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ipv6: fix src addr routing with the exception table
[ Upstream commit510e2ceda0
] When inserting route cache into the exception table, the key is generated with both src_addr and dest_addr with src addr routing. However, current logic always assumes the src_addr used to generate the key is a /128 host address. This is not true in the following scenarios: 1. When the route is a gateway route or does not have next hop. (rt6_is_gw_or_nonexthop() == false) 2. When calling ip6_rt_cache_alloc(), saddr is passed in as NULL. This means, when looking for a route cache in the exception table, we have to do the lookup twice: first time with the passed in /128 host address, second time with the src_addr stored in fib6_info. This solves the pmtu discovery issue reported by Mikael Magnusson where a route cache with a lower mtu info is created for a gateway route with src addr. However, the lookup code is not able to find this route cache. Fixes:2b760fcf5c
("ipv6: hook up exception table to store dst cache") Reported-by: Mikael Magnusson <mikael.kernel@lists.m7n.se> Bisected-by: David Ahern <dsahern@gmail.com> Signed-off-by: Wei Wang <weiwan@google.com> Cc: Martin Lau <kafai@fb.com> Cc: Eric Dumazet <edumazet@google.com> Acked-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
parent
c3a0725977
commit
81a61a9581
1 changed files with 27 additions and 24 deletions
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@ -110,8 +110,8 @@ static int rt6_fill_node(struct net *net, struct sk_buff *skb,
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int iif, int type, u32 portid, u32 seq,
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unsigned int flags);
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static struct rt6_info *rt6_find_cached_rt(struct fib6_info *rt,
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struct in6_addr *daddr,
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struct in6_addr *saddr);
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const struct in6_addr *daddr,
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const struct in6_addr *saddr);
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#ifdef CONFIG_IPV6_ROUTE_INFO
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static struct fib6_info *rt6_add_route_info(struct net *net,
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@ -1542,31 +1542,44 @@ void rt6_flush_exceptions(struct fib6_info *rt)
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* Caller has to hold rcu_read_lock()
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*/
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static struct rt6_info *rt6_find_cached_rt(struct fib6_info *rt,
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struct in6_addr *daddr,
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struct in6_addr *saddr)
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const struct in6_addr *daddr,
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const struct in6_addr *saddr)
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{
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const struct in6_addr *src_key = NULL;
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struct rt6_exception_bucket *bucket;
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struct in6_addr *src_key = NULL;
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struct rt6_exception *rt6_ex;
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struct rt6_info *res = NULL;
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bucket = rcu_dereference(rt->rt6i_exception_bucket);
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#ifdef CONFIG_IPV6_SUBTREES
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/* rt6i_src.plen != 0 indicates rt is in subtree
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* and exception table is indexed by a hash of
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* both rt6i_dst and rt6i_src.
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* Otherwise, the exception table is indexed by
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* a hash of only rt6i_dst.
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* However, the src addr used to create the hash
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* might not be exactly the passed in saddr which
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* is a /128 addr from the flow.
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* So we need to use f6i->fib6_src to redo lookup
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* if the passed in saddr does not find anything.
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* (See the logic in ip6_rt_cache_alloc() on how
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* rt->rt6i_src is updated.)
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*/
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if (rt->fib6_src.plen)
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src_key = saddr;
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find_ex:
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#endif
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bucket = rcu_dereference(rt->rt6i_exception_bucket);
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rt6_ex = __rt6_find_exception_rcu(&bucket, daddr, src_key);
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if (rt6_ex && !rt6_check_expired(rt6_ex->rt6i))
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res = rt6_ex->rt6i;
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#ifdef CONFIG_IPV6_SUBTREES
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/* Use fib6_src as src_key and redo lookup */
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if (!res && src_key && src_key != &rt->fib6_src.addr) {
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src_key = &rt->fib6_src.addr;
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goto find_ex;
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}
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#endif
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return res;
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}
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@ -2650,10 +2663,8 @@ static unsigned int ip6_mtu(const struct dst_entry *dst)
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u32 ip6_mtu_from_fib6(struct fib6_info *f6i, struct in6_addr *daddr,
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struct in6_addr *saddr)
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{
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struct rt6_exception_bucket *bucket;
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struct rt6_exception *rt6_ex;
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struct in6_addr *src_key;
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struct inet6_dev *idev;
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struct rt6_info *rt;
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u32 mtu = 0;
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if (unlikely(fib6_metric_locked(f6i, RTAX_MTU))) {
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@ -2662,18 +2673,10 @@ u32 ip6_mtu_from_fib6(struct fib6_info *f6i, struct in6_addr *daddr,
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goto out;
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}
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src_key = NULL;
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#ifdef CONFIG_IPV6_SUBTREES
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if (f6i->fib6_src.plen)
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src_key = saddr;
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#endif
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bucket = rcu_dereference(f6i->rt6i_exception_bucket);
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rt6_ex = __rt6_find_exception_rcu(&bucket, daddr, src_key);
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if (rt6_ex && !rt6_check_expired(rt6_ex->rt6i))
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mtu = dst_metric_raw(&rt6_ex->rt6i->dst, RTAX_MTU);
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if (likely(!mtu)) {
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rt = rt6_find_cached_rt(f6i, daddr, saddr);
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if (unlikely(rt)) {
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mtu = dst_metric_raw(&rt->dst, RTAX_MTU);
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} else {
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struct net_device *dev = fib6_info_nh_dev(f6i);
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mtu = IPV6_MIN_MTU;
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