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ipv6: remove RTNL protection from ip6addrlbl_dump()

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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: Eric Dumazet <edumazet@google.com>
Link:https://lore.kernel.org/netdev/67f5cb70-14a4-4455-8372-f039da2f15c2@kernel.org/
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2024-04-04 13:24:13 +00:00 committed by David S. Miller
parent 802e12ff9c
commit eec53cc38c
1 changed files with 11 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
net/ipv6/addrlabel.c
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@ -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); hlist_add_head_rcu(&newp->list, &net->ipv6.ip6addrlbl_table.head);
out: out:
if (!ret) if (!ret)
net->ipv6.ip6addrlbl_table.seq++; WRITE_ONCE(net->ipv6.ip6addrlbl_table.seq,
net->ipv6.ip6addrlbl_table.seq + 1);
return ret; return ret;
} }
@ -445,7 +446,7 @@ static void ip6addrlbl_putmsg(struct nlmsghdr *nlh,
}; };
static int ip6addrlbl_fill(struct sk_buff *skb, static int ip6addrlbl_fill(struct sk_buff *skb,
struct ip6addrlbl_entry *p, const struct ip6addrlbl_entry *p,
u32 lseq, u32 lseq,
u32 portid, u32 seq, int event, u32 portid, u32 seq, int event,
unsigned int flags) 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 net *net = sock_net(skb->sk);
struct ip6addrlbl_entry *p; struct ip6addrlbl_entry *p;
int idx = 0, s_idx = cb->args[0]; int idx = 0, s_idx = cb->args[0];
int err; int err = 0;
u32 lseq;
if (cb->strict_check) { if (cb->strict_check) {
err = ip6addrlbl_valid_dump_req(nlh, cb->extack); 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(); rcu_read_lock();
lseq = READ_ONCE(net->ipv6.ip6addrlbl_table.seq);
hlist_for_each_entry_rcu(p, &net->ipv6.ip6addrlbl_table.head, list) { hlist_for_each_entry_rcu(p, &net->ipv6.ip6addrlbl_table.head, list) {
if (idx >= s_idx) { if (idx >= s_idx) {
err = ip6addrlbl_fill(skb, p, err = ip6addrlbl_fill(skb, p,
net->ipv6.ip6addrlbl_table.seq, lseq,
NETLINK_CB(cb->skb).portid, NETLINK_CB(cb->skb).portid,
nlh->nlmsg_seq, nlh->nlmsg_seq,
RTM_NEWADDRLABEL, RTM_NEWADDRLABEL,
@ -522,7 +525,7 @@ static int ip6addrlbl_dump(struct sk_buff *skb, struct netlink_callback *cb)
} }
rcu_read_unlock(); rcu_read_unlock();
cb->args[0] = idx; cb->args[0] = idx;
return skb->len; return err;
} }
static inline int ip6addrlbl_msgsize(void) 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(); rcu_read_lock();
p = __ipv6_addr_label(net, addr, ipv6_addr_type(addr), ifal->ifal_index); 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) if (p)
err = ip6addrlbl_fill(skb, p, lseq, err = ip6addrlbl_fill(skb, p, lseq,
NETLINK_CB(in_skb).portid, NETLINK_CB(in_skb).portid,
@ -647,6 +650,7 @@ int __init ipv6_addr_label_rtnl_register(void)
return ret; return ret;
ret = rtnl_register_module(THIS_MODULE, PF_INET6, RTM_GETADDRLABEL, ret = rtnl_register_module(THIS_MODULE, PF_INET6, RTM_GETADDRLABEL,
ip6addrlbl_get, ip6addrlbl_get,
ip6addrlbl_dump, RTNL_FLAG_DOIT_UNLOCKED); ip6addrlbl_dump, RTNL_FLAG_DOIT_UNLOCKED |
RTNL_FLAG_DUMP_UNLOCKED);
return ret; return ret;
} }