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ipv6: properly combine dev_base_seq and ipv6.dev_addr_genid

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net->dev_base_seq and ipv6.dev_addr_genid are monotonically increasing.

If we XOR their values, we could miss to detect if both values
were changed with the same amount.

Fixes: 63998ac24f ("ipv6: provide addr and netconf dump consistency info")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Nicolas Dichtel <nicolas.dichtel@6wind.com>

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2024-02-15 17:21:07 +00:00 committed by David S. Miller
parent 081a0e3b0d
commit e898e4cd1a
1 changed files with 18 additions and 3 deletions
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21
net/ipv6/addrconf.c
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@ -708,6 +708,22 @@ static int inet6_netconf_get_devconf(struct sk_buff *in_skb,
return err;
}
/* Combine dev_addr_genid and dev_base_seq to detect changes.
*/
static u32 inet6_base_seq(const struct net *net)
{
u32 res = atomic_read(&net->ipv6.dev_addr_genid) +
net->dev_base_seq;
/* Must not return 0 (see nl_dump_check_consistent()).
* Chose a value far away from 0.
*/
if (!res)
res = 0x80000000;
return res;
}
static int inet6_netconf_dump_devconf(struct sk_buff *skb,
struct netlink_callback *cb)
{
@ -741,8 +757,7 @@ static int inet6_netconf_dump_devconf(struct sk_buff *skb,
idx = 0;
head = &net->dev_index_head[h];
rcu_read_lock();
cb->seq = atomic_read(&net->ipv6.dev_addr_genid) ^
net->dev_base_seq;
cb->seq = inet6_base_seq(net);
hlist_for_each_entry_rcu(dev, head, index_hlist) {
if (idx < s_idx)
goto cont;
@ -5362,7 +5377,7 @@ static int inet6_dump_addr(struct sk_buff *skb, struct netlink_callback *cb,
}
rcu_read_lock();
cb->seq = atomic_read(&tgt_net->ipv6.dev_addr_genid) ^ tgt_net->dev_base_seq;
cb->seq = inet6_base_seq(tgt_net);
for (h = s_h; h < NETDEV_HASHENTRIES; h++, s_idx = 0) {
idx = 0;
head = &tgt_net->dev_index_head[h];