[PATCH 4.14 17/45] xfrm: Dont accidentally set RTO_ONLINK in decode_session4()

Greg Kroah-Hartman
2022-02-21T08:56:42Z

From: Guillaume Nault <gnault@redhat.com>

commit 23e7b1bfed61e301853b5e35472820d919498278 upstream.

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>
[sudip: manually backport to previous location]
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/ipv4/xfrm4_policy.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/net/ipv4/xfrm4_policy.c
+++ b/net/ipv4/xfrm4_policy.c
@@ -17,6 +17,7 @@
#include <net/xfrm.h>
#include <net/ip.h>
#include <net/l3mdev.h>
+#include <net/inet_ecn.h>

static struct dst_entry *__xfrm4_dst_lookup(struct net *net, struct flowi4 *fl4,
int tos, int oif,
@@ -126,7 +127,7 @@ _decode_session4(struct sk_buff *skb, st
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) {