The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 23e7b1bfed61e301853b5e35472820d919498278 Mon Sep 17 00:00:00 2001 From: Guillaume Nault gnault@redhat.com Date: Mon, 10 Jan 2022 14:43:06 +0100 Subject: [PATCH] xfrm: Don't accidentally set RTO_ONLINK in decode_session4()

Similar to commit 94e2238969e8 ("xfrm4: strip ECN bits from tos field"), clear the ECN bits from iph->tos when setting ->flowi4_tos. This ensures that the last bit of ->flowi4_tos is cleared, so ip_route_output_key_hash() isn't going to restrict the scope of the route lookup.

Use ~INET_ECN_MASK instead of IPTOS_RT_MASK, because we have no reason to clear the high order bits.

Found by code inspection, compile tested only.

Fixes: 4da3089f2b58 ("[IPSEC]: Use TOS when doing tunnel lookups") Signed-off-by: Guillaume Nault gnault@redhat.com Signed-off-by: Jakub Kicinski kuba@kernel.org

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c index dccb8f3318ef..04d1ce9b510f 100644 --- a/net/xfrm/xfrm_policy.c +++ b/net/xfrm/xfrm_policy.c @@ -31,6 +31,7 @@ #include <linux/if_tunnel.h> #include <net/dst.h> #include <net/flow.h> +#include <net/inet_ecn.h> #include <net/xfrm.h> #include <net/ip.h> #include <net/gre.h> @@ -3295,7 +3296,7 @@ decode_session4(struct sk_buff *skb, struct flowi *fl, bool reverse) fl4->flowi4_proto = iph->protocol; fl4->daddr = reverse ? iph->saddr : iph->daddr; fl4->saddr = reverse ? iph->daddr : iph->saddr; - fl4->flowi4_tos = iph->tos; + fl4->flowi4_tos = iph->tos & ~INET_ECN_MASK;

if (!ip_is_fragment(iph)) { switch (iph->protocol) {