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 5bafcfe18be61f497e4ae36585e87ab57d75e9c9..f86f9396f727beb840a59a50cca0b0f981982103 100644 (file)
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -2972,6 +2972,21 @@ 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 1d107241b9018798f32997f813d344561ef6fae6..5d0f8f40b8d16b679d0d3b556ebf412201ea19a6 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 c54676998eb60b7a47ee9defe8d97aec643dd1e1..801404f7d657465c8a5e873a9578a122f2b2e940 100644 (file)
--- a/net/ipv4/xfrm4_input.c
+++ b/net/ipv4/xfrm4_input.c
@@ -63,7 +63,11 @@ 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 6e36e5047fbab6bd2a4236006bab5efa546d6850..4e6dcefd635c8bd71f6ac597b05539569cfe1792 100644 (file)
--- a/net/ipv6/xfrm6_input.c
+++ b/net/ipv6/xfrm6_input.c
@@ -58,7 +58,11 @@ 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 bd4ce21d76d7551d8f0a4a11f4b75705a7f634c5..b2f7af63b7daeb31762d1be3ddfd706856cf1c80 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 -