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net: replace dst_cache ip6_tunnel implementation with the generic one

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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@redhat.com>
Suggested-and-acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Paolo Abeni
2016-02-12 15:43:54 +01:00
committed by David S. Miller
parent 911362c70d
commit 607f725f6f
5 changed files with 16 additions and 116 deletions
Download Patch File Download Diff File Expand all files Collapse all files

14
include/net/ip6_tunnel.h
View File

@@ -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,