4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Paolo Abeni pabeni@redhat.com
commit 607f725f6f7d5ec3759fbc16224afb60e2152a5b upstream.
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 Signed-off-by: Manoj Boopathi Raj manojboopathi@google.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- include/net/ip6_tunnel.h | 15 ---- net/ipv6/Kconfig | 1 net/ipv6/ip6_gre.c | 12 +-- net/ipv6/ip6_tunnel.c | 151 +++++++---------------------------------------- net/ipv6/ip6_vti.c | 2 5 files changed, 35 insertions(+), 146 deletions(-)
--- a/include/net/ip6_tunnel.h +++ b/include/net/ip6_tunnel.h @@ -5,6 +5,8 @@ #include <linux/netdevice.h> #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)
@@ -32,12 +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 */ @@ -45,7 +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; @@ -65,11 +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, --- a/net/ipv6/Kconfig +++ b/net/ipv6/Kconfig @@ -205,6 +205,7 @@ 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. --- a/net/ipv6/ip6_gre.c +++ b/net/ipv6/ip6_gre.c @@ -362,7 +362,7 @@ static void ip6gre_tunnel_uninit(struct 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); }
@@ -640,7 +640,7 @@ static netdev_tx_t ip6gre_xmit2(struct s }
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); @@ -709,7 +709,7 @@ static netdev_tx_t ip6gre_xmit2(struct s }
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; @@ -1017,7 +1017,7 @@ static int ip6gre_tnl_change(struct ip6_ 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; } @@ -1228,7 +1228,7 @@ static void ip6gre_dev_free(struct net_d { 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); } @@ -1266,7 +1266,7 @@ static int ip6gre_tunnel_init_common(str 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; --- a/net/ipv6/ip6_tunnel.c +++ b/net/ipv6/ip6_tunnel.c @@ -122,97 +122,6 @@ static struct net_device_stats *ip6_get_ 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 @@ -331,7 +240,7 @@ static void ip6_dev_free(struct net_devi { 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); } @@ -464,7 +373,7 @@ ip6_tnl_dev_uninit(struct net_device *de 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); }
@@ -1053,7 +962,6 @@ static int ip6_tnl_xmit2(struct sk_buff struct ipv6_tel_txoption opt; struct dst_entry *dst = NULL, *ndst = NULL; struct net_device *tdev; - bool use_cache = false; int mtu; unsigned int max_headroom = sizeof(struct ipv6hdr); u8 proto; @@ -1061,39 +969,28 @@ static int ip6_tnl_xmit2(struct sk_buff
/* NBMA tunnel */ if (ipv6_addr_any(&t->parms.raddr)) { - if (skb->protocol == htons(ETH_P_IPV6)) { - struct in6_addr *addr6; - struct neighbour *neigh; - int addr_type; - - if (!skb_dst(skb)) - goto tx_err_link_failure; - - neigh = dst_neigh_lookup(skb_dst(skb), - &ipv6_hdr(skb)->daddr); - if (!neigh) - goto tx_err_link_failure; + struct in6_addr *addr6; + struct neighbour *neigh; + int addr_type; + + if (!skb_dst(skb)) + goto tx_err_link_failure;
- addr6 = (struct in6_addr *)&neigh->primary_key; - addr_type = ipv6_addr_type(addr6); + neigh = dst_neigh_lookup(skb_dst(skb), + &ipv6_hdr(skb)->daddr); + if (!neigh) + goto tx_err_link_failure;
- if (addr_type == IPV6_ADDR_ANY) - addr6 = &ipv6_hdr(skb)->daddr; + addr6 = (struct in6_addr *)&neigh->primary_key; + addr_type = ipv6_addr_type(addr6);
- memcpy(&fl6->daddr, addr6, sizeof(fl6->daddr)); - neigh_release(neigh); - } - } else if (t->parms.proto != 0 && !(t->parms.flags & - (IP6_TNL_F_USE_ORIG_TCLASS | - IP6_TNL_F_USE_ORIG_FWMARK))) { - /* enable the cache only if neither the outer protocol nor the - * routing decision depends on the current inner header value - */ - use_cache = true; - } + if (addr_type == IPV6_ADDR_ANY) + addr6 = &ipv6_hdr(skb)->daddr;
- if (use_cache) - dst = ip6_tnl_dst_get(t); + memcpy(&fl6->daddr, addr6, sizeof(fl6->daddr)); + neigh_release(neigh); + } else if (!fl6->flowi6_mark) + dst = dst_cache_get(&t->dst_cache);
if (!ip6_tnl_xmit_ctl(t, &fl6->saddr, &fl6->daddr)) goto tx_err_link_failure; @@ -1156,8 +1053,8 @@ static int ip6_tnl_xmit2(struct sk_buff skb = new_skb; }
- if (use_cache && ndst) - ip6_tnl_dst_set(t, ndst); + if (!fl6->flowi6_mark && ndst) + dst_cache_set_ip6(&t->dst_cache, ndst, &fl6->saddr); skb_dst_set(skb, dst);
skb->transport_header = skb->network_header; @@ -1392,7 +1289,7 @@ ip6_tnl_change(struct ip6_tnl *t, const 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; } @@ -1663,7 +1560,7 @@ ip6_tnl_dev_init_gen(struct net_device * 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; --- a/net/ipv6/ip6_vti.c +++ b/net/ipv6/ip6_vti.c @@ -645,7 +645,7 @@ vti6_tnl_change(struct ip6_tnl *t, const 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; }