char type, unsigned int len)
- {
- int status = 0;
- if (len < sizeof(*pmsg))
- return -EINVAL;
- switch (type) {
- case IPQM_MODE:
- status = ipq_set_mode(pmsg->msg.mode.value,
- pmsg->msg.mode.range);
- break;
- case IPQM_VERDICT:
- if (pmsg->msg.verdict.value > NF_MAX_VERDICT)
- status = -EINVAL;
- else
- status = ipq_set_verdict(&pmsg->msg.verdict,
- len - sizeof(*pmsg));
- break;
- default:
- status = -EINVAL;
- }
- return status;
- }
- static int
- dev_cmp(struct ipq_queue_entry *entry, unsigned long ifindex)
- {
- if (entry->info->indev)
- if (entry->info->indev->ifindex == ifindex)
- return 1;
- if (entry->info->outdev)
- if (entry->info->outdev->ifindex == ifindex)
- return 1;
- #ifdef CONFIG_BRIDGE_NETFILTER
- if (entry->skb->nf_bridge) {
- if (entry->skb->nf_bridge->physindev &&
- entry->skb->nf_bridge->physindev->ifindex == ifindex)
- return 1;
- if (entry->skb->nf_bridge->physoutdev &&
- entry->skb->nf_bridge->physoutdev->ifindex == ifindex)
- return 1;
- }
- #endif
- return 0;
- }
- static void
- ipq_dev_drop(int ifindex)
- {
- struct ipq_queue_entry *entry;
- while ((entry = ipq_find_dequeue_entry(dev_cmp, ifindex)) != NULL)
- ipq_issue_verdict(entry, NF_DROP);
- }
- #define RCV_SKB_FAIL(err) do { netlink_ack(skb, nlh, (err)); return; } while (0)
- static inline void
- ipq_rcv_skb(struct sk_buff *skb)
- {
- int status, type, pid, flags, nlmsglen, skblen;
- struct nlmsghdr *nlh;
- skblen = skb->len;
- if (skblen < sizeof(*nlh))
- return;
- nlh = (struct nlmsghdr *)skb->data;
- nlmsglen = nlh->nlmsg_len;
- if (nlmsglen < sizeof(*nlh) || skblen < nlmsglen)
- return;
- pid = nlh->nlmsg_pid;
- flags = nlh->nlmsg_flags;
- if(pid <= 0 || !(flags & NLM_F_REQUEST) || flags & NLM_F_MULTI)
- RCV_SKB_FAIL(-EINVAL);
- if (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 (security_netlink_recv(skb, CAP_NET_ADMIN))
- RCV_SKB_FAIL(-EPERM);
- write_lock_bh(&queue_lock);
- if (peer_pid) {
- if (peer_pid != pid) {
- write_unlock_bh(&queue_lock);
- RCV_SKB_FAIL(-EBUSY);
- }
- } else {
- net_enable_timestamp();
- peer_pid = pid;
- }
- write_unlock_bh(&queue_lock);
- status = ipq_receive_peer(NLMSG_DATA(nlh), type,
- nlmsglen - NLMSG_LENGTH(0));
- if (status < 0)
- RCV_SKB_FAIL(status);
- if (flags & NLM_F_ACK)
- netlink_ack(skb, nlh, 0);
- return;
- }
- static void
- ipq_rcv_sk(struct sock *sk, int len)
- {
- struct sk_buff *skb;
- unsigned int qlen;
- mutex_lock(&ipqnl_mutex);
- for (qlen = skb_queue_len(&sk->sk_receive_queue); qlen; qlen--) {
- skb = skb_dequeue(&sk->sk_receive_queue);
- ipq_rcv_skb(skb);
- kfree_skb(skb);
- }
- mutex_unlock(&ipqnl_mutex);
- }
- static int
- ipq_rcv_dev_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(dev->ifindex);
- return NOTIFY_DONE;
- }
- static struct notifier_block ipq_dev_notifier = {
- .notifier_call = ipq_rcv_dev_event,
- };
- static int
- ipq_rcv_nl_event(struct notifier_block *this,
- unsigned long event, void *ptr)
- {
- struct netlink_notify *n = ptr;
- if (event == NETLINK_URELEASE &&
- n->protocol == NETLINK_FIREWALL && n->pid) {
- write_lock_bh(&queue_lock);
- if (n->pid == peer_pid)
- __ipq_reset();
- write_unlock_bh(&queue_lock);
- }
- return NOTIFY_DONE;
- }
- static struct notifier_block ipq_nl_notifier = {
- .notifier_call = ipq_rcv_nl_event,
- };
- static struct ctl_table_header *ipq_sysctl_header;
- static ctl_table ipq_table[] = {
- {
- .ctl_name = NET_IPQ_QMAX,
- .procname = NET_IPQ_QMAX_NAME,
- .data = &queue_maxlen,
- .maxlen = sizeof(queue_maxlen),
- .mode = 0644,
- .proc_handler = proc_dointvec
- },
- { .ctl_name = 0 }
- };
- static ctl_table ipq_dir_table[] = {
- {
- .ctl_name = NET_IPV4,
- .procname = "ipv4",
- .mode = 0555,
- .child = ipq_table
- },
- { .ctl_name = 0 }
- };
- static ctl_table ipq_root_table[] = {
- {
- .ctl_name = CTL_NET,
- .procname = "net",
- .mode = 0555,
- .child = ipq_dir_table
- },
- { .ctl_name = 0 }
- };
- #ifdef CONFIG_PROC_FS
- static int
- ipq_get_info(char *buffer, char **start, off_t offset, int length)
- {
- int len;
- read_lock_bh(&queue_lock);
- len = sprintf(buffer,
- "Peer PID : %d\n"
- "Copy mode : %hu\n"
- "Copy range : %u\n"
- "Queue length : %u\n"
- "Queue max. length : %u\n"
- "Queue dropped : %u\n"
- "Netlink dropped : %u\n",
- peer_pid,
- copy_mode,
- copy_range,
- queue_total,
- queue_maxlen,
- queue_dropped,
- queue_user_dropped);
- read_unlock_bh(&queue_lock);
- *start = buffer + offset;
- len -= offset;
- if (len > length)
- len = length;
- else if (len < 0)
- len = 0;
- return len;
- }
- #endif /* CONFIG_PROC_FS */
- static struct nf_queue_handler nfqh = {
- .name = "ip_queue",
- .outfn = &ipq_enqueue_packet,
- };
- static int __init ip_queue_init(void)
- {
- int status = -ENOMEM;
- struct proc_dir_entry *proc;
- netlink_register_notifier(&ipq_nl_notifier);
- ipqnl = netlink_kernel_create(NETLINK_FIREWALL, 0, ipq_rcv_sk,
- THIS_MODULE);
- if (ipqnl == NULL) {
- printk(KERN_ERR "ip_queue: failed to create netlink socket\n");
- goto cleanup_netlink_notifier;
- }
- proc = proc_net_create(IPQ_PROC_FS_NAME, 0, ipq_get_info);
- if (proc)
- proc->owner = THIS_MODULE;
- else {
- printk(KERN_ERR "ip_queue: failed to create proc entry\n");
- goto cleanup_ipqnl;
- }
- register_netdevice_notifier(&ipq_dev_notifier);
- ipq_sysctl_header = register_sysctl_table(ipq_root_table);
- status = nf_register_queue_handler(PF_INET, &nfqh);
- if (status < 0) {
- printk(KERN_ERR "ip_queue: failed to register queue handler\n");
- goto cleanup_sysctl;
- }
- return status;
- cleanup_sysctl:
- unregister_sysctl_table(ipq_sysctl_header);
- unregister_netdevice_notifier(&ipq_dev_notifier);
- proc_net_remove(IPQ_PROC_FS_NAME);
- cleanup_ipqnl:
- sock_release(ipqnl->sk_socket);
- mutex_lock(&ipqnl_mutex);
- mutex_unlock(&ipqnl_mutex);
- cleanup_netlink_notifier:
- netlink_unregister_notifier(&ipq_nl_notifier);
- return status;
- }
- static void __exit ip_queue_fini(void)
- {
- nf_unregister_queue_handlers(&nfqh);
- synchronize_net();
- ipq_flush(NF_DROP);
- unregister_sysctl_table(ipq_sysctl_header);
- unregister_netdevice_notifier(&ipq_dev_notifier);
- proc_net_remove(IPQ_PROC_FS_NAME);
- sock_release(ipqnl->sk_socket);
- mutex_lock(&ipqnl_mutex);
- mutex_unlock(&ipqnl_mutex);
- netlink_unregister_notifier(&ipq_nl_notifier);
- }
- MODULE_DESCRIPTION("IPv4 packet queue handler");
- MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
- MODULE_LICENSE("GPL");
- module_init(ip_queue_init);
- module_exit(ip_queue_fini);
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