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vlan: no longer rely on RTNL in vlan_fill_info()

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vlan_fill_info() used rcu_dereference_rtnl() to walk the egress
priority map, forcing "ip link show" dumps to hold RTNL.

The egress priority map is already fully RCU compliant:
entries are published with rcu_assign_pointer() and freed with
kfree_rcu() from vlan_dev_set_egress_priority() and
vlan_dev_free_egress_priority().

Wrap the QoS mapping serialization in rcu_read_lock() /
rcu_read_unlock() and use rcu_dereference().

Now that all the involved fields are annotated, use READ_ONCE()
for vlan->flags, vlan->nr_ingress_mappings, vlan->nr_egress_mappings
and vlan->ingress_priority_map[].

Also add missing const qualifiers in vlan_get_size() and
vlan_fill_info().

Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260916132532.1785657-3-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet 2026-09-16 13:25:32 +00:00 committed by Jakub Kicinski
parent ca6ff8dd70
commit ea5bd52c8b
1 changed files with 30 additions and 18 deletions
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48
net/8021q/vlan_netlink.c
View File

@ -209,7 +209,7 @@ static inline size_t vlan_qos_map_size(unsigned int n)
static size_t vlan_get_size(const struct net_device *dev)
{
struct vlan_dev_priv *vlan = vlan_dev_priv(dev);
const struct vlan_dev_priv *vlan = vlan_dev_priv(dev);
return nla_total_size(2) + /* IFLA_VLAN_PROTOCOL */
nla_total_size(2) + /* IFLA_VLAN_ID */
@ -220,60 +220,72 @@ static size_t vlan_get_size(const struct net_device *dev)
static int vlan_fill_info(struct sk_buff *skb, const struct net_device *dev)
{
struct vlan_dev_priv *vlan = vlan_dev_priv(dev);
struct vlan_priority_tci_mapping *pm;
struct ifla_vlan_flags f;
const struct vlan_dev_priv *vlan = vlan_dev_priv(dev);
const struct vlan_priority_tci_mapping *pm;
struct ifla_vlan_qos_mapping m;
struct ifla_vlan_flags f;
struct nlattr *nest;
unsigned int i;
u32 flags;
if (nla_put_be16(skb, IFLA_VLAN_PROTOCOL, vlan->vlan_proto) ||
nla_put_u16(skb, IFLA_VLAN_ID, vlan->vlan_id))
goto nla_put_failure;
if (vlan->flags) {
f.flags = vlan->flags;
flags = READ_ONCE(vlan->flags);
if (flags) {
f.flags = flags;
f.mask = ~0;
if (nla_put(skb, IFLA_VLAN_FLAGS, sizeof(f), &f))
goto nla_put_failure;
}
if (vlan->nr_ingress_mappings) {
rcu_read_lock();
if (READ_ONCE(vlan->nr_ingress_mappings)) {
nest = nla_nest_start_noflag(skb, IFLA_VLAN_INGRESS_QOS);
if (nest == NULL)
goto nla_put_failure;
if (!nest)
goto nla_put_failure_unlock;
for (i = 0; i < ARRAY_SIZE(vlan->ingress_priority_map); i++) {
if (!vlan->ingress_priority_map[i])
u32 skb_prio = READ_ONCE(vlan->ingress_priority_map[i]);
if (!skb_prio)
continue;
m.from = i;
m.to = vlan->ingress_priority_map[i];
m.to = skb_prio;
if (nla_put(skb, IFLA_VLAN_QOS_MAPPING,
sizeof(m), &m))
goto nla_put_failure;
goto nla_put_failure_unlock;
}
nla_nest_end(skb, nest);
}
if (vlan->nr_egress_mappings) {
if (READ_ONCE(vlan->nr_egress_mappings)) {
nest = nla_nest_start_noflag(skb, IFLA_VLAN_EGRESS_QOS);
if (nest == NULL)
goto nla_put_failure;
if (!nest)
goto nla_put_failure_unlock;
for (i = 0; i < ARRAY_SIZE(vlan->egress_priority_map); i++) {
for (pm = rcu_dereference_rtnl(vlan->egress_priority_map[i]); pm;
pm = rcu_dereference_rtnl(pm->next)) {
for (pm = rcu_dereference(vlan->egress_priority_map[i]); pm;
pm = rcu_dereference(pm->next)) {
u16 vlan_qos = READ_ONCE(pm->vlan_qos);
m.from = pm->priority;
m.to = (vlan_qos >> 13) & 0x7;
if (nla_put(skb, IFLA_VLAN_QOS_MAPPING,
sizeof(m), &m))
goto nla_put_failure;
goto nla_put_failure_unlock;
}
}
nla_nest_end(skb, nest);
}
rcu_read_unlock();
return 0;
nla_put_failure_unlock:
rcu_read_unlock();
nla_put_failure:
return -EMSGSIZE;
}