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ip6mr: Convert ip6mr_rtm_getroute() to RCU.

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ip6mr_rtm_getroute() calls __ip6mr_get_table(), ip6mr_cache_find(),
and ip6mr_fill_mroute().

Once created, struct mr_table is not freed until netns dismantle,
so it's safe under RCU.

ip6mr_cache_find() iterates mrt->mfc_hash with rhl_for_each_entry_rcu().
struct mr_mfc is freed with call_rcu(), so this is also safe under
RCU.

ip6mr_fill_mroute() calls mr_fill_mroute(), which properly uses
RCU helpers.

Let's call them under RCU and register ip6mr_rtm_getroute() with
RTNL_FLAG_DOIT_UNLOCKED.

Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260604224712.3209821-6-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Kuniyuki Iwashima 2026-06-04 22:46:23 +00:00 committed by Jakub Kicinski
parent c2f5fd21ac
commit 76ea2ba229
1 changed files with 7 additions and 4 deletions
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11
net/ipv6/ip6mr.c
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@ -1386,7 +1386,8 @@ static struct pernet_operations ip6mr_net_ops = {
static const struct rtnl_msg_handler ip6mr_rtnl_msg_handlers[] __initconst_or_module = {
{.owner = THIS_MODULE, .protocol = RTNL_FAMILY_IP6MR,
.msgtype = RTM_GETROUTE,
.doit = ip6mr_rtm_getroute, .dumpit = ip6mr_rtm_dumproute},
.doit = ip6mr_rtm_getroute, .dumpit = ip6mr_rtm_dumproute,
.flags = RTNL_FLAG_DOIT_UNLOCKED},
};
int __init ip6_mr_init(void)
@ -2710,6 +2711,8 @@ static int ip6mr_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
grp = nla_get_in6_addr(tb[RTA_DST]);
tableid = nla_get_u32_default(tb[RTA_TABLE], 0);
rcu_read_lock();
mrt = __ip6mr_get_table(net, tableid ?: RT_TABLE_DEFAULT);
if (!mrt) {
NL_SET_ERR_MSG_MOD(extack, "MR table does not exist");
@ -2717,10 +2720,7 @@ static int ip6mr_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
goto err;
}
/* entries are added/deleted only under RTNL */
rcu_read_lock();
cache = ip6mr_cache_find(mrt, &src, &grp);
rcu_read_unlock();
if (!cache) {
NL_SET_ERR_MSG_MOD(extack, "MR cache entry not found");
err = -ENOENT;
@ -2732,9 +2732,12 @@ static int ip6mr_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
if (err < 0)
goto err;
rcu_read_unlock();
return rtnl_unicast(skb, net, NETLINK_CB(in_skb).portid);
err:
rcu_read_unlock();
kfree_skb(skb);
return err;
}