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netfilter: move skb_gso_segment into nfnetlink_queue module
skb_gso_segment is expensive, so it would be nice if we could avoid it in the future. However, userspace needs to be prepared to receive larger-than-mtu-packets (which will also have incorrect l3/l4 checksums), so we cannot simply remove it. The plan is to add a per-queue feature flag that userspace can set when binding the queue. The problem is that in nf_queue, we only have a queue number, not the queue context/configuration settings. This patch should have no impact other than the skb_gso_segment call now being in a function that has access to the queue config data. A new size attribute in nf_queue_entry is needed so nfnetlink_queue can duplicate the entry of the gso skb when segmenting the skb while also copying the route key. The follow up patch adds switch to disable skb_gso_segment when queue config says so. Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Florian Westphal
Pablo Neira Ayuso
parent
4bd60443cc
commit
a5fedd43d5
@ -9,10 +9,13 @@ struct nf_queue_entry {
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struct nf_hook_ops *elem;
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u_int8_t pf;
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u16 size; /* sizeof(entry) + saved route keys */
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unsigned int hook;
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struct net_device *indev;
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struct net_device *outdev;
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int (*okfn)(struct sk_buff *);
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/* extra space to store route keys */
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};
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#define nf_queue_entry_reroute(x) ((void *)x + sizeof(struct nf_queue_entry))
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@ -27,4 +30,7 @@ void nf_register_queue_handler(const struct nf_queue_handler *qh);
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void nf_unregister_queue_handler(void);
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extern void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict);
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bool nf_queue_entry_get_refs(struct nf_queue_entry *entry);
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void nf_queue_entry_release_refs(struct nf_queue_entry *entry);
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#endif /* _NF_QUEUE_H */
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@ -45,7 +45,7 @@ void nf_unregister_queue_handler(void)
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}
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EXPORT_SYMBOL(nf_unregister_queue_handler);
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static void nf_queue_entry_release_refs(struct nf_queue_entry *entry)
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void nf_queue_entry_release_refs(struct nf_queue_entry *entry)
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{
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/* Release those devices we held, or Alexey will kill me. */
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if (entry->indev)
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@ -65,9 +65,10 @@ static void nf_queue_entry_release_refs(struct nf_queue_entry *entry)
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/* Drop reference to owner of hook which queued us. */
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module_put(entry->elem->owner);
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}
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EXPORT_SYMBOL_GPL(nf_queue_entry_release_refs);
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/* Bump dev refs so they don't vanish while packet is out */
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static bool nf_queue_entry_get_refs(struct nf_queue_entry *entry)
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bool nf_queue_entry_get_refs(struct nf_queue_entry *entry)
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{
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if (!try_module_get(entry->elem->owner))
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return false;
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@ -92,12 +93,13 @@ static bool nf_queue_entry_get_refs(struct nf_queue_entry *entry)
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return true;
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}
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EXPORT_SYMBOL_GPL(nf_queue_entry_get_refs);
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/*
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* Any packet that leaves via this function must come back
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* through nf_reinject().
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*/
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static int __nf_queue(struct sk_buff *skb,
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int nf_queue(struct sk_buff *skb,
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struct nf_hook_ops *elem,
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u_int8_t pf, unsigned int hook,
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struct net_device *indev,
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@ -137,6 +139,7 @@ static int __nf_queue(struct sk_buff *skb,
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.indev = indev,
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.outdev = outdev,
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.okfn = okfn,
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.size = sizeof(*entry) + afinfo->route_key_size,
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};
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if (!nf_queue_entry_get_refs(entry)) {
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@ -163,87 +166,6 @@ err:
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return status;
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}
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#ifdef CONFIG_BRIDGE_NETFILTER
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/* When called from bridge netfilter, skb->data must point to MAC header
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* before calling skb_gso_segment(). Else, original MAC header is lost
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* and segmented skbs will be sent to wrong destination.
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*/
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static void nf_bridge_adjust_skb_data(struct sk_buff *skb)
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{
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if (skb->nf_bridge)
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__skb_push(skb, skb->network_header - skb->mac_header);
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}
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static void nf_bridge_adjust_segmented_data(struct sk_buff *skb)
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{
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if (skb->nf_bridge)
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__skb_pull(skb, skb->network_header - skb->mac_header);
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}
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#else
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#define nf_bridge_adjust_skb_data(s) do {} while (0)
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#define nf_bridge_adjust_segmented_data(s) do {} while (0)
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#endif
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int nf_queue(struct sk_buff *skb,
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struct nf_hook_ops *elem,
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u_int8_t pf, unsigned int hook,
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struct net_device *indev,
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struct net_device *outdev,
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int (*okfn)(struct sk_buff *),
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unsigned int queuenum)
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{
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struct sk_buff *segs;
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int err = -EINVAL;
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unsigned int queued;
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if (!skb_is_gso(skb))
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return __nf_queue(skb, elem, pf, hook, indev, outdev, okfn,
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queuenum);
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switch (pf) {
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case NFPROTO_IPV4:
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skb->protocol = htons(ETH_P_IP);
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break;
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case NFPROTO_IPV6:
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skb->protocol = htons(ETH_P_IPV6);
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break;
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}
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nf_bridge_adjust_skb_data(skb);
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segs = skb_gso_segment(skb, 0);
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/* Does not use PTR_ERR to limit the number of error codes that can be
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* returned by nf_queue. For instance, callers rely on -ECANCELED to mean
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* 'ignore this hook'.
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*/
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if (IS_ERR(segs))
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goto out_err;
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queued = 0;
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err = 0;
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do {
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struct sk_buff *nskb = segs->next;
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segs->next = NULL;
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if (err == 0) {
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nf_bridge_adjust_segmented_data(segs);
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err = __nf_queue(segs, elem, pf, hook, indev,
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outdev, okfn, queuenum);
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}
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if (err == 0)
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queued++;
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else
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kfree_skb(segs);
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segs = nskb;
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} while (segs);
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if (queued) {
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kfree_skb(skb);
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return 0;
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}
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out_err:
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nf_bridge_adjust_segmented_data(skb);
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return err;
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}
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void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict)
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{
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struct sk_buff *skb = entry->skb;
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@ -283,9 +205,9 @@ void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict)
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local_bh_enable();
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break;
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case NF_QUEUE:
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err = __nf_queue(skb, elem, entry->pf, entry->hook,
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entry->indev, entry->outdev, entry->okfn,
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verdict >> NF_VERDICT_QBITS);
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err = nf_queue(skb, elem, entry->pf, entry->hook,
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entry->indev, entry->outdev, entry->okfn,
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verdict >> NF_VERDICT_QBITS);
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if (err < 0) {
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if (err == -ECANCELED)
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goto next_hook;
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@ -477,28 +477,13 @@ nla_put_failure:
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}
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static int
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nfqnl_enqueue_packet(struct nf_queue_entry *entry, unsigned int queuenum)
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__nfqnl_enqueue_packet(struct net *net, struct nfqnl_instance *queue,
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struct nf_queue_entry *entry)
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{
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struct sk_buff *nskb;
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struct nfqnl_instance *queue;
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int err = -ENOBUFS;
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__be32 *packet_id_ptr;
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int failopen = 0;
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struct net *net = dev_net(entry->indev ?
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entry->indev : entry->outdev);
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struct nfnl_queue_net *q = nfnl_queue_pernet(net);
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/* rcu_read_lock()ed by nf_hook_slow() */
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queue = instance_lookup(q, queuenum);
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if (!queue) {
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err = -ESRCH;
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goto err_out;
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}
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if (queue->copy_mode == NFQNL_COPY_NONE) {
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err = -EINVAL;
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goto err_out;
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}
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nskb = nfqnl_build_packet_message(queue, entry, &packet_id_ptr);
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if (nskb == NULL) {
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@ -547,6 +532,141 @@ err_out:
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return err;
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}
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static struct nf_queue_entry *
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nf_queue_entry_dup(struct nf_queue_entry *e)
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{
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struct nf_queue_entry *entry = kmemdup(e, e->size, GFP_ATOMIC);
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if (entry) {
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if (nf_queue_entry_get_refs(entry))
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return entry;
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kfree(entry);
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}
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return NULL;
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}
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#ifdef CONFIG_BRIDGE_NETFILTER
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/* When called from bridge netfilter, skb->data must point to MAC header
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* before calling skb_gso_segment(). Else, original MAC header is lost
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* and segmented skbs will be sent to wrong destination.
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*/
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static void nf_bridge_adjust_skb_data(struct sk_buff *skb)
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{
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if (skb->nf_bridge)
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__skb_push(skb, skb->network_header - skb->mac_header);
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}
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static void nf_bridge_adjust_segmented_data(struct sk_buff *skb)
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{
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if (skb->nf_bridge)
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__skb_pull(skb, skb->network_header - skb->mac_header);
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}
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#else
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#define nf_bridge_adjust_skb_data(s) do {} while (0)
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#define nf_bridge_adjust_segmented_data(s) do {} while (0)
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#endif
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static void free_entry(struct nf_queue_entry *entry)
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{
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nf_queue_entry_release_refs(entry);
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kfree(entry);
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}
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static int
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__nfqnl_enqueue_packet_gso(struct net *net, struct nfqnl_instance *queue,
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struct sk_buff *skb, struct nf_queue_entry *entry)
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{
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int ret = -ENOMEM;
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struct nf_queue_entry *entry_seg;
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nf_bridge_adjust_segmented_data(skb);
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if (skb->next == NULL) { /* last packet, no need to copy entry */
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struct sk_buff *gso_skb = entry->skb;
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entry->skb = skb;
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ret = __nfqnl_enqueue_packet(net, queue, entry);
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if (ret)
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entry->skb = gso_skb;
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return ret;
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}
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skb->next = NULL;
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entry_seg = nf_queue_entry_dup(entry);
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if (entry_seg) {
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entry_seg->skb = skb;
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ret = __nfqnl_enqueue_packet(net, queue, entry_seg);
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if (ret)
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free_entry(entry_seg);
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}
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return ret;
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}
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static int
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nfqnl_enqueue_packet(struct nf_queue_entry *entry, unsigned int queuenum)
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{
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unsigned int queued;
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struct nfqnl_instance *queue;
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struct sk_buff *skb, *segs;
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int err = -ENOBUFS;
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struct net *net = dev_net(entry->indev ?
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entry->indev : entry->outdev);
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struct nfnl_queue_net *q = nfnl_queue_pernet(net);
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/* rcu_read_lock()ed by nf_hook_slow() */
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queue = instance_lookup(q, queuenum);
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if (!queue)
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return -ESRCH;
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if (queue->copy_mode == NFQNL_COPY_NONE)
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return -EINVAL;
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if (!skb_is_gso(entry->skb))
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return __nfqnl_enqueue_packet(net, queue, entry);
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skb = entry->skb;
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switch (entry->pf) {
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case NFPROTO_IPV4:
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skb->protocol = htons(ETH_P_IP);
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break;
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case NFPROTO_IPV6:
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skb->protocol = htons(ETH_P_IPV6);
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break;
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}
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nf_bridge_adjust_skb_data(skb);
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segs = skb_gso_segment(skb, 0);
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/* Does not use PTR_ERR to limit the number of error codes that can be
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* returned by nf_queue. For instance, callers rely on -ECANCELED to
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* mean 'ignore this hook'.
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*/
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if (IS_ERR(segs))
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goto out_err;
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queued = 0;
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err = 0;
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do {
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struct sk_buff *nskb = segs->next;
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if (err == 0)
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err = __nfqnl_enqueue_packet_gso(net, queue,
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segs, entry);
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if (err == 0)
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queued++;
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else
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kfree_skb(segs);
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segs = nskb;
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} while (segs);
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if (queued) {
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if (err) /* some segments are already queued */
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free_entry(entry);
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kfree_skb(skb);
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return 0;
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}
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out_err:
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nf_bridge_adjust_segmented_data(skb);
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return err;
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}
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static int
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nfqnl_mangle(void *data, int data_len, struct nf_queue_entry *e, int diff)
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{
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