This is a note to let you know that I've just added the patch titled
ipv4: Mask upper DSCP bits and ECN bits in NETLINK_FIB_LOOKUP family
to the 5.10-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-mask-upper-dscp-bits-and-ecn-bits-in-netlink_fi.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit f27de3a68d68c5e1ea5336f8b4b16af87774636d
Author: Ido Schimmel <idosch@xxxxxxxxxx>
Date: Wed Aug 14 15:52:22 2024 +0300
ipv4: Mask upper DSCP bits and ECN bits in NETLINK_FIB_LOOKUP family
[ Upstream commit 8fed54758cd248cd311a2b5c1e180abef1866237 ]
The NETLINK_FIB_LOOKUP netlink family can be used to perform a FIB
lookup according to user provided parameters and communicate the result
back to user space.
However, unlike other users of the FIB lookup API, the upper DSCP bits
and the ECN bits of the DS field are not masked, which can result in the
wrong result being returned.
Solve this by masking the upper DSCP bits and the ECN bits using
IPTOS_RT_MASK.
The structure that communicates the request and the response is not
exported to user space, so it is unlikely that this netlink family is
actually in use [1].
[1] https://lore.kernel.org/netdev/ZpqpB8vJU%2FQ6LSqa@debian/
Signed-off-by: Ido Schimmel <idosch@xxxxxxxxxx>
Reviewed-by: Guillaume Nault <gnault@xxxxxxxxxx>
Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index 41f890bf9d4c4..0394146f813c5 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -1334,7 +1334,7 @@ static void nl_fib_lookup(struct net *net, struct fib_result_nl *frn)
struct flowi4 fl4 = {
.flowi4_mark = frn->fl_mark,
.daddr = frn->fl_addr,
- .flowi4_tos = frn->fl_tos,
+ .flowi4_tos = frn->fl_tos & IPTOS_RT_MASK,
.flowi4_scope = frn->fl_scope,
};
struct fib_table *tb;
