[PATCH net-next 12/13] nfp: prepare metadata handling for xdp_adjust_head()

[Jakub Kicinski]

XDP may require us to move metadata to make room for pushing
headers.  Track meta data location with a pointer and pass
it explicitly to functions.

While at it validate that meta_len from the descriptor is not
bogus.

Signed-off-by: Jakub Kicinski <jakub.kicin...@netronome.com>
---
 .../net/ethernet/netronome/nfp/nfp_net_common.c    | 28 +++++++++++++++-------
 1 file changed, 19 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ethernet/netronome/nfp/nfp_net_common.c 
b/drivers/net/ethernet/netronome/nfp/nfp_net_common.c
index 0e4fa6802733..fe7c3f6d820d 100644
--- a/drivers/net/ethernet/netronome/nfp/nfp_net_common.c
+++ b/drivers/net/ethernet/netronome/nfp/nfp_net_common.c
@@ -1385,24 +1385,21 @@ static void nfp_net_set_hash(struct net_device *netdev, 
struct sk_buff *skb,
 
 static void
 nfp_net_set_hash_desc(struct net_device *netdev, struct sk_buff *skb,
-                     struct nfp_net_rx_desc *rxd)
+                     void *data, struct nfp_net_rx_desc *rxd)
 {
-       struct nfp_net_rx_hash *rx_hash;
+       struct nfp_net_rx_hash *rx_hash = data;
 
        if (!(rxd->rxd.flags & PCIE_DESC_RX_RSS))
                return;
 
-       rx_hash = (struct nfp_net_rx_hash *)(skb->data - sizeof(*rx_hash));
-
        nfp_net_set_hash(netdev, skb, get_unaligned_be32(&rx_hash->hash_type),
                         &rx_hash->hash);
 }
 
 static void *
 nfp_net_parse_meta(struct net_device *netdev, struct sk_buff *skb,
-                  int meta_len)
+                  void *data, int meta_len)
 {
-       u8 *data = skb->data - meta_len;
        u32 meta_info;
 
        meta_info = get_unaligned_be32(data);
@@ -1546,6 +1543,7 @@ static int nfp_net_rx(struct nfp_net_rx_ring *rx_ring, 
int budget)
                struct nfp_net_rx_desc *rxd;
                dma_addr_t new_dma_addr;
                void *new_frag;
+               u8 *meta;
 
                idx = rx_ring->rd_p & (rx_ring->cnt - 1);
 
@@ -1589,6 +1587,17 @@ static int nfp_net_rx(struct nfp_net_rx_ring *rx_ring, 
int budget)
                r_vec->rx_bytes += pkt_len;
                u64_stats_update_end(&r_vec->rx_sync);
 
+               /* Pointer to start of metadata */
+               meta = rxbuf->frag + data_off - meta_len;
+
+               if (unlikely(meta_len > NFP_NET_MAX_PREPEND ||
+                            (dp->rx_offset && meta_len > dp->rx_offset))) {
+                       nn_dp_warn(dp, "oversized RX packet metadata %u\n",
+                                  meta_len);
+                       nfp_net_rx_drop(r_vec, rx_ring, rxbuf, NULL);
+                       continue;
+               }
+
                if (xdp_prog && !(rxd->rxd.flags & PCIE_DESC_RX_BPF &&
                                  dp->bpf_offload_xdp)) {
                        unsigned int dma_off;
@@ -1641,12 +1650,13 @@ static int nfp_net_rx(struct nfp_net_rx_ring *rx_ring, 
int budget)
                skb_put(skb, pkt_len);
 
                if (!dp->chained_metadata_format) {
-                       nfp_net_set_hash_desc(dp->netdev, skb, rxd);
+                       nfp_net_set_hash_desc(dp->netdev, skb, meta, rxd);
                } else if (meta_len) {
                        void *end;
 
-                       end = nfp_net_parse_meta(dp->netdev, skb, meta_len);
-                       if (unlikely(end != skb->data)) {
+                       end = nfp_net_parse_meta(dp->netdev, skb, meta,
+                                                meta_len);
+                       if (unlikely(end != meta + meta_len)) {
                                nn_dp_warn(dp, "invalid RX packet metadata\n");
                                nfp_net_rx_drop(r_vec, rx_ring, NULL, skb);
                                continue;
-- 
2.11.0