linux-kernel - [PATCH 6.7 08/61] xfrm: Clear low order bits of ->flowi4_tos in decode

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Message-ID: <20240313163236.613880-9-sashal@kernel.org>
Date: Wed, 13 Mar 2024 12:31:43 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Guillaume Nault <gnault@...hat.com>,
	Steffen Klassert <steffen.klassert@...unet.com>,
	Sasha Levin <sashal@...nel.org>
Subject: [PATCH 6.7 08/61] xfrm: Clear low order bits of ->flowi4_tos in decode_session4().

From: Guillaume Nault <gnault@...hat.com>

[ Upstream commit 1982a2a02c9197436d4a8ea12f66bafab53f16a0 ]

Commit 23e7b1bfed61 ("xfrm: Don't accidentally set RTO_ONLINK in
decode_session4()") fixed a problem where decode_session4() could
erroneously set the RTO_ONLINK flag for IPv4 route lookups. This
problem was reintroduced when decode_session4() was modified to
use the flow dissector.

Fix this by clearing again the two low order bits of ->flowi4_tos.
Found by code inspection, compile tested only.

Fixes: 7a0207094f1b ("xfrm: policy: replace session decode with flow dissector")
Signed-off-by: Guillaume Nault <gnault@...hat.com>
Signed-off-by: Steffen Klassert <steffen.klassert@...unet.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 net/xfrm/xfrm_policy.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index c13dc3ef79107..e69d588caa0c6 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -3416,7 +3416,7 @@ decode_session4(const struct xfrm_flow_keys *flkeys, struct flowi *fl, bool reve
 	}
 
 	fl4->flowi4_proto = flkeys->basic.ip_proto;
-	fl4->flowi4_tos = flkeys->ip.tos;
+	fl4->flowi4_tos = flkeys->ip.tos & ~INET_ECN_MASK;
 }
 
 #if IS_ENABLED(CONFIG_IPV6)
-- 
2.43.0