net/sched: sch_frag: add generic packet fragment support.
Currently kernel tc subsystem can do conntrack in cat_ct. But when several fragment packets go through the act_ct, function tcf_ct_handle_fragments will defrag the packets to a big one. But the last action will redirect mirred to a device which maybe lead the reassembly big packet over the mtu of target device. This patch add support for a xmit hook to mirred, that gets executed before xmiting the packet. Then, when act_ct gets loaded, it configs that hook. The frag xmit hook maybe reused by other modules. Signed-off-by: wenxu <wenxu@ucloud.cn> Acked-by: Cong Wang <cong.wang@bytedance.com> Acked-by: Jamal Hadi Salim <jhs@mojatatu.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
wenxu
Jakub Kicinski
parent
fa6d639930
commit
c129412f74
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@ -239,6 +239,12 @@ int tcf_action_check_ctrlact(int action, struct tcf_proto *tp,
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struct netlink_ext_ack *newchain);
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struct tcf_chain *tcf_action_set_ctrlact(struct tc_action *a, int action,
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struct tcf_chain *newchain);
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#ifdef CONFIG_INET
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DECLARE_STATIC_KEY_FALSE(tcf_frag_xmit_count);
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#endif
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int tcf_dev_queue_xmit(struct sk_buff *skb, int (*xmit)(struct sk_buff *skb));
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#endif /* CONFIG_NET_CLS_ACT */
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static inline void tcf_action_stats_update(struct tc_action *a, u64 bytes,
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@ -1281,4 +1281,6 @@ void mini_qdisc_pair_init(struct mini_Qdisc_pair *miniqp, struct Qdisc *qdisc,
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void mini_qdisc_pair_block_init(struct mini_Qdisc_pair *miniqp,
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struct tcf_block *block);
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int sch_frag_xmit_hook(struct sk_buff *skb, int (*xmit)(struct sk_buff *skb));
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#endif
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@ -5,6 +5,7 @@
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obj-y := sch_generic.o sch_mq.o
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obj-$(CONFIG_INET) += sch_frag.o
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obj-$(CONFIG_NET_SCHED) += sch_api.o sch_blackhole.o
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obj-$(CONFIG_NET_CLS) += cls_api.o
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obj-$(CONFIG_NET_CLS_ACT) += act_api.o
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@ -22,6 +22,22 @@
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#include <net/act_api.h>
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#include <net/netlink.h>
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#ifdef CONFIG_INET
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DEFINE_STATIC_KEY_FALSE(tcf_frag_xmit_count);
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EXPORT_SYMBOL_GPL(tcf_frag_xmit_count);
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#endif
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int tcf_dev_queue_xmit(struct sk_buff *skb, int (*xmit)(struct sk_buff *skb))
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{
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#ifdef CONFIG_INET
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if (static_branch_unlikely(&tcf_frag_xmit_count))
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return sch_frag_xmit_hook(skb, xmit);
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#endif
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return xmit(skb);
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}
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EXPORT_SYMBOL_GPL(tcf_dev_queue_xmit);
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static void tcf_action_goto_chain_exec(const struct tc_action *a,
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struct tcf_result *res)
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{
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@ -1541,6 +1541,8 @@ static int __init ct_init_module(void)
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if (err)
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goto err_register;
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static_branch_inc(&tcf_frag_xmit_count);
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return 0;
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err_register:
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@ -1552,6 +1554,7 @@ static int __init ct_init_module(void)
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static void __exit ct_cleanup_module(void)
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{
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static_branch_dec(&tcf_frag_xmit_count);
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tcf_unregister_action(&act_ct_ops, &ct_net_ops);
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tcf_ct_flow_tables_uninit();
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destroy_workqueue(act_ct_wq);
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@ -210,7 +210,7 @@ static int tcf_mirred_forward(bool want_ingress, struct sk_buff *skb)
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int err;
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if (!want_ingress)
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err = dev_queue_xmit(skb);
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err = tcf_dev_queue_xmit(skb, dev_queue_xmit);
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else
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err = netif_receive_skb(skb);
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@ -0,0 +1,150 @@
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// SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB
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#include <net/netlink.h>
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#include <net/sch_generic.h>
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#include <net/dst.h>
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#include <net/ip.h>
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#include <net/ip6_fib.h>
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struct sch_frag_data {
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unsigned long dst;
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struct qdisc_skb_cb cb;
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__be16 inner_protocol;
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u16 vlan_tci;
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__be16 vlan_proto;
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unsigned int l2_len;
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u8 l2_data[VLAN_ETH_HLEN];
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int (*xmit)(struct sk_buff *skb);
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};
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static DEFINE_PER_CPU(struct sch_frag_data, sch_frag_data_storage);
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static int sch_frag_xmit(struct net *net, struct sock *sk, struct sk_buff *skb)
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{
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struct sch_frag_data *data = this_cpu_ptr(&sch_frag_data_storage);
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if (skb_cow_head(skb, data->l2_len) < 0) {
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kfree_skb(skb);
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return -ENOMEM;
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}
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__skb_dst_copy(skb, data->dst);
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*qdisc_skb_cb(skb) = data->cb;
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skb->inner_protocol = data->inner_protocol;
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if (data->vlan_tci & VLAN_CFI_MASK)
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__vlan_hwaccel_put_tag(skb, data->vlan_proto,
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data->vlan_tci & ~VLAN_CFI_MASK);
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else
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__vlan_hwaccel_clear_tag(skb);
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/* Reconstruct the MAC header. */
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skb_push(skb, data->l2_len);
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memcpy(skb->data, &data->l2_data, data->l2_len);
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skb_postpush_rcsum(skb, skb->data, data->l2_len);
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skb_reset_mac_header(skb);
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return data->xmit(skb);
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}
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static void sch_frag_prepare_frag(struct sk_buff *skb,
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int (*xmit)(struct sk_buff *skb))
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{
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unsigned int hlen = skb_network_offset(skb);
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struct sch_frag_data *data;
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data = this_cpu_ptr(&sch_frag_data_storage);
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data->dst = skb->_skb_refdst;
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data->cb = *qdisc_skb_cb(skb);
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data->xmit = xmit;
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data->inner_protocol = skb->inner_protocol;
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if (skb_vlan_tag_present(skb))
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data->vlan_tci = skb_vlan_tag_get(skb) | VLAN_CFI_MASK;
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else
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data->vlan_tci = 0;
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data->vlan_proto = skb->vlan_proto;
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data->l2_len = hlen;
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memcpy(&data->l2_data, skb->data, hlen);
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memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
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skb_pull(skb, hlen);
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}
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static unsigned int
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sch_frag_dst_get_mtu(const struct dst_entry *dst)
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{
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return dst->dev->mtu;
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}
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static struct dst_ops sch_frag_dst_ops = {
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.family = AF_UNSPEC,
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.mtu = sch_frag_dst_get_mtu,
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};
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static int sch_fragment(struct net *net, struct sk_buff *skb,
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u16 mru, int (*xmit)(struct sk_buff *skb))
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{
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int ret = -1;
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if (skb_network_offset(skb) > VLAN_ETH_HLEN) {
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net_warn_ratelimited("L2 header too long to fragment\n");
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goto err;
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}
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if (skb_protocol(skb, true) == htons(ETH_P_IP)) {
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struct dst_entry sch_frag_dst;
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unsigned long orig_dst;
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sch_frag_prepare_frag(skb, xmit);
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dst_init(&sch_frag_dst, &sch_frag_dst_ops, NULL, 1,
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DST_OBSOLETE_NONE, DST_NOCOUNT);
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sch_frag_dst.dev = skb->dev;
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orig_dst = skb->_skb_refdst;
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skb_dst_set_noref(skb, &sch_frag_dst);
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IPCB(skb)->frag_max_size = mru;
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ret = ip_do_fragment(net, skb->sk, skb, sch_frag_xmit);
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refdst_drop(orig_dst);
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} else if (skb_protocol(skb, true) == htons(ETH_P_IPV6)) {
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unsigned long orig_dst;
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struct rt6_info sch_frag_rt;
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sch_frag_prepare_frag(skb, xmit);
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memset(&sch_frag_rt, 0, sizeof(sch_frag_rt));
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dst_init(&sch_frag_rt.dst, &sch_frag_dst_ops, NULL, 1,
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DST_OBSOLETE_NONE, DST_NOCOUNT);
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sch_frag_rt.dst.dev = skb->dev;
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orig_dst = skb->_skb_refdst;
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skb_dst_set_noref(skb, &sch_frag_rt.dst);
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IP6CB(skb)->frag_max_size = mru;
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ret = ipv6_stub->ipv6_fragment(net, skb->sk, skb,
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sch_frag_xmit);
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refdst_drop(orig_dst);
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} else {
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net_warn_ratelimited("Fail frag %s: eth=%x, MRU=%d, MTU=%d\n",
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netdev_name(skb->dev),
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ntohs(skb_protocol(skb, true)), mru,
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skb->dev->mtu);
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goto err;
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}
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return ret;
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err:
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kfree_skb(skb);
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return ret;
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}
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int sch_frag_xmit_hook(struct sk_buff *skb, int (*xmit)(struct sk_buff *skb))
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{
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u16 mru = qdisc_skb_cb(skb)->mru;
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int err;
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if (mru && skb->len > mru + skb->dev->hard_header_len)
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err = sch_fragment(dev_net(skb->dev), skb, mru, xmit);
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else
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err = xmit(skb);
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return err;
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}
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EXPORT_SYMBOL_GPL(sch_frag_xmit_hook);
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