Commit eec53cc3 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

ipv6: remove RTNL protection from ip6addrlbl_dump() 



No longer hold RTNL while calling ip6addrlbl_dump()
("ip addrlabel show")

ip6addrlbl_dump() was already mostly relying on RCU anyway.

Add READ_ONCE()/WRITE_ONCE() annotations around
net->ipv6.ip6addrlbl_table.seq

Note that ifal_seq value is currently ignored in iproute2,
and a bit weak.

We might user later cb->seq  / nl_dump_check_consistent()
protocol if needed.

Also change return value for a completed dump,
so that NLMSG_DONE can be appended to current skb,
saving one recvmsg() system call.

v2: read net->ipv6.ip6addrlbl_table.seq once, (David Ahern)

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Link:https://lore.kernel.org/netdev/67f5cb70-14a4-4455-8372-f039da2f15c2@kernel.org/


Reviewed-by: default avatarDavid Ahern <dsahern@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 802e12ff

net/ipv6/addrlabel.c

+11 −7
Original line number Diff line number Diff line
@@ -234,7 +234,8 @@ static int __ip6addrlbl_add(struct net *net, struct ip6addrlbl_entry *newp, 
		hlist_add_head_rcu(&newp->list, &net->ipv6.ip6addrlbl_table.head);

out:

	if (!ret)

		net->ipv6.ip6addrlbl_table.seq++;

		WRITE_ONCE(net->ipv6.ip6addrlbl_table.seq,

			   net->ipv6.ip6addrlbl_table.seq + 1);

	return ret;

}
@@ -445,7 +446,7 @@ static void ip6addrlbl_putmsg(struct nlmsghdr *nlh, 
};



static int ip6addrlbl_fill(struct sk_buff *skb,

			   struct ip6addrlbl_entry *p,

			   const struct ip6addrlbl_entry *p,

			   u32 lseq,

			   u32 portid, u32 seq, int event,

			   unsigned int flags)
@@ -498,7 +499,8 @@ static int ip6addrlbl_dump(struct sk_buff *skb, struct netlink_callback *cb) 
	struct net *net = sock_net(skb->sk);

	struct ip6addrlbl_entry *p;

	int idx = 0, s_idx = cb->args[0];

	int err;

	int err = 0;

	u32 lseq;



	if (cb->strict_check) {

		err = ip6addrlbl_valid_dump_req(nlh, cb->extack);
@@ -507,10 +509,11 @@ static int ip6addrlbl_dump(struct sk_buff *skb, struct netlink_callback *cb) 
	}



	rcu_read_lock();

	lseq = READ_ONCE(net->ipv6.ip6addrlbl_table.seq);

	hlist_for_each_entry_rcu(p, &net->ipv6.ip6addrlbl_table.head, list) {

		if (idx >= s_idx) {

			err = ip6addrlbl_fill(skb, p,

					      net->ipv6.ip6addrlbl_table.seq,

					      lseq,

					      NETLINK_CB(cb->skb).portid,

					      nlh->nlmsg_seq,

					      RTM_NEWADDRLABEL,
@@ -522,7 +525,7 @@ static int ip6addrlbl_dump(struct sk_buff *skb, struct netlink_callback *cb) 
	}

	rcu_read_unlock();

	cb->args[0] = idx;

	return skb->len;

	return err;

}



static inline int ip6addrlbl_msgsize(void)
@@ -614,7 +617,7 @@ static int ip6addrlbl_get(struct sk_buff *in_skb, struct nlmsghdr *nlh, 


	rcu_read_lock();

	p = __ipv6_addr_label(net, addr, ipv6_addr_type(addr), ifal->ifal_index);

	lseq = net->ipv6.ip6addrlbl_table.seq;

	lseq = READ_ONCE(net->ipv6.ip6addrlbl_table.seq);

	if (p)

		err = ip6addrlbl_fill(skb, p, lseq,

				      NETLINK_CB(in_skb).portid,
@@ -647,6 +650,7 @@ int __init ipv6_addr_label_rtnl_register(void) 
		return ret;

	ret = rtnl_register_module(THIS_MODULE, PF_INET6, RTM_GETADDRLABEL,

				   ip6addrlbl_get,

				   ip6addrlbl_dump, RTNL_FLAG_DOIT_UNLOCKED);

				   ip6addrlbl_dump, RTNL_FLAG_DOIT_UNLOCKED |

						    RTNL_FLAG_DUMP_UNLOCKED);

	return ret;

}