![Jason Wang](/assets/img/avatar_default.png)
We drop packet unconditionally when we fail to mirror it. This is not intended in some cases. Consdier for kvm guest, we may mirror the traffic of the bridge to a tap device used by a VM. When kernel fails to mirror the packet in conditions such as when qemu crashes or stop polling the tap, it's hard for the management software to detect such condition and clean the the mirroring before. This would lead all packets to the bridge to be dropped and break the netowrk of other virtual machines. To solve the issue, the patch does not drop packets when kernel fails to mirror it, and only drop the redirected packets. Signed-off-by: Jason Wang <jasowang@redhat.com> Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com> Signed-off-by: David S. Miller <davem@davemloft.net>
300 lines
6.8 KiB
C
300 lines
6.8 KiB
C
/*
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* net/sched/mirred.c packet mirroring and redirect actions
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* Authors: Jamal Hadi Salim (2002-4)
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*
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* TODO: Add ingress support (and socket redirect support)
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*
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*/
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <linux/string.h>
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#include <linux/errno.h>
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#include <linux/skbuff.h>
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#include <linux/rtnetlink.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/gfp.h>
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#include <net/net_namespace.h>
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#include <net/netlink.h>
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#include <net/pkt_sched.h>
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#include <linux/tc_act/tc_mirred.h>
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#include <net/tc_act/tc_mirred.h>
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#include <linux/if_arp.h>
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#define MIRRED_TAB_MASK 7
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static struct tcf_common *tcf_mirred_ht[MIRRED_TAB_MASK + 1];
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static u32 mirred_idx_gen;
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static DEFINE_RWLOCK(mirred_lock);
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static LIST_HEAD(mirred_list);
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static struct tcf_hashinfo mirred_hash_info = {
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.htab = tcf_mirred_ht,
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.hmask = MIRRED_TAB_MASK,
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.lock = &mirred_lock,
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};
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static int tcf_mirred_release(struct tcf_mirred *m, int bind)
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{
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if (m) {
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if (bind)
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m->tcf_bindcnt--;
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m->tcf_refcnt--;
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if (!m->tcf_bindcnt && m->tcf_refcnt <= 0) {
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list_del(&m->tcfm_list);
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if (m->tcfm_dev)
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dev_put(m->tcfm_dev);
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tcf_hash_destroy(&m->common, &mirred_hash_info);
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return 1;
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}
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}
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return 0;
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}
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static const struct nla_policy mirred_policy[TCA_MIRRED_MAX + 1] = {
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[TCA_MIRRED_PARMS] = { .len = sizeof(struct tc_mirred) },
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};
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static int tcf_mirred_init(struct nlattr *nla, struct nlattr *est,
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struct tc_action *a, int ovr, int bind)
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{
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struct nlattr *tb[TCA_MIRRED_MAX + 1];
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struct tc_mirred *parm;
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struct tcf_mirred *m;
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struct tcf_common *pc;
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struct net_device *dev;
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int ret, ok_push = 0;
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if (nla == NULL)
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return -EINVAL;
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ret = nla_parse_nested(tb, TCA_MIRRED_MAX, nla, mirred_policy);
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if (ret < 0)
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return ret;
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if (tb[TCA_MIRRED_PARMS] == NULL)
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return -EINVAL;
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parm = nla_data(tb[TCA_MIRRED_PARMS]);
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switch (parm->eaction) {
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case TCA_EGRESS_MIRROR:
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case TCA_EGRESS_REDIR:
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break;
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default:
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return -EINVAL;
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}
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if (parm->ifindex) {
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dev = __dev_get_by_index(&init_net, parm->ifindex);
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if (dev == NULL)
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return -ENODEV;
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switch (dev->type) {
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case ARPHRD_TUNNEL:
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case ARPHRD_TUNNEL6:
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case ARPHRD_SIT:
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case ARPHRD_IPGRE:
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case ARPHRD_VOID:
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case ARPHRD_NONE:
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ok_push = 0;
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break;
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default:
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ok_push = 1;
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break;
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}
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} else {
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dev = NULL;
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}
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pc = tcf_hash_check(parm->index, a, bind, &mirred_hash_info);
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if (!pc) {
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if (dev == NULL)
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return -EINVAL;
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pc = tcf_hash_create(parm->index, est, a, sizeof(*m), bind,
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&mirred_idx_gen, &mirred_hash_info);
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if (IS_ERR(pc))
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return PTR_ERR(pc);
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ret = ACT_P_CREATED;
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} else {
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if (!ovr) {
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tcf_mirred_release(to_mirred(pc), bind);
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return -EEXIST;
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}
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}
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m = to_mirred(pc);
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spin_lock_bh(&m->tcf_lock);
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m->tcf_action = parm->action;
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m->tcfm_eaction = parm->eaction;
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if (dev != NULL) {
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m->tcfm_ifindex = parm->ifindex;
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if (ret != ACT_P_CREATED)
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dev_put(m->tcfm_dev);
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dev_hold(dev);
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m->tcfm_dev = dev;
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m->tcfm_ok_push = ok_push;
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}
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spin_unlock_bh(&m->tcf_lock);
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if (ret == ACT_P_CREATED) {
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list_add(&m->tcfm_list, &mirred_list);
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tcf_hash_insert(pc, &mirred_hash_info);
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}
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return ret;
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}
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static int tcf_mirred_cleanup(struct tc_action *a, int bind)
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{
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struct tcf_mirred *m = a->priv;
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if (m)
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return tcf_mirred_release(m, bind);
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return 0;
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}
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static int tcf_mirred(struct sk_buff *skb, const struct tc_action *a,
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struct tcf_result *res)
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{
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struct tcf_mirred *m = a->priv;
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struct net_device *dev;
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struct sk_buff *skb2;
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u32 at;
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int retval, err = 1;
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spin_lock(&m->tcf_lock);
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m->tcf_tm.lastuse = jiffies;
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bstats_update(&m->tcf_bstats, skb);
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dev = m->tcfm_dev;
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if (!dev) {
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printk_once(KERN_NOTICE "tc mirred: target device is gone\n");
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goto out;
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}
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if (!(dev->flags & IFF_UP)) {
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net_notice_ratelimited("tc mirred to Houston: device %s is down\n",
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dev->name);
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goto out;
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}
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at = G_TC_AT(skb->tc_verd);
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skb2 = skb_act_clone(skb, GFP_ATOMIC, m->tcf_action);
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if (skb2 == NULL)
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goto out;
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if (!(at & AT_EGRESS)) {
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if (m->tcfm_ok_push)
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skb_push(skb2, skb2->dev->hard_header_len);
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}
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/* mirror is always swallowed */
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if (m->tcfm_eaction != TCA_EGRESS_MIRROR)
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skb2->tc_verd = SET_TC_FROM(skb2->tc_verd, at);
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skb2->skb_iif = skb->dev->ifindex;
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skb2->dev = dev;
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err = dev_queue_xmit(skb2);
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out:
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if (err) {
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m->tcf_qstats.overlimits++;
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if (m->tcfm_eaction != TCA_EGRESS_MIRROR)
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retval = TC_ACT_SHOT;
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else
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retval = m->tcf_action;
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} else
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retval = m->tcf_action;
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spin_unlock(&m->tcf_lock);
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return retval;
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}
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static int tcf_mirred_dump(struct sk_buff *skb, struct tc_action *a, int bind, int ref)
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{
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unsigned char *b = skb_tail_pointer(skb);
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struct tcf_mirred *m = a->priv;
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struct tc_mirred opt = {
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.index = m->tcf_index,
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.action = m->tcf_action,
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.refcnt = m->tcf_refcnt - ref,
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.bindcnt = m->tcf_bindcnt - bind,
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.eaction = m->tcfm_eaction,
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.ifindex = m->tcfm_ifindex,
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};
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struct tcf_t t;
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if (nla_put(skb, TCA_MIRRED_PARMS, sizeof(opt), &opt))
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goto nla_put_failure;
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t.install = jiffies_to_clock_t(jiffies - m->tcf_tm.install);
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t.lastuse = jiffies_to_clock_t(jiffies - m->tcf_tm.lastuse);
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t.expires = jiffies_to_clock_t(m->tcf_tm.expires);
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if (nla_put(skb, TCA_MIRRED_TM, sizeof(t), &t))
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goto nla_put_failure;
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return skb->len;
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nla_put_failure:
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nlmsg_trim(skb, b);
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return -1;
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}
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static int mirred_device_event(struct notifier_block *unused,
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unsigned long event, void *ptr)
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{
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struct net_device *dev = ptr;
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struct tcf_mirred *m;
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if (event == NETDEV_UNREGISTER)
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list_for_each_entry(m, &mirred_list, tcfm_list) {
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if (m->tcfm_dev == dev) {
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dev_put(dev);
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m->tcfm_dev = NULL;
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}
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}
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return NOTIFY_DONE;
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}
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static struct notifier_block mirred_device_notifier = {
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.notifier_call = mirred_device_event,
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};
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static struct tc_action_ops act_mirred_ops = {
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.kind = "mirred",
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.hinfo = &mirred_hash_info,
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.type = TCA_ACT_MIRRED,
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.capab = TCA_CAP_NONE,
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.owner = THIS_MODULE,
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.act = tcf_mirred,
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.dump = tcf_mirred_dump,
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.cleanup = tcf_mirred_cleanup,
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.lookup = tcf_hash_search,
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.init = tcf_mirred_init,
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.walk = tcf_generic_walker
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};
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MODULE_AUTHOR("Jamal Hadi Salim(2002)");
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MODULE_DESCRIPTION("Device Mirror/redirect actions");
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MODULE_LICENSE("GPL");
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static int __init mirred_init_module(void)
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{
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int err = register_netdevice_notifier(&mirred_device_notifier);
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if (err)
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return err;
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pr_info("Mirror/redirect action on\n");
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return tcf_register_action(&act_mirred_ops);
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}
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static void __exit mirred_cleanup_module(void)
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{
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unregister_netdevice_notifier(&mirred_device_notifier);
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tcf_unregister_action(&act_mirred_ops);
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}
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module_init(mirred_init_module);
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module_exit(mirred_cleanup_module);
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