From 0d3f6d297bfb7af24d0508460fdb3d1ec4903fa3 Mon Sep 17 00:00:00 2001 From: Martin KaFai Lau Date: Wed, 11 Nov 2015 11:51:06 -0800 Subject: ipv6: Avoid creating RTF_CACHE from a rt that is not managed by fib6 tree The original bug report: https://bugzilla.redhat.com/show_bug.cgi?id=1272571 The setup has a IPv4 GRE tunnel running in a IPSec. The bug happens when ndisc starts sending router solicitation at the gre interface. The simplified oops stack is like: __lock_acquire+0x1b2/0x1c30 lock_acquire+0xb9/0x140 _raw_write_lock_bh+0x3f/0x50 __ip6_ins_rt+0x2e/0x60 ip6_ins_rt+0x49/0x50 ~~~~~~~~ __ip6_rt_update_pmtu.part.54+0x145/0x250 ip6_rt_update_pmtu+0x2e/0x40 ~~~~~~~~ ip_tunnel_xmit+0x1f1/0xf40 __gre_xmit+0x7a/0x90 ipgre_xmit+0x15a/0x220 dev_hard_start_xmit+0x2bd/0x480 __dev_queue_xmit+0x696/0x730 dev_queue_xmit+0x10/0x20 neigh_direct_output+0x11/0x20 ip6_finish_output2+0x21f/0x770 ip6_finish_output+0xa7/0x1d0 ip6_output+0x56/0x190 ~~~~~~~~ ndisc_send_skb+0x1d9/0x400 ndisc_send_rs+0x88/0xc0 ~~~~~~~~ The rt passed to ip6_rt_update_pmtu() is created by icmp6_dst_alloc() and it is not managed by the fib6 tree, so its rt6i_table == NULL. When __ip6_rt_update_pmtu() creates a RTF_CACHE clone, the newly created clone also has rt6i_table == NULL and it causes the ip6_ins_rt() oops. During pmtu update, we only want to create a RTF_CACHE clone from a rt which is currently managed (or owned) by the fib6 tree. It means either rt->rt6i_node != NULL or rt is a RTF_PCPU clone. It is worth to note that rt6i_table may not be NULL even it is not (yet) managed by the fib6 tree (e.g. addrconf_dst_alloc()). Hence, rt6i_node is a better check instead of rt6i_table. Fixes: 45e4fd26683c ("ipv6: Only create RTF_CACHE routes after encountering pmtu") Signed-off-by: Martin KaFai Lau Reported-by: Chris Siebenmann Cc: Chris Siebenmann Cc: Hannes Frederic Sowa Signed-off-by: David S. Miller --- net/ipv6/route.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/net/ipv6/route.c b/net/ipv6/route.c index c8bc9b4ac328..74907c58a5c7 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -1322,6 +1322,12 @@ static void rt6_do_update_pmtu(struct rt6_info *rt, u32 mtu) rt6_update_expires(rt, net->ipv6.sysctl.ip6_rt_mtu_expires); } +static bool rt6_cache_allowed_for_pmtu(const struct rt6_info *rt) +{ + return !(rt->rt6i_flags & RTF_CACHE) && + (rt->rt6i_flags & RTF_PCPU || rt->rt6i_node); +} + static void __ip6_rt_update_pmtu(struct dst_entry *dst, const struct sock *sk, const struct ipv6hdr *iph, u32 mtu) { @@ -1335,7 +1341,7 @@ static void __ip6_rt_update_pmtu(struct dst_entry *dst, const struct sock *sk, if (mtu >= dst_mtu(dst)) return; - if (rt6->rt6i_flags & RTF_CACHE) { + if (!rt6_cache_allowed_for_pmtu(rt6)) { rt6_do_update_pmtu(rt6, mtu); } else { const struct in6_addr *daddr, *saddr; -- cgit v1.2.3-55-g7522 From 5973fb1e245086071bf71994c8b54d99526ded03 Mon Sep 17 00:00:00 2001 From: Martin KaFai Lau Date: Wed, 11 Nov 2015 11:51:07 -0800 Subject: ipv6: Check expire on DST_NOCACHE route Since the expires of the DST_NOCACHE rt can be set during the ip6_rt_update_pmtu(), we also need to consider the expires value when doing ip6_dst_check(). This patches creates __rt6_check_expired() to only check the expire value (if one exists) of the current rt. In rt6_dst_from_check(), it adds __rt6_check_expired() as one of the condition check. Signed-off-by: Martin KaFai Lau Cc: Hannes Frederic Sowa Signed-off-by: David S. Miller --- net/ipv6/route.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/net/ipv6/route.c b/net/ipv6/route.c index 74907c58a5c7..3754cf9287a0 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -404,6 +404,14 @@ static void ip6_dst_ifdown(struct dst_entry *dst, struct net_device *dev, } } +static bool __rt6_check_expired(const struct rt6_info *rt) +{ + if (rt->rt6i_flags & RTF_EXPIRES) + return time_after(jiffies, rt->dst.expires); + else + return false; +} + static bool rt6_check_expired(const struct rt6_info *rt) { if (rt->rt6i_flags & RTF_EXPIRES) { @@ -1252,7 +1260,8 @@ static struct dst_entry *rt6_check(struct rt6_info *rt, u32 cookie) static struct dst_entry *rt6_dst_from_check(struct rt6_info *rt, u32 cookie) { - if (rt->dst.obsolete == DST_OBSOLETE_FORCE_CHK && + if (!__rt6_check_expired(rt) && + rt->dst.obsolete == DST_OBSOLETE_FORCE_CHK && rt6_check((struct rt6_info *)(rt->dst.from), cookie)) return &rt->dst; else -- cgit v1.2.3-55-g7522 From 02bcf4e082e4dc634409a6a6cb7def8806d6e5e6 Mon Sep 17 00:00:00 2001 From: Martin KaFai Lau Date: Wed, 11 Nov 2015 11:51:08 -0800 Subject: ipv6: Check rt->dst.from for the DST_NOCACHE route All DST_NOCACHE rt6_info used to have rt->dst.from set to its parent. After commit 8e3d5be73681 ("ipv6: Avoid double dst_free"), DST_NOCACHE is also set to rt6_info which does not have a parent (i.e. rt->dst.from is NULL). This patch catches the rt->dst.from == NULL case. Fixes: 8e3d5be73681 ("ipv6: Avoid double dst_free") Signed-off-by: Martin KaFai Lau Cc: Hannes Frederic Sowa Signed-off-by: David S. Miller --- include/net/ip6_fib.h | 3 ++- net/ipv6/route.c | 3 ++- 2 files changed, 4 insertions(+), 2 deletions(-) diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h index aaf9700fc9e5..fb961a576abe 100644 --- a/include/net/ip6_fib.h +++ b/include/net/ip6_fib.h @@ -167,7 +167,8 @@ static inline void rt6_update_expires(struct rt6_info *rt0, int timeout) static inline u32 rt6_get_cookie(const struct rt6_info *rt) { - if (rt->rt6i_flags & RTF_PCPU || unlikely(rt->dst.flags & DST_NOCACHE)) + if (rt->rt6i_flags & RTF_PCPU || + (unlikely(rt->dst.flags & DST_NOCACHE) && rt->dst.from)) rt = (struct rt6_info *)(rt->dst.from); return rt->rt6i_node ? rt->rt6i_node->fn_sernum : 0; diff --git a/net/ipv6/route.c b/net/ipv6/route.c index 3754cf9287a0..6f01fe122abd 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -1281,7 +1281,8 @@ static struct dst_entry *ip6_dst_check(struct dst_entry *dst, u32 cookie) rt6_dst_from_metrics_check(rt); - if ((rt->rt6i_flags & RTF_PCPU) || unlikely(dst->flags & DST_NOCACHE)) + if (rt->rt6i_flags & RTF_PCPU || + (unlikely(dst->flags & DST_NOCACHE) && rt->dst.from)) return rt6_dst_from_check(rt, cookie); else return rt6_check(rt, cookie); -- cgit v1.2.3-55-g7522