[NET]: Store skb->timestamp as offset to a base timestamp

[mirror_ubuntu-bionic-kernel.git] / net / ipv6 / netfilter / ip6_queue.c

/*
 * This is a module which is used for queueing IPv6 packets and
 * communicating with userspace via netlink.
 *
 * (C) 2001 Fernando Anton, this code is GPL.
 *     IPv64 Project - Work based in IPv64 draft by Arturo Azcorra.
 *     Universidad Carlos III de Madrid - Leganes (Madrid) - Spain
 *     Universidad Politecnica de Alcala de Henares - Alcala de H. (Madrid) - Spain
 *     email: fanton@it.uc3m.es
 *
 * 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.
 *
 * 2001-11-06: First try. Working with ip_queue.c for IPv4 and trying
 *             to adapt it to IPv6
 *             HEAVILY based in ipqueue.c by James Morris. It's just
 *             a little modified version of it, so he's nearly the
 *             real coder of this.
 *             Few changes needed, mainly the hard_routing code and
 *             the netlink socket protocol (we're NETLINK_IP6_FW).
 * 2002-06-25: Code cleanup. [JM: ported cleanup over from ip_queue.c]
 * 2005-02-04: Added /proc counter for dropped packets; fixed so
 *             packets aren't delivered to user space if they're going
 *             to be dropped.
 */
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/init.h>
#include <linux/ipv6.h>
#include <linux/notifier.h>
#include <linux/netdevice.h>
#include <linux/netfilter.h>
#include <linux/netlink.h>
#include <linux/spinlock.h>
#include <linux/sysctl.h>
#include <linux/proc_fs.h>
#include <net/sock.h>
#include <net/ipv6.h>
#include <net/ip6_route.h>
#include <linux/netfilter_ipv4/ip_queue.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netfilter_ipv6/ip6_tables.h>

#define IPQ_QMAX_DEFAULT 1024
#define IPQ_PROC_FS_NAME "ip6_queue"
#define NET_IPQ_QMAX 2088
#define NET_IPQ_QMAX_NAME "ip6_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 = IPQ_COPY_NONE;
static unsigned int queue_maxlen = IPQ_QMAX_DEFAULT;
static DEFINE_RWLOCK(queue_lock);
static int peer_pid;
static unsigned int copy_range;
static unsigned int queue_total;
static unsigned int queue_dropped = 0;
static unsigned int queue_user_dropped = 0;
static struct sock *ipqnl;
static LIST_HEAD(queue_list);
static DECLARE_MUTEX(ipqnl_sem);

static void
ipq_issue_verdict(struct ipq_queue_entry *entry, int verdict)
{
        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_HW &&
                    (*errp = skb_checksum_help(entry->skb,
                                               entry->info->outdev == NULL))) {
                        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   = skb_tv_base.tv_sec + entry->skb->tstamp.off_sec;
        pmsg->timestamp_usec  = skb_tv_base.tv_usec + entry->skb->tstamp.off_usec;
        pmsg->mark            = entry->skb->nfmark;
        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 "ip6_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 "ip6_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 "ip6_queue: fill at %d entries, "
                                "dropping packet(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_ipv6(ipq_verdict_msg_t *v, struct ipq_queue_entry *e)
{
        int diff;
        struct ipv6hdr *user_iph = (struct ipv6hdr *)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 "ip6_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_ipv6(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;

        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))
                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,
                                  skblen - 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;

        down(&ipqnl_sem);
                        
        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);
        }
                
        up(&ipqnl_sem);
}

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_IP6_FW && 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_IPV6,
                .procname       = "ipv6",
                .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 }
};

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"
                      "Netfilter 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;
}

static struct nf_queue_handler nfqh = {
        .name   = "ip6_queue",
        .outfn  = &ipq_enqueue_packet,
};

static int
init_or_cleanup(int init)
{
        int status = -ENOMEM;
        struct proc_dir_entry *proc;
        
        if (!init)
                goto cleanup;

        netlink_register_notifier(&ipq_nl_notifier);
        ipqnl = netlink_kernel_create(NETLINK_IP6_FW, ipq_rcv_sk, THIS_MODULE);
        if (ipqnl == NULL) {
                printk(KERN_ERR "ip6_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 "ip6_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, 0);
        
        status = nf_register_queue_handler(PF_INET6, &nfqh);
        if (status < 0) {
                printk(KERN_ERR "ip6_queue: failed to register queue handler\n");
                goto cleanup_sysctl;
        }
        return status;

cleanup:
        nf_unregister_queue_handlers(&nfqh);
        synchronize_net();
        ipq_flush(NF_DROP);
        
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);
        down(&ipqnl_sem);
        up(&ipqnl_sem);
        
cleanup_netlink_notifier:
        netlink_unregister_notifier(&ipq_nl_notifier);
        return status;
}

static int __init init(void)
{
        
        return init_or_cleanup(1);
}

static void __exit fini(void)
{
        init_or_cleanup(0);
}

MODULE_DESCRIPTION("IPv6 packet queue handler");
MODULE_LICENSE("GPL");

module_init(init);
module_exit(fini);