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rtnetlink: protect handler table with rcu
Note that netlink dumps still acquire rtnl mutex via the netlink dump infrastructure. Signed-off-by: Florian Westphal <fw@strlen.de> Reviewed-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Florian Westphal
David S. Miller
parent
0cc09020ae
commit
6853dd4881
@ -126,7 +126,7 @@ bool lockdep_rtnl_is_held(void)
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EXPORT_SYMBOL(lockdep_rtnl_is_held);
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#endif /* #ifdef CONFIG_PROVE_LOCKING */
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static struct rtnl_link *rtnl_msg_handlers[RTNL_FAMILY_MAX + 1];
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static struct rtnl_link __rcu *rtnl_msg_handlers[RTNL_FAMILY_MAX + 1];
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static refcount_t rtnl_msg_handlers_ref[RTNL_FAMILY_MAX + 1];
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static inline int rtm_msgindex(int msgtype)
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@ -143,36 +143,6 @@ static inline int rtm_msgindex(int msgtype)
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return msgindex;
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}
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static rtnl_doit_func rtnl_get_doit(int protocol, int msgindex)
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{
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struct rtnl_link *tab;
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if (protocol <= RTNL_FAMILY_MAX)
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tab = rtnl_msg_handlers[protocol];
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else
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tab = NULL;
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if (tab == NULL || tab[msgindex].doit == NULL)
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tab = rtnl_msg_handlers[PF_UNSPEC];
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return tab[msgindex].doit;
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}
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static rtnl_dumpit_func rtnl_get_dumpit(int protocol, int msgindex)
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{
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struct rtnl_link *tab;
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if (protocol <= RTNL_FAMILY_MAX)
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tab = rtnl_msg_handlers[protocol];
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else
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tab = NULL;
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if (tab == NULL || tab[msgindex].dumpit == NULL)
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tab = rtnl_msg_handlers[PF_UNSPEC];
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return tab[msgindex].dumpit;
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}
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/**
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* __rtnl_register - Register a rtnetlink message type
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* @protocol: Protocol family or PF_UNSPEC
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@ -201,18 +171,17 @@ int __rtnl_register(int protocol, int msgtype,
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BUG_ON(protocol < 0 || protocol > RTNL_FAMILY_MAX);
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msgindex = rtm_msgindex(msgtype);
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tab = rtnl_msg_handlers[protocol];
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tab = rcu_dereference(rtnl_msg_handlers[protocol]);
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if (tab == NULL) {
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tab = kcalloc(RTM_NR_MSGTYPES, sizeof(*tab), GFP_KERNEL);
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if (tab == NULL)
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return -ENOBUFS;
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rtnl_msg_handlers[protocol] = tab;
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rcu_assign_pointer(rtnl_msg_handlers[protocol], tab);
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}
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if (doit)
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tab[msgindex].doit = doit;
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if (dumpit)
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tab[msgindex].dumpit = dumpit;
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@ -249,16 +218,22 @@ EXPORT_SYMBOL_GPL(rtnl_register);
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*/
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int rtnl_unregister(int protocol, int msgtype)
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{
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struct rtnl_link *handlers;
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int msgindex;
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BUG_ON(protocol < 0 || protocol > RTNL_FAMILY_MAX);
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msgindex = rtm_msgindex(msgtype);
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if (rtnl_msg_handlers[protocol] == NULL)
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rtnl_lock();
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handlers = rtnl_dereference(rtnl_msg_handlers[protocol]);
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if (!handlers) {
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rtnl_unlock();
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return -ENOENT;
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}
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rtnl_msg_handlers[protocol][msgindex].doit = NULL;
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rtnl_msg_handlers[protocol][msgindex].dumpit = NULL;
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handlers[msgindex].doit = NULL;
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handlers[msgindex].dumpit = NULL;
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rtnl_unlock();
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return 0;
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}
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@ -278,10 +253,12 @@ void rtnl_unregister_all(int protocol)
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BUG_ON(protocol < 0 || protocol > RTNL_FAMILY_MAX);
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rtnl_lock();
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handlers = rtnl_msg_handlers[protocol];
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rtnl_msg_handlers[protocol] = NULL;
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handlers = rtnl_dereference(rtnl_msg_handlers[protocol]);
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RCU_INIT_POINTER(rtnl_msg_handlers[protocol], NULL);
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rtnl_unlock();
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synchronize_net();
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while (refcount_read(&rtnl_msg_handlers_ref[protocol]) > 0)
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schedule();
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kfree(handlers);
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@ -2820,11 +2797,13 @@ static u16 rtnl_calcit(struct sk_buff *skb, struct nlmsghdr *nlh)
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* traverse the list of net devices and compute the minimum
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* buffer size based upon the filter mask.
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*/
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list_for_each_entry(dev, &net->dev_base_head, dev_list) {
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rcu_read_lock();
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for_each_netdev_rcu(net, dev) {
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min_ifinfo_dump_size = max_t(u16, min_ifinfo_dump_size,
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if_nlmsg_size(dev,
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ext_filter_mask));
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}
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rcu_read_unlock();
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return nlmsg_total_size(min_ifinfo_dump_size);
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}
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@ -2836,19 +2815,29 @@ static int rtnl_dump_all(struct sk_buff *skb, struct netlink_callback *cb)
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if (s_idx == 0)
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s_idx = 1;
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for (idx = 1; idx <= RTNL_FAMILY_MAX; idx++) {
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int type = cb->nlh->nlmsg_type-RTM_BASE;
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struct rtnl_link *handlers;
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rtnl_dumpit_func dumpit;
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if (idx < s_idx || idx == PF_PACKET)
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continue;
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if (rtnl_msg_handlers[idx] == NULL ||
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rtnl_msg_handlers[idx][type].dumpit == NULL)
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handlers = rtnl_dereference(rtnl_msg_handlers[idx]);
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if (!handlers)
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continue;
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dumpit = READ_ONCE(handlers[type].dumpit);
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if (!dumpit)
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continue;
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if (idx > s_idx) {
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memset(&cb->args[0], 0, sizeof(cb->args));
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cb->prev_seq = 0;
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cb->seq = 0;
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}
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if (rtnl_msg_handlers[idx][type].dumpit(skb, cb))
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if (dumpit(skb, cb))
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break;
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}
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cb->family = idx;
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@ -4151,11 +4140,12 @@ static int rtnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
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struct netlink_ext_ack *extack)
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{
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struct net *net = sock_net(skb->sk);
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struct rtnl_link *handlers;
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int err = -EOPNOTSUPP;
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rtnl_doit_func doit;
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int kind;
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int family;
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int type;
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int err;
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type = nlh->nlmsg_type;
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if (type > RTM_MAX)
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@ -4173,23 +4163,40 @@ static int rtnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
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if (kind != 2 && !netlink_net_capable(skb, CAP_NET_ADMIN))
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return -EPERM;
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if (family > ARRAY_SIZE(rtnl_msg_handlers))
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family = PF_UNSPEC;
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rcu_read_lock();
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handlers = rcu_dereference(rtnl_msg_handlers[family]);
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if (!handlers) {
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family = PF_UNSPEC;
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handlers = rcu_dereference(rtnl_msg_handlers[family]);
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}
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if (kind == 2 && nlh->nlmsg_flags&NLM_F_DUMP) {
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struct sock *rtnl;
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rtnl_dumpit_func dumpit;
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u16 min_dump_alloc = 0;
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rtnl_lock();
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dumpit = READ_ONCE(handlers[type].dumpit);
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if (!dumpit) {
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family = PF_UNSPEC;
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handlers = rcu_dereference(rtnl_msg_handlers[PF_UNSPEC]);
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if (!handlers)
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goto err_unlock;
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dumpit = rtnl_get_dumpit(family, type);
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if (dumpit == NULL)
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goto err_unlock;
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dumpit = READ_ONCE(handlers[type].dumpit);
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if (!dumpit)
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goto err_unlock;
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}
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refcount_inc(&rtnl_msg_handlers_ref[family]);
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if (type == RTM_GETLINK)
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min_dump_alloc = rtnl_calcit(skb, nlh);
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__rtnl_unlock();
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rcu_read_unlock();
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rtnl = net->rtnl;
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{
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struct netlink_dump_control c = {
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@ -4202,18 +4209,20 @@ static int rtnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
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return err;
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}
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rcu_read_unlock();
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rtnl_lock();
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doit = rtnl_get_doit(family, type);
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if (doit == NULL)
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goto err_unlock;
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err = doit(skb, nlh, extack);
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handlers = rtnl_dereference(rtnl_msg_handlers[family]);
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if (handlers) {
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doit = READ_ONCE(handlers[type].doit);
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if (doit)
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err = doit(skb, nlh, extack);
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}
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rtnl_unlock();
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return err;
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err_unlock:
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rtnl_unlock();
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rcu_read_unlock();
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return -EOPNOTSUPP;
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}
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