[PATCH 6.8 084/336] net: gro: fix udp bad offset in socket lookup by adding {inner_}network_offset to napi_gro_cb

Greg Kroah-Hartman
2024-05-14T10:29:34Z

From: Richard Gobert <richardbgobert@gmail.com>

[ Upstream commit 5ef31ea5d053a8f493a772ebad3f3ce82c35d845 ]

Commits a602456 ("udp: Add GRO functions to UDP socket") and 57c67ff ("udp:
additional GRO support") introduce incorrect usage of {ip,ipv6}_hdr in the
complete phase of gro. The functions always return skb->network_header,
which in the case of encapsulated packets at the gro complete phase, is
always set to the innermost L3 of the packet. That means that calling
{ip,ipv6}_hdr for skbs which completed the GRO receive phase (both in
gro_list and *_gro_complete) when parsing an encapsulated packet's _outer_
L3/L4 may return an unexpected value.

This incorrect usage leads to a bug in GRO's UDP socket lookup.
udp{4,6}_lib_lookup_skb functions use ip_hdr/ipv6_hdr respectively. These
*_hdr functions return network_header which will point to the innermost L3,
resulting in the wrong offset being used in __udp{4,6}_lib_lookup with
encapsulated packets.

This patch adds network_offset and inner_network_offset to napi_gro_cb, and
makes sure both are set correctly.

To fix the issue, network_offsets union is used inside napi_gro_cb, in
which both the outer and the inner network offsets are saved.

Reproduction example:

Endpoint configuration example (fou + local address bind)

# ip fou add port 6666 ipproto 4
# ip link add name tun1 type ipip remote 2.2.2.1 local 2.2.2.2 encap fou encap-dport 5555 encap-sport 6666 mode ipip
# ip link set tun1 up
# ip a add 1.1.1.2/24 dev tun1

Netperf TCP_STREAM result on net-next before patch is applied:

net-next main, GRO enabled:
$ netperf -H 1.1.1.2 -t TCP_STREAM -l 5
Recv Send Send
Socket Socket Message Elapsed
Size Size Size Time Throughput
bytes bytes bytes secs. 10^6bits/sec

131072 16384 16384 5.28 2.37

net-next main, GRO disabled:
$ netperf -H 1.1.1.2 -t TCP_STREAM -l 5
Recv Send Send
Socket Socket Message Elapsed
Size Size Size Time Throughput
bytes bytes bytes secs. 10^6bits/sec

131072 16384 16384 5.01 2745.06

patch applied, GRO enabled:
$ netperf -H 1.1.1.2 -t TCP_STREAM -l 5
Recv Send Send
Socket Socket Message Elapsed
Size Size Size Time Throughput
bytes bytes bytes secs. 10^6bits/sec

131072 16384 16384 5.01 2877.38

Fixes: a6024562ffd7 ("udp: Add GRO functions to UDP socket")
Signed-off-by: Richard Gobert <richardbgobert@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/net/gro.h | 9 +++++++++
net/8021q/vlan_core.c | 2 ++
net/core/gro.c | 1 +
net/ipv4/af_inet.c | 1 +
net/ipv4/udp.c | 3 ++-
net/ipv4/udp_offload.c | 3 ++-
net/ipv6/ip6_offload.c | 1 +
net/ipv6/udp.c | 3 ++-
net/ipv6/udp_offload.c | 3 ++-
9 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/include/net/gro.h b/include/net/gro.h
index b435f0ddbf64f..62b006f3ed184 100644
--- a/include/net/gro.h
+++ b/include/net/gro.h
@@ -86,6 +86,15 @@ struct napi_gro_cb {

/* used to support CHECKSUM_COMPLETE for tunneling protocols */
__wsum csum;
+
+ /* L3 offsets */
+ union {
+ struct {
+ u16 network_offset;
+ u16 inner_network_offset;
+ };
+ u16 network_offsets[2];
+ };
};

#define NAPI_GRO_CB(skb) ((struct napi_gro_cb *)(skb)->cb)
diff --git a/net/8021q/vlan_core.c b/net/8021q/vlan_core.c
index f001582345052..9404dd551dfd2 100644
--- a/net/8021q/vlan_core.c
+++ b/net/8021q/vlan_core.c
@@ -478,6 +478,8 @@ static struct sk_buff *vlan_gro_receive(struct list_head *head,
if (unlikely(!vhdr))
goto out;

+ NAPI_GRO_CB(skb)->network_offsets[NAPI_GRO_CB(skb)->encap_mark] = hlen;
+
type = vhdr->h_vlan_encapsulated_proto;

ptype = gro_find_receive_by_type(type);
diff --git a/net/core/gro.c b/net/core/gro.c
index cefddf65f7db0..31e40f25fdf10 100644
--- a/net/core/gro.c
+++ b/net/core/gro.c
@@ -373,6 +373,7 @@ static inline void skb_gro_reset_offset(struct sk_buff *skb, u32 nhoff)
const struct skb_shared_info *pinfo = skb_shinfo(skb);
const skb_frag_t *frag0 = &pinfo->frags[0];

+ NAPI_GRO_CB(skb)->network_offset = 0;
NAPI_GRO_CB(skb)->data_offset = 0;
NAPI_GRO_CB(skb)->frag0 = NULL;
NAPI_GRO_CB(skb)->frag0_len = 0;
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index a5a820ee20266..ce5c26cf1e2e8 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -1571,6 +1571,7 @@ struct sk_buff *inet_gro_receive(struct list_head *head, struct sk_buff *skb)
/* The above will be needed by the transport layer if there is one
* immediately following this IP hdr.
*/
+ NAPI_GRO_CB(skb)->inner_network_offset = off;

/* Note : No need to call skb_gro_postpull_rcsum() here,
* as we already checked checksum over ipv4 header was 0
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 40282a34180ca..9120694359af4 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -534,7 +534,8 @@ static inline struct sock *__udp4_lib_lookup_skb(struct sk_buff *skb,
struct sock *udp4_lib_lookup_skb(const struct sk_buff *skb,
__be16 sport, __be16 dport)
{
- const struct iphdr *iph = ip_hdr(skb);
+ const u16 offset = NAPI_GRO_CB(skb)->network_offsets[skb->encapsulation];
+ const struct iphdr *iph = (struct iphdr *)(skb->data + offset);
struct net *net = dev_net(skb->dev);
int iif, sdif;

diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
index c3d67423ae189..889d4926fc0c1 100644
--- a/net/ipv4/udp_offload.c
+++ b/net/ipv4/udp_offload.c
@@ -718,7 +718,8 @@ EXPORT_SYMBOL(udp_gro_complete);

INDIRECT_CALLABLE_SCOPE int udp4_gro_complete(struct sk_buff *skb, int nhoff)
{
- const struct iphdr *iph = ip_hdr(skb);
+ const u16 offset = NAPI_GRO_CB(skb)->network_offsets[skb->encapsulation];
+ const struct iphdr *iph = (struct iphdr *)(skb->data + offset);
struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);

/* do fraglist only if there is no outer UDP encap (or we already processed it) */
diff --git a/net/ipv6/ip6_offload.c b/net/ipv6/ip6_offload.c
index cca64c7809bee..19ae2d4cd2021 100644
--- a/net/ipv6/ip6_offload.c
+++ b/net/ipv6/ip6_offload.c
@@ -237,6 +237,7 @@ INDIRECT_CALLABLE_SCOPE struct sk_buff *ipv6_gro_receive(struct list_head *head,
goto out;

skb_set_network_header(skb, off);
+ NAPI_GRO_CB(skb)->inner_network_offset = off;

flush += ntohs(iph->payload_len) != skb->len - hlen;

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 8c14c4cc82ff7..785b2d076a6b3 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -275,7 +275,8 @@ static struct sock *__udp6_lib_lookup_skb(struct sk_buff *skb,
struct sock *udp6_lib_lookup_skb(const struct sk_buff *skb,
__be16 sport, __be16 dport)
{
- const struct ipv6hdr *iph = ipv6_hdr(skb);
+ const u16 offset = NAPI_GRO_CB(skb)->network_offsets[skb->encapsulation];
+ const struct ipv6hdr *iph = (struct ipv6hdr *)(skb->data + offset);
struct net *net = dev_net(skb->dev);
int iif, sdif;

diff --git a/net/ipv6/udp_offload.c b/net/ipv6/udp_offload.c
index 626d7b362dc7b..639a4b506f9b5 100644
--- a/net/ipv6/udp_offload.c
+++ b/net/ipv6/udp_offload.c
@@ -164,7 +164,8 @@ struct sk_buff *udp6_gro_receive(struct list_head *head, struct sk_buff *skb)

INDIRECT_CALLABLE_SCOPE int udp6_gro_complete(struct sk_buff *skb, int nhoff)
{
- const struct ipv6hdr *ipv6h = ipv6_hdr(skb);
+ const u16 offset = NAPI_GRO_CB(skb)->network_offsets[skb->encapsulation];
+ const struct ipv6hdr *ipv6h = (struct ipv6hdr *)(skb->data + offset);
struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);

/* do fraglist only if there is no outer UDP encap (or we already processed it) */
--
2.43.0