0.1. SUMMARY
There is a struct in_device __rcu *ip_ptr under every net_device.
which stores all the IPv4 related information for this device.
Each IPv4 address is stored a struct in_ifaddr,
all the IPv4 address of a net device are stored into a list(netdev->ip_ptr->ifa_list).
0.1.1. 相关结构体
0.1.1.1. net_device 和in_device
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| 1075 struct net_device {
...
1208 struct in_device __rcu *ip_ptr;
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| 55 struct in_device {
56 struct net_device *dev;
57 atomic_t refcnt;
58 int dead;
59 struct in_ifaddr *ifa_list;
...
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0.1.1.2. ifa结构体struct in_ifaddr
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| 161 struct in_ifaddr {
162 struct hlist_node hash;
163 struct in_ifaddr *ifa_next;
164 struct in_device *ifa_dev;
165 struct rcu_head rcu_head;
166 __be32 ifa_local;
167 __be32 ifa_address;
168 __be32 ifa_mask;
169 __be32 ifa_broadcast;
170 unsigned char ifa_scope;
171 unsigned char ifa_flags;
172 unsigned char ifa_prefixlen;
173 char ifa_label[IFNAMSIZ];
174
175 /* In seconds, relative to tstamp. Expiry is at tstamp + HZ * lft. */
176 __u32 ifa_valid_lft;
177 __u32 ifa_preferred_lft;
178 unsigned long ifa_cstamp; /* created timestamp */
179 unsigned long ifa_tstamp; /* updated timestamp */
180 };
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0.1.1.3. 注册处理增删IP地址命令的入口函数
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| 2284 void __init devinet_init(void)
2285 {
...
2300 rtnl_register(PF_INET, RTM_NEWADDR, inet_rtm_newaddr, NULL, NULL);
2301 rtnl_register(PF_INET, RTM_DELADDR, inet_rtm_deladdr, NULL, NULL);
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0.2. 内核如何处理增加ip地址
0.2.1. calltrace
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| > inet_rtm_newaddr
> > rtm_to_ifaddr
> > find_matching_ifa
> > __inet_insert_ifa
> > > insert ifa to ifa_list with right postion.
> > > inet_hash_insert(dev_net(in_dev->dev), ifa);
> > > rtmsg_ifa(RTM_NEWADDR, ifa, nlh, portid);
> > > blocking_notifier_call_chain(&inetaddr_chain, NETDEV_UP, ifa);
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0.2.1.1. NOTE:
inetaddr_chain will be shown in next blog.
0.2.2. 处理增加IP地址命令的入口函数
0.2.2.1. inet_rtm_newaddr
- 创建：函数
rtm_to_ifaddr根据netlink 消息，生成一个 ifa实例
- 查找：使用函数
find_matching_ifa查找是否有相同的ifa
- 插入：如果没有找到， 则通过``__inet_insert_ifa`添加ifa到内核里。
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| 807 static int inet_rtm_newaddr(struct sk_buff *skb, struct nlmsghdr *nlh)
808 {
809 struct net *net = sock_net(skb->sk);
810 struct in_ifaddr *ifa;
811 struct in_ifaddr *ifa_existing;
812 __u32 valid_lft = INFINITY_LIFE_TIME;
813 __u32 prefered_lft = INFINITY_LIFE_TIME;
814
815 ASSERT_RTNL();
816
817 ifa = rtm_to_ifaddr(net, nlh, &valid_lft, &prefered_lft);
818 if (IS_ERR(ifa))
819 return PTR_ERR(ifa);
820
821 ifa_existing = find_matching_ifa(ifa);
822 if (!ifa_existing) {
823 /* It would be best to check for !NLM_F_CREATE here but
824 * userspace alreay relies on not having to provide this.
825 */
826 set_ifa_lifetime(ifa, valid_lft, prefered_lft);
827 return __inet_insert_ifa(ifa, nlh, NETLINK_CB(skb).portid);
828 } else {
829 inet_free_ifa(ifa);
830
831 if (nlh->nlmsg_flags & NLM_F_EXCL ||
832 !(nlh->nlmsg_flags & NLM_F_REPLACE))
833 return -EEXIST;
834 ifa = ifa_existing;
835 set_ifa_lifetime(ifa, valid_lft, prefered_lft);
836 cancel_delayed_work(&check_lifetime_work);
837 schedule_delayed_work(&check_lifetime_work, 0);
838 rtmsg_ifa(RTM_NEWADDR, ifa, nlh, NETLINK_CB(skb).portid);
839 blocking_notifier_call_chain(&inetaddr_chain, NETDEV_UP, ifa);
840 }
841 return 0;
842 }
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0.2.2.1.1. rtm_to_ifaddr
根据netlink消息生成 ifa
- 查找并确认netdev 网口名字: 查找 ip命令指定的网口下，是否有这个IP地址，而不是在整个ns下查
- 分配一个ifa实例
- 根据 netlink 消息内容初始化 ifa
Q: 同一个IP地址(掩码也相同)可以配置的多个网口上吗？或者说多个网口可以配置相同的ip地址（ip 和掩码都相同）?
A: 可以
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| 708 static struct in_ifaddr *rtm_to_ifaddr(struct net *net, struct nlmsghdr *nlh,
709 __u32 *pvalid_lft, __u32 *pprefered_lft)
710 {
711 struct nlattr *tb[IFA_MAX+1];
712 struct in_ifaddr *ifa;
713 struct ifaddrmsg *ifm;
714 struct net_device *dev;
715 struct in_device *in_dev;
716 int err;
717
718 err = nlmsg_parse(nlh, sizeof(*ifm), tb, IFA_MAX, ifa_ipv4_policy);
719 if (err < 0)
720 goto errout;
721
722 ifm = nlmsg_data(nlh);
723 err = -EINVAL;
724 if (ifm->ifa_prefixlen > 32 || tb[IFA_LOCAL] == NULL)
725 goto errout;
726
727 dev = __dev_get_by_index(net, ifm->ifa_index);
728 err = -ENODEV;
729 if (dev == NULL)
730 goto errout;
731
732 in_dev = __in_dev_get_rtnl(dev);
733 err = -ENOBUFS;
734 if (in_dev == NULL)
735 goto errout;
736
737 ifa = inet_alloc_ifa();
738 if (ifa == NULL)
739 /*
740 * A potential indev allocation can be left alive, it stays
741 * assigned to its device and is destroy with it.
742 */
743 goto errout;
744
745 ipv4_devconf_setall(in_dev);
746 in_dev_hold(in_dev);
747
748 if (tb[IFA_ADDRESS] == NULL)
749 tb[IFA_ADDRESS] = tb[IFA_LOCAL];
750
751 INIT_HLIST_NODE(&ifa->hash);
752 ifa->ifa_prefixlen = ifm->ifa_prefixlen;
753 ifa->ifa_mask = inet_make_mask(ifm->ifa_prefixlen);
754 ifa->ifa_flags = ifm->ifa_flags;
755 ifa->ifa_scope = ifm->ifa_scope;
756 ifa->ifa_dev = in_dev;
757
758 ifa->ifa_local = nla_get_be32(tb[IFA_LOCAL]);
759 ifa->ifa_address = nla_get_be32(tb[IFA_ADDRESS]);
760
761 if (tb[IFA_BROADCAST])
762 ifa->ifa_broadcast = nla_get_be32(tb[IFA_BROADCAST]);
763
764 if (tb[IFA_LABEL])
765 nla_strlcpy(ifa->ifa_label, tb[IFA_LABEL], IFNAMSIZ);
766 else
767 memcpy(ifa->ifa_label, dev->name, IFNAMSIZ);
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769 if (tb[IFA_CACHEINFO]) {
770 struct ifa_cacheinfo *ci;
771
772 ci = nla_data(tb[IFA_CACHEINFO]);
773 if (!ci->ifa_valid || ci->ifa_prefered > ci->ifa_valid) {
774 err = -EINVAL;
775 goto errout_free;
776 }
777 *pvalid_lft = ci->ifa_valid;
778 *pprefered_lft = ci->ifa_prefered;
779 }
780
781 return ifa;
782
783 errout_free:
784 inet_free_ifa(ifa);
785 errout:
786 return ERR_PTR(err);
787 }
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0.2.2.2. 把 ifa 插入到对应的两个链表里。
- 插入到网口下的 ip 地址列表
- 插入同 ns 下的 hash 链表
- 发送 netlink 更新消息
- 发送
blocking_notifier_call_chain :待学习
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| 426 static int __inet_insert_ifa(struct in_ifaddr *ifa, struct nlmsghdr *nlh,
427 u32 portid)
428 {
429 struct in_device *in_dev = ifa->ifa_dev;
430 struct in_ifaddr *ifa1, **ifap, **last_primary;
431
432 ASSERT_RTNL();
433
434 if (!ifa->ifa_local) {
435 inet_free_ifa(ifa);
436 return 0;
437 }
438
439 ifa->ifa_flags &= ~IFA_F_SECONDARY;
440 last_primary = &in_dev->ifa_list;
441
442 for (ifap = &in_dev->ifa_list; (ifa1 = *ifap) != NULL;
443 ifap = &ifa1->ifa_next) {
444 if (!(ifa1->ifa_flags & IFA_F_SECONDARY) &&
445 ifa->ifa_scope <= ifa1->ifa_scope)
446 last_primary = &ifa1->ifa_next;
447 if (ifa1->ifa_mask == ifa->ifa_mask &&
448 inet_ifa_match(ifa1->ifa_address, ifa)) {
449 if (ifa1->ifa_local == ifa->ifa_local) {
450 inet_free_ifa(ifa);
451 return -EEXIST;
452 }
453 if (ifa1->ifa_scope != ifa->ifa_scope) {
454 inet_free_ifa(ifa);
455 return -EINVAL;
456 }
457 ifa->ifa_flags |= IFA_F_SECONDARY;
458 }
459 }
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461 if (!(ifa->ifa_flags & IFA_F_SECONDARY)) {
462 net_srandom(ifa->ifa_local);
463 ifap = last_primary;
464 }
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466 ifa->ifa_next = *ifap;
467 *ifap = ifa;
468
469 inet_hash_insert(dev_net(in_dev->dev), ifa);
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471 cancel_delayed_work(&check_lifetime_work);
472 schedule_delayed_work(&check_lifetime_work, 0);
473
474 /* Send message first, then call notifier.
475 Notifier will trigger FIB update, so that
476 listeners of netlink will know about new ifaddr */
477 rtmsg_ifa(RTM_NEWADDR, ifa, nlh, portid);
478 blocking_notifier_call_chain(&inetaddr_chain, NETDEV_UP, ifa);
479
480 return 0;
481 }
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