xfrm: Preserve vlan tags for transport mode software GRO

[ Upstream commit 58fbfecab965014b6e3cc956a76b4a96265a1add ]

The software GRO path for esp transport mode uses skb_mac_header_rebuild
prior to re-injecting the packet via the xfrm_napi_dev.  This only
copies skb->mac_len bytes of header which may not be sufficient if the
packet contains 802.1Q tags or other VLAN tags.  Worse copying only the
initial header will leave a packet marked as being VLAN tagged but
without the corresponding tag leading to mangling when it is later
untagged.

The VLAN tags are important when receiving the decrypted esp transport
mode packet after GRO processing to ensure it is received on the correct
interface.

Therefore record the full mac header length in xfrm*_transport_input for
later use in corresponding xfrm*_transport_finish to copy the entire mac
header when rebuilding the mac header for GRO.  The skb->data pointer is
left pointing skb->mac_header bytes after the start of the mac header as
is expected by the network stack and network and transport header
offsets reset to this location.

Fixes: 7785bba299a8 ("esp: Add a software GRO codepath")
Signed-off-by: Paul Davey <paul.davey@alliedtelesis.co.nz>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 7d54808a1e8f9736522ccff0da8f42d9bdf864ce..5f11f98733419030d2400657c28147938f783517 100644 (file)
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -2962,6 +2962,21 @@ static inline void skb_mac_header_rebuild(struct sk_buff *skb)
        }
 }
 
+/* Move the full mac header up to current network_header.
+ * Leaves skb->data pointing at offset skb->mac_len into the mac_header.
+ * Must be provided the complete mac header length.
+ */
+static inline void skb_mac_header_rebuild_full(struct sk_buff *skb, u32 full_mac_len)
+{
+       if (skb_mac_header_was_set(skb)) {
+               const unsigned char *old_mac = skb_mac_header(skb);
+
+               skb_set_mac_header(skb, -full_mac_len);
+               memmove(skb_mac_header(skb), old_mac, full_mac_len);
+               __skb_push(skb, full_mac_len - skb->mac_len);
+       }
+}
+
 static inline int skb_checksum_start_offset(const struct sk_buff *skb)
 {
        return skb->csum_start - skb_headroom(skb);

diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index 363c7d5105542ec7f43f91e5071b877314584bc5..a3fd2cfed5e33e62e257b1534bba2858508c21f8 100644 (file)
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -1047,6 +1047,9 @@ struct xfrm_offload {
 #define CRYPTO_INVALID_PACKET_SYNTAX           64
 #define CRYPTO_INVALID_PROTOCOL                        128
 
+       /* Used to keep whole l2 header for transport mode GRO */
+       __u32                   orig_mac_len;
+
        __u8                    proto;
        __u8                    inner_ipproto;
 };

diff --git a/net/ipv4/xfrm4_input.c b/net/ipv4/xfrm4_input.c
index 183f6dc3724293f60c05aac630347405344c5010..f6e90ba50b639de89ef2853382269cbefc769720 100644 (file)
--- a/net/ipv4/xfrm4_input.c
+++ b/net/ipv4/xfrm4_input.c
@@ -61,7 +61,11 @@ int xfrm4_transport_finish(struct sk_buff *skb, int async)
        ip_send_check(iph);
 
        if (xo && (xo->flags & XFRM_GRO)) {
-               skb_mac_header_rebuild(skb);
+               /* The full l2 header needs to be preserved so that re-injecting the packet at l2
+                * works correctly in the presence of vlan tags.
+                */
+               skb_mac_header_rebuild_full(skb, xo->orig_mac_len);
+               skb_reset_network_header(skb);
                skb_reset_transport_header(skb);
                return 0;
        }

diff --git a/net/ipv6/xfrm6_input.c b/net/ipv6/xfrm6_input.c
index 4156387248e40e15b0dd10ccfa89cee5dd7e7534..8432b50d9ce4ca4027fcb969cd8769e94d86e05f 100644 (file)
--- a/net/ipv6/xfrm6_input.c
+++ b/net/ipv6/xfrm6_input.c
@@ -56,7 +56,11 @@ int xfrm6_transport_finish(struct sk_buff *skb, int async)
        skb_postpush_rcsum(skb, skb_network_header(skb), nhlen);
 
        if (xo && (xo->flags & XFRM_GRO)) {
-               skb_mac_header_rebuild(skb);
+               /* The full l2 header needs to be preserved so that re-injecting the packet at l2
+                * works correctly in the presence of vlan tags.
+                */
+               skb_mac_header_rebuild_full(skb, xo->orig_mac_len);
+               skb_reset_network_header(skb);
                skb_reset_transport_header(skb);
                return 0;
        }

diff --git a/net/xfrm/xfrm_input.c b/net/xfrm/xfrm_input.c
index d5ee96789d4bf3ba3ec2869edeeea5d91a92d677..0c08bac3ed269d53e43654db57e8dd0a32774d51 100644 (file)
--- a/net/xfrm/xfrm_input.c
+++ b/net/xfrm/xfrm_input.c
@@ -388,11 +388,15 @@ static int xfrm_prepare_input(struct xfrm_state *x, struct sk_buff *skb)
  */
 static int xfrm4_transport_input(struct xfrm_state *x, struct sk_buff *skb)
 {
+       struct xfrm_offload *xo = xfrm_offload(skb);
        int ihl = skb->data - skb_transport_header(skb);
 
        if (skb->transport_header != skb->network_header) {
                memmove(skb_transport_header(skb),
                        skb_network_header(skb), ihl);
+               if (xo)
+                       xo->orig_mac_len =
+                               skb_mac_header_was_set(skb) ? skb_mac_header_len(skb) : 0;
                skb->network_header = skb->transport_header;
        }
        ip_hdr(skb)->tot_len = htons(skb->len + ihl);
@@ -403,11 +407,15 @@ static int xfrm4_transport_input(struct xfrm_state *x, struct sk_buff *skb)
 static int xfrm6_transport_input(struct xfrm_state *x, struct sk_buff *skb)
 {
 #if IS_ENABLED(CONFIG_IPV6)
+       struct xfrm_offload *xo = xfrm_offload(skb);
        int ihl = skb->data - skb_transport_header(skb);
 
        if (skb->transport_header != skb->network_header) {
                memmove(skb_transport_header(skb),
                        skb_network_header(skb), ihl);
+               if (xo)
+                       xo->orig_mac_len =
+                               skb_mac_header_was_set(skb) ? skb_mac_header_len(skb) : 0;
                skb->network_header = skb->transport_header;
        }
        ipv6_hdr(skb)->payload_len = htons(skb->len + ihl -