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ipv4: properly combine dev_base_seq and ipv4.dev_addr_genid

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net->dev_base_seq and ipv4.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: 0465277f6b ("ipv4: provide addr and netconf dump consistency info")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Nicolas Dichtel <nicolas.dichtel@6wind.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 17:21:06 +00:00 committed by David S. Miller
parent 97dde84026
commit 081a0e3b0d
1 changed files with 17 additions and 4 deletions
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21
net/ipv4/devinet.c
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@ -1825,6 +1825,21 @@ done:
return err;
}
/* Combine dev_addr_genid and dev_base_seq to detect changes.
*/
static u32 inet_base_seq(const struct net *net)
{
u32 res = atomic_read(&net->ipv4.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 inet_dump_ifaddr(struct sk_buff *skb, struct netlink_callback *cb)
{
const struct nlmsghdr *nlh = cb->nlh;
@ -1876,8 +1891,7 @@ static int inet_dump_ifaddr(struct sk_buff *skb, struct netlink_callback *cb)
idx = 0;
head = &tgt_net->dev_index_head[h];
rcu_read_lock();
cb->seq = atomic_read(&tgt_net->ipv4.dev_addr_genid) ^
tgt_net->dev_base_seq;
cb->seq = inet_base_seq(tgt_net);
hlist_for_each_entry_rcu(dev, head, index_hlist) {
if (idx < s_idx)
goto cont;
@ -2278,8 +2292,7 @@ static int inet_netconf_dump_devconf(struct sk_buff *skb,
idx = 0;
head = &net->dev_index_head[h];
rcu_read_lock();
cb->seq = atomic_read(&net->ipv4.dev_addr_genid) ^
net->dev_base_seq;
cb->seq = inet_base_seq(net);
hlist_for_each_entry_rcu(dev, head, index_hlist) {
if (idx < s_idx)
goto cont;