[PATCH] net/ipv4: swap flow ports when validating source

When doing source address validation, the flowi4 struct used for
fib_lookup should be in the reverse direction to the given skb.
fl4_dport and fl4_sport returned by fib4_rules_early_flow_dissect
should thus be swapped.

Fixes: 5a847a6 ("net/ipv4: Initialize proto and ports in flow struct")
Signed-off-by: Miao Wang <redacted>
---
 net/ipv4/fib_frontend.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index 84bb707bd88d..647bceab56c2 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c

@@ -371,6 +371,8 @@ static int __fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst,
 		fl4.flowi4_proto = 0;
 		fl4.fl4_sport = 0;
 		fl4.fl4_dport = 0;
+	} else {
+		swap(fl4.fl4_sport, fl4.fl4_dport);
 	}
 
 	if (fib_lookup(net, &fl4, &res, 0))

-- 
2.20.1

On 6/21/21 9:17 AM, Wang Shanker wrote:

When doing source address validation, the flowi4 struct used for
fib_lookup should be in the reverse direction to the given skb.
fl4_dport and fl4_sport returned by fib4_rules_early_flow_dissect
should thus be swapped.

Fixes: 5a847a6 ("net/ipv4: Initialize proto and ports in flow struct")

I believe the hash should be 12 chars: 5a847a6e1477

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

2021年06月22日 09:23，David Ahern [off-list ref] 写道：

On 6/21/21 9:17 AM, Wang Shanker wrote:

quoted

When doing source address validation, the flowi4 struct used for
fib_lookup should be in the reverse direction to the given skb.
fl4_dport and fl4_sport returned by fib4_rules_early_flow_dissect
should thus be swapped.

Fixes: 5a847a6 ("net/ipv4: Initialize proto and ports in flow struct")

I believe the hash should be 12 chars: 5a847a6e1477

quoted

Signed-off-by: Miao Wang <redacted>
---
net/ipv4/fib_frontend.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index 84bb707bd88d..647bceab56c2 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c

@@ -371,6 +371,8 @@ static int __fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst,

		fl4.flowi4_proto = 0;
		fl4.fl4_sport = 0;
		fl4.fl4_dport = 0;
+	} else {
+		swap(fl4.fl4_sport, fl4.fl4_dport);
	}

	if (fib_lookup(net, &fl4, &res, 0))

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

Thanks for your suggestion. I wonder if I also CC this to 
stable?

On 6/21/21 8:39 PM, Miao Wang wrote:

Thanks for your suggestion. I wonder if I also CC this to 
stable?

nope. Fixes tag will take care of that.

When doing source address validation, the flowi4 struct used for
fib_lookup should be in the reverse direction to the given skb.
fl4_dport and fl4_sport returned by fib4_rules_early_flow_dissect
should thus be swapped.

Fixes: 5a847a6e1477 ("net/ipv4: Initialize proto and ports in flow struct")
Signed-off-by: Miao Wang <redacted>
Reviewed-by: David Ahern <dsahern@kernel.org>
---
 net/ipv4/fib_frontend.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index 84bb707bd88d..647bceab56c2 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c

@@ -371,6 +371,8 @@ static int __fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst,
 		fl4.flowi4_proto = 0;
 		fl4.fl4_sport = 0;
 		fl4.fl4_dport = 0;
+	} else {
+		swap(fl4.fl4_sport, fl4.fl4_dport);
 	}
 
 	if (fib_lookup(net, &fl4, &res, 0))

-- 
2.20.1

Hello:

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

On Tue, 22 Jun 2021 12:24:50 +0800 you wrote:

When doing source address validation, the flowi4 struct used for
fib_lookup should be in the reverse direction to the given skb.
fl4_dport and fl4_sport returned by fib4_rules_early_flow_dissect
should thus be swapped.

Fixes: 5a847a6e1477 ("net/ipv4: Initialize proto and ports in flow struct")
Signed-off-by: Miao Wang <redacted>
Reviewed-by: David Ahern <dsahern@kernel.org>

[...]

Here is the summary with links:
  - [v2] net/ipv4: swap flow ports when validating source
    https://git.kernel.org/netdev/net/c/c69f114d0989

You are awesome, thank you!
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