This is a note to let you know that I've just added the patch titled
ipv4: Fix incorrect source address in Record Route option
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ipv4-fix-incorrect-source-address-in-record-route-op.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 5fc748ea1060a3e1e3bef541f1cf8aa882aaee2c
Author: Ido Schimmel <idosch@xxxxxxxxxx>
Date: Thu Jul 18 15:34:07 2024 +0300
ipv4: Fix incorrect source address in Record Route option
[ Upstream commit cc73bbab4b1fb8a4f53a24645871dafa5f81266a ]
The Record Route IP option records the addresses of the routers that
routed the packet. In the case of forwarded packets, the kernel performs
a route lookup via fib_lookup() and fills in the preferred source
address of the matched route.
The lookup is performed with the DS field of the forwarded packet, but
using the RT_TOS() macro which only masks one of the two ECN bits. If
the packet is ECT(0) or CE, the matched route might be different than
the route via which the packet was forwarded as the input path masks
both of the ECN bits, resulting in the wrong address being filled in the
Record Route option.
Fix by masking both of the ECN bits.
Fixes: 8e36360ae876 ("ipv4: Remove route key identity dependencies in ip_rt_get_source().")
Signed-off-by: Ido Schimmel <idosch@xxxxxxxxxx>
Reviewed-by: Guillaume Nault <gnault@xxxxxxxxxx>
Link: https://patch.msgid.link/20240718123407.434778-1-idosch@xxxxxxxxxx
Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 2672b71e662d3..f3e77b1e1d4b9 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1283,7 +1283,7 @@ void ip_rt_get_source(u8 *addr, struct sk_buff *skb, struct rtable *rt)
struct flowi4 fl4 = {
.daddr = iph->daddr,
.saddr = iph->saddr,
- .flowi4_tos = RT_TOS(iph->tos),
+ .flowi4_tos = iph->tos & IPTOS_RT_MASK,
.flowi4_oif = rt->dst.dev->ifindex,
.flowi4_iif = skb->dev->ifindex,
.flowi4_mark = skb->mark,
