[PATCH net v3] net: ipv4: Fix rtnexthop len when RTA_FLOW is present

[PATCH net v3] net: ipv4: Fix rtnexthop len when RTA_FLOW is present

[Xiao Liang]

Multipath RTA_FLOW is embedded in nexthop. Dump it in fib_add_nexthop()
to get the length of rtnexthop correct.

Fixes: b0f60193632e ("ipv4: Refactor nexthop attributes in fib_dump_info")
Signed-off-by: Xiao Liang <shaw.leon@gmail.com>
---
 include/net/ip_fib.h     |  2 +-
 include/net/nexthop.h    |  2 +-
 net/ipv4/fib_semantics.c | 16 +++++++++-------
 net/ipv6/route.c         |  5 +++--
 4 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/include/net/ip_fib.h b/include/net/ip_fib.h
index 21c5386d4a6d..ab5348e57db1 100644
--- a/include/net/ip_fib.h
+++ b/include/net/ip_fib.h
@@ -597,5 +597,5 @@ int ip_valid_fib_dump_req(struct net *net, const struct nlmsghdr *nlh,
 int fib_nexthop_info(struct sk_buff *skb, const struct fib_nh_common *nh,
 		     u8 rt_family, unsigned char *flags, bool skip_oif);
 int fib_add_nexthop(struct sk_buff *skb, const struct fib_nh_common *nh,
-		    int nh_weight, u8 rt_family);
+		    int nh_weight, u8 rt_family, u32 nh_tclassid);
 #endif  /* _NET_FIB_H */
diff --git a/include/net/nexthop.h b/include/net/nexthop.h
index 10e1777877e6..28085b995ddc 100644
--- a/include/net/nexthop.h
+++ b/include/net/nexthop.h
@@ -325,7 +325,7 @@ int nexthop_mpath_fill_node(struct sk_buff *skb, struct nexthop *nh,
 		struct fib_nh_common *nhc = &nhi->fib_nhc;
 		int weight = nhg->nh_entries[i].weight;
 
-		if (fib_add_nexthop(skb, nhc, weight, rt_family) < 0)
+		if (fib_add_nexthop(skb, nhc, weight, rt_family, 0) < 0)
 			return -EMSGSIZE;
 	}
 
diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index b42c429cebbe..3364cb9c67e0 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -1661,7 +1661,7 @@ EXPORT_SYMBOL_GPL(fib_nexthop_info);
 
 #if IS_ENABLED(CONFIG_IP_ROUTE_MULTIPATH) || IS_ENABLED(CONFIG_IPV6)
 int fib_add_nexthop(struct sk_buff *skb, const struct fib_nh_common *nhc,
-		    int nh_weight, u8 rt_family)
+		    int nh_weight, u8 rt_family, u32 nh_tclassid)
 {
 	const struct net_device *dev = nhc->nhc_dev;
 	struct rtnexthop *rtnh;
@@ -1679,6 +1679,9 @@ int fib_add_nexthop(struct sk_buff *skb, const struct fib_nh_common *nhc,
 
 	rtnh->rtnh_flags = flags;
 
+	if (nh_tclassid && nla_put_u32(skb, RTA_FLOW, nh_tclassid))
+		goto nla_put_failure;
+
 	/* length of rtnetlink header + attributes */
 	rtnh->rtnh_len = nlmsg_get_pos(skb) - (void *)rtnh;
 
@@ -1706,14 +1709,13 @@ static int fib_add_multipath(struct sk_buff *skb, struct fib_info *fi)
 	}
 
 	for_nexthops(fi) {
-		if (fib_add_nexthop(skb, &nh->nh_common, nh->fib_nh_weight,
-				    AF_INET) < 0)
-			goto nla_put_failure;
+		u32 nh_tclassid = 0;
 #ifdef CONFIG_IP_ROUTE_CLASSID
-		if (nh->nh_tclassid &&
-		    nla_put_u32(skb, RTA_FLOW, nh->nh_tclassid))
-			goto nla_put_failure;
+		nh_tclassid = nh->nh_tclassid;
 #endif
+		if (fib_add_nexthop(skb, &nh->nh_common, nh->fib_nh_weight,
+				    AF_INET, nh_tclassid) < 0)
+			goto nla_put_failure;
 	} endfor_nexthops(fi);
 
 mp_end:
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index dbc224023977..9b9ef09382ab 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -5681,14 +5681,15 @@ static int rt6_fill_node(struct net *net, struct sk_buff *skb,
 			goto nla_put_failure;
 
 		if (fib_add_nexthop(skb, &rt->fib6_nh->nh_common,
-				    rt->fib6_nh->fib_nh_weight, AF_INET6) < 0)
+				    rt->fib6_nh->fib_nh_weight, AF_INET6,
+				    0) < 0)
 			goto nla_put_failure;
 
 		list_for_each_entry_safe(sibling, next_sibling,
 					 &rt->fib6_siblings, fib6_siblings) {
 			if (fib_add_nexthop(skb, &sibling->fib6_nh->nh_common,
 					    sibling->fib6_nh->fib_nh_weight,
-					    AF_INET6) < 0)
+					    AF_INET6, 0) < 0)
 				goto nla_put_failure;
 		}
 
-- 
2.33.0

Re: [PATCH net v3] net: ipv4: Fix rtnexthop len when RTA_FLOW is present

[David Ahern]

On 9/23/21 9:03 AM, Xiao Liang wrote:
> Multipath RTA_FLOW is embedded in nexthop. Dump it in fib_add_nexthop()
> to get the length of rtnexthop correct.
> 
> Fixes: b0f60193632e ("ipv4: Refactor nexthop attributes in fib_dump_info")
> Signed-off-by: Xiao Liang <shaw.leon@gmail.com>
> ---
>  include/net/ip_fib.h     |  2 +-
>  include/net/nexthop.h    |  2 +-
>  net/ipv4/fib_semantics.c | 16 +++++++++-------
>  net/ipv6/route.c         |  5 +++--
>  4 files changed, 14 insertions(+), 11 deletions(-)
> 

Reviewed-by: David Ahern <dsahern@kernel.org>

Re: [PATCH net v3] net: ipv4: Fix rtnexthop len when RTA_FLOW is present

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (refs/heads/master):

On Thu, 23 Sep 2021 23:03:19 +0800 you wrote:
> Multipath RTA_FLOW is embedded in nexthop. Dump it in fib_add_nexthop()
> to get the length of rtnexthop correct.
> 
> Fixes: b0f60193632e ("ipv4: Refactor nexthop attributes in fib_dump_info")
> Signed-off-by: Xiao Liang <shaw.leon@gmail.com>
> ---
>  include/net/ip_fib.h     |  2 +-
>  include/net/nexthop.h    |  2 +-
>  net/ipv4/fib_semantics.c | 16 +++++++++-------
>  net/ipv6/route.c         |  5 +++--
>  4 files changed, 14 insertions(+), 11 deletions(-)

Here is the summary with links:
  - [net,v3] net: ipv4: Fix rtnexthop len when RTA_FLOW is present
    https://git.kernel.org/netdev/net/c/597aa16c7824

You are awesome, thank you!
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