Re: [PATCH net-next 9/9] sit: no longer rely on RTNL in ipip6_fill_info()
From: Lorenzo Bianconi <hidden>
Date: 2026-09-07 15:04:32
Now that SIT parameters and 6RD parameters are RCU-protected, and fwmark/encap are annotated with READ_ONCE()/WRITE_ONCE(), ipip6_fill_info() no longer requires RTNL to be held. Wrap the attribute serialization in rcu_read_lock() and rcu_read_unlock().
Acked-by: Lorenzo Bianconi <redacted>
quoted hunk ↗ jump to hunk
Signed-off-by: Eric Dumazet <edumazet@google.com> --- net/ipv6/sit.c | 21 +++++++++++++++------ 1 file changed, 15 insertions(+), 6 deletions(-)diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c index c9049ab87e010eed5f53a342460ed10006083cd7..14ba3cfb304a83ee37e3be5b09a57c371f1977c3 100644 --- a/net/ipv6/sit.c +++ b/net/ipv6/sit.c@@ -1846,11 +1846,18 @@ static size_t ipip6_get_size(const struct net_device *dev) static int ipip6_fill_info(struct sk_buff *skb, const struct net_device *dev) { struct ip_tunnel *tunnel = netdev_priv(dev); - const struct ip_tunnel_parm_kern *parm = rtnl_dereference(tunnel->sit_parms); + const struct ip_tunnel_parm_kern *parm; #ifdef CONFIG_IPV6_SIT_6RD const struct ip_tunnel_6rd_parm *ip6rd; #endif + rcu_read_lock(); + parm = rcu_dereference(tunnel->sit_parms); + if (!parm) { + rcu_read_unlock(); + return -ENODEV; + } + if (nla_put_u32(skb, IFLA_IPTUN_LINK, parm->link) || nla_put_in_addr(skb, IFLA_IPTUN_LOCAL, parm->iph.saddr) || nla_put_in_addr(skb, IFLA_IPTUN_REMOTE, parm->iph.daddr) ||@@ -1865,7 +1872,7 @@ static int ipip6_fill_info(struct sk_buff *skb, const struct net_device *dev) goto nla_put_failure; #ifdef CONFIG_IPV6_SIT_6RD - ip6rd = rcu_dereference_rtnl(tunnel->ip6rd); + ip6rd = rcu_dereference(tunnel->ip6rd); if (ip6rd && (nla_put_in6_addr(skb, IFLA_IPTUN_6RD_PREFIX, &ip6rd->prefix) ||@@ -1879,18 +1886,20 @@ static int ipip6_fill_info(struct sk_buff *skb, const struct net_device *dev) #endif if (nla_put_u16(skb, IFLA_IPTUN_ENCAP_TYPE, - tunnel->encap.type) || + READ_ONCE(tunnel->encap.type)) || nla_put_be16(skb, IFLA_IPTUN_ENCAP_SPORT, - tunnel->encap.sport) || + READ_ONCE(tunnel->encap.sport)) || nla_put_be16(skb, IFLA_IPTUN_ENCAP_DPORT, - tunnel->encap.dport) || + READ_ONCE(tunnel->encap.dport)) || nla_put_u16(skb, IFLA_IPTUN_ENCAP_FLAGS, - tunnel->encap.flags)) + READ_ONCE(tunnel->encap.flags))) goto nla_put_failure; + rcu_read_unlock(); return 0; nla_put_failure: + rcu_read_unlock(); return -EMSGSIZE; }-- 2.55.0.979.g7e5102b832-goog
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