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Date: Fri, 28 Oct 2016 10:27:43 -0400
From: "John W. Linville" <linville@...driver.com>
To: Pravin B Shelar <pshelar@....org>
Cc: netdev@...r.kernel.org
Subject: Re: [PATCH net 2/2] geneve: avoid using stale geneve socket.
On Thu, Oct 27, 2016 at 11:51:56AM -0700, Pravin B Shelar wrote:
> This patch is similar to earlier vxlan patch.
> Geneve device close operation frees geneve socket. This
> operation can race with geneve-xmit function which
> dereferences geneve socket. Following patch uses RCU
> mechanism to avoid this situation.
>
> Signed-off-by: Pravin B Shelar <pshelar@....org>
LGTM, although I reckon that Stephen's comment about RCU_INIT_POINTER
applies to this patch as well.
Either way...
Acked-by: John W. Linville <linville@...driver.com>
> ---
> drivers/net/geneve.c | 45 ++++++++++++++++++++++++++++++++++-----------
> 1 file changed, 34 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/net/geneve.c b/drivers/net/geneve.c
> index 16af1ce..42edd7b 100644
> --- a/drivers/net/geneve.c
> +++ b/drivers/net/geneve.c
> @@ -58,9 +58,9 @@ struct geneve_dev {
> struct hlist_node hlist; /* vni hash table */
> struct net *net; /* netns for packet i/o */
> struct net_device *dev; /* netdev for geneve tunnel */
> - struct geneve_sock *sock4; /* IPv4 socket used for geneve tunnel */
> + struct geneve_sock __rcu *sock4; /* IPv4 socket used for geneve tunnel */
> #if IS_ENABLED(CONFIG_IPV6)
> - struct geneve_sock *sock6; /* IPv6 socket used for geneve tunnel */
> + struct geneve_sock __rcu *sock6; /* IPv6 socket used for geneve tunnel */
> #endif
> u8 vni[3]; /* virtual network ID for tunnel */
> u8 ttl; /* TTL override */
> @@ -543,9 +543,19 @@ static void __geneve_sock_release(struct geneve_sock *gs)
>
> static void geneve_sock_release(struct geneve_dev *geneve)
> {
> - __geneve_sock_release(geneve->sock4);
> + struct geneve_sock *gs4 = rtnl_dereference(geneve->sock4);
> #if IS_ENABLED(CONFIG_IPV6)
> - __geneve_sock_release(geneve->sock6);
> + struct geneve_sock *gs6 = rtnl_dereference(geneve->sock6);
> +
> + rcu_assign_pointer(geneve->sock6, NULL);
> +#endif
> +
> + rcu_assign_pointer(geneve->sock4, NULL);
> + synchronize_net();
> +
> + __geneve_sock_release(gs4);
> +#if IS_ENABLED(CONFIG_IPV6)
> + __geneve_sock_release(gs6);
> #endif
> }
>
> @@ -586,10 +596,10 @@ static int geneve_sock_add(struct geneve_dev *geneve, bool ipv6)
> gs->flags = geneve->flags;
> #if IS_ENABLED(CONFIG_IPV6)
> if (ipv6)
> - geneve->sock6 = gs;
> + rcu_assign_pointer(geneve->sock6, gs);
> else
> #endif
> - geneve->sock4 = gs;
> + rcu_assign_pointer(geneve->sock4, gs);
>
> hash = geneve_net_vni_hash(geneve->vni);
> hlist_add_head_rcu(&geneve->hlist, &gs->vni_list[hash]);
> @@ -603,9 +613,7 @@ static int geneve_open(struct net_device *dev)
> bool metadata = geneve->collect_md;
> int ret = 0;
>
> - geneve->sock4 = NULL;
> #if IS_ENABLED(CONFIG_IPV6)
> - geneve->sock6 = NULL;
> if (ipv6 || metadata)
> ret = geneve_sock_add(geneve, true);
> #endif
> @@ -720,6 +728,9 @@ static struct rtable *geneve_get_v4_rt(struct sk_buff *skb,
> struct rtable *rt = NULL;
> __u8 tos;
>
> + if (!rcu_dereference(geneve->sock4))
> + return ERR_PTR(-EIO);
> +
> memset(fl4, 0, sizeof(*fl4));
> fl4->flowi4_mark = skb->mark;
> fl4->flowi4_proto = IPPROTO_UDP;
> @@ -772,11 +783,15 @@ static struct dst_entry *geneve_get_v6_dst(struct sk_buff *skb,
> {
> bool use_cache = ip_tunnel_dst_cache_usable(skb, info);
> struct geneve_dev *geneve = netdev_priv(dev);
> - struct geneve_sock *gs6 = geneve->sock6;
> struct dst_entry *dst = NULL;
> struct dst_cache *dst_cache;
> + struct geneve_sock *gs6;
> __u8 prio;
>
> + gs6 = rcu_dereference(geneve->sock6);
> + if (!gs6)
> + return ERR_PTR(-EIO);
> +
> memset(fl6, 0, sizeof(*fl6));
> fl6->flowi6_mark = skb->mark;
> fl6->flowi6_proto = IPPROTO_UDP;
> @@ -842,7 +857,7 @@ static netdev_tx_t geneve_xmit_skb(struct sk_buff *skb, struct net_device *dev,
> struct ip_tunnel_info *info)
> {
> struct geneve_dev *geneve = netdev_priv(dev);
> - struct geneve_sock *gs4 = geneve->sock4;
> + struct geneve_sock *gs4;
> struct rtable *rt = NULL;
> const struct iphdr *iip; /* interior IP header */
> int err = -EINVAL;
> @@ -853,6 +868,10 @@ static netdev_tx_t geneve_xmit_skb(struct sk_buff *skb, struct net_device *dev,
> bool xnet = !net_eq(geneve->net, dev_net(geneve->dev));
> u32 flags = geneve->flags;
>
> + gs4 = rcu_dereference(geneve->sock4);
> + if (!gs4)
> + goto tx_error;
> +
> if (geneve->collect_md) {
> if (unlikely(!info || !(info->mode & IP_TUNNEL_INFO_TX))) {
> netdev_dbg(dev, "no tunnel metadata\n");
> @@ -932,9 +951,9 @@ static netdev_tx_t geneve6_xmit_skb(struct sk_buff *skb, struct net_device *dev,
> struct ip_tunnel_info *info)
> {
> struct geneve_dev *geneve = netdev_priv(dev);
> - struct geneve_sock *gs6 = geneve->sock6;
> struct dst_entry *dst = NULL;
> const struct iphdr *iip; /* interior IP header */
> + struct geneve_sock *gs6;
> int err = -EINVAL;
> struct flowi6 fl6;
> __u8 prio, ttl;
> @@ -943,6 +962,10 @@ static netdev_tx_t geneve6_xmit_skb(struct sk_buff *skb, struct net_device *dev,
> bool xnet = !net_eq(geneve->net, dev_net(geneve->dev));
> u32 flags = geneve->flags;
>
> + gs6 = rcu_dereference(geneve->sock6);
> + if (!gs6)
> + goto tx_error;
> +
> if (geneve->collect_md) {
> if (unlikely(!info || !(info->mode & IP_TUNNEL_INFO_TX))) {
> netdev_dbg(dev, "no tunnel metadata\n");
> --
> 1.9.1
>
>
--
John W. Linville Someday the world will need a hero, and you
linville@...driver.com might be all we have. Be ready.
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