[PATCH 5.11 427/601] udp: never accept GSO_FRAGLIST packets

Greg Kroah-Hartman
2021-05-12T17:41:53Z

From: Paolo Abeni <pabeni@redhat.com>

[ Upstream commit 78352f73dc5047f3f744764cc45912498c52f3c9 ]

Currently the UDP protocol delivers GSO_FRAGLIST packets to
the sockets without the expected segmentation.

This change addresses the issue introducing and maintaining
a couple of new fields to explicitly accept SKB_GSO_UDP_L4
or GSO_FRAGLIST packets. Additionally updates udp_unexpected_gso()
accordingly.

UDP sockets enabling UDP_GRO stil keep accept_udp_fraglist
zeroed.

v1 -> v2:
- use 2 bits instead of a whole GSO bitmask (Willem)

Fixes: 9fd1ff5d2ac7 ("udp: Support UDP fraglist GRO/GSO.")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/linux/udp.h | 16 +++++++++++++---
net/ipv4/udp.c | 3 +++
2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/include/linux/udp.h b/include/linux/udp.h
index aa84597bdc33..ae58ff3b6b5b 100644
--- a/include/linux/udp.h
+++ b/include/linux/udp.h
@@ -51,7 +51,9 @@ struct udp_sock {
* different encapsulation layer set
* this
*/
- gro_enabled:1; /* Can accept GRO packets */
+ gro_enabled:1, /* Request GRO aggregation */
+ accept_udp_l4:1,
+ accept_udp_fraglist:1;
/*
* Following member retains the information to create a UDP header
* when the socket is uncorked.
@@ -131,8 +133,16 @@ static inline void udp_cmsg_recv(struct msghdr *msg, struct sock *sk,

static inline bool udp_unexpected_gso(struct sock *sk, struct sk_buff *skb)
{
- return !udp_sk(sk)->gro_enabled && skb_is_gso(skb) &&
- skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4;
+ if (!skb_is_gso(skb))
+ return false;
+
+ if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4 && !udp_sk(sk)->accept_udp_l4)
+ return true;
+
+ if (skb_shinfo(skb)->gso_type & SKB_GSO_FRAGLIST && !udp_sk(sk)->accept_udp_fraglist)
+ return true;
+
+ return false;
}

#define udp_portaddr_for_each_entry(__sk, list) \
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 9d2a1a247cec..a5d716f185f6 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -2659,9 +2659,12 @@ int udp_lib_setsockopt(struct sock *sk, int level, int optname,

case UDP_GRO:
lock_sock(sk);
+
+ /* when enabling GRO, accept the related GSO packet type */
if (valbool)
udp_tunnel_encap_enable(sk->sk_socket);
up->gro_enabled = valbool;
+ up->accept_udp_l4 = valbool;
release_sock(sk);
break;

--
2.30.2