From f712bf6f17d881763547d6c33ccdcf3e62d4ae84 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Mon, 7 Sep 2026 07:58:46 +0000 Subject: [PATCH] sit: no longer rely on RTNL in ipip6_fill_info() 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(). Signed-off-by: Eric Dumazet Acked-by: Lorenzo Bianconi Link: https://patch.msgid.link/20260907075846.2913645-10-edumazet@google.com Signed-off-by: Jakub Kicinski --- 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 c9049ab87e01..14ba3cfb304a 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; }