writeback: Fix performance regression in wb_over_bg_thresh()

[deliverable/linux.git] / net / netfilter / nfnetlink_queue.c

/*
 * This is a module which is used for queueing packets and communicating with
 * userspace via nfnetlink.
 *
 * (C) 2005 by Harald Welte <laforge@netfilter.org>
 * (C) 2007 by Patrick McHardy <kaber@trash.net>
 *
 * Based on the old ipv4-only ip_queue.c:
 * (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.
 *
 */
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/notifier.h>
#include <linux/netdevice.h>
#include <linux/netfilter.h>
#include <linux/proc_fs.h>
#include <linux/netfilter_ipv4.h>
#include <linux/netfilter_ipv6.h>
#include <linux/netfilter_bridge.h>
#include <linux/netfilter/nfnetlink.h>
#include <linux/netfilter/nfnetlink_queue.h>
#include <linux/netfilter/nf_conntrack_common.h>
#include <linux/list.h>
#include <net/sock.h>
#include <net/tcp_states.h>
#include <net/netfilter/nf_queue.h>
#include <net/netns/generic.h>

#include <linux/atomic.h>

#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
#include "../bridge/br_private.h"
#endif

#define NFQNL_QMAX_DEFAULT 1024

/* We're using struct nlattr which has 16bit nla_len. Note that nla_len
 * includes the header length. Thus, the maximum packet length that we
 * support is 65531 bytes. We send truncated packets if the specified length
 * is larger than that.  Userspace can check for presence of NFQA_CAP_LEN
 * attribute to detect truncation.
 */
#define NFQNL_MAX_COPY_RANGE (0xffff - NLA_HDRLEN)

struct nfqnl_instance {
        struct hlist_node hlist;                /* global list of queues */
        struct rcu_head rcu;

        u32 peer_portid;
        unsigned int queue_maxlen;
        unsigned int copy_range;
        unsigned int queue_dropped;
        unsigned int queue_user_dropped;


        u_int16_t queue_num;                    /* number of this queue */
        u_int8_t copy_mode;
        u_int32_t flags;                        /* Set using NFQA_CFG_FLAGS */
/*
 * Following fields are dirtied for each queued packet,
 * keep them in same cache line if possible.
 */
        spinlock_t      lock;
        unsigned int    queue_total;
        unsigned int    id_sequence;            /* 'sequence' of pkt ids */
        struct list_head queue_list;            /* packets in queue */
};

typedef int (*nfqnl_cmpfn)(struct nf_queue_entry *, unsigned long);

static int nfnl_queue_net_id __read_mostly;

#define INSTANCE_BUCKETS        16
struct nfnl_queue_net {
        spinlock_t instances_lock;
        struct hlist_head instance_table[INSTANCE_BUCKETS];
};

static struct nfnl_queue_net *nfnl_queue_pernet(struct net *net)
{
        return net_generic(net, nfnl_queue_net_id);
}

static inline u_int8_t instance_hashfn(u_int16_t queue_num)
{
        return ((queue_num >> 8) ^ queue_num) % INSTANCE_BUCKETS;
}

static struct nfqnl_instance *
instance_lookup(struct nfnl_queue_net *q, u_int16_t queue_num)
{
        struct hlist_head *head;
        struct nfqnl_instance *inst;

        head = &q->instance_table[instance_hashfn(queue_num)];
        hlist_for_each_entry_rcu(inst, head, hlist) {
                if (inst->queue_num == queue_num)
                        return inst;
        }
        return NULL;
}

static struct nfqnl_instance *
instance_create(struct nfnl_queue_net *q, u_int16_t queue_num, u32 portid)
{
        struct nfqnl_instance *inst;
        unsigned int h;
        int err;

        spin_lock(&q->instances_lock);
        if (instance_lookup(q, queue_num)) {
                err = -EEXIST;
                goto out_unlock;
        }

        inst = kzalloc(sizeof(*inst), GFP_ATOMIC);
        if (!inst) {
                err = -ENOMEM;
                goto out_unlock;
        }

        inst->queue_num = queue_num;
        inst->peer_portid = portid;
        inst->queue_maxlen = NFQNL_QMAX_DEFAULT;
        inst->copy_range = NFQNL_MAX_COPY_RANGE;
        inst->copy_mode = NFQNL_COPY_NONE;
        spin_lock_init(&inst->lock);
        INIT_LIST_HEAD(&inst->queue_list);

        if (!try_module_get(THIS_MODULE)) {
                err = -EAGAIN;
                goto out_free;
        }

        h = instance_hashfn(queue_num);
        hlist_add_head_rcu(&inst->hlist, &q->instance_table[h]);

        spin_unlock(&q->instances_lock);

        return inst;

out_free:
        kfree(inst);
out_unlock:
        spin_unlock(&q->instances_lock);
        return ERR_PTR(err);
}

static void nfqnl_flush(struct nfqnl_instance *queue, nfqnl_cmpfn cmpfn,
                        unsigned long data);

static void
instance_destroy_rcu(struct rcu_head *head)
{
        struct nfqnl_instance *inst = container_of(head, struct nfqnl_instance,
                                                   rcu);

        nfqnl_flush(inst, NULL, 0);
        kfree(inst);
        module_put(THIS_MODULE);
}

static void
__instance_destroy(struct nfqnl_instance *inst)
{
        hlist_del_rcu(&inst->hlist);
        call_rcu(&inst->rcu, instance_destroy_rcu);
}

static void
instance_destroy(struct nfnl_queue_net *q, struct nfqnl_instance *inst)
{
        spin_lock(&q->instances_lock);
        __instance_destroy(inst);
        spin_unlock(&q->instances_lock);
}

static inline void
__enqueue_entry(struct nfqnl_instance *queue, struct nf_queue_entry *entry)
{
       list_add_tail(&entry->list, &queue->queue_list);
       queue->queue_total++;
}

static void
__dequeue_entry(struct nfqnl_instance *queue, struct nf_queue_entry *entry)
{
        list_del(&entry->list);
        queue->queue_total--;
}

static struct nf_queue_entry *
find_dequeue_entry(struct nfqnl_instance *queue, unsigned int id)
{
        struct nf_queue_entry *entry = NULL, *i;

        spin_lock_bh(&queue->lock);

        list_for_each_entry(i, &queue->queue_list, list) {
                if (i->id == id) {
                        entry = i;
                        break;
                }
        }

        if (entry)
                __dequeue_entry(queue, entry);

        spin_unlock_bh(&queue->lock);

        return entry;
}

static void
nfqnl_flush(struct nfqnl_instance *queue, nfqnl_cmpfn cmpfn, unsigned long data)
{
        struct nf_queue_entry *entry, *next;

        spin_lock_bh(&queue->lock);
        list_for_each_entry_safe(entry, next, &queue->queue_list, list) {
                if (!cmpfn || cmpfn(entry, data)) {
                        list_del(&entry->list);
                        queue->queue_total--;
                        nf_reinject(entry, NF_DROP);
                }
        }
        spin_unlock_bh(&queue->lock);
}

static int
nfqnl_put_packet_info(struct sk_buff *nlskb, struct sk_buff *packet,
                      bool csum_verify)
{
        __u32 flags = 0;

        if (packet->ip_summed == CHECKSUM_PARTIAL)
                flags = NFQA_SKB_CSUMNOTREADY;
        else if (csum_verify)
                flags = NFQA_SKB_CSUM_NOTVERIFIED;

        if (skb_is_gso(packet))
                flags |= NFQA_SKB_GSO;

        return flags ? nla_put_be32(nlskb, NFQA_SKB_INFO, htonl(flags)) : 0;
}

static int nfqnl_put_sk_uidgid(struct sk_buff *skb, struct sock *sk)
{
        const struct cred *cred;

        if (!sk_fullsock(sk))
                return 0;

        read_lock_bh(&sk->sk_callback_lock);
        if (sk->sk_socket && sk->sk_socket->file) {
                cred = sk->sk_socket->file->f_cred;
                if (nla_put_be32(skb, NFQA_UID,
                    htonl(from_kuid_munged(&init_user_ns, cred->fsuid))))
                        goto nla_put_failure;
                if (nla_put_be32(skb, NFQA_GID,
                    htonl(from_kgid_munged(&init_user_ns, cred->fsgid))))
                        goto nla_put_failure;
        }
        read_unlock_bh(&sk->sk_callback_lock);
        return 0;

nla_put_failure:
        read_unlock_bh(&sk->sk_callback_lock);
        return -1;
}

static u32 nfqnl_get_sk_secctx(struct sk_buff *skb, char **secdata)
{
        u32 seclen = 0;
#if IS_ENABLED(CONFIG_NETWORK_SECMARK)
        if (!skb || !sk_fullsock(skb->sk))
                return 0;

        read_lock_bh(&skb->sk->sk_callback_lock);

        if (skb->secmark)
                security_secid_to_secctx(skb->secmark, secdata, &seclen);

        read_unlock_bh(&skb->sk->sk_callback_lock);
#endif
        return seclen;
}

static struct sk_buff *
nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue,
                           struct nf_queue_entry *entry,
                           __be32 **packet_id_ptr)
{
        size_t size;
        size_t data_len = 0, cap_len = 0;
        unsigned int hlen = 0;
        struct sk_buff *skb;
        struct nlattr *nla;
        struct nfqnl_msg_packet_hdr *pmsg;
        struct nlmsghdr *nlh;
        struct nfgenmsg *nfmsg;
        struct sk_buff *entskb = entry->skb;
        struct net_device *indev;
        struct net_device *outdev;
        struct nf_conn *ct = NULL;
        enum ip_conntrack_info uninitialized_var(ctinfo);
        struct nfnl_ct_hook *nfnl_ct;
        bool csum_verify;
        char *secdata = NULL;
        u32 seclen = 0;

        size =    nlmsg_total_size(sizeof(struct nfgenmsg))
                + nla_total_size(sizeof(struct nfqnl_msg_packet_hdr))
                + nla_total_size(sizeof(u_int32_t))     /* ifindex */
                + nla_total_size(sizeof(u_int32_t))     /* ifindex */
#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
                + nla_total_size(sizeof(u_int32_t))     /* ifindex */
                + nla_total_size(sizeof(u_int32_t))     /* ifindex */
#endif
                + nla_total_size(sizeof(u_int32_t))     /* mark */
                + nla_total_size(sizeof(struct nfqnl_msg_packet_hw))
                + nla_total_size(sizeof(u_int32_t))     /* skbinfo */
                + nla_total_size(sizeof(u_int32_t));    /* cap_len */

        if (entskb->tstamp.tv64)
                size += nla_total_size(sizeof(struct nfqnl_msg_packet_timestamp));

        if (entry->state.hook <= NF_INET_FORWARD ||
           (entry->state.hook == NF_INET_POST_ROUTING && entskb->sk == NULL))
                csum_verify = !skb_csum_unnecessary(entskb);
        else
                csum_verify = false;

        outdev = entry->state.out;

        switch ((enum nfqnl_config_mode)ACCESS_ONCE(queue->copy_mode)) {
        case NFQNL_COPY_META:
        case NFQNL_COPY_NONE:
                break;

        case NFQNL_COPY_PACKET:
                if (!(queue->flags & NFQA_CFG_F_GSO) &&
                    entskb->ip_summed == CHECKSUM_PARTIAL &&
                    skb_checksum_help(entskb))
                        return NULL;

                data_len = ACCESS_ONCE(queue->copy_range);
                if (data_len > entskb->len)
                        data_len = entskb->len;

                hlen = skb_zerocopy_headlen(entskb);
                hlen = min_t(unsigned int, hlen, data_len);
                size += sizeof(struct nlattr) + hlen;
                cap_len = entskb->len;
                break;
        }

        nfnl_ct = rcu_dereference(nfnl_ct_hook);

        if (queue->flags & NFQA_CFG_F_CONNTRACK) {
                if (nfnl_ct != NULL) {
                        ct = nfnl_ct->get_ct(entskb, &ctinfo);
                        if (ct != NULL)
                                size += nfnl_ct->build_size(ct);
                }
        }

        if (queue->flags & NFQA_CFG_F_UID_GID) {
                size +=  (nla_total_size(sizeof(u_int32_t))     /* uid */
                        + nla_total_size(sizeof(u_int32_t)));   /* gid */
        }

        if ((queue->flags & NFQA_CFG_F_SECCTX) && entskb->sk) {
                seclen = nfqnl_get_sk_secctx(entskb, &secdata);
                if (seclen)
                        size += nla_total_size(seclen);
        }

        skb = alloc_skb(size, GFP_ATOMIC);
        if (!skb) {
                skb_tx_error(entskb);
                return NULL;
        }

        nlh = nlmsg_put(skb, 0, 0,
                        NFNL_SUBSYS_QUEUE << 8 | NFQNL_MSG_PACKET,
                        sizeof(struct nfgenmsg), 0);
        if (!nlh) {
                skb_tx_error(entskb);
                kfree_skb(skb);
                return NULL;
        }
        nfmsg = nlmsg_data(nlh);
        nfmsg->nfgen_family = entry->state.pf;
        nfmsg->version = NFNETLINK_V0;
        nfmsg->res_id = htons(queue->queue_num);

        nla = __nla_reserve(skb, NFQA_PACKET_HDR, sizeof(*pmsg));
        pmsg = nla_data(nla);
        pmsg->hw_protocol       = entskb->protocol;
        pmsg->hook              = entry->state.hook;
        *packet_id_ptr          = &pmsg->packet_id;

        indev = entry->state.in;
        if (indev) {
#if !IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
                if (nla_put_be32(skb, NFQA_IFINDEX_INDEV, htonl(indev->ifindex)))
                        goto nla_put_failure;
#else
                if (entry->state.pf == PF_BRIDGE) {
                        /* Case 1: indev is physical input device, we need to
                         * look for bridge group (when called from
                         * netfilter_bridge) */
                        if (nla_put_be32(skb, NFQA_IFINDEX_PHYSINDEV,
                                         htonl(indev->ifindex)) ||
                        /* this is the bridge group "brX" */
                        /* rcu_read_lock()ed by __nf_queue */
                            nla_put_be32(skb, NFQA_IFINDEX_INDEV,
                                         htonl(br_port_get_rcu(indev)->br->dev->ifindex)))
                                goto nla_put_failure;
                } else {
                        int physinif;

                        /* Case 2: indev is bridge group, we need to look for
                         * physical device (when called from ipv4) */
                        if (nla_put_be32(skb, NFQA_IFINDEX_INDEV,
                                         htonl(indev->ifindex)))
                                goto nla_put_failure;

                        physinif = nf_bridge_get_physinif(entskb);
                        if (physinif &&
                            nla_put_be32(skb, NFQA_IFINDEX_PHYSINDEV,
                                         htonl(physinif)))
                                goto nla_put_failure;
                }
#endif
        }

        if (outdev) {
#if !IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
                if (nla_put_be32(skb, NFQA_IFINDEX_OUTDEV, htonl(outdev->ifindex)))
                        goto nla_put_failure;
#else
                if (entry->state.pf == PF_BRIDGE) {
                        /* Case 1: outdev is physical output device, we need to
                         * look for bridge group (when called from
                         * netfilter_bridge) */
                        if (nla_put_be32(skb, NFQA_IFINDEX_PHYSOUTDEV,
                                         htonl(outdev->ifindex)) ||
                        /* this is the bridge group "brX" */
                        /* rcu_read_lock()ed by __nf_queue */
                            nla_put_be32(skb, NFQA_IFINDEX_OUTDEV,
                                         htonl(br_port_get_rcu(outdev)->br->dev->ifindex)))
                                goto nla_put_failure;
                } else {
                        int physoutif;

                        /* Case 2: outdev is bridge group, we need to look for
                         * physical output device (when called from ipv4) */
                        if (nla_put_be32(skb, NFQA_IFINDEX_OUTDEV,
                                         htonl(outdev->ifindex)))
                                goto nla_put_failure;

                        physoutif = nf_bridge_get_physoutif(entskb);
                        if (physoutif &&
                            nla_put_be32(skb, NFQA_IFINDEX_PHYSOUTDEV,
                                         htonl(physoutif)))
                                goto nla_put_failure;
                }
#endif
        }

        if (entskb->mark &&
            nla_put_be32(skb, NFQA_MARK, htonl(entskb->mark)))
                goto nla_put_failure;

        if (indev && entskb->dev &&
            entskb->mac_header != entskb->network_header) {
                struct nfqnl_msg_packet_hw phw;
                int len;

                memset(&phw, 0, sizeof(phw));
                len = dev_parse_header(entskb, phw.hw_addr);
                if (len) {
                        phw.hw_addrlen = htons(len);
                        if (nla_put(skb, NFQA_HWADDR, sizeof(phw), &phw))
                                goto nla_put_failure;
                }
        }

        if (entskb->tstamp.tv64) {
                struct nfqnl_msg_packet_timestamp ts;
                struct timespec64 kts = ktime_to_timespec64(skb->tstamp);

                ts.sec = cpu_to_be64(kts.tv_sec);
                ts.usec = cpu_to_be64(kts.tv_nsec / NSEC_PER_USEC);

                if (nla_put(skb, NFQA_TIMESTAMP, sizeof(ts), &ts))
                        goto nla_put_failure;
        }

        if ((queue->flags & NFQA_CFG_F_UID_GID) && entskb->sk &&
            nfqnl_put_sk_uidgid(skb, entskb->sk) < 0)
                goto nla_put_failure;

        if (seclen && nla_put(skb, NFQA_SECCTX, seclen, secdata))
                goto nla_put_failure;

        if (ct && nfnl_ct->build(skb, ct, ctinfo, NFQA_CT, NFQA_CT_INFO) < 0)
                goto nla_put_failure;

        if (cap_len > data_len &&
            nla_put_be32(skb, NFQA_CAP_LEN, htonl(cap_len)))
                goto nla_put_failure;

        if (nfqnl_put_packet_info(skb, entskb, csum_verify))
                goto nla_put_failure;

        if (data_len) {
                struct nlattr *nla;

                if (skb_tailroom(skb) < sizeof(*nla) + hlen)
                        goto nla_put_failure;

                nla = (struct nlattr *)skb_put(skb, sizeof(*nla));
                nla->nla_type = NFQA_PAYLOAD;
                nla->nla_len = nla_attr_size(data_len);

                if (skb_zerocopy(skb, entskb, data_len, hlen))
                        goto nla_put_failure;
        }

        nlh->nlmsg_len = skb->len;
        return skb;

nla_put_failure:
        skb_tx_error(entskb);
        kfree_skb(skb);
        net_err_ratelimited("nf_queue: error creating packet message\n");
        return NULL;
}

static int
__nfqnl_enqueue_packet(struct net *net, struct nfqnl_instance *queue,
                        struct nf_queue_entry *entry)
{
        struct sk_buff *nskb;
        int err = -ENOBUFS;
        __be32 *packet_id_ptr;
        int failopen = 0;

        nskb = nfqnl_build_packet_message(net, queue, entry, &packet_id_ptr);
        if (nskb == NULL) {
                err = -ENOMEM;
                goto err_out;
        }
        spin_lock_bh(&queue->lock);

        if (queue->queue_total >= queue->queue_maxlen) {
                if (queue->flags & NFQA_CFG_F_FAIL_OPEN) {
                        failopen = 1;
                        err = 0;
                } else {
                        queue->queue_dropped++;
                        net_warn_ratelimited("nf_queue: full at %d entries, dropping packets(s)\n",
                                             queue->queue_total);
                }
                goto err_out_free_nskb;
        }
        entry->id = ++queue->id_sequence;
        *packet_id_ptr = htonl(entry->id);

        /* nfnetlink_unicast will either free the nskb or add it to a socket */
        err = nfnetlink_unicast(nskb, net, queue->peer_portid, MSG_DONTWAIT);
        if (err < 0) {
                queue->queue_user_dropped++;
                goto err_out_unlock;
        }

        __enqueue_entry(queue, entry);

        spin_unlock_bh(&queue->lock);
        return 0;

err_out_free_nskb:
        kfree_skb(nskb);
err_out_unlock:
        spin_unlock_bh(&queue->lock);
        if (failopen)
                nf_reinject(entry, NF_ACCEPT);
err_out:
        return err;
}

static struct nf_queue_entry *
nf_queue_entry_dup(struct nf_queue_entry *e)
{
        struct nf_queue_entry *entry = kmemdup(e, e->size, GFP_ATOMIC);
        if (entry)
                nf_queue_entry_get_refs(entry);
        return entry;
}

#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
/* When called from bridge netfilter, skb->data must point to MAC header
 * before calling skb_gso_segment(). Else, original MAC header is lost
 * and segmented skbs will be sent to wrong destination.
 */
static void nf_bridge_adjust_skb_data(struct sk_buff *skb)
{
        if (skb->nf_bridge)
                __skb_push(skb, skb->network_header - skb->mac_header);
}

static void nf_bridge_adjust_segmented_data(struct sk_buff *skb)
{
        if (skb->nf_bridge)
                __skb_pull(skb, skb->network_header - skb->mac_header);
}
#else
#define nf_bridge_adjust_skb_data(s) do {} while (0)
#define nf_bridge_adjust_segmented_data(s) do {} while (0)
#endif

static void free_entry(struct nf_queue_entry *entry)
{
        nf_queue_entry_release_refs(entry);
        kfree(entry);
}

static int
__nfqnl_enqueue_packet_gso(struct net *net, struct nfqnl_instance *queue,
                           struct sk_buff *skb, struct nf_queue_entry *entry)
{
        int ret = -ENOMEM;
        struct nf_queue_entry *entry_seg;

        nf_bridge_adjust_segmented_data(skb);

        if (skb->next == NULL) { /* last packet, no need to copy entry */
                struct sk_buff *gso_skb = entry->skb;
                entry->skb = skb;
                ret = __nfqnl_enqueue_packet(net, queue, entry);
                if (ret)
                        entry->skb = gso_skb;
                return ret;
        }

        skb->next = NULL;

        entry_seg = nf_queue_entry_dup(entry);
        if (entry_seg) {
                entry_seg->skb = skb;
                ret = __nfqnl_enqueue_packet(net, queue, entry_seg);
                if (ret)
                        free_entry(entry_seg);
        }
        return ret;
}

static int
nfqnl_enqueue_packet(struct nf_queue_entry *entry, unsigned int queuenum)
{
        unsigned int queued;
        struct nfqnl_instance *queue;
        struct sk_buff *skb, *segs;
        int err = -ENOBUFS;
        struct net *net = entry->state.net;
        struct nfnl_queue_net *q = nfnl_queue_pernet(net);

        /* rcu_read_lock()ed by nf_hook_slow() */
        queue = instance_lookup(q, queuenum);
        if (!queue)
                return -ESRCH;

        if (queue->copy_mode == NFQNL_COPY_NONE)
                return -EINVAL;

        skb = entry->skb;

        switch (entry->state.pf) {
        case NFPROTO_IPV4:
                skb->protocol = htons(ETH_P_IP);
                break;
        case NFPROTO_IPV6:
                skb->protocol = htons(ETH_P_IPV6);
                break;
        }

        if ((queue->flags & NFQA_CFG_F_GSO) || !skb_is_gso(skb))
                return __nfqnl_enqueue_packet(net, queue, entry);

        nf_bridge_adjust_skb_data(skb);
        segs = skb_gso_segment(skb, 0);
        /* Does not use PTR_ERR to limit the number of error codes that can be
         * returned by nf_queue.  For instance, callers rely on -ESRCH to
         * mean 'ignore this hook'.
         */
        if (IS_ERR_OR_NULL(segs))
                goto out_err;
        queued = 0;
        err = 0;
        do {
                struct sk_buff *nskb = segs->next;
                if (err == 0)
                        err = __nfqnl_enqueue_packet_gso(net, queue,
                                                        segs, entry);
                if (err == 0)
                        queued++;
                else
                        kfree_skb(segs);
                segs = nskb;
        } while (segs);

        if (queued) {
                if (err) /* some segments are already queued */
                        free_entry(entry);
                kfree_skb(skb);
                return 0;
        }
 out_err:
        nf_bridge_adjust_segmented_data(skb);
        return err;
}

static int
nfqnl_mangle(void *data, int data_len, struct nf_queue_entry *e, int diff)
{
        struct sk_buff *nskb;

        if (diff < 0) {
                if (pskb_trim(e->skb, data_len))
                        return -ENOMEM;
        } else if (diff > 0) {
                if (data_len > 0xFFFF)
                        return -EINVAL;
                if (diff > skb_tailroom(e->skb)) {
                        nskb = skb_copy_expand(e->skb, skb_headroom(e->skb),
                                               diff, GFP_ATOMIC);
                        if (!nskb) {
                                printk(KERN_WARNING "nf_queue: OOM "
                                      "in mangle, dropping packet\n");
                                return -ENOMEM;
                        }
                        kfree_skb(e->skb);
                        e->skb = nskb;
                }
                skb_put(e->skb, diff);
        }
        if (!skb_make_writable(e->skb, data_len))
                return -ENOMEM;
        skb_copy_to_linear_data(e->skb, data, data_len);
        e->skb->ip_summed = CHECKSUM_NONE;
        return 0;
}

static int
nfqnl_set_mode(struct nfqnl_instance *queue,
               unsigned char mode, unsigned int range)
{
        int status = 0;

        spin_lock_bh(&queue->lock);
        switch (mode) {
        case NFQNL_COPY_NONE:
        case NFQNL_COPY_META:
                queue->copy_mode = mode;
                queue->copy_range = 0;
                break;

        case NFQNL_COPY_PACKET:
                queue->copy_mode = mode;
                if (range == 0 || range > NFQNL_MAX_COPY_RANGE)
                        queue->copy_range = NFQNL_MAX_COPY_RANGE;
                else
                        queue->copy_range = range;
                break;

        default:
                status = -EINVAL;

        }
        spin_unlock_bh(&queue->lock);

        return status;
}

static int
dev_cmp(struct nf_queue_entry *entry, unsigned long ifindex)
{
        if (entry->state.in)
                if (entry->state.in->ifindex == ifindex)
                        return 1;
        if (entry->state.out)
                if (entry->state.out->ifindex == ifindex)
                        return 1;
#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
        if (entry->skb->nf_bridge) {
                int physinif, physoutif;

                physinif = nf_bridge_get_physinif(entry->skb);
                physoutif = nf_bridge_get_physoutif(entry->skb);

                if (physinif == ifindex || physoutif == ifindex)
                        return 1;
        }
#endif
        return 0;
}

/* drop all packets with either indev or outdev == ifindex from all queue
 * instances */
static void
nfqnl_dev_drop(struct net *net, int ifindex)
{
        int i;
        struct nfnl_queue_net *q = nfnl_queue_pernet(net);

        rcu_read_lock();

        for (i = 0; i < INSTANCE_BUCKETS; i++) {
                struct nfqnl_instance *inst;
                struct hlist_head *head = &q->instance_table[i];

                hlist_for_each_entry_rcu(inst, head, hlist)
                        nfqnl_flush(inst, dev_cmp, ifindex);
        }

        rcu_read_unlock();
}

static int
nfqnl_rcv_dev_event(struct notifier_block *this,
                    unsigned long event, void *ptr)
{
        struct net_device *dev = netdev_notifier_info_to_dev(ptr);

        /* Drop any packets associated with the downed device */
        if (event == NETDEV_DOWN)
                nfqnl_dev_drop(dev_net(dev), dev->ifindex);
        return NOTIFY_DONE;
}

static struct notifier_block nfqnl_dev_notifier = {
        .notifier_call  = nfqnl_rcv_dev_event,
};

static int nf_hook_cmp(struct nf_queue_entry *entry, unsigned long ops_ptr)
{
        return entry->elem == (struct nf_hook_ops *)ops_ptr;
}

static void nfqnl_nf_hook_drop(struct net *net, struct nf_hook_ops *hook)
{
        struct nfnl_queue_net *q = nfnl_queue_pernet(net);
        int i;

        rcu_read_lock();
        for (i = 0; i < INSTANCE_BUCKETS; i++) {
                struct nfqnl_instance *inst;
                struct hlist_head *head = &q->instance_table[i];

                hlist_for_each_entry_rcu(inst, head, hlist)
                        nfqnl_flush(inst, nf_hook_cmp, (unsigned long)hook);
        }
        rcu_read_unlock();
}

static int
nfqnl_rcv_nl_event(struct notifier_block *this,
                   unsigned long event, void *ptr)
{
        struct netlink_notify *n = ptr;
        struct nfnl_queue_net *q = nfnl_queue_pernet(n->net);

        if (event == NETLINK_URELEASE && n->protocol == NETLINK_NETFILTER) {
                int i;

                /* destroy all instances for this portid */
                spin_lock(&q->instances_lock);
                for (i = 0; i < INSTANCE_BUCKETS; i++) {
                        struct hlist_node *t2;
                        struct nfqnl_instance *inst;
                        struct hlist_head *head = &q->instance_table[i];

                        hlist_for_each_entry_safe(inst, t2, head, hlist) {
                                if (n->portid == inst->peer_portid)
                                        __instance_destroy(inst);
                        }
                }
                spin_unlock(&q->instances_lock);
        }
        return NOTIFY_DONE;
}

static struct notifier_block nfqnl_rtnl_notifier = {
        .notifier_call  = nfqnl_rcv_nl_event,
};

static const struct nla_policy nfqa_verdict_policy[NFQA_MAX+1] = {
        [NFQA_VERDICT_HDR]      = { .len = sizeof(struct nfqnl_msg_verdict_hdr) },
        [NFQA_MARK]             = { .type = NLA_U32 },
        [NFQA_PAYLOAD]          = { .type = NLA_UNSPEC },
        [NFQA_CT]               = { .type = NLA_UNSPEC },
        [NFQA_EXP]              = { .type = NLA_UNSPEC },
};

static const struct nla_policy nfqa_verdict_batch_policy[NFQA_MAX+1] = {
        [NFQA_VERDICT_HDR]      = { .len = sizeof(struct nfqnl_msg_verdict_hdr) },
        [NFQA_MARK]             = { .type = NLA_U32 },
};

static struct nfqnl_instance *
verdict_instance_lookup(struct nfnl_queue_net *q, u16 queue_num, u32 nlportid)
{
        struct nfqnl_instance *queue;

        queue = instance_lookup(q, queue_num);
        if (!queue)
                return ERR_PTR(-ENODEV);

        if (queue->peer_portid != nlportid)
                return ERR_PTR(-EPERM);

        return queue;
}

static struct nfqnl_msg_verdict_hdr*
verdicthdr_get(const struct nlattr * const nfqa[])
{
        struct nfqnl_msg_verdict_hdr *vhdr;
        unsigned int verdict;

        if (!nfqa[NFQA_VERDICT_HDR])
                return NULL;

        vhdr = nla_data(nfqa[NFQA_VERDICT_HDR]);
        verdict = ntohl(vhdr->verdict) & NF_VERDICT_MASK;
        if (verdict > NF_MAX_VERDICT || verdict == NF_STOLEN)
                return NULL;
        return vhdr;
}

static int nfq_id_after(unsigned int id, unsigned int max)
{
        return (int)(id - max) > 0;
}

static int nfqnl_recv_verdict_batch(struct net *net, struct sock *ctnl,
                                    struct sk_buff *skb,
                                    const struct nlmsghdr *nlh,
                                    const struct nlattr * const nfqa[])
{
        struct nfgenmsg *nfmsg = nlmsg_data(nlh);
        struct nf_queue_entry *entry, *tmp;
        unsigned int verdict, maxid;
        struct nfqnl_msg_verdict_hdr *vhdr;
        struct nfqnl_instance *queue;
        LIST_HEAD(batch_list);
        u16 queue_num = ntohs(nfmsg->res_id);
        struct nfnl_queue_net *q = nfnl_queue_pernet(net);

        queue = verdict_instance_lookup(q, queue_num,
                                        NETLINK_CB(skb).portid);
        if (IS_ERR(queue))
                return PTR_ERR(queue);

        vhdr = verdicthdr_get(nfqa);
        if (!vhdr)
                return -EINVAL;

        verdict = ntohl(vhdr->verdict);
        maxid = ntohl(vhdr->id);

        spin_lock_bh(&queue->lock);

        list_for_each_entry_safe(entry, tmp, &queue->queue_list, list) {
                if (nfq_id_after(entry->id, maxid))
                        break;
                __dequeue_entry(queue, entry);
                list_add_tail(&entry->list, &batch_list);
        }

        spin_unlock_bh(&queue->lock);

        if (list_empty(&batch_list))
                return -ENOENT;

        list_for_each_entry_safe(entry, tmp, &batch_list, list) {
                if (nfqa[NFQA_MARK])
                        entry->skb->mark = ntohl(nla_get_be32(nfqa[NFQA_MARK]));
                nf_reinject(entry, verdict);
        }
        return 0;
}

static struct nf_conn *nfqnl_ct_parse(struct nfnl_ct_hook *nfnl_ct,
                                      const struct nlmsghdr *nlh,
                                      const struct nlattr * const nfqa[],
                                      struct nf_queue_entry *entry,
                                      enum ip_conntrack_info *ctinfo)
{
        struct nf_conn *ct;

        ct = nfnl_ct->get_ct(entry->skb, ctinfo);
        if (ct == NULL)
                return NULL;

        if (nfnl_ct->parse(nfqa[NFQA_CT], ct) < 0)
                return NULL;

        if (nfqa[NFQA_EXP])
                nfnl_ct->attach_expect(nfqa[NFQA_EXP], ct,
                                      NETLINK_CB(entry->skb).portid,
                                      nlmsg_report(nlh));
        return ct;
}

static int nfqnl_recv_verdict(struct net *net, struct sock *ctnl,
                              struct sk_buff *skb,
                              const struct nlmsghdr *nlh,
                              const struct nlattr * const nfqa[])
{
        struct nfgenmsg *nfmsg = nlmsg_data(nlh);
        u_int16_t queue_num = ntohs(nfmsg->res_id);
        struct nfqnl_msg_verdict_hdr *vhdr;
        struct nfqnl_instance *queue;
        unsigned int verdict;
        struct nf_queue_entry *entry;
        enum ip_conntrack_info uninitialized_var(ctinfo);
        struct nfnl_ct_hook *nfnl_ct;
        struct nf_conn *ct = NULL;
        struct nfnl_queue_net *q = nfnl_queue_pernet(net);

        queue = instance_lookup(q, queue_num);
        if (!queue)
                queue = verdict_instance_lookup(q, queue_num,
                                                NETLINK_CB(skb).portid);
        if (IS_ERR(queue))
                return PTR_ERR(queue);

        vhdr = verdicthdr_get(nfqa);
        if (!vhdr)
                return -EINVAL;

        verdict = ntohl(vhdr->verdict);

        entry = find_dequeue_entry(queue, ntohl(vhdr->id));
        if (entry == NULL)
                return -ENOENT;

        /* rcu lock already held from nfnl->call_rcu. */
        nfnl_ct = rcu_dereference(nfnl_ct_hook);

        if (nfqa[NFQA_CT]) {
                if (nfnl_ct != NULL)
                        ct = nfqnl_ct_parse(nfnl_ct, nlh, nfqa, entry, &ctinfo);
        }

        if (nfqa[NFQA_PAYLOAD]) {
                u16 payload_len = nla_len(nfqa[NFQA_PAYLOAD]);
                int diff = payload_len - entry->skb->len;

                if (nfqnl_mangle(nla_data(nfqa[NFQA_PAYLOAD]),
                                 payload_len, entry, diff) < 0)
                        verdict = NF_DROP;

                if (ct && diff)
                        nfnl_ct->seq_adjust(entry->skb, ct, ctinfo, diff);
        }

        if (nfqa[NFQA_MARK])
                entry->skb->mark = ntohl(nla_get_be32(nfqa[NFQA_MARK]));

        nf_reinject(entry, verdict);
        return 0;
}

static int nfqnl_recv_unsupp(struct net *net, struct sock *ctnl,
                             struct sk_buff *skb, const struct nlmsghdr *nlh,
                             const struct nlattr * const nfqa[])
{
        return -ENOTSUPP;
}

static const struct nla_policy nfqa_cfg_policy[NFQA_CFG_MAX+1] = {
        [NFQA_CFG_CMD]          = { .len = sizeof(struct nfqnl_msg_config_cmd) },
        [NFQA_CFG_PARAMS]       = { .len = sizeof(struct nfqnl_msg_config_params) },
};

static const struct nf_queue_handler nfqh = {
        .outfn          = &nfqnl_enqueue_packet,
        .nf_hook_drop   = &nfqnl_nf_hook_drop,
};

static int nfqnl_recv_config(struct net *net, struct sock *ctnl,
                             struct sk_buff *skb, const struct nlmsghdr *nlh,
                             const struct nlattr * const nfqa[])
{
        struct nfgenmsg *nfmsg = nlmsg_data(nlh);
        u_int16_t queue_num = ntohs(nfmsg->res_id);
        struct nfqnl_instance *queue;
        struct nfqnl_msg_config_cmd *cmd = NULL;
        struct nfnl_queue_net *q = nfnl_queue_pernet(net);
        __u32 flags = 0, mask = 0;
        int ret = 0;

        if (nfqa[NFQA_CFG_CMD]) {
                cmd = nla_data(nfqa[NFQA_CFG_CMD]);

                /* Obsolete commands without queue context */
                switch (cmd->command) {
                case NFQNL_CFG_CMD_PF_BIND: return 0;
                case NFQNL_CFG_CMD_PF_UNBIND: return 0;
                }
        }

        /* Check if we support these flags in first place, dependencies should
         * be there too not to break atomicity.
         */
        if (nfqa[NFQA_CFG_FLAGS]) {
                if (!nfqa[NFQA_CFG_MASK]) {
                        /* A mask is needed to specify which flags are being
                         * changed.
                         */
                        return -EINVAL;
                }

                flags = ntohl(nla_get_be32(nfqa[NFQA_CFG_FLAGS]));
                mask = ntohl(nla_get_be32(nfqa[NFQA_CFG_MASK]));

                if (flags >= NFQA_CFG_F_MAX)
                        return -EOPNOTSUPP;

#if !IS_ENABLED(CONFIG_NETWORK_SECMARK)
                if (flags & mask & NFQA_CFG_F_SECCTX)
                        return -EOPNOTSUPP;
#endif
                if ((flags & mask & NFQA_CFG_F_CONNTRACK) &&
                    !rcu_access_pointer(nfnl_ct_hook)) {
#ifdef CONFIG_MODULES
                        nfnl_unlock(NFNL_SUBSYS_QUEUE);
                        request_module("ip_conntrack_netlink");
                        nfnl_lock(NFNL_SUBSYS_QUEUE);
                        if (rcu_access_pointer(nfnl_ct_hook))
                                return -EAGAIN;
#endif
                        return -EOPNOTSUPP;
                }
        }

        rcu_read_lock();
        queue = instance_lookup(q, queue_num);
        if (queue && queue->peer_portid != NETLINK_CB(skb).portid) {
                ret = -EPERM;
                goto err_out_unlock;
        }

        if (cmd != NULL) {
                switch (cmd->command) {
                case NFQNL_CFG_CMD_BIND:
                        if (queue) {
                                ret = -EBUSY;
                                goto err_out_unlock;
                        }
                        queue = instance_create(q, queue_num,
                                                NETLINK_CB(skb).portid);
                        if (IS_ERR(queue)) {
                                ret = PTR_ERR(queue);
                                goto err_out_unlock;
                        }
                        break;
                case NFQNL_CFG_CMD_UNBIND:
                        if (!queue) {
                                ret = -ENODEV;
                                goto err_out_unlock;
                        }
                        instance_destroy(q, queue);
                        goto err_out_unlock;
                case NFQNL_CFG_CMD_PF_BIND:
                case NFQNL_CFG_CMD_PF_UNBIND:
                        break;
                default:
                        ret = -ENOTSUPP;
                        goto err_out_unlock;
                }
        }

        if (!queue) {
                ret = -ENODEV;
                goto err_out_unlock;
        }

        if (nfqa[NFQA_CFG_PARAMS]) {
                struct nfqnl_msg_config_params *params =
                        nla_data(nfqa[NFQA_CFG_PARAMS]);

                nfqnl_set_mode(queue, params->copy_mode,
                                ntohl(params->copy_range));
        }

        if (nfqa[NFQA_CFG_QUEUE_MAXLEN]) {
                __be32 *queue_maxlen = nla_data(nfqa[NFQA_CFG_QUEUE_MAXLEN]);

                spin_lock_bh(&queue->lock);
                queue->queue_maxlen = ntohl(*queue_maxlen);
                spin_unlock_bh(&queue->lock);
        }

        if (nfqa[NFQA_CFG_FLAGS]) {
                spin_lock_bh(&queue->lock);
                queue->flags &= ~mask;
                queue->flags |= flags & mask;
                spin_unlock_bh(&queue->lock);
        }

err_out_unlock:
        rcu_read_unlock();
        return ret;
}

static const struct nfnl_callback nfqnl_cb[NFQNL_MSG_MAX] = {
        [NFQNL_MSG_PACKET]      = { .call_rcu = nfqnl_recv_unsupp,
                                    .attr_count = NFQA_MAX, },
        [NFQNL_MSG_VERDICT]     = { .call_rcu = nfqnl_recv_verdict,
                                    .attr_count = NFQA_MAX,
                                    .policy = nfqa_verdict_policy },
        [NFQNL_MSG_CONFIG]      = { .call = nfqnl_recv_config,
                                    .attr_count = NFQA_CFG_MAX,
                                    .policy = nfqa_cfg_policy },
        [NFQNL_MSG_VERDICT_BATCH]={ .call_rcu = nfqnl_recv_verdict_batch,
                                    .attr_count = NFQA_MAX,
                                    .policy = nfqa_verdict_batch_policy },
};

static const struct nfnetlink_subsystem nfqnl_subsys = {
        .name           = "nf_queue",
        .subsys_id      = NFNL_SUBSYS_QUEUE,
        .cb_count       = NFQNL_MSG_MAX,
        .cb             = nfqnl_cb,
};

#ifdef CONFIG_PROC_FS
struct iter_state {
        struct seq_net_private p;
        unsigned int bucket;
};

static struct hlist_node *get_first(struct seq_file *seq)
{
        struct iter_state *st = seq->private;
        struct net *net;
        struct nfnl_queue_net *q;

        if (!st)
                return NULL;

        net = seq_file_net(seq);
        q = nfnl_queue_pernet(net);
        for (st->bucket = 0; st->bucket < INSTANCE_BUCKETS; st->bucket++) {
                if (!hlist_empty(&q->instance_table[st->bucket]))
                        return q->instance_table[st->bucket].first;
        }
        return NULL;
}

static struct hlist_node *get_next(struct seq_file *seq, struct hlist_node *h)
{
        struct iter_state *st = seq->private;
        struct net *net = seq_file_net(seq);

        h = h->next;
        while (!h) {
                struct nfnl_queue_net *q;

                if (++st->bucket >= INSTANCE_BUCKETS)
                        return NULL;

                q = nfnl_queue_pernet(net);
                h = q->instance_table[st->bucket].first;
        }
        return h;
}

static struct hlist_node *get_idx(struct seq_file *seq, loff_t pos)
{
        struct hlist_node *head;
        head = get_first(seq);

        if (head)
                while (pos && (head = get_next(seq, head)))
                        pos--;
        return pos ? NULL : head;
}

static void *seq_start(struct seq_file *s, loff_t *pos)
        __acquires(nfnl_queue_pernet(seq_file_net(s))->instances_lock)
{
        spin_lock(&nfnl_queue_pernet(seq_file_net(s))->instances_lock);
        return get_idx(s, *pos);
}

static void *seq_next(struct seq_file *s, void *v, loff_t *pos)
{
        (*pos)++;
        return get_next(s, v);
}

static void seq_stop(struct seq_file *s, void *v)
        __releases(nfnl_queue_pernet(seq_file_net(s))->instances_lock)
{
        spin_unlock(&nfnl_queue_pernet(seq_file_net(s))->instances_lock);
}

static int seq_show(struct seq_file *s, void *v)
{
        const struct nfqnl_instance *inst = v;

        seq_printf(s, "%5u %6u %5u %1u %5u %5u %5u %8u %2d\n",
                   inst->queue_num,
                   inst->peer_portid, inst->queue_total,
                   inst->copy_mode, inst->copy_range,
                   inst->queue_dropped, inst->queue_user_dropped,
                   inst->id_sequence, 1);
        return 0;
}

static const struct seq_operations nfqnl_seq_ops = {
        .start  = seq_start,
        .next   = seq_next,
        .stop   = seq_stop,
        .show   = seq_show,
};

static int nfqnl_open(struct inode *inode, struct file *file)
{
        return seq_open_net(inode, file, &nfqnl_seq_ops,
                        sizeof(struct iter_state));
}

static const struct file_operations nfqnl_file_ops = {
        .owner   = THIS_MODULE,
        .open    = nfqnl_open,
        .read    = seq_read,
        .llseek  = seq_lseek,
        .release = seq_release_net,
};

#endif /* PROC_FS */

static int __net_init nfnl_queue_net_init(struct net *net)
{
        unsigned int i;
        struct nfnl_queue_net *q = nfnl_queue_pernet(net);

        for (i = 0; i < INSTANCE_BUCKETS; i++)
                INIT_HLIST_HEAD(&q->instance_table[i]);

        spin_lock_init(&q->instances_lock);

#ifdef CONFIG_PROC_FS
        if (!proc_create("nfnetlink_queue", 0440,
                         net->nf.proc_netfilter, &nfqnl_file_ops))
                return -ENOMEM;
#endif
        return 0;
}

static void __net_exit nfnl_queue_net_exit(struct net *net)
{
#ifdef CONFIG_PROC_FS
        remove_proc_entry("nfnetlink_queue", net->nf.proc_netfilter);
#endif
}

static struct pernet_operations nfnl_queue_net_ops = {
        .init   = nfnl_queue_net_init,
        .exit   = nfnl_queue_net_exit,
        .id     = &nfnl_queue_net_id,
        .size   = sizeof(struct nfnl_queue_net),
};

static int __init nfnetlink_queue_init(void)
{
        int status;

        status = register_pernet_subsys(&nfnl_queue_net_ops);
        if (status < 0) {
                pr_err("nf_queue: failed to register pernet ops\n");
                goto out;
        }

        netlink_register_notifier(&nfqnl_rtnl_notifier);
        status = nfnetlink_subsys_register(&nfqnl_subsys);
        if (status < 0) {
                pr_err("nf_queue: failed to create netlink socket\n");
                goto cleanup_netlink_notifier;
        }

        register_netdevice_notifier(&nfqnl_dev_notifier);
        nf_register_queue_handler(&nfqh);
        return status;

cleanup_netlink_notifier:
        netlink_unregister_notifier(&nfqnl_rtnl_notifier);
        unregister_pernet_subsys(&nfnl_queue_net_ops);
out:
        return status;
}

static void __exit nfnetlink_queue_fini(void)
{
        nf_unregister_queue_handler();
        unregister_netdevice_notifier(&nfqnl_dev_notifier);
        nfnetlink_subsys_unregister(&nfqnl_subsys);
        netlink_unregister_notifier(&nfqnl_rtnl_notifier);
        unregister_pernet_subsys(&nfnl_queue_net_ops);

        rcu_barrier(); /* Wait for completion of call_rcu()'s */
}

MODULE_DESCRIPTION("netfilter packet queue handler");
MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
MODULE_LICENSE("GPL");
MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_QUEUE);

module_init(nfnetlink_queue_init);
module_exit(nfnetlink_queue_fini);