netdev - [PATCH net] ipv6: use rt6_info members when dst is set in rt6_fill

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Message-Id: <840f0c017c670ae9cc8fd8330ca24fcca1207918.1536398641.git.lucien.xin@gmail.com>
Date:   Sat,  8 Sep 2018 17:24:01 +0800
From:   Xin Long <lucien.xin@...il.com>
To:     network dev <netdev@...r.kernel.org>
Cc:     davem@...emloft.net, David Ahern <dsa@...ulusnetworks.com>,
        Roopa Prabhu <roopa@...ulusnetworks.com>
Subject: [PATCH net] ipv6: use rt6_info members when dst is set in rt6_fill_node

In inet6_rtm_getroute, since Commit 93531c674315 ("net/ipv6: separate
handling of FIB entries from dst based routes"), it has used rt->from
to dump route info instead of rt.

However for some route like cache, its information is not the same as
that of the 'from' one. It caused 'ip -6 route get' to dump the wrong
route information.

In Jianlin's testing, the output information even lost the expiration
time for a pmtu route cache due to the wrong fib6_flags.

So change to use rt6_info members when it tries to dump a route entry
without fibmatch set.

Note that we will fix the gw/nh dump in another patch.

Fixes: 93531c674315 ("net/ipv6: separate handling of FIB entries from dst based routes")
Reported-by: Jianlin Shi <jishi@...hat.com>
Signed-off-by: Xin Long <lucien.xin@...il.com>
---
 net/ipv6/route.c | 39 ++++++++++++++++++++++++++-------------
 1 file changed, 26 insertions(+), 13 deletions(-)

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 18e00ce..e554922 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -4670,20 +4670,33 @@ static int rt6_fill_node(struct net *net, struct sk_buff *skb,
 			 int iif, int type, u32 portid, u32 seq,
 			 unsigned int flags)
 {
-	struct rtmsg *rtm;
+	struct rt6key *fib6_prefsrc, *fib6_dst, *fib6_src;
+	struct rt6_info *rt6 = (struct rt6_info *)dst;
+	u32 *pmetrics, table, fib6_flags;
 	struct nlmsghdr *nlh;
+	struct rtmsg *rtm;
 	long expires = 0;
-	u32 *pmetrics;
-	u32 table;
 
 	nlh = nlmsg_put(skb, portid, seq, type, sizeof(*rtm), flags);
 	if (!nlh)
 		return -EMSGSIZE;
 
+	if (rt6) {
+		fib6_dst = &rt6->rt6i_dst;
+		fib6_src = &rt6->rt6i_src;
+		fib6_flags = rt6->rt6i_flags;
+		fib6_prefsrc = &rt6->rt6i_prefsrc;
+	} else {
+		fib6_dst = &rt->fib6_dst;
+		fib6_src = &rt->fib6_src;
+		fib6_flags = rt->fib6_flags;
+		fib6_prefsrc = &rt->fib6_prefsrc;
+	}
+
 	rtm = nlmsg_data(nlh);
 	rtm->rtm_family = AF_INET6;
-	rtm->rtm_dst_len = rt->fib6_dst.plen;
-	rtm->rtm_src_len = rt->fib6_src.plen;
+	rtm->rtm_dst_len = fib6_dst->plen;
+	rtm->rtm_src_len = fib6_src->plen;
 	rtm->rtm_tos = 0;
 	if (rt->fib6_table)
 		table = rt->fib6_table->tb6_id;
@@ -4698,7 +4711,7 @@ static int rt6_fill_node(struct net *net, struct sk_buff *skb,
 	rtm->rtm_scope = RT_SCOPE_UNIVERSE;
 	rtm->rtm_protocol = rt->fib6_protocol;
 
-	if (rt->fib6_flags & RTF_CACHE)
+	if (fib6_flags & RTF_CACHE)
 		rtm->rtm_flags |= RTM_F_CLONED;
 
 	if (dest) {
@@ -4706,7 +4719,7 @@ static int rt6_fill_node(struct net *net, struct sk_buff *skb,
 			goto nla_put_failure;
 		rtm->rtm_dst_len = 128;
 	} else if (rtm->rtm_dst_len)
-		if (nla_put_in6_addr(skb, RTA_DST, &rt->fib6_dst.addr))
+		if (nla_put_in6_addr(skb, RTA_DST, &fib6_dst->addr))
 			goto nla_put_failure;
 #ifdef CONFIG_IPV6_SUBTREES
 	if (src) {
@@ -4714,12 +4727,12 @@ static int rt6_fill_node(struct net *net, struct sk_buff *skb,
 			goto nla_put_failure;
 		rtm->rtm_src_len = 128;
 	} else if (rtm->rtm_src_len &&
-		   nla_put_in6_addr(skb, RTA_SRC, &rt->fib6_src.addr))
+		   nla_put_in6_addr(skb, RTA_SRC, &fib6_src->addr))
 		goto nla_put_failure;
 #endif
 	if (iif) {
 #ifdef CONFIG_IPV6_MROUTE
-		if (ipv6_addr_is_multicast(&rt->fib6_dst.addr)) {
+		if (ipv6_addr_is_multicast(&fib6_dst->addr)) {
 			int err = ip6mr_get_route(net, skb, rtm, portid);
 
 			if (err == 0)
@@ -4737,9 +4750,9 @@ static int rt6_fill_node(struct net *net, struct sk_buff *skb,
 			goto nla_put_failure;
 	}
 
-	if (rt->fib6_prefsrc.plen) {
+	if (fib6_prefsrc->plen) {
 		struct in6_addr saddr_buf;
-		saddr_buf = rt->fib6_prefsrc.addr;
+		saddr_buf = fib6_prefsrc->addr;
 		if (nla_put_in6_addr(skb, RTA_PREFSRC, &saddr_buf))
 			goto nla_put_failure;
 	}
@@ -4777,7 +4790,7 @@ static int rt6_fill_node(struct net *net, struct sk_buff *skb,
 			goto nla_put_failure;
 	}
 
-	if (rt->fib6_flags & RTF_EXPIRES) {
+	if (fib6_flags & RTF_EXPIRES) {
 		expires = dst ? dst->expires : rt->expires;
 		expires -= jiffies;
 	}
@@ -4785,7 +4798,7 @@ static int rt6_fill_node(struct net *net, struct sk_buff *skb,
 	if (rtnl_put_cacheinfo(skb, dst, 0, expires, dst ? dst->error : 0) < 0)
 		goto nla_put_failure;
 
-	if (nla_put_u8(skb, RTA_PREF, IPV6_EXTRACT_PREF(rt->fib6_flags)))
+	if (nla_put_u8(skb, RTA_PREF, IPV6_EXTRACT_PREF(fib6_flags)))
 		goto nla_put_failure;
 
 
-- 
2.1.0