xdp: Fix handling of devmap in generic XDP

Commit 67f29e07e131 ("bpf: devmap introduce dev_map_enqueue") changed
the return value type of __devmap_lookup_elem() from struct net_device *
to struct bpf_dtab_netdev * but forgot to modify generic XDP code
accordingly.

Thus generic XDP incorrectly used struct bpf_dtab_netdev where struct
net_device is expected, then skb->dev was set to invalid value.

v2:
- Fix compiler warning without CONFIG_BPF_SYSCALL.

Fixes: 67f29e07e131 ("bpf: devmap introduce dev_map_enqueue")
Signed-off-by: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

2 files changed, 28 insertions, 0 deletions

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 995c3b1e59bf..7df32a3200f7 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -488,12 +488,15 @@ void bpf_patch_call_args(struct bpf_insn *insn, u32 stack_depth);
 
 /* Map specifics */
 struct xdp_buff;
+struct sk_buff;
 
 struct bpf_dtab_netdev *__dev_map_lookup_elem(struct bpf_map *map, u32 key);
 void __dev_map_insert_ctx(struct bpf_map *map, u32 index);
 void __dev_map_flush(struct bpf_map *map);
 int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_buff *xdp,
 		    struct net_device *dev_rx);
+int dev_map_generic_redirect(struct bpf_dtab_netdev *dst, struct sk_buff *skb,
+			     struct bpf_prog *xdp_prog);
 
 struct bpf_cpu_map_entry *__cpu_map_lookup_elem(struct bpf_map *map, u32 key);
 void __cpu_map_insert_ctx(struct bpf_map *map, u32 index);
@@ -586,6 +589,15 @@ int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_buff *xdp,
 	return 0;
 }
 
+struct sk_buff;
+
+static inline int dev_map_generic_redirect(struct bpf_dtab_netdev *dst,
+					   struct sk_buff *skb,
+					   struct bpf_prog *xdp_prog)
+{
+	return 0;
+}
+
 static inline
 struct bpf_cpu_map_entry *__cpu_map_lookup_elem(struct bpf_map *map, u32 key)
 {
diff --git a/include/linux/filter.h b/include/linux/filter.h
index 108f9812e196..b615df57b7d5 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -19,6 +19,7 @@
 #include <linux/cryptohash.h>
 #include <linux/set_memory.h>
 #include <linux/kallsyms.h>
+#include <linux/if_vlan.h>
 
 #include <net/sch_generic.h>
 
@@ -802,6 +803,21 @@ static inline bool bpf_dump_raw_ok(void)
 struct bpf_prog *bpf_patch_insn_single(struct bpf_prog *prog, u32 off,
 				       const struct bpf_insn *patch, u32 len);
 
+static inline int __xdp_generic_ok_fwd_dev(struct sk_buff *skb,
+					   struct net_device *fwd)
+{
+	unsigned int len;
+
+	if (unlikely(!(fwd->flags & IFF_UP)))
+		return -ENETDOWN;
+
+	len = fwd->mtu + fwd->hard_header_len + VLAN_HLEN;
+	if (skb->len > len)
+		return -EMSGSIZE;
+
+	return 0;
+}
+
 /* The pair of xdp_do_redirect and xdp_do_flush_map MUST be called in the
  * same cpu context. Further for best results no more than a single map
  * for the do_redirect/do_flush pair should be used. This limitation is