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Message-Id: <b625c84cc67747a2ce519821ff6c52e63d2935f6.1455184959.git.pabeni@redhat.com>
Date: Thu, 11 Feb 2016 11:11:58 +0100
From: Paolo Abeni <pabeni@...hat.com>
To: netdev@...r.kernel.org
Cc: "David S. Miller" <davem@...emloft.net>,
Thomas Graf <tgraf@...g.ch>,
Pravin B Shelar <pshelar@...ira.com>,
Jiri Benc <jbenc@...hat.com>,
Hannes Frederic Sowa <hannes@...essinduktion.org>,
Tom Herbert <therbert@...gle.com>
Subject: [PATCH net-next 2/7] net: replace dst_cache ip6_tunnel implementation with the generic one
This also fix a potential race into the existing tunnel code, which
could lead to the wrong dst to be permanenty cached:
CPU1: CPU2:
<xmit on ip6_tunnel>
<cache lookup fails>
dst = ip6_route_output(...)
<tunnel params are changed via nl>
dst_cache_reset() // no effect,
// the cache is empty
dst_cache_set() // the wrong dst
// is permanenty stored
// into the cache
With the new dst implementation the above race is not possible
since the first cache lookup after dst_cache_reset will fail due
to the timestamp check
Signed-off-by: Paolo Abeni <pabeni@...hat.com>
Suggested-and-acked-by: Hannes Frederic Sowa <hannes@...essinduktion.org>
---
include/net/ip6_tunnel.h | 14 +------
net/ipv6/Kconfig | 1 +
net/ipv6/ip6_gre.c | 12 +++---
net/ipv6/ip6_tunnel.c | 103 +++--------------------------------------------
net/ipv6/ip6_vti.c | 2 +-
5 files changed, 16 insertions(+), 116 deletions(-)
diff --git a/include/net/ip6_tunnel.h b/include/net/ip6_tunnel.h
index 0d0ce0b..499a707 100644
--- a/include/net/ip6_tunnel.h
+++ b/include/net/ip6_tunnel.h
@@ -6,6 +6,7 @@
#include <linux/if_tunnel.h>
#include <linux/ip6_tunnel.h>
#include <net/ip_tunnels.h>
+#include <net/dst_cache.h>
#define IP6TUNNEL_ERR_TIMEO (30*HZ)
@@ -33,12 +34,6 @@ struct __ip6_tnl_parm {
__be32 o_key;
};
-struct ip6_tnl_dst {
- seqlock_t lock;
- struct dst_entry __rcu *dst;
- u32 cookie;
-};
-
/* IPv6 tunnel */
struct ip6_tnl {
struct ip6_tnl __rcu *next; /* next tunnel in list */
@@ -46,7 +41,7 @@ struct ip6_tnl {
struct net *net; /* netns for packet i/o */
struct __ip6_tnl_parm parms; /* tunnel configuration parameters */
struct flowi fl; /* flowi template for xmit */
- struct ip6_tnl_dst __percpu *dst_cache; /* cached dst */
+ struct dst_cache dst_cache; /* cached dst */
int err_count;
unsigned long err_time;
@@ -66,11 +61,6 @@ struct ipv6_tlv_tnl_enc_lim {
__u8 encap_limit; /* tunnel encapsulation limit */
} __packed;
-struct dst_entry *ip6_tnl_dst_get(struct ip6_tnl *t);
-int ip6_tnl_dst_init(struct ip6_tnl *t);
-void ip6_tnl_dst_destroy(struct ip6_tnl *t);
-void ip6_tnl_dst_reset(struct ip6_tnl *t);
-void ip6_tnl_dst_set(struct ip6_tnl *t, struct dst_entry *dst);
int ip6_tnl_rcv_ctl(struct ip6_tnl *t, const struct in6_addr *laddr,
const struct in6_addr *raddr);
int ip6_tnl_xmit_ctl(struct ip6_tnl *t, const struct in6_addr *laddr,
diff --git a/net/ipv6/Kconfig b/net/ipv6/Kconfig
index 40c8975..11e875f 100644
--- a/net/ipv6/Kconfig
+++ b/net/ipv6/Kconfig
@@ -207,6 +207,7 @@ config IPV6_NDISC_NODETYPE
config IPV6_TUNNEL
tristate "IPv6: IP-in-IPv6 tunnel (RFC2473)"
select INET6_TUNNEL
+ select DST_CACHE
---help---
Support for IPv6-in-IPv6 and IPv4-in-IPv6 tunnels described in
RFC 2473.
diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index f37f18b..a94e506 100644
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -360,7 +360,7 @@ static void ip6gre_tunnel_uninit(struct net_device *dev)
struct ip6gre_net *ign = net_generic(t->net, ip6gre_net_id);
ip6gre_tunnel_unlink(ign, t);
- ip6_tnl_dst_reset(t);
+ dst_cache_reset(&t->dst_cache);
dev_put(dev);
}
@@ -633,7 +633,7 @@ static netdev_tx_t ip6gre_xmit2(struct sk_buff *skb,
}
if (!fl6->flowi6_mark)
- dst = ip6_tnl_dst_get(tunnel);
+ dst = dst_cache_get(&tunnel->dst_cache);
if (!dst) {
dst = ip6_route_output(net, NULL, fl6);
@@ -702,7 +702,7 @@ static netdev_tx_t ip6gre_xmit2(struct sk_buff *skb,
}
if (!fl6->flowi6_mark && ndst)
- ip6_tnl_dst_set(tunnel, ndst);
+ dst_cache_set_ip6(&tunnel->dst_cache, ndst, &fl6->saddr);
skb_dst_set(skb, dst);
proto = NEXTHDR_GRE;
@@ -1009,7 +1009,7 @@ static int ip6gre_tnl_change(struct ip6_tnl *t,
t->parms.o_key = p->o_key;
t->parms.i_flags = p->i_flags;
t->parms.o_flags = p->o_flags;
- ip6_tnl_dst_reset(t);
+ dst_cache_reset(&t->dst_cache);
ip6gre_tnl_link_config(t, set_mtu);
return 0;
}
@@ -1219,7 +1219,7 @@ static void ip6gre_dev_free(struct net_device *dev)
{
struct ip6_tnl *t = netdev_priv(dev);
- ip6_tnl_dst_destroy(t);
+ dst_cache_destroy(&t->dst_cache);
free_percpu(dev->tstats);
free_netdev(dev);
}
@@ -1257,7 +1257,7 @@ static int ip6gre_tunnel_init_common(struct net_device *dev)
if (!dev->tstats)
return -ENOMEM;
- ret = ip6_tnl_dst_init(tunnel);
+ ret = dst_cache_init(&tunnel->dst_cache, GFP_KERNEL);
if (ret) {
free_percpu(dev->tstats);
dev->tstats = NULL;
diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index 137fca4..3f3aabd 100644
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -122,97 +122,6 @@ static struct net_device_stats *ip6_get_stats(struct net_device *dev)
return &dev->stats;
}
-/*
- * Locking : hash tables are protected by RCU and RTNL
- */
-
-static void ip6_tnl_per_cpu_dst_set(struct ip6_tnl_dst *idst,
- struct dst_entry *dst)
-{
- write_seqlock_bh(&idst->lock);
- dst_release(rcu_dereference_protected(
- idst->dst,
- lockdep_is_held(&idst->lock.lock)));
- if (dst) {
- dst_hold(dst);
- idst->cookie = rt6_get_cookie((struct rt6_info *)dst);
- } else {
- idst->cookie = 0;
- }
- rcu_assign_pointer(idst->dst, dst);
- write_sequnlock_bh(&idst->lock);
-}
-
-struct dst_entry *ip6_tnl_dst_get(struct ip6_tnl *t)
-{
- struct ip6_tnl_dst *idst;
- struct dst_entry *dst;
- unsigned int seq;
- u32 cookie;
-
- idst = raw_cpu_ptr(t->dst_cache);
-
- rcu_read_lock();
- do {
- seq = read_seqbegin(&idst->lock);
- dst = rcu_dereference(idst->dst);
- cookie = idst->cookie;
- } while (read_seqretry(&idst->lock, seq));
-
- if (dst && !atomic_inc_not_zero(&dst->__refcnt))
- dst = NULL;
- rcu_read_unlock();
-
- if (dst && dst->obsolete && !dst->ops->check(dst, cookie)) {
- ip6_tnl_per_cpu_dst_set(idst, NULL);
- dst_release(dst);
- dst = NULL;
- }
- return dst;
-}
-EXPORT_SYMBOL_GPL(ip6_tnl_dst_get);
-
-void ip6_tnl_dst_reset(struct ip6_tnl *t)
-{
- int i;
-
- for_each_possible_cpu(i)
- ip6_tnl_per_cpu_dst_set(per_cpu_ptr(t->dst_cache, i), NULL);
-}
-EXPORT_SYMBOL_GPL(ip6_tnl_dst_reset);
-
-void ip6_tnl_dst_set(struct ip6_tnl *t, struct dst_entry *dst)
-{
- ip6_tnl_per_cpu_dst_set(raw_cpu_ptr(t->dst_cache), dst);
-
-}
-EXPORT_SYMBOL_GPL(ip6_tnl_dst_set);
-
-void ip6_tnl_dst_destroy(struct ip6_tnl *t)
-{
- if (!t->dst_cache)
- return;
-
- ip6_tnl_dst_reset(t);
- free_percpu(t->dst_cache);
-}
-EXPORT_SYMBOL_GPL(ip6_tnl_dst_destroy);
-
-int ip6_tnl_dst_init(struct ip6_tnl *t)
-{
- int i;
-
- t->dst_cache = alloc_percpu(struct ip6_tnl_dst);
- if (!t->dst_cache)
- return -ENOMEM;
-
- for_each_possible_cpu(i)
- seqlock_init(&per_cpu_ptr(t->dst_cache, i)->lock);
-
- return 0;
-}
-EXPORT_SYMBOL_GPL(ip6_tnl_dst_init);
-
/**
* ip6_tnl_lookup - fetch tunnel matching the end-point addresses
* @remote: the address of the tunnel exit-point
@@ -329,7 +238,7 @@ static void ip6_dev_free(struct net_device *dev)
{
struct ip6_tnl *t = netdev_priv(dev);
- ip6_tnl_dst_destroy(t);
+ dst_cache_destroy(&t->dst_cache);
free_percpu(dev->tstats);
free_netdev(dev);
}
@@ -462,7 +371,7 @@ ip6_tnl_dev_uninit(struct net_device *dev)
RCU_INIT_POINTER(ip6n->tnls_wc[0], NULL);
else
ip6_tnl_unlink(ip6n, t);
- ip6_tnl_dst_reset(t);
+ dst_cache_reset(&t->dst_cache);
dev_put(dev);
}
@@ -1069,7 +978,7 @@ static int ip6_tnl_xmit2(struct sk_buff *skb,
memcpy(&fl6->daddr, addr6, sizeof(fl6->daddr));
neigh_release(neigh);
} else if (!fl6->flowi6_mark)
- dst = ip6_tnl_dst_get(t);
+ dst = dst_cache_get(&t->dst_cache);
if (!ip6_tnl_xmit_ctl(t, &fl6->saddr, &fl6->daddr))
goto tx_err_link_failure;
@@ -1133,7 +1042,7 @@ static int ip6_tnl_xmit2(struct sk_buff *skb,
}
if (!fl6->flowi6_mark && ndst)
- ip6_tnl_dst_set(t, ndst);
+ dst_cache_set_ip6(&t->dst_cache, ndst, &fl6->saddr);
skb_dst_set(skb, dst);
skb->transport_header = skb->network_header;
@@ -1366,7 +1275,7 @@ ip6_tnl_change(struct ip6_tnl *t, const struct __ip6_tnl_parm *p)
t->parms.flowinfo = p->flowinfo;
t->parms.link = p->link;
t->parms.proto = p->proto;
- ip6_tnl_dst_reset(t);
+ dst_cache_reset(&t->dst_cache);
ip6_tnl_link_config(t);
return 0;
}
@@ -1637,7 +1546,7 @@ ip6_tnl_dev_init_gen(struct net_device *dev)
if (!dev->tstats)
return -ENOMEM;
- ret = ip6_tnl_dst_init(t);
+ ret = dst_cache_init(&t->dst_cache, GFP_KERNEL);
if (ret) {
free_percpu(dev->tstats);
dev->tstats = NULL;
diff --git a/net/ipv6/ip6_vti.c b/net/ipv6/ip6_vti.c
index 0a8610b..d90a11f 100644
--- a/net/ipv6/ip6_vti.c
+++ b/net/ipv6/ip6_vti.c
@@ -640,7 +640,7 @@ vti6_tnl_change(struct ip6_tnl *t, const struct __ip6_tnl_parm *p)
t->parms.i_key = p->i_key;
t->parms.o_key = p->o_key;
t->parms.proto = p->proto;
- ip6_tnl_dst_reset(t);
+ dst_cache_reset(&t->dst_cache);
vti6_link_config(t);
return 0;
}
--
1.8.3.1
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